Why Are Some People Color Blind?
Scientists think that some people are color blind because they have an abnormality of the three pigments in the cones in the retina of the eye which, it is supposed, are necessary for color vision. The theory of color vision depends on the fact that any color in the spectrum can be matched by a mixture of three pure spectral colors of variable intensity but fixed wavelength.
In color blind persons, all three pigments are usually present, but are of intensity different from normal. They can see all the colors, but have difficulty in distinguishing between red, green and yellow, or between blue, green and yellow. Absence of one or more pigments is rare but does exist, while the complete absence of color vision resulting from lack of cones in the retina sometimes occurs. Most color blind people are ignorant of their abnormality until it is demonstrated to them by means of a special test.
Usually it is not a great handicap. But there are situations, and jobs, such as an air pilot, in which it may be important to distinguish colors quickly. Color blindness is also called a color vision problem. A color vision problem can change your life. It may make it harder to learn and read, and you may not be able to have certain careers. But children and adults with color vision problems can learn to make up for their problems seeing color.
Most color vision problems are inherited (genetic) and are present at birth. People usually have three types of cone cells in the eye. Each type senses red, green, or blue light. You see color when your cone cells sense different amounts of these three basic colors. The highest concentration of cone cells are found in the macula, which is the central part of the retina
Inherited color blindness happens when you don’t have one of these types of cone cells or they don’t work right. You may not see one of these three basic colors, or you may see a different shade of that color or a different color. This type of color vision problem doesn’t change over time. A color vision problem isn’t always inherited. In some cases, a person can have an acquired color vision problem. This can be caused by:
- Eye problems, such as glaucoma, macular degeneration, cataracts, or diabetic retinopathy.
- Injury to the eye.
- Side effects of some medicines.