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COMPUTERS AND EYESTRAIN Carpal tunnel syndrome is probably the most widely known repetitive strain injury (RSI), but eyestrain is the most common. If uncorrected, eyestrain can lead to general fatigue, increased myopia (nearsightedness), and a decrease in overall efficiency. Everyone is at risk for eyestrain, especially those who work at a computer for more than three hours a day.

What are the symptoms of eyestrain?

Eyestrain usually results in a combination of any of the following symptoms:

  • headache

  • dry eyes, "gritty" feeling in the eyes

  • blurred vision

  • eye fatigue

  • changes in color perception

In addition, while attempting to view the screen more clearly users tend to hold their heads in unnatural positions, which contributes to neck and shoulder pain. When any of these symptoms appear they inevitably lead to decreased visual efficiency and an increase in typing errors.

What causes eyestrain?

Eyestrain is primarily a result of overworking the muscles of the eyes. This can happen in four ways. The first is simply a result of human evolution: our eyes have evolved to see at a distance in a three-dimensional world, but a monitor presents the user with a close-up, two-dimensional environment. As a result, after hours in front of the computer, the eye focusing point extends beyond the screen and out to a resting point of accommodation. This causes the user to exert extra effort to keep the eyes focused on the screen.

Glare is another common factor in eye muscle fatigue. Like a TV screen, if there is a glare on the monitor the eyes have to work harder to discern an image on the screen.

Thirdly is the position of the monitor. In their natural resting position the eyes accommodate a field of vision straight ahead and slightly down. If the monitor doesn't fall in that field of vision, muscles must continually work to hold the eyes differently.

The final way to overwork the muscles of the eye is to use rapid, repetitive movements such as darting your eyes between a source document and the screen.

Aside from eye muscle fatigue, the eyeball itself can become irritated, contributing to eyestrain. Studies have shown that while staring at a monitor, users "forget" to blink which deprives the eye of needed moisture. This is exacerbated by the dry, hot air most monitors and computer CPUs generate and disperse into the environment. Another source of irritation is dust. Most monitors create an electrostatic field that propels particles toward the user and into the eyes. All of these things create a hostile environment for the eyes.

How can I protect my eyes?

There are several things you can do to create a more eye-friendly environment around the computer. The easiest thing to do is reposition the monitor. It should be squarely in front of you at a distance of 18 to 30 inches with the top of the monitor (not the screen) level with your eyes. Positioning the monitor in such a way will allow your eyes to remain in a natural position (straight ahead and slightly down) and you will be far enough away so that particles propelled from the screen's electrostatic field will not reach your eyes.

To cut down on particle emission wipe down the screen daily with anti-static spray. If you have to read a source document while typing, use a document holder and position it right next to the monitor at the same height.

Although a document should be in a well-lighted area for optimal reading, a monitor should not. Screen glare is caused by both natural and artificial lighting reflecting off the screen surface. For maximum glare reduction, nearby windows should be covered with blinds (vertical are the best), furniture and countertops near the monitor should have non-reflective surfaces, and walls should be soft-colored and matte-finished.

Though most offices are illuminated with harsh fluorescent lighting, this is unsuitable for computer users because it creates a lot of overhead glare and harsh shadows. Ideally, a monitor should be in a softly lit, dim area. If this is not possible, the monitor should be positioned between rows of overhead lights instead of directly underneath them, and a light diffuser should be used. If the sources of glare cannot be eliminated, it might be necessary to buy a hood or a glare guard for the monitor. Glare guards, however, should be considered a last resort because many of them reduce glare at the cost of screen clarity.

The monitor itself can contribute to eyestrain. If the monitor flickers, distorts images, or is set to the incorrect brightness, contrast, or color levels, the eyes will have to work harder. It is recommended that the monitor be professionally serviced when any of these problems arise. There are even software packages available that will run diagnostic tests on your monitor.

No matter what type of environment you work in there are some steps you can take which will go a long way toward reducing eyestrain.

The first is to blink. That sounds elementary, but since it is an involuntary action most computer users don't notice that they blink much less in front of the screen.

Another helpful idea is to rest your eyes at least every two hours by taking a break, doing a simple exercise or doing a non-computer related task. Even your diet can help cut down on eyestrain! The natural oils in certain fish and potassium-rich foods like bananas and potatoes will help keep your eyes well lubricated.

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