Building your OrthoK practice using GOV lenses

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1

Building your Ortho-K practice using GOV lenses

Arthur Tung

Charl Laäs

Chris Eksteen

Hal Ostrom

Thought of the Day

“Vision is not enough,

it must be combined with venture.

It is not enough to stare up the steps,

we must step up the stairs.”

~ Václav Havel

Fitting OrthokeratologyLenses

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Who to fit - Starting

• Hyperopia– <+2.00

• Myopia – <-4.00D

• Astigmatism– <-0.75D

• E value:– 0.35 – 0.55

• Normal healthy cornea

Who to fit – With confidence

• Hyperopia – <+5.00

• Hyperopia Presbyopia– <+4.00, Add<+2.50

• Myopia– <-6.00D

• Astigmatism – -1.25D

• E value– 0.30 – 0.60

• Normal healthy cornea

Who to fit – Master Fitter

• Hyperopia– <5.00

• Hyperopia Presbyopia:– <+4.00, Add<+2.50

• Myopia– <-10.00D

• Astigmatism – <-2.25D

• Post Lasik

• Keratoconus

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Astigmatism

• Cyl must always be less than half of sphere

• With the rule <-1.50

• Against the rule < -0.75

Empirical VS Systemized Systems

Empirical Fitting Systems

• Manual Calculate– Formula

• BC– Mean K (D) – SE (D) – 1.25D (Compression Factor)– Diameter: 6.00mm

• RC– 2D to 6 D steeper than central curve– 0.6mm to 1.2mm wide

• AC– 0.75D flatter than Mean K

• Propriety Software– Topographer based (Medmont, Wave, etc.)– Stand Alone - OrthoTool

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Empirical Fitting Systems

• Corneal information or design is given to lab

• Lab designs and manufacture lens

• Lens works

• Or it doesn’t!

Systemized Fitting Systems

• GOV – Global Orthokeratology Vision

• CRT – Corneal Refractive Therapy

• Vision Shaping Treatment (VST) Program– “BE Retainer" backed by BE Enterprises – "CKR" backed by Eye Care Associates– "Contex OK-E System" backed by Contex .– "DreamLens" backed by Dreimlens– "Emerald" designed and manufactured by Euclid – "NightMove" backed by Advanced Corneal Engineering


• Pre designed lenses

• Fitted from a fitting chart

• Use Trial lenses to verify theoretical calculations

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Mean K/ S.E -1.50 -2.00 -2.50 -3.00 -3.50 -4.00 -4.50 -5.00 OAD 11.2 mm Best fit cornea 11.3~11.9 mm

A 39.87~40.11 (40.00) 40.00/-1.5 40.00/-2.0 40.00/-2.5 40.00/-3.0 40.00/-3.5 40.00/-4.0 40.00/-4.5 40.00/-5.0B 40.12~40.36 (40.25) 40.25/-1.5 40.25/-2.0 40.25/-2.5 40.25/-3.0 40.25/-3.5 40.25/-4.0 40.25/-4.5 40.25/-5.0C 40.37~40.66 (40.50) 40.50/-1.5 40.50/-2.0 40.50/-2.5 40.50/-3.0 40.50/-3.5 40.50/-4.0 40.50/-4.5 40.50/-5.0D 40.67~40.86 (40.75) 40.75/-1.5 40.75/-2.0 40.75/-2.5 40.75/-3.0 40.75/-3.5 40.75/-4.0 40.75/-4.5 40.75/-5.0E 40.87~41.11 (41.00) 41.00/-1.5 41.00/-2.0 41.00/-2.5 41.00/-3.0 41.00/-3.5 41.00/-4.0 41.00/-4.5 41.00/-5.0F 41.12~41.36 (41.25) 41.25/-1.5 41.25/-2.0 41.25/-2.5 41.25/-3.0 41.25/-3.5 41.25/-4.0 41.25/-4.5 41.25/-5.0G 41.37~41.66 (41.50) 41.50/-1.5 41.50/-2.0 41.50/-2.5 41.50/-3.0 41.50/-3.5 41.50/-4.0 41.50/-4.5 41.50/-5.0H 41.67~41.86 (41.75) 41.75/-1.5 41.75/-2.0 41.75/-2.5 41.75/-3.0 41.75/-3.5 41.75/-4.0 41.75/-4.5 41.75/-5.0I 41.87~42.11 (42.00) 42.00/-1.5 42.00/-2.0 42.00/-2.5 42.00/-3.0 42.00/-3.5 42.00/-4.0 42.00/-4.5 42.00/-5.0J 42.12~42.36 (42.25) 42.25/-1.5 42.25/-2.0 42.25/-2.5 42.25/-3.0 42.25/-3.5 42.25/-4.0 42.25/-4.5 42.25/-5.0

OAD 10.8 mm Best fit cornea: 11.2~11.6 mm

K 42.37~42.66 (42.50) 42.50/-1.5 42.50/-2.0 42.50/-2.5 42.50/-3.0 42.50/-3.5 42.50/-4.0 42.50/-4.5 42.50/-5.0L 42.67~42.86 (42.75) 42.75/-1.5 42.75/-2.0 42.75/-2.5 42.75/-3.0 42.75/-3.5 42.75/-4.0 42.75/-4.5 42.75/-5.0M 42.87~43.11 (43.00) 43.00/-1.5 43.00/-2.0 43.00/-2.5 43.00/-3.0 43.00/-3.5 43.00/-4.0 43.00/-4.5 43.00/-5.0N 43.12~43.36 (43.25) 43.25/-1.5 43.25/-2.0 43.25/-2.5 43.25/-3.0 43.25/-3.5 43.25/-4.0 43.25/-4.5 43.25/-5.0O 43.37~43.66 (43.50) 43.50/-1.5 43.50/-2.0 43.50/-2.5 43.50/-3.0 43.50/-3.5 43.50/-4.0 43.50/-4.5 43.50/-5.0P 43.67~43.86 (43.75) 43.75/-1.5 43.75/-2.0 43.75/-2.5 43.75/-3.0 43.75/-3.5 43.75/-4.0 43.75/-4.5 43.75/-5.0

OAD 10.4 mm Best fit cornea: 10.8~11.4 mm

Q 43.87~44.11 (44.00) 44.00/-1.5 44.00/-2.0 44.00/-2.5 44.00/-3.0 44.00/-3.5 44.00/-4.0 44.00/-4.5 44.00/-5.0R 44.12~44.36 (44.25) 44.25/-1.5 44.25/-2.0 44.25/-2.5 44.25/-3.0 44.25/-3.5 44.25/-4.0 44.25/-4.5 44.25/-5.0S 44.37~44.66 (44.50) 44.50/-1.5 44.50/-2.0 44.50/-2.5 44.50/-3.0 44.50/-3.5 44.50/-4.0 44.50/-4.5 44.50/-5.0T 44.67~44.86 (44.75) 44.75/-1.5 44.75/-2.0 44.75/-2.5 44.75/-3.0 44.75/-3.5 44.75/-4.0 44.75/-4.5 44.75/-5.0U 44.87~45.11 (45.00) 45.00/-1.5 45.00/-2.0 45.00/-2.5 45.00/-3.0 45.00/-3.5 45.00/-4.0 45.00/-4.5 45.00/-5.0V 45.12~45.36 (45.25) 45.25/-1.5 45.25/-2.0 45.25/-2.5 45.25/-3.0 45.25/-3.5 45.25/-4.0 45.25/-4.5 45.25/-5.0W 45.37~45.66 (45.50) 45.50/-1.5 45.50/-2.0 45.50/-2.5 45.50/-3.0 45.50/-3.5 45.50/-4.0 45.50/-4.5 45.50/-5.0X 45.67~45.86 (45.75) 45.75/-1.5 45.75/-2.0 45.75/-2.5 45.75/-3.0 45.75/-3.5 45.75/-4.0 45.75/-4.5 45.75/-5.0Y 45.87~46.11 (46.00) 46.00/-1.5 46.00/-2.0 46.00/-2.5 46.00/-3.0 46.00/-3.5 46.00/-4.0 46.00/-4.5 46.00/-5.0Z 46.12~46.36 (46.25) 46.25/-1.5 46.25/-2.0 46.25/-2.5 46.25/-3.0 46.25/-3.5 46.25/-4.0 46.25/-4.5 46.25/-5.0

