Safety and efficacy of riboflavin-assisted collagen cross-linking of cornea in progressive keratoconus patients: A prospective study in North East India

INTRODUCTION: Riboflavin-and ultraviolet (UV)-A-mediated collagen cross-linking of the cornea is a frequently used therapeutic measure for the treatment of progressive keratoconus (PK). First, riboflavin increases cross-linking and second, it serves as a protective shield to other deep ocular structures. However, pharmacogenomic variation in riboflavin efficacy is reported. As the Northeast Indian population represents a genetically diverse group of population compared to mainstream India, we have assessed the efficacy of the procedure in a northeastern population with PK. METHODS: In this study, 78 eyes with PK were included (n = 39 in the treatment arm and n = 39 in the control arm). The primary objective was to evaluate the effect of corneal collagen cross-linking using riboflavin (C3R) (epithelium off) on maximum keratometry. The secondary objectives were evaluation of change in corneal topography parameters, i.e., minimum keratometry (K-min), simulated keratometry (Sim K), subjective refraction (cylinder power, spherical power, and spherical equivalent [SE]), uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), and contrast sensitivity (CS) and safety (intraocular pressure, endothelial cell density, and percentage hexagonality) at 1, 3, and 6 months following C3R procedure. RESULTS: Statistically significant improvement was noted in K-min (6 months), Sim K (3 and 6 months), cylinder power (3 and 6 months), spherical power (3 and 6 months), SE (3 and 6 months), BCVA (6 months), and UCVA (1, 6 months) in the C3R group (n = 39) when compared to the control group (n = 39). The mean CS decreased at 1 month and gradually improved to achieve statistically significant value at 6 months in the C3R group (P < 0.05). CONCLUSION: Riboflavin-assisted C3R treatment showed promising efficacy in the treatment of PK patients in our population. As the collagen turnover rate of cornea is 2-3 years and the progression of PK is highly variable, we need long-term studies to evaluate the efficacy of C3R over time, requirement of repeat therapy, and safety of repeat cross-linking.