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 moisture 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.
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.
FAQ’s
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. 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?
Headaches, sore neck, shoulders or back 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.
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.
 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 antireflective coating applied to your glasses. This
will prevent glare and reflections on the back
side of your lenses
4. Adjust the brightness of your computer screen.
 Closely match the brightness of the environment
with that of your computer screen. Make sure
that the text size and color are optimized for the
most comfort.
10 Steps to Reducing
Computer Eyestrain
5. Monitor Display Quality
Refresh rate: 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: a monitor's pixel density: the more pixels,
the higher the level of detail. Generally, the higher the
resolution the better.
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.
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