ELECTRORETINOGRAM RECOVERY IN THE RABBIT AFTER REPETITIVE SHORT-TERM ISCHEMIA IN LIGHT AND DARK

Purpose. To determine the time course and reproducibility of electrore tinogram recovery after short-term (5- to 20-minute) retinal ischemia in the light and in the dark. Methods. Electroretinogram recovery was measured in Dutch rabbits after 5-, 10-, or 20-minute episodes of ocul ar ischemia, repeated three times at 1-hour intervals. Results were co mpared under light- and dark-adapted conditions. Results. The rate of b-wave recovery was highly reproducible after repetitive ischemic insu lts in the same eye. The rate of b-wave recovery varied in proportion to the duration of ischemia but generally reached 100% of preischemic levels within 45 to 60 minutes. Recovery was slower under dark-adapted conditions than under light-adapted conditions, and 10 minutes of isc hemia appeared to be a critical duration to maximize light- and dark-a dapted metabolic differences. Conclusions. Because of the speed and re producibility of electroretinogram recovery, the use of short-term isc hemic episodes may facilitate studies on the pharmacologic therapy of retinal ischemia. It remains to be determined, however, whether the re tinal effects of short-term ischemia are mediated by the same mechanis ms as the effects of longer-term ischemia.