Health Encyclopedia

Color vision test

Definition

A color vision test checks your ability to distinguish between different colors.

Alternative Names

Eye test - color; Vision test - color; Ishihara color vision test

How the test is performed

You will sit in a comfortable position, and your health care provider will explain the test to you. You will be shown several symbols made of colored dot patterns. These dot patterns are on a background of randomly mixed colors.

You will be asked to identify the symbols, if possible.

As you cover one eye, the tester will hold the test plates 14 inches from your face and ask you to quickly identify the symbol found in each color scheme.

How to prepare for the test

If your child is to have this test performed, it may be helpful to explain how the test will feel, and even practice or demonstrate on a doll. Your child will feel less anxious about the test if you explain what will happen and why.

If you or your child normally wears glasses, wear them during the test.

With small children, distinguishing a red bottle cap from caps of a different color may be the test.

How the test will feel

The test is similar to a vision test.

Why the test is performed

This test is done to determine if you have any problems in your color vision.

In some cases, color vision testing is done to determine how well your optic nerve works. The optic nerve is the main nerve connecting the eye to the brain. Changes in color vision can often be the first sign of a vision problem.

Normal Values

Normally, you will be able to distinguish all colors.

What abnormal results mean

This test can determine the following color vision problems:

Achromatopsia - complete color blindness, seeing only shades of gray
Deuteranopia - difficulty telling the difference between red/purple and green/purple
Protanopia - difficulty telling the difference between blue/green and red/green
Tritanopia - difficulty telling the difference between yellow/green and blue/green)

What the risks are

There are no risks associated with this test.

Review Date:1/21/2009
Reviewed By:Paul B. Griggs, MD, Department of Ophthalmology, Virginia Mason Medical Center, Seattle, WA . Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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