Colorblindness, also called color vision deficiency, is an inherited condition that can range from a slight difficulty in telling the shades of a color apart to the rare condition of not being able to identify any color.

The most common type of colorblindness is one in which the person can't distinguish between red and green. The second most common type is the inability to distinguish between blue and yellow.


The dazzling visual experience of color begins when light strikes nerve cells in the retina at the back of the eye. These cells are called rods and cones. Rods help us distinguish light and dark; cones contain chemicals that identify color and send the message to the brain that enables us to see color. People who are colorblind are lacking in one or more of the chemicals contained in the cone.

Colorblindness is a group of inherited traits, passed down through families, usually from mother to son. It can also be caused by diabetes, glaucoma, cataracts, macular degeneration, Alzheimer’s disease, Parkinson’s disease, leukemia, and sickle cell anemia. Certain medications, exposure to strong chemicals and aging are also causes.

Colorblindness affects millions of Americans. It is much more common in boys than in girls, affecting 8 percent of males and 0.5 percent of females, according to the US National Library of Medicine. White children are affected more than children in other ethnic and racial groups.


Colorblindness can range from mild to severe. In the milder forms, a person will not see colors with the same intensity that people with normal color vision see them. In the more severe forms, a person will have difficulty distinguishing among colors.

People with normal color vision can identify more than 100 different hues. Those with severe forms of red-green colorblindness can't distinguish between these hues. They may see only blacks, grays and whites, along with blues and yellows. When they look at a rainbow, they will see red, orange, yellow, and green as one color, yellow. The blue and purple of the rainbow will appear as blue.

Another type of colorblindness is the inability to distinguish blue and yellow. Most people with this type of colorblindness also have trouble with red and green.

The most severe form of colorblindness, achromatopsia, is the inability to see any color. It is rare and usually associated with other eye conditions, including lazy eye (amblyopia) and photosensitivity.

If you suspect someone has a problem with colors, suggest that he or she see a doctor for testing. The test usually involves trying to identify a shape in a multicolored dot-pattern book. The shape or a number in the middle of the dot pattern can be identified by people with normal color vision.

Helping a child cope

If your child has inherited colorblindness, you can work with your child's teachers to help your child learn effective ways to cope with it. If there is another cause for color blindness, then treatment of that cause may help. Here are suggestions:

  • Learn all you can about colorblindness.

  • Be sensitive to your child's condition. Provide visual cues other than color, such as textures and patterns.

  • Make sure teachers know your child is colorblind.

  • Buy scented crayons.

  • Let your child pick certain articles of clothing. Then choose other articles that match those choices.

Medical Reviewer: [Fincannon, Joy RN MN, Godsey, Cynthia M.S., M.S.N., APRN, Hammersmith, Kristin, MD, Lambert, J.G. M.D.] Last Annual Review Date: 2011-01-12T00:00:00-07:00 Copyright: Copyright Health Ink & Vitality Communications

Your Guide to Alzheimer's Disease

Take a Personalized Health Test

Did You Know?

View Source

More than 5.3 million people in the United States are living with Alzheimer's disease, with a new person developing the disease every 70 seconds. Americans ages 65 and older with Alzheimer's and dementia pay three times as much in health care costs.