1
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Fine I, Boynton GM. Pulse trains to percepts: A virtual patient describing the perceptual effects of human visual cortical stimulation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.18.532424. [PMID: 36993519 PMCID: PMC10055195 DOI: 10.1101/2023.03.18.532424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
The field of cortical sight restoration prostheses is making rapid progress with three clinical trials of visual cortical prostheses underway. However, as yet, we have only limited insight into the perceptual experiences produced by these implants. Here we describe a computational model or 'virtual patient', based on the neurophysiological architecture of V1, which successfully predicts the perceptual experience of participants across a wide range of previously published cortical stimulation studies describing the location, size, brightness and spatiotemporal shape of electrically induced percepts in humans. Our simulations suggest that, in the foreseeable future the perceptual quality of cortical prosthetic devices is likely to be limited by the neurophysiological organization of visual cortex, rather than engineering constraints.
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2
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Lestak J, Chod J, Rosina J, Hana K. Visual neuroprosthesis: present and possible perspectives. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub 2022; 166:251-257. [PMID: 35713333 DOI: 10.5507/bp.2022.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 05/26/2022] [Indexed: 11/23/2022] Open
Abstract
The purpose of this study is to provide an overview of the replacements used in lost vision in the form of the bionic eye, to show their deficiencies and outline other possibilities for non-invasive stimulation of functional areas of the visual cortex. The review highlights the damage not only to the primary altered cellular structures, but also to all other horizontally and vertically localised structures. Based on the results of a large number of functional magnetic resonance imaging and electrophysiological methods, the authors focus on the pathology of the entire visual pathway in pigmentary retinopathy (PR) and age-related macular degeneration (AMD). This study provides a recent overview of the possible systems used to replace lost vision. These range from stimulation with intraocular implants, through stimulation of the optic nerve and lateral geniculate nucleus to the visual cortex. The second part deals with the design of image processing technology and its transformation into the form of transcranial stimulation of undamaged parts of the brain, which is protected by a patent. This is comprehensive overview of the current possibilities of replacement of lost vision and a proposal for a new non-invasive methods of stimulation of functional neurons of the visual cortex.
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Affiliation(s)
- Jan Lestak
- Faculty of Biomedical Engineering, Czech Technical University in Prague, Czech Republic
| | - Jiri Chod
- Faculty of Electrical Engineering, Czech Technical University in Prague, Czech Republic
| | - Jozef Rosina
- Faculty of Biomedical Engineering, Czech Technical University in Prague, Czech Republic
| | - Karel Hana
- Faculty of Biomedical Engineering, Czech Technical University in Prague, Czech Republic
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3
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Esquenazi RB, Meier K, Beyeler M, Boynton GM, Fine I. Learning to see again: Perceptual learning of simulated abnormal on- off-cell population responses in sighted individuals. J Vis 2021; 21:10. [PMID: 34935878 PMCID: PMC8727313 DOI: 10.1167/jov.21.13.10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Many forms of artificial sight recovery, such as electronic implants and optogenetic proteins, generally cause simultaneous, rather than complementary firing of on- and off-center retinal cells. Here, using virtual patients—sighted individuals viewing distorted input—we examine whether plasticity might compensate for abnormal neuronal population responses. Five participants were dichoptically presented with a combination of original and contrast-reversed images. Each image (I) and its contrast-reverse (Iʹ) was filtered using a radial checkerboard (F) in Fourier space and its inverse (Fʹ). [I * F′] + [Iʹ * F] was presented to one eye, and [I * F] + [Iʹ * F′] was presented to the other, such that regions of the image that produced on-center responses in one eye produced off-center responses in the other eye, and vice versa. Participants continuously improved in a naturalistic object discrimination task over 20 one-hour sessions. Pre-training and post-training tests suggest that performance improvements were due to two learning processes: learning to recognize objects with reduced visual information and learning to suppress contrast-reversed image information in a non–eye-selective manner. These results suggest that, with training, it may be possible to adapt to the unnatural on- and off-cell population responses produced by electronic and optogenetic sight recovery technologies.
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Affiliation(s)
| | - Kimberly Meier
- Department of Psychology, University of Washington, USA.,
| | - Michael Beyeler
- Department of Computer Science, University of California, Santa Barbara, Santa Barbara, California, USA.,Department of Psychological and Brain Sciences, University of California, Santa Barbara, Santa Barbara, California, USA.,
| | | | - Ione Fine
- Department of Psychology, University of Washington, USA.,
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4
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Eggenberger SC, James NL, Ho C, Eamegdool SS, Tatarinoff V, Craig NA, Gow BS, Wan S, Dodds CWD, La Hood D, Gilmour A, Donahoe SL, Krockenberger M, Tumuluri K, da Cruz MJ, Grigg JR, McCluskey P, Lovell NH, Madigan MC, Fung AT, Suaning GJ. Implantation and long-term assessment of the stability and biocompatibility of a novel 98 channel suprachoroidal visual prosthesis in sheep. Biomaterials 2021; 279:121191. [PMID: 34768150 DOI: 10.1016/j.biomaterials.2021.121191] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 09/28/2021] [Accepted: 10/18/2021] [Indexed: 11/25/2022]
Abstract
Severe visual impairment can result from retinal degenerative diseases such as retinitis pigmentosa, which lead to photoreceptor cell death. These pathologies result in extensive neural and glial remodelling, with survival of excitable retinal neurons that can be electrically stimulated to elicit visual percepts and restore a form of useful vision. The Phoenix99 Bionic Eye is a fully implantable visual prosthesis, designed to stimulate the retina from the suprachoroidal space. In the current study, nine passive devices were implanted in an ovine model from two days to three months. The impact of the intervention and implant stability were assessed using indirect ophthalmoscopy, infrared imaging, and optical coherence tomography to establish the safety profile of the surgery and the device. The biocompatibility of the device was evaluated using histopathological analysis of the tissue surrounding the electrode array, with a focus on the health of the retinal cells required to convey signals to the brain. Appropriate stability of the electrode array was demonstrated, and histological analysis shows that the fibrotic and inflammatory response to the array was mild. Promising evidence of the safety and potential of the Phoenix99 Bionic Eye to restore a sense of vision to the severely visually impaired was obtained.
