Ultrastructural changes of the rabbit retina following methohexital anaesthesia.

The effect of methohexital on retinal ultrastructure was studied. In spite of the negligible decrease in arterial blood pressure and the significant decrease in intraocular pressure, retinal cells showed hypoxic alterations after anaesthesia. This indicates that the protective effect of barbiturates against brain hypoxia fails to manifest in the retina. Therefore, in ophthalmological patients, application of methohexital without O2 inhalation and respiratory stimulation, is not recommended. Numerous reports have been published on the ophthalmological complications of anaesthesia. These were thought to be due to hypoxic cerebral lesions. In our previous studies almost all intravenously applied anaesthetics were found to produce fine structural changes in the retina which appeared to be independent of the general effect. As barbiturates are the most frequently used intravenous anaesthetics, the effects of these compounds have been studies. This paper is an account of retinal alterations observed after the application of methohexital, an anaesthetic of ultrashort action.