My solution is cheaper than postage. For indoor ranges, I'm using $2 3M glasses.
http://www.amazon.com/gp/product/B00166OALC
I have four pairs of The Wiley X "Jake" glasses. Two pair clear, two pair sunglasses accumulated over the past 5yrs, and I still use them all.
The Jake has a pop-in plastic-framed foam gasket that is awesome for wind and dust control. The model is part of their "Climate Control" series. The first time I wore the gasket to our windy, desert-like 3-gun matches I was ecstatic. Everyone else was rubbing their eyes and wiping their lenses down, but not me. They also work well in cold weather, keeping the cold, dry air from whipping your eyes. Also when used on ATVs or boats. The lenses are semi-wrapped and intrude on very little of my peripheral awareness. The frames are ANSI Z87, so I can use them at work. From a functional standpoint I'll be hard pressed to choose a better design for me. I use Croakies Terra Cord on every pair. I can cinch the gasket against my face without discomfort, and the Terras have saved many drops or knocks. Most of the time I don't use the gasket insert.
Head size and nose bridge have a lot to do with all-day, active use comfort. If you're near a metro area you should be able to find a stocking OEM store or optometrist so you can check out at least some of the models and frame sizes. Locally I have an Oakley Vault store, Wiley and Rudy stocking optometrists.
Prone rifle head position is a big consideration.
Pupillary Distance and Offset are also big factors. PD is distance between pupil centers, and the offset is the actual measurement from the bridge of your nose. My pupils have a 1.5mm offset. Make sure the vendor asks for and uses this offset. A sneaky way of getting the RX info is to tell the optometrist your employer is purchasing RX respirator inserts.
One huge advantage to RX is the option to choose anti-glare coating. I don't know why Oakleys, SO and such aren't made with this to begin with. It really helps to cut down on reflections without the shine of mirrored lenses. If I had great uncorrected vision I'd pay to have the lenses coated. I also choose the anti-scratch coating. It does help. My first pair lacked these and it shows.
I keep hearing about the new RX lens curving process. Rudy Project is using it, and my favored vendor is as well.
I get all my RX safety glasses from http://www.rx-safety.com/. No affiliation, just happy with the service over the past 5yrs.
I had one insert system, the Wiley Talon. I didn't like the weight, position or the double dirty effect at the end of a training day (light in your eyes). I had to remove the insert to clean both sides of both sets of lenses. The combined weight was a bit farther out on the bridge of my nose due to insert/eyelash interference.
I wear Oakley Radars actually, I drool over my buddies Pillas. I was supposed to be getting a complete set from them for this season of shooting, and then I'm not. However if you can afford the absolute best, they are certainly them. I thought the Oakley's were clear lenses with no distortion, looking through the Pillas however told a different story. And the frames, oh my god the frames, they are amazing. The quick change lenses the lightness of the frames, incredible glasses.
...and to think today you just have fangs
Rob Engh
BC, Canada
Monovision works pretty well on the range for me. Takes a few minutes to adjust when switching from regular glasses with the monovision lenses and vice versa. I don't really like having special glasses to shoot with though --- sucks getting old. I have heard of some who wear mono full time. I couldn't do that. Much more than a few hours and I think my eyes would rebel. I really think a red dot is in my future.
"Specialization is for insects." -Robert A. Heinlein