Another vote for the Gnass cases.
In addition th ethe Gnass case, if you suffered a "scratch" then I would seriously evaluate how you pack your backpack. I have hiked many miles with my gear and never scratched a lens. I have suffered a slight rub to the front element of a lens, due to the flimsy lens caps that come with modern lenses. One of the best thinks you can do to protect the glass surfaces are replace the manufacturer's lens caps with the more ruggered types made by S. K. Grimes. Since I replaced mine, I haven't had any further problems.