Iontophoresis Corneal Cross-linking With Oxygen Supplementation in Ovine Eyes

Abstract

PURPOSE: To evaluate the biomechanical changes and advanced oxidation protein products (AOPP) production after different corneal cross-linking (CXL) protocols with or without oxygen supplementation. METHODS: Ovine eyes in the study were equally distributed to five groups as control, standard Dresden protocol, diluted alcohol- and iontophoresis-assisted CXL (DAI-CXL), and 0.1% and 0.2% riboflavin-mediated iontophoresis-assisted CXL with oxygen supplementation (I-CXL). Corneas that received CXL were divided into two equal parts, one part was used for uniaxial tensiometry and one part was used for AOPP measurement. RESULTS: All treatment groups showed higher Young's modulus and stiffness compared to the control group ( P < .05). Both oxygen-assisted I-CXL groups with 0.1% and 0.2% riboflavin concentrations had higher corneal Young's modulus ( P = .009 and .006, respectively) and stiffness ( P = .009) values, whereas the DAI-CXL group had lesser Young's modulus and stiffness values ( P = .032) compared to the Dresden protocol group. All treatment groups showed higher AOPP concentrations compared to the control group ( P < .05). DAI-CXL and I-CXL groups showed similar AOPP formation compared to the Dresden protocol ( P = .673). CONCLUSIONS: When the epithelium is intact, the desired increase in corneal stiffness might not be achieved. However, increasing the oxygen in the environment might provide a sufficient increase in stiffness in cases undergoing epitheliumon I-CXL, which might be promising in terms of shortening the CXL therapy and decreasing the complications. [ J Refract Surg . 2022;38(10):674–681.]