What are color vision deficiencies? How common are they?
Color vision deficiencies result from either a lack of one or more cone types, or cones that behave somewhat differently from average. Those lacking long wavelength cone pigment suffer from protanopia. A related condition is anomalous protanopia, or protanomaly. Here, long wavelength cones are present, but their sensitivity is shifted spectrally to shorter wavelengths, so they interpret certain stimuli differently than normal observers. Similarly, deuteranopia (deuteranomaly) is the lack (spectral shift to longer wavelengths) of the middle wavelength cone pigment, and tritanopia is the lack of short wavelength cones (tritanomaly is incomplete tritanopis). It is important to remember than none of these conditions should be referred to as true color blindness. This is not simply a politically correct statement. In fact, those suffering from any of these conditions do experience color, but not in the sense that a color “normal” observer does. Other less-common deficiencies are rod monochr
