Exploring the changes of perceptual eye position after SMILE based on the virtual reality platform

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METHODS: A total of 141 patients participated in this prospective study. The patients were divided into three groups according to the degree of myopia: low myopic group ( equivalent spherical refraction ≤ 3.00D), moderate myopic group(3.00D 6.00D). The relationship of perceptual eye position was measured by the computer-controlled visual perception detection system before, 1 day, 1 week and 1 month after surgery to investigate the changes of perceptual eye position after SMILE. RESULTS: The differences in horizontal perceptual eye position were statistically significant at all time periods (X2=82.004, P<0.001), and the horizontal perceptual eye position improved at 1 day and 1 week postoperatively compared with that before surgery, but rebounded in January postoperatively. The differences in vertical perceptual eye position were statistically significant at all time periods (X2=38.59, P<0.001), and the vertical PEP improved at 1 day, 1 week, and 1 month postoperatively compared with the preoperative level, but the improvement was small. The difference between horizontal perceptual eye position and vertical perceptual eye position in all three groups was not statistically significant, and it can be concluded that the deviation of perceptual eye position after SMILE is not related to the degree of myopia. CONCLUSION: Most myopic patients have perceptual eye position shift before refractive correction, and SMILE surgery can improve the perceptual eye position shifts significantly in the early postoperative period, but the long-term results need to be further observed. perceptual eye position SMILE virtual reality myopia Figures Figure 1 1. Background Myopia, the most common eye disease in the world, has become a serious public health problem [1-3]. Holden et al. showed that there are currently 1.406 billion people with myopia worldwide, accounting for 22.9% of the global population, and it is expected that by 2050 there will be 47.58 billions people with myopia, accounting for about half of the global population [4]. Femtosecond Laser Small Incision Lenticule Extraction (SMILE), as one of the refractive correction methods, is considered as a fast and painless vision restoration and less SMILE is an intra-stromal keratomileusis procedure that uses a femtosecond laser to create a microlens by scanning between the corneal stroma and extracting the lenticular corneal tissue through a tiny corneal incision [12]. The cornea is the most densely distributed surface tissue for nerves in vivo, and incomplete nerve regeneration in the cornea after SMILE may lead to reduced corneal sensitivity and may transiently or chronically alter the functional integrity of the ocular surface [13-16]. Based on this study, we speculate that the visual discomfort experienced by patients after SMILE may result from the need for the neural pathways of the brain to receive visual information from the eye to readapt. Vision is a product of the entire visual pathway, where external light is projected onto the retina through the intraocular refractive system, where light signals are converted into electrical signals, and then transmitted by the optic nerve to the visual cortex, where they are integrated and processed into visual perceptual images in the visual centers of the brain [17-19]. Therefore, to understand the source of discomfort in patients after SMILE, the entire visual pathway, including the visual system of the brain, should also be considered. Perceptual eye positions (PEP), a visual perceptual function used to describe sensory binocular alignment, is a standard psychophysical method that reflects the state of eye position deviation under binocular separation conditions, that is, the ability of the brain center to control eye position, a concept first proposed by Zhao Guohong et al. in 2014 [20]. Traditional masking and corneal reflection methods do not detect bilateral PEP deficits, for example, in patients with non-amblyopia and non-strabismus who may not have significant strabismus but whose perceptual eye position may have deviated, so the use of perceptual eye position as an assessment index in this study may have greater clinical significance [21, 22]. The computer-controlled visual perception detection and evaluation system reveal subtle changes in eye position deviation by showing the results of perceptual eye position deviation through an easy-to-understand crossed-loop test based on brain vision studies. In contrast to traditional eye position detection methods, the computer-controlled visual perception detection and evaluation system uses red and blue glasses to perform binocular segmentation and uses pixels as units to respond to the degree of perceptual eye position shift [23, 24]. The smallest unit of binocular misalignment examined by the visual perception detection and evaluation system is 1 pixel, which is approximately equal to 0.04 prism degrees, and can objectively quantify the perceptual eye position shift more accurately. Previous studies have found varying degrees of perceptual eye position shift in patients with strabismus and amblyopia, but there is a lack of research on the changes of perceptual eye position in patients after SMILE. Therefore, this study compared the changes of perceptual eye position in patients after SMILE using the perceptual examination and evaluation system to investigate the effect of SMILE surgery on perceptual eye position [21, 25]. 2. Materials and methods 2.1 Patients. One hundred and forty-one myopic patients, 88 males and 53 females, with an average age of 21.22 ± 4.48 years (17 to 45 years), who underwent SMILE treatment in the ophthalmology department of the Affiliated Hospital of Southwest Medical University from June 2022 to September 2022 were selected. The inclusion criteria were age ≥ 17 years, refractive error not exceeding 0.50 D in the last two years, and exclusion of patients with amblyopia, dry eye and other major ocular diseases. The patients were divided into low myopic group (equivalent spherical refraction ≤ 3.00D) group, moderate group (3.00D 6.00D) group according to low, moderate, and high refractive power. Finally, 20 patients were included in the mild myopia group, 83 patients were included in the moderate myopia group, and 38 patients were included in the high myopia group (see Table for summary demographics ). All patients completed written informed consent before inclusion in the study. All study protocols were approved by the Medical Ethics Committee of the Affiliated Hospital of Southwest Medical University and were performed following the Helsinki Declaration on Ethical Principles for Human Research. 2.2 Surgical procedure All patients underwent a standard SMILE procedure by the same surgeon, using a VisuMax (Carl Zeiss Meditec, Germany) 500 kHz femtosecond laser system for each of the patient's eyes. Postoperative medications: tobramycin dexamethasone eye drops, levofloxacin eye drops, flumethasone eye drops, and non-preservative artificial tears. 