Elephants and shit.
Elephants, when young, are shown that they cant break the chains that hold them. When they get older and much stronger and capable of breaking the chains they dont. The memory of not being able to break the chains stops them from trying. I think this is true with humans, we are conditioned not to break the chains.
loosing sight
What if when humans have poor eye sight its just a way of evolution trying to show that there is a better way of sensing than eye sight. And we keep trying to fix and maintain our sight and continue to use the less efficient form of senses. Before we can gain higher senses we have to let go of the lesser ones. DOWN WITH GLASSES! DOWN WITH CONTACTS!