Color blindness tests for children might identify the degree of deficiency and which form of color blindness exists. An anomaloscope might accurately define the degree of colorblindness, while pseudoisochromatic plates can identity how various colors are seen. Arranging color blindness tests for children can detect their perception of subtle differences in hues.
Most people are familiar with the Ishihara test, named after the doctor who invented a series of plates with symbols or numbers hidden in various colors. These tests are still in use but considered a less accurate color blindness test for children to determine the degree of the disorder. The first Ishihara test plates were painted in 1917 using different colored dots designed in patterns.
Four kinds of plates make up these color blindness tests for children. The vanishing design might be missed by people who are not color blind and is the most difficult to identify. Most children who are severely color blind will not see any number or symbol during the vanishing plate test. On the transformation plate test, a child might see the symbol but be unable to identify its color.
Hidden design Ishihara color blindness tests for children usually spark identification of the number because the patient sees outlines instead of color. These symbols typically cannot be seen by people with normal color discrimination abilities. Eye doctors might use a classification test to diagnose red-green blindness. This type of color blindness test for children uses 14 to 38 plates depicting different colors.
The most accurate tool for evaluating the severity of color blindness involves the use of an anomaloscope, which resembles a microscope. The patient matches green and red lights with yellow lights appearing through the scope. Results of the color blindness test can determine the degree of red-green deficiency and identify specific defects in the eye causing the disorder.
An arrangement test employs a series of colored discs. The patient is asked to arrange the discs in the order displayed on a sample plate. A doctor can determine how the child sees different hues of the same color by analyzing how he or she arranges the discs.
Tests for color blindness first emerged in the 1700s, when patients were asked to match batches of colored ribbons. This subjective test examined how people perceived color and variations in color. Later tests used colored paper and first identified red-green colored blindness.
Many free tests are available on the Internet, but doctors commonly consider these inaccurate color blindness tests for children. Digital images use only red, green, and blue, making these tests limited in identifying severe color blindness. The brightness and hue of colors on individual computer monitors also vary between brands and computer settings.