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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