Optimized Zernike Terms Selection In Customized Treatments For Laser Corneal Refractive Surgery
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Transcript of Optimized Zernike Terms Selection In Customized Treatments For Laser Corneal Refractive Surgery
Optimized Zernike Terms SelectionIn Customized Treatments
For Laser Corneal Refractive Surgery6 months experience in state-of-the-art treatments
Maria C. Arbelaez, MD1
Samuel Arba Mosquera, MSc2,3
Camila Vidal, OD1
The authors Arbelaez and Vidal have no proprietary interest in the materials presented hereinSamuel Arba Mosquera is employee at SCHWIND eye-tech-solutions
Part of a Doctoral Thesis in Sciences of Vision
1 Muscat Eye Laser Center (Sultanate of Oman)2 Grupo de Investigación en Cirugía Refractiva y Calidad de Visión (IOBA, Spain)
3 SCHWIND eye-tech-solutions (Germany)Preceptor: Jesús Merayo2
Goals:To evaluate the clinical application of two methods for minimizing the required ablation tissue based upon:- objective minimization of the maximum depth of a customized ablation- objective minimization of the ablation volume of a customized ablationboth based on the Zernike expansion of the wavefront aberration
Materials:- SCHWIND CAM Software Platform (not approved by U.S. Food and Drug Administration)
- SCHWIND ESIRIS Excimer Laser (not approved by U.S. Food and Drug Administration)
- SCHWIND Ocular Wavefront Analyzer (not approved by U.S. Food and Dug Administration)
- SCHWIND Corneal Wavefront Analyzer:- OPTIKON Keratron Scout
- Contrast Sensitivity Tester:- Vision Sciences Research Corporation CST 1800 D
Optimized Zernike Terms Selection in Customized Treatments for Laser Corneal Refractive Surgery
Optimized Zernike Terms Selection in Customized Treatments for Laser Corneal Refractive Surgery
Arbelaez, MD. and colsArbelaez, MD. and cols
Groups:3 groups treated with LASIK technique with 30 eyes each:- Corneal Wavefront group (CW): Full customized correction- Min Depth group (MD): Optimal Zernike terms selection for minimum depth- Min Volume group (MV): Optimal Zernike terms selection for minimum time
Optimized Zernike Terms Selection in Customized Treatments for Laser Corneal Refractive Surgery
Optimized Zernike Terms Selection in Customized Treatments for Laser Corneal Refractive Surgery
min Depth min Vol
Only terms of 3rd or higher order (HOA terms) can be disabled
Only terms with optical blur ≤0.25D can be disabled Only terms with optical blur ≤0.25D can be disabled
For each subset of Zernike terms, Automatic Refraction Balance is used
The subset of Zernike terms that needs minimum depth is selected
The subset of Zernike terms that needs minimum ablation volume is selected
CW MD MV
Arbelaez, MD. and colsArbelaez, MD. and cols
Optimized Zernike Terms Selection in Customized Treatments for Laser Corneal Refractive Surgery
Optimized Zernike Terms Selection in Customized Treatments for Laser Corneal Refractive Surgery
Metric CW group MD group MV group
Eyes (number) 30 30 30
Age (years)(mean, range)
2418 to 35
2920 to 47
2718 to 47
Gender(Male / Female)
19 / 11 14 / 16 17 / 13
Eye(OD / OS)
16 / 14 17 / 13 12 / 18
Pre-op SEq (D)(mean±stddev, range)
-2.80±1.25-5.50 to -1.00
-3.15±1.57-6.38 to -0.75
-2.90±1.44-6.88 to -0.75
Post-op SEq (D)(mean±stddev, range)
-0.22±0.23-0.75 to +0.38
-0.22±0.23-0.75 to +0.25
-0.26±0.21-0.62 to +0.13
Pre-op Sph (D)(mean±stddev, range)
-2.31±1.39-5.25 to 0.00
-2.76±1.63-6.25 to 0.00
-2.38±1.65-6.50 to 0.00
Post-op Sph (D)(mean±stddev, range)
-0.13±0.26-0.75 to +0.50
-0.14±0.24-0.75 to +0.25
-0.14±0.23-0.50 to +0.25
Pre-op Cyl (D)(mean±stddev, range)
-0.98±0.84-3.75 to 0.00
-0.77±0.54-2.50 to 0.00
-1.05±0.86-4.25 to -0.25
Post-op Cyl (D)(mean±stddev, range)
-0.19±0.19-0.50 to 0.00
-0.16±0.19-0.50 to 0.00
-0.24±0.25-0.75 to 0.00
Arbelaez, MD. and colsArbelaez, MD. and cols
Refractive OutcomesRefractive Outcomes
Very good refractive outcomes from the three groups:
> 57% in 0.25 D; 100% in 1.00 D > 90% in 0.50 DEq; 100% in 1.00 DEq
60%57%
73%
93%100%
93%100%100%100%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
S.
