I have tried a bunch of goggles- best ones are the scotts with the fan. About 150 as I recall.. You may want to try a ski store as they sell more of them than most snowmobile shops. The best alternative is to go get a prescription for contacts.. I have a "compromise prescription" so that I use the same strength lens in both eyes and can see about 20/40 or so. But it is a hell of a lot better than fighting glasses fogging. I used to have a prescription scuba mask that had the lenses cut into the glass- cost me about 500 bucks. I can buy a lot of disposable lenses for that and if your prescription changes you aren't out a bunch of cash...
I have never used their rx system, I have the snap tint turbo goggles and they are by far my favorite. In really fine powder some snow can get in between the lenses is about the only issues I have with them, so I usually ride without the snap on lens in those conditions.
Like 2walla, I also wear soft disposable contacts for sledding only. I tried soft contacts 25 yrs ago and hated them. I tried them three yrs. ago and the technology advancements were amazing. You forget you have them in.
Go pro-vue's snow goggle page and click on the "about fog" button. There are some of the best tips on how to keep your goggles from fogging up on that page.
We are Habervision dealers. Haber has a couple of options for people who wear prescription glasses. The first one is our OTG goggle the Ouzo.
Just slip an Eliminator in them and you are good to go. You may need to run the Eliminator in continuous mode to keep the glasses as well as the goggle fog free. My son found when he wore them with his glasses in the automatic mode that they kept the goggle fog free but did not fully keep his glasses fog free so he simply kept them on all the time and had no problems keeping both fog free.
The other option is our optical inserts. This is an insert that you take to your optometrist to be filled with your prescription. It has a telescoping center post that can easily be adjusted to fit different widths of goggles. You pop it into any goggle and you are good to go. You just have to remember to still take your glasses with you because once your goggles are off your prescription lenses are gone too.
I have been trying to load pictures of the inserts but can`t seem to do it on this thread but here is a link to the thread that we did post pictures of the inserts on: