Zukünftige Entwicklungen bei implantierbaren Netzhautprothesen

Zusammenfassung

Implantierbare retinale Sehprothesen werden bereits in der Klinik eingesetzt. Bei blinden Patienten mit Retinitis pigmentosa (RP) lassen sich mit den bisherigen Systemen Phosphene auslösen, jedoch ist der messbare Sehschärfengewinn begrenzt. Die Ursachen hierfür liegen einerseits in dem eigentlichen retinalen Degenerationsprozess und andererseits in der zum Einsatz kommenden Technologie. Forschergruppen und Hersteller arbeiten an Lösungskonzepten und neuen Prototypen für implantierbare Sehprothesen, um diese Limitationen zu überwinden. Zu den Maßnahmen gehört die Vergrößerung der Fläche des Stimulators mit dem Ziel, ein größeres Gesichtsfeld wiederherzustellen, eine Erhöhung der Zahl der Elektroden, um das räumliche Auflösungsvermögen der Implantate zu verbessern und die Schaffung einer Registrierfunktion neben der eigentlichen Stimulation. Mit einer solchen Registrierfunktion könnte das Implantat Informationen über die unter den Elektroden liegenden Ganglienzellen gewinnen und so das Stimulationsmuster auf die jeweilige Situation anpassen. Neben der Implantation auf oder unter der Netzhaut werden auch Systeme entwickelt, die im Suprachoroidalraum, am Sehnerv, am Corpus geniculatum laterale oder direkt in der Sehrinde implantiert werden.

Abstract

Implantable retinal prostheses for the blind are already in use. In blind subjects suffering from retinitis pigmentosa (RP), these systems are able to induce phosphenes. However, the measurable gain in vision is limited. This is due to degeneration in the retina itself and to the technology, which is used in the currently available systems. Research groups and companies are working on solutions and prototypes to improve the outcome of electrical stimulation in the visual system. One improvement will be to enlarge the electrode array in order to restore a larger visual field. A second approach is to enlarge the number of electrodes and to place them at a higher density to improve the spatial resolution of the system. A third concept is to develop a recording unit within the electrode array to analyse ganglion cell behaviour underneath the electrode. This information can than be used to optimise the stimulation pattern. Not only retinal prostheses are under development but also systems to stimulate the retina from the suprachoroidal space, to directly stimulate the optic nerve or the lateral geniculate body or even the primary visual cortex.

Schlüsselwörter

Retinaimplantat - Netzhautstimulation - Netzhautdegeneration - multimodale Implantate

Key words

retina implant - retinal stimulation - retinal degeneration - multimodal implants

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