i
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:
Accommodation:
Effects Refraction (ex. Night Myopia)
Refraction is NOT a FIXED Number!
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
• 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

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

Corneal
Aberrations
Internal
Optics
Aberrations
Total Ocular
Aberrations
*Measuring Corneal Aberration without Lens or Total Aberration is of Questionable Value

The i Trace

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
20
10
0
-10
-20
-20 -10 0
X, µm
10 20
Ablation Map
Wavefront Map

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 <0.12 D
• Reproducibility <0.12 D

The i Trace

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
Vertical Cyl
Sphere
Coma
Variations in
Mapping
Accommodative
Power in the
Natural
Crystalline Lens 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
• Measures Accommodation

Multifocal Acrylic IOL
Alcon ReStor Lens

Monofocal Acrylic IOL
Alcon SA-60

Normal Eye
+0.5 D Hyperope

i Trace
• 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
• Measures Accommodation
• Accurate Pupil Size Measurement