My definition of twenty twenty vision? It's being able to see a size twenty speck on the surface of the water at twenty feet.
The classic eye chart used by optometrists is of little use to a fly fisherman. Who reads while they're standing in the stream anyway? I have however seen and heard guys yelling into their cell phones, fly rod tucked under an arm while knee deep. Maybe they should see an audiologist and have their ears checked.
Instead of the eye chart with the little letters, I propose one with rows of flies. We'll start with something big, maybe a bomber. Or, one of those foamy things with legs sticking out all over. Make it pink, then we can check for color blindness too.
Next, a steelhead skater or two. Can't see it at twenty feet? Don't matter. Don't have to. Just cast and hang on. You'll know when you've got one when you get yanked into the river headfirst by a marauding steelhead. Might as well check ones coordination while we're at it.
A few hoppers are in order too. Don't use 'em much, but they're still nice and big. I like the deer hair ones, but, those foam things are ok.
I'll omit beetles. Even a twelve or fourteen rides flatter in the surface film than a road killed possum. Just goes to show that size doesn't matter.
Next, mid-sized stuff. How about a row of Humpies or....Goofus Bugs? I've always liked the sound of that. Wait. They're the same fly. Three more deer hair fibers don't change the pattern.
Now let's get down to business. The middle of the chart.
How about some run of the mill sixteens and eighteens. Maybe some Catskill dries, an Adams, some sort of caddis. We can cheat a little and put a parachute post on them. You pick the color.
Midge time. Let's start with twenties. Can't see 'em at twenty feet? Or maybe you can't see 'em at twenty inches? That's a different problem. Your arms are too short.
And for the degenerates among us, the itty-bitty stuff. Fall blue winged olives. Not the monster sized ones that hatch in the spring. Twenty-two's. Ever been to the Henry's Fork in October? Corrective eyewear means strapping an electron microscope to your head to see the little buggers.
Twenty-fours? I've got 'em. Seriously. You've heard of no-see-ums?
I've read that there's hooks as small as thirty-two's. Guys who use them don't spend much time fishing though. They're too busy looking over their shoulders for men bearing straight jackets.
And, there you have it, a practical eye test for the fly fisherman.