COMPLEMENT-INDUCED RETINAL ARTERIOLAR OCCLUSIONS IN THE CAT

Purpose: To develop an animal model of complement-induced retinal vasc ulopathy and determine whether it resembles Purtscher's retinopathy. M ethods: Intravenous cobra venom factor was used to achieve intravascul ar activation of the complement system in cats. After a single bolus o f cobra venom factor (75 units/kg), retinal blood flow was monitored a t regular intervals by fluorescein angioscopy and angiography. Results : Multiple small retinal arteriolar occlusions were present during the initial fluorescein transit of the immediate postinjection fluorescei n study in 12 of 12 animals. Small, rapidly moving gaps in the fluores cein column were seen in two thirds of the animals observed continuous ly by fluorescein angioscopy. Angiographically, the obstructions were transient, and filling of the associated patches of capillary nonperfu sion occurred within 3 minutes. Purtscher's-like ischemic retinal infa rcts did not develop in any eye, Histopathologic analysis failed to de monstrate the nature of the transient vascular obstructive lesions, bu t indirect evidence suggested the possibility of granulocyte aggregate s. Conclusion: Intravascular activation of the complement system produ ces transient microembolic retinal arteriolar occlusions in the cat. A lthough this model may represent a mild form of Purtscher's retinopath y, factors in addition to complement activation appear necessary to in duce ischemic retinal infarcts.