The Efficiency and Safety of Oxygen-Supplemented Accelerated Scleral Cross-Linking in Rabbits.

Abstract

PURPOSE: The purpose of this study was to evaluate the efficacy and safety of accelerated scleral collagen cross-linking (SXL) with supplemental oxygen. METHODS: The rabbit scleral tissues were randomly divided into seven different SXL protocols, including traditional (T)-SXL (3 mW/cm2 for 30 minutes, 3*30) and accelerated (A)-SXL (30 mW/cm2 for 3, 5, or 8 minutes, respectively, with or without supplemental oxygen). The control group received no ultraviolet-A (UVA) radiation. The tangent modulus of scleral strip was determined by uniaxial tensile test. The protocol with better mechanical property and shorter cross-linking time in vitro was selected for immediate safety assessment using electroretinogram (ERG) in vivo, hematoxylin and eosin (H&E) staining and TUNEL assay in vitro. RESULTS: The tangent modulus was significantly greater in all SXL groups compared to the control group. The equatorial sclera showed a larger stiffening effect than the posterior. In the equatorial sclera, extending the irradiation time in normoxic A-SXL can result in a further enhancement of the stiffening effect. The tangent modulus was enhanced by 92% in the hyperoxic A-SXL group (30*3) compared with the normoxic A-SXL (30*3) group, and achieved the same mechanical performance as the T-SXL group. The oxygen supplementation did not play a role in further improving he stiffening effect at the posterior sclera. The ERG and H&E staining indicated no abnormalities in the sclera and retina. Apoptosis was only observed in the outer layer of the sclera in the A-SXL groups. CONCLUSIONS: A-SXL protocol of 30 mW/cm2 can improve the mechanical properties of the sclera. In particular, the protocol of 30 mW/cm2 for 3 minutes with supplemental oxygen showed excellent cross-linking efficacy with shorter surgical time and was relatively safe.