For all of you who haven't thought of this before (I'm sure many of you have):
If you have an appointment with the optometrist soon, don't miss out on the opportunity to snatch up a pair of the post-mydriatic sunglasses (given away to those that have had their pupils dialated, which is done during routine checkups) that can be used for backpacking with 5 minutes of modification. With a little trimming around the edges, two holes punched on either end (with a hole punch) and a bit of cord or string of your choice, you've got a pair of 0.1 oz shades that will eliminate side glare, offer 100% UV protection, and will fit under glasses if need be. The glasses can be rolled and tied with the attached string for packing, or they can easily be fitted into a 0.2 oz (6 grams on my scale) film canister for a bit of extra protection (although I dont think the glasses are capable of being crushed, and so I probably wont use one).
If you don't have an appointment anytime soon, try walking in and simply asking for a pair. All they can really do is say no. Thanks,