Deuteranomalous color matching in the deuteranopic eye.

Two observers were classified as deuteranopes by standard tests including two-degree anomaloscope matches. Color matching similar to the Rayleigh type was then carried out for a 10-degree field size at retinal illuminance ranging from 1 to more than 3000 trolands (td). The results show that at the larger field size and higher levels of retinal illuminance, a third independent color-mediating mechanism with the sensitivity of the deuteranomalous cone is participating in the color match. The results also confirm participation of a different third mechanism with rod sensitivity at levels below about 100 td. There is a range of transition between the two as the level increases above 100 td. Therefore large-field color matching in these deuteranopes is trichromatic at the levels tested, not dichromatic, and a third cone system is found to operate at typical photopic light levels under static viewing conditions in a dichromatic eye.