Tomographic characteristics of thick corneas

Tomographic characteristics of thick corneas | 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 Tomographic characteristics of thick corneas Junjie Yu, Ye Xu, Xiaoying Wang, Yishan Qian This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3969726/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 10 Feb, 2025 Read the published version in BMC Ophthalmology → Version 1 posted 14 You are reading this latest preprint version Abstract Purpose : To investigate the tomographic characteristics of corneas with excessive thickness and to explore their potential impact on the assessment of candidates for refractive surgery. Methods: One hundred and two eyes from 102 patients with the thinnest pachymetry (TP) < 500 μm, 100 eyes from 100 patients with TP ranging from 500 to 580 μm, and 102 eyes from 102 subjects with TP ≥ 580 μm were included. Pentacam ectasia indices were compared among these different groups. Results : When compared to eyes with TP between 500 and 580 μm, significantly higher values in anterior radius of curvature (ARC), anterior corneal astigmatism (KAp), back elevation at the thinnest pachymetry (BE), deviation ofnormality of the back elevation (Db), and a more negative Q value for the back surface (Qback) were observed in eyes with TP ≥ 580 μm (Mann-Whitney U test: P<0.001). No significant differences were observed in the indices for the anterior cornea (Mann-Whitney U test: index of height decentration, P=0.348; inferior-superior value, P=0.334; keratoconus percentage index, P=0.077; deviation of normality of the front elevation, P=0.891). The proportion of abnormalities was highest in eyes with TP ≥ 580 μm for BE (16.7%, Chi-square test: P<0.001) and Db (20.6%, Chi-square test: P=0.001). Conclusions : The tomography of thick corneas reveals greater BE and Db,as well as a more negative Qback while no significant disparities emerged in the anterior corneal indices. corneal thickness forme fruste keratoconus tomography asphericity Introduction In recent years, advances in tomography have greatly improved the ability to assess surgical candidates and detect subtle corneal changes, including subclinical keratoconus (KC). The Scheimpflug principle-based device employs a rotating camera to measure elevation points, providing a three-dimensional reconstruction of the entire cornea, encompassing both anterior and posterior surfaces, corneal thickness, and various standardized indices for ectasia detection, such as the Belin/Ambrosio Enhanced Ectasia display (BAD display) [1] . As the most widely used device for corneal evaluation, recent studies have revealed that certain factors, such as eyelid morphometry [2] and corneal diameter (CD) [3] , can influence the values of certain tomographic indices, thus affecting their interpretation. Parameters related to corneal thickness, such as the thinnest pachymetry (TP) and pachymetric indices, have become crucial in preoperative evaluations. According to a large-sample epidemiological study by Ma et al., the median TP for Chinese young adults was approximately 540 μm (Quartile 1 to Quartile 3: 520-570 μm) [4] . While a thin cornea has been considered a risk factor for KC, limited research has focused on the impact of a thick cornea on KC indices. Roshdy et al. [5] discovered that thicker corneas in an Egyptian population (>564 μm) displayed significantly higher values of back elevation (BE). However, as this study only analyzed pachymetric and elevation data with a relatively small sample size, the influence of thick corneas on KC screening remains uncertain. The objective of this study is to investigate the tomographic characteristics of thick corneas using the Pentacam HR device (OCULUS GmbH, Wetzlar, Germany) and to explore its potential impact on the screening of candidates for refractive surgery. Methods Participants This cross-section study included participants who were selected from the Fudan University EENT Hospital Refractive Center Database from January 202 to January 2023. The inclusion criteria were as follows: participants who were followed-up once a year for at least 3 years; age between 18 and 50 years; unremarkable slit-lamp examination; normal tomography (ABCD classification system, stage 0, and overall deviation of normality [BAD-D] <2.6), and a horizontal corneal diameter of ≥11.1mm in both eyes as measured by the Pentacam HR (OCULUS Optikgerate GmbH, Wetzlar, Germany). Stage 0 in the ABCD classification system was specified as follows: anterior radius of curvature for a 3.0 mm zone centered on the thinnest point (ARC) > 7.25 mm, posterior radius of curvature for a 3.0 mm zone centered on the thinnest point (PRC) > 5.9 mm, the thinnest pachymetry (TP) > 490 μm, the best documented visual acuity ≥ 1.0, and the absence of corneal scarring. Cases with any pathological ocular conditions or relevant systemic diseases were excluded. Soft contact lens wear was discontinued for at least 7 days before the examination, while rigid or hybrid contact lenses were discontinued for a minimum period of 3 weeks. The study received approval from the Ethics Committee of the Eye and ENT Hospital of Fudan University in Shanghai, China, and was conducted in accordance with tenets of the Declaration of Helsinki. Written informed consent was obtained from all participants before their inclusion in this study. The corneas included in the study were categorized into three groups based on epidemiological data [4] : group 1 comprised eyes with TP less than 500 μm, group 2 included eyes with TP between 500 and 580 μm, and group 3 encompassed eyes with TP greater than 580 μm. Corneal Tomography A comprehensive ophthalmic examination was conducted for all patients, which included a slit-lamp examination, objective and subjective refractions, and Pentacam HR examination. The Pentacam imaging was performed by the same experienced examiner (YJ) for all participants, with three measurements averaged for each individual. Only scans meeting the "OK" criteria as per the Examination Quality Specification of the instrument were utilized for analysis. The following corneal characteristics were obtained using the Pentacam software: thinnest pachymetry (TP), horizontal corneal diameter (CD), anterior radius of curvature for a 3-mm zone centered on the thinnest point (ARC), posterior radius of curvature for a 3-mm zone centered on the thinnest point (PRC), best fit sphere for the anterior cornea (BFSa), best fit sphere for the posterior cornea (BFSp), corneal astigmatism of the anterior and posterior cornea for a 3-mm zone centered on the thinnest point (KAa and KAp), asphericity (Q-value) of the front (Qfront) and back corneal surface (Qback), front and back corneal elevations at TP (FE and BE), pachymetric progression index (PPI, including minimum, average, and maximum values), Ambrósio's maximum relational thickness index (ARTmax), index of height decentration (IHD), inferior-superior value (I-S), and keratoconus percentage index (KISA%). The BAD normalized indices include deviation of normality of the front elevation (Df), deviation of normality of the back elevation (Db), deviation of normality of pachymetric progression (Dp), deviation of normality of corneal thinnest point (Dt), deviation of normality of relational thickness (Da), and overall deviation of normality (BAD-D). The analyzing dimensions for these indices are all 8 mm in diameter. PPI represents the change in corneal thickness from TP to the periphery and can be calculated over all 360 degrees of the cornea. The average of these meridians is represented as PPIavg, while the meridian with the maximum pachymetric increase is PPImax, and the one with the minimum pachymetric increase is PPImin. The deviation-based indices are categorized by the software as normal (<1.6 standard deviations [SD] from the population mean, indicated in white), suspicious (≥1.6 SD and <2.6 SD, highlighted in yellow), and pathologic (≥2.6 SD, highlighted in red), based on data reported by Ambrósio et al., [6] and this classification was consistently applied throughout this study. FE was classified as normal (<5.01), suspicious (≥5.01 and <7.14), and pathologic (≥7.14), while BE (for myopia only) was categorized as normal (<11.77), suspicious (≥11.77 and <16.42), and pathologic (≥16.42). For the purpose of statistical analysis, eyes classified as 'suspect' and 'abnormal' were grouped as 'abnormal' for the aforementioned indices. Other indices were categorized as normal or abnormal in accordance with the cutoff values provided by the manufacturer or Feng et al.: PPImin (abnormal: ≥0.79); PPIavg (abnormal: ≥1.15); PPImax (abnormal: ≥1.44); ARTmax (abnormal: ≤313); IHD (abnormal: ≥0.014); I-S (abnormal: ≥1.4D); KISA% (abnormal: ≥60%). [7, 8] Statistical Analysis The statistical analysis was carried out using SPSS 13.0 software (IBM, Armonk, NY, USA). The normality assumption of the data was assessed using the Kolmogorov-Smirnov test. Continuous variables with a normal distribution were compared using analysis of variance (ANOVA) between 3 groups or Student's t-test with Bonferroni correction between 2 groups. Data with a non-normal distribution were analyzed using the Mann-Whitney U test between two groups and the Kruskal-Wallis test between three groups. The percentages of abnormality between groups were compared using the chi-square test or the Fisher exact test. A P value of less than 0.05 was considered to be statistically significant. Results The study involved 102 eyes of 102 patients with TP < 500μm (Group 1), 100 eyes of 100 patients with TP between 500 and 580 μm (Group 2), and 102 eyes of 102 subjects with TP ≥ 580μm (Group 3). Demographic characteristics and the means for individual Pentacam corneal descriptors are presented in Table 1. The mean TP was 487.60±9.15, 540.96±17.07, and 610.11±13.93 μm for the three groups, respectively (Kruskal-Wallis tests: P<0.001). No significant difference in age was found between the three groups (Kruskal-Wallis tests: P=0.121). A higher proportion of males was observed in Group 3 compared to the other two groups (Chi-square test: P<0.001). Comparisons between TP groups for corneal descriptors Compared to eyes with TP between 500 and 580 μm, greater values in ARC, KAp, BE at TP, ARTmax, and Db were demonstrated by eyes with TP ≥ 580μm (Mann-Whitney U test: P<0.001), along with a more negative Qback (Mann-Whitney U test: P<0.001, Table 1). No significant differences were found in the anterior corneal indices (Mann-Whitney U test: IHD, P=0.348; I-S, P=0.334; KISA%, P=0.077; Df, P=0.891). Compared to eyes with TP between 500 and 580 μm, greater FE at TP (Mann-Whitney U test: P=0.045), I-S (Mann-Whitney U test: P=0.001), PPImax, PPIavg, Dp, Dt, Da, and BAD-D were exhibited by eyes with TP less than 500 μm (Mann-Whitney U test: P<0.001). ARTmax was significantly smaller for eyes with TP less than 500 μm (Mann-Whitney U test: P<0.001, Table 1). Comparisons between TP groups for the classification results of the KC descriptors The results of classifications for individual KC indices in each group are summarized in Table 2. The highest proportion of abnormalities was observed in eyes with TP ≥ 580μm for BE (16.7%, Chi-square test: P<0.001) and Db (20.6%, Chi-square test: P=0.001). In eyes with TP less than 500 μm, the highest proportion of abnormalities was found for PPImin (47.1%, Chi-square test: P<0.001), PPImax (41.2%, P<0.001), PPIavg (39.2%, P<0.001), ARTmax (23.5%, P<0.001), Dp (40.2%, P<0.001), Dt (37.3%, P<0.001), Da (24.5%, P<0.001), and BAD-D (54.9%, P<0.001). Comparison of individual Pentacam Corneal Descritpors between BE groups in eyes with TP≥580um Among the 22 eyes with BE≥11.77, 17 belonged to Group 3. Subsequently, the eyes in Group 3 were subdivided into two groups based on the values of BE (BE<11.77 or BE≥11.77, see Table 3). Eyes with BE≥11.77 exhibited a smaller PRC (Student's t-test: P=0.004) and ARTmax (Student's test: P<0.001), a more negative Qfront (Student's t-test: P=0.004) and Qback (Mann-Whitney U test: P=0.001), as well as a greater PPImax (Mann-Whitney U test: P=0.001), PPIavg (Mann-Whitney U test: P=0.001), Db (Student's test: P=0.002), Dp (Student's test: P=0.001), Da (Student's test: P<0.001), and BAD-D (Mann-Whitney U test: P<0.001). No differences were observed in IHD (Mann-Whitney U test: P=0.248), I-S (P=0.190), KISA% (P=0.625), and Df (P=0.145). Discussion To date, limited research has delved into the tomographic attributes of thick corneas. This study has uncovered that thick corneas (TP≥580μm) exhibit heightened posterior corneal astigmatism, increased