high myopia final czm dubai 2011

8/6/2019 High Myopia Final CZM Dubai 2011

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Very high myopic LASIK using newhybrid aspheric profiles

Dan Z Reinstein MD MA(Cantab) FRCSC FRCOphth1,2,3,4

1. London Vision Clinic, London, UK

2. St. Thomas Hospital - Kings College, London, UK

3. Weill Medical College of Cornell University, New York, USA

4. Centre Hospitalier National dOphtalmologie, (Pr. Laroche) , Paris, France


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DZ Reinstein [email protected]

First Results: Munnerlyn Ablation Profile

Early ablation profiles often induced:

Night Vision disturbances Decreased contrast sensitivity

Limited the range of treatable refractions

PROBLEM: Induction of spherical aberration

Eur J Ophthalmol. 1994 Jan-Mar;4(1):43-51. Night vision after

excimer laser photorefractive keratectomy: haze and halos. O'Brart

DP, Lohmann CP, Fitzke FW, Smith SE, Kerr-Muir MG, Marshall J.


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Ablation Profile Design: Larger Optical Zone

Arch Ophthalmol. 1995 Apr;113(4):438-43. The effects of

ablation diameter on the outcome of excimer laser

photorefractive keratectomy. A prospective, randomized,

double-blind study. O'Brart DP, Corbett MC, Lohmann CP,

Kerr Muir MG, Marshall J.

J Refract Corneal Surg. 1994 Mar-Apr;10(2):87-94.

Excimer laser photorefractive keratectomy for myopia:

comparison of 4.00- and 5.00-millimeter ablation zones.

O'Brart DP, Gartry DS, Lohmann CP, Muir MG, Marshall J.

Topography Wavefront

Z(4,0) (OSA)

1.18 m

Example: 5-mm Munnerlyn ablation for -6.00 D (1993 Summit Laser)


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Ablation Profile Design: Aspheric Profiles

Barraquer 1980 Suggested parabolic keratomileusis

Seiler 1993 PRK aspheric profiles Less starburst & halos

Larger effective clear optical zone size


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Why was spherical aberrationincreasing?


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Fluence correction: Topography

Beam reflection compensation Beam projection compensation

Optimization: Fluence correction

J Refract Surg 2001;17(5):S584-7.

Influence of corneal curvature on

calculation of ablation patterns

used in photorefractive laser

surgery. Mrochen M, Seiler T.


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Optimization

Biomechanics

VHF digital ultrasound


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Artemis C12 DisplayReinstein et al. Journal of Refractive Surgery

2000 Jul-Aug;16:414-30

Roberts C. The cornea is not a piece of plastic.

JRS 2000; 16:407-413

VHF digital ultrasound


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Examples of Peripheral Stromal Thickening


Peripheral Stromal

Thickening

Central Flattening


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Corneal Biomechanical Trade-off

Hyperopic shift induced by

Central flattening due to peripheral tissue removal

Myopic shift induced by

Epithelial thickening

Bowing of the back surface

Post-Op

Pre-Op

Back surface bowing

Epithelial thickening


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Free lunch?


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ESCRS 2002, DZ Reinstein: Z4,0-Slider(aka Q-slider)


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Free Lunch?

Increasing ablation zone diameter

Adding asphericity

Increases central

ablation depth

No Free Lunch


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550 m Pachymetry: Forces Compromise

Modern asphericablation profiles still induce spherical

aberration Problem: high myopic corrections may result in NVDs

y = -0.059x - 0.0136

R= 0.6444

-0.2

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

-10.00-9.00-8.00-7.00-6.00-5.00-4.00-3.00-2.00-1.000.00

Attempted Spherical Equivalent vs. Change in Z(4,0) Coefficient

ASA Treatments

Attempted Spherical Equivalent (Diopters)

Changein

Z(4,0)Coefficient(m,OSA)


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Wavefront-Guided Treatmentof Spherical Aberration


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Contro l Pre Control PostPre CRS-M

RepairPost CRSM-

Repair

Sph Ab Area 122 276 563 410

0

100

200

300

400

500

600

700800

900

m

2

3 cpd 6 cpd 12 cpd 18 cpd

Control Pre 1.02 1.02 1.03 1.04

Control Post 1.04 1.01 1.03 1.01Pre CRSM-Repair 0.85 0.84 0.77 0.75

Post CRSM-Repair 1.04 1.02 1.02 1.00

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

NormalizedContrast

SensitivityRatio

Correlation of Contrast with Wavefront

Spherical Aberration Contrast Sensitivity

27% Gross Reduction

53% NetReduction (cf tolerable level)

Tolerable level ~0.56 m @ 6mm


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Pre-Compensate for Spherical Aberration

Q-slider

(WaveLight) Wavefront-guided ablation

Includes pre-op spherical aberration

Effect dependent on pre-op spherical aberration

Our Approach: Include an artificial wavefront

Isolate spherical aberration: Z(4,0) as the only coefficient

Z(4,0) coefficient proportional to expected induction Increase Z(4,0) coefficient: wavefront only 20% effective


