Aspheric Laser Ablation for LASIK in Comparison to Standard Ablation with Zyoptix TS TissueSaving Al - PowerPoint PPT Presentation

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Aspheric Laser Ablation for LASIK in Comparison to Standard Ablation with Zyoptix TS TissueSaving Al

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Title: Aspheric Laser Ablation for LASIK in Comparison to Standard Ablation with Zyoptix TS TissueSaving Al


1
Aspheric 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
2
Poster 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.

3
Spherical 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

4
Asphericity 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)

5
Ray trace calculation of surfaces of different Q
value
6
Aspheric Algorithms
-0.5 -0.3 0.0
0.0µm ? -0.2µm ? -0.4µm
z400
7
Basic 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.

8
Schematic 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
9
Basic 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

10
Development 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

11
Initial 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

12
Predictability Day 1
13
Predictability 1 Week
14
Predictability 3 Months
15
Efficacy
16
Safety
17
Visual Acuity
18
Wavefront 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
19
Corneal Asphericity and Wavefront Results
20
Corneal Asphericity and Wavefront Results
21
Conclusions
  • 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)

22
Thank you.
Q pre Q post is the Destination
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