Residual bodies in the retinal pigment epithelium induced by intravitreal netilmicin

Intravitreal injection of aminoglycoside antibiotics is known to induce morphological changes in the retinal pigment epithelium (RPE) resembling a lipidosis. The RPE of netilmicin-treated rabbits displays a dose-related increase in autofluorescence compared to untreated controls. Netilmicin produces an accumulation of membrane-limited osmiophilic lamellated inclusions in the pigment epithelial cell. These inclusions measure from 1 to 3 microns in diameter, and have acid hydrolase activity demonstrated by cytidine monophosphate cytochemistry. These findings suggest that netilmicin-induced inclusions are residual bodies and that the accumulation of these residual bodies is responsible for the observed cellular lipidosis.