BE and Db, along with a more negative asphericity of the posterior cornea. Notably, no significant disparities emerged in the anterior corneal indices (IHD, I-S, KISA%, and Df). Evaluating corneal shape stands as a pivotal facet of the preoperative assessment of refractive surgery candidates. Past investigations primarily concentrated on thin corneas, which have conventionally been identified as a principal keratoconus risk factor. However, scant attention has been given to thick corneas. Our findings align with the outcomes of Roshdy's study, [5 ] which demonstrated that thicker corneas manifest higher BE values. The augmented BE could be attributed to the more negative Qback in thick corneas. Although no substantial distinctions were observed in the posterior curvature of the 3mm zone among the different thickness groups, the more prolate corneal shape in thick corneas may be attributed to a flatter peripheral cornea. Additionally, the study unveiled that posterior corneal astigmatism is more pronounced in thicker corneas, which could be an additional factor contributing to the elevated back elevation in thick corneas [9] . Furthermore, measurement errors may lead to higher BE values in thicker corneas when corneal thickness deviates significantly from the adjusted normative database, as previously reported by Roshdy et al. [5 ] In this study, eyes with TP≥580μm were categorized into two groups based on their BE values. The results revealed that eyes with elevated BE were associated with a steeper posterior curvature and increased Qfront and Qback. Additionally, these patients exhibited significantly higher values in two pachymetric progression indices (PPImax and PPIavg) and four normalized indices (Db, Dp, Da, and BAD-D). However, no significant differences were discerned in parameters related to the anterior cornea (IHD, I-S, KISA%, and Df) between eyes with elevated BE and normal controls. The earliest signs of keratoconus have long been a topic of debate. Although back elevation abnormalities have been considered a fundamental diagnostic criterion for subclinical keratoconus according to the Global Consensus on Keratoconus and Ectatic Diseases, [10] recent studies have indicated that both back elevation and regional thickness irregularities are less effective at distinguishing forme fruste keratoconus (FFKC) from normal eyes compared to parameters associated with the anterior cornea. [11, 12] Studies employing spectral domain OCT have affirmed that the earliest structural changes related to keratoconus involve epithelial remodeling with compensatory thinning at the apex. [13, 14] Therefore, the heightened BE and pachymetric progression indices in thick corneas, in the absence of anterior corneal irregularities, may stem from the distinct corneal shape (more prolate) in thick corneas, rather than representing early signs of keratoconus. A conclusive judgment awaits long-term observations of these eyes. Variations in corneal thickness have the potential to impact the corneal shape. Studies on the diurnal changes in the cornea have revealed that the thickening of the cornea upon waking is accompanied by the flattening of the anterior corneal surface and a steepening of the posterior surface. [15] Additionally, various factors have been reported to have potential effects on the elevation maps and pachymetry-based parameters. [16] Small corneas have been shown to exhibit higher rates of false positives for several BAD parameters, especially BE, Db, and PPIavg. [3,17,18] Consequently, only eyes with a CD of 11.1mm or greater were included in this study. Furthermore, both large angle kappa and corneal astigmatism were found to influence the corneal elevation maps. [19] These studies recommend adjusting the normative database to account for variations in these factors. The present study also incorporated a group of eyes with a TP less than 500 μm. The results were consistent with previous research indicating that pachymetric progression indices, as well as Dp, Dt, and BAD-D among the BAD normalized indices, were most sensitive to corneal thinning. [5, 6] Limitations The primary limitation of this study is its cross-sectional nature. Therefore, we included only patients who have been followed-up for at least 3 years and their topographies remained normal. Further study involving patients who had undergone uneventful corneal refractive surgery with at least 2 years of stable follow-up could help to make the conclusions more convincing. The second limitation is the exclusive use of the Scheimpflug device in this study. It is highly recommended that further research should explore different technologies, such as corneal biomechanical assessments using Corvis ST or Ocular Response Analyzer (ORA), Placido disk topography combined with Scheimpflug rotating cameras (e.g., Sirius tomography system), and corneal epithelium thickness mapping using anterior segment optical coherence tomography. Conclusions In comparison with eyes of normal thickness (500-580 μm), eyes with thicker corneas (>580 μm) demonstrated higher BE and Db, a more negative Qback, and no significant differences in anterior corneal indices when measured using the Scheimpflug device. The distinctive features of the back surface in thick corneas may be attributed to the distinct corneal shape (more prolate back cornea) and a higher pachymetric progression rate. Further research is required to confirm the long-term safety of performing corneal refractive surgery on these patients. Declarations Ethics approval and consent to participate Ethics approval for this study was granted by the Ethics Committee of the Eye and ENT Hospital of Fudan University (Shanghai, China. No. 2021026). It was conducted in compliance with the tenets of the Declaration of Helsinki. Written informed consent was obtained from all the patients. Consent for publication Not applicable. Availability of data and materials The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request. Competing interests The authors declare that they have no competing interests. Funding: This study was supported by the Natural Science Foundation of Minhang District, Shanghai, China (2023MHZ066) and the Research Project Grant of Shanghai Municipal Health Commission (202340220). Authors' contributions Conceptualization: Yishan Qian; Methodology: Junjie Yu; Formal analysis and investigation: Ye Xu and Junjie Yu; Writing - original draft preparation: Yishan Qian; Writing - review and editing: Xiaoying Wang; Funding acquisition: Yishan Qian; Supervision: Xiaoying Wang. Acknowledgments: We would like to thank Editage (www.editage.cn) for English language editing. References Vinciguerra P, Camesasca FI. Prevention of corneal ectasia in laser in situ keratomileusis. J Refract Surg. 2001;17(2 Suppl):S187-9. Maseedupally V, Gifford P, Swarbrick H. Variation in normal corneal shape and the influence of eyelid morphometry. Optom Vis Sci. 2015;92(3):286-300. Ding L, Wang J, Niu L, et al. Pentacam Scheimpflug Tomography findings in chinese patients with different corneal diameters. J Refract Surg. 2020;36(10):688-695. Ma R, Liu Y, Zhang L, et al. Distribution and Trends in Corneal Thickness Parameters in a Large Population-Based Multicenter Study of Young Chinese Adults. Invest Ophthalmol Vis Sci. 2018;59(8):3366-3374. Roshdy MMS, Wahba SS, Elkitkat RS, et al. Pentacam HR Indices Variation in Normal Corneas with Different Corneal Thickness. J Ophthalmol. 2018;2018:9328120. Ambrósio R Jr, Caiado AL, Guerra FP, et al. Novel pachymetric parameters based on corneal tomography for diagnosing keratoconus. J Refract Surg. 2011;27(10):753-8. Feng MT, Belin MW, Ambrósio R Jr, et al. International values of corneal elevation in normal subjects by rotating Scheimpflug camera. J Cataract Refract Surg. 2011;37(10):1817-21. Rabinowitz YS, Rasheed K. KISA% index: a quantitative videokeratography algorithm embodying minimal topographic criteria for diagnosing keratoconus. J Cataract Refract Surg. 1999;25(10):1327-35 Gatinel D, Malet J, Hoang-Xuan T, et al. Corneal elevation topography: best fit sphere, elevation distance, asphericity, toricity, and clinical implications. Cornea. 2011;30(5):508-15. Gomes JA, Tan D, Rapuano CJ, et al. Global consensus on keratoconus and ectatic diseases. Cornea. 2015;34(4):359-69. Donoso R, Rodríguez Á, Esteffan K, et al. Analysis of OPD-Scan and Pentacam Parameters for Early Keratoconus Detection. Am J Ophthalmol. 202;226:235-242. Hwang ES, Perez-Straziota CE, Kim SW, et al. Distinguishing Highly Asymmetric Keratoconus Eyes Using Combined Scheimpflug and Spectral-Domain OCT Analysis. Ophthalmology. 2018;125(12):1862-1871. Silverman RH, Urs R, Roychoudhury A, et al. Epithelial remodeling as basis for machine-based identification of keratoconus. Invest Ophthalmol Vis Sci. 2014;55(3):1580-7. Sandali O, El Sanharawi M, Temstet C, et al. Fourier-domain optical coherence tomography imaging in keratoconus: a corneal structural classification. Ophthalmology. 2013;120(12):2403-2412. Read SA, Collins MJ. Diurnal variation of corneal shape and thickness. Optom Vis Sci. 2009;86(3):170-80. Roshdy MMS, Wahba SS, Elkitkat RS, et al. Effect of Age on Pentacam Keratoconus Indices. J Ophthalmol. 2018;2018:2016564. Boyd BM, Bai J, Borgstrom M et al. Comparison of Chinese and North American tomographic parameters and the implications for refractive surgery screening. Asia Pac J Ophthalmol (Phila) 2020; 9: 117-125. Cao KW, Liu LN, Sun YL et al. The influence of different corneal diameters on Belin/Ambrósio enhanced ectasia display of Pentacam corneal topography. Zhonghua Yan Ke Za Zhi. 2020; 56: 761-767. Salouti R, Nowroozzadeh MH, Azizi A, et al. Angle κ and its effect on the corneal elevation maps in refractive surgery candidates. J Cataract Refract Surg. 2022;48(10):1148-1154. Tables Table 1 Demographic, tomographic and Pentacam Corneal Descritpors and comparisons between groups a . Comparison between three TP groups Comparison between two TP groups Parameter ≤500 um (n=102) 500-580 um (n=100) >580 um (n=102) P ≤500 um v.s. 500-580 um ≤500 um v.s. >580 um 500-580 um v.s. >580 um TP (um) 487.60±9.15 (456, 500) 540.96±17.07 (504, 580) 610.11±13.93 (580, 650) <0.001 <0.001 <0.001 <0.001 Age (years) 26.61±6.54 (18, 41) 27.66±7.18 (18, 46) 26.02±6.05 (18, 37) 0.302 0.302 0.710 0.121 Sex (male, %) 30.4 35 61.8 <0.001 b 0.549 b <0.001 b <0.001 b Sphere (diopter) -3.87±1.40 (-6.5, +1.0) -4.39±1.79 (-9.0, +1.0） -4.02±2.51 (-12.0, +5.0) 0.082 <0.001 0.051 0.120 Cylinder (diopter) -0.91±0.65 (-2.75, 0) -1.08±0.66 (-3.25, 0) -0.98±0.68 (-3.75, 0) 0.096 0.049 0.369 0.213 CD (mm) 11.70±0.36 (11.1, 12.6) 11.68±0.34 (11.1, 12.5) 11.64±0.28 (11.1, 12.3) 0.725 0.976 0.520 0.457 ARC (mm) 7.79±0.28 (7.34, 8.63) 7.84±0.22 (7.40, 8.31) 7.98±0.25 (7.36, 8.57) <0.001 0.098 <0.001 <0.001 PRC (mm) 6.38±0.28 (5.82, 7.15) 6.35±0.23 (5.85, 6.84) 6.38±0.25 (5.75, 6.95) 0.809 0.961 0.512 0.649 BFSa (mm) 7.90±0.28 (7.43, 8.78) 7.94±0.22 (7.48, 8.34) 8.08±0.25 (7.51, 8.65) <0.001 0.076 <0.001 <0.001 BFSp (mm) 6.50±0.27 (6.05, 7.22) 6.43±0.21 (6.02, 6.86) 6.51±0.25 (6.00, 7.16) 0.225 0.367 0.410 0.085 KAa (D) 1.24±0.70 (0, 3.20) 1.22±0.74 (0.10, 3.20) 1.37±0.64 (0.30, 3.30) 0.129 0.699 0.119 0.063 KAp (D) 0.34±0.15 (0, 0.70) 0.34±0.14 (0.10, 0.70) 0.41±0.14 (0.10, 0.80) <0.001 0.876 0.001 <0.001 Qfront -0.35±0.10 (-0.65, -0.15) -0.35±0.13 (-0.69, -0.11) -0.34±0.13 (-0.62, -0.02) 0.579 0.224 0.680 0.773 Qback -0.34±0.14 (-0.72, -0.06) -0.36±0.13 (-0.71, -0.07) -0.47±0.16 (-0.94, -0.12) <0.001 0.212 <0.001 <0.001 FE at TP (um) 2.58±1.17 (0, 5) 2.29±1.31 (-1, 5) 2.24±1.47 (-1, 7) 0.034 0.048 0.062 0.543 BE at TP (um) 5.25±3.15 (-2, 13) 5.33±3.18 (-1, 14) 7.37±4.03 (-4, 16) <0.001 0.879 <0.001 <0.001 PPImin 0.80±0.14 (0.51, 1.38) 0.76±0.12 (0.38,1.09) 0.69±0.11 (0.49, 1.02) <0.001 0.142 <0.001 <0.001 PPImax 1.42±0.19 (1.08, 2.06) 1.32±0.17 (1.02, 1.81) 1.16±0.20 (0.71, 1.77) <0.001 <0.001 <0.001 <0.001 PPIavg 1.12±0.14 (0.81, 1.60) 1.06±0.12 (0.76, 1.29) 0.95±0.13 (0.64, 1.25) <0.001 <0.001 <0.001 <0.001 ARTmax 349.94±46.74 (241, 446) 416.04±58.51 (288, 551) 540.20±93.29 (343, 865) <0.001 <0.001 <0.001 <0.001 IHD 0.01±0.005 (0.002, 0.020) 0.01±0.01 (0.002, 0.102) 0.01±0.008 (0, 0.07) 0.652 0.683 0.624 0.348 I-S (diopter) 0.73±0.38 (-0.06, 1.15) 0.004±0.46 (-0.84, 0.77) 0.09±0.61 (-1.47, 1.69) <0.001 0.001 <0.001 0.334 KISA% 16.88±18.21 (0.85, 51.70) 7.08±11.85 (0.33, 53.33) 6.72±9.43 (0.33, 53.33) 0004 0.972 0.104 0.077 Df 0.31±0.82 (-1.57, 2.60) 0.22±0.81 (-1.54, 2.60) 0.21±0.99 (-1.71, 2.98) 0.724 0.442 0.534 0.891 Db -0.10±0.86 (-1.38, 2.45) 0.17±0.94 (-1.28, 3.14) 0.76±0.96 (-1.35, 2.83) <0.001 0.052 <0.001 <0.001 Dp 1.48±0.96 (-0.62, 4.68) 1.02±0.83 (-0.99, 2.62) 0.29±0.88 (-1.78, 2.36) <0.001 <0.001 <0.001 <0.001 Dt 1.57±0.31 (1.17, 2.75) -0.08±0.49 (-1.17, 1.03) -1.82±0.31 (-2.66, -1.12) <0.001 <0.001 <0.001 <0.001 Da 1.27±0.45 (0.39, 2.59) 0.66±0.54 (-0.58, 1.83) -0.48±0.85 (-3.45, 1.32) <0.001 <0.001 <0.001 <0.001 BAD-D 1.63±0.50 (0.21, 2.58) 1.11±0.56 (-0.41, 2.18) 0.50±0.61 (-0.75, 2.10) <0.001 <0.001 <0.001 <0.001 a Continuous variables following normal distribution were analyzed by analysis of variance or student’s t test with Bonferroni correction; skewed data were analyzed by Kruskal-Wallis test and Mann-Whitney U test. b Chi-square test. TP = thinnest pachymetry; CD = corneal diameter; ARC = anterior radius of curvature for a 3-mm zone centered on the thinnest point; PRC = posterior radius of curvature for a 3-mm zone centered on the thinnest point; BFSa = the best-fit sphere for the anterior cornea; BFSp = the best-fit sphere for the posterior cornea; KAa = corneal astigmatism for the anterior cornea; KAp = corneal astigmatism for the posterior cornea; Qfront = Q value for the front surface; Qback = Q value for the back surface; FE at TP = front elevation at thinnest pachymetry ; BE at TP = back elevation at thinnest pachymetry; PPI = pachymetric progression indices (min = minimum, avg = average, max =maximum); ARTmax = Ambrósio’s maximum relational thickness index; IHD=index of height decentration; I-S = inferior-superior value; KISA% = keratoconus percentage index; Df = deviation of normality of the front elevation; Db = deviation of normality of the back elevation; Dp = deviation of normality of pachymetric progression; Dt = deviation of normality of corneal thinnest point; Da = deviation of normality of relational thickness; BAD-D = Belin/Ambrósio Enhanced Ectasia display (overall deviation of normality). Table 2. Comparisons for the percentages of abnormality for individual Keratoconus Indices between different thickness groups. 580 um (n=102) P a Parameters Normal Abnormal Normal Abnormal Normal Abnormal FE 102 (100%) 0 (0%) 100 (100%) 0 (0%) 99 (97.1%) 3 (2.9%) 0.109 b BE 100 (98.0%) 2 (2.0%) 97 (97.0%) 3 (3.0%) 85 (83.3%) 17 (16.7%) <0.001 IHD 77 (75.5%) 25 (24.5%) 81 (81.0%) 19 (19.0%) 78 (76.5%) 24 (23.5%) 0.618 PPImin 54 (52.9%) 48 (47.1%) 60 (60.0%) 40 (40.0%) 79 (77.5%) 23 (22.5%) 0.001 PPImax 60 (58.8%) 42 (41.2%) 79 (79.0%） 21 (21.0%) 93 (91.2%) 9 (8.8%) <0.001 PPIavg 62 (60.8%) 40 (39.2%) 80 (80.0%) 20 (20.0%) 96 (94.1%) 6 (5.9%) <0.001 ARTmax 78 (76.5%) 24 (23.5%) 96 (96.0%) 4 (4.0%) 102 (100%) 0 (0%) <0.001 b Df 93 (91.2%) 9 (8.8%) 95 (95.0%) 5 (5.0%) 94 (92.2%) 8 (7.8%) 0.618 Db 98 (96.1%) 4 (3.9%) 88 (88.0%) 12 (12.0%) 81 (79.4%) 21 (20.6%) 0.001 Dp 61 (59.8%) 41 (40.2%) 77 (77.0%) 23 (23.0%) 95 (93.1%) 7 (6.9%) <0.001 Dt 64 (62.7%) 38 (37.3%) 100 (100%) 0 (0%) 102 (100%) 0 (0%) <0.001 Da 77 (75.5%) 25 (24.5%) 96 (96.0%) 4 (4.0%) 102 (100%) 0 (0%) <0.001 b BAD-D 46 (45.1%) 56 (54.9%） 79 (79.0%) 21 (21.0%) 96 (94.1%) 6 (5.9%) <0.001 a Chi-square test b Fisher’s exact test FE = front elevation; BE = back elevation; IHD=index of height decentration; PPI = pachymetric progression indices (min = minimum, avg = average, max = maximum); ARTmax = Ambrósio’s maximum relational thickness index; Df = deviation of normality of the front elevation; Db = deviation of normality of the back elevation; Dp =deviation of normality of pachymetric progression; Dt = deviation of normality of corneal thinnest point; Da = deviation of normality of relational thickness; BAD-D = Belin/Ambrósio Enhanced Ectasia display (overall deviation of normality). Table 3 Comparison of individual Pentacam Corneal Descritpors between BE groups in eyes with TP≥580um. Parameter BE<11.77 BE ≥ 11.77 P a TP (um) 610.79±13.38 (580, 650) 606.71±16.45 (585, 649) 0.169 Age (years) 26.75±6.08 (18, 38) 22.35±4.47 (18, 36) 0.681 Sex (male, %) 65.9 47.1 0.118 b Sphere (D) -4.29±2.43 (-12, +1.0) -2.66±2.55 (-6.0, +5.0） 0.049 Cylinder (D) -0.92±0.62 (-3.0, 0) -1.30±0.91 (-3.75, 0) 0.082 CD (mm) 11.66±0.28 (11.1, 12.3) 11.53±0.26 (11.2, 12.2) 0.052 ARC (mm) 7.99±0.24 (7.47, 8.57) 7.92±0.25 (7.36, 8.33) 0.262 PRC (mm) 6.41±0.23 (5.85, 6.95) 6.22±0.25 (5.75, 6.66) 0.004 BFSa (mm) 8.08±0.25 (7.51, 8.65) 8.04±0.27 (7.55, 8.36) 0.475 BFSp (mm) 6.51±0.25 (6.05, 7.16) 6.47±0.26 (6.00, 6.98) 0.815 KAa (diopter) 1.29±0.58 (0.30, 2.90) 1.75±0.79 (0.60, 3.30) 0.057 KAp (diopter) 0.39±0.13 (0.10, 0.80) 0.48±0.13 (0.20, 0.70) 0.297 Qfront -0.32±0.12 (-0.58, -0.02) -0.42±0.13 (-0.62, -0.15) 0.004 Qback -0.44±0.15 (-0.94, -0.12) -0.58±0.14 (-0.89, -0.37) 0.001 FE at TP (um) 2.08±1.24 (0, 5) 3.00±2.21 (-1, 7) 0.134 BE at TP (um) 6.20±3.30 (-4, 11) 13.24±1.25 (12, 16) <0.001 PPImin 0.69±0.11 (0.49, 1.02) 0.73±0.13 (0.56, 0.95) 0.343 PPImax 1.12±0.17 (0.71, 1.55) 1.35±0.20 (1.03, 1.77) <0.001 PPIavg 0.93±0.13 (0.64, 1.21) 1.04±0.12 (0.89, 1.25) 0.001 ARTmax 556.65±89.08 (405, 865) 457.94±68.19 (343, 589) <0.001 IHD 0.01±0.01 (0, 0.07) 0.01±0.01 (0.002, 0.035) 0.248 I-S (diopter) 0.03±0.58 (-1.47, 1.26) 0.42±0.75 (-0.59, 1.69) 0.190 KISA% 6.91±10.12 (0.33, 53.33) 5.67±3.63 (0.63, 9.73) 0.625 Df 0.12±0.91 (-1.71, 2.29) 0.66±1.25 (-1.57, 2.98) 0.145 Db 0.63±0.95 (-1.35, 2.83) 1.40±0.71 (0.13, 2.80) 0.002 Dp 0.16±0.85 (-1.78, 2.03) 0.91±0.80 (-0.12, 2.36) 0.001 Dt -1.84±0.30 (-2.66, -1.12) -1.75±0.37 (-2.66, -1.24) 0.167 Da -0.63±0.81 (-3.45, 0.76) 0.27±0.62 (-0.92, 1.32) <0.001 BAD-D 0.35±0.52 (-0.75, 1,60) 1.26±0.48 (0.49, 2.10) <0.001 a Continuous variables following normal distribution were analyzed by student’s t test; skewed data were analyzed by Mann-Whitney U test. b Chi-square test. TP = thinnest pachymetry; CD = corneal diameter; D = diopters; ARC = anterior radius of curvature for a 3-mm zone centered on the thinnest point; PRC = posterior radius of curvature for a 3-mm zone centered on the thinnest point; BFSa = the best-fit sphere for the anterior cornea; BFSp = the best-fit sphere for the posterior cornea; KAa = corneal astigmatism for the anterior cornea; KAp = corneal astigmatism for the posterior cornea; Qfront = Q value for the front surface; Qback = Q value for the back surface; FE at TP = front elevation at thinnest pachymetry; BE at TP = back elevation at thinnest pachymetry; PPI = pachymetric progression indices (min = minimum, avg = average, max =maximum); ARTmax = Ambrósio’s maximum relational thickness index; IHD=index of height decentration; I-S = inferior-superior value; KISA% = keratoconus percentage index; Df = deviation of normality of the front elevation; Db = deviation of normality of the back elevation; Dp = deviation of normality of pachymetric progression; Dt = deviation of normality of corneal thinnest point; Da = deviation of normality of relational thickness; BAD-D = Belin/Ambrósio Enhanced Ectasia display (overall deviation of normality) Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 10 Feb, 2025 Read the published version in BMC Ophthalmology → Version 1 posted Editorial decision: Revision requested 07 Nov, 2024 Reviews received at journal 30 Oct, 2024 Reviewers agreed at journal 29 Oct, 2024 Reviews received at journal 13 Jul, 2024 Reviews received at journal 26 Jun, 2024 Reviewers agreed at journal 19 Jun, 2024 Reviewers agreed at journal 14 Jun, 2024 Reviews received at journal 10 Jun, 2024 Reviewers agreed at journal 04 Jun, 2024 Reviewers invited by journal 23 May, 2024 Editor invited by journal 19 Feb, 2024 Submission checks completed at journal 19 Feb, 2024 Editor assigned by journal 19 Feb, 2024 First submitted to journal 19 Feb, 2024 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. 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The Scheimpflug principle-based device\u0026nbsp;employs a rotating camera to measure elevation points, providing a three-dimensional reconstruction of the entire cornea, encompassing both anterior and posterior surfaces, corneal thickness, and various\u0026nbsp;standardized indices for ectasia detection,\u0026nbsp;such as\u0026nbsp;the Belin/Ambrosio Enhanced Ectasia display (BAD display)\u0026nbsp;\u003csup\u003e[1]\u003c/sup\u003e. As the most widely used device for corneal evaluation, recent studies have revealed that certain factors, such as eyelid morphometry\u003csup\u003e[2]\u003c/sup\u003e and corneal diameter (CD) \u003csup\u003e[3]\u003c/sup\u003e, can influence the values of certain tomographic indices, thus affecting their interpretation.\u003c/p\u003e\n\u003cp\u003eParameters related to corneal thickness, such as the thinnest pachymetry (TP) and pachymetric indices, have become crucial in preoperative evaluations. According to a large-sample epidemiological study by Ma et al., the median TP for Chinese young adults was approximately 540 \u0026mu;m (Quartile 1 to Quartile 3: 520-570 \u0026mu;m) \u003csup\u003e[4]\u003c/sup\u003e. While a thin cornea has been considered a risk factor for KC, limited research has focused on the impact of a thick cornea on KC indices. Roshdy et al.\u0026nbsp;\u003csup\u003e[5]\u003c/sup\u003e discovered that thicker corneas in an Egyptian population (\u0026gt;564 \u0026mu;m) displayed significantly higher values of back elevation (BE). However, as this study only analyzed pachymetric and elevation data with a relatively small sample size, the influence of thick corneas on KC screening remains uncertain.\u003c/p\u003e\n\u003cp\u003eThe objective of this study is to investigate the tomographic characteristics of thick corneas using the Pentacam HR device (OCULUS GmbH, Wetzlar, Germany) and to explore its potential impact on the screening of candidates for refractive surgery.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cstrong\u003eParticipants\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis cross-section study included participants who were selected from the Fudan University EENT Hospital Refractive Center Database from January 202 to January 2023. The inclusion criteria were as follows: participants who were followed-up once a year for at least 3 years; age between 18 and 50 years; unremarkable slit-lamp examination;\u0026nbsp;normal tomography (ABCD classification system, stage 0, and overall deviation of normality [BAD-D] \u0026lt;2.6), and a horizontal corneal diameter of \u0026ge;11.1mm in both eyes as measured by the\u0026nbsp;Pentacam HR (OCULUS Optikgerate GmbH, Wetzlar, Germany). Stage 0 in the ABCD classification system was specified as follows: anterior radius of curvature for a 3.0 mm zone centered on the thinnest point (ARC) \u0026gt; 7.25 mm, posterior radius of curvature for a 3.0 mm zone centered on the thinnest point (PRC) \u0026gt; 5.9 mm, the thinnest pachymetry (TP) \u0026gt; 490 \u0026mu;m, the best documented visual acuity \u0026ge; 1.0, and the absence of corneal scarring. Cases with any pathological ocular conditions or relevant systemic diseases were excluded. Soft contact lens wear was discontinued for at least 7 days before the examination, while rigid or hybrid contact lenses were discontinued for a minimum period of 3 weeks. The study received approval from the Ethics Committee of the Eye and ENT Hospital of Fudan University in Shanghai, China, and was conducted in accordance with tenets of the Declaration of Helsinki. Written informed consent was obtained from all participants before their inclusion in this study. The corneas included in the study were categorized into three groups based on epidemiological data\u0026nbsp;\u003csup\u003e[4]\u003c/sup\u003e: group 1 comprised eyes with TP less than 500 \u0026mu;m, group 2 included eyes with TP between 500 and 580 \u0026mu;m, and group 3 encompassed eyes with TP greater than 580 \u0026mu;m.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCorneal Tomography\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA comprehensive ophthalmic examination was conducted for all patients, which included a slit-lamp examination, objective and subjective refractions, and Pentacam HR examination. The Pentacam imaging was performed by the same experienced examiner (YJ) for all participants, with three measurements averaged for each individual. Only scans meeting the \u0026quot;OK\u0026quot; criteria as per the Examination Quality Specification of the instrument were utilized for analysis.