Double contact lens-assisted corneal cross-linking in ultrathin corneas with keratoconus

Abstract

Aims: This study aimed to evaluate the safety and effectiveness of double contact lens-assisted corneal cross-linking (CXL) in keratoconus patients with very thin corneas. Settings and Design: This is a prospective, interventional, nonrandomized, and noncontrolled case series. Subjects and Methods: Twenty eyes of 15 patients with the corneal thinnest point (CTP) <400 μm were included in the study. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), Scheimpflug imaging, and endothelial cell loss were evaluated at baseline and at each study visit. After corneal epithelial debridement, ultrasonic pachymetry was used to measure CTP. Double soft contact lenses were applied while riboflavin was instilled every 2 min and ultrasonic pachymetry was repeated. The cornea was then exposed to ultraviolet A light (370 nm, 3 mW/cm2) for 30 min. Riboflavin 0.1% was administered every 2 min during irradiation. Statistical Analysis Used: Statistical evaluation of values at baseline and 6- and 12-month after CXL was performed using t-test with SPSS software version 20 (SPSS Inc., Chicago, IL, USA). Results: Following epithelial removal, mean CTP was 271.4 ± 13.7 μm (range: 263–284 μm). After double contact lens placement, mean CTP increased by 196.8 ± 15.4 μm (range: 188–223 μm) for a mean thickness of 467.1 ± 19.4 μm (range: 423–508 μm). No statistically significant differences were observed in maximum keratometry value (Kmax) and posterior elevation 1 year after CXL. Endothelial cell count, CDVA, anterior elevation, and average of simulated keratometry values (Average SimK) as well as the CTP were not significantly different before and 12 months after CXL. No postoperative complications were encountered in any of our patients. Conclusion: Double contact lens-assisted CXL can be effective for stabilizing corneal topography in eyes with advanced keratoconus, including those with corneas that are too thin for traditional CXL. Further controlled studies with a larger sample size are recommended to confirm our findings.