I was watching the news today (a rarity) and there was a story about the side effects of erectile disfunction medications.
Apparently for some section of the population taking drug like Viagra will cause loss of sight. For some people the blood vessels from the optic nerve to the brain, are adversely affected thus blindness.
It's not exactly the whole masterbation causes blindness thing but you have to wonder. If given the choice between sight and the ability to have sex, which would you choose?