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Affiliation(s)
- Samuel C Eggenberger
- School of Biomedical Engineering, Faculty of Engineering, University of Sydney, Sydney, Australia
| | - Natalie L James
- Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia
| | - Cherry Ho
- Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia
| | - Steven S Eamegdool
- Save Sight Institute, The University of Sydney, Specialty of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, Australia
| | - Veronika Tatarinoff
- Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia
| | - Naomi A Craig
- Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia
| | - Barry S Gow
- Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia
| | - Susan Wan
- The Westmead Institute for Medical Research, Westmead, Australia
| | - Christopher W D Dodds
- Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia
| | - Donna La Hood
- Brien Holden Vision Institute, Sydney, Australia; School of Optometry and Vision Science, University of New South Wales (UNSW), Sydney, Australia
| | - Aaron Gilmour
- School of Biomedical Engineering, Faculty of Engineering, University of Sydney, Sydney, Australia; Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia
| | - Shannon L Donahoe
- Veterinary Pathology Diagnostic Services, Sydney School of Veterinary Science, University of Sydney, Sydney, Australia
| | - Mark Krockenberger
- Veterinary Pathology Diagnostic Services, Sydney School of Veterinary Science, University of Sydney, Sydney, Australia
| | - Krishna Tumuluri
- Save Sight Institute, The University of Sydney, Specialty of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, Australia; Westmead Clinical School, Specialty of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, University of Sydney, Sydney, Australia; Department of Ophthalmology, Faculty of Medicine and Health Sciences, Macquarie University, New South Wales, Australia
| | - Melville J da Cruz
- Department of Otolaryngology, Westmead Hospital, University of Sydney, Sydney, Australia; Faculty of Medicine and Health, University of Sydney, Sydney, Australia
| | - John R Grigg
- Save Sight Institute, The University of Sydney, Specialty of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, Australia; Faculty of Medicine and Health, University of Sydney, Sydney, Australia
| | - Peter McCluskey
- Save Sight Institute, The University of Sydney, Specialty of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, Australia; Faculty of Medicine and Health, University of Sydney, Sydney, Australia
| | - Nigel H Lovell
- Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia
| | - Michele C Madigan
- Save Sight Institute, The University of Sydney, Specialty of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, Australia; School of Optometry and Vision Science, University of New South Wales (UNSW), Sydney, Australia
| | - Adrian T Fung
- Save Sight Institute, The University of Sydney, Specialty of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, Australia; Westmead Clinical School, Specialty of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, University of Sydney, Sydney, Australia; Department of Ophthalmology, Faculty of Medicine and Health Sciences, Macquarie University, New South Wales, Australia
| | - Gregg J Suaning
- School of Biomedical Engineering, Faculty of Engineering, University of Sydney, Sydney, Australia; Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia.
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5
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Karapanos L, Abbott CJ, Ayton LN, Kolic M, McGuinness MB, Baglin EK, Titchener SA, Kvansakul J, Johnson D, Kentler WG, Barnes N, Nayagam DAX, Allen PJ, Petoe MA. Functional Vision in the Real-World Environment With a Second-Generation (44-Channel) Suprachoroidal Retinal Prosthesis. Transl Vis Sci Technol 2021; 10:7. [PMID: 34383875 PMCID: PMC8362639 DOI: 10.1167/tvst.10.10.7] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 06/09/2021] [Indexed: 11/24/2022] Open
Abstract
Purpose In a clinical trial (NCT03406416) of a second-generation (44-channel) suprachoroidal retinal prosthesis implanted in subjects with late-stage retinitis pigmentosa (RP), we assessed performance in real-world functional visual tasks and emotional well-being. Methods The Functional Low-Vision Observer Rated Assessment (FLORA) and Impact of Vision Impairment-Very Low Vision (IVI-VLV) instruments were administered to four subjects before implantation and after device fitting. The FLORA contains 13 self-reported and 35 observer-reported items ranked for ease of conducting task (impossible-easy, central tendency given as mode). The IVI-VLV instrument quantified the impact of low vision on daily activities and emotional well-being. Results Three subjects completed the FLORA for two years after device fitting; the fourth subject ceased participation in the FLORA after fitting for reasons unrelated to the device. For all subjects at each post-fitting visit, the mode ease of task with device ON was better or equal to device OFF. Ease of task improved over the first six months with device ON, then remained stable. Subjects reported improvements in mobility, functional vision, and quality of life with device ON. The IVI-VLV suggested self-assessed vision-related quality of life was not impacted by device implantation or usage. Conclusions Subjects demonstrated sustained improved ease of task scores with device ON compared to OFF, indicating the device has a positive impact in the real-world setting. Translational Relevance Our suprachoroidal retinal prosthesis shows potential utility in everyday life, by enabling an increased environmental awareness and improving access to sensory information for people with end-stage RP.
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Affiliation(s)
- Lewis Karapanos
- Centre for Eye Research Australia, Royal Victorian Eye & Ear Hospital, East Melbourne, VIC, Australia
- Ophthalmology, Department of Surgery, University of Melbourne, East Melbourne, VIC, Australia
| | - Carla J. Abbott
- Centre for Eye Research Australia, Royal Victorian Eye & Ear Hospital, East Melbourne, VIC, Australia
- Ophthalmology, Department of Surgery, University of Melbourne, East Melbourne, VIC, Australia
| | - Lauren N. Ayton
- Centre for Eye Research Australia, Royal Victorian Eye & Ear Hospital, East Melbourne, VIC, Australia
- Ophthalmology, Department of Surgery, University of Melbourne, East Melbourne, VIC, Australia
- Department of Optometry and Vision Sciences, University of Melbourne, Melbourne, VIC, Australia
| | - Maria Kolic
- Centre for Eye Research Australia, Royal Victorian Eye & Ear Hospital, East Melbourne, VIC, Australia
| | - Myra B. McGuinness
- Centre for Eye Research Australia, Royal Victorian Eye & Ear Hospital, East Melbourne, VIC, Australia
- Melbourne School of Population and Global Health, University of Melbourne, Parkville, VIC, Australia
| | - Elizabeth K. Baglin
- Centre for Eye Research Australia, Royal Victorian Eye & Ear Hospital, East Melbourne, VIC, Australia
| | - Samuel A. Titchener
- Bionics Institute, East Melbourne, VIC, Australia
- Medical Bionics Department, University of Melbourne, Parkville, VIC, Australia
| | - Jessica Kvansakul
- Bionics Institute, East Melbourne, VIC, Australia
- Medical Bionics Department, University of Melbourne, Parkville, VIC, Australia
| | - Dean Johnson
- Specialised Orientation and Mobility, Melbourne, VIC, Australia
| | - William G. Kentler
- Department of Biomedical Engineering, University of Melbourne, Parkville, VIC, Australia
| | - Nick Barnes
- Research School of Engineering, Australian National University, Canberra, ACT, Australia
| | - David A. X. Nayagam
- Bionics Institute, East Melbourne, VIC, Australia
- Department of Pathology, University of Melbourne, St. Vincent's Hospital, Fitzroy, VIC, Australia
| | - Penelope J. Allen
- Centre for Eye Research Australia, Royal Victorian Eye & Ear Hospital, East Melbourne, VIC, Australia
- Ophthalmology, Department of Surgery, University of Melbourne, East Melbourne, VIC, Australia
| | - Matthew A. Petoe
- Bionics Institute, East Melbourne, VIC, Australia
- Medical Bionics Department, University of Melbourne, Parkville, VIC, Australia
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6
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Petoe MA, Titchener SA, Kolic M, Kentler WG, Abbott CJ, Nayagam DAX, Baglin EK, Kvansakul J, Barnes N, Walker JG, Epp SB, Young KA, Ayton LN, Luu CD, Allen PJ. A Second-Generation (44-Channel) Suprachoroidal Retinal Prosthesis: Interim Clinical Trial Results. Transl Vis Sci Technol 2021; 10:12. [PMID: 34581770 PMCID: PMC8479573 DOI: 10.1167/tvst.10.10.12] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To report the initial safety and efficacy results of a second-generation (44-channel) suprachoroidal retinal prosthesis at 56 weeks after device activation. Methods Four subjects, with advanced retinitis pigmentosa and bare-light perception only, enrolled in a phase II trial (NCT03406416). A 44-channel electrode array was implanted in a suprachoroidal pocket. Device stability, efficacy, and adverse events were investigated at 12-week intervals. Results All four subjects were implanted successfully and there were no device-related serious adverse events. Color fundus photography indicated a mild postoperative subretinal hemorrhage in two recipients, which cleared spontaneously within 2 weeks. Optical coherence tomography confirmed device stability and position under the macula. Screen-based localization accuracy was significantly better for all subjects with device on versus device off. Two subjects were significantly better with the device on in a motion discrimination task at 7, 15, and 30°/s and in a spatial discrimination task at 0.033 cycles per degree. All subjects were more accurate with the device on than device off at walking toward a target on a modified door task, localizing and touching tabletop objects, and detecting obstacles in an obstacle avoidance task. A positive effect of the implant on subjects' daily lives was confirmed by an orientation and mobility assessor and subject self-report. Conclusions These interim study data demonstrate that the suprachoroidal prosthesis is safe and provides significant improvements in functional vision, activities of daily living, and observer-rated quality of life. Translational Relevance A suprachoroidal prosthesis can provide clinically useful artificial vision while maintaining a safe surgical profile.
