Biochemically Modified Surfaces as a Fixation Concept for Epiretinal Stimulator Arrays: First Results of in-vivo Implantation in Rabbits

Abstract

Purpose: : To develop an alternative fixation procedure for epiretinal stimulators as an alternative to the conventional fixation using retinal tacks.

Methods: : Polyimide microstructures were coated with different protein configurations by immobilizing laminin peptide composites onto the surface. Implantation was performed in rabbits including vitrectomy and the positioning of the structures onto the retinal surface. After an observation period of three months the eyes were enucleated for histopathological examination.

Results: : Using one additional retinal tack at one edge of the microstructures led to tight connection of the entire dummy microstructures at the posterior pole of the rabbits’ eyes. In cases where the positioning was performed without an additional tack fixation the dummy structures did not remain at the posterior pole. In one case with additional tack fixation the microstructure showed tight contact although the tack was not detectable at the fixation site during the follow-up examinations.

Conclusions: : Our first results of in-vivo implantation show that basically a tight contact of the modified microstructures with the retinal surface could be achieved. However, the necessity of a temporary additional tack fixation implies that a certain period of time needs to be bypassed until the biochemical fixation takes effect completely. Moreover, experiments in animal models which a more similar to the human eye could be helpful to investigate the relevance of this problem while the design of an entirely implanted prosthesis including the transscleral fixation of the receiver and the built-in stress of the stimulator cable may provide a certain temporary fixation.

Keywords: retinal degenerations: hereditary • vitreoretinal surgery • Muller cells