Glasses on their own provide limited protection. If you can fit you fingers in behind the frame and touch your eyeball, then high speed sharp things can get in there too.
So I wandered down to the local optician, who had a selection of about 5 pairs of safety specs at about €200 a pair. Ouch.
This calls for a bit of surfing.
I found http://www.opticsplanet.net/ who even listed the temple size for the frames (handy when you have a 64cm head size) and I got a pair of Wiley X Brick RX prescription glasses made up for €120.
They have removeable foam padding for when you are sanding and want to keep dust out, and on hot days when you are more concerned with high speed flying pieces of blindness, you can take out the foam, and they fit nice and closely around your eyes sockets.