anomaloscope(redirected from Pickford-Nicholson anomaloscope)
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an apparatus used to detect anomalies of color vision.
An instrument used to diagnose abnormalities of color perception in which one half of a field of color is matched by mixing two other colors.
[G. anōmalos, irregular, + skopeō, to examine]
anomaloscope(ă-nom′ă-lŏ-skōp″) [ anomaly + -scope]
A device used to assess color perception (color blindness). The patient is asked to adjust red and green lights to match another color, e.g., a yellow light.
An instrument for testing colour vision in which the observer is required to match one-half of a circular field which is illuminated with yellow with a mixture of green and red in the other half. The yellow half can be varied in brightness, while the other may be varied continuously from red to green. A certain combination of the red and green mixture is considered normal, and variations from that mixture indicate anomalous colour vision. With this instrument one can distinguish between a protanope and a protanomal and between a deuteranope and a deuteranomal. Syn. Nagel anomaloscope. Some anomaloscopes also test for blue-yellow colour vision deficiencies, e.g. Pickford-Nicholson anomaloscope. See defective colour vision; Rayleigh equation.