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Affiliation(s)
- Matthew A Petoe
- Bionics Institute, East Melbourne, Victoria, Australia.,Medical Bionics Department, University of Melbourne, Melbourne, Victoria, Australia
| | - Samuel A Titchener
- Bionics Institute, East Melbourne, Victoria, Australia.,Medical Bionics Department, University of Melbourne, Melbourne, Victoria, Australia
| | - Maria Kolic
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
| | - William G Kentler
- Department of Biomedical Engineering, University of Melbourne, Melbourne, Victoria, Australia
| | - Carla J Abbott
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia.,Ophthalmology, Department of Surgery, University of Melbourne, Melbourne, Victoria, Australia
| | - David A X Nayagam
- Bionics Institute, East Melbourne, Victoria, Australia.,Department of Pathology, University of Melbourne, St. Vincent's Hospital, Victoria, Australia
| | - Elizabeth K Baglin
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
| | - Jessica Kvansakul
- Bionics Institute, East Melbourne, Victoria, Australia.,Medical Bionics Department, University of Melbourne, Melbourne, Victoria, Australia
| | - Nick Barnes
- Research School of Engineering, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Janine G Walker
- Research School of Engineering, Australian National University, Canberra, Australian Capital Territory, Australia.,Health & Biosecurity, CSIRO, Canberra, Australian Capital Territory, Australia
| | | | - Kiera A Young
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
| | - Lauren N Ayton
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia.,Ophthalmology, Department of Surgery, University of Melbourne, Melbourne, Victoria, Australia.,Department of Optometry and Vision Sciences, University of Melbourne, Australia
| | - Chi D Luu
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia.,Ophthalmology, Department of Surgery, University of Melbourne, Melbourne, Victoria, Australia
| | - Penelope J Allen
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia.,Ophthalmology, Department of Surgery, University of Melbourne, Melbourne, Victoria, Australia
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7
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Allen PJ. Retinal prostheses: Where to from here? Clin Exp Ophthalmol 2021; 49:418-429. [PMID: 34021959 DOI: 10.1111/ceo.13950] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 05/05/2021] [Accepted: 05/09/2021] [Indexed: 11/29/2022]
Abstract
Researchers have been working towards the development of retinal prostheses, so called "bionic eyes" since the 1960s in an effort to restore functional vision to severely visually impaired patients. Groups from all around the world are involved in this research but in particular, groups from the United States, Germany, France, Japan and Australia have conducted clinical trials of these devices and three of these devices have achieved either FDA HDE (U.S. Food and Drug Administration Humanitarian Device Exception) or CE mark approval for commercial production. Despite this, all three of these devices are now not in commercial production. There are many challenges to overcome to develop devices suitable to implant in human patients and then reach commercial distribution. This is an exacting process and many hurdles need to be overcome to reach this point so that leaving the market after achieving this goal is a significant decision. Ongoing research is exploring the possibility of less complicated surgery with better visual processing algorithms to provide more useful visual information for our patients to provide a commercial alternative.
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Affiliation(s)
- Penelope J Allen
- The Centre for Eye Research Australia, East Melbourne, Australia.,Department of Surgery (Ophthalmology), University of Melbourne, Melbourne, Australia.,The Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
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8
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Ophthalmologic Applications. Biomater Sci 2020. [DOI: 10.1016/b978-0-12-816137-1.00072-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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9
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An update on retinal prostheses. Clin Neurophysiol 2019; 131:1383-1398. [PMID: 31866339 DOI: 10.1016/j.clinph.2019.11.029] [Citation(s) in RCA: 84] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 11/13/2019] [Accepted: 11/14/2019] [Indexed: 11/23/2022]
Abstract
Retinal prostheses are designed to restore a basic sense of sight to people with profound vision loss. They require a relatively intact posterior visual pathway (optic nerve, lateral geniculate nucleus and visual cortex). Retinal implants are options for people with severe stages of retinal degenerative disease such as retinitis pigmentosa and age-related macular degeneration. There have now been three regulatory-approved retinal prostheses. Over five hundred patients have been implanted globally over the past 15 years. Devices generally provide an improved ability to localize high-contrast objects, navigate, and perform basic orientation tasks. Adverse events have included conjunctival erosion, retinal detachment, loss of light perception, and the need for revision surgery, but are rare. There are also specific device risks, including overstimulation (which could cause damage to the retina) or delamination of implanted components, but these are very unlikely. Current challenges include how to improve visual acuity, enlarge the field-of-view, and reduce a complex visual scene to its most salient components through image processing. This review encompasses the work of over 40 individual research groups who have built devices, developed stimulation strategies, or investigated the basic physiology underpinning retinal prostheses. Current technologies are summarized, along with future challenges that face the field.
