Causes

Color blindness occurs when there is a problem with the color-sensing granules (pigments) in certain nerve cells of the eye. These cells are called cones. They are found in the retina, the light-sensitive layer of tissue that lines the back of the eye.

If just one pigment is missing, you may have trouble telling the difference between red and green. This is the most common type of color blindness. If a different pigment is missing, you may have trouble seeing blue-yellow colors. People with blue-yellow color blindness usually have problems identifying reds and greens, too.

The most severe form of color blindness is achromatopsia. A person with this rare condition cannot see any color, so they see everything in shades of gray. Achromatopsia is often associated with lazy eye, nystagmus (small, jerky eye movements), severe light sensitivity, and extremely poor vision.

Most color blindness is due to a genetic problem. (See: X-linked recessive) About 1 in 10 men have some form of color blindness. Very few women are color blind.

The drug hydroxychloroquine (Plaquenil) can also cause color blindness. It is used to treat rheumatoid arthritis, among other conditions.

Symptoms

Symptoms vary from person to person, but may include:

• Trouble seeing colors and the brightness of colors in the usual way
• Inability to tell the difference between shades of the same or similar colors

Often, the symptoms may be so mild that some people do not know they are color blind. A parent may notice signs of color blindness when a child is learning his or her colors.

Rapid, side-to-side eye movements (nystagmus) and other symptoms may occur in severe cases.

Exams and Tests

Your doctor or eye specialist can check your color vision in several ways. Testing for color blindness is commonly done during an eye exam.

Treatment

There is no known treatment. However, there are special contact lenses and glasses that may help people with color blindness tell the difference between similar colors.

Outlook (Prognosis)

Color blindness is a lifelong condition. Most people are able to adjust to it without difficulty or disability.

Possible Complications

People who are colorblind may not be able to get a job that requires the ability to see colors accurately. For example, electricians (color-coded wires), painters, fashion designers (fabrics), and cooks (using the color of meat to tell whether it's done) need to be able to see colors accurately.

When to Contact a Medical Professional

Make an appointment with your health care provider or ophthalmologist if you think you (or your child) have color blindness.

Alternative Names

Color deficiency; Blindness - color

References

Adams AJ, Verdon WA, Spivey BE. Color vision. In: Tasman W, Jaeger EA, eds. Duane's Foundations of Clinical Ophthalmology 15th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2009:chap 19.

Berson EL. Visual function testing: clinical correlations. In: Tasman W, Jaeger EA, eds. Duane's Foundations of Clinical Ophthalmology 15th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2009:chap 14.

Wiggs JL. Molecular genetics of selected ocular disorders. In: Yanoff M, Duker JS, eds. Ophthalmology. 3rd ed. St. Louis, Mo: Mosby Elsevier; 2008:chap 1.2.

Sieving PA, Caruso RC. Retinitis pigmentosa and related disorders. In: Yanoff M, Duker JS, eds. Ophthalmology. 3rd ed. St. Louis, Mo: Mosby Elsevier; 2008:chap 6.10.

Update Date: 4/1/2012

Reviewed by: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; and Franklin W. Lusby, MD, Ophthalmologist, Lusby Vision Institute, La Jolla, California. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.