I've found that if you ask the optician for "safety glasses," you'll be told, "they're all safety glasses." What they mean is that they're all safety LENSES. You have to ask for "industrial safety glasses." You can get them with Crizal coating, progressive bi- or trifocals, transitions or photogray self-shading, polarized--all the regular stuff. The frames aren't sexy, but they're half the price of the designer stuff.
You can, as someone mentioned above, get occupational trifocals that'll give you distance vision in the center and near vision at the bottom AND top. They're useful for reading a tape measure overhead.
Photochromic lenses like transitions and photogray won't dim while you're driving. The dimming is caused by the ultraviolet light from the sun, and the laminated glass in the windshield filters out 99% of UV light.