Anterior Segment Parameter Analysis After SMILE Surgery and Its Impact on the Calculation of Effective Intraocular Lens Position

Anterior Segment Parameter Analysis After SMILE Surgery and Its Impact on the Calculation of Effective Intraocular Lens Position | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Anterior Segment Parameter Analysis After SMILE Surgery and Its Impact on the Calculation of Effective Intraocular Lens Position Congcong Sun, Xiujin Guo, Bing Zhang, Tao Jin, Chunmei Tong This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8639765/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Objective: This study aims to investigate post-SMILE alterations in corneal refractive power, axial length, and anterior chamber depth, as well as examining the relationship between changes in anterior chamber depth and corneal ablation depth. By utilizing both Pentacam and IOL Master devices, researchers will input measurement data into the Holladay 1 and Haigis formulas to calculate and compare Estimated Lens Position (ELP) values. The objective is to provide accurate anterior segment parameters for patients undergoing corneal refractive surgery, thereby enhancing the precision of intraocular lens calculations. Methodology: A large hospital of Hebei Medical University made a prospective study. The subjects are a group of people who have undergone SMILE surgery in the second half of 2020.Clinical examinations were made before operation and 1st and 3rd Month Post-Surgery, respectively, and the results of naked eye vision, diopter, intraocular pressure, slit lamp microscope examination, as well as data of Pentacam (corneal diopter, central corneal thickness, anterior chamber depth) and IOL-Master (corneal power, aqueous depth, axial length) were recorded. In addition, supplementary parameters such as corneal thickness and cutting depth were recorded. We used paired t test to compare the changes of corneal diopter, anterior chamber dimensions and axial measurement measured by Pentacam and IOL-Master before and after SMILE operation. The same method is also used to compare the estimated lens position (ELP) calculated from IOL-Master and Pentacam data according to Holladay I and Haigis formula, and p-value below 0.05 denotes significance. In addition, Pearson correlation coefficient was used to analyze the relationship between the changes of anterior chamber depth measured by IOL-Master and Pentacam before and after SMILE operation and the corneal ablation depth. Results: At postoperative months 1 and 3, the measurement results of ALand（AL*） were notably dissimilar to preoperative measures (P<0.05). Whether measured by IOLMaster or Pentacam equipment, there were significant differences between ICACD and ECCD at 1 month and 3 months after operation (P<0.05). It should be noted that the ICACD value measured by IOLMaster is larger than that measured by Pentacam before and after operation. Similarly, the values of Km, SimK and TCRP were significantly different from those before operation at 1 month and 3 months after operation (P<0.05), and the values of Km were always higher than that of SimK, while that of SimK was higher than that of TCRP before and after operation. When the effective lens position (ELP) was calculated by Holladay I and Haigis formula using the data of IOLMaster or Pentacam, the results of Holladay I(ELP) and Haigis(ELP) were significantly different at 1 and 3 months post-surgery (P < 0.05). In addition, the estimated lens position (ELP) calculated by IOLMaster Haigis data is higher than that measured by Pentacam, and this trend is the same as that of Holladay I (ELP) calculated by IOLMaster before and after operation. Moreover, the ELP value measured by the same examination equipment always shows that the result of Haigis (ELP) after operation is higher than that measured by Holladay I (ELP). Conclusion: 1.After the SMILE operation, we found that the axial length of the eyes became shorter and the anterior chamber depth became shallower. Although the shortening of axial length is related to cutting off a part of corneas, the shallowing of anterior chamber depth has nothing to do with how many corneas are cut off during surgery.2.After SMILE operation, the axial length can be measured accurately with IOL-Master instrument, among which TCRP method is the most reliable, followed by SimK and Km. When measuring anterior chamber depth, Pentacam and IOL-Master are very reliable. 3.He shallowness of anterior chamber depth after SMILE surgery will lead to the doctor's error in estimating the effective lens position, so the calculated intrinsic lens degree will be inaccurate, and finally the vision correction after cataract surgery will be biased. effective lens position corneal ablation depth Haigis formula HolladayI formula axial length Preface Refractive error is the most common eye problem when we see a doctor. Although there is no particularly effective medicine to cure it, surgery is the most important way at present. Small incidence lenticule extraction (SMILE for short) is a new corneal refractive surgery technique, which is particularly popular now, and it is liked by both surgeons and ophthalmologists. It is so popular because it has several main advantages: no corneal flap, less trauma, safety, effectiveness and reliability, so it has become the first choice in vision correction surgery [1]. Up to now, about 2 million SMILE operations have been performed in the world, accounting for more than 10% of all corneal refractive operations [1], and this number is increasing rapidly. However, as time goes by, people who have undergone SMILE surgery may eventually need to undergo cataract surgery and implant an intraocular lens (IOL) because of the side effects of surgery or because they are naturally suffering from cataracts when they are old.The main problem is how to choose the most suitable intraocular lens (IOL) power for more and more patients undergoing cataract surgery, so that their postoperative vision is normal or close to normal. The key to success lies in accurate measurement of eye data before operation. However, the corneal curvature will change in people who have undergone SMILE surgery, which often leads to inaccurate calculation of IOL power. There are three main reasons: 1) the measurement of corneal refractive power is inaccurate, 2) the measurement of axial length is incorrect, and 3) the method of calculating IOL power is flawed [2]. This research aims to discern variations in effective lens positioning assessment using the Haigis and Holladay-I formulas.The accuracy of our intraocular lens power calculation hinges primarily on three crucial elements: the corneal refractive strength, the axial length of the eye (AL), and the measurement of the anterior chamber depth (ACD).A big problem now is that the measurement accuracy of the commonly used standard ultrasonic biometric instruments is often not accurate enough, especially for patients who have undergone laser surgery for myopia. This is mainly because of their shortcomings in design, such as the need for contact eye measurement, unstable results and low accuracy.Pentacam is an advanced medical tool, which uses Seheimpflug imaging technology to comprehensively image and evaluate the front of the eye. Cutting-edge technology allows this instrument to directly assess the refractive power of both the front and back layers of the cornea while simultaneously forecasting shifts in the eye's focusing capability with remarkable precision.On the other hand, IOLMaster is a non-contact, minimally invasive eye measurement device, which works based on partially coherent interferometry. It uses 780 nm focused infrared diode laser with short coherent wavelength as light source. The IOLMaster has earned its reputation as a gold standard in ophthalmology, boasting impressive resolution and precision, while remaining remarkably user-friendly. Its patient-friendly design ensures minimal discomfort during examinations, ultimately enhancing the reliability of intraocular lens power calculations following vision correction procedures. The current investigation employed both the IOL-Master and Pentacam technologies to assess post-SMILE surgical alterations in corneal refractive power, axial length, and anterior chamber depth. Additionally, this research examined the correlation between variations in anterior chamber depth and corneal ablation depth. By feeding Pentacam and IOL-Master data into both the Holladay 1 and Haigis formulas, the study compared the predicted effective lens position (ELP) values. The overarching goal here is to furnish more precise anterior segment measurements for individuals undergoing corneal refractive surgery, thereby enhancing the accuracy of intraocular lens power calculations. Materials and Methods 1.Design: A prospective study was conducted. 2.Participants and Inclusion Criteria 2.1 Study Participants Between September and October 2020, a total of 35 patients (69 eyes) with nearsightedness underwent the SMILE procedure at the Second Hospital of Hebei Medical University's Eye Center. This group consisted of 19 men (37 eyes) and 16 women (32 eyes), ranging in age from 18 to 36 years. Every patient achieved perfect 20/20 vision or better following their surgery. Medical evaluations were conducted before the operation as well as at one-month and three-month follow-up appointments. 2.2: Inclusion Criteria ① Must be in good health, Unaffected by severe autoimmune disorders like systemic lupus or MS, and devoid of systemic connective tissue disorders or keloid tendencies. ② Must be at least 18 years old, with a strong desire and requirement for vision correction, and in good mental health. ③ Should not have active eye inflammation, cataracts, retinal detachment, keratoconus, severe dry eye, glaucoma, subretinal hemorrhage, or significant ocular adnexal lesions. The tear film function test must not indicate severe dry eye. The cornea was transparent, with no significant opacities or spots. Soft contact lenses must be halted for over 2 weeks preoperatively.Discontinue wearing rigid contact lenses for more than a month. Orthokeratology lenses must be removed for at least 3 months. Postoperative follow-up must be at least six months. Myopia spectacle power should be no greater than -6.00D, and astigmatism no more than -0.50D. The remaining corneal stromal bed thickness must be at least 280μm after surgery. Candidates must show a stable diopter in the past 24 months. Before the SMILE operation, the patients understood the specific details of the procedure and its possible risks. be completed without any obvious problems during and after the operation. 3.Preoperative Preparations 3.1 Informed Consent Before the SMILE operation, the patients understood the specific details of the procedure and its possible risks. They must then complete and sign the consent form and the surgical approval document. 3.2 Visual Acuity and Refractive Testing Vision: We use a standard eye chart before and after the operation to check the patient's vision without glasses. Optometry: We performed automated optometry using a digital instrument. When preparing, give the patient 1 drop of tropicamide eye drops every 5 minutes for a total of 6 drops. The patient rested for 30 minutes with his eyes closed, and the degree was measured while his pupils remained dilated. During the preoperative consultation, we also performed subjective optometry and carefully recorded all results. 3.3 Anterior Segment Examination We carefully examined the conjunctiva,cornea, anterior segment, iris, pupil, and lens in sequence with a slit lamp microscope. 3.4 Fundus Examination After using tropicamide eye drops to enlarge the pupil, we carefully examined the fundus with a lens or a three-sided mirror mounted on a slit lamp. We examined the retina carefully for any abnormal signs, such as degeneration, tears, or bleeding. If treatment is needed, laser therapy may be used to solve the retina's problem. 3.5 Intraocular Pressure Measurement We measured intraocular pressure three times with a non-contact tonometer, and the final recorded value is the average of these three measurements. 3.6 Corneal Topography Examination Methods: Pentacam HR anterior segment analyzer was used for evaluation. Before the test, input the patient's information into the equipment. Guide the participants to place their chin on the instrument's bracket and their forehead against the bandage. Then let them blink a few more times to evenly distribute the tear film, then open their eyes completely and stare at the flashing red light. The operator uses the joystick to adjust the focal length according to the on-screen prompts, and the equipment automatically takes pictures when the focal length is optimal. Data collection is performed in a dark environment to maintain the patient's pupil in a natural state. Per the manufacturer's guidelines, scan outcomes only qualify when the image quality indicator registers as "OK." Every subject underwent three consecutive scanning sessions, all conducted by a single, highly trained technician to ensure consistency throughout the process. 3.7 Examination by IOL Master The working principle of IOLMaster is to project six evenly distributed light spots to the cornea to form a circle with a diameter of 2.3 mm. By analyzing the reflection of these light spots, the instrument can measure the distance between them. By applying the Gullstrand formula, k = (n-1)/r, this instrument is able to determine the mean curvature of the front portion of the cornea. Given that the curvature relationship between the back and front surfaces stands at 82% and utilizing the conventional refractive index value of 1.3375, the cornea's focusing strength can be accurately calculated.When measuring, the patient needs to rest his chin and forehead on the designated support and stare at the target point inside the instrument. IOLMaster will record the values of K1 and K2, and the final result (Km) is the average of three consecutive readings; the calculation formula is Km = (K1 + K2)/2. The main output from IOLMaster is the Km value. 4.Surgical methods All the surgical steps were completed by an experienced surgeon. To reduce the risk of infection, we asked patients to use gatifloxacin eye drops 4 times daily for 3 days before the operation. This antibiotic regimen will continue after the operation. For local anesthesia, we dropped a drop of 0.4% procaine hydrochloride into the conjunctival sac during the operation. Then, the conjunctival sac was washed with warm saline, and the skin around the eyes was cleaned with a cotton swab soaked in 0.5% povidone-iodine. Disinfection is centered on the drooping eyelid, extending from the hairline to the line connecting the nasolabial groove and the earlobe, and crossing the nasal midline inward. Disinfectant was used three times in all. Employing the VisuMax femtosecond laser system (Carl Zeiss, Germany), the corneal flap and lens were crafted post-preparation.The laser parameters are as follows: pulse energy 140nJ, pulse frequency 500kHz, corneal flap thickness 120um, flap diameter 7 mm, lens diameter 6-6.5 mm, expected residual matrix bed thickness 10-15um, lateral incision 2 mm, and lens and lateral incision angle 90 degrees. The patient lies flat on the operating table, his head should be straightened, his forehead and chin should be level, and the midline of his face should be aligned with the center. After local anesthesia, the doctor asked the patient to stare at the overhead lamp and remember the position relationship between the corneal reflection point and the pupil center. Before making lenses, the green fixed target should be adjusted to align with this reflective point. Then slowly put the device close to the cornea until it touches 80%, and start suction. The front and back surfaces of the lens are scanned by a femtosecond laser at the incision position. After complete separation, carefully and quickly remove the lens from this small opening and check whether it is complete. Finally, the corneal bed was washed with balanced salt solution, a sterile sponge absorbed the residual liquid, concluding the procedure. 5.Preoperative and Postoperative Calculation of Effective IOL Position in SMILE Surgery Before and after the SMILE operation, we substituted the Pentacam and IOL-Master measurements into the Holladay I and Haigis formulas, respectively, to estimate the Estimated Lens Position (ELP). When using the Haigis formula, ELP is calculated as follows: a0 + a1 × ACD + a2 × AL. Here A0 = ACD-Const-A1× m (ACD Pro)-A2× m (Alpro), and A-Const = (ACD-Const+68.747)/0.62467. The manufacturer provides a constant for the intraocular lens, and we use it to calculate the ACD constant. The default coefficients for a1 and a2 are 0.4 and 0.1, respectively. In medical terminology, ACD represents the preoperative anterior chamber depth, AL stands for axial length, while A-const denotes the manufacturer-provided A-constant value of 119.The standard models a1 and a2 were determined by binary regression analysis, and a1 = 0.4 and a2 = 0.1 were finally obtained. The formula of Holladay I is calculated as follows: ELP = aACD+S, where the calculation method of s is A-constant×0.5663-65.60. The value of A-constant is 119. If AG exceeds 13.5, it is calculated as 13.5; If r is less than 7, count it as 7. Here, AL represents the axial length (the distance from the corneal apex to the vitreoretinal interface) measured by ultrasound, R is the radius of corneal curvature, the anterior chamber depth (AG) represents the measurement before the surgery, denoted as aACD. Additionally, S signifies the space between the iris's front and the intraocular lens's optical plane. 6.Data Analytics and Statistical Methodology: ①The statistical analysis was conducted using SPSS version 26.0, with all data presented as mean values alongside their standard deviations. To evaluate shifts in axial length, corneal refractive power, and anterior chamber depth following the SMILE procedure, we employed a paired t-test for comparison.② In order to compare the estimated lens position (ELP) calculated by Holladay I and Haigis formula, we analyzed the measured data of IOLMaster and Pentacam before and after SMILE operation by paired t-test. Statistical significance is denoted by p-values below 0.05.③ The Pearson correlation coefficient was employed to examine the interplay between the alterations in anterior chamber depth, as assessed by both the IOLMaster and Pentacam, and the depth of corneal ablation pre and post SMILE surgery. Results 1. Patient Demographics (Age, Corneal Ablation Depth, Visual Acuity, Intraocular Pressure, and Refractive Power) There are 35 participants in our study, with a total of 69 eyes (including 34 right eyes and 35 left eyes), including 19 boys (37 eyes) and 16 girls (32 eyes).Age span: 18-36, mean ± SD: 21.43 ± 4.72. During the operation, the corneal thickness ranged from 67 to 138 μm, with an average of 101.49±20.44 μm. After the operation, all corneal flaps were returned to their correct positions; there were no problems with them, and the cornea remained completely transparent. Before the operation, their UCVA LogMAR was 0.88±0.25, intraocular pressure was 16±2.11 mmHg, spherical power was-4.20±1.13 D, and cylindrical power was-0.40±0.30 D. One month after the operation, these values became better: UCVA LogMAR was-0.04±0.04, IOP was 10.54±2.43 mmHg, spherical power was-0.13±0.52 D, and cylindrical power was 0.02±0.39D. By the end of three months, the numerical values were more stable: UCVA LogMAR was-0.06±0.03, IOP was 10.33±1.65 mmHg, spherical lens power was 0.10±0.42 D, and cylindrical lens power was-0.10±0.39 D. 2. Anterior Posterior SMILE Ocular Axial Length (AL) Comparison In this study, we delved into the pre- and post-SMILE surgery axial length (AL) and AL* (which is AL minus central corneal thickness) assessments using the IOLMaster. We analyzed data from 35 myopic patients (totaling 69 eyes). Results revealed that the patients' AL before surgery was 25.63±0.58 mm, which decreased to 25.55±0.59 mm at one month post-op and 25.54±0.59 mm at three months post-op. The surgical intervention resulted in a mean change of 0.08±0.21 mm from baseline to the one-month follow-up and 0.09±0.16 mm from baseline to the three-month assessment, with both outcomes proving statistically significant (P0.05). Turning to AL*, the baseline measurement stood at 25.08±0.58 mm, dipping slightly to 25.09±0.60 mm by the one-month mark before returning to 25.08±0.60 mm by three months post-surgery. The respective deviations from preoperative values of -0.01±0.21 mm and -0.01±0.15 mm failed to achieve statistical significance (P>0.05), nor did a meaningful difference materialize between the one-month and three-month AL* readings (P>0.05)(Tables 1 and 2). 3. Comparison of Anterior Chamber Depth (ICAD) Pre- and Post- SMILE Surgery 3.1Comparing Anterior Chamber Depth Measurements (ICACD and ECACD) Pre- and Post-SMILE Surgery via IOLMaster (ECACD = ICACD - Central Corneal Thickness). The study cohort comprised 35 patients with myopia, totaling 69 eyes, who exhibited preoperative ICACD measurements averaging 3.80±0.24 mm. This metric nosedived to 3.66±0.24 mm at the one-month mark following surgery and stabilized at 3.67±0.23 mm by three months post-surgery. The pre-to-one-month delta came in at 0.13±0.07 mm, while the pre-to-three-month variation registered 0.12±0.09 mm. Although these changes passed the statistical muster (P0.05). On a parallel track, preoperative ECACD measurements stood at 3.25±0.24 mm, tapering off to 3.20±0.25 mm at one month and holding steady at 3.20±0.23 mm by three months post-surgery. Both the one-month (0.06±0.05 mm) and three-month (0.06±0.04 mm) differences proved statistically significant (P0.05) (Tables 1 and 2). 3.2Pentacam-measured Anterior Chamber Depth Variations (ICACD and ECACD) Pre- and Post-SMILE Procedure In our Pentacam analysis of the SMILE procedure, we noted alterations in the anterior chamber depth, specifically the ICACD and ECACD, both before and after the procedure. Among the 35 patients (totaling 69 eyes) with myopia, the ICACD was measured at 3.75±0.24 mm before surgery, decreasing to 3.59±0.26 mm at one month and then stabilizing at 3.60±0.24 mm at three months post-op. The ICACD measurement demonstrated a notable difference from pre-op to one month post-op, which was 0.16±0.13 mm, and from pre-op to three months post-op, at 0.15±0.07 mm. Both of these differences were statistically significant (P0.05). In line with this, the ECACD was measured at 3.20±0.25 mm before surgery, shrinking to 3.13±0.26 mm after a month and remaining constant at 3.13±0.24 mm at three months. The discrepancy between the pre-op and one-month post-op ECACD was 0.08±0.13 mm, while the difference between pre-op and three-month post-op was 0.07±0.06 mm, both pointing to statistically significant changes (P0.05)(Tables 1 and 2). 