A while back I had worse eyesight on one eye than the other, and the result was that if I closed just my good eye, after a few seconds, I'd see nothing with bot

A while back I had worse eyesight on one eye than the other, and the result was that if I closed just my good eye, after a few seconds, I'd see nothing with both eyes, because even though my bad eye was still seeing the world, my brain was so used to the opposite being true it sketched in the darkness from the closed eye. What seems to happen is your brain learns to ignore the signal from one of the eyes if the other is "malfunctioning" somehow.