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GOV & VIPOK Updates. The Ideal Ortho-K Patient Suitable candidates for Ortho-K Age of Patient – older than 6 years Spherical refractive power +5D to.

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Presentation on theme: "GOV & VIPOK Updates. The Ideal Ortho-K Patient Suitable candidates for Ortho-K Age of Patient – older than 6 years Spherical refractive power +5D to."— Presentation transcript:

1 GOV & VIPOK Updates

2

3 The Ideal Ortho-K Patient Suitable candidates for Ortho-K Age of Patient – older than 6 years Spherical refractive power +5D to D Cylindrical refractive power: -1.50D or less W-T-Rule astigmatism -0.75D or less A-T-Rule astigmatism Children with progressive myopia Patients free of corneal pathology Patients that are committed to initial and ongoing cost of treatment

4 Screen for a healthy cornea Don’t fit when: Cornea is distorted Eye Rubbing (treat allergies & habit) Soft or RGP imprints (allow rehabilitation) Corneal abnormalities Irregular corneal astigmatism Keratoconus Pellucid Marginal Degeneration Lid or corneal pathology is present

5 Topographer Calibrate Topographer!

6 Topographer Accuracy depends on: Software algorithms used to reconstruct corneal shape (update software) Stability of the patient’s tear film during capture (use wetting drops) Head position & movement during capture Lid aperture (open eyes) Number of reading done to get statistically significant accuracy Take multiple readings Omit high & low values

7 Cylinder Rules <1.50D W-T-R <0.75D A-T-R Cyl ≤ ½Sph / – Problem -3.00/-1.00 – Fine

8

9 Empirical fitting vs. Systemised Fitting Systems

10 Empirical Fitting Systems Corneal information is given to lab Lab designs lens Lens works Or it doesn’t!

11 Systemised Fitting Systems General fitting process: Initial lens is chosen from chart Fit with diagnostic trial lenses and evaluate NaFL pattern – Look for Bull’s eye pattern Initial lens should not be too flat and should move 1 – 2mm on blink Evaluate after 30 min using the topographer Does the Px show a central flattening effect ?

12 Systemised Fitting Systems General fitting process If diagnostic lens looks acceptable, allow Px to wear overnight and evaluate the next morning If the lens is too tight or too loose a different lens can be chosen from trial set and refitted

13 Systemised Fitting Systems Lens adaptation and follow-up Centration is critical. Movement: 1 – 2 mm with blinking. Flourescein pattern: Bulls eye pattern.

14 Fitting the Ortho-K Lens Flourescein patterns:

15 The Orthokeratology Company GOV – Global Ortho-K Vision Vipok II – Non Conformed <-5.00D XMJ– Conformed <-5.00D XM – Conformed >5.00 <10.00D H – Hyperopia HP – Hyperopia Presbyopia MP – Miopic Presbyopia Post Lasik & Keratoconus Website (Plan Date Jan 2008) Ordering Blog Px & Prac Education

16 The GOV System Advanced inventory system Multi-curve aspheric conformed Reverse Geometry Lenses Simple method for myopia & hyperopia correction You are in control of the lens fit – not laboratories Correct from +5.00D to D GOAL A simple method to start Orthokeratology allowing for growth into fitting higher powers with the confidence that there is a support group.

17 Benifits Simple effective system You choose the appropriate lens and make changes Immediate dispensing – (full trial set) Efficient and effective method to increase turnover Develop a specialty Ortho-k practice Confidently fit with GOV support

18 GOV TM lens details Base curve Hydraulic massage to central cornea Conformed fitting curve (1 st reverse zone) Space for tear circulation & tissue molding Alignment curve (2 nd reverse) Peripheral compression & centration Peripheral curve Tear reservoir for cornea wetting

19 Predetermined OAD (lens size) OADs of trial lenses are predetermined Flatter Ks accompany larger corneas Steeper Ks accompany smaller corneas KM rangeOAD% of HVIDBest-fit HVID ~ mm96%11.3~11.9 mm ~ mm94%11.2~11.6 mm ~ mm93%10.8~11.4 mm

20 Fitting GOV TM Lenses External ocular exam Measure refraction, keratometry & HVID Select K-code by Mean K Select Power-code by S.E. Order lenses Empirically and/or with trial fit K-code / Power-code / Color / Material / OAD Lens size Predetermined Match Corneal size by Best-fit HVID

21 Orthokeratology The GOV System K-code: Mean K = (Steep K + Flat K) / 2 Carry value up to 2 decimal places (0.01) Km in Diopters Power Calculation: SE = Spherical Spec power – [K astigmatism / 2] Spherical power must not be vertexed K astigmatism = steep K – flat K (in Dioptres)

22 Mean K/ S.E 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/ / / / / / / /-5.0 B 40.12~40.36 (40.25) 40.25/ / / / / / / /-5.0 C 40.37~40.66 (40.50) 40.50/ / / / / / / /-5.0 D 40.67~40.86 (40.75) 40.75/ / / / / / / /-5.0 E 40.87~41.11 (41.00) 41.00/ / / / / / / /-5.0 F 41.12~41.36 (41.25) 41.25/ / / / / / / /-5.0 G 41.37~41.66 (41.50) 41.50/ / / / / / / /-5.0 H 41.67~41.86 (41.75) 41.75/ / / / / / / /-5.0 I 41.87~42.11 (42.00) 42.00/ / / / / / / /-5.0 J 42.12~42.36 (42.25) 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/ / / / / / / /-5.0 L 42.67~42.86 (42.75) 42.75/ / / / / / / /-5.0 M 42.87~43.11 (43.00) 43.00/ / / / / / / /-5.0 N 43.12~43.36 (43.25) 43.25/ / / / / / / /-5.0 O 43.37~43.66 (43.50) 43.50/ / / / / / / /-5.0 P 43.67~43.86 (43.75) 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/ / / / / / / /-5.0 R 44.12~44.36 (44.25) 44.25/ / / / / / / /-5.0 S 44.37~44.66 (44.50) 44.50/ / / / / / / /-5.0 T 44.67~44.86 (44.75) 44.75/ / / / / / / /-5.0 U 44.87~45.11 (45.00) 45.00/ / / / / / / /-5.0 V 45.12~45.36 (45.25) 45.25/ / / / / / / /-5.0 W 45.37~45.66 (45.50) 45.50/ / / / / / / /-5.0 X 45.67~45.86 (45.75) 45.75/ / / / / / / /-5.0 Y 45.87~46.11 (46.00) 46.00/ / / / / / / /-5.0 Z 46.12~46.36 (46.25) 46.25/ / / / / / / /-5.0 ZA 46.37~46.66 (46.50) 46.50/ / / / / / / /-5.0 ZB 46.67~46.86 (46.75) 46.75/ / / / / / / /-5.0 ZC 46.87~47.11 (47.00) 47.00/ / / / / / / /-5.0 ZD 47.12~47.36 (47.25) 47.25/ / / / / / / /-5.0 ZE 47.37~47.66 (47.50) 47.50/ / / / / / / /-5.0

23 Prescribe Empirically Km: x 90 RX: x 180 Determine K-code Mean K=( ) / 2 = K-code = Determine Power-code S.E.= – [( ) / 2] = Power-code= Empirically ordered by XMJ / (43.75) / / 10.8 mm

24 Empirically with trial fit Prescribe a looser lens empirically Subtract 0.50D from K code (flatter K code) Add D to power-code (less minus) Order lens by: XMJ / (43.25) / / 10.8 mm Prescribe a tighter lens empirically Add 0.50 D to K code (steeper K code) Add D to power code (more minus) Order lens by: XMJ / (44.25) / / 10.4 mm

25 Prescribe by over refract trial lens Select first trial lens by mean K XMJ/(43.75)/-3.00, if fit is loose try XMJ/(44.25)/ to tighten AC Over refraction of XMJ/(44.25)/-3.00 = –1.50 D Power-code = (-1.50) = Order M4 lens by: XMJ/(44.25)/-4.50/10.4 mm (Predetermined OAD)

