ABSTRACTColor vision loss can be an early sign of eye disease; in many retinal disorders the loss precedes any change in visual acuity. Nonin-vasive psychophysical methods allow factoring out of preretinal, receptoral, and postre-ceptoral (neural) components of the color vision change. A loss of chromatic but not achromatic sensitivity occurs for diabetics; the loss is selective for pathways subserving blue-sensitive photoreceptors. Both chromatic and achromatic pathways are altered in glaucoma and senile macular degeneration; the most marked change in central serous choroido-pathy is loss of sensitivity somewhere in the blue-sensitive cone pathway. There is evidence that the pathways subserved by blue-sensitive cones have anatomically and physiologically different properties from those served by other receptor types, and they appear particularly vulnerable to disturbances of retinal integrity.