Protective effects of riboflavin-UVA-mediated posterior sclera collagen cross-linking in a guinea pig model of form-deprived myopia.

Aim: To evaluate the effect of posterior sclera collagen cross-linking induced by riboflavin-ultraviolet A (UVA) on form-deprived myopia in guinea pigs.

Methodes: Twenty-five pigmented guinea pigs of 3-week-old were randomly assigned into 4 groups that included normal control (NOR, =7), form-deprived (FDM, =7), normal with riboflavin-UVA cross-linking (NOR+CL, =5) and form-deprived with cross-linking (FDM+CL, =6). The NOR+CL group and the FDM+CL group received the riboflavin-UVA induced cross-linking at day 0. FDM was induced by monocularly deprived with facemask in the right eyes. The refraction, axial length and corneal curvature were measured by retinoscopy, A-scan and keratometer respectively in scheduled time points (day 0 and 1, 2, 3, 4wk after form-deprivation). At the end of 4 weeks' experiment, stress-strain tests of sclera were measured and morphological changes of sclera and retina were examined.

Results: After 4wk, the interocular difference of refractive error were -0.11±0.67, -2.93±0.56, 1.10±0.58, and -1.63±0.41 D in the NOR, FDM, NOR+CL, and FDM+CL groups respectively. Mixed-effect linear model revealed significant effect of FDM (<0.01) and CL (<0.001). Also, after 4wk, the interocular difference of axial length were 0.01±0.04, 0.29±0.07, -0.13±0.06, and 0.11±0.05 mm in the NOR, FDM, NOR+CL, and FDM+CL group. Mixed-effect linear model revealed significant effect of FDM (<0.001) and CL (<0.01). As for corneal curvature, significant interocular difference have not found between any of the two groups. At the end of this experiment, the ultimate stress and elastic modulus were found significantly increased in both CL groups. But no difference was found in the groups without cross-linked. There was no abnormality observed in the retina and RPE cells of the treated eyes.

Conclusion: The posterior sclera collagen cross-linking induced by riboflavin-UVA can slow down the progress of myopia and increase the sclera biomechanical strength in the guinea pig model of form-deprived myopia.