Title: Integration of Aberrometry and Topography with the i Trace System
1Integration of Aberrometry and Topography with
thei Trace System
July 2005 Joe S. Wakil, MD - Tracey
Technologies, LLC EyeSys Vision, Inc.
2Founding Technology Developers
- Vasyl Molebny, DSc
- Kiev, Ukraine
- Ioannis Pallikaris, MD
- Crete, Greece
- Canadian Swedish Governments
3Why Aberroscopy?
- Current Laser Technology Permits One to Go Beyond
Correction of Sphere and Astigmatism - You Can Now Address Your Patients Quality of
Vision - High Order Aberrations Define
- Quality of Vision
4Why 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)
Pupil Size Accommodation Tear Film
Where are the Sources of Aberrations? How do
they change with Surgery?
Astigmatism (Irreg.), Sph other HOA
Astigmatism, Coma other HOA
Cornea Lens
5The Eye is NOT a Telescope
- EYE
- Off-Axis design
- No magnification
- Variable aperture
- Variable detector res.
- Accommodation
- Changing fixation
- Brain image processing
- Nature-made
- TELESCOPE
- On-Axis design
- High magnification
- Fixed aperture
- Constant detector res.
- No accommodation
- Fixed alignment
- Digital image processing
- Man-made
6Significant Higher Order Aberrations
Coma
Trefoil
Spherical Aberration
7Aberrometer/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
8Hartmann Shack
9Hartmann Shack
10Hartmann-ShackWavefront Sensor
H/S Photo of patient with tight eye lid courtesy
David Williams
11Tscherning
12Disadvantages 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
13Differential Skiascopy
14Disadvantages 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
15Measuring Corneal Aberration without Lens or
Total Aberration is of Questionable Value
Total Ocular Aberrations
Internal Optics Aberrations
Corneal Aberrations
Total Ocular Aberrations
16 The iTrace
17Principles of Tracey
- Programmable thin beam ray tracing measuring
forward aberrations of the eye - Rapid sequential measurement of data points over
entire entrance pupil (lt50ms) - 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
18Programmable Data Sample Points
19Multiplying the Number of Sites
20Higher Local Density of Sites
21Overlay of Two Sets of Site Configuration
22Refractive Error Measurements
Myopia
Hyperopia
23Retinal Spot Diagram/Point Spread Function
24Data Displays
25Traceys 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!
26Baylor Clinical Study (100 eyes)by Doug Koch, MD
7D
-13D
27Validation 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 lt0.12 D
- Reproducibility lt0.12 D
28 The iTrace
29Normal Eye
30Irregular Eye
31UCVA vs BCVA
32Post LASIK
33Full Corneal Topography
34Full Corneal Topography
35Keratoconus
36Normal
37iTrace Measures Accommodation Mechanism
38Very Spherical Accommodation
39Variations inMapping AccommodativePower in
the Natural Crystalline LensasMeasured
byiTrace
Horizontal Cyl
Sphere
Vertical Cyl
Coma
40Crystalens Accommodative Arching
Overall Refraction change is 0.5D but Central
Cylinder 2.5 D adds Depth of Field to Enhance
Accommodative Effect
41MultiFocal IOL Analysis withi 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
42Multifocal Acrylic IOL
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54Monofocal Acrylic IOL
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66Normal Eye
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78iTrace 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
79Thank you for your attention.