computer vision syndrome
CVS:Constructing a New Approach to Visual Ergonomics
How to manage patients with computer vision syndrome � from your office to their
BY JEFFREY R. ANSHEL, O.D.
Symptoms of CVS
Blurred near vision
Blurred distance vision
Tired or burning eyes
Excessive blinking or Squinting
more than three decades in private practice, I've seen an increasing number of
patients with symptoms such as headaches, blurred vision, dryness, tired or
burning eyes and eyestrain. These symptoms, which may also include color
distortion or double vision, are known collectively as Computer Vision Syndrome
Approximately 75% of all jobs in the United
States now rely on computers (Kanitar, et al.) and Metafacts.com reported that
employees in those jobs spend an increasing share of their work hours at the
computer. Adults and children also play video games and use the Internet at
home, as well as rely on "mini-computers" (such as a Palm Pilot, Blackberry or
cell phone) wherever they go, compounding the effects of eyestrain at work. Not
surprisingly, this dramatic shift in the way we use our eyes has led to
I specialize in visual ergonomics, and it's a
topic I believe colleagues ought to pay much closer attention to. With so many
patients suffering from computer-related problems, the ability to diagnose and
treat CVS can be a practice growth engine. Let me show you how.
There's a place for us
Studies estimate that the vast majority (75 to
90%) of those who work on computers experience at least some of the symptoms of
CVS. According to the National Institute for Occupational Safety and Health (NIOSH),
nearly 80% of those who work at a computer for more than two hours a day suffer
from the symptoms of CVS. While less than one in four regular computer users
suffers from carpal tunnel syndrome, three times as many experience CVS.
We can help patients evaluate their work
environments and habits (without physically going into their offices) and can
play an important role in recommending ergonomic changes. In addition, providing
regular vision care and prescribing the right vision aids can help alleviate
patients' symptoms. Treating CVS should drive new referrals, keep existing
patients happy with their contact lenses and benefit the practice financially
through prescriptions for new products and lenses.
Many patients come in for an exam with general,
vague complaints. Contact lens patients are especially prone to say that their
contact lenses, "don't feel as good as they used to," or that they bother them
Optometrists who ask the right questions will
find that these complaints are often computer-related. I ask every patient about
his or her computer use � I've learned never to assume that someone is too old
or too young for that question. If patients are bothered by any of the symptoms
of CVS, I obtain more specific information about their work habits and position
of their computer equipment. I also ask patients to check off symptoms they
experience from a list of about a dozen potentially CVS-related problems (see
"Symptoms of CVS," page 37).
In addition to the questionnaire, I take a full
battery of near-point tests, including binocular balance, fusional reserves and
accommodative abilities. While the symptoms of CVS can manifest in patients who
don't use computers, the diagnosis of CVS is made in conjunction with the
symptoms the computer-using patient mentions.
You might consider a "computer vision
examination" as a separate battery of tests for computer-using patients. Because
our standard exam is now so full of refractive and eye health procedures, a
return examination could be an additional source of revenue. Send patients back
to their offices with a questionnaire that requires them to take specific
measurements of monitor and keyboard distances and elicits the specific lighting
arrangement and other ergonomic conditions. On the return visit, conduct an
environmental review with the data gathered, and perform near-point and dry eye
testing. You can also perform this evaluation right after the routine exam, if
necessary. A fee comparable to the contact lens examination is appropriate.
There are currently no codes for CVS. However,
the symptoms related to computer use (such as eyestrain, accommodative spasm,
etc.) do fall into the category of visual stress. You can legitimately submit
them as such to insurance companies.
eight tips you can give patients to implement right away
to reduce the risk of CVS and make computer work more
your computer monitor five to nine inches below the
horizontal line of sight so that when you look straight
ahead, you look just over the top of the monitor.
2. Sit far
enough away that you can't touch the monitor without
leaning forward. A good minimum working distance is
about 24 to 26 inches.
you use a laptop frequently, get a separate monitor
4. Set computer
monitor contrast at high.
down overall room lighting and use a task lamp for
6. If you have a
window, position the computer so that the window is off
to the side, not directly in front of, or behind the
a note that says "Blink" next to your computer screen.
8. Every 20
minutes, take a 20-second break and look at something at
least 20 feet away.
Treating CVS involves educating your patients
about the appropriate adjustment and placement of computer monitors, lighting
control, good preventive vision care habits and regular professional eye care.
You can also help patients take advantage of new contact lens and spectacle
products designed for CVS and computer-related vision needs.
Improving work habits
Most people sit too close to their computers and
place the monitor too high on the desk, forcing them to look straight ahead or
slightly upward at their screen. An upward gaze exposes 40% more of the cornea,
which dries out the tear film and compounds the effects of the already dry
environment in many office buildings. This is especially hard on contact lens
wearers, who typically struggle with dryness anyway. So the first change I
generally recommend is to lower the computer monitor (see "Visual Ergonomics
101," page 38).
