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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 in regular lighting, and your health care provider will explain the test to you. You will be shown several cards with multicolored dot patterns. In the patterns, some of the dots will apear to form numbers or symbols.

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 pattern.

Depending on the problem suspected, you may be asked to determine the intensity of a color, especially in one eye compared to the other. This is often tested by using the cap of a red eyedrop bottle.

How to prepare for the test

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

Usually there is a sample card of multicolored dots that almost everyone can identify, even people with color vision problems.

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

Small children may be asked to tell the difference between a red bottle cap and caps of a different color.

How the test will feel

The test is similar to a vision test.

Why the test is performed

This test is done to determine whether you have any problems with your color vision.

Color vision problems usually fall into two categories:

• Present from birth (congenital) problems in the light-sensitive cells (cones) of the retina (the light-sensitive layer at the back of the eye)
• Diseases of the optic nerve (the nerve that carries visual information from the eye to the brain)

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

Problems in the optic nerve can show up as a loss of color intensity, although the test may be normal.

What the risks are

There are no risks associated with this test.

Special considerations

References

Adams AJ, Verdon WA, Spivey BE. Color vision. In: Tasman W, Jaeger EA, eds. Duane's Foundations of Clinical Ophthalmology. 15th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2009:chap 19.

American Academy of Ophthalmology Preferred Practice Patterns Committee. Preferred Practice Pattern Guidelines. Comprehensive Adult Medical Eye Evaluation. San Francisco, CA: American Academy of Ophthalmology, 2010. Accessed January 17, 2011.

Olitsky SE, Hug D, Smith LP. Examination of the eye. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 618.