Many of us think that 20/20 eyesight is perfect, like scoring 100% on a math test. It’s become a popular expression in English, connoting wisdom and experience with phrases like “hindsight is 20/20.”
But it simply means that, from 20 feet away, you can read letters that most people can read. Meaning?
20/20 is not perfect — or even all that good. It’s just average.
Imagine telling your grandchildren “hindsight is average.” It loses some of the magic.
That chart in your eye doctor’s office with the letters descending in size is what determines your visual acuity. (It’s called a Snellen chart.) If you can read all the letters from the fourth line up, from 20 feet away, you have 20/20 vision.
Of course most doctors’ offices are far smaller than 20 feet, so they use mirrors to mimic the distance.
The expression 20/20 also betrays a bias for the imperial measurement system, given that we’re talking about feet. In Canada, we ought to say “hindsight in 6/6”. That would be the metric version of the phrase, 6 metres equaling almost 20 feet. But instead when we say 6/6, many of us think of basketball players.
Do this 20/20/20 exercise every day.
To preserve your eyesight, try focusing at different distances regularly during the day. Like other muscles in your body, those surrounding your eyes need regular stretching for “optimal” performance. Every 20 minutes, spend 20 second staring 20 feet away.
We’ve talked about this exercise before but that’s okay. If you want to be a good Canadian, we suppose you could say 20/20/6 — but that just sounds kind of average.