2.3 Measurement of perceptual eye position The equipment used to measure PEP included: Android system tablet PC, a resolution of 1920 * 1200, a refresh frequency of 120HZ ,and red and blue split-vision glasses. The visual perception detection and evaluation system developed by the National Healthcare Apparatus Engineering Technology Research Center was used, and the stimulus templates in the examination model were generated by MATLAB. The examinations were performed at constant room luminance, and all patients wore red and blue glasses for the perceptual eye position examination. The patients' PEP was measured by a cross-in-circle test in which the patient was allowed to see a cross in the left eye and a circle in the right eye (Figure 1,2). Before the test began ensure that the patient was 80 cm away from the screen and adjust the seat height to ensure that each patient's eyes were equal to the exact center of the monitor at the time of measurement. Patients use the mouse to position it at what they believe to be the center of the circle and subsequently click the mouse one by one. The system will record the patient's vertical and horizontal deviations in all directions in order to observe the perceptual control, direction of the deviation and size of deviation of both eyes under different temporal and spatial conditions. 2.4 Statistical analysis Statistical analyses were performed using SPSS software (version 23.0; SPSS, Inc, Chicago,IL), with normally distributed data expressed as mean ± standard deviation and abnormally distributed data expressed as median (P25, P75). Two-way comparisons were performed using the Friedman test, and the Bonferroni method was used to correct for significance, with P values <0.05 considered statistically significant. 3. Results 3.1 Study population A total of 282 eyes of 141 patients aged between 17 and 45 years were included in this study, with a mean patient age of 21.12±4.84 years, including 20 cases in the mild myopia group, 83 cases in the moderate myopia group, and 38 cases in the high myopia group, with no statistically significant differences between the three groups in terms of gender (P=0.344) and age (P=0.3) (see Table 1 for a summary of demographics ). Low myopia group Moderate myopia group High myopia group P Patients a 20 83 38 Gender (Male: Female) a 13：7 55：28 20：18 0.344 Age b 19.75±0.83 20.95±0.48 22.26±0.94 0.3 Spherical equivalent 2.03±0.16 4.14±0.96 6.45±0.15 Table 1 Summary Demographics of Patients in the Study a Numbers of subjects b Average years of age at first diagnosis 3.2 Comparison of horizontal PEP between different groups The horizontal perceptual eye quartiles of the 3 groups were as follows (Table 2), and the differences in horizontal PEP between the 3 groups were not statistically significant on preoperative, 1 day postoperative, 1 week postoperative, and 1 month postoperative (P=0.189; P=0.173; P=0.213; P=0.246), and it can be concluded that the changes in horizontal PEP were not related to the degree of myopia. Using the Friedman test performed as follows (Table 3), the difference in horizontal PEP was statistically significant in patients at all periods (X2=82.004, P<0.001), and the horizontal PEP improved at 1 day and 1 week postoperatively compared with the preoperative period, but rebounded in January postoperatively. Before 1 day postoperative 1 week postoperative 1 month postoperative Low myopia group 10.67（8.58，21.41） 8.67（5.35，10.91） 8.09（4.56，12.64） 12.5（8.42，19.24） Moderate myopia group 18.33（10.42，47.83） 11.91（6.41，19.82） 10（6.08，18.67） 16（9.17，29） High myopia group 14.15（9.39，38.87） 8.99（6.29，18.54） 10.27（6.16，17.1） 12.17（8.6，23.49） Table 2 Comparison of horizontal perceptual eye position in 3 groups Before-1 day postoperative Before-1 week postoperative Before-1 month postoperative Before-1 day-1 week postoperative Before-1 day-Before-1 month 1 week postoperative-Before-1 month P ＜0.001 ＜0.001 0.096 0.831 ＜0.001 ＜0.001 P value < 0.05 was considered statistically significant Table 3 Two-by-two comparison of horizontal perceptual eye position at different periods 3.3 Comparison of vertical PEP between different groups The vertical perceptual eye quartiles of the 3 groups were as follows (Table 4), and the differences in vertical PEP between the 3 groups were not statistically significant on preoperative, 1 day postoperative, 1 week postoperative, and 1 month postoperative (P=0.131; P=0.85; P=0.367; P=0.349), and the two-way comparison using the Friedman test was as follows (Table 5), and the differences in horizontal PEP of patients at each time period were statistically significant (X2=38.59, P<0.001), and the vertical PEP at 1 day, 1 week, and 1 month postoperatively were all elevated compared to preoperatively, but the elevation was smaller. Before 1 day postoperative 1 week postoperative 1 month postoperative Low myopia group 4.67（3.41，6.85） 4.67（3.95，6.31） 3.52（2.65，5.8） 4（3.04，5.29） Moderate myopia group 6（4.08，10.17） 4.67（3.75，6） 4.28（3.33，5.67） 4.67（3.33，5.29） High myopia group 6.5（4.67，8.83） 5.2（3.46，6.7） 4.02（3.27，5.91） 4（3.31，5.89） Table 4 Comparison of horizontal perceptual eye position in 3 groups at different periods Before-1 day postoperative Before-1 week postoperative Before-1 month postoperative Before-1 day-1 week postoperative Before-1 day-Before-1 month 1 week postoperative-Before-1 month Before-1 day postoperative P ＜0.001 ＜0.001 0.096 0.831 ＜0.001 ＜0.001 ＜0.001 P value < 0.05 was considered statistically significant Table 5 Two-by-two comparison of vertical perceptual eye position at different periods 4. Discussion Binocular vision is not exactly the same as the visual function that we think of as the visual function that humans value when performing object recognition and processing in traditional ophthalmology; it includes both the visual function part of traditional ophthalmology and part of the functional vision aspects. Not only visual acuity, but also binocular functional vision, such as stereo vision, perceptual eye position and binocular suppression system, which is integrated by information from the brain [24]. Most studies have investigated the discomfort of patients after SMILE based on traditional visual function tests, visual quality instruments, and dry eye examinations, but few studies have investigated postoperative binocular visual function [26-30]. Previous studies have found changes in stereoscopic vision after SMILE, but there are no studies on changes in perceptual eye position after SMILE [31]. Therefore, in the present study, we compared perceptual eye position in patients with different degrees of myopia after SMILE to investigate whether deviations in perceptual eye position are related to SMILE surgery and the occurrence of their degree of myopia, complementing the existing studies related to binocular vision after SMILE. This study found an improvement in horizontal PEP and no significant change in vertical PEP changes in patients after SMILE. The improvement in the horizontal PEP at both one day and one week postoperatively may indicate that the visual center of the brain has enhanced control of eye position postoperatively and that the brain perception level has increased to control the position of the eye. In contrast, the horizontal PEP did not improve at one month postoperatively, and we speculate that the newly established neural reflex pathways may require longer and repetitive training. This suggests that we should also strengthen PEP training in the postoperative period to help patients regain good eye position as soon as possible. PEP differs from conventional eye position in that this eye position deviation may better reflect the ability of the visual center of the brain to control eye position in the divided vision state, and abnormalities in PEP are more indicative of the state and degree of impairment of central perceptual function [20]. In children with normal corrected visual acuity and normal eye position, the mean vertical PEP was 1 to 3 pixels, while the mean horizontal PEP was 4 to 8 pixels; however, in amblyopic children, the deviation of PEP pixels was much higher than this and depended on the severity of amblyopia; for this reason, our study excluded patients with monocular amblyopia to maintain homogeneity of the patients' PEP tests [32]. The results of our experiment found statistically significant horizontal PEP comparisons and no