A baseball hat under the helmet for light rain seems to work, however not much. I have no solution and ride fuzzy. I am particularly challenged on humid/misty nights when the on coming headlights cause a white out - I ride like a school marm, peering over the glasses during on coming traffic and through when it is more contrasting.
I've been debating getting prescription goggles that were mentioned on BF last year but haven't gotten around to searching.
I also keep intending to get cat crap or other goop (a potato had been suggested) but never remember and have relatively few days that it is a problem.