20/20 vision - twenty what?

Question

obviously you don't know what it means either

Answer 1

my understanding is that the first number is a base number, which is set at 20 and is considered normal, and the second number is how far away youre standing from the target. a person with 20/30 vision can sees something clearly from 20 feetthat a "normal" person can read from 30 feet. somebody with 20/15 vision has better than normal vision, because they can see something at 15 feet that a normal person sees at 20. i may be wrong, but that's how ive heard it works

Answer 2

20/20 vision means that you have perfect vision as far as how far you can see either corrected or uncorrected (with or without glasses/contacts). If you don't see 20/20 uncorrected the goal is to give you a prescription for glasses/contacts that will get you as close to 20/20 as possible. Other factors play into that though such as cataracts, macular degeneration, retinal tear or detachment, uncontrolled glaucoma can cause vision loss as can uncontrolled diabetes.

Basically when you stand 20ft away from the chart and you can read everything, you have normal vision. If you have 20/40 vision, it means that when you stand 20 feet away from the chart you can see what a normal human can see when standing 40 feet from the chart, and so on (20/60, 20/80, etc).

Answer 3

It refers to eye testing. The Snellen eye chart is typically 20 feet away. If the individual has normal vision he or she can read the chart at 20 feet away. If the person has 20/30, it means he can read at 20 feet what a person with normal vision can read at 30 feet, and so on. 20/200 is considered legally blind in the USA.

Answer 4

20/20 means you're at normal vision range for that test

Answer 5

ive got 20/20 vision
its wats called 'normal', its when u see something 20ft away as a 'normal' person would see it

Answer 6

it is an improper fraction it should say
can you see 1 whole?
but Im not normal, as above.

Answer 7

What exactly are you asking?