Visual Ergonomics In The Workplace
Vision is our
most precious sense. Our eyes are in constant use every waking minute of every
day. The way we use our eyes can determine how well we work throughout our lifetime.
Over eighty percent of our learning is mediated through our eyes, indicating
the important role our vision plays in our daily activities. Vision disturbance
is a silent enemy that only appears after a long period of continued stress.
In the past two
decades, computers have taken industry and business by storm. It is estimated
that there are now over seventy-five million Americans using computers regularly.
We are increasingly becoming an information society and the price we are paying
is our eyesight.
The human eye
has been essentially unchanged for over 40,000 years in our evolution. However,
in the last one hundred years or so we have been gradually altering our viewing
tasks from predominantly distance to near work. Today we spend a disproportionate
amount of time involved in close work. To adapt to this change, our eyes have
become increasingly near-sighted. Researchers have confirmed this shift toward
increased near-sightedness in our society. This is much more prominent in the
population of computer users.
Let's look at
the different factors that effect our eyes while using a computer.
Using a computer
differs significantly from traditional reading in many ways. There is a difference
in looking at a white piece of paper with black letters that reflects light
versus looking at a (usually) white screen with various colored letters that
is self-illuminated. The additional light coming from the screen dictates that
less surrounding light is necessary. The light emanates from the screen by a
process that continually refreshes a phosphor coating so the image doesn't fade.
This refreshing of the coating must be accomplished at a rate of more than sixty
times per second. If it occurs at a slower rate, the user will experience the
"flicker" that is similar to that of an old fluorescent light. People
experience this flicker differently and different screens have different flicker
rates. This can be a very distracting and stressful experience for the terminal
user. One can reduce flicker by dimming the brightness of the screen. However,
that can lead to other potential problems which will be discussed later.
of the letters is also a concern. Research has shown that productivity and performance
is reduce when looking at a display screen vs. paper. Although the quality of
the images on a display screen are improving, they do not yet approach that
of ink on paper.
There is a considerable
difference in the normal eye position when looking at the terminal as compared
to reading. Conventional reading is normally done while looking at a 14-16"
working distance with the reading material held in a lowered (about forty degrees)
position. The straight-ahead position used by many computer users is unnatural.
The muscles must fight one another to achieve a balance and maintain the image
correctly in the eyes. This can lead to fatigue, eyestrain or headaches. Ideally,
the center of the screen should be 7-10 inches below your horizontal line of
Glare is any extraneous
scattering of light. There are many sources of glare in most office situations:
improperly positioned lamps, fluorescent lights, outdoor light, highly reflective
surfaces or any illuminated object. The glass surface a computer terminal can
be highly reflective. While the eyes are in the straight-ahead position they
are more susceptible to outside sources of light, especially those coming from
There are many
ways to reduce glare. The first way should be with an anti-glare screen that
is placed over the screen. The most common screens are mesh or glass and each
has it's own advantages. Glass screens are generally better but may lead to
further reflections if it doesnt have an anti-reflective coating. Although
they are more bothersome to keep clean and are more expensive, they do an excellent
job of reducing glare. Of these, circular polarized are the best. They block
glare but allow the normal light from the monitor to come through.
glare by positioning the screen properly. While the screen is off, angle it
so that you can see no reflections of any lights on the front surface of the
to glare may be a bit more difficult to control. Traditional lens panels on
fluorescent lights are often a significant source of glare. These units can
be retrofit with louvers that direct the light straight downward instead of
allowing scattering. This will create a dimmer working environment but will
be much more soothing on the eyes. Research has found that most offices are
much too bright for terminal work. The surrounding illumination should only
be three times as bright or less as the screen that you are using.
If glasses are
worn while using a computer, you'll probably benefit from a very slight pink
or rose colored tint in the lens. This is a barely noticeable tint but will
help to offset the poor color definition of fluorescent light around the office.
If you are wearing
glasses regularly, the prescription in them is usually designed to help you
see better at a distance, while driving for example. However, the power required
for clear distant vision may be different from what will make your eyes most
comfortable at 20-25 inches. How your eyes focus and coordinate together will
determine what the proper prescription will be for glasses at the close distance.
If you haven't
worn glasses at all before, get your eyes examined by your eyecare professional.
Be sure to tell him or her that you work on a computer and try to give them
as much information about it as possible, i.e., working distance, lighting conditions,
amount of time spent at the terminal, symptoms you experience, etc. Very often
special computer glasses will be prescribed simply to ease the effect of long
hours looking at the screen.
