Transcript Tracey VFA
Wavefront by Method of Ray Tracing: Because the Eye is Not a Telescope Joe S. Wakil, M.D. Chairman, Tracey Technologies, LLC and EyeSys Vision, Inc. Speaker has a Financial Interest Founding Technology Developers: Vasyl Molebny, DSc Kiev, Ukraine Ioannis Pallikaris, MD Crete, Greece Canadian & Swedish Governments Why Dynamic Ray Tracing? Because… the Eye is NOT a Telescope! Pupil Size: Effects Refraction (ex. Night Myopia) Accommodatio Refraction is NOT a FIXED Number! n: Effects Refraction (Instrument Myopia) Tear Film: Effects Quality of Vision (Aberrations) Where are the Sources of Aberrations? How do they change with Surgery? Cornea: Astigmatism (Irreg.), Sph & other HOA Lens: The Eye is NOT a Telescope EYE TELESCOPE • • • • • • • • • • • • • • Off-Axis design No magnification Variable aperture Variable detector res. Accommodation Changing fixation Brain image processing • Nature-made On-Axis design High magnification Fixed aperture Constant detector res. No accommodation Fixed alignment Digital image processing • Man-made Aberrometer/Wavefront Technologies • Hartmann-Shack Lenslet Array • Tscherning Aberrometer • Differential Skiascopy • Ray Tracing Features: -Rapid, point by point, IR measurement - no data confusion -Pupillometry with autotracking/capture -Programmable sampling (256 pts.) in any pupil up to 8mm -Open Field Fixation – avoid instrument myopia and measure Accommodation -Corneal Topography integration – Hartmann-Shack Wavefront Sensor H/S Photo of patient with tight eye lid courtesy David Williams Principles of Tracey • Programmable thin beam ray tracing measuring forward aberrations of the eye • Rapid sequential measurement of data points over entire entrance pupil (<50ms) • Localization of each reflected retinal spot • Integration of individual retinal spots to form Point Spread Function (PSF) Data Sample Points Data Sample Points Multiplying the Number of Sites Higher Local Density of Sites Overlay of Two Sets of Site Configuration Ray Tracing Objective lens Input Beam Retina Position sensitive detector Eye optics Ray Tracing Objective lens Retina Position sensitive detector Eye optics Ray Tracing Objective lens Retina Position sensitive detector Eye optics Ray Tracing Objective lens Retina Position sensitive detector Eye optics Ray Tracing Objective lens Retina Position sensitive detector Eye optics Ray Tracing Objective lens Retina Position sensitive detector Eye optics Refractive Error Measurements Myopia Hyperopia Retinal Spot Diagram/Point Spread Function Data Displays Retinal Spot Diagram Refraction Map 40 30 Y, µm 20 10 0 -10 -20 -20 -10 0 10 20 X, µm Ablation Map Wavefront Map Tracey Analysis • • • • • Conoid of Sturm Evaluation Contrast Sensitivity Data Depth of Field Analysis Individual Data Point PSF’s Zernike Calculations Diagnostic Capabilities • Determine Higher Order Aberrations • True Point Spread Function Presentation • Optical Media Opacity Mapping • Integrated Corneal Topography Validation Studies Three independent studies of Tracey vs. Manifest Refraction • Koch et al - 58 eyes • Slade et al - 42 eyes • Schalhorn et al - 106 eyes Results • Accuracy to manifest • Reproducibility <0.12 D <0.12 D Post LASIK Post LASIK Post LASIK Keratoconu s Normal Normal Near Fixation Accommodating IOL Change due to Accommodation Far Fixation Advantages of Ray Tracing Aberrometry Combined with Corneal Topography - iTrace • Robust dynamic range to measure highly irregular eyes including immediately postop • Multi-Zone Refraction in seconds to measure variations in refraction from normal night myopes to post-op results saving chair time • Able to separate Corneal from Lenticular (internal ocular) sources of aberrations with EyeSys Corneal Topography • Improved Diagnostic Wavefront to help in patient selection including Custom LASIK and IOL procedures Conclusion The Tracey iTrace brings a new standard of care in completely assessing vision in terms of quality of vision (aberrometry) and corneal topography to progress visual correction diagnosis and treatments to its ultimate goals.