Recovery of retinal pigment epithelial function after ischemia in the rabbit.

Survival of the rabbit retinal pigment epithelium (RPE) after ischemia was studied. The ischemia was induced by elevating intraocular pressure; retinal and RPE function were monitored by electrophysiologic recordings. The b-wave recovered to control amplitude in 1-4 hr after 30-60 min of ischemia, but it never recovered more than about 50% amplitude after 90 min of ischemia. The c-wave recovered after 30 min of ischemia but was replaced by a negative response after 60-90 min of ischemia. The RPE hyperosmolarity response was normal after 60 min of ischemia, but it was severely depressed after 90 min of ischemia. The RPE response to acetazolamide (cornea positive in the rabbit) was lost after both 60 and 90 min of ischemia. These results suggest that different components of RPE function have different tolerances to ischemia and is consistent with evidence that the RPE electrophysiologic responses differ in mechanism and response to disease.