Color blindness (patient information): Difference between revisions
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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. | 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. | ||
Color | Color blindness is often inherited [[Heredity|genetically]] It is most commonly inherited from mutations in a [[X-linked recessive]] fashion, but the mapping of the [[human genome]] has shown there are many causative [[mutations]] – [[mutations]] capable of causing color blindness originate from at least 19 different [[chromosomes]] and many different [[genes]] (as shown online at the [[Online Mendelian Inheritance in Man]] (OMIM) database at Johns Hopkins University). | ||
Some of the inherited diseases known to cause color blindness are: | |||
*[[cone dystrophy]] | |||
*[[cone-rod dystrophy]] | |||
*[[achromatopsia]] (aka rod monochromatism, aka stationary cone dystrophy, aka cone dysfunction syndrome) | |||
*[[blue cone monochromatism]], | |||
*[[Leber's congenital amaurosis]]. | |||
*[[retinitis pigmentosa]] (initially affects rods but can later progress to cones and therefore color blindness) | |||
Inherited color blindness can be [[congenital]] (from birth), or it can commence in childhood or adulthood. | |||
Other causes of color blindness include: | |||
* [[Brain]] or [[retina|retinal]] damage caused by [[shaken baby syndrome]], accidents and other trauma which produce swelling of the [[brain]] in the [[occipital lobe]] | * [[Brain]] or [[retina|retinal]] damage caused by [[shaken baby syndrome]], accidents and other trauma which produce swelling of the [[brain]] in the [[occipital lobe]] | ||
* Damage to the [[retina]] caused by exposure to [[ultraviolet light]]. | * Damage to the [[retina]] caused by exposure to [[ultraviolet light]]. | ||
Revision as of 17:17, 26 January 2010
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What is color blindness?
Color blindness is the inability to see certain colors in the usual way.
What are the symptoms of color blindness?
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, the symptoms may be so mild that some persons do not know they are color blind. A parent may notice signs of color blindness when a child is learning his or her colors.
Rapid, side-to-side eye movements and other symptoms may occur in severe cases.
What are the causes of color blindness?
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.
Color blindness is often inherited genetically It is most commonly inherited from mutations in a X-linked recessive fashion, but the mapping of the human genome has shown there are many causative mutations – mutations capable of causing color blindness originate from at least 19 different chromosomes and many different genes (as shown online at the Online Mendelian Inheritance in Man (OMIM) database at Johns Hopkins University).
Some of the inherited diseases known to cause color blindness are:
- cone dystrophy
- cone-rod dystrophy
- achromatopsia (aka rod monochromatism, aka stationary cone dystrophy, aka cone dysfunction syndrome)
- blue cone monochromatism,
- Leber's congenital amaurosis.
- retinitis pigmentosa (initially affects rods but can later progress to cones and therefore color blindness)
Inherited color blindness can be congenital (from birth), or it can commence in childhood or adulthood.
Other causes of color blindness include:
- Brain or retinal damage caused by shaken baby syndrome, accidents and other trauma which produce swelling of the brain in the occipital lobe
- Damage to the retina caused by exposure to ultraviolet light.
- The drug hydroxychloroquine (Plaquenil) can also cause color blindness. It is used to treat rheumatoid arthritis, among other conditions.
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. Achromatopsia is either an acquired or congenital condition. The acquired version is caused by damage to the thalamus, a portion of the brain stem. It is most frequently caused by tumor growth, since the thalamus is well protected from external damage. All known causes of congenital achromatopsia are due to a malfunction of the retinal phototransduction pathway.
Who is at risk for color blindness?
While about 1 in 10 men have some form of color blindness, very few women are color blind.
How to know you have color blindness?
While some people notice that they have difficulty telling the differences between certain colors, others may have such a mild case that they do not even notice any symptoms.
To be certain, your doctor or eye specialist can check your color vision in several ways. Testing for color blindness is commonly done during an eye exam.
When to seek urgent medical care
Color blindness is not considered a medical emergency.
However, make an appointment with your optometrist or ophthalmologist if you think you (or your child) have color blindness.
Treatment options
There is no known treatment.
Diseases with similar symptoms
Where to find medical care for color blindness
Directions to Hospitals Treating color blindness
Prevention of color blindness
What to expect (Outlook/Prognosis)
Color blindness is a life-long condition. Most persons are able to adjust without difficulty or disability.
Sources
http://www.nlm.nih.gov/medlineplus/ency/article/001002.htm