System and method for selective retinal stimulation

A method for electrically stimulating a retina of an eye to induce visual perception, said method comprising the steps of:

• placing an electrode adjacent a retinal ganglion cell (RGC) layer, the RGC layer including at least one ganglion cell having an axon, at least a portion of the axon having an approximately 90° bending region;
• and
• selectively applying a biphasic asymmetrical waveform to a portion of the axon, said biphasic asymmetrical waveform including a pre-pulse phase and a stimulation-pulse phase;
• said pre-pulse phase having a first polarity, a first amplitude and a first duration, said first amplitude and said first duration together defining a pre-pulse charge having a first magnitude;
• said stimulation-pulse phase having a second polarity opposite said first polarity, a second amplitude, and a second duration less than said first duration, said second amplitude and said second duration together defining a stimulation charge having a second magnitude;
• wherein application of said pre-pulse phase and said stimulation-pulse phase effects a change in excitability of the at least one ganglion cell and induces visual perception, respectively.

A method for electrically stimulating a retina of an eye to induce visual perception, said method comprising the steps of:

• placing an electrode adjacent an approximately 90° bending region of an axon of at least one ganglion cell, the at least one ganglion cell comprising a RGC layer;
• and
• selectively applying a biphasic asymmetrical waveform to the axon, said biphasic asymmetrical waveform including a pre-pulse phase and a stimulation-pulse phase;
• said pre-pulse phase having a first polarity, a first amplitude and a first duration, said first amplitude and said first duration together defining a pre-pulse charge having a first magnitude;
• said stimulation-pulse phase being applied after said pre-pulse phase and having a second polarity opposite said first polarity, a second amplitude, and a second duration less than said first duration, said second amplitude and said second duration together defining a stimulation charge having a second magnitude;
• wherein a cathodic pre-pulse phase and an anodic stimulation-pulse phase induce perception of a circular shape, and an anodic pre-pulse phase and a cathodic stimulation-pulse phase induce perception of an elongate shape.

A method for electrically stimulating a retina of an eye to induce visual perception, said method comprising the steps of:

• placing an electrode adjacent an approximately 90° bending region of an axon of at least one ganglion cell, the at least one ganglion cell comprising a RGC layer;
• and
• selectively applying a biphasic charge-balanced asymmetrical waveform to the axon, said biphasic charge-balanced asymmetrical waveform including a pre-pulse phase and a stimulation-pulse phase;
• said pre-pulse phase having a first polarity, a first amplitude and a first duration, said first amplitude and said first duration together defining a pre-pulse charge having a first magnitude;
• said stimulation-pulse phase being applied after said pre-pulse phase and having a second polarity opposite said first polarity, a second amplitude, and a second duration less than said first duration, said second amplitude and said second duration together defining a stimulation charge having a second magnitude;
• wherein a cathodic pre-pulse phase and an anodic stimulation-pulse phase induce perception of a circular shape, and an anodic pre-pulse phase and a cathodic stimulation-pulse phase induce perception of an elongate shape;
• wherein said first duration of said pre-pulse phase to said second duration of said stimulation-pulse phase is approximately 10:1.