Photocoagulation Does Not Ablate Angiogenic Markers in Rabbit Retina

Abstract

Panretinal photocoagulation (PRP) in rabbits produces treatment areas consisting of destroyed outer retina and intact inner retina separated by areas of normal-appearing retina. Intravenous iodoacetate produces widespread destruction of the outer retina with sparing of the inner retina, approximating total, confluent PRP. After PRP (at three weeks), intravenous injection of iodoacetate (at three weeks or four months), and in control rabbits, eyes were harvested and retinas were homogenized in a balanced salt solution. Retinal homogenates were measured for three markers of angiogenic activity: vascular endothelial cell migration, proliferation, and production of plasminogen activator. Retinas subjected to PRP or intravenous iodoacetate (at three weeks or four months) stimulated migration and proliferation above baseline levels twice as much as control retinas and stimulated plasminogen activator production by twofold to 2.5-fold. These data suggest that PRP does not eliminate the ability of the retina to produce angiogenic activity, but rather exerts its antiangiogenic effect in an indirect fashion.