3.3Comparison of IOLMaster and Pentacam-measured Anterior Chamber Depth (ICACD) Pre- and Post-SMILE Surgery Statistically significant differences (P<0.05) were observed between preoperative values and measurements at 1 and 3 months postoperatively for both the IOLMaster (ICACD) and Pentacam (ICACD). Furthermore, the ICACD readings obtained with the IOLMaster consistently exceeded those obtained with the Pentacam across all measurement time points (Table 4). 3.4Anterior Chamber Depth Variations in Relation to Corneal Ablation Thickness No significant correlation was found between the Pentacam-measured difference in anterior chamber angle depth (ACAD) before and one month after surgery (n=35 eyes, 69 cases) and the depth of corneal ablation (r=0.15, P>0.05). Similarly, no significant correlation existed between the Pentacam-determined ACAD difference at the three-month postoperative interval and the corneal ablation depth (r=0.21, P>0.05). The same was true for the Master-observed ACAD variance at one month postoperatively when compared to the depth of corneal ablation (r=0.20, P>0.05), as well as for the three-month assessment (r=0.14, P>0.05) (Table3). 4.Comparison of Keratometric Refractive Power Before and After SMILE Surgery 4.1Km Measurements with IOLMaster Before and After SMILE Surgery In a study involving 35 myopic patients with a total of 69 eyes, the preoperative K-value was 43.08±1.14D, decreasing to 38.96±1.25D after just a month of surgery and further settling at 38.98±1.22D by the three-month mark. These changes were statistically significant when comparing pre-op to one-month and three-month post-op readings (P0.05) (Tables 1 and 2). 4.2SimK Variations in SMILE Procedures as Measured by Pentacam In our cohort of 35 myopia patients comprising 69 eyes, the preoperative SimK measurements averaged 42.82±1.16D, which nosedived to 38.86±1.27D at the one-month postoperative mark, before leveling off at 38.90±1.18D by the three-month check-in. The contrast between preoperative SimK values and those recorded at both one-month and three-month follow-ups was statistically significant (P0.05) (Tables 1 and 2). 4.3Comparison of pre- and post-SMILE surgery changes (Km) as measured by IOLMaster versus those (SimK) by Pentacam The preoperative discrepancy between Km and SimK measurements averaged 0.26±0.20D, which dropped to 0.20±0.10D one month post-surgery and further decreased to 0.17±0.08D by three months. Statistically significant differences were observed between Km and SimK values at all three time points (P<0.05) (Table 4). 4.4Comparison of TCRP and SimK measurements before and after SMILE surgery using Pentacam Before the operation, the TCRP was recorded at 42.22±1.17 diopters, while the SimK was 42.83±1.16 diopters. A month after the surgery, the TCRP dropped to 37.27±1.36 diopters, and the SimK to 38.86±1.27 D. By three months post-op, the TCRP was 37.42±1.25 diopters, and the SimK was 38.90±1.18 D. There was a notable difference in both TCRP and SimK values when comparing pre-op to one month and three months post-op, with the stats showing it was statistically significant (P<0.05)(Table 5). 5.Comparison of ELP Pre- and Post-SMILE Surgery Using the Holladayl Formula 5.1IOLMaster Holladayl ELP Comparisons: Pre- versus Post-SMILE Procedure The Preoperative Effective Lens Position (ELP) was measured at 6.16±0.19 mm, dropping to 5.54±0.12 mm at one month post-surgery and stabilizing at 5.54±0.01 mm by three months. The preoperative Holladay I (ELP) values showed a statistically significant divergence from both the one-month and three-month postoperative readings (P0.05)(Table 7). 5.2Pentacam ELP Comparison Using Holladayl Formula in SMILE Surgery Preoperative ELP was 6.12±0.19 mm, but nosedived to 5.52±0.12 mm one month post-surgery, then held steady at 5.52±0.11 mm by the three-month mark. The Holladay I (ELP) values showed that the difference between preoperative readings and both one-month and three-month postoperative measurements was statistically significant (P0.05)(Table 7). 5.3Comparison of IOLMaster and Pentacam Holladay I Formula Calculated ELP Before and After SMILE Surgery The preoperative discrepancy between the IOL Master Holladay I (ELP) and Pentacam Holladay I (ELP) was just 0.04±0.04 mm. One month post-surgery, the difference between the IOL Master's Holladay I (ELP) and the Pentacam's Holladay I (ELP) was only 0.01±0.01 mm, and this figure remained the same at 0.01±0.01 mm three months post-surgery. Notably, the differences between the IOLMaster and Pentacam measurements before and after one month, as well as after three months, were statistically significant (P<0.05) (Table 8). 6.Pre- versus Post-SMILE Haigis-Derived ELP Comparison 6.1IOLMaster ELP Comparisons in SMILE Surgery Using Haigis Formula Prior to the procedure, the ELP was 5.98 millimeters with a margin of error of ±0.12. At one month post-op, it had shrunk to 5.92 millimeters, within the same ±0.12 margin. By the three-month check-in, it had maintained that 5.92 millimeter mark with a slightly tighter margin, ±0.11. A statistical evaluation revealed a significant difference between the pre-surgery and both the one-month and three-month post-surgery readings (P0.05)(Table 7). 6.2Pentacam in Haigis Formula-Based SMILE Pre- and Postoperative ELP Comparison Before undergoing the procedure, the ELP was 5.97±0.12 mm. A month after the surgery, the measurement dropped to 5.89±0.12 mm. Three months later, it stood at 5.90 ± 0.12 mm. There was a notable difference in ELP between pre-op and both 1 and 3 months post-op, with P-values below 0.05. On the other hand, the difference between 1 and 3 months post-op wasn't significant, as the P-value was above 0.05 (Table 7). 6.3IOLMaster and Pentacam ELP Comparisons Using Haigis Formula in SMILE Procedures The preoperative discrepancy between the IOL Master Haigis (ELP) and Pentacam Haigis (ELP) measurements was 0.02±0.02 mm, whereas this gap widened slightly to 0.05±0.03 mm at the one-month postoperative mark and narrowed again to 0.03±0.03 mm by the three-month follow-up. Notably, all these differences between the two devices, both before surgery and at both postoperative timepoints, differed meaningfully (p<0.05) (Table 8). 7.Holladayl and Haigis ELP Calculations: Preoperative vs. Postoperative SMILE Surgery Comparison 7.1Comparison of pre- and post-SMILE surgery ELPs calculated using the Holladay I and Haigis formulas with IOLMaster In a comparative study of the Holladay I ELP and the Haigis ELP preoperatively, there was a discrepancy of -0.39 ± 0.16 mm between the two at one month post-op, and -0.39 ± 0.15 mm at three months post-op. Statistical significance was observed for all comparisons—before and after surgery, and at both 1 and 3 months postoperatively—reaching P-values below 0.05 (Table 6). 7.2Pentacam ELP Calculations Using Holladayl and Haigis Formulas Before and After SMILE Surgery Prior to SMILE surgery, the Holladay I (ELP) and Haigis (ELP) discrepancies measured 0.15±0.22 mm. Following surgery, at one month, this gap had widened to -0.37±0.17 mm, and at three months, it had stabilized at -0.37±0.16 mm. Comparing the Holladay I (ELP) values at one month and three months post-op to the pre-op readings, we saw significant differences in the Haigis (ELP) values (P<0.05) (Table 6). Discussion Our nation has the highest prevalence of myopia, and over the past two decades, refractive corneal surgery has gained immense popularity in our country. The SMILE procedure, in particular, has been validated for its safety, efficacy, and long-term stability[1], making it one of the primary surgical methods for correcting refractive error. Patients who undergo SMILE may face a shared challenge two to three decades later: the development of cataracts in the surgical eye. Accurately computing the power of the intraocular lens is a tough nut to crack in the field of ophthalmology, especially since the SMILE technique messes with the cornea's shape. This tweak affects the front-to-back surface ratio and disrupts the correlation between corneal depth and the eye's central axis. Common biometric methods are prone to errors, such as diopter measurement, axial alignment, and effective lens position, which can affect the accuracy of intraocular lens (IOL) power calculation [3]. For the calculation of IOL power, the accuracy of axial length is the most important, because a measurement error of 1 mm may lead to a deviation of 2.5 to 3.5 diopters [4]. Similarly, an error of 1 mm in the measurement of anterior chamber depth will lead to a difference of 1.5 diopters after operation [5], while an error of 1.00 diopters in the measurement of corneal curvature will lead to a deviation of 1.3 to 1.6 diopters in the estimation of IOL power [6]. Therefore, researchers have devoted significant effort to improve the accuracy of IOL power calculation for cataract patients who have undergone corneal refractive surgery and have developed various measurement methods and calculation formulas. Despite the continuous improvement in ophthalmology technology and the increasing complexity of formulas, Wang L's team's research found that methods such as Haigis-L, Wang Koch Maloney, and Shammas, which do not rely on past clinical data, are better than those that use all patient data [7]. This conclusion is consistent with the similar research done by McCarthy and others [8]. When measuring axial length, doctors primarily use ultrasound (A-scan) and optical devices, such as IOL-Master and Lenstar. The accuracy of these optical biometers in determining the axial length of the eyes has been fully proved in clinical practice [9]. However, there is a lack of research, both at home and abroad, on potential errors in the predicted lens position (ELP). As the third and fourth generation ELP formulas show, the main determinants of ELP are axial length, anterior chamber depth, and corneal refractive power. Therefore, most errors in ELP calculation can be traced back to these specific factors. To solve these problems, several methods are proposed: improving the accuracy of biometric parameter evaluation, strategically selecting appropriate measuring tools, and carefully selecting the optimal calculation formula for the intraocular lens. The following analysis will discuss these strategies in detail. 1. Evaluation of Biological Parameters 1.1Axial Length (AL) Even a 1 mm difference in axial length (AL) can lead to an error of 2.5 to 3.5 diopters [1], so accurate AL data must be used when calculating intraocular lens power. Instruments such as the IOL-Master are more accurate than traditional A-super technology eye-axis measurements. Clinical data show that if AL is accurately measured, postoperative refractive error can be reduced from 54% to 36%[11]. The accuracy of traditional contact A super-measuring eye axis is 0.10–0.12mm [12], while IOL-Master can reach 0.01mm [9], and the result is more reliable. In addition, people with high myopia often have posterior scleral staphyloma, which distorts the smooth, uniform shape of the posterior segment of the eyeball, making measurements more difficult and results more variable [13-14]. The optical measurement technology of IOLMaster aligns with the natural anatomical distance from the anterior corneal surface to the center of the macula, and its built-in signal processing function improves the accuracy of axial length measurements. In our study measuring the axial length (AL) of patients undergoing SMILE surgery with IOL-Master, the postoperative value is always shorter than the preoperative value, but the change over different follow-up times is not obvious. This result is consistent with the reports of Wang et al. [15] and Spyridon et al. [16]. On the contrary, Xu et al. [17] measured the AL of 28 LASIK patients (55 eyes) with IOL-Master and contact A ultrasound and found that the postoperative AL measured by the two devices was significantly shorter. The observed shortening of AL seems to be related to the amount of corneal tissue removed during the operation. The analysis of AL*(AL* = AL-central corneal thickness) one month and three months after refractive surgery showed that there was no statistically significant change compared with the preoperative measurement, indicating that AL* remained stable. This means the distance between the corneal endothelium and the macula has not changed, further confirming that the decrease in AL is due to the removal of corneal tissue. In addition, our data showed that the posterior corneal surface did not move forward or backward after the SMILE operation, consistent with the findings of Wang et al. [15] and Wang L [18]. 1.2Anterior Chamber Depth (ICACD) A-scan biometrics is still a common method for evaluating the anterior chamber of the eye, but it requires contact with the cornea, which increases the risk of infection. Moreover, the results obtained with this method are often inconsistent, and its accuracy depends on the operators' skills and experience. Therefore, more and more people are now using non-contact measurement methods [19]. The characteristic of the Pentacam 3D anterior segment analyzer is that it doesn't contact the cornea, greatly reducing the risk of contamination. In addition, the anterior chamber measurement data it provides has been shown to be very accurate and reliable [19]. Therefore, in this study, we aim to use the Pentacam system to measure anterior chamber depth in Chinese people with mild myopia and to further investigate this issue. Looking at it with a Pentacam, the anterior chamber is the space between the innermost layer of the cornea (the corneal endothelium) and the iris, pupil, and the front of the lens. In this study, anterior chamber depth is measured as the thickness of the middle corneal layer, allowing us to analyze the ICACD value obtained from Pentacam. Our results show that the ICACD value measured after the SMILE operation is shallower than before. However, in the follow-up one month and three months after the operation, these changes were not statistically significant, and the measured value was stable at (3.13 0.26) mm. This result is consistent with the previous research of Zhu et al. They examined anterior chamber depth in 138 eyes before and after LASIK/LASEK using the Pentacam system and found that depth decreased after both procedures [20]. In a similar study, Li et al. [21] used the Sirius anterior segment analyzer and the A-scan thickness gauge to measure the posterior corneal surface height, anterior chamber depth, and lens thickness of patients before and after refractive surgery. Their results show that the anterior chamber depth becomes shallower and the lens thickness increases after the operation, suggesting an inverse relationship between the two [21]. Therefore, our study also examined the ECCD before and after the SMILE operation (calculated as ICACD minus the cutting depth) and found that a shallow anterior chamber persisted after the SMILE operation. Because ECACD can accurately reflect the true anterior chamber depth (the distance from the posterior surface of the cornea to the anterior surface of the lens), we think that the decrease in ICACD after surgery is mainly due to the thickening of the lens after myopia correction. Importantly, we found no correlation between the depth of corneal ablation and the decrease in ICACD after operation, indicating that this phenomenon was not solely related to the cornea but also to important changes in the lens. IOL-Master measures the depth of the anterior chamber using a method called slit beam projection, which involves shining light from the side of the eye, taking photos, and letting the computer system analyze the results. This measurement includes the distance from the front of the cornea to the lens, including the cornea's thickness. After laser surgery for myopia, the anterior chamber will become shallow, and the cornea will change shape. Nawa [22] believes that the shallow depth of the anterior chamber after excimer laser surgery is related to the change of corneal shape and the magnifying effect of the imaging system. Our study found that the depth of corneal ablation is unrelated to a shallow anterior chamber. This shows that there are other reasons for a decrease in anterior chamber depth besides corneal ablation depth. Therefore, we compared the ECCD before and after the SMILE operation (that is, ICACD minus the cutting depth) and found that the ECCD became shallower after the operation. This raises the question of whether anterior chamber depth decreases after SMILE, a finding related to the lens. Wang Liang et al. [24] found that the shallow depth of the anterior chamber after LASIK was related to the thickening of the lens. In addition, previous studies [23-24] show that changes in eye accommodation ability can cause the lens to thicken and move forward, thereby reducing the depth of the anterior chamber. Therefore, the shallow ICACD observed after SMILE surgery may be due to several factors, including corneal tissue cut off during the operation, changes in lens thickness and position after the operation, and the magnifying effect of the imaging system during examination. We also compared and evaluated the two instruments used in this survey. The results showed a significant difference between the two methods at 1 and 3 months after SMILE (P<0.05). Before the operation, the depth of the anterior chamber (ICACD) measured by IOL-Master was higher than that measured by Pentacam, with a difference of 0.04-0.07 mm. After the operation, the gap was expanded to 0.07 0.08 mm. There may be several reasons why the ACD readings from these devices are inconsistent. First, the two devices use different measurement methods. Pentacam uses Scheimpflug technology to directly measure the depth of the anterior chamber (ECCD) and the central thickness of the cornea, while IOL-Master uses imaging technology plus corneal refractive power to calculate ICACD. Secondly, they are measured in different ways. When measuring ICACD, IOL-Master emits a 0.7 mm slit beam at an angle of 38, which passes through the cornea to form an optical section. The distance from the front surface of the cornea to the front surface of the lens is then calculated by the internal software. In this process, the visual axis and optical axis of the IOL-Master show a nasal deviation of 5, whereas Pentacam measures ECACD directly along the optical axis. Finally, the two devices have different definitions of ICACD. IOL-Master calculates the distance from the anterior surface of the cornea to the anterior surface of the lens, while Pentacam measures the distance from the posterior surface of the cornea to the anterior surface of the lens. To facilitate direct comparison, we added the CCT value to Pentacam's readings, which may introduce some inaccuracy. Although there are obvious statistical differences between the two devices when measuring ACD, the difference of 0.1 mm only accounts for 2.7% of the average ICACD measured by them. Such a small difference has no effect on the actual medical treatment. Therefore, when measuring ICACD in myopia patients, both devices can be used, and the results are consistent with previous studies, indicating that Pentacam and IOL-Master have similar effects [25]. Simply put, this study used IOL-Master and Pentacam to measure the eye data before and after myopia surgery. The results showed that the axial length was shortened and the depth of the anterior chamber (ICACD) was also reduced. The change of axial length seems to be directly related to corneal ablation, while the change of anterior chamber depth (ICACD) may be related to surgical ablation depth, corneal healing after operation, and lens thickening. However, the specific reasons need more research. In addition, IOL-Master and Pentacam have similar effects in monitoring changes in anterior chamber depth (ICACD) after SMILE, indicating they can be used interchangeably in this case. 1.3Keratometric mean (Km) The cornea is like a super-powerful lens, with two curved surfaces: the front and the back. The front curved surface contributes about +48D focusing power, while the rear curved surface provides about -5D refractive power. This is because the refractive power of corneal stroma (1.336) and aqueous humor (1.337) is slightly different. This shows that the anterior and posterior surfaces of the cornea are very important to its overall refractive function. At present, the equipment used to measure the cornea in eye clinics, such as keratometers, keratoscopes, and early topography machines, is mostly based on Gullstrand's eye model. These devices usually use a fixed refractive index, n = 1.3375. Their working principle is to measure the curvature in front of the cornea, and then convert this curvature into diopters (in D) by the formula k=(n-1)/r, where K denotes the corneal refractive index, and R represents the curvature radius. However, this calculation is based on two key premises: first, the ratio of the front radius to the back radius is always about 82%, the corneal thickness is set to 500μm, and the front and back surfaces are regarded as a whole with a refractive index of 1.3375; Secondly, assuming that the cornea is perfectly spherical, the radius of curvature of the central area and the peripheral area (3-4 mm) has not changed significantly. Pentacam is a new development in an anterior segment diagnosis platform that uses Scheimpflug imaging technology to measure the posterior corneal surface for the first time. This advanced equipment can collect extensive data, including height maps of the anterior and posterior surfaces, axial and tangential curvature radii, and corneal thickness information point by point. In this way, ophthalmologists can more accurately evaluate the posterior corneal shape and track changes in corneal structure after refractive surgery. Simply put, Pentacam is like a rotating Scheimpflug camera that uses optical tomography to capture images of the front part of the eye. It can rotate a full circle in just 2 seconds and capture 50 images of corneal cracks simultaneously. From each image, this device can find 500 accurate height points on the cornea and collect more than 25,000 data points, enabling the generation of a three-dimensional image of the anterior segment of the eye [26]. Through its Scheimpflug camera, Pentacam