Visual Prosthesis Color Perception via Electrode Stimulation
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Solution Overview
Problem
Current visual prostheses are unable to effectively induce color perception in individuals with outer retinal degenerative diseases, such as retinitis pigmentosa, due to the inability to stimulate cone cells individually, which are responsible for color vision.
Innovation Solution
A method and system that determine and store stimulation patterns of current, frequency, pulse width, and inter-pulse gap to induce color perception by testing these patterns on subjects and using the stored relationships to process video data and stimulate visual neurons accordingly, allowing for the perception of colors through an array of electrodes implanted in the eye.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical stimulation is applied to retinal cells to produce phosphenes, then visual perception is restored, but color perception cannot be induced because cone cells cannot be stimulated individually
Solution Approach 1:
The electrode array is divided into multiple independently controllable electrodes that can stimulate different groups of cone cells (L, M, and S cones) separately. By segmenting the stimulation targets and using multiple electrodes with different spectral sensitivities, the system can selectively activate specific cone types to generate color perception, resolving the limitation of unable to stimulate individual cone cells.
2Reliability
If multiple stimulation parameters (current, frequency, pulse width, inter-pulse gap) are varied to induce color perception, then color vision can be restored, but the system complexity and calibration difficulty increase
Solution Approach 1:
The system utilizes multiple stimulation parameters (current amplitude, frequency, pulse width, and inter-pulse gap) that can be independently adjusted to optimize color perception. By changing these parameters across different electrodes, the system can elicit different color perceptions from the same electrode array, enabling color vision restoration while managing complexity through systematic parameter optimization.
3Loss of information
If electrical current is passed through electrodes to stimulate visual neurons, then artificial vision is produced, but the ability to distinguish colors is lost due to non-specific stimulation
Solution Approach 1:
Different electrodes in the array are designed with different spectral qualities to match the sensitivity profiles of L-cones (red), M-cones (green), and S-cones (blue). By assigning specific spectral characteristics to different electrodes and stimulating them selectively, the system preserves color information and enables accurate color discrimination, transforming uniform electrical stimulation into spectrally-specific activation.
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 enables blind subjects to perceive different colors by mapping video input data to specific stimulation patterns, with results showing consistent color perception in a significant percentage of subjects, particularly white and yellow, and demonstrating the effectiveness of the method in restoring color vision.
Implementation Method 1
Neural tissue can be artificially stimulated and activated by prosthetic devices that pass pulses of electrical current through electrodes on such a device. The passage of current causes changes in electrical potentials across visual neuronal membranes, which can initiate visual neuron action potentials
Data Source
AI summary
The present invention is an improved method of electrically stimulating percepts in a patient with a visual prosthesis, to induce the perception of color. In particular, the present invention is a method of inducing the perception of color by determining experimentally which patterns induce which colors, storing that information and using the stored information to induce the perception of color according to video input data and the stored color information.