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Artificial vision and retinal prostheses
Published in A Peyman MD Gholam, A Meffert MD Stephen, D Conway MD FACS Mandi, Chiasson Trisha, Vitreoretinal Surgical Techniques, 2019
Humayun Mark S, Lakhanpal Rohit R, Weiland James D
Visual prostheses are based on neuronal electrical stimulation at different locations along the visual pathway (i.e., cortical, optic nerve, epiretinal, and subretinal). In terms of retinal prostheses, advances in microtechnology have allowed for the development of sophisticated, high-density integrated circuit devices that may be implanted in either the subretinal or the epiretinal space. The aim of these devices, analogous to the cochlear implants for some forms of deafness, is to restore useful vision by converting visual information into patterns of electrical stimulation that would excite the remaining spared inner retinal neurons in diseases such as RP and ARMD. However, the approach in the visual system is more complex than in the auditory system. In the eye, information processing occurs simultaneously and in parallel within millions of neurons that transform the incoming light stimuli into electrical impulses, processing these impulses within the retina before sending the results through axons via the lateral geniculate nucleus to the visual cortex. The relative complexity of the visual system presents challenges to researchers.
Bidirectional Neural Interfaces
Published in Chang S. Nam, Anton Nijholt, Fabien Lotte, Brain–Computer Interfaces Handbook, 2018
Mikhail A. Lebedev, Alexei Ossadtchi
Visual prostheses hold promise of restoring vision to the blind (Fernandes et al. 2012). Several types of visual prostheses have been developed, which are applicable to different cases of blindness. Retinal prostheses (epiretinal, subretinal, transchoroidal, and optic nerve) are applicable to eye pathologies that spare parts of the optic nerve. Non-retinal prostheses employ electrical stimulation of cortical and subcortical visual areas. They are applicable to cases where the eye and/or optic nerve is severely damaged. Electrical stimulation of visual cortex to restore vision has been pioneered by William Dobelle (Dobelle et al. 1974).
Retinal Prostheses Current Approaches, Challenges, and Outlook
Published in Iniewski Krzysztof, Integrated Microsystems, 2017
Luke Theogarajan, John Wyatt, Joseph Rizzo
We have recently designed, fabricated, and implanted a visual prosthesis. Animal studies show that the implant remains viable postoperation. There exist numerous challenges in moving the implant from the bench to the bedside, and a concerted effort from scientists in different disciplines to come together is required. We hope that in the future we will eventually take the important step as we are able to perform human studies to understand the efficacy of a chronic retinal implant.
Adherence and satisfaction in Argus II prosthesis users: a self determination theory model
Published in Ophthalmic Genetics, 2022
Mariam Khan, Kari Branham, Kanishka T. Jayasundera, Naheed W. Khan
It would be interesting and beneficial to conduct a long-term follow-up study using a larger number of subjects and longitudinal research design to examine how the Argus users’ perspectives and motivations change over time. Response to the open-ended questions revealed that although most users were satisfied with their decision to get the Argus, they felt that the device could provide more enhanced vision and were hopeful that technological upgrades and improvements would be available. Although Second Sight Medical Products discontinued production of the Argus II retinal prosthesis system in April 2020, other similar implantable visual prosthetic devices and systems may be developed in future. When designing and implementing these new devices, it will be important to consider motivational factors that enable their successful usage to tailor the devices appropriately and to support patients who may wish to utilize them.
Advances in Neuroscience, Not Devices, Will Determine the Effectiveness of Visual Prostheses
Published in Seminars in Ophthalmology, 2021
Bardia Abbasi, Joseph F. Rizzo
Despite our limitations in both engineering and knowledge of neural coding, it might seem surprising that current devices have had any meaningful success. Perhaps neural plasticity—the ability of the brain to modify its function based upon learning or adaptation—enables the brain to extract value from suboptimal stimuli. The best evidence that neural plasticity may provide such leverage can be gleaned from recipients of cochlear implants, who often initially report metallic, monotonous, and inscrutable sounds, but can frequently hear well enough to hold telephone conversations with long-term rehabilitative training (often up to 1 year in duration).102 In contrast, despite restoration of normal optics in patients treated for early vision loss from corneal injury or congenital cataracts, deficits in complex visual processing (such as identification of three-dimensional forms or gender classification) can persist.103–105 Some such patients have even found their restored visual input frightening or disappointing.105,106 Clearly, the success of any visual prosthetic will depend upon central reorganization following prolonged blindness.