20/20 vision

[fairy!]

I understand what this is... but if after an eye test, you are told that you have 20/20 vision, does that mean you can just about make out what you're looking at or, as I have always assumed, it's pin-sharp?

[PinkFizz]

I though it meant your eyesight was perfect.

[n00dles]

It does Pink...

I used to have 20/20 vision (fighter pilot - in my younger days) lol...but unfortunately now need specs for reading...

Your eyes are Perfect with 20/20 fairy!

[fairy!]

Right... so if I can read the line on the eye-test chart, but it's not pin-sharp, I don't have 20/20 vision??

[kempie]

The Snellen fractions, 20/20, 20/30, etc., (mtric equivalents 6/6,6/9, etc.) are measures of sharpness of sight. They relate to the ability to identify small letters with high contrast at a specified distance. They give no information about seeing larger objects and objects with poor contrast (such as steps and kerbs); it does not represent the quality of vision in general.

Contrary to popular belief, 20/20 is not actually normal or average, let alone perfect, acuity. Snellen established it as a reference standard. Normal acuity in healthy adults is one or two lines better. Average acuity in a population sample does not drop to the 20/20 level until age 60 or 70. This explains the existence of the two lines smaller than 20/20: 20/15 and 20/10.

[Hans_Olo]

Agree with Kempie - 6/6 is metric equivalent of 20/20 - 6/5 is better and a lot of people can read this - it is distance vision not close vision this represents - also UK driving regulations are the equivalent of 6/9 or better in 1 eye an 6/12 in the other and that is for lorries and buses - cars it's between 6/9 and 6/12 in 1 eye

[robbo82]

I always remember I was aked a quiz question years ago that went something along the lines of 'true or false: 20/20 vision means you have perfect sight'. I said true and was annoyed it was wrong. Now I know why...