Contenu connexe Similaire à High Myopia Final CZM Dubai_2011 Similaire à High Myopia Final CZM Dubai_2011 (20) Plus de London Vision Clinic Plus de London Vision Clinic (12) High Myopia Final CZM Dubai_20111. Very high myopic LASIK using new
hybrid 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 d’Ophtalmologie, (Pr. Laroche) , Paris, France
2. 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.
©DZ Reinstein 2009
dzr@londonvisionclinic.com
3. Ablation Profile Design: Larger Optical Zone
Example: 5-mm Munnerlyn ablation for -6.00 D (1993 Summit Laser)
Topography Wavefront
Z(4,0) (OSA)
1.18 µm
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.
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.
©DZ Reinstein 2009
dzr@londonvisionclinic.com
4. Ablation Profile Design: Aspheric Profiles
• Barraquer 1980
– Suggested parabolic keratomileusis
• Seiler 1993 – PRK aspheric profiles
– Less starburst & halos
– Larger effective clear optical zone size
©DZ Reinstein 2009
dzr@londonvisionclinic.com
6. Optimization: Fluence correction
• Fluence correction: Topography
– Beam reflection compensation
– Beam projection compensation
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.
©DZ Reinstein 2009
dzr@londonvisionclinic.com
8. Reinstein et al. Journal of Refractive Surgery
Artemis C12 Display 2000 Jul-Aug;16:414-30
VHF digital ultrasound
Roberts C. The cornea is not a piece of plastic.
JRS 2000; 16:407-413
©DZ Reinstein 2009
dzr@londonvisionclinic.com
9. Examples of Peripheral Stromal Thickening
Peripheral Stromal
Thickening
Central Flattening
Roberts C. The cornea is not a piece of plastic.
