Purkinje Image Tracking for Laser Eye Positioning
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Solution Overview
Problem
Current laser treatment methods for addressing opacities and scars on the cornea are invasive and require precise positioning of treatment apparatuses, which is challenging due to the need for accurate determination of the eye's position relative to the optical axis, especially when pathological areas are on the axis of vision.
Innovation Solution
A method involving a treatment apparatus that captures a Purkinje image using an optical capturing device to determine the eye's current position relative to the optical axis, allowing for automatic eye tracking and position correction, thereby ensuring accurate and efficient treatment by aligning the eye's position with a target position using a beam deflection device with a neutral pose.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If laser treatment methods are used to address corneal opacities and scars, then sight improvement is achieved, but the treatment becomes invasive and requires precise positioning which is difficult to maintain
Solution Approach 1:
The patent replaces complex mechanical positioning systems with an optical-based Purkinje image tracking system. By using the optical properties of the cornea to generate and track Purkinje images, the system achieves precise eye position determination without relying on complex mechanical sensors or actuators, thus improving reliability while reducing mechanical complexity
Solution Approach 2:
The patent creates an optical copy (Purkinje image) of the illumination pattern reflected from the cornea surface. This optical copy serves as a reliable marker for tracking eye position and orientation, enabling accurate position determination through image processing rather than direct mechanical measurement
2Productivity
If the treatment apparatus is positioned precisely to treat only the altered corneal area, then treatment efficiency is improved, but the positioning accuracy becomes more critical and difficult to maintain
Solution Approach 1:
The patent implements continuous tracking of the Purkinje image throughout the treatment process. By continuously monitoring the position and movement of the Purkinje image, the system maintains accurate eye positioning without interruption, ensuring that the laser beam remains precisely targeted on the altered corneal area throughout the entire treatment duration
Solution Approach 2:
The patent employs a feedback mechanism where the captured Purkinje image is continuously compared to reference positions, and control signals are generated to correct any deviations. This closed-loop feedback system automatically adjusts the beam deflection device to maintain precise eye positioning, improving measurement precision through active correction
3Adaptability or versatility
If the beam deflection device is used to rotate the laser beam to the cornea, then treatment flexibility is improved, but the neutral pose alignment becomes more challenging to maintain
Solution Approach 1:
The patent performs preliminary determination of the target position of the eye relative to the optical axis before treatment begins. By calculating the required beam deflection angles in advance based on the desired treatment location, the system can pre-position the beam deflection device, reducing the complexity of maintaining neutral pose alignment during treatment
Solution Approach 2:
The patent makes the optical axis dynamic by allowing it to adapt its position based on the determined eye position and target treatment location. The optical axis can be repositioned relative to the cornea as needed, enabling flexible beam positioning while maintaining precise alignment through active control rather than fixed mechanical constraints
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
Enables reliable and efficient treatment by accurately determining and correcting the eye's position, reducing treatment duration and minimizing invasiveness by using Purkinje images for precise alignment and correction during the treatment process.
Implementation Method 1
A Purkinje image, which is associated with a cornea of the eye, is captured by means of an optical capturing device of the treatment apparatus during the approaching procedure
Implementation Method 2
A Purkinje image, which is associated with a cornea of the eye, is captured by means of an optical capturing device of the treatment apparatus during the approaching procedure
Data Source
AI summary
A method is disclosed for determining a current position of an eye of a patient relative to an optical axis of a laser beam of a treatment apparatus. The method includes presetting a criterion characterizing the eye, determining a first target position of the eye relative to the optical axis, positioning a patient interface in a preset area in front of the optical axis, illuminating the eye during an approaching procedure of the patient interface to the eye, capturing a Purkinje image, which is associated with a cornea of the eye, by means of an optical capturing device during the approaching procedure, comparing the captured Purkinje image to the optical axis and determining the current position of the eye depending thereon, comparing the current position to the target position and with a deviation, outputting a control signal to a control device of the treatment apparatus.