Iontophoresis Corneal Cross-linking With Oxygen Supplementation in Ovine Eyes

To evaluate the biomechanical changes and advanced oxidation protein products (AOPP) production after different corneal cross-linking (CXL) protocols with or without oxygen supplementation.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.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).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.].