Abstract
Purpose :
A minimum corneal thickness of 400 μm after epithelium removal has been recommended for keratoconus (KC) patients undergoing conventional corneal collagen cross-linking (CXL) to avoid endothelial cell damage, excluding patients with advanced KC with thinner corneas. This systematic review investigated the efficacy and safety of CXL in patients with KC and a corneal thickness of <400μm.
Methods :
MEDLINE Ovid, Embase Ovid, and SCOPUS databases were searched in July 2023for studies published in peer-reviewed journals in English. prospective and retrospective case series, cohort studies, and randomised clinical trials were eligible. Random effects meta-analysis was used to pool average change from pre-operative keratometry and visual acuity parameters at key timepoints. Study quality was assessed using the JBI Critical Appraisal Checklist for Case Series. PROSPERO registration: CRD42023403190.
Results :
Twenty case series published between 2011 and 2023 were included. Modifications to standard CXL techniques included using hypo-osmolar riboflavin, Sub 400 protocol, accelerated, contact lens assisted, accelerated contact lens assisted, transepithelial, accelerated transepithelial, customized peripheral, customized epithelial debridement, epi-off-lenticule-on, and Ionotropic CXL. Average maximum keratometry (Kmax) deceased at 6 (n=9 studies/208 eyes, mean -1.4D, 95% CI -2.6, -0.2) and 12 months (n=12 studies/ 272 eyes, mean -1.7D, 95% CI -2.3, -1.0) compared to baseline. Corrected visual acuity (CVA) also improved at 6 (n=12 studies/259 eyes, mean -0.05 log MAR units, 95% CI -0.08, -0.02) and 12 months (n=15 studies/ 312 eyes, mean -0.08 log MAR units, 95% CI -0.12, -0.05). All studies were conducted seamlessly without encountering any notable complications.
Conclusions :
CVA and Kmax improved following CXL, suggesting that performing CXL in patients with corneal thicknesses of < 400 microns is safe and effective. The study is limited due to heterogeneity in study design and interventions, and the inclusion of small retrospective case series. Further prospective comparative studies are necessary to investigate which techniques produce optimal results.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.