Transmission electron microscopic observations of vitreous abnormalities in retinitis pigmentosa.

Ultrastructural studies of six vitreous biopsy specimens obtained during cataract surgery on patients with retinitis pigmentosa showed four types of cells. These were ocular pigment epithelium, uveal melanocytes, retinal astrocytes, and macrophage-like cells. The fibrous astrocytes displayed plump cell bodies, large nuclei, and numerous intracytoplasmic filaments. The pigment epithelial cells and uveal melanocytes were round to cuboidal and were heavily pigmented. Macrophage-like cells demonstrated round cell bodies, inclusions of glycogen, and long processes extending from the cell membrane. Also identified in the vitreous material were loose pigment granules. In contrast, vitreous from the control group showed occasional macrophages and loose pigment. These findings explained the clinical observation of material within the vitreous of patients with retinitis pigmentosa.