A.
Mos
quer
a S
chw
ind
ET
S
+- 0,2
5
+- 0,5
+- 1,0
Refractive outcome - Percentage within | Attempted |
CW (30) MV (30)
MD (30)
month (eyes)
60%57%
73%
93%100%
93%100%100%100%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
S.
A.
Mos
quer
a S
chw
ind
ET
S
+- 0,2
5
+- 0,5
+- 1
,0
Refractive outcome - Percentage within | Attempted |
CW (30) MV (30)
MD (30)
month (eyes)
93%90%
93%100% 100% 100%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
S. A
. Mos
quer
a S
chw
ind
ET
S
<=0,
5D<=
1D
Defocus Equivalent - Percentage
CW (30)
MD (30)
MV (30)
month(eyes)
93%90%
93%100% 100% 100%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
S. A
. Mos
quer
a S
chw
ind
ET
S
<=0,
5D<=
1D
Defocus Equivalent - Percentage
CW (30)
MD (30)
MV (30)
month(eyes)
Best results for the MV group, but not statistically significant
Arbelaez, MD. and colsArbelaez, MD. and cols
PredictabilityPredictability
Very high predictability from the three groups. SEq Cyl
Best results for the MV group, but not statistically significant
Scatter: Attempted vs. Achieved SEQ 'PREDICTABILITY' 3 x 30 eyes
y = 1,00x - 0,22
R2 = 0,97
y = 0,95x - 0,04
R2 = 0,98
y = 0,99x - 0,21
R2 = 0,98
0
1
2
3
4
5
6
7
0 1 2 3 4 5 6 7Attempted delta SR equiv. [D]
S.
A.
Mos
quer
a S
chw
ind
ET
S
Achieved [D]
overcorrected
undercorrected
Scatter: Attempted vs. Achieved SEQ 'PREDICTABILITY' 3 x 30 eyes
y = 1,00x - 0,22
R2 = 0,97
y = 0,95x - 0,04
R2 = 0,98
y = 0,99x - 0,21
R2 = 0,98
0
1
2
3
4
5
6
7
0 1 2 3 4 5 6 7Attempted delta SR equiv. [D]
S.
A.
Mos
quer
a S
chw
ind
ET
S
Achieved [D]
overcorrected
undercorrected
Scatter: Attempted change in CYL vs. SIRC 3 x 30 eyes
y = 0,88x + 0,01
R2 = 0,94
y = 0,94x - 0,01
R2 = 0,91
y = 0,95x - 0,10
R2 = 0,92
0
1
2
3
4
0 1 2 3 4Attempted Cyl [D]
S.
A.
Mos
quer
a S
chw
ind
ET
S
Achieved [D]
overcorrected
undercorrected
Scatter: Attempted change in CYL vs. SIRC 3 x 30 eyes
y = 0,88x + 0,01
R2 = 0,94
y = 0,94x - 0,01
R2 = 0,91
y = 0,95x - 0,10
R2 = 0,92
0
1
2
3
4
0 1 2 3 4Attempted Cyl [D]
S.
A.
