There are seven types of color blindness and most of them are types that cause a person to perceive color in a limited way. Color blindness ranges from mild, in which a person may not be aware of experiencing color any differently than others do, to severe, in which there is a total inability to perceive color.
Four of the seven types of color blindness are in the red-green spectrum, two are in the blue-yellow spectrum, and one version that cannot distinguish any color.
For most people with the disorder, it is a color deficiency rather than a true color blindness, meaning they can perceive some colors, but can easily confuse colors. For example, someone with one of the red/green color deficiencies is likely to confuse blue and purple because they can’t distinguish the red (long wavelength) element that is within the purple color.
What Causes Color Blindness?
A type of photoreceptor in the eye called cones enables us to see fine detail and to perceive color. The cones are concentrated in the center of the retina in an area called the macula.
- There are three types of cone cells:
- Red-sensing cones (60%)
- Green-sensing cones (30%)
- Blue-sensing cones (10%)
Color deficiencies occur when one or more of the color-sensing cones cells are absent, not functioning properly, or simply detect a differ color. The severe form of color deficiency in which there is no perception of color occurs when all three types of color-sensing cones are defective or absent.
Symptoms of Color Blindness
Parents may notice a child has difficulty learning colors. The most common symptom is the inability to tell the difference between shades of the same or similar color. This happens mostly with red and green or blue and yellow.
Color blindness is usually present from birth but can be caused by disease, brain trauma, or toxic effects from drugs or environmental chemicals.
How Common is Color Blindness?
The inherited form of color blindness is more common in males and that is because the genes responsible for the most common forms of color blindness are on the X chromosomes. Because men only have one X chromosome, if there is a defect on it for color blindness then they are color blind. Women have two X chromosomes so if one chromosome has a defect and the other has a functioning gene for color they will not be color blind. It is estimated that about 1 in 12 men (8%) are colorblind and 1 in 200 women (0.5%) are colorblind.
Ways to Adapt or Compensate for Color Blindness
There is a free smartphone app called “Color Blind Pal” for both iOS and Android phones that helps people identify the colors around them. It also allows people who are not color blind to experience what a color blind person sees.
There are also color blind glasses that use a filter to cut out overlapping color wavelengths that enable a clearer distinction between colors. The glasses do not restore 100% color vision but do enhance and partially correct color deficiencies.
The glasses will provide more contrast between different wavelengths of light making it easier for the brain to differentiate medium wavelengths of light—green from long ones—red.
Color blind glasses do not fix or correct color blindness, but they may make it easier for color deficient people to distinguish between colors. You also have to choose lenses that are for your specific type of color blindness.
While color blindness glasses may help they have limitations:
- Users still cannot pass a color vision test for jobs such as electrician, air pilot, engineer, police officer, and firefighter.
- Colors are brighter but still can be a little off, depending on the severity of a person’s color deficiency.
- They may affect the appearance of other colors.
- You need to be in an area with a lot of light for the glasses to function best.
If you think you might have a color vision deficiency your eye care professional can perform tests to diagnose it or rule it out. If you have a color vision deficiency, you can talk with your eye doctor about the options that will work best for you.