• Home

Home > Medical Reference > Encyclopedia (English)

Toggle: English / Spanish

Color blindness

• Overview
• Symptoms
• Treatment

Definition:

Color blindness is the inability to see certain colors in the usual way.

Alternative Names:

Color deficiency; Blindness - color

Causes, incidence, and risk factors:

Color blindness occurs when there is a problem with the color-sensing materials (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 at the back of the inner eye.

If you are missing just one pigment, you might have trouble telling the difference between red and green. This is the most common type of color blindness. Other times, people have trouble seeing blue-yellow colors. People with blue-yellow color blindness almost always have problems identify reds and greens, too.

The most severe form of color blindness is achromatopsia. A person with this rare condition cannot see any color. 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.

References:

Yanoff M, Duker JS, Augsburger JJ, et al. Ophthalmology . 2nd ed. St. Louis, Mo: Mosby; 2004:34.

Goldman L, Ausiello D. Cecil Textbook of Medicine , 22nd ed. Philadelphia, Pa: WB Saunders; 2004:2410.

• Review Date: 2/22/2007
• Reviewed By: Manju Subramanian, MD, Assistant Professor in Ophthalmology, Vitreoretinal Disease and Surgery, Boston University Eye Associates, Boston, MA. Review provided by VeriMed Healthcare Network.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is the first of its kind, requiring compliance with 53 standards of quality and accountability, verified by independent audit. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial process . A.D.A.M. is also a founding member of Hi-Ethics (www.hiethics.com) and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 1997-2007 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.