Epithelial thickness and tomographic characteristics in central keratoconus: A comparative analysis of cross-linked and untreated eyes

Abstract

Purpose: To evaluate epithelial thickness (ET) and corneal tomographic parameters in early-stage keratoconus (KC) patients with central cones, comparing eyes with and without a history of corneal collagen cross-linking (CXL). Methods: This retrospective cross-sectional study included patients with early-stage keratoconus (Grade 1–2) and central cone localization diagnosed between 2020 and 2024. Central cones were defined by a maximum keratometry value within the central 3 mm zone, and one eye per patient was randomly selected. Eyes were classified as cross-linked (CXL+) or untreated (CXL−), with all treated eyes demonstrating clinical stability. Corneal tomography and epithelial thickness mapping were performed using Scheimpflug imaging and spectral-domain anterior segment optical coherence tomography. Results: Group 1 (n=30 eyes) had a mean age of 24.6 ±5.7 years, significantly younger than Group 2 (n=33 eyes, 35.9 ±9.0 years, p < 0.05). The mean interval since CXL was 4.8±3.2 years. Gender distribution did not differ significantly between groups. Among epithelial parameters, central ET was significantly thinner in CXL-treated eyes (p=0.014), whereas peripheral ET values showed no significant differences. Tomographic comparison revealed a significant reduction in front apex thickness in Group 1 (p=0.018), while other indices remained comparable. Conclusion: In early-stage central keratoconus, CXL-treated eyes demonstrated thinner central epithelial thickness compared to untreated eyes in a cross-sectional comparison. These findings suggest that epithelial remodeling may serve as a long-term biomarker of biomechanical stabilization after CXL, highlighting the clinical utility of epithelial mapping in the follow-up of keratoconus patients.