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

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

How the test is performed

Your health care provider will ask you to sit in a comfortable position, and the test will be explained 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.

You will cover one eye, and the tester will then show you the test plates, holding them 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. The more familiar your child is with what will happen and why, the less anxiety he or she will feel.

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

By using these plates, your health care provider can detect, classify, and estimate the degree of defect in your color vision.

In some circumstances, color vision testing is used to evaluate the function of the optic nerve. The optic nerve is the main nerve connecting the eye to the brain.

Normal Values
Normally all symbols are distinguished.

What abnormal results mean
This test can determine the following abnormalities:

 
• Protanopia (difficulty distinguishing between blue/green and red/green)  
• Deuteranopia (difficulty distinguishing between red/purple and green/purple)  
• Tritanopia (difficulty distinguishing between yellow/green and blue/green)  
• Achromatopsia (complete color blindness, seeing only shades of gray)  
• Optic nerve difficulties

What the risks are
There are no risks associated with this test.

Medical Encyclopedia

All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.