In contrast to Drowning's experience, I've been using Silverfish sunglasses (same thing as SeaSpecs [http://www.silverfish.com/eyewear/Discount-Surf.html]) for about 5 years. Mine have a bifocal (progressive line-less, actually) prescription. Every once in awhile I get some fogging, but not often. It takes the right conditions. Before going into the water, I apply anti-fog McNett Sea Drops Anti-Fog solution (http://www.leisurepro.com/Prod/AQUASAF.html
-- not endorsing this vendor, just wanted to show you). An important thing about wearing glasses in surf: you want a strap that cannot stretch. If the strap can stretch, the sea can pull them off. Prior to using water sport sunglasses, I used my football ("soccer" not American football) prescription sunglasses for awhile. They have an elastic strap. When I wiped out, they came off. Initially, I was surfing without sunglasses. But, my eyes are light sensitive and following one bright day out surfing, I was snow blind. My head was pounding and I couldn't see. My wife had to take over, drive, etc. I never want a headache like that again. Not being able to see was pretty weird, too.
I also tried some non-prescription swimmer's goggles. It was fun to be able to see when underwater following wipe out, but the goggles blocked all peripheral vision. As a result, I nearly cut in on a few guys that were already on the wave. I could not see them until the last second. Kinda sucked to interfere with their ride.
Not telling you what to do. Just providing info related to topic.