do e-readers cause more eyestrain than paper and ink? (it depends)

In 2010 I wrote a blog, Why I Bought the Kindle Instead of the iPad, which listed the reasons that I had selected the simple black and white Kindle (E-ink technology) over the iPad, Nook, Sony, and other dedicated E-readers (all using LCD backlit technology). At the top of the list was the prevailing wisdom that E-ink and paper-and-ink cause less eyestrain than LCD during longer reading periods.

(Incidentally, it is hard to believe that the tablet format was new at the time! The first iPad was introduced April 3, 2010.)

I've continued to advise people to purchase a separate, inexpensive, dedicated E-ink device for long form reading. But when someone recently challenged me on this issue and asked where I got my data that LCD backlit screens increase eyestrain, I had to admit I couldn't remember where I got the information and that I had never personally read a primary research piece.

 I was delighted to find a fairly recent (December 13, 2013) peer-reviewed journal article, E-Readers and Visual Fatigue (Kevin Paterson), which is available to you in its entirety with compliments from the National Library of Science if you want to go through the design, methodology, and data of the study to draw your own conclusions.

And just in case you were wondering, with the explosion of digital reading, whether it be on E-reader devices,  smartphones or computer screens, there is a scientific name for eyestrain caused by digital reading: Visual Fatigue Syndrome (VFS).

So do e-readers cause more eye strain than E-ink or paper-and-ink reading?

The results were based on two objective measures - BPS, blinks per second and CFF, critical flicker
frequency (those moments when separate visual stimuli fuse together and appear as a single stimulus), and a single subjective measure of VFS, the subjects' own perception of six post-reading feelings: dizziness, headache, eyes feel funny, can't see as well, eyes feel tired, and numbness.

The results were conclusive. (And click on the link above if you want more details.)


CFF - With paper-and-ink or E-ink, subjects still saw separate flickers as separate - with LCD there was much more fusion, which means a drop in sensory perception function.

BPS - We blink less when we read, no matter what the format. So if you read, you're going to blink less, which is not good. Less blinking means poor tear film quality, stress to the cornea, and often results in dry eye. There was no difference in the BPS for E-ink and paper-and-ink but dropped by a third with an LCD device.

VFS - The subjects' responses showed that E-ink had slightly higher levels of perceived fatigue than paper-and-ink - though neither was very high - but with LCD reading the fatigue factor was about 70% higher.

So much of the technological advance in the digital world is designed to decrease the number of devices we need to carry. I'm all for that. But based on Paterson's study, I've decided to stay the course I took in the Fall of 2010 and use a tablet for visual entertainment and light productivity chores, and hold onto my inexpensive Kindle Paperwhite for long form reading.