Long-Term Follow-Up of the Effect of Accelerated CXL Protocol on Pellucid Marginal Degeneration

Purpose: Pellucid marginal degeneration (PMD) is a rare non-inflammatory corneal ectasia that progresses, making visual rehabilitation challenging.Since PMD is unique and different from keratoconus, the effect of collagen cross-linking might be different.This study aims to evaluate the efficacy of accelerated corneal collagen crosslinking (CXL) over a 5-year follow-up period in patients with PMD.Methods: A retrospective interventional case series study was conducted on 43 eyes of 24 patients with PMD who underwent accelerated CXL.Visual acuity, refraction, topographic keratometry, pachymetry, and topometric indices were measured before and after the procedure. Results:The study found an improvement in visual acuity from LogMAR 0.36 0.22 before CXL to LogMAR 0.21 0.12 after CXL (P < 0.001).The study also observed a reduction in the sphere from -2.46 1.81 D before CXL to -1.7 1.63 after CXL (P < 0.001).However, there was no significant difference in cylindrical value (P = 0.83).Flat keratometry decreased from 45.11 1.75 D preoperatively to 44.30 1.75 postoperatively (P < 0.001), but steep keratometry did not change significantly (preoperative 47.92 1.74D, postoperative 47.53 1.70, P = 0.081).Additionally, maximum keratometry reduced from 51.03 3.21 D before CXL to 50.53 3.42 after CXL (P = 0.005). Conclusions:The results of this study suggest that accelerated CXL can be effective in treating PMD, as it was found to improve visual acuity and reduce spherical and maximum keratometry values.