Transcript Computer Vision Syndrome

Computer Vision
Syndrome
What is Computer Vision
Syndrome? (CVS)
“A complex of eye or vision
problems which are
experienced during and
related to computer use.”
Superior and lateral rectus muscles,
optic nerve.
Superior and inferior oblique muscles,
superior,inferior, and lateral rectus
muscles, with eye.
Superior and inferior oblique muscles,
medial and inferior rectus muscles.
Eye with rectus muscle attachments.
Why are we CONCERNED
ABOUT CVS?
 143M American workers work on a
computer and estimates are
88% suffer from computer eyestrain
 90% of the 143M U.S. workers use
computers today for more than 3 hours
per day
 This problem effects productivity by
4 to 19%
What are the symptoms of
CVS?
 Eyestrain (sore or fatigued
eyes)
Headache
 Slowness in changing focusing
distance
 Eye irritation (burning, dryness,
redness)
Neck, back & shoulder pain
The Problem
 It has multiple causes & symptoms
 Prolonged viewing is the most
common cause and it has been
proven to be unnatural for the
human optical system
 Humans blink approximately 22
times per minute. During computer
use humans blink only 4 to 6 times
per minute
Other Problems
 Lower blinking rates cause eye
moister to evaporate (dry eye)
 Dry eye causes people to arch their
foreheads in a effort see better, thus
causing headaches
 Many people assume awkward,
unnatural postures, thus causing
sore backs, stiff necks & hurting
shoulders
FAQ’s
• What Causes Computer Vision Syndrome?
– CVS is caused by our eyes and brain reacting
differently to characters on the screen than they do to
printed characters.
– Our eyes have little problem focusing on most
printed material, which is characterized by dense
black characters with well-defined edges.
– Healthy eyes can easily maintain focus on the printed
page. Characters on a computer screen, however,
don't have this contrast or well-defined edges.
– These characters (pixels) are brightest at the center
and diminish in intensity toward their edges. This
makes it very difficult for our eyes to maintain focus
and remain fixed onto these images.
– Instead our eyes drift out to a point called the "resting
point of accommodation" (RPA) which is
approximately 30 inches and grows as we get older.
FAQ’s
• Will Glare Screens Prevent CVS?
– Glare screen filters may help somewhat, but
they will not solve your computer vision
problems because they only affect glare from
the computer screen — not the visual problems
related to the constant refocusing of your eyes
when working at a computer.
– Only when your eyes can focus clearly at the
plane of proper distance on the computer screen
can they experience relief from the fatiguing
effects of CVS. An anti-reflective coating (AR)
is also highly recommended on all computer
eyeglasses. An AR coating prevents glare and
reflections on the front and the back of the
lenses that would interfere with focusing on the
screen.
FAQ’s
• Will Computer Eyeglasses Make the
Screen Clearer?
– Yes, because they will eliminate the constant
refocusing effort that your eyes go through
when viewing the screen. It has also been
proven clinically that having the correct
prescription in computer eyeglasses increases
productivity and accuracy.
• What About the Tints I've Heard of for
Computer Lenses?
– If you work in a brightly lit office, you may
benefit from a light tint applied to your
computer lenses. This can cut the amount of
light that reaches your eyes and provide relief
in some cases. But tints and filters don't
address the underlying cause of computer
eyestrain.
FAQ’s
• Does Every Computer User Need
Computer Glasses?
– More than 70% of computer users need
computer eyeglasses.** In fact, according to
a study out of the University of California,
Berkeley, 25%-30% of children would
benefit from computer eyewear.
FAQ’s
• Will My Reading Glasses Work at the
Computer?
– Not necessarily. As with anything else you do in
life, it is important to have the right tool for the
job. You would not use a hammer when you
need a screwdriver. The same goes for your
vision: you would not use distance glasses for
doing close work. So in most cases your reading
glasses are probably not going to do the job.
The correct computer eyeglasses will optimize
your comfort and productivity at the computer
screen while also allowing you to read and see
out at some determined distance (10-13 feet).
Reading glasses are usually prescribed to read
at a distance of 16"-18", but computer glasses
are usually designed to work at 18" to 28".
FAQ’s
• Can CVS Cause Other Body Pains?
Do you get headaches when you use the
computer?
What about a sore neck, shoulders or back?
These are common complaints and there are two
main causes, one having to do with your vision
and one not.
– Vision
• So where do the other aches and pains come
in? These are often caused by trying to read
the screen through the bottom portion of
bifocals, or though half-eye reading glasses.
You tip your head up or lean forward to see
and this unnatural posture makes you sore
FAQ’s
• Isn't Ergonomics the Solution to
Computer Eyestrain?
– Ergonomics is important — changing one's
computer workstation can certainly help to
minimize other physical symptoms. But
ergonomics cannot fix a visual problem. The
proper prescription computer eyeglasses at
the proper computer distance (18" to 28") is
most important. This can be done only with
the right computer lens prescription.
FAQ’s
– Ergonomics
• Poor ergonomic setup is another cause of
head, neck, shoulder and back pain. Follow
these quick tips for maximum comfort.
– Place your monitor directly in front of
you, not off to one side (it should be
about 20 to 26 inches away from you).
– Make sure your monitor is NOT too
high. CVS expert Dr. James Sheedy
recommends that the center of the screen
be four to nine inches below your
straight-ahead gaze. If you reposition
your chair, keep in mind that your arms
should be parallel to the floor when you
type, and your feet should be flat on the
floor (or a footstool).
10 Steps to Reducing
Computer Eyestrain
1. Get a computer eye exam.
2. Use proper lighting.