statistically significant vertical PEP comparisons in patients after SMILE, contrary to the results of Yang et al [23]. By comparing myopic patients with severe refractive error with those without refractive error, Yang's team found that the two groups had statistically significant comparisons of results between vertical PEP, while there was no statistically significant comparison in horizontal PEP. Their results suggest that patients with a severe refractive error have unstable vertical PEP, and thus speculate that instability in vertical perceptual eye position may be related to the development of severe refractive error. In our study, on the other hand, we found an improvement in horizontal PEP after surgery, and therefore ventured to speculate that the instability of horizontal PEP might be related to refractive correction. Similarly, this inspires us to pay more attention to the changes in vertical perceptual eye position in patients with concomitant refractive aberrations, to consider whether to make relevant interventions before surgery, and to follow up well after surgery. The limitation of this study is that the sample size is too small and the observation time is only one month after surgery, which can only reflect the changes of PEP in the early postoperative period after SMILE. In the future, this study should expand the sample size and continue to extend the observation period to further investigate the changes of PEP in patients after SMILE, and provide PEP training to patients when necessary to help restore good eye position as soon as possible. In conclusion, the results of the small sample suggest that the PEP shift is not only limited to patients with strabismic amblyopia, but also exists in patients with refractive error, and the SMILE procedure can improve the PEP shift, and the long-term results remain to be further observed. Conclusion In conclusion, by using virtual reality technology, We found Most myopic patients have perceptual eye position shift before refractive correction, and SMILE surgery can improve the perceptual eye position shifts significantly in the early postoperative period, but the long-term results need to be further observed. Declarations Acknowledgements Not applicable. Authors’ contributions LLB and KXM analyzed the data and write the manuscript.LLB performed the statistical analysis. LLB and KXM collected the data. HJT and GL designed part of the study, as well as revised and polish the manuscript. LHB designed the study and analyzed the data. All authors read and approved the final manuscript. Funding. This study is supported by Science and Technology Program of SiChuan of China(N0.2020JDKP0072). Availability of data and materials The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request. Ethics approval and consent to participate The study protocol was approved by the Affiliated Hospital of Southwest Medical University. A written informed consent was obtained from each patient before surgery. All methods were carried out in accordance with relevant guidelines and regulations. Consent for publication Not applicable. Competing interests All authors declare that they have no competing interests. References Baird, P.N., et al., Myopia. Nat Rev Dis Primers, 2020. 6 (1): p. 99.DOI: 10.1038/s41572-020-00231-4 Modjtahedi, B.S., et al., Public Health Burden and Potential Interventions for Myopia. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-2237873","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":151894649,"identity":"c365fe05-03c4-4cf7-a616-dacfe2714923","order_by":0,"name":"linbi Luo","email":"","orcid":"","institution":"Hospital of Southwest Medical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"linbi","middleName":"","lastName":"Luo","suffix":""},{"id":151894650,"identity":"29cda4d1-3453-4dac-8016-45ec5fff9b72","order_by":1,"name":"Xiangmei kong","email":"","orcid":"","institution":"Hospital of Southwest Medical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Xiangmei","middleName":"","lastName":"kong","suffix":""},{"id":151894651,"identity":"6d396329-dbdd-4df0-9cb1-eda3d1eeb9f6","order_by":2,"name":"Junting Huang","email":"","orcid":"","institution":"Sichuan Academy of Medical Sciences \u0026 Sichuan Provincial People's Hospital","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Junting","middleName":"","lastName":"Huang","suffix":""},{"id":151894652,"identity":"0236ec57-fa2f-40ca-b7bb-3fa9f5e75e2c","order_by":3,"name":"Lu Guo","email":"","orcid":"","institution":"Hospital of Southwest Medical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Lu","middleName":"","lastName":"Guo","suffix":""},{"id":151894653,"identity":"0f6b44ee-77da-448d-a1f0-160a01ee77e5","order_by":4,"name":"Hongbin Lv","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA/0lEQVRIiWNgGAWjYHACxgMJDAwyDBIgZoMEAz8z8+EHhPQAtRjwwLVItrOlGRDUwoDQAmSe51GQwKecn/2MwYEHf/7wGNxuPvbw6w6LPOPDPAwGDDU20bi0SPbkGBxIbDPgMbhzLN1Y9oxEsdlh3gMPGI6l5Tbg0GJwgweopcGAR3JGjpm0ZJtE4rbDfAkGjA2H8WtJ+IOkZXMzj4EEYS1sBjz8Ejlmkh+BWjYwE9Ai2ZNWAPSLMVBLWpo04xmJxBmHgYGcgMcv/OyHNz788UdOjk0i+Zjkzx11if39hw8/+FBjg1MLCmDmgbESiFEOAow/iFU5CkbBKBgFIwoAAOTDWLsxkmH0AAAAAElFTkSuQmCC","orcid":"","institution":"Hospital of Southwest Medical University","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Hongbin","middleName":"","lastName":"Lv","suffix":""}],"badges":[],"createdAt":"2022-11-04 11:30:28","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-2237873/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-2237873/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":29246077,"identity":"636a2ea1-d865-4556-8ac5-c33fe9614d8f","added_by":"auto","created_at":"2022-11-18 15:42:44","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":59659,"visible":true,"origin":"","legend":"\u003cp\u003e1, 2 Example of a cross-in-circle test. Wearing red and blue divided vision glasses, patients will see a cross in their left eye and a circle in their right eye. They are asked to use a computer mouse to place the cross in their subjective view of the center of the circle and then click the mouse. The system automatically records the horizontal and vertical offset pixels.\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-2237873/v1/9be0d964bdb98e6c9f58d24d.jpeg"},{"id":37061121,"identity":"7aa51527-638d-479e-a28d-62aa92f8c393","added_by":"auto","created_at":"2023-05-16 02:14:35","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":199389,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-2237873/v1/d3cf8400-09f1-4a6a-a04c-912d07505d93.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Exploring the changes of perceptual eye position after SMILE based on the virtual reality platform","fulltext":[{"header":"1. Background","content":"\u003cp\u003eMyopia, the most common eye disease in the world, has become a serious public health problem [1-3]. Holden et al. showed that there are currently 1.406 billion people with myopia worldwide, accounting for 22.9% of the global population, and it is expected that by 2050 there will be 47.58 billions people with myopia, accounting for about half of the global population [4]. Femtosecond Laser Small Incision Lenticule Extraction (SMILE), as one of the refractive correction methods, is considered as a fast and painless vision restoration and less SMILE is an intra-stromal keratomileusis procedure that uses a femtosecond laser to create a microlens by scanning between the corneal stroma and extracting the lenticular corneal tissue through a tiny corneal incision [12]. The cornea is the most densely distributed surface tissue for nerves in vivo, and incomplete nerve regeneration in the cornea after SMILE may lead to reduced corneal sensitivity and may transiently or chronically alter the functional integrity of the ocular surface [13-16]. Based on this study, we speculate that the visual discomfort experienced by patients after SMILE may result from the need for the neural pathways of the brain to receive visual information from the eye to readapt. Vision is a product of the entire visual pathway, where external light is projected onto the retina through the intraocular refractive system, where light signals are converted into electrical signals, and then transmitted by the optic nerve to the visual cortex, where they are integrated and processed into visual perceptual images in the visual centers of the brain [17-19]. Therefore, to understand the source of discomfort in patients after SMILE, the entire visual pathway, including the visual system of the brain, should also be considered.