Corneal biomechanics after small incision lenticule extraction and femtosecond laser in situ keratomileusis: A systematic review and meta-analysis

Small incision lenticule extraction (SMILE) and femtosecond laser in situ keratomileusis (FS-LASIK) have been extensively studied as the main surgical methods for corneal refractive surgery. However, there is no consensus on whether SMILE is superior to FS-LASIK in corneal biomechanics. Therefore, this systematic review and meta-analysis used the results of ocular response analyzer and corvis ST to explore whether SMILE is superior to FS-LASIK in corneal biomechanics. METHODS: The literature was searched in PubMed, EMBASE, and Controlled Trials Register databases. The Cochrane Collaboration’s “risk of bias” tool was used to evaluate the quality of the included randomized clinical trials, and the Newcastle-Ottawa Scale was used to evaluate the included non-randomized controlled trials. The results were analyzed using Revman 5.3. RESULTS: Sixteen studies (3 randomized clinical trials and 13 non-randomized controlled trials) were included in this meta-analysis. There was no statistical difference in corneal biomechanics between SMILE and FS-LASIK in corneal hysteresis [mean difference (MD), 0.20; 95% confidence interval (CI): −0.09, 0.49; P = .18] and corneal resistant factor (MD, 0.31; 95% CI: −0.09, 0.71; P = .13), A1 time (MD, −0.02; 95% CI: −0.11, 0.07; P = .66), A1 length (MD, 0.01; 95% CI: −0.01, 0.03; P = .42), A1 velocity (MD, 0.00; 95% CI: −0.01, 0.01; P = .85), A2 velocity (MD, −0.01; 95% CI: −0.11, 0.09; P = .86), HC time (MD, 0.12; 95% CI: −0.13, 0.38; P = .35), The stiffness parameter at first applanation (MD, −7.91; 95% CI: −17.96, 2.14; P = .12), The ratio between the deformation amplitude 2 mm away from apex and the apical deformation (MD, 0.01; 95% CI: −0.26, 0.27; P = .96). CONCLUSION: A comprehensive assessment of the parameters of ocular response analyzer and corvis ST showed that SMILE is not superior to LASIK in corneal biomechanics 3 months post-surgery.