Effects of different three-dimensional electrodes on epiretinal electrical stimulation by modeling analysis

Area of Science:

• Biomedical Engineering
• Neuroscience
• Computational Modeling

Background:

• Epiretinal prostheses restore vision in patients with retinal degenerative diseases.
• Electrode design is critical for epiretinal prosthesis performance.
• Investigating 3-D electrode effects on retinal ganglion cell (RGC) excitation is key.

Purpose of the Study:

• To computationally analyze the impact of different 3-D electrode designs on RGC excitation.
• To evaluate electrode performance metrics including threshold current, charge density, and activated area.

Main Methods:

• Developed 3-D finite element models of retinal electrical stimulation (COMSOL).
• Simulated epiretinal electrical stimulation using disk and non-planar electrodes.
• Utilized a multi-RGC model (NEURON) to assess RGC excitability.

Main Results:

• Threshold current and charge density increased linearly with electrode-retina distance.
• Increasing disk electrode diameter raised threshold current but lowered charge density.
• Non-planar electrodes, particularly concave ones, demonstrated superior stimulation localization and safety compared to convex designs.

Conclusions:

• 3-D electrode design significantly influences epiretinal stimulation efficacy.
• Computational modeling (COMSOL and NEURON) efficiently evaluates electrode performance.
• Concave hemispherical electrodes are promising for optimizing epiretinal prostheses due to enhanced safety and localization.