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Refraction test - Overview

Alternative Names

Eye test - refraction; Vision test - refraction; Refraction

Definition of Refraction test:

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

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.

Normal vision

Reviewed last on: 2/10/2011
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.

References

Katz M, Kruger PB. The human eye as an optical system. In: Tasman W, Jaeger Ea, eds. Duane's Ophthalmology. 15th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2009:chap 33.

Kaufman JH. Subjective refraction: fogging and use of the astigmatic dials. In: Tasman W, Jaeger Ea, eds. Duane's Ophthalmology. 15th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2009:chap 39.

Scott CA. Testing of refraction. In: Yanoff M, Duker JS, eds. Ophthalmology. 3rd ed. St. Louis, MO: Mosby Elsevier;2008:chap 2.8.

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.

American Academy of Ophthalmology Refractive Management/Intervention Panel. Preferred Practice Pattern Guidelines. Refractive Errors & Refractive Surgery. San Francisco, CA. American Academy of Ophthalmology, 2010. Accessed January 17, 2011.

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.

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