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

ASTHENOPIACaused by convergence &

accommodation difficulties

Very common complaint among VDU users

40% VDU operators suffer from asthenopic symptoms

ASTHENOPIA SYMPTOMS DUE TO Ocular status

Personal factors

Workstation factors

Environmental factors

OCULAR STATUS

Minor refractive error

Astigmatism

Convergence insufficiency

More likely to develop myopia

PERSONAL FACTORS

General fatigue Ill health Migraine } -physiological factors photophobia

Anxious Stress } –psychological factors

WORKSTATION DESIGN

Lightning Glare Colour contrast Alpha numeric design

LIGHTNING

Correct level of illumination Using up lighters – reduce glare - reflection

GLARE

Caused by bright sources of light Light from window or artificial light

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

Eliminate screen reflections Filter panel Anti reflection coatings

Colour contrast Colour of phosphors used for VDUs varies

ALPHA NUMERIC DISPLAY

Visible

Legible

readable

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

SYMPTOMS OF ASTHENOPIA

Ocular symptoms

Visual symptoms

Systemic symptoms

Functional symptoms

OCULAR SYMPTOMS

Sore Tired Itching Dryness Burning Aching

VISUAL SYMPTOMS

Focusing problem

Blurred vision

Double vision

Fixation problem

SYSTEMIC SYMPTOMS

Headache

tiredness

FUNCTIONAL SYMPTOMS

Behavioral changes

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

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

To Prevent

Glass sheet between the operator & the screen

Periodic cleaning of the VDU screen with antistatic solution will control the dust accumulation

EPILEPSY Some people suffer from epilepsy Rare condition Known as photosensitive epilepsy

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

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.