The effects of two stereoisomers of N-acetylcysteine on photochemical damage by UVA and blue light in rat retina

High doses of light can cause damage to the retina, e.g. during intraocular surgery. Previously, thiols have been demonstrated to protect against reti nal damage in various damage models. Such protection is very promising for clinical practice. Retinal light damage can be caused by a relatively short exposure to high irradiance levels. These conditions occur during intraocu lar surgery. In the current study we therefore investigated whether the thi ol N-acetylcysteine protects against retinal light damage under high irradi ance conditions in the rat retina. Two stereoisomers of this thiol were tes ted for protection against two spectrally defined types of retinal light da mage. Shortly after administration N-acetyl-L-cysteine in doses of 270-1000 mg/kg intraperitoneally protected against 380 mo (UVA) light but not again st 470 mo (blue) light. Two hours after injection the protection had dimini shed. We observed no protection by the stereoisomer N-acetyl-D-cysteine, Fr om this study we conclude that N-acetyl-L-cysteine protects stereospecifica lly against retinal damage in the UV but not in the visible part of the spe ctrum. This limits the possible applications.