Wavefront-guided LASIK:

Transcription

Wavefront-guided LASIK:
a practical approach to diagnostic methodology and
technique, indications for LASIK with the Allegretto Wave
Instructional Course 57. Tuesday
September 10th, 2:00-4:00 PM
Faculty:
Cummings A, Jankow M, Kezirian G,
Machat J, Maus M, Mrochen M,
Moore C, Seiler T, Kanellopoulos AJ
www.brilliantvision.com
Wavefront-guided LASIK
Lessons from a 2 and 1/2 year
experience
ESCRS Munich 2003
A. John Kanellopoulos, MD
Director, Laservision.gr Eye Institute, Athens, Greece
Manhattan Eye, Ear and Throat Hospital, NY
Associate Professor, NYU Medical School, NY
My Background
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•
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Harvard Medical School-Cornea Fellow
Cornell University-Cornea Fellow
Medical Director- TLC Laser Eye Centers
Director of Refractive Surgery, NYU
Medical School, NY
• Laservision.gr Eye Institute, Athens, Greece
• Over 11000 Lasik procedures
Experience-Excimer Lasers
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Summit- Apex plus
VISX-S2 and S3
Lasersight
Nidek
Alcon-Ladarvision
B&L: Technolas 217
Wavelight: Allegretto-Wave
One of the initial LASIK cases,
1993
Common problem with standard LASIK:
“goasting”
(large pupils, de-centered/small diameter ablations
etc)
Effects of Corneal Curvature on
Ablation Profile
Round spot shape,
even energy
distribution, 96%
energy absorption
Elliptical spot shape,
only 26% energy
absorption per pulse
Cornea
The ALLEGRETTO Wave compensates for the reduced
energy absorption in the periphery with more spots!
Result: True, large optical zone and ability to create prolate
cornea shape.
Effects of Corneal Curvature on
Ablation Profile
Round spot shape,
even energy
distribution, 96%
energy absorption
Elliptical spot shape,
only 26% energy
absorption per pulse
Cornea
The ALLEGRETTO Wave compensates for the reduced
energy absorption in the periphery with more spots!
Result: True, large optical zone and ability to create prolate
cornea shape.
Prolate Ablation
Prolate Cornea Shape
Prolate Cornea Shape with the ALLEGRETTO Wave
Oblate cornea shape with other refractive laser
systems
-7D myopia
corrected in same
pt
• One eye (top) with the
Allegretto-Wave
• The other eye
(bottom) with the
Technolas 217z
Our Allegeretto-Wave and M2
experience in “standard LASIK”:
• 287 consecutive eyes, underwent LASIK for
myopia or myopic astigmatism.
• The Allegetto-Wave treats by a gaussian-profile
flying-spot of 0.9mm, with 200Hz frequency and a
250Hz active eye-tracker.
• We evaluated amount of myopia and astigmatism,
pre- and post-operative: UCVA and BCVA, IOP,
endothelial cell count and wavefront analysis by
the Wavelight Tscherning aberrometer.
Prolate or Wavefront-enhanced
LASIK
• Experience with the Allegretto
• Monitor with Wavefront analyzer
• Monitor with LCS (Vector vision)
Results:
(presented originally at the winter ESCRS meeting in Barcelona, Spain 2.2002)
• Mean values: The mean pre-operative
sphere was – 4.75 D (-1.00 to –12.50) and
the cylinder –1.25 (-0.25 to –3.75)
• UCVA improved from 20/200 to 20/25. At
3 months 87% of the eyes were 20/20, 47%
20/15 and 32% 20/10. 100% of eye were
within +/- 1D at 3 months.