can directly obtain the height map of the anterior and posterior surfaces of the cornea, and then calculate a lot of detailed information by mathematical methods, including the heights of the anterior and posterior surfaces, the axial and tangential curvatures, the thickness of the cornea, and the depth of the anterior chamber. Moreover, this technology can also help track the changes in various corneal measurements before and after surgery. Previous studies have confirmed that Pentacam data for measuring anterior segment parameters of the eye are reliable [27-28]. IOL-Master has always been the standard equipment for measuring corneal diopter in traditional cataract surgery, and it can accurately capture data from the normal cornea. However, if the corneal structure is abnormal, its measurement results will be unreliable [29-30]. Its working principle is: six hexagonal light spots are projected in the area with a diameter of 2.3 mm on the anterior surface of the cornea, and then the curvature radius of the anterior surface of this annular area is calculated by reflected light. After the SMILE operation, it can only measure the average corneal diopter of two symmetrical points in the central annular area, and it is impossible to know the situation outside this area. The problem is that the normal cornea is not a perfect sphere; its center appears spherical, while the edges are flatter (as shown in the topographic map).IOL-Master only measures the curvature of the anterior cornea. It assumes that the curvature radius of the posterior cornea is always 82.2% of that of the anterior cornea, thus forming a ratio of 1.2:1. It uses a formula Km=(1.3375-1) × 1000/R and the usual refractive index of 1.3375 to calculate the diopter of the cornea. However, the corneal refractive index may be inaccurate, thereby affecting its reliability. Moreover, if the patient is uncooperative, has corneal leukoplakia, has severe lens opacity, or can't maintain a steady gaze, the IOL-Master reading may be very inaccurate. Because the working principles of these two devices are fundamentally different, our research mainly uses IOL-Master (Km) and Pentacam (SimK) to measure corneal diopter before and after SMILE, and also compares Pentacam (SimK) data with Pentacam TCRP.According to the curvature of the 3 mm area in the center of the anterior surface of the cornea and the commonly used refractive index of 1.3375, the SimK value obtained by Pentacam is calculated by the Gaussian thin lens formula, which is the same as the Km value calculated by the standard corneal topographic map. To avoid potential systematic errors, IOLMaster also uses the same standard refractive index of 1.3375 when calculating Km. Our results show that the Km reading after operation is obviously larger than that measured by SimK, which is consistent with the research of Elbaz et al. [31], who reported that there is a difference of -0.47D between the two measurement methods; The research of Pan Hong et al [32] also supports this point, and they found a statistically significant difference of-0.49 D.The difference between Km and SimK values mainly comes from two reasons. First of all, IOL-Master and Pentacam use different measurement areas: IOL-Master looks at a range of 2.3 mm in the middle of the cornea, while Pentacam looks at a range of 3 mm in the middle. Because the refractive power of the middle part of the cornea is usually stronger before the operation, the reading of Km is 0.21 to 0.31D higher than that of SimK. Secondly, after SMILE surgery, the intermediate optical zone usually becomes flatter, altering the normal curvature relationship between the anterior and posterior corneal surfaces. Because both devices use the average refractive power in the middle region to represent the cornea's axial refractive power, this change after surgery may lead us to overestimate the cornea's true refractive power.For these patients, inaccurate measurements may lead to excessive farsightedness after cataract surgery [33]. Researchers such as Seitz and Qazi have found that Pentacam equipment can overestimate corneal refractive power after laser vision correction. Similarly, Savini and colleagues observed that the SimK reading on the Pentacam (39.82±1.51 D) was higher than the actual refractive power in 15 people who had undergone LASIK surgery. Schafer et al. also observed that IOLMaster equipment overestimated corneal refractive power after surgery in 58 eyes. Clinical evidence shows that both SimK and Km readings are lower than the refractive power really needed when choosing an intraocular lens, as mentioned in reference [33]. Our own data show that the value of Km is 0.05-0.15 D and 0.03-0.12 D higher than that of SimK one month and three months after operation, respectively. Despite the absence of an ideal technique for assessing corneal refractive strength post-surgically, Pentacam tends to report a lower postoperative refractive value, which may be closer to the actual postoperative refractive value.In addition, our study found that before and after the SMILE operation, there was a significant difference between the Pentacam-measured SimK and TCRP values, with TCRP consistently lower than SimK. This shows that the SimK from Pentacam does not account for the posterior corneal surface, and the ratio of the anterior to posterior corneal surfaces will change after SMILE surgery.Pentacam's TCRP function uses ray tracing technology. According to Snell's law, it determines the trajectory of collimated light through both the front and back corneal layers,and then determines the focal length and converts it into corneal refractive power. This method uses the true refractive indices: air (1), cornea (1.376), and aqueous humor (1.336). Corneal refractive power is calculated according to the formula K = n/f, where n is 1.336, and f is the focal length.The anterior surface of the cornea is the reference plane, and ray tracing technology does not depend on the assumed refractive index of the cornea to calculate curvature, so it can evaluate the true curvature of any specified corneal diameter.In addition, TCPR will comprehensively evaluate four key parts: anterior and posterior corneal layers, true refractive index, corneal asphericity (including spherical deviation), and the depth of the whole cornea. In this way, the cornea's focusing ability can be evaluated more reliably, especially after laser vision correction surgery. Generally speaking, the corneal curvature readings measured by Pentacam after SMILE surgery are more reliable than the average curvature data measured by IOL-Master. Moreover, PentacamTCRP's readings are more accurate than PentacamSimK's measurements. 2.Factors affecting ELP The evolution of intraocular lens power calculation methods has spanned four distinct phases. When dealing with cataract patients who haven't had corneal refractive procedures, we're able to precisely anticipate their preoperative refractive errors, a development that's a win-win for both patients and medical professionals. But when it comes to eyes that have had prior corneal refractive surgery, the level of accuracy takes a nosedive. A crucial element in this equation is the Effective Lens Position (ELP), which essentially refers to the distance from the cornea's front to the plane of the inserted lens. It is found that even a 1 mm error in ELP calculation can lead to a change in degree of about 1.5 to 2 diopters [34]. For eyes that have undergone myopia correction surgery, if the ELP is underestimated, a lower-power intraocular lens will be selected, and the patient will eventually become hyperopic. This result is consistent with the conclusion of our study [29,35]. In the past 10 years, more than 20 new calculation methods have been developed worldwide, all aimed at improving the prediction of intraocular lens power after this type of corneal surgery [36-37]. Recent studies have found that although the Hoffer-Q, Holladay, and SRK/T formulas yield similar results in predicting intraocular lens power, each method performs better at specific axial lengths [38-39]. The Hoffer-Q formula is most suitable for eyes with an axial length of 22 mm or less, while the Holladay formula works best in the range of 24.5 to 26 mm [40]. Interestingly, when the axial length is between 22.0 and 24.5 mm, the accuracy of the three formulas is almost the same, and none of them is obviously better. In our study, the axial length ranged from 22 to 27 mm, which was consistent with previous studies. An analysis of 77 eyes found no significant difference in refractive results among the Holladay1, Olsen, and SRK/T formulas [41]. A subsequent investigation involving 100 eyes ( averaging 22.89 mm in axial length ) determined that the Holladay I formula outperformed both the SRK/T and Hoffer Q formulas in terms of precision. [42]. A large-scale study of 8,018 eyes found that for eyes with an axial length of 22 to 26 mm, the results of the Holladay1 formula were slightly better or similar to those of the HofferQ and SRK/T formulas [43]. For the range of axial length from 22 to 27 mm, Haigis, Holladay I, and Hoffer Q formulas all perform very well, and the effect is almost the same [44]. In patients with an axial length of 24.5 to 27 mm, Haigis, SRK/T, and Holladay1 formulas can each give reliable predictions [45]. This conclusion was supported by Jiang et al. [46], who evaluated 169 cases and found no significant difference in prediction errors among the third-generation IOL formulas (SRK-T, Hoferq, Holladay-I, and Haigis). In this study, the Holladay and Haigis formulas are used to compare the accuracy of calculation methods for intraocular lens (IOL) power after refractive surgery. It further examined and compared the accuracy and determining factors of measuring corneal refractive power with Pentacam and IOL-Master equipment after refractive surgery. The Holladay formula, in theory, is an improved method that uses axial length and average corneal refractive power to more accurately predict the Effective Lens Position (ELP). Holladay's innovation in 1988 combined the patient-specific Anterior Chamber Depth (ACD) factor with the Fyodorov method, marking the beginning of the third-generation calculation formula. This method uses axial length and corneal refractive power to estimate corneal height, that is, the distance from the corneal endothelium to the iris plane. In this model, the depth of the anterior chamber is calculated by adding the corneal height, corneal thickness, and the distance from the anterior surface of the iris to the optical plane (SF) of the IOL. In order to achieve the best accuracy, this formula also adds a personalized "surgeon factor" to adjust the IOL model and other factors, such as the equipment for measuring the cornea, the position where the lens is placed during the operation, the wound suture method, and the technical level of the surgical team [47]. Haigis formula was introduced by Professor Haigis in 1991 [49]. It is widely used in Germany and is increasingly used in other parts of the world. This formula improves the accuracy of predicting the effect of vision correction after intraocular lens implantation. Like other third-generation theoretical formulas, Haigis model is a multivariate regression equation based on the concept of a thin lens. Its advantages include a detailed, practical description of anterior chamber depth [48] and an advanced method for calculating the effective crystal position (ELP). The terms M(ACDpro) and M(ALpro) denote average ELP and axial length, respectively, calculated from biometric data from a large group of patients who have undergone cataract surgery [49]. The coefficients a0, a1, and a2 are calibrated to take into account the characteristics of the intraocular lens, the axial length of the eye, and the depth of the anterior chamber, which makes the estimation of ELP more accurate [50]. This research examined data from 35 patients (69 eyes) using two diagnostic tools—the IOL-Master and Pentacam—to assess corneal refractive power and anterior chamber depth before and after SMILE surgery. The Effective Lens Position (ELP) was computed using two separate formulas, and the outcomes were cross-compared. With the Holladay I formula, the IOL-Master’s ELP measurements averaged slightly higher than the Pentacam’s by 0.04±0.04 mm at one month, 0.01±0.01 mm at three months, and 0.01±0.01 mm at six months post-operation. Although statistically significant, this minor deviation—just 1.3% of the mean ELP value—is clinically insignificant and likely due to instrument variability and the limited cohort. Parallel trends emerged with the Haigis formula, where the IOL-Master’s ELP exceeded the Pentacam’s by 0.02±0.02 mm, 0.05±0.03 mm, and 0.03±0.03 mm at the same postoperative intervals. These differences may be caused by inaccurate instruments and too few subjects. The study also found that both Pentacam and IOL-Master Holladay I ELP were much higher (0.18±0.22 mm) before operation than Haigis ELP, but much lower (0.39±0.15 mm) after operation. When comparing the ELP calculated by the two formulas, Holladay I's formula directly links the ELP with corneal refractive power, anterior chamber depth, and axial length. In this formula, the depth of the anterior chamber is calculated from the axial length and corneal refractive power, indicating that ELP is essentially determined by these two variables. In contrast, Haigis formula does not depend on corneal refractive power when calculating ELP, but directly uses anterior chamber depth and axial length. Because the IOL-Master equipment ensures the axial measurement accuracy of the two formulas, the difference of their ELP results mainly comes from the error of corneal refractive power and anterior chamber depth after SMILE surgery. Moreover, the ELP values calculated by these formulas were originally developed by the author based on specific assumptions and statistical results, and this process naturally introduces systematic and random errors [51-52]. The parameters used by Holladay I's formula to predict ELP-corneal refractive power and axial length are easily adjusted across different measuring equipment [53]. Similarly, the predictive parameters of Haigis' formula, anterior chamber depth, and axial length, will also be affected by the inconsistency of measuring instruments [53]. This study found that in 35 myopia patients (69 eyes), the effective lens position (ELP) moved forward by 0.63 ± 0.18 mm after SMILE surgery, a statistically significant change. Previous studies have shown that when only cataract surgery is performed, the intraocular lens (IOL) position is very stable and rarely moves [80]. For example, Eom et al. observed that the IOL moved by only 0.06 to 0.11 mm after cataract surgery; this small change had no effect on the treatment [54]. Similarly, Corydon et al. also found that the displacement of IOL can be ignored (0.02 0.13 mm) after myopia laser surgery and cataract treatment, which is similar to the result of simple cataract surgery [55]. The stability of ELP mainly depends on the fixed position of the capsular bag, suspensory ligament, and ciliary body. Our study found that the effective lens position (ELP) of myopia patients shifted forward by 0.63 ± 0.18 mm after SMILE surgery, indicating a significant change in ELP. This forward movement of ELP is consistent with the decrease in anterior chamber depth, indicating that ELP adjustment is directly related to this change. Therefore, the changes in ELP observed in our study appear to be due to a decrease in anterior chamber depth. This study has several limitations, including the lack of data at different postoperative time points. In addition, it is not clear whether the patient's accommodation conditions will change over time, whether lens thickness will change, or whether there is a difference in anterior chamber depth between short-term and long-term postoperative evaluations. The small number of participants also means that systematic bias cannot be ruled out entirely. With ongoing advances in medical technology, managing cataracts after refractive surgery is increasingly challenging. By comprehensively analyzing the causes of inaccurate intraocular lenses in patients who have undergone prior refractive surgery, adopting the most advanced surgical methods, and combining our skilled surgical expertise with customized lens selection, we can finally help patients achieve the best visual outcome. Conclusions 1. After the SMILE operation, we found that the axial length of the eyes became shorter and the anterior chamber depth became shallower. Although the shortening of axial length is related to cutting off a part of corneas, the shallowing of anterior chamber depth has nothing to do with how many corneas are cut off during surgery. 2.After SMILE operation, the axial length can be measured accurately with IOL-Master instrument, among which TCRP method is the most reliable, followed by SimK and Km. When measuring anterior chamber depth, Pentacam and IOL-Master are very reliable. 3.He shallowness of anterior chamber depth after SMILE surgery will lead to the doctor's error in estimating the effective lens position, so the calculated intrinsic lens degree will be inaccurate, and finally the vision correction after cataract surgery will be biased. Declarations Funding No external funding was obtained for this study. Authors' contributions Conceptualization: C. S., X.G.,B.Z.; Methodology: X.G. and Clinical studies demonstrate C. S.; Data curation:C. S. Formal analysis: X.G.,B.Z.,T.J.,C.T.; Writing-original draft preparation: C. S. Writing-review and editing: C. S. Supervision: X.G., B.Z Data availability The study's resulting datasets can be accessed from the principal investigator upon submission of a suitable request. Ethics approval and consent to participate The study's methodology received approval from the Ethics Committee at the Second Hospital of Hebei Medical University and was conducted in full compliance with the Declaration of Helsinki. Because the research was designed to be prospective, every participant provided written informed consent, which was also approved by the same Ethics Committee. Human ethics and informed consent statement: Applicable Competing interests No competing interests are declared. References BlumM,FlachA,KunertKS,etal.Five-year results of refractive lenticule extraction[J].Journal of Cataract & Refractive Surgery,2014,40(9):1425-1429. Albouganem C, Lavaud A,Amar R. SMILE:Refractive lenticule extraction for myopic correction[J].Journal Francais D Ophtalmologie,2015,38(3). Masket S,Masket SE.Simple regression formula for intraocular lens power adjustment in eyes requiring cataract surgery after excimer laser photoablation.J Cataract Refract Surg 2006;32:430-434. 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McAlinden C,Khadka J,Pesudovs K.A Comprehensive Evaluation of the Precision(Repeatability and Reproducibility)of the Oculus Pentacam HR.Invest Ophthalmol Vis Sci 2011;52(10):7731-7737. Elbaz U,Barkana Y,Gerber Y.Comparison of different techniques of anterior chamber depth and keratometric measurements.Am J Ophthalmol 2007; 143(1):48-53. Gimbel H,Sun R.Accuracy and predictability of intraocular lens power calculation after laser in situ keratomileusis.J Cataract Refract Surg 2001;27(4):571-576. Olsen T. Calculation of power from the curvature of the cornea. Br J Ophthalmol 1986;70(2):152-154. Pan H, Wang L H, Ma LX. Comparison of corneal curvature and anterior chamber depth measurements between Pentacam and IOL Master[J]. Journal of Shandong University (Health Sciences), 2008, 46(6): 624-627. Reuland MS,Reuland AJ,Nishi Y,et al.Corneal radii and anterior chamber depth measurements using the IOL Master versus the Pentacam.J Refract Surg 2007;23(4):368-373. Seitz B,Langenbucher A.Intraocular lens power calcuation in eyes after corneal refractive surgery.[J].J Refract Surg.2000,16(3):349-361. Shajari M,Cremonese C,Petermann K,et. Comparison of axial length,corneal curvature,and anterior chamber depth measurements of two recently introduced devices to a known biometer[J].American journal of ophthalmology,2017,178:58-64. Gimbel HV,Sun R,Furlong,et al.Accuracyand predictability of intraocularlens power calculation after photorefractive keratectomy[J].CataractRefract Surg.2000,26;1147-1151. Holladay JT.Consultations in refractive surgery comment.Refract Corneal Surg 1989;5:203. Haigis W.Strahldurchrechnung in GauB’scher Optik zur Beschreibung des System Brille-Kontaktlinse-Hornhaut-Augenlinse(IOL).Schott hrsg,v.K Jacobi KW,Freyler H,et al. Intraokularlinsen Implant[M].Berlin: Essen,1990:233-246. Jiang Y, Shi Y Y, Yang WL. Comparison of the accuracies of six intraocular lens power calculation formulas[J]. Ophthalmology in China, 2007, 16(2): 100-103. Sasaki H,Sakamoto Y,Harada S,et a1.Predicting postoperative anterior chamber depth in patients with cataracts using Scheimpflug slit photography[J].Ophthalmic Res,2002,34(5):265-272. Olsen T．Improved accuracy of intraocular lens power calculation with the Zeiss IOL Master．Acta Ophthalmol Scand,2007,85(1)：84-87． Findl O,Drexler W,Menapace R,et al.Improved prediction of intraocular lens power using partial coherence interferometry.J Cataract Refract Surg 2001;27(6):861-867. Eleftheriadis H.IOLMaster biometry:refractive results of 100 consecutive cases.Br J Ophthalmol 2003;87(8):960-963. Wang J-K,Chang S-W.Optical biometry intraocular lens power calculation using different formulas in patients with different axial lengths[J].International Journal of Ophthalmology(English Edition),2013,6(02):150-154. Chen F, Sheng Y H, Li Z Q. Comparison between SRK-Ⅱ formula and the third-generation intraocular lens power calculation formulas[J]. Chinese Journal of Practical Ophthalmology, 2000, 18(3): 139-142. Du Y L, Jin C, Lin LY. Correlation between posterior staphyloma depth and postoperative refractive error in patients with high myopia complicated with cataracts [J]. Recent Advances in Ophthalmology, 2018, 38(11): 1070-1072. Shammas HJ,Shammas MC.No-history method of intraocular lens power calculation for cataract surgery after myopic laser in situ keratomileusis.J Cataract Refract Surg 2007;33:31-36. Huang F, Zhao Y E, Huang H H. Accuracy of the Haigis formula in predicting postoperative refraction after cataract surgery[J]. Eye Research, 2008, 26(3): 225-227. Biometrie HW. Yearbook of Ophthalmology 1995.In:Kampik A,editor.Optics and Refraction.Zuelpich:Biermann Verlag,1995.p.123-40. Haigis W.The Haigis formula.In:Shammas HJ,editor.Intraocular lens power calculations.Thorofare,NJ,USA:Slack Inc,2003.p.41-57. Jack T.Intraocular lens power calculations for the refractive surgeon.