Refraction

This test is performed by an ophthalmologist or optometrist. Both of these professionals are often called an "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 (6 meters) away. The device contains…

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

There is no discomfort.

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.

If your uncorrected vision (without glasses or contact lenses) is normal, then the refractive error is zero (plano) and your vision should be 20/20 (6/6). A value of 20/20 (6/6) is normal vision. This means you can read 3/8-inch (1 centimeter) tall letters at 20 feet (6 meters). A small type size is also used to…

You have a refractive error if you need a combination of lenses to see 20/20 (6/6). Glasses or contact lenses should give you good vision. If you have a refractive error, you have a "prescription." Your prescription is a series of numbers that describe the powers of the lenses needed to make you see clearly. If your…

There are no risks with this test.

You should have a complete eye examination every 3 to 5 years if you have no problems. If your vision becomes blurry, worsens, or if there are other noticeable changes, schedule an exam right away. After age 40 (or for people with a family history of glaucoma ), eye exams should be scheduled at least once a year to…

Chuck RS, Dunn SP, Flaxel CJ; American Academy of Ophthalmology Preferred Practice Pattern Committee, et al. Comprehensive adult medical eye evaluation preferred practice pattern. Ophthalmology . 2021;128(1):1-29. www.aaojournal.org/article/S0161-6420(20)31026-5/fulltext . Published November 12, 2020. Jacobs DS,…