| Color vision
deficiency means that your ability to distinguish some colors
and shades is less than normal. It occurs when the color-sensitive
cone cells in your eyes do not properly pick up or send the proper
color signals to your brain. About eight percent of men and one
percent of women are color deficient.
Red-green deficiency is by far the most common form
and it results in the inability to distinguish certain shades of red
and green. Those with a less common type have difficulty
distinguishing blue and yellow. In very rare cases, color deficiency
exists to an extent that no colors can be detected, only shades of
black, white and grey.
Since many learning materials are color-coded, it is
important to diagnose color vision deficiency early in life. This is
why the American Optometric Association recommends a comprehensive
optometric examination before a child begins school.
Color vision deficiency is usually inherited and
cannot be cured, but those affected can often be taught to adapt to
the inability to distinguish colors. In some cases, a special red
tinted contact lens is used in one eye to aid persons with certain
color deficiencies.
| 