ZA 46.37~46.66 (46.50) 46.50/-1.5 46.50/-2.0 46.50/-2.5 46.50/-3.0 46.50/-3.5 46.50/-4.0 46.50/-4.5 46.50/-5.0ZB 46.67~46.86 (46.75) 46.75/-1.5 46.75/-2.0 46.75/-2.5 46.75/-3.0 46.75/-3.5 46.75/-4.0 46.75/-4.5 46.75/-5.0ZC 46.87~47.11 (47.00) 47.00/-1.5 47.00/-2.0 47.00/-2.5 47.00/-3.0 47.00/-3.5 47.00/-4.0 47.00/-4.5 47.00/-5.0ZD 47.12~47.36 (47.25) 47.25/-1.5 47.25/-2.0 47.25/-2.5 47.25/-3.0 47.25/-3.5 47.25/-4.0 47.25/-4.5 47.25/-5.0ZE 47.37~47.66 (47.50) 47.50/-1.5 47.50/-2.0 47.50/-2.5 47.50/-3.0 47.50/-3.5 47.50/-4.0 47.50/-4.5 47.50/-5.0

Reference Table


General fitting process:• Initial lens is chosen from chart

• Fit with diagnostic trial lenses and evaluate NaFlpattern – Look for Bull’s eye pattern

• Initial lens – should not be too flat and tight at the alignment curve zone

– should move 1 – 2mm on blink

• Evaluate after 30 min using the topographer

• Does the Px show a central flattening/steeping effect ?

The GOV System

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The GOV® System

• Advanced inventory system• Multi-curve Aspheric Conformed Reverse Geometry

Lenses (MAC-RGL)• Practitioner in control of the lens fit – not laboratories• Simplified method for myopic & hyperopic correction• Correct from +5.00D to -10.00D

GOALA simple fitting method to start Orthokeratology which allows for growth into fitting higher and unusual powers with the confidence that there is an active support group.

Reverse Geometry Design

• Alignment Zone

GOV® Global patents

Patents Referencetable (PA1)

High myopia(PA2)

Hyperopia &Presbyopia

(PA3)KC & PL (PA4)

Hyperopia &Presbyopia

(PA3C)

KC & PL triallens &

system(PA4C)

Soft OK(PA7)

USA # 6,361,169 # 6,543,897 # 6,652,095 # 6,997,553 # 7,070,275 # 7,360,892 Pending

Europe EP1527369B1

China ZL01818951.2 ZL200580024766.2 ZL03818340.4

Australia #2005279761 # 2003258115

Canada (Pending) # 2,492,132

Korea

Japan (Pending) granted

India (Pending) #236549

Taiwan

(Pending)

(Pending) (Pending)

(Pending)

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GOV™ –Global Orthokeratology Vision

• XMJ – Conformed <-5.00D• XM – Conformed >-5.00 <-10.00+D• H – Hyperopia• HP – Hyperopic Presbyopia• MP – Myopic Presbyopia• PL - Post Lasik • Kc - Keratoconus • Support Websites

• www.OrthokInstitute.com

Benifits

Simple effective system

• Practitioner chooses the appropriate lens and make changes

• Immediate dispensing – (full trial set)

• Efficient and effective method to increase turnover

• Quickly develop a specialty Ortho-k practice

• Confidently fit with GOV support

Fitting GOV Lenses

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Fitting GOV® lensesAs easy as 1-2-3• Select K-code

• Determine Power-code

• Determine Lens sizes (OAD)

K-Code

Calculate K-code by Mean K• Mean-K=(Horizontal K + Vertical K) / 2

• TK and e values are unnecessary

• ‘e’-value has been calculated into lens

• Change in steps of 0.25D

• Choose the closest mean K for K-code using tables

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Prescribe Empirically

• Km: 42.87 x 44.75 @ 90Rx: - 3.50 - 1.50 x 180

• Determine K-code– Mean K=(42.87 + 44.75) / 2 = 43.81

Mean K/ S.E -1.50 -2.00 -2.50 -3.00 -3.50 -4.00 -4.50 -5.00 OAD 11.2 mm Best fit cornea 11.3~11.9 mm (OAD =95-97% of HVID)

A 39.87~40.11 (40.00) 40.00/-1.5 40.00/-2.0 40.00/-2.5 40.00/-3.0 40.00/-3.5 40.00/-4.0 40.00/-4.5 40.00/-5.0

B 40.12~40.36 (40.25) 40.25/-1.5 40.25/-2.0 40.25/-2.5 40.25/-3.0 40.25/-3.5 40.25/-4.0 40.25/-4.5 40.25/-5.0

C 40.37~40.66 (40.50) 40.50/-1.5 40.50/-2.0 40.50/-2.5 40.50/-3.0 40.50/-3.5 40.50/-4.0 40.50/-4.5 40.50/-5.0

D 40.67~40.86 (40.75) 40.75/-1.5 40.75/-2.0 40.75/-2.5 40.75/-3.0 40.75/-3.5 40.75/-4.0 40.75/-4.5 40.75/-5.0

E 40.87~41.11 (41.00) 41.00/-1.5 41.00/-2.0 41.00/-2.5 41.00/-3.0 41.00/-3.5 41.00/-4.0 41.00/-4.5 41.00/-5.0

F 41.12~41.36 (41.25) 41.25/-1.5 41.25/-2.0 41.25/-2.5 41.25/-3.0 41.25/-3.5 41.25/-4.0 41.25/-4.5 41.25/-5.0

G 41.37~41.66 (41.50) 41.50/-1.5 41.50/-2.0 41.50/-2.5 41.50/-3.0 41.50/-3.5 41.50/-4.0 41.50/-4.5 41.50/-5.0

H 41.67~41.86 (41.75) 41.75/-1.5 41.75/-2.0 41.75/-2.5 41.75/-3.0 41.75/-3.5 41.75/-4.0 41.75/-4.5 41.75/-5.0

I 41.87~42.11 (42.00) 42.00/-1.5 42.00/-2.0 42.00/-2.5 42.00/-3.0 42.00/-3.5 42.00/-4.0 42.00/-4.5 42.00/-5.0

J 42.12~42.36 (42.25) 42.25/-1.5 42.25/-2.0 42.25/-2.5 42.25/-3.0 42.25/-3.5 42.25/-4.0 42.25/-4.5 42.25/-5.0OAD 10.8 mm Best fit cornea: 11.2~11.6 mm (OAD =93-95% of HVID)

K 42.37~42.66 (42.50) 42.50/-1.5 42.50/-2.0 42.50/-2.5 42.50/-3.0 42.50/-3.5 42.50/-4.0 42.50/-4.5 42.50/-5.0

L 42.67~42.86 (42.75) 42.75/-1.5 42.75/-2.0 42.75/-2.5 42.75/-3.0 42.75/-3.5 42.75/-4.0 42.75/-4.5 42.75/-5.0

M 42.87~43.11 (43.00) 43.00/-1.5 43.00/-2.0 43.00/-2.5 43.00/-3.0 43.00/-3.5 43.00/-4.0 43.00/-4.5 43.00/-5.0

N 43.12~43.36 (43.25) 43.25/-1.5 43.25/-2.0 43.25/-2.5 43.25/-3.0 43.25/-3.5 43.25/-4.0 43.25/-4.5 43.25/-5.0

O 43.37~43.66 (43.50) 43.50/-1.5 43.50/-2.0 43.50/-2.5 43.50/-3.0 43.50/-3.5 43.50/-4.0 43.50/-4.5 43.50/-5.0

P 43.67~43.86 (43.75) 43.75/-1.5 43.75/-2.0 43.75/-2.5 43.75/-3.0 43.75/-3.5 43.75/-4.0 43.75/-4.5 43.75/-5.0OAD 10.4 mm Best fit cornea: 10.8~11.4 mm (OAD =92-94% of HVID)

Q 43.87~44.11 (44.00) 44.00/-1.5 44.00/-2.0 44.00/-2.5 44.00/-3.0 44.00/-3.5 44.00/-4.0 44.00/-4.5 44.00/-5.0

R 44.12~44.36 (44.25) 44.25/-1.5 44.25/-2.0 44.25/-2.5 44.25/-3.0 44.25/-3.5 44.25/-4.0 44.25/-4.5 44.25/-5.0

S 44.37~44.66 (44.50) 44.50/-1.5 44.50/-2.0 44.50/-2.5 44.50/-3.0 44.50/-3.5 44.50/-4.0 44.50/-4.5 44.50/-5.0

T 44.67~44.86 (44.75) 44.75/-1.5 44.75/-2.0 44.75/-2.5 44.75/-3.0 44.75/-3.5 44.75/-4.0 44.75/-4.5 44.75/-5.0

U 44.87~45.11 (45.00) 45.00/-1.5 45.00/-2.0 45.00/-2.5 45.00/-3.0 45.00/-3.5 45.00/-4.0 45.00/-4.5 45.00/-5.0

V 45.12~45.36 (45.25) 45.25/-1.5 45.25/-2.0 45.25/-2.5 45.25/-3.0 45.25/-3.5 45.25/-4.0 45.25/-4.5 45.25/-5.0

W 45.37~45.66 (45.50) 45.50/-1.5 45.50/-2.0 45.50/-2.5 45.50/-3.0 45.50/-3.5 45.50/-4.0 45.50/-4.5 45.50/-5.0

X 45.67~45.86 (45.75) 45.75/-1.5 45.75/-2.0 45.75/-2.5 45.75/-3.0 45.75/-3.5 45.75/-4.0 45.75/-4.5 45.75/-5.0

Y 45.87~46.11 (46.00) 46.00/-1.5 46.00/-2.0 46.00/-2.5 46.00/-3.0 46.00/-3.5 46.00/-4.0 46.00/-4.5 46.00/-5.0

Z 46.12~46.36 (46.25) 46.25/-1.5 46.25/-2.0 46.25/-2.5 46.25/-3.0 46.25/-3.5 46.25/-4.0 46.25/-4.5 46.25/-5.0

ZA 46.37~46.66 (46.50) 46.50/-1.5 46.50/-2.0 46.50/-2.5 46.50/-3.0 46.50/-3.5 46.50/-4.0 46.50/-4.5 46.50/-5.0

ZB 46.67~46.86 (46.75) 46.75/-1.5 46.75/-2.0 46.75/-2.5 46.75/-3.0 46.75/-3.5 46.75/-4.0 46.75/-4.5 46.75/-5.0

ZC 46.87~47.11 (47.00) 47.00/-1.5 47.00/-2.0 47.00/-2.5 47.00/-3.0 47.00/-3.5 47.00/-4.0 47.00/-4.5 47.00/-5.0

ZD 47.12~47.36 (47.25) 47.25/-1.5 47.25/-2.0 47.25/-2.5 47.25/-3.0 47.25/-3.5 47.25/-4.0 47.25/-4.5 47.25/-5.0

ZE 47.37~47.66 (47.50) 47.50/-1.5 47.50/-2.0 47.50/-2.5 47.50/-3.0 47.50/-3.5 47.50/-4.0 47.50/-4.5 47.50/-5.0


• Km: 42.87 x 44.75 @ 90Rx: - 3.50 - 1.50 x 180

• Determine K-code– Mean K=(42.87 + 44.75) / 2 = 43.81– K-code = 43.75

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K-code using Trial lenses

Properly fitted

Tight

4 steps

Loose

2 steps

Loose

4 steps

K-code using Trial Lenses

• If initial lens 43.75 fit is too tight– Fit a looser lens from trial set – Subtract 0.50D from K code (flatter K code)– Fit lens: XMJ / (43.25) / -4.50 / 10.8 mm


A 39.87~40.11 (40.00) 40.00/-1.5 40.00/-2.0 40.00/-2.5 40.00/-3.0 40.00/-3.5 40.00/-4.0 40.00/-4.5 40.00/-5.0

B 40.12~40.36 (40.25) 40.25/-1.5 40.25/-2.0 40.25/-2.5 40.25/-3.0 40.25/-3.5 40.25/-4.0 40.25/-4.5 40.25/-5.0

C 40.37~40.66 (40.50) 40.50/-1.5 40.50/-2.0 40.50/-2.5 40.50/-3.0 40.50/-3.5 40.50/-4.0 40.50/-4.5 40.50/-5.0

D 40.67~40.86 (40.75) 40.75/-1.5 40.75/-2.0 40.75/-2.5 40.75/-3.0 40.75/-3.5 40.75/-4.0 40.75/-4.5 40.75/-5.0

E 40.87~41.11 (41.00) 41.00/-1.5 41.00/-2.0 41.00/-2.5 41.00/-3.0 41.00/-3.5 41.00/-4.0 41.00/-4.5 41.00/-5.0

F 41.12~41.36 (41.25) 41.25/-1.5 41.25/-2.0 41.25/-2.5 41.25/-3.0 41.25/-3.5 41.25/-4.0 41.25/-4.5 41.25/-5.0

G 41.37~41.66 (41.50) 41.50/-1.5 41.50/-2.0 41.50/-2.5 41.50/-3.0 41.50/-3.5 41.50/-4.0 41.50/-4.5 41.50/-5.0

H 41.67~41.86 (41.75) 41.75/-1.5 41.75/-2.0 41.75/-2.5 41.75/-3.0 41.75/-3.5 41.75/-4.0 41.75/-4.5 41.75/-5.0

I 41.87~42.11 (42.00) 42.00/-1.5 42.00/-2.0 42.00/-2.5 42.00/-3.0 42.00/-3.5 42.00/-4.0 42.00/-4.5 42.00/-5.0


K 42.37~42.66 (42.50) 42.50/-1.5 42.50/-2.0 42.50/-2.5 42.50/-3.0 42.50/-3.5 42.50/-4.0 42.50/-4.5 42.50/-5.0

L 42.67~42.86 (42.75) 42.75/-1.5 42.75/-2.0 42.75/-2.5 42.75/-3.0 42.75/-3.5 42.75/-4.0 42.75/-4.5 42.75/-5.0

M 42.87~43.11 (43.00) 43.00/-1.5 43.00/-2.0 43.00/-2.5 43.00/-3.0 43.00/-3.5 43.00/-4.0 43.00/-4.5 43.00/-5.0

N 43.12~43.36 (43.25) 43.25/-1.5 43.25/-2.0 43.25/-2.5 43.25/-3.0 43.25/-3.5 43.25/-4.0 43.25/-4.5 43.25/-5.0

O 43.37~43.66 (43.50) 43.50/-1.5 43.50/-2.0 43.50/-2.5 43.50/-3.0 43.50/-3.5 43.50/-4.0 43.50/-4.5 43.50/-5.0


Q 43.87~44.11 (44.00) 44.00/-1.5 44.00/-2.0 44.00/-2.5 44.00/-3.0 44.00/-3.5 44.00/-4.0 44.00/-4.5 44.00/-5.0

R 44.12~44.36 (44.25) 44.25/-1.5 44.25/-2.0 44.25/-2.5 44.25/-3.0 44.25/-3.5 44.25/-4.0 44.25/-4.5 44.25/-5.0

S 44.37~44.66 (44.50) 44.50/-1.5 44.50/-2.0 44.50/-2.5 44.50/-3.0 44.50/-3.5 44.50/-4.0 44.50/-4.5 44.50/-5.0

T 44.67~44.86 (44.75) 44.75/-1.5 44.75/-2.0 44.75/-2.5 44.75/-3.0 44.75/-3.5 44.75/-4.0 44.75/-4.5 44.75/-5.0

U 44.87~45.11 (45.00) 45.00/-1.5 45.00/-2.0 45.00/-2.5 45.00/-3.0 45.00/-3.5 45.00/-4.0 45.00/-4.5 45.00/-5.0

V 45.12~45.36 (45.25) 45.25/-1.5 45.25/-2.0 45.25/-2.5 45.25/-3.0 45.25/-3.5 45.25/-4.0 45.25/-4.5 45.25/-5.0

W 45.37~45.66 (45.50) 45.50/-1.5 45.50/-2.0 45.50/-2.5 45.50/-3.0 45.50/-3.5 45.50/-4.0 45.50/-4.5 45.50/-5.0

X 45.67~45.86 (45.75) 45.75/-1.5 45.75/-2.0 45.75/-2.5 45.75/-3.0 45.75/-3.5 45.75/-4.0 45.75/-4.5 45.75/-5.0

Y 45.87~46.11 (46.00) 46.00/-1.5 46.00/-2.0 46.00/-2.5 46.00/-3.0 46.00/-3.5 46.00/-4.0 46.00/-4.5 46.00/-5.0

Z 46.12~46.36 (46.25) 46.25/-1.5 46.25/-2.0 46.25/-2.5 46.25/-3.0 46.25/-3.5 46.25/-4.0 46.25/-4.5 46.25/-5.0

ZA 46.37~46.66 (46.50) 46.50/-1.5 46.50/-2.0 46.50/-2.5 46.50/-3.0 46.50/-3.5 46.50/-4.0 46.50/-4.5 46.50/-5.0

ZB 46.67~46.86 (46.75) 46.75/-1.5 46.75/-2.0 46.75/-2.5 46.75/-3.0 46.75/-3.5 46.75/-4.0 46.75/-4.5 46.75/-5.0

ZC 46.87~47.11 (47.00) 47.00/-1.5 47.00/-2.0 47.00/-2.5 47.00/-3.0 47.00/-3.5 47.00/-4.0 47.00/-4.5 47.00/-5.0

ZD 47.12~47.36 (47.25) 47.25/-1.5 47.25/-2.0 47.25/-2.5 47.25/-3.0 47.25/-3.5 47.25/-4.0 47.25/-4.5 47.25/-5.0

ZE 47.37~47.66 (47.50) 47.50/-1.5 47.50/-2.0 47.50/-2.5 47.50/-3.0 47.50/-3.5 47.50/-4.0 47.50/-4.5 47.50/-5.0

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K-code using Trial Lenses

• If initial lens 43.75 fit is too loose– Prescribe a tighter lens empirically– Add 0.50 D to K code (steeper K code)– Fit lens: XMJ / (44.25) / -4.50 / 10.4 mm


