Do you have any suggestion how to keep faces from freezing with glasses?

[Munnerlyn]

Do you have any suggestion how to keep faces from freezing with glasses while taking photos in cold nights?

We'll probably be out there taking photos when the temperature is -25C or colder. I have a balaclava to keep my face from getting too cold. But there is a problem: the balaclava directs my warm breath upwards to my eye glasses, causing the glasses to fog and making it impossible to operate a camera or even to see the sky clearly.I don't wear contact lenses and definitely need my prescription eye glasses to see.

[Roxboro]

I found that I had to concentrate to put my mouth in such a way my breath was directed downward (combined with a mask or scarf that keep an open space below the chin so the breath can escape and not be reflected upward.); some for nose opening...

[Munising]

There are anti-fogging sprays you can buy that may help, although I have to admit, I've not had great luck with them.