[J]Operative Techniques in Cataract and Refractive Surgery,1998,1:105-117. Norrby S.Sources of error in intraocular lens power calculation.J Cataract Refract Surg 2008;34:368-76. Norrby S,Bergman R,Hirnschall N,et al.Prediction of the true IOL position.Br J Ophthalmol 2017;101:1440-6. Tamaoki A,Kojima T,Tanaka Y,et al. Prediction of effective lens position using multi-objective evolutionary algorithm. Transl Vis Sci Technol 2019;8. Eom Y,Kang SY,Song JS,et al.Comparison of the actual amount of axial movement of 3 aspheric inti-aocular lenses using anterior segment optical coherence tomography,J Cataract Refract Surg 2013;39:1528-1533. Olsen T,Olesen H,Thim K,et al.Prediction of postoperative intraocular lens chamber depth.J Cataract Refract Surg 1990;16:587-590. Tables Table 1 . Biological parameters measured by two instruments before and after SMILE surgery (X±S) Pentacam Iol-Master Preoperative 1 month after the operation 3 months after surgery preoperative 1 month after surgery 3 months after the operation AL - - - 25.63±0.58 25.55±0.60 25.54±0. 59 AL* - - - 25.08±0.58 25.09±0.60 25.07±0.60 ICACD 3.75±0.24 3.59±0.26 3.60±0.24 3.79±0.24 3.66±0.24 3.67±0.23 ECACD 3.20±0.25 3.13±0.26 3.13±0.24 3.25±0.24 3.20±0.25 3.20±0.23 SimK/Km 42.83±1.16 38.86±1.27 38.90±1.18 43.08±1.14 38.96±1.25 38.98±1.22 TCRP 42.22±1.17 37.27±1.36 37.42±1.25 - - - Al: axial length (mm)Al * axial length - depth of cutting (mm)ICACD: depth of anterior chamber including corneal thickness (mm)ECACD: ICACD- depth of cutting (mm)Km: IOL Master corneal refractive power (D)SimK:Pentacam corneal refractive power (D)TCRP: total corneal refractive power (D) Table 2. Paired t-test of biological parameters measured by two instruments before and after SMILE surgery Pentacam Iol-Master 1 month after surgery VS before surgery 3 months after surgery VS before surgery 1 month after surgery VS 3 months after surgery 1 month after surgery VS before surgery 3 months after surgery VS before surgery 1 month after surgery VS 3 months after surgery t p t p t p t p t p t p AL - - - - - - 3.06 0.003 4.58 0.00 0.71 0.48 AL* - - - - - - -0.26 0.80 0.36 0.72 0.84 0.41 ICACD 9.80 0.00 17.78 0.00 -0.56 0.58 15.80 0.00 10.85 0.00 -0.42 0.68 ECACD 4.70 0.00 8.70 0.00 -0.41 0.33 6.07 0.00 3.96 0.00 -0.25 0.80 SimK /Km 30.89 0.00 34.74 0.00 -0.98 0.68 31.21 0.00 34.50 0.00 -0.32 0.75 Table 3. Correlation analysis of ICACD changes and corneal cutting thickness before and after SMILE surgery Range(mm) Corneal ablation thickness r p Difference in MAster (ICACD) between pre-operation and 1 month post-operation 0.11-0.15 0.20 0.11 Difference in MAster (ICACD) between pre-operation and 3 months post-operation 0.10-0.15 0.14 0.25 Difference between Pentacam before surgery and 1 month after surgery (ICACD) 0.13-0. 19 0.15 0.21 Difference between Pentacam before surgery and 3 months after surgery (ICACD) 0.13-0.17 0.21 0.08 Correlation analysis between ICACD difference and corneal cutting thickness, *P<0.05，**P<0.01 Table 4. Paired t-test of biological parameters measured by two instruments before and after SMILE surgery preoperativeSimK/Km 1 month after the operationSimK/Km 3 months after the operationSimK/Km preoperativeICACD 1 month after the operationICACD 3 months after the operationICACD Iol-Master 43.08±1.14 38.96±1.25 38.98±1.22 3.79±0.24 3.66±0.24 3.67±0.23 Pentacam 42.83±1.16 38.86±1.27 38.90±1.18 3.75±0.24 3.59±0.26 3.60±0.24 t 10.51 4.14 3.68 4.64 4.42 6.50 p 0.00 0.00 0.00 0.00 0.00 0.00 Table 5. Paired t-test of corneal refractive power measured by Pentacam before and after SMILE surgery Pentacam preoperativeTCRP/SimK 1 month after the operationTCRP/SimK 3 months after surgeryTCRP/SimK TCRP 42.22±1.17 37.27±1.36 37.42±1.25 SimK 42.83±1.16 38.86±1.27 38.90±1.18 t -29.66 -36.16 -48.24 p 0.00 0.00 0.00 Table 6. Paired t-test of ELP of two IOL calculation formulas measured by two instruments before and after surgery Pentacam preoperative 1month after the operation 3 months after surgery Iol-Master preoperative 1 month after the operation 3 months after the operation HolladayⅠELP 6.11±0.19 5.52±0. 12 5.53±0.11 HolladayⅠELP 6.16±0. 19 5.54±0.12 5.54±0.01 Haigis-L ELP 5.97±0.12 5.89±0.12 5.90±0.12 Haigis-L ELP 5.98±0.12 5.92±0.12 5.92±0.11 t 5.96 -18.66 -19.49 t 7.04 -20.09 -21.22 p 0.00 0.00 0.00 p 0.00 0.00 0.00 Table 7. Paired t-test of ELP of two IOL calculation formulas measured by two instruments before and after surgery Pentacam Iol-Master 1 month after surgery VS before surgery 3 months after surgery VS before surgery 1 month after surgery VS 3 months after surgery 1 month after surgery VS before surgery 3 months after surgery VS before surgery 1 month after surgery VS 3 months after surgery t p t p t p t p t p t p HolladayI ELP 29.59 0.00 32.59 0.00 -0.97 0.34 28.88 0.00 32.26 0.00 -0.10 0.92 Haigis-L ELP 10.02 0.00 16.65 0.00 -0.36 0.72 13.02 0.00 11.08 0.00 -0.13 0.90 Table 8. Paired t-test of ELP of two IOL calculation formulas before and after SMILE surgery preoperative HolladayI 1 month after surgery HolladayI 3 months after surgeryHolladayI preoperative Haigis-L 1 month after surgery Haigis-L 3 months after surgeryHaigis-L Iol-Master 6.16±0. 19 5.5±0.12 5.54±0.01 5.98±0.12 5.92±0.12 5.92±0.11 Pentacam 6.12±0.19 5.52±0. 12 5.53±0.11 5.97±0.12 5.89±0.12 5.90±0.12 t 10.16 5.34 3.16 4.64 4.42 6.50 p 0.00 0.00 0.00 0.00 0.00 0.00 Additional Declarations No competing interests reported. Supplementary Files SCI2.xlsx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Although there is no particularly effective medicine to cure it, surgery is the most important way at present. Small incidence lenticule extraction (SMILE for short) is a new corneal refractive surgery technique, which is particularly popular now, and it is liked by both surgeons and ophthalmologists. It is so popular because it has several main advantages: no corneal flap, less trauma, safety, effectiveness and reliability, so it has become the first choice in vision correction surgery [1]. Up to now, about 2 million SMILE operations have been performed in the world, accounting for more than 10% of all corneal refractive operations [1], and this number is increasing rapidly. However, as time goes by, people who have undergone SMILE surgery may eventually need to undergo cataract surgery and implant an intraocular lens (IOL) because of the side effects of surgery or because they are naturally suffering from cataracts when they are old.The main problem is how to choose the most suitable intraocular lens (IOL) power for more and more patients undergoing cataract surgery, so that their postoperative vision is normal or close to normal. The key to success lies in accurate measurement of eye data before operation. However, the corneal curvature will change in people who have undergone SMILE surgery, which often leads to inaccurate calculation of IOL power. There are three main reasons: 1) the measurement of corneal refractive power is inaccurate, 2) the measurement of axial length is incorrect, and 3) the method of calculating IOL power is flawed [2].\u003c/p\u003e\n\u003cp\u003eThis research aims to discern variations in effective lens positioning assessment using the Haigis and Holladay-I formulas.The accuracy of our intraocular lens power calculation hinges primarily on three crucial elements: the corneal refractive strength, the axial length of the eye (AL), and the measurement of the anterior chamber depth (ACD).A big problem now is that the measurement accuracy of the commonly used standard ultrasonic biometric instruments is often not accurate enough, especially for patients who have undergone laser surgery for myopia. This is mainly because of their shortcomings in design, such as the need for contact eye measurement, unstable results and low accuracy.Pentacam is an advanced medical tool, which uses Seheimpflug imaging technology to comprehensively image and evaluate the front of the eye. Cutting-edge technology allows this instrument to directly assess the refractive power of both the front and back layers of the cornea while simultaneously forecasting shifts in the eye\u0026apos;s focusing capability with remarkable precision.On the other hand, IOLMaster is a non-contact, minimally invasive eye measurement device, which works based on partially coherent interferometry. It uses 780 nm focused infrared diode laser with short coherent wavelength as light source. The IOLMaster has earned its reputation as a gold standard in ophthalmology, boasting impressive resolution and precision, while remaining remarkably user-friendly. Its patient-friendly design ensures minimal discomfort during examinations, ultimately enhancing the reliability of intraocular lens power calculations following vision correction procedures.\u003c/p\u003e\n\u003cp\u003eThe current investigation employed both the IOL-Master and Pentacam technologies to assess post-SMILE surgical alterations in corneal refractive power, axial length, and anterior chamber depth. Additionally, this research examined the correlation between variations in anterior chamber depth and corneal ablation depth. By feeding Pentacam and IOL-Master data into both the Holladay 1 and Haigis formulas, the study compared the predicted effective lens position (ELP) values. The overarching goal here is to furnish more precise anterior segment measurements for individuals undergoing corneal refractive surgery, thereby enhancing the accuracy of intraocular lens power calculations.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003e\u003cstrong\u003e1.Design:\u003c/strong\u003e A prospective study was conducted.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.Participants and Inclusion Criteria\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.1 Study Participants\u003c/strong\u003e\u003cbr\u003e\u0026nbsp;Between September and October 2020, a total of 35 patients (69 eyes) with nearsightedness underwent the SMILE procedure at the Second Hospital of Hebei Medical University\u0026apos;s Eye Center. This group consisted of 19 men (37 eyes) and 16 women (32 eyes), ranging in age from 18 to 36 years. Every patient achieved perfect 20/20 vision or better following their surgery. Medical evaluations were conducted before the operation as well as at one-month and three-month follow-up appointments.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.2: Inclusion Criteria\u003c/strong\u003e\u003cbr\u003e\u0026nbsp;① Must be in good health, Unaffected by severe autoimmune disorders like systemic lupus or MS, and devoid of systemic connective tissue disorders or keloid tendencies. ② Must be at least 18 years old, with a strong desire and requirement for vision correction, and in good mental health. ③ Should not have active eye inflammation, cataracts, retinal detachment, keratoconus, severe dry eye, glaucoma, subretinal hemorrhage, or significant ocular adnexal lesions. The tear film function test must not indicate severe dry eye. The cornea was transparent, with no significant opacities or spots. Soft contact lenses must be halted for over 2 weeks preoperatively.Discontinue wearing rigid contact lenses for more than a month. Orthokeratology lenses must be removed for at least 3 months. Postoperative follow-up must be at least six months. Myopia spectacle power should be no greater than -6.00D, and astigmatism no more than -0.50D. The remaining corneal stromal bed thickness must be at least 280\u0026mu;m after surgery. Candidates must show a stable diopter in the past 24 months. Before the SMILE operation, the patients understood the specific details of the procedure and its possible risks. be completed without any obvious problems during and after the operation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.Preoperative Preparations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.1 Informed Consent\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBefore the SMILE operation, the patients understood the specific details of the procedure and its possible risks. They must then complete and sign the consent form and the surgical approval document.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2 Visual Acuity and Refractive Testing\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eVision: We use a standard eye chart before and after the operation to check the patient\u0026apos;s vision without glasses.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eOptometry: We performed automated optometry using a digital instrument. When preparing, give the patient 1 drop of tropicamide eye drops every 5 minutes for a total of 6 drops. The patient rested for 30 minutes with his eyes closed, and the degree was measured while his pupils remained dilated. During the preoperative consultation, we also performed subjective optometry and carefully recorded all results.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.3 Anterior Segment Examination\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe carefully examined the conjunctiva,cornea, anterior segment, iris, pupil, and lens in sequence with a slit lamp microscope.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.4 Fundus Examination\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAfter using tropicamide eye drops to enlarge the pupil, we carefully examined the fundus with a lens or a three-sided mirror mounted on a slit lamp. We examined the retina carefully for any abnormal signs, such as degeneration, tears, or bleeding. If treatment is needed, laser therapy may be used to solve the retina\u0026apos;s problem.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.5 Intraocular Pressure Measurement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe measured intraocular pressure three times with a non-contact tonometer, and the final recorded value is the average of these three measurements.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.6 Corneal Topography Examination\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eMethods: Pentacam HR anterior segment analyzer was used for evaluation. Before the test, input the patient\u0026apos;s information into the equipment. Guide the participants to place their chin on the instrument\u0026apos;s bracket and their forehead against the bandage. Then let them blink a few more times to evenly distribute the tear film, then open their eyes completely and stare at the flashing red light. The operator uses the joystick to adjust the focal length according to the on-screen prompts, and the equipment automatically takes pictures when the focal length is optimal. Data collection is performed in a dark environment to maintain the patient\u0026apos;s pupil in a natural state. Per the manufacturer\u0026apos;s guidelines, scan outcomes only qualify when the image quality indicator registers as \u0026quot;OK.\u0026quot; Every subject underwent three consecutive scanning sessions, all conducted by a single, highly trained technician to ensure consistency throughout the process.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.7 Examination by IOL Master\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe working principle of IOLMaster is to project six evenly distributed light spots to the cornea to form a circle with a diameter of 2.3 mm. By analyzing the reflection of these light spots, the instrument can measure the distance between them. By applying the Gullstrand formula, k = (n-1)/r, this instrument is able to determine the mean curvature of the front portion of the cornea. Given that the curvature relationship between the back and front surfaces stands at 82% and utilizing the conventional refractive index value of 1.3375, the cornea\u0026apos;s focusing strength can be accurately calculated.When measuring, the patient needs to rest his chin and forehead on the designated support and stare at the target point inside the instrument. IOLMaster will record the values of K1 and K2, and the final result (Km) is the average of three consecutive readings; the calculation formula is Km = (K1 + K2)/2. The main output from IOLMaster is the Km value.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e4.Surgical methods\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll the surgical steps were completed by an experienced surgeon. To reduce the risk of infection, we asked patients to use gatifloxacin eye drops 4 times daily for 3 days before the operation. This antibiotic regimen will continue after the operation. For local anesthesia, we dropped a drop of 0.4% procaine hydrochloride into the conjunctival sac during the operation. Then, the conjunctival sac was washed with warm saline, and the skin around the eyes was cleaned with a cotton swab soaked in 0.5% povidone-iodine. Disinfection is centered on the drooping eyelid, extending from the hairline to the line connecting the nasolabial groove and the earlobe, and crossing the nasal midline inward. Disinfectant was used three times in all. Employing the VisuMax femtosecond laser system (Carl Zeiss, Germany), the corneal flap and lens were crafted post-preparation.The laser parameters are as follows: pulse energy 140nJ, pulse frequency 500kHz, corneal flap thickness 120um, flap diameter 7 mm, lens diameter 6-6.5 mm, expected residual matrix bed thickness 10-15um, lateral incision 2 mm, and lens and lateral incision angle 90 degrees. The patient lies flat on the operating table, his head should be straightened, his forehead and chin should be level, and the midline of his face should be aligned with the center. After local anesthesia, the doctor asked the patient to stare at the overhead lamp and remember the position relationship between the corneal reflection point and the pupil center. Before making lenses, the green fixed target should be adjusted to align with this reflective point. Then slowly put the device close to the cornea until it touches 80%, and start suction. The front and back surfaces of the lens are scanned by a femtosecond laser at the incision position. After complete separation, carefully and quickly remove the lens from this small opening and check whether it is complete. Finally, the corneal bed was washed with balanced salt solution, a sterile sponge absorbed the residual liquid, concluding the procedure.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e5.Preoperative and Postoperative Calculation of Effective IOL Position in SMILE Surgery\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBefore and after the SMILE operation, we substituted the Pentacam and IOL-Master measurements into the Holladay I and Haigis formulas, respectively, to estimate the Estimated Lens Position (ELP).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eWhen using the Haigis formula, ELP is calculated as follows: a0 + a1 \u0026times; ACD + a2 \u0026times; AL. Here A0 = ACD-Const-A1\u0026times; m (ACD Pro)-A2\u0026times; m (Alpro), and A-Const = (ACD-Const+68.747)/0.62467. The manufacturer provides a constant for the intraocular lens, and we use it to calculate the ACD constant. The default coefficients for a1 and a2 are 0.4 and 0.1, respectively. In medical terminology, ACD represents the preoperative anterior chamber depth, AL stands for axial length, while A-const denotes the manufacturer-provided A-constant value of 119.The standard models a1 and a2 were determined by binary regression analysis, and a1 = 0.4 and a2 = 0.1 were finally obtained.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe formula of Holladay I is calculated as follows: ELP = aACD+S, where the calculation method of s is A-constant\u0026times;0.5663-65.60. The value of A-constant is 119. If AG exceeds 13.5, it is calculated as 13.5; If r is less than 7, count it as 7. Here, AL represents the axial length (the distance from the corneal apex to the vitreoretinal interface) measured by ultrasound, R is the radius of corneal curvature, the anterior chamber depth (AG) represents the measurement before the surgery, denoted as aACD. Additionally, S signifies the space between the iris\u0026apos;s front and the intraocular lens\u0026apos;s optical plane.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e6.Data Analytics and Statistical Methodology:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e①The statistical analysis was conducted using SPSS version 26.0, with all data presented as mean values alongside their standard deviations. To evaluate shifts in axial length, corneal refractive power, and anterior chamber depth following the SMILE procedure, we employed a paired t-test for comparison.② In order to compare the estimated lens position (ELP) calculated by Holladay I and Haigis formula, we analyzed the measured data of IOLMaster and Pentacam before and after SMILE operation by paired t-test. Statistical significance is denoted by p-values below 0.05.③ The Pearson correlation coefficient was employed to examine the interplay between the alterations in anterior chamber depth, as assessed by both the IOLMaster and Pentacam, and the depth of corneal ablation pre and post SMILE surgery.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cstrong\u003e1.\u003c/strong\u003e\u003cstrong\u003ePatient Demographics (Age, Corneal Ablation Depth, Visual Acuity, Intraocular Pressure, and Refractive Power)\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThere are 35 participants in our study, with a total of 69 eyes (including 34 right eyes and 35 left eyes), including 19 boys (37 eyes) and 16 girls (32 eyes).Age span: 18-36, mean\u0026nbsp;\u0026plusmn;\u0026nbsp;SD: 21.43\u0026nbsp;\u0026plusmn;\u0026nbsp;4.72. During the operation, the corneal thickness ranged from 67 to 138\u0026nbsp;\u0026mu;m, with an average of 101.49\u0026plusmn;20.44\u0026nbsp;\u0026mu;m. After the operation, all corneal flaps were returned to their correct positions; there were no problems with them, and the cornea remained completely transparent. Before the operation, their UCVA LogMAR was 0.88\u0026plusmn;0.25, intraocular pressure was 16\u0026plusmn;2.11 mmHg, spherical power was-4.20\u0026plusmn;1.13 D, and cylindrical power was-0.40\u0026plusmn;0.30 D. One month after the operation, these values became better: UCVA LogMAR was-0.04\u0026plusmn;0.04, IOP was 10.54\u0026plusmn;2.43 mmHg, spherical power was-0.13\u0026plusmn;0.52 D, and cylindrical power was 0.02\u0026plusmn;0.39D. By the end of three months, the numerical values were more stable: UCVA LogMAR was-0.06\u0026plusmn;0.03, IOP was 10.33\u0026plusmn;1.65 mmHg, spherical lens power was 0.10\u0026plusmn;0.42 D, and cylindrical lens power was-0.10\u0026plusmn;0.39 D.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.