Visual display unit

Visual display unit

2. VISUAL DISPLAY UNITS
Millions of people of all ages now use VDU
Possible health hazards
Use of VDU that may affect the eyes
Asthenopia
Facial rash/ dermatitis
Epilepsy
Radiation

3. ASTHENOPIA
Caused by convergence &
accommodation difficulties
Very common complaint among
VDU users
40% VDU operators suffer from
asthenopic symptoms

4. ASTHENOPIA SYMPTOMS DUE
TO
Ocular status
Personal factors
Workstation factors
Environmental factors

5. OCULAR STATUS
Minor refractive error
Astigmatism
Convergence insufficiency
More likely to develop myopia

6. PERSONAL FACTORS
General fatigue
Ill health
Migraine } -physiological factors
photophobia
Anxious
Stress } –psychological factors

7. WORKSTATION DESIGN
Lightning
Glare
Colour contrast
Alpha numeric design

8. LIGHTNING
Correct level of illumination
Using up lighters – reduce glare
- reflection

9. GLARE
Caused by bright sources of light
Light from window or artificial light

10. Reduce
Position of VDU screen should be adjusted
VDU contrast & brightness control
Windows be fitted

11. Eliminate screen reflections
Filter panel
Anti reflection coatings
Colour contrast
Colour of phosphors used for VDUs varies

12. ALPHA NUMERIC DISPLAY
Visible
Legible
readable

13. ENVIRONMENTAL CONDITION
Glare free
Involuntary relief of eyes occurs by looking away the
distant object
Noisy equipment should be positioned away from the
operator
Adequate ventilation
Reasonable humidity

14. SYMPTOMS OF ASTHENOPIA
Ocular symptoms
Visual symptoms
Systemic symptoms
Functional symptoms

15. OCULAR SYMPTOMS
Sore
Tired
Itching
Dryness
Burning
Aching

16. VISUAL SYMPTOMS
Focusing problem
Blurred vision
Double vision
Fixation problem

17. SYSTEMIC SYMPTOMS
Headache
tiredness

18. FUNCTIONAL SYMPTOMS
Behavioral changes

19. VISUAL STANDARDS
Ability to read 6/6
Ability to read n6 at 33-75 cm
Well established monocular vision
Well established binocular vision
Near point of convergence is normal
Clear ocular media

20. FACIAL RASH/DERMATITIS
Electric beam of VDU attracts of dust particles
forming dusty layer
Facial rashes common among VDU operators
Complaints may be itching of the skin, reddening
It occurs usually couple of hours & disappear

21. To Prevent
Glass sheet between the operator & the screen
Periodic cleaning of the VDU screen with antistatic
solution will control the dust accumulation

22. EPILEPSY
Some people suffer from epilepsy
Rare condition
Known as photosensitive epilepsy

23. To reduce
Reducing the luminous of the display
Covering the screen with tinted
Operator should wear tinted spectacle

24. RADIATION
Radiation emission from the VDU screen –UV, IR
Weiss & peterson – 1979 & Elliot 1986
concluded that the measured values of
electromagnetic radiation were at below existing
limits
The radiation emitted from VDU is not
considered to be a health hazard.