[Animal experiment studies of the ocular toxicity of cardiac glycosides]

The addition of different types of cardiac glycosides (strophanthin, digoxin, digitoxin) to the perfusion medium of isolated cat eyes, kept alive by extracorporeal perfusion, leads to changes in ERG. There is a dose-dependent reduction of the b-wave amplitude in scotopic and photopic electroretinogram (ERG). At the same time the implicit time of the potentials increases. In the scotopic-isolated P III component, both amplitude and implicit time increase. The concentrations inducing ERG changes that are fully reversible after cessation of drug application correlate well with the known toxic drug blood levels in humans. The disappearance rate of the drug induced effects was almost equal under these conditions (extracorporeal perfusion) for the different glycosides. In conclusion, our results indicate that at least part of the visual symptoms of glycoside intoxication are already evident at the retinal level.