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10
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Bloch E, Luo Y, da Cruz L. Advances in retinal prosthesis systems. Ther Adv Ophthalmol 2019; 11:2515841418817501. [PMID: 30729233 PMCID: PMC6350159 DOI: 10.1177/2515841418817501] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 11/05/2018] [Indexed: 01/18/2023] Open
Abstract
Retinal prosthesis systems have undergone significant advances in the past quarter century, resulting in the development of several different novel surgical and engineering approaches. Encouraging results have demonstrated partial visual restoration, with improvement in both coarse objective function and performance of everyday tasks. To date, four systems have received marketing approval for use in Europe or the United States, with numerous others undergoing preclinical and clinical evaluation, reflecting the established safety profile of these devices for chronic implantation. This progress represents the first notion that the field of visual restorative medicine could offer blind patients a hope of real and measurable benefit. However, there are numerous complex engineering and biophysical obstacles still to be overcome, to reconcile the gap that remains between artificial and natural vision. Current developments in the form of enhanced image processing algorithms and data transfer approaches, combined with emerging nanofabrication and conductive polymerization techniques, herald an exciting and innovative future for retinal prosthetics. This review provides an update of retinal prosthetic systems currently undergoing development and clinical trials while also addressing future challenges in the field, such as the assessment of functional outcomes in ultra-low vision and strategies for tackling existing hardware and software constraints.
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Affiliation(s)
- Edward Bloch
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, London, UK
| | - Yvonne Luo
- NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Lyndon da Cruz
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, London, UK
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11
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Shepherd RK, Villalobos J, Burns O, Nayagam DAX. The development of neural stimulators: a review of preclinical safety and efficacy studies. J Neural Eng 2018; 15:041004. [PMID: 29756600 PMCID: PMC6049833 DOI: 10.1088/1741-2552/aac43c] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Given the rapid expansion of the field of neural stimulation and the rigorous regulatory approval requirements required before these devices can be applied clinically, it is important that there is clarity around conducting preclinical safety and efficacy studies required for the development of this technology. APPROACH The present review examines basic design principles associated with the development of a safe neural stimulator and describes the suite of preclinical safety studies that need to be considered when taking a device to clinical trial. MAIN RESULTS Neural stimulators are active implantable devices that provide therapeutic intervention, sensory feedback or improved motor control via electrical stimulation of neural or neuro-muscular tissue in response to trauma or disease. Because of their complexity, regulatory bodies classify these devices in the highest risk category (Class III), and they are therefore required to go through a rigorous regulatory approval process before progressing to market. The successful development of these devices is achieved through close collaboration across disciplines including engineers, scientists and a surgical/clinical team, and the adherence to clear design principles. Preclinical studies form one of several key components in the development pathway from concept to product release of neural stimulators. Importantly, these studies provide iterative feedback in order to optimise the final design of the device. Key components of any preclinical evaluation include: in vitro studies that are focussed on device reliability and include accelerated testing under highly controlled environments; in vivo studies using animal models of the disease or injury in order to assess efficacy and, given an appropriate animal model, the safety of the technology under both passive and electrically active conditions; and human cadaver and ex vivo studies designed to ensure the device's form factor conforms to human anatomy, to optimise the surgical approach and to develop any specialist surgical tooling required. SIGNIFICANCE The pipeline from concept to commercialisation of these devices is long and expensive; careful attention to both device design and its preclinical evaluation will have significant impact on the duration and cost associated with taking a device through to commercialisation. Carefully controlled in vitro and in vivo studies together with ex vivo and human cadaver trials are key components of a thorough preclinical evaluation of any new neural stimulator.
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Affiliation(s)
- Robert K Shepherd
- Bionics Institute, East Melbourne, Australia. Medical Bionics Department, University of Melbourne, Melbourne, Australia
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12
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Bareket L, Barriga-Rivera A, Zapf MP, Lovell NH, Suaning GJ. Progress in artificial vision through suprachoroidal retinal implants. J Neural Eng 2018; 14:045002. [PMID: 28541930 DOI: 10.1088/1741-2552/aa6cbb] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Retinal implants have proven their ability to restore visual sensation to people with degenerative retinopathy, characterized by photoreceptor cell death and the retina's inability to sense light. Retinal bionics operate by electrically stimulating the surviving neurons in the retina, thus triggering the transfer of visual sensory information to the brain. Suprachoroidal implants were first investigated in Australia in the 1950s. In this approach, the neuromodulation hardware is positioned between the sclera and the choroid, thus providing significant surgical and safety benefits for patients, with the potential to maintain residual vision combined with the artificial input from the device. Here we review the latest advances and state of the art devices for suprachoroidal prostheses, highlight future technologies and discuss challenges and perspectives towards improved rehabilitation of vision.
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Affiliation(s)
- Lilach Bareket
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Australia
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13
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Spencer TC, Fallon JB, Shivdasani MN. Creating virtual electrodes with 2D current steering. J Neural Eng 2018; 15:035002. [DOI: 10.1088/1741-2552/aab1b8] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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14
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Abdallah W, Li W, Weiland J, Humayun M, Ameri H. Implantation of multiple suprachoroidal electrode arrays in rabbits. J Curr Ophthalmol 2018; 30:68-73. [PMID: 29564412 PMCID: PMC5859463 DOI: 10.1016/j.joco.2017.11.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 11/06/2017] [Accepted: 11/10/2017] [Indexed: 11/23/2022] Open
Abstract
Purpose Epiretinal and subretinal prosthesis have been shown to be a valid way to provide some vision to patients with advanced outer retinal degeneration and profound vision loss. However, the field of vision for these patients is markedly limited by the area occupied by the electrode array. In this study, we aimed to evaluate the feasibility of implantation of multiple suprachoroidal electrode arrays in a single eye in order to increase the field of vision in patients implanted with retinal prosthesis. Methods The right eye of seventeen Dutch rabbits (age range, 5–6 months) was used for the study. Multiple inactive custom-made electrode arrays were inserted into the suprachoroidal space (SCS) and animals were followed up for up to 6 months using fundus photography, optical coherence tomography (OCT), and fluorescein angiography (FA). Results It was possible to surgically implant up to 8 electrode arrays in a single eye. None of the rabbits showed any major complications. The electrodes were well tolerated and remained in position in all rabbits. There was no evidence of retinal damage on follow-up exams and FA throughout the study. Conclusion Multiple suprachoroidal electrode array implantation is feasible and may provide a novel approach to increase the field of vision in subjects implanted with retinal prosthesis.
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Affiliation(s)
- Walid Abdallah
- Department of Ophthalmology, USC Roski Eye Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA
| | - Wen Li
- Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI, USA
| | - James Weiland
- Department of Ophthalmology, USC Roski Eye Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA
| | - Mark Humayun
- Department of Ophthalmology, USC Roski Eye Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA
| | - Hossein Ameri
- Department of Ophthalmology, USC Roski Eye Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA
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15
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Abstract
Percutaneous pedestals have been integral to the development of cochlear implants since 1969. By enabling direct electrical access to implanted electrodes or other devices, they allow optimization of control of stimulation strategies. Similarly, technology not validated for implantable use can be safely tested. These advantages have facilitated the development of cochlear implants and also resulted in their inclusion in trials investigating electronic implants developed for other organs. Surgery is straightforward, but post-operative care, in particular, skin-care is crucial to ensure complications are minimized. This review discusses the history of percutaneous pedestal use in cochlear implants and other electronic devices. Surgical technique, aftercare, and complications of surgery are discussed along with possibilities for future development.
