Longitudinal changes in corneal epithelial thickness after FS-LASIK, keratorefractive lenticule extraction, and transepithelial PRK: systematic review and meta-analysis.

PURPOSE: To evaluate the longitudinal changes in corneal epithelial thickness after FS-LASIK, keratorefractive lenticule extraction (KLEx), and transepithelial photorefractive keratectomy (tPRK).

SETTING

Multicenter, international.

DESIGN

Systematic review and meta-analysis.

METHODS

This study was registered with International Platform of Registered Systematic Review and Meta-Analysis Protocols (INPLASY202510085). A systematic search of electronic databases was conducted through January 2025 in accordance with PRISMA guidelines. Studies reporting both baseline and postoperative corneal epithelial thickness in myopic eyes treated with FS-LASIK, KLEx, or tPRK were included. Data from 33 studies (n = 2579 eyes) were extracted, with 23 studies incorporated into the meta-analysis. Meta-regressions were performed to identify predictors of epithelial thickness changes.

RESULTS

FS-LASIK-treated eyes exhibited a central epithelial thickness increase of 3.31 ± 0.75 μm at 1 month, further increasing to 4.58 ± 0.72 μm at 6 months. KLEx resulted in central thickening of 2.51 ± 0.28 μm at 1 month and 3.82 ± 0.35 μm at 6 months. By contrast, tPRK eyes initially demonstrated epithelial thinning, followed by central thickening reaching 3.89 ± 0.38 μm at 6 months. Meta-regression analyses indicated that each additional diopter of myopic correction was associated with 1.05 μm greater central epithelial thickening in FS-LASIK and 1.04 μm in KLEx at 3 months postoperatively. In addition, an increase in the programmed optical zone (OZ) corresponded to a reduction in postoperative epithelial thickness.

CONCLUSIONS

Distinct epithelial remodeling patterns were observed: rapid, early thickening and stabilization with FS-LASIK and KLEx vs delayed regeneration with tPRK. Baseline spherical equivalent and programmed OZ were predictors of corneal epithelial thickness changes, suggesting procedure-specific remodeling profiles that may support future refinement of refractive planning.