Home / Color Blindness Explained

Most people see the world the same way. However, some people have a color vision deficiency, which means that how they see colors is different than what most of us see. In severe cases, people with color blindness aren't aware of the differences between colors, and they may not even realize that they don't see the world like everyone else does unless they have their color vision tested by a medical professional.

Causes of Color Blindness

Color blindness is usually a hereditary condition, meaning that you are born with it, but it can also be caused by aging, injury to the eye, glaucoma, or macular degeneration. This condition comes about due to a difference in eye structure. In the macula, a part of the eye connected to the retina, are three different types of cone cells, which allow us to see colors. When one of these types of cones doesn't work properly, color blindness results. If the problem is with the L-cones, also called protanopes, or M-cones, also known as deutanopes, the result will be red-green color blindness. Blue-yellow color blindness is caused by defective S-cones, or tritanopes.

Different Types of Color Blindness

The most common types of color blindness involve red-green deficiencies, in which the person has a hard time telling the difference between these two colors. Protanopia is a red deficiency, which causes the person to see reds more like beiges and experience them as being darker than they are. Deuteranopia, a green deficiency, is the single most common type of color blindness, and people with this condition are insensitive to greens. The result is much like that of protanopia, but people with deuteranopia can often tell the difference between shades of red and green more accurately. The third color deficiency is tritanopia, blue deficiency. With this condition, blue and green look similar, and yellow can sometimes look like red. The rarest type of color blindness is achromacy, which is the experience of no color at all: Everything is in shades of gray.

How Color Blindness Impacts Males and Females

Men are more likely to inherit color blindness than women. This is because color blindness is a recessive trait that is carried on the X chromosome. Since men only have one X chromosome, they only need one copy of this gene to be color-blind, but in women, who have two X chromosomes, two copies of the gene are necessary; otherwise, the dominant trait of having full color vision will be expressed. A woman with only one copy of the gene for color blindness is a carrier for this trait but does not experience it herself. However, she has a 50% chance of passing on this gene to her children; if she passes this gene on to her daughter, and if the child's father is color-blind, the girl will be color-blind as well.

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