I wear riding glasses on the bike as i don't like a visor. Finding decent ones which don't steam up at low temps or in the rain can be difficult. The old traditional style goggles steam up or any pair I've tried over the years do.
What I've found is it's about air flow. The problem is if air can't flow across the inside of the lens they'll steam up as you have heat from the body meeting a cold lens, the same as with a car windscreen, so airflow is necessary. Of course I want the glasses to protect my eyes from wind and rain so there's a problem right there.
The solution is to try various types over the years until ya get the right pair then run out and buy some more of the same as spares, before they're discontinued. The ones I have now work quite well and I have two pairs. I had to mod them by cutting out some rubber linings which kept them wind and waterproof but also prevented the necessary airflow inside, which doesn't hurt my eyes but does prevent fogging even though rain will come in. They work. They will fog when I stop the bike so I have to pull out to the tip of me nose away from my eyes until I move off again, then I can readjust them.
I tried all sorts of tricks over the years like Fairy liquid etc non of which worked. I did try one thing, exactly what it was I don't remember now, which worked but it distorted my vision which is no good when riding a bike.
So it's about fit and ergonomics which dictate air flow around the inside of the lens. How any of that helps you as a walker I know not but maybe it's given ya something to go on.
Mountaineers in sub zero conditions wear goggles though. Obviously not the Biggles style goggles folks of old wore on bikes though. They are pretty big and are designed to allow air in around the top while protecting the eyes. Obviously there's no rain at sub zero temps.
For anyone who watches ''Worlds greatest motorcycle rides'' on The Travel Channel on Freeview... The presenter Henry Cole wears a brand of modern goggles I haven't seen before. He takes those same goggles all around the world with him on his travels so I'm assuming they work well. He is an experienced biker so it's hard to believe he would value them as he does if they were prone to steaming up...
http://www.travelchannel.co.uk/series-info.asp?series=World%27s%20Greatest%20Motorcycle%20Rides&ID=1544#.UpgVu4YmySo
Hope some of that helps, sorry if it doesn't.