2. Orthokeratology
• Orthokeratology is the
use of a corneal
reshaping device, to
mould the cornea to
reduce or correct
myopic (short-sighted)
and mild astigmatic
refractive errors of the
eye.
• (Soon Hyperopia and
astigmatism)
3. Corneal Reshaping
Technology
• In some ways it is
similar to the use of
dental braces by an
orthodontist to
straighten crooked
teeth.
• The main difference is
that if a tooth position is
corrected for some
months it will usually
stay in the new position.
4. Orthokeratology
• The cornea is highly
elastic however, and
always returns to its
original shape. For
this reason retainer
lenses are worn
several nights per
week after the ideal
corneal shape has
been achieved.
5. Why Have Ortho-k ?
• The main purpose of
Orthokeratology is to be
free of both contact
lenses and spectacles
for all waking hours.
• Ideal for sportsmen and
women, swimmers or
those who work in dusty
or dirty environments,
To have a lens free day.!!!
6. Why Have Ortho-K?
• People with allergies
• Dusty Environments
• Firemen
• Farmers
• Builders
• Cold Room
Employees.
7. Why Have Ortho-K ?
• The freedom from any
optical correction
appeals to many other
myopic spectacle and
contact lens wearers.
• School age children
benefit greatly:-No more
lost contact lenses or
broken frames.
8. Why Have Ortho-K Cont’d ?
• Contact lens
wearers that have
developed dry eyes,
discomfort or
sensitivity to their
lenses.
• Surgery is not in
your comfort zone.
9. Can Ortho-k Slow Myopia?
• In late 2004 a study
published in an
international journal
found that
Orthokeratology can
slow myopia
progression by an
average of 50%
10. Myopia Control
“The etiology of myopia has excited an immense amount
of speculation and controversy...and the theories which
have been put forward to explain its development are as
ingenious, fanciful and contradictory as have
accumulated around any subject in medicine.”
Sir Stewart Duke-Elder, 1970
11. Myopia Control
• Bifocal Lenses
Relaxing accommodation
• Rigid Contact Lenses
???
• Contact Lens Corneal
Reshaping (CRT)
Anterior aspheric optics
• Pharmacologic Intervention
Target specific anatomic
structures of the eye
14. Do Bifocal Spectacle Lenses
Decrease Myopia in Children ???
More Consistent, Full Time, Correction
All previous studies plagued with
patient non-compliance
17. Does this premise hold true?
• STUDY:
• Journal of Paediatric Ophthalmology and
Strabismus 1993.
18. The Influence of Study Habits on
Myopia in Jewish Teenagers
Journal of Pediatric Ophthalmology and Strabismus
September / October Vol 30 . No. 5 1993
870 multicultural Jewish teenagers
attending school in Jerusalem.
Females in General Schools
Females in Orthodox
Schools
Males in General School
Males in Orthodox
19. Orthodox Males
• Sustained near vision
(16 hours a day)
• Frequent changes in
accommodation
(due to habitual head rocking)
• Need for accurate
accommodation
(when reading tiny print, 1.0 mm
height)
20. Myopia in Orthodox Males is
worse than the general population.
Females in General Schools
Females in Orthodox Schools
Males in General School
Orthodox Males
23. Is there a link between Close
Work and Myopia?
•Yes.
24. Does Under-correction Slow the
Progression of Myopia?
• STUDY
• Chung, et al. Vision Research 2002
(2 year follow-up)
25. Undercorrection of Myopia Enhances ,
Rather than Inhibits Myopia Progression
• Chung, et al. Vision Research 2002
(2 year follow-up)
• Under-corrected to 20/40 (~+0.75 D)
• The undercorrected group showed INCREASED myopia
and axial length compared to the fully corrected group.