Eyestrain is often caused by excessively
bright light coming in from outside and
excessively bright light inside. When you
use a computer, your ambient lighting
should be about half that used in most
offices. Eliminate exterior light by closing
drapes, shades, or blinds. Reduce interior
lighting by using fewer light bulbs or
fluorescent tubes, or use lower intensity
bulbs and tubes. If possible, position your
monitor so that windows are to the side of
it, instead of in front or back.
10 Steps to Reducing
Computer Eyestrain
3.
Minimize glare.

4.
Glare on walls and finished surfaces, as well as
reflections on the computer screen itself can also
cause eyestrain. You may want to install an anti-glare
screen on your monitor and, if possible, paint bright
white walls a darker color with a matte finish. Again,
cover the windows; when outside light cannot be
reduced, use a computer hood. Have an anti-reflective
coating applied to your glasses. This will prevent
glare and reflections on the back side of your lenses
Adjust the brightness of your computer screen.

Closely match the brightness of the environment with
that of your computer screen, by using the buttons on
the monitor. As a test, try looking at the white
background of this web page: if it looks like a light
source, it's too bright; if it seems dull and gray, it may
be too dark. Also adjust the monitor to make sure the
contrast between the screen background and the onscreen characters is high. And make sure that the text
size and color are optimized for the most comfort.
10 Steps to Reducing
Computer Eyestrain
5. Monitor Display Quality
How well your monitor displays everything on the
screen depends on three things:



Refresh rate refers to how often your monitor redraws
the content on the screen. A too-low rate can be hard on
your eyes, and a very slow rate causes a noticeable and
irritating flicker.
Resolution refers to a monitor's pixel density: the more
pixels, the higher the level of detail. Generally, the
higher the resolution the better, but watch out for that
refresh rate: sometimes, the very high resolutions have
an inadequate refresh rate, so you need to choose a
setting where both are high numbers.
Dot pitch affects the sharpness of the display: the lower
the number, the sharper the image. Most monitors have
a dot pitch between 0.25 mm (millimeters) and 0.28
mm; 0.28 or lower is desirable.
If you think you need help with your Monitor Display Quality, please contact
your I.T. Department.
10 Steps to Reducing
Computer Eyestrain
6. Blink more often.

Blinking is very important when working at a
computer — it rewets your eyes to avoid dryness and
irritation. When working at a computer, people blink
less frequently — about five times less than normally,
according to studies. Tears coating the eye evaporate
more rapidly during long non-blinking phases and
cause dry eyes . Office buildings may have excessively
dry environments that also reduce tearing.

Also try this exercise: Every 30 minutes blink 10 times
by closing your eyes as if falling asleep (very slowly).
This will help rewet your eyes
7. Exercise and stretch your eyes.

An hourly exercise to readjust your focusing is to look
far away at an object for 10-15 seconds and then near
for 10-15 seconds, rocking your focusing back and
forth between near and far. Do this 10 times. Both of
these exercises will help you prevent strained near
vision and stretch your focusing muscles
10 Steps to Reducing
Computer Eyestrain
8. Take frequent breaks.


20/20/20 – every 20 minutes look at
something at least 20 feet away for 20
seconds.
Every 50 minutes on a computer, change
tasks for 10 minutes.
9. Modify your workstation.

If you need to look back and forth between a
printed page and your computer screen, this
can cause eyestrain. Place written pages on a
copy stand adjacent to the monitor. Properly
light the copy stand; you may want to use a
desk lamp, but make sure it doesn't shine into
your eyes or onto the computer screen. Adjust
your workstation and chair to the correct
height. Purchase ergonomic furniture to
insure proper screen locations and posture.
10 Steps to Reducing
Computer Eyestrain
10. Exercise even when sitting.
 Anyone in a sedentary job, especially
those using computers, should stand up,
move about, or exercise their arms, legs,
back, neck, and shoulders frequently.
NIOSH recommends several sitting,
stretching, and joint rotating exercises
for computer users
The Solution
Keep computer screens slightly
below eye level
20-26 inch from the screen
Keep contrast & brightness at
moderate levels
Keep screen clean
Reduce screen glare
Frequent short breaks
Purposely blink rapidly