A Second-Generation (44-Channel) Suprachoroidal Retinal Prosthesis: Interim Clinical Trial Results

Petoe, Matthew A.; Titchener, Samuel A; Kolic, Maria; Kentler, William G; Abbott, Carla J; Nayagam, David A. X.; Baglin, Elizabeth Kate; Kvansakul, Jessica; Barnes, Nick; Walker, Janine; Epp, Stephanie B.; Young, Kiera A; Ayton, Lauren N; Luu, Chi D; Allen, Penelope J

doi:10.1167/tvst.10.10.12

Cited by 36 publications

(45 citation statements)

References 59 publications

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“…Different neural targets along the visual pathway can be stimulated to elicit flashes of light known as phosphenes, which can be used as rudimentary visual feedback for people with blindness. To date, visual neuroprostheses have been implanted for at least several months in the retina (Humayun et al 2012; Stingl et al 2013; Fujikado et al 2016; Petoe et al 2021; Barnes et al 2016; Palanker et al 2022; Xu et al 2021), optic nerve (Veraart et al 2003), and visual cortex of human subjects (Beauchamp et al 2020; Fernández et al 2021). The Argus® II (Second Sight Medical Products, Sylmar, CA, USA) is a device that was implanted commercially in the United States from 2014 through 2020.…”

Section: Introductionmentioning

confidence: 99%

Sequential epiretinal stimulation improves discrimination in simple shape discrimination tasks only

Christie

Sadeghi

Kartha

et al. 2022

Preprint

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ObjectiveElectrical stimulation of the retina can elicit flashes of light called phosphenes, which can be used to restore rudimentary vision for people with blindness. Functional sight requires stimulation of multiple electrodes to create patterned vision, but phosphenes tend to merge together in an uninterpretable way. Sequentially stimulating electrodes in human visual cortex has recently demonstrated that shapes could be “drawn” with better perceptual resolution relative to simultaneous stimulation. The goal of this study was to evaluate if sequential stimulation would also form clearer shapes when the retina is the neural target.ApproachTwo human participants with retinitis pigmentosa who had Argus® II retinal prostheses participated in this study. We evaluated different temporal parameters for sequential stimulation in phosphene shape mapping and forced-choice discrimination tasks. For the discrimination tasks, performance was compared between stimulating electrodes simultaneously versus sequentially.Main resultsPhosphenes elicited by different electrodes were reported as vastly different shapes. Sequential electrode stimulation outperformed simultaneous stimulation in simple discrimination tasks, in which shapes were created by stimulating 3-4 electrodes, but not in more complex discrimination tasks involving 5+ electrodes. For sequential stimulation, the optimal pulse train duration was 200 ms when stimulating at 20 Hz and the optimal gap interval was tied between 0 and 50 ms. Efficacy of sequential stimulation also depended strongly on selecting electrodes that elicited phosphenes with similar shapes and sizes.SignificanceAn epiretinal prosthesis can produce coherent simple shapes with a sequential stimulation paradigm, which can be used as rudimentary visual feedback. However, success in creating more complex shapes, such as letters of the alphabet, is still limited. Sequential stimulation may be most beneficial for epiretinal prostheses in simple tasks, such as basic navigation, rather than complex tasks such as object identification.

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Section: Introductionmentioning

confidence: 99%

Sequential epiretinal stimulation improves discrimination in simple shape discrimination tasks only

Christie

Sadeghi

Kartha

et al. 2022

Preprint

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“…Several approaches to vision restoration with electronic implants exist today (Weiland et al, 2011(Weiland et al, , 2016, including epiretinal (Zhou et al, 2013), subretinal (Palanker et al, 2020), and suprachoroidal (Bareket et al, 2017;Petoe et al, 2021) devices. Each approach has demonstrated the feasibility of partial restoration of visual signals, and in some cases, of useful visually guided behaviors.…”

Section: Discussionmentioning

confidence: 99%

High-fidelity reproduction of visual signals by electrical stimulation in the central primate retina

Gogliettino

Madugula

Grosberg

et al. 2022

Preprint

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Electrical stimulation of retinal ganglion cells (RGCs) with electronic implants provides rudimentary artificial vision to people blinded by retinal degeneration, but cannot reproduce the neural code of the retina. Recent work has demonstrated more precise activation of RGCs using focal electrical stimulation in the peripheral macaque retina, but high-resolution vision requires the central retina. This work probes the effectiveness of focal epiretinal stimulation in the central macaque retina, using large-scale recording and stimulation ex vivo. The functional organization of the major RGC types was similar between the peripheral and central retina, and these cell types could be distinguished by their electrical properties. Electrical stimulation revealed similar RGC activation thresholds and reduced axon bundle activation in the central retina, but diminished stimulation selectivity. However, a novel stimulation algorithm revealed higher expected acuity in the central retina. These results support the possibility of reproducing high-acuity vision in the central retina with an epiretinal implant.

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“…This study presents data from four adult human subjects (S1–S4) who participated in the clinical trial of a 44-channel suprachoroidal retinal implant (NCT03406416) between 2018 and 2021. 16 – 18 The subjects were profoundly blind (bare light perception only) from end-stage retinitis pigmentosa and had the suprachoroidal retinal prosthesis implanted unilaterally in 2018 ( Table 1 ). Device fitting commenced 8 weeks postoperatively, followed by training in laboratory and real-world environments and a minimum of 2 years of regular outcome measure assessments.…”

Section: Methodsmentioning

confidence: 99%

“…Device fitting commenced 8 weeks postoperatively, followed by training in laboratory and real-world environments and a minimum of 2 years of regular outcome measure assessments. 16 – 18 During this time the subjects used the prosthesis unsupervised in their daily lives and regularly visited the laboratory for training, functional vision assessment, and OCT imaging. Table 1 summarizes the subject demographics and the length of observation for each subject.…”

Section: Methodsmentioning

confidence: 99%

“…All four subjects perceived phosphenes in response to electrical stimulation with the implant, and the prosthesis provided functional vision improvements and meaningful assistance in activities of daily living. 16 – 18 For these practical benefits to be sustained in the long term, it is important that chronic stimulation with the implant does not lead to a loss of device functionality owing to changes in the electrode–tissue interface.…”

Section: Introductionmentioning

confidence: 99%

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A Second-Generation (44-Channel) Suprachoroidal Retinal Prosthesis: Long-Term Observation of the Electrode–Tissue Interface

Titchener

Nayagam

Kvansakul

et al. 2022

Trans. Vis. Sci. Tech.

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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/cm 2 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; P gradient > 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/cm 2 per phase is suitable for long-term use in humans.

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A Second-Generation (44-Channel) Suprachoroidal Retinal Prosthesis: Interim Clinical Trial Results

Cited by 36 publications

References 59 publications

Sequential epiretinal stimulation improves discrimination in simple shape discrimination tasks only

Sequential epiretinal stimulation improves discrimination in simple shape discrimination tasks only

High-fidelity reproduction of visual signals by electrical stimulation in the central primate retina

A Second-Generation (44-Channel) Suprachoroidal Retinal Prosthesis: Long-Term Observation of the Electrode–Tissue Interface

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