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What causes color blindness?

Color deficiency or colorblindedness is an inherited condition. It is caused by a common X-linked recessive gene. It is usually passed from mother to son. Disease or injury that damages the optic nerve or retina can also cause loss of color deficiency.


Color vision is possible due to photoreceptors in the retina of the eye known as cones. These cones have light-sensitive pigments that enable us to recognize color. Found in the macula (the central part of the retina), each cone is sensitive to either red, green or blue light (long, medium or short wavelengths).

The cones recognize these lights based on their wavelengths. Normally, the pigments inside the cones register different colors and send that information through the optic nerve to the brain. This enables us to distinguish countless shades of color. But if the cones don't have one or more light-sensitive pigments, they will be unable to see all colors.

Red-blue, blue-yellow deficiencies

Most people with color vision deficiency can see colors. The most common form of color deficiency is red-green. This does not mean that people with this deficiency cannot see these colors altogether, they simply have a harder time differentiating between them, which can depend on the darkness or lightness of the colors.

Another form of color deficiency is blue-yellow. This is a rarer and more severe form of color vision loss than just red-green deficiency because people with blue-yellow deficiency frequently have red-green blindness, too. In both cases, people with color-vision deficiency often see neutral or gray areas where color should appear.


People who are totally color deficient, a condition called achromatopsia, can only see things as black and white or in shades of gray. Color vision deficiency can range from mild to severe, depending on the cause. It affects both eyes if it is inherited and usually just one if it is caused by injury or illness.


There is no cure for inherited color deficiency. Organizing and labeling clothing, furniture or other colored objects (with the help of friends or family) for ease of recognition. Remembering the order of things rather than their color.

Color vision deficiency can be frustrating and may limit participation in some occupations, but in most cases, it is not a serious threat to vision. With time, patience and practice, people can adapt.

If the cause is an illness or eye injury, treating these conditions may improve color vision. Using specially tinted eyeglasses or wearing a red-tinted contact lens on one eye can increase some people's ability to differentiate between colors, though nothing can make them truly see the deficient color. For a regular eye examination and refraction, contact lens fitting and/or frame selection, call MCO today at 412 621 6773 or book an on-line appointment

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