Abstract
So far there are no possibilities for restitution of vision abilities in people blind from hereditary retinal degeneration except electronic visual implants. Epiretinal and subretinal implants are already commercially available. Here the subretinal implant Alpha IMS (Retina Implant AG, Reutlingen, Germany) is presented, its technical construction, area of application, possible benefit for blind patients as well as surgical procedures including replacement, results from a clinical study in 29 patients, and safety issues. Subretinal implants are considered to have a number of advantages: the subretinal space is immunoprivileged, therefore less prone to proliferative vitreoretinal reactions; the fixation of the implant in between retina and choroid does not require scleral tacks; a retinotopically correct relation between perceived spot and retinal electrode is maintained in the visual field, thus shortening training times; natural eye movement and gaze help to localize objects; microsaccades are beneficial to avoid image fading; there are no devices attached to the face as all stimulation electronics are within the body; and resolution with 1500 pixels is the highest so far achieved.
The Alpha-IMS implant has received a CE mark for commercial use in Europe in 2013. Psychophysical testing and self-reported outcomes show restoration of useful vision in approximately half of the patients. Subretinal implantation surgery is safe. A new version (RETINA IMPLANT ALPHA AMS) with 1600 pixel and considerably improved longevity has received CE mark in March 2016 and providing centers have been recruited in several European countries.
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Zrenner, E. et al. (2017). The Subretinal Implant ALPHA: Implantation and Functional Results. In: Gabel, V. (eds) Artificial Vision. Springer, Cham. https://doi.org/10.1007/978-3-319-41876-6_6
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DOI: https://doi.org/10.1007/978-3-319-41876-6_6
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