Effect Of Riboflavin-UVA Induced Collagen Cross-linking On Form-deprived Myopia Of The Sclera In Guinea Pigs

Purpose Myopia has the highest incidence in the eye diseases,and presents a trend of rapid grouth.While the degree of myopia is deeper,the risk of retinal detachment,retinal neovascularization,cataracts and glaucoma also increased significantly,these complications can cause severe visual loss and irreversible visual impairment.In myopic eye,the structure of sclera was changed,the dry weight of sclera was reduced,the collagen arrangement was disordered,the diameter of the sclera was reduced,and the anti-tension ability of sclera was poor.The scleral collagen cross-linking is a method to covalent binding the sclera collagen,and then to enhance the anti-traction ability of sclera,thereby to prevent further extension of axial length.This research adopts the method of making form deprivation myopia in guinea pigs model,and through the riboflavin-UVA induced collagen cross-linking in the posterior sclera,to observe the effect of cross-linking in the myopia model,and we expect to provide a new reliable method of clinical treatment of myopia.Methods 1.Nine guinea pigs were randomly divided into normal control group(NOR,n=4)and form deprivation myopia group(FDM,n=5).FDM group was from deprived in the right eye by a mask making with balloon,and the NOR group without any treatment,the right eye was treated as the experimental eye.Measurements were given before the cover and after 1,2 weeks including refraction and axial length.2.Nine guinea pigs were selected to this study.The right eye was the experimental eye,the left eye was the control eye.The riboflavin-ultraviolet A collagen cross-linking was given on the right eye,1 week from the surgery,the guinea pigs were killed to do a biomechanical test.3.Twenty-five pigmented guinea pigs of 3-weeks-old were randomly assigned into 4 groups,including Normal control group(NOR,n=7),Form-Deprived Myopia group(FDM,n=7),Riboflavin-UVA cross-linking group(NOR+CL,n=5)and Form-Deprived Myopia with cross-linking group(FDM+CL,n=6).NOR+CL group and FDM+CL group were under the riboflavin-UVA cross-linking surgery before the experiment,then FDM group and FDM+CL group were monocularly form-deprived in the right eyes.The retinoscopy,A-scan and keratometry were measured before and each 1 week,2 weeks,3 weeks,4weeks after the form-deprived.After 4 weeks,the guinea pigs were executed by snapping the certical vertibra to undergo the histopathology test and the biomechanical test.Results 1.Mask from deprivation was successfully to produce a myopia model in guinea pigs,while the refractive error in the experimental eye was-2.50 D myopia than the control eye,the axial length was longer about 0.2mm.the right eye in the FDM group was more myopia than the control left eye,and in the NOR group,there was no difference,and there was significantly difference between the two groups.2.Riboflavin-UVA induced posterior sclera collagen cross-linking can successfully induce sclera collagen cross-linking,effectively enhanced the mechanical properties of the sclera,the ultimat stress and elastic modulus were increased,and the ultimate strain was decreased.3.The posterior sclera collagen cross-linking induced by riboflavin-UVA can slow down the progression of experimental myopia in guinea pigs.Riboflavin-UVA collagen cross-linking slow down the growth about 35% of myopia.The axial length of the experimental eye in FDM group was significantly longer than the control lateral eye comparing with the other 3 groups,and there was no significantly difference between FDM+CL group and NOR group.According to the histopathology test,there was no obvious damage to retina and RPE cells in the cross-linking groups.Conclusion Riboflavin / UVA induced collagen cross-linking in the posterior sclera can enhance the mechanical properties and then to delay the experimental myopia in guinea pigs,and there was no obvious damage in retina and RPE cells.