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Affiliation(s)
| | - Richard Irving
- a University Hospital Birmingham NHS Foundation Trust , Birmingham B15 2TH , UK
| | - Robert Briggs
- b Royal Victorian Eye and Ear Hospital , East Melbourne , Victoria 3002 , Australia
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16
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Beyeler M, Rokem A, Boynton GM, Fine I. Learning to see again: biological constraints on cortical plasticity and the implications for sight restoration technologies. J Neural Eng 2017; 14:051003. [PMID: 28612755 DOI: 10.1088/1741-2552/aa795e] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The 'bionic eye'-so long a dream of the future-is finally becoming a reality with retinal prostheses available to patients in both the US and Europe. However, clinical experience with these implants has made it apparent that the visual information provided by these devices differs substantially from normal sight. Consequently, the ability of patients to learn to make use of this abnormal retinal input plays a critical role in whether or not some functional vision is successfully regained. The goal of the present review is to summarize the vast basic science literature on developmental and adult cortical plasticity with an emphasis on how this literature might relate to the field of prosthetic vision. We begin with describing the distortion and information loss likely to be experienced by visual prosthesis users. We then define cortical plasticity and perceptual learning, and describe what is known, and what is unknown, about visual plasticity across the hierarchy of brain regions involved in visual processing, and across different stages of life. We close by discussing what is known about brain plasticity in sight restoration patients and discuss biological mechanisms that might eventually be harnessed to improve visual learning in these patients.
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Affiliation(s)
- Michael Beyeler
- Department of Psychology, University of Washington, Seattle, WA, United States of America. Institute for Neuroengineering, University of Washington, Seattle, WA, United States of America. eScience Institute, University of Washington, Seattle, WA, United States of America
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17
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Barriga-Rivera A, Guo T, Yang CY, Abed AA, Dokos S, Lovell NH, Morley JW, Suaning GJ. High-amplitude electrical stimulation can reduce elicited neuronal activity in visual prosthesis. Sci Rep 2017; 7:42682. [PMID: 28209965 PMCID: PMC5314337 DOI: 10.1038/srep42682] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 01/13/2017] [Indexed: 12/13/2022] Open
Abstract
Retinal electrostimulation is promising a successful therapy to restore functional vision. However, a narrow stimulating current range exists between retinal neuron excitation and inhibition which may lead to misperformance of visual prostheses. As the conveyance of representation of complex visual scenes may require neighbouring electrodes to be activated simultaneously, electric field summation may contribute to reach this inhibitory threshold. This study used three approaches to assess the implications of relatively high stimulating conditions in visual prostheses: (1) in vivo, using a suprachoroidal prosthesis implanted in a feline model, (2) in vitro through electrostimulation of murine retinal preparations, and (3) in silico by computing the response of a population of retinal ganglion cells. Inhibitory stimulating conditions led to diminished cortical activity in the cat. Stimulus-response relationships showed non-monotonic profiles to increasing stimulating current. This was observed in vitro and in silico as the combined response of groups of neurons (close to the stimulating electrode) being inhibited at certain stimulating amplitudes, whilst other groups (far from the stimulating electrode) being recruited. These findings may explain the halo-like phosphene shapes reported in clinical trials and suggest that simultaneous stimulation in retinal prostheses is limited by the inhibitory threshold of the retinal ganglion cells.
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Affiliation(s)
| | - Tianruo Guo
- Graduate School of Biomedical Engineering, UNSW, Sydney, 2052, Australia
| | - Chih-Yu Yang
- Graduate School of Biomedical Engineering, UNSW, Sydney, 2052, Australia
| | - Amr Al Abed
- Graduate School of Biomedical Engineering, UNSW, Sydney, 2052, Australia
| | - Socrates Dokos
- Graduate School of Biomedical Engineering, UNSW, Sydney, 2052, Australia
| | - Nigel H Lovell
- Graduate School of Biomedical Engineering, UNSW, Sydney, 2052, Australia
| | - John W Morley
- School of Medicine, Western Sydney University, Sydney, 2753, Australia.,School of Medical Science, UNSW, Sydney, 2052, Australia
| | - Gregg J Suaning
- Graduate School of Biomedical Engineering, UNSW, Sydney, 2052, Australia.,Sydney Medical School, University of Sydney, 2000, Australia
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18
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Lewis PM, Ayton LN, Guymer RH, Lowery AJ, Blamey PJ, Allen PJ, Luu CD, Rosenfeld JV. Advances in implantable bionic devices for blindness: a review. ANZ J Surg 2016; 86:654-9. [PMID: 27301783 PMCID: PMC5132139 DOI: 10.1111/ans.13616] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 03/03/2016] [Accepted: 03/17/2016] [Indexed: 02/02/2023]
Abstract
Since the 1950s, vision researchers have been working towards the ambitious goal of restoring a functional level of vision to the blind via electrical stimulation of the visual pathways. Groups based in Australia, USA, Germany, France and Japan report progress in the translation of retinal visual prosthetics from the experimental to clinical domains, with two retinal visual prostheses having recently received regulatory approval for clinical use. Regulatory approval for cortical visual prostheses is yet to be obtained; however, several groups report plans to conduct clinical trials in the near future, building upon the seminal clinical studies of Brindley and Dobelle. In this review, we discuss the general principles of visual prostheses employing electrical stimulation of the visual pathways, focusing on the retina and visual cortex as the two most extensively studied stimulation sites. We also discuss the surgical and functional outcomes reported to date for retinal and cortical prostheses, concluding with a brief discussion of novel developments in this field and an outlook for the future.
