Wavefront Treatment with the Carl Zeiss Meditec CRS-Master & MEL80 Excimer Laser

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  • Wavefront sensing technology is necessary to improve what we are delivering our patients. For too long we have been judging our success on 100% contrast charts. See how much more difficult it is to see when contrast is low; Instead of gauging our success on the Snellen chart, we are now looking to actually improving the quality of vision.
  • Here is a night vision view with good optics
  • Here is the same view with added spherical and other aberrations
  • Similar issues can arise from high levels of higher order aberrations during the day.
  • Multiple claims have been made about wavefront technology, but many. What has wavefront technology really allowed us to do?
  • Let me give you a real example.
  • Certainly wavefront technology has taught us that Munnerlyn profile based treatments induce considerable amounts of spherical aberration, and that aspherically optimised treatments significantly reduce the induction of spherical aberration. The big question is really: does adding the higher-order aberrations to an aspherically optimized treatment of further benefit?
  • Wavefront technology has taught us that Munnerlyn based myopic profiles induce considerable amounts of spherical aberration, and that aspherically optimised treatments significantly reduce the induction of spherical aberration. The big question is really: does adding the higher-order aberrations to an aspherically optimized sphere and cylinder treatment actually provide further benefit?
  • To find out, we prospectively studied 25 patients in whom an aspherically optimised profile was used to correct sphere and cylinder in one eye, while the other eye received the same plus the higher order aberrations present in that eye.
  • The cohort included myopic eyes evenly distributed between -1 and -7.50 D.
  • This is the standard scatter plot, showed a Pearson Correlation coefficient of 0.97 between the attempted and achieved results.
  • The first thing we learned was that adding the higher order wavefront components to the aspheric lower order treatment did not increase the scatter in the results: the correlation coefficient for the wavefront eyes was the same at 0.96
  • The second thing that we learned was that there was no difference between wavefront and aspheric alone eyes in efficacy, with over 90% achieving 20/20 or better and 20% 20/10.
  • Neither was a difference in spherical equivalent accuracy
  • Nor safety, both in lines gained or lost. However, when me moved to look at the higher order aberrations, the data was more revealing.
  • The wavefront eyes benefited by a 20% lower level of induction of spherical aberration, which was statistically significant.
  • For these eyes at 3 months follow-up, there was statistically significant improvement in contrast sensitivity in the wvaefront guided eyes, but by 6 months, this difference was no longer seen.
  • This we believed to be due to the very low levels of higher order aberrations in these normal eyes before surgery. In other words: if we are putting only a small amount of higher order aberrations into the treatment of eyes, the wavefront component of the treatment may get overshadowed by the induced aberrations caused by the sphere and cylinder treatment.
  • Wavefront Treatment with the Carl Zeiss Meditec CRS-Master & MEL80 Excimer Laser

