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Color blindness is an eye condition in which someone can't see the difference between certain colors. Though many people commonly use the term "color blind" for this condition, true color blindness — in which everything is seen in shades of black and white — is rare. The medical term for color blindness is known as color vision deficiency.
Color blindness is usually inherited, meaning it's passed down through families. Men are more likely to be born with color blindness. Most people with color blindness can't tell the difference between certain shades of red and green. Less commonly, people with color blindness can't tell the difference between shades of blue and yellow.
Certain eye diseases and some medicines also can cause color blindness.
You may have a color vision deficiency and not know it. Some people figure out that they or their child has the condition when it causes confusion — such as when there are problems differentiating the colors in a traffic light or interpreting color-coded learning materials.
People affected by color blindness may not be able to distinguish:
The most common color deficiency is an inability to see some shades of red and green. Often, a person who is red-green or blue-yellow deficient isn't completely insensitive to both colors. Defects can be mild, moderate or severe.
If you suspect you have problems distinguishing certain colors or your color vision changes, see an eye doctor for testing. It's important that children get comprehensive eye exams, including color vision testing, before starting school.
There's no cure for inherited color deficiencies, but if illness or eye disease is the cause, treatment may improve color vision.
Seeing colors across the light spectrum is a complex process that begins with your eyes' ability to respond to different wavelengths of light.
Light, which contains all color wavelengths, enters your eye through the cornea and passes through the lens and transparent, jellylike tissue in your eye (vitreous humor) to wavelength-sensitive cells (cones) at the back of your eye in the macular area of the retina. The cones are sensitive to short (blue), medium (green) or long (red) wavelengths of light. Chemicals in the cones trigger a reaction and send the wavelength information through your optic nerve to your brain.
If your eyes work as they should, you perceive color. But if your cones don't work properly, you will be unable to distinguish the colors red, green or blue.
Several factors increase the risk of color blindness, including:
If you have trouble seeing certain colors, an eye care professional can test for a color deficiency. Testing likely involves a thorough eye exam and looking at specially designed pictures. These pictures are made of colored dots that have numbers or shapes in a different color hidden in them.
If someone has a color vision deficiency, they'll find it difficult or impossible to see some of the patterns in the dots.
There are no treatments for most types of color vision difficulties, unless the color vision problem is related to the use of certain medicines or eye conditions. Stopping the medicine causing the vision problem or treating the underlying eye disease may result in better color vision.
Wearing a colored filter over eyeglasses or a colored contact lens may enhance perception of contrast between the confused colors. But such lenses won't improve the ability to see all colors.
Some rare retinal disorders associated with color deficiency could possibly be modified with gene replacement techniques. These treatments are under study. One treatment was approved for a rare condition called Leber congenital amaurosis, a retina condition that is present at birth. More treatments might become available in the future.
Try the following tips to help you work around your color blindness.
You can start by seeing someone on your primary healthcare team or make an appointment with an eye care professional who specializes in eye disorders (ophthalmologist or optometrist).
Preparing a list of questions can help you make the most of your time. For color blindness, some basic questions to ask include:
You'll likely be asked a few questions, such as: