The chromaticity confusions characteristic of tritanopia may be represented on the (x, y)-chromaticity diagram by a family of straight lines intersecting at a copunctal point near the shortwave extreme of the spectrum locus. A case of congenital tritanopia is reported that departs from typical tritanopia, first by having a luminosity function abnormally curtailed on the shortwave end, second by having chromaticity confusions among object colors describable by straight lines on the (x, y)-plot intersecting in an area surrounding the spectrum locus at 460 mµ instead of near the shortwave extreme, and third by confusing incandescent lamp light at a color temperature of 2900°K with the spectrum at 586 mµ instead of the typical tritanopic value of 579 mµ. It has been found that all three of these disagreements with typical tritanopia are to be expected from a tritanope possessing normal macular pigmentation combined with an ocular pigment five times normal. We believe, therefore, that this case of atypical tritanopia departs from typical tritanopia because of abnormally heavy ocular pigmentation.
DEANE B. JUDD, LORENZO PLAZA, and DEAN FARNSWORTH, "Tritanopia with Abnormally Heavy Ocular Pigmentation," J. Opt. Soc. Am. 40, 833-841 (1950)