26. Do Rigid Contact Lens
Assist in Myopia Control
Katz (2003)
Am J Ophthalmology
Walline (2004)
Arch of Ophthalmology
Alignment Fitting Lenses
27. Rigid Contact Lens
and Myopia Control
Katz, Schein (2003)
2 Year Results
American Journal of Ophthalmology
Subjects wearing
CL Group:- 0.07 D. decrease in myopia progression
CL Group:- 0.05 mm increase in axial length
28. A Randomized Trial of the Effects of
Rigid Contact Lenses on
Myopia Progression
31. Change in Axial Length
RGP = 0.81 mm SCL = 0.76 mm Difference = 0.05 mm
32. Change in Axial Eye Growth
Two Year Data
0.84
0.79
0.6 0.59
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Katz Study Walline Study
RGP
Group
Controls RGP
Group
Controls
N = 97 N = 184 N = 59 N = 57
33. What Can Be Said ???
Over a three year period:
• The alignment fitting RGP lens group
increased in myopia -1.56 D. the SCL
group -2.19 D.
• This difference in myopia was related to
change in the corneal curvature induced
by the two different modalities.
• There were no differences in the axial
growth of the eyes between the two
groups.
• GP lenses DO NOT control myopia
progression.
34. The Longitudinal Orthokeratology
Research In Children (LORIC) study in
Hong Kong
A pilot study on refractive changes and myopic
control in 35 children 7-12
Pauline Cho, PhD, Associate Professor
Sin Wan Cheung, MPhil, Research Associate
Marion Edwards, PhD
Department of Optometry & Radiography
The Hong Kong Polytechnic University
36. Change in Axial Eye Growth
Two Year Data
0.6 0.59
0.54
0.29
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Walline Study Cho Study
RGP
Group
SCL
Group
Control
Group
Corneal
Re-
Shaping
Group
37. Jeffrey J. Walline, OD PhD
AOCLE Conference Montreal Canada, June 2006
Crayon Study
Inclusion Criteria
• Ages 9 to 12 years
• Sphere -0.75 D to -4.00 D
• Cylinder less than -1.00 D
• 20/20 OU
• No previous RGP wear
Contact Lenses
• Orthokeratology / Paragon CRT
• CIBA Vision Focus 2 Week (SCL)
38. Walline One Year Results
Vitreous Chamber Depth
0.27
0.14
0
0.05
0.1
0.15
0.2
0.25
0.3
SCL Control CRT
39. Conclusions
• 3 out of 4 children can wear Paragon CRT lens
for corneal reshaping.
• Confirms study by Cho, et al. that:
Corneal reshaping contact lenses
slow axial growth of the eye.
41. Does the Fovea Control the Axial
Growth of the Eye ???
Earl Smith et.al. University of Houston
42. What Does This Mean ???
These data demonstrate
that the fovea DOES NOT
play the dominate role in
refractive development.
Instead peripheral retinal
image plays the MAJOR
role in determining
overall eye growth.
44. The “Image Shell” Post OK
Negative Curvature of Field
The post OK
cornea generates a
negative curvature
of field. Central
rays of light are
focused on the
fovea. Peripheral
rays of light are
focused more
anteriorly (in front)
of the retina.
45. Pharmacological Intervention
Medications that target specific anatomic
structures of the eye.
1. Retinal neurotransmitters
linked to eye growth.
2. Scleral remodeling
enzymes and growth
factors.
3. Intraocular pressure
46. Atropine Therapy
• Long history for myopia control dating back to
the late 1960’s.
• Is a non-selective anti-muscarinic drug.
• Underlying assumption;
– Excessive accommodation implicated.
47. Chau ATOM Study ARVO 2003
400 subjects 331 at 2 years
Ages 6 – 12 with Myopia -1.00 to -6.00 D.
Atropine 1% once a day for two years
No
Growth
Control
48. Side Effects of Atropine 1%
Cycloplegia and photophobia
Decreased performance at near
Ultraviolet absorption
Possible macular damage
Papillary & Follicular conjunctivitis
Ocular and Systemic toxicity
Respiratory infection
Fever
49. Pirenzepine Ophthalmic 2% Gel
• Novartis Ophthalims,
Basel Switzerland
• Valley Forge
Pharmaceuticals, Irvine
CA
• Currently the product has
been discontinued from
clinical trials.
