Kindle parper white, or later will make reduce the eye strain. Actually, the problem is that the
blue-light emitted from the screens(iPhone, iPad or iPod touch) causes eye strain, even some eye diseases like xerophthalmia.
http://mashable.com/2012/03/19/ipad-...ay-eye-strain/
If you still want to use an Apple device to read, here are some tips for you:
1. Use blue-light protection app on your smartphones.(Android:
https://play.google.com/store/apps/d...ghtfilter.free),
2. Reduce your time on playing computer games, watching TV etc.
3. A pair of eyewear like Taime computer eyewear(
http://www.halovis.com) that can filter UV and blue-light is your best choice.