I think we would be stronger than we imagine. In 2004 I had this horrible thing happen to my eye, half the vision in my right eye was grayed out and in the sun it was BLACK! Before I went to the eyedoctor I resigned myself to the "fact" that this was bad, that I'd be blind in that eye. (and losing my sight is ONE of my fears!) But strangely enough I wasn't freaking out, I wasn't panicking, I just thought, "Well, I'll deal with this, they might be able to DO something".. as it turned out it was nothing serious (posterior vitreous detachment) pretty common in extremely nearsighted people... as time went on it got lighter and lighter to where I don't have a problem indoors anymore (just outside, it's still darkish in that spot, but I got USED to it and don't even notice it anymore because I compensated. So as much as we worry, we are very resilient I think.
(I just read Brick's post and that certainly would be the case for most of us)