Effect of exposure to 2,5-hexanediol in light or darkness on the retina of albino and pigmented rats. II. Electrophysiology.

Albino (Sprague-Dawley) and pigmented (Norwegian Brown) male rats were exposed to 2,5-hexanediol (H; 1%) in their drinking water for 5 or 8 weeks, respectively. Half of the rats of each strain were housed in light (average 30 cd/cm2 inside cage, 12 h/day); the other half was kept in constant darkness. Control groups were studied in parallel under identical conditions but without H. Electrophysiological recordings were made 2-5 days and 13 weeks after the end of the exposure to H. Alterations in the visual system, as measured by electroretinography and visual evoked response, were found in groups of albino rats exposed to H and/or light. The pupillary diameter was enlarged in the albino group exposed to both H and light. Among the pigmented rats, alterations were recorded only in the visual evoked response of the H exposed groups. The results demonstrate that simultaneous exposure to H and light can lead to alterations in visual function that are more severe than those induced by each agent alone, and may exceed a simple summation.