Biomechanical Responses of Different Cap Thicknesses of Corneas After Small Incision Lenticule Extraction: Finite Element Analysis.

Purpose: This study analyzed the biomechanical responses of different corneal cap thicknesses after small incision lenticule extraction (SMILE). Methods: Individual finite element models of myopic eyes were constructed based on the clinical data. Then, four types of corneal cap thicknesses after SMILE were included for each model. The biomechanical effects of material parameters and intraocular pressure on corneas with different cap thicknesses were analyzed. Results: When the cap thickness increased, the vertex displacements of the anterior and posterior corneal surfaces decreased slightly. The corneal stress distributions demonstrated little change. Regarding wave-front aberrations caused by the displacements of the anterior surface, the absolute defocus value decreased slightly, but the magnitude of primary spherical aberration increased slightly. The horizontal coma increased, and the levels of other low-order and high-order aberrations were small and demonstrated little change. The corneal vertex displacement and wave-front aberration were significantly affected by elastic modulus and intraocular pressure, whereas the corneal stress distribution was greatly affected by intraocular pressure. There were obvious individual differences in the biomechanical responses of human eyes. Conclusions: The biomechanical difference of different corneal cap thicknesses after SMILE was small. The effect of corneal cap thickness was significantly less than that resulting from material parameters and intraocular pressure. Translational Relevance: Individual models were constructed based on the clinical data. The elastic modulus was controlled by programming to simulate its heterogeneous distribution in the actual human eye. The simulation was improved to bridge the gap between basic research and clinical care.

The effects of programmed optical zones on achieved corneal refractive power with myopic astigmatism after small incision lenticule extraction (SMILE): a vector analysis.

PURPOSE: To evaluate the effects of different programmed optical zones (POZs) on achieved corneal refractive power (CRP) with myopic astigmatism after small incision lenticule extraction (SMILE). METHODS: In total, 113 patients (113 eyes) were included in this retrospective study. The eyes were divided into two groups according to POZ: group A (6.5, 6.6, and 6.7 mm, n = 59) and group B (6.8, 6.9, and 7.0 mm, n = 54). Fourier vector analysis was applied to evaluate the error values between the attempted and achieved corneal refractive power (CRP). Alpins vector analysis was used to calculate surgically induced astigmatism (SIA), difference vector (DV), magnitude of error (ME), and astigmatism correction index (ACI). Multivariate regression analysis was performed to assess potential factors associated with the error values. RESULTS: The error values in the group with large POZ were closer to zero, and significantly associated with the POZ at 2 and 4 mm of the cornea (ß = - 0.50, 95% confidence interval [CI] [- 0.80, - 0.20]; ß = - 0.37, 95% CI [- 0.63, - 0.10], P < 0.05, respectively). For the correction of astigmatism, the values of SIA, ME, and ACI were lower in group B than in group A (P < 0.05). The fitting curves between TIA and SIA were y = 0.83x + 0.19 (R2 = 0.84) and y = 1.05x + 0.04 (R2 = 0.90), respectively. CONCLUSIONS: Smaller POZs resulted in higher error values between the achieved- and attempted-CRP in the SMILE procedure, which should be considered when performing surgery.

Change in the corneal material mechanical property for small incision lenticule extraction surgery.

Purpose: To assess the distribution characteristics and related factors of stress-strain index (SSI) values and discuss changes in biomechanical parameters, including SSI, after small incision lenticule extraction (SMILE) surgery. Methods: This study included 253 patients who underwent SMILE (253 eyes). SSI and other biomechanical parameters were measured using corneal visualization Scheimpflug technology before and 3 months after surgery. The data collected included SSI, central corneal thickness (CCT), and eight other dynamic corneal response parameters. The Kolmogorov-Smirnov test, Pearson and partial correlation analyses, and paired-sample t-tests were used for statistical analyses. Results: Both pre-op SSI and ΔSSI follow a normal distribution, while post-op SSI does not follow a normal distribution. The decline in SSI after SMILE surgery was not statistically significant, and the data dispersion of SSI after SMILE surgery was close to that before surgery (p > 0.05). No statistical correlation was noted between SSI values and age and pre-op CCT (all p > 0.05). However, both pre- and post-op SSI values decreased with increasing degree of myopia (all p < 0.05), and weakly correlated with preoperative intraocular pressure and biomechanically corrected intraocular pressure (all p < 0.05). Other biomechanical parameters changed significantly after surgery (all p < 0.001). After SMILE, the magnitude of the deformation at the highest concave, deformation ratio, and integral radius increased significantly (all p < 0.001), while the Ambrosio relational thickness horizontal, stiffness parameter A1, and Corvis biomechanical index decreased significantly (p < 0.001). Conclusion: SSI, which reflects essential corneal material attributes, differs from other corneal biomechanical parameters and remains stable before and after SMILE surgery, and can be used as an indicator to evaluate changes in corneal material properties after SMILE surgery.