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Affiliation(s)
- Philip M Lewis
- Department of Neurosurgery, Alfred Hospital, Melbourne, Victoria, Australia.,Department of Surgery, Central Clinical School, Monash University, Melbourne, Victoria, Australia.,Monash Vision Group, Faculty of Engineering, Monash University, Melbourne, Victoria, Australia.,Monash Institute of Medical Engineering, Monash University, Melbourne, Victoria, Australia
| | - Lauren N Ayton
- Centre for Eye Research Australia, The Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia.,Department of Ophthalmology, The University of Melbourne, Melbourne, Victoria, Australia.,Department of Surgery, The University of Melbourne, Melbourne, Victoria, Australia
| | - Robyn H Guymer
- Centre for Eye Research Australia, The Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia.,Department of Ophthalmology, The University of Melbourne, Melbourne, Victoria, Australia.,Department of Surgery, The University of Melbourne, Melbourne, Victoria, Australia
| | - Arthur J Lowery
- Monash Vision Group, Faculty of Engineering, Monash University, Melbourne, Victoria, Australia.,Monash Institute of Medical Engineering, Monash University, Melbourne, Victoria, Australia
| | - Peter J Blamey
- Bionics Institute, Department of Medical Bionics, The University of Melbourne, Melbourne, Victoria, Australia
| | - Penelope J Allen
- Centre for Eye Research Australia, The Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia.,Department of Ophthalmology, The University of Melbourne, Melbourne, Victoria, Australia.,Department of Surgery, The University of Melbourne, Melbourne, Victoria, Australia
| | - Chi D Luu
- Centre for Eye Research Australia, The Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia.,Department of Ophthalmology, The University of Melbourne, Melbourne, Victoria, Australia.,Department of Surgery, The University of Melbourne, Melbourne, Victoria, Australia
| | - Jeffrey V Rosenfeld
- Department of Neurosurgery, Alfred Hospital, Melbourne, Victoria, Australia.,Department of Surgery, Central Clinical School, Monash University, Melbourne, Victoria, Australia.,Monash Vision Group, Faculty of Engineering, Monash University, Melbourne, Victoria, Australia.,Monash Institute of Medical Engineering, Monash University, Melbourne, Victoria, Australia.,F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA
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19
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Barnes N, Scott AF, Lieby P, Petoe MA, McCarthy C, Stacey A, Ayton LN, Sinclair NC, Shivdasani MN, Lovell NH, McDermott HJ, Walker JG. Vision function testing for a suprachoroidal retinal prosthesis: effects of image filtering. J Neural Eng 2016; 13:036013. [DOI: 10.1088/1741-2560/13/3/036013] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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20
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Wong YT, Halupka K, Kameneva T, Cloherty SL, Grayden DB, Burkitt AN, Meffin H, Shivdasani MN. Spectral distribution of local field potential responses to electrical stimulation of the retina. J Neural Eng 2016; 13:036003. [DOI: 10.1088/1741-2560/13/3/036003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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21
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Moisseiev E, Loewenstein A, Yiu G. The suprachoroidal space: from potential space to a space with potential. Clin Ophthalmol 2016; 10:173-8. [PMID: 26869750 PMCID: PMC4734808 DOI: 10.2147/opth.s89784] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Recent advances have made it possible to image the suprachoroidal space, and the understanding of its clinical applications is currently being greatly expanded. This opinion piece covers the advances in imaging techniques that enable the demonstration of the suprachoroidal space, and its implication in various retinal pathologies. It also reviews its potential uses as a route for drug delivery for the treatment of retinal diseases, and its use in innovative surgical techniques. Current research is leading the way for the suprachoroidal space to be an aspect of retinal disease diagnosis, monitoring, medical treatment, and surgical manipulation.
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Affiliation(s)
- Elad Moisseiev
- UC Davis Eye Center, University of California Davis, Sacramento, CA, USA; Ophthalmology Department, Tel Aviv Medical Center, Tel Aviv, Israel; Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Anat Loewenstein
- Ophthalmology Department, Tel Aviv Medical Center, Tel Aviv, Israel; Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Glenn Yiu
- UC Davis Eye Center, University of California Davis, Sacramento, CA, USA
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22
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Barriga-Rivera A, Eiber CD, Dodds CWD, Fung AT, Tatarinoff V, Lovell NH, Suaning GJ. Electrically evoked potentials in an ovine model for the evaluation of visual prosthesis efficacy. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2016; 2015:3359-62. [PMID: 26737012 DOI: 10.1109/embc.2015.7319112] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Visual prostheses are becoming a reality as a therapy to restore functional vision to the blind. New stimulation strategies and novel electrode designs are contributing to accelerate the development of such devices triggering the interest of scientists, clinicians and the blind community worldwide. In this scenario, there is a need for large animal models that are suitable for preclinical testing of retinal neuroprostheses. This study presents an electrophysiology assessment of an ovine model for single and simultaneous electrode stimulation from the suprachoroidal space, using symmetric biphasic current pulses with a monopolar return configuration. Visually and electrically evoked potentials were recorded using supradural surface electrodes, showing charge thresholds comparable to those in humans. This model represents an alternative to feline or canine models with analogous activation levels and an eye anatomy similar to that of humans.
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23
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Fox K, Meffin H, Burns O, Abbott CJ, Allen PJ, Opie NL, McGowan C, Yeoh J, Ahnood A, Luu CD, Cicione R, Saunders AL, McPhedran M, Cardamone L, Villalobos J, Garrett DJ, Nayagam DAX, Apollo NV, Ganesan K, Shivdasani MN, Stacey A, Escudie M, Lichter S, Shepherd RK, Prawer S. Development of a Magnetic Attachment Method for Bionic Eye Applications. Artif Organs 2015; 40:E12-24. [DOI: 10.1111/aor.12582] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Kate Fox
- School of Physics; University of Melbourne; Melbourne Victoria Australia
- School of Aerospace, Mechanical and Manufacturing Engineering; RMIT University; Melbourne Victoria Australia
| | - Hamish Meffin
- Department of Electrical and Electronic Engineering; University of Melbourne; Melbourne Victoria Australia
- National Vision Research Institute; Australian College of Optometry; Melbourne Victoria Australia
| | - Owen Burns
- The Bionics Institute; Melbourne Victoria Australia
| | - Carla J. Abbott
- Centre for Eye Research Australia (CERA) Royal Victorian Eye and Ear Hospital; Melbourne Victoria Australia
| | - Penelope J. Allen
- Centre for Eye Research Australia (CERA) Royal Victorian Eye and Ear Hospital; Melbourne Victoria Australia
| | - Nicholas L. Opie
- Centre for Eye Research Australia (CERA) Royal Victorian Eye and Ear Hospital; Melbourne Victoria Australia
| | | | - Jonathan Yeoh
- Centre for Eye Research Australia (CERA) Royal Victorian Eye and Ear Hospital; Melbourne Victoria Australia
| | - Arman Ahnood
- School of Physics; University of Melbourne; Melbourne Victoria Australia
| | - Chi D. Luu
- Centre for Eye Research Australia (CERA) Royal Victorian Eye and Ear Hospital; Melbourne Victoria Australia
| | - Rosemary Cicione
- School of Physics; University of Melbourne; Melbourne Victoria Australia
| | | | | | | | | | - David J. Garrett
- School of Physics; University of Melbourne; Melbourne Victoria Australia
- The Bionics Institute; Melbourne Victoria Australia
| | | | - Nicholas V. Apollo
- School of Physics; University of Melbourne; Melbourne Victoria Australia
- The Bionics Institute; Melbourne Victoria Australia
| | - Kumaravelu Ganesan
- School of Physics; University of Melbourne; Melbourne Victoria Australia
| | | | - Alastair Stacey
- School of Physics; University of Melbourne; Melbourne Victoria Australia
| | - Mathilde Escudie
- School of Physics; University of Melbourne; Melbourne Victoria Australia
| | - Samantha Lichter
- School of Physics; University of Melbourne; Melbourne Victoria Australia
| | | | - Steven Prawer
- School of Physics; University of Melbourne; Melbourne Victoria Australia
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24
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Slater KD, Sinclair NC, Nelson TS, Blamey PJ, McDermott HJ. neuroBi: A Highly Configurable Neurostimulator for a Retinal Prosthesis and Other Applications. IEEE JOURNAL OF TRANSLATIONAL ENGINEERING IN HEALTH AND MEDICINE-JTEHM 2015; 3:3800111. [PMID: 27170910 PMCID: PMC4848081 DOI: 10.1109/jtehm.2015.2455507] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 03/26/2015] [Accepted: 07/02/2015] [Indexed: 11/10/2022]
Abstract
To evaluate the efficacy of a suprachoroidal retinal prosthesis, a highly configurable external neurostimulator is required. In order to meet functional and safety specifications, it was necessary to develop a custom device. A system is presented which can deliver charge-balanced, constant-current biphasic pulses, with widely adjustable parameters, to arbitrary configurations of output electrodes. This system is shown to be effective in eliciting visual percepts in a patient with approximately 20 years of light perception vision only due to retinitis pigmentosa, using an electrode array implanted in the suprachoroidal space of the eye. The flexibility of the system also makes it suitable for use in a number of other emerging clinical neurostimulation applications, including epileptic seizure suppression and closed-loop deep brain stimulation. Clinical trial registration number NCT01603576 (www.clinicaltrials.gov).