\u003c/strong\u003e\u003cstrong\u003eAnterior Posterior SMILE Ocular Axial Length (AL) Comparison\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn this study, we delved into the pre- and post-SMILE surgery axial length (AL) and AL* (which is AL minus central corneal thickness) assessments using the IOLMaster. We analyzed data from 35 myopic patients (totaling 69 eyes). Results revealed that the patients\u0026apos; AL before surgery was 25.63\u0026plusmn;0.58 mm, which decreased to 25.55\u0026plusmn;0.59 mm at one month post-op and 25.54\u0026plusmn;0.59 mm at three months post-op. The surgical intervention resulted in a mean change of 0.08\u0026plusmn;0.21 mm from baseline to the one-month follow-up and 0.09\u0026plusmn;0.16 mm from baseline to the three-month assessment, with both outcomes proving statistically significant (P\u0026lt;0.05). However, no substantial difference emerged when comparing measurements at the one-month and three-month postoperative intervals (P\u0026gt;0.05). Turning to AL*, the baseline measurement stood at 25.08\u0026plusmn;0.58 mm, dipping slightly to 25.09\u0026plusmn;0.60 mm by the one-month mark before returning to 25.08\u0026plusmn;0.60 mm by three months post-surgery. The respective deviations from preoperative values of -0.01\u0026plusmn;0.21 mm and -0.01\u0026plusmn;0.15 mm failed to achieve statistical significance (P\u0026gt;0.05), nor did a meaningful difference materialize between the one-month and three-month AL* readings (P\u0026gt;0.05)(Tables 1 and 2).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.\u003c/strong\u003e\u003cstrong\u003eComparison of Anterior Chamber Depth (ICAD) Pre- and Post- SMILE Surgery\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.1Comparing Anterior Chamber Depth Measurements (ICACD and ECACD) Pre- and Post-SMILE Surgery via IOLMaster (ECACD = ICACD - Central Corneal Thickness).\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study cohort comprised 35 patients with myopia, totaling 69 eyes, who exhibited preoperative ICACD measurements averaging 3.80\u0026plusmn;0.24 mm. This metric nosedived to 3.66\u0026plusmn;0.24 mm at the one-month mark following surgery and stabilized at 3.67\u0026plusmn;0.23 mm by three months post-surgery. The pre-to-one-month delta came in at 0.13\u0026plusmn;0.07 mm, while the pre-to-three-month variation registered 0.12\u0026plusmn;0.09 mm. Although these changes passed the statistical muster (P\u0026lt;0.05), the comparison between one-month and three-month readings failed to show any significant divergence (P\u0026gt;0.05). On a parallel track, preoperative ECACD measurements stood at 3.25\u0026plusmn;0.24 mm, tapering off to 3.20\u0026plusmn;0.25 mm at one month and holding steady at 3.20\u0026plusmn;0.23 mm by three months post-surgery. Both the one-month (0.06\u0026plusmn;0.05 mm) and three-month (0.06\u0026plusmn;0.04 mm) differences proved statistically significant (P\u0026lt;0.05), mirroring the ICACD findings where no meaningful gap existed between the one-month and three-month ECACD values (P\u0026gt;0.05) (Tables 1 and 2).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2Pentacam-measured Anterior Chamber Depth Variations (ICACD and ECACD) Pre- and Post-SMILE Procedure\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn our Pentacam analysis of the SMILE procedure, we noted alterations in the anterior chamber depth, specifically the ICACD and ECACD, both before and after the procedure. Among the 35 patients (totaling 69 eyes) with myopia, the ICACD was measured at 3.75\u0026plusmn;0.24 mm before surgery, decreasing to 3.59\u0026plusmn;0.26 mm at one month and then stabilizing at 3.60\u0026plusmn;0.24 mm at three months post-op. The ICACD measurement demonstrated a notable difference from pre-op to one month post-op, which was 0.16\u0026plusmn;0.13 mm, and from pre-op to three months post-op, at 0.15\u0026plusmn;0.07 mm. Both of these differences were statistically significant (P\u0026lt;0.05). Nevertheless, the ICACD from one to three months post-op didn\u0026apos;t show any significant variation (P\u0026gt;0.05). In line with this, the ECACD was measured at 3.20\u0026plusmn;0.25 mm before surgery, shrinking to 3.13\u0026plusmn;0.26 mm after a month and remaining constant at 3.13\u0026plusmn;0.24 mm at three months. The discrepancy between the pre-op and one-month post-op ECACD was 0.08\u0026plusmn;0.13 mm, while the difference between pre-op and three-month post-op was 0.07\u0026plusmn;0.06 mm, both pointing to statistically significant changes (P\u0026lt;0.05). But again, there was no notable difference detected between the one-month and three-month post-op ECACD (P\u0026gt;0.05)(Tables 1 and 2).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.3Comparison of IOLMaster and Pentacam-measured Anterior Chamber Depth (ICACD) Pre- and Post-SMILE Surgery\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eStatistically significant differences (P\u0026lt;0.05) were observed between preoperative values and measurements at 1 and 3 months postoperatively for both the IOLMaster (ICACD) and Pentacam (ICACD). Furthermore, the ICACD readings obtained with the IOLMaster consistently exceeded those obtained with the Pentacam across all measurement time points (Table 4).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.4Anterior Chamber Depth Variations in Relation to Corneal Ablation Thickness\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo significant correlation was found between the Pentacam-measured difference in anterior chamber angle depth (ACAD) before and one month after surgery (n=35 eyes, 69 cases) and the depth of corneal ablation (r=0.15, P\u0026gt;0.05). Similarly, no significant correlation existed between the Pentacam-determined ACAD difference at the three-month postoperative interval and the corneal ablation depth (r=0.21, P\u0026gt;0.05). The same was true for the Master-observed ACAD variance at one month postoperatively when compared to the depth of corneal ablation (r=0.20, P\u0026gt;0.05), as well as for the three-month assessment (r=0.14, P\u0026gt;0.05) (Table3).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e4.Comparison of Keratometric Refractive Power Before and After SMILE Surgery\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e4.1Km Measurements with IOLMaster Before and After SMILE Surgery\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn a study involving 35 myopic patients with a total of 69 eyes, the preoperative K-value was 43.08\u0026plusmn;1.14D, decreasing to 38.96\u0026plusmn;1.25D after just a month of surgery and further settling at 38.98\u0026plusmn;1.22D by the three-month mark. These changes were statistically significant when comparing pre-op to one-month and three-month post-op readings (P\u0026lt;0.05). However, when comparing the one-month and three-month post-op K-values, the differences were negligible (P\u0026gt;0.05) (Tables 1 and 2).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e4.2SimK Variations in SMILE Procedures as Measured by Pentacam\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn our cohort of 35 myopia patients comprising 69 eyes, the preoperative SimK measurements averaged 42.82\u0026plusmn;1.16D, which nosedived to 38.86\u0026plusmn;1.27D at the one-month postoperative mark, before leveling off at 38.90\u0026plusmn;1.18D by the three-month check-in. The contrast between preoperative SimK values and those recorded at both one-month and three-month follow-ups was statistically significant (P\u0026lt;0.05), whereas the comparison between the one-month and three-month readings showed no meaningful difference (P\u0026gt;0.05) (Tables 1 and 2).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e4.3Comparison of pre- and post-SMILE surgery changes (Km) as measured by IOLMaster versus those (SimK) by Pentacam\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe preoperative discrepancy between Km and SimK measurements averaged 0.26\u0026plusmn;0.20D, which dropped to 0.20\u0026plusmn;0.10D one month post-surgery and further decreased to 0.17\u0026plusmn;0.08D by three months. Statistically significant differences were observed between Km and SimK values at all three time points (P\u0026lt;0.05) (Table 4).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e4.4Comparison of TCRP and SimK measurements before and after SMILE surgery using Pentacam\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBefore the operation, the TCRP was recorded at 42.22\u0026plusmn;1.17 diopters, while the SimK was 42.83\u0026plusmn;1.16 diopters. A month after the surgery, the TCRP dropped to 37.27\u0026plusmn;1.36 diopters, and the SimK to 38.86\u0026plusmn;1.27 D. By three months post-op, the TCRP was 37.42\u0026plusmn;1.25 diopters, and the SimK was 38.90\u0026plusmn;1.18 D. There was a notable difference in both TCRP and SimK values when comparing pre-op to one month and three months post-op, with the stats showing it was statistically significant (P\u0026lt;0.05)(Table 5).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e5.Comparison of ELP Pre- and Post-SMILE Surgery Using the Holladayl Formula\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e5.1IOLMaster Holladayl ELP Comparisons: Pre- versus Post-SMILE Procedure\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe Preoperative Effective Lens Position (ELP) was measured at 6.16\u0026plusmn;0.19 mm, dropping to 5.54\u0026plusmn;0.12 mm at one month post-surgery and stabilizing at 5.54\u0026plusmn;0.01 mm by three months. The preoperative Holladay I (ELP) values showed a statistically significant divergence from both the one-month and three-month postoperative readings (P\u0026lt;0.05). That said, when we compared the results at the one-month and three-month postoperative marks, we found no statistically meaningful distinction between them (P\u0026gt;0.05)(Table 7).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e5.2Pentacam ELP Comparison Using Holladayl Formula in SMILE Surgery\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePreoperative ELP was 6.12\u0026plusmn;0.19 mm, but nosedived to 5.52\u0026plusmn;0.12 mm one month post-surgery, then held steady at 5.52\u0026plusmn;0.11 mm by the three-month mark. The Holladay I (ELP) values showed that the difference between preoperative readings and both one-month and three-month postoperative measurements was statistically significant (P\u0026lt;0.05). That said, the one-month and three-month postoperative Holladay I (ELP) readings were pretty much in the same ballpark (P\u0026gt;0.05)(Table 7).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e5.3Comparison of IOLMaster and Pentacam Holladay I Formula Calculated ELP Before and After SMILE Surgery\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe preoperative discrepancy between the IOL Master Holladay I (ELP) and Pentacam Holladay I (ELP) was just 0.04\u0026plusmn;0.04 mm. One month post-surgery, the difference between the IOL Master\u0026apos;s Holladay I (ELP) and the Pentacam\u0026apos;s Holladay I (ELP) was only 0.01\u0026plusmn;0.01 mm, and this figure remained the same at 0.01\u0026plusmn;0.01 mm three months post-surgery. Notably, the differences between the IOLMaster and Pentacam measurements before and after one month, as well as after three months, were statistically significant (P\u0026lt;0.05) (Table 8).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e6.Pre- versus Post-SMILE Haigis-Derived ELP Comparison\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e6.1IOLMaster ELP Comparisons in SMILE Surgery Using Haigis Formula\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePrior to the procedure, the ELP was 5.98 millimeters with a margin of error of\u0026nbsp;\u0026plusmn;0.12. At one month post-op, it had shrunk to 5.92 millimeters, within the same\u0026nbsp;\u0026plusmn;0.12 margin. By the three-month check-in, it had maintained that 5.92 millimeter mark with a slightly tighter margin,\u0026nbsp;\u0026plusmn;0.11. A statistical evaluation revealed a significant difference between the pre-surgery and both the one-month and three-month post-surgery readings (P\u0026lt;0.05). Yet, there was no meaningful variance detected between the one-month and three-month post-op measurements (P\u0026gt;0.05)(Table 7).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e6.2Pentacam in Haigis Formula-Based SMILE Pre- and Postoperative ELP Comparison\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBefore undergoing the procedure, the ELP was 5.97\u0026plusmn;0.12 mm. A month after the surgery, the measurement dropped to 5.89\u0026plusmn;0.12 mm. Three months later, it stood at 5.90\u0026nbsp;\u0026plusmn;\u0026nbsp;0.12 mm. There was a notable difference in ELP between pre-op and both 1 and 3 months post-op, with P-values below 0.05. On the other hand, the difference between 1 and 3 months post-op wasn\u0026apos;t significant, as the P-value was above 0.05 (Table 7).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e6.3IOLMaster and Pentacam ELP Comparisons Using Haigis Formula in SMILE Procedures\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe preoperative discrepancy between the IOL Master Haigis (ELP) and Pentacam Haigis (ELP) measurements was 0.02\u0026plusmn;0.02 mm, whereas this gap widened slightly to 0.05\u0026plusmn;0.03 mm at the one-month postoperative mark and narrowed again to 0.03\u0026plusmn;0.03 mm by the three-month follow-up. Notably, all these differences between the two devices, both before surgery and at both postoperative timepoints, differed meaningfully (p\u0026lt;0.05) (Table 8).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e7.Holladayl and Haigis ELP Calculations: Preoperative vs. Postoperative SMILE Surgery Comparison\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e7.1Comparison of pre- and post-SMILE surgery ELPs calculated using the Holladay I and Haigis formulas with IOLMaster\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn a comparative study of the Holladay I ELP and the Haigis ELP preoperatively, there was a discrepancy of -0.39\u0026nbsp;\u0026plusmn;\u0026nbsp;0.16 mm between the two at one month post-op, and -0.39\u0026nbsp;\u0026plusmn;\u0026nbsp;0.15 mm at three months post-op. Statistical significance was observed for all comparisons\u0026mdash;before and after surgery, and at both 1 and 3 months postoperatively\u0026mdash;reaching P-values below 0.05 (Table 6).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e7.2Pentacam ELP Calculations Using Holladayl and Haigis Formulas Before and After SMILE Surgery\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePrior to SMILE surgery, the Holladay I (ELP) and Haigis (ELP) discrepancies measured 0.15\u0026plusmn;0.22 mm. Following surgery, at one month, this gap had widened to -0.37\u0026plusmn;0.17 mm, and at three months, it had stabilized at -0.37\u0026plusmn;0.16 mm. Comparing the Holladay I (ELP) values at one month and three months post-op to the pre-op readings, we saw significant differences in the Haigis (ELP) values (P\u0026lt;0.05) (Table 6).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eOur nation has the highest prevalence of myopia, and over the past two decades, refractive corneal surgery has gained immense popularity in our country. The SMILE procedure, in particular, has been validated for its safety, efficacy, and long-term stability[1], making it one of the primary surgical methods for correcting refractive error. Patients who undergo SMILE may face a shared challenge two to three decades later: the development of cataracts in the surgical eye. Accurately computing the power of the intraocular lens is a tough nut to crack in the field of ophthalmology, especially since the SMILE technique messes with the cornea\u0026apos;s shape. This tweak affects the front-to-back surface ratio and disrupts the correlation between corneal depth and the eye\u0026apos;s central axis. Common biometric methods are prone to errors, such as diopter measurement, axial alignment, and effective lens position, which can affect the accuracy of intraocular lens (IOL) power calculation [3]. For the calculation of IOL power, the accuracy of axial length is the most important, because a measurement error of 1 mm may lead to a deviation of 2.5 to 3.5 diopters [4]. Similarly, an error of 1 mm in the measurement of anterior chamber depth will lead to a difference of 1.5 diopters after operation [5], while an error of 1.00 diopters in the measurement of corneal curvature will lead to a deviation of 1.3 to 1.6 diopters in the estimation of IOL power [6]. Therefore, researchers have devoted significant effort to improve the accuracy of IOL power calculation for cataract patients who have undergone corneal refractive surgery and have developed various measurement methods and calculation formulas. Despite the continuous improvement in ophthalmology technology and the increasing complexity of formulas, Wang L\u0026apos;s team\u0026apos;s research found that methods such as Haigis-L, Wang Koch Maloney, and Shammas, which do not rely on past clinical data, are better than those that use all patient data [7]. This conclusion is consistent with the similar research done by McCarthy and others [8]. When measuring axial length, doctors primarily use ultrasound (A-scan) and optical devices, such as IOL-Master and Lenstar. The accuracy of these optical biometers in determining the axial length of the eyes has been fully proved in clinical practice [9]. However, there is a lack of research, both at home and abroad, on potential errors in the predicted lens position (ELP). As the third and fourth generation ELP formulas show, the main determinants of ELP are axial length, anterior chamber depth, and corneal refractive power. Therefore, most errors in ELP calculation can be traced back to these specific factors. To solve these problems, several methods are proposed: improving the accuracy of biometric parameter evaluation, strategically selecting appropriate measuring tools, and carefully selecting the optimal calculation formula for the intraocular lens. The following analysis will discuss these strategies in detail.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.\u003c/strong\u003e\u003cstrong\u003eEvaluation of Biological Parameters\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.1Axial Length (AL)\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eEven a 1 mm difference in axial length (AL) can lead to an error of 2.5 to 3.5 diopters [1], so accurate AL data must be used when calculating intraocular lens power. Instruments such as the IOL-Master are more accurate than traditional A-super technology eye-axis measurements. Clinical data show that if AL is accurately measured, postoperative refractive error can be reduced from 54% to 36%[11]. The accuracy of traditional contact A super-measuring eye axis is 0.10\u0026ndash;0.12mm [12], while IOL-Master can reach 0.01mm [9], and the result is more reliable. In addition, people with high myopia often have posterior scleral staphyloma, which distorts the smooth, uniform shape of the posterior segment of the eyeball, making measurements more difficult and results more variable [13-14]. The optical measurement technology of IOLMaster aligns with the natural anatomical distance from the anterior corneal surface to the center of the macula, and its built-in signal processing function improves the accuracy of axial length measurements. In our study measuring the axial length (AL) of patients undergoing SMILE surgery with IOL-Master, the postoperative value is always shorter than the preoperative value, but the change over different follow-up times is not obvious. This result is consistent with the reports of Wang et al. [15] and Spyridon et al. [16]. On the contrary, Xu et al. [17] measured the AL of 28 LASIK patients (55 eyes) with IOL-Master and contact A ultrasound and found that the postoperative AL measured by the two devices was significantly shorter. The observed shortening of AL seems to be related to the amount of corneal tissue removed during the operation. The analysis of AL*(AL* = AL-central corneal thickness) one month and three months after refractive surgery showed that there was no statistically significant change compared with the preoperative measurement, indicating that AL* remained stable. This means the distance between the corneal endothelium and the macula has not changed, further confirming that the decrease in AL is due to the removal of corneal tissue. In addition, our data showed that the posterior corneal surface did not move forward or backward after the SMILE operation, consistent with the findings of Wang et al. [15] and Wang L [18].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.2Anterior Chamber Depth (ICACD)\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA-scan biometrics is still a common method for evaluating the anterior chamber of the eye, but it requires contact with the cornea, which increases the risk of infection. Moreover, the results obtained with this method are often inconsistent, and its accuracy depends on the operators\u0026apos; skills and experience. Therefore, more and more people are now using non-contact measurement methods [19]. The characteristic of the Pentacam 3D anterior segment analyzer is that it doesn\u0026apos;t contact the cornea, greatly reducing the risk of contamination. In addition, the anterior chamber measurement data it provides has been shown to be very accurate and reliable [19]. Therefore, in this study, we aim to use the Pentacam system to measure anterior chamber depth in Chinese people with mild myopia and to further investigate this issue. Looking at it with a Pentacam, the anterior chamber is the space between the innermost layer of the cornea (the corneal endothelium) and the iris, pupil, and the front of the lens. In this study, anterior chamber depth is measured as the thickness of the middle corneal layer, allowing us to analyze the ICACD value obtained from Pentacam. Our results show that the ICACD value measured after the SMILE operation is shallower than before. However, in the follow-up one month and three months after the operation, these changes were not statistically significant, and the measured value was stable at (3.13 0.26) mm. This result is consistent with the previous research of Zhu et al. They examined anterior chamber depth in 138 eyes before and after LASIK/LASEK using the Pentacam system and found that depth decreased after both procedures [20]. In a similar study, Li et al. [21] used the Sirius anterior segment analyzer and the A-scan thickness gauge to measure the posterior corneal surface height, anterior chamber depth, and lens thickness of patients before and after refractive surgery. Their results show that the anterior chamber depth becomes shallower and the lens thickness increases after the operation, suggesting an inverse relationship between the two [21]. Therefore, our study also examined the ECCD before and after the SMILE operation (calculated as ICACD minus the cutting depth) and found that a shallow anterior chamber persisted after the SMILE operation. Because ECACD can accurately reflect the true anterior chamber depth (the distance from the posterior surface of the cornea to the anterior surface of the lens), we think that the decrease in ICACD after surgery is mainly due to the thickening of the lens after myopia correction. Importantly, we found no correlation between the depth of corneal ablation and the decrease in ICACD after operation, indicating that this phenomenon was not solely related to the cornea but also to important changes in the lens.