Subretinal Chronic Active Visual Prostheses in Blind Patients: The Transchoroidal Surgical Procedure

Abstract

Purpose: : The size of subretinal active film bound visual prostheses and their connection to extraocular structures requires a transchoroidal surgical procedure. A safe transchoroidal subretinal access is mandatory for a successful chronic implantation in humans.

Methods: : Two volunteer legally blind (LP) patients were implanted with a transdermal transchoroidal film bound subretinal stimulation device (active implant). The implant consisted of a stimulation chip which was mounted on a polyimide film and additional stimulation electrodes. The implant with its transchoroidal transdermal connection was supplied with energy via a retroauricular plug. Thus energy could be delivered and stimulation experiments could be carried out. Explantation was planned after 30 days. Radiodiathermy and a specially designed implantation instrument were used to penetrate the choroid without bleeding. Silicone oil was used as a tamponade.

Results: : The implantation was successfully performed in 2 patients. Neither a choroidal bleeding nor a retinal detachment were observed during the surgical procedure or the follow up period. The implants remained stable. One implant was explanted according to schedule after the experiment the other patient received an silicon oil explanation and kept the implant for further experiments.

Conclusions: : The transchoroidal implantation which was developed in animal experiments was successfully transferred to the human situation. This procedure enables safe chronic stable transchoroidal implantation.

Keywords: vitreoretinal surgery