gms | German Medical Science

Objective: The objective of this work is to create multielectrode arrays (MEA) for epiretinal stimulation covering an area of about 100 mm². This could be the first step to an epiretinal prosthesis restoring not only the central but also the peripheral field of vision of RP patients.

Methods: Suitable shapes for the electrode arrays were designed under two main aspects, the implantability and the adaption to the curvature of the retina. The MEA is used for epiretinal stimulation and therefore has to be inserted into the eye-ball through a scleral incision, which should not exceed 5 mm in size. As the diameter of the MEA is about 10 mm it needs to be folded or rolled during the insertion and to regain its shape inside the eye without suffering from plastic deformations. When the MEA is attached to the retina it has to adapt to its curvature. To prevent the foil from wrinkling and buckling and to ensure the electrodes have a good contact to the tissue it needs stress-relieving patterns. Several design prototypes based on polyimide were fabricated and tested in various experiments on silicone molds and in cadaver eyes. Polyimide was chosen as a base material due to its mechanical properties. Additionally it can be easily structured with standard photolithographic techniques.

Discussion: With globe- and star-shaped VLARS MEAs we found two designs that comply with the criteria mentioned above. Non-functional prototypes could be implanted successfully in porcine and leporine cadaver eyes and were intact also after explantation.

Acknowledgement: This work was supported by the Jackstaedt Foundation.