26 As simple as Select K-code Determine Power-code Verify OAD (Lens size)

27

28 Aligned Fit Good Seal off Good compression

29 Trouble Shooting Ideal fit

30 Trouble Shooting Bull’s Eye Pattern

31 Trouble Shooting Alignment Fit

32

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34 Steep Fit No Compression

35 Flatten alignment curve Up the column

36 Steep Fit 4 Steps

37 Steep Fit Steep fit – 6 Steps

38 Trouble Shooting Central Islands

39 Steep Fit No Compression

40 Central Island Small areas of distortion along or near the visual axis

41 Central Island Cause: Alignment curve too tight Excessive uncorrected astigmatism resulting in unequal forces on the cornea Solution: 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.

42

43 Alignment Fit

44 Flat Fit Poor Seal off Too much bearingSideway force induced

45 Flat Fit Decentred Good Seal off Poor Seal off Good compression Poor compression

46 Steepen alignment curve Down the column

47 Trouble Shooting Flat Fit – 4 Steps

48 Trouble Shooting Smiley Face

49 Flat Fit Decentred Good Seal off Poor Seal off Good compression Poor seal off

50 Flat Fit Smiley Face Flat fitting lens decentered superiorly

51 Flat Fit Smiley Face Cause: Alignment curve too loose Solution: Increase sagittal depth of lens by steepening alignment curve move down the column

52 Loose 1.0 D Tight 1.0 D Lens Fitting Tight 0.50 D Loose 0.50 D Optimal

53 Verifying tightness Properly fitted Tight 4 steps Loose 2 steps Loose 4 steps

54

55 Power Changes

56 Moving Right = More myopia reduction

57 Power Changes Moving Left = Less myopia reduction

58

59 Estimate lens size Obtain white to white corneal Diameter by Topography Verify Visible Iris Diameter (VID), horizontal & vertically manually Compare VID to Best-fit VID of the K-code If VID too large (larger cornea, smaller lens) Loose fit, Decentration, Poor effect If VID too small (smaller cornea, larger lens) Tight fit, Lens Bridging, Central island

60 Standard lens sizes Default OAD based on KM KM ranges ~ mm ~ mm ~ mm

61 Big Corneas Rule of thumb: KM =< (flatter) 42.25D 95% to 97% coverage of VID KM between – 43.75D 93% to 95% coverage of VID KM => (steeper) 44.00D 92% to 94% coverage of VID 93% - 95% coverage of VID would suit most corneas most of the time.

62 Big Corneas Use existing trial lenses to evaluate alignment curves Determine lens Diameter (OAD) 93% of VID if KM => % of VID if KM % of VID if KM =<42.25 It is NOT necessary to alter K-kode (alignment) when adjusting for OAD In high minus lenses (±40% of cases) a flatter alignment lens will be need later on

63 Big Corneas Example: V (45.25D) Lens best fit. VID: 12mm 93% VID coverage = 11.2mm 94% VID coverage = 11.4mm 96% VID coverage = 11.6mm V lens (KM steeper than 44.00D) = 11.2mm

64 Big Corneas Example how to order: V Lens best fit. VID: 12mm V lens (KM steeper than 44.00D) = 11.2mm Eg. 2V04, 11.20mm or XMJ/45.25/-3.00/11.2mm

65 86% too small 98% slightly large Lens Size 89% too small 95% Optimal 105% very large

66 Case 1 – Big Cornea

67 Male, Age 21 RIGHT KM= = H (41.75) SE= -1.50D = 01 (-1.50) Trial 2H01, 10.4mm or XMJ/41.75/-1.50/10.4mm LEFT KM= = G (41.50) SE= -1.50D = 01 (-1.50) Trial = 2G01, 10.4mm or XMJ/41.50/-1.50/10.4mm

68 Case 1 – Big Cornea

69 Case 1 – Big Cornea (Small lens)

70 Case 1 – Big Cornea HVID = 12.9 KM > 42.25D Rule 95% HVID 95% of 12.9 = 12.25mm Final lens ordered: R: 2H01, 12.2mm L: 2G01, 12.2mm

71 Case 1 – Big Cornea

72 Thank you For more information please met at:


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