I know what you mean as I've had a lot of visual problems to deal with lately. After my retina surgery, I couldn't see much of anything our of my right eye and it was very disconcerting trying to practice. Not only could I not see the music, for some reason, I couldn't find the right strings and frets consistantly, even if I tried to play without looking. I think there's just such a dependence on being able to see a certain way, that when you can't it really affects ones perception of where things are in space.
Now that my eye has improved following my recent cataract surgery, things have improved and actually I can sit in front of the TV and play really well(??) without looking. Even though there are and have been great blind players, if you're used to using your eyes, it's a challenge when there are changes to your vision. But Sam, it certainly does clarify things when you wear your glasses:lol: