That's what I thought immediately while reading the article. Frequent reading on a smartphone must be really horrible for the long-term eye health. Especially

That's what I thought immediately while reading the article. Frequent reading on a smartphone must be really horrible for the long-term eye health. Especially on smartphone, not a tablet. And as far as I know that is actually the reason for the existance of e-books: the e-ink technology makes reading on them similar to reading a book regarding the eyestrain. So if you read in a well lit environment, you should be okay. And I am not sure you can say that about a smartphone screen. I have had a Kindle Paperwhite for several years and have been really pleased by my reading experience so far. The only negative for me is that it is sometimes kinda slow in drawing pages (especially during interface navigation), I don't know whether it is caused by slow firmware, hardware or it is just because of the e-ink technology that causes the interface rendering to be slow; this makes me feel that the device is unresponsive sometimes.