Results
100
90
80
70
60
50
40
30
20
10
0
8/10 (20/25)
10/10 (20/20)
12/10 (20/16)
15/10 (20/13)
Day 1
Month 1
Month 2
Month 3
Results:
“standard”-prolate LASIK
• Wavefront analysis showed a postoperative
increase in coma of only 35% (mean coma
of 6% pre-op to 9% post-op)
• 37% of eyes gained at least 1 line of BCVA
• No complications were noted in this limited
group
Pre- and Post-op Wave
BCVA improved 10/10 to 12/10
Case example:
Pre-op RE:
+2.00 –7.00 x 167 and
BCVA 6/10
3m post “standard”
LASIK :+0.50 -0.50 x 19
UCVA 9/10
In topographic terms all
of the cylinder corrected,
of importance the effective
ablation zone on
topography is exactly the
one planned with the
laser: 6.5mm
Same patient:
Orbscan measurements:
pre-op above and postop below
Results in 520 consecutive cases
myopic astigmatism
Results in 105 consecutive cases
Hyperopia and mixed astigmatism
My Technique
Placement of the M2
Microkeratome pass
Folding of flap, even moisture on
stromal bed
Check parameters
Intraoperative
moistute eq
Irrigation of flap
and careful wipe
2’ observation interval
Flap is evaluated with build-in slit-lamp
My technique
• 1 Drop of Alcaine
• Betadine drape
• Isolate eyelids with drape
• Aspirating speculum
• Lubricate blade and rotating parts
with Alcaine!!!
My technique
• Careful check of lock
• Alcaine during MK assembly
on eye
• Technician observes tubing
• Avoid pt sqeeze
My technique
• “Taco” flap to minimize
Dehydration
• Even bed hydration
very important
My technique
• Irrigation very important
• “Squeeze” out excees
fluid and
Striae with moist Weck-cell
• “milky” drop (predforte 1%)
to delineate gutter width,
centration and striae
Why Wavefront?
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Necessary tool in today’s refractive practice
Large (usually light-colored) pupils
High astigmatism
Enhancements (decentrations)
“Enhancing” monovision
Our Wavefront-guided
experience started with a pilot
study:
• 10 patients
• One eye wavefront-guided, the
other “standard” LASIK
• Wave group: RMSh pre-op 0.120.35 (0.17), post-op dropped to:
0.11. A reduction therefore of
HOA
• Non-wave: pre-op 0.165 post-op:
0.195 a slight increase of HOA just
as in our larger standard LASIK
group reported
Purpose of Study
• To evaluate the safety, efficacy and
accuracy of wavefront-guided LASIK
• To determine the spherical nomogram
adjustment
• To evaluate the wavefront pre- and postoperatively
Key specifications
that are important for
the clinician:
• - the frequency of the flying spot treatment is 200
Hz
• - the spot size is 0.9 mm;
• - its active eye-tracking system involves an
infrared camera and three individual illumination
modules to sense the eye movement (by fixing on
the pupilary reflex) with a detection frequency of
250 Hz and a reaction time 6 to 8 msec
Method
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155 consecutive cases treated
Refractive errors:
-0.52 to -6.75 D
Average refraction: -3.80 D
Astigmatism:
0.00 to -3.75 D
Average astigmatism:
-0.85 D
Average age:
29.5 yrs
Method
• WaveFront evaluated prior to surgery (4 scans)
• Dilated pupil to 7mm (not cycloplegic, 1 drop
Mydriacyl 1%))
• Pre-op, Day 1, Week 1, month 1 and Month 3 Data
Wavefront-guided
INPUT
OUTPUT
WaveLight Laser Technologie AG 10/2000
WaveAnalyzer
Measurement
Measurement Principle
Principle
Data
Data Flow
Flow
INPUT
Optical Ocular
Aberrations
Measurement of
local distortions
Local
distortions
Calculation of
Wavefront Error
Calculation of
Ablation Profile
Custom
LASIK
WaveAnalyzer
OUTPUT
WaveFront
WaveFront basics
basics
HartmannShackSensor
TscherningSensor
+
well-known technique
+
variable incoming pattern
+
central cornea information
+
patient sees own aberrations
-
expensive sensor
-
expensive low light sensor
-
incoming light must be diffraction limited -
-
insensitive of opacities
WaveLight Laser Technologie AG
sensitive against scattering
- no central cornea information
Laser, λ=532nm
Laser Laser
Lens
AL
M
Mask
INPUT
IR-Led
IR-LED
CO
Telescope
S
Shutter
IR-Camera
OL1
Lens
Aperture stop
C2
C1
Fixation target
OUTPUT
VIS-High-Sensitive-Camera
OL2
Lens
ALLEGRETTO WAVE
WaveFront
WaveFront basics
basics
THE ALLEGRETTO WAVE ANALYZER
TS-Sensor
Opacity
Unsafe and misleading
It appears that even opaque eyes can
be measured because a clear image is
seen on the instrument display
But it is really caused by reflections of the lens.
