Corneal Cross-Linking Illumination Tracking for Eye Movement Compensation
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Solution Overview
Problem
Cross-linking treatments for conditions like keratoconus and post-LASIK ectasia face challenges due to eye movement during the procedure, making precise application of photoactivating light difficult, which can lead to undesired structural changes in the cornea.
Innovation Solution
An active eye tracking system with a spatial light modulator and controller adjusts the projection of pixelated illumination patterns in response to eye movements, using a combination of DMD and electromechanical X-Y motion to ensure precise delivery of photoactivating light to specified corneal areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a smaller pixelated illumination pattern is projected onto the cornea to allow greater range of positional adjustments for eye tracking, then the range of positional adjustments is improved, but the minimum resolvable spatial feature degrades and pixelation artifacts increase
Solution Approach 1:
The system dynamically adjusts the size of the pixelated illumination pattern based on eye movement magnitude. During treatment, if eye movement exceeds a threshold, the system reduces the illumination pattern size to expand the adjustable range, while maintaining adequate resolution through real-time recalibration of the spatial light modulator parameters.
2Ease of operation
If the size of pixelated illumination is decreased to increase adjustment range, then greater positional flexibility is achieved, but pixelation artifacts are produced and resolution degrades
Solution Approach 1:
The system employs periodic dithering of the pixelated illumination pattern, rapidly alternating between adjacent pixels at frequencies above the visual threshold. This temporal modulation effectively smooths out pixelation artifacts while maintaining the reduced spatial pattern size needed for greater positional adjustment range.
3Manufacturing precision
If photoactivating light is applied precisely to specified corneal areas, then treatment precision is improved, but the procedure becomes more complex and time-consuming due to eye movement compensation requirements
Solution Approach 1:
The system implements real-time feedback through an eye tracking system that continuously monitors corneal position and gaze angle. The tracked eye movement parameters are fed back to the controller, which dynamically adjusts the spatial light modulator to compensate for movement, maintaining precise light delivery without requiring complex manual intervention.
Solution Approach 2:
The system replaces complex mechanical adjustment mechanisms with a digitally controlled spatial light modulator. Instead of physically moving optical components to track eye movement, the system uses electronic control of pixel activation patterns to maintain precise illumination on the moving corneal target, significantly simplifying the mechanical complexity.
4Reliability
If eye tracking is implemented to compensate for eye movement, then treatment accuracy is improved, but the system complexity and procedural time increase
Solution Approach 1:
The system performs preliminary calibration of the eye tracking system before the actual cross-linking treatment begins. During this calibration phase, the system maps the relationship between eye movement and required illumination adjustments, storing these parameters for rapid retrieval during treatment. This preliminary setup enables real-time compensation without adding significant time during the critical treatment phase.
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
The system effectively stabilizes the cornea by minimizing pixelation artifacts and achieving uniform cross-linking, even with eye movements, enhancing treatment accuracy and reducing procedural time.
Implementation Method 1
a spatial light modulator configured to receive the photoactivating light from the light source and provide a pixelated illumination with the photoactivating light
Implementation Method 2
to generate cross-linking activity in a treatment area by photoactivating a cross-linking agent applied to the treatment area
Data Source
AI summary
A corneal cross-linking system includes a light source configured to emit a photoactivating light. The system includes a spatial light modulator configured to receive the photoactivating light from the light source and provide a pixelated illumination. The spatial light modulator defines a maximum area for the pixelated illumination. The system includes a controller configured to cause the spatial light modulator to project a first pixelated illumination onto the cornea to photoactivate a cross-linking agent applied to a treatment area. The first pixelated illumination has an area that is smaller than the maximum area defined by the spatial light modulator. The controller is configured to determine movement of the cornea. In response to the movement, the controller controls the spatial light modulator to project a second pixelated illumination to the treatment area based on a translation and/or transformation of the first pixelated illumination to continue photoactivating the cross-linking agent.