Evaluation of 2 Riboflavin Dosing Regimens for Corneal CXL in Eyes With Progressive Keratoconus or Ectasia
Narrative Responses:
Purpose
This study compared safety and efficacy of two riboflavin-dosing intervals (2 vs. 5 minutes) during collagen cross-linking for treatment of progressive keratoconus or post-refractive ectasia to address concerns about whether more frequent application of a viscous riboflavin-dextran solution may impede UV-light penetration.
Methods
This prospective, randomized study enrolled subjects over 9 years old with progressive keratoconus or documented ectasia after refractive surgery. After epithelial removal, riboflavin 0.1% ophthalmic solution was applied topically every 2 minutes for 30 minutes, with penetration confirmed at a slit lamp. Then the eye was irradiated with a 365-nm 3-mW/cm2 UV light for 30 minutes. The first treated eye per subject was randomized to riboflavin instillation at 2- or 5-minute intervals during UV-irradiation. Vision, keratometry and adverse events were assessed at baseline, 1 day, 1 week, 3 and 6 months after treatment.
Results
Two hundred patients were enrolled (149 keratoconus and 51 ectasia); 105 were randomized to the 2-minute and 95 to the 5-minute riboflavin application interval. At baseline, the median Kmax by tomography was 58D and median best corrected visual acuity (BCVA) was 20/40. From baseline to 6-months postop, the median improvement in Kmax was 0.1D in the 2-min group and 0.05D in the 5-min group, P=0.24, and median change in BCVA was 0 lines in the 2-min group and 1 line improvement in the 5-min group, P=0.096. Crosslinking appeared to stabilize corneas without progression and no corneas required retreatment or transplant.
Conclusion
The riboflavin application interval (2 vs. 5 minutes) during the 30-minute UV-irradiation did not significantly affect the efficacy or safety of the corneal crosslinking treatment for keratoconus or corneal ectasia.