Computer vision syndrome is a complex of eye and vision problems related to near work performed on computers. It is characterized by visual symptoms like eyestrain, headache, blurred vision, and dry eyes that result from prolonged computer use. The pathophysiology involves extraocular mechanisms affecting muscles, accommodative mechanisms straining focus, and ocular surface mechanisms drying out eyes. Risk factors include aging, poor ergonomics, lighting, and underlying eye diseases. Treatment focuses on lubricating eyes, improving ergonomics, taking breaks, and managing underlying conditions. Prevention emphasizes modifying lighting and workstation setup, proper eye care, and short breaks to reduce visual demands of computer use.

1. By Eva Sarah Abraham
House Surgeon
Ophthalmology

2. TABLE OF CONTENTS
• DEFINITION
• INTRODUCTION
• AETIOLOGY
• PATHOPHYSIOLOGY OF COMPUTER VISION SYNDROME
• VISUAL ERGONOMICS
• COMMON FACTORS FOUND TO BE RELATED TO
DRYNESS AND REDNESS OF THE EYES
• CONTRIBUTING FACTORS
• VISUAL DEMAND WHILE WORKING WITH COMPUTER
• CLINICAL FEATURES
• MANAGEMENT
• PREVENTION

3. DEFINITION
• American Optometric Association (AOA) defines computer vision
syndrome (CVS) as “Complex of eye and vision problems related to
near work, which are experienced during or related to computer use”
• These include eyestrain, tired eyes, irritation,
redness, blurred vision, and double vision,
collectively referred to as computer vision
syndrome.

4. INTRODUCTION
• Computer vision syndrome is characterized by visual symptoms
which result from interaction with computer display or its
environment . The main ocular symptoms reported by workers are
eye strain, irritation, burning sensation, redness, blurred vision and
double vision.
• These symptoms are usually temporary and disappear at the end of
the working day even though a minority of worker may experience
continuity of symptoms after work. If no intervention is initiated, a
majority of these symptoms will recur and also worsen in the future.

5. AETIOLOGY
• Computer vision syndrome symptoms may be the cause of :
Ocular (ocular-surface abnormalities Extraocular (ergonomic)
or accommodative spasms)
The visual effects of various display characteristics such as lighting, glare,
display quality, refresh rates, and radiation also seem to affect this
condition.

6. PATHOPHYSIOLOGY OF COMPUTER VISION SYNDROME
The symptoms experienced in computer vision syndrome are caused by
three potential mechanisms:
(i) Extra ocular mechanism-
Extraocular mechanism causes musculoskeletal symptoms such as neck
stiffness, pain, headache, backache and shoulder pain. These symptoms are
well associated with improper placement of computer screen which lead to
muscles sprain.
(ii) Accommodative mechanism-
Accommodative mechanism causes blurring of vision, double vision,
presbyopia, myopia and slowness of focus change.

7. Certain studies also reported that a transient myopia was observed in 20%
of computer users at the end of their work shift.
Many people may have slight accommodative problem or binocular
problems which do not usually cause symptoms when they are doing
ordinary less strenuous visual task, but these problems are worsen in
prolonged period of computer usage
(iii) Ocular surface mechanism
Ocular surface mechanism causes symptoms such as dryness of the eyes,
redness, gritty sensation and burning after extended period of computer
usage.

8. Visual ergonomics
• Visual ergonomics is the multidisciplinary science concerned with
understanding human visual processes and the interactions between
humans and other elements of a system.
• Visual ergonomics applies theories, knowledge and methods to the
design and assessment of systems, optimizing human well-being and
overall system performance.
• Includes: the visual environment, such as lighting; visually demanding
work and other tasks; visual function and performance; visual
comfort and safety; optical corrections and other assistive tools.

