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Student’s name : Anis Suzanna Binti MohamadMatrix number : A123369Lecturer’s name : Prof. Dr. Norhani
Mohidin
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.
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.
• 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.
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 analysisa. 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
Patient’s profile: F/14/CFile. No: 5596Visit 1: PCCDate: 7/1/2011History 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 LEVision aided Distant Near Distant Near
6/6With +1.00: 6/18
N5@40cm 6/9+3
With pinhole: 6/6N5@40cm
Current Rx -3.50/-0.25x180 -3.00/-0.50x180Slit lamp Dusty eyelashes
PapillaeTBUT: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
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.
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 eyeOrdered lens VIPOK 2N05 VIPOK 2003Lens inspection Ok OkOver-refraction and VA
Plano, 6/5 Plano, 6/5
Remarks Deliver Deliver
Right eye Left eyeVA with CL Not done Not doneFitting assessment Not done Not doneOver-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 eyelashesSlit lamp findings Cornea: clear
PapillaeCornea: SPKPapillae
Corneal topography
Apical radius 7.724mm 7.833mm
Keratometry [email protected] [email protected]
Corneal astig:-1.81x133.2
[email protected] [email protected]
Corneal astig:-1.99x99.6Remarks To come again one week after wearing CL.
Aftercare 2 weeks later: 7/3/2011Symptom:•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, 6/6VA without CL: 6/24
-1.50/-0.50x140, 6/6VA without CL: 6/24
VA without CL on both eyes: 6/18
Corneal topography
Apical radius 8.101mm 7.839mmLens 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
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 eyeVA 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, 6/6VA without CL: 6/6-3
-0.25Ds, 6/6VA without CL: 6/6
VA without CL on both eyes: None
Corneal topography
Keratometry [email protected] [email protected]
Corneal astig:-2.57x123.6
[email protected] [email protected]
Corneal astig:-2.60x99.6Apical radius 8.013mm 7.833mmLens inspection
Not done Not done
Slit lamp findings
Remarks To continue with contact lens wear. To come again 15/4/2011 for review.
• 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
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.
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
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+3Vision 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.
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
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.
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.
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.
Millodot, M. 2000. Dictionary of Optometry and Visual Science. Oxford: Butterworth-
Heinemann Ltd.M. Petterburg & B. Bowling. 1999. Ophthalmology: An Illustrated Colour Text. First Edition. Pg;62-63. Churchill Livingstone.David B. Elliot. 2000. Clinical Procedures in Primary Eye Care. Third Edition. Pg; 40. Elsevier: Butterworth-Heinemann Ltd.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=12133Swarbrick HA, Wong G, O’Leary DJ. Corneal response to orthokeratology. Optom
Vis Sci. 1998;75:791–799.Soni PS, Nguyen TT, Bonanno JA. Overnight orthokeratology: refractive and
corneal recovery after discontinuation of reversegeometry lenses. Eye Contact Lens. 2004;30:254–262.
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