Corneal Cross-Linking in Pellucid Marginal Degeneration: Evaluation after Five Years

PURPOSE: To evaluate the long-term outcome of corneal cross-linking (CXL) for pellucid marginal degeneration (PMD). METHODS: In a retrospective study, forty eyes of forty patients were enrolled. All subjects had undergone CXL for PMD at least 5 years before the assessments. Visual acuity, refraction, and topography data were compared to their respective values before CXL. RESULTS: The comparison between mean preoperative logMAR uncorrected visual acuity and 5-year postoperative evaluation revealed no significant change (1.20 ± 0.65 and 1.17 ± 0.64, P > 0.05). No statistically significant difference was noted comparing preoperative mean logMAR best-corrected visual acuity (BCVA) and postoperative mean logMAR BCVA (0.24 ± 0.19 and 0.22 ± 0.20, P > 0.05). We did not find any significant difference between pre- and postoperative spherical equivalent and spherical refractive errors (P = 0.419 and P = 0.396, respectively). Regarding the BCVA Snellen lines, 23 eyes had no significant change in pre- and postoperative examinations, 11 eyes had improvement, and 6 subjects showed worsening defined as significant when two or more lines change. The spherical equivalent refractive error improved in 4 subjects, was stable in 25, and worsened in 11 subjects, while a 0.5 diopter or more myopic change was considered significant. Furthermore, regarding steep keratometry values, 25 subjects were stable, 7 had improvements, and 8 worsened. CONCLUSION: CXL appears to be a safe and effective procedure to halt the progression of PMD.