Which of the following conditions does the Ishihara test detect?

If you've ever been tested for colorblindness, the eye doctor probably had you look at a series of circles, crowded with multiple random-sized colored dots. For most people, the dots within the circle reveal a symbol, such as a number or letter. This group finds the test to be relatively simple; they can easily see the figure within because the dots appear to be two different colors.

However, for the colorblind, this type of test, known as an “Ishihara Test”, may prove to be literally impossible. While there are many types of colorblindness, the most common type makes it challenging, at best, to differentiate red from green. An estimated 1 in 12 men and 1 in 200 women are affected by the condition.

The color-perception test was named after its designer, Shinobu Ishihara, a professor at the University of Tokyo, who first published his tests in 1917. The full Ishihara test consists of 38 circles (known as “plates”), but the presence of a severe red-green deficiency is usually apparent after an individual views only a few. Since its introduction, the Ishihara Color Blindness Test has become commonly used worldwide because of its easy use and high accuracy.

At present, there is no cure for inherited color blindness, but most people find ways to cope with it, having never known anything else. Children with color blindness may need help with some classroom activities, and adults with the condition may be restricted from holding job positions which require seeing true colors.