Effect of Ablation Depth on the Endothelial Status of Eyes of Myopic Patients Undergoing Transepithelial Photorefractive Keratectomy: A Retrospective Study in Saudi Arabia.

Purpose: The aim of this study was to correlate ablation depth on corneal endothelial cell (EC) indices following transepithelial photorefractive keratectomy (TPRK) in Saudi myopic patients.

Methods: This was a retrospective cohort study of myopic eyes treated with TPRK. The changes in EC density and other indices were noted one week (W1) and 12 weeks (W12) after TPRK, which was the primary outcome. The laser ablation depth (AD) was correlated to the EC indices. The preoperative factors were also correlated to the outcomes using regression analysis to review predictors of change in the EC density.

Results: We had 120 eyes of 60 myopic patients operated on for TPRK. The mean of maximum AD (Adm) and central AD (ADc) were 110.3±23.7 µ and 108.8±24.4 µ, respectively. The median change in EC count at W1 and W12 were -9.5 (interquartile range (IQR) -33.0, 17.0) and -3.0 (IQR -29.3, 13.3), respectively. The ADm was negatively correlated to a change in EC density at W1 (Wilcoxon (Z) =-2.7, P = 0.006) and at W12 (Z = -3.74, P <0.001). ADm (Kruskal-Wallis (K-W) test (P) = 0.167), ADc (K-W P = 0.08), central corneal thickness (K-W P = 0.65), and use of mitomycin-C (K-W P = 0.357) were not significant predictors of the change in EC density at W1. None of the variables significantly influenced the change in EC density at W12.

Conclusions: The corneal ablation depth for TPRK is correlated to changes in EC density at W1 and W12 after TPRK.