\u003c/p\u003e\n\u003cp\u003eThe following corneal characteristics were obtained using the Pentacam software: thinnest pachymetry (TP), horizontal corneal diameter (CD), anterior radius of curvature for a 3-mm zone centered on the thinnest point (ARC), posterior radius of curvature for a 3-mm zone centered on the thinnest point (PRC), best fit sphere for the anterior cornea (BFSa), best fit sphere for the posterior cornea (BFSp), corneal astigmatism of the anterior and posterior cornea for a 3-mm zone centered on the thinnest point (KAa and KAp), asphericity (Q-value) of the front (Qfront) and back corneal surface (Qback), front and back corneal elevations at TP (FE and BE), pachymetric progression index (PPI, including minimum, average, and maximum values), Ambr\u0026oacute;sio\u0026apos;s maximum relational thickness index (ARTmax),\u0026nbsp;index of height decentration (IHD),\u0026nbsp;inferior-superior value (I-S), and keratoconus percentage index (KISA%). The BAD normalized indices include deviation of normality of the front elevation (Df), deviation of normality of the back elevation (Db), deviation of normality of pachymetric progression (Dp), deviation of normality of corneal thinnest point (Dt), deviation of normality of relational thickness (Da), and overall deviation of normality (BAD-D). The analyzing dimensions for these indices are all 8 mm in diameter. PPI represents the change in corneal thickness from TP to the periphery and can be calculated over all 360 degrees of the cornea. The average of these meridians is represented as PPIavg, while the meridian with the maximum pachymetric increase is PPImax, and the one with the minimum pachymetric increase is PPImin. The deviation-based indices are categorized by the software as normal (\u0026lt;1.6 standard deviations [SD] from the population mean, indicated in white), suspicious (\u0026ge;1.6 SD and \u0026lt;2.6 SD, highlighted in yellow), and pathologic (\u0026ge;2.6 SD, highlighted in red), based on data reported by Ambr\u0026oacute;sio et al.,\u003csup\u003e[6]\u003c/sup\u003e\u003csup\u003e\u0026nbsp;\u003c/sup\u003eand this classification was consistently applied throughout this study. FE was classified as normal (\u0026lt;5.01), suspicious (\u0026ge;5.01 and \u0026lt;7.14), and pathologic (\u0026ge;7.14), while BE (for myopia only) was categorized as normal (\u0026lt;11.77), suspicious (\u0026ge;11.77 and \u0026lt;16.42), and pathologic (\u0026ge;16.42).\u0026nbsp;For the\u0026nbsp;purpose\u0026nbsp;of\u0026nbsp;statistical analysis, eyes\u0026nbsp;classified as \u0026apos;suspect\u0026apos; and \u0026apos;abnormal\u0026apos;\u0026nbsp;were\u0026nbsp;grouped as \u0026apos;abnormal\u0026apos;\u0026nbsp;for\u0026nbsp;the aforementioned\u0026nbsp;indices. Other\u0026nbsp;indices were categorized as normal or abnormal in accordance with the cutoff values provided by the manufacturer or Feng et al.: PPImin (abnormal: \u0026ge;0.79); PPIavg (abnormal: \u0026ge;1.15); PPImax (abnormal: \u0026ge;1.44); ARTmax (abnormal: \u0026le;313); IHD (abnormal: \u0026ge;0.014); I-S (abnormal: \u0026ge;1.4D); KISA% (abnormal: \u0026ge;60%).\u003csup\u003e[7, 8]\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical Analysis\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe statistical analysis was carried out using SPSS 13.0 software (IBM, Armonk, NY, USA). The normality assumption of the data was assessed using the Kolmogorov-Smirnov test. Continuous variables with a normal distribution were compared using analysis of variance (ANOVA) between 3 groups or Student\u0026apos;s t-test with Bonferroni correction between 2 groups. Data with a non-normal distribution were analyzed using the Mann-Whitney U test between two groups and the Kruskal-Wallis test between three groups. The percentages of abnormality between groups were compared using the chi-square test or the Fisher exact test. A P value of less than 0.05 was considered to be statistically significant.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eThe study involved 102 eyes of 102 patients with TP\u0026nbsp;\u0026lt; 500\u0026mu;m (Group 1), 100 eyes of 100 patients with TP between 500 and 580 \u0026mu;m (Group 2), and 102 eyes of 102 subjects with\u0026nbsp;TP\u0026nbsp;\u0026ge; 580\u0026mu;m\u0026nbsp;(Group 3). Demographic characteristics and the means for individual Pentacam corneal descriptors are presented in Table 1. The mean TP was 487.60\u0026plusmn;9.15, 540.96\u0026plusmn;17.07, and 610.11\u0026plusmn;13.93 \u0026mu;m for the three groups, respectively (Kruskal-Wallis tests: P\u0026lt;0.001). No significant difference in age was found between the three groups (Kruskal-Wallis tests: P=0.121). A higher proportion of males was observed in Group 3 compared to the other two groups (Chi-square test: P\u0026lt;0.001).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eComparisons between TP groups for\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003ecorneal descriptors\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCompared to eyes with TP between 500 and 580 \u0026mu;m, greater values in ARC, KAp, BE at TP, ARTmax, and Db were demonstrated by eyes with TP\u0026nbsp;\u0026ge; 580\u0026mu;m (Mann-Whitney U test: P\u0026lt;0.001), along with a more negative Qback (Mann-Whitney U test: P\u0026lt;0.001, Table 1). No significant differences were found in the anterior corneal indices (Mann-Whitney U test: IHD, P=0.348; I-S, P=0.334; KISA%, P=0.077; Df, P=0.891).\u003c/p\u003e\n\u003cp\u003eCompared to eyes with TP between 500 and 580 \u0026mu;m, greater FE at TP (Mann-Whitney U test: P=0.045), I-S (Mann-Whitney U test: P=0.001), PPImax, PPIavg, Dp, Dt, Da, and BAD-D were exhibited by eyes with TP less than 500 \u0026mu;m (Mann-Whitney U test: P\u0026lt;0.001). ARTmax was significantly smaller for eyes with TP less than 500 \u0026mu;m (Mann-Whitney U test: P\u0026lt;0.001, Table 1).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eComparisons between TP groups for the classification results of the KC\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003edescriptors\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe results of classifications for individual KC indices in each group are summarized in Table 2. The highest proportion of abnormalities was observed in eyes with TP\u0026nbsp;\u0026ge; 580\u0026mu;m for BE (16.7%, Chi-square test: P\u0026lt;0.001) and Db (20.6%, Chi-square test: P=0.001). In eyes with TP less than 500 \u0026mu;m, the highest proportion of abnormalities was found for PPImin (47.1%, Chi-square test: P\u0026lt;0.001), PPImax (41.2%, P\u0026lt;0.001), PPIavg (39.2%, P\u0026lt;0.001), ARTmax (23.5%, P\u0026lt;0.001), Dp (40.2%, P\u0026lt;0.001), Dt (37.3%, P\u0026lt;0.001), Da (24.5%, P\u0026lt;0.001), and BAD-D (54.9%, P\u0026lt;0.001).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eComparison of individual Pentacam Corneal Descritpors between BE groups in eyes with TP\u0026ge;580um\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAmong the 22 eyes with BE\u0026ge;11.77, 17 belonged to Group 3. Subsequently, the eyes in Group 3 were subdivided into two groups based on the values of BE (BE\u0026lt;11.77 or BE\u0026ge;11.77, see Table 3). Eyes with BE\u0026ge;11.77 exhibited a smaller PRC (Student\u0026apos;s t-test: P=0.004) and ARTmax (Student\u0026apos;s test: P\u0026lt;0.001), a more negative Qfront (Student\u0026apos;s t-test: P=0.004) and Qback (Mann-Whitney U test: P=0.001), as well as a greater PPImax (Mann-Whitney U test: P=0.001), PPIavg (Mann-Whitney U test: P=0.001), Db (Student\u0026apos;s test: P=0.002), Dp (Student\u0026apos;s test: P=0.001), Da (Student\u0026apos;s test: P\u0026lt;0.001), and BAD-D (Mann-Whitney U test: P\u0026lt;0.001). No differences were observed in IHD (Mann-Whitney U test: P=0.248), I-S (P=0.190), KISA% (P=0.625), and Df (P=0.145).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eTo date, limited research has delved into the tomographic attributes of thick corneas. This study has uncovered that thick corneas (TP\u0026ge;580\u0026mu;m) exhibit heightened posterior corneal astigmatism, increased BE and Db, along with a more negative asphericity of the posterior cornea. Notably, no significant disparities emerged in the anterior corneal indices (IHD, I-S, KISA%, and Df).\u003c/p\u003e\n\u003cp\u003e\u0026nbsp; Evaluating corneal shape stands as a pivotal facet of the preoperative assessment of refractive surgery candidates.\u0026nbsp;Past investigations primarily concentrated\u0026nbsp;on thin corneas, which have\u0026nbsp;conventionally\u0026nbsp;been\u0026nbsp;identified\u0026nbsp;as a\u0026nbsp;principal\u0026nbsp;keratoconus\u0026nbsp;risk factor. However,\u0026nbsp;scant attention has\u0026nbsp;been\u0026nbsp;given to\u0026nbsp;thick\u0026nbsp;corneas. Our findings align with the outcomes of Roshdy\u0026apos;s\u0026nbsp;study,\u003csup\u003e\u0026nbsp;[5\u003c/sup\u003e\u003csup\u003e]\u003c/sup\u003e which demonstrated\u0026nbsp;that thicker corneas\u0026nbsp;manifest\u0026nbsp;higher\u0026nbsp;BE\u0026nbsp;values. The\u0026nbsp;augmented\u0026nbsp;BE could be\u0026nbsp;attributed to\u0026nbsp;the more negative Qback in thick\u0026nbsp;corneas. Although no substantial distinctions were observed\u0026nbsp;in the posterior curvature of\u0026nbsp;the\u0026nbsp;3mm\u0026nbsp;zone among the different\u0026nbsp;thickness groups, the more prolate corneal shape in thick\u0026nbsp;corneas\u0026nbsp;may be\u0026nbsp;attributed\u0026nbsp;to a flatter peripheral cornea.\u0026nbsp;Additionally, the\u0026nbsp;study\u0026nbsp;unveiled\u0026nbsp;that posterior corneal astigmatism\u0026nbsp;is more pronounced\u0026nbsp;in thicker\u0026nbsp;corneas, which\u0026nbsp;could be\u0026nbsp;an additional factor contributing to the elevated\u0026nbsp;back elevation in thick\u0026nbsp;corneas\u003csup\u003e[9]\u003c/sup\u003e.\u0026nbsp;Furthermore, measurement\u0026nbsp;errors\u0026nbsp;may lead to higher BE values in thicker corneas\u0026nbsp;when corneal thickness\u0026nbsp;deviates significantly from\u0026nbsp;the adjusted normative database, as previously\u0026nbsp;reported by Roshdy et al. \u003csup\u003e[5\u003c/sup\u003e\u003csup\u003e]\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003eIn this study, eyes with TP\u0026ge;580\u0026mu;m\u0026nbsp;were categorized into two groups based on their BE values. The results\u0026nbsp;revealed\u0026nbsp;that eyes with\u0026nbsp;elevated\u0026nbsp;BE were\u0026nbsp;associated with a\u0026nbsp;steeper posterior curvature and increased Qfront and Qback.\u0026nbsp;Additionally, these patients exhibited significantly higher\u0026nbsp;values\u0026nbsp;in\u0026nbsp;two pachymetric progression indices\u0026nbsp;(PPImax and PPIavg) and four\u0026nbsp;normalized indices (Db, Dp, Da, and BAD-D). However, no significant differences were discerned in parameters related to the anterior cornea (IHD, I-S, KISA%, and Df) between eyes with elevated BE and normal controls. The earliest signs of keratoconus have long been a topic of debate. Although back elevation abnormalities have been considered a fundamental diagnostic criterion for subclinical keratoconus according to the Global Consensus on Keratoconus and Ectatic Diseases,\u003csup\u003e[10]\u003c/sup\u003e recent studies have indicated that both back elevation and regional thickness irregularities are less effective at distinguishing forme fruste keratoconus (FFKC) from normal eyes compared to parameters associated with the anterior cornea.\u003csup\u003e[11, 12]\u003c/sup\u003e Studies employing spectral domain OCT have affirmed that the earliest structural changes related to keratoconus involve epithelial remodeling with compensatory thinning at the apex.\u003csup\u003e[13, 14]\u003c/sup\u003e Therefore, the heightened BE and pachymetric progression indices in thick corneas, in the absence of anterior corneal irregularities, may stem from the distinct corneal shape (more prolate) in thick corneas, rather than representing early signs of keratoconus. A conclusive judgment awaits long-term observations of these eyes.\u003c/p\u003e\n\u003cp\u003eVariations in corneal thickness have the potential to impact the corneal shape. Studies on the diurnal changes in the cornea have revealed that the thickening of the cornea upon waking is accompanied by the flattening of the anterior corneal surface and a steepening of the posterior surface.\u003csup\u003e[15]\u0026nbsp;\u003c/sup\u003eAdditionally, various factors have been reported to have potential effects on the elevation maps and pachymetry-based parameters.\u003csup\u003e[16]\u003c/sup\u003e Small corneas have been shown to exhibit higher rates of false positives for several BAD parameters, especially BE, Db, and PPIavg.\u003csup\u003e[3,17,18]\u003c/sup\u003e Consequently, only eyes with a CD of 11.1mm or greater were included in this study. Furthermore, both large angle kappa and corneal astigmatism were found to influence the corneal elevation maps.