Ultrastructural alterations in rat and cat retina and pigment epithelium induced by chloroquine.

Chloroquine retinopathy in rats and cats was studied (in long-term experiments on rats the drug was injected into the stomach). We observed the slow development of the pathological process, accompanied by the appearance of membrane inclusions in GC, structural alterations in the RPE, and after 10 months complete destruction of the outer segments of the photoreceptors. In experiments on cats, after a single intravitreous chloroquine injection destruction of the photoreceptors, similar to that observed in rats, was found 2 weeks after the injection. In the region of tapetum nigrum containing melanin photoreceptors were safe. These data suggest the protective effect of melanin on the process of chloroquine retinopathy.