Computer vision syndrome by hala

Disclaimer
No financial interest.

Computer Vision Syndrome (CVS)
Topics
• Introduction.
• Definition?
• Who can be affected?
• Symptoms :Identifying if I have CVS?
• Factors contributing &Mechanism: Why and How
this happens?
• Complications: Risks From Untreated CVS.
• Examination: How Is Computer Vision Syndrome
Diagnosed?
• Prevention: How to guard against CVS?
• Treatment of Computer Vision Syndrome?
• Conclusion.

This syndrome is gaining importance in this modern era because of the
widespread use of technologies in day-to-day life.

CVS or digital eye strain
A group of eye and vision-related problems
that result from prolonged computer, tablet,
e-reader and cell phone use.
Repetitive strain injury
 Sore eyes
 sore neck
 Sore back
American Optometric Association

Who can be affected?
• Anyone who exceeds two hours of Computer use a
day is at a risk for CVS.
All professions that use computers (IT, BPO,
Accounting, banking, front office) students and
children..
Almost everyone nowadays!
• The prevalence of CVS among computer users ranges from 32%–90%.
• The incidence is directly related to the number of hours spent in front of “visual display
terminal.

Identifying CVS --- Do I have CVS?

External Ocular Internal Ocular
Extra-Ocular
Ocular

Ocular dryness or Tearing.
Burning, Irritation.
Increased sensitivity to light : photophobia.
Feeling that you cannot keep your eyes open.

Asthenopia- Eyestrain-Sore tired eyes.
Blurring of vision- Acquired myopia “short sightness,.
Headache.
Diplopia.

Neck, shoulder, back, arms ,wrist pain.

Internal Ocular
Visual –ocular balance:
-Uncorrected refractive error -
presbyopia.
-Inappropriate glasses .
-Ocular imbalance
“convergence /divergence-
strabismus”
External Ocular:
-Dry eye and tear film dysfunction.
-Dysfunction of Mebomian glands
-Lagophthalmos
-Sjogren’s syndrome
-Eye disorders or inflammations.
Behavior:
-Decreased blinking rate.
-Prolonged viewing.
-Improper seating-
viewing distance and
angle.
-Reduced Resolution, sharpness , contrast.
-Glare of the display.
-Small screen.
-Workstation setup.
-Room Light.
-Room temperature.
Environmental
Device
Personal

Personal
Behavior
External Ocular
Internal Ocular

1- External Ocular
-Dysfunction of Mebomian glands( is the
leading cause of evaporative dry eye).
-Lagophthalmos (the inability to fully close the
eyelids-> evaporative dry eye & exposure
keratopathy).
Eye disorders or inflammations.
Dry eye and tear film dysfunction.
Sjogren’s syndrome (SS) Keratoconjunctivitis sicca
autoimmune disease causes severe dry eyes.
“lacrimal secretion impairment.

• Tear film  lubrication of ocular surface.

• Prolonged Staring at the screens 
• Concentration.” reflex inhibition of blinking” 
• Small font size and low contrast of suboptimal quality monitors 
• Compared to reading a textbook, one uses a horizontal gaze when reading a
computer monitor 
 blinking ( Incomplete blinking and Reduced blink rate )

Normal blink rate :20-22 times /minute.
During computer blinking rate: 4-6 times /minute.
** contact lens wearers

• Uncorrected refractive error- Inappropriate
glasses for computer use.
• Presbyopia.
• Amblyopia.
2- Internal Ocular:
Visual/Refractive

• Strabismus.
• Convergence /divergence.
Ocular Imbalance

How our eyes auto focus to see near object clearly?
Near response

1- Miosis (pupil constricts to sharpen vision).
2- Convergence (Medial Recti contracts) Eyes turn inward when view near target.
3- Accommodation (ciliary muscle contract- lens power more convex to auto focus).
Near response
Auto focus (Lens Power change –0.50 to –0.75 dioptre (D)) to view near target clearly.
temporary of refraction.
• These shifts are so small and transient (return to baseline values by the end of workday.
• distant visual acuity is not affected.
Myopic shift:
change of eye power to the myopic side .. Short sightness

• Prolonged Near work
changes in both relative accommodation and vergence.
With repetitive actions failure to relax the
accommodation after completion of the near task
 internal muscle spasm = Asthenopia &eye strain.
• The degree of accommodation is increased with
increased time and when the screen is more near.
Accommodation spasm—eye strain.
–8.00 !

