Although I prefer to read on my Kindle, I don't have any problems reading on my iP4 (with white letters on black) for a hour or so at a time. But I really don't enjoy reading black letters on a white background...so I'd change the background first. After that, I would increase the font size - a size that is comfortable on paper may not be the most comfortable size for reading on an LCD.
If that doesn't work, you should consider trying an e-ink reader. They really are quite different from LCDs. I'll post again some magnified e-ink and iPad screens:
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While I'm at it:
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The site for these is
http://www.bit-101.com/blog/?p=2722
You are correct, of course, that e-ink readers require light - and at least for me, a little more light that books; only after replacing my 75w reading light with a 100w bulb did I feel like I really had as much light as I wanted. But, under those conditions, I really do enjoy reading the Kindle more.
(But the light issue is also a reason why I often end up reading my iPhone while out and about).