Like most of us - my reading has suffered greatly (and typing - it really didnt used to be this bad).. I used to devour books and could lie motionless and read something I liked cover to cover (was a nice change after a hectic day or week of regular life) as others have said too - since I got sick all the other feelings of discomfort disturb my concentration, I cant lay still, just super uncomfortable - I read in very small spurts unless I'm having a "good" day - and reading on the screen for me even harder - dont know why.... maybe too since I dont have the challeneges that were personally satisfying with work etc. any more my mind is more at unrest too.....
In any case - I agree - chronic illness does affect concentration!
(also, investing more then 2 dollars in drug store reading glasses and getting my eyes checked for real one of these days might help!) I'm not a spring chicken any more!