For added effectiveness, condition this as a "productivity trigger". Make a rule that you only put on your glasses to work, and before taking a break, you have to take your glasses off. This actually seems to work pretty well. I've made lots of things productivity triggers: rainymood.com, original-flavor Trident gum, specific heavy metal music, and most recently sitting on my bed.
Thus spake Eliezer:
It seems that many here might have outlandish ideas for ways of improving our lives. For instance, a recent post advocated installing really bright lights as a way to boost alertness and productivity. We should not adopt such hacks into our dogma until we're pretty sure they work; however, one way of knowing whether a crazy idea works is to try implementing it, and you may have more ideas than you're planning to implement.
So: please post all such lifehack ideas! Even if you haven't tried them, even if they seem unlikely to work. Post them separately, unless some other way would be more appropriate. If you've tried some idea and it hasn't worked, it would be useful to post that too.