The red and green cone visual pigments of deuternomalous trichromacy.

Abstract

Three simple deuteranomalous trichromats matched with abnormally low red tristimulus values throughout the spectrum and abnormally high green tristimulus values in the long wave end of the spectrum which become normal (and then low) in the yellow-green. The spectrum locus of this transition differed from 1 anomalous to the other. Differences in the matches of 2 of these could not be due to differences in eye media transmissivities alone. Therefore these 2 deuteranomalous had different cone visual pigments. The analytical anomaloscope was used in the confrontation of 1 deuteranomalous with 6 deuteranopes in turn. In each confrontation the deuteranope set the anomaloscope in his mode and adjusted the intensity of the monochromatic light for a match. Deuteranomalous matches were rejected by 4 of these 6 deuteranopes. They were accepted by 2 of the 6. These 2 rejected each other''s matches in a way not attributable to differences in eye media transmissivity. Three different psychophysical techniques were used to measure the action spectra of the long wave cones of these 2 deuteranopes. All 3 methods reveal small but systematic differences in .lambda.max [wavelength of maximum absorption] and shape of the curve for the 1 deuteranope compared with that of the other. In the red-green spectral range, these spectra were accurately described by different linear combinations of the color matching functions of the same deuteranomalous whose matches the 2 deuteranopes accept. Linear combinations of those of a 2nd deuteranomalous, with at least 1 different kind of cone, fit less well. The wavelength discrimination curve of the former deuteranomalous was measured with a new method. The curves of 2 normals were also obtained for comparison. Wavelength discrimination predictions from the Stiles line element theory were compared to the anamalous curve. The deuteranopic action spectra were used in the line element to compute this deuteranomalous'' discrimination. There was reasonable 1st order correspondence between prediction and observation, but the prediction was sensitive to small changes in the derivatives of the logarithms of the action spectra. Line element prediction of the deuteranomalous step-by-step luminous efficiency curve was insensitive to such uncertainties. The agreement with expectation from the above assumptions and the measured step-by-step deuteranomalous luminous efficiency curve in the red-green part of the spectrum was therefore good. The erythrolabe in 1 deuteranope''s long wave cones apparently has the action spectrum of this deuteranomalous'' long wave cones and the erythrolabe in the other deuteranope''s long wave sensitive cones has that of this deuteranomalous'' medium wave cones. A general hypothesis about the nature of all forms of red-green color vision defects transmitted recessively on the X chromosome was discussed.