©DZ Reinstein 2009
dzr@londonvisionclinic.com
10. Corneal Biomechanical Trade-off
• Hyperopic shift induced by
– Central flattening due to peripheral tissue removal
• Myopic shift induced by
Pre-Op
– Epithelial thickening
– Bowing of the back surface
Epithelial thickening
Post-Op
Back surface bowing
©DZ Reinstein 2009
dzr@londonvisionclinic.com
12. ESCRS 2002, DZ Reinstein: Z4,0-Slider (aka Q-slider)
©DZ Reinstein 2009
dzr@londonvisionclinic.com
13. ESCRS 2002, DZ Reinstein: Z4,0-Slider (aka Q-slider)
©DZ Reinstein 2009
dzr@londonvisionclinic.com
14. ESCRS 2002, DZ Reinstein: Z4,0-Slider (aka Q-slider)
©DZ Reinstein 2009
dzr@londonvisionclinic.com
15. ESCRS 2002, DZ Reinstein: Z4,0-Slider (aka Q-slider)
©DZ Reinstein 2009
dzr@londonvisionclinic.com
16. ESCRS 2002, DZ Reinstein: Z4,0-Slider (aka Q-slider)
©DZ Reinstein 2009
dzr@londonvisionclinic.com
17. ESCRS 2002, DZ Reinstein: Z4,0-Slider (aka Q-slider)
©DZ Reinstein 2009
dzr@londonvisionclinic.com
18. Free Lunch?
• Increasing ablation zone diameter
• Adding asphericity
• Increases central
ablation depth
• No “Free Lunch”
©DZ Reinstein 2009
dzr@londonvisionclinic.com
19. 550 µm Pachymetry: Forces Compromise
• Modern aspheric ablation profiles still induce spherical
aberration
• Problem: high myopic corrections may result in NVDs
Attempted Spherical Equivalent vs. Change in Z(4,0) Coefficient
ASA Treatments
0.7
y = -0.059x - 0.0136
0.6
) R² = 0.6444
A
S
O 0.5
,
m
µ
(
t 0.4
n
e
i
c
i
f
f 0.3
e
o
C 0.2
)
0
,
4
(
Z 0.1
n
i
e
g 0.0
n
a
h
C -0.1
-0.2
0.00 -1.00 -2.00 -3.00 -4.00 -5.00 -6.00 -7.00 -8.00 -9.00 -10.00
Attempted Spherical Equivalent (Diopters)
©DZ Reinstein 2009
dzr@londonvisionclinic.com
21. Correlation of Contrast with Wavefront
Spherical Aberration Contrast Sensitivity
p
900 1.2
800 t 1.1
s
700 a o
r i
t t 1.0
600 n a
o R
C y 0.9
500 t
d i
e v
z i
t
2 400 i i
l s
a n
0.8
m 300 m
r e
µ o S
0.7
200 N
0.6
100
0.5
0 3 cpd 6 cpd 12 cpd 18 cpd
Pre CRS-M Post CRSM-
Control Pre Control Post Control Pre 1.02 1.02 1.03 1.04
Repair Repair
Control Post 1.04 1.01 1.03 1.01
Sph Ab Area 122 276 563 410 Pre CRSM-Repair 0.85 0.84 0.77 0.75
Post CRSM-Repair 1.04 1.02 1.02 1.00
• 27% Gross Reduction
• 53% Net Reduction (cf tolerable level)
• Tolerable level ~0.56 µm @ 6mm
©DZ Reinstein 2009
dzr@londonvisionclinic.com
22. 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
©DZ Reinstein 2009
dzr@londonvisionclinic.com
23. Patient 1, OD
-7.13 D Corrected
6mm OSA 6mm OSA
Coma 0.09 µm Coma 0.04 µm
Sph Ab 0.48 µm Sph Ab 0.42 µm
HO RMS 0.59 µm HO RMS 0.52 µm
©DZ Reinstein 2009
dzr@londonvisionclinic.com
24. Patient 1, OS
-9.00 D Corrected
6mm OSA 6mm OSA
Coma 0.03 µm Coma 0.05 µm
Sph Ab 0.49 µm Sph Ab 0.55 µm
HO RMS 0.57 µm HO RMS 0.60 µm
©DZ Reinstein 2009
dzr@londonvisionclinic.com
25. Patient 1, Night Vision
Pre Op Post Op
Rx Treated
OD -6.50 -1.25 x 178
OS -8.25 -1.50 x 17
©DZ Reinstein 2009
dzr@londonvisionclinic.com
26. Induction of Spherical Aberration
Complaint of NVD post RS1
1
©DZ Reinstein 2009
dzr@londonvisionclinic.com
27. Limits to SA Pre-Compensation
• Excess spherical aberration pre-compensation can
lead to “central islands”
TMS WASCA (zonal) Epithelium
OD
©DZ Reinstein 2009
dzr@londonvisionclinic.com
28. CENTRAL ISLANDS:
-5.50 D ablation
Diplopia first week
Slow resolution over 2 weeks
Slides courtesy Gordon Balazsi, MD
©DZ Reinstein 2009
dzr@londonvisionclinic.com
31. New Profile for High Myopia
• Non-linear aspheric ablation profile:
– Increased peripheral ablation (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
Roberts C. The cornea is not a piece of plastic.
©DZ Reinstein 2009
dzr@londonvisionclinic.com
32. New Profile: “Free Lunch”
• Over-corrected by +0.50 D compared with theory
