Eye Strain and E-Readers

Many of us as children heard the admonition not to sit too close to the TV, yet today we always seem to have our faces poked in some digital device including the increasingly popular ereaders.

In an article for The New York Times “Bits” blog, “Do E-Readers Cause Eye Strain” by Nick Bilton in February 2010, the chair of the University of North Carolina’s ophthalmology department said:

“Most of what our mothers told us about our eyes was wrong. Sitting close to a television, or computer screen, isn’t bad for our eyes. It’s a variety of other factors that can cause physical fatigue.”

Researchers have determined that poor quality paper, like that used for newspapers and many softcover books, offers an inferior reading experience for the eyes when compared to electronic reading devices.

The screens used for various reading devices range from the E-Ink technology incorporated into the lower end Amazon Kindle line of devices to the high resolution screens with which the latest generation Apple iPads are outfitted.

The quality of the viewing experience with the devices varies by environment. E-Ink screens are exceptionally good in direct sunlight where an iPad screen might offer too much glare or be overwhelmed by the strength of the direct, ambient light.

On the other end of the spectrum, however, E-Ink can fatigue the eyes in low light because it offers less contrast. Additionally, many of these less expensive devices do not have screens with backlighting.

Eye Strain and E – Readers: Putting It All Together

Professor Alan Hedge, the director of Cornell University’s Human Factors and Ergonomic Laboratory, was interviewed for the same New York Times article. “While you’re reading, your eyes make about 10,000 movements an hour,” he said. “It’s important to take a step back every 20 minutes and let your eyes rest.”

Thankfully the current screens on all devices from ereaders to desktop machines are worlds better than the old displays where the refresh rate was so slow, a visible flicker was easily detected.

Carl Taussig, the director of the Information Surfaces Lab at Hewlett-Packard, told The New York Times that modern screens refresh more quickly than the human eye can see. “Today’s screens update every eight milliseconds, whereas the human eye is moving at a speed between 10 and 30 milliseconds.”

As is the case with most reading situations, posture and viewing position wind up being the most critical factors with ereader use. It’s important when reading anything, including a traditional book, not to bend the head down for long periods of time without stretching. In this position, the neck muscles cramp, causing even more discomfort than eye strain alone.