Exudative retinal detachment after photodynamic injury.

Exudative retinal detachments occur in a variety of retinal and choroidal diseases. We created serous retinal detachment in the cat eye by means of photodynamic injury produced by activation of intravascular rose bengal using filtered, focused light (550 nm). Fluorescein angiography later revealed focal retinal and choroidal vascular occlusion surrounded by a larger area of leakage through the pigment epithelium. Serous retinal detachments occurred rapidly, gradually enlarged over the next 3 days, and resolved in all eyes after 14 to 21 days. Histopathologic and ultrastructural features of early lesions included the accumulation of proteinaceous fluid in the subretinal space, pigment epithelial cell damage, and localized occlusion of retinal vessels and the choriocapillaris. Later changes consisted of limited regeneration of the retina and portions of the tapetum. In several respects, these experimental detachments resemble the serous retinal detachments associated with choroidal ischemia in humans, and may serve as a useful model in the study of choroidal microvascular hypoperfusion.

Photochemical initiation of thrombosis. Fluorescein angiographic, histologic, and ultrastructural alterations in the choroid, retinal pigment epithelium, and retina.

A new method of producing vascular occlusion, photochemical activation of intravenously injected rose bengal, was used to produce experimental thrombosis of the preretinal and choroidal blood vessels in rabbit eyes. Fluorescein angiography and light and electron microscopy were used to describe the resultant pathologic alterations over time. As early as one hour after treatment, the endothelium of both preretinal and choroidal blood vessels was severely damaged or completely obliterated, and platelet aggregates occluded the vascular lumina. Occlusion of the preretinal and choroidal blood vessels persisted for up to three days; however, endothelial regeneration and reperfusion had occurred in both vascular beds by seven days. In addition, the retinal pigment epithelium and myelin wings suffered ischemic damage. The retinal pigment epithelium began to recover by seven days, but the myelin wings appeared to be irreversibly damaged.