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Refraction test


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Definition

The refraction test is an eye exam that measures a person's prescription for eyeglasses or contact lenses.


Alternative Names

Eye test - refraction; Vision test - refraction; Refraction


How the test is performed

This test is performed by an ophthalmologist or optometrist. Both of these professionals are often called "eye doctor."

You sit in a chair that has a special device (called a phoroptor or refractor) attached to it. You look through the device and focus on an eye chart 20 feet away. The device contains lenses of different strengths that can be moved into your view. The test is performed one eye at a time.




The eye doctor performing the test will ask if the chart appears more or less clear when different lenses are in place.


How to prepare for the test

If you wear contact lenses, ask the doctor if you need to remove them before the test and for how long.


How the test will feel

There is no discomfort.


Why the test is performed

This test can be done as part of a routine eye exam. The purpose is to determine whether you have a refractive error (a need for glasses or contact lenses).

For people over age 40 who have normal distance vision but difficulty with near vision, a refraction test can determine the right power of reading glasses.



Review Date: 02/10/2011
Reviewed By: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; and Franklin W. Lusby, MD, Ophthalmologist, Lusby Vision Institute, La Jolla, California. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org).

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