What is the meaning of 20 20 Vision?
Furthermore, why is it called 20/20 Vision?
Snellen charts display letters of progressively smaller size. "Normal" vision is 20/20. This means that the test subject sees the same line of letters at 20 feet that person with normal vision sees at 20 feet. 20/40 vision means that the test subject sees at 20 feet what a person with normal vision sees at 40 feet.
Considering this, what is perfect eyesight?
Visual acuity of 20/20 is considered “perfect vision” because no aids are required to see better, but people can have better than 20/20 vision. Many young people are able to see letters smaller than the general “20/20” size.
Most government agencies and health care institutions agree that legal blindness is defined as a visual acuity (central vision) of 20/200 or worse in the best seeing eye or a visual field (peripheral vision) that is limited to only 20 degrees.