Originally Posted by Sil_liS
I...When noticing something in fine detail we are using the cone cells. ...
It should also be noted that the human eye has evolved to have no rods in the very center of the field of vision, that area where we concentrate on detail (read: read text).
Personally, I've read a lot of books and a range of displays; reflective LCD, backlit LCD of varying resolution, and eInk. I've never encountered eye strain issues except when using backlit LCD displays that lack the ability to adequately adjust the brightness. Overly bright backlit displays in dim surroundings give me problems.
I've also found that color LCDs, like all color displays to date, have color fringing issues when black text on white backgrounds gets too small. In order to yield a clean, crisp image of text, a color display must be 2-4x the resolution of a monochrome display.
Another point, in lower light your eye has less "depth of field" (range of distances adequately in focus at one time without the eye refocusing). This makes to precision of your eyeglass, or contact lens, prescription more critical in low light compared to bright light. Lenses that correct your vision for distance don't necessarily have the best correction for reading distance, failed to provide good correction in dim light though they may be good enough in bright light. Anyone
who encounters any eyestrain reading, whether paper or electronic display, should first see their optometrist and have their eyes checked, even those who don't currently where corrective lenses.