Patient-Specific Visual Defect Simulation via fMRI Retinotopic Mapping
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Solution Overview
Problem
Current visual defect simulators fail to provide patient-specific, realistic simulations of potential visual field defects resulting from medical procedures, as they do not account for the unique retinotopic organization of each patient's visual cortex and the effects of proposed treatments.
Innovation Solution
A system utilizing fMRI to create a functional field map of a patient's visual cortex, which is then used to simulate potential visual defects through a Visual Defect Simulator (VDS) that dynamically adjusts images to retinopically fix the predicted defects in the patient's field of view, allowing for a first-hand experience of the anticipated visual impairment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional visual defect simulators are used, then a general simulation of visual defects can be provided, but the simulation is not patient-specific and does not account for individual retinotopic organization
Solution Approach 1:
The system performs preliminary fMRI scanning and retinotopic mapping before surgery to establish patient-specific visual cortex organization. This advance preparation allows the simulation to be customized to each patient's unique neural architecture, resolving the contradiction between personalization and complexity by doing the complex work beforehand rather than during simulation.
Solution Approach 2:
The system creates a computational copy of the patient's retinotopic map from fMRI data, which can then be used to simulate visual defects without requiring the physical presence of the patient's brain during simulation. This copying approach enables patient-specific customization while keeping the actual simulation system relatively simple and reusable across multiple patients.
2Reliability
If invasive surgical procedures are performed to treat brain pathologies, then therapeutic benefit can be achieved, but visual field defects may occur as side effects
Solution Approach 1:
The system applies preliminary anti-action by simulating potential visual defects before surgery occurs, allowing patients to mentally prepare and compensate for anticipated deficits. This pre-surgical simulation does not prevent the defects but mitigates their psychological and functional impact by providing advance warning and adaptation opportunities.
Solution Approach 2:
The system provides feedback to both patients and physicians about predicted visual outcomes before surgical decisions are made. This feedback loop allows for informed consent and potential modification of surgical plans to minimize visual field defects while maintaining treatment efficacy.
3Measurement precision
If retinotopic mapping is performed for each patient using fMRI, then accurate patient-specific simulation can be achieved, but the process requires complex imaging procedures and time
Solution Approach 1:
The system uses standard fMRI retinotopic mapping protocols that cover the entire visual cortex, which may be more extensive than strictly necessary for some patients. This excessive action ensures complete coverage and accuracy for all patients, with the option to use only the relevant portions of the mapped data for each individual case, thus maintaining high precision while managing time requirements.
4Ease of operation
If the simulation dynamically tracks eye movements to maintain retinotopic fixation, then realistic visual defect experience is provided, but the system requires real-time eye tracking and rapid image adjustment
Solution Approach 1:
The system introduces an intermediary computational layer that translates eye tracking data into retinotopic coordinate transformations and applies them to the visual simulation. This intermediary processing layer decouples the complexity of real-time eye tracking from the final display, allowing realistic simulation while managing system complexity through modular architecture.
Data Source
AI summary
A visual defect simulation system receives a functional field map produced by an MRI system that relates locations in a patient's brain to locations in the patient's field of view. Planned medical operations are indicated at locations in the patient's brain and any resulting vision loss is simulated with a revised functional field map. A scene is displayed and an impairment overlay is produced from the revised functional field map that blocks the scene at locations corresponding to simulated vision loss. The overlay is translated over the scene in response to viewer eye movements detected by a vision-tracking system to present a real-time simulation of the resulting vision loss.