Intraocular impedance as a function of the position in the eye, electrode material and electrode size

A critical element of a retinal prosthesis is the electrode assembly, which is placed on the retina. It is via this interface that the nerve cells are stimulated to produce the perception of light. The electrode impedance is an integral part in determining the design of the stimulating electrode and the attached circuit. The impedances involved are not only the tissue impedance but the electrode itself contributes to the impedance. Further on the electrode impedance depends not only the material of the electrode but also the size of the electrode. This paper discusses the results obtained by the intraocular impedance measurements with varying electrode size, electrode material and position of the electrode within the eye.