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Patient 1, OD

-7.13 D Corrected

6mm OSA

Coma 0.04 m

Sph Ab 0.42 m

HO RMS 0.52 m

6mm OSA

Coma 0.09 m

Sph Ab 0.48 m

HO RMS 0.59 m


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Patient 1, Night Vision

Rx TreatedOD -6.50 -1.25 x 178

OS -8.25 -1.50 x 17

Pre Op Post Op


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Induction of Spherical Aberration

Complaint of NVD post RS1

1


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Limits to SA Pre-Compensation

Excess spherical aberration pre-compensation can

lead to central islands

TMS WASCA (zonal) Epithelium

OD


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CENTRAL ISLANDS:

Slides courtesy Gordon Balazsi, MD

-5.50 D ablationDiplopia first week

Slow resolution over 2 weeks


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CENTRAL ISLANDS:

Slides courtesy Gordon Balazsi, MD

-5.00 D ablation


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Ablation Depth with SA Pre-Compensation


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New Profile for High Myopia

Non-linear aspheric ablation profile:

Increasedperipheralablation (not z(4,0)) Reduced induction of spherical aberration

Free lunch: some myopia corrected due to central

flattening

Extend this concept further to promote central flattening

Ability to correct high myopia without risk of NVDs


Peripheral Stromal

Thickening

Central Flattening


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New Profile: Free Lunch

Over-corrected by +0.50 D compared with theory

Ablation depth lower than expected

y = 0.9958x - 0.5106

R = 0.9291

-14

-13

-12

-11

-10

-9

-8

-7

-6

-5

-14-13-12-11-10-9-8-7-6

Attempted vs. Achieved Spherical Equivalent


AchievedSphericalEquivalent(D

iopters)


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Ablation Depth for New Profile


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Femtosecond Lasers

Femtosecond lasers have improved flap thickness

reproducibility(VisuMax SD: 8 m) We can create thinner flaps (VisuMax: 80 m)

Thinner flaps extends the range of myopia in LASIK

Pre-release online

S


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Example RST Planning

Refraction -10.75 D sph

Pachymetry 509 m

Flap Thickness (VisuMax) 80 m

Ablation Depth 135 m

Predicted RST 296 m


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Outcomes

N P fil f Hi h M i


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New Profile for High Myopia

Patients

Myopia SEQ -9.51 1.32 D -8.00 up to -14.50 D Myopia max merid -10.18 1.48 D -8.00 up to -16.00 D

Cylinder -1.32 1.10 D up to -6.25 D

220 eyes

1 year follow up

Retreatments

45% eyes treated as two-stage

Enhancement rate (non two-stage): 35%

Ad t f T St P d


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Advantages of Two Stage Procedure

Increased safety

Greater RST for primary treatment Artemis measured RST to calculate retreatment

Option to retreat using topography-guided profile

More accurate result

Patient has lower expectations

T h G id d R t t t


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Topography Guided Retreatment

Pre Post Reduced

Sph Ab 0.48 m 0.28 m 41%

HO RMS 0.72 m 0.57 m 21%

MEL80 Hi h M i A


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MEL80 High Myopia: Accuracy

y = 1.0726x + 0.8394R = 0.8759

-14

-13

-12

-11

-10

-9

-8

-7

-14-13-12-11-10-9-8-7

Attempted vs. Achieved Spherical Equivalent


Ach

ievedSphericalEqu

ivalent(Diopters)

MEL80 Hi h M i A


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-2.00

To -1.51

-1.50

To -1.01

-1.00

To -0.51

-0.50

To -0.14

-0.13

To0.13

0.14

To+0.50

+0.51

To+1.00

+1.01

To+1.50

+1.51

To+2.00

Accuracy 0% 3% 15% 33% 25% 13% 7% 1% 1%

0%

3%

15%

33%

25%

13%

7%

1%1%0%

5%

10%

15%

20%

25%

30%

35%

PercentageEyes

Accuracy of Spherical Equivalent

Accuracy: Within Range of Intended

MEL80 High Myopia: Accuracy

Within0.50

D71%

Within1.00

D94%

Monocular Efficacy


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20/12.5 20/16 20/20 20/25 20/32 20/40 20/63

Pre BSCVA 1% 28% 83% 100%

Efficacy 11% 47% 90% 97% 99% 99% 99%

1%

28%

83%

100%

11%

47%

90%

97% 99% 99% 99%

0%

20%

40%

60%

80%

100%

Percentage

Eyes

Monocular UCVA

Efficacy: Monocular UCVA

Monocular Efficacy(excluding eyes not intended plano)

n=176

MEL80 Hi h M i S f t BSCVA


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MEL80 High Myopia: Safety BSCVA

Loss 3 or

More

Loss 2 Loss 1No

Change

Gain 1Gain 2 or

MoreSafety 0.0% 0.0% 2% 40% 52% 6%

0.0% 0.0%2%

40%

52%

6%

0%

20%

40%

60%

PercentageEyes

Lines Change BSCVA

Safety: Lines Change BSCVA

N=4

n=220

MEL80 Hi h M i C t t S iti it


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MEL80 High Myopia: Contrast Sensitivity

*

* Statistically significant (p


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Thank You


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Very high myopic LASIK using new

hybrid aspheric profilesDan Z Reinstein MD MA(Cantab) FRCSC FRCOphth1,2,3,4

Thank You

high myopia final czm dubai 2011

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