I'll kick off the new vendor column with one of the few opticians that do period glasses, The Grand Spectacle.
At time I write this, I think the Grand Spectacle is the only vendor that specializes in period glasses. The owner, Richard Buchanan, mostly does frames from the 1800's, but some of his frames can probably be used for WW1 reenacting too. I've heard a ton of great things about The Grand Spectacle, so it seems that he's a good solid vendor to deal with. Besides that, he's mentioned on almost every comprehensive vendor list on the various reenacting sites I've surfed.
The Web site is catchy, but a little confusing as far as navigation. Be very careful as you surf the site, or you'll miss some nice mouse-overs that show close-ups of his products. A nice addition to this site would be some education on how to find and choose appropriate frames for reenacting. I know it's a subject I could stand to know about.