I have high-impact sport glasses with removeable magnetic lenses. Between the extra lenses (for different light situations) and the height and curvature of the glasses themselves, the usual clamshell cases don't have enough room.  This case is about 30% larger than most and provides enough space to tuck in an additional pair or two of lenses in their own little case. The hinge mechanism is also better than standard--and that's the past that usually fails first. Bright colors make it easy to find in a tote or large bag or briefcase.
If your glasses are valuable and always falling to the bottom of your bag, it's worth trying one of these cases.