How Do People See Color If They Are Color Blind?

There are different types of color blindness, depending on which of the cones in the retina are affected. There are three types of cone cells: red cones, blue cones and green cones. If one of these is affected, that color is not seen as other people see it. Defects on the red or green cone cells are known as red-green color blindness and is the most common form.

How Color Blindness Occurs

• Color blindness is inherited from the mother and passed on in the X chromosome. Because of this, red-green color blindness mainly affects males. Some people acquire color blindness from illnesses or as a side effect of some medicines, or it may be the result of eye disease such as glaucoma or macular degeneration. There is no cure for the condition.

Dichromatism

• Dichromatism occurs when one of the cone cells is missing. If the red cones are absent, protanopia is the result, deuteranopia is when the green cones are missing and tritanopia is when the blue cones are absent. Milder forms of the condition where the cone cells are present but deficient in their function are called Protanomaly and Deuteranomaly.

Protanopia

• Protanomaly: colors seen as same.

  Protanopia affects one in 100 males. They have difficulty distinguishing between red, orange and yellow, and red may even be confused with black. Blue, violet, lavender and purple may all appear as shades of blue. In the milder form of protanomaly, red, orange and yellow may be seen as tending towards green.

Deuteranopia

• Deuteranomaly: colors seen as shades of red.

  Deuteranopia can affect five out of 100 males. In Deuteranomaly, the green cone cells are weak and green, yellow, red and orange are seen as shades of red. This is the most common form of color blindness. In the more severe form of Deuteranopia, red, yellow, orange and green all appear more or less the same hue.

Tritanopia

• This is the less common form of color blindness and can affect women as well as men because it is not carried on the X chromosome. They have difficulty with shades of blue, which may be seen as tending towards green.

Monochromatism

• Monochromatism: no color is seen.

  Monochromatism occurs when none or only one of the cone cell types is working properly. No color is seen, only shades of black or grey and white. This type of color blindness is rare.

How Color Blindness Affects Career Choices

• Most people can compensate for their loss of some color vision by, for example, recognizing a red traffic light by its position. However, some careers require accurate color vision and applicants are tested for color blindness when they apply. These include pilots, electricians, train drivers and positions in fashion or art departments where the ability to distinguish between shades of color is important.