Download Wavefront by Method of Ray Tracing

Wavefront by Method of Ray
Tracing: Because the Eye is
Not a Telescope
Joe S. Wakil, M.D.
Chairman, Tracey Technologies, LLC
and EyeSys Vision, Inc.
Speaker has a Financial Interest
Founding Technology
Developers:
Vasyl Molebny, DSc
Kiev, Ukraine
Ioannis Pallikaris, MD
Crete, Greece
Canadian & Swedish Governments
Why Dynamic Ray Tracing?
Because… the Eye is NOT a Telescope!
Pupil Size: Effects Refraction (ex. Night
Myopia)
Accommodatio Refraction is NOT a FIXED Number!
n: 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:
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
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 autotracking/capture
-Programmable sampling (256 pts.) in
any pupil up to 8mm
-Open Field Fixation – avoid
instrument myopia and measure
Accommodation
-Corneal Topography integration –
Hartmann-Shack
Wavefront Sensor
H/S Photo of patient with tight eye lid courtesy David Williams
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)
Data Sample Points
Data Sample Points
Multiplying the Number of Sites
Higher Local Density of Sites
Overlay of Two Sets of Site Configuration
Ray Tracing
Objective lens
Input Beam
Retina
Position
sensitive
detector
Eye optics
Ray Tracing
Objective lens
Retina
Position
sensitive
detector
Eye optics
Ray Tracing
Objective lens
Retina
Position
sensitive
detector
Eye optics
Ray Tracing
Objective lens
Retina
Position
sensitive
detector
Eye optics
Ray Tracing
Objective lens
Retina
Position
sensitive
detector
Eye optics
Ray Tracing
Objective lens
Retina
Position
sensitive
detector
Eye optics
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 Analysis
•
•
•
•
•
Conoid of Sturm Evaluation
Contrast Sensitivity Data
Depth of Field Analysis
Individual Data Point PSF’s
Zernike Calculations
Diagnostic Capabilities
• Determine Higher Order Aberrations
• True Point Spread Function
Presentation
• Optical Media Opacity Mapping
• Integrated Corneal Topography
Validation Studies
Three independent studies of
Tracey vs. Manifest Refraction
• Koch et al - 58 eyes
• Slade et al - 42 eyes
• Schalhorn et al - 106 eyes
Results
• Accuracy to manifest
• Reproducibility
<0.12 D
<0.12 D
Post
LASIK
Post
LASIK
Post LASIK
Keratoconu
s
Normal
Normal
Near Fixation
Accommodating IOL
Change due to Accommodation
Far Fixation
Advantages of Ray Tracing
Aberrometry Combined with Corneal
Topography - iTrace
• Robust dynamic range to measure highly
irregular eyes including immediately postop
• Multi-Zone Refraction in seconds to
measure variations in refraction from
normal night myopes to post-op results
saving chair time
• Able to separate Corneal from Lenticular
(internal ocular) sources of aberrations
with EyeSys Corneal Topography
• Improved Diagnostic Wavefront to help in
patient selection including Custom LASIK
and IOL procedures
Conclusion
The Tracey iTrace brings a new
standard of care in completely
assessing vision in terms of quality
of vision (aberrometry) and corneal
topography to progress visual
correction diagnosis and treatments
to its ultimate goals.