I can't believe no one has mentioned the Chums vs. Croakies issue! If you want to keep your glasses, you better where Chums. I lost some nice perscription sunglasses on Deso in a Duckie in 1987. I was wearing croakies. The Holiday guide said, "man, if I had known all you had was croakies, i'd have lent you some chums". Since then, Chums have kept my sunglasses on kayaking, a paddle boat flip in Little Niagra on Cat at 45,000cfs, and high winds in the Mojave desert.
If you like your glasses, go with chums. When they wear out, mail them back with a good adventure story and they will send you a new pair. I haven't bought a new pair of chums in over 15 years. I do know I have talked at least 20 people into choosing chums over croakies, though.
Thanks for the tip on riverdrops.