ALLEGRETTO
WAVE
HS Sensor
Safe, only valid images can be processed
The individual beams are distracted by the
Opacity. No clear image can be seen, low risk of
accidentially treating with wrong data
By Thomas Zieger WaveLight Laser Technologie AG
Ten top pearls of my technique
• Wavefront monitoring essential for refractive
surgery
• Pt expectations
• Understand the technology (surgeon-staff)
• Aberration indices that REALLY matter
• Preoperative measurements RE
• Preoperative planning mesopic-scotopic pupil
• Preoperative wave evaluation #, quality
• Wavefront-guided OZ
• Preoperative LASIK planning
• Consistent flap, tracker, excimer energy
Importance of capture
Methods
Tserning aberrometer,
M2 and M2single use 130 and 110 heads
Results:
• Able to include 142 cases
• Mean values: The mean pre-operative sphere was
– 4.85 D (-1.00 to –6.50) and the cylinder –1.25 (0.25 to –2.75)
• UCVA improved from 20/200 to 20/18. At 3
months 92% of the eyes were 20/20, 57% 20/15
and 34% 20/10. 100% of eye were within +/- 0.5D
at 3 months.
Results: Efficacy
15
13
11
10,5
11,5
10,5
11,6
10,5
11,6
9
Pre-op BCVA
Post-op UCVA
7
5
3
1
-1
Day 1
Week 4
Month 3
Results: Safety
70
60
50
Loss of > 1 line
Loss of 1 line
No change
Gained 1 or more lines
Gained 2 or more lines
40
30
20
10
0
Day 1
Week 4
Month 3
Results Day 1:
Programmed vs. Achieved
1
0
-8
-6
-4
-2
-1 0
-2
-3
-4
-5
-6
-7
-8
Programmed
Achieved
0.5 DS Over
0.5 DS Under
Linear (Achieved)
Management of decentered
ablation with the use of
wavefront-guided LASIK
A.
John Kanellopoulos, MD
Laservision.gr Eye Institute, Athens, Greece
Manhattan Eye, Ear and Throat Hospital, NY
Michael Mrochen, PhD- Un. Of Zurich
Ablation decentration
• Troublesome compl. c serious visually debilitating sideeffects.1, 9, 10 Causes:
• Intra-op fixation error and/or drift of the patients’ fixation;
• Ecc.-displaced treatment (surgeon error or equipment
calibration error; and eye tracker or eye tracker calibration
error2).
• Larger decentrations are usually associated with larger
reductions in low contrast sensitivity and visual acuity.
3
•
Mrochen M, Krueger RR, Bueeler M, Seiler T. Aberration-sensing and
wavefront-guided laser in situ keratomileusis management of decentered
ablation. J Refract Surg 2002; Jul-Aug, 18(4)418-29.
Verdon-W; Bullimore-M; Maloney-RK
Visual performance after photorefractive keratectomy: A prospective
study Arch-of-Ophthalmol 1996;(114/12):1465-1472
Treatment Centration
• Centration = important bias in measmnts as
well as reference points in laser treatments.
