When are you Legally Blind - Approximately ten percent of those deemed legally blind, by any measure, have no vision. The rest have some vision, from light perception alone to relatively good acuity. Low vision is sometimes used to describe visual acuities from 20/70 to 20/200.
What is 20/20 Vision - To better understand visual impairment we need to first look at what 20/20 vision is. This is a term that is used express the sharpness of ones vision in measurement at the distance of 20 feet. What this means is if you have 20/20 vision you can see with clarity at the distance of 20 feet. Take for instance those with 20/60 vision. They must be as close as 20 feet to see what a person with 20/20 vision can see at 60 feet.