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Color Blindness

Color blindness, or color vision deficiency, is the inability or decreased ability to see color, or perceive color differences, under normal lighting conditions. There is no actual blindness.

PubMed Health Glossary
(Source: Wikipedia)

About Color Blindness

Most of us share a common color vision sensory experience. Some people, however, have a color vision deficiency, which means their perception of colors is different from what most of us see. The most severe forms of these deficiencies are referred to as color blindness. People with color blindness aren't aware of differences among colors that are obvious to the rest of us. People who don't have the more severe types of color blindness may not even be aware of their condition unless they're tested in a clinic or laboratory.

Inherited color blindness is caused by abnormal photopigments. These color-detecting molecules are located in cone-shaped cells within the retina, called cone cells. In humans, several genes are needed for the body to make photopigments, and defects in these genes can lead to color blindness.

There are three main kinds of color blindness, based on photopigment defects in the three different kinds of cones that respond to blue, green, and red light. Red-green color blindness is the most common, followed by blue-green color blindness. A complete absence of color vision —total color blindness — is rare.

Sometimes color blindness can be caused by physical or chemical damage to the eye, the optic nerve, or parts of the brain that process color information. Color vision can also decline with age, most often because of cataract - a clouding and yellowing of the eye's lens. NIH - National Eye Institute

What works? Research summarized

Evidence reviews

Colour vision testing for diabetic retinopathy: a systematic review of diagnostic accuracy and economic evaluation

Diabetic retinopathy (DR) is caused by pathological changes in the blood vessels of the retina, which can lead to blindness.

Colour vision testing for diabetic retinopathy: a systematic review of diagnostic accuracy and economic evaluation

This well-conducted review concluded that there was insufficient evidence to support the use of colour vision testing alone, or in combination with retinal photography, as a method for screening for retinopathy in patients with diabetes. Given the paucity of good quality evidence, the authors' conclusion seems appropriate and reliable.

Treatment for Glaucoma: Comparative Effectiveness [Internet]

Glaucoma is a leading cause of visual impairment and blindness worldwide. Treatment focuses on the reduction of intraocular pressure (IOP), which secondarily prevents worsening of visual field loss; in this way, available treatments may prevent visual impairment and blindness. The objective of this Comparative Effectiveness Review is to summarize the evidence regarding the safety and effectiveness of medical, laser, and other surgical treatments for open-angle glaucoma in adults.

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Summaries for consumers

Treatments for Open-Angle Glaucoma: A Review of the Research for Adults

This summary will tell you about medicines, laser surgery, and traditional surgery to treat open-angle glaucoma. It will discuss what research says about how well these treatments work and possible side effects. You can use this information when talking with your eye doctor about what treatment may be right for you.

Late Effects of Treatment for Childhood Cancer (PDQ®): Patient Version

Expert-reviewed information summary about the health problems that continue or appear after cancer treatment has ended.

More about Color Blindness

Photo of an adult

Also called: Colour blindness, Color vision deficiency, Color vision defects

Other terms to know:
Cone Cells, Retina

Keep up with systematic reviews on Color Blindness:


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