If you are over
the age of 40, you probably have (or soon will) experienced difficulty changing
focus to near objects. This is the usual decrease in the eyes' ability to focus
as we age. Glasses used for reading and computer work can let you function normally
again. If you already wear glasses for distance and experience difficulty focusing,
then bifocals may be in your future. The traditional bifocal is not well suited
for computer vision so an alternate choice may be necessary. New lenses that
have no lines and provide for a full range of distance, intermediate and near
vision are available so be sure you ask for as many alternatives as possible.
If you have contact
lenses, you also may be experiencing dryness and discomfort while working on
your terminal. The first problem can often be contributed to the environment.
If you work in a room that has computer hardware in the area, air filters are
often used to dry the air to make the conditions optimal for the computer. This
will, of course leave less moisture in the air causing the lenses to dry. Additionally
the cooling fans of the units themselves draw more dust into the area creating
more problems. There is also a tendency to blink less when doing intense close
work (see below). Lubricating drops recommended by your doctor will help relieve
the symptoms of dryness.
precautions and/or using glasses are just not enough. If your visual system
is not able to make necessary adjustments to work effectively, you could probably
benefit from vision therapy.
is a program offered by optometrists to teach people how to use their eyes properly
and with less effort. This is done by using an integrated program of techniques
and procedures that help the person in improving all aspects of vision, including
general coordination, balance, hand-eye coordination, eye movements, eye teaming,
and focusing efficiency. It is done on patients of all ages for any number of
different problems. Ask your local Optometric Society for the name of a doctor
in your area that specializes in vision therapy.
A recently introduced
software program has shown to be very effective in conducting a vision screening
test on the computer. The Eye-Computer Ergonomic Evaluation (Eye-CEE) System
for Computer Users® consists of an on-line questionnaire and vision tests
which can determine if your symptoms are related to your vision or to your environment.
The program produces reports that can be taken to your doctor so that they can
do a more effective examination of your vision. It has shown to be the most
effective way to determine computer -related visual stress.
Self Eye Care
There are many
things you can do for yourself to reduce the eyestrain you feel while working
at the computer. I've narrowed these down to a "3 B's" approach: Blink,
Breathe and Break.
Blinking is an automatic function. It also happens to be the fastest reflex
in the body! We usually blink at a rate of about 12-15 times a minute in normal
situations. Unfortunately, we have never figured out what a normal situation
is yet. We blink more often when we are excited, stimulated, anxious, talking
and doing general physical activity. We blink much less frequently while quiet,
which includes reading, thinking and concentrating on a particular task. This
staring can strain the eyes. Blinking allows the eye to rest for a short time
and it also cleans and re-wets the eye surface to maintain clear vision. Because
blinking is so automatic it might take some concentration initially to keep
up a normal blink rate while working at a terminal. Just being aware of this
concern will allow you to blink more normally.
Our breath is our life. Our entire body is governed by the exchange of oxygen
and carbon dioxide from our breathing process. When we reach a stressful situation
in our activities, we tend to hold our breath to "break through" the
situation. This is because the breath can control our muscle activity. If we
hold our breath, we may tighten muscles in places where we are not even aware.
Correct breathing- even and steady- can relax the eye muscles as well.
With the amount of intense concentration we use doing computer work it is not
surprising that we need more breaks. Our eyes were just not designed to be used
at that close distance for a long period of time. I've devised a plan of breaks
that will allow you to do the maximum amount of work and still allow you to
relax your eyes. These are called: Micro-, Mini- and Maxi-Breaks.
Also known as the "20/20/20" rule, this break is only for about twenty
seconds and should be taken about every twenty minutes. Look far away from your
terminal (at least twenty feet) and breathe and blink easily. Keep your eyes
moving while looking at different distant objects. This should not interfere
with your work nor your concentration.
Take this break about every hour; it should last about five minutes. Stand up
and stretch. I often recommend eye exercises be done during this break so the
eyes can flex and be used in different seeing situations. Ask your eye doctor
which exercises he or she would recommend.
This could be a "coffee" break or lunch. The maxi-break is a "get
up and move" type of break that will allow your blood to start flowing
again and get you more energized. These should be taken every few hours.
There is no one
solution to all types of problems encountered with computer use. However, education
and common sense can help to reduce your potential risk. Our productivity is
supposed to be increased with computer use but it should not be at the expense
of our eyesight. Hopefully we can co-exist with computers and use them to their
fullest potential. The answer to many of these problems may be right before