O.K. This is OT. Tongue in cheek, too!
Consider one (like me) who has a less-than-perfect visual system -- however one defines that. Most of us have imperfect visual systems -- whether we realize that or not. Certainly if reading ever gives one a headache then one has a less-than-perfect visual system. You are reading late at night a challenging book. You say "Man, I just can't read this anymore, time to go to bed!" OK, but WHY -- what was the problem? Glasses prescription off? One eye went lazy? Secondary eye just went dominant? Eye tremor? One eye stopped tracking? Too much emotional content? Too much intellectual content? Now add in the effect of the reading device, say a 600 dpi printed text vs. a 100 dpi LCD backlit display: Screen door effect? Lack of sharp edges for the eyes to focus on? Lack of sharp edges for eyes to converge on? Color bifringement problems? Etc. One can say "Oh, I was just tired" -- yes, but *what part* of the display system made what part of *your* "visual processing system" tired? For many of us the low resolution backlit color LCD displays are MUCH more tiring than a high resolution laser printout, or eInk display. I've talked to MANY eInk display users who have told me "well the screen door effect on LCD displays is just too tiring for me." And just as I am writing this on a backlit LCD display system my left eye decided to "check out" and stop focusing...but my right eye continues to work. ;-) Thirty years ago I worked on high-resolution monochrome CRT displays which were absolutely beautiful and easy to read -- not at all like the crap color displays we read on now -- and it sounds like the expectations on color display are now going *down* not up in quality! Certainly when I went to buy a new laptop for one of my teenagers recently I was not even able to buy a laptop nowadays that has the resolution of the display I could get on a laptop five years ago. Bad displays, ugly printouts, ugly formatting, crappy content: equals more tired and less productive readers having less fun and reading less.