Visual acuity
Visual acuity is a measure of how well a person can focus on a distant object. To test visual acuity, the person may read letters or symbols on a wall chart (Snellen test) 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. A person who can read what people with normal vision can read at 20ft has 20/20 (6/6) vision. The larger the second number, the worse the vision.
- If vision is 20/40 (6/12), the person can read at 20ft what people with normal vision can read at 40ft.
- If vision is 20/60 (6/18), the person can read at 20ft what people with normal vision can read at 60ft.
| Author | Jeannette Curtis |
| Author | Caroline Rea, RN, BS, MS |
| Editor | Kathleen M. Ariss, MS |
| Editor | Susan Van Houten, RN, BSN, MBA |
| Associate Editor | Tracy Landauer |
| Associate Editor | Pat Truman |
| Primary Medical Reviewer | Patrice Burgess, MD - Family Medicine |
| Primary Medical Reviewer | Adam Husney, MD - Family Medicine |
| Primary Medical Reviewer | Kathleen Romito, MD - Family Medicine |
| Last Updated | May 25, 2007 |
WebMD Medical Reference from Healthwise
Last Updated:
May 25, 2007
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