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Techniques for Processing Eyes Implanted With a Retinal Prosthesis for Localized Histopathological Analysis

With  the recent development of retinal prostheses, it is important to develop  reliable techniques for assessing the safety of these devices in ...

Bionics Institute

Our research goal is to develop a safe, reproducible surgical approach for implantation of a wide-field retinal stimulating array. The aim of this study was to evaluate the pathological response to acute implantation of a functional prototype electrode array in the suprachoroidal space.

Development of a surgical approach for a wide-view suprachoroidal retinal prosthesis: evaluation of implantation trauma.

L&#39;objectif de notre recherche est de d&eacute;velopper une approche chirurgicale s&ucirc;re et reproductible pour l&#39;implantation d&#39;une r&eacute;tine grand-angulaire stimulant tableau. Le but de cette &eacute;tude &eacute;tait d&#39;&eacute;valuer la r&eacute;ponse pathologique &agrave; la nidation d&#39;un tableau d&#39;&eacute;lectrode prototype fonctionnel dans l&#39;espace de suprachoroidal aigu&euml;.

D&eacute;veloppement d&#39;une approche chirurgicale pour une proth&egrave;se de r&eacute;tine grand angle suprachoroidal : &eacute;valuation du traumatisme de l&#39;implantation.

Il nostro obiettivo di ricerca &egrave; quello di sviluppare un approccio chirurgico sicuro, riproducibile per l&#39;impianto di un grande campo retinico stimolando la matrice. Lo scopo di questo studio era di valutare la risposta patologica per l&#39;impianto acuta di una matrice di elettrodo prototipo funzionale nello spazio suprachoroidal.

Sviluppo di un approccio chirurgico per una protesi retiniche wide-view suprachoroidal: valutazione del trauma dell&#39;impianto.

PURPOSE: The safety of chronic implantation of a retinal prosthesis in the suprachoroidal space has not been established. This study aimed to determine the safety of a wide-field suprachoroidal electrode array following chronic implantation using histopathological techniques and electroretinography. METHODS: A platinum electrode array in a wide silicone substrate was implanted unilaterally in the suprachoroidal space in cats (n = 7). The lead and connector were tunneled out of the orbit and positioned subcutaneously. Post-surgical recovery was assessed using fundus photography and electroretinography (ERG). Following 3 months of passive implantation, the animals were terminated and the eyes assessed for the pathological response to implantation. RESULTS: The implant was mechanically stable in the suprachoroidal space during the course of the study. The implanted eye showed a transient increase in ERG response amplitude at 2 weeks which returned to normal by 3 months. Pigmentary changes were observed at the distal end of the implant, near the optic disc. Histopathological assessment revealed a largely intact retina and a thin fibrous capsule around the suprachoroidal implant cavity. The foreign body response was minimal with sporadic presence of macrophages and no active inflammation. All implanted eyes were negative for bacterial or fungal infections. A mid-grade granuloma and thick fibrous build-up surrounded the extraocular cable. Scleral closure was maintained in 6 of 7 eyes. There were no staphylomas or choroidal incarceration. CONCLUSIONS: A wide-field retinal prosthesis was stable and well tolerated during long-term suprachoroidal implantation in a cat model. The surgical approach was reproducible and overall safe.

A wide-field suprachoroidal retinal prosthesis is stable and well tolerated following chronic implantation.

