Getting a massive scrach on one's glasses and having no idea how it got there.

Thats why I went contact lens years ago, I'd always end up destroying my glasses. These days if you break a lens its not big deal. Mind you years ago I broke a gas permable in my eye and cut my eyeball. Had to spend a month with a patch on, lots of YoHoHo comments. It hurt. the pain not pirate gags.
Looks like they've been dragged across something abrasive.