Small Incision Lenticule Extraction (SMILE) Versus Laser Assisted Stromal In Situ Keratomileusis (LASIK) for Astigmatism Corrections: A Systematic Review and Meta-analysis.

PURPOSE: To compare small incision lenticule extraction (SMILE) and laser assisted stromal in situ keratomileusis (LASIK) for astigmatism correction. DESIGN: Systematic review and meta-analysis METHODS: We reviewed published studies comparing outcomes after LASIK and SMILE for astigmatism correction by querying PubMed, EMBASE, Cochrane, and Web of Science, with a cut-off date of September 3, 2022. We also compared the changes in visual acuity, refraction, and high-order aberrations between the surgeries. Astigmatism correction outcomes in the low-to-moderate group (less than or equal to -2.00 D) and high group (greater than -2.00 D) were evaluated using vector analysis. The Cochrane risk of bias tool in RevMan software was used for randomized studies (RCT), and Risk Of Bias In Nonrandomized Studies - of Interventions (ROBINS-I) was used for the nonrandomized studies (NRSs). RESULTS: There were 17 studies (5 randomized studies and 12 cohort studies), including 1,985 eyes. A statistically significant difference was found in the correction index (mean difference [MD] = -0.02, 95% confidence interval [CI] = -0.04 to -0.01, P =0.01), although there was no significant difference in the index of success (MD = 0.01, 95% CI = -0.03 to 0.05, P =0.51), different vector (MD = 0.07, 95% CI = 0.00 to 0.13, P =0.04), and angle of error (MD = 0.56, 95% CI = -0.34 to 1.45, P =0.22) between SMILE and LASIK. However, for low-to-moderate astigmatism correction, SMILE exhibited a smaller correction index (MD = -0.08, 95% CI= -0.13 to -0.02, P =0.008) and a larger difference vector (MD = 0.18, 95% CI = 0.09 to 0.27, P <0.0001) than LASIK. There was no significant difference between the different procedures in visual acuity and refraction (spherical equivalent: MD = -0.04, 95% CI = -0.08 to 0.01, P =0.15) or high-order aberration (MD = -0.01, 95% CI = -0.07 to 0.04, P =0.67), except spherical aberration (MD = -0.12, 95% CI = -0.23 to -0.01, P =0.04). The risk of bias was moderate in most studies because of poor reporting of several bias domains for RCTs, and because of confounding and selective outcome reporting for NRSs. CONCLUSIONS: When used to treat severe astigmatism, both SMILE and LASIK provide effective and predictable results and generally have equivalent outcomes. However, evidence reveals a tendency toward undercorrection in the SMILE groups for astigmatism correction. In addition, LASIK has a greater probability of causing postoperative spherical aberration.

Association between Cataract Surgery and Age-Related Macular Degeneration: A Systematic Review and Meta-Analysis.

Purpose: We performed a systematic review and meta-analysis to evaluate the association between cataract surgery and the development and progression of AMD. Methods: This meta-analysis was registered at PROSPERO (CRD42017077962). We conducted a systematic literature search in August 2020 in Embase and PubMed and included cohort studies, case-control studies, or randomized controlled trials (RCTs) if they examined the association between cataract surgery and AMD. Odds ratio (OR) was used as a measure of the association with a random effect model. The analysis was further stratified by factors that could affect the outcomes. Results: 15 studies were included in this study. In the overall analysis, cataract surgery was significantly associated with the incidence of late AMD (OR, 1.80; 95% CI, 1.26-2.56; P = 0.001), particularly geographic atrophy (OR, 3.20; 95% CI, 1.90-5.39; P ≤ 0.001). No significant associations were observed between cataract surgery and the incidence of early AMD. Subgroup analysis showed that the OR for incidence of early and late AMD was significantly higher for cataract surgery performed more than 5 years compared with less than 5 years. We also found an increased risk of progression of AMD after cataract surgery performed more than 5 years (OR, 1.97; 95% CI, 1.29-3.01; P = 0.002). Conclusions: Our results suggest that cataract surgery may be associated with an increased risk of late AMD development and AMD progression. In addition, increasing the follow-up time since cataract surgery may further increase the risk for the development and progression of AMD. In the future, prospective multicenter studies with well-designed RCTs are required to confirm our findings.

