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The b-Wave of the Electroretinogram as an Index of Retinal Ischemia*

1998; Elsevier BV; Volume: 30; Issue: 3 Linguagem: Inglês

10.1016/s0306-3623(97)00359-5

1879-0011

F. Block, Martin Schwarz,

Photoreceptor and optogenetics research

The b-wave of the electroretinogram (ERG) is a particularly sensitive index of retinal ischemia. The present paper summarizes the changes in the b-wave observed in five in vivo models of retinal ischemia. Although the amount of reduction in b-wave amplitude during ischemia corresponds to the severity of the insult, the degree of recovery of the b-wave during reperfusion depends on the duration of ischemia. A massive release of glutamate, intracellular overload with calcium and enhanced production of free radicals are suggested to be three major pathophysiological processes that contribute to retinal ischemic damage. The b-wave of the ERG represents a functional measure for potential therapeutic efficacy of drugs interacting with these pathophysiological processes. Several glutamate antagonists, such as MK-801, memantine, flupirtine or GYKI 52466, along with the free radical scavengers vitamin E, lipoate, superoxide dismutase and catalase, all reduce the depression of the b-wave during ischemia or accelerate the recovery of the b-wave during reperfusion or both. The calcium channel antagonists nimodipine and levemopamil exert only a slight beneficial effect on the recovery of the amplitude of the b-wave during reperfusion, provided that the blood pressure is not potently reduced.