A histopathologic study of retinitis pigmentosa

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Abstract
The ultrastructural features of the retina in two cases of X-linked recessive and one of autosomal dominant retinitis pigmentosa are described. Histopathologic changes were most apparent in the retinal pigment epithelium (RPE), photoreceptor cells, and retinal vessels. the RPE was foeally absent, focally proliferated, and mostly depigmented. Thickening of the basal membrane of the RPE was present. Photoreceptors were severely reduced in number. Two forms of photoreceptor cell degeneration were observed. In the first form the photoreceptor cells exhibited mitochondrial swelling, wateriness of cytoplasm, and loss of organelles. In the second form the cells showed densified, shrunken cytoplasm with vacuolated mitochondria. In many retinal vessels, endothelial cell and pericytic degeneration were apparent. Pigment-laden macrophages were present in all layers of the retina. A preretinal membrane was observed in the posterior pole of all six eyes and consisted of cellular elements bearing the ultrastructural characteristics of smooth muscle cells. the preretinal membrane may account for the retinal vascular leakage observed in some cases of retinitis pigmentosa.