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Home > Health Library > Visual acuity
Visual acuity is a measure of how well a person can focus on an object. To test visual acuity, the person may read letters or symbols on a chart from the top down, line by line, covering first one eye and then the other.
A visual acuity score is a ratio comparing the person's performance to that of people who have "normal" vision.
For example, a person who can read what people with normal vision can read at 20 ft (6 m) has 20/20 (6/6) distance vision. The larger the second number, the worse the vision.
Current as of: December 18, 2019
Author: Healthwise Staff
Medical Review:Kathleen Romito MD - Family Medicine & Adam Husney MD - Family Medicine & Christopher J. Rudnisky MD, MPH, FRCSC - Ophthalmology
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