Talc retinopathy in primates: A Model of Ischemic Retinopathy: I. Clinical Studies

Four rhesus monkeys received intravenous injections of talc twice weekly for 3½ to ten months. Within one month, talc particles were visible in fine perifoveal retinal vessels in the posterior pole. Continued deposition of talc could then be seen after subsequent injections. Hemorrhages in the nerve fiber layer, cotton-wool patches, and whitish plaques in the choroid were visible ophthalmoscopically. Fluorescein angiography revealed precapillary arteriolar occlusions, capillary nonperfusion, an abnormal foveal avascular zone, and retinal vascular leakage. Vitreous fluorophotometric findings were abnormal in all five eyes tested, while electroretinograms were normal in two eyes with advanced talc retinopathy. Talc retinopathy in the primate is similar to ischemic retinopathies in humans, including human talc retinopathy, sickle cell retinopathy, and hypertensive retinopathy. Subsequent reports will describe the light microscopic and ultrastructural changes in these eyes using tracer studies with horseradish peroxidase.