Maculopathy in cynomolgus monkeys. A correlated fluorescein angiographic and ultrastructural study.

Maculae of seven cynomolgus macaque monkeys (Macaca fascicularis) showing abnormalities in color fundus photographs and fluorescein angiograms were studied in serial sections by light and electron microscopy and compared with three eyes without clinically visible defects in the macula. Maculae that showed hyperfluorescent nonleaking window defects showed no drusen or interruptions in the retinal pigment epithelium (RPE). Six of these monkeys had mis-shapen foveal depressions, all showed some degree of photoreceptor degeneration, and one had cells in Bruch's membrane. Bright yellow spots correlated with scattered RPE filled with lipid vacuoles. Shallow RPE elevations correlated with diffuse nonleaking window defects. Patches of RPE deficient in melanin occurred at sites of hyperfluorescence. Quantitative studies showed that maculae with window defects had more lipofuscin and less melanin per RPE cell. Maculae deemed normal by photography showed degenerating photoreceptors.