You know... A few years back, I had this problem where I'd basically roll my eyes. My parents thought I had some neurologic disease, she even found some site with my "symptoms" and what not. Well, pretty soon after I got myself a LCD, and guess what, my symptoms decreased.
I have noticed them coming back since I got my new display, and I beleive it's from how bright it is. That or I'm wondering if the faster responce/sharper images cause the problem.
And if your wondering about actual vision problems, my vision actually improved a bit over the last few years! Not to say using a computer is "good" for you...