50. Pirenzepine Gel
Siatkowski, et al. IOVS (2002)
174 Subjects Ages 8 - 12
Pirenzepine 2% BID
Placebo BID
Refractive Change
PIR BID -0.26 D
Placebo -0.53 D
Axial Length Change
PIR BID 0.21 mm
Placebo 0.33 mm
Change
0.27 D 0.12 mm
51. Pirenzepine
Siatkowski, et al. IOVS (2002)
– 0% of placebo subjects dropped due to adverse
events
– 11% of PIR subjects dropped due to adverse events
• Gel residue on lids
• Blurred vision at near
• Asymptomatic conjunctival reactions
52. Pirenzepine Gel
Tan et.al. ARVO 2003
353 Subjects Ages 6 - 12
Pirenzepine 2% BID
Placebo BID
Refractive Change
PIR BID -0.47 D
Placebo -0.84 D
Axial Length Change
PIR BID 0.21 mm
Placebo 0.33 mm
Change
0.37 D 0.12 mm
53. Pirenzepine Complications
Tan et.al. ARVO 2003
• Abnormalities of accommodation
• Papillae and follicles
• Systemic complications
– Cough
– Respiratory infection
– Fever
– Rhinitis
– Abdominal pain
54. Myopia Control
Bifocal Lenses
Relaxing accommodation
Rigid Contact Lenses
? Improving retinal imagery
Myopia under-correction
-0.75 D
Optical Interventions
Curvature of field modification
Pharmacologic Intervention
Oral delivery, target specific
anatomic structures i.e. sclera
55. Earl Smith 2005
Eye growth may possibly be retarded, or
halted through:
“A precise and pre-determined optical system at the
corneal plane that will manipulate the peripheral optics
of the eye.”
56. Summary
Ideally the Myopia Controlling device should maintain
axial alignment “centered” with the eye regardless of
the position of gaze i.e.
The ideal system would be one that that could be
easily changed as the ocular power and peripheral
aberration profiles change.
Contact lenses
Orthokeratology
Refractive surgery
Intraocular lens
Corneal implants
57. Night Therapy!!
• For most people it is
possible to go straight
to night therapy. This
gives a fast and easy
way of arriving at
myopia correction.
Lenses are inserted
before going to sleep
and removed in the
morning.
58. Therapy Progression
• As the therapy
progresses and the
cornea is moulded, the
lenses give good
unaided vision for
longer periods of time.
Gradually the lens
wearing time may be
decreased to a level,
which gives the desired
reduction in myopia.
59. Teenagers.
• Possibly the ideal
situation for using
Ortho-K is for the
teenager just becoming
Myopic.
• Not only does it have all
the advantages already
discussed, but the
procedure appears to
stabilise or retard the
progression of the
Myopia.
60. Every Night?
• Lenses will still need
to be worn at night,
but the frequency of
wearing time varies
between individuals.
61. Advantages Over Surgery.
• Ortho-K costs less
and is a reversible
procedure.
• It is also more
appropriate for
people whose eyes
are still changing
62. IS EVERYONE SUITABLE
FOR Ortho-K?
The procedure works best up
to -4.00 dioptres of
Myopia and -1.0 dioptres
of Astigmatism.
New designs are expected to
come available for
prescriptions up to -6.00D
and for hyperopes up to
+3.00D
63. IS EVERYONE SUITABLE
FOR Ortho-K?
• The procedure also does
not work as effectively on
very steep or very flat
corneas.
• In addition there are
several unknown factors
for each individual; The
complexity of the corneal
shape and the rigidity of
the cornea itself.
64. Contra-indications:
• Extreme dry eye
(unable to tolerate
regular contact lenses)
• Patients that have had
laser or LASIK surgery
• Any active or recurrent
ocular surface disease
• Keratoconus
65. Lost Lenses: Ceasing Wear
• In the event of a lost
lens the cornea will
tend to return to its
original shape.
• A spare pair of
lenses is provided in
the schedule, and a
new lens takes 3
working days.
Lost City of Petra.
66. Aftercare.
• As with any contact
lens wear it is vital to
ensure the health
and integrity of the
cornea at all stages.
Over the first year
many visits are
involved.
67. Aftercare Continued.
• After the initial
therapy an
examination twice a
year is considered
essential to ensure
ongoing safety of
the eyes and good
vision
69. History.
• The initial flurry into
Orthokeratology was
hindered by poor
technology and
understanding of the
criteria needed to
successfully and
predictably correct
myopia.
