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Types of Color Blindness

Color blindness is a result of an abnormality in the eye’s photoreceptors called cones. A person who is color blind, or color deficient, has difficulty discerning between colors because of this. The human eye has three different types of cones that can be found in the retina:  the L-cones, M-cones and S-cones. Each of these cones is sensitive to red, green and blue, respectively. These cones, along with rods, help to transmit information to the brain upon receiving light.

Abnormalities among certain genes can cause a specific type of color blindness that can vary from mild to severe. The various types of color blindness are listed below:


Tritanopia a type of color blindness where the individual cannot discern between the blue and yellow colors. However, a person with Tritanopia has normal red and green color vision. About 1% of females and males have Tritanopia.

Red Green Color Blindness

Red green color blindness is the most common form of color deficiency, affecting about 6% of males. Individuals with red green color blindness have trouble discerning between shades of red and greenRed Green Colorblindness


Monochromatism is characterized by a complete lack of color vision and is referred to as either cone monchromasy or rod monochromasy. Individuals with rod monochromasy can only see black, white and shades of gray. Rod monochromasy can cause severe sensitivity to light and poor vision.

Cone monochromasy is when only one cone is present in the retina, either the blue, red or green one. Individuals with cone monochromasy can have decent vision in full light, but are still unable to differentiate colors.


Dichromatism is when only two of three cones are present in the eye’s retina.

  • Protanopia is the absence of the red cones, which causes an individual to confuse red and green.
  • Deuteranopia is the absence of green cones, which causes the sufferer to be insensitive to green shades and to perceive mainly blue and yellow colors.
  • Tritanopia is a type of dichromatism where there are no blue cones. Individuals with tritanopia have difficulty distinguishing between blue and yellow hues.

Anomalous Trichromatism

In anomalous trichromatism, all three cones are present but there is one that is deficient. The deficient cone causes an individual to perceive certain colors to a greater degree than others. The condition is less serious than in dichromatism, but similarly, either the red, blue or green cones can be affected.

  • Protanomaly is the deficiency of the red cones, which is most common and referred to as red green color blindness.
  • Deuteranomaly is the deficiency of green cones, which is most common and referred to as red green color blindness.
  • Tritanomaly is the deficiency of blue cones, which affects the appearance of blue and yellow colors.



March 21, 2021