Working for long periods on a computer is a demanding visual
task. Daily, millions of Americans use a computer for hours at a time, both at work and
at play. Many of them routinely experience
symptoms of headache, fatigue, blurry
vision, scratchy eyes, or pain in the shoulders, neck or back.
Our eyes and brain react differently to characters displayed
on
a computer screen than they do to characters printed
on paper. Computer
images are less distinct than printed characters, may have perceptible
flicker, and usually have less contrast between characters and the
background. Computer users must rapidly switch focus from keyboard to
monitor and vice versa; this constant refocusing can also contribute to
symptoms. |
What are computer glasses?
Computer
glasses are prescription glasses that are specifically designed to wear when doing
computer work. They allow you to focus your eyes comfortably on a computer screen,
which
is usually farther away than reading material is held.
General
purpose bifocals and trifocals are not designed for computer work.
Bifocals
force the wearer to tilt the head back in order to focus on
the screen, while
looking through the lower portion of the bifocal lenses.
While conventional trifocals
allow a
more normal head posture, they generally have too small an area for
viewing
the computer screen and the visible dividing lines can be a
significant distraction.
Which kind of
computer glasses are the best?
There
is no one type of computer glasses that fits all or is the best
for everyone. Visual ability, personal preferences of the computer
operator, the type of work, the distance between the computer user's eyes
and the monitor, and lighting design in the workplace should all be taken into consideration when selecting computer glasses.
Lens design and lens options vary significantly from manufacturer to
manufacturer. It's always best to make your final selection of computer
glasses based upon the advice and recommendations of your eye doctor;
however, all of the options listed below
have proven to be beneficial for computer users.
Progressive
Addition Lenses
Surveys conducted among persons working long hours with computers revealed
that Progressive Addition Lenses (PALs) were the lenses of choice. These
modern lenses
have more than just the cosmetic advantage of "no lines." They provide all
the benefits of bifocals but add the feature of continuous clear vision at
all distances, including
mid-range distance (arm's length). Several lens manufactures have
introduced PALs designed specifically for computer use. These specialized
PALs allow an even wider
field of view for near and intermediate working distances than standard
PALs.
Anti-Reflective
coating
Today's advanced Anti-Reflective (AR)
coatings eliminate bothersome reflections from overhead lights and
computer monitors.
AR coatings not only reduce reflections but increase the amount of light
transmitted through the lenses to the wearer's eyes. It
may seem strange but AR coated lenses actually appear clearer than
uncoated
clear lenses...sometimes appearing to be nearly "invisible."
Natural light sources (windows) can be especially bothersome in the
workplace. When a window is located over the wearer's shoulder, natural
light striking the back surfaces of the lenses bounces directly into the
wearer's eyes. Since outside light levels are quite high, the intensity of
these reflections can be even greater than reflections from light sources
within the workplace. An AR coating placed on the back surfaces of the
lenses eliminates these "outside" reflections as well.
High Index Lenses
Modern technology has created lenses that bend light differently so that
stronger corrections are thinner than when made in conventional materials.
Such lenses are
called "high index".
High index materials can
drastically reduce the thickness and weight of prescription lenses.
Lens thickness can sometimes be cut by as much as 50% by simply using a
higher index material and choosing an appropriate frame. High index
materials are more shatter resistant than traditional plastic and will
improve the appearance of any prescription.
Note: High index lenses bend
light to a greater degree so an anti-reflective coating
is especially recommended to
maximize their performance and cosmetic advantages.
In
Conclusion
If you're one of the millions of people who use a computer on a regular
basis, be sure to ask your eye doctor about "computer glasses" the next
time you have your eyes examined or replace your current prescription.
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Vision and Health Newsletter courtesy of:
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Berner Eye Clinic
Terry Berner, O.D. Karri Buresh, O.D.
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250 East 300 South Salt Lake City, UT 84111
801-322-0467 |
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