Subjective Spectrum of Colour Sensation in Colour Defectives

Abstract

Twenty-two cases of trichromats as diagnosed by conventional technique were subjected to spectral examination in which their colour sensation in reference to wavelength in the continuous spectrum of incandescent daylight lamp was determined.Of the 22 male cases, one possessed a spectrum consisting of two principal colour zones, “yellow” and “blue”, i. e. dichromic in the terminology of Edridge-Green. Four proved to be tetrachromic with red, yellow, greeri and blue, or red, “orange”, blue and violet. Another four were pentachromic with red, orange, yellow, green and blue (three case), or red, “violet”, yellow, green and blue (one case). Remaining 13 cases were hexachromic with red, orange, yellow, green, blue and violet. It was then inferred that all eyes, even the dichromic were able to make out yEllow and blue ift the spectrum.Wave-length range of each discriminated principal colours varied from case to case. Inter-lateral difference was also present, although in a lesser extent A most markei characteristic common to all cases examined was deviation with expansion of the yellow range.In 4 cases among the hexachromic, point of transition between yellow and green was labile, showing fluctuation. In a case apparently normal in colour distribution in the spectrum on the first glance, yellow range expanded toward green, at a partial sacrifice of the latter in a few seconds. Four cases showed the reverse condition. Chromic feature of their spectrum at first was anomalous with an expanded yellow zone. When the gazing was continued a few seco id, the transition point between yellow and green shifted toward yellow side. Anomalous arrangement of the subjective spectrum thus resulted.As for subjective luminosity, 17 eyes out of 44 (22 cases) were reported to have two summit distribution.Twenty-nine eyes of 44 is reportei to have an unsaturated zone in the spectrum. It is generally situated in the neighbourhood of 500±5mμ.Some of the cases here reported, when subjectied to examination with an anomaloscope, showed a typical dichromatic pattern, while they were often found polychromic by direct spectroscopic examination, or more than two principal colour zones were differentiated.