Azimuthal Eye Orientation via Polar Image Correlation
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Solution Overview
Problem
Current eye surgery systems face challenges in accurately determining the azimuthal orientation of a patient's eye during cataract operations, especially when the eye moves, as existing methods are either unreliable or require marking the eye.
Innovation Solution
An eye surgery apparatus with imaging optics and a computer unit that displays observation and reference images in polar coordinates, allowing for precise determination of the azimuthal orientation by shifting image strips and calculating the center of the limbus or iris, enabling accurate alignment without the need for eye markings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the patient's eye moves during surgery, then the image of the object area becomes non-stationary, but marking the eye to indicate azimuthal orientation increases the complexity of the surgical procedure
Solution Approach 1:
The patent creates a digital reference image (copy) of the patient's eye taken before surgery, which is then overlaid and aligned with the real-time image during surgery. This digital copy serves as a marker-free reference for determining azimuthal orientation, eliminating the need for physical eye markings while maintaining accuracy.
Solution Approach 2:
The patent replaces the mechanical approach of physically marking the eye with a digital image processing system. The computer unit performs image correlation and polar coordinate transformation to calculate azimuthal orientation automatically, substituting mechanical marking with computational analysis.
2Measurement precision
If conventional image display methods are used, then the surgeon can observe the eye, but cannot accurately determine azimuthal orientation when the eye moves
Solution Approach 1:
The patent transforms the image coordinates from Cartesian to polar coordinates, with the origin at the calculated center of the limbus or iris. This dimensional transformation enables accurate azimuthal orientation measurement by expressing pixel positions in terms of radial distance and angular position, naturally separating the orientation information from the image data.
Solution Approach 2:
The patent changes the coordinate system parameters from Cartesian (x, y) to polar (r, θ), where θ represents the azimuthal angle. This parameter change allows direct extraction of orientation information and enables the system to track eye rotation by comparing the angular positions of corresponding features in the reference and current images.
3Measurement precision
If the center of the limbus or iris is not accurately calculated, then polar coordinate transformation cannot be performed, but calculating the center adds processing complexity
Solution Approach 1:
The patent performs the center calculation of the limbus or iris as a preliminary step before the main image correlation and polar coordinate transformation. By pre-calculating and storing the center position from the reference image, the system avoids repeated calculations during real-time surgery, reducing processing time while maintaining accuracy.
Data Source
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AI summary
The invention relates to an eye surgery apparatus (1) having imaging optics (14, 26, 27) for generating an observation image (40) of a patient's eye (16). The eye surgery apparatus (1) has a device (36) for determining the azimuthal orientation of a patient's eye (16) with respect to a reference (3) which is fixed with respect to the patient's eye (16). The device (36) contains a visual display device (34) for simultaneously displaying a section (92) of an observation image (40) of the patient's eye (16), which is captured by the imaging optics (14, 26, 27) and contains at least one segment of the limbus or of the iris, said section being composed of pixels, and a reference image of the patient's eye (16), which is composed of pixels (106) and contains this segment of the limbus or of the iris. The device (36) has an input interface (28) which makes it possible for an observer to move the displayed section (92) of the captured observation image (40) of the patient's eye (16) relative to the displayed section (94) of the reference image (80). The device (36) comprises a measuring system which can be used to determine the azimuthal orientation of the observation image and of the reference image, which orientation is changed during the relative movement. The device (36) has a computer unit (5) having a computer program for calculating the center (46) of the limbus (44) and/or of the iris (43) of the observation image (40) of the patient's eye (16), as captured by the imaging optics (14, 26, 27), and of the reference image (80). The visual display device (34) displays the pixels (102) of the observation image (40) of the patient's eye (16), as captured by the imaging optics (14, 26, 27), with polar coordinates in a polar coordinate system (96), the center (46) of which coincides with the calculated center of the circular structure (44) of the limbus and/or of the iris (43) of the patient's eye (16). It displays the pixels (106) of the reference image (80) of the patient's eye (16) with polar coordinates in a polar coordinate system (98), the center (84) of which corresponds to the calculated center of the circular structure (94) of the limbus of the patient's eye (16) on which the reference image (80) is based.