20/20 vision

The term "20/20 vision" does not translate to perfect vision. Rather, the term was coined by eye doctors and refers to what a normal person should be able to see from 20 feet away. People with 20/40 vision, then, can see at 20 feet what a normal person can see from 40 feet away. It is also possible to have vision that is better than the norm. People with 20/10 vision, for example, can see from 20 feet away what a normal person can see from 10 feet away. On the opposite end of the spectrum, the cutoff for legal blindness in the United States is 20/200 vision, meaning you can see at 20 feet away what a normal person can see from 200 feet away.