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Founding Technology Developers: Vasyl Molebny, dsc
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tarix | 14.12.2017 | ölçüsü | 461 b. | | #34852 |
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Founding Technology Developers: Vasyl Molebny, DSc Kiev, Ukraine Ioannis Pallikaris, MD Crete, Greece
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! Effects Refraction (ex. Night Myopia) Refraction is NOT a FIXED Number! Effects Refraction (Instrument Myopia) Effects Quality of Vision (Aberrations)
The Eye is NOT a Telescope EYE Off-Axis design No magnification Variable aperture Variable detector res. Accommodation Changing fixation Nature-made
Significant Higher Order Aberrations
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
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
*Measuring Corneal Aberration without Lens or Total Aberration is of Questionable Value
The iTrace
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
Refractive Error Measurements
Retinal Spot Diagram/Point Spread Function
Data Displays
Baylor Clinical Study (100 eyes) by Doug Koch, MD
Validation Studies Tracey vs. Manifest Refraction Koch et al - 100 eyes Slade et al - 42 eyes Schalhorn et al - 106 eyes Results Accuracy to manifest <0.12 D Reproducibility <0.12 D
The iTrace
Normal Eye
Irregular Eye
UCVA vs BCVA
Full Corneal Topography
Full Corneal Topography
iTrace Measures Accommodation Mechanism
Very Spherical Accommodation
Variations in Mapping Accommodative Power in the Natural Crystalline Lens as Measured by iTrace
Crystalens Accommodative Arching
MultiFocal IOL Analysis with i Trace PSF Analysis Modulation Transfer Function (MTF)obust Aberrometer - Pupil Dependent Analysis
- Multi-Zone Refraction Analysis
Retinal Spot Diagram Complete Corneal Topography Analysis Separates Corneal from Total Aberrations Resulting in Lenticular (internal ocular) Aberrations Measures Accommodation
Multifocal Acrylic IOL
Monofocal Acrylic IOL
Normal Eye
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
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