Dataset Information

Chronic electrical stimulation with a suprachoroidal retinal prosthesis: a preclinical safety and efficacy study.

ABSTRACT:

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 k? 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.

SUBMITTER: Nayagam DA

PROVIDER: S-EPMC4031073 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Publications

Chronic electrical stimulation with a suprachoroidal retinal prosthesis: a preclinical safety and efficacy study.

Nayagam David A X DA Williams Richard A RA Allen Penelope J PJ Shivdasani Mohit N MN Luu Chi D CD Salinas-LaRosa Cesar M CM Finch Sue S Ayton Lauren N LN Saunders Alexia L AL McPhedran Michelle M McGowan Ceara C Villalobos Joel J Fallon James B JB Wise Andrew K AK Yeoh Jonathan J Xu Jin J Feng Helen H Millard Rodney R McWade Melanie M Thien Patrick C PC Williams Chris E CE Shepherd Robert K RK

PloS one 20140522 5

<h4>Purpose</h4>To assess the safety and efficacy of chronic electrical stimulation of the retina with a suprachoroidal visual prosthesis.<h4>Methods</h4>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 an ...[more]

PMID: 24853376

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Dataset Information

Chronic electrical stimulation with a suprachoroidal retinal prosthesis: a preclinical safety and efficacy study.

Purpose

Methods

Results

Conclusions

Publications

Chronic electrical stimulation with a suprachoroidal retinal prosthesis: a preclinical safety and efficacy study.

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