utilizing topolyzer vario & oculyzer ii for accurate refractive
DESCRIPTION
Topography guided LASIK, PRK, Pentacam, Oculyzer, Topolyzer, WaveLight, alconTRANSCRIPT
IROC Science to Innovation AG Technoparkstrasse 18005 ZürichTel: +41 43 500 0850
We focus your ideas
Utilizing TopolyzerVario & Oculyzer II for accurate refractive outcomes
Michael Mrochen, PhD
VISION - OPTICS - LIGHTVISION - OPTICS - LIGHT
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
VISION - OPTICS - LIGHTVISION - OPTICS - LIGHT
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
VISION - OPTICS - LIGHTVISION - OPTICS - LIGHT
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
VISION - OPTICS - LIGHTVISION - OPTICS - LIGHT
What is different between WFO and T-CAT?
5
Ex500Algorithm
WFO Wavefront Optimized for sphere and cylinder
Manifest Refraction
Optical zone
WFOAblation profile
- Refractive predictability- Maintain visual performance
Ex500Algorithm
T-CAT Topography guided for sphere, cylinder and corneal irregularities
Manifest Refraction
Optical zoneT-CAT
Ablation profile
- Refractive predictability- Improve visual performanceHeight maps from
Topolyzer / Oculyzer
VISION - OPTICS - LIGHTVISION - OPTICS - LIGHT
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%] ±0.2592% [80% to 98%] ±0.5100% [91% to 100%] ±1.0
Error of refraction (irregular cornea)
25% [18% to 33%] ±0.2550% [41% to 58%] ±0.580% [72% to 86%] ±1.0
VISION - OPTICS - LIGHTVISION - OPTICS - LIGHT
Accuracy of the TopolyzerVario
7
44Edges
Edge Detection
VISION - OPTICS - LIGHTVISION - OPTICS - LIGHT
Accuracy of the TopolyzerVario
8
Eye lashes, lid & nose Corneal irregularities
Pupil detection Corneal surface / tear film
VISION - OPTICS - LIGHTVISION - OPTICS - LIGHT
Degree of light scattering is of clinical relevance
9
Accuracy of the Oculyzer II
VISION - OPTICS - LIGHTVISION - OPTICS - LIGHT
Accuracy of the Oculyzer II
10
Segmented measurement Motion compensation
Light scattering
VISION - OPTICS - LIGHTVISION - OPTICS - LIGHT
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
VISION - OPTICS - LIGHTVISION - OPTICS - LIGHT
A small pocket guide on: What to use when?
12
Manifest Refraction
How much can I trust the Rx?
TopolyzerVarioMeasurement
Oculyzer IIMeasurement
Mires of rings well detected?
Scheimpflug images well detected?
Yes
Successful Topolyzer or
Oculyzer measurement?
Noex500
Yes
NoOther treatment
options
VISION - OPTICS - LIGHTVISION - OPTICS - LIGHT
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