Transcript Document
Integration of Aberrometry and Topography with the i Trace System July 2005 Joe S. Wakil, MD Tracey Technologies, LLC EyeSys Vision, Inc. Founding Technology Developers: Vasyl Molebny, DSc Kiev, Ukraine Ioannis Pallikaris, MD Crete, Greece Canadian & Swedish Governments Why Aberroscopy? Current Laser Technology Permits One to Go Beyond Correction of Sphere and Astigmatism You Can Now Address Your Patient’s Quality of Vision High Order Aberrations Define Quality of Vision Why Ray Tracing? Because… the Eye is NOT a Telescope! Pupil Size: Effects Refraction (ex. Night Myopia) Refraction is NOT a FIXED Number! Accommodation: 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: Astigmatism, Coma & other HOA 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 Significant Higher Order Aberrations Trefoil Coma Spherical Aberration 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 auto-tracking/capture -Programmable sampling (256 pts.) in any pupil up to 8mm -Open Field Fixation – avoid instrument myopia and measure Accommodation -Corneal Topography integration – able to measure Lens Aberrations Hartmann Shack Hartmann Shack Hartmann-Shack Wavefront Sensor H/S Photo of patient with tight eye lid courtesy David Williams Tscherning Disadvantages of H-S and Tscherning • Measures All Points at Once Data Confusion, Compromised Resolution • Limited Dynamic Range – Cannot Measure Highly Irregular Eyes • Highly Sensitive to Noise – Slow, Requires Multiple Scans • Expensive Components – High Cost to Purchase and Repair • H-S Measures Reverse Aberrations – Not Physiologic with Real Vision especially for High Orders in Accomodation • Tscherning Needs 2-D Imaging of Retina Additional noise and errors Differential Skiascopy Disadvantages of Differential Skiascopy • Does NOT Measure Skew Aberrations – Inaccurate WaveFront especially for Trefoil, Quadrafoil, etc. • Measures Multiple Points at Once (slit) and only in Perpendicular Direction Limited WF measurement (axial bias) • No Open Field Fixation – Problem of instrument myopia in young patients Total Ocular Aberrations Corneal Aberrations Internal Optics Aberrations Total Ocular Aberrations *Measuring Corneal Aberration without Lens or Total Aberration is of Questionable Value The iTrace 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) • Analysis of PSF for higher order aberrations and other data formats Programmable Data Sample Points Multiplying the Number of Sites Higher Local Density of Sites Overlay of Two Sets of Site Configuration 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’s Key Advantage: Rapid, point-by-point analysis of 256 data points avoids data confusion associated with simultaneous data measurements, therefore, all eyes (highly irregular) can be measured. All points in any pupil size (2-8mm) each with full dynamic range (+/- 15 D). NO COMPROMISES! Baylor Clinical Study (100 eyes) by Doug Koch, MD +7D -13D Validation Studies Three independent studies of Tracey vs. Manifest Refraction • Koch et al - 100 eyes • Slade et al - 42 eyes • Schalhorn et al - 106 eyes Results • Accuracy to manifest • Reproducibility <0.12 D <0.12 D The iTrace Normal Eye Irregular Eye UCVA vs BCVA Post LASIK Full Corneal Topography Full Corneal Topography Keratoconu s Normal iTrace Measures Accommodation Mechanism Very Spherical Accommodation Horizontal Cyl Sphere Variations in Mapping Accommodative Power in the Natural Crystalline Lens Vertical Cyl Coma as Measured by iTrace Crystalens Accommodative Arching 73 Year Old Male Overall Refraction change is 0.5D but Central Cylinder 2.5 D adds Depth of Field to Enhance Accommodative Effect MultiFocal IOL Analysis with i Trace • PSF Analysis • Modulation Transfer Function (MTF)obust Aberrometer Pupil Dependent Analysis Multi-Zone Refraction Analysis • Retinal Spot Diagram Conoid of Sturm Dynamic Analysis • Complete Corneal Topography Analysis • Separates Corneal from Total Aberrations Resulting in Lenticular (internal ocular) Aberrations • Measures Accommodation Multifocal Acrylic IOL Alcon ReStor Lens Monofocal Acrylic IOL Alcon SA-60 Normal Eye +0.5 D Hyperope iTrace Summary • Robust Aberrometer Measures Spatially Resolved Refraction and Aberrations for ALL eyes – including highly irregular Measurement Zone from 2.0 to 8.0 mm (Flexible) Multi-Zone Refraction Analysis Can do Over-Refraction with Contact Lenses or Spectacles Measures Psuedophakic eyes • Complete Corneal Topography Analysis • Separates Corneal from Total Aberrations Resulting in Lenticular (internal ocular) Aberrations • Measures Accommodation • Accurate Pupil Size Measurement Thank you for your attention.