Color blindness, or color vision deficiency, refers to the inability of a person to correctly distinguish certain colors. Color vision problems range from the inability to see different shades of a color to not being able to see certain colors at all. Many people mistakenly believe that to be color blind is to view the world in only black and white, but complete color blindness is rare. A color blind person usually has problems distinguishing between the colors red and green, mistaking them for the same color. A less common type of color blindness involves the colors blue and yellow.
Causes of Color Blindness:
Color blindness is caused by cells in the retina that incorrectly process colors. Specialized cone cells, which are responsible for color vision, lack the ability to send the correct signals to the brain. Color blindness is usually hereditary. About eight percent of men and one percent of women are color vision deficient. More males are affected by the disorder than females.
Occasionally, certain eye diseases cause color blindness, referred to as "acquired color blindness." Aging can also cause the disorder; as the lens darkens with age, older people may find it difficult to distinguish colors.
Symptoms of Color Blindness:
The main symptom of color blindness is difficulty distinguishing between red and green or blue and yellow. Parents will often suspect color blindness when their child has difficulty learning colors. Children having problems at school should be tested for color blindness, as many learning materials rely heavily on students being able to differentiate between colors.
Diagnosing Color Blindness:
The most common test for diagnosing color blindness is the Ishihara test. This quick and simple test consists of a series of pictures made up of colored dots. Among the dots is a figure, usually a number, made up of dots of a different color. A person with normal color vision will be able to see the number, but a color blind person will see a different number or no number at all.
Another test used to diagnose color blindness is called an arrangement test, in which the patient is asked to arrange a group of colored chips in a particular order.
Treating Color Blindness:
Unfortunately, there is no cure for color blindness. People with color vision deficiencies, however, learn ways to cope with the disorder. Patients usually teach themselves how to differentiate between different colors and shades of colors.
Some doctors prescribe color-corrective lenses, depending on the severity of the color vision deficiency. Additionally, computer software has been developed to aid those with color vision disorders.
Source: American Optometric Association, Color Deficiency. 17 Jul 2007.