Color blindness
Definition
Color blindness is the inability to see some colors in the usual way.
Causes
Color blindness occurs when there is a problem with the pigments in certain nerve cells of the eye that sense color. These cells are called cones. They are found in the light-sensitive layer of tissue at the back of the eye, called the retina.
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 often have problems seeing reds and greens, too.
The most severe form of color blindness is achromatopsia. This is a rare condition in which a person cannot see any color, only shades of gray.
Most cases of color blindness are due to a genetic variant. Recent research has helped to identify some of the genes that are variants in people with color blindness. 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 and other conditions. It has also been used to treat COVID-19.
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, symptoms are so mild that people may not know they are color blind. A parent may notice signs of color blindness when a young child is first learning colors.
Rapid, side-to-side eye movements (nystagmus) and other symptoms may occur in severe cases.
Exams and Tests
Your health care provider or eye specialist can check your color vision in several ways. Testing for color blindness is usually part of a complete eye exam.
Treatment
There is no known treatment. Special contact lenses and glasses may help people with color blindness tell the difference between similar colors. Gene therapy, in which normal genes for color perception are introduced into the eye through harmless viral carriers, may hold promise as a treatment.
Outlook (Prognosis)
Color blindness is a lifelong condition. Most people are able to adjust to it.
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, painters, and fashion designers need to be able to see colors accurately.
When to Contact a Medical Professional
Contact your provider or eye specialist if you think you (or your child) may have color blindness.
References
American Academy of Ophthalmology website. What to know if you took Plaquenil and Aralen for COVID-19. www.aao.org/eye-health/tips-prevention/covid-chloroquine-hydroxychloroquine-plaquenil. Updated January 8, 2021. Accessed May 5, 2025.
Robson AG, Moore AT, Duncan JL. Abnormalities of rod and cone function. In: Sadda SVR, Sarraf D, Freund KB, et al, eds. Ryan's Retina. 7th ed. Philadelphia, PA: Elsevier; 2023:chap 44.
Wiggs JL. Molecular genetics of selected ocular disorders. In: Yanoff M, Duker JS, eds. Ophthalmology. 6th ed. Philadelphia, PA: Elsevier; 2023:chap 1.2.2024;18:1265630. PMID: 38298913 pubmed.ncbi.nlm.nih.gov/38298913/.
Yang Z, Yan L, Zhang W, Qi J, An W, Yao K. Dyschromatopsia: a comprehensive analysis of mechanisms and cutting-edge treatments for color vision deficiency. Front Neurosci. 2024;18:1265630. PMID: 38298913 pubmed.ncbi.nlm.nih.gov/38298913/.
Review Date: 4/29/2025
Reviewed By: Franklin W. Lusby, MD, Ophthalmologist, Lusby Vision Institute, La Jolla, CA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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