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25
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Nayagam DAX, Durmo I, McGowan C, Williams RA, Shepherd RK. Techniques for processing eyes implanted with a retinal prosthesis for localized histopathological analysis: Part 2 Epiretinal implants with retinal tacks. J Vis Exp 2015. [PMID: 25798628 PMCID: PMC4370214 DOI: 10.3791/52348] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Retinal prostheses for the treatment of certain forms of blindness are gaining traction in clinical trials around the world with commercial devices currently entering the market. In order to evaluate the safety of these devices, in preclinical studies, reliable techniques are needed. However, the hard metal components utilised in some retinal implants are not compatible with traditional histological processes, particularly in consideration for the delicate nature of the surrounding tissue. Here we describe techniques for assessing the health of the eye directly adjacent to a retinal implant secured epiretinally with a metal tack. Retinal prostheses feature electrode arrays in contact with eye tissue. The most commonly used location for implantation is the epiretinal location (posterior chamber of the eye), where the implant is secured to the retina with a metal tack that penetrates all the layers of the eye. Previous methods have not been able to assess the proximal ocular tissue with the tack in situ, due to the inability of traditional histological techniques to cut metal objects. Consequently, it has been difficult to assess localized damage, if present, caused by tack insertion. Therefore, we developed a technique for visualizing the tissue around a retinal tack and implant. We have modified an established technique, used for processing and visualizing hard bony tissue around a cochlear implant, for the soft delicate tissues of the eye. We orientated and embedded the fixed eye tissue, including the implant and retinal tack, in epoxy resin, to stabilise and protect the structure of the sample. Embedded samples were then ground, polished, stained, and imaged under various magnifications at incremental depths through the sample. This technique allowed the reliable assessment of eye tissue integrity and cytoarchitecture adjacent to the metal tack.
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Affiliation(s)
- David A X Nayagam
- Bionics Institute; Department of Pathology, The University of Melbourne;
| | | | | | - Richard A Williams
- Department of Pathology, The University of Melbourne; Department of Anatomical Pathology, St Vincent's Hospital Melbourne
| | - Robert K Shepherd
- Bionics Institute; Medical Bionics Department, The University of Melbourne
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26
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Ayton LN, Blamey PJ, Guymer RH, Luu CD, Nayagam DAX, Sinclair NC, Shivdasani MN, Yeoh J, McCombe MF, Briggs RJ, Opie NL, Villalobos J, Dimitrov PN, Varsamidis M, Petoe MA, McCarthy CD, Walker JG, Barnes N, Burkitt AN, Williams CE, Shepherd RK, Allen PJ. First-in-human trial of a novel suprachoroidal retinal prosthesis. PLoS One 2014; 9:e115239. [PMID: 25521292 PMCID: PMC4270734 DOI: 10.1371/journal.pone.0115239] [Citation(s) in RCA: 199] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 11/18/2014] [Indexed: 11/19/2022] Open
Abstract
Retinal visual prostheses (“bionic eyes”) have the potential to restore vision to blind or profoundly vision-impaired patients. The medical bionic technology used to design, manufacture and implant such prostheses is still in its relative infancy, with various technologies and surgical approaches being evaluated. We hypothesised that a suprachoroidal implant location (between the sclera and choroid of the eye) would provide significant surgical and safety benefits for patients, allowing them to maintain preoperative residual vision as well as gaining prosthetic vision input from the device. This report details the first-in-human Phase 1 trial to investigate the use of retinal implants in the suprachoroidal space in three human subjects with end-stage retinitis pigmentosa. The success of the suprachoroidal surgical approach and its associated safety benefits, coupled with twelve-month post-operative efficacy data, holds promise for the field of vision restoration. Trial Registration Clinicaltrials.gov NCT01603576
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Affiliation(s)
- Lauren N. Ayton
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
- * E-mail:
| | - Peter J. Blamey
- Bionics Institute, East Melbourne, Australia
- Department of Medical Bionics, University of Melbourne, East Melbourne, Australia
| | - Robyn H. Guymer
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
| | - Chi D. Luu
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
| | - David A. X. Nayagam
- Bionics Institute, East Melbourne, Australia
- Department of Pathology, University of Melbourne, St Vincent's Hospital Melbourne, Fitzroy, Australia
| | | | - Mohit N. Shivdasani
- Bionics Institute, East Melbourne, Australia
- Department of Medical Bionics, University of Melbourne, East Melbourne, Australia
| | - Jonathan Yeoh
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
| | - Mark F. McCombe
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
| | - Robert J. Briggs
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
| | - Nicholas L. Opie
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
| | | | - Peter N. Dimitrov
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
| | - Mary Varsamidis
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
| | | | - Chris D. McCarthy
- NICTA, Computer Vision Research Group, Canberra, Australia
- National Institute for Mental Health Research, Australian National University, Canberra, Australia
| | - Janine G. Walker
- NICTA, Computer Vision Research Group, Canberra, Australia
- National Institute for Mental Health Research, Australian National University, Canberra, Australia
| | - Nick Barnes
- NICTA, Computer Vision Research Group, Canberra, Australia
- National Institute for Mental Health Research, Australian National University, Canberra, Australia
| | - Anthony N. Burkitt
- Bionics Institute, East Melbourne, Australia
- Centre for Neural Engineering, University of Melbourne, National Information and Communications Technology Australia (NICTA), Ltd., Melbourne, Australia
| | | | - Robert K. Shepherd
- Bionics Institute, East Melbourne, Australia
- Department of Medical Bionics, University of Melbourne, East Melbourne, Australia
| | - Penelope J. Allen
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
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27
