Electroretinography in the Non-Human Primate as a Standardized Method in Toxicology

Abstract

Electroretinogram traces including the five standard responses were recorded from 80 cynomolgus monkeys (Macaca fascicularis) under general anesthesia. First, after 30 minutes of dark adaptation, the scotopic ERG was recorded by seven measurements with increasing flash intensity from the rod threshold up to the maximal response to the standard flash of 2.6 cds/m². A standard rod response was elicited with flashes 2.6 log units below the standard flash. The oscillatory potentials were then measured at 0.4 log units above the standard flash. At the onset of light adaptation and 10 minutes thereafter, 30 Hz flicker responses were obtained with the standard flash in presence of background illumination. For the next photopic electroretinogram, three red flash cone responses were recorded with increasing flash intensity. The final photopic trace to be recorded was the single flash cone response with the white standard flash. Beyond the requirements of the Standard for Clinical Electroretinography, electroretinograms were also recorded during the course of the dark adaptation at 4 minute intervals. The results of the recordings performed in accordance with the Standard for Clinical Electroretinography and of the dark adapted electroretinogram correspond very well with the results obtained in humans. Thus, the cynomolgus monkey has proved to be an excellent animal model for testing retinal (dys)functions in toxicity assessment.