Computer Vision Syndrome (CVS)
Computer Vision Syndrome (CVS) is complex
eye and vision problems related to near work which are experienced
during, or related to computer use. CVS is characterized by visual
symptoms which result from interaction with a computer display or
its environment. In most cases, symptoms occur because the visual
demands of the task exceed the visual abilities of the individual to
comfortably perform the task.
Computer Vision Syndrome affects three out of four
computer users. It is a series of symptoms related to
extended periods of computer usage. Although it is no cause
for panic, measures can be taken to relieve symptoms of CVS.
CVS can appear as a variety of symptoms. Headaches, eye
strain, neck and back aches, sensitivity to light, blurred
vision, double vision, and dry or irritated eyes are all
possible problems related to CVS.
Any computer user can develop CVS. Your vision, your
computer, and the environment where you use your computer
are all factors that can lead to CVS.
There are many aspects of computers and the work environment in
which they are used which may cause or contribute to the development
of eye or vision difficulties. To obtain optimum visual comfort and
work efficiency, all computer operators who could benefit from a
visual correction should wear it. One way to help ensure this is to
remove financial barriers to the employee for obtaining an eye
examination and, when needed, treatment for eye and vision problems.
This can often be accomplished by having an employer or third party
sponsored program which provides eye care services for employees who
work at computers.
As part of an eye care program for computer operators, it may be
necessary to determine whether any treatment, usually in the form of
eyeglasses, is specific to the computer task or whether the same
glasses or treatment would be required for general vision needs.
This may establish whether the employee is eligible to receive
occupationally related eye care services under the program.
Whether a particular vision condition requires correction with
eyeglasses or other treatment depends upon the clinical findings and
the judgment of the examining doctor. However, the following
criteria are recommended to help determine whether the care provided
is computer related. These criteria are based upon the individual
diagnosis and/or prescribed treatment. Since it is necessary for
computer operators to have an eye and vision examination to
determine whether these criteria are met, it is recommended that an
examination be provided as part of the computer eye care program.
Vision problems occur frequently among
video display terminal (VDT) workers. Most worker health
surveys show that the most frequent health related
complaints among workers at VDTs are visually related.
However, more public and professional attention is currently
being directed towards the avoidance of musculoskeletal
disorders such as wrist problems (e.g., Carpal Tunnel
Syndrome), bursitis, muscle strains (e.g., neck tension
syndrome), tendon disorders (e.g., de Quervain's disease),
and tenosynovitis (e.g., trigger finger) among others. These
disorders are generally classified as Cumulative Trauma
Disorders (CTD) or as Repetitive Strain Injuries (RSI).
VDT related vision problems are at least as significant a health
concern as the musculoskeletal disorders. Most studies indicate that
visual symptoms occur in 50-90% of VDT workers, while a study
released by NIOSH showed that 22% of VDT workers have
musculoskeletal disorders. A survey of optometrists indicated that
10 million primary eye care examinations are provided annually in
this country primarily because of visual problems at VDTs - not a
small public health issue. Vision problems are pervasive among
computer workers and are the source of worker discomfort and
decreased work performance.
There appears to be a communication gap regarding the nature and
extent of vision problems related to VDT use. The vision problems
experienced by VDT workers are varied and are difficult to grasp and
understand by those who don't specialize in vision. The
misunderstanding may also be the result of unfounded reports of
cataracts caused by VDTs, exaggerated manufacturer claims about the
need for UV and other radiation protections, and misleading
statements about the effects of specialty tinted and coated lenses
(e.g., computer glasses) among other products.
In order to improve communication and understanding of the vision
problems at computers, the American Optometric Association supports
the use of the term "Computer Vision Syndrome" (CVS) to broadly
encompass the visual problems experienced at VDTs. CVS can be used
to refer to the entirety of visual problems experienced by computer
users and therefore improve communication and understanding of these
problems. However, since there is not a single factor or visual
disorder which causes the visual problems at computers, CVS
encompasses many different symptoms, disorders and treatments.
Impact of Computer Use on Children's Vision
When first introduced, computers were almost
exclusively used by adults. Today, children increasingly use these
devices both for education and recreation. Millions of children use
computers on a daily basis at school and at home.
Children can experience many of the same symptoms related to
computer use as adults. Extensive viewing of the computer screen can
lead to eye discomfort, fatigue, blurred vision and headaches.
