EFFECT OF LIGHT STIMULATION ON THE DISTRIBUTION OF N-METHYL-N-NITROSOUREA-INDUCED RETINOPATHY

Abstract

For determination of the effect of light stimulation on the distribution of the lesions in N-methyl-N-nitrosourea (MNU)-induced retinopathy, MNU-treated (70mg/kg) rats with sutured closed right eyelid were housed under constant light (150 lux for 24 hours). In spite of the unilateral eyelid closure, retinopathy was observed in bilateral retinas by 24 hours after MNU treatment and the retinal lesion was severe in the area centralis. In addition, the retinopathy wasmore pronounced in the non-closed left retina than that in the closed right retina. In the morphometrical analysis of the retina at 21 days after MNU treatment, the ratio of the outer nuclear layer thickness to the whole retinal thickness was markedly reduced in the area within 2 nun distance from the optic nerve head in both retinas. These results indicate that the light stimulation does not critically affect the distribution of the MNU-induced lesions but does enhance the severity of the lesion.