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Nanegrungsunk O, Au A, Sarraf D, Sadda SR. New frontiers of retinal therapeutic intervention: a critical analysis of novel approaches. Ann Med 2022; 54:1067-1080. [PMID: 35467460 PMCID: PMC9045775 DOI: 10.1080/07853890.2022.2066169] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
A recent wave of pharmacologic and technologic innovations has revolutionized our management of retinal diseases. Many of these advancements have demonstrated efficacy and can increase the quality of life while potentially reducing complications and decreasing the burden of care for patients. Some advances, such as longer-acting anti-vascular endothelial growth factor agents, port delivery systems