However, some unique aspects of how children use computers may make
them more susceptible than adults to the development of these
The potential impact
of computer use on children's vision involves the
Children often have a limited degree of
children keep performing
an enjoyable task with
until near exhaustion
(e.g., playing video
games for hours with
little, if any, breaks).
without a significant
break can cause eye
problems and eye
Accommodative problems may occur as a result of
the eyes' focusing system "locking in" to a particular target and
viewing distance. In some cases, this may cause the eyes to be
unable to smoothly and easily focus on a particular object, even
long after the original work is completed.
Eye irritation may occur because of poor tearflow over the eye due
to reduced blinking. Blinking is often inhibited by concentration
and staring at a computer or video screen. Compounding this,
computers usually are located higher in the field of view than
traditional paperwork. This results in the upper eyelids being
retracted to a greater extent. Therefore, the eye tends to
experience more than the normal amount of tear evaporation resulting
in dryness and irritation.
Children are very adaptable
Although there are many
positive aspects to
ignore problems that
would be addressed by
adults. A child who is
viewing a computer
screen with a large
amount of glare often
will not think about
changing the computer
arrangement or the
surroundings to achieve
viewing. This can result
in excessive eye strain.
Also, children often
accept blurred vision
astigmatism because they
think everyone sees the
way they do. Uncorrected
farsightedness can cause
eye strain, even when
clear vision can be
Children are not the same size as adults.
children are smaller,
computers don't fit them
well. Most computer
arranged for adult use.
Therefore, a child using
a computer on a typical
office desk often must
look up further than an
adult. Since the most
efficient viewing angle
is slightly downward
about 15 degrees,
problems using the eyes
together can occur. In
addition, children may
have difficulty reaching
the keyboard or placing
their feet on the floor,
causing arm, neck or
Children often use computers in a home or
classroom with less than optimum lighting
lighting level for the
proper use of a computer
is about half as bright
as that normally found
in a classroom.
Increased light levels
can contribute to
excessive glare and
problems associated with
adjustments of the eye
to different levels of
to Visually-Friendly Computer Use
Here are some things to consider for children using a
Children have different needs to comfortably use a
computer. A small amount of effort can
help reinforce appropriate viewing habits and assure
comfortable and enjoyable computer use.
Have the child's vision checked. This will make
sure that the child can see clearly and comfortably and
can detect any hidden conditions that may contribute to
eye strain. When necessary, glasses, contact lenses or
vision therapy can provide clear, comfortable vision,
not just for using the computer, but for all other
aspects of daily activities.
Strictly enforce the amount of time that a child can
continuously use the computer. A ten-minute break
every hour will minimize the development of eye focusing
problems and eye irritation caused by improper blinking.
Carefully check the height and arrangement of the
computer. The child's size should determine how the
monitor and keyboard are positioned. In many situations,
the computer monitor will be too high in the child's
field of view, the chair too low and the desk too high.
A good solution to many of these problems is an
adjustable chair that can be raised for the child's
comfort, since it is usually difficult to lower the
computer monitor. A foot stool may be necessary to
support the child's feet.
Carefully check the lighting for glare on the
computer screen. Windows or other light sources
should not be directly visible when sitting in front of
the monitor. When this occurs, the desk or computer may
be turned to prevent glare on the screen. Sometimes
glare is less obvious. In this case, holding a small
mirror flat against the screen can be a useful way to
look for light sources that are reflecting off of the
screen from above or behind. If a light source can be
seen in the mirror, the offending light should be moved
or blocked from hitting the screen with a cardboard hood
(a baffle) attached to the top of the monitor. In
addition, the American Optometric Association has
evaluated and accepted a number of glare screens that
can be added to a computer to reduce glare. Look for the
AOA Seal of Acceptance when purchasing a glare reduction
Reduce the amount of lighting in the room to match
the computer screen. Often this is very simple in
the home. In some cases, a smaller light can be
substituted for the bright overhead light or a dimmer
switch can be installed to give flexible control of room
lighting. In other cases, a three-way bulb can be turned
onto its lowest setting.
Children have different needs to comfortably use a
computer. A small amount of effort can help reinforce
appropriate viewing habits and assure comfortable and
enjoyable computer use.