Have you tried a pair of well ventilated ski goggles with double lenses? Also, if you are wearing something over your nose and mouth like a balaclava or scarf, make sure your breath isn't getting deflected up into your goggles.

The pair of Smith goggles I got this year have worked really well. I used to have problems with fogging (icing actually) on the inside of the lenses of my old goggles when it got really cold (like -15 or colder) but these have been great.