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Title: A Second-Generation (44-Channel) Suprachoroidal Retinal Prosthesis: Long-Term Observation of the Electrode–Tissue Interface
Authors: Titchener, Samuel
Nayagam, David
Kvansakul, Jessica
Kolic, Maria
Baglin, Elizabeth
Abbott, Carla
McGuinness, Myra
Ayton, Lauren
Luu, Chi
Greenstein, Steven
Kentler, William
Shivdasani, Mohit
Allen, Penelope
Petoe, Matthew
Keywords: Visual prosthesis
Retinal prosthesis
Issue Date: Jun-2022
Publisher: Translational Vision Science & Technology
Citation: Titchener SA, Nayagam DAX, Kvansakul J, Kolic M, Baglin EK, Abbott CJ, McGuinness MB, Ayton LN, Luu CD, Greenstein S, Kentler WG, Shivdasani MN, Allen PJ, Petoe MA. A Second-Generation (44-Channel) Suprachoroidal Retinal Prosthesis: Long-Term Observation of the Electrode–Tissue Interface. Trans Vis Sci Tech. 2022;11(6):12
Abstract: Purpose: To report the long-term observations of the electrode–tissue interface and perceptual stability in humans after chronic stimulation with a 44-channel suprachoroidal retinal implant. Methods: Four subjects (S1–4) with end-stage retinitis pigmentosa received the implant unilaterally (NCT03406416). Electrode impedances, electrode–retina distance (measured using optical coherence tomography imaging), and perceptual thresholds were monitored up to 181 weeks after implantation as the subjects used the prosthesis in the laboratory and in daily life. Stimulation charge density was limited to 32 µC/cm2 per phase. Results: Electrode impedances were stable longitudinally. The electrode–retina distances increased after surgery and then stabilized, and were well-described by an asymptotic exponential model. The stabilization of electrode–retina distances was variable between subjects, stabilizing after 45 weeks for S1, 63 weeks for S2, and 24 weeks for S3 (linear regression; Pgradient > 0.05). For S4, a statistically significant increase in electrode–retina distance persisted (P < 0.05), but by the study end point the rate of increase was clinically insignificant (exponential model: 0.33 µm/wk). Perceptual electrical thresholds were stable in one subject, decreased over time in two subjects (linear model; P < 0.05), and increased slightly in one subject but remained within the predefined charge limits (P = 0.02). Conclusions: Chronic stimulation with the suprachoroidal retinal prosthesis over 3 years resulted in stable impedances, small individual changes in perceptual electrical thresholds, and no clinically significant increase in electrode–retina distances after a period of settling after surgery. Translational Relevance: Chronic stimulation with the 44-channel suprachoroidal retinal implant with a charge density of up to 32 µC/cm2 per phase is suitable for long-term use in humans.
URI: http://repository.bionicsinstitute.org:8080/handle/123456789/420
ISSN: 2164-2591
Appears in Collections:Bionic Vision Research Publications

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