Topic Overview
What is color blindness?
Color blindness means you
have trouble seeing red, green, or blue or a mix of these colors. It’s rare
that a person sees no color at all.
Color blindness is also called
a color vision problem.
A color vision problem can change your
life. It makes it harder to learn and read, and you may not be able to have
certain careers. But children and adults with color vision problems can learn
to make up for their problems seeing color.
What causes color blindness?
Most color vision
problems are inherited (genetic) and are present at
birth.
People usually have three types of cone cells in the eye.
Each type senses either red, green, or blue light. You see color when your cone
cells sense different amounts of these three basic colors. Most cone cells are
found in the
macula, which is the central part of the
retina.
See a picture of the
eye that shows the retina and the macula.
Inherited color blindness happens when you don't have one of these types
of cone cells or they don't work right. You may not see one of these three
basic colors, or you may see a different shade of that color or a different
color. This type of color vision problem doesn't change over time.
A color vision problem is not always inherited. In some cases, a person
can have an acquired color vision problem. This can be caused by:
What are the symptoms?
The symptoms of color
vision problems vary:
- You may see many colors, so you may not know
that you see color differently from others.
- You may only be able
to see a few shades of color, while most people can see thousands of colors.
- In rare cases, you may see only black, white, and gray.
How is color blindness diagnosed?
Tests measure
how well you recognize different colors.
- In one type of test, you look at sets of
colored dots and try to find a pattern in them, such as a letter or number. The
patterns you see help your doctor determine which colors you have trouble with.
- In another type of test, you arrange colored chips in order
according to how similar the colors are. People with color vision problems
cannot arrange the colored chips correctly.
How is it treated?
Inherited color vision problems
cannot be treated or corrected.
Some acquired color vision
problems can be treated, depending on the cause. For example, if a cataract is
causing a problem with color vision, surgery to remove the cataract may restore
normal color vision.
You can find ways to help make up for a color
vision problem, such as wearing colored contact lenses or eyeglasses or wearing
glasses that block glare. You can learn to look for other things, such as
brightness or location, rather than colors. For example, you can learn the
order of the three colored lights on a traffic signal.
How can you help a child who has color blindness?
Color vision problems can make learning and reading hard for children, which
can lead to poor schoolwork and low self-esteem.
You can help your
child by:
- Making sure your child is tested for color
vision problems during routine eye tests. The sooner you know there is a
problem, the sooner you can help your child.
- Telling your child’s
teachers and other school staff about the problem. Suggest seating your child
where there is no glare and using a color of chalk that your child can see.
Frequently Asked Questions
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Learning about color blindness:
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Being diagnosed:
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Getting treatment:
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Ongoing concerns:
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Living with color blindness:
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Symptoms
Symptoms of
color blindness can vary. Different people see
different shades of colors. You may not be able to see red, green, and blue or
variations of those colors. If the color vision problem is not severe, you may
not realize that you are seeing something different than a person who has
normal color vision.
People with less severe color vision problems
see variations of colors. They may not be able to tell the difference between
red and green but can see blue and yellow.
People with severe
color vision problems cannot see color at all. They see only shades of gray,
black, and white.
Inherited color vision problems affect
both eyes equally. Acquired color vision problems may occur in only one
eye or may affect one eye more than the other. Inherited problems with color
vision are usually present at birth and do not change. An acquired color vision
problem may change over time as a person ages or during the course of the
disease or injury that causes the problem.
Exams and Tests
Tests can detect
color blindness by measuring the ability to recognize
different colors.
A test that is used to check for inherited color
vision problems is called a pseudoisochromatic plate test. For this test, you
are asked to look at a square of colored dots and identify a pattern, such as a
letter or number, within the colored dots. People who have normal color vision
can see these patterns. People who have color vision problems can see only some
of these patterns or cannot see the patterns at all. Often the type of color
vision problem a person has can be determined from which patterns they can
identify in the plate test.
An arrangement test is used to check
for acquired color vision problems or check the severity of inherited color
vision problems. This test involves arranging colored chips in sequence
according to hue (color) from a reference color. People who have normal color
vision can arrange the colored chips with similar color. People who have color
vision problems cannot arrange the colored chips correctly.
For
more information about vision tests, including tests used for color vision, see
the topic
Vision Tests.
Early detection
Because a color vision problem can
have a big impact on a person's life, it is important to detect the problem as
early as possible. In children, color vision problems can affect learning
abilities and reading development. And color vision problems may limit career choices. Most experts
recommend eye exams for children between ages 3 and 5. Vision screening is
recommended for all children at least once before entering school, preferably
between the ages of 3 and 4.
Treatment Overview
There is no medical treatment for
color blindness that is
inherited. Some
acquired color vision problems can be treated,
depending on the cause.
Color blindness that is acquired may
sometimes be improved by surgery. For example, if you are having trouble seeing
colors because of cataracts, surgery to treat the cataracts may improve color
vision. If the problem is caused by a side effect of medicine, color vision
may be improved when that medicine is stopped.
