Reduced fluence corneal cross-linking in mild to moderate keratoconus: One year-follow-up

Purpose: To evaluate the safety and efficacy of reduced fluence CXL (lower dose of UV-A irradiation) in mild to moderate keratoconus. Setting: Farabi Eye Hospital, Tehran, Iran. Design: Non-randomized prospective comparative interventional case series. Every eligible patient included in the study (mild to moderate progressive keratoconus) was randomly allocated to case (reduced fluence) and control (standard) groups, except for bilateral patients. In these patients the eye with more advanced disease was allocated to control group and the other eye was randomly assigned in either case or control group. Operators performing refraction and images and the data analyst were masked, but patients and physicians were not. Methods: Forty-six eyes of 38 patients were recruited. Group 1 received 7 min (fluence of 3.8 J/cm(2)), while group 2 received 10 min of 9 mW/cm(2) UV-A (fluence of 5.4 J/cm(2)). Visual, keratometric and biomechanical outcomes were compared between groups. Results: At last follow-up (mean12 months, range 6-24 months), there were no statistically significant differences in changes in uncorrected visual acuity, best corrected distance visual acuity, Kmax, Kmean, corneal hysteresis, corneal resistance factor, endothelial cell counts, demarcation line depth, and intraoperative pain scores between groups (all p-values < 0.05). Conclusion: The results of this study show comparable one-year outcomes between 3.8 and 5.4 J/cm(2) accelerated CXL in mild to moderate keratoconus. Should the results of this study be confirmed in longer follow-ups, using a reduced fluence setting could be considered as an alternative to standard treatment in these patients.