Color Vision Deficiency

aka Color Blindness

What is color blindness?

Definition: The inability or decreased ability to see color, or perceive color differences. It is a single gene mutation.

Who first discovered/reported having color blindness?

Scientist John Dalton realized in 1794 that he mixed up red with green and pink with blue. He decreed in his will that after his death, his eyes should be examined to see what made this so. It was discovered that he was missing the OPN1MW gene in his retinas, which made him have deuteranopia.

Deuteranopia and Protanopia

Deuteranopia is the official name for the red form of color blindness. Protanopia is the name for the green form. Those affected cannot see the color red, and/or the color green. This also changes how affected people see other colors that have components of red or green, such as purple. These two forms are incredibly similar in terms of the visible spectrum. There are no other side effects of these deficiencies. Both of these forms, when inherited, have NO effect on life expectancy.
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Rainbow: Normal vs. Protanopia/Deuteranopia

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Visible Color Spectrum: Normal vs. Deuteranopia


Tritanopia is the official name for the blue/yellow form of color blindness. Individuals with tritanopia cannot see yellow at all, and struggle to perceive depth in blue. Thus, orange is the same as red to them, green is a light blue, and purple is a dark red. There are no other side effects of this defect. This form of color blindness has no effect on life expectancy when inherited.
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Visible Spectrum of Color: Normal vs. Tritanopia

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Tritanopia Rainbow

Inheritance of Red and/or Green Color Blindness (Deuteranopia/Protanopia)

Color vision deficiencies are sex-linked traits, specifically on the X chromosome. People with red/green color blindness have mutations on the OPN1LW (opsin 1, long wave sensitive) and OPN1MW (opsin 1, medium wave sensitive) genes. The OPN1LW gene controls the cone pigments in a person's eye that respond to yellow/red light. The OPN1MW gene controls the cone pigments that respond to yellow/green light. This leads to the affected person not seeing the green component in blue, or the red component in purple.

As this trait is passed down through the X chromosome, fathers cannot pass this to a son. It is also more common in boys, as the mutation only has to occur on 1 X chromosome, as opposed to 2 in girls. Numerous studies have shown that red/green color blindness affects 1 in 12 boys of Northern European ancestry and 1 in 200 girls of Northern European ancestry.

Inheritance of Blue/Yellow Color Blindness (Tritanopia)

People who are affected by blue/yellow color blindness have a mutation on their OPN1SW (opsin 1, short wave sensitive) gene. The OPN1SW gene controls the cone pigments that sense blue/violet light. This form of color blindness affects 1 in 10,000 people, with no difference between race or gender.

Diagnostic Tests

Ishihara Test

The Ishihara test is a process used to diagnose red/green color blindness, named after its creator, Dr. Shinobu Ishihara. It consists of 24 pseudoisochromatic plates made up of multicolored dots, in which numbers and lines are constructed out of colors. Some plates, known as transformation plates, construct 1 number based on color (usually red or green) and another based on the depth of a single color. This makes it so that color blind people see one number, and those with normal color vision see a completely different number.

Other plates, known as vanishing plates, contain figures that only those with good color vision can see. Hidden digit plates are plates where only colorblind people can see the figure shown. Classification plates determine whether a colorblind person is red colorblind or green colorblind. Two numbers are on the plate, and they are different colors. Someone with normal color vision can see both digits, where a red/green colorblind person can only see one or the other.


The most accurate and precise test to determine the presence and severity of color vision deficiencies, the anomaloscope, uses color matching to conduct its test. Most use the Rayleigh match (combination of red and green light) matched with yellow light. Due to the way people with protanopia and deuteranopia perceive red and green, they will add more or less of each colored light to create a color match. For example, those with protanopia will use more red in their match, and those with deuteranopia will use more green. To test for tritanopia, the Moreland match (blue/green) is utilized.


There is no complete cure available for inherited color blindness, but some brightness enhancement technology may help with some symptoms. Some special glasses and/or contact lenses change the brightness perceived for certain colors, but the user is still unable to actually see those colors. The lenses are mainly for distinguishing different colors.

Soon, however, those with genetically inherited color blindness may be able to find a cure. Scientists are working on one now! Hopefully, this new treatment will debut shortly.

*NOTE*: If the color blindness is caused by another condition, such as diabetes or Alzheimer's, then treating the underlying condition may help with treating the color blindness.

Report completed by Hannah Peacock