THE IS REGARDING THE OPHTHALMIC DEFECTS EFFECTING EYE BY USING COMPUTER MONITORS

1. VISUAL DISPLAY UNITS
CIBIN YACOB

2.  Millions of people of all ages now use VDU¢ Possible health hazards
 ¢ Use of VDU that may affect the eyes

3. Cathode Ray Tube Monitors
• Cathode Ray Tube moves an electron gun to and
fro across the screen.
• The beam collides on the phosphor dots present
on the screen and emits light.
• The beam actives the pixels and makes an image
on the screen

4. Liquid Crystal Diode Monitors
• A Cold cathode ray, the fluorescent panel are two
major components of the LCD.
• The cold cathode ray technology is used in LCD which
emits electrons and light up the fluorescent coated
monitor screen.
• The process is known as backlighting. The second
component is a fluorescent panel, which is made of
liquid crystal.
• Liquid Crystal determines is current sensitive and
determines the number of electrons to pass through
the screen to make the shape and image of an object.

5. • The both monitors are based on the same display
technology and provide better resolution.
• However, the difference comes on backlighting as
LCD monitors use Cold Cathode Fluorescent Light and
LED monitors are based on light emitting diode.
• The backlighting impacts badly on the image and
decreases its sharpness and brightness.
• WLED and RGB LED are the two types of LED monitors,
depending on the way LED placed in the panel.
Light Emitting Diode Monitors

6. The cathode rayed tube can easily increase the monitor’s
brightness by reflecting the light.
They produce more colours
The Cathode Ray Tube monitors have lower price rate
than the LCD display or Plasma display.
The quality of the image displayed on a Cathode Ray
Tube is superior to the LCD and Plasma monitors.
The contrast features of the cathode ray tube monitor
are considered highly excellent
Advantages of CRT

7. DisAdvantages of CRT
• The electromagnetic fields emitted by CRT monitors constitute a
• health hazard to the functioning of living cells.
• CRTs emit a small amount of X-ray band radiation which can
result
• in a health hazard.
• Constant refreshing of CRT monitors can result in headache.
• CRTs operate at very high voltage which can overheat system or
• result in an implosion
• Within a CRT a strong vacuum exists in it and can also result in a
• implosion
• They are heavy to pick up and carry around

8. • Produces very bright images due to high peak
intensity.
• Produce considerably lower electric, magnetic and
electromagnetic fields than CRTs.
• No geometric distortion at the native resolution.
Minor
• distortion can occur for other resolutions.
• Take up about 40% less desk space. LCDs are thin and
compact
ADVANTAGES OF LCD

9. • The aspect ratio and resolution are fixed
• Not proficient at producing black and very dark grays. In a
• "standard" configuration, not appropriate for use in dimly lit dark
conditions.
• Lower contrast than CRTs due to a poor black-level.
• Slow response times and scan rate conversion result in severe
• motion artifacts and image degradation for moving or rapidly
• changing images.
Works best at the native resolution. The native resolution can not
be changed. All other resolutions require adjusting procedures
which can cause considerable deterioration of the image
DisAdvantages of LCD

10. CRT/LCD do not emit harmful rays ?
LCD/LED do not emit harmful rays. Older CRT monitors and older CRT
based Televisions (the big bulky boxes) do emit harmful rays and will
damage your eyes.

11. VISUAL DISPLAY UNITS

12.  Millions of people of all ages now use VDU
 Possible health hazards
 Use of VDU that may affect the eyes

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

14. ASTHENOPIA SYMPTOMS DUE TO
 Ocular status
 Personal factors
 Workstation factors
 Environmental factors

15. OCULAR STATUS
 Minor refractive error
 Astigmatism
 Convergence insufficiency
 More likely to develop myopia

16. PERSONAL FACTORS
 General fatigue
 Ill health
 Migraine
 Photophobia
 Anxious
 Stress
physiological factors
psychological factors

17. LIGHTNING
 Correct level of illumination
 Using up lighters – reduce glare

18. OCULAR SYMPTOMS
 Sore
 Tired
 Itching
 Dryness
 Burning
 Aching

19. VISUAL SYMPTOMS
 Focusing problem
 Blurred vision
 Double vision
 Fixating problem

20. WORKSTATION DESIGN
 Lightning
 Glare
 Colour contrast
 Alpha numeric design

21. GLARE
 Caused by bright sources of light
 Light from window or artificial light
 Over Damaging of operating system…

22. Reduce Glare
 Position of screen should be adjusted
 Contrast & brightness control
 Windows be fitted Direct over head of light should away from PC screen

23. That can put a real strain on your eyes. Eye problems caused by computer use fall under the heading
computer vision syndrome
What is Computer vision Syndrome