A 39.87~40.11 (40.00) 40.00/-1.5 40.00/-2.0 40.00/-2.5 40.00/-3.0 40.00/-3.5 40.00/-4.0 40.00/-4.5 40.00/-5.0

B 40.12~40.36 (40.25) 40.25/-1.5 40.25/-2.0 40.25/-2.5 40.25/-3.0 40.25/-3.5 40.25/-4.0 40.25/-4.5 40.25/-5.0

C 40.37~40.66 (40.50) 40.50/-1.5 40.50/-2.0 40.50/-2.5 40.50/-3.0 40.50/-3.5 40.50/-4.0 40.50/-4.5 40.50/-5.0

D 40.67~40.86 (40.75) 40.75/-1.5 40.75/-2.0 40.75/-2.5 40.75/-3.0 40.75/-3.5 40.75/-4.0 40.75/-4.5 40.75/-5.0

E 40.87~41.11 (41.00) 41.00/-1.5 41.00/-2.0 41.00/-2.5 41.00/-3.0 41.00/-3.5 41.00/-4.0 41.00/-4.5 41.00/-5.0

F 41.12~41.36 (41.25) 41.25/-1.5 41.25/-2.0 41.25/-2.5 41.25/-3.0 41.25/-3.5 41.25/-4.0 41.25/-4.5 41.25/-5.0

G 41.37~41.66 (41.50) 41.50/-1.5 41.50/-2.0 41.50/-2.5 41.50/-3.0 41.50/-3.5 41.50/-4.0 41.50/-4.5 41.50/-5.0

H 41.67~41.86 (41.75) 41.75/-1.5 41.75/-2.0 41.75/-2.5 41.75/-3.0 41.75/-3.5 41.75/-4.0 41.75/-4.5 41.75/-5.0

I 41.87~42.11 (42.00) 42.00/-1.5 42.00/-2.0 42.00/-2.5 42.00/-3.0 42.00/-3.5 42.00/-4.0 42.00/-4.5 42.00/-5.0


K 42.37~42.66 (42.50) 42.50/-1.5 42.50/-2.0 42.50/-2.5 42.50/-3.0 42.50/-3.5 42.50/-4.0 42.50/-4.5 42.50/-5.0

L 42.67~42.86 (42.75) 42.75/-1.5 42.75/-2.0 42.75/-2.5 42.75/-3.0 42.75/-3.5 42.75/-4.0 42.75/-4.5 42.75/-5.0

M 42.87~43.11 (43.00) 43.00/-1.5 43.00/-2.0 43.00/-2.5 43.00/-3.0 43.00/-3.5 43.00/-4.0 43.00/-4.5 43.00/-5.0

N 43.12~43.36 (43.25) 43.25/-1.5 43.25/-2.0 43.25/-2.5 43.25/-3.0 43.25/-3.5 43.25/-4.0 43.25/-4.5 43.25/-5.0

O 43.37~43.66 (43.50) 43.50/-1.5 43.50/-2.0 43.50/-2.5 43.50/-3.0 43.50/-3.5 43.50/-4.0 43.50/-4.5 43.50/-5.0


Q 43.87~44.11 (44.00) 44.00/-1.5 44.00/-2.0 44.00/-2.5 44.00/-3.0 44.00/-3.5 44.00/-4.0 44.00/-4.5 44.00/-5.0

R 44.12~44.36 (44.25) 44.25/-1.5 44.25/-2.0 44.25/-2.5 44.25/-3.0 44.25/-3.5 44.25/-4.0 44.25/-4.5 44.25/-5.0

S 44.37~44.66 (44.50) 44.50/-1.5 44.50/-2.0 44.50/-2.5 44.50/-3.0 44.50/-3.5 44.50/-4.0 44.50/-4.5 44.50/-5.0

T 44.67~44.86 (44.75) 44.75/-1.5 44.75/-2.0 44.75/-2.5 44.75/-3.0 44.75/-3.5 44.75/-4.0 44.75/-4.5 44.75/-5.0

U 44.87~45.11 (45.00) 45.00/-1.5 45.00/-2.0 45.00/-2.5 45.00/-3.0 45.00/-3.5 45.00/-4.0 45.00/-4.5 45.00/-5.0

V 45.12~45.36 (45.25) 45.25/-1.5 45.25/-2.0 45.25/-2.5 45.25/-3.0 45.25/-3.5 45.25/-4.0 45.25/-4.5 45.25/-5.0

W 45.37~45.66 (45.50) 45.50/-1.5 45.50/-2.0 45.50/-2.5 45.50/-3.0 45.50/-3.5 45.50/-4.0 45.50/-4.5 45.50/-5.0

X 45.67~45.86 (45.75) 45.75/-1.5 45.75/-2.0 45.75/-2.5 45.75/-3.0 45.75/-3.5 45.75/-4.0 45.75/-4.5 45.75/-5.0

Y 45.87~46.11 (46.00) 46.00/-1.5 46.00/-2.0 46.00/-2.5 46.00/-3.0 46.00/-3.5 46.00/-4.0 46.00/-4.5 46.00/-5.0

Z 46.12~46.36 (46.25) 46.25/-1.5 46.25/-2.0 46.25/-2.5 46.25/-3.0 46.25/-3.5 46.25/-4.0 46.25/-4.5 46.25/-5.0

ZA 46.37~46.66 (46.50) 46.50/-1.5 46.50/-2.0 46.50/-2.5 46.50/-3.0 46.50/-3.5 46.50/-4.0 46.50/-4.5 46.50/-5.0

ZB 46.67~46.86 (46.75) 46.75/-1.5 46.75/-2.0 46.75/-2.5 46.75/-3.0 46.75/-3.5 46.75/-4.0 46.75/-4.5 46.75/-5.0

ZC 46.87~47.11 (47.00) 47.00/-1.5 47.00/-2.0 47.00/-2.5 47.00/-3.0 47.00/-3.5 47.00/-4.0 47.00/-4.5 47.00/-5.0

ZD 47.12~47.36 (47.25) 47.25/-1.5 47.25/-2.0 47.25/-2.5 47.25/-3.0 47.25/-3.5 47.25/-4.0 47.25/-4.5 47.25/-5.0

ZE 47.37~47.66 (47.50) 47.50/-1.5 47.50/-2.0 47.50/-2.5 47.50/-3.0 47.50/-3.5 47.50/-4.0 47.50/-4.5 47.50/-5.0

Power-Code

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Calculate Power-code by S.E.• SE=Spherical error + (K astigmatism / 2)

• Spherical power must NOT be vertexed

• Changes in 0.25D

• Prescribe

– Empirically

– Using Trial Lenses & Over refract


• Km: 42.87 x 44.75 @ 90Rx: - 3.50 - 1.50 x 180

• Determine Power-code– S.E.= - 3.50 – [(44.75-42.87) / 2] = -4.44– Power-code= -4.50

Power using Over Refraction

• Select first trial lens by empirical calculation– Fit trial set lens

– Example: XMJ/(43.75)/-3.00,

• Over refraction of XMJ/(43.75)/-3.00 = –1.50D– Power-code = -3.00 + (-1.50) = -4.50

• Order XMJ lens as:– XMJ / (43.75) / -4.50 / 10.4 mm (Predetermined

OAD)

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Power changes using the Table

Mean K/ S.E -1.50 -2.00 -2.50 -3.00 -3.50 -4.00 -4.50 -5.00

OAD 11.2 mm Best fit cornea 11.3~11.9 mm (OAD=95-97% of HVID)

A 39.87~40.11 (40.00) 40.00/-1.5 40.00/-2.0 40.00/-2.5 40.00/-3.0 40.00/-3.5 40.00/-4.0 40.00/-4.5 40.00/-5.0B 40.12~40.36 (40.25) 40.25/-1.5 40.25/-2.0 40.25/-2.5 40.25/-3.0 40.25/-3.5 40.25/-4.0 40.25/-4.5 40.25/-5.0C 40.37~40.66 (40.50) 40.50/-1.5 40.50/-2.0 40.50/-2.5 40.50/-3.0 40.50/-3.5 40.50/-4.0 40.50/-4.5 40.50/-5.0D 40.67~40.86 (40.75) 40.75/-1.5 40.75/-2.0 40.75/-2.5 40.75/-3.0 40.75/-3.5 40.75/-4.0 40.75/-4.5 40.75/-5.0E 40.87~41.11 (41.00) 41.00/-1.5 41.00/-2.0 41.00/-2.5 41.00/-3.0 41.00/-3.5 41.00/-4.0 41.00/-4.5 41.00/-5.0F 41.12~41.36 (41.25) 41.25/-1.5 41.25/-2.0 41.25/-2.5 41.25/-3.0 41.25/-3.5 41.25/-4.0 41.25/-4.5 41.25/-5.0G 41.37~41.66 (41.50) 41.50/-1.5 41.50/-2.0 41.50/-2.5 41.50/-3.0 41.50/-3.5 41.50/-4.0 41.50/-4.5 41.50/-5.0H 41.67~41.86 (41.75) 41.75/-1.5 41.75/-2.0 41.75/-2.5 41.75/-3.0 41.75/-3.5 41.75/-4.0 41.75/-4.5 41.75/-5.0I 41.87~42.11 (42.00) 42.00/-1.5 42.00/-2.0 42.00/-2.5 42.00/-3.0 42.00/-3.5 42.00/-4.0 42.00/-4.5 42.00/-5.0J 42.12~42.36 (42.25) 42.25/-1.5 42.25/-2.0 42.25/-2.5 42.25/-3.0 42.25/-3.5 42.25/-4.0 42.25/-4.5 42.25/-5.0

