20/20

When the eye is considered in focus and able to accurately view objects from 20ft away.

The standard metric used to determine if someone has achieved “normal” visual acuity. When your eye has a nominal performance of 20/20 vision, your vision is said to be in focus and accurately able to view items 20 feet away.

How 20/20 Vision Impacts Vision

With 20/20 vision, the human eye is able to separate lines that are spaced 1.75mm apart at 20 feet away. When using the expression 20/40 vision, 20 would represent the distance in feet between you and the chart. The 40 means that the you can read the eye chart from 20 feet away as well as a normal person could read the same chart from 40 feet away. For example, a vision of 20/40 would be half as good as 20/20 vision. Keep in mind, 20/20 vision is not necessarily the best possible visual acuity you can have, but rather the standard for “normal” vision.