Investigation of the biomechanics of blue-light cross-linking on rabbit scleral tissue with different concentrations of riboflavin

Abstract

Objective This study had two objectives: To evaluate the efficiency of collagen cross-linking (CXL) in rabbit sclera induced by different concentrations of riboflavin and blue light. To find the optimal concentration of riboflavin in scleral cross-linking. Methods In this experimental study, scleral stress-strain measurementswere performed to evaluate the biomechanical efficiency of collagen cross-linking using riboflavin and blue light (460 nm). Ten New Zealand rabbits were randomly divided into Group Ⅰ and Ⅱ. In Group Ⅰ, a 0.1% riboflavin solution was used for the CXL induced by blue light. In Group Ⅱ, a 0.5% riboflavin solution was used. In each group, the right eye was defined as the experimental eye and the left eye was the control. Biomechanical measurements of scleral strips were performed 2 months after CXL using a microcomputer-controlled biomaterial testing device. The focus was on Young's modulus calculated as σ=Aexp(B×e) and maximum stress. The data were analyzed by paired sample t-test and two independent sample t-test. Results Scleral specimens from both groups exhibited nonlinear stress-strain behavior with an initially low Young's modulus that increased gradually under higher stress. It was derived using the equation σ=Aexp(B×e). The Young's modulus (Group Ⅰ: t=19.78, P<0.01; Group Ⅱ: t=7.82, P<0.01) and maximum stress (Group Ⅰ: t=4.90, P<0.05; Group Ⅱ: t=4.30, P<0.05) of the sclera increased after CXL. In addition, the scleral strips in Group Ⅰ were stiffer than in Group Ⅱ (Young's modulus: t=2.52, P<0.05; Maximum stress: t=3.03, P<0.05). Conclusion CXL induced by riboflavin/blue light can significantly enhance the biomechanical strength of rabbit sclera. The 0.1% riboflavin solution had significantly better biomechanical behavior than the 0.5% riboflavin in CXL. Key words: Collagen cross-linking; Sclera; Riboflavin; Biomechanics; Blue light