Mos
quer
a S
chw
ind
ET
S
Achieved [D]
overcorrected
undercorrected
Arbelaez, MD. and colsArbelaez, MD. and cols
Stability & EfficacyStability & Efficacy
Very stable results from the three groups since the first month follow up
Results for the MD and MV groups better than for CW group,statistically significant (p < 0.01)
Achieved Correction SEQ over Time 'STABILITY'
-3,15
-2,90
-0,24-0,21
-2,80
-0,24-0,21
-0,28-0,23
303030-3,50
-3,00
-2,50
-2,00
-1,50
-1,00
-0,50
0,00
pre op 1 m 3 m
S. A
. Mo
squ
era
Sch
win
d E
TS
Achieved Correction SEQ over Time 'STABILITY'
-3,15
-2,90
-0,24-0,21
-2,80
-0,24-0,21
-0,28-0,23
303030-3,50
-3,00
-2,50
-2,00
-1,50
-1,00
-0,50
0,00
pre op 1 m 3 m
S. A
. Mo
squ
era
Sch
win
d E
TS
17%
37%37%
70%
63%63%
13%
0%
10%
20%
30%
40%
50%
60%
70%
S. A
. Mos
quer
a S
chw
ind
ET
S
UCVA - Percentage 'EFFICACY'
CW (30)
MD (30)
MV (30)
month(eyes)
17%
37%37%
70%
63%63%
13%
0%
10%
20%
30%
40%
50%
60%
70%
S. A
. Mos
quer
a S
chw
ind
ET
S
UCVA - Percentage 'EFFICACY'
CW (30)
MD (30)
MV (30)
month(eyes)
Very good UCVA postoperative from the three groups
> 87% UCVA 20/20 or better
Arbelaez, MD. and colsArbelaez, MD. and cols
SafetySafety
Between 34% and 47% of the treatmentsgained at least 1 line of BSCVANo single eye lost even 1 line of BSCVA
Best results for the MV group, but not statistically significant
Between 30% and 40% of the treatments with post-op UCVA were better than pre-op BSCVA
10%
50%
70%
60%
40%
23%
33%
7%7%
0%
10%
20%
30%
40%
50%
60%
70%
S. A
. Mos
quer
a S
chw
ind
ET
S
lost
>=
2
lost
1
unchan
ged
gained
1
gained
>=
2
Change in UCVA vs. preOP BSCVA - Percentage
CW (30)
MD (30)
MV (30)
month(eyes) 10%
50%
70%
60%
40%
23%
33%
7%7%
0%
10%
20%
30%
40%
50%
60%
70%
S. A
. Mos
quer
a S
chw
ind
ET
S
lost
>=
2
lost
1
unchan
ged
gained
1
gained
>=
2
Change in UCVA vs. preOP BSCVA - Percentage
CW (30)
MD (30)
MV (30)
month(eyes)
60%
66%
53%
40%
27%
40%
7%7%
0%
10%
20%
30%
40%
50%
60%
70%
S. A
. Mos
quer
a S
chw
ind
ET
S
lost
>=
2
lost
1
unchan
ged
gained
1
gained
>=
2
Change in BSCVA - Percentage 'SAFETY'
CW (30)
MD (30)
MV (30)
month(eyes)
60%
66%
53%
40%
27%
40%
7%7%
0%
10%
20%
30%
40%
50%
60%
70%
S. A
. Mos
quer
a S
chw
ind
ET
S
lost
>=
2
lost
1
unchan
ged
gained
1
gained
>=
2
Change in BSCVA - Percentage 'SAFETY'
CW (30)
MD (30)
MV (30)
month(eyes)
Arbelaez, MD. and colsArbelaez, MD. and cols
Contrast SensitivityContrast Sensitivity
Excellent improvement in postoperative contrast sensitivity for all three groups
Best results for the MV group, but not statistically significant
Contrast Sensitivity Mesopic
0,68
1,32
1,821,76
0,83
1,46
1,941,83
0,84
1,38
1,98
1,81
0,92
1,42
1,98
1,85
0,40
0,60
0,80
1,00
1,20
1,40
1,60
1,80
2,00
2,20
A (3cpd) B (6cpd) C (12cpd) D (18cpd)
S.
A.
Mos
quer
a S
chw
ind
ET
S
pre op (90)
CW (30)
MD (30)
MV (30)
month
Spatial Frequency [cycles/degree]
Contrast Sensitivity Mesopic
0,68
1,32
1,821,76
0,83
1,46
1,941,83
0,84
1,38
1,98
1,81
0,92
1,42
1,98
1,85
0,40
0,60
0,80
1,00
1,20
1,40
1,60
1,80
2,00
2,20
A (3cpd) B (6cpd) C (12cpd) D (18cpd)
S.
A.
