Looking at a screen too long may lead to computer vision syndrome.
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There are many reasons to restrict the amount of time you spend in front of an electronic screen. For example, more hours sitting at a computer or smartphone means fewer hours of being physically active, and looking at a computer screen at night can stimulate the brain and make it difficult to fall asleep.
Here's another reason to curb screen time: a problem called computer vision syndrome — an umbrella term for conditions that result from looking at a computer or smartphone screen. "It's most prevalent with computers, and typically occurs when looking at a screen at arm's length or closer," says Dr. Matthew Gardiner, an ophthalmologist with Harvard-affiliated Massachusetts Eye and Ear Infirmary.
About the causes
Computer vision syndrome results from staring at a screen for long periods of time. That can lead to two problems.
One is dry eyes, caused by a lack of blinking. "When you look at a screen, you're so involved that you forget to blink. The blink rate goes from 15 times a minute to five or seven times per minute," explains Dr. Gardiner. But you need to blink to re-establish the tear film on the eyes — a thin layer of liquid that protects the surface of the eye. If you don't blink enough, your eyes dry out, causing blurry vision and discomfort.
The other main problem from staring at a screen too long is eyestrain. Dr. Gardiner says one possible cause of this is the brightness or glare that comes from the electronic screen. "Bright light sources can feel uncomfortable, especially if you have cataracts," Dr. Gardiner says. Eyestrain can also result from focusing up close on a screen without the proper eyeglass prescription. "Any time you strain to see something, maybe because you need reading glasses and have resisted getting them, you can get a headache. You can exhaust your eyes' ability to focus," says Dr. Gardiner.
Some research has even suggested that eyestrain may result from difficulty focusing on the text and images on computer screens in particular, since they're made of pixels that create blurry edges.
Fortunately, eyestrain and dry eyes are easily treated. Dr. Gardiner recommends using artificial tears several times throughout the day. The artificial tears don't have to be preservative-free. Another tip: remind yourself to blink from time to time.
If you have eyestrain and headaches after looking at the computer screen for long periods, make sure your eyeglass prescription is up to date. "The proper glasses can reduce eyestrain," says Dr. Gardiner. "The classic example is a person who never needed glasses, and then after age 45 has trouble seeing up close and is straining all day and getting headaches. Once the person gets reading glasses, the headaches are gone."
Adjusting your environment can also help reduce the risk for developing computer vision syndrome. Some ideas:
Sit about two feet away from a computer screen to reduce eyestrain.
Make sure the center of the computer monitor is slightly lower than eye level — four to eight inches.
Use a matte screen filter (about $10) to reduce glare on your smartphone, computer screen, or tablet.
Use a larger font to keep your eyes from working hard to see letters.
Reduce glare with softer lighting.
Dr. Gardiner's best advice: take a break from electronic screens every 15 to 30 minutes, just for a minute. "Look away from the screen. Do something else, and refocus on a distant target."
Do TV screens invite eye problems?
Mom warned you not to sit too close to the TV when you were a kid. "In the past, screens were bombarded with energy. That emission back in the 1950s was too strong. In the '60s and '70s, they made safer TVs. Now with LCD or LED TVs, there's nothing coming out of the screen to hurt you," says Dr. Matthew Gardiner, an ophthalmologist with Harvard-affiliated Massachusetts Eye and Ear Infirmary.
Watching TV for long periods won't generally lead to computer vision syndrome, since you're using your distance vision for viewing, not close-up vision, which risks eyestrain. However, sitting too close to a big-screen TV may cause neck strain. "You'll only see what's right in front of you, and end up looking around to see all aspects of the screen," says Dr. Gardiner.
For optimal viewing, TV retailers suggest sitting seven to 11 feet away from a 55-inch TV screen or five to eight feet away from a 40-inch TV screen.
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