A Case of Unilateral Deuteranopia*

Abstract

Studies are reported of a subject with deuteranopia of the right eye and mild deuteranomaly of the left. On the Nagel anomaloscope this subject, using the right eye, matched both spectral red and spectral green to yellow. The left eye did not differ from normal on this test. Selected pseudo-isochromatic charts and the Farnsworth-Munsell 100-hue test, however, revealed, in the left eye, definite color deficiency of the deutan type. Scores on the color threshold tester indicated a marked defect in the right eye, slight in the left.Because of the relatively slight abnormality of the left eye it is possible to obtain reliable information as to the colors actually perceived by the deuteranopic right eye. Tests with the 100-hue series of Munsell papers and with a spectrometer showed that perception of red and green is entirely lacking. The Munsell papers were described as browns, grays, and blues. In the spectrum the range from 501 to 505 millimicrons was reported as white; longer wave-lengths were reported as yellow, shorter ones, as blue. The only regions of the spectrum identical in appearance to the two eyes were those wave-lengths chosen by the deuteranomalous left eye as unitary blue (451–453) and unitary yellow (584).