73. OOK.
• High tech laboratory
equipment.
• High oxygen
transmissible
materials.
74. Improved Reverse Geometry
• Changes to contact
lens designs
achieved with high
tech precision laser
guided lathes
75. WHAT ARE THE
DISADVANTAGES OF
ORTHO-K?
• You must be prepared to
allow for 4-10 visits over 3-6
months.
• Retainer lens wear is
essential or the cornea will
revert to its original shape.
• The degree of success is high
but cannot always be
guaranteed.
76. Disadvantages Cont’d..
• The rate of improvement
varies from one person to the
next.You must be prepared
to follow instructions
implicitly for the best results.
• Reaching the optimal vision
result can take up to 3
months.
• Vision will fluctuate over the
first 10 to 14 days.
77. Does ORTHO-K Have Any
Advantages Over EXCIMER
Laser Surgery?
• Yes!
• The procedure is REVERSIBLE (Excimer is not!).
• It does not involve post-operative pain.
• It does not leave the hazy vision often experienced by
patients following laser surgery.
• There is no loss of Bowman's membrane (the tough
protective layer just under the Corneal surface).
78. Does ORTHO-K Have Any
Advantages Over EXCIMER
Laser Surgery?
• Yes!!
• Changes in prescription over time can
be dealt with (unlike Excimer).
• Ortho-K is significantly cheaper.
• No age limit. (not recommended under
age 8 years.)
• Both eyes are done together (rather
than several weeks or months apart).
79. Fees and Charges.
• The technique involves the
provision of specialist
Orthokeratology contact
lenses and a number of
visits to your practitioner.
• Each practitioner sets their
own fees which may vary
dependant on the Rx being
treated.
.
80. Fees and Charges:-Rebates.
• Like laser surgery
there is no rebate
available from
health funds on this
technique, however,
some funds do
cover part of the
cost of the contact
lenses.
81. Cost.
• The procedure is time
consuming and can
involve several Lens
changes.
• However, once
complete, the on-going
costs are no greater
and often less than
conventional Contact
Lens wear.
88. Total 5 Year Cost Analysis.
$0.00
$1,000.00
$2,000.00
$3,000.00
$4,000.00
$5,000.00
$6,000.00
Ortho-K 2 Weekly
Disposable
30 day C/W Monthly
Disposable
Daily
Disposable
Lens Type
Fees Lenses Care Products
89. 5 Year Cost with Glasses.
$0.00
$1,000.00
$2,000.00
$3,000.00
$4,000.00
$5,000.00
$6,000.00
$7,000.00
Ortho-K 2 Weekly
Disposable
30 day C/W Monthly
Disposable
Daily
Disposable
Fees Lenses
Care Products Glasses
Rx Sunglasses
90. Adapting to Refractive Change.
• Another benefit of OOK
is that its effects can be
adjusted or modified .
• As a patient’s myopia
increases, we design a
new lens to move more
epithelial cells, creating
more focusing power.
91. Presbyopia:-Aging Eye.
• When a patient reaches their 40’s,
the ability to focus on near objects
is reduced which is called
presbyopia.
• OOK can be adjusted on one or both
of the eyes to provide good distance
vision but at the same time, improve
a patients’ ability to focus on nearby
objects as well (called monovision).
92. Orthokeratology Is a Safe and
Effective Vision Correction
Procedure That Requires No
Surgery.
If You Are Unsatisfied With the
Results It Is a Completely
Reversible Procedure.
All You Have to Do Is Take Out
the Retainer Lenses and No
Longer Wear Them.
Summary.
93. Be Free to See Exceptionally,
Without Any Aid!!!
• Each night before going
to bed, you will insert
you OOK retainer.
• It has been designed so
that you can see to read
before sleeping or
provide you with
adequate vision should
you wake up in the
middle of the night for
any reason.
•
95. Be Free to See Exceptionally,
Without Any Aid!!!
–As soon as you wake in the
morning, you will employ the
proper removal, handling, and
cleaning techniques and place
your retainers in their case.
•And the best part....You see
exceptionally, without any aid!!!
