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 (Kmin), 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 Kmin (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.
Keywords: Collagen cross-linking using riboflavin; corneal collagen cross-linking; progressive keratoconus.