I admit that I might be one of the few -- if not the only -- racer whose vision is somewhat less than perfect, but I'll offer this:
I wear glasses to see way down the course -- anything more than about 20 feet in front of me is a tad blurry without those lenses. When the doctor asked why I wanted glasses I said "I ride a motorcycle over 200 mph", and his response was something like "That sounds like a reason for glasses, yup, you're right."
So I got the glasses and I can see the mile markers just dandy. But then the dashboard was a complete blur. I've got a tach and a couple of indicator lights ("shift" and "OH SHIT!") and while I could make out the lights -- the tach was hard to read. A GPS would have been totally impossible to see (I tried it a few times). I noticed, by the way, that I didn't choose to spend very much of my limited concentration on seeing the GPS, but the story needs closure, so here's what I did.
I got a new pair of glasses last year -- bifocals. BUT -- I had the opticians put the reading part of the lens way the heck up higher than normal -- above the midpoint of the lens, in fact. They thought I was crazy when I requested the glasses be ground that way, but now -- when I'm going down the track all tucked in and craning my neck upwards to get my head out of the wind and see down the track -- now the very tippy-top of the lens, which is still for "long" seeing, is where I need it to be -- and the reading part of the lens lets me read the tach (and would let me see a GPS or anything else I chose to put on the dashboard) without moving my head back-and-forth.
I can't use the glasses for much of anything else, what with the reading lens getting in the way if I'm not tucked in -- but they're slicker than soap on a doorknob for racing.