Comparative effectiveness of different treatment modalities for active, moderate-to-severe Graves' orbitopathy: a systematic review and network meta-analysis.

To compare the effects of different treatment modalities on active, moderate-to-severe Graves' orbitopathy (GO). We searched PubMed and Embase for randomized controlled trials published up to 30 Nov 2020, of different modalities for the treatment of active, moderate-to-severe GO. We performed Bayesian network meta-analyses. This study is registered with PROSPERO (CRD42020166287). Fifteen RCTs were identified. Network meta-analysis showed that in comparison with placebo, teprotumumab, mycophenolate plus intravenous glucocorticoids (IVGCs), mycophenolate, rituximab, azathioprine, IVGCs, orbital radiotherapy, oral glucocorticoids (OGCs) were effective treatments (ordered from most effective to least effective). Teprotumumab was more efficacious in reducing proptosis than IVGCs. No significant difference in changes in diplopia grade was recorded between teprotumumab, rituximab, orbital radiotherapy and IVGCs. Low (4.5-5 g), middle (6 g) and high (7-8 g) cumulative doses of IVGCs were shown to be more effective than OGC in improving the overall response rate, but the very low-group (<3 g) seemed to have a lower risk of adverse events. We found that teprotumumab offered the highest level of efficacy in terms of the overall response rate and was more efficacious in reducing proptosis than IVGCs. With regard to different dosages of IVGCs, the cumulative dose of 4.5-5 g of IVGCs seems to be the most appropriate schedule in terms of efficacy and safety outcomes. Due to the limited number of patients treated with teprotumumab and the lack of comparison with other effective therapeutics, teprotumumab might not become the standard first-line therapy for active, moderate-to-severe GO.

Comparative study of small-incision lenticule extraction with and without prophylactic corneal crosslinking: 1-year outcomes.

PURPOSE: To compare myopia and astigmatic correction after small-incision lenticule extraction (SMILE) with or without prophylactic crosslinking (SMILE Xtra). SETTING: Shenyang Aier Eye Hospital, Central South University, China. DESIGN: Retrospective study. METHODS: Patients with comparable manifest sphere and cylinder undergoing SMILE Xtra or SMILE were enrolled. The crosslinking (CXL) energy was 2.7 J/cm2. Only right eyes were selected. Visual and refractive changes were evaluated for 1 year. Astigmatic correction was analyzed using Alpins method. RESULTS: Thirty-six eyes undergoing SMILE Xtra and 40 eyes undergoing SMILE were enrolled. The uncorrected distance visual acuity at 1-day visit was lower after SMILE Xtra than that after SMILE (P = .01). At 12 months, the mean manifest refraction spherical equivalent (MRSE) and manifest cylinder were 0.08 ± 0.32 diopters (D) and -0.29 ± 0.23 D in SMILE Xtra group, whereas -0.25 ± 0.29 D and -0.22 ± 0.19 D in SMILE group (P < .01 and P = .135), respectively. Thirty-four eyes (94%) and 32 eyes (89%) in SMILE Xtra group and 36 eyes (91%) and 39 eyes (98%) in SMILE group exhibited target MRSE and manifest cylinder within ±0.50 D (P = .771 and P = .294), respectively. Compared with SMILE group, spherical correction index (SCI), correction index (CI), and difference vector were higher in SMILE Xtra group since 1-week follow-up (all P < .05). SCI and CI were slightly more than 1.0 after SMILE Xtra even at postoperative 12-month follow-up. CONCLUSIONS: With CXL protocol of 30 mW/cm2 for 90 seconds, SMILE Xtra exhibited comparable astigmatic correction with SMILE up to 1-year follow-up, although slight spherical equivalent and astigmatic overcorrection were evident after SMILE Xtra.

Effect of Wavefront Aberrations on Night Vision Problems and Mesopic Contrast Threshold After SMILE.

