Write your abstract here.Sitting Too Close to the Computer Screen Can Make You Go Blind.
Eyestrain is a common—and
occasionally debilitating—effect of staring at screens. By Molly Webster. You roll your head, hoping to loosen the knots in your neck, and
shut your eyes. After rubbing them you settle back into staring,
hunched inches away from the computer screen. Despite the brief reprise
your vision remains cloudy, causing the words on the monitor to blur.
At this point, you need to know: With each further click on the
keyboard, video watched on YouTube, and e-mail sent—are you damaging your vision?
Ophthalmologists, optometrists and other eye professionals note a
seeming link between myopia, also called nearsightedness, and "near
work"—visual activities that take place at a distance of about 40
centimeters (16 inches) from the eye—such as reading a book. Staring at
a computer screen qualifies as well, though monitors usually are around
50 centimeters (20 inches) away. But only a small—and mysterious—subset of people see
myopic progression from near work, whether they are focusing on a
computer or accounting books. "We are not very clever in identifying
who
yet," says James Sheedy, a professor at the Pacific
University College of Optometry in Oregon.
The fact that near work doesn''t lead to myopia in all of us,
however, doesn''t mean sitting close to a computer screen causes no
problems. Though for most it is not permanently damaging, computer near
work leads to an uncomfortable, at times debilitating, list of symptoms
collectively known as eyestrain.
Eyestrain, says Mark Bullimore, a professor at The Ohio State
University College of Optometry, results from staring at a screen over
long periods of time. Such activity causes eye exhaustion: burning,
dryness and muscle aches—all unpleasant and potentially incapacitating
symptoms while they last.
The simplest way to understand why eyestrain develops—and learn how
to prevent it—is by looking at the way our built-in binoculars show us
the fine print. When we "see" something, light reflects from an object
through the cornea, the transparent, dome-shaped layer covering the
eye. The cornea and the crystalline lens (a transparent, round,
flexible structure behind the iris) then bend the wavelengths so they
hit the rods and cones—photoreceptors on the retina that gather
incoming light information. This innermost layer at the back of the eye
is responsible for collecting and then moving light information, via
the optic nerve, to the brain, which produces an image.
Staring closely at a screen forces our ciliary muscle, which
controls the shape of our lens and therefore how well we focus, to
remain contracted, without rest. This is demanding—and tiring—for the
poor little muscle. Up close focusing also stops us from blinking.
Blinking is essential because it spreads tears over the surface of
the eye; if blinking stops, the corneal surface dries out. When this
happens, the cornea becomes cloudy, causing "foggy" vision, according
to Sheedy. The normal blink rate is around 20 times per minute but
using a computer can drop it to as low as seven, though experts believe
this has no long-term effect.
Staring at a screen—surrounded by glaring peripheral lights—also
causes us to squint, says Dennis Robertson, an ophthalmology professor
at the Mayo Medical School in Rochester, Minn.
And though squinting cuts down on glare and prevents exorbitant
amounts of light from assaulting your eyeballs (which solves some of
the problems created by not blinking), it''s exhausting. Freezing the
muscles around your eye into a tense, squinched position all day long
is just as tiring as it would be to hold a stomach-crunch for nine
hours.
These eyestrain symptoms usually only last a few hours, dissipating
as we allow ourselves time to blink and focus on things farther away.
But once thrt, they hamper productivity and, more importantly,
make us grumpy. All is not lost, however. We can fix these burning,
aching, dried out sensations one ergonomic workstation at a time.
Invest in one of today''s nonglare computer screens, and don''t be
afraid to change your computer''s brightness, contrast or text size, all
of which will alleviate eye stress. Also, position your screen slightly
lower than your eyes; the top of your monitor should be level with your
eyebrows. For physiological problems, hit your doctor up for a pair of
corrective lenses.
Finally, eliminate any glaring peripheral light. To find out
what lights are bothersome, Sheedy recommends performing the
hand-as-visor trick: Shield your eyes with your hand, and see if that
makes the tension in your face and shoulders dissipate. If it does,
manually adjust the lamps you blocked out as bothersome. As for
watching TV, experts recommend laughing along with your favorite sitcom
from a comfortable distance. (Finally, a reason to be a couch potato.)
But by far the simplest and best expert advice for eliminating
eyestrain from any type of medium: take regular breaks. Go on, walk
over to the water cooler, even if you aren''t thirsty; and by all means,
move your easy chair at least two feet from the television. Above all:
don''t forget to blink.