Like Bcrash, I have eye problems. My eyes are hard to coordinate because of a weak muscle in my right eye, which causes it to drift to the right. It also rotates the eyeball.
Add to that, my left eye is dominant, but I'm right handed -- cross dominance. The upside is that the vision in my dominant eye is much better than in my non-dominant eye.
When I read, I often slightly close my right eye. This is usually when my eyes are fatigued.
Until I get the surgery to fix this, I can't effectively use my right eye.