Feasibility of extraocular stimulation for a retinal prosthesis

Area of Science:

• Ophthalmology
• Neuroscience
• Biomedical Engineering

Background:

• A novel approach for retinal prosthesis development using extraocular stimulation is presented.
• Disc electrodes are utilized for stimulating the eye externally.

Purpose of the Study:

• To assess the feasibility of extraocular stimulation for retinal prostheses.
• To investigate the potential of adapting the Nucleus 24 auditory brainstem implant (ABI) for this purpose.

Main Methods:

• Experiments were conducted on anesthetized cats (n=6).
• Electrodes were placed on the posterior scleral surface of the eye.
• Cortical potentials were recorded from the primary visual cortex following electrical stimulation.

Main Results:

• Extraocular electrodes reliably evoked visual cortex responses.
• Low threshold currents (<100 microA) were sufficient for eliciting responses.
• The Nucleus 24 ABI demonstrated effectiveness for retinal stimulation.

Conclusions:

• Electrical stimulation of the retina is achievable with extraocular electrodes.
• Low threshold currents, comparable to epiretinal implants, were observed.
• Prototype electrodes and the ABI showed efficacy in retinal stimulation.