As a child, your mother always said: "Don't sit so close to the TV, or you'll go blind!" But now almost everyone who works at a desk spends their entire day staring at a screen from distances that are most definitely not "mom-approved."
Do all those hours spent staring at your personal glowing portal to the digital world have an effect on your eyesight? Recent studies show that Mom might have known a thing or two after all. Eyestrain has also been linked with an increased risk of glaucoma.
The human visual system is complex and amazingly adaptive. It can change focus to see objects both near and far. It can change to see in bright conditions or dark conditions. With the help of 140 million neurons in the visual cortex it can identify, classify, analyze and react to approximately 12 to 15 one-million-point images per second. Yet, despite this complexity, human eyes just don't handle extended computer screen viewing all that well. "Your eyes are happiest when used for a variety of tasks utilizing a variety of focal distances with a variety of properly aligned light sources," states Jeffrey Anshel, O.D., author of Visual Ergonomics in the Workplace. "Computer use provides none of the above."
Strain on the eye from computer use comes from a several sources. The first is a constant working distance typical of computer users. Two sets of muscles work in tandem to see your screen clearly. One set converges the eyes onto the same point. The other set actually flexes and fattens up the crystalline lens in each eye to properly focus light rays from the computer onto the retina. As with any muscle in the body, continuous flexing can create repetitive stress problems. Ever have blurred vision when looking away from the screen? This may be a spasm of the ciliary muscles causing focus to "lock," thereby creating a temporary loss of distance vision. Other symptoms may include blurred vision, the inability to properly focus on the screen, or even a good old-fashioned headache.
Ever find that your eyes have an irritated "scratchy" feeling after a long session using the computer? A relatively normal blink rate is 12-15 blinks per minute, but computer users tend to blink much less frequently, more typically around 4-5 blinks per minute. Why? The eyes normally jump around the screen in pattern called a "saccade." Blinking disrupts this pattern and lowers productivity for someone concentrating on an intense visual task, especially when under deadline to get a big project done. Blink less and you get more done... but it can take a toll on your eyes. A dry, scratchy sensation is a common symptom of dry eyes. Interestingly, in some cases, computer users actually suffer watery eye symptoms due to the fact that the eyes are irritated but the reduced blink rate doesn't spread the tears effectively.
Another reason your eyes strain when using the computer relates to the quality of light emitted from the screen. "In simplest terms, it's like you're looking at a lightbulb for hours on end," says Anshel. "Not to mention the fact that today's LCD screens are almost all backlit with fluorescent light, which is harsh on your eyes to begin with."
In an effort to reduce the amount of energy consumed, screen manufacturers use very narrow bands of the visual spectrum to light the screen. Combined with overhead fluorescent office light, the harsh artificial light is far from full spectrum daylight that the eye likes to see. In an effort to improve the quality of light, often computer users will put the computer close to windows or other more natural light sources. However, improperly-placed lighting can actually cause problems due to screen glare or over-illumination of the eye, which causes the pupil to constrict and makes the screen harder to see.
As eyestrain affects normal vision, secondary problems may occur as well. "Walk around the office and notice how many people are hunched in toward the computer to see the screen better," prompts Anshel. "With poor ergonomic posture, it's easy to see how computer vision problems can create head, neck, and back pain."
To simplify diagnosis, all of these symptoms commonly are lumped under the term Computer Vision Syndrome. While Carpal Tunnel Syndrome is one of the most well-known workplace ergonomic issues, Computer Vision Syndrome is by far and away the most prevalent, affecting an estimated 150 to 200 million Americans, or 90 percent of computer users who work more than three hours a day on the computer.
Not surprisingly, computer vision issues are ranked by OSHA No. 1 on the list of health-related office complaints. The National Eye Institute, again unsurprisingly, recently released data showing a 66 percent increase in the prevalence of myopia in the 25 years since the advent of the personal computer.
So it sounds like Mom might have had it right. But will computer viewing truly make you go blind? The good news is that there are a number of ways to prevent or lessen the strain felt while viewing a computer. Many are quick or inexpensive solutions to address certain parts or the problem. For example, rearranging the workplace for proper posture, viewing angle, and lighting can help out.
Dr. Anshel suggests, "Make sure you have your computer far enough away to comfortably see it. Ideally, the center of the screen is 7-10 inches below your horizontal line of sight. Move your lights to where they don't cause any glare and to where you don't have any bright objects, like a window, in your field of view when viewing the screen." He also suggests a series of breaks during the workday. The smallest should occur every 10 minutes and can be as short as 10 or 20 seconds. To properly relax the eye muscles, you must look at least 20 feet away. At least once each hour, take a bigger break that includes standing and stretching. An eye doctor can recommend specific eye exercises during these bigger breaks to help further relax eye muscles.
Several commercial solutions are available for sale to help alleviate Computer Vision Syndrome. Glare protectors are an easy fix for both older CRT monitors and some newer screens that have a glossy surface. Reflections may create awkward posture if the glare prevents you from seeing the screen from a straight-on view. Certain software is also available to help users remember to take breaks, blink more often, or even change the color of the screen to adapt to different times of the day in an effort to limit blue light, which may affect sleep patterns.
Specific computer eyewear will also help relieve many symptoms. Most eye doctors can make adjustments to a general prescription to make it more adapted for computer use, but some companies, such as Gunnar Optiks, make glasses specifically designed to reduce computer eyestrain.
Regardless of the solution you end up adopting to help your eyes, the first step is awareness of the problem. In fact, the Vision Council of America (VCA) has made computer eyestrain awareness a major initiative for 2012 and 2013. "Computer-related vision problems will continue to increase at record levels as people spend more and more time in front of a screen," said Joe LaMountain, a spokesperson for VCA. "If you work on a computer regularly, then you should get your eyes examined regularly."
The encouragement is a good one. A yearly visit to an eye care professional will ensure that any problems are caught prior to becoming serious issues. So pick up the phone and call your eye doctor. And then call Mom to let her know, too!
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