PURPOSE: To investigate the effect of wavefront aberrations on night vision problems and mesopic contrast threshold after small incision lenticule extraction (SMILE). METHODS: Forty-two participants (84 eyes) who underwent SMILE were included in this prospective observational study. Visual outcomes including uncorrected distance visual acuity (UDVA), subjective manifest refraction, mesopic contrast threshold (Binoptometer 4P; Oculus Optikgeräte GmbH), and higher order aberrations (HOAs) were analyzed before and 3 months after surgery. The patient's night vision satisfaction was assessed using a questionnaire. RESULTS: The mean spherical equivalent was -5.30 ± 1.38 diopters (D) preoperatively and -0.06 ± 0.15 D postoperatively. UDVA was better than 20/20 in 98.81% of the patients and better than 20/25 in all patients. Scores of night vision satisfaction and glare changed significantly in the postoperative period (F = 8.463, P = .001; F = 69.518, P < .001, respectively). Preoperative spherical diopters (lower order aberrations) were positively correlated with night vision satisfaction (r = -0.329, P = .041) and glare score (r =-0.332, P = .039). Age (odds ratio [OR] = 1.272, 95% CI = 1.019 to 1.589) and preoperative spherical diopter (OR = 0.437, 95% CI = 0.199 to 0.975) were correlated with night vision satisfaction scores by analysis of binary regression. The root mean square value of total HOAs increased 3 months after surgery (t = -6.873, P < .001) with an increase in horizontal coma (Z31) and spherical aberration (Z40) (P < .001). No correlation was observed between glare score and HOAs; however, patients with higher preoperative myopia demonstrated continuously decreasing contrast under mesopic conditions and higher postoperative horizontal coma. CONCLUSIONS: Myopic patients with higher preoperative spherical errors experienced more glare at night after SMILE surgery. Postoperative horizontal coma was associated with worse mesopic contrast thresholds. [J Refract Surg. 2021;37(7):446-452.].

Comparison of Wavefront-Guided Femtosecond LASIK and Optimized SMILE for Correction of Moderate-to-High Astigmatism.

PURPOSE: To compare refractive outcomes, higher order aberrations (HOAs), and the changes in contrast sensitivity after wavefront-guided femtosecond laser-assisted in situ keratomileusis (WFG LASIK) and optimized small incision lenticule extraction (SMILE) for moderate-to-high astigmatism correction. METHODS: This prospective, randomized study included 87 eyes: 40 eyes in the WFG LASIK group and 47 eyes in the SMILE group. Manual cyclotorsion compensation by marking the horizontal axis before SMILE surgery was used for optimized SMILE. Refractive diopter, aberrations, and contrast sensitivity were assessed 3 months postoperatively. The Alpins vector analysis method was used to analyze the astigmatic changes after surgery. RESULTS: There were no significant differences in the corrected distance visual acuity and refraction between the two groups after surgery. The fitted curve of surgically induced astigmatism versus target induced astigmatism was described as y = 0.9905 x + 0.0009 in the WFG LASIK group and y = 0.9672 x + 0.0026 in the SMILE group. The percentage of corneal astigmatism axis change within 5 degrees was statistically significant (chi-square test: 10.632, P = .001). HOAs increased in both the WFG LASIK and SMILE groups after surgery (t = -3.655, P = .001, t = -3.784, P = .001, respectively). However, comparison of the changes of HOAs between both groups was not significant (t = -0.565, P = .575). The improvement in contrast sensitivity in the WFG LASIK group was significantly higher than that in the SMILE group. CONCLUSIONS: WFG LASIK and optimized SMILE can achieve similar outcomes for astigmatism correction. Optimized SMILE with marking could achieve good astigmatism correction, even without an eye tracking system. [J Refract Surg. 2021;37(3):166-173.].

Distribution and analysis of intraocular pressure and its possible association with glaucoma in children.