\u003c/p\u003e\n\u003cp\u003ePerceptual eye positions (PEP), a visual perceptual function used to describe sensory binocular alignment, is a standard psychophysical method that reflects the state of eye position deviation under binocular separation conditions, that is, the ability of the brain center to control eye position, a concept first proposed by Zhao Guohong et al. in 2014 [20]. Traditional masking and corneal reflection methods do not detect bilateral PEP deficits, for example, in patients with non-amblyopia and non-strabismus who may not have significant strabismus but whose perceptual eye position may have deviated, so the use of perceptual eye position as an assessment index in this study may have greater clinical significance [21, 22]. The computer-controlled visual perception detection and evaluation system reveal subtle changes in eye position deviation by showing the results of perceptual eye position deviation through an easy-to-understand crossed-loop test based on brain vision studies. In contrast to traditional eye position detection methods, the computer-controlled visual perception detection and evaluation system uses red and blue glasses to perform binocular segmentation and uses pixels as units to respond to the degree of perceptual eye position shift [23, 24]. The smallest unit of binocular misalignment examined by the visual perception detection and evaluation system is 1 pixel, which is approximately equal to 0.04 prism degrees, and can objectively quantify the perceptual eye position shift more accurately. Previous studies have found varying degrees of perceptual eye position shift in patients with strabismus and amblyopia, but there is a lack of research on the changes of perceptual eye position in patients after SMILE. Therefore, this study compared the changes of perceptual eye position in patients after SMILE using the perceptual examination and evaluation system to investigate the effect of SMILE surgery on perceptual eye position [21, 25].\u003c/p\u003e"},{"header":"2. Materials and methods","content":"\u003cp\u003e2.1 Patients.\u003c/p\u003e\n\u003cp\u003eOne hundred and forty-one myopic patients, 88 males and 53 females, with an average age of 21.22\u0026nbsp;\u0026plusmn;\u0026nbsp;4.48 years (17 to 45 years), who underwent SMILE treatment in the ophthalmology department of the Affiliated Hospital of Southwest Medical University from June 2022 to September 2022 were selected. The inclusion criteria were age\u0026nbsp;\u0026ge;\u0026nbsp;17 years, refractive error not exceeding 0.50 D in the last two years, and exclusion of patients with amblyopia, dry eye and other major ocular diseases. The patients were divided into low myopic group (equivalent spherical refraction\u0026nbsp;\u0026le;\u0026nbsp;3.00D) group, moderate group (3.00D \u0026lt; equivalent spherical refraction\u0026nbsp;\u0026le;\u0026nbsp;6.00D), and high myopic group(equivalent spherical refraction \u0026gt; 6.00D) group according to low, moderate, and high refractive power. Finally, 20 patients were included in the mild myopia group, 83 patients were included in the moderate myopia group, and 38 patients were included in the high myopia group (see Table for summary demographics ). All patients completed written informed consent before inclusion in the study. All study protocols were approved by the Medical Ethics Committee of the Affiliated Hospital of Southwest Medical University and were performed following the Helsinki Declaration on Ethical Principles for Human Research.\u003c/p\u003e\n\u003cp\u003e2.2 Surgical procedure\u003c/p\u003e\n\u003cp\u003eAll patients underwent a standard SMILE procedure by the same surgeon, using a VisuMax (Carl Zeiss Meditec, Germany) 500 kHz femtosecond laser system for each of the patient\u0026apos;s eyes. Postoperative medications: tobramycin dexamethasone eye drops, levofloxacin eye drops, flumethasone eye drops, and non-preservative artificial tears.\u003c/p\u003e\n\u003cp\u003e2.3 Measurement of perceptual eye position\u003c/p\u003e\n\u003cp\u003eThe equipment used to measure PEP included: Android system tablet PC, a resolution of 1920 * 1200, a refresh frequency of 120HZ ,and red and blue split-vision glasses. The visual perception detection and evaluation system developed by the National Healthcare Apparatus Engineering Technology Research Center was used, and the stimulus templates in the examination model were generated by MATLAB. The examinations were performed at constant room luminance, and all patients wore red and blue glasses for the perceptual eye position examination. The patients\u0026apos; PEP was measured by a cross-in-circle test in which the patient was allowed to see a cross in the left eye and a circle in the right eye (Figure 1,2). Before the test began ensure that the patient was 80 cm away from the screen and adjust the seat height to ensure that each patient\u0026apos;s eyes were equal to the exact center of the monitor at the time of measurement. Patients use the mouse to position it at what they believe to be the center of the circle and subsequently click the mouse one by one. The system will record the patient\u0026apos;s vertical and horizontal deviations in all directions in order to observe the perceptual control, direction of the deviation and size of deviation of both eyes under different temporal and spatial conditions.\u003c/p\u003e\n\u003cp\u003e2.4 Statistical analysis\u003c/p\u003e\n\u003cp\u003eStatistical analyses were performed using SPSS software (version 23.0; SPSS, Inc, Chicago,IL), with normally distributed data expressed as mean \u0026plusmn; standard deviation and abnormally distributed data expressed as median (P25, P75). Two-way comparisons were performed using the Friedman test, and the Bonferroni method was used to correct for significance, with P values \u0026lt;0.05 considered statistically significant.\u003c/p\u003e"},{"header":"3. Results","content":"\u003cp\u003e3.1 Study population\u003c/p\u003e\n\u003cp\u003eA total of 282 eyes of 141 patients aged between 17 and 45 years were included in this study, with a mean patient age of 21.12\u0026plusmn;4.84 years, including 20 cases in the mild myopia group, 83 cases in the moderate myopia group, and 38 cases in the high myopia group, with no statistically significant differences between the three groups in terms of gender (P=0.344) and age (P=0.3) (see Table 1 for a summary of demographics ).