\u003c/p\u003e\n\u003cp\u003eIOL-Master measures the depth of the anterior chamber using a method called slit beam projection, which involves shining light from the side of the eye, taking photos, and letting the computer system analyze the results. This measurement includes the distance from the front of the cornea to the lens, including the cornea\u0026apos;s thickness. After laser surgery for myopia, the anterior chamber will become shallow, and the cornea will change shape. Nawa [22] believes that the shallow depth of the anterior chamber after excimer laser surgery is related to the change of corneal shape and the magnifying effect of the imaging system. Our study found that the depth of corneal ablation is unrelated to a shallow anterior chamber. This shows that there are other reasons for a decrease in anterior chamber depth besides corneal ablation depth. Therefore, we compared the ECCD before and after the SMILE operation (that is, ICACD minus the cutting depth) and found that the ECCD became shallower after the operation. This raises the question of whether anterior chamber depth decreases after SMILE, a finding related to the lens. Wang Liang et al. [24] found that the shallow depth of the anterior chamber after LASIK was related to the thickening of the lens. In addition, previous studies [23-24] show that changes in eye accommodation ability can cause the lens to thicken and move forward, thereby reducing the depth of the anterior chamber. Therefore, the shallow ICACD observed after SMILE surgery may be due to several factors, including corneal tissue cut off during the operation, changes in lens thickness and position after the operation, and the magnifying effect of the imaging system during examination.\u003c/p\u003e\n\u003cp\u003eWe also compared and evaluated the two instruments used in this survey. The results showed a significant difference between the two methods at 1 and 3 months after SMILE (P\u0026lt;0.05). Before the operation, the depth of the anterior chamber (ICACD) measured by IOL-Master was higher than that measured by Pentacam, with a difference of 0.04-0.07 mm. After the operation, the gap was expanded to 0.07 0.08 mm. There may be several reasons why the ACD readings from these devices are inconsistent. First, the two devices use different measurement methods. Pentacam uses Scheimpflug technology to directly measure the depth of the anterior chamber (ECCD) and the central thickness of the cornea, while IOL-Master uses imaging technology plus corneal refractive power to calculate ICACD. Secondly, they are measured in different ways. When measuring ICACD, IOL-Master emits a 0.7 mm slit beam at an angle of 38, which passes through the cornea to form an optical section. The distance from the front surface of the cornea to the front surface of the lens is then calculated by the internal software. In this process, the visual axis and optical axis of the IOL-Master show a nasal deviation of 5, whereas Pentacam measures ECACD directly along the optical axis. Finally, the two devices have different definitions of ICACD. IOL-Master calculates the distance from the anterior surface of the cornea to the anterior surface of the lens, while Pentacam measures the distance from the posterior surface of the cornea to the anterior surface of the lens. To facilitate direct comparison, we added the CCT value to Pentacam\u0026apos;s readings, which may introduce some inaccuracy. Although there are obvious statistical differences between the two devices when measuring ACD, the difference of 0.1 mm only accounts for 2.7% of the average ICACD measured by them. Such a small difference has no effect on the actual medical treatment. Therefore, when measuring ICACD in myopia patients, both devices can be used, and the results are consistent with previous studies, indicating that Pentacam and IOL-Master have similar effects [25].\u003c/p\u003e\n\u003cp\u003eSimply put, this study used IOL-Master and Pentacam to measure the eye data before and after myopia surgery. The results showed that the axial length was shortened and the depth of the anterior chamber (ICACD) was also reduced. The change of axial length seems to be directly related to corneal ablation, while the change of anterior chamber depth (ICACD) may be related to surgical ablation depth, corneal healing after operation, and lens thickening. However, the specific reasons need more research. In addition, IOL-Master and Pentacam have similar effects in monitoring changes in anterior chamber depth (ICACD) after SMILE, indicating they can be used interchangeably in this case.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.3Keratometric mean (Km)\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe cornea is like a super-powerful lens, with two curved surfaces: the front and the back. The front curved surface contributes about +48D focusing power, while the rear curved surface provides about -5D refractive power. This is because the refractive power of corneal stroma (1.336) and aqueous humor (1.337) is slightly different. This shows that the anterior and posterior surfaces of the cornea are very important to its overall refractive function. At present, the equipment used to measure the cornea in eye clinics, such as keratometers, keratoscopes, and early topography machines, is mostly based on Gullstrand\u0026apos;s eye model. These devices usually use a fixed refractive index, n = 1.3375. Their working principle is to measure the curvature in front of the cornea, and then convert this curvature into diopters (in D) by the formula k=(n-1)/r, where K denotes the corneal refractive index, and R represents the curvature radius. However, this calculation is based on two key premises: first, the ratio of the front radius to the back radius is always about 82%, the corneal thickness is set to 500\u0026mu;m, and the front and back surfaces are regarded as a whole with a refractive index of 1.3375; Secondly, assuming that the cornea is perfectly spherical, the radius of curvature of the central area and the peripheral area (3-4 mm) has not changed significantly. Pentacam is a new development in an anterior segment diagnosis platform that uses Scheimpflug imaging technology to measure the posterior corneal surface for the first time. This advanced equipment can collect extensive data, including height maps of the anterior and posterior surfaces, axial and tangential curvature radii, and corneal thickness information point by point. In this way, ophthalmologists can more accurately evaluate the posterior corneal shape and track changes in corneal structure after refractive surgery. Simply put, Pentacam is like a rotating Scheimpflug camera that uses optical tomography to capture images of the front part of the eye. It can rotate a full circle in just 2 seconds and capture 50 images of corneal cracks simultaneously. From each image, this device can find 500 accurate height points on the cornea and collect more than 25,000 data points, enabling the generation of a three-dimensional image of the anterior segment of the eye [26]. Through its Scheimpflug camera, Pentacam can directly obtain the height map of the anterior and posterior surfaces of the cornea, and then calculate a lot of detailed information by mathematical methods, including the heights of the anterior and posterior surfaces, the axial and tangential curvatures, the thickness of the cornea, and the depth of the anterior chamber. Moreover, this technology can also help track the changes in various corneal measurements before and after surgery. Previous studies have confirmed that Pentacam data for measuring anterior segment parameters of the eye are reliable [27-28].\u003c/p\u003e\n\u003cp\u003eIOL-Master has always been the standard equipment for measuring corneal diopter in traditional cataract surgery, and it can accurately capture data from the normal cornea. However, if the corneal structure is abnormal, its measurement results will be unreliable [29-30]. Its working principle is: six hexagonal light spots are projected in the area with a diameter of 2.3 mm on the anterior surface of the cornea, and then the curvature radius of the anterior surface of this annular area is calculated by reflected light. After the SMILE operation, it can only measure the average corneal diopter of two symmetrical points in the central annular area, and it is impossible to know the situation outside this area. The problem is that the normal cornea is not a perfect sphere; its center appears spherical, while the edges are flatter (as shown in the topographic map).IOL-Master only measures the curvature of the anterior cornea. It assumes that the curvature radius of the posterior cornea is always 82.2% of that of the anterior cornea, thus forming a ratio of 1.2:1. It uses a formula Km=(1.3375-1) \u0026times; 1000/R and the usual refractive index of 1.3375 to calculate the diopter of the cornea. However, the corneal refractive index may be inaccurate, thereby affecting its reliability. Moreover, if the patient is uncooperative, has corneal leukoplakia, has severe lens opacity, or can\u0026apos;t maintain a steady gaze, the IOL-Master reading may be very inaccurate. Because the working principles of these two devices are fundamentally different, our research mainly uses IOL-Master (Km) and Pentacam (SimK) to measure corneal diopter before and after SMILE, and also compares Pentacam (SimK) data with Pentacam TCRP.According to the curvature of the 3 mm area in the center of the anterior surface of the cornea and the commonly used refractive index of 1.3375, the SimK value obtained by Pentacam is calculated by the Gaussian thin lens formula, which is the same as the Km value calculated by the standard corneal topographic map. To avoid potential systematic errors, IOLMaster also uses the same standard refractive index of 1.3375 when calculating Km. Our results show that the Km reading after operation is obviously larger than that measured by SimK, which is consistent with the research of Elbaz et al. [31], who reported that there is a difference of -0.47D between the two measurement methods; The research of Pan Hong et al [32] also supports this point, and they found a statistically significant difference of-0.49 D.The difference between Km and SimK values mainly comes from two reasons. First of all, IOL-Master and Pentacam use different measurement areas: IOL-Master looks at a range of 2.3 mm in the middle of the cornea, while Pentacam looks at a range of 3 mm in the middle. Because the refractive power of the middle part of the cornea is usually stronger before the operation, the reading of Km is 0.21 to 0.31D higher than that of SimK. Secondly, after SMILE surgery, the intermediate optical zone usually becomes flatter, altering the normal curvature relationship between the anterior and posterior corneal surfaces. Because both devices use the average refractive power in the middle region to represent the cornea\u0026apos;s axial refractive power, this change after surgery may lead us to overestimate the cornea\u0026apos;s true refractive power.For these patients, inaccurate measurements may lead to excessive farsightedness after cataract surgery [33]. Researchers such as Seitz and Qazi have found that Pentacam equipment can overestimate corneal refractive power after laser vision correction. Similarly, Savini and colleagues observed that the SimK reading on the Pentacam (39.82\u0026plusmn;1.51 D) was higher than the actual refractive power in 15 people who had undergone LASIK surgery. Schafer et al. also observed that IOLMaster equipment overestimated corneal refractive power after surgery in 58 eyes. Clinical evidence shows that both SimK and Km readings are lower than the refractive power really needed when choosing an intraocular lens, as mentioned in reference [33]. Our own data show that the value of Km is 0.05-0.15 D and 0.03-0.12 D higher than that of SimK one month and three months after operation, respectively. Despite the absence of an ideal technique for assessing corneal refractive strength post-surgically, Pentacam tends to report a lower postoperative refractive value, which may be closer to the actual postoperative refractive value.In addition, our study found that before and after the SMILE operation, there was a significant difference between the Pentacam-measured SimK and TCRP values, with TCRP consistently lower than SimK. This shows that the SimK from Pentacam does not account for the posterior corneal surface, and the ratio of the anterior to posterior corneal surfaces will change after SMILE surgery.Pentacam\u0026apos;s TCRP function uses ray tracing technology. According to Snell\u0026apos;s law,\u0026nbsp;\u003cbr\u003e\u0026nbsp;it determines the trajectory of collimated light through both the front and back corneal layers,and then determines the focal length and converts it into corneal refractive power. This method uses the true refractive indices: air (1), cornea (1.376), and aqueous humor (1.336). Corneal refractive power is calculated according to the formula K = n/f, where n is 1.336, and f is the focal length.The anterior surface of the cornea is the reference plane, and ray tracing technology does not depend on the assumed refractive index of the cornea to calculate curvature, so it can evaluate the true curvature of any specified corneal diameter.In addition, TCPR will comprehensively evaluate four key parts: anterior and posterior corneal layers, true refractive index, corneal asphericity (including spherical deviation), and the depth of the whole cornea. In this way, the cornea\u0026apos;s focusing ability can be evaluated more reliably, especially after laser vision correction surgery. Generally speaking, the corneal curvature readings measured by Pentacam after SMILE surgery are more reliable than the average curvature data measured by IOL-Master. Moreover, PentacamTCRP\u0026apos;s readings are more accurate than PentacamSimK\u0026apos;s measurements.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.Factors affecting ELP\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe evolution of intraocular lens power calculation methods has spanned four distinct phases. When dealing with cataract patients who haven\u0026apos;t had corneal refractive procedures, we\u0026apos;re able to precisely anticipate their preoperative refractive errors, a development that\u0026apos;s a win-win for both patients and medical professionals. But when it comes to eyes that have had prior corneal refractive surgery, the level of accuracy takes a nosedive. A crucial element in this equation is the Effective Lens Position (ELP), which essentially refers to the distance from the cornea\u0026apos;s front to the plane of the inserted lens. It is found that even a 1 mm error in ELP calculation can lead to a change in degree of about 1.5 to 2 diopters [34]. For eyes that have undergone myopia correction surgery, if the ELP is underestimated, a lower-power intraocular lens will be selected, and the patient will eventually become hyperopic. This result is consistent with the conclusion of our study [29,35]. In the past 10 years, more than 20 new calculation methods have been developed worldwide, all aimed at improving the prediction of intraocular lens power after this type of corneal surgery [36-37]. Recent studies have found that although the Hoffer-Q, Holladay, and SRK/T formulas yield similar results in predicting intraocular lens power, each method performs better at specific axial lengths [38-39]. The Hoffer-Q formula is most suitable for eyes with an axial length of 22 mm or less, while the Holladay formula works best in the range of 24.5 to 26 mm [40]. Interestingly, when the axial length is between 22.0 and 24.5 mm, the accuracy of the three formulas is almost the same, and none of them is obviously better. In our study, the axial length ranged from 22 to 27 mm, which was consistent with previous studies. An analysis of 77 eyes found no significant difference in refractive results among the Holladay1, Olsen, and SRK/T formulas [41]. A subsequent investigation involving 100 eyes ( averaging 22.89 mm in axial length ) determined that the Holladay I formula outperformed both the SRK/T and Hoffer Q formulas in terms of precision. [42]. A large-scale study of 8,018 eyes found that for eyes with an axial length of 22 to 26 mm, the results of the Holladay1 formula were slightly better or similar to those of the HofferQ and SRK/T formulas [43]. For the range of axial length from 22 to 27 mm, Haigis, Holladay I, and Hoffer Q formulas all perform very well, and the effect is almost the same [44]. In patients with an axial length of 24.5 to 27 mm, Haigis, SRK/T, and Holladay1 formulas can each give reliable predictions [45]. This conclusion was supported by Jiang et al. [46], who evaluated 169 cases and found no significant difference in prediction errors among the third-generation IOL formulas (SRK-T, Hoferq, Holladay-I, and Haigis). In this study, the Holladay and Haigis formulas are used to compare the accuracy of calculation methods for intraocular lens (IOL) power after refractive surgery. It further examined and compared the accuracy and determining factors of measuring corneal refractive power with Pentacam and IOL-Master equipment after refractive surgery.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe Holladay formula, in theory, is an improved method that uses axial length and average corneal refractive power to more accurately predict the Effective Lens Position (ELP). Holladay\u0026apos;s innovation in 1988 combined the patient-specific Anterior Chamber Depth (ACD) factor with the Fyodorov method, marking the beginning of the third-generation calculation formula. This method uses axial length and corneal refractive power to estimate corneal height, that is, the distance from the corneal endothelium to the iris plane. In this model, the depth of the anterior chamber is calculated by adding the corneal height, corneal thickness, and the distance from the anterior surface of the iris to the optical plane (SF) of the IOL. In order to achieve the best accuracy, this formula also adds a personalized \u0026quot;surgeon factor\u0026quot; to adjust the IOL model and other factors, such as the equipment for measuring the cornea, the position where the lens is placed during the operation, the wound suture method, and the technical level of the surgical team [47]. Haigis formula was introduced by Professor Haigis in 1991 [49]. It is widely used in Germany and is increasingly used in other parts of the world. This formula improves the accuracy of predicting the effect of vision correction after intraocular lens implantation. Like other third-generation theoretical formulas, Haigis model is a multivariate regression equation based on the concept of a thin lens. Its advantages include a detailed, practical description of anterior chamber depth [48] and an advanced method for calculating the effective crystal position (ELP). The terms M(ACDpro) and M(ALpro) denote average ELP and axial length, respectively, calculated from biometric data from a large group of patients who have undergone cataract surgery [49]. The coefficients a0, a1, and a2 are calibrated to take into account the characteristics of the intraocular lens, the axial length of the eye, and the depth of the anterior chamber, which makes the estimation of ELP more accurate [50].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThis research examined data from 35 patients (69 eyes) using two diagnostic tools\u0026mdash;the IOL-Master and Pentacam\u0026mdash;to assess corneal refractive power and anterior chamber depth before and after SMILE surgery. The Effective Lens Position (ELP) was computed using two separate formulas, and the outcomes were cross-compared. With the Holladay I formula, the IOL-Master\u0026rsquo;s ELP measurements averaged slightly higher than the Pentacam\u0026rsquo;s by 0.04\u0026plusmn;0.04 mm at one month, 0.01\u0026plusmn;0.01 mm at three months, and 0.01\u0026plusmn;0.01 mm at six months post-operation. Although statistically significant, this minor deviation\u0026mdash;just 1.3% of the mean ELP value\u0026mdash;is clinically insignificant and likely due to instrument variability and the limited cohort. Parallel trends emerged with the Haigis formula, where the IOL-Master\u0026rsquo;s ELP exceeded the Pentacam\u0026rsquo;s by 0.02\u0026plusmn;0.02 mm, 0.05\u0026plusmn;0.03 mm, and 0.03\u0026plusmn;0.03 mm at the same postoperative intervals. These differences may be caused by inaccurate instruments and too few subjects. The study also found that both Pentacam and IOL-Master Holladay I ELP were much higher (0.18\u0026plusmn;0.22 mm) before operation than Haigis ELP, but much lower (0.39\u0026plusmn;0.15 mm) after operation. When comparing the ELP calculated by the two formulas, Holladay I\u0026apos;s formula directly links the ELP with corneal refractive power, anterior chamber depth, and axial length. In this formula, the depth of the anterior chamber is calculated from the axial length and corneal refractive power, indicating that ELP is essentially determined by these two variables. In contrast, Haigis formula does not depend on corneal refractive power when calculating ELP, but directly uses anterior chamber depth and axial length. Because the IOL-Master equipment ensures the axial measurement accuracy of the two formulas, the difference of their ELP results mainly comes from the error of corneal refractive power and anterior chamber depth after SMILE surgery. Moreover, the ELP values calculated by these formulas were originally developed by the author based on specific assumptions and statistical results, and this process naturally introduces systematic and random errors [51-52]. The parameters used by Holladay I\u0026apos;s formula to predict ELP-corneal refractive power and axial length are easily adjusted across different measuring equipment [53]. Similarly, the predictive parameters of Haigis\u0026apos; formula, anterior chamber depth, and axial length, will also be affected by the inconsistency of measuring instruments [53].