15 Facts About Color Blindness

Color blindness is usually genetic, but can also be caused by traumatic injury or exposure to chemicals.

There are three types of color blindness - one type makes it difficult to distinguish between red and green, the second type makes it difficult to distinguish between blue and yellow, and a third type is actually complete color blindness in which the eye cannot detect any colors at all.

Red-green color blindness affects 10% of males in the United States, while only 0.5% of women are affected. 99% of all people with color blindness have red-green color blindness.

Blue-yellow color blindness is rare and affects between 1 in 15,000 and 1 in 50,000 people. Both men and women are affected equally.

Monochromacy is the name for total color blindness. It affects about 1 in 30,000 people. Unlike people with red-green or blue-yellow color "blindness," people with monochromacy do not see any color at all, only varying shades of black, white, and gray.

An English chemist named John Dalton, who was himself colorblind, published the first scientific paper on color blindness in 1798.

Color blindness may be an advantage. Colorblind capuchin monkeys are able to catch more insects per hour than non-color blind capuchins. The U.S. Army has found that colorblind people are able to spot camouflaged objects much better than non-colorblind people.

A woman who is red-green colorblind will always have sons who are red-green colorblind.

The Ishihara test, widely used to test for color blindness, was created by Shinobu Ishihara, a Japanese opthalmologist. The Ishihara test consists of 38 plates filled with colored dots that contain numbers in dots of different shades that people who are colorblind cannot see.

The difference between red, green, and yellow traffic lights can be hard to distinguish for colorblind drivers. In Bulgaria, Romania, and Turkey colorblind people are prohibited from driving.

People with color blindness usually dream in the same limited colors they see in waking life.

Colorblind people often have difficulty with foods. They have trouble telling if a piece of red meat is cooked or raw, they can't tell whether a banana is yellow or green, and they can't see any difference between a green, unripe tomato and a ripe, red one.

One theory as to why more men die of colorectal cancer than women is that more men are colorblind and are therefore unable to detect blood on the toilet paper after a bowel movement.

Goldfish are the only animal that can see infrared and ultraviolet light and they have the largest range of color vision so far discovered in any animal.

Contrary to popular belief that dogs and cats only see in shades of gray, they are not completely color blind. However, they do see a more limited range of colors than humans.