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Alternative names Return to top
Eye test - acuity; Vision test - acuityDefinition Return to top
The visual acuity test measures the smallest letters that you can read on a standardized chart at a distance of 20 feet.How the test is performed Return to top
This test may be done in a health care provider's office, a school, a work place, or elsewhere. Stand behind a line 20 feet from the eye chart. Remove glasses or contacts. Keep both eyes open and gently cover one eye with the palm of your hand, a piece of paper, or a paper cup while you read out loud the smallest line of letters that you can read on the chart.
If you are not sure of the letter, you may guess. This is repeated with the other eye. Repeat the procedure while wearing glasses or contacts.
How to prepare for the test Return to top
No special preparation is necessary for this test.How the test will feel Return to top
There is no discomfort.Why the test is performed Return to top
The visual acuity test is a routine part of an eye examination or general physical examination, particularly if there is a change in vision or a problem with vision. In children, the test is performed to screen for any visual problems.Normal Values Return to top
Visual acuity is expressed as a fraction. The top number refers to the distance you stand from the chart. This is usually 20 feet. The bottom number indicates the distance at which a person with normal eyesight could read the same line you correctly read.
For example 20/20 is considered normal. 20/40 indicates that the line you correctly read letters at 20 feet that could be read by a person with normal vision at 40 feet.
What abnormal results mean Return to top
Abnormal results may indicate that you need corrective lenses to obtain normal vision, or may indicate an eye condition requiring further evaluation.What the risks are Return to top
There are no risks. Update Date: 8/18/2003 Updated by: Edward B. Feinberg, M.D., M.P.H., Professor and Chair, Ophthalmology, Boston University School of Medicine, Boston, MA. Review provided by VeriMed Healthcare Network.
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Page last updated: 28 October 2004 |