10. COMMON FACTORS FOUND TO BE RELATED TO DRYNESS
AND REDNESS OF THE EYES
• Corneal dryness,
• Reduction in blink rate,
• Increased surface of cornea exposure caused by horizontal gaze at the
computer screen,
• Reduction of tear production due to ageing process contact lens
usage,
• Medications such as antihistamines
• systemic medical illnesses such as autoimmune connective tissue
disease.

11. CONTRIBUTiNG FACTORS
Personal factor Poor seating posture
Improper viewing distances
Improper viewing angle
Ocular diseases
Medical diseases
Ageing
Environmental factor Poor lighting
Imbalanced of light between
the computer screen and
the surrounding
Computer factor Poor resolution
Poor contrast
Glare of the display
Slow refresh rate

12. VISUAL DEMAND WHILE WORKING WITH COMPUTER
• There is an increased visual demand when one is viewing the display
on the computer screen as compared to reading a printed text.
• As the resolution goes down the image become poor in quality and
the visual demand of a reader has to be increased in order to
appreciate well the wording or image.
• Refresh rate is also known to affect the visual demand.

13. CLINICAL FEATURES
• Accommodation and vergence responses to electronic screens
appear to be similar to those found when viewing printed materials,
whereas the prevalence of dry eye symptoms is greater during
computer operation. The latter is probably due to a decrease in blink
rate and blink amplitude, as well as increased corneal exposure
resulting from the monitor frequently being positioned in primary
gaze.

18. MANAGEMENT
• Treatment requires a multidirectional approach combining ocular
therapy with adjustment of the workstation.
• Proper lighting,
• Anti-glare filters,
• Ergonomic positioning of computer monitor and
• Regular work breaks may help improve visual comfort.
• Lubricating eye drops and special computer glasses help relieve ocular
surface-related symptoms.

20. • Proper distance from the screen, proper adjustment of the image size
and proper height of the seat are all important factors to be
considered.
• It is recommended that the
• eyes should be about 35-40 inches from the screen and that the
screen should be placed 10-20 degrees below or
• that the middle of the screen 5-6 inches below eye level.
• Improved physical ergonomics of the computer workstation has been
proven to reduce ocular discomfort and improve performance.

21. PREVENTIONOF COMPUTER VISION SYNDROME
Environmental factor modification
• Among the most important modifiable external environmental factors is lighting. Acceptable
level of lighting is obtained to minimize visual fatigue. Different age group may require different
light intensity to work with, workers over 50 years of age tends to require twice the light levels
of young adults to perform the same task.
• Imbalanced light between the computer screen and the surrounding is another important
factor to be considered.
• Use of screen filters can reduce glare and reflection of the computer screen, but it should be
used as a supplement and not a replacement for poor lighting of the room
• Screen brightness and contrast should be adjusted to provide balance with room lighting and
maximum visibility.
• Musculoskeletal problems related to head and eye postures can often be prevented by proper
workstation adjustment.

22. Proper eye care
• Taking a short break:-20-20-20 rule
• Dry eyes secondary to decreased blink rate can be easily managed by applying
lubricating eye drops or artificial tears.
• Workers who are using contact lens must be more careful with any ocular
symptom which started acutely such as pain and redness. Complications following
prolonged contact lens usage such as cornea ulcer must be excluded before one
can say that the symptoms are due to computer vision syndrome.
• Use of proper corrective glasses for refractive errors such as myopia, astigmatism
and presbyopia is important to prevent further deteriorating of the ocular
symptoms which can lead to poor work performance and the poor quality of life.
• Workers who have history of medical illnesses such as diabetes mellitus and
connective tissue disease affecting the eyes must be further evaluated.
• A.C.DISTANCE-avoid sitting under direct bow of air.

25. REFERENCES
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potential treatments.’
• www.aoa.org
• Dr.Soman Mani, Dr.Ligi Menon M.,Dr.Harishankar.S,Dr.Anna M ‘Prevalence of computer vision
syndrome,among IT students in a rural engineering College, International journal of current
research,