Automatic Patient Positioning in Laser Eye Surgery
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Solution Overview
Problem
Current laser-assisted eye surgery systems face challenges in accurately determining the astigmatic axis of a patient's eye, which affects the precision of cataract removal and astigmatism correction procedures, requiring improved methods for positioning the patient and measuring astigmatic power.
Innovation Solution
The system employs an optical coherence tomography (OCT) scanning subsystem to measure the spatial disposition of eye structures, combined with alignment and video subsystems to automatically position the patient relative to the laser eye surgery system, using closed-loop iterative methods to optimize the distance and focus for precise incisions and intraocular lens placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional keratometry using topography principles is used to determine astigmatic axis, then the measurement can be obtained, but the accuracy depends on multiple factors affecting measurements and requires manual positioning
Solution Approach 1:
The system performs automatic patient positioning and astigmatic axis determination without requiring manual intervention. The computer automatically controls the patient support positioning based on video feedback from the objective camera, and automatically determines the astigmatic axis from LED reflections, eliminating the need for manual positioning and measurement by surgeons.
Solution Approach 2:
The system uses a closed-loop feedback mechanism where the video subsystem continuously monitors the position of the patient's eye relative to the objective camera, and the computer automatically adjusts the patient support positioning to maximize the size of the eye in the video image, ensuring optimal positioning for accurate measurement.
2Ease of operation
If manual positioning methods are used, then the patient can be positioned relative to the system, but the accuracy and efficiency of positioning is reduced
Solution Approach 1:
The system automatically positions the patient's eye relative to the objective camera by controlling the patient support movement based on video feedback. The computer calculates the optimal position by analyzing the size of the eye in the video image and automatically adjusts the positioning, eliminating manual positioning efforts and improving both ease of operation and measurement precision.
Solution Approach 2:
The system replaces manual mechanical positioning with an automated optical-mechanical system. Instead of manual adjustment of patient position, the system uses video imaging to detect eye position and automatically controls the patient support mechanism to achieve optimal positioning, substituting human operation with automated sensor-based control.
3Measurement precision
If the system requires determining astigmatic power and axis during preparation, then accurate surgery can be performed, but the time required for positioning and measurement increases
Solution Approach 1:
The system performs patient positioning and astigmatic axis determination as preliminary actions before the actual laser surgery begins. By automatically completing these preparatory steps using video feedback and automated analysis of LED reflections, the system reduces the time required for preparation while ensuring accurate measurements are obtained before surgery commences.
Solution Approach 2:
The computer automatically determines the astigmatic power and axis by analyzing reflections from LEDs arranged in concentric circles, without requiring manual measurement procedures. This automated self-service approach to measurement reduces the time surgeons need to spend on positioning and measurement tasks while maintaining high measurement precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the accuracy and efficiency of cataract removal and astigmatism correction by providing precise positioning and measurement of the astigmatic axis, reducing patient discomfort and improving surgical outcomes.
Implementation Method 1
an optical coherence tomography (OCT) scanning subsystem to measure the spatial disposition of external and internal structures of the eye
Implementation Method 2
a laser to form precise incisions in the cornea, in the lens capsule, and/or in the crystalline lens nucleus
Implementation Method 3
an alignment subsystem, which can include a video subsystem that can be used to, for example, provide images of the eye during docking of the eye to the laser eye surgery system
Data Source
AI summary
A laser eye surgery system produces a treatment beam that includes a plurality of laser pulses. An optical coherence tomography (OCT) subsystem produces a source beam used to locate one or more structures of an eye. The OCT subsystem is used to sense the distance between a camera objective on the underside of the laser eye surgery system and the patient's eye. Control electronics compare the sensed distance with a pre-determined target distance, and reposition a movable patient support toward or away the camera objective until the sensed distance is at the pre-determined target distance. A subsequent measurement dependent upon the spacing between the camera objective and the patient's eye is performed, such as determining the astigmatic axis by observing the reflection of a plurality of point source LEDs arranged in concentric rings off the eye.