    1. 1. Wavefront Treatment with the Carl Zeiss Meditec CRS-Master and MEL80 Excimer Laser Dan Z Reinstein MD MA(Cantab) FRCSC 1,2,3,4 1. London Vision Clinic, London, UK 2. St. Thomas’ Hospital - Kings College, London, UK 3. Weill Medical College of Cornell University, New York, 4. Centre Hospitalier National d’Ophtalmologie, (Pr. Laroche) , Paris, France
    2. 2. Why do we need Wavefront Sensing? <ul><li>Current metric of success </li></ul><ul><ul><li>Snellen chart (100% contrast) </li></ul></ul><ul><ul><li>Quantity of vision </li></ul></ul><ul><li>New metrics of success - Quality of vision </li></ul><ul><ul><li>Night Vision </li></ul></ul><ul><ul><li>Contrast Sensitivity </li></ul></ul>20/20 20/20
    3. 3. Night Vision – Starbursts & Haloes
    4. 4. Night Vision – Starbursts & Haloes
    5. 5. Reduced Contrast Sensitivity Natural vision  contrast
    6. 6. Wavefront Technology <ul><li>Reduce high pre-operative aberrations </li></ul><ul><li>Reduce surgical induction of aberrations </li></ul><ul><li>Repair highly aberrated post-operative eyes </li></ul><ul><li>Improve QUALITY of vision </li></ul>
    7. 7. Pre -3.25-0.50x102 4.63 1.51 Reduce Aberrations 0.55 0.36 Post +0.50-0.50x5
    8. 8. What has wavefront sensing taught us? <ul><li>Munnerlyn based ablation induces +++++ spherical aberration (Z4,0) </li></ul><ul><li>Aspheric ablation induces +++ ( less) spherical aberration (Z4,0) </li></ul><ul><li>Can Wavefront improve on aspheric ablation? </li></ul>
    9. 9. Can the wavefront add benefit to aspherically optimised sphero–cylindrical treatments?
    10. 10. What has wavefront sensing taught us? <ul><li>Spherically based ablation induces +++++ spherical aberration (Z4,0) </li></ul><ul><li>Aspheric ablation induces +++ ( less) spherical aberration (Z4,0) </li></ul><ul><ul><li>Reducing induced spherical aberration improves contrast sensitivity </li></ul></ul><ul><li>Can Wavefront HO’s improve outcomes beyond just aspheric ablation? </li></ul>
    11. 11. Aspheric Alone or Aspheric + Wavefront HO’s? <ul><li>Prospective study </li></ul><ul><li>Twenty-five LASIK patients </li></ul><ul><li>WASCA/CRS-Master, MEL80 </li></ul><ul><li>Paired eye control: </li></ul><ul><ul><li>(aspheric profile) vs ( aspheric profile + wavefront) </li></ul></ul>Aspheric Aspheric + HOA
    12. 12. Aspheric Alone or Aspheric + Wavefront HO’s? R Spheric Aspheric Aspheric + Wavefront HO’s
    13. 13. Preoperative parameters <ul><li>Eye pairs within 0.75 D spherical equivalent </li></ul>0.31 ± 0.098 [0.14, 0.62] 0.30 ± 0.096 [0.13, 0.47] Higher Order RMS -0.60 ± 0.40 [0.00, -1.25] -0.53 ± 0.44 [0.00, -1.50] Cylinder -3.97 ± 1.79 [-1.25. -7.38] -4.10 ± 1.80 [-1.88, -7.50] Spherical Equivalent Aspheric Wavefront Guided Aspheric
    14. 14. Results: Precision Aspheric
    15. 15. Results: Precision Aspheric Wavefront Guided
    16. 16. Add Wavefront to Aspheric Treatment? Efficacy
    17. 17. Add Wavefront to Aspheric Treatment? Accuracy
    18. 18. Add Wavefront to Aspheric Treatment? Safety
    19. 19. Average Induction of Seidel Spherical Aberration ~ 20% less Induced Spherical Aberration Add Wavefront to Aspheric Treatment? Significant
    20. 20. Results: Contrast Sensitivity 6 months 3 months * * Average Post Operative Contrast Sensitivity * *
    21. 21. Pre-Operative 6 Month Post-Operative Results: Contrast Sensitivity * * * Average Contrast Sensitivity
    22. 22. Average Contrast Sensitivity Aspheric Aspheric Wavefront Guided Results: Contrast Sensitivity
    23. 23. Discussion: Pre-op levels of HOAs Average Pre Op Zernike Coefficients Mean HO RMS: 0.30 µm (OSA Notation)
    24. 24. Conclusions <ul><li>Addition of HOAberrations to aspheric sphere and cylinder treatment results in: </li></ul><ul><ul><li>No loss of accuracy in refractive outcomes </li></ul></ul><ul><ul><li>Reduced induction of spherical aberration </li></ul></ul><ul><ul><li>Possible benefits to postoperative contrast sensitivity </li></ul></ul>
    25. 25. Benefit of Aspheric-WF over Aspheric Spherical Aberration Z4,0 -50% -50% -50% -50%

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