Mos
quer
a S
chw
ind
ET
S
pre op (90)
CW (30)
MD (30)
MV (30)
month
Spatial Frequency [cycles/degree]
Arbelaez, MD. and colsArbelaez, MD. and cols
ComparisonComparison
MD group saved -4 µm depth in averageMV group saved -3 µm depth in average
MD group saved -3 s time in averageMV group saved -4 s time in average
CW MD Diff
Avg. Ablation Depth (µm)
46 ± 32 42 ± 31 -4 ± 2
Ablation Depth range (µm)
24 – 103 19 – 98 -11 – -1
Avg. Ablation Time (s)
38 ± 20 35 ± 20 -3 ± 1
Ablation Time range (s)
17 – 76 15 – 71 -8 – 0
min Depth < Ab-Free (%)
--- 43% (13) ---
CW MV Diff
Avg. Ablation Depth (µm)
46 ± 32 43 ± 31 -3 ± 2
Ablation Depth range (µm)
32 – 88 27 – 83 -9 – 0
Avg. Ablation Time (s)
38 ± 20 34 ± 20 -4 ± 1
Ablation Time range (s)
21 – 86 17 – 73 -13 – 0
min Vol < Ab-Free (%)
--- 40% (12) ---
Arbelaez, MD. and colsArbelaez, MD. and cols
SummarySummary
Avg. Diff. (µm)
Avg. Diff. (%)
Max. Diff. (µm)
Max. Diff. (%)
min Depth correction
-4 ± 2 -8% -11 -23%
min Vol correction
-3 ± 2 -5% -9 -20%
MD group saved -4 µm depth in averageMV group saved -3 µm depth in average
MD group saved -3 s time in averageMV group saved -4 s time in average
Avg. Diff. (s)
Avg. Diff. (%)
Max. Diff. (s)
Max. Diff. (%)
min Depth correction
-3 ± 1 -7% -8 -24%
min Vol correction
-4 ± 1 -10% -13 -25%
Ablation depth
y = 1,00x
R2 = 1,00
y = 0,97x - 2,32
R2 = 0,99
y = 0,94x + 0,71
R2 = 0,94
0
20
40
60
80
100
120
0 20 40 60 80 100 120
Ablation depth for full customised correction (µm)
Ab
lati
on
dep
th f
or
op
tim
al Z
ern
ike
term
s se
lect
ion
(µ
m)
CorWave
MinDepth
MinVol
Linear (CorWave)
Linear (MinDepth)
Linear (MinVol)
Ablation time
y = 1,00x
R2 = 1,00
y = 0,96x - 2,19
R2 = 0,99
y = 0,89x + 1,50
R2 = 0,96
0
10
20
30
40
50
60
70
80
90
0 10 20 30 40 50 60 70 80 90
Ablation time for full customised correction (µm)
Ab
lati
on
tim
e fo
r o
pti
mal
Zer
nik
e te
rms
sele
ctio
n (
µm
)
CorWave
MinDepth
MinVol
Linear (CorWave)
Linear (MinDepth)
Linear (MinVol)
Arbelaez, MD. and colsArbelaez, MD. and cols
Conclusions:
- The three groups compared here (CW, MD and MV) are Predictable, Safe, Stable and Accurate
- The two minimization techniques compared here can be used to reduce the depth and time needed for the ablation
- Depth and time were effectively reduced by up to a maximum of 25%, and by 8% in average
- The performed ablations reduced in depth and time did not affect negatively the clinical outcomes postoperatively
- The two minimization techniques compared here yielded results equivalent to those of the full customization group
Conclusions:
- The three groups compared here (CW, MD and MV) are Predictable, Safe, Stable and Accurate
- The two minimization techniques compared here can be used to reduce the depth and time needed for the ablation
- Depth and time were effectively reduced by up to a maximum of 25%, and by 8% in average
- The performed ablations reduced in depth and time did not affect negatively the clinical outcomes postoperatively
- The two minimization techniques compared here yielded results equivalent to those of the full customization group
Optimized Zernike Terms Selection in Customized Treatments for Laser Corneal Refractive Surgery
Optimized Zernike Terms Selection in Customized Treatments for Laser Corneal Refractive Surgery
Arbelaez, MD. and colsArbelaez, MD. and cols
Optimized Zernike Terms Selection in Customized Treatments for Laser Corneal Refractive Surgery
Optimized Zernike Terms Selection in Customized Treatments for Laser Corneal Refractive Surgery
Conclusions II: What I would choose for minimizationConclusions II: What I would choose for minimization
CW MD MV
Minimization principle --- Minimum depthMinimum volumeMinimum time
When to be usedIn very high
aberrated eyesAt risk of
keratectasiaWhen treatment time is very long
Typical case
Low refractive corrections, predominant aberrations
Customized myopias
Customized hyperopias
Typical savings ----4 µm-3 s
-3 µm-4 s
Maximum savings ----10 µm
-8 s-9 µm-13 s
Arbelaez, MD. and colsArbelaez, MD. and cols