30 year optician here guys. Here's my take on this. Everyone should definitely wear glasses with polycarbonate lenses, even if you don't have an rx. They are the most impact resistant material out there. There are tons of good quality sport style safety glasses (non rx) out there for very reasonable prices. I made myself a pair of transitions lenses and wore them for deer season up here one year. Didn't like 'em. They stayed too dark, especially if there was any snow on the ground. Made it hard to see back in the woods.
Yellow lenses will brighten things up. Good on a cloudy overcast day. I'm a big believer in anti reflective coating, which usually isn't found on the cheaper glasses. It helps reduce eye strain a lot.
As for bifocals, if you want a pair with bifocals I'd suggest lined bifocals for a couple reasons. 1) Your optician can mount them very low in your frame. This keeps the bifocal out of your way when you're down on the stock lining up a shot. You will have to look into the very bottom of the lenses to read. Basically you'll just use this to fill out a deer tag, but not much more than that. The other reason to go with a lined bifocal in stead of a progressive (no line) bifocal is that the progressives can't be fit low in the frame, than they have noticeable peripheral distortion. You will find yourself turning your head farther to see things off to the sides as the outer areas of the progressive lens have that distortion.
What I do is run my self a pair of single vision lenses for distance in a flat black aviator frame. I wear these for hunting and carry a couple pair of throw away readers with me in my pocket.
Get something big enough to cover up your eye socket. An aviator shape or the popular sports shape wrapped glasses.
You only get one set of eyes guys. Take good care of them.
