1. SurgiVision® DataLink Study Group
Mixed Astigmatism Treatments With the Allegretto Laser Comparison of Hyperopic v. Crossed Cylinder Ablations
Guy M. Kezirian, MD, FACS
SurgiVision® DataLink Study Group
December 20, 2007

2. Note to DataLink Users
This presentation is based on data from 2 DataLink surgeons
David Wallace, MD
Robin Beran, MD
The goal is to inspire other DataLink surgeons to assign mixed astigmatism eyes already entered into DataLink to either the “hyperopic” or “cross cylinder” cohort
Please participate in this worthwhile project!

3. Introduction
Mixed astigmatism exists when the sphere and cylinder components of a refraction are of opposite sign, and the cylinder magnitude is larger than the sphere
Allegretto corrects mixed astigmatism using a myopic spherical ablation with a hyperopic cylinder ablation
Some surgeons prefer a crossed cylinder approach
Combined myopic and hyperopic astigmatism ablations

4. Ablation Effects
Regardless of the treatment method, both approaches yield the same refractive change, the same central depth and the same postoperative K
Cross cylinder ablations divide the peripheral ablation in 2 meridians, where the hyperopic approach puts it all in one meridian
The following slides from Joachim Loeffler, formerly of WaveLight, illustrate these points

5. Treatment / Correction Options
Example Mixed Astigmatism: -2 / +3 x 0° equals / -3 x 90°
Different treatment options:
A) Plus Cylinder Sphere: -2 Cylinder: +3 x 0°
B) Minus Cylinder Sphere: +1 Cylinder: - 3 x 90°
C) Crossed Cylinder Cylinder1: -2 x 90° Cylinder2: +1 x 0°
D) Split Cylinder Sphere: Cylinder1: +1.5 x 0° Cylinder2: x 90°
E) Any other split cylinder …..
All options create the same refractive change and the same resulting K‘s
Courtesy of Joachim Loeffler

6. Courtesy of Joachim Loeffler
Myopic Pure Sphere 2D
Courtesy of Joachim Loeffler

7. Courtesy of Joachim Loeffler
Myopic Pure Cylinder
Courtesy of Joachim Loeffler

8. Courtesy of Joachim Loeffler
Hyperopic Pure Sphere
Courtesy of Joachim Loeffler

9. Hyperopic Pure Cylinder
Courtesy of Joachim Loeffler

10. Courtesy of Joachim Loeffler
Ablation Depths
Treatment Profiles
central 0°
90°
Plus Cylinder
Sphere
Cylinder +3 x 0°
total
20µm
0µm
30µm
Crossed Cylinder
Cylinder1 -2 x 90°
Cylinder2 +1 x 0°
Total
10µm
Courtesy of Joachim Loeffler

11. Ablation Characteristics Conclusions
All approaches provide same final K’s and central curvatures
Myopic sphere with hyperopic cyl takes more tissue in the periphery
Hyperopic sphere with myopic cyl takes more tissue centrally
Cross cyl divides the tissue between the two areas

12. What about the Allegretto?
The Allegretto is programmed with the plus-cyl approach to mixed astigmatism correction
Using cross-cyl requires double carding, interruption of treatment, manual calculations and a more complex nomogram
FDA results with plus-cyl approach were excellent (better than any other platform)
The following slides summarize the results for the FDA trial

13. FDA Cohort Description
Female 48/142 (38%) : Male 94/142 (62%)
Age: 40.2 ± 9.4 Years
75% wore no contact lenses
Refractions
Spheroequivalent: ± 0.59 D
Astigmatism: ± 1.11 D
Summary of FDA Mixed Astigmatism Results with the Allegretto (Hyperopic Cyl Approach)

14. 46% Gained 1 or More Lines BSCVA
All Safety Targets Met
One eye lost 2 lines of BSCVA
Had trauma 6 days after surgery
Went from 20/15 to 20/25
46% Gained 1 or More Lines BSCVA
Summary of FDA Mixed Astigmatism Results with the Allegretto (Hyperopic Cyl Approach)

