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Vision Tests

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Confrontation tests and Amsler grid tests take just a few minutes. More thorough visual field testing that uses perimetry and tangent screens can take more than 45 minutes when both eyes are tested.

Color vision test

People who have normal color vision are able to distinguish the colored numbers, symbols, or paths from the background of colored dots.

If you are not able to distinguish some or all of the colored patterns from the background, you may have a color vision problem. You may be able to pick out some patterns of colors but not others, or you may be able to pick out patterns that are different from a person with normal vision, depending on what type of color vision problem you have.

This test takes only a few minutes.

Many conditions can change your vision test results. Your health professional will discuss any significant abnormal results with you in relation to your symptoms and past health.

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

  • Your ability to understand or follow instructions. Some vision tests cannot be done on babies, small children, or people who cannot understand or follow the instructions.
  • Your ability to stay alert and respond to questions.
  • Failure to wear prescribed eyeglasses or contact lenses.
  • Poor lighting.

What To Think About

  • Eye charts that use pictures or symbols (such as an E chart) may be needed to test children or people who cannot read. Vision tests are also available for babies and young children.
  • A complete eye and vision evaluation also includes a physical examination of the structures inside the eye. To learn more, see the topic Ophthalmoscopy.
  • A test to screen for increased intraocular pressure (IOP), which increases your risk for glaucoma, is often part of a routine eye exam. It also is used to monitor treatment for glaucoma. Tonometry can be used to determine whether a medicine is keeping your IOP below a set target pressure determined by your doctor. To learn more, see the topic Tonometry.
  • Home tests for near vision in adults and distance vision in children are available. These tests should not replace a thorough eye examination by a health professional.

Other Works Consulted

  • Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.

  • Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.

ByHealthwise Staff
Primary Medical ReviewerKathleen Romito, MD - Family Medicine
Specialist Medical ReviewerChristopher J. Rudnisky, MD, MPH, FRCSC - Ophthalmology
Last RevisedJune 9, 2011

WebMD Medical Reference from Healthwise

Last Updated: June 09, 2011
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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