Transcript Clinical Pearls for Optimizing CustomVue™ Outcomes

Ocular functional optical zone
following hyperopic LASIK/PRK:
Analysis based on polychromatic
retinal image quality
Mitchell P. Weikert, MD
Li Wang, MD, PhD
Douglas D. Koch, MD
Cullen Eye Institute
Baylor College of Medicine
Houston, TX
Financial disclosure: none.
Background
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
Traditionally, the functional optical zone
(FOZ) is analyzed based on corneal
topography*
Wavefront-guided treatments correct
ocular aberrations on anterior cornea
Optical quality of the anterior corneal
surface may not represent retinal image
quality of the whole eye

Due to the effect of the internal optics
* Holladay & Janes. JCRS 2002; Boxer Wachler et al. JCRS 2002; Racine, Wang &
Koch. AJO 2006; Tabernero et al. IOVS 2007
Purpose

To investigate the size of the ocular FOZ
before and after wavefront-guided
hyperopic LASIK/PRK

Based on optical image quality of the whole
eye
Patients and Methods
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Consecutive cases who underwent AMOCustomVue LASIK or PRK (CVLASIK/PRK) for Hyperopia by one surgeon
between 1/1/05 to 6/1/09
Inclusion criteria:
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Available follow-up at 6 months post-op
CustomVue wavefront measurements ≥6 mm
at both pre-op and 6 months post-op
Patients
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30 eyes of 21 subjects included
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Age: 51 ± 8.4 years (31to 66 years)
Pre-op CV SE: +1.70 ± 0.82 D (+0.20 to +3.53D)
Post-op CV SE: +0.86 ± 0.63 D (-0.53 to +2.10D)
Refractive correction: -0.84 ± 0.57 D (0.-1.755 to
+0.35 D)
Methods
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Based on CustomVue wavefront
measurements, ocular wavefront
aberrations were calculated for simulated
pupils from 2–6 mm in 0.1 mm intervals
Assuming full correction of 2nd order
aberrations, optical image quality of
higher-order aberrations (HOAs, 3rd-6th
order) was evaluated
Methods
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Using ZernikeTool program (AMO),
polychromatic modulation transfer function
(MTF) at 9 cyc/deg with Stiles-Crawford
effect calculated for 2-6 mm pupils
FOZ defined as the size over which the
MTF at 9 cyc/deg was ≥0.18

MTF ≥ 0.18 maintains visual acuity of ≥ 20/20
Tabernero J, Klyce SD, Sarver EJ, Artal P. IOVS 2007
Results: FOZ
FOZ range: pre-op: 5.2 - 6.0 mm
post-op: 4.1 - 6.0 mm
100 100
100 100
87
77
73
Preop
Postop
% of
eyes
100
90
80
70
60
50
40
30
20
10
0
100
≥6
≥5
≥4
FOZ (mm)
≥3
FOZ Change Following Myopic CV-PRK
Δ in FOZ (mm) % of eyes
 0.6 – 1.0
13
 0.1 – 0.5
3
0
58
 0.1 – 0.5
0
 0.6 – 1.0
13
 1.1 – 1.5
10
 1.6 – 2.0
3
FOZ vs. 4th-Order Spherical Aberration (SA)
Hyperopic CV-LASIK/PRK
7
6
FOZ (mm)
5
4
Post-op
y = 1.7294x + 6.1102
R2 = 0.3263
3
2
Pre-op
y = -1.2142x + 6.0846
R2 = 0.174
Pre-op
1
Post-op
0
-0.6
-0.4
-0.2
0
0.2
4th order SA coefficient (microns)
0.4
Post-op FOZ  with  spherical aberration (r2 = 0.33, P<0.001 )
0.6
FOZ vs. Higher Order Aberrations (HOAs)
Hyperopic CV-LASIK/PRK
7
6
FOZ (mm)
Pre-op
5 y = -1.4901x + 6.4687
R2 = 0.2547
4
Post-op
y = -2.0842x + 6.8054
R2 = 0.3074
3
2
Pre-op
1
Post-op
0
0
0.2
0.4
0.6
HOAs (microns)
Post-op FOZ  with  HOAs (r2 = 0.31, P<0.001 )
0.8
1
Change in FOZ vs. Change in SA
Hyperopic CV-LASIK/PRK
1.5
Change in FOZ (mm)
y = 1.9957x + 0.6715
R² = 0.30975
1
0.5
0
-1
-0.8
-0.6
-0.4
-0.2
0
-0.5
-1
-1.5
-2
Change in SA (microns)
FOZ  with  SA (r2 = -0.31, P<0.001 )
0.2
Change in FOZ vs. Change in HOAs
Hyperopic CV-LASIK/PRK
1.5
y = -2.3305x + 0.1124
R² = 0.36448
Change in FOZ (mm)
1
0.5
0
-0.4
-0.2
0
0.2
-0.5
-1
-1.5
-2
Change in HOAs (microns)
FOZ  with  HOAs (r2 = 0.36, P<0.001 )
0.4
0.6
Change in FOZ vs. refractive correction
Hyperopic CV-LASIK/PRK
1.5
Change in FOZ (mm)
y = 0.0858x - 0.1243
R² = 0.00572
1
0.5
0
-2
-1.5
-1
-0.5
0
-0.5
-1
-1.5
-2
Change in SE (D)
FOZ stable with  refractive correction (r2 = 0.01, P<0.001 )
0.5
Summary
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26% of eyes had post-op FOZ < 6 mm
74% of eyes had post-op FOZ ≥ 6 mm
Post-op FOZ positively correlated with SA
and negatively correlated with HOAs
Hyperopic FOZ:
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 with SA
 with  HOAs
No change with  amount of refractive correction
Limitations
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Results are not correlated with measures
of visual function
Analysis only done up to 6-mm zone
Conclusion
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FOZ following wavefront-guided hyperopic
LASIK/PRK:
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Increased to area > 6 mm in 17% of eyes
Decreased to area < 6 mm in 20% of eyes
These results may lead to further
refinement of treatment parameters
Study investigating optical FOZ following
myopic LASIK/PRK presented as
additional poster.