OAD 10.8 mm Best fit cornea: 11.2~11.6 mm (OAD =93-95% of HVID)

K 42.37~42.66 (42.50) 42.50/-1.5 42.50/-2.0 42.50/-2.5 42.50/-3.0 42.50/-3.5 42.50/-4.0 42.50/-4.5 42.50/-5.0L 42.67~42.86 (42.75) 42.75/-1.5 42.75/-2.0 42.75/-2.5 42.75/-3.0 42.75/-3.5 42.75/-4.0 42.75/-4.5 42.75/-5.0M 42.87~43.11 (43.00) 43.00/-1.5 43.00/-2.0 43.00/-2.5 43.00/-3.0 43.00/-3.5 43.00/-4.0 43.00/-4.5 43.00/-5.0N 43.12~43.36 (43.25) 43.25/-1.5 43.25/-2.0 43.25/-2.5 43.25/-3.0 43.25/-3.5 43.25/-4.0 43.25/-4.5 43.25/-5.0O 43.37~43.66 (43.50) 43.50/-1.5 43.50/-2.0 43.50/-2.5 43.50/-3.0 43.50/-3.5 43.50/-4.0 43.50/-4.5 43.50/-5.0P 43.67~43.86 (43.75) 43.75/-1.5 43.75/-2.0 43.75/-2.5 43.75/-3.0 43.75/-3.5 43.75/-4.0 43.75/-4.5 43.75/-5.0

OAD 10.4 mm Best fit cornea: 10.8~11.4 mm (OAD =92-94% of HVID)

Q 43.87~44.11 (44.00) 44.00/-1.5 44.00/-2.0 44.00/-2.5 44.00/-3.0 44.00/-3.5 44.00/-4.0 44.00/-4.5 44.00/-5.0R 44.12~44.36 (44.25) 44.25/-1.5 44.25/-2.0 44.25/-2.5 44.25/-3.0 44.25/-3.5 44.25/-4.0 44.25/-4.5 44.25/-5.0S 44.37~44.66 (44.50) 44.50/-1.5 44.50/-2.0 44.50/-2.5 44.50/-3.0 44.50/-3.5 44.50/-4.0 44.50/-4.5 44.50/-5.0T 44.67~44.86 (44.75) 44.75/-1.5 44.75/-2.0 44.75/-2.5 44.75/-3.0 44.75/-3.5 44.75/-4.0 44.75/-4.5 44.75/-5.0U 44.87~45.11 (45.00) 45.00/-1.5 45.00/-2.0 45.00/-2.5 45.00/-3.0 45.00/-3.5 45.00/-4.0 45.00/-4.5 45.00/-5.0V 45.12~45.36 (45.25) 45.25/-1.5 45.25/-2.0 45.25/-2.5 45.25/-3.0 45.25/-3.5 45.25/-4.0 45.25/-4.5 45.25/-5.0W 45.37~45.66 (45.50) 45.50/-1.5 45.50/-2.0 45.50/-2.5 45.50/-3.0 45.50/-3.5 45.50/-4.0 45.50/-4.5 45.50/-5.0X 45.67~45.86 (45.75) 45.75/-1.5 45.75/-2.0 45.75/-2.5 45.75/-3.0 45.75/-3.5 45.75/-4.0 45.75/-4.5 45.75/-5.0Y 45.87~46.11 (46.00) 46.00/-1.5 46.00/-2.0 46.00/-2.5 46.00/-3.0 46.00/-3.5 46.00/-4.0 46.00/-4.5 46.00/-5.0Z 46.12~46.36 (46.25) 46.25/-1.5 46.25/-2.0 46.25/-2.5 46.25/-3.0 46.25/-3.5 46.25/-4.0 46.25/-4.5 46.25/-5.0

ZA 46.37~46.66 (46.50) 46.50/-1.5 46.50/-2.0 46.50/-2.5 46.50/-3.0 46.50/-3.5 46.50/-4.0 46.50/-4.5 46.50/-5.0

Power Changes

Power Changes

• Moving Right = More myopia reduction

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Power Changes

• Moving Left = Less myopia reduction

Lens Diameter (OAD)

Predetermined OAD (lens size)

• OADs of trial lenses are predetermined• Flatter K’s usually measured with larger corneas• Steeper K’s usually measured with smaller corneas

KM range OAD % of HVID Best-fit HVID

40.00 ~ 42.25 11.2 mm 96% 11.3~11.9 mm

42.50 ~ 43.75 10.8 mm 94% 11.2~11.6 mm

44.00 ~ 47.50 10.4 mm 93% 10.8~11.4 mm

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Verification of corneal size

• Determine corneal size (HVID) by using– Graticule in Topographer or Slit-lamp– GOV® HVID ruler

• Lens diameter must be 93% ~ 97% of HVID

• If lens diameter is too small – Insufficient peripheral stabilization force

• If lens diameter is too large– Insufficient central compression & the lens tents up

Determine HVID from Topographer

11.0

11.2

11.4

10.0

10.2

10.4

10.6

10.8

11.0

11.2

11.4

GOV™ HVID Ruler

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Loose 1.00D

Tight 1.00D

Verify K-code

Tight 0.50D

Loose 0.50D

Optimal

86% (too small)

89% (too small)

95% (Optimal)

98% (slightly large)

105% (very large)

Verify OAD

(Optimal K-code)

Verify OAD

Verify Lens sizes (Correct K-code)

Proper

(10.8)

0.4 mm larger

0.4 mm Smaller

0.8 mm smaller

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Tear flooding

When the eyes tear excessively the lens will float on the tear layer & simulate a fit that appears too steep or too loose Pulling the inferior lid off & keeping the lens edge from touching tear meniscus, the Fluorescein pattern becomes a proper bull’s eye fit.

GOV Calculator

Fitting GOV Lenses

• Initial lens is chosen from empirical data

• Fit with diagnostic trial lenses and evaluate NaFLpattern – Look for Bull’s eye pattern

• Initial lens should not be too flat or steep

• Should move 1 – 2mm on blink

• Evaluate after 30 min using the topographer

• Does the Px show a central flattening effect?

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Fitting GOV Lenses

Flourescein patterns:

Check List for good fit

Lens adaptation and follow-up

• Centration is critical.

• Movement: 1 – 2 mm with blinking.

• Fluorescein pattern: Bulls eye pattern.

• Adequate corneal coverage

Fitting GOV Lenses

• If diagnostic lens acceptable allow Px to wear overnight and evaluate the next morning

• Allow a week for fit to settle

• If the lens is too tight or loose after a few days, use a flatter or steeper alignment curve

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GOV® Myopic S ystem

Four curve RG lens structure

• Base Curve– Hydraulic massage on central cornea

• Fitting Curve (1st reverse zone)– Space for tear circulation and epithelial tissue molding

• Alignment Curve – Peripheral force to aid molding process– Provides centration

• Peripheral Curve– Tear reservoir

Dual force for cornea molding

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GOV® XMJ Lens

• Five or more curve design• Unique XM curves to help with molding

• Aspheric alignment zone– Enhanced peripheral force– Better centration and stabilization of lens on eye

• Effective up to –5.00D– Molds faster – Maintains longer

GOV® High Myopic S ystem

GOV® XM Lens

• Five or more curve design• Unique XM curves to help molding

• Aspheric alignment zone– Enhanced peripheral force– Better centration and stabilization

• Effective up to –10.00D (or higher)• Two step procedure may be required

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Mechanism of XM molding

• Optical zone for central compression• XM curves to enhance peripheral force

– Maximize H division force – Minimize V division force

• X.M. curves to execute template effect– Steepen the mid-peripheral cornea

How does Xcessive OK work?

