Prospective longitudinal study of corneal collagen cross-linking in progressive keratoconus

Background: Collagen cross-linking has been reported to be effective in treating progressive keratoconus, and this study aims to evaluate the long-term efficacy of this procedure. Design: Prospective longitudinal interventional study of patients with progressive keratoconus who underwent cross-linking in a tertiary referral hospital. Participants: Thirty-five patients (51 eyes) who underwent cross-linking with a mean follow-up of 14.38±9.36 months (range 6-48) were compared with a control group of 25 fellow eyes that did not undergo the procedure. Methods: Cross-linking was performed using 0.1% riboflavin (in 20% dextran T500) and ultraviolet A irradiation (370nm, 3mW/cm², 30min). Main Outcome Measures: Maximum keratometry in dioptres, logMAR best spectacle-corrected visual acuity, cylindrical power, manifest refraction spherical equivalent and central corneal thickness. Results: Analysis of the treated group demonstrated a significant flattening of maximum keratometry by 0.96±2.33 dioptres (P=0.005) and a significant improvement in visual acuity by 0.05±0.13 logMAR (P=0.04). In the control group, maximum keratometry increased significantly by 0.43±0.85 dioptres (P=0.05), and visual acuity decreased by mean 0.05±0.14 (P=0.2). No statistical differences were noted regarding cylindrical power, spherical equivalent or corneal thickness in both groups. Conclusions: Results indicate that corneal collagen cross-linking using riboflavin and ultraviolet A is effective as a therapeutic option in cases of progressive keratoconus by reducing the corneal curvature and by improving the visual acuity in these patients.