The Feasibility of Explanting a Suprachoroidal Electrode Array in a Feline Model

Abstract

Purpose: To determine whether chronically implanted suprachoroidal electrode arrays can be safely explanted in a feline model.

Methods: Six healthy subjects were unilaterally implanted with suprachoroidal electrode arrays which were surgically explanted after one month. Fundus photography and optical coherence tomography (OCT) was performed pre- and post- operatively. The subjects were overdosed two months post-explantation and the eyes were prepared for histological study.

Results: All the arrays were explanted with no intra-operative complications. OCT and fundus photography showed that the tapetum and retina was disrupted near the tip of the implant within two weeks of implantation and that explantation did not result in further disruption. Staphylomas were observed in five subjects upon macroscopic dissection. There was no change in the thickness of the choroid, photoreceptor layer or inner retina compared to the contralateral unimplanted control eye following array implantation or explantation. Histological results showed that the morphology of the retina was well preserved except for focal disruption of the tapetum and photoreceptors near the optic disk which corresponded to the same damaged regions observed in fundus photographs and OCT. There was a minor foreign body response with mild episcleral acute inflammation and mild chronic inflammation in the suprachoroidal space.

Conclusions: The feasibility of explanting a suprachoroidal retinal prosthesis has been demonstrated. This procedure can be safely performed provided that there is good management of the scleral wound. There was minimal damage to the globe and surrounding tissues. These findings have important implications for suprachoroidal array explantation in the clinical setting.

Keywords: 607 nanotechnology • 765 wound healing