Download Parallel light rays are focused directly on the retina.

Dr Wilfred Tang
Head
Singapore Polytechnic Optometry Centre
www.optometrycentre.com.sg
Parallel light rays are focused
directly on the retina.
1
The ability to see near objects clearly
but distant objects appeared blurred.
Normal Vision
Myopic Vision
2
Parallel light rays from distant
objects are focused in front of
the retina.
3
Accommodation - The adjustment of
the lens so that clear images of
objects at different distances are
focused on the retina.
Pseudomyopia - is caused by spasms
of accommodation which may be
associated with prolonged periods of
intensive near work.
Hyperopia-longsightedness/farsightedness
Normal Near Vision
Hyperopia Near Vision
Presbyopia-inability to see near objects
clearly due to weakness in accommodation.
Common during old age. It is not the same as
longsightedness
Hyperopia
Presbyopia
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Also known as “lazy eye”, it can
happen when there is a great
difference in the degree of
myopia between the two eyes.
A condition in which vision at
all distances may be distorted
due to irregularity in the
shape of the front surface
(cornea) of the eye.
% of prevalence defective vision by
educational level
70
60
50
40
30
20
10
0
1990
2000
Primary
1
Primary
6
School Health Service Figures
5
„
„
128 kindergarten children, cycloplegic
refraction
Prevalence of myopia = 8.6%
3 years old: 0%
4 years old: 9%
5 years old: 9%
6 years old: 12.5%
Optometry & Vision Science Vol. 72/5: 286-91 May 2001
„
Retinal detachment
„
Macular degeneration
„
Cataract
„
Glaucoma
“The annual cost of eye examination
and correction of myopia in the US
reaches US$4.6 billion.”
Negative impact on self-esteem,
inconvenience when playing sports or
games and ocular health.
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„
Genetic factors
„
Environmental factors
„
Parental history of myopia
„
Ethnicity : Chinese
„
For examples, reading, writing, drawing,
sewing, playing handheld games, doing
craft work with small objects, etc.
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•Emmetropisation
•Eyes normally used more for distance for
thousands of years
•Modern Society, eyes mostly used for
near
•Disrupts the normal development of the
eyes
≤ 2 books
per week
> 2 book
per week
All participants :
Parental history of myopia
4.8
13.6
None
One
Two
2.5
3.5
9.7
5.3
15.6
23.7
Lancet Vol. 357 : 2001 SM Saw, CY Hong, RA Stone, D Tan
Strategies:
„ Public education
- Mass media campaign
- School programmes
- Parents’ programmes
„ Vision screening
„ Myopia Registry
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• Near work is an important
environmental factor
• Outdoor activities might have
protective effect
Key Messages
1. Spend less time on unnecessary
near work.
• E.g. Playing computer, handheld or
handphone games and other computer
related activities such as blogging and
internet chats
• Encourage children to take a break after 30
to 40 minutes of near work
Key Messages
2. Spend more time on outdoor activities
everyday
• Encourage our children to go outdoors for activities
as a break from their studies/revision
• Examples: sports and non-sports related activities
• Outdoor activities DO NOT include reading or
playing handheld games outdoors.
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„
Hold the book about 30cm away from
the eyes.
„
Sit upright
„
Ensure adequate lighting
„
Choose books with bigger prints
„Take a break after every
30 – 40 min of near work
„ Sit about 50cm away from the
monitor
„
Ensure adequate lighting
„
Adjust monitor to reduce glare
„ Remind child not to engage in this
activity continuously for long hours
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„ Sit at distance from the TV that is
appropriate to its size
„ Screen should be at the
eye level or lower
„
Ensure adequate lighting
„ Limit amount of time spent on video
games and encourage more outdoor
activities
„
Regular exercises to strengthen your
body
„ Eat a balanced diet : 2+2 servings of
fruits & vegetables everyday
„ Sleep at least 8 hours a day to
adequately rest the eyes
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Spectacles
Contact lenses
Lasik
„
Not suitable for children
„
Only correct vision
„
Does not reduce the risk of severe
myopia
Eye drops
Contact lenses
Progressive lenses
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What about available
commercial products?
Are they effective
against Myopia?
Commercial Products
ƒ MOST of these products and services
DO NOT have robust scientific
evidence to prove their effectiveness
ƒ Exercise caution when being
approached by these companies
What about
NeuroVision
Technology?
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NeuroVision Technology…
ƒ Special images to train the visual part of the
brain. Improves the processing of visual
information
ƒ Reduces user’s dependency on spectacles or
contact lenses.
About NeuroVision Technology…
ƒ Effectiveness in managing myopia…
ƒ Effective among adults with low myopia –
ƒ improved vision without need for spectacles.
ƒ Ongoing study for its use in children.
ƒ Preliminary results - improved vision
ƒ Yet to be proven that it is effective
against myopia progression.
Does your child…
•complain of blurred vision while
reading?
•Frequently squint when reading
or watching TV?
•Hold reading closer than normal?
•Make errors when copying from
blackboard to their notebooks?
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More children are
getting myopia
at a younger age.
Severe myopia can lead to
complications
that are potentially blinding.
•Spend more time in outdoor
activities everyday
•Spend less time in continuous
near work
Good eye care habits:
•Adequate lighting
•Proper posture
•Appropriate distance from
the book, computer screen & TV
•Regular exercises
•Balanced Diet
•Sufficient Sleep
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