I'm a fellow student For me the opposite is usually the case, as the glare from my computer screen causes a huge amount of discomfort.
What normally sets my eyes off when reading printed text is small font size. Many books are hugely condensed to save paper and weight, with the result that there is very little 'white space' on the page, and that the text becomes very difficult to read.
I also know that some font styles are impossible for me to read for any length of time! I've skipped articles because it just wasn't worth the eye-strain of reading them.
Something else I've noticed is that my posture and my position in relation to the page changes when I move from computer to print. Maybe you are leaning too close to the page? I also tend to move a lot less when reading print, so perhaps you are the same and your eyes are under extra pressure than when they are moving around a computer screen?
If you are photocopying text, it might be worth enlarging it a little so it's easier to read. Some photocopiers are terrible though, and I'd imagine even normal healthy eyes would have a problem reading the copies!
My favourite gadget is my Kindle. It's easier to read than either my computer or print. I transfer PDF articles etc to my Kindle, and I can change font size there easily. Not an option for everyone, but if you have a Kindle it might be worth having a go.
I hope you find something to ease the eye strain, and good luck with you studying!
The eye altering, alters all - William Blake