Kretzschmar et al. did a study in 2013 that compared reading effort on three different media: a paper page, an e-reader (e-ink) and a tablet computer. They studied eye movement, brain activity and reading speed. The participants also answered a few questions to determine reading comprehension. The interesting thing was that all participants said that they preferred reading on paper, even though the study found no support for it being more effortful to read on digital media. On the contrary, the older participants read both faster and with less effort on the tablet computer, due to the back lighting giving a better contrast, and because of this being better for older eyes.
Summary from UKSG Insights.
I’d be interested to hear about any studies where dedicated e-ink readers have been shown to be inferior to paper for eyestrain or reading comprehension.