Title: Aspheric Laser Ablation for LASIK in Comparison to Standard Ablation with Zyoptix TS TissueSaving Al
1Aspheric Laser Ablation for LASIK in Comparison
to Standard Ablation with Zyoptix TS
Tissue-Saving Algorithm
ASCRS 2006 San Francisco
We disclose to have no financial Interest in this
study.
Q -0,5
Jörg M. Hassel, MS alz augenklinik
muenchen Thomas F. Neuhann, MD alz augenklinik
muenchen Michael C. Knorz, MD FreeVis LASIK
Zentrum Mannheim Markus Bauer, MD alz
augenklinik muenchen Barbara Lege, MD alz
augenklinik muenchen
2Poster Abstract
- Purpose The objective of this study was to
evaluate the safety and effectiveness of the
TechnoVision H.Eye.Tech Laser with Bausch Lomb
Zyoptix Tissue Saving Aspheric Algorithm versus
Zyoptix Tissue Saving Algorithm when used for
myopia and myopic astigmatism. - Methods The study was a German dual-centre study
of Prof. Th. Neuhann alz augenklinik muenchen
and Prof. M. Knorz FreeVis LASIK Centre
University Mannheim, subject masked, randomized,
bilateral eye evaluation of the BL Zyoptix
Tissue Saving Aspherical Algorithm and BL
Zyoptix Tissue Saving Algorithm for the LASIK
Corrections. A number of 18 Patients (36 eyes)
have been treated half with the Aspheric TS and
half with the TS Algorithm. Besides the safety
and efficacy parameters the effects of the
aspheric algorithm on the postoperative corneal
asphericity and its influence on the
postoperative wavefront aberration map and the
contrast sensitivity have been analyzed.Conclusi
on The BL Zyoptix Tissue Saving Aspheric
Algorithm is minimum as good as the Bausch Lomb
Zyoptix Tissue Saving Algorithm and has its
advantages in better keeping the asphericity of
the cornea. There is still room for improvement,
but we are on the right track.
3Spherical aberration, asphericity
- Rays refracted by a spherical surface do converge
the more, the more peripheral they fall onto that
surface - Refraction into one single focal point can only
be obtained by aspherical surfaces, which refract
less with increasing distance from the optical
axis
4Asphericity Parameter Q
b
a
R
- Q zero gt spherical shape (a b)
- Q positive gt oblate shape (centre flat
periphery steep) - Q negative gt prolate shape (centre steep
periphery flat)
5Ray trace calculation of surfaces of different Q
value
6Aspheric Algorithms
-0.5 -0.3 0.0
0.0µm ? -0.2µm ? -0.4µm
z400
7Basic problem
- Photorefractive procedures with spherical
ablation patterns induce spherical aberration
(SA), independently of laser type, company and
theory (Munnerlyn, Wavefront, ) - Spherical aberration causes deterioration of
imaging with increasing pupillary aperture - For optimal quality of optical imaging and,
thereby, quality of vision with larger pupils,
minimization of - induced - SE is required.
8Schematic presentation due to the induced
asphericity post-op Night Myopia vs. Pupil Size
PlanoScan
Tissue Saving -Aspheric
PlanoScan can induce spherical aberration TS-
Aspheric aims to preserve the pre-op asphericity
9Basic solution options
- Wavefront guided treatment
- Potential advantages
- Personalized treatment
- Addresses all aberrations
- Potential disadvantages
- Dependent on many variables still poorly
understood and controlled - Standard aspheric ablation pattern
- Potential advantages
- Can be optimized by iterative steps based on
result data - Addresses only induced spherical aberration
- Potential disadvantages
- Fits correction, but not individual cornea
profile
10Development of an asphericablation pattern for
the BL Zyoptix 100
- Calculation of ablation pattern for avoidance of
induced spherical aberration - Limited by peripheral depth required
- Verification in plastic
- Initial trial patients
- Evaluation of results
- Modification accordingly
- Definitive ablation pattern
11Initial Clinical Results
- 18 patients
- One eye Zyoptix TS
- One eye Zyoptix TS aspheric
- LASIK bilateral
- Hansatom Microkeratome
- Follow up
- 1 day, 1 week, 3 months
- Parameters
- Predictability
- Efficacy and Safety
- Corneal Asphericity
- Wavefront analysis
- TechnoVision Algorithm
- Not yet FDA approved
12Predictability Day 1
13Predictability 1 Week
14Predictability 3 Months
15Efficacy
16Safety
17Visual Acuity
18Wavefront Results
Zywave HORMS
Zywave HORMS w/o Z400
0,6
0,7
0,6
0,5
0,5
0,4
0,4
0,3
0,3
Pre-Op
Week 1
Month 3
Pre-Op
Week 1
Month 3
µm
µm
19Corneal Asphericity and Wavefront Results
20Corneal Asphericity and Wavefront Results
21Conclusions
- Today LASIK induces spherical aberration
- Zyoptix TS aspheric as compared to Zyoptix TS
- Is as predictable, stable, efficient and safe
- Induces less spherical aberration
- Leads to a more prolate cornea
- Induces less higher-order aberrations post op
(HORMS) -
22Thank you.
Q pre Q post is the Destination