I've recently started wearing glasses on court. Sports ones with a polycarbonate shield infront of a standard RX insert with prescription lenses. I haven't worn glasses since I was a kid and I'm a bit stuck for ways of stopping the lenses from fogging up. This tends to happen when it's cold and when I'm returning serve as I'm crouched forward and my breath seems to fog up the lenses. I know there are some commerically available anti-fogging spray and cloths and some people recommend saliva (this doesn't seem to work for me) also some lenses are already coated with an anti-fog solution (mine aren't.) Any tips appreciated. Also wondering if some anti-fogging solutions can damage prescription lenses or polycarbonate etc.