Histologic Analysis of a Retinal Prosthesis Implant in an Animal Model

Abstract

Abstract: : Purpose: To investigate the biocompatibility of a retinal prosthesis in rabbit eyes. Methods: An experimental retinal prosthesis made of polyimide with dummy microelectrodes on the surface was developed and implanted into the epiretinal and subretinal spaces in rabbit eyes after vitrectomy. One month after, the eyes were studied histologically. The retina was embedded in Epon mixture and sectioned. The samples were subjected to immunohistochemistry for glial fibrillary acidic protein (GFAP) and deoxynucleotidyl-transferase nick-end labelingTUNELin retinal neuronal cells. Transmission electron microscopy was also performed. Results: The retinal architecture was well preserved after 1 month in eyes with an epiretinal implant. Neither the number of GFAP-positive cells nor TUNEL staining increased in those eyes. However, vacuolated regions were observed in the outer retinal layer under electron microscopy. In eyes with a subretinal implant, the layered structure of the retina was highly disturbed and the retina was thinned. GFAP-positive cells and TUNEL-positive cells were extensively distributed throughout the region of the implant. Conclusions: We confirmed the biocompatibility of the epiretinal prosthesis in rabbit eyes. Retinal vacuolated changes may result from mechanical pressure by the prosthesis. The subretinal implant caused extensive retinal damage.

Keywords: retina • apoptosis/cell death • retinal degenerations: hereditary