What exactly does 20/20 vision mean?
20/20 vision is what we strive for. It is often considered “normal standard vision”. What 20/20 means scientifically is that an individual can identify a letter of a pre-determined size (8.75cm) from 20 feet away.
What if a person’s vision is less than “standard”, say 20/100?
This means what that individual can see at 20 feet, an individual with “standard 20/20” vision can see at 100ft. In other words the person with 20/100 vision needs to be 5x closer to the letter or have the letter be 5x larger to view it.