HISTOPATHOLOGIC FEATURES OF NEOVASCULARIZATION IN SICKLE-CELL RETINOPATHY

PURPOSE: To examine the histopathologic and morphometric features of n eovascular lesions in human proliferative sickle cell retinopathy. MET HODS: Postmortem ocular tissue was obtained from three subjects (aged 20, 28, and 40 years) with SS hemoglobinopathy and prepared for adenos ine diphosphatase flat-embedding. Morphometric analysis was performed before serial sectioning, RESULTS: Numerous active and autoinfarcted l esions were found that represented virtually all stages in the life cy cle of preretinal neovascularization. These formations ranged from sin gle small loops extending from arteries and veins along the retinal su rface to the typical complex, elevated sea fan formations. Sea fans de veloped at hairpin loops and at arteriovenous crossings, There was an average of 5.6 connections between sea fans and retinal vessels; of th ese, 45% were arteriolar, 52.5% were venular, and 2.6% were at the cap illary level, Six of eight sea fans were located at arteriovenous cros sings, Autoinfarction appeared to occur initially within the sea fan c apillaries. The average height of sea fans was 123 mu m above the reti nal surface. CONCLUSIONS: Preretinal neovascularization in sickle cell retinopathy can arise from both the arterial and venous sides of the retinal vasculature and can assume a variety of morphologic configurat ions, Multiple feeding arterioles and draining venules are common, and autoinfarction appears to occur initially at the preretinal capillary level rather than at feeding arterioles. Arteriovenous crossings may be a preferential site for sea fan development.