Screening Tests to Diagnose Color Blindness

Color BlindnessWe often joke about being color blind, but in its truest sense it is a serious condition. Color deficiency, in which a person has difficulty distinguishing between colors, is a fairly common condition, though much more so in men. It is estimated that one in ten men and one in a hundred women have some form of color blindness. Total color blindness, where the person sees only in shades of gray, is fortunately very rare.

What is color deficiency?

The retina, which captures an image much like the film in a camera, is made up of layers of tissue and within them are photoreceptors called rods and cones. There are three types of cones responsible for color vision, and a deficiency will produce confusion between the colors. The most common forms of color blindness involve the red and/or green cones and cause difficulty differentiating between reds and greens. Color deficiency is usually hereditary and congenital but can also be the result of an accident or exposure to certain chemicals.

Diagnosing color blindness

Color Vision Test is a booklet of pages each with a circular pattern made up of colored dots in various colors, sizes and degrees of brightness. The colored dots are arranged so that a person with normal color vision will clearly see a number within the array of dots in a different color. A color blind person will either see a different number, or no number at all. The full test has 38 plates, but generally only 14 or 24 plates are used. The test is usually taken in normal room lighting with the patient wearing their normal eyeglasses, if needed. Note: this test is unsuitable for young children who can’t accurately identify numbers.

Who should be screened for color blindness?

Anyone pursuing a profession which requires color accuracy should be screened for color blindness. This includes would-be electricians, commercial artists, designers, technicians, police officers, pilots and those interested in certain military careers, as safety and job performance can depend heavily upon accurate color perception.

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