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M. Rostkjaer, L. E. Johnson, L. Kessel; Electrophysiologial Changes After Acute Retinal Damage Induced by Blue Light. Invest. Ophthalmol. Vis. Sci. 2010;51(13):2252.
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Acute phototoxic damage by short wavelength light may occur as an unwanted side-effect when visualizing the retina for therapeutic purposes, such as during prolonged vitreoretinal surgery. Furthermore, phototoxic damage is believed to be a risk factor for the development of age-related macular degeneration. The purpose of the present study was to examine the electrophysiological changes over time after blue light induced acute retino-phototoxic damage in Brown Norway rats.
Male Brown Norway rats were exposed to a blue laser at 445 nm on one eye for 10 minutes. The time course of changes in retinal function and morphology was assessed weekly for 4 weeks using full-field electroretinography (ERG) with 30 min dark adaptation and funduscopy before the rats were euthanized and the eyes used for histology.
Acute effects were seen on the exposed eyes using scotopic ERG where amplitudes were severely reduced after phototoxic injury despite dark adaptation whereas photopic responses were only somewhat affected. One week after phototoxic injury scotopic ERG showed slightly decreased a- and b-wave amplitudes in exposed eyes when compared with unexposed, whereas no major differences were observed on the photopic ERG. This difference remained consistent for all following measurements up to 4 weeks after exposure. In parallell, funduscopic examination revealed white, edematous lesions immediately after damage. Four weeks post-injury, the lesions were barely visible macroscopically but a slight change in the pigmentation of the fundus was observed in the injured region.
Our results indicate that phototoxic retinal damage can be detected electrophysiologically immediately after exposure and that the ERG of the exposed eyes recovers to a plateau within a week. The action spectrum of phototoxic damage implies that the damage mechanism for short wavelength irradiation is related to the absorption by rhodopsin but we found no evidence of expansive damage to the photoreceptors as seen by ERG.
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