Compressed Epithelium depth

Compressed Epithelium depth


Normal edge profile

Conformed edge profile

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1 2 3 4 5 6 7 8 9 10

(Dioptre)

What does the XM® curves do?Central Pressure

(Eyelids)

Peripheral Pressure

(Relieve Curve )

Conventional Reverse Geometry

Design

Xtreme (XM) Reverse Geometry

Design

Central Pressure

(Eyelids)

Peripheral Pressure

(Relieve Curve)

H

V

Initial

Conformation Pressure

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What does the XM® curves do?

Conventional Reverse Geometry

Design

Xtreme (XM) Reverse Geometry

Design

Final

H

VConformation Pressure

What does the XM® curves do?

XM RGL profile Normal RGL profile

Molded corneaMolded cornea

XM Curve

Comparing Reverse Curves

-4.00D -8.00D

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Xcessive (XC) Orthokeratology

Sagittal Map

Tangential Map

Xtreme (XC) Orthokeratology

-8.00D to Pl to -8.00D

-8.05D

36.06D

+

44.11DD

+

Xcessive (XC) Orthokeratology

-8.00D to Pl to -8.00D

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High Myopia & Flat KM

-8.00-7.75/-

0.75x180

+0.75 +0.25

52-54D

34D

41D

(8.23mm)

Two step procedure might be required for high myopia

• Signs for replacing with 2nd lens– Residual myopia (after 2~3 weeks) – Unresolved central island– Solid midperipheral steeper ring in Topo– Tightened lens with central tenting in FP

• Tips for adjustment– Usually 1~2 steps looser – Looser AC will restore NaFl to Bull’s eye pattern

Two Steps ProcedureFor high myopic Ortho-K

-7.50 - 1.50 @ 165 Pl, no glare

-1.50, glare

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Hal Ostrom, OD FOAA

• Clinton, CT

Some selected cases with GOV lenses

The GOV XMJ

• 8 yo af

• 2/28/11– OD -2.25-.50 x 180– OS -2.00 -.5 x 180

• 8/19/09– OD -1.00 -.5 x 180– OS -1.25 -.5 x 180

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Step 1

• K Readings

Step 2

• Determine HVID

10.0

10.2

10.4

10.6

10.8

11.0

11.2

11.4

Step 3

• Enter Data into the Calculator

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• Trial Fit From Calculator

Order Lenses

• XMJ / 43.25 / -3.25 / 10.2 / Green

Overnight PE20/20

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Day 10 PE

• OD – VA: 20/20 – +0.75

• OS – VA: 20/20 – +0.75

• OU – VA: 20/15

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Size Does Matter

Day 1 Tangential

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Day 10 PE

What do you need?

• Good Topographies

• Diameter is Key

• Trial Set

Thank You!

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DUAL REVERSE GEOMETRY LENSES

Dual Geometry Lens

Ways to steepen central cornea

• Posterior Aspheric design

• Posterior Aspheric with

– Reverse zone (RG-DG)

• Posterior Aspheric with

– Plateau and

– Reverse zones (DG)

Corneal distortion or reshaping?

Unwanted warpage?

Central island?

Edema?

(Cornea distortion)

Intentional steepening

How is it different?

(Cornea Reshaping)

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Dual Geometry (DG) Designs• H lens (+1.00 ~ +6.00)

– Aspheric BOZR & Alignment zone

• HP lens (Pl ~ +6.00 & Add ~+3.0)– Aspheric BOZR & Alignment zone– Incorporating front progressive Add +3.0

• MP lens (-0.25 ~ -10.00 & Add ~+3.0)– Aspheric BOZR & Alignment zone– Incorporating front progressive Add +3.0

Geometric features of DG lenses

• Steep-flat-steep-flat central to Periphery

• Steeper Central zone– Molding steeper center for Far vision (H, HP)– Forming a center reading button (MP, HP)

• A relatively flat (2nd) Plateau zone– Highlighting central steepening (H, HP)– Reshaping an annular zone for distance vision (MP)

Dual Geometry Lenses

H EP, HP & MP

Can be smoothened up with aspheric curves

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GOV® Hyperopic S ystem

Hyperopic Orthokeratology

• Effective up to +5.00D

• No tight lens problems

• Simple method using reference table

• Patented design.

How does Hyperopic OK work?

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Dual Reverse Geometry Lens

Neg. Central Pressure

Neg. Peripheral Pressure

(Relieve Curve)

Pos. conformation Pressure


Fluorescein pattern (HP, H, MP with different central vaulting)

Central steepeningAlignment Zone

compression

Edge Lift

Reverse zonePlateau zone

compression

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HP lens VideoBack


Orthokeratology for Hyperopia

Topography

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Plateau zone (for H lenses precision control)

• Hyperopia (H) molding– For highlighting central steepening– Forming wide & well defined steeper central zone– Molding much faster & predictable– Less squeezing on central cornea

• How different?

Aspheric OZ without plateau zone DG lens with plateau zone

14 Days Hyperopia Correction

Case Study

• Male, 27years• Building Industry• RX

– R:+5.25/-1.50x180 VA: 6/36– L: +5.50 VA: 6/6

• Post OK– R: +0.50 VA: 6/36– L: +0.75/-0.25x125 VA: 6/6

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Hyperopic Orthokeratology

Post 5 Month – Right eye

2D Tangential Map

3D Tangential Map

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Post 5 Month – Left eye

2D Tangential Map

3D Tangential Map

DG lens for Hyperopia (ET)

+3.00D

-0.50D

+2.75D

-0.50D


GOV® Presbyopic S ystem

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Presbyopia Options

• Monovision– Over plus / Under minus for non-sighing eye

• Central for near Simultaneous Multifocal– Hyperopic or lower myopic presbyopia

• Central for far Simultaneous Multifocal– Higher myopic presbyopia

• Modified Monovision (Cross Vision)

Precision Control (for Multifocal reshaping)• Forming Near zone precisely

– Locus, zone width, steepness

• Smooth transition from near to far

• Reshaping Far zone for– Non compromised, functional far vision

• Meeting requirement for whole day clear vision

Presbyopic (HP) Lens

• Sph: Pl to +4.00D

• Add<+2.00

• Fitting– Same as for Hyperopic Lens

• Effect takes longer than Myopic OK– ±1 month to establish good near VA

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How does Presbyopic OK work?

