Colour Blindness

Examinations and Tests

Tests can detect colour blindness by measuring the ability to recognize different colours.

A test that is used to check for inherited colour vision problems is called a pseudoisochromatic plate test. For this test, you are asked to look at a square of coloured dots and identify a pattern, such as a letter or number, within the coloured dots. People who have normal colour vision can see these patterns. People who have colour vision problems can see only some of these patterns or cannot see the patterns at all. Often the type of colour vision problem a person has can be determined from which patterns they can identify in the plate test.

An arrangement test is used to check for acquired colour vision problems or check the severity of inherited colour vision problems. This test involves arranging coloured chips in sequence according to hue (colour) from a reference colour. People who have normal colour vision can arrange the coloured chips with similar colour. People who have colour vision problems cannot arrange the coloured chips correctly.

For more information about vision tests, including tests used for colour vision, see the topic Vision Tests.

Early detection

Because a colour vision problem can have a significant impact on a person's life, it is important to detect it as early as possible. In children, colour vision problems can affect learning abilities and reading development and may limit career choices. Most experts recommend eye examinations for children between ages 3 and 5. Vision screening is recommended for all children at least once before entering school, preferably between the ages of 3 and 4.

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Author:	Alison Allen Robin Parks, MS	Last Updated: December 6, 2007
Medical Review:	Kathleen Romito, MD - Family Medicine Carol L. Karp, MD - Ophthalmology Anne C. Poinier, MD - Internal Medicine
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