Just wanted to post a universal 'why'.
Why do eyeglasses continually break?   I have gone thru two pairs now both ending with the exact same result.   As I am typing, here on my face sits what resembles eyeglasses except one of the arms is missing and the lens has been strategically hand crafted to stay in place with a small wire.  
That tiny screw never did fit back into place as it once did.  When I bend over now to pick something up, off they fall to the ground again while the lens goes flying across the room.
Is this the way all glasses end up, I wonder?   I suppose I would not have stepped on them to begin with had I been able to see where I was going.
(updated- I took a nap and upon waking there sat my eyeglasses with two sturdy lenses and another attached arm.  My husband is the best person, always looking out for me.  So, I felt pretty bad when within a couple hours I somehow managed to again be walking around the house with my one armed, one lensed glassware.  Yeh, they inadvertently received my gentle touch and 'tada' back to looking like a crazed professor.  So, for now...contacts.)