\u003c/p\u003e\n\u003ctable border=\"1\" cellpadding=\"0\" cellspacing=\"0\" width=\"606\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"19.669421487603305%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.669421487603305%\"\u003e\n \u003cp\u003eLow myopia group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.669421487603305%\"\u003e\n \u003cp\u003eModerate myopia group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.49586776859504%\"\u003e\n \u003cp\u003eHigh myopia group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.49586776859504%\"\u003e\n \u003cp\u003eP\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"19.669421487603305%\"\u003e\n \u003cp\u003ePatients\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.669421487603305%\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.669421487603305%\"\u003e\n \u003cp\u003e83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.49586776859504%\"\u003e\n \u003cp\u003e38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.49586776859504%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"19.669421487603305%\"\u003e\n \u003cp\u003eGender (Male: Female)\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.669421487603305%\"\u003e\n \u003cp\u003e13：7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.669421487603305%\"\u003e\n \u003cp\u003e55：28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.49586776859504%\"\u003e\n \u003cp\u003e20：18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.49586776859504%\"\u003e\n \u003cp\u003e0.344\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"19.669421487603305%\"\u003e\n \u003cp\u003eAge\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.669421487603305%\"\u003e\n \u003cp\u003e19.75\u0026plusmn;0.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.669421487603305%\"\u003e\n \u003cp\u003e20.95\u0026plusmn;0.48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.49586776859504%\"\u003e\n \u003cp\u003e22.26\u0026plusmn;0.94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.49586776859504%\"\u003e\n \u003cp\u003e0.3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"19.669421487603305%\"\u003e\n \u003cp\u003eSpherical equivalent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.669421487603305%\"\u003e\n \u003cp\u003e2.03\u0026plusmn;0.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.669421487603305%\"\u003e\n \u003cp\u003e4.14\u0026plusmn;0.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.49586776859504%\"\u003e\n \u003cp\u003e6.45\u0026plusmn;0.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.49586776859504%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eTable 1 \u0026nbsp;Summary Demographics of Patients in the Study\u003c/p\u003e\n\u003cp\u003e\u003csup\u003ea\u003c/sup\u003e Numbers of subjects\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003csup\u003eb\u003c/sup\u003e Average years of age at first diagnosis\u003c/p\u003e\n\u003cp\u003e3.2 Comparison of horizontal PEP between different groups\u003c/p\u003e\n\u003cp\u003eThe horizontal perceptual eye quartiles of the 3 groups were as follows (Table 2), and the differences in horizontal PEP between the 3 groups were not statistically significant on preoperative, 1 day postoperative, 1 week postoperative, and 1 month postoperative (P=0.189; P=0.173; P=0.213; P=0.246), and it can be concluded that the changes in horizontal PEP were not related to the degree of myopia. Using the Friedman test performed as follows (Table 3), the difference in horizontal PEP was statistically significant in patients at all periods (X2=82.004, P\u0026lt;0.001), and the horizontal PEP improved at 1 day and 1 week postoperatively compared with the preoperative period, but rebounded in January postoperatively.\u003c/p\u003e\n\u003ctable border=\"1\" cellpadding=\"0\" cellspacing=\"0\" width=\"573\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"14.31064572425829%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.11692844677138%\"\u003e\n \u003cp\u003eBefore\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.465968586387433%\"\u003e\n \u003cp\u003e1 day postoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.11692844677138%\"\u003e\n \u003cp\u003e1 week postoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.98952879581152%\"\u003e\n \u003cp\u003e1 month postoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"14.31064572425829%\"\u003e\n \u003cp\u003eLow myopia group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.11692844677138%\"\u003e\n \u003cp\u003e10.67（8.58，21.41）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.465968586387433%\"\u003e\n \u003cp\u003e8.67（5.35，10.91）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.11692844677138%\"\u003e\n \u003cp\u003e8.09（4.56，12.64）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.98952879581152%\"\u003e\n \u003cp\u003e12.5（8.42，19.24）\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"14.31064572425829%\"\u003e\n \u003cp\u003eModerate myopia group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.11692844677138%\"\u003e\n \u003cp\u003e18.33（10.42，47.83）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.465968586387433%\"\u003e\n \u003cp\u003e11.91（6.41，19.82）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.11692844677138%\"\u003e\n \u003cp\u003e10（6.08，18.67）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.98952879581152%\"\u003e\n \u003cp\u003e16（9.17，29）\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"14.31064572425829%\"\u003e\n \u003cp\u003eHigh myopia group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.11692844677138%\"\u003e\n \u003cp\u003e14.15（9.39，38.87）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.465968586387433%\"\u003e\n \u003cp\u003e8.99（6.29，18.54）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.11692844677138%\"\u003e\n \u003cp\u003e10.27（6.16，17.1）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.98952879581152%\"\u003e\n \u003cp\u003e12.17（8.6，23.49）\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eTable 2 \u0026nbsp; Comparison of horizontal perceptual eye position in 3 groups\u003c/p\u003e\n\u003ctable border=\"1\" cellpadding=\"0\" cellspacing=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"3.5211267605633805%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"14.788732394366198%\"\u003e\n \u003cp\u003eBefore-1 day postoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"14.788732394366198%\"\u003e\n \u003cp\u003eBefore-1 week postoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"14.788732394366198%\"\u003e\n \u003cp\u003eBefore-1 month postoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"14.788732394366198%\"\u003e\n \u003cp\u003eBefore-1 day-1 week postoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.8943661971831%\"\u003e\n \u003cp\u003eBefore-1 day-Before-1 month\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.429577464788732%\"\u003e\n \u003cp\u003e1 week postoperative-Before-1 month\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"3.5211267605633805%\"\u003e\n \u003cp\u003eP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"14.788732394366198%\"\u003e\n \u003cp\u003e＜0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"14.788732394366198%\"\u003e\n \u003cp\u003e＜0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"14.788732394366198%\"\u003e\n \u003cp\u003e0.096\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"14.788732394366198%\"\u003e\n \u003cp\u003e0.831\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.8943661971831%\"\u003e\n \u003cp\u003e＜0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.429577464788732%\"\u003e\n \u003cp\u003e＜0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eP value \u0026lt; 0.05 was considered statistically significant\u003c/p\u003e\n\u003cp\u003eTable 3 \u0026nbsp;Two-by-two comparison of horizontal perceptual eye position at different periods\u003c/p\u003e\n\u003cp\u003e3.3 Comparison of vertical PEP between different groups\u003c/p\u003e\n\u003cp\u003eThe vertical perceptual eye quartiles of the 3 groups were as follows (Table 4), and the differences in vertical PEP between the 3 groups were not statistically significant on preoperative, 1 day postoperative, 1 week postoperative, and 1 month postoperative (P=0.131; P=0.85; P=0.367; P=0.349), and the two-way comparison using the Friedman test was as follows (Table 5), and the differences in horizontal PEP of patients at each time period were statistically significant (X2=38.59, P\u0026lt;0.001), and the vertical PEP at 1 day, 1 week, and 1 month postoperatively were all elevated compared to preoperatively, but the elevation was smaller.