Prolonged Near work which requires high visual demand

3- Behavior
• Decreased blinking rate. “++dry eyes”
• Very close Near viewing. “++ visual demand”
• Prolonged focusing-Addiction “++ all symptoms ”

Device
Resolution &Contrast
Glare
Screen size

Reduced Resolution and sharpness -
Poor contrast.
The text and images on computer screens are composed of small pixels and when
there are fewer pixels, the resultant decrease in resolution causes excessive
demand on one's visual system.
“++ visual demand”

Glare
Glare of the display.
Low refresh rate flickering.

Screen size
• Small screens. Requires too much near
work response. “++ visual demand”

Workstation
Light Temperature
Environmental

Improper seating .
viewing distance and angle.
“++ extraocular symptoms”

• Awkward positions
Awkward or unnatural posture during using
computer/tab/mobile use

 neck, shoulder , back ,arms and hands pain.
“++ extraocular symptoms”

• Direct Glare.
• Veiling reflections.
• Indirect reflected glare.

Risks From Untreated CVS
• Dry eyes
corneal erosions 
risk of
(Dry eye patients potentially have decreased corneal and conjunctival sensitivity
due to the deficiency/instability of the tear film that may make the superficial nerve
endings susceptible to damage.)
• Poor visual functions- Possible increase in errors –
myopic shift” acquired error of refraction and
myopia”

• Consistent eye strain and Dry eye causes people to arch their foreheads
in an effort to see better 
. The blue light emitted from such
devices can trigger a stronger sense of wakefulness in the brain.

• Neck pain.
• Back pain,.
• Shoulder pain, shoulder tendonitis.
• Elbow epicondylitis.
• carpal tunnel syndrome
venous thromboembolism. reported

1. Vision and Optical assessment:
Determination of visual acuity.
Determination of refraction:
If there is realerror of refraction and there is a need
to spectacle power for distance or for near.
• People with refractive errors(myopia- hypermetropia-Astigmatism)
till age of 40 need distance glasses ,they can use to all activities.
• Myopia due to too much accommodation- needs no glasses.
• People above 40 ,they naturally lose accommodation gradually
(presbyopia), so they can’t auto-accomodate like before-> must
wear glasses for near activities only so it will be ( + ) additional
glasses if they have glasses for distance.

=cycloplegia =Cycloplegic refraction. (diagnostic and
therapeutic as it relieves the spasm.)
the patient will not
accommodate (but it will not eliminate effect
of spasm of accommodation esp if severe).
Determination of degree of Accommodation
The routine method gives false results sometimes, we can’t rely on.
Esp of there is history-symptoms-myopia.
Some opticians prescribe false glasses!

• May be prescribed glasses.
(wrong-unneeded )
After Cycloplegic refraction: accommodation spasm
is relaxed and no myopia.
Without accommodation
With accommodation
Initial examination

After Cycloplegic refraction: accommodation spasm
is relaxed and no myopia.
• May be prescribed glasses.
(wrong-unneeded )
Without accommodation
With accommodation
Initial examination

• Overlooked and need glasses.

2. Orthoptic and ocular motility evaluation:
• Ocular muscle coordination and Convergence evaluation.
• Steropsis and binocular vision assessment.

3. Complete eye examination :
fluorescein 1 % at the slip lamp with cobalt
blue light
Staining Lissamine green, rose Bengal.
Fluorescein staining ,Epithelial thickness.
Slit lamp evaluation of lid morphology, expression of
Meibomian glands.
Blink evaluation (rate / complete or not).

application of a filter paper test strip in the inferior temporal conjunctival sac
of both eyes. If anesthetic is applied, the inferior fornix should be blotted to
remove residual fluid. The strip is removed after 5 minutes and the length of
the tear wetting is measured in millimeters. A reading of 10 mm or greater is
generally considered the cut-off for a normal value for both tests. An
abnormal finding is highly suggestive of aqueous deficient dry eye.
Tear film stability: TBUT tear break-up time.( local evaporation from the tear film surface.)
moist fluorescein strip in sac - time in seconds between a blink and the
appearance of a dark spot in the fluorescein is the TBUT.
Tear turnover rate& tear clearance: Fluorescein clearance.
Sjogren’s disease: Serological test.
Tear volume: Schirmer test.
Schirmer 1 with anaesthetic measures the basal aqueous tear production.
Schirmer 2 without anesthetic additionally measures reflex tearing.

