PURPOSE: To examine the histopathologic and morphometric features of neovascular lesions in human proliferative sickle cell retinopathy. METHODS: Postmortem ocular tissue was obtained from three subjects (aged 20, 28, and 40 years) with SS hemoglobinopathy and prepared for adenosine diphosphatase flat-embedding. Morphometric analysis was performed before serial sectioning. RESULTS: Numerous active and autoinfarcted lesions were found that represented virtually all stages in the life cycle of preretinal neovascularization. These formations ranged from single small loops extending from arteries and veins along the retinal surface to the typical complex, elevated sea fan formations. Sea fans developed at hairpin loops and at arteriovenous crossings. There was an average of 5.6 connections between sea fans and retinal vessels; of these, 45% were arteriolar, 52.5% were venular, and 2.6% were at the capillary level. Six of eight sea fans were located at arteriovenous crossings. Autoinfarction appeared to occur initially within the sea fan capillaries. The average height of sea fans was 123 μm above the retinal 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 configurations. 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.
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