[Saintly]

I'm guessing that there is only one bar gount through his nose. that bar (at the top of the glasses) would have a loop or closed hook of some type. The glasses are then hung on the hook and rest on the nose pads.
The hook would also have a square edge to alow some directional control of the glasses.
Useing this method the glasses would be easly removable (with just the nose bar left in place) and they would probbly easly come off if you banged them. you could have multiple sets of lenses / sunglasses.
I doudt i would use a set tho.