What is 20/20 Vision?

In 1864 a test for visual acuity (the clarity or sharpness of vision) was devised by Herman Snellen, a Dutch opthalmologist. Using the eyesight of his assistant Snellen created a chart with letters on it. The “snellen” chart has different sized letters on it and forms the basis of modern eye exams. Snellen decided what a person should be able to see when standing 20 feet away from the eye chart. 20/20 vision is a term which means that you can see clearly at 20 feet what a person with normal vision can see. If you have 20/40 vision this means that you must be as close as 20 feet to see what a person with normal vision can see at 40 feet. 20/20 does not mean “perfect” vision, it only indicates the clarity or sharpness of distance vision. You can also have vision that is better than normal vision, for example a person with 20/10 vision can see things at 20 feet what a normal person can see standing 10 feet from the chart.

Snellen Test Chart

There are other vision skills including peripheral vision, eye coordination, depth perception, focusing ability and color vision that contribute to your overall vision.