To Investigate the Changes in Corneal Curvature and Its Correlation with Corneal Epithelial Remodeling After Trans-PRK and FS-LASIK.

Purpose: To evaluate curvature changes in different regions and their correlation with corneal epithelial remodeling in myopic patients undergoing femtosecond laser-assisted in situ keratomileusis (FS-LASIK) and transepithelial refractive keratectomy (Trans-PRK) after surgery.

Methods: One hundred and sixty-three patients (163 right eyes) undergoing Trans-PRK and LASIK were evaluated for up to 6 months using anterior segment optical coherence tomography (OCT) to measure the epithelial thickness and corneal topography to measure corneal curvature in different areas (2 mm, 5 mm, and 7 mm). We calculated the curvature ΔK (ΔK = preoperative - postoperative), ΔK_5-2 (ΔK_5-2 = K_5mm - K_2mm), ΔK_7-5 (ΔK_7-5 = K_7mm - K_5mm), and the epithelial thickness ΔET_5-2 (ΔET_5-2 = ET_5mm - ET_2mm) and ΔET_7-5 (ΔET_7-5= ET_7mm - ET_5mm).

Results: Corneal curvature flattened in each region of the two groups (all p < 0.001) and gradually steepened during the follow-up period. The Trans-PRK group flattened more significantly within 2 mm and 5 mm, while the FS-LASIK group at 7 mm. Both groups of ΔK decreased over time. Both groups of ΔK_5-2 and ΔK_7-5 gradually decreased during the follow-up period (P_5-2=0.025 and P_7-5 < 0.001 for Trans-PRK, P_5-2 = 0.011 and P_7-5 < 0.001 for FS-LASIK). The corneal epithelium of the two groups gradually thickened during the follow-up period, with Trans-PRK significantly thickening in the central and peripheral regions and FS-LASIK in the central and paracentral regions. There is a significant correlation between the ΔK_5-2 and ΔET_5-2, ΔK_7-5 and ΔET_7-5 (all r > 0.37, p < 0.001).

Conclusions: All groups showed significant curvature flattening after surgery and gradually steepening during the follow-up period. The corneal epithelium thickness in both groups of 17 regions became thicker,. In contrast, Trans-PRK group showed more significant thickening to the periphery and the central 5 mm area of the FS-LASIK. This study indicates a significant positive correlation between differences in epithelial thickening in different regions and differences in curvature changes in the corresponding areas PRK, FS-LASIK, curvature, corneal epithelial thickness.