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Chronic Electrical Stimulation with a Suprachoroidal Retinal Prosthesis: A Preclinical Safety and Efficacy Study
PURPOSE: To assess the safety and efficacy of chronic electrical stimulation of the retina with a suprachoroidal visual prosthesis. METHODS: Seven normally-sighted feline subjects were implanted for 96–143 days with a suprachoroidal electrode array and six were chronically stimulated for 70–105 days...
Autores principales: | , , , , , , , , , , , , , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Public Library of Science
2014
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4031073/ https://www.ncbi.nlm.nih.gov/pubmed/24853376 http://dx.doi.org/10.1371/journal.pone.0097182 |
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author | Nayagam, David A. X. Williams, Richard A. Allen, Penelope J. Shivdasani, Mohit N. Luu, Chi D. Salinas-LaRosa, Cesar M. Finch, Sue Ayton, Lauren N. Saunders, Alexia L. McPhedran, Michelle McGowan, Ceara Villalobos, Joel Fallon, James B. Wise, Andrew K. Yeoh, Jonathan Xu, Jin Feng, Helen Millard, Rodney McWade, Melanie Thien, Patrick C. Williams, Chris E. Shepherd, Robert K. |
author_facet | Nayagam, David A. X. Williams, Richard A. Allen, Penelope J. Shivdasani, Mohit N. Luu, Chi D. Salinas-LaRosa, Cesar M. Finch, Sue Ayton, Lauren N. Saunders, Alexia L. McPhedran, Michelle McGowan, Ceara Villalobos, Joel Fallon, James B. Wise, Andrew K. Yeoh, Jonathan Xu, Jin Feng, Helen Millard, Rodney McWade, Melanie Thien, Patrick C. Williams, Chris E. Shepherd, Robert K. |
author_sort | Nayagam, David A. X. |
collection | PubMed |
description | PURPOSE: To assess the safety and efficacy of chronic electrical stimulation of the retina with a suprachoroidal visual prosthesis. METHODS: Seven normally-sighted feline subjects were implanted for 96–143 days with a suprachoroidal electrode array and six were chronically stimulated for 70–105 days at levels that activated the visual cortex. Charge balanced, biphasic, current pulses were delivered to platinum electrodes in a monopolar stimulation mode. Retinal integrity/function and the mechanical stability of the implant were assessed monthly using electroretinography (ERG), optical coherence tomography (OCT) and fundus photography. Electrode impedances were measured weekly and electrically-evoked visual cortex potentials (eEVCPs) were measured monthly to verify that chronic stimuli were suprathreshold. At the end of the chronic stimulation period, thresholds were confirmed with multi-unit recordings from the visual cortex. Randomized, blinded histological assessments were performed by two pathologists to compare the stimulated and non-stimulated retina and adjacent tissue. RESULTS: All subjects tolerated the surgical and stimulation procedure with no evidence of discomfort or unexpected adverse outcomes. After an initial post-operative settling period, electrode arrays were mechanically stable. Mean electrode impedances were stable between 11–15 kΩ during the implantation period. Visually-evoked ERGs & OCT were normal, and mean eEVCP thresholds did not substantially differ over time. In 81 of 84 electrode-adjacent tissue samples examined, there were no discernible histopathological differences between stimulated and unstimulated tissue. In the remaining three tissue samples there were minor focal fibroblastic and acute inflammatory responses. CONCLUSIONS: Chronic suprathreshold electrical stimulation of the retina using a suprachoroidal electrode array evoked a minimal tissue response and no adverse clinical or histological findings. Moreover, thresholds and electrode impedance remained stable for stimulation durations of up to 15 weeks. This study has demonstrated the safety and efficacy of suprachoroidal stimulation with charge balanced stimulus currents. |
format | Online Article Text |
id | pubmed-4031073 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2014 |
publisher | Public Library of Science |
record_format | MEDLINE/PubMed |