PURPOSE: To analyze intraocular pressure (IOP) and glaucoma-associated factors in children. METHODS: A total of 4438 children aged 7-16 years (2321 boys and 2117 girls) were included in this study. Various ophthalmologic [IOP, central corneal thickness (CCT), etc.] and demographic (body mass index, etc.) parameters were evaluated. RESULTS: IOP increased between the ages of 7 and 9 years, peaking at 9 years. IOP increased after reaching a trough at 11 years and subsequently stabilized after 14 years. Girls exhibited thinner CCT (534.28 ± 30.84 µm vs. 537.04 ± 31.33 µm, P = 0.003), thicker lens thickness (3.56 ± 0.21 mm vs. 3.54 ± 0.20 mm, P = 0.001), shorter axial length (22.91 ± 0.93 mm vs. 23.32 ± 0.89 mm, P < 0.001), shallower anterior chamber depth (2.92 ± 0.27 mm vs. 3.00 ± 0.26 mm, P < 0.001), higher refraction (- 0.57 ± 1.48 D vs. 0.16 ± 1.35 D, P < 0.001), and higher mean corneal curvature (43.77 ± 1.39 vs. 43.03 ± 1.35, P < 0.001). Multivariable analysis assessed the following IOP-associated factors: thicker CCT [standardized correlation coefficient (SRC) = 0.201, P < 0.001), deeper anterior chamber depth (SRC = 0.059, P = 0.009), shorter axial length (SRC = - 0.086, P = 0.036), lower mean corneal curvature (SRC = - 0.123, P < 0.001), higher refraction (SRC = - 0.090, P < 0.001). CONCLUSION: IOP fluctuated in children, and a trend toward a higher mean IOP between the ages of 9 and 11 years, which stabilized after 14 years, was observed. IOP was associated with CCT, anterior chamber depth, axial length, lens thickness, mean corneal curvature, spherical equivalent, and systolic blood pressure.

Quantitative Evaluation of Aerosol Generation from Non-contact Tonometry and its Correlation with Tear Film Characteristics.

INTRODUCTION: Ophthalmologists are inevitably exposed to tears and ocular discharge during ophthalmologic examinations and are at high risk for SARS-CoV-2 infection. To understand the role of aerosols in disease transmission, we adopted a prospective cross-sectional study design and investigated the count and size distribution of aerosols generated by a non-contact tonometer and its correlation with individual tear film characteristics. METHODS: This study constituted two parts. The study population included outpatients who underwent an intraocular pressure examination in an intraocular pressure examination room (Part I) and 20 participants who underwent an intraocular pressure examination in a laboratory (Part II). The following main outcomes were measured: aerosol counts at 0, 50, 100, 150, and 200 cm from the non-contact tonometer (Part I); aerosol counts after each participant underwent non-contact tonometry, and lipid layer thickness score and tear film break-up time (Part II). RESULTS: The aerosol count decreased with increasing distance from the tonometer. The aerosol count at 0 cm had the highest value compared to that at other distances. For aerosols of diameters 0.25-0.5 µm and 0.5-1.0 µm, the count decreased at 50 cm and remained stable at further distances. For aerosols of diameters 1.0-2.5 µm and ≥ 2.5 µm, the count dropped progressively at all five distances. The aerosol count from each tonometer correlated positively with the lipid layer thickness score (r = 0.490, P = 0.028), whereas the aerosol count correlated negatively with the tear film break-up time (r = - 0.675, P = 0.001). CONCLUSIONS: Aerosols tended to coagulate during diffusion. A 50-cm distance from the tonometer could confer safety from aerosols with < 1.0-µm diameter. Aerosols generated during non-contact tonometry could contain a lipid layer component. Moreover, tear film stability could affect aerosol generation. Protective eyewear is recommended for reducing infection risk from aerosols. Individual tear film characteristics should be considered during non-contact tonometry.

Quantitative Analysis of Human Corneal Lenticule Surface Microstructure Irregularity with 3D Optical Profiler Using White Light Interferometry.

PURPOSE: To quantitatively evaluate the cutting quality of small incision lenticule extraction (SMILE) by measuring human corneal lenticule surface roughness in different areas with white light interferometer. METHOD: A white light interferometer was used to quantitatively measure the corneal lenticule surface roughness in different areas. Sixty-three myopic patients (102 eyes) who underwent SMILE surgery were recruited. The surface roughness of the central, pericentral, and peripheral parts of the corneal lenticule surface was measured in both the anterior and posterior planes. Differences in corneal lenticule surface roughness were analyzed between different myopic groups. RESULTS: The surface roughness of the anterior plane of the corneal lenticule was lower than the posterior plane in various areas (central, pericentral, and peripheral parts) (P < .01). Surface roughness gradually increased from the center to the periphery, in both the anterior and posterior planes (P < .01). There were no significant differences in the surface roughness of the central part in both the anterior and posterior planes between the low and high myopic groups. The surface roughness of the high myopic group was higher than that of the low myopic group in the peripheral part (P < .01). There were no significant differences among the three cylinder-specific groups. There was no significant correlation between two paired eyes. A positive correlation between posterior central surface roughness and the percentage tissue altered score (PTA) was found (r = 0.248, P = .012). CONCLUSIONS: The cutting surface of the corneal lenticule performed by femtosecond laser was evaluated with a white light interferometer and displayed inhomogeneity. Deeper cutting with higher myopia and some intraoperative complications, such as suction loss, may result in larger irregularities.

