Experimental Implantation and long–term testing of an Intraocular Vision Aid in rabbits

Abstract

Abstract: : Purpose: The development of an Intraocular Vision Aid (IoVA) aims to provide artificial vision in severely traumatized eyes with irreversible opacification and shrinkage of the anterior segment. However the neuroretinal function has to be preserved. The principle of the IoVA is based on a silicone–encapsulated LED array implanted in the ciliary sulcus to bridge the opaque cornea and to allow for artificial light stimulation of the retina. A high–dynamic range CMOS camera and digital signal processing unit placed outside of the eye provides the data for the prosthesis which projects an image onto the retina. In this study the current results of long–term biocompatibility and wireless energy and signal transmission are presented. Methods: Thirteen active miniaturized arrays of light emitting diodes (LED) were implanted in pigmented rabbit eyes by extracapsular lentectomy and fixation in the ciliary sulcus. The eyes were followed–up for up to twelwe months. Function of the prosthesis was checked weekly by using an inductive transmission energy supply. Biocompatibility testing comprised electrophysiological investigation of the retina and histological evaluation. To achieve slices of tissue together with the implanted microelectronic components a micro–grinding preparation technique was performed in two eyes. Results: Inductive energy transmission and wireless stimulation of the implant could be achieved without functional loss up to twelwe months. Electrophysiology showed no difference in the electro–retinogram (ERG) between the operated eye and the fellow eye. Histological investigation of the enucleated eye revealed a prolonged moderate inflammatory reaction around the capsular bag for several weeks, but in the long–term no cellular alteration was detectable indicating good tissue biocompatibility. Conclusions:Our results demonstrate the general feasibility to implant and fixate an IoVA for long–term and to establish wireless light stimulation. Biocompatibility and inductive energy transmission to the intraocular device are assured in the long–term and allow for future development of an IoVA with a multi–LED micro array to provide higher spatial resolution.

Keywords: keratoprostheses • trauma • low vision