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThis study found that in 35 myopia patients (69 eyes), the effective lens position (ELP) moved forward by 0.63 \u0026plusmn; 0.18 mm after SMILE surgery, a statistically significant change. Previous studies have shown that when only cataract surgery is performed, the intraocular lens (IOL) position is very stable and rarely moves [80]. For example, Eom et al. observed that the IOL moved by only 0.06 to 0.11 mm after cataract surgery; this small change had no effect on the treatment [54]. Similarly, Corydon et al. also found that the displacement of IOL can be ignored (0.02 0.13 mm) after myopia laser surgery and cataract treatment, which is similar to the result of simple cataract surgery [55]. The stability of ELP mainly depends on the fixed position of the capsular bag, suspensory ligament, and ciliary body. Our study found that the effective lens position (ELP) of myopia patients shifted forward by 0.63 \u0026plusmn; 0.18 mm after SMILE surgery, indicating a significant change in ELP. This forward movement of ELP is consistent with the decrease in anterior chamber depth, indicating that ELP adjustment is directly related to this change. Therefore, the changes in ELP observed in our study appear to be due to a decrease in anterior chamber depth. This study has several limitations, including the lack of data at different postoperative time points. In addition, it is not clear whether the patient\u0026apos;s accommodation conditions will change over time, whether lens thickness will change, or whether there is a difference in anterior chamber depth between short-term and long-term postoperative evaluations. The small number of participants also means that systematic bias cannot be ruled out entirely. With ongoing advances in medical technology, managing cataracts after refractive surgery is increasingly challenging. By comprehensively analyzing the causes of inaccurate intraocular lenses in patients who have undergone prior refractive surgery, adopting the most advanced surgical methods, and combining our skilled surgical expertise with customized lens selection, we can finally help patients achieve the best visual outcome.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003e1. After the SMILE operation, we found that the axial length of the eyes became shorter and the anterior chamber depth became shallower. Although the shortening of axial length is related to cutting off a part of corneas, the shallowing of anterior chamber depth has nothing to do with how many corneas are cut off during surgery.\u003cp\u003e2.After SMILE operation, the axial length can be measured accurately with IOL-Master instrument, among which TCRP method is the most reliable, followed by SimK and Km. When measuring anterior chamber depth, Pentacam and IOL-Master are very reliable. \u003cp\u003e3.He shallowness of anterior chamber depth after SMILE surgery will lead to the doctor\u0026apos;s error in estimating the effective lens position, so the calculated intrinsic lens degree will be inaccurate, and finally the vision correction after cataract surgery will be biased.\u003c/p\u003e\n"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo external funding was obtained for this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eConceptualization: C. S., X.G.,B.Z.; Methodology: X.G. and Clinical studies demonstrate C. S.; Data curation:C. S. Formal analysis: X.G.,B.Z.,T.J.,C.T.; Writing-original draft preparation: C. S. Writing-review and editing: C. S. Supervision: X.G., B.Z\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study\u0026apos;s resulting datasets can be accessed from the principal investigator upon submission of a suitable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study\u0026apos;s methodology received approval from the Ethics Committee at the Second Hospital of Hebei Medical University and was conducted in full compliance with the Declaration of Helsinki. Because the research was designed to be prospective, every participant provided written informed consent, which was also approved by the same Ethics Committee.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eHuman ethics and informed consent statement: Applicable\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo competing interests are declared.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eBlumM,FlachA,KunertKS,etal.Five-year results of refractive lenticule extraction[J].Journal of Cataract \u0026amp; Refractive Surgery,2014,40(9):1425-1429.\u003c/li\u003e\n\u003cli\u003eAlbouganem C, Lavaud A,Amar R. SMILE:Refractive lenticule extraction for myopic correction[J].Journal Francais D Ophtalmologie,2015,38(3). \u003c/li\u003e\n\u003cli\u003eMasket S,Masket SE.Simple regression formula for intraocular lens power adjustment in eyes requiring cataract surgery after excimer laser photoablation.J Cataract Refract Surg 2006;32:430-434.\u003c/li\u003e\n\u003cli\u003eAkman A,Asena L,G\u0026uuml;ng SG. Evaluation and comparison of the new swept-source OCT-basedIOLMaster 700 with the IOLMaster500[J].British Journal of Ophthalmology, 2016, 100 (9): 1201-1205. \u003c/li\u003e\n\u003cli\u003eKoch DD.The Enigmatic Cornea and Intraocular Lens Calculations:The LXXIII EdwardJackson Memorial Lecture. Am J Ophthalmol,2016,171.\u003c/li\u003e\n\u003cli\u003eShammas HJ. Intraocular IOL power calculations(Illustrated).Thorofare, NJ: Slack Incorporated, 2004.\u003c/li\u003e\n\u003cli\u003eMcCarthy M,Gavanski GM,Paton KE,et al.Intraocular lens power calculations after myopiclaser refractive surgery:a comparison of methods in 173 eyes.Ophthalmology,2011,118:940-4.\u003c/li\u003e\n\u003cli\u003eWong CW,Yuen L,Tseng P,et al.Outcomes of the Haigis-L formula for calculating intraocular lens power in Asian eyes after refractive surgery.J Cataract Refract Surg,2015,41(3):607-12.\u003c/li\u003e\n\u003cli\u003eFang J, Ma H H. Clinical analysis of refractive status after intraocular lens implantation for complicated cataracts in high myopia[J]. Chinese Journal of Practical Ophthalmology, 1998, 16(7): 428-429.\u003c/li\u003e\n\u003cli\u003eOlsen T.Sources of error in intraocular lens power calculation.J Cataract Refract Surg,1992,18(2):125-129.\u003c/li\u003e\n\u003cli\u003eGarg A,Lin J,Latkany R,et al.. Mastering the techniques of IOL power calculations,2nd ed.New York:McGraw-Hill, 2009.\u003c/li\u003e\n\u003cli\u003eZhang Y L, Zhao Y E, Wang Q M. Evaluation of the accuracy of intraocular lens power measurement by optical coherence biometer[J]. Chinese Journal of Optometry \u0026amp; Ophthalmology, 2005, 7(1): 41-43.\u003c/li\u003e\n\u003cli\u003eYing L, Yao Z, Ma N. Application of combined A-mode and B-mode ultrasound in axial length measurement for intraocular lens power calculation in high myopia[J]. Journal of Clinical Ophthalmology, 2002, 10(6): 493-495.\u003c/li\u003e\n\u003cli\u003eWang L, Guo H K, Zeng J. Analysis of anterior chamber shallowing and its related factors after LASIK[J]. Recent Advances in Ophthalmology, 2012, 32(5): 464-466.\u003c/li\u003e\n\u003cli\u003eSpyridon E,Georgis A,Efstratios A,et al.. Axial eye length measurements pre-and post-laser-assisted in situ keratomileusis using the IOL Master:a pilot study[J].Clinical Ophthalmology,2010;4:1267-1269.\u003c/li\u003e\n\u003cli\u003eLam AKC, Rufina C, Woo GC, et al. Intra-observer and inter-observer repeatability of Anterior Eye Segment analysis system(EAS-1000)in anterior chamber configuration[J].Ophthalmic \u0026amp; Physiological Optics,2002, 22(6):552\u0026ndash;559.\u003c/li\u003e\n\u003cli\u003eQi Y Y, Zhang F J. Clinical application of optical coherence biometry [J]. Chinese Journal of Practical Ophthalmology, 2007, 25(8): 809.\u003c/li\u003e\n\u003cli\u003eHarper A R. The dynamic sclera:Extracellular matrix remodeling in normal ocular growth and myopia development.Experimental Eye Research,2015,133:100-11.\u003c/li\u003e\n\u003cli\u003eBaek TM,Lee KH,Kagaya F,et al. Factors affecting the forward shift of the posterior corneal surface after laser in situ keratomileusis[J].Ophthalmology,2001,108:317-320.\u003c/li\u003e\n\u003cli\u003eLi X Y. A study on dynamic changes in the anterior segment after excimer laser corneal refractive surgery[D]. Chongqing Medical University, 2014.\u003c/li\u003e\n\u003cli\u003eNawa Y.Corneal magnification[J].Ophthalmology,2008,115(3):588-588.\u003c/li\u003e\n\u003cli\u003eBolz M,Prinz A,Drexler W,et al.Linear relationship of refractive and biometric lenticular changes during accommodation in emmetropic and myopic eyes[J].Br J Ophthalmol,2007,91(3):360-365.\u003c/li\u003e\n\u003cli\u003eRead SA,Buehren T,Collins MJ.Influence of accommodation on the anterior and posterior cornea[J].J Cataract Refract Surge,2007,33(11):1877-1885.\u003c/li\u003e\n\u003cli\u003eJin H Y, Guo H K. Cataract surgery in patients with a history of corneal refractive surgery[J]. Foreign Medical Sciences Section of Ophthalmology, 2002, 26: 42-45.\u003c/li\u003e\n\u003cli\u003eSalouti R,Nowmozzadeh MH,Zamani M,et a1.Comparis on of anterior chamber depth measurements using Galilei,HR Pentacam and Orbscan II 0ptometry,2010,81:35-39.\u003c/li\u003e\n\u003cli\u003eLackner B, Schmidinger G,Pieh S,et al.Repeatability and Reproducibility of Central Corneal Thickness Measurement With Pentacam,Orbscan,and Ultrasound.Optom Vis Sci 2005;82(10):892-899.\u003c/li\u003e\n\u003cli\u003eMcAlinden C,Khadka J,Pesudovs K.A Comprehensive Evaluation of the Precision(Repeatability and Reproducibility)of the Oculus Pentacam HR.Invest Ophthalmol Vis Sci 2011;52(10):7731-7737.\u003c/li\u003e\n\u003cli\u003eElbaz U,Barkana Y,Gerber Y.Comparison of different techniques of anterior chamber depth and keratometric measurements.Am J Ophthalmol 2007; 143(1):48-53.\u003c/li\u003e\n\u003cli\u003eGimbel H,Sun R.Accuracy and predictability of intraocular lens power calculation after laser in situ keratomileusis.J Cataract Refract Surg 2001;27(4):571-576.\u003c/li\u003e\n\u003cli\u003eOlsen T. Calculation of power from the curvature of the cornea. Br J Ophthalmol 1986;70(2):152-154.\u003c/li\u003e\n\u003cli\u003ePan H, Wang L H, Ma LX. Comparison of corneal curvature and anterior chamber depth measurements between Pentacam and IOL Master[J]. Journal of Shandong University (Health Sciences), 2008, 46(6): 624-627.\u003c/li\u003e\n\u003cli\u003eReuland MS,Reuland AJ,Nishi Y,et al.Corneal radii and anterior chamber depth measurements using the IOL Master versus the Pentacam.J Refract Surg 2007;23(4):368-373.\u003c/li\u003e\n\u003cli\u003eSeitz B,Langenbucher A.Intraocular lens power calcuation in eyes after corneal refractive surgery.[J].J Refract Surg.2000,16(3):349-361.\u003c/li\u003e\n\u003cli\u003eShajari M,Cremonese C,Petermann K,et. Comparison of axial length,corneal curvature,and anterior chamber depth measurements of two recently introduced devices to a known biometer[J].American journal of ophthalmology,2017,178:58-64.\u003c/li\u003e\n\u003cli\u003eGimbel HV,Sun R,Furlong,et al.Accuracyand predictability of intraocularlens power calculation after photorefractive keratectomy[J].CataractRefract Surg.2000,26;1147-1151.\u003c/li\u003e\n\u003cli\u003eHolladay JT.Consultations in refractive surgery comment.Refract Corneal Surg 1989;5:203.\u003c/li\u003e\n\u003cli\u003eHaigis W.Strahldurchrechnung in GauB\u0026rsquo;scher Optik zur Beschreibung des System Brille-Kontaktlinse-Hornhaut-Augenlinse(IOL).Schott hrsg,v.K Jacobi KW,Freyler H,et al. Intraokularlinsen Implant[M].Berlin: Essen,1990:233-246. \u003c/li\u003e\n\u003cli\u003eJiang Y, Shi Y Y, Yang WL. Comparison of the accuracies of six intraocular lens power calculation formulas[J]. Ophthalmology in China, 2007, 16(2): 100-103.\u003c/li\u003e\n\u003cli\u003eSasaki H,Sakamoto Y,Harada S,et a1.Predicting postoperative anterior chamber depth in patients with cataracts using Scheimpflug slit photography[J].Ophthalmic Res,2002,34(5):265-272. \u003c/li\u003e\n\u003cli\u003eOlsen T．Improved accuracy of intraocular lens power calculation with the Zeiss IOL Master．Acta Ophthalmol Scand,2007,85(1)：84-87．\u003c/li\u003e\n\u003cli\u003eFindl O,Drexler W,Menapace R,et al.Improved prediction of intraocular lens power using partial coherence interferometry.J Cataract Refract Surg 2001;27(6):861-867.\u003c/li\u003e\n\u003cli\u003eEleftheriadis H.IOLMaster biometry:refractive results of 100 consecutive cases.Br J Ophthalmol 2003;87(8):960-963.\u003c/li\u003e\n\u003cli\u003eWang J-K,Chang S-W.Optical biometry intraocular lens power calculation using different formulas in patients with different axial lengths[J].International Journal of Ophthalmology(English Edition),2013,6(02):150-154.\u003c/li\u003e\n\u003cli\u003eChen F, Sheng Y H, Li Z Q. Comparison between SRK-Ⅱ formula and the third-generation intraocular lens power calculation formulas[J]. Chinese Journal of Practical Ophthalmology, 2000, 18(3): 139-142.\u003c/li\u003e\n\u003cli\u003eDu Y L, Jin C, Lin LY. Correlation between posterior staphyloma depth and postoperative refractive error in patients with high myopia complicated with cataracts [J]. Recent Advances in Ophthalmology, 2018, 38(11): 1070-1072.\u003c/li\u003e\n\u003cli\u003eShammas HJ,Shammas MC.No-history method of intraocular lens power calculation for cataract surgery after myopic laser in situ keratomileusis.J Cataract Refract Surg 2007;33:31-36.\u003c/li\u003e\n\u003cli\u003eHuang F, Zhao Y E, Huang H H. Accuracy of the Haigis formula in predicting postoperative refraction after cataract surgery[J]. Eye Research, 2008, 26(3): 225-227.\u003c/li\u003e\n\u003cli\u003eBiometrie HW. Yearbook of Ophthalmology 1995.In:Kampik A,editor.Optics and Refraction.Zuelpich:Biermann Verlag,1995.p.123-40. \u003c/li\u003e\n\u003cli\u003eHaigis W.The Haigis formula.In:Shammas HJ,editor.Intraocular lens power calculations.Thorofare,NJ,USA:Slack Inc,2003.p.41-57. \u003c/li\u003e\n\u003cli\u003eJack T.Intraocular lens power calculations for the refractive surgeon.[J]Operative Techniques in Cataract and Refractive Surgery,1998,1:105-117.\u003c/li\u003e\n\u003cli\u003eNorrby S.Sources of error in intraocular lens power calculation.J Cataract Refract Surg 2008;34:368-76.\u003c/li\u003e\n\u003cli\u003eNorrby S,Bergman R,Hirnschall N,et al.Prediction of the true IOL position.Br J Ophthalmol 2017;101:1440-6. \u003c/li\u003e\n\u003cli\u003eTamaoki A,Kojima T,Tanaka Y,et al. Prediction of effective lens position using multi-objective evolutionary algorithm. Transl Vis Sci Technol 2019;8.\u003c/li\u003e\n\u003cli\u003eEom Y,Kang SY,Song JS,et al.Comparison of the actual amount of axial movement of 3 aspheric inti-aocular lenses using anterior segment optical coherence tomography,J Cataract Refract Surg 2013;39:1528-1533.\u003c/li\u003e\n\u003cli\u003eOlsen T,Olesen H,Thim K,et al.Prediction of postoperative intraocular lens chamber depth.J Cataract Refract Surg 1990;16:587-590.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable 1\u003c/strong\u003e.\u0026nbsp;Biological parameters measured by two instruments before and after SMILE surgery (X\u0026plusmn;S)\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" style=\"width: 85px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 227px;\"\u003e\n \u003cp\u003ePentacam\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 242px;\"\u003e\n \u003cp\u003eIol-Master\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003ePreoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e1 month after the operation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e3 months after surgery\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003epreoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e1 month after surgery\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 81px;\"\u003e\n \u003cp\u003e3 months after the operation\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003eAL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e25.63\u0026plusmn;0.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e25.55\u0026plusmn;0.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 81px;\"\u003e\n \u003cp\u003e25.54\u0026plusmn;0.\u0026nbsp;59\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003eAL*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e25.08\u0026plusmn;0.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e25.09\u0026plusmn;0.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 81px;\"\u003e\n \u003cp\u003e25.07\u0026plusmn;0.60\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003eICACD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e3.75\u0026plusmn;0.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e3.59\u0026plusmn;0.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e3.60\u0026plusmn;0.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e3.79\u0026plusmn;0.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e3.66\u0026plusmn;0.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 81px;\"\u003e\n \u003cp\u003e3.67\u0026plusmn;0.23\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003eECACD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e3.20\u0026plusmn;0.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e3.13\u0026plusmn;0.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e3.13\u0026plusmn;0.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e3.25\u0026plusmn;0.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e3.20\u0026plusmn;0.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 81px;\"\u003e\n \u003cp\u003e3.20\u0026plusmn;0.23\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003eSimK/Km\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e42.83\u0026plusmn;1.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e38.86\u0026plusmn;1.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e38.90\u0026plusmn;1.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e43.08\u0026plusmn;1.14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e38.96\u0026plusmn;1.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 81px;\"\u003e\n \u003cp\u003e38.98\u0026plusmn;1.22\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003eTCRP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e42.22\u0026plusmn;1.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e37.27\u0026plusmn;1.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e37.42\u0026plusmn;1.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 81px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eAl: axial length (mm)Al * axial length - depth of cutting (mm)ICACD: depth of anterior chamber including corneal thickness (mm)ECACD: ICACD- depth of cutting (mm)Km: IOL Master corneal refractive power (D)SimK:Pentacam corneal refractive power (D)TCRP: total corneal refractive power (D)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2.\u0026nbsp;\u003c/strong\u003ePaired t-test of biological parameters measured by two instruments before and after SMILE surgery\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"6\" style=\"width: 255px;\"\u003e\n \u003cp\u003ePentacam\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"6\" style=\"width: 268px;\"\u003e\n \u003cp\u003eIol-Master\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width: 85px;\"\u003e\n \u003cp\u003e1 month after surgery VS before surgery\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 85px;\"\u003e\n \u003cp\u003e3 months after surgery VS before surgery\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 85px;\"\u003e\n \u003cp\u003e1 month after surgery VS 3 months after surgery\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 94px;\"\u003e\n \u003cp\u003e1 month after surgery VS before surgery\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 85px;\"\u003e\n \u003cp\u003e3 months after surgery VS before surgery\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 88px;\"\u003e\n \u003cp\u003e1 month after surgery VS 3 months after surgery\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 38px;\"\u003e\n \u003cp\u003ep\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 38px;\"\u003e\n \u003cp\u003ep\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 38px;\"\u003e\n \u003cp\u003ep\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003ep\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 38px;\"\u003e\n \u003cp\u003ep\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 49px;\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 39px;\"\u003e\n \u003cp\u003ep\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003eAL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 38px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 38px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 38px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e3.06\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e0.003\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e4.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 38px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 49px;\"\u003e\n \u003cp\u003e0.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 39px;\"\u003e\n \u003cp\u003e0.48\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003eAL*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 38px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 38px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 38px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e-0.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e0.80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e0.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 38px;\"\u003e\n \u003cp\u003e0.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 49px;\"\u003e\n \u003cp\u003e0.84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 39px;\"\u003e\n \u003cp\u003e0.41\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003eICACD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e9.80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 38px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e17.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 38px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e-0.56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 38px;\"\u003e\n \u003cp\u003e0.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e15.80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e10.85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 38px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 49px;\"\u003e\n \u003cp\u003e-0.