Computer vision syndrome.
Reading text on hand-held computer devices or flat-panel monitors for extended periods is more likely to produce blurred vision and other symptoms of eyestrain than reading hard copy. These symptoms, which also include dry eyes, eye irritation, redness, burning, headache, and neck and shoulder pain, are diagnosed as computer vision syndrome (CVS) by the American Optometrie Association. "[S]ome 90% of the 70 million U.S. workers using computers for more than 3 hours a day may experience CVS," say Jamie Klamm, BSN, RN, and Karen Gahan Tarnow, PhD, RN, in their 2015 CNE article. Good ergonomic positioning of the computer screen and exercises can mitigate neck and shoulder pain. Eye strain, however, requires less time staring at the computer--a difficulty for workers and students who need to finish their tasks.
Reading is an intense workout for the eyes and the orbicularis oculi muscle that controls squinting and blinking, as Jim Reedy and Kevin Larson explain in their 2008 article "Blink: The Stress of Reading." Glare, small text, and light-colored or gray text make the eye muscle work harder, contributing to eye strain. In addition, we blink less when reading. Less blinking means reduced tear film and less protection from irritants. As a result, symptoms of dry eye--redness, irritation, burning--arise. Although the mean blink rate between reading hard-copy text and computer text does not significantly differ, Christina A. Chu and colleagues observed "a significantly higher percentage of incomplete blinks" when subjects were reading from a computer (7.02% for computer vs. 4.33% for hard copy; p = 0.02) in their 2014 study. "Decreased blink rates and incomplete blinks [also] occur with both fast-paced and slow-paced computer games," Klamm and Tarnow write.
Klamm and Tarnow offer several recommendations for preventing computer vision syndrome. First, eliminate glare and reflection from the computer screen by adjusting room lighting and using an antiglare cover or coating on the screen. The computer screen should be positioned at least 20 to 24 inches away, as eye muscles have to work harder when text is too close. Klamm and Tarnow also recommend blinking often, closing the lids completely, and taking short breaks by looking about 20 feet away for at least 20 seconds every 20 minutes. Over-the-counter eye drops for the redness and irritation caused by dry eyes are another suggestion. I have also found enlarging the text size and using a darker font, such as Comic Sans MS, to be helpful.
Chu CA, Rosenfield M, Portel lo JK. Blink patterns: reading from a computer screen vs. hard copy [abstract]. Optom Vis Sci. March 2014;91(3):297-302. Available at http://www.ncbi.nlm.nih.gov/ pubmed/24413278. Accessed February 11, 2016.
Klamm J, Tarnow KG. Computer vision syndrome: a review of literature. MEDSURG Nursing. March-April 2015;24(2):89-93. Available at EBSCOhost. Accessed January 20, 2016.
Sheedy J, Larson K. Blink: the stress of reading. Eye Magazine. March 2008;67(17). Available at http:// www.eyemagazine.com/opinion/article/eye-strain. Accessed February 11, 2016.
briefed by Jule Klotter
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|Date:||Apr 1, 2016|
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