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Chapter 1 - Restoring Vision to the Blind: The New Age of Implanted Visual Prostheses. Transl Vis Sci Technol 2014; 3:3. [PMID: 25653887 PMCID: PMC4314997 DOI: 10.1167/tvst.3.7.3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 10/27/2014] [Indexed: 11/24/2022] Open
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28
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Affiliation(s)
- Hossein Ameri
- Department of Ophthalmology, USC Eye Institute, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA
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29
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Leung RT, Nayagam DAX, Williams RA, Allen PJ, Salinas-La Rosa CM, Luu CD, Shivdasani MN, Ayton LN, Basa M, Yeoh J, Saunders AL, Shepherd RK, Williams CE. Safety and efficacy of explanting or replacing suprachoroidal electrode arrays in a feline model. Clin Exp Ophthalmol 2014; 43:247-58. [PMID: 25196241 DOI: 10.1111/ceo.12428] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 08/24/2014] [Indexed: 11/26/2022]
Abstract
BACKGROUND A key requirement for retinal prostheses is the ability for safe removal or replacement. We examined whether suprachoroidal electrode arrays can be removed or replaced after implantation. METHODS Suprachoroidal electrode arrays were unilaterally implanted into 13 adult felines. After 1 month, arrays were surgically explanted (n = 6), replaced (n = 5) or undisturbed (n = 2). The retina was assessed periodically using fundus photography and optical coherence tomography. Three months after the initial implantation, the function of replaced or undisturbed arrays was assessed by measuring the responses of the visual cortex to retinal electrical stimulation. The histopathology of tissues surrounding the implant was examined. RESULTS Array explantation or replacement was successful in all cases. Fundus photography showed localized disruption to the tapetum lucidum near the implant's tip in seven subjects following implantation. Although optical coherence tomography showed localized retinal changes, there were no widespread statistically significant differences in the thickness of the retinal layers or choroid. The distance between the electrodes and retina increased after device replacement but returned to control values within eight weeks (P < 0.03). Staphylomas developed near the scleral wound in five animals after device explantation. Device replacement did not alter the cortical evoked potential threshold. Histopathology showed localized outer nuclear layer thinning, tapetal disruption and pseudo-rosette formation, but the overall retinal morphology was preserved. CONCLUSIONS It is feasible to remove or replace conformable medical grade silicone electrode arrays implanted suprachoroidally. The scleral wound requires careful closure to minimize the risk of staphylomas.
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Affiliation(s)
- Ronald T Leung
- Bionics Institute, Melbourne, Victoria, Australia; Department of Pathology, The University of Melbourne, Melbourne, Victoria, Australia
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30
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Nayagam DAX, Williams RA, Allen PJ, Shivdasani MN, Luu CD, Salinas-LaRosa CM, Finch S, Ayton LN, Saunders AL, McPhedran M, McGowan C, Villalobos J, Fallon JB, Wise AK, Yeoh J, Xu J, Feng H, Millard R, McWade M, Thien PC, Williams CE, Shepherd RK. Chronic electrical stimulation with a suprachoroidal retinal prosthesis: a preclinical safety and efficacy study. PLoS One 2014; 9:e97182. [PMID: 24853376 PMCID: PMC4031073 DOI: 10.1371/journal.pone.0097182] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 04/16/2014] [Indexed: 11/23/2022] Open
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 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.
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Affiliation(s)
- David A. X. Nayagam
- Bionics Institute, East Melbourne, Victoria, Australia
- Department of Pathology, University of Melbourne, Parkville, Victoria, Australia
- * E-mail:
| | - Richard A. Williams
- Department of Pathology, University of Melbourne, Parkville, Victoria, Australia
- Department of Anatomical Pathology, St Vincent’s Hospital Melbourne, Fitzroy, Victoria, Australia
| | - Penelope J. Allen
- Centre for Eye Research Australia, University of Melbourne, East Melbourne, Victoria, Australia
- Department of Ophthalmology, The University of Melbourne, East Melbourne, Victoria, Australia
| | - Mohit N. Shivdasani
- Bionics Institute, East Melbourne, Victoria, Australia
- Medical Bionics Department, University of Melbourne, East Melbourne, Victoria, Australia
| | - Chi D. Luu
- Centre for Eye Research Australia, University of Melbourne, East Melbourne, Victoria, Australia
| | - Cesar M. Salinas-LaRosa
- Department of Anatomical Pathology, St Vincent’s Hospital Melbourne, Fitzroy, Victoria, Australia
| | - Sue Finch
- Statistical Consulting Centre, The University of Melbourne, Parkville, Victoria, Australia
| | - Lauren N. Ayton
- Centre for Eye Research Australia, University of Melbourne, East Melbourne, Victoria, Australia
| | | | | | - Ceara McGowan
- Bionics Institute, East Melbourne, Victoria, Australia
| | | | - James B. Fallon
- Bionics Institute, East Melbourne, Victoria, Australia
- Medical Bionics Department, University of Melbourne, East Melbourne, Victoria, Australia
| | - Andrew K. Wise
- Bionics Institute, East Melbourne, Victoria, Australia
- Department of Otolaryngology, The University of Melbourne, East Melbourne, Victoria, Australia
- Medical Bionics Department, University of Melbourne, East Melbourne, Victoria, Australia
| | - Jonathan Yeoh
- Centre for Eye Research Australia, University of Melbourne, East Melbourne, Victoria, Australia
- Department of Ophthalmology, The University of Melbourne, East Melbourne, Victoria, Australia
| | - Jin Xu
- Bionics Institute, East Melbourne, Victoria, Australia
- The HEARing Cooperative Research Centre, The University of Melbourne, East Melbourne, Victoria, Australia
- Department of Otolaryngology, The University of Melbourne, East Melbourne, Victoria, Australia
| | - Helen Feng
- Bionics Institute, East Melbourne, Victoria, Australia
- Department of Otolaryngology, The University of Melbourne, East Melbourne, Victoria, Australia
| | | | - Melanie McWade
- Bionics Institute, East Melbourne, Victoria, Australia
- Biomedical Engineering Department, Vanderbilt University, Nashville, Tennessee, United States of America
| | | | - Chris E. Williams
- Bionics Institute, East Melbourne, Victoria, Australia
- Department of Pathology, University of Melbourne, Parkville, Victoria, Australia
- Medical Bionics Department, University of Melbourne, East Melbourne, Victoria, Australia
| | - Robert K. Shepherd
- Bionics Institute, East Melbourne, Victoria, Australia
- Medical Bionics Department, University of Melbourne, East Melbourne, Victoria, Australia
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