Neuroprotective effects of different absorption filters: exploring macular degeneration in pigmented rats.

Abstract

PURPOSE: Visible light has a phototoxic effect on photoreceptors and retinal pigment epithelium cells. Short wavelengths are the most dangerous radiations of the visible spectrum. This study was designed to examine the neuroprotective role played by filters that short wavelengths of light in an experimental model of retinal phototoxicity in pigmented rats. METHODS: Famale Lister Hooded pigmented rats, 8 weeks of age, were used in a sequence of 3 experiments in which each group of animals was exposed to different light intensities, being 3086.67 lux the average in the first experiment and 2350 lux in the second one. For the third experiment it was employed a light intensity that oscilated between 700-800 lux, and what was adapted to the standard enviroment conditions of the city of Madrid (Spain); with an irradiance that varied from 1.48 w/m2 until 1.64 w/m2. FIlters that short wavelengths of different absorbance were used as much in second experiment as in the third one. The aimals were exposed to the light for 72 hours after having previously dilated the left pupil of each animal by instiling 1% atropine. The animals were sacrificed 1 or 7 days after light exposure and their retinas processed for microscopy. RESULTS: The light exposed retinas that has no protection or were protected at 5% with filters that short wavelengths, showed a nuclear density of 2-4 nuclei, while retinas exposed to light using filters that afforded a protection of 20% exhibited a nuclear density of 10-12 nuclei. This nuclear density was siilar to that recorded for control retinas, indicating a compensatory effect of these optic elements. CONCLUSIONS: Adapting the illuminance to the values of the eviroment standard conditions, filters of suitable optical density that short wavelengths of light protect retinal neurones, giving rise to similar nuclear densities to control retinas.