Abstract
Purpose :
Retinitis pigmentosa is a leading cause of blindness in industrialized countries, for which there is still no established prevention, treatment or cure. In the past decade, retinal prostheses emerged as promising technology to restore vision. On the other hand, optic nerve stimulation was proposed as an attractive alternative to retinal prostheses, by acting directly on the axons of the ganglion cells and avoid exclusion criteria of retinal implants.
Our goal is to develop a novel self-opening intraneural electrode array (OpticSELINE) based on a 3D concentric bipolar configuration, where a local return electrode surrounds each stimulating electrode. This solution was chosen to achieve higher stimulation resolution by confining the electrical stimulation.
Methods :
Intraneural electrode arrays were manufactured using wafer-scale processes. Sixteen concentric bipolar electrodes were fabricated with a 3D multilayer process in platinum / platinum black over a polyimide flexible substrate. Electrochemical characterization was performed before and after platinum black coating.
In parallel, a hybrid FEM / NEURON simulation of the optic nerve was performed to evaluate the performance of the concentric bipolar electrode configuration. To performFor in-vivo experimentsvalidation, the OpticSELINE was implanted in the optic nerve of anesthetized rabbits, while the electrical activity of the contra-lateral visual cortex was recorded.
Results :
The electrochemical study showed that platinum black reduces the impedance module below 10 kOhm and the charge storage capacity was nearly 5 times higher compared to bare platinum for actives sites of 0.0013 mm2. The hybrid simulation showed that the area of the optic nerve activated by a current pulse is greatly reduced using concentric bipolar electrodes compared to standard monopolar configuration. Preliminary in-vivo results show that the amplitude of electrical evoked-potentials is lower when stimulation is applied with the local return configuration with respect to the monopolar one.
Conclusions :
This technology has the potential to allow stable and selective stimulation of the optic nerve during chronic implantations. The advancement will improve the use of the OpticSELINE as visual prosthesis for blind patients and as tool to further investigate the effect of the electrical stimulation in the visual system.
This is a 2021 ARVO Annual Meeting abstract.