Integration of Aberrometry and Topography with the i Trace System

1
Integration of Aberrometry and Topography with
thei Trace System
July 2005 Joe S. Wakil, MD - Tracey
Technologies, LLC EyeSys Vision, Inc.
2
Founding Technology Developers

• Vasyl Molebny, DSc
• Kiev, Ukraine
• Ioannis Pallikaris, MD
• Crete, Greece
• Canadian Swedish Governments

3
Why 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

4
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)

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
5
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

6
Significant Higher Order Aberrations
Coma
Trefoil
Spherical Aberration
7
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

8
Hartmann Shack
9
Hartmann Shack
10
Hartmann-ShackWavefront Sensor
H/S Photo of patient with tight eye lid courtesy
David Williams
11
Tscherning
12
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

13
Differential Skiascopy
14
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

15
Measuring 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
17
Principles 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

18
Programmable Data Sample Points
19
Multiplying the Number of Sites
20
Higher Local Density of Sites
21
Overlay of Two Sets of Site Configuration
22
Refractive Error Measurements
Myopia
Hyperopia
23
Retinal Spot Diagram/Point Spread Function
24
Data Displays
25
Traceys 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!
26
Baylor Clinical Study (100 eyes)by Doug Koch, MD
7D
-13D
27
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 lt0.12 D
• Reproducibility lt0.12 D

28
The iTrace
29
Normal Eye
30
Irregular Eye
31
UCVA vs BCVA
32
Post LASIK
33
Full Corneal Topography
34
Full Corneal Topography
35
Keratoconus
36
Normal
37
iTrace Measures Accommodation Mechanism
38
Very Spherical Accommodation
39
Variations inMapping AccommodativePower in
the Natural Crystalline LensasMeasured
byiTrace
Horizontal Cyl
Sphere
Vertical Cyl
Coma
40
Crystalens Accommodative Arching
Overall Refraction change is 0.5D but Central
Cylinder 2.5 D adds Depth of Field to Enhance
Accommodative Effect
41
MultiFocal 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

42
Multifocal Acrylic IOL

• Alcon ReStor Lens

43
(No Transcript)
44
(No Transcript)
45
(No Transcript)
46
(No Transcript)
47
(No Transcript)
48
(No Transcript)
49
(No Transcript)
50
(No Transcript)
51
(No Transcript)
52
(No Transcript)
53
(No Transcript)
54
Monofocal Acrylic IOL

• Alcon SA-60

55
(No Transcript)
56
(No Transcript)
57
(No Transcript)
58
(No Transcript)
59
(No Transcript)
60
(No Transcript)
61
(No Transcript)
62
(No Transcript)
63
(No Transcript)
64
(No Transcript)
65
(No Transcript)
66
Normal Eye

• 0.5 D Hyperope

67
(No Transcript)
68
(No Transcript)
69
(No Transcript)
70
(No Transcript)
71
(No Transcript)
72
(No Transcript)
73
(No Transcript)
74
(No Transcript)
75
(No Transcript)
76
(No Transcript)
77
(No Transcript)
78
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

79
Thank you for your attention.