Ortho K Contact Lenses

1. Student’s name : Anis Suzanna Binti
Mohamad
Matrix number : A123369
Lecturer’s name : Prof. Dr. Norhani
Mohidin

2.  Orthokeratology (OK) is a clinical technique that
uses specially designed rigid contact lenses to
reshape the cornea to temporarily reduce or
eliminate refractive error (H.A Swarbick., 2006).
 Also known as corneal shaping lenses, corneal
refractive therapy or CRT and vision shaping
treatment or VST
 Mode of wear:
 Night therapy - during sleep for about 8 hours.
 Day therapy - half day of waking hours.

4. 1. Base curve- flatter than
the flattest central
apical radius.
2. Reverse curve- steeper
secondary curve forms a
tear reservoir for excess
tear.
3. Alignment curve-
allows the shaping lens
to centre and position
properly on the eye.
4. Peripheral curve- allow
for tear circulation
under the shaper & easy
removal of debris
trapped.

6. • Age: juvenile to adult myopes
• Spherical refractive error:
-1.00 D to -5.00 D spherical power correction
• Cylindrical refractive error:
- 1.50 D or less “with-the-rule” corneal astigmatism
- 0.75 D or less “against-the-rule” astigmatism
• Recreational and sports activities where periods without wearing visual
correction are beneficial
• Those whose vocation requires unaided visual acuity for certain periods, such
as police, firemen, military, or occupations where refractive surgery may be a
cause for exclusion (deep-sea divers, high altitude pilots, etc.)
• Free of corneal dystrophies (e.g. keratoconus), ocular diseases, or any
condition that may preclude the patient from wearing any type of GP lens
• Motivated to undergo full or partial myopia reduction and willing to return to
the office for two to three months of active treatment and every six months for
passive treatment
• Committed to the initial and ongoing cost of ortho-k treatment. Practitioners
should consult fitting information provided by specific design/fitting systems.

7. 2. Pre-fitting
assessment
3. Post-fitting assessment/
Follow up examination
• Refraction and VA
• Baseline topography
(keratometry
optional, but
topography is a must)
• Tear film analysis
a. Schirmer test
(quantitative)
b. Tear Break-Up Time
or TBUT (qualitative)
• Biomicroscopy-corneal
health/fitting pattern
 Refraction and VA with and
w/o CL
 Overefraction
 Corneal health
 Fitting pattern
 Topography
 Follow-up pattern:-
 24 hour after wearing the lens
 1 week after wearing the lens
 2 week after wearing the lens
 1 month
 3 month

8. Patient’s profile: F/14/C
File. No: 5596
Visit 1: PCC
Date: 7/1/2011
History taking:
•Chief complaint:-Come for ortho-K examination.
•Ocular history:-Patient start wearing contact lenses 8 years. Current Rx since last year.
•General health:-Allergic to dust. Others nil.
•Family history:-Bronchitis.
RE LE
Vision aided Distant Near Distant Near
6/6
With +1.00: 6/18
N5@40cm 6/9+3
With pinhole: 6/6
N5@40cm
Current Rx -3.50/-0.25x180 -3.00/-0.50x180
Slit lamp Dusty eyelashes
Papillae
TBUT:7 secs
Dusty eyelashes
Papillae
TBUT:7 secs
Subjective
refraction&VA
-3.50/-0.50x10 (6/6) -2.75/-1.00x10 (6/6)
Keratometry 7.9/42.8@180
7.55/44.6@90
Lens to fit: 2P05
7.9/42.8@180
7.50/45.0@90
Lens to fit: 2Q03@ 2P02

9. Corneal topography
Axial length 24.55mm 24.25mm
Apical radius 7.718mm 7.648mm
Diagnosis
• Papillae with dusty eyelashes.
Management plan
• Suggest to use lid care for eyelashes hygiene
• Suggest do warm compression.
• To come again for ortho-K fitting. KIV to see papillae and eyelashes.

10. Assessment of ortho-K fitting was done: delivery lens on 18.02.2011
24 hours after overnight wear assessment: 21.02.11
Right eye Left eye
Ordered lens VIPOK 2N05 VIPOK 2003
Lens inspection Ok Ok
Over-refraction and
VA
Plano, 6/5 Plano, 6/5
Remarks Deliver Deliver
Right eye Left eye
VA with CL Not done Not done
Fitting assessment Not done Not done
Over-refraction and VA
without CL
-2.50/-0.25x180, 6/6-
VA without CL: 6/36-1
-2.25/-0.25x180, 6/6-
VA without CL: 6/36
Lens inspection Small deposits Lens has eyelashes
Slit lamp findings Cornea: clear
Papillae
Cornea: SPK
Papillae

11. Corneal topography
Apical radius 7.724mm 7.833mm
Keratometry 44.09@43.2
45.90@133.2
Corneal astig:-1.81x133.2
42.93@9.6
44.92@99.6
Corneal astig:-1.99x99.6
Remarks • To come again one week after wearing CL.

