The effects of N-acetylcarnosine (NAC)-contained eye drop ‘Clarastil’ on a model of adrenaline-induced high intraocular pressure (IOP) in Wistar rats were studied. The retina ultrastructure and markers of oxidative stress have been studied. NAC was found to have no significant effect on edema in the retinal ultrastructure, did not reduce endothelial thickening and histogemic barrier, and accordingly did not affect the value of IOP after prolonged adrenaline administration. However, the introduction of the eye drop prevented the swelling of the mitochondria, the formation of vacuolated crystals and probably stimulated energy production as a compensatory mechanism under conditions of hypercatecholemia. In addition, NAC significantly reduced adrenaline-induced overproduction of reactive oxygen species and lipid peroxidation products in eye tissues, indicating its antioxidant effect.