Long term outcome of corneal collagen cross linking in progressive keratoconus

Purpose: To evaluate the efficacy of corneal collagen cross linking in the management of cases of progressive keratoconus. Methods: Thirty five patients (fifty one eyes) with progressive keratoconus who underwent cross linking with a mean follow up of 14.38 + 9.36 months (range 6–48 months) were compared with a control group of twenty five fellow eyes that did not undergo the procedure. Collagen cross linking was performed using 0.1% riboflavin (in 20% dextran T500) and ultraviolet A (UVA) irradiation (370 nm,3 mW/cm2, 30 min). Results: Analysis of the treated group demonstrated a significant flattening of maximum keratometry by 0.96+2.33 D (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 D (p=0.05) and visual acuity decreased by mean 0.05 + 0.14 (p=0.2). No tatistical 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 improving the visual acuity in these patients.