12. Aftercare 2 weeks later: 7/3/2011
Symptom:
•Vision is still not improved. Patient complaint of seeing haloes or double
vision at all time.
•Patient wore contact lenses 8 hours every night since 2 weeks ago.
Right eye Left eye
VA with CL 6/6 6/6
Fitting assessment Too much pooling Too much pooling
Over-refraction and VA
without CL
-1.75/-0.25x140, 6/6
VA without CL: 6/24
-1.50/-0.50x140, 6/6
VA without CL: 6/24
VA without CL on both eyes: 6/18

13. Corneal
topography
Apical radius 8.101mm 7.839mm
Lens inspection Not done Not done
Slit lamp findings NAD NAD
Remarks • To fit with flatter lens on both eyes.
• Lens to fit:
RE: 2M05 LE: 2N03

14. Assessment of ortho-K fitting was done: delivery lens on 7.3.2011
Symptom:
•Get double vision after takeoff CL occasionally.
•Patient wore contact lenses 11 p.m. to 7 p.m. every night since 2 weeks ago.
Aftercare 2 weeks after new ortho-K wearing on 18.3.2011
Right eye Left eye
VA with CL 6/9+1
6/6+
Fitting assessment
x = 0, y = 0 x = -1, y = 0
Over-refraction and VA
without CL
-0.50Ds, 6/6
VA without CL: 6/6-3
-0.25Ds, 6/6
VA without CL: 6/6
VA without CL on both eyes: None

15. Corneal
topography
Keratometry 41.99@33.96
44.56@123.6
Corneal astig:-2.57x123.6
43.02@96.9
45.62@99.6
Corneal astig:-2.60x99.6
Apical radius 8.013mm 7.833mm
Lens inspection Not done Not done
Slit lamp findings
Remarks • To continue with contact lens wear.
• To come again 15/4/2011 for review.

16. • Patient start wearing ortho-k lenses since 18.02.11:
• Fitting acceptable, lens can deliver.
• First aftercare after 24 hours wearing on 21.2.11:
• still a residue of the steep cornea
• changes of corneal curvature and refractive error still continue over
first few days
• reach stable usually after 7-10 night.
• Aftercare after 2weeks on 7.3.11:
• The fitting at first was unsuccessful/unable to obtain bull eye pattern.
• Change to flatter lenses.
• Aftercare after 2 weeks on 18.3.11:
• improvement in topographic pattern were shown and been follow up
monthly

17.  There are three possible outcomes from wearing
ortho-K lenses:-
 The centred treatment pattern (Bull’s eye).
 A well-centred area of flattening.
 A circle of mid-peripheral corneal steepening.
 Little/no perpheral corneal change.
 Decentered treatment pattern.
 ‘Smiley Face Pattern- lens superior and too flat.
 ‘Frowny Face Pattern- alignment curve too steep or tight.
 Lateral decentration- lens diameter too small or cornea
flattens much faster on nasal compare to temporal.
 Central island pattern.
 Due to overestimating the corneal sagittal height or
underestimating the eccentricity.
Therefore, corneal topography is useful in orthokeratology.

18. Pre-fitting analysis Post-fitting analysis
• Screening for pathologic
corneas
• Establishing the
baseline corneal shape
• Predicting the outcome
based on the pre-fitting
apical radius and
corneal eccentricity.
• Accurate shape analysis
to assist in selecting
optimum lens
parameters
• Identifying and
documenting induced
corneal changes
• Assisting with
problem solving and
lens design
refinements
• Patient education

19. 7/1/2011
(PCC)
21/2/2011
(A/care 24hrs)
7/3/2011
(A/care 2wks)
18/3/2011
(A/care 2wks)
Vision aided 6/6 6/6- 6/6 6/9+3
Vision unaided Not done 6/36- 6/24 6/6-3
Corneal
topographic
Apical radius 7.718 7.724 8.101 8.013
• Remember that the position of the contact lens in the open-eye environment is not necessarily
representative of where the lens positions in the closed eye. Therefore, corneal mapping
provides the only reliable means of knowing precisely where the lens positioned during sleep.

20. 7/1/2011
(PCC)
21/2/2011
(A/care 24hrs)
7/3/2011
(A/care 2wks)
18/3/2011
(A/care 2wks)
Vision aided 6/9+3 6/6- 6/6 6/6+
Vision unaided Not done 6/36 6/24 6/6
Corneal
topographic
Apical radius 7.648 7.833 7.839 7.833
•Good fit: treatment zone composes the pupil diameter
•The size of central treatment zone will influence the subjective visual
outcome

21.  Vision unaided after removal of the ortho-K lens is
satisfied on both eyes.
 The fitting is determine the vision and corneal
mapping after the lens removal.
 According to the last visit, for the right eye, the
corneal topographic showed that the centered
treatment pattern.
 However, for the left eye, there are some residual
steepening of corneal topographic. It looks like
‘smile face pattern’.
 The management is quite confusing. Smile face
pattern or decentered pattern showed the lens is
decentered superiorly or lens too flat. However, the
examiner just advice patient to continue wear the
glasses.

22.  Incomplete record
 Do not do the crucial test such as pachymetry and
Schimer’s test during pre-fitting orthokeratology.
 Not change the date of recording for corneal topography
 Use different form for recording.
 Lack of optometric management
 Discover lens deposits- no management given.
 Mistakes can end up patient with corneal staining.
 Patient poor compliance
 Patient poor in lens handling and lens care.
 It cause the lack of information in monitoring the
orthokeratology treatment.

23.  In a nutshell, orthokeratology is a lens that
wears for reshape the corneal surface to form
the correct shape for clear focusing onto both
the peripheral and the central retina.
 In fitting ortho-k lenses a baseline of cornea
shape is a must.
 However, the handling of the lens are the same
as normal RGP contact lens care.
 The end result is unpredictable. The proper
management is a little bit tricky and really need
patient high motivation and compliance.

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J. Kanski & B. Bowling. 2005. Ophthalmology In Focus. Second Edition.
Pg; 45. Elsevier: Churchill Livingstone.
Nathan Efron. 2004. Contact lens complications. Second Edition.
Pg; 175-185. Elsevier: Butterworh-Heinemenn.
John Mountford, Patrick J. Caroline, and Don Noack; Corneal Topography and
Orthokeratology: Pre-fitting
Evaluation;http://www.clspectrum.com/pf_article.asp?article=12133
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1998;75:791–799.
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