\u003csup\u003e[19]\u003c/sup\u003e These studies recommend adjusting the normative database to account for variations in these factors.\u003c/p\u003e\n\u003cp\u003eThe present study also incorporated a group of eyes with a TP less than 500 \u0026mu;m. The results were consistent with previous research indicating that pachymetric progression indices, as well as Dp, Dt, and BAD-D among the BAD normalized indices, were most sensitive to corneal thinning. \u003csup\u003e[5, 6]\u003c/sup\u003e\u003c/p\u003e"},{"header":"Limitations","content":"\u003cp\u003eThe primary limitation of this study is its cross-sectional nature. Therefore, we included only patients who have been followed-up for at least 3 years and their topographies remained normal. Further study involving patients who had undergone uneventful corneal refractive surgery with at least 2 years of stable follow-up could help to make the conclusions more convincing. The second limitation is the exclusive use of the Scheimpflug device in this study. It is highly recommended that further research should explore different technologies, such as corneal biomechanical assessments using Corvis ST or Ocular Response Analyzer (ORA), Placido disk topography combined with Scheimpflug rotating cameras (e.g., Sirius tomography system), and corneal epithelium thickness mapping using anterior segment optical coherence tomography.\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn comparison with eyes of normal thickness (500-580 \u0026mu;m), eyes with thicker corneas (\u0026gt;580 \u0026mu;m) demonstrated higher BE and Db, a more negative Qback, and no significant differences in anterior corneal indices when measured using the Scheimpflug device. The distinctive features of the back surface in thick corneas may be attributed to the distinct corneal shape (more prolate back cornea) and a higher pachymetric progression rate. Further research is required to confirm the long-term safety of performing corneal refractive surgery on these patients.\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eEthics approval for this study was granted by the Ethics Committee of the Eye and ENT Hospital of Fudan University (Shanghai, China. No. 2021026). It was conducted in compliance with the tenets of the Declaration of Helsinki. Written informed consent was obtained from all the patients.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was supported by the Natural Science Foundation of Minhang District, Shanghai, China (2023MHZ066) and the Research Project Grant of Shanghai Municipal Health Commission (202340220).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eConceptualization: Yishan Qian; Methodology: Junjie Yu; Formal analysis and investigation: Ye Xu and Junjie Yu; Writing - original draft preparation: Yishan Qian; Writing - review and editing: Xiaoying Wang; Funding acquisition: Yishan Qian; Supervision: Xiaoying Wang.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe would like to thank Editage (www.editage.cn) for English language editing.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eVinciguerra P, Camesasca FI. Prevention of corneal ectasia in laser in situ keratomileusis. J Refract Surg. 2001;17(2 Suppl):S187-9.\u003c/li\u003e\n \u003cli\u003eMaseedupally V, Gifford P, Swarbrick H. Variation in normal corneal shape and the influence of eyelid morphometry. Optom Vis Sci. 2015;92(3):286-300.\u003c/li\u003e\n \u003cli\u003eDing L, Wang J, Niu L, et al. Pentacam Scheimpflug Tomography findings in chinese patients with different corneal diameters. J Refract Surg. 2020;36(10):688-695.\u003c/li\u003e\n \u003cli\u003eMa R, Liu Y, Zhang L, et al. Distribution and Trends in Corneal Thickness Parameters in a Large Population-Based Multicenter Study of Young Chinese Adults. Invest Ophthalmol Vis Sci. 2018;59(8):3366-3374.\u003c/li\u003e\n \u003cli\u003eRoshdy MMS, Wahba SS, Elkitkat RS, et al. Pentacam HR Indices Variation in Normal Corneas with Different Corneal Thickness. J Ophthalmol. 2018;2018:9328120.\u003c/li\u003e\n \u003cli\u003eAmbr\u0026oacute;sio R Jr, Caiado AL, Guerra FP, et al. Novel pachymetric parameters based on corneal tomography for diagnosing keratoconus. J Refract Surg. 2011;27(10):753-8.\u003c/li\u003e\n \u003cli\u003eFeng MT, Belin MW, Ambr\u0026oacute;sio R Jr, et al. International values of corneal elevation in normal subjects by rotating Scheimpflug camera. J Cataract Refract Surg. 2011;37(10):1817-21.\u003c/li\u003e\n \u003cli\u003eRabinowitz YS, Rasheed K. KISA% index: a quantitative videokeratography algorithm embodying minimal topographic criteria for diagnosing keratoconus. J Cataract Refract Surg. 1999;25(10):1327-35\u003c/li\u003e\n \u003cli\u003eGatinel D, Malet J, Hoang-Xuan T, et al. Corneal elevation topography: best fit sphere, elevation distance, asphericity, toricity, and clinical implications. Cornea. 2011;30(5):508-15.\u003c/li\u003e\n \u003cli\u003eGomes JA, Tan D, Rapuano CJ, et al. Global consensus on keratoconus and ectatic diseases. Cornea. 2015;34(4):359-69.\u003c/li\u003e\n \u003cli\u003eDonoso R, Rodr\u0026iacute;guez \u0026Aacute;, Esteffan K, et al. Analysis of OPD-Scan and Pentacam Parameters for Early Keratoconus Detection. Am J Ophthalmol. 202;226:235-242.\u003c/li\u003e\n \u003cli\u003eHwang ES, Perez-Straziota CE, Kim SW, et al. Distinguishing Highly Asymmetric Keratoconus Eyes Using Combined Scheimpflug and Spectral-Domain OCT Analysis. Ophthalmology. 2018;125(12):1862-1871.\u003c/li\u003e\n \u003cli\u003eSilverman RH, Urs R, Roychoudhury A, et al. Epithelial remodeling as basis for machine-based identification of keratoconus. Invest Ophthalmol Vis Sci. 2014;55(3):1580-7.\u003c/li\u003e\n \u003cli\u003eSandali O, El Sanharawi M, Temstet C, et al. Fourier-domain optical coherence tomography imaging in keratoconus: a corneal structural classification. Ophthalmology. 2013;120(12):2403-2412.\u003c/li\u003e\n \u003cli\u003eRead SA, Collins MJ. Diurnal variation of corneal shape and thickness. Optom Vis Sci. 2009;86(3):170-80.\u003c/li\u003e\n \u003cli\u003eRoshdy MMS, Wahba SS, Elkitkat RS, et al. Effect of Age on Pentacam Keratoconus Indices. J Ophthalmol. 2018;2018:2016564.\u003c/li\u003e\n \u003cli\u003eBoyd BM, Bai J, Borgstrom M et al. Comparison of Chinese and North American tomographic parameters and the implications for refractive surgery screening. Asia Pac J Ophthalmol (Phila) 2020; 9: 117-125.\u003c/li\u003e\n \u003cli\u003eCao KW, Liu LN, Sun YL et al. The influence of different corneal diameters on Belin/Ambr\u0026oacute;sio enhanced ectasia display of Pentacam corneal topography. Zhonghua Yan Ke Za Zhi. 2020; 56: 761-767.\u003c/li\u003e\n \u003cli\u003eSalouti R, Nowroozzadeh MH, Azizi A, et al. Angle \u0026kappa; and its effect on the corneal elevation maps in refractive surgery candidates. J Cataract Refract Surg. 2022;48(10):1148-1154.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable 1 Demographic, tomographic and Pentacam Corneal Descritpors and comparisons between groups \u003csup\u003ea\u003c/sup\u003e.\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"4\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eComparison between three TP groups\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eComparison between two TP groups\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e\u003cstrong\u003eParameter\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026le;500 um\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=102)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e500-580 um\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=100)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026gt;580 um\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=102)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eP\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026le;500 um v.s. 500-580 um\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026le;500 um v.s. \u0026gt;580 um\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e500-580 um v.s. \u0026gt;580 um\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eTP (um)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e487.60\u0026plusmn;9.15\u003c/p\u003e\n \u003cp\u003e(456, 500)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e540.96\u0026plusmn;17.07\u003c/p\u003e\n \u003cp\u003e(504, 580)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e610.11\u0026plusmn;13.93\u003c/p\u003e\n \u003cp\u003e(580, 650)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eAge (years)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e26.61\u0026plusmn;6.54\u003c/p\u003e\n \u003cp\u003e(18, 41)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e27.66\u0026plusmn;7.18\u003c/p\u003e\n \u003cp\u003e(18, 46)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e26.02\u0026plusmn;6.05\u003c/p\u003e\n \u003cp\u003e(18, 37)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.302\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.302\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.710\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.121\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eSex (male, %)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e30.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e61.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.549\u003csup\u003e\u0026nbsp;b\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003csup\u003e\u0026nbsp;b\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003csup\u003e\u0026nbsp;b\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eSphere (diopter)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-3.87\u0026plusmn;1.40\u003c/p\u003e\n \u003cp\u003e(-6.5, +1.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-4.39\u0026plusmn;1.79\u003c/p\u003e\n \u003cp\u003e(-9.0, +1.0）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-4.02\u0026plusmn;2.51\u003c/p\u003e\n \u003cp\u003e(-12.0, +5.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.082\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.051\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.120\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eCylinder (diopter)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-0.91\u0026plusmn;0.65\u003c/p\u003e\n \u003cp\u003e(-2.75, 0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-1.08\u0026plusmn;0.66\u003c/p\u003e\n \u003cp\u003e(-3.25, 0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-0.98\u0026plusmn;0.68\u003c/p\u003e\n \u003cp\u003e(-3.75, 0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.096\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.049\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.369\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.213\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eCD (mm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e11.70\u0026plusmn;0.36\u003c/p\u003e\n \u003cp\u003e(11.1, 12.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e11.68\u0026plusmn;0.34\u003c/p\u003e\n \u003cp\u003e(11.1, 12.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e11.64\u0026plusmn;0.28\u003c/p\u003e\n \u003cp\u003e(11.1, 12.