I played with that, It did not help a great deal.
What bothers me is the lack of sharpness that the PDF readers presents when it comes to rendering different documents. I also played with what I could to adjust that. Played with the contrast and brightness, color saturation, background and text color ...nothing helped.
Another issue is that sometimes I seem inclined to see the small cells (grid) that the monitor is made of... More with the new LED monitors less with the OLD LCDs.
I reed a lot about it.
Another issue seem to be that a wider monitor seems to be more distracting and not very helpful when focusing on the text. The efficiency improved dramatically when I got my first ereader. I could only explain these when I read Carr's book "The shallows...What internet is doing to our brain"... now I am entirely sold to reading on ereaders as a compromise between paper and tablet/PC