Vision Question: What does it mean to have 20/20 vision. What do the numbers mean?

Question

I know that 20/20 is always the standard by which people say they have good eye sight but what do the numbers mean?

I wear glasses and I was just at the eye doctor for a battery of tests. I asked what my vision was and he said about "20 over 800"

Can you help me understand?

* the more simple the explanation the better*

Thanks all

Answer 1

The 20/20 means you can see at 20 feet what a "normal" eye should see at 20 feet.

20/800 means you have to be at 20 feet to see what a normal eye can see at 800 feet in theory.

That would be your UNcorrected vision. You are most likely 20/20 with your glasses on.

EDIT ****

Diane is very confused...I sure hope she doesn't work in the optical industry.

Answer 2

20 / 20 means that something 20 feet away looks like it's 20 feet away.  20 / 800 means that something 20 feet away looks like it's 800 feet away.

Answer 3

There is no "20 over 800"!

The big "E" is 20/100. If you can't see that, there are different tests to do from there.

They always say that 20/20 is perfect vision, and that is what they go by. The 20 is measured at what you see from 20 ft. So, when you are reading that eye chart, the lines have different size letters to see what you can see at 20 ft. They start off big and get smaller as you go, the smallest being 20. So if your vision is say, 20/50, that means that the fifth line is the smallest that you can read clearly from 20 feet. So it means that you can read a line on the chart with those size letters where someone with 20/20 vision could read the bottom line from 20 ft.

In other words, someone with 20/20 vision can read what you are reading at 50 ft away, but for you to see it you can only be 20 feet away.

Okay, I just confused myself! Do you get any of that?