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.725\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.976\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.520\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.457\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eARC (mm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e7.79\u0026plusmn;0.28\u003c/p\u003e\n \u003cp\u003e(7.34, 8.63)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e7.84\u0026plusmn;0.22\u003c/p\u003e\n \u003cp\u003e(7.40, 8.31)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e7.98\u0026plusmn;0.25\u003c/p\u003e\n \u003cp\u003e(7.36, 8.57)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.098\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ePRC (mm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e6.38\u0026plusmn;0.28\u003c/p\u003e\n \u003cp\u003e(5.82, 7.15)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e6.35\u0026plusmn;0.23\u003c/p\u003e\n \u003cp\u003e(5.85, 6.84)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e6.38\u0026plusmn;0.25\u003c/p\u003e\n \u003cp\u003e(5.75, 6.95)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.809\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.961\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.512\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.649\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eBFSa (mm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e7.90\u0026plusmn;0.28\u003c/p\u003e\n \u003cp\u003e(7.43, 8.78)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e7.94\u0026plusmn;0.22\u003c/p\u003e\n \u003cp\u003e(7.48, 8.34)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e8.08\u0026plusmn;0.25\u003c/p\u003e\n \u003cp\u003e(7.51, 8.65)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.076\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eBFSp (mm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e6.50\u0026plusmn;0.27\u003c/p\u003e\n \u003cp\u003e(6.05, 7.22)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e6.43\u0026plusmn;0.21\u003c/p\u003e\n \u003cp\u003e(6.02, 6.86)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e6.51\u0026plusmn;0.25\u003c/p\u003e\n \u003cp\u003e(6.00, 7.16)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.225\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.367\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.410\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.085\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eKAa (D)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.24\u0026plusmn;0.70\u003c/p\u003e\n \u003cp\u003e(0, 3.20)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.22\u0026plusmn;0.74\u003c/p\u003e\n \u003cp\u003e(0.10, 3.20)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.37\u0026plusmn;0.64\u003c/p\u003e\n \u003cp\u003e(0.30, 3.30)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.129\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.699\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.119\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.063\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eKAp (D)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.34\u0026plusmn;0.15\u003c/p\u003e\n \u003cp\u003e(0, 0.70)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.34\u0026plusmn;0.14\u003c/p\u003e\n \u003cp\u003e(0.10, 0.70)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.41\u0026plusmn;0.14\u003c/p\u003e\n \u003cp\u003e(0.10, 0.80)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.876\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eQfront\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-0.35\u0026plusmn;0.10\u003c/p\u003e\n \u003cp\u003e(-0.65, -0.15)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-0.35\u0026plusmn;0.13\u003c/p\u003e\n \u003cp\u003e(-0.69, -0.11)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-0.34\u0026plusmn;0.13\u003c/p\u003e\n \u003cp\u003e(-0.62, -0.02)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.579\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.224\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.680\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.773\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eQback\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-0.34\u0026plusmn;0.14\u003c/p\u003e\n \u003cp\u003e(-0.72, -0.06)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-0.36\u0026plusmn;0.13\u003c/p\u003e\n \u003cp\u003e(-0.71, -0.07)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-0.47\u0026plusmn;0.16\u003c/p\u003e\n \u003cp\u003e(-0.94, -0.12)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.212\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eFE at TP (um)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e2.58\u0026plusmn;1.17\u003c/p\u003e\n \u003cp\u003e(0, 5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e2.29\u0026plusmn;1.31\u003c/p\u003e\n \u003cp\u003e(-1, 5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e2.24\u0026plusmn;1.47\u003c/p\u003e\n \u003cp\u003e(-1, 7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.034\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.048\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.062\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.543\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eBE at TP (um)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e5.25\u0026plusmn;3.15\u003c/p\u003e\n \u003cp\u003e(-2, 13)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e5.33\u0026plusmn;3.18\u003c/p\u003e\n \u003cp\u003e(-1, 14)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e7.37\u0026plusmn;4.03\u003c/p\u003e\n \u003cp\u003e(-4, 16)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.879\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ePPImin\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n 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3.14)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.76\u0026plusmn;0.96\u003c/p\u003e\n \u003cp\u003e(-1.35, 2.83)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.052\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eDp\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.48\u0026plusmn;0.96\u003c/p\u003e\n \u003cp\u003e(-0.62, 4.68)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.02\u0026plusmn;0.83\u003c/p\u003e\n \u003cp\u003e(-0.99, 2.62)\u003c/p\u003e\n \u003c/td\u003e\n 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\u003cp\u003e-1.82\u0026plusmn;0.31\u003c/p\u003e\n \u003cp\u003e(-2.66, -1.12)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eDa\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.27\u0026plusmn;0.45\u003c/p\u003e\n \u003cp\u003e(0.39, 2.59)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.66\u0026plusmn;0.54\u003c/p\u003e\n \u003cp\u003e(-0.58, 1.83)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-0.48\u0026plusmn;0.85\u003c/p\u003e\n \u003cp\u003e(-3.45, 1.32)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eBAD-D\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.63\u0026plusmn;0.50\u003c/p\u003e\n \u003cp\u003e(0.21, 2.58)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.11\u0026plusmn;0.56\u003c/p\u003e\n \u003cp\u003e(-0.41, 2.18)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.50\u0026plusmn;0.61\u003c/p\u003e\n \u003cp\u003e(-0.75, 2.10)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003csup\u003ea\u003c/sup\u003e\u003c/strong\u003eContinuous variables following normal distribution were analyzed by analysis of variance or student\u0026rsquo;s t test with Bonferroni correction; skewed data were analyzed by Kruskal-Wallis test and Mann-Whitney U test.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003csup\u003eb\u003c/sup\u003e\u003c/strong\u003eChi-square test.\u003c/p\u003e\n\u003cp\u003eTP = thinnest pachymetry; CD = corneal diameter; ARC = anterior radius of curvature for a 3-mm zone centered on the thinnest point; PRC = posterior radius of curvature for a 3-mm zone centered on the thinnest point; BFSa = the best-fit sphere for the anterior cornea; BFSp = the best-fit sphere for the posterior cornea; KAa = corneal astigmatism for the anterior cornea; KAp = corneal astigmatism for the posterior cornea; Qfront = Q value for the front surface; Qback = Q value for the back surface; FE at TP = front elevation at thinnest pachymetry ; BE at TP = back elevation at thinnest pachymetry; PPI = pachymetric progression indices (min = minimum, avg = average, max =maximum); ARTmax = Ambr\u0026oacute;sio\u0026rsquo;s maximum relational thickness index; IHD=index of height decentration; I-S = inferior-superior value; KISA% = keratoconus percentage index; Df = deviation of normality of the front elevation; Db = deviation of normality of the back elevation; Dp = deviation of normality of pachymetric progression; Dt = deviation of normality of corneal thinnest point; Da = deviation of normality of relational thickness; BAD-D = Belin/Ambr\u0026oacute;sio Enhanced Ectasia display (overall deviation of normality).\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2. Comparisons for the percentages of abnormality for individual Keratoconus Indices between different thickness groups.\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"586\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.576791808873722%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.378839590443686%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026lt;500 um (n=102)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"24.914675767918087%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e500-580 um (n=100)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.378839590443686%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026gt;580 um (n=102)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.750853242320819%\" rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eP\u003csup\u003ea\u003c/sup\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"19.731800766283524%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eParameters\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.685823754789272%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eNormal\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.559386973180077%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eAbnormal\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.218390804597702%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eNormal\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.559386973180077%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eAbnormal\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.685823754789272%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eNormal\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.559386973180077%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eAbnormal\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.60683760683761%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eFE\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.427350427350428%\" valign=\"top\"\u003e\n \u003cp\u003e102\u003c/p\u003e\n \u003cp\u003e(100%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003cp\u003e(0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.794871794871796%\" valign=\"top\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003cp\u003e(100%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003cp\u003e(0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.427350427350428%\" valign=\"top\"\u003e\n \u003cp\u003e99\u003c/p\u003e\n \u003cp\u003e(97.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003cp\u003e(2.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\" valign=\"top\"\u003e\n \u003cp\u003e0.109\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.60683760683761%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eBE\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.427350427350428%\" valign=\"top\"\u003e\n \u003cp\u003e100 (98.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e2\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e(2.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.794871794871796%\" valign=\"top\"\u003e\n \u003cp\u003e97\u003c/p\u003e\n \u003cp\u003e(97.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003cp\u003e(3.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.427350427350428%\" valign=\"top\"\u003e\n \u003cp\u003e85\u003c/p\u003e\n \u003cp\u003e(83.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003cp\u003e(16.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.60683760683761%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eIHD\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.427350427350428%\" valign=\"top\"\u003e\n \u003cp\u003e77\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e(75.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003cp\u003e(24.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.794871794871796%\" valign=\"top\"\u003e\n \u003cp\u003e81\u003c/p\u003e\n \u003cp\u003e(81.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e19\u003c/p\u003e\n \u003cp\u003e(19.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.427350427350428%\" valign=\"top\"\u003e\n \u003cp\u003e78\u003c/p\u003e\n \u003cp\u003e(76.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e24\u003c/p\u003e\n \u003cp\u003e(23.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\" valign=\"top\"\u003e\n \u003cp\u003e0.618\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.60683760683761%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ePPImin\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.427350427350428%\" valign=\"top\"\u003e\n \u003cp\u003e54\u003c/p\u003e\n \u003cp\u003e(52.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e48\u003c/p\u003e\n \u003cp\u003e(47.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.794871794871796%\" valign=\"top\"\u003e\n \u003cp\u003e60\u003c/p\u003e\n \u003cp\u003e(60.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e40\u003c/p\u003e\n \u003cp\u003e(40.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.427350427350428%\" valign=\"top\"\u003e\n \u003cp\u003e79\u003c/p\u003e\n \u003cp\u003e(77.