Biomechanical effect of ultraviolet-A-riboflavin cross-linking on simulated human corneal stroma model and its correlation with changes in corneal stromal microstructure.

In this study, we established an experimental human corneal stroma model of simulated cornea tissue composed of thin anterior cornea strips layers obtained from small incision lenticular extraction (SMILE) surgery. We investigated the biomechanical effect of ultraviolet-A- riboflavin cross-linking at different depths of corneal stroma model and correlated it with stromal microstructural changes examined by transmission electron microscopy (TEM). Corneal strips were harvested from fresh human corneal lenticules obtained after SMILE surgery. Experimental models (n = 34) were established by superimposing the corneal lenticule strips until their thickness reached close to 500 µm. Corneal cross-linking (CXL) was performed subsequently using standard or accelerated protocol. Elasticity and viscosity were quantified using stress-strain extensometer. TEM was used to visualize the collagen fiber diameter and interfibrillar spacing. The relative change in Young's modulus (rel. ΔE) decreased nonlinearly with increasing stromal depth both in the standard and accelerated groups. Compared to the sham controls, the rel. ΔE in standard and accelerated CXL groups increased significantly in the anterior 400 µm and 275 µm depth, respectively. Also, the relative change in stress (rel. ΔS) was significantly lower after standard and accelerated CXL compared to sham controls. Depth analysis showed similar results for the elastic effect. TEM images showed a small, non-significant increase in fibril diameter. The interfibrillar spacing decreased significantly after standard and accelerated CXL in the anterior-mid stromal region. We noted that the increase of corneal stiffness correlated with decrease in interfibrillar spacing after CXL. The stiffening effect was depth dependent. The effect of accelerated CXL was less in the deep corneal stromal regions compared to standard CXL.

Changes and quantitative characterization of hyper-viscoelastic biomechanical properties for young corneal stroma after standard corneal cross-linking treatment with different ultraviolet-A energies.

Corneal collagen cross-linking (CXL) treatment can restore vision in patients suffering from keratoconus and corneal injury, by improving the mechanical properties of the cornea. The correlation between ultraviolet-A (UVA) irradiant energies of standard CXL (SCXL) and corneal visco-hyperelastic mechanical behavior remains unknown. In this study, SCXL with four different UVA irradiant energy doses (0-5.4 J/cm2) were administered as part of quantitative treatments of corneal stromal lenticules extracted from young myopic patients via small incision lenticule extraction (SMILE) corneal refractive surgery. Double-strip samples with symmetric geometries were cut simultaneously for SCXL treatment and non-treated control. First, 40 pairs of strips were loaded to failure to assess the mechanical parameters of the material. Then, another 40 pairs were tested using a special uniaxial tensile test including quasi-static loading-unloading, instantaneous loading, and stress relaxation, to determine the visco-hyperelastic mechanical behavior. Upon combining the collagen fibril crimping constitutive model with the quasi-linear viscoelastic model, it was observed that with increasing UVA energy dose, the corneal strength and hyperelastic stiffness were significantly enhanced, while the maximum stretch and viscosity of the cornea were significantly reduced. Considering the quantitative analysis of SCXL and the rehabilitation prediction of keratoconus treatment, the results clarify the biomechanical behavior of human corneal stroma in SCXL clinical surgery. STATEMENT OF SIGNIFICANCE: This study quantitatively analyzes the improvement in the biomechanical properties of young central corneal stroma, due to SCXL treatment with different energies. Furthermore, the correlation between the hyper-viscoelastic mechanical parameters and UVA irradiant energy doses of SCXL are clarified. The contribution of this study fills the knowledge gap of the CXL on corneal biomechanics. It can not only clarify this mechanism better but also assist with guiding SCXL surgery for individualized patient corneas.