Color Blindness

What is color blindness?

Color blindness is a vision problem that makes it hard to tell the difference between certain colors. It does not mean that you cannot see any colors. That is very rare. Most color-blind people have trouble with just 1 or 2 colors, most commonly red and green. Shades of red and green might look brownish to a color-blind person.

What is the cause?

Special cells in your eye called cones allow you to see colors. The cones are located in the retina, which is the lining at the back of the eye that senses light coming into your eye. If the cones are weak, damaged or missing, you may not see colors the same way that other people see them.

Color blindness is most often something you are born with, and it is more common in men than in women. It is rare for a female to have color blindness.

Color blindness can happen later in life if something damages your retina or the nerve that connects your eye to your brain. This may be caused by:

  • An injury
  • A disease such as diabetes, sickle cell anemia, or multiple sclerosis
  • An eye disease such as cataracts, glaucoma, or age-related macular degeneration
  • Alcohol abuse
  • Smoking
  • Certain medicines

What are the symptoms?

Color blindness can be mild to severe. You may have trouble telling some colors apart, or you may not be able to recognize certain colors at all.

If you develop color blindness and have not had it before, contact your eye care provider right away.

How is it diagnosed?

Your eye care provider can do a simple test for color blindness. You look at a special test book that has a pattern of small colored circles. Some of the circles on the page are a different color and form a number. A color blind person will not be able to see the number because it looks the same color as the other circles on the page. The test book has about a dozen of these patterns in it to make sure of the diagnosis and to judge how severe the color blindness is. This is a simple screening test that can be used even on very young children.

Your eye care provider may refer you to a specialist for more detailed testing and diagnosis.

How is it treated?

Color blindness is a lifelong condition. Usually there is no need to treat it. People with color blindness learn to tell the differences between colors. For example, green might look brighter than red.

How can I take care of myself?

Most of the time, you can learn to adjust by using cues other than colors. For example, you can look for the position of the brightest light on a traffic signal rather than whether it is red, yellow, or green. You may find that red looks darker than green for you.

You may need help to do some tasks that involve colors such as:

  • Choosing and buying clothes
  • Reading color-coded maps or weather charts
  • Knowing if fruits are ripe or if meat is rare or well-done

You may need to avoid careers that require good color vision. For example, electricians must work with multi-colored wires. While you may not be able to do some jobs, employers may work with you to find ways you can adapt.

How can I help prevent color blindness?

Inherited color blindness cannot be prevented.

Have regular eye exams, especially if you take medicine for rheumatoid arthritis, erectile dysfunction, or heart disease. If you have diabetes, multiple sclerosis, or sarcoidosis, you should have yearly eye exams.

Reviewed for medical accuracy by faculty at the Wilmer Eye Institute at Johns Hopkins. Web site:
Developed by RelayHealth.
Adult Advisor 2015.1 published by RelayHealth.
Last modified: 2014-10-28
Last reviewed: 2014-10-28
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
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