blindness (color vision deficiency) is a condition in which certain colors
cannot be detected. There are two types of color vision difficulties: inherited
(congenital) problems that you have at birth, and problems that develop later
born with color vision problems are unaware what they see is different from
what others see unless it is pointed out to them. People with acquired color
vision problems are aware that something has gone wrong with their color
color vision defects usually pass from mother to son. These defects are due to
partial or complete lack of the light-sensitive photoreceptors (cones) in the
retina, the layer of light-sensitive nerve cells lining the back of the eye.
Cones distinguish the colors red, green and blue through visual pigment present
in the normal human eye. Problems with color vision occur when the amount of
pigment per cone is reduced or one or more of the three cone systems are
absent. This limits the ability to distinguish between greens and reds, and
occasionally blues. It involves both eyes equally and remains stable throughout
are different degrees of color blindness. Some people with mild color
deficiencies can see colors normally in good light but have difficulty in dim
light. Others can't distinguish certain colors in any light. In the most severe
form of color blindness everything is seen in shades of gray.
in the most severe form, color blindness does not affect the sharpness of
vision at all. It does not correlate with low intelligence or learning
color vision problems that occur later in life are a result of disease, trauma,
toxic effects from drugs, metabolic disease, or vascular disease. Color vision
defects from disease are less understood than congenital color vision problems.
There is often uneven involvement of the eyes and the color vision defect will
usually be progressive. Acquired color vision loss can be the result of damage
to the retina or optic nerve.
is no treatment for color blindness. It usually does not cause any significant
disability. It can, however, prevent employment in an increasing number of
in color vision can signify a more serious condition. Anyone who experiences a
significant change in color perception should see an ophthalmologist.