Computer Vision Syndrome - Dr James Beatty

1. Computer Vision Syndrome
Dr James Beatty

2. Overview
 Introduction
 Symptoms (Ocular, extraocular)
 Diagnosis (Ocular, extraocular)
 Treatment
 Children

3. Introduction
 Increased use of computers in the workplace has
brought about the development of a number of health
concerns.
 Eye related symptoms are the most frequently
occurring health problem in computer uses.
 Many individuals who work at a computer video display
terminal (VDT) report high levels of job-related
complaints and symptoms, including ocular
discomfort, muscular strain and stress.

4. Introduction
 The level of discomfort appears to increase with the amount of
VDT use, and symptoms appear to be different to other near-
point workers.
 Up to 90% of the 70 million US workers using computers for more
than 3hrs per day experience it in some form.
 Based on current evidence it is unlikely that the use of VDTs
causes permanent changes or damage to the eyes or visual
system.
 However, some workers may experience continued impaired or
reduced visual abilities, such as blurred distance vision, even after
work

5. Introduction
 The extent to which an individual may experience symptoms is
largely dependent upon his/her visual abilities in relation to the
visual demands of the task being performed
 High visual demands of VDT work make many individuals
susceptible to the development of eye and vision-related
symptoms
 Uncorrected vision conditions, poor VDT design and workplace
ergonomics and a highly demanding visual task can all contribute
to the development of visual symptoms and complaints
 These visual and ergonomic problems can often significantly
affect worker comfort and ultimately performance.

6. Symptoms
 Eyestrain (Non-specific ocular discomfort)
 Blurred distance vision
 Fatigue
 Headache
 Blurred near vision
 Double vision

7. Symptoms
 Ocular surface: Dry eyes, watery eyes, irritated eyes, contact lens
problems.
 Ergonomic: Neck pain, back pain, shoulder pain.

8. Diagnosis
 Visual dysfunction
– Accommodative disorders
– Presbyopia
– Hyperopia
– Myopia
– Astigmatism
– Binocular vision dysfunctions
 Ocular surface mechanisms
 Extraocular mechanisms

9. Visual dysfunction
 Uncorrected or undercorrected myopia, hyperopia and
astigmatism which under normal circumstances are harmless
become manifest
 Underlying accommodative disorders can lead to decreased
amplitude of accomodation or infacility of accommodation
 Presbyopic patients may have have an improper add prescribed
or spectacle design is incorrect (no intermediate distance,
segment height)
 Binocular visual problems can become manifest with deviation of
phorias and strabismus
 Transient induced myopia from excessive near work..

10. Visual dysfunction
 Mostly after prolonged usage.
 Transient phenomenon, may continue long after use.

11. Ocular Surface Mechanisms
 Enviromental factors (fans, ventilation, static, dust)
 Reduced blink rate (up to 60% reduction).
 Increased staring
 Increased exposure (horizontal gaze with wider palpebral fissure).
 Systemic or ocular cause for dry eye.

12. Extra ocular mechanisms
 Contrast and resolution of the display
– Maximum contrast (black letters on white background)
– Radiation exposure is extreemly low and not harmful.
 Viewing distances and angles
– the top of the screen should be below the horizontal eye level of the
operator and tilted back slightly (10o
-20o
) away from the operator.
– VDT at arms length

13. Extra ocular mechanisms
 Room lighting
– General workplace lighting, glare and images reflected on the VDT
screen.
– ? The value of filters
– Compromise required between that amount of light needed to
enhance VDT screen visibility and reduce reflections and glare and
that needed to perform other office reading and work tasks. Older
individuals will generally require more light than younger individuals to
perform the same tasks comfortably
– Do not place computers in front of windows

14. Treatment
– Enviromental factors (fans, air conditioning, dust,
humidifiers)
– Ergonomics (chair, table, keyboard, VDT
positioning)
– Lighting, anti-glare filters, display quality
– Regular work breaks
– Lubrication
– Glasses (NB presbyopes)
– By far the most common cause is Dry Eye

15. Children and computers
 Children often have a limited degree of self-awareness.
 Children are very adaptable.
 Children are not the same size as adults.
 Children often use computers in a home or classroom with less
than optimum lighting.

16. Management
 Have the child's vision checked.
 Strictly enforce the amount of time that a child can
continuously use the computer.
 Carefully check the height and arrangement of the
computer.
 Carefully check the lighting for glare on the computer
screen.
 Reduce the amount of lighting in the room to match the
computer screen.

17. References
 Blem, Vishnu, Khattak, Mitra, Yee. Computer
vision syndrome. Survey of ophthalmology, Vol
50, No. 3, May-June 2005.
 www.aoa.org (american optometric
association)