How to Fight Computer Vision Syndrome REVIEW Therapeutic Topics

REVIEW Therapeutic Topics
How to Fight
Computer Vision Syndrome
Advice on treating one of the
possible epidemics of the 21st
century.
SINCE THE ADVENT OF VIDEO DISPLAY
terminals and personal computers, a condition
known as Computer Vision Syndrome, or CVS,
has been on the rise. Millions of computer users
commonly complain of eyestrain, headaches,
blurred and double vision, dry and irritated
eyes, photophobia, and neck and/or back pain.
According to some reports, the diagnosis and
treatment of these symptoms costs almost $2 billion each year. As computer users become more
concerned with CVS, it is important that ophthalmologists be made aware of this rapidly evolving
disorder and determine whether or not it should
be termed a ‘syndrome.’ This installment of
Therapeutic Topics will investigate the methods
of evaluating CVS, examine its suspected causes
and review the current treatments.
Diagnosis
We have all encountered patients complaining of problems associated with computer use
(Figure 1). However, these symptoms can be
By Mark B. Abelson, MD
and George W. Ousler III, BS
vague, and may be related to problems like
chronic fatigue or stress-related disorders.
To diagnose a patient with CVS properly, we
must first eliminate other possible causes of discomfort. For example, blurred vision can result
from uncorrected refractive error (e.g., hyperopia, myopia, astigmatism), improper prescription
lenses or presbyopia. Known muscle disorders
such as phoria or tropia may induce eyestrain
and headaches. Cataracts or corneal scarring can
result in glare symptoms.
Ask patients about their computer usage, habits and workstation ergonomics. These questions can often provide insight for diagnosis and
potential treatment. If the patient’s complaints
continue to include the described symptoms, all
other possible causes have been ruled out, and
computer usage exceeds more than two consecutive hours per day, then more often than not the
patient is suffering from CVS.
Symptoms of the syndrome in
question are often both ocular and
musculoskeletal. Any combination of
these symptoms may be present and
should not be taken lightly.
Causes
CVS symptoms can arise from a
combination of visual problems, poor
computer workstation conditions,
and improper computer user habits.
One of the most significant problems is the reduction in a patient’s
blink rate. Studies show that individuals blink approximately 66 percent
less when using a computer. Possible
explanations for the decreased blink
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Figure 1. Common Symptoms of
Computer Vision Syndrome
Eyestrain
Headaches
Blurred and Double Vision
Dry and Irritated Eyes
Photophobia
Neck and Back Pain
rate include concentration on the task
or a relatively limited range of eye
movement. Consequently, the tear film
gets replenished less frequently and
evaporates more quickly, causing ocular
discomfort.
Improper ergonomics may also influence symptoms of CVS. The placement of a video display terminal often
requires individuals to gaze upward,
widening their interpalpebral fissure.
This increases the exposure of the ocular surface to the environment, contributing to the accelerated loss of the tear
film. This viewing angle may also result
in incomplete interpalpebral closure,
further enhancing a deficiency in lubrication by the blink reflex.
The process by which an image is
displayed on video display terminals
can also induce ocular discomfort.
The images consist of thousands of
tiny, bright spots, better known as pixels, which collectively form an unresolved image that lacks sharp edges.
This requires the user’s accommodative
mechanism to refocus continuously,
inducing ciliary muscle fatigue. The
result can include blurred or double
vision, headaches, eyestrain and irritated eyes.
The lighting conditions of a workstation can also adversely affect a computer user’s ocular comfort. The constant,
bright illumination of overhead fluorescent lighting, large windows and/or
desk lamps often washes out the images
of video display terminals. Improper
screen settings or reflections of objects
located near the computer can also
interfere with viewing. This causes the
user to focus intensely in order to properly process the images.
In addition to ocular symptoms,
many individuals develop bodily symptoms as well. If the patient’s focal length
is inappropriate for viewing the screen
(the ideal viewing distance is 20 to 24
inches), or if glare is present, many individuals will position their head, neck,
or back awkwardly to achieve adequate
viewing of the screen. After extended periods, this adapted posture is the
perfect recipe for musculoskeletal pain
of the neck and shoulder. Brow and
facial muscle fatigue or spasms may also
develop.
Treatment
When treating a patient, we should
consider both ocular therapy and the
adjustment of the computer user’s
workstation and/or habits.