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 39px;\"\u003e\n \u003cp\u003e0.68\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003eECACD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e4.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 38px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e8.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 38px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e-0.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 38px;\"\u003e\n \u003cp\u003e0.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e6.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e3.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 38px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 49px;\"\u003e\n \u003cp\u003e-0.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 39px;\"\u003e\n \u003cp\u003e0.80\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003eSimK\u003c/p\u003e\n \u003cp\u003e/Km\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e30.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 38px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e34.74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 38px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e-0.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 38px;\"\u003e\n \u003cp\u003e0.68\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e31.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 47px;\"\u003e\n \u003cp\u003e34.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 38px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 49px;\"\u003e\n \u003cp\u003e-0.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 39px;\"\u003e\n \u003cp\u003e0.75\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3.\u003c/strong\u003e Correlation analysis of ICACD changes and corneal cutting thickness before and after SMILE surgery\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"586\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" style=\"width: 284px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" style=\"width: 113px;\"\u003e\n \u003cp\u003eRange(mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 189px;\"\u003e\n \u003cp\u003eCorneal ablation thickness\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003er\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003ep\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003eDifference in MAster (ICACD) between pre-operation and 1 month post-operation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e0.11-0.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e0.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e0.11\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003eDifference in MAster (ICACD) between pre-operation and 3 months post-operation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e0.10-0.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e0.14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e0.25\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003eDifference between Pentacam before surgery and 1 month after surgery (ICACD)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e0.13-0.\u0026nbsp;19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e0.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e0.21\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003eDifference between Pentacam before surgery and 3 months after surgery (ICACD)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e0.13-0.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e0.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e0.08\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eCorrelation analysis between ICACD difference and corneal cutting thickness, *P\u0026lt;0.05，**P\u0026lt;0.01\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 4.\u0026nbsp;\u003c/strong\u003ePaired t-test of biological parameters measured by two instruments before and after SMILE surgery\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"604\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003epreoperativeSimK/Km\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e1 month after the operationSimK/Km\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e3 months after the operationSimK/Km\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003epreoperativeICACD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e1 month after the operationICACD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e3 months after the operationICACD\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003eIol-Master\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e43.08\u0026plusmn;1.14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e38.96\u0026plusmn;1.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e38.98\u0026plusmn;1.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e3.79\u0026plusmn;0.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e3.66\u0026plusmn;0.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e3.67\u0026plusmn;0.23\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003ePentacam\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e42.83\u0026plusmn;1.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e38.86\u0026plusmn;1.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e38.90\u0026plusmn;1.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e3.75\u0026plusmn;0.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e3.59\u0026plusmn;0.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e3.60\u0026plusmn;0.24\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e10.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e4.14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e3.68\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e4.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e4.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e6.50\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003ep\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eTable 5.\u0026nbsp;\u003c/strong\u003ePaired t-test of corneal refractive power measured by Pentacam before and after SMILE surgery\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"567\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 124px;\"\u003e\n \u003cp\u003ePentacam\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 160px;\"\u003e\n \u003cp\u003epreoperativeTCRP/SimK\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 141px;\"\u003e\n \u003cp\u003e1 month after the operationTCRP/SimK\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003e3 months after surgeryTCRP/SimK\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 124px;\"\u003e\n \u003cp\u003eTCRP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 160px;\"\u003e\n \u003cp\u003e42.22\u0026plusmn;1.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 141px;\"\u003e\n \u003cp\u003e37.27\u0026plusmn;1.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003e37.42\u0026plusmn;1.25\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 124px;\"\u003e\n \u003cp\u003eSimK\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 160px;\"\u003e\n \u003cp\u003e42.83\u0026plusmn;1.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 141px;\"\u003e\n \u003cp\u003e38.86\u0026plusmn;1.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003e38.90\u0026plusmn;1.18\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 124px;\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 160px;\"\u003e\n \u003cp\u003e-29.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 141px;\"\u003e\n \u003cp\u003e-36.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003e-48.24\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 124px;\"\u003e\n \u003cp\u003ep\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 160px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 141px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eTable 6.\u0026nbsp;\u003c/strong\u003ePaired t-test of ELP of two IOL calculation formulas measured by two instruments before and after surgery\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"576\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003ePentacam\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003epreoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e1month after the operation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e3 months after surgery\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003eIol-Master\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003epreoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 79px;\"\u003e\n \u003cp\u003e1 month after the operation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e3 months after the operation\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003eHolladayⅠELP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e6.11\u0026plusmn;0.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e5.52\u0026plusmn;0. 12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e5.53\u0026plusmn;0.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003eHolladayⅠELP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e6.16\u0026plusmn;0.\u0026nbsp;19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 79px;\"\u003e\n \u003cp\u003e5.54\u0026plusmn;0.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e5.54\u0026plusmn;0.01\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003eHaigis-L\u003c/p\u003e\n \u003cp\u003eELP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e5.97\u0026plusmn;0.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e5.89\u0026plusmn;0.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e5.90\u0026plusmn;0.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003eHaigis-L\u003c/p\u003e\n \u003cp\u003eELP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e5.98\u0026plusmn;0.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 79px;\"\u003e\n \u003cp\u003e5.92\u0026plusmn;0.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e5.92\u0026plusmn;0.11\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e5.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e-18.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e-19.49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e7.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 79px;\"\u003e\n \u003cp\u003e-20.09\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e-21.22\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003ep\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003ep\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 79px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eTable 7.\u003c/strong\u003ePaired t-test of ELP of two IOL calculation formulas measured by two instruments before and after surgery\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 58px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"6\" valign=\"top\" style=\"width: 263px;\"\u003e\n \u003cp\u003ePentacam\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"6\" valign=\"top\" style=\"width: 268px;\"\u003e\n \u003cp\u003eIol-Master\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width: 83px;\"\u003e\n \u003cp\u003e1 month after surgery VS before surgery\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 77px;\"\u003e\n \u003cp\u003e3 months after surgery VS before surgery\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 103px;\"\u003e\n \u003cp\u003e1 month after surgery VS 3 months after surgery\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 85px;\"\u003e\n \u003cp\u003e1 month after surgery VS before surgery\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 85px;\"\u003e\n \u003cp\u003e3 months after surgery VS before surgery\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 98px;\"\u003e\n \u003cp\u003e1 month after surgery VS 3 months after surgery\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 58px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 44px;\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 39px;\"\u003e\n \u003cp\u003ep\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 41px;\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 35px;\"\u003e\n \u003cp\u003ep\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 40px;\"\u003e\n \u003cp\u003ep\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48px;\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 37px;\"\u003e\n \u003cp\u003ep\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 51px;\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 34px;\"\u003e\n \u003cp\u003ep\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 54px;\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 44px;\"\u003e\n \u003cp\u003ep\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 58px;\"\u003e\n \u003cp\u003eHolladayI ELP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 44px;\"\u003e\n \u003cp\u003e29.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 39px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 41px;\"\u003e\n \u003cp\u003e32.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 35px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e-0.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 40px;\"\u003e\n \u003cp\u003e0.34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48px;\"\u003e\n \u003cp\u003e28.88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 37px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 51px;\"\u003e\n \u003cp\u003e32.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 34px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 54px;\"\u003e\n \u003cp\u003e-0.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 44px;\"\u003e\n \u003cp\u003e0.92\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 58px;\"\u003e\n \u003cp\u003eHaigis-L\u003c/p\u003e\n \u003cp\u003eELP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 44px;\"\u003e\n \u003cp\u003e10.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 39px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 41px;\"\u003e\n \u003cp\u003e16.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 35px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e-0.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 40px;\"\u003e\n \u003cp\u003e0.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48px;\"\u003e\n \u003cp\u003e13.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 37px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 51px;\"\u003e\n \u003cp\u003e11.08\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 34px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 54px;\"\u003e\n \u003cp\u003e-0.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 44px;\"\u003e\n \u003cp\u003e0.90\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eTable 8.\u003c/strong\u003ePaired t-test of ELP of two IOL calculation formulas before and after SMILE surgery\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"576\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 86px;\"\u003e\n \u003cp\u003epreoperative\u003c/p\u003e\n \u003cp\u003eHolladayI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003e1 month after surgery\u003c/p\u003e\n \u003cp\u003eHolladayI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e3 months after surgeryHolladayI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 74px;\"\u003e\n \u003cp\u003epreoperative\u003c/p\u003e\n \u003cp\u003eHaigis-L\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e1 month after surgery\u003c/p\u003e\n \u003cp\u003eHaigis-L\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e3 months after surgeryHaigis-L\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003eIol-Master\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 86px;\"\u003e\n \u003cp\u003e6.16\u0026plusmn;0.\u0026nbsp;19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003e5.5\u0026plusmn;0.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e5.54\u0026plusmn;0.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 74px;\"\u003e\n \u003cp\u003e5.98\u0026plusmn;0.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e5.92\u0026plusmn;0.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e5.92\u0026plusmn;0.11\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003ePentacam\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 86px;\"\u003e\n \u003cp\u003e6.12\u0026plusmn;0.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003e5.52\u0026plusmn;0.\u0026nbsp;12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e5.53\u0026plusmn;0.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 74px;\"\u003e\n \u003cp\u003e5.97\u0026plusmn;0.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e5.89\u0026plusmn;0.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e5.90\u0026plusmn;0.12\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 86px;\"\u003e\n \u003cp\u003e10.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003e5.34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e3.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 74px;\"\u003e\n \u003cp\u003e4.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e4.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e6.50\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003ep\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 86px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 74px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"effective lens position, corneal ablation depth, Haigis formula, HolladayI formula, axial length","lastPublishedDoi":"10.21203/rs.3.rs-8639765/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8639765/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eObjective:\u003c/strong\u003eThis study aims to investigate post-SMILE alterations in corneal refractive power, axial length, and anterior chamber depth, as well as examining the relationship between changes in anterior chamber depth and corneal ablation depth. By utilizing both Pentacam and IOL Master devices, researchers will input measurement data into the Holladay 1 and Haigis formulas to calculate and compare Estimated Lens Position (ELP) values. The objective is to provide accurate anterior segment parameters for patients undergoing corneal refractive surgery, thereby enhancing the precision of intraocular lens calculations.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethodology:\u003c/strong\u003eA large hospital of Hebei Medical University made a prospective study. The subjects are a group of people who have undergone SMILE surgery in the second half of 2020.Clinical examinations were made before operation and 1st and 3rd Month Post-Surgery, respectively, and the results of naked eye vision, diopter, intraocular pressure, slit lamp microscope examination, as well as data of Pentacam (corneal diopter, central corneal thickness, anterior chamber depth) and IOL-Master (corneal power, aqueous depth, axial length) were recorded. In addition, supplementary parameters such as corneal thickness and cutting depth were recorded. We used paired t test to compare the changes of corneal diopter, anterior chamber dimensions and axial measurement measured by Pentacam and IOL-Master before and after SMILE operation. The same method is also used to compare the estimated lens position (ELP) calculated from IOL-Master and Pentacam data according to Holladay I and Haigis formula, and p-value below 0.05 denotes significance. In addition, Pearson correlation coefficient was used to analyze the relationship between the changes of anterior chamber depth measured by IOL-Master and Pentacam before and after SMILE operation and the corneal ablation depth.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003eAt postoperative months 1 and 3, the measurement results of ALand（AL*） were notably dissimilar to preoperative measures (P\u0026lt;0.05). Whether measured by IOLMaster or Pentacam equipment, there were significant differences between ICACD and ECCD at 1 month and 3 months after operation (P\u0026lt;0.05). It should be noted that the ICACD value measured by IOLMaster is larger than that measured by Pentacam before and after operation. Similarly, the values of Km, SimK and TCRP were significantly different from those before operation at 1 month and 3 months after operation (P\u0026lt;0.05), and the values of Km were always higher than that of SimK, while that of SimK was higher than that of TCRP before and after operation. When the effective lens position (ELP) was calculated by Holladay I and Haigis formula using the data of IOLMaster or Pentacam, the results of Holladay I(ELP) and Haigis(ELP) were significantly different at 1 and 3 months post-surgery (P \u0026lt; 0.05). In addition, the estimated lens position (ELP) calculated by IOLMaster Haigis data is higher than that measured by Pentacam, and this trend is the same as that of Holladay I (ELP) calculated by IOLMaster before and after operation. Moreover, the ELP value measured by the same examination equipment always shows that the result of Haigis (ELP) after operation is higher than that measured by Holladay I (ELP).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion:\u003c/strong\u003e1.After the SMILE operation, we found that the axial length of the eyes became shorter and the anterior chamber depth became shallower. Although the shortening of axial length is related to cutting off a part of corneas, the shallowing of anterior chamber depth has nothing to do with how many corneas are cut off during surgery.2.After SMILE operation, the axial length can be measured accurately with IOL-Master instrument, among which TCRP method is the most reliable, followed by SimK and Km. When measuring anterior chamber depth, Pentacam and IOL-Master are very reliable. 3.He shallowness of anterior chamber depth after SMILE surgery will lead to the doctor's error in estimating the effective lens position, so the calculated intrinsic lens degree will be inaccurate, and finally the vision correction after cataract surgery will be biased.\u003c/p\u003e","manuscriptTitle":"Anterior Segment Parameter Analysis After SMILE Surgery and Its Impact on the Calculation of Effective Intraocular Lens Position","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-06 09:37:47","doi":"10.21203/rs.3.rs-8639765/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"597b5a79-42ec-4dcc-a143-640569ccdc9e","owner":[],"postedDate":"February 6th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-04-23T05:39:22+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-06 09:37:47","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8639765","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8639765","identity":"rs-8639765","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}