Aspheric Design

Plateau zone (for EP & HP lenses precision control)

• Hyperopic Presbyopia (HP) molding

Precise reshaping to form a well defined Para-central Far zone

Further steepening to get a sharp central Near zone

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Reshaping myopic presbyopia

-7.00 ADD +2.00

20/25 for far , J3 for near

Plateau zone (for MP lenses precision control)

• Reshaping the Far zone– Inward molding by (3rd & 4th) outer zones – Flattening far zone by (2nd) Plateau zone– Form a wide ablation base to reduce myopia

• Flattening the far zone radially outward– Moving more tissue inward than outward– Highlight flattening by the steep rim

Further Precision Control (Centration)

• Lens size– Intra limbal, 93~100% HVID coverage

• Sagittal depth conformation– Bear lenses for para-central compression

• Aspheric alignment zone– Center better with less cornea pinch

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Presbyopic Case Study

• Male, 52 years

• Existing Soft Lens Multi-Focal wearer

• Rx– R: +1.00/-0.25x75 Add:+2.25– L: +1.00/-0.25x130 Add:+2.25


Right Lens

Left Lens


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Presbyopic (HP) LensDist VA 6/6-2 Near VA: N6

6 hrs

Initial 1 hr

2 hrs

Far : 20/25 Near : J11

Far : 20/25 Near : J3-J5

(Before)

(After)

GOV Presbyopic Lens

Case 1Low Hyperopic Presbyopia• 47 y/o female Nurse

• Refraction:

OD +0.75

OS +0.25 with add +2.00 (40cm)

• Need better near vision for nursing care

May accept slightly blurring for far vision

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Case 2Higher Hyperopic Presbyopia

• 45 y/o female, school teacher

• Refraction:

OD +4.00 – 1.00 x 15

OS +3.75 – 0.75 x 175

with add +1.50 (40cm)

• Need better far vision for driving but want spectacle free for near work also

Case 2 specs

• KM: OD 43.00 / 44.80

OS 43.00 / 44.80

HVID 11mm

• Rx: HP lens with add +2.00

OD: K(43.75)/P(+3.25)/10.2 mm

OS: K(43.75)/P(+3.00)/10.2 mm

• Result after 2 weeks till now for 6 months

Ref:

OD 20/25, pl - 0.50 x 0

OS 20/25, pl – 0.50 x 0

Near: J2 for both eyes

Wearing lenses for every day

Case 3Low Myopic Presbyopia

• 45 y/o female

• Refraction:

OD -3.00 – 0.25 x 0

OS -1.50 – 0.50 x 15

with add +1.50 (40cm)

• Need better far vision for driving but want spectacle free for near work also

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Case 3 • KM: OD 41.75 / 42.50

OS 41.40 / 42.50 HVID 11.4mm

• Rx: MP lens with add +2.00

OD: K(42.00)/P(-3.50)/11.4 mmOS: K(42.00)/P(-2.00)/11.4 mm

• Result after 2 weeks till now for 6 months

Ref: OD 20/20 plOS 20/20 pl

Near: J3 for both eyes• Wearing lenses for every day.

Case 4 High Myopic Presbyopia (Modified monovision)

• Ref:OD: -8.00 - 0.50 x 90OS: -6.25 – 0.50 x 120HVID 11.2 , add +2.00Dominant eye: OS

• Central-far, peripheral -near MP lenses with –1.00 less in targeted power for OD, full targeted for OS.

• OD 20/40 far, J5 near• OS 20/20 far, J7 near

THE ALIGNED FIT

Troubleshooting

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Aligned Fit

Good Seal off

Good Seal off

Good compression

Trouble Shooting

Ideal fit

Trouble Shooting

Bull’s Eye Pattern

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Trouble Shooting

Alignment Fit

THE ALIGNED FIT

Steep Fit

Alignment Fit

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Steep Fit

No Compression

Flatten alignment curve

• Up the column

Steep Fit

4 Steps

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Steep Fit

Steep fit – 6 Steps

Trouble Shooting

Central Islands

Steep Fit

No Compression

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Central Island

Small areas of distortion along or near the visual axis

Central Island

Cause:

• Alignment curve too tight• Excessive uncorrected astigmatism resulting in

unequal forces on the corneaSolution:• Decrease sagittal depth of lens by flattening

alignment curve– move up the column

• Decentered lens must be centered • Flatten the BC if caused by uncorrected

astigmatism– move one column right.

TOO FLAT FIT

Flat Fit

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Alignment Fit

Flat Fit

Poor Seal Off Poor Seal Off

Too much bearingSideway force induced

Flat Fit Decentred

Good Seal off

Poor Seal off

Good compression

Poor compression

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Steepen alignment curve

• Down the column

Trouble Shooting

Flat Fit – 4 Steps

Trouble Shooting

Smiley Face

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Flat Fit Decentred

Good Seal Off

Poor Seal Off

Good compressionPoor seal off and compression

Flat Fit

Smiley FaceFlat fitting lens decentered superiorly

Flat Fit

Smiley FaceCause:• Alignment curve too looseSolution:• Increase sagittal depth of lens by steepening

alignment curve– move down the column

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Size Matters !

Lens Size

Estimate lens size

• Obtain Grey to Grey HIVD by Topography

• Verify HVID manually

• Compare HVID to Best-fit HVID of the K-code

• If HVID too large (larger cornea, smaller lens)– Loose fit, Decentration, Poor effect

• If HVID too small (smaller cornea, larger lens)– Tight fit, Lens Bridging, Central island

Standard lens sizes

• Default OAD based on KM

• KM ranges

40.00 ~ 42.25 11.2 mm

42.50 ~ 43.75 10.8 mm

44.00 ~ 47.50 10.4 mm

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Big Corneas

Rule of thumb:

• KM =< (flatter) 42.25D – 95% to 97% coverage of HVID

• KM between 42.50 – 43.75D – 93% to 95% coverage of HVID

• KM => (steeper) 44.00D – 92% to 94% coverage of HVID

• 93% - 95% coverage of HVID would suit most corneas most of the time.

Big Corneas

• Use existing trial lenses to evaluate alignment curves

• Determine lens Diameter (OAD)– 93% of HVID if KM =>44.00– 94% of HVID if KM 42.50-43.75– 96% of HVID if KM =<42.25

• It is NOT necessary to alter K-code (alignment) when adjusting for OAD

• In high minus lenses (±40% of cases) a flatter alignment lens will be need later on

Big Corneas

Example:

• 45.25D Lens best fit. HVID: 12mm – 93% HVID coverage = 11.2mm– 94% HVID coverage = 11.4mm– 96% HVID coverage = 11.6mm– 45.25D lens (KM steeper than 44.00D) = 11.2mm

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Big Corneas

Example how to order:

• 45.25 Lens best fit. HVID: 12mm – 45.25 lens (KM steeper than 44.00D) = 11.2mm

– Eg. XMJ/45.25/-3.00/11.2mm

Big Cornea – Pre fit

Big Cornea

• Male, Age 21

• RIGHT– KM= 41.72 = H (41.75)– SE= -1.50D = 01 (-1.50)– XMJ/41.75/-1.50/10.4mm

• LEFT– KM= 41.56 = G (41.50)– SE= -1.50D = 01 (-1.50)– XMJ/41.50/-1.50/10.4mm

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Big Cornea – Post Fit (10.4mm)

Big Cornea (Small lens)

Big Cornea

• HVID = 12.9

• KM > 42.25D

• Rule– 95% HVID– 95% of 12.9 = 12.25mm

• Final lens ordered:– R: XMJ/41.75/-1.50/ 12.20mm– L: XMJ/41.50/-1.50/ 12.20mm

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Big Cornea – Post fit (11.20mm)

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