• Ablation depth lower than expected
Attempted vs. Achieved Spherical Equivalent
-14
y = 0.9958x - 0.5106
) -13 R² = 0.9291
s
r
e
t
p-12
o
i
D
(
t -11
n
e
l
a
v -10
i
u
q
E -9
l
a
c
i
r
e -8
h
p
S
d -7
e
v
e
i
h -6
c
A
-5
-6 -7 -8 -9 -10 -11 -12 -13 -14
Attempted Spherical Equivalent (Diopters)
©DZ Reinstein 2009
dzr@londonvisionclinic.com
34. Femtosecond Lasers
• Femtosecond lasers have improved flap thickness
reproducibility (VisuMax SD: 8 µm)
• We can create thinner flaps (VisuMax: 80 µm)
• Thinner flaps extends the range of myopia in LASIK
Pre-release online
©DZ Reinstein 2009
dzr@londonvisionclinic.com
35. Example RST Planning
Refraction -10.75 D sph
Pachymetry 509 µm
Flap Thickness (VisuMax) 80 µm
Ablation Depth 135 µm
Predicted RST 296 µm
©DZ Reinstein 2009
dzr@londonvisionclinic.com
37. 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%
©DZ Reinstein 2009
dzr@londonvisionclinic.com
38. 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
©DZ Reinstein 2009
dzr@londonvisionclinic.com
39. Topography Guided Retreatment
Pre Post Reduced
Sph Ab 0.48 µm 0.28 µm 41%
HO RMS 0.72 µm 0.57 µm 21%
©DZ Reinstein 2009
dzr@londonvisionclinic.com
40. MEL80 High Myopia: Accuracy
Attempted vs. Achieved Spherical Equivalent
-14
) y = 1.0726x + 0.8394
s
r
e
t
-13 R² = 0.8759
p
o
i
D
(
t -12
n
e
l
a
v
i -11
u
q
E
l
a
c
i -10
r
e
h
p
S -9
d
e
v
e
i
h -8
c
A
-7
-7 -8 -9 -10 -11 -12 -13 -14
Attempted Spherical Equivalent (Diopters)
©DZ Reinstein 2009
dzr@londonvisionclinic.com
41. MEL80 High Myopia: Accuracy
Within ±0.50
71%
D
Within ±1.00
94% Accuracy: Within Range of Intended
D
35% 33%
30%
25%
s 25%
e
y
E 20%
e 15%
g 15% 13%
a
t
n
e 10%
c
r 7%
e
P 5% 3%
0% 1% 1%
0%
-2.00 -1.50 -1.00 -0.50 -0.13 0.14 +0.51 +1.01 +1.51
To - To - To - To - To To To To To
1.51 1.01 0.51 0.14 0.13 +0.50 +1.00 +1.50 +2.00
Accuracy 0% 3% 15% 33% 25% 13% 7% 1% 1%
Accuracy of Spherical Equivalent
©DZ Reinstein 2009
dzr@londonvisionclinic.com
42. Monocular Efficacy
(excluding eyes not intended plano)
n=176
Efficacy: Monocular UCVA
100% 99% 99% 99%
100% 97%
90%
83%
80%
s
e
y
E 60%
e 47%
g
a
t
n 40%
e 28%
c
r
e
P 20%
11%
1%
0%
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%
Monocular UCVA
©DZ Reinstein 2009
dzr@londonvisionclinic.com
43. MEL80 High Myopia: Safety – BSCVA
n=220 Safety: Lines Change BSCVA
60%
52%
s 40%
e
y 40%
E
e
g
a
t
n
e 20%
c
r
e
P N=4
6%
2%
0.0% 0.0%
0%
Loss 3 or No Gain 2 or
Loss 2 Loss 1 Gain 1
More Change More
Safety 0.0% 0.0% 2% 40% 52% 6%
Lines Change BSCVA
©DZ Reinstein 2009
dzr@londonvisionclinic.com
44. MEL80 High Myopia: Contrast Sensitivity
*
* Statistically significant (p<0.05)
©DZ Reinstein 2009
dzr@londonvisionclinic.com
45. Stability
2.00
) 0.00
D
(
t
n
e
l -2.00
a
v
i
u
q
E -4.00
l
a
c
i
r
e -6.00
h
p
S
-8.00
-10.00
-12.00
3 Mo 6 Mo 12 Mo 24 Mo
Pre-op 1 Day 1 Month 3 Months 6 Months 1 Year 2 Years
Mean±SD -9.60±1.39 +0.41±0.82 +0.01±0.82 -0.18±0.86 -0.22±0.91 -0.04±0.91 -0.06±1.07
# eyes 220 199 201 188 158 124 45
©DZ Reinstein 2009
dzr@londonvisionclinic.com
46. Take Home Message
• Know your spherical aberration induction per dioptre
• Measure pre-op spherical aberration
• Check whether spherical aberration is going to go
beyond the threshold
– Use SA pre-compensation
– Use a 2-stage procedure (wavefront / topography guided
repair if necessary as second treatment)
• Caution with predicted RST
– Reduce potential errors
– Measure pachymetry with high repeatability instrument
– Use high reproducibility flap creation technique
– Always include flap thickness bias
©DZ Reinstein 2009
dzr@londonvisionclinic.com
47. Thank You
Very high myopic LASIK using new
hybrid aspheric profiles
Dan Z Reinstein MD MA(Cantab) FRCSC FRCOphth1,2,3,4