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e23\u003c/p\u003e\n \u003cp\u003e(22.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\" valign=\"top\"\u003e\n \u003cp\u003e0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.60683760683761%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ePPImax\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.427350427350428%\" valign=\"top\"\u003e\n \u003cp\u003e60\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e(58.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e42\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e(41.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.794871794871796%\" valign=\"top\"\u003e\n \u003cp\u003e79\u003c/p\u003e\n \u003cp\u003e(79.0%）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e21\u003c/p\u003e\n \u003cp\u003e(21.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.427350427350428%\" valign=\"top\"\u003e\n \u003cp\u003e93\u003c/p\u003e\n \u003cp\u003e(91.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003cp\u003e(8.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.60683760683761%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ePPIavg\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.427350427350428%\" valign=\"top\"\u003e\n \u003cp\u003e62\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e(60.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e40\u003c/p\u003e\n \u003cp\u003e(39.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.794871794871796%\" valign=\"top\"\u003e\n \u003cp\u003e80\u003c/p\u003e\n \u003cp\u003e(80.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003cp\u003e(20.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.427350427350428%\" valign=\"top\"\u003e\n \u003cp\u003e96\u003c/p\u003e\n \u003cp\u003e(94.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003cp\u003e(5.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.60683760683761%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eARTmax\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.427350427350428%\" valign=\"top\"\u003e\n \u003cp\u003e78\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e(76.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e24\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e(23.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.794871794871796%\" valign=\"top\"\u003e\n \u003cp\u003e96\u003c/p\u003e\n \u003cp\u003e(96.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003cp\u003e(4.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.427350427350428%\" valign=\"top\"\u003e\n \u003cp\u003e102\u003c/p\u003e\n \u003cp\u003e(100%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003cp\u003e(0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.60683760683761%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eDf\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.427350427350428%\" valign=\"top\"\u003e\n \u003cp\u003e93\u003c/p\u003e\n \u003cp\u003e(91.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003cp\u003e(8.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.794871794871796%\" valign=\"top\"\u003e\n \u003cp\u003e95\u003c/p\u003e\n \u003cp\u003e(95.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003cp\u003e(5.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.427350427350428%\" valign=\"top\"\u003e\n \u003cp\u003e94\u003c/p\u003e\n \u003cp\u003e(92.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003cp\u003e(7.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\" valign=\"top\"\u003e\n \u003cp\u003e0.618\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.60683760683761%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eDb\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.427350427350428%\" valign=\"top\"\u003e\n \u003cp\u003e98 (96.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e4\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e(3.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.794871794871796%\" valign=\"top\"\u003e\n \u003cp\u003e88\u003c/p\u003e\n \u003cp\u003e(88.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003cp\u003e(12.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.427350427350428%\" valign=\"top\"\u003e\n \u003cp\u003e81\u003c/p\u003e\n \u003cp\u003e(79.4%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e21\u003c/p\u003e\n \u003cp\u003e(20.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\" valign=\"top\"\u003e\n \u003cp\u003e0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.60683760683761%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eDp\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.427350427350428%\" valign=\"top\"\u003e\n \u003cp\u003e61\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e(59.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e41\u003c/p\u003e\n \u003cp\u003e(40.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.794871794871796%\" valign=\"top\"\u003e\n \u003cp\u003e77\u003c/p\u003e\n \u003cp\u003e(77.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e23\u003c/p\u003e\n \u003cp\u003e(23.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.427350427350428%\" valign=\"top\"\u003e\n \u003cp\u003e95\u003c/p\u003e\n \u003cp\u003e(93.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003cp\u003e(6.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.60683760683761%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eDt\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.427350427350428%\" valign=\"top\"\u003e\n \u003cp\u003e64\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e(62.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e38\u003c/p\u003e\n \u003cp\u003e(37.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.794871794871796%\" valign=\"top\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003cp\u003e(100%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003cp\u003e(0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.427350427350428%\" valign=\"top\"\u003e\n \u003cp\u003e102\u003c/p\u003e\n \u003cp\u003e(100%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003cp\u003e(0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.60683760683761%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eDa\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.427350427350428%\" valign=\"top\"\u003e\n \u003cp\u003e77\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e(75.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e25\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e(24.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.794871794871796%\" valign=\"top\"\u003e\n \u003cp\u003e96\u003c/p\u003e\n \u003cp\u003e(96.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003cp\u003e(4.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.427350427350428%\" valign=\"top\"\u003e\n \u003cp\u003e102\u003c/p\u003e\n \u003cp\u003e(100%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003cp\u003e(0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.60683760683761%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eBAD-D\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.427350427350428%\" valign=\"top\"\u003e\n \u003cp\u003e46\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e(45.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e56\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e(54.9%）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.794871794871796%\" valign=\"top\"\u003e\n \u003cp\u003e79\u003c/p\u003e\n \u003cp\u003e(79.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e21\u003c/p\u003e\n \u003cp\u003e(21.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.427350427350428%\" valign=\"top\"\u003e\n \u003cp\u003e96\u003c/p\u003e\n \u003cp\u003e(94.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.991452991452991%\" valign=\"top\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003cp\u003e(5.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003csup\u003e\u0026nbsp;\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003e\u003csup\u003ea\u003c/sup\u003e Chi-square test\u003c/p\u003e\n\u003cp\u003e\u003csup\u003eb\u0026nbsp;\u003c/sup\u003eFisher\u0026rsquo;s exact test\u003c/p\u003e\n\u003cp\u003eFE = front elevation; BE = back elevation; IHD=index of height decentration; PPI = pachymetric progression indices (min = minimum, avg = average, max = maximum); ARTmax = Ambr\u0026oacute;sio\u0026rsquo;s maximum relational thickness index; Df = deviation of normality of the front elevation; Db = deviation of normality of the back elevation; Dp =deviation of normality of pachymetric progression; Dt = deviation of normality of corneal thinnest point; Da = deviation of normality of relational thickness; BAD-D = Belin/Ambr\u0026oacute;sio Enhanced Ectasia display (overall deviation of normality).\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3 Comparison of individual Pentacam Corneal Descritpors between BE groups in eyes with TP\u0026ge;580um.\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eParameter\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eBE\u0026lt;11.77\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eBE\u003c/strong\u003e\u0026ge;\u003cstrong\u003e11.77\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eP\u003c/strong\u003e\u003cstrong\u003e\u003csup\u003ea\u003c/sup\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eTP (um)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e610.79\u0026plusmn;13.38\u003c/p\u003e\n \u003cp\u003e(580, 650)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e606.71\u0026plusmn;16.45\u003c/p\u003e\n \u003cp\u003e(585, 649)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.169\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eAge (years)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e26.75\u0026plusmn;6.08\u003c/p\u003e\n \u003cp\u003e(18, 38)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e22.35\u0026plusmn;4.47\u003c/p\u003e\n \u003cp\u003e(18, 36)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.681\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eSex (male, %)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e65.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e47.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.118\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eSphere (D)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-4.29\u0026plusmn;2.43\u003c/p\u003e\n \u003cp\u003e(-12, +1.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-2.66\u0026plusmn;2.55\u003c/p\u003e\n \u003cp\u003e(-6.0, +5.0）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.049\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eCylinder (D)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-0.92\u0026plusmn;0.62\u003c/p\u003e\n \u003cp\u003e(-3.0, 0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-1.30\u0026plusmn;0.91\u003c/p\u003e\n \u003cp\u003e(-3.75, 0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.082\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eCD (mm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e11.66\u0026plusmn;0.28\u003c/p\u003e\n \u003cp\u003e(11.1, 12.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e11.53\u0026plusmn;0.26\u003c/p\u003e\n \u003cp\u003e(11.2, 12.