Clinical results with two different pharmaceutical preparations of riboflavin in corneal cross-linking: an 18-month follow up

Background: Comparison of long-term clinical results of two different pharmaceutical formulations used in corneal cross-linking (CXL) in keratoconus patients. Methods: Sixty eyes of 60 keratoconus patients underwent CXL in two groups. We used riboflavin preparations from Sina Darou, Iran in group A, and Streuli Pharma, Switzerland in group B. Here we made inter-group comparison of changes in vision, refraction, Pentacam indices, corneal biomechanical indices, and endothelial cell count (ECC) 18 months after CXL. Results: Since four patients were lost to follow-up, 56 eyes (28 eyes in each group) were compared. Mean improvement in uncorrected visual acuity (UCVA) was 0.31 ± 0.65 LogMAR (P = 0.014) in group A and 0.24 ± 0.62 LogMAR (P = 0.082) in group B. Best corrected visual acuity (BCVA) remained quite unchanged in both groups (P = 0.774). Mean spherical refractive error reduced by 0.45 ± 1.15 diopter (D) (P = 0.041) in group A and 0.27 ± 1.73 D (P = 0.458) in group B (P = 0.655). Cylinder error and spherical equivalent had a similar trend without any change. Max-K (P = 0.006) and mean-K (P = 0.044) decreased significantly more in group A compared to group B. The reduction in CCT was significantly more in group A than group B (P = 0.004). Q-value was quite unchanged in both groups (P = 0.704). The inter-group difference in CH reduction was borderline significant statistically (P = 0.057). Changes in corneal resistance factor and endothelial cell count were not significantly different between two groups (P = 0.117 and P = 0.229). Conclusion: Clinical results of CXL with the domestic preparation of riboflavin are similar to that achieved with the Swiss made product in some aspects, and it is the preferred brand in some other aspects. This study will continue to report longer follow-up results.