Feline central retinal degeneration.

Seven domestic cats with feline central retinal degeneration (FCRD) were investigated by ophthalmoscopy, fluorescein angiography, electroretinography, and light and electron microscopy. Little or no increase in lesion size was observed ophthalmoscopically over periods as long as four years. Five cats showed normal rod electroretinographic (ERG) responses and abnormal cone responses. In one cat both rod and cone responses were abnormal and in one cat neither rod nor cone responses were abnormal. Electron microscopic studies of one cat with an abnormal cone ERG showed outer segment lamellar disorganization in cones outside of the focal lesion. In the FCRD-affected cat with no ERG abnormalities, ultrastructure of cones outside the focal lesion was normal. Fluorescein angiography did not demonstrate abnormalities of apparent etiologic significance.