gms | German Medical Science

Artificial Vision 2019

The International Symposium on Visual Prosthetics

13.12. - 14.12.2019, Aachen

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44-channel suprachoroidal retinal prosthesis clinical trial: interim device status update 1 year post-implantation

Meeting Abstract

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  • David A.X. Nayagam - Bionics Institute, East Melbourne/AUS; Department of Pathology, University of Melbourne, St. Vincent’s Hospital, Melbourne/AUS
  • M. A. Petoe - Bionics Institute, East Melbourne/AUS; Medical Bionics Department, University of Melbourne/AUS
  • S. A. Titchener - Bionics Institute, East Melbourne/AUS; Medical Bionics Department, University of Melbourne/AUS
  • M. Kolic - Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital,Melbourne/AUS
  • E. K. Baglin - Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital,Melbourne/AUS
  • C. J. Abbott - Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital,Melbourne/AUS; Ophthalmology, Department of Surgery, University of Melbourne/AUS
  • C. D. Luu - Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital,Melbourne/AUS; Ophthalmology, Department of Surgery, University of Melbourne/AUS
  • S. B. Epp - Bionics Institute, East Melbourne/AUS
  • P. Thien - Bionics Institute, East Melbourne/AUS
  • J. Kvansakul - Bionics Institute, East Melbourne/AUS; Medical Bionics Department, University of Melbourne/AUS
  • M. N. Shivdasani - Graduate School of Biomedical Engineering, The University of New South Wales, Sydney/AUS; Bionics Institute, East Melbourne/AUS
  • W. G. Kentler - Department of Biomedical Engineering, University of Melbourne, Melbourne/AUS
  • O. Burns - Bionics Institute, East Melbourne/AUS
  • J. Villalobos - Bionics Institute, East Melbourne/AUS
  • R. Millard - Bionics Institute, East Melbourne/AUS
  • P. Seligman - Bionics Institute, East Melbourne/AUS
  • J. Yeoh - Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital,Melbourne/AUS
  • R. J. Briggs - Otolaryngology, Department of Surgery, University of Melbourne/AUS
  • R. K. Shepherd - Bionics Institute, East Melbourne/AUS; Medical Bionics Department, University of Melbourne/AUS
  • C. E. Williams - Bionics Institute, East Melbourne/AUS; Medical Bionics Department, University of Melbourne/AUS
  • P. J. Allen - Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital,Melbourne/AUS; Ophthalmology, Department of Surgery, University of Melbourne/AUS

Artificial Vision 2019. Aachen, 13.-14.12.2019. Düsseldorf: German Medical Science GMS Publishing House; 2019. Doc19artvis26

doi: 10.3205/19artvis26, urn:nbn:de:0183-19artvis265

Published: December 10, 2019

© 2019 Nayagam et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 License. See license information at http://creativecommons.org/licenses/by/4.0/.

Outline

Text

Purpose: To evaluate the functionality and mechano-electrical stability of our suprachoroidal retinal prosthesis (SRP) in clinical trial participants.

Methods: 4 patients were implanted with a generation-2 SRP (Feb-Aug, 2018; ClinicalTrials.gov:NCT03406416). The implant had 44 platinum electrodes of 1mm diameter and 2 large return electrodes, embedded within a silicone substrate. This array was surgically positioned, suprachoroidally, with its stimulator package located on the ipsilateral skull. A patch affixed the implant to the temporal sclera beneath the lateral rectus muscle and a grommet stabilised the cable at the orbit. Impedances were measured intraoperatively and at follow-up visits to evaluate the implant’s electrical status and its effect on surrounding tissue. Impedances were calculated from voltage measurements in response to monopolar current controlled biphasic pulses (75µA, 25µs/phase). Array stability was assessed with optical coherence tomography (OCT). From 8 weeks post-implantation, electrodes were utilised with a range of stimulation parameters remaining within 250nC/phase/electrode.

Results: Intraoperatively 100% electrodes were operational; median impedances were 3.5kΩ (mean=3.5; SE=0.04; range=2.2-6.0). At switch-on, median impedance had risen to 5.9kΩ (mean=5.8; SE=0.05; range=3.2-8.1) in all participants and held steady thereafter. After a year of implantation, 98% electrodes remained <10kΩ. Electrode utilisation was weakly associated with short term decreases in impedances. There were no clear threshold trends. The array remained generally stable in the suprachoroidal space after an initial settling period. There was an average increase of 64-98µm in electrode to retina distance, as expected for fibrous tissue encapsulation.

Conclusion: The 44-channel SRP remains functional and stable after a year of implantation. Likewise, mechanical fixation and local tissue reaction are consistent with previous preclinical and clinical findings.

Acknowledgements and Funding: ARC Special Research Initiative in Bionic Vision Science and Technology grant to Bionic Vision Australia; NHMRC grant 1082358 to CIA PJA. NHMRC grant 1120664 to CIA CEW. The Centre for Eye Research Australia and the Bionics Institute wish to acknowledge the support of the Victorian Government through its Operational Infrastructure Support Program. DN, MP, ST, MK, EB, CA, CL, JK, WK, OB, PS, CW, PA receive(d) funding support from Bionic Vision Technologies.