What Is Color Blindness? Symptoms, Causes, Diagnosis, Treatment, and Prevention

Also known as color deficiency, color blindness is when you can’t see colors as most other people do. You may have a hard time differentiating between certain colors, such as shades of red and green or, less commonly, shades of blue and yellow. People who are completely color blind can’t see color at all — they can only see shades of black and white. This condition, known as achromatopsia, is rare.

Color blindness tends to run in families and is inherited at birth. There’s no cure for color blindness, but special glasses and corrective lenses can help. (1)

Symptoms of color blindness can vary from person to person. Many people have such mild symptoms that they don’t know they have a color deficiency.

The main symptom of color blindness is difficulty telling colors apart or making mistakes when identifying colors.

People with color blindness may not be able to tell the difference between:

• Shades of colors, especially shades of red and green or shades of green and blue
• The brightness of colors

In rare cases, people with severe color blindness may also experience symptoms like nystagmus (rapid, uncontrollable eye movements) or sensitivity to light. (1)

The most common types of color blindness are hereditary, passed from parent to child. Many people are born with it, which makes it a congenital condition.

Color blindness is caused by a total or partial lack of cones in the retina. Cones are what detect the colors red, green, and blue. (2)

In some cases, color blindness may occur later in life due to these circumstances:

• Diseases such as eye disease, metabolic disease, or vascular disease
• Damage to the eye or brain
• Age-related cataracts
• Certain medications (1,2)

Men have a higher risk of color blindness than women. You’re also more likely to have color blindness if you meet any of the following criteria:

• Have a family history of color blindness
• Have an eye disease such as age-related macular degeneration or glaucoma
• Have health issues like diabetes, multiple sclerosis, or Alzheimer’s disease
• Are on certain medications
• Are white (1)

Red-green color blindness can be diagnosed with a simple eye test. Optometrists (eye doctors) often check children for color blindness as part of a routine vision screening.

The most common way to determine if you have color blindness is with the Ishihara color test: You’ll be presented with several plates or pages. Each will have a circle created by dots composed of two or more colors. The optometrist will ask you what number you see. People with red-green color blindness will have trouble seeing some of the numbers. (2)

Learn More About How Color Blindness is Diagnosed

Whether you’re born with color blindness or you develop it as you age, you will most likely experience it for the duration of your life. There is no cure for color blindness, but there are ways to manage it. (1) If your color blindness is caused by an eye injury or underlying condition, treating these issues may improve your color vision. (3)

For inherited forms of color blindness, not due to an underlying condition, there are currently no medical treatments. Most people with color blindness learn to adapt and live with the condition.

For many people, a color vision deficiency is a relatively minor inconvenience. Some people go many years without even knowing that they see colors differently from how most people see them.

Here are some ways to work around poor color vision:

• Special glasses or contacts may help some people with red-green deficiency see the difference between colors.
• Smartphone or tablet apps designed for people with poor color vision allow users to detect colors of objects.
• Try memorizing the order of colored objects, such as traffic lights.
• Ask someone with good color vision to label and sort your clothing or other items that you want to match. (1,3)

If your child has color blindness, let teachers know that your child has trouble seeing certain colors.

Children with color blindness may have a hard time seeing yellow chalk on a green chalkboard or reading assignments printed on colored paper or with colored ink.

Teach your child the colors of common items. This can provide a frame of reference for when other people are discussing colors in your child’s presence. (4)

Learn More About Treatment Options for Color Blindness

Prevention of Color Blindness

There’s no way to prevent genetic color blindness. However, it’s possible to reduce your chances of developing color blindness as you get older by seeing your general practitioner regularly, getting an annual eye exam, and following a healthy lifestyle. (5)

People with a severe form of color blindness called achromatopsia cannot see any colors — they only see black, white, and shades of gray. They may also have other vision problems, such as sensitivity to light and glare, uncontrollable eye movements (nystagmus), low visual acuity (not being able to see things sharply), and farsightedness. Achromatopsia is rare — it affects approximately 1 in 30,000 people worldwide. (6)

Red-green color vision defects are the most common form of color blindness, and it affects men more than women. Among people with northern European ancestry, red-green color blindness impacts about 8 percent of men and 0.5 percent of women.

Blue-yellow color blindness affects men and women equally. Fewer than 1 in 10,000 people worldwide have blue-yellow color blindness. (7)

The Latest Research

Researchers are experimenting with gene therapy to treat color blindness. In a small study from 2020, nine people with achromatopsia (total color blindness) were able to see some color after being treated with a gene therapy — specifically, a genetically engineered virus designed to correct a defect in a gene called CNGA3. (8)

Gene therapy uses viruses because of how easily they can enter cells (the viruses are altered so they don’t cause infection). Each participant received an injection in one eye. Although the study was meant to test the safety of the approach, researchers found that it improved focus, contrast, and color vision in participants to a small degree. More research is needed, but the results are promising. (8)

Black, Indigenous, and People of Color (BIPOC) are less likely than white people to have color blindness. A study from 2014 looked at color vision deficiency in preschool children and found that almost 6 percent of white boys had color blindness, compared with 3 percent of Asian American boys, almost 3 percent of Hispanic American boys, and less than 2 percent of African American boys. (9)

Having certain conditions can increase your risk of color blindness:

• Glaucoma
• Macular degeneration
• Diabetes
• Parkinson’s disease
• Alzheimer’s disease
• Alcoholism
• Leukemia
• Sickle cell anemia

Additionally, certain drugs can increase the risk of color blindness. For example, a drug used to treat rheumatoid arthritis called hydroxychloroquine (Plaquenil) can increase your risk. (2)

American Academy of Ophthalmology (AAO)

The AAO is the largest association of eye physicians and surgeons in the world, with over 32,000 doctors. Ophthalmologists receive special training in eye care, including the prevention, diagnosis, and medical and surgical treatment of eye conditions and diseases. In addition to providing information about color blindness, the AAO website has a feature to help you find an ophthalmologist.

National Eye Institute (NEI)

The NEI is a division of the National Institutes of Health, providing up-to-date facts on symptoms, causes, and treatment for color blindness. Its website has tips for parents on when to get your child tested if you’re concerned about color blindness.

American Optometric Association (AOA)

The AOA, which represents doctors and professionals of optometry, offers a wealth of information on eye conditions and diseases, including color blindness, on its website.

We Are Colorblind

This project from a team in the Netherlands describes itself as “dedicated to making the world a better place for the color blind” by improving the design of products and services to make them more accessible. The website features articles, interviews, and news on the subject, along with additional resources such as a list of children’s books on color blindness and a podcast.