Effect of Corneal Cross-linking on Epithelial Hyperplasia and Myopia Regression After Transepithelial Photorefractive Keratectomy

PURPOSE: To investigate the effect of accelerated corneal cross-linking (CXL) on epithelial thickness change and refractive outcome after myopic transepithelial photorefractive keratectomy (TPRK). METHODS: This study compared epithelial thickness changes in 49 patients undergoing TPRK-CXL with 49 patients undergoing TPRK who were matched for age and refractive error. Corneal epithelial thickness, obtained using spectral-domain optical coherence tomography preoperatively and 12 months postoperatively, was compared between the groups. Regression analysis was performed to investigate the association between changes in epithelial thickness and keratometric power. Factors affecting myopic regression (> 0.50 diopters] were evaluated using logistic regression analysis. RESULTS: For TPRK, the mean epithelial thickness of the center (2-mm diameter), paracenter (2- to 5-mm diameter), and pericenter (5- to 6-mm diameter) increased by 6.5 ± 3.1, 7.0 ± 2.9, and 4.9 ± 2.9 µm, respectively; increases of 4.8 ± 3.0, 5.9 ± 2.8, and 4.8 ± 2.7 µm were observed following TPRK-CXL, indicating a significant difference in the center ( P = .013). Epithelial thickness increased linearly to the magnitude of myopic correction and was negatively correlated with the optical zone diameter of ablation. Change in epithelial thickness showed a linear correlation with the change in keratometric power between 1 and 12 months postoperatively, indicating regression in eyes following TPRK. Corneal epithelial thickening was significantly associated with myopic regression and simultaneous CXL tended to reduce the risk of regression. CONCLUSIONS: TPRK-CXL induces less epithelial hyperplasia than does TPRK, presumably owing to the effect of CXL, and the magnitude of epithelial thickening seemed to be associated with myopic regression. [ J Refract Surg. 2019;35(6):354–361.]