Factors Affecting Perceptual Thresholds in a Suprachoroidal Retinal Prosthesis

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dc.contributor.authorShivdasani, Mohit
dc.contributor.authorSinclair, Nicholas
dc.contributor.authorDimitrov, Peter
dc.contributor.authorVarsamidis, Mary
dc.contributor.authorAyton, Lauren
dc.contributor.authorLuu, Chi
dc.contributor.authorPerera, Thushara
dc.contributor.authorMcDermott, Hugh
dc.contributor.authorBlamey, Peter
dc.date.accessioned2015-04-01T03:09:02Z
dc.date.available2015-04-01T03:09:02Z
dc.date.issued2014-10
dc.description.abstractPURPOSE: The suprachoroidal location for a retinal prosthesis provides advantages over other locations in terms of a simplified surgical procedure and a potentially more stable electrode-neural interface. The aim of this study was to assess the factors affecting perceptual thresholds, and to optimize stimulus parameters to achieve the lowest thresholds in patients implanted with a suprachoroidal retinal prosthesis. METHODS: Three patients with profound vision loss from retinitis pigmentosa were implanted with a suprachoroidal array. Perceptual thresholds measured on individual electrodes were analyzed as a function of stimulus (return configuration, pulse polarity, pulse width, interphase gap, and rate), electrode (area and number of ganged electrodes), and clinical (retinal thickness and electrode-retina distance) parameters. RESULTS: A total of 92.8% of 904 measurements made up to 680 days post implantation yielded thresholds (range, 44-436 nanocoulombs [nC]) below the safe charge limit. Thresholds were found to vary between individuals and to depend significantly on electrode-retina distance, negligibly on retinal thickness, and not on electrode area or the number of ganged electrodes. Lowest thresholds were achieved when using a monopolar return, anodic-first polarity, short pulse widths (100 μs) combined with long interphase gaps (500 μs), and high stimulation rates (≥400 pulses per second [pps]). CONCLUSIONS: With suprachoroidal stimulation, anodic-first pulses with a monopolar return are most efficacious. To enable high rates, an appropriate combination of pulse width and interphase gap must be chosen to ensure low thresholds and electrode voltages. Electrode-retina distance needs to be monitored carefully owing to its influence on thresholds. These results inform implantable stimulator specifications for a suprachoroidal retinal prosthesis. (ClinicalTrials.gov number, NCT01603576.).en_US
dc.description.sponsorshipThis work was supported by the Australian Research Council through its Special Research Initiative in Bionic Vision Science and Technology awarded to Bionic Vision Australia and by the Bertalli Family Foundation to the Bionics Institute. The Bionics Institute and the Centre for Eye Research Australia (CERA) acknowledge the support received from the Victorian Government through its Operational Infrastructure Program. CERA is also supported by an NHMRC Centre for Clinical Research Excellence Award #529923.en_US
dc.identifier.citationShivdasani, M. N., Sinclair, N. C., Dimitrov, P. N., Varsamidis, M., Ayton, L. N., Luu, C. D., et al. (2014). Factors affecting perceptual thresholds in a suprachoroidal retinal prosthesis. Investigative Ophthalmology & Visual Science, 55(10), 6467-6481en_US
dc.identifier.urihttp://repository.bionicsinstitute.org:8080/handle/123456789/116
dc.language.isoenen_US
dc.publisherThe Association for Research in Vision and Ophthalmology Incen_US
dc.subjectretinal prosthesisen_US
dc.subjectretinitis pigmentosaen_US
dc.subjectsuprachoroidalen_US
dc.subjectthresholden_US
dc.titleFactors Affecting Perceptual Thresholds in a Suprachoroidal Retinal Prosthesisen_US
dc.typeArticleen_US
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