• The actual clinical measmnts of wavefront, are
centered by the coaxially cited corneal reflex,
the geometrical center of the cornea, the
corneal apex, and the entrance pupil, which is
the actual point where the visual axis goes
through.
• There are several the potential biases of
decentration of the human eye
Centration errors
sytematic and random
Systematic: a constant decentration
systematic caused by different axes (coordinate systems
defined in measurement and treatment, or the defined axis
where the coordinate system is not stable, the eye tracker is
calibrated imprecisely, there is head tilt, or the initial
alignment by the operator is not precise, or there is a
fixation problem from the patient).
Centration errors
Systematic centration errors can be avoided
with precise alignment techniques. Random
or dynamic centration errors are avoided
only with active eye tracking.
Random or dynamic centration errors, which
cause “smearing” of the ablation.
Active tracking
• A small pilot study compared the advantage of active eye
tracking. Twenty eyes treated with eye tracking and 20
eyes treated without eye tracking were evaluated with
regard to their wavefront indices.
• There was difference in wavefront measurements in
trefoil, quadrafoil, higher order astigmatism, and spherical
aberrations.
• Less stat. significant aberrations with the tracker-treated
patients. This study confirms others that show eye tracking
appears to improve the visual outcome of refractive
surgery.
Advantage of active eye tracking
in refractive surgery
U
UniversitätsSpital
Zürich
• 20 eyes treated with eye-tracker
• 20 eyes treated without eye-tracker
Tracker group
Non-tracker group
Absolute value [µm]
0.12
0.10
0.08
Preoperative higher-order
wavefront deviations in
both examined groups
0.06
0.04
0.02
0.00
3-fol
d
com
a
4-fol
d
s
high
. ord pher. ab
. ast
err.
.
On the importance of centration
Mrochen-M; Eldeine-MS; Kaemmerer-M; Seiler-T; Hutz-W
Improvement in photorefractive corneal laser surgery results using an active
eye-tracking system .J Cataract-and-Refractive-Surgery. 2001; 27/7 (1000www.brilliantvision.com
1006)
Methods
• We define the decentration zone by obtaining the
difference between the pre- and postoperative
corneal topographic measurements, which is a
tangential map.
• The ablation is surrounded by a region of
approximately zero power, determined with this
method described by Mrochen.2
• The decentration of the ablation is determined as a
distance of the center of the flattened zone from
the center of the pupil.
Methods
• We term an ablation grossly decentered if
this decentration is more than 1 mm
• There is evidence that decentration, even as
much as 100 microns, will significantly
increased higher aberrations and the
possibility of the symptoms described
previously to affect the patients’ visual
quality3
Treatment
• We treat decentered ablations with a preop
evaluation using wavefront measurements and
topographic measurements of the decentered
ablation.
• The preoperative measurements include visual
acuity, topography, OrbScan measurement as
mentioned previously, and wavefront
measurement.
• low contrast sensitivity measured by the Vector
Vision 3000 device
Treatment
• The wavefront-guided treatment is relatively standard.
• Only one drop of Alcaine (proparacaine 0.5%, Allergan,
Irvine, CA) as a topical anesthetic.
• We instill a drop of ofloxacin (Ocuflox, Allergan, Irvine,
CA) mixed with preservative-free Acular as antibiotic
prophylaxis several times during flap repositioning, and a
drop of PredForte.. (Fig. 6)
• We use PredForte to delineate the flap gutter and ascertain good
centration of the repositioned flap.
• Any differences in the gutter width, either on the X or Y axis,
even if the corneal markings are perfectly aligned, indicates a
decentration of the flap, which requires repositioning.
Results
• The 3 patients were followed the first day, first week, first
month, and then at three month intervals.
• The initial group of patients have subjectively improved
symptoms including night driving and quality of night
vision.
• All symptoms of monocular diplopia, ghosting and most of
the glare subsided after this treatment.
