anomalous trichromatism

a form of color blindness or color weakness in which affected individuals have three types of retinal cone but one of these has a color sensitivity that is different from that of the corresponding normal cones. It is usually marked by a diminished capacity to respond to the red–green color system. The ability to distinguish these colors increases in proportion to their intensity; that is, less brilliant shades are less easily identified. Also called anomalopia; anomalous trichromasy.