The next biggest offender in office settings is
the lighting. Most offices are far too bright for comfortable computer use, so I
advise dimming overhead lights directly above the computer.
It's also very important to consider work habits
such as how often people take breaks. Studies show that we spontaneously blink
18 to 22 times per minute under normal conditions. But during computer use, most
likely due to the increased visual attention required, the average blink rate
drops to seven per minute, or about one-third the normal rate. I've noticed that
people playing video games blink even less often. This allows the cornea to dry
out and is a significant cause of CVS symptoms.
Lowering the monitor and increasing awareness of
blinking can help patients improve their blink rate. They also need to take
frequent, short breaks from looking at the computer to maintain greater
flexibility in focusing. I recommend the "20/20/20 rule." Take a 20-second break
every 20 minutes. Focus your eyes on points at least 20 feet from your terminal.
Keep your eyes moving while looking at objects at various distances.
to American Optometric Association, Computer Vision Syndrome (CVS) is "the
complex of 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."
additional information, call the AOA Clinical Care
Center at the St. Louis Office at (800) 365-2219 x
244 or 245.
Computer work is particularly stressful for
contact lens wearers. Long, non-blinking phases may cause the surfaces of most
lenses to dry out, which can lead to discomfort and a loss of visual clarity. In
one survey of more than 2,000 current and former contact lens wearers, time
spent in front of a computer was the activity most frequently cited (41%) as
causing discomfort while wearing lenses. Left uncorrected, CVS problems could
lead to contact lens dropout.
Refractive lens issues
It's important that computer users have a
current, accurate spectacle or contact lens prescription and that their contact
lenses are clean, well-fitting and healthy (or their glasses free of dust and
I try to put my contact lens patients in the most
comfortable lens possible in order to alleviate the dryness and discomfort that
most suffer. I've had great success with Acuvue Oasys with Hydraclear Plus (Vistakon),
a silicone hydrogel lens made from senofilcon A.
Even with a lens that's comfortable for them, I
still recommend that patients try to blink more frequently. I also prescribe an
oral nutritional supplement containing essential fatty acids.
all seen for ourselves that children spend a lot of time
on computers, but did you know that:
In the United
States alone, 54 million children (or 90% of school-age
children) use a computer at home or school.
A study at the
University of California at Berkeley found that 25% to
30% of children who use computers need corrective eye
wear in order to work safely on them.
Besides the rise in
what some experts call "environmental myopia" in
children, too many hours spent on the computer may
contribute to other dangers as well. According to the
children's advocacy group Alliance for Childhood, the
high number of hours many children spend on the computer
place them at increased risk for repetitive stress
injuries and obesity. The group warns that children's
visual systems are immature, and long periods in front
of monitors may retard their visual-spatial awareness.
To prevent Computer
Vision Syndrome in children, experts recommend arranging
computer workstations to accommodate a child's smaller
size. This means changing the viewing angle of the
monitor, making sure the child is 18 to 28 inches from
the monitor and placing the keyboard within comfortable
For patients who wear spectacles, I often
prescribe a second pair of glasses. Regular progressive lenses, which so many
patients wear these days, are really not appropriate for intensive computer use.
For the office, I prescribe "computer glasses" with occupational progressive
lenses. Like regular progressive lenses, these have no lines. They feature an
intermediate zone at the top for computer viewing and a near zone at the bottom
for reading material. The lab will compute the prescription for intermediate as
long as you provide the full prescription (distance and add with near PD).
Patients who wear multifocal contact lenses don't
have the same issues as spectacle wearers because the designs vary. Many of
these lenses do allow intermediate vision, but it's important to target them for
the patient's actual working distance to the computer. Those who wear bifocal,
monovision or single vision contact lenses may also want to consider wearing a
pair of computer glasses over their contacts.
If you're interested in visual ergonomic
consulting, be proactive. I ask patients with CVS symptoms who is responsible
for employee health and safety at their workplace. I then contact that person
directly and say that I've seen some employees from the company who have visual
stress related to computer use. I then offer my services in several ways: I can
conduct an on-site evaluation for the individual patient or an evaluation of the
entire workplace. I can also provide a lunch-time "brown bag" seminar on
Providing such services can expand your practice
as you become known as a computer-vision specialist. Of course, you must do this
without violating patient confidentiality.
There's no end in sight to the proliferation of
computers in our lives. Doctors who question patients about computer use,
identify ergonomic problems, and prescribe the right refractive correction and
dry eye aids will reap the rewards of happy patients with improved vision and
ocular comfort. This should keep patients in their contact lenses, bring them in
for regular eyecare visits and generate patient referrals.
References available upon request.
Anshel is the founder of Corporate Vision Consulting and the author of "Visual
Ergonomics in the Workplace." He is also in private practice and is a consultant
for Vistakon and BioSyntrx. Dr. Anshel offers the CVS Eyecare Seminar to train
doctors in becoming specialists in the area. Contact him at (760) 944-1200, or
Optometric Management, Issue: September 2006