Many eyeglass wearers have done it: taken our glasses off and wondered how we can even see through them. They're dirty, smudged, and foggy. Sometimes it seems like no matter how much you clean eyeglasses, they’re still full of fingerprints and smudges. Dirty eyeglasses are more than just annoying, though. Trying to focus through unclean lenses can create headaches and eye strain. The problem is that...