The breath deflector products out there work great for this. Most new helmets have this built in but the older ones you can add it to. I don't wear eyeglasses but I do wear sunglasses, and have never had a serious problems with fogging.
2002 Arctic Cat ZR 800 EFI
founding member of the Arctic Cat Mind Control Team......you will believe!!

founding member of the Arctic Cat Mind Control Team......you will believe!!