Occupational Optometry - Computer Vision Syndrome

1. SPECTACLE FOR COMPUTER USE

2. WHY DO
COMPUTERS CAUSE EYE STRAIN ?
• Accommodation:
Computer use requires
focusing & refocusing and
eye alignment at 45-75 cm
for long time
• Vergence: When viewing computer screen,
eyes become locked in this close range,
increasing near-sightness or myopia
• Dry eye: With sustained fixation, the eyes
do not blink enough, so they dry out

3. EYE STRAIN DUE TO
WRONG MONITOR SETTING
FOLLOWING MONITOR SETTING
AFFECT EYES
• REFRESH RATE refers to how often your monitor
redraws the content on the screen 70 hertz
or higher is better
• RESOLUTION refers to monitor's pixel density
• The more pixels, the higher the level of detail and less
eye strain
• DOT PITCH affects the sharpness of the display
Lower the number, the sharper the image
0.28 or lower is desirable

4. THE MONITOR VS. PRINTED PAGE
THE SIGNAL FROM THE
MONITOR IS NOT AS GOOD
AS THE PRINTED PAGE
• A monitor is a dynamic signal, in that screen is
constantly being redrawn
• A monitor creates images on the basis of varying
light intensity through a fixed set of red, green and
blue points. This results in less distinct edges, and
lower contrast
• The illumination of points on a monitor is not sharp,
but is somewhat rounded.

5. COMPUTER VISION SYNDROME (CVS)
TYPICAL SYMPTOMS
• Fatigue
• Eyestrain
• Headaches
• Slow focusing
• Tired, burning eyes
• Neck and shoulder pain
– Frequent bending forward & backward
• Blurred vision at distance

6. 9 STEPS TO REDUCE CVS
1. Get a computer eye exam
2. Use proper lighting
3. Minimize glare
4. Blink more often
5. Take frequent breaks
6. Exercise and stretch your eyes
7. Adjust the settings of your computer screen
8. Modify your workstation
9. Use separate eye ware for computer use

7. AVAILABLE
CORRECTIVE METHODS
1. FULL VISION READING GLASS
2. HALF EYE READING GLASS
3. TWO SEPARATE SPECTACLE
4. BI-FOCAL SPECTACLE
5. TRI-FOCAL SPECTACLE
6. REGULAR PROGRESSIVE LENSES

8. AVAILABLE CORRECTIVE METHODS
1. Full vision reading glass
Full vision reading glass
• Clear near vision
• Distance blur
• Move close to monitor to see clearly.
• Need Tint and ARC
• Creating neck & back pain and CVS

9. AVAILABLE CORRECTIVE METHODS
2. Half eye reading glass
Half eye reading glass
• Clear near vision
• Distance blur
• Must lower heads to an unnatural 15- 45° tilt
• Suitable for patients, just becoming presbyopic
• Creating neck & back pain and CVS

10. AVAILABLE CORRECTIVE METHODS
3. Two separate spectacle
• Clear near vision with reading glass
• Clear distance vision with second glass
• No Intermediate vision
• In-convenient in keeping two spectacle

11. AVAILABLE CORRECTIVE METHODS
4. Bi-focal spectacle
• The segment may be too low and set for 30cm
• Near vision through lower lens area
• Lift their heads by 25°
• Visible bi-focal line
• Strain in neck and shoulder muscles

12. AVAILABLE CORRECTIVE METHODS
5. Tri-focal spectacle
Tri-focal
Intermediate vision
• Top of the glasses are for distance
• Intermediate area for the computer use
• Bottom segment for reading and keyboard
• Visible tri-focal lines
• Inconvenient and Outdated

13. AVAILABLE CORRECTIVE METHODS
6. Regular progressive lenses
• Multi focal / Graduated power Design
• Lift their heads 25°
• The reading area may not be high enough
• Intermediate channel is not wide enough
– (Hour Glass)
• Outside of channel are distorted

14. WHAT ARE
COMPUTER EYE WARE ?
• They are different from usual glasses
• They need special prescription
• Using different lens design
• Special lens treatments
• Optimum visual comfort and work
efficiency
• Ideal solution for CVS

15. WHO NEED
COMPUTER EYE WARE ?
INDIVIDUALS WITH THE FOLLOWING
DIAGNOSED CONDITIONS OFTEN REQUIRE
COMPUTER GLASSES
• PRESBYOPIA
• HYPEROPIA
• MYOPIA
• ASTIGMATISM
• HETEROPHORIA
• DRY EYE
• CONVERGENCE INSUFFICIENCY
• DISORDERS OF ACCOMMODATION

16. COMPUTER EYE WARE
DIAGNOSTIC INSTRUMENTS
This System simulates the real
characteristics of computer
screen in the doctor's clinic
and cause eyes to react the
same way as they do when
you sit in front of computer
in your office
This allows the doctor to
determine the exact
correction and prescribe
suitable computer eye ware
E.g.. PRIO Diagnostic System

