Utilizing topolyzer vario & oculyzer ii for accurate refractive outcomes

Topography guided lasik

1. Utilizing TopolyzerVario & Oculyzer II for accurate refractive outcomes Michael Mrochen, PhD

2. Content What essential data are required by your ex500? What is different between WFO and T-CAT? A limiting factor: the subjective refraction Accuracy of the TopolyzerVario Accuracy of the Oculyzer II A small pocket guide on: What to use when? 2

3. What essential data are required by your ex500 ? Ablation profile A map of required tissue removal at each point of the cornea It’s based on difference between the pre- and to post-operative cornea anterior surface Derived from either modelled or measured anterior cornea data 3

4. What essential data are required by your ex500? How to calculate an ablation profile? Assume a preoperative cornea shape (R,Q, Cyl ,…) Calculate the postoperative corneal shape based on the attempted refractive power change Define to optical zone Calculate the change in corneal height maps within the optical zone Define a transition zone 4 Preoperative Postoperative Optical zone

5. What is different between WFO and T-CAT? 5 Ex500 Algorithm WFO Wavefront Optimized for sphere and cylinder Manifest Refraction Optical zone WFO Ablation profile - Refractive predictability - Maintain visual performance Ex500 Algorithm T-CAT Topography guided for sphere, cylinder and corneal irregularities Manifest Refraction Optical zone T-CAT Ablation profile - Refractive predictability - Improve visual performance Height maps from Topolyzer / Oculyzer

6. A limiting factor: the subjective refraction Thomas W. Raasch1, Kenneth B. Schechtman2, Larry J. Davis3, Karla Zadnik1 Repeatability of subjective refraction in myopic and keratoconic subjects: results ofvector analysis. Ophthal. Physiol. Opt. Vol. 21, No. 5, pp. 376±383, 2001 Error of refraction (normal eyes) 60% [43% to 75%] ±0.25 92% [80% to 98%] ±0.5 100% [91% to 100%] ±1.0 Error of refraction (irregular cornea) 25% [18% to 33%] ±0.25 50% [41% to 58%] ±0.5 80% [72% to 86%] ±1.0

7. Accuracy of the TopolyzerVario 7 44Edges Edge Detection

8. Accuracy of the TopolyzerVario 8 Eye lashes, lid & nose Corneal irregularities Pupil detection Corneal surface / tear film

9. Degree of light scattering is of clinical relevance 9 Accuracy of the Oculyzer II

10. Accuracy of the Oculyzer II 10 Segmented measurement Motion compensation Light scattering

11. Consequences of accuracy 11 Uncertainty of topography ~ 2 - 5 microns @ 8 mm 2 micrometer will result in an uncertainty of approximately 0.14 D for an optical zone of 6.5 mm 2 micrometer will result in an uncertainty of approximately 0.98 D for an optical zone of 2.5 mm

12. A small pocket guide on: What to use when? 12 Manifest Refraction How much can I trust the Rx? TopolyzerVario Measurement Oculyzer II Measurement Mires of rings well detected? Scheimpflug images well detected? Yes Successful Topolyzer or Oculyzer measurement? No ex500 Yes No Other treatment options

13. Summary TopolyzerVario and Oculyzer II are accurate measurement devices as demonstrated by experimental measurements and clinical studies. Measurements of each device can be affected differently by the condition of the patient’s eye. Raw data checks are required to assure accurate measurements. Consequences can be irregular ablations or poor refractive predictability 13