Abstract
Purpose: :
It is known that light exposure can produce retinal damage and our aim was to determine the alterations produced in the retina by light exposure in an experimental model of retinal phototoxicity in rabbits.
Methods: :
The eyes of 74 New Zealand rabbits were divided into seven experimental groups. One group of animals was not exposed. Three groups were exposed to more than 100,000 luxes of a white light for 30, 60 or 120 minutes and sacrificed immediately after exposure. The remaining three groups were exposed to 30, 60 or 120 and sacrificed one week after exposure. Oxidative stress and the total antioxidant capacity in the retina were determined and retinal histological changes, such as number of photoreceptors and outer nuclear layer height were also studied. Moreover, early apoptosis was analyzed by immunohistochemistry for active caspase-3.
Results: :
The retinal exposure of white cold light increased the oxidative stress in the animals sacrificed just after the end of the exposure, and decreased after one week after the exposure. The retinal level of the total antioxidant power was not modified. The outer nuclear layer thickness and the neurosensory retinal thickness were decreased. The rabbits with euthanasia one week after the exposure showed higher decrease than the rabbits with an immediate euthanasia. No statistical changes were noted in the number of photoreceptors for any group. Moreover, active caspase-3 were more intense stained in the eyes of animals sacrificed one week after exposure than in controls or immediately sacrificed animals.
Conclusions: :
Oxidative stress is induced and early apoptosis mechanisms are starting caused by white light exposure. The retinal alterations found were not very severe even though the high intensity of the light exposure. This rabbit model of retinal light damage could be useful to test the possible protective effect of the new yellow intraocular lenses or antioxidant therapies for the retina.
Keywords: retinal degenerations: cell biology • lesion study • pathology: experimental