Changes in decorin levels in the posterior sclera of form-deprived guinea pig eyes

Objective To investigate the changes in decorin levels in the posterior sclera of guinea pig eyes induced by form deprivation and its association with the pathogenesis of mammalian myopia.Methods Two groups of guinea pigs,with 10 animals in each group,were included in the study.Animals in the monocular-deprived(MD) group were subjected to 2 weeks of form deprivation,and those in the MD/recovery group were treated the same way followed by 1 week of recovery.Form deprivation with a monocular occluder was introduced between 2 and 3 weeks of age in all animals.The contralateral,untreated eyes of the animals served as interocular controls.Refraction and axial eye length of all animals were measured at the beginning and the end of the treatment period.All animals were sacrificed and eyes enucleated at the end of study.The posterior sclera was dissected from the eye and the expression of decorin core protein was assayed by immunohistochemistry and RT-PCR.The data were analyzed by a paired t-test and analysis of variance(ANOVA).Results In the MD group,2 weeks of monocular deprivation produced-8.15 D myopia with an 0.63 mm axial elongation of the eye.In the MD/recovery group,2 weeks of monocular deprivation followed by 1 week of recovery produced-4.30 D myopia with an 0.57 mm axial elongation of the eye.There was a significant difference in the amount of myopia between the two groups(F=5.974,P0.05).Immunohistochemistry showed positive stains of decorin core protein in both the MD and control eyes.There were significant differences in the relative levels of decorin core protein mRNA between the MD eyes and interocular controls(P0.05).This was also observed between the recovered eyes and interocular controls.Conclusion Decorin levels in the posterior sclera of guinea pig eyes decrease significantly under form deprivation,but can be restored during a recovery period.This suggests that decorin might be involved in the pathogenesis of myopia.