-Enhancement of Resolution, sharpness , contrast.
-use Anti-Glare filters.
-Bigger screens (working or watching or reading).
- Proper Workstation setup.
- Adjust Room Light.
- Adjust Room temperature.
Behavior:
- blinking frequently.
- Take breaks. 20 20 20.
- Stop un-necessary work
& find alternatives.
- Sit far.
- Exercise at computer.
Ocular:
- Management of Dry eye.
- TTT of ocular conditions.
Visual– ocular balance:
-Correction of refractive error
- glasses.
-Management of strabismus.
Environmental
Device
Personal

Personal Behavior
Ocular
Visual

Ocular
• Get your eyes checked and treated if you have
any dryness or eye inflammation.

Visual
• Wear if there is any Errors of refraction (myopia-
hypermetropia- Astigmatism).
• Wear presbyopia (any person above 40).
Unfortunately, the glare protection from an anti-reflective coating is very slight.
These lenses may serve as a supplementary option
 can partially filter high-energy short-wavelength light (blue-light) to affect the retina.
 very slightly increase the light transmission of eyeglass lenses, but the increase is so
small almost no one notices it.
Adequate glare protection but it is only available in darkly tinted
lenses.

Behavior
• Remember to blink more often.
• Use lubricants while working to maintain good
tear film.

Behavior
Look Far in between
Take Breaks
• Get habit of Frequent quick look far while
working at the wall clock.
• 20 20 20 rule: Every 20 minutes, look away
from your computer and look at something
20 feet away for 20 seconds. This will give
your eyes a chance to refocus.
Taking regular small breaks after working for 2 hours, 15 mins, may relax
accommodation process of the eyes, thereby preventing eye strain.

Behavior
• Try to reduce un-necessary near activity–
stopaddiction for adults and children .

Behavior
Play enhance fine motor skills- activity- intellectual.
• Find alternatives to your children

• Find alternatives to yourself.
Behavior
Practice your hobbies or start a new one.

Behavior
• Neck and Shoulders:
Chin Tuck: Slide your chin inward, don’t bend your neck up
or down. practice initially against a wall.
Tuck chin in, attempting to touch back of neck to the wall.
Head Side to Side: Bend your neck so left ear
approaches left shoulder, then repeat for right.
Shoulder Rotation-Shoulder rolls::
Circle your shoulders, then reverse directions.
Neck Rotation: Slowly rotate your head as far as comfortable to the
right, then left.
Neck Rotation
Shoulder Rotation
Head Side to Side

Shrug:
Slowly raise your shoulders toward ears and hold for a few
seconds. Gradually bring shoulders down and relax.
Shoulder Blade Retraction :
Pull your shoulders down and back.
Behavior
Shoulder Blade Retraction
Shrug
Cross-body arm stretch
Shoulder stretches
Cross a straight right arm across your chest and
use your left hand to gently pull your upper
right arm closer to your body. Hold for 5
seconds, relax and repeat with the left arm.

Behavior
Arms:
Arm Relaxation: Drop your arms and hands
to your sides. Gently shake them for a few
seconds.
Arm Rotation: Raise your arms in front of
your body. Rotate arms so palms face up,
then rotate so backs of hands face each
other.
Arm Rotation
Arm Relaxation
Stretch Up: Sit up straight and imagine a cable
attached to the top of your head. Gradually
stretch to be as tall as possible, hold for a few
seconds, then relax.
Stretch Up
Back:
Shoulder Squeeze: Raise your arms in front of body, with elbows
bent and thumbs up. Pull elbows back, squeezing shoulder blades
together. Hold for a few seconds then release.
Shoulder Squeeze

Feet:
Behavior
Foot Rotation: Circle foot slowly from the ankle, then reverse.
Toe Curl: Flex toes up, then curl toes under. Release.
Hands and Wrists:
Finger Fan: Spread your fingers as far apart as
possible, hold, then clench fists, then release.
Wrist Flex: With your elbows on desk, gently use left hand
to bend right hand back toward forearm. Hold for a few
seconds, then relax. Repeat on other side.

• Enhancement of Resolution, sharpness and
contrast.
Poor resolution

Glare
• Use Anti-Glare of the display.
• Make screens away from reflected light
(window or headlight).

or watch
Read
on bigger screen.
Screen Size
Use Bigger screens.

Laptop computers are not ergonomically designed
for prolonged use. The monitor and keyboard are
so close together that they cannot both be in good
positions at the same time.

Environmental
Workstation
Light Temperature

Workstation setup
Key objects
(documents-phone).
Desk
Laptop ergonomics.

