Retinal Prosthesis Stimulation for Image Persistence

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Solution Overview

Problem

Current retinal prostheses face challenges in achieving image persistence due to retinal desensitization from continuous stimulation, leading to reduced resolution and inability to mimic natural eye movements, which are essential for perceiving constant images.

Innovation Solution

A method involving periodic interruptions of electrical stimulation to individual electrodes in a retinal prosthesis, with programmable timing to maintain retinal sensitivity, utilizing a secondary inductive coil and molded body for mechanical stability, and a pseudorandom pattern to minimize user perception of interruptions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If continuous electrical stimulation is applied to retinal neurons, then initial visual perception is achieved, but retinal desensitization occurs leading to reduced persistence and resolution

Engineering Contradiction:

Improvevisual perception reliabilityVSAvoidimage persistence duration

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent applies periodic interruption of electrical stimulation to retinal neurons. Instead of continuous stimulation, the system delivers stimulation in periodic intervals with brief interruptions (e.g., 10-100 milliseconds off periods between on periods). This periodic action prevents retinal desensitization while maintaining visual perception, thereby resolving the contradiction between achieving reliable visual perception and maintaining long-duration image persistence.

Inventive Principle:

Principle #19Periodic action

2Illumination intensity

If stimulation parameters are increased to maintain image persistence, then brightness and visibility improve, but retinal desensitization accelerates reducing persistence

Engineering Contradiction:

Improvephosphene brightnessVSAvoidimage persistence duration

Core Design Contradiction:

Illumination intensityVSDuration of action of stationary object

Solution Approach 1:

The system uses periodic stimulation with controlled duty cycles to maintain phosphene brightness without causing rapid desensitization. By interrupting stimulation periodically rather than continuously, the retinal neurons recover sensitivity between pulses, allowing sustained bright phosphene perception without accelerating desensitization.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent dynamically adjusts stimulation parameters including amplitude, pulse width, and duty cycle based on detected retinal response and persistence requirements. By changing these parameters periodically or adaptively, the system maintains optimal brightness while preventing desensitization, resolving the contradiction between intensity and persistence duration.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If high-resolution electrode arrays are used to improve visual resolution, then more retinal neurons are stimulated, but retinal desensitization occurs more rapidly across the array

Engineering Contradiction:

Improvevisual resolutionVSAvoidimage persistence duration

Core Design Contradiction:

Measurement precisionVSDuration of action of stationary object

Solution Approach 1:

The patent divides the retinal stimulation into segmented temporal patterns rather than simultaneous continuous stimulation across all electrodes. By segmenting the stimulation in time (periodic interruption) and potentially in space (scanning patterns across electrode arrays), the system maintains high resolution while allowing different retinal regions to recover between stimulation phases, preventing rapid array-wide desensitization.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Periodic interruption of stimulation is applied across the electrode array to maintain sensitivity in all stimulated regions. This temporal segmentation allows neurons across the high-resolution array to recover periodically, sustaining resolution without rapid desensitization.

Inventive Principle:

Principle #19Periodic action

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

Restores retinal sensitivity and improves image persistence by interrupting stimulation for milliseconds, allowing for more natural perception of images without noticeable disruptions, enhancing the resolution and effectiveness of visual prostheses.

Implementation Method 1

a secondary inductive coil and molded body for mechanical stability

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The passage of current causes changes in electrical potentials across retinal neuronal cell membranes, which can initiate retinal neuronal action potentials

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS9186507B2Neural stimulation for increased persistence

Publication Date: 2015.11.17 CORTIGENT INC

AI summary

The present invention is a method of improving the persistence of electrical neural stimulation, and specifically a method of improving the persistence of an image supplied to a retina, or visual cortex, through a visual prosthesis. A continuously stimulated retina, or other neural tissue, will desensitize after a time period in the range of 20 to 150 seconds. However, an interruption of the stimulation on the order of a few milliseconds will restore the retinal sensitivity without the user perceiving the interruption, or with the user barely perceiving the interruption.