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Have you ever wondered what those numbers on your eyeglass prescription actually mean? Although reading an eye chart is a fairly simple test, it provides a very accurate way to measure your visual acuity or the sharpness of your vision. You'll also need a few other tests, in addition to the results of your eye chart reading, before your optometrist hands you your eyeglass prescription.
Reading an Eye Chart Provides an Accurate Representation of Your Vision
Every eye exam includes a reading of the Snellen eye chart. The chart contains 11 lines of random letters, each line smaller than the preceding line. Patients were once required to stand exactly 20 feet away from the chart, but optometrists use mirrors today to approximate that distance.
The chart is read from the top to the bottom. Each line corresponds to a specific measurement, such as 20/20 or 20/80. If your vision is 20/60, you can read words clearly at 20 feet that people with normal vision can read at 60 feet. Although 20/20 is considered normal vision, some people can see even better than 20/20. If you can read the bottom line of the eye chart clearly, your vision is 20/10.
In addition to reading the Snellen eye chart, you may also be asked to read text on the small printed card that you'll hold in your hands. This test evaluates your near vision.
Other Eye Tests Augment Your Eye Chart Measurement
Your optometrist uses a variety of tests to determine your prescription, if needed, and assess the health of your eyes, including:
Is it time for your annual eye exam? Call us today to schedule your appointment.
American Optometric Association: Visual Acuity: What is 20/20 Vision?
All About Vision: Is 20/20 Vision Perfect Vision
American Academy of Ophthalmology: What Does 20/20 Vision Mean, 11/30/16
All About Vision: What to Expect During a Comprehensive Eye Exam