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Color blindness

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Color blindness is the inability of a person to see certain color ranges. Color blindness is very common in males, approximately %10 of males are color blind while less than %1 of females are. It is more common than the AB blood type.[1] It is important to note that when some one is color blind that does not mean they cannot see any color. Color blind people can recognize several different colors. However, a color blind person may have trouble differentiating between certain colors in a specific range. The colors that an individual has trouble seeing are different depending on the type of color blindness that person has.


There are several different types of color blindness. The first differentiation is between congenital and acquired. Congenital color blindness is when a person is born with an abnormality of the cone photo receptors in the eye. Most color blindness is congenital and genetic. Acquired color blindness refers to color blindness that develops after birth. It can be caused by several things including injuries to the eye, nerves, or brain, eye disease, or aging. Color blindness is further divided into several types based on the range of color the individual can see.[2] These are:

  • Anomalous Trichromacy - A mild shift in the appearance of some colors
    • Protanomaly - shades of red appear weaker in depth and brightness. %1.3 of males, %0.02
    • Deuteranomaly - shades of green appear weaker.  %5 of males, %0.35 of females
    • Tritanomaly - very rare case where shades of blue appear weaker  %0.01 of both males and females
  • Dichromacy - Great deficiency or missing completely one of the cones
    • Protanopia - shades of red are greatly reduced or not present. %1.3 of males, %0.02 of females
    • Deuteranopia - shades of green are greatly reduced or not present.  %1.2 of males, %0.01
    • Tritanopia - very rare case where shades of blue are greatly reduced or not present.  %0.001 of males, %0.03 in females
  • Monochromatism - Inability to see any color.  %0.0001 of both males and females


References

  1. http://jfly.iam.u-tokyo.ac.jp/color/
  2. http://psychology.ucalgary.ca/pace/VA-Lab/colourperceptionweb/congenital.htm