15. UCVA Results
Summary of FDA Mixed Astigmatism Results with the Allegretto (Hyperopic Cyl Approach)

16. Spheroequivalent Results
Summary of FDA Mixed Astigmatism Results with the Allegretto (Hyperopic Cyl Approach)

17. Astigmatic Results
Summary of FDA Mixed Astigmatism Results with the Allegretto (Hyperopic Cyl Approach)

18. Achieved v. Attempted Cylinder
Summary of FDA Mixed Astigmatism Results with the Allegretto (Hyperopic Cyl Approach)

19. Doubled Angle Plots (M3)
Summary of FDA Mixed Astigmatism Results with the Allegretto (Hyperopic Cyl Approach)

20. Glare and Night Driving
Preop
Postop
Delta
Mean SD
Night Driving
4.6
2.8
4.1
2.7
-0.5
3.6
Glare
4.9
2.6
4.3
2.4
-0.6
Overall average improved for both symptoms
Summary of FDA Mixed Astigmatism Results with the Allegretto (Hyperopic Cyl Approach)

21. Change in Symptoms
Summary of FDA Mixed Astigmatism Results with the Allegretto (Hyperopic Cyl Approach)

22. SurgiVision® Data Link Post-Approval Registry Results
DataLink Analysis Cross v. Hyperopic Cylinder Treatments for Mixed Astigmatism
SurgiVision® Data Link Post-Approval Registry Results

23. SurgiVision® Data Link Post-Approval Registry Results
Current Analysis
This analysis was performed to evaluate the objective outcome metrics using both approaches
SurgiVision® Data Link Post-Approval Registry Results

24. SurgiVision® Data Link Post-Approval Registry Results
Methods
WaveLight surgeons using SurgiVision® DataLink software were asked to assign eyes entered for Mixed Astigmatism corrections to cohorts, depending on the treatment modality
Results were analyzed for refractive and visual outcomes
Month 3 outcomes were used for the analysis
NOTE: Unable to perform stability analysis due to lack of long-term data
SurgiVision® Data Link Post-Approval Registry Results

25. DataLink Surgeons: Please Assign Existing Data to the Cohorts
Assign eyes to the appropriate cohort in the Preop form of DataLink

26. SurgiVision® Data Link Post-Approval Registry Results
Total of 36 eyes were reported
Cross cylinder approach: 25 (69%)
Hyperopic cylinder approach: 11 (31%)
5 eyes operated with cross cylinder were operated using PRK
Results did not differ from the LASIK eyes, so these results were pooled with the LASIK eyes
Preoperative refractive features were similar for the two approaches
Mean Preop Cyl was 3.2 ± 1.4 D for both groups
SurgiVision® Data Link Post-Approval Registry Results

27. Uncorrected Visual Acuity 20/20 or Better Distance Targets Only
SurgiVision® Data Link Post-Approval Registry Results

28. SurgiVision® Data Link Post-Approval Registry Results
Spheroequivalent ± 0.50 D
SurgiVision® Data Link Post-Approval Registry Results

29. Postop Cylinder (Mean/SD)
SurgiVision® Data Link Post-Approval Registry Results

30. Doubled Angle Plot: Postop Cyl Hyperopic Cyl Approach1 2 3
Very little scatter
Centroid: (0.03, 0.05) SD 0.15 D
SurgiVision® Data Link Post-Approval Registry Results

31. Doubled Angle Plot: Postop Cyl Cross Cyl Approach1 2 3
Very little scatter
Centroid: (-0.03, 0.03) SD 0.46 D
SurgiVision® Data Link Post-Approval Registry Results

32. Attempted vs. Achieved Abs Cyl Hyperopic Cyl Approach
SurgiVision® Data Link Post-Approval Registry Results

33. Attempted vs. Achieved Abs Cyl Cross Cyl Approach
SurgiVision® Data Link Post-Approval Registry Results

34. SurgiVision® Data Link Post-Approval Registry Results
Discussion
Results in all categories are significantly better for hyperopic cyl
Nomograms could potentially improve the cross-cyl accuracy
However, the longer treatment time and interrupted treatment with cross-cyl approach is not amenable to nomogram improvement
Results suggest that hyperopic cyl should be used to correct mixed astigmatism with the Allegretto
More data could lead to other conclusions
SurgiVision® Data Link Post-Approval Registry Results

35. SurgiVision® Data Link Post-Approval Registry Results
Discussion
Please update the “Cohort” field in the preop form for all mixed astigmatism corrections entered into DataLink
Enter in the 3 month postop for these eyes, with a careful refraction
This will allow me to supplement this analysis with more data
SurgiVision® Data Link Post-Approval Registry Results

36. Comments Welcome DataLinkWLTForum@SurgiVision.net