Unsettling: You are just sitting there when your glasses pop a lens and you sense a Very Very Very small screw fall into the darkness beneath your desk. And you can't see well any longer.
It's the human equivalent of throwing a horseshoe. You'll live, but not well.
I somehow managed to find the screw and screw it in using my wits and a fingernail.
I also got a SPAM that advertised a special deal on carpet that was actually tax deductable.