Most people assume that e-ink e-book readers like the Amazon Kindle or Nook cause less eye strain than the LCD backlit screen like your laptop computer or even the upcoming iPad. A professor breaks this myth:
E-Ink has a very low contrast ratio. Although it can offer an excellent reading experience in bright sunlight, the screens can become uncomfortable to use in dark settings because of the lack of contrast and backlighting on the screen.
LCD screens, meanwhile, have long struggled to offer good viewing angles for reading. Apple’s latest IPS LCD screens include extremely wide viewing angles, but the reflective glass on the screen could be a hindrance in brightly lit situations.
Professor Alan Hedge, director of the Human Factors and Ergonomics Laboratory at Cornell University, said that reducing eye fatigue is less a matter of choosing a specific display than of taking short breaks from looking at the screen. link