The pre-op and post-p corneal
topography,
The pre-op and post-p wavefront map
Conclusion
• In this small group we achieved significant improvement,
both in the signs and symptoms of decentered LASIK.
• Obvious limitations the relative corneal thickness and our
ability to perform an enhancement.
• Extreme decentrations, refractive errors, and higher order
aberrations may exceed the limits that this technology can
measure precisely.
• Other methods to treat aberrated eyes are currently under
study in the U.S.11
Conclusion
• There is also promising work being done in determining
the specific Zernike polynomials in higher order
aberrations are important functionally in humans.
• Better knowledge of the clinical correlation of these
findings may help us create more effective customized
enhancements.12,13 Further studies and clinical experience
will enhance our understanding of most effective and safe
methods to retreat aberrated eyes.
•
•
Applegate, RA, Sarver EJ, Khemsara V. Are all aberrations Equal? J Refract
Surg 2002. 18:S556-562.
Applegate, RA, Ballentine C, Gross H, et al. Visual acuity as a function of
Zernike Mode and Level of RMS Error, Optom and Vis Sci, in press.
Wavefront-guided anhancements
• Now 100% of our attempted enhancements
• Since flap is created already, little new
aberrations expected
• Ability to treat decentrations and night
vision problems
• Unhappy eye study with Wavelight
Unhappy eye study with Wavelight
Methods:26 consecutive eyes that had LASIK and were
symptomatic, underwent wavefront-guided treatment, based
on 4 reproducible aberration measurements. We evaluated pre, and post-operative refraction, total and high order aberrations
(RMSH), cornea and flap thickness, low contrast sensitivity
(LCS) and possible complications. Follow-up was 3-7 months
(4.5)
Results: 22 eyes were included. The mean values were:
refractive error: sphere: –0,92D (plano to –1.50) and cylinder:
-0.85D (0 to –1,75). UCVA improved from 20/25 to 20/18.
There was no loss of BCVA in any case. The RMSH
decreased from 0.62 to 0.25. LCS improved by 55%.
Sample study cases
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45 y/o male s/p LASIK for -5
OD : plano, BCVA 20/25+, LCS C4
OS: -0.50, BCVA 20/25+ LCS C5
WG enhancement OU, 6.5mm OZ
Post-op:
OD UCVA 20/20, LCS C6
OS UCVA 20/20, LCS C5
Pre and
post-op
data
Sample case
•
•
•
•
•
•
28y/oF
LASIK for -7
OD UCVA 20/25, -0,75-1,00 15 C4
OS UCVA 20/15 plano
C6
WG enhancement OD, 6,5mmOZ
Post-op UCVA 20/15, C6
Case 5
• Old LASIK when 20y/o
• Did well for 2 years then developed KCN picture
• Management with INTACS-very happy but large
fluctuations of sphere (-2 to –8)
• Removed intacs placed ALTK sliver 120 microns
• Enhancement at 2 ms for -2.50-3.50 X 165
• 3 months post-op: 20/20
QuickTime™ and a DV - PAL decompressor are needed to see this picture.
Post-LASIK ectasia
• Minimal stroma: 280
• Minimal total K: 420
• Beware that microkeratome may become
unstable (usually they cut thinner though)
• Best treatment careful screening
Conclusion
• WaveFront-guided LASIK with the
ALLEGRETTO-WAVE (a 0.9mm flying-spot
and 200Hz) and the M2 appears to be safe and
very effective for correction of myopic
astigmatism
• It has demonstarted in our clinical practice the
ability to significantly reduce higher order
aberrations
Conclusion
• Improving the quality of vision (Contrast
sensitivity)
• The postoperative results at day one were
very impressive, possibly deriving from the
smooth ablation pattern of corneal stroma
bed and/or the smooth microkeratome pass.
• Very significant improvement in BCVA
postoperatively
Thank You

Wavefront-guided LASIK:

Transcription

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