Retinal Prosthesis Stimulation Timing and Current Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
During electrical stimulation of the retina, subjects experience discomfort due to high brightness and interactions among multiple electrodes, leading to inconsistent contrast and brightness in presented images or patterns.
Innovation Solution
A method involving the assignment of image pixels to electrodes based on temporal stimulation patterns, edge detection, current clipping, scaling, and adjusting electrode currents to minimize discomfort and ensure consistent stimulation, along with the use of a return electrode to optimize comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high brightness stimulation is applied to maintain a bright percept, then the brightness perception is improved, but patient discomfort increases
Solution Approach 1:
The image is divided into multiple timing groups where bright pixels are distributed across different time slots rather than all being stimulated simultaneously. This segmentation in time allows the system to maintain bright perception while avoiding excessive total current that causes discomfort
Solution Approach 2:
The system dynamically adjusts stimulation parameters including timing group assignment and current amplitude based on the spatial and temporal distribution of bright pixels. This dynamic adaptation allows optimization of brightness perception while staying within comfort limits
2Productivity
If multiple electrodes stimulate at the same time to present a pattern, then the pattern presentation is improved, but electrode interactions create unintended brightness and discomfort
Solution Approach 1:
Electrodes are organized into timing groups that are activated in sequence rather than all at once. This temporal segmentation reduces direct interactions between simultaneously active electrodes while maintaining the ability to present complex patterns
Solution Approach 2:
The system performs preliminary analysis of the image to identify bright pixel locations and distributions before assigning electrodes to timing groups. This allows optimization of electrode activation sequences to minimize interactions while preserving pattern integrity
3Illumination intensity
If all bright pixels are stimulated simultaneously to maintain image fidelity, then the image brightness is improved, but the total current exceeds discomfort limits
Solution Approach 1:
Bright pixels are distributed across multiple timing groups in sequence. Each timing group contains a subset of bright pixels that can be stimulated without exceeding current limits, while the cumulative effect across all timing groups maintains overall image brightness
Solution Approach 2:
The stimulation follows a periodic temporal pattern where different timing groups are activated in sequence. This periodic activation allows the system to deliver the necessary total current over time while keeping instantaneous current within comfortable limits
Data Source
AI summary
Techniques and functional electrical stimulation to eliminate discomfort during electrical stimulation of the retina are provided. According to a first technique, discomfort is eliminated through control of timing group assignment. According to a second technique, discomfort is eliminated through an edge detection method. According to a third technique, brightness clipping is used to eliminate discomfort. According to a fourth technique, direct reduction of current is obtained by scaling it down by a factor which is dependent on the sum of current in all electrodes. According to a fifth technique, the current being fed to each electrode is adjusted, by dividing it by a weighted sum of currents fed to the surrounding electrodes. According to a sixth technique, a method based on the current summation effect is used. According to a seventh technique, a large return electrode is used. According to an eighth technique, the return electrode is used for a pseudo-multi-polar stimulation.