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, or "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 about 20 feet away. The device contains lenses of different strengths that can be moved into your view.

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 how long they should be left out before the test.

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 test to determine if a person has normal vision.

When a person complains of blurred vision, this test can help determine the extent of poor vision. It can also be done to monitor a person who is being treated for an eye disease.

The test is used to prescribe glasses, if needed. It also will determine if you need bifocals.