Lipoidal degeneration of the retinal pigment epithelium.

Vacuolation of the retinal pigment epithelium in the foveomacular region of aging rhesus monkey eyes was re-examined with the eyes initially fixed in osmium tetroxide to retain the alcohol-soluble lipid. All vacuoles were found to be completely occupied by lipid material. Similar cells were positive to oil red O. The vacuolation of the pigment epithelial cell is considered to be a form of lipoidal degeneration.