Founding Technology Developers: Vasyl Molebny, dsc

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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!

  • 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

  • Brain image processing

  • 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


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

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

Refractive Error Measurements

Retinal Spot Diagram/Point Spread Function

Data Displays

Baylor Clinical Study (100 eyes) by Doug Koch, MD

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 iTrace

Normal Eye

Irregular Eye


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

  • 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

Multifocal Acrylic IOL

  • Alcon ReStor Lens

Monofocal Acrylic IOL

  • Alcon SA-60

Normal Eye

  • +0.5 D Hyperope

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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