[Protective effect of alpha-tocopherol in retinal light damage of pigmented rabbits--evaluation by nitro blue tetrazolium staining].

Free radicals are thought to be one of the causes of retinal light damage. Experiments were performed to identify the production of free radicals in light exposed retinas of rabbits using nitro blue tetrazolium (NBT) staining. In addition, a free radical scavenger, alpha-tocopherol, was administered systemically before light exposure to evaluate the protective effect against the retinal light damage. Pigmented rabbits were exposed to xenon light without long waves for 60 minutes. The eyes were enucleated immediately after light exposure, and incubated in the equilibrated media at 37 degrees C with 0.1 mM NBT solution for 60 minutes. After incubation, the eyes were embedded in paraffin, sectioned, and mounted without further staining. The same procedure was done to the tocopherol treated retinas. In the light exposed eyes, the NBT staining was markedly observed at the inner retina, and the staining was more remarkable than that of the non-exposed eyes. The tocopherol treated eyes showed weaker NBT staining in the inner retina than the non-treated eyes. The results suggest that free radicals are increased in the inner retina by light exposure and alpha-tocopherol suppresses production of free radicals.