I love reading on a PC, but find it uncomfortable to use the full screen. I adjust the size to about 1/2 or 3/4 of the screen, so that my eyes seem to have less strain moving back and forth the whole width of the screen.
I prefer the eReader software for reading on the PC. It allows you to hide all of the superfluous buttons and menus, and that makes the page more pleasant to view.
A lot of thought and analysis has gone into making this easier on my eyes. Maybe too much thought and analysis bordering on obsession??