17. SIGNIFICANCE OF LENS MATERIAL
IN COMPUTER EYE WARE
• CROWN GLASS:
– Best optics and scratch resistant
– Heavy and not safe, therefore not used very much
• CR - 39: Standard plastic, excellent optics
– Good for small and medium prescriptions
• POLYCARBONATE :
– Thin, light and strong - Safest lens
• HIGH INDEX :
– Good for higher prescriptions
– Need Scratch resistant and Anti-reflective coatings
• PHOTOCHROMIC:
– No significance in computer eye ware

18. SIGNIFICANCE OF LENS COATING
IN COMPUTER EYE WARE
• ULTRA-VIOLET (UV) COATING:
– Monitors do not emit UV light
– So computer eye ware do not need UV coatings
• ANTI-REFLECTIVE COATINGS (ARC):
– Reduce reflection and back glare
– Available in gold, green and blue color
• SCRATCH RESISTANT COATINGS (SRC):
– This clear coating hardens to provide a durable,
tougher lens
– Scratch resistance does not mean scratch proof

19. SIGNIFICANCE OF TINTING
IN COMPUTER EYE WARE
• THE TINTING:
– Recommended for working in a bright lit office
– This can cut the amount of light that reaches
your eyes and provide relief
– But tints and filters don't address the underlying
cause of computer eyestrain
– Example: Melanin tint
• POLARIZATION:
– These lenses provide excellent clarity and
maximize visual acuity by minimizing glare

20. SPECTACLES
FOR COMPUTER USE
1. NORMAL VISION SPECTACLE
2. COMPUTER READING GLASSES
3. OCCUPATIONAL PROGRESSIVE
LENSES
4. FLIP FOCALS OR CLIP-ON LENSES
5. PIN HOLE SPECTACLE
6. PC MAGNI VIEWER

21. 1. NORMAL VISION SPECTACLE
as computer eye ware
• For people
with normal vision
• Have +0.25 D add power
• Idea is not to add magnification
• But to move focal point closer without using eye
muscles for accommodation
• Need ARC and tinting
• Rimless frame
• Height only 26 mm to permit viewing “underneath”
to focus key board etc

22. 2. COMPUTER READING GLASS
as computer eye ware
• DESIGNED TO
SEE AT 45 – 75 CM
• ANTI GLARE COATED & TINTED
• EFFICIENT PROTECTION & REDUCE EYE STRAIN
Normal Reading Glass Computer Reading Glass
+0.75 to + 2.00D + 1.00 D
+2.00 to + 2.50D + 1.25 D
+2.50 to + 3.50D + 1.50 D

23. 3a. OCCUPATIONAL PROGRESSIVES
as computer eye ware
Occupational Progressive
• Multi-focal aspheric progressive design for
both near and intermediate vision
• Lower half for near vision correction
• Upper half for mid range vision up to 2.50 M

24. 3b. OCCUPATIONAL PROGRESSIVES
as computer eye ware
• Wide intermediate
area for computer use
• Benefit from a natural
head and neck position
• Ideal solution for CVS
AVAILABLE
BRANDS:
• Power continuously reduced to: AO COMPACT
+0.75 D for + 0.75 to + 1.75 NV Zeiss RD
+1.25 D for + 2.00 to + 3.00 NV Panorama Mini
ESSILOR
Kodak Precise

25. 4. FLIP FOCAL SPECTACLE
as computer eye ware
FLIP FOCALS IS A PAIR OF
CLIP-ON ENHANCEMENTS
• For Bifocals and progressives
• Clip – on half frame glasses
• Focus on monitor 45 – 75 cm from eye
• Flip down lens for screen viewing
• Flip up lens for normal viewing (distance)
• Screen park holder, park on monitor
• Poly carbonate, simply clip into frames

26. 4. FLIP FOCAL SPECTACLE
as computer eye ware
Flip Focals Power calculation
WORKING DISTANCE CLIP ON READING GLASS
30 – 48” + 1.00 D +0.75 to +2.00 D
24 – 42” + 1.25 D +2.00 to +2.50 D
18 – 36” + 1.50 D +2.50 to +3.50 D
- Based on working distance from monitor
- Approximately half of reading glass power

27. 5. PIN HOLE SPECTACLE
as computer eye ware
• Low cost
• No glare problem
• Increased depth of field
• The focusing effort or accommodation
is reduced
• Good solution for CVS

28. 6. PC MAGNI VIEWER
as computer eye ware
• Small screens appear much
larger, sharper and more distant
• Large size and sharpness reduce
accommodation problems, so
the eye no longer needs to
constantly refocus
• Distant-appearing text lets your
eyes stay parallel, so eye
muscles relax
• Economically better than buying
a large monitor

29. HOW TO CHECK THE QUALITY OF
COMPUTER GLASSES ?
• The lenses and its material should be of
good quality
• There should be no aberrations in the lens
• Lenses must be centered both vertically and
horizontally in front of the eyes
• There should be no spaces between the
lenses and frame
• The lenses should be tilted 15 degrees
towards the cheeks
• The frame should be slight wrapped to
match the contour of the face

30. SELECTION & CARE
• Wide choices are available in computer
eye ware
• Selection depends on occupational
conditions, taste, and budget of people
• Care must be taken in prescribing the
power of computer eye ware
• Need special lens design & treatments
• Coating and tinting gives good result
• Ergonomics is also important