June 2023
Volume 64, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2023
Chronic electrical stimulation with a peripheral suprachoroidal retinal implant: A preclinical safety study
Author Affiliations & Notes
  • Carla J Abbott
    Centre for Eye Research Australia Ltd, East Melbourne, Victoria, Australia
    Department of Surgery (Ophthalmology), The University of Melbourne Faculty of Medicine Dentistry and Health Sciences, Melbourne, Victoria, Australia
  • David AX Nayagam
    Bionics Institute, East Melbourne, Victoria, Australia
    Department of Pathology, St Vincent's Hospital, The University of Melbourne Faculty of Medicine Dentistry and Health Sciences, Melbourne, Victoria, Australia
  • Stephanie B Epp
    Bionics Institute, East Melbourne, Victoria, Australia
  • Owen Burns
    Bionics Institute, East Melbourne, Victoria, Australia
  • Ross Thomas
    Bionics Institute, East Melbourne, Victoria, Australia
  • Mark Harrison
    Bionics Institute, East Melbourne, Victoria, Australia
  • Patrick C Thien
    Bionics Institute, East Melbourne, Victoria, Australia
    Medical Bionics Department, The University of Melbourne Faculty of Medicine Dentistry and Health Sciences, Melbourne, Victoria, Australia
  • Alexia Saunders
    Bionics Institute, East Melbourne, Victoria, Australia
  • Ceara McGowan
    Bionics Institute, East Melbourne, Victoria, Australia
  • Caitlin Sloan
    Bionics Institute, East Melbourne, Victoria, Australia
  • Richard A Williams
    Department of Pathology, St Vincent's Hospital, The University of Melbourne Faculty of Medicine Dentistry and Health Sciences, Melbourne, Victoria, Australia
    St. Vincent's Hospital Melbourne, Victoria, Australia
  • Chris E Williams
    Bionics Institute, East Melbourne, Victoria, Australia
    Medical Bionics Department, The University of Melbourne Faculty of Medicine Dentistry and Health Sciences, Melbourne, Victoria, Australia
  • Penelope J Allen
    Centre for Eye Research Australia Ltd, East Melbourne, Victoria, Australia
    Department of Surgery (Ophthalmology), The University of Melbourne Faculty of Medicine Dentistry and Health Sciences, Melbourne, Victoria, Australia
  • Chi D Luu
    Centre for Eye Research Australia Ltd, East Melbourne, Victoria, Australia
    Department of Surgery (Ophthalmology), The University of Melbourne Faculty of Medicine Dentistry and Health Sciences, Melbourne, Victoria, Australia
  • Footnotes
    Commercial Relationships   Carla Abbott Bionic Vision Technologies, Code F (Financial Support), Mira Therapeutics, Code O (Owner); David Nayagam Mira Therapeutics, Code O (Owner), Bionics Institute, Code P (Patent); Stephanie Epp None; Owen Burns Bionics Institute, Code P (Patent); Ross Thomas None; Mark Harrison None; Patrick Thien None; Alexia Saunders None; Ceara McGowan None; Caitlin Sloan None; Richard Williams None; Chris Williams Bionics Institute, Code P (Patent); Penelope Allen Mira Therapeutics, Code O (Owner), CERA, Code P (Patent); Chi Luu Mira Therapeutics, Code O (Owner), CERA, Code P (Patent)
  • Footnotes
    Support  Australian National Health and Medical Research Council Development Grant (#1120664); Victorian Government Operational Infrastructure Support Program.
Investigative Ophthalmology & Visual Science June 2023, Vol.64, 4608. doi:
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    • Get Citation

      Carla J Abbott, David AX Nayagam, Stephanie B Epp, Owen Burns, Ross Thomas, Mark Harrison, Patrick C Thien, Alexia Saunders, Ceara McGowan, Caitlin Sloan, Richard A Williams, Chris E Williams, Penelope J Allen, Chi D Luu; Chronic electrical stimulation with a peripheral suprachoroidal retinal implant: A preclinical safety study. Invest. Ophthalmol. Vis. Sci. 2023;64(8):4608.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Transcorneal electrical stimulation is known to provide neuroprotection for retinal cells in retinitis pigmentosa. Currently, the treatment approach requires patients to set up corneal electrodes and stimulate weekly due to the lack of an implantable stimulation device. We developed a minimally invasive implantable device which allows delivery of chronic stimulation to the retina and may improve patient compliance for long-term use. The aim was to determine the surgical and stimulation safety of this novel device designed for neuroprotective stimulation.

Methods : Eight normally sighted adult feline subjects were monocularly implanted in the suprachoroidal space in the peripheral retina for 9-39 weeks. Charge balanced, biphasic, current pulses (100µA, 500µs pulse width and 50 pulse/s) were delivered continuously to platinum electrodes for 3-34 weeks. The current was selected to be delivered at physiologically relevant levels. Electrode impedances were measured weekly. Retinal structure, function and device stability were assessed at 1-, 2-, 4-, 6- and 8-months using electroretinography, optical coherence tomography and fundus photography. Randomized, blinded histopathological assessments of stimulated and non-stimulated retina of the implanted eye and retina of the fellow eye was performed by two trained graders (N=33 samples).

Results : All subjects tolerated the surgical and stimulation procedure with no evidence of discomfort or unexpected adverse outcomes. The device position was stable after a post-surgery settling period (4 weeks). Median electrode impedance at 1-week post-surgery (7.5kΩ) remained within a consistent range (5-10kΩ) over time. There was no change in retinal thickness or function relative to baseline and fellow eyes (p>0.05). Fibrotic capsule thickness was equivalent between stimulated and non-stimulated tissue (p>0.05). Histopathologically, there was no fibroblastic response in any samples, 19% had a minimal histiocytic response, 19% had minimal to mild acute inflammation and 28% had minimal to mild chronic inflammation.

Conclusions : Chronic suprathreshold electrical stimulation of the retina using a minimally invasive device evoked a mild tissue response and no adverse clinical findings. This device could potentially be an alternative approach to TES for delivering neuroprotective stimulation.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

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