The Characteristics of Tritanopia

The paper describes how contact was made with a number of tritanopes through an article published in Picture Post, an illustrated weekly English journal. Seventeen cases of tritanopia were tested and confirmed at the Imperial College, London, and of these, seven made detailed observations on the author’s colorimeter. The measurements included the relative luminous efficiency of monochromatic radiation through the spectrum (the luminosity curve), the dichromatic spectral coefficient curves, the spectral mixture curves, the tritanopic confusion loci in the C.I.E. chromaticity chart, and the wavelength discrimination curve. The results support the theory that tritanopia is due to the absence of blue receptors, although the location on the chromaticity chart of the fundamental stimulus associated with the blue process has not yet been determined with precision. From the readership statistics of Picture Post and from an analysis of the correspondence received as a result of the article, it is estimated that the incidence of tritanopia lies somewhere between 1 person in 13,000 and 1 in 65,000, and that the ratio of men to women tritanopes is of the order of 1.6 to 1. The transmission of the defect appears to differ from that found for protanopia and deuteranopia.I should like to express my very warm appreciation of the honor which the Optical Society of America has conferred on me in inviting me to give the 1952 Adolph Lomb Memorial Lecture. The work described below has itself involved a degree of Anglo-American cooperation which has given me great pleasure, and the invitation to give this lecture is a further indication of the cordial relationship between optics research in our two countries. I am glad, too, to be linked in this way with Adolph Lomb, if for no other reason than the important part which I understand Mr. Lomb played in securing the English translation of Helmholtz’s Physiological Optics. The subject of this lecture stems very directly from some of the problems discussed in that great treatise.