BUT : L&#39;innocuit&eacute; d&#39;implantation chronique d&#39;un implant r&eacute;tinien en l&#39;espace de suprachoroidal n&#39;a pas &eacute;t&eacute; &eacute;tablie. Cette &eacute;tude visait &agrave; d&eacute;terminer l&#39;innocuit&eacute; d&#39;un tableau d&#39;&eacute;lectrode suprachoroidal grand champ apr&egrave;s l&#39;implantation chronique &agrave; l&#39;aide d&#39;&eacute;lectror&eacute;tinographie et techniques histopathologiques. M&eacute;thodes : Un tableau d&#39;&eacute;lectrode de platine dans un substrat de silicone large a &eacute;t&eacute; unilat&eacute;ralement implant&eacute; dans l&#39;espace suprachoroidal chez le chat (n = 7). Le plomb et le connecteur &eacute;taient hors de l&#39;orbite en tunnel et plac&eacute;s sous la peau. R&eacute;cup&eacute;ration post-op&eacute;ratoire a &eacute;t&eacute; &eacute;valu&eacute;e &agrave; l&#39;aide de la photographie du fond de &oelig;il et &eacute;lectror&eacute;tinographie (ERG). Apr&egrave;s 3 mois d&#39;implantation passive, les animaux ont &eacute;t&eacute; r&eacute;sili&eacute;s et les yeux &eacute;valu&eacute; pour la r&eacute;ponse pathologique &agrave; la nidation. R&Eacute;SULTATS : L&#39;implant a &eacute;t&eacute; m&eacute;caniquement stable dans l&#39;espace suprachoroidal au cours de l&#39;&eacute;tude. L&#39;oeil implant&eacute; a montr&eacute; une augmentation transitoire dans l&#39;ERG r&eacute;ponse en amplitude &agrave; 2 semaines, ce qui revient &agrave; la normale de 3 mois. Changements pigmentaires ont &eacute;t&eacute; observ&eacute;es &agrave; l&#39;extr&eacute;mit&eacute; distale de l&#39;implant, pr&egrave;s du disque optique. &Eacute;valuation histopathologique a r&eacute;v&eacute;l&eacute; une r&eacute;tine en grande partie intacte et une mince capsule fibreuse autour de la cavit&eacute; d&#39;implant de suprachoroidal. La r&eacute;action au corps &eacute;tranger &eacute;tait minime avec une pr&eacute;sence sporadique des macrophages et aucune inflammation active. Tous les yeux implant&eacute;s &eacute;taient n&eacute;gatifs pour des infections bact&eacute;riennes ou fongiques. Un granulome mi-cat&eacute;gorie et accumulation fibreuse &eacute;paisse entour&eacute; le c&acirc;ble extra-oculaires. Fermeture scl&eacute;rale persistait dans 6 des 7 yeux. Il n&#39;y a aucun staphylomas ou incarc&eacute;ration choro&iuml;dienne. CONCLUSIONS : Une proth&egrave;se de r&eacute;tine grand-angulaire est stable et bien tol&eacute;r&eacute; pendant l&#39;implantation de suprachoroidal &agrave; long terme dans un mod&egrave;le de chat. L&#39;approche chirurgicale a &eacute;t&eacute; globalement s&ucirc;re et reproductible.

Une proth&egrave;se de r&eacute;tine suprachoroidal grand champ est stable et bien tol&eacute;r&eacute; apr&egrave;s l&#39;implantation chronique.

SCOPO: La sicurezza del cronico dell&#39;impianto di una protesi della retina nello spazio suprachoroidal non &egrave; stata stabilita. Questo studio finalizzato a determinare la sicurezza di una matrice di elettrodo wide-field suprachoroidal seguendo l&#39;impianto cronico utilizzando tecniche istopatologiche ed elettroretinografia. Metodi: Un array di elettrodo di platino in un substrato di vasta in silicone &egrave; stato impiantato unilateralmente nello spazio suprachoroidal in gatti (n = 7). Il cavo e connettore erano tunneled fuori l&#39;orbita e posizionati sotto la cute. Recupero post-operatorio &egrave; stata valutata utilizzando la fotografia del fundus ed elettroretinografia (ERG). Dopo 3 mesi di impianto passivo, gli animali sono stati terminati e gli occhi valutata per la risposta patologica per l&#39;impianto. RISULTATI: L&#39;impianto era meccanicamente stabile nello spazio suprachoroidal durante il corso di studio. L&#39;occhio impiantato ha mostrato un aumento transitorio ERG ampiezza di risposta a 2 settimane che torn&ograve; normale di 3 mesi. L&#39;estremit&agrave; distale dell&#39;impianto, vicino il disco ottico sono state osservate alterazioni della pigmentazione. Valutazione istopatologica ha rivelato una retina in gran parte intatto e una sottile capsula fibrosa intorno alla cavit&agrave; dell&#39;impianto suprachoroidal. La risposta da corpo estraneo &egrave; stato minima con sporadica presenza di macrofagi e nessuna infiammazione attiva. Tutti gli occhi impiantati erano negativi per le infezioni fungine o batteriche. Un granuloma contraffatto e accumulo fibroso denso circondato il cavo extraoculari. Chiusura sclerale &egrave; stato mantenuto in 6 di 7 occhi. C&#39;erano staphylomas o incarcerazione della coroide. CONCLUSIONI: Una protesi retiniche wide-field era stabile e ben tollerati durante l&#39;impianto di suprachoroidal a lungo termine in un modello di gatto. L&#39;approccio chirurgico &egrave; stato nel complesso sicuro e riproducibile.

Joel Villalobos

Bionics Institute

Techniques for Processing Eyes Implanted With a Retinal Prosthesis for Localized Histopathological Analysis