\u003c/p\u003e\n\u003ctable border=\"1\" cellpadding=\"0\" cellspacing=\"0\" width=\"575\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"14.45993031358885%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"24.56445993031359%\"\u003e\n \u003cp\u003eBefore\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"22.99651567944251%\"\u003e\n \u003cp\u003e1 day postoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.686411149825783%\"\u003e\n \u003cp\u003e1 week postoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.29268292682927%\"\u003e\n \u003cp\u003e1 month postoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"14.45993031358885%\"\u003e\n \u003cp\u003eLow myopia group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"24.56445993031359%\"\u003e\n \u003cp\u003e4.67（3.41，6.85）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"22.99651567944251%\"\u003e\n \u003cp\u003e4.67（3.95，6.31）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.686411149825783%\"\u003e\n \u003cp\u003e3.52（2.65，5.8）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.29268292682927%\"\u003e\n \u003cp\u003e4（3.04，5.29）\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"14.45993031358885%\"\u003e\n \u003cp\u003eModerate myopia group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"24.56445993031359%\"\u003e\n \u003cp\u003e6（4.08，10.17）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"22.99651567944251%\"\u003e\n \u003cp\u003e4.67（3.75，6）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.686411149825783%\"\u003e\n \u003cp\u003e4.28（3.33，5.67）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.29268292682927%\"\u003e\n \u003cp\u003e4.67（3.33，5.29）\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"14.45993031358885%\"\u003e\n \u003cp\u003eHigh myopia group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"24.56445993031359%\"\u003e\n \u003cp\u003e6.5（4.67，8.83）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"22.99651567944251%\"\u003e\n \u003cp\u003e5.2（3.46，6.7）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.686411149825783%\"\u003e\n \u003cp\u003e4.02（3.27，5.91）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.29268292682927%\"\u003e\n \u003cp\u003e4（3.31，5.89）\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eTable 4 Comparison of horizontal perceptual eye position in 3 groups at different periods\u003c/p\u003e\n\u003ctable border=\"1\" cellpadding=\"0\" cellspacing=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"3.6971830985915495%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"11.795774647887324%\"\u003e\n \u003cp\u003eBefore-1 day postoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"11.267605633802816%\"\u003e\n \u003cp\u003eBefore-1 week postoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"12.67605633802817%\"\u003e\n \u003cp\u003eBefore-1 month postoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"14.612676056338028%\"\u003e\n \u003cp\u003eBefore-1 day-1 week postoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"16.549295774647888%\"\u003e\n \u003cp\u003eBefore-1 day-Before-1 month\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"16.725352112676056%\"\u003e\n \u003cp\u003e1 week postoperative-Before-1 month\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"12.67605633802817%\"\u003e\n \u003cp\u003eBefore-1 day postoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"3.6971830985915495%\"\u003e\n \u003cp\u003eP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"11.795774647887324%\"\u003e\n \u003cp\u003e＜0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"11.267605633802816%\"\u003e\n \u003cp\u003e＜0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"12.67605633802817%\"\u003e\n \u003cp\u003e0.096\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"14.612676056338028%\"\u003e\n \u003cp\u003e0.831\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"16.549295774647888%\"\u003e\n \u003cp\u003e＜0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"16.725352112676056%\"\u003e\n \u003cp\u003e＜0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"12.67605633802817%\"\u003e\n \u003cp\u003e＜0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eP value \u0026lt; 0.05 was\u0026nbsp;considered statistically significant\u003c/p\u003e\n\u003cp\u003eTable 5 \u0026nbsp;Two-by-two comparison of vertical perceptual eye position at different periods\u003c/p\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eBinocular vision is not exactly the same as the visual function that we think of as the visual function that humans value when performing object recognition and processing in traditional ophthalmology; it includes both the visual function part of traditional ophthalmology and part of the functional vision aspects. Not only visual acuity, but also binocular functional vision, such as stereo vision, perceptual eye position and binocular suppression system, which is integrated by information from the brain [24]. Most studies have investigated the discomfort of patients after SMILE based on traditional visual function tests, visual quality instruments, and dry eye examinations, but few studies have investigated postoperative binocular visual function [26-30]. Previous studies have found changes in stereoscopic vision after SMILE, but there are no studies on changes in perceptual eye position after SMILE [31]. Therefore, in the present study, we compared perceptual eye position in patients with different degrees of myopia after SMILE to investigate whether deviations in perceptual eye position are related to SMILE surgery and the occurrence of their degree of myopia, complementing the existing studies related to binocular vision after SMILE. This study found an improvement in horizontal PEP and no significant change in vertical PEP changes in patients after SMILE. The improvement in the horizontal PEP at both one day and one week postoperatively may indicate that the visual center of the brain has enhanced control of eye position postoperatively and that the brain perception level has increased to control the position of the eye. In contrast, the horizontal PEP did not improve at one month postoperatively, and we speculate that the newly established neural reflex pathways may require longer and repetitive training. This suggests that we should also strengthen PEP training in the postoperative period to help patients regain good eye position as soon as possible.\u003c/p\u003e\n\u003cp\u003ePEP differs from conventional eye position in that this eye position deviation may better reflect the ability of the visual center of the brain to control eye position in the divided vision state, and abnormalities in PEP are more indicative of the state and degree of impairment of central perceptual function [20]. In children with normal corrected visual acuity and normal eye position, the mean vertical PEP was 1 to 3 pixels, while the mean horizontal PEP was 4 to 8 pixels; however, in amblyopic children, the deviation of PEP pixels was much higher than this and depended on the severity of amblyopia; for this reason, our study excluded patients with monocular amblyopia to maintain homogeneity of the patients\u0026apos; PEP tests [32]. The results of our experiment found statistically significant horizontal PEP comparisons and no statistically significant vertical PEP comparisons in patients after SMILE, contrary to the results of Yang et al [23]. By comparing myopic patients with severe refractive error with those without refractive error, Yang\u0026apos;s team found that the two groups had statistically significant comparisons of results between vertical PEP, while there was no statistically significant comparison in horizontal PEP. Their results suggest that patients with a severe refractive error have unstable vertical PEP, and thus speculate that instability in vertical perceptual eye position may be related to the development of severe refractive error. In our study, on the other hand, we found an improvement in horizontal PEP after surgery, and therefore ventured to speculate that the instability of horizontal PEP might be related to refractive correction. Similarly, this inspires us to pay more attention to the changes in vertical perceptual eye position in patients with concomitant refractive aberrations, to consider whether to make relevant interventions before surgery, and to follow up well after surgery.