Like Dianyla, I have Rudy Projects with Rx prescriptions. Took me an age to figure out how they clipped in, as they didn't come with any instructions...

I found them pretty good, took me a while to get used to, but found the vision better than contact lenses. I find contact lenses tricky... Just can't seem to get used to them.

I have another pair of sunnies called Ryders which I bought because they looked cool (not sure if you can get them in the US), but they don't seem to sit on my nose like Rudys do. Rudys really perform, and they are expensive, but my friend bought his pair off Ebay and got a real bargain. Whereas I bought mine off the LBS and they were pricey.