I mentioned a few days ago my need for enhanced protection against UV because my opthamologist noticed the beginning of cataracts. It turns out that not all sunglasses are equally effective against UV. There is actually a standard called UV400 that specifies that nothing from 400 nanometers down will get through--providing a barrier to both UV-A and UV-B radiation. I gave up on the clip-on idea because so much light comes in around the clip-on frame.
What I found at Cabela's was a brand called Cocoons, in a form intended to fit over your prescription glasses. These have side protection as well, to prevent light from coming in on the sides. I guess it has been a while since I bought sunglasses, so I was a bit surprised at paying $44.95. They seem well made, and while I don't look completely goofy wearing them, I don't look particularly cool wearing them, either. (Not that there is much danger of me ever looking cool.) I do try to always wear them when I am outside in daylight now--even it is looks a little odd.
The only annoyance was that when I went to buy them, they had several sizes on display. I determined that I needed Large. In the rack underneath, the various columns were labeled with size: M, ML, L, XL. I grabbed a box out of the L bin, assuming that all these boxes were in fact L. Nope. I discovered when I got home that this was a box labeled (correctly) as ML, so I had to return them for the right size.