One for the RD's regarding Glacier Glasses. For goggles, I normally go for a Cat 0 or Cat 1 lens as these don't reduce the light as much as cat 2 or 3 lenses. So ideal for low light/night. Also a yellow tint helps improve contrast. There are various tints that do different things, so worth researching. Most Glacier Glasses will be a Cat 2 or 3 lens. You can get goggles with Cat 1 and Cat 3 lenses, the Cat 3 normally clips in. If you're only going to use them for the Spine then a cheap pair of Cat 0 such as the Bolle Mojo's or Julbo Plasma's.
Cool, cheers Paul. I'll check out the goggles suggested.
As Paul says, goggles please and change the lenses. Glacier glasses are good, and you can use them instead of sunglasses but even a cheap pair of goggles offers incredible protection. It's to protect your eyes from from damage caused by the turbulent winter weather, scratching etc than UV so changing the lenses is the most sensible option.