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Color Deficiencies

DESCRIPTION: A defect of the cones which affects color detection; called "achromatopsia" in its most extreme form; X-linked genetic defect occurring in 8% of men and 0.4% of women; may also be acquired as a result of retinal disease (specifically when it affects the macula) or poisoning. Type depends on which cones are affected:

Cone Monochromats have only one type of cone and may be red-green, red-blue, or green-blue blind; occurs one in a million.

Dichromats have two types of cones; this group is further divided into: Protanopes (red-blind; see blue and green), Deuteranopes (green- blind; confuse shades of red, green and yellow), and Tritanopes (blue-blind; see red and green).

Anomalous Trichromats make up the largest group and are similar to the Dichromatic group except in intensity (Protans and Protanopes, Deutrans and Deuteranopes, Tritans and Tritanopes...similar but milder defects.

Rod Monochromatism is very rare; there is complete lack of cone function and accompanying photophobia, nystagmus, and poor visual acuity; visual fields are normal. The photophobia and nystagmus reduce with age.

TREATMENT: There is no treatment for color deficiencies; in the case of achromatopsia, optical aids, sunglasses, and lowered illumination may be helpful.

IMPLICATIONS: Although color blindness is more of a social inconvenience than a handicap, educators should be aware of students with this condition since many educational materials utilize color as an instructional vehicle. Students with color blindness may need to learn compensatory techniques for sorting or selecting clothing or interpreting traffic signals.

Genetic counseling may be indicated.

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