Height of chair
• Adjustable
• so that your feet rest
flat on the floor or on
a footrest and your
thighs are parallel to
the floor. (when
sitting at knee level”
Base: wheels: 5 stars base
for stability wheels.
Surface :
• Non slip surface.
• Chair can be tilted
forward slightly” hips
will be slightly higher
than knees when
sitting”-
Chair
backrest: upright with slight
rear lean (90-110 ) /supports
your spinal curves.
Adjust the Adjust
armrests so your arms
gently rest on them
with your shoulders
relaxed. Arm rest at
elbow height.

Monitor
Distance: Place the
monitor directly in
front of you, about an
arm's length away.
Level: The top of the
screen should be at or
slightly below eye level.
If you wear bifocals, lower
the monitor an additional
1 to 2 inches for more
comfortable viewing.
(adjustable monitor or
monitor riser).

Eyes : at or below top
screen level. Eyes look
slightly downward without
neck bend
Head Upright. slight
forward tilt is ok”
Back. Supported,
maintain natural curves.
Wrists. Supported,
relaxed “without flex”
Knee.
-Relaxed (90:110 ),not
flexed over the chair edge.
-Slightly lower then hips.
Elbow. Right angle
Neck. Relaxed ,not bended
Arms close to the body
Shoulders. relaxed
“down with chest open
and wide” not raised.
Forearms. Supported
,relaxed, horizontal,
parallel
Hands : level of elbow
Fingers. Gentle curve.
Hips sit back in the seat
with hips fully supported.
Feet. on the floor
or on footrest.
Posture
Desk :
Desk height should be at the same level of elbow height.

keyboard & mouse position
Keyboard Ideally the keyboard
detached, on a surface that is flat or
negatively inclined.
Keyboard is close to the edge of the
desk.
Mouse is immediately next to keyboard and
loosely gripped
Wrist-rest if present is used for resting ,not
leaning on while typing
When using a keyboard, your elbows should
be slightly bent with your forearms parallel to
the floor and your wrists should be fairly
straight.

Key objects
Key objects between monitor and keyboard or just beside the monitor.

Desk
Desk height should be at the same level of elbow height.

Ergonomics for laptops
Laptop computers are designed for short-term or mobile use
When using a laptop for significant periods :
• Do not work with your laptop in your lap.
• Prop it up on your desk at a reasonable height. You can use a
laptop riser to achieve that.
• use separate components (different external keyboard and mouse
) that allow for better posture (elbows can rest at 90° by your
side).
• If you’re working in bed (Not recommended) make sure you use an
ergonomic bed tray.

Light
• Indirect light to avoid bright spots on display.
• Windows or lights should not create glare
reflection of display.
• Overhead lighting is the best.
• Fluorescent light with a grid or shield
covering the fixture.

Temperature
keep the humidity at least to 40% to decrease your
risk of developing dry eye.

• Treatment of underlying vision problems (from refractive errors
like farsightedness or myopia or presbyopia), inadequate focusing in
the eyes or eye coordination problems. If there is any refractive
error, spectacles of appropriate power with anti-reflective coating
is to be prescribed.
• Acquired myopia and Accommodation spasm: relief of the
spasm by cycloplegic eye drops together with regulation of use.
Internal ocular & visual:

External ocular: Dry eye
Dry eye symptoms improve after dietary intervention with omega 3 fatty acids
for 3 months.
• Conjunctival goblet cell density increases after Omega 3 fatty acid treatment.
• Omega 3 fatty acid treatment ->decrease tear evaporation rates.
Tear Substitutes keep our eyes moist and decrease irritation
monitor room humidity.
cyclosporin

Extra-Ocular:
• Headache, back pain, shoulder pain are
treated by NSAIDs.

Environmental
Device
Personal
-poor resolution.
-glare.
-small screen.
-Workstation.
-Light.
-temperature.
- Ocular.
- Visual.
- Behavior.

Ocular
Device:
Behavior
Visual
Personal:
Glasses / AR is ok
Dryness-Allergy
Bigger Screen Anti- glare filters Better contrast& resolution
Room light
Proper Seating
Temperature
Eye exam
20 20 20 rule
Take breaks

If resistant strain: need cycloplegic drops to
relieve spasm and will manage the acquired
myopia.
Ocular: manage Dry eye if you have,
put lubricants if prolonged use.
For children stop un-necessary
near activity and replace with
other alternatives.
Eye Strain: reduce near activity.

Sometimes all you need is to change your perspectives

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