Computer screens are something that I'm having issues with as well. I've tried everything (screen brightness, reading glasses, Flux program, computer glasses, etc) and so far nothing has helped.
I had to quit working full-time last year because of this, and my symptoms have gotten better overall after I stopped forcing myself to look at computer screens all day.
So far the only thing that I found as a possibility is issues with how the eyes work together (for example convergence insufficiency). I've tried vision therapy a couple of times, but haven't had any luck so far.
Went to a new neuro-optometrist that was trained by the Vision Specialist of Michigan (
Is it My Eyes that are causing my headaches, nausea, dizziness) and she did a bunch of tests on my eyes and said that my eyes are vertically misaligned and that's why the brain is always struggling. She prescribed me new glasses which I'm going to pick up sometime this week, will let you know how it goes.