There may be some
things you can do to help compensate for a color vision problem.
- Specially tinted contact lenses and eyeglasses
may help you see differences between colors. But these lenses do not
provide normal color vision and can distort objects.
- Glasses that
block glare (with side shields or wide temples) are helpful because people with
color vision problems can see differences between colors better when there is
less glare and brightness. A person with color vision problems can actually see
better when the lighting is not bright.
- If you do not see color at
all and rely on rod cells for vision (rod monochromatism), you may need to wear
tinted or dark glasses with side shields because rod cells work better in dim
light. You may also need corrective lenses (glasses or contact lenses) because
vision using only the rod cells is less clear and sharp.
Color vision problems cannot be prevented.
Home Treatment
Color blindness
can have a big impact on your life. Many common activities rely on
signs or signals that are color-coded, such as traffic signs, signal lights,
and maps. Choosing clothing with appropriate matching or complementary colors
can also be more of a challenge.
In many cases, there are ways to
help compensate for your inability to see or distinguish colors by the way you
observe things or by watching other people's actions. You may rely on
brightness or location rather than color to identify objects. For example, you
can learn the order of the three colored lights on a traffic signal and know
that if the bottom light is lit, it means that the light is green and it is
safe to go.
Color vision problems can affect learning abilities
and reading development. Children may try to hide the fact that they cannot see
certain colors by watching other classmates or even copying their work. Not
being able to tell the difference between colors can be a serious problem for
children and can lead to poor class work and low self-esteem.
- Testing for color vision problems during
routine vision screening may help a child avoid having trouble in school. If
your child is having trouble in school, have his or her vision, including color
vision, checked by an eye doctor.
- If your child has color vision
problems, it is important that his or her teacher be aware of this. Even simple
things like reading yellow chalk on a green board can be hard for a child with
color vision problems.
- You may want to offer suggestions to your
child's teacher about how to help your child see better. This can include using
a different color chalk or seating your child where there is no glare from
bright lights. You can test your child at home with different colors of chalk,
pens, and paper to find out which colors are easiest for your child to
see.
Color vision problems may limit career choices. For
example, color photographers, interior and clothing designers, and painters
need normal color vision. Laws prohibit people with severe color vision
problems from holding certain jobs, such as airline pilot, police officer, and
some positions in the military.
Other Places To Get Help
Organizations
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American Academy of Ophthalmology
(AAO)
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| P.O. Box 7424 |
| San Francisco, CA 94120-7424 |
| Phone: |
(415) 561-8500 |
| Fax: |
(415) 561-8533 |
| Web Address: |
www.aao.org |
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The American Academy of Ophthalmology (AAO) is an association of
medical eye doctors. It provides general information and brochures on eye
conditions and diseases and low-vision resources and services. The AAO is not
able to answer questions about specific medical problems or conditions.
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American Optometric Association
(AOA)
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| 243 North Lindbergh Boulevard |
| St. Louis, MO 63141-7881 |
| Phone: |
1-800-365-2219 |
| Web Address: |
www.aoanet.org |
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The American Optometric Association (AOA), which is a
national organization of optometrists, can provide information on eye health
and eye problems.
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National Eye Institute, National Institutes of
Health
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| Information Office |
| 31 Center Drive MSC 2510 |
| Bethesda, MD 20892-2510 |
| Phone: |
(301) 496-5248 |
| E-mail: |
2020@nei.nih.gov |
| Web Address: |
www.nei.nih.gov |
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As part of the U.S. National Institutes of Health, the National Eye
Institute provides information on eye diseases and vision research.
Publications are available to the public at no charge. The Web site includes
links to various information resources.
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Prevent Blindness America
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| 211 West Wacker Drive |
| Suite 1700 |
| Chicago, IL 60606 |
| Phone: |
1-800-331-2020 |
| Web Address: |
www.preventblindness.org |
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Prevent Blindness America assists the visually impaired
and provides consumer information on vision problems and vision aids.
Its Web site has information about eye health and safety for children
and adults. Many states have local affiliates.
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References
Other Works Consulted
- Chang DF (2008). Color vision testing section of Ophthalmologic examination. In P Riordan-Eva, JP Whitcher, eds., Vaughan and Asbury's General Ophthalmology, 17th ed., pp. 46-59. New York: McGraw-Hill.
- Sieving PA, Caruso RC (2009). Retinitis pigmentosa and related
disorders. In M Yanoff, JS Duker, eds., Ophthalmology,
3rd ed., pp. 550–559. Edinburgh: Mosby Elsevier.
Credits
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Author
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Jeannette Curtis |
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Editor
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Kathleen M. Ariss, MS |
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Associate Editor
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Pat Truman, MATC |
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Primary Medical Reviewer
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Kathleen Romito, MD - Family Medicine |
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Specialist Medical Reviewer
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Christopher J. Rudnisky, MD, FRCSC - Ophthalmology |
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Last Updated
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October 7, 2009 |
