Sometimes you just learn something that so impresses you that you can’t wait to tell someone. This just happened to me. I should warn you that it really doesn’t take a lot to impress me, but still I think this information could come in handy some day. You could be at a party where you need to impress someone and you can ask, “Do you know what 20/20 vision really means?”
I know most of you think that a person with 20/20 eyesight has the best possible vision. They don’t. They just have what is called “perfect vision” for measurement purposes. In fact people can have 20/15 vision, even 20/10. Also, most of us have the misconception that 20/20 is the measurement of each eye. Not so either. This measurement is called visual acuity and you use the standard vision chart to measure it.
The standard vision chart, that we are all familiar with, is called the Snellen Chart. It was named after the Dutch ophthalmologist, Hermann Snellen, who developed it in 1862. And it’s normally viewed at six feet. So perfect vision is really 6/6. That’s why the chart differs in size, but measures the same thing, like that little one you see through the stereoscope at the DMV.
The first number is always 20. Ever notice that? I don’t think I did. That number represents the smallest letter on the chart that a person with perfect vision could see from 20 feet. Pretty cool, huh? The second number is your “visual acuity.” For example, if you have 20/40 vision, the smallest letter that you can see on the chart from 20 feet away, a person with perfect vision can see from 40 feet away. People who measure 20/10 have some pretty good vision. It means the person with perfect vision can see at 20 feet from the chart, the smallest letter that you can see at 10 feet. If you have 20/200 acuity, you are only able to see the largest letter, the letter “E,” on the Snellen chart at 20 feet. You have some serious problems. You are considered legally blind. We’re talking pop-bottle-bottom lenses.
Why did I find that so amazing? Because I’m a boomer who has worn glasses almost all my life and I’ve always thought that was a measurement for each eye. I had no idea about the 20 foot thing either. Now, I feel enlightened because my eye doctor thought it was valuable enough information to explain to me.
I can remember the first time I put on a pair of eyeglasses. I can flash back to the exact moment in an instant in my mind. That’s probably why they call those kinds of episodes “mind-blowing”. Anyway, I was in third grade. One of those kids that had to sit in the front row in class to see the board and a few feet from the television to see it clearly. My mother was always telling me not to sit so close to the screen because I was getting radiation poisoning.
Finally, when my third-grade teacher called my parents in for a conference, she told them she believed I needed glasses. After the eye exam, which I still find very stressful because I’m never really sure if number one is better than number two, and then they’ll throw number three into the mix, it was determined that I needed “corrective lens”. I suffered from “nearsightedness”. That’s like a death sentence to an 8-year old kid who has never had anything wrong with them.
So, after a week, I went back to Dr. Whitney, for my fitting. He told me to stand at a window and look out at the tree in the front of the yard, about twenty feet away. “Do you see the tree?” he asked. Sure I saw the tree. It was a big tree.
“Okay,” he said, “now put these on.” He handed me the black framed, “four-eyes,” glasses and I put them on. “Now look at the tree he said. What do you see?”
My Gawd. There were leaves on the tree and I could see each one attached to branches that were swinging in the breeze. I can’t explain how incredible it was. I’m sure the eye doctor got his kicks out of watching people “see” for the first time.
So now you know what 20/20 eyesight is. I don’t have it. I don’t even know what my visual acuity is, but if I was to guess, I would say 20/50. I’m pretty near-sighted…about a lot of things.
And just remember now, hindsight doesn’t always have to be 20/20, sometimes it could be 20/10 or 20/15. Sometimes the outcome shouldn’t have been that hard to see in the beginning.