Smartphones May Be Taxing Your Eyes07/22/11
THURSDAY, July 21 (HealthDay News) -- People reading text
messages or browsing the Internet on their smartphones tend to hold
the devices closer than they would a book or newspaper, forcing
their eyes to work harder than usual, new research shows.
This closer distance -- plus the often tiny font sizes on
smartphones -- could put added strain on people who already wear
glasses or contact lenses, according to the study, which appears in
the July issue of
Optometry and Vision Science.
"The fact that people are holding the devices at close distances means that the eyes have to work that much harder to focus on the print and to have their eyes pointed in right direction," said study co-author Dr. Mark Rosenfield, a professor at the SUNY State College of Optometry in New York City. "The fact that the eyes are having to work harder means that people may get symptoms such as headaches and eye strain."
Texting and browsing the Web on smartphones can also result in
dry eye, discomfort and blurred vision after prolonged use, the
study authors point out. Previous studies have also found that up
to 90 percent of people who use computers experience eye
Rosenfield got the idea for the study while commuting to work on
the train and noticing that people using smartphones seemed to be
holding them very close to their eyes.
Given that more and more adults and children are using
smartphones to write and receive messages or look up restaurant
reviews, it made sense to measure exactly how close people were
holding their phones.
The experiments were relatively simple ones. In the first, about
130 volunteers with an average age of 23.2 years were asked to hold
their smartphone while reading an actual text message.
In a different experiment, 100 participants, whose average age
24.9, were next asked to hold their smartphone when reading a web
The researchers then measured the distance between the device
and the eyes as well as the font size.
When reading printed text in newspapers, books and magazines,
the average working distance is close to 16 inches from the eyes,
but the study volunteers writing or sending text messages held
their phones, on average, only about 14 inches away. In some
people, it was as close as 7 inches, Rosenfield said.
When viewing a web page, the average working distance was 12.6
The font on text messages tended to be slightly larger (about 10
percent, on average) than newspaper print, but web-page font was
only 80 percent the size of newspaper print and, in some cases, as
small as 30 percent, Rosenfield said.
The findings hold messages for doctors and smartphone-users
Given the ubiquitousness of these handheld devices, eye doctors
might consider testing people's vision at closer distances and
prescribing glasses for closer distances.
But there's a simple way for smartphone addicts to minimize eye
strain: Increase the font size on your device, advised Dr. Scott
MacRae, a professor of ophthalmology and of visual science at the
University of Rochester Medical Center and an eye surgeon.
This is especially important for sustained reading, like reading
a book on Kindle, he noted.
Font size on an e-book reader is usually pretty easy to do. For
other handheld devices," MacRae said, "the problem is to figure out
how to do it."
If you're a regular computer user, try using Verdana 12-point
font, the only font designed specifically for computers, MacRae
The authors are now also assessing Kindles and IPads, but those
results haven't been published.
The American Academy of Ophthalmology has more on
how to keep your eyes healthy.
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