Implantation und Explantation von inaktiven, epiretinal fixierten Retina Implant Systemen am Minipig

Hereditary photoreceptor-degenerations of the retina, such as Retinitis pigmentosa, lead to progressive visual loss and often result in complete blindness of the patient. Until now it has not been possible to halt disease progression. For the purpose of visual rehabilitation of those affected, the development of an artificial visual prosthesis is being aimed at. Thanks to progress made in the fields of microtechnology and microsurgery different approaches emerge, particularly those where stimulation of the retina is performed via epiretinal, subretinal or transscleral electrodes. Preliminary studies suggest that electric stimulation at the level of the retina via a chronically implanted micro-contact-foil is able to induce stable visual phenomenons in patients over an extended period of time, which may be useful for spatial orientation. The subject-matter of the publication at hand is a system designed for complete intraocular implantation and wireless activation to receive and deliver electric signals. In the course of the development of this system the tolerability of the used materials inside the eye, feasibility of reversible epiretinal fixation via retinal tacks, the viability of implantation as well as cortical activation triggered by the system via wireless activation could be shown, among other features. The purpose of the trial described herein was to show that both implantation and explantation of the EPI-RET® III device could be conducted safely, and to investigate tissue compatibility via immunohistochemical examination. To attain this goal, the system was implanted in five Göttinger minipigs. The eyes of this species and those of humans are very much alike as far as size and anatomy are concerned. Following phacoemulsification of the lens and complete vitrectomy the implant could be inserted into the eye via a corneal incision. While the receiver was placed into the ciliary sulcus (or into the anterior chamber) the stimulator which is attached to it was placed onto the central retina. For explantation these steps were reversed, removing the implant from the eye as gently as possible. Finally, histopathologic examination of the study eyes was conducted. In the course of this examination, special attention was paid to the visualisation of potential inflammatory or proliferative changes. The use of known and established surgical materials and procedures has shown to be a special advantage of the completely intraocular concept of the EPI-RET®-prosthesis. Extensive bleeding, due to the very particular vascularisation of the ciliary body in pigs, has complicated especially the explantation, so that the prosthesis could not be recovered completely in all cases. However, this could be achieved through altering the implantation strategy and placing the receiver chip in loco alio (i.e. into the anterior chamber, instead of ciliary sulcus). In spite of these difficulties the chosen animal model has shown to be suitable for demonstrating the general viability of implantation and explantation of the EPI-RET®-system. The complications we came across using the minipigs are unlikely to be encountered to the same extend in humans. In the human eye there is some substantial experience with the implantation of technical devices (intraocular lenses). The exigencies of the German “Medizinproduktegesetz” (national law to implement the European directive 90/385/EWG) for the safety of a human proband on the occasion of implantation and testing of the EPI-RET® III-system are fulfilled and a human trial can be deemed possible. This is supported by the absence of immunocompetent cells or a strong glial reaction in the histopathologic analysis of the study eyes.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2010

Author dc:creator

• Menzel-Severing, Johannes

Contributors dc:contributor

• Walter, Peter

• info:eu-repo/classification/ddc/610
• Netzhaut
• Implantat
• Augenchirurgie
• Immuncytochemie
• Medizin
• Epiretinal
• Sehprothese
• Immunhistochemie
• epiretinal prosthesis
• immunohistochemistry

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-124575%22

OAI identifier oai:identifier

oai:publications.rwth-aachen.de:63118