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.
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:
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 eyecare provider right away.
Your eyecare 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 eyecare provider may refer you to a specialist for more detailed testing and diagnosis.
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. If you are severely color blind, a red tinted contact lens may be prescribed for just one eye. This may help you see colors a little better.
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:
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.
Inherited color blindness cannot be prevented.