\u003c/p\u003e\n\u003cp\u003eThe limitation of this study is that the sample size is too small and the observation time is only one month after surgery, which can only reflect the changes of PEP in the early postoperative period after SMILE. In the future, this study should expand the sample size and continue to extend the observation period to further investigate the changes of PEP in patients after SMILE, and provide PEP training to patients when necessary to help restore good eye position as soon as possible.\u003c/p\u003e\n\u003cp\u003eIn conclusion, the results of the small sample suggest that the PEP shift is not only limited to patients with strabismic amblyopia, but also exists in patients with refractive error, and the SMILE procedure can improve the PEP shift, and the long-term results remain to be further observed.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn conclusion, by using virtual reality technology, We found Most myopic patients have perceptual eye position shift before refractive correction, and SMILE surgery can improve the perceptual eye position shifts significantly in the early postoperative period, but the long-term results need to be further observed.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eAcknowledgements\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003eAuthors\u0026rsquo;\u0026nbsp;contributions\u003c/p\u003e\n\u003cp\u003eLLB and KXM analyzed the data and write the manuscript.LLB performed the\u003c/p\u003e\n\u003cp\u003estatistical analysis. LLB and KXM collected the data. HJT and GL designed\u003c/p\u003e\n\u003cp\u003epart of the study, as well as revised and polish the manuscript. LHB designed the study and analyzed the data. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003eFunding.\u003c/p\u003e\n\u003cp\u003eThis study is supported by Science and Technology Program of SiChuan of China(N0.2020JDKP0072).\u003c/p\u003e\n\u003cp\u003eAvailability of data and materials\u003c/p\u003e\n\u003cp\u003eThe datasets generated during and/or analyzed during the current study are\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eavailable from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003eEthics approval and consent to participate\u003c/p\u003e\n\u003cp\u003eThe study protocol was approved by the Affiliated Hospital of Southwest Medical University. A written informed consent \u0026nbsp;was obtained from each patient before surgery. All methods were carried out in accordance with relevant guidelines and regulations.\u003c/p\u003e\n\u003cp\u003eConsent for publication\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003eCompeting interests\u003c/p\u003e\n\u003cp\u003eAll authors declare that they have no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eBaird, P.N., et al., \u003cem\u003eMyopia.\u003c/em\u003e Nat Rev Dis Primers, 2020. \u003cstrong\u003e6\u003c/strong\u003e(1): p. 99.DOI: 10.1038/s41572-020-00231-4\u003c/li\u003e\n\u003c/ol\u003e\n\u003col start=\"2\"\u003e\n\u003cli\u003eModjtahedi, B.S., et al., \u003cem\u003ePublic Health Burden and Potential Interventions for Myopia.\u003c/em\u003e Ophthalmology, 2018. \u003cstrong\u003e125\u003c/strong\u003e(5): p. 628-630.DOI: 10.1016/j.ophtha.2018.01.033\u003c/li\u003e\n\u003c/ol\u003e\n\u003col start=\"3\"\u003e\n\u003cli\u003eMorgan, I.G., et al., \u003cem\u003eThe epidemics of myopia: Aetiology and prevention.\u003c/em\u003e Prog Retin Eye Res, 2018. \u003cstrong\u003e62\u003c/strong\u003e: p. 134-149.DOI: 10.1016/j.preteyeres.2017.09.004\u003c/li\u003e\n\u003c/ol\u003e\n\u003col start=\"4\"\u003e\n\u003cli\u003eHolden, B.A., et al., \u003cem\u003eGlobal Prevalence of Myopia and High Myopia and Temporal Trends from 2000 through 2050.\u003c/em\u003e Ophthalmology, 2016. \u003cstrong\u003e123\u003c/strong\u003e(5): p. 1036-42.DOI: 10.1016/j.ophtha.2016.01.006\u003c/li\u003e\n\u003c/ol\u003e\n\u003col start=\"5\"\u003e\n\u003cli\u003eBlum, M., et al., \u003cem\u003eFive-year results of refractive lenticule extraction.\u003c/em\u003e J Cataract Refract Surg, 2014. \u003cstrong\u003e40\u003c/strong\u003e(9): p. 1425-9.DOI: 10.1016/j.jcrs.2014.01.034\u003c/li\u003e\n\u003c/ol\u003e\n\u003col start=\"6\"\u003e\n\u003cli\u003eSekundo, W., et al., \u003cem\u003eFirst efficacy and safety study of femtosecond lenticule extraction for the correction of myopia: six-month results.\u003c/em\u003e J Cataract Refract Surg, 2008. \u003cstrong\u003e34\u003c/strong\u003e(9): p. 1513-20.DOI: 10.1016/j.jcrs.2008.05.033\u003c/li\u003e\n\u003c/ol\u003e\n\u003col start=\"7\"\u003e\n\u003cli\u003eAng, M., et al., \u003cem\u003eRandomized Clinical Trial Comparing Femtosecond LASIK and Small-Incision Lenticule Extraction.\u003c/em\u003e Ophthalmology, 2020. \u003cstrong\u003e127\u003c/strong\u003e(6): p. 724-730.DOI: 10.1016/j.ophtha.2019.09.006\u003c/li\u003e\n\u003c/ol\u003e\n\u003col start=\"8\"\u003e\n\u003cli\u003eAvetisov, S.E., et al., \u003cem\u003e[Results of a two-year clinical study of myopia control with bifocal defocus-inducing soft contact lenses].\u003c/em\u003e Vestn Oftalmol, 2021. \u003cstrong\u003e137\u003c/strong\u003e(3): p. 5-12.DOI: 10.17116/oftalma20211370315\u003c/li\u003e\n\u003c/ol\u003e\n\u003col start=\"9\"\u003e\n\u003cli\u003eRobboy, M.W., et al., \u003cem\u003eAssessment of Clinical Trials for Devices Intended to Control Myopia Progression in Children.\u003c/em\u003e Eye Contact Lens, 2018. \u003cstrong\u003e44\u003c/strong\u003e(4): p. 212-219.DOI: 10.1097/ICL.0000000000000476\u003c/li\u003e\n\u003c/ol\u003e\n\u003col start=\"10\"\u003e\n\u003cli\u003eZhang, Y., et al., \u003cem\u003eClinical Outcomes of SMILE and FS-LASIK Used to Treat Myopia: A Meta-analysis.\u003c/em\u003e J Refract Surg, 2016. \u003cstrong\u003e32\u003c/strong\u003e(4): p. 256-65.DOI: 10.3928/1081597X-20151111-06\u003c/li\u003e\n\u003c/ol\u003e\n\u003col start=\"11\"\u003e\n\u003cli\u003eDamgaard, I.B., et al., \u003cem\u003e7-Year Results of SMILE for High Myopia: Visual and Refractive Outcomes and Aberrations.\u003c/em\u003e J Refract Surg, 2021. \u003cstrong\u003e37\u003c/strong\u003e(10): p. 654-661.DOI: 10.3928/1081597X-20210712-02\u003c/li\u003e\n\u003c/ol\u003e\n\u003col start=\"12\"\u003e\n\u003cli\u003eDoane, J.F., et al., \u003cem\u003eSmall Incision Lenticule Extraction SMILE - 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Songco-Aguas, and F. Rieke, \u003cem\u003eParallel Processing of Rod and Cone Signals: Retinal Function and Human Perception.\u003c/em\u003e Annu Rev Vis Sci, 2018. \u003cstrong\u003e4\u003c/strong\u003e: p. 123-141.DOI: 10.1146/annurev-vision-091517-034055\u003c/li\u003e\n\u003c/ol\u003e\n\u003col start=\"20\"\u003e\n\u003cli\u003eMasri, R.A., U. Gr\u0026uuml;nert, and P.R. Martin, \u003cem\u003eAnalysis of Parvocellular and Magnocellular Visual Pathways in Human Retina.\u003c/em\u003e J Neurosci, 2020. \u003cstrong\u003e40\u003c/strong\u003e(42): p. 8132-8148.DOI: 10.1523/JNEUROSCI.1671-20.2020\u003c/li\u003e\n\u003c/ol\u003e\n\u003col start=\"21\"\u003e\n\u003cli\u003eLan, J., et al., \u003cem\u003eVirtual Reality Assessment Reveals Myopic Regression After ICL Implantation in High Myopia.\u003c/em\u003e Stud Health Technol Inform, 2020.DOI: 10.3233/SHTI200014\u003c/li\u003e\n\u003c/ol\u003e\n\u003col start=\"22\"\u003e\n\u003cli\u003eZhao, G. H., et al., Investigation of perceptual eye position and gaze stability status in children with normal vision. Ophthalmology, 2014. 23(05): p. 312-315.\u003c/li\u003e\n\u003cli\u003eSerrano-Pedraza, I., et al., \u003cem\u003eVisual suppression in intermittent exotropia during binocular alignment.\u003c/em\u003e Invest Ophthalmol Vis Sci, 2011. \u003cstrong\u003e52\u003c/strong\u003e(5): p. 2352-64.DOI: 10.1167/iovs.10-6144\u003c/li\u003e\n\u003c/ol\u003e\n\u003col start=\"24\"\u003e\n\u003cli\u003eBlohm, G. and J.D. Crawford, \u003cem\u003eComputations for geometrically accurate visually guided reaching in 3-D space.\u003c/em\u003e J Vis, 2007. \u003cstrong\u003e7\u003c/strong\u003e(5): p. 4.1-22.DOI: 10.1167/7.5.4\u003c/li\u003e\n\u003c/ol\u003e\n\u003col start=\"25\"\u003e\n\u003cli\u003eYang, C., et al., \u003cem\u003eComparison of perceptual eye positions among patients with different degrees of anisometropia.\u003c/em\u003e Medicine (Baltimore), 2017. \u003cstrong\u003e96\u003c/strong\u003e(39): p. e8119.DOI: 10.1097/MD.0000000000008119\u003c/li\u003e\n\u003c/ol\u003e\n\u003col start=\"26\"\u003e\n\u003cli\u003eSun, Hongjiang, A study of binocular vision in patients before and after LASIK surgery based on binocular integration of VR technology. 2021, University of Electronic Science and Technology.\u003c/li\u003e\n\u003cli\u003eTan, F., et al., \u003cem\u003eThe Study of Perceptual Eye Position Examination and Visual Perceptual Training in Postoperative Intermittent Exotropes.\u003c/em\u003e Cyberpsychol Behav Soc Netw, 2020. \u003cstrong\u003e23\u003c/strong\u003e(12): p. 871-875.DOI: 10.1089/cyber.2020.0837\u003c/li\u003e\n\u003c/ol\u003e\n\u003col start=\"28\"\u003e\n\u003cli\u003eLi, X., et al., \u003cem\u003eIntermittent Exotropia Treatment with Dichoptic Visual Training Using a Unique Virtual Reality Platform.\u003c/em\u003e Cyberpsychol Behav Soc Netw, 2019. \u003cstrong\u003e22\u003c/strong\u003e(1): p. 22-30.DOI: 10.1089/cyber.2018.0259\u003c/li\u003e\n\u003c/ol\u003e\n\u003col start=\"29\"\u003e\n\u003cli\u003eKobashi, H., K. Kamiya, and K. Shimizu, \u003cem\u003eDry Eye After Small Incision Lenticule Extraction and Femtosecond Laser-Assisted LASIK: Meta-Analysis.\u003c/em\u003e Cornea, 2017. \u003cstrong\u003e36\u003c/strong\u003e(1): p. 85-91.DOI: 10.1097/ICO.0000000000000999\u003c/li\u003e\n\u003c/ol\u003e\n\u003col start=\"30\"\u003e\n\u003cli\u003eMiao, H., et al., \u003cem\u003eVisual Quality After Femtosecond Laser Small Incision Lenticule Extraction.\u003c/em\u003e Asia Pac J Ophthalmol (Phila), 2017. \u003cstrong\u003e6\u003c/strong\u003e(5): p. 465-468.DOI: 10.22608/APO.2016171\u003c/li\u003e\n\u003c/ol\u003e\n\u003col start=\"31\"\u003e\n\u003cli\u003eCao, K., et al., \u003cem\u003eChanges in corneal biomechanics during small-incision lenticule extraction (SMILE) and femtosecond-assisted laser in situ keratomileusis (FS-LASIK).\u003c/em\u003e Lasers Med Sci, 2020. \u003cstrong\u003e35\u003c/strong\u003e(3): p. 599-609.DOI: 10.1007/s10103-019-02854-w\u003c/li\u003e\n\u003c/ol\u003e\n\u003col start=\"32\"\u003e\n\u003cli\u003eYang, W., et al., \u003cem\u003eVisual Outcomes after Small Incision Lenticule Extraction and Femtosecond Laser-Assisted LASIK for High Myopia.\u003c/em\u003e Ophthalmic Res, 2020. \u003cstrong\u003e63\u003c/strong\u003e(4): p. 427-433.DOI: 10.1159/000504304\u003c/li\u003e\n\u003c/ol\u003e\n\u003col start=\"33\"\u003e\n\u003cli\u003eRandleman, J.B., \u003cem\u003eSmall Incision Lenticule Extraction (SMILE): What Now? What Next?\u003c/em\u003e Ophthalmology, 2020. \u003cstrong\u003e127\u003c/strong\u003e(8): p. 1035-1036.DOI: 10.1016/j.ophtha.2020.03.013\u003c/li\u003e\n\u003c/ol\u003e\n\u003col start=\"34\"\u003e\n\u003cli\u003eXiang, A., et al., \u003cem\u003eDetection of Static and Dynamic Stereopsis after Femtosecond Laser Small Incision Lenticule Extraction for High Myopia.\u003c/em\u003e J Ophthalmol, 2021. \u003cstrong\u003e2021\u003c/strong\u003e: p. 6667263.DOI: 10.1155/2021/6667263\u003c/li\u003e\n\u003cli\u003eLin, N., et al., Investigation of perceptual eye position and gaze stability status in amblyopic children. Ophthalmology, 2014. 23(06): p. 417-419.\u003c/li\u003e\n\u003c/ol\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":"perceptual eye position, SMILE, virtual reality, myopia","lastPublishedDoi":"10.21203/rs.3.rs-2237873/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-2237873/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eOBJECTIVE: To investigate the pattern of changes in perceptual eye position in patients after Femtosecond Laser Small Incision Lenticule Extraction(SMILE), which was examined using the visual perception detection system developed by the National Engineering and Technology Research Center for Healthcare Appliances.\u003c/p\u003e\n\u003cp\u003eMETHODS: A total of 141 patients participated in this prospective study. The patients were divided into three groups according to the degree of myopia: low myopic group\u003c/p\u003e\n\u003cp\u003e( equivalent spherical refraction ≤ 3.00D), moderate myopic group(3.00D \u0026lt; equivalent spherical refraction ≤ 6.00D), and high myopic group (equivalent spherical refraction \u0026gt; 6.00D). The relationship of perceptual eye position was measured by the computer-controlled visual perception detection system before, 1 day, 1 week and 1 month after surgery to investigate the changes of perceptual eye position after SMILE.\u003c/p\u003e\n\u003cp\u003eRESULTS: The differences in horizontal perceptual eye position were statistically significant at all time periods (X2=82.004, P\u0026lt;0.001), and the horizontal perceptual eye position improved at 1 day and 1 week postoperatively compared with that before surgery, but rebounded in January postoperatively. The differences in vertical perceptual eye position were statistically significant at all time periods (X2=38.59, P\u0026lt;0.001), and the vertical PEP improved at 1 day, 1 week, and 1 month postoperatively compared with the preoperative level, but the improvement was small. The difference between horizontal perceptual eye position and vertical perceptual eye position in all three groups was not statistically significant, and it can be concluded that the deviation of perceptual eye position after SMILE is not related to the degree of myopia.\u003c/p\u003e\n\u003cp\u003eCONCLUSION: Most myopic patients have perceptual eye position shift before refractive correction, and SMILE surgery can improve the perceptual eye position shifts significantly in the early postoperative period, but the long-term results need to be further observed.\u003c/p\u003e","manuscriptTitle":"Exploring the changes of perceptual eye position after SMILE based on the virtual reality platform","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2022-11-18 15:42:39","doi":"10.21203/rs.3.rs-2237873/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":"09491877-d5e3-453b-a123-1f23df98be85","owner":[],"postedDate":"November 18th, 2022","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2023-05-16T02:14:23+00:00","versionOfRecord":[],"versionCreatedAt":"2022-11-18 15:42:39","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-2237873","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-2237873","identity":"rs-2237873","version":["v1"]},"buildId":"FbvkV6FR0MCFSLy54lSbu","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}