2015 Volume 34 Pages 1-10
Electroretinography (ERG) is a useful method for the quantitative evaluation of retinal function. In the fields of clinical veterinary medicine and drug safety research, ERG has largely been evaluated according to the international standard protocol used in the human clinical field as recommended by the International Society for Clinical Electrophysiology of Vision (ISCEV) in recent years. In this study, we performed ERG on rabbits treated with sodium iodate (SI), a retinal toxicant, according to the ISCEV protocol using a Ganzfeld dome (Ganz) or a contact lens electrode with a built-in white light-emitting diode (LED), which provides full-field light stimulation. The studies were conducted in two different laboratories and the differences in ERG changes between the two light stimulations were compared. ERG included rod response (RR), combined rod-cone response (COR), oscillatory potentials (OPs), cone response, and 30Hz flicker response (FR). ERG with both Ganz and LED showed an increase or decrease in the amplitudes of the RR and b-wave of the COR at 3 h after dosing. At 8 h after dosing, these amplitudes increased with Ganz but decreased with LED. The latencies of all responses, except OPs, were prolonged or tended to be prolonged with both Ganz and LED from 3 h after dosing. The RR and FR disappeared at 48 h after dosing and the other responses disappeared at 96 h after dosing in the case of both Ganz and LED. Histopathological examination revealed sequential retinal changes from the pigment epithelial layer to the external granular layer in both the laboratories. These results suggest that ERG analyses using both Ganz and LED enable the early detection of the toxic effects of SI on the rabbit retinal function. There were no significant differences in ERG changes between the two light stimulations.
