Our optomistrist takes digital pictures of the various choices and puts them onto the computer to look at!
And if you are nearsighted, it's a good idea to bring a camera with you and take pictures of yourself wearing the glasses you like. I'm pretty nearsighted, and find that it's hard to judge what glasses look like on me when trying them on because I can't see that clearly!
This is sort of off topic, but I get all of my glasses from Zenni Optical (online). All you need is your prescription, and they literally have thousands of pairs of glasses to choose from-and CHEAP!! I got my last two pairs for $20 a piece. The downfall is that you don't get to try them on, but if you know the style you want then its awesome! Plus you get to have multiple pairs without having to break the bank.