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.052\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eARC (mm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e7.99\u0026plusmn;0.24\u003c/p\u003e\n \u003cp\u003e(7.47, 8.57)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e7.92\u0026plusmn;0.25\u003c/p\u003e\n \u003cp\u003e(7.36, 8.33)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.262\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ePRC (mm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e6.41\u0026plusmn;0.23\u003c/p\u003e\n \u003cp\u003e(5.85, 6.95)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e6.22\u0026plusmn;0.25\u003c/p\u003e\n \u003cp\u003e(5.75, 6.66)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.004\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eBFSa (mm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e8.08\u0026plusmn;0.25\u003c/p\u003e\n \u003cp\u003e(7.51, 8.65)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e8.04\u0026plusmn;0.27\u003c/p\u003e\n \u003cp\u003e(7.55, 8.36)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.475\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eBFSp (mm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e6.51\u0026plusmn;0.25\u003c/p\u003e\n \u003cp\u003e(6.05, 7.16)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e6.47\u0026plusmn;0.26\u003c/p\u003e\n \u003cp\u003e(6.00, 6.98)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.815\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eKAa (diopter)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.29\u0026plusmn;0.58\u003c/p\u003e\n \u003cp\u003e(0.30, 2.90)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.75\u0026plusmn;0.79\u003c/p\u003e\n \u003cp\u003e(0.60, 3.30)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.057\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eKAp (diopter)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.39\u0026plusmn;0.13\u003c/p\u003e\n \u003cp\u003e(0.10, 0.80)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.48\u0026plusmn;0.13\u003c/p\u003e\n \u003cp\u003e(0.20, 0.70)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.297\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eQfront\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-0.32\u0026plusmn;0.12\u003c/p\u003e\n \u003cp\u003e(-0.58, -0.02)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-0.42\u0026plusmn;0.13\u003c/p\u003e\n \u003cp\u003e(-0.62, -0.15)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.004\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eQback\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-0.44\u0026plusmn;0.15\u003c/p\u003e\n \u003cp\u003e(-0.94, -0.12)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-0.58\u0026plusmn;0.14\u003c/p\u003e\n \u003cp\u003e(-0.89, -0.37)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eFE at TP (um)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e2.08\u0026plusmn;1.24\u003c/p\u003e\n \u003cp\u003e(0, 5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e3.00\u0026plusmn;2.21\u003c/p\u003e\n \u003cp\u003e(-1, 7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.134\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eBE at TP (um)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e6.20\u0026plusmn;3.30\u003c/p\u003e\n \u003cp\u003e(-4, 11)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e13.24\u0026plusmn;1.25\u003c/p\u003e\n \u003cp\u003e(12, 16)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ePPImin\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.69\u0026plusmn;0.11\u003c/p\u003e\n \u003cp\u003e(0.49, 1.02)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.73\u0026plusmn;0.13\u003c/p\u003e\n \u003cp\u003e(0.56, 0.95)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.343\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ePPImax\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.12\u0026plusmn;0.17\u003c/p\u003e\n \u003cp\u003e(0.71, 1.55)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.35\u0026plusmn;0.20\u003c/p\u003e\n \u003cp\u003e(1.03, 1.77)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ePPIavg\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.93\u0026plusmn;0.13\u003c/p\u003e\n \u003cp\u003e(0.64, 1.21)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.04\u0026plusmn;0.12\u003c/p\u003e\n \u003cp\u003e(0.89, 1.25)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eARTmax\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e556.65\u0026plusmn;89.08\u003c/p\u003e\n \u003cp\u003e(405, 865)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e457.94\u0026plusmn;68.19\u003c/p\u003e\n \u003cp\u003e(343, 589)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eIHD\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.01\u0026plusmn;0.01\u003c/p\u003e\n \u003cp\u003e(0, 0.07)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.01\u0026plusmn;0.01\u003c/p\u003e\n \u003cp\u003e(0.002, 0.035)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.248\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eI-S (diopter)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.03\u0026plusmn;0.58\u003c/p\u003e\n \u003cp\u003e(-1.47, 1.26)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.42\u0026plusmn;0.75\u003c/p\u003e\n \u003cp\u003e(-0.59, 1.69)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.190\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eKISA%\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e6.91\u0026plusmn;10.12\u003c/p\u003e\n \u003cp\u003e(0.33, 53.33)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e5.67\u0026plusmn;3.63\u003c/p\u003e\n \u003cp\u003e(0.63, 9.73)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.625\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eDf\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.12\u0026plusmn;0.91\u003c/p\u003e\n \u003cp\u003e(-1.71, 2.29)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.66\u0026plusmn;1.25\u003c/p\u003e\n \u003cp\u003e(-1.57, 2.98)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.145\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eDb\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.63\u0026plusmn;0.95\u003c/p\u003e\n \u003cp\u003e(-1.35, 2.83)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.40\u0026plusmn;0.71\u003c/p\u003e\n \u003cp\u003e(0.13, 2.80)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.002\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eDp\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.16\u0026plusmn;0.85\u003c/p\u003e\n \u003cp\u003e(-1.78, 2.03)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.91\u0026plusmn;0.80\u003c/p\u003e\n \u003cp\u003e(-0.12, 2.36)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eDt\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-1.84\u0026plusmn;0.30\u003c/p\u003e\n \u003cp\u003e(-2.66, -1.12)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-1.75\u0026plusmn;0.37\u003c/p\u003e\n \u003cp\u003e(-2.66, -1.24)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.167\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eDa\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-0.63\u0026plusmn;0.81\u003c/p\u003e\n \u003cp\u003e(-3.45, 0.76)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.27\u0026plusmn;0.62\u003c/p\u003e\n \u003cp\u003e(-0.92, 1.32)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eBAD-D\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.35\u0026plusmn;0.52\u003c/p\u003e\n \u003cp\u003e(-0.75, 1,60)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.26\u0026plusmn;0.48\u003c/p\u003e\n \u003cp\u003e(0.49, 2.10)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003csup\u003ea\u003c/sup\u003e\u003c/strong\u003eContinuous variables following normal distribution were analyzed by student\u0026rsquo;s t test; skewed data were analyzed by\u0026nbsp;Mann-Whitney U test.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003csup\u003eb\u003c/sup\u003e\u003c/strong\u003eChi-square test.\u003c/p\u003e\n\u003cp\u003eTP = thinnest pachymetry; CD = corneal diameter; D = diopters; ARC = anterior radius of curvature for a 3-mm zone centered on the thinnest point; PRC = posterior radius of curvature for a 3-mm zone centered on the thinnest point; BFSa = the best-fit sphere for the anterior cornea; BFSp = the best-fit sphere for the posterior cornea; KAa = corneal astigmatism for the anterior cornea; KAp = corneal astigmatism for the posterior cornea; Qfront = Q value for the front surface; Qback = Q value for the back surface; FE at TP = front elevation at thinnest pachymetry; BE at TP = back elevation at thinnest pachymetry; PPI = pachymetric progression indices (min = minimum, avg = average, max =maximum); ARTmax = Ambr\u0026oacute;sio\u0026rsquo;s maximum relational thickness index; IHD=index of height decentration; I-S = inferior-superior value; KISA% = keratoconus percentage index; Df = deviation of normality of the front elevation; Db = deviation of normality of the back elevation; Dp = deviation of normality of pachymetric progression; Dt = deviation of normality of corneal thinnest point; Da = deviation of normality of relational thickness; BAD-D = Belin/Ambr\u0026oacute;sio Enhanced Ectasia display (overall deviation of normality)\u003c/p\u003e\n"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-ophthalmology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"boph","sideBox":"Learn more about [BMC Ophthalmology](http://bmcophthalmol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/boph","title":"BMC Ophthalmology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"corneal thickness, forme fruste keratoconus, tomography, asphericity","lastPublishedDoi":"10.21203/rs.3.rs-3969726/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3969726/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003ePurpose\u003c/strong\u003e: To investigate the tomographic characteristics of corneas with excessive thickness and to explore their potential impact on the assessment of candidates for refractive surgery.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods:\u003c/strong\u003e One hundred and two eyes from 102 patients with the thinnest pachymetry (TP) \u0026lt; 500 μm, 100 eyes from 100 patients with TP ranging from 500 to 580 μm, and 102 eyes from 102 subjects with TP ≥ 580 μm were included. Pentacam ectasia indices were compared among these different groups.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e: When compared to eyes with TP between 500 and 580 μm, significantly higher values in anterior radius of curvature (ARC), anterior corneal astigmatism (KAp), back elevation at the thinnest pachymetry (BE), deviation ofnormality of the back elevation (Db), and a more negative Q value for the back surface (Qback) were observed in eyes with TP ≥ 580 μm (Mann-Whitney U test: P\u0026lt;0.001). No significant differences were observed in the indices for the anterior cornea (Mann-Whitney U test: index of height decentration, P=0.348; inferior-superior value, P=0.334; keratoconus percentage index, P=0.077; deviation of normality of the front elevation, P=0.891). The proportion of abnormalities was highest in eyes with TP ≥ 580 μm for BE (16.7%, Chi-square test: P\u0026lt;0.001) and Db (20.6%, Chi-square test: P=0.001).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions\u003c/strong\u003e: The tomography of thick corneas reveals greater BE and Db,as well as a more negative Qback while no significant disparities emerged in the anterior corneal indices.\u003c/p\u003e","manuscriptTitle":"Tomographic characteristics of thick corneas","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-02-21 04:02:59","doi":"10.21203/rs.3.rs-3969726/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-11-07T06:36:43+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-10-30T19:19:54+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"192531394798479427944413201044343454269","date":"2024-10-29T15:08:17+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-07-13T17:02:37+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-06-26T17:20:12+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"60598456037764752703028673836560910842","date":"2024-06-19T19:33:47+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"69400123050527247911206201699017804292","date":"2024-06-14T06:05:52+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-06-10T04:06:46+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"105900092068681523632611754598588273414","date":"2024-06-05T02:47:37+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-05-23T06:00:14+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2024-02-19T11:36:27+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-02-19T11:17:25+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-02-19T11:17:25+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Ophthalmology","date":"2024-02-19T10:20:26+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-ophthalmology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"boph","sideBox":"Learn more about [BMC Ophthalmology](http://bmcophthalmol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/boph","title":"BMC Ophthalmology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"d5baff25-c4fe-4582-9fd3-fffe2b6620d5","owner":[],"postedDate":"February 21st, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-02-17T16:07:38+00:00","versionOfRecord":{"articleIdentity":"rs-3969726","link":"https://doi.org/10.1186/s12886-025-03905-3","journal":{"identity":"bmc-ophthalmology","isVorOnly":false,"title":"BMC Ophthalmology"},"publishedOn":"2025-02-10 15:58:09","publishedOnDateReadable":"February 10th, 2025"},"versionCreatedAt":"2024-02-21 04:02:59","video":"","vorDoi":"10.1186/s12886-025-03905-3","vorDoiUrl":"https://doi.org/10.1186/s12886-025-03905-3","workflowStages":[]},"version":"v1","identity":"rs-3969726","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3969726","identity":"rs-3969726","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}