Lubricating drops. These are a simple and effective therapy for the inevitable reduction of an individual’s blink
Figure 2. Etiology and Suggested Therapies of Computer Vision
Syndrome
ETIOLOGY
SUGGESTED THERAPIES
Refractive Problem
Viewing Distance (ideally, 20 - 24
inches from VDT)
Scheduled Breaks from VDT/Prism
Lower VDT/Modify Posture/
Patient Awareness
Brow and Facial Muscle Massage/
Patient Awareness
Frequent Use of Lubricant Eye Drops/
Lower VDT/Increase Blink Rate
Correct Adverse Environment
Factors (e.g., Humidifier)
Equalize Lighting/Anti-reflective
Screen Filter
Phoria / Tropia
Musculoskeletal Pain
(e.g., Neck and Shoulders)
Brow and Facial Muscle Fatigue
or Spasm
Ocular Surface Irritation/
Reduced Blink Rate
Adverse Environmental Factors
(e.g., Air Conditioning)
Screen Glare
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rate and tear film. An over-the-counter
tear substitute can periodically rewet
the ocular surface, contribute to tear
volume, and maintain the proper balance of salts and acidity while viewing a
terminal. Prescribe them PRN.
Adjust the monitor. To further minimize the drying, recommend that the
patient position his video display terminal 10 to 20 degrees below eye level.
This minor alteration allows patients to
gaze downward, narrowing the interpalpebral fissure, improving the fullness of
the blinks, and reducing tear film loss.
This more natural posture also can help
alleviate musculoskeletal pain.
Relax accommodation. To minimize
accommodative spasms caused by
video displayed images, recommend
that the patient vary his focal point, or
look away from the computer screen,
at least one to two times every hour
of computer usage. This provides the
patient with temporary relief from
the continual visual accommodation
and glare of the monitor. Available on
the market today are Windows-based
interactive software programs (e.g.,
Vision Guard, www.visionguard.com),
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REVIEW Therapeutic Topics
The Effects of Computer Use on the Ocular Surface
designed to remind individuals when
to perform these exercises and relax
their eyes.
Get the light right. In the ideal environment, all objects in the patient’s
visual field should be equal in brightness. The light should never be behind
the video display terminal. By the same
token, computer users should not work
in the dark. The contrast between computer-generated light and lack of background light can lead to symptoms.
It should go without saying that a
light should not be aimed directly at the
computer monitor. This will result in
glare. If direct light is present that can’t
be altered, an anti-reflective screen filter may help reduce the glare.
Using a computer for as little as 45 minutes results in a drop in blink rates
of 57 percent, leading to significant keratoconjunctivitis and discomfort.
Those were among the results of a study we completed here in our center.
To measure the effects of computer use on the ocular surface, we performed baseline exams on healthy computer users. We then placed them
in a room we call the Controlled Adverse Environment Model, or CAE. The
room, which contains a computer, has regulated humidity, temperature and
airflow.
We assigned all the subjects tasks to perform on the computer. Half of
all the subjects administered lubricant eye drops 15 minutes after exposure.
The rest received no treatment at all. The users were asked to evaluate their
ocular comfort at 15 (pre-instillation), 20, 25, 30 and 45 minutes. After exposure, subjects underwent exit examinations, including slit-lamp, fluorescein
staining, tear break-up time, blink rate and visual acuity.
All the subjects demonstrated a mean increase in keratitis by 1.3 units
(on a 4-unit scale), a mean increase in conjunctival fluorescein staining of
2.9 units (on a 4 unit scale), an 18 percent decrease in mean tear break-up
time, and a 57 percent decrease in blink rate. The drops resulted in a mean
improvement of 1.1 units on a 4-unit subjective comfort scale. The relief
lasted 15 to 30 minutes after drop instillation. Untreated subjects’ ocular discomfort scores remained the same or worsened during the same time period.
The Future
It’s reasonable to believe that as
our society’s dependence on computers, on-line services and the Internet
increases, so too will the frequency
Figure 3.
The ideal position for using a VDT. The screen
should be 20 degrees below the line of primary gaze.
and severity of CVS. What we need is
prevention, not a short-term remedy.
We need a global treatment plan
encompassing not only ocular agents
but also patient education and ‘user
friendly’ workstations. Then, perhaps
what some are calling the “ocular epidemic of the 21st century,”will soon
be ancient history. RO
Reprinted with permission of the American Optometric Association
Dr. Abelson, an Associate Clinical
Professor of Ophthalmology at the
Harvard Medical School, consults in
ophthalmic pharmaceuticals.
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‘The Effects of a Lubricant Eye Drop on the Signs
and Symptoms of Computer Vision Syndrome
(CVS) Exacerbated in a Controlled Adverse
Environment.’ Abstract. ARVO 1999. Volume 40;
No. 4: S540.
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