spelling | pubmed-40310732014-05-28 Chronic Electrical Stimulation with a Suprachoroidal Retinal Prosthesis: A Preclinical Safety and Efficacy Study Nayagam, David A. X. Williams, Richard A. Allen, Penelope J. Shivdasani, Mohit N. Luu, Chi D. Salinas-LaRosa, Cesar M. Finch, Sue Ayton, Lauren N. Saunders, Alexia L. McPhedran, Michelle McGowan, Ceara Villalobos, Joel Fallon, James B. Wise, Andrew K. Yeoh, Jonathan Xu, Jin Feng, Helen Millard, Rodney McWade, Melanie Thien, Patrick C. Williams, Chris E. Shepherd, Robert K. PLoS One Research Article PURPOSE: To assess the safety and efficacy of chronic electrical stimulation of the retina with a suprachoroidal visual prosthesis. METHODS: Seven normally-sighted feline subjects were implanted for 96–143 days with a suprachoroidal electrode array and six were chronically stimulated for 70–105 days at levels that activated the visual cortex. Charge balanced, biphasic, current pulses were delivered to platinum electrodes in a monopolar stimulation mode. Retinal integrity/function and the mechanical stability of the implant were assessed monthly using electroretinography (ERG), optical coherence tomography (OCT) and fundus photography. Electrode impedances were measured weekly and electrically-evoked visual cortex potentials (eEVCPs) were measured monthly to verify that chronic stimuli were suprathreshold. At the end of the chronic stimulation period, thresholds were confirmed with multi-unit recordings from the visual cortex. Randomized, blinded histological assessments were performed by two pathologists to compare the stimulated and non-stimulated retina and adjacent tissue. RESULTS: All subjects tolerated the surgical and stimulation procedure with no evidence of discomfort or unexpected adverse outcomes. After an initial post-operative settling period, electrode arrays were mechanically stable. Mean electrode impedances were stable between 11–15 kΩ during the implantation period. Visually-evoked ERGs & OCT were normal, and mean eEVCP thresholds did not substantially differ over time. In 81 of 84 electrode-adjacent tissue samples examined, there were no discernible histopathological differences between stimulated and unstimulated tissue. In the remaining three tissue samples there were minor focal fibroblastic and acute inflammatory responses. CONCLUSIONS: Chronic suprathreshold electrical stimulation of the retina using a suprachoroidal electrode array evoked a minimal tissue response and no adverse clinical or histological findings. Moreover, thresholds and electrode impedance remained stable for stimulation durations of up to 15 weeks. This study has demonstrated the safety and efficacy of suprachoroidal stimulation with charge balanced stimulus currents. Public Library of Science 2014-05-22 /pmc/articles/PMC4031073/ /pubmed/24853376 http://dx.doi.org/10.1371/journal.pone.0097182 Text en © 2014 Nayagam et al http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited. |
spellingShingle | Research Article Nayagam, David A. X. Williams, Richard A. Allen, Penelope J. Shivdasani, Mohit N. Luu, Chi D. Salinas-LaRosa, Cesar M. Finch, Sue Ayton, Lauren N. Saunders, Alexia L. McPhedran, Michelle McGowan, Ceara Villalobos, Joel Fallon, James B. Wise, Andrew K. Yeoh, Jonathan Xu, Jin Feng, Helen Millard, Rodney McWade, Melanie Thien, Patrick C. Williams, Chris E. Shepherd, Robert K. Chronic Electrical Stimulation with a Suprachoroidal Retinal Prosthesis: A Preclinical Safety and Efficacy Study |
title | Chronic Electrical Stimulation with a Suprachoroidal Retinal Prosthesis: A Preclinical Safety and Efficacy Study |
title_full | Chronic Electrical Stimulation with a Suprachoroidal Retinal Prosthesis: A Preclinical Safety and Efficacy Study |
title_fullStr | Chronic Electrical Stimulation with a Suprachoroidal Retinal Prosthesis: A Preclinical Safety and Efficacy Study |
title_full_unstemmed | Chronic Electrical Stimulation with a Suprachoroidal Retinal Prosthesis: A Preclinical Safety and Efficacy Study |
title_short | Chronic Electrical Stimulation with a Suprachoroidal Retinal Prosthesis: A Preclinical Safety and Efficacy Study |
title_sort | chronic electrical stimulation with a suprachoroidal retinal prosthesis: a preclinical safety and efficacy study |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4031073/ https://www.ncbi.nlm.nih.gov/pubmed/24853376 http://dx.doi.org/10.1371/journal.pone.0097182 |
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