Investigating the Effect of Different Riboflavin Concentrations on Corneal Biomechanical Properties in Cross-linking.

Purpose: To evaluate the corneal cross-linking (CXL) efficacy of riboflavin (RF) at 5 different concentrations (0.1%, 0.25%, 0.5%, 0.75%, 1.0%) and determine the optimal concentration for maximizing the cornea's biomechanical performance.

Setting: Department of Ophthalmology, Zhongshan Hospital, Fudan University.

Design: Experimental study.

Methods: The corneal epithelium was removed from all eyes. In the first part, 0.1% to 1.0% RF solutions were applied to rabbit eyes for 30 minutes, with 20% dextran used as the vehicle for the RF solutions. After application, RF concentration in the cornea and aqueous humor were evaluated. In the second part, after applying different RF solutions, the corneas underwent CXL with 9 mW/cm2 ultraviolet-A light for 10 minutes. Stress-strain curves, Young's modulus, and resistance to enzymatic digestion were measured.

Results: 107 eyes were used in total. RF concentrations in the cornea were 447.57 ± 28.72 μg/g, 536.51 ± 19.59 μg/g, 885.89 ± 111.77 μg/g, 1280.46 ± 103.86 μg/g, and 1668.68 ± 89.02 μg/g from 0.1% to 1.0% RF solutions, respectively. Following CXL, the corneal stress of the other four groups was 123%, 147%, 116%, and 69% relative to the 0.1% RF group at 10% strain. Similarly, after CXL with RF solutions at five concentrations, the residual corneal dry weights were 0.45 ± 0.08 mg, 0.53 ± 0.03 mg, 0.62 ± 0.07 mg, 0.50 ± 0.04 mg, and 0.35 ± 0.05 mg, respectively.

Conclusions: The 0.5% RF group achieved the optimal corneal biomechanical performance under controlled experimental conditions, with decreased efficiency as the RF concentration further increased.