Electroretinographic assessment of early retinopathy in rats.

Amoscanate, a substance which damages photoreceptors, was administered orally to Wistar rats in doses of 10, 40, and 125 mg/kg body weight once daily for 3 or 10 days. At both times electroretinographic, ophthalmological, and histopathological examinations of the retina were carried out to compare the sensitivity of conventional methods and to test electroretinography (ERG) for suitability for use in toxicity studies. Time-dependent and dose-dependent effects were found by electroretinography and light microscopy. However, signs of retinal changes appeared earlier and more distinctly in the electroretinogram. Ophthalmological fundus examination in albino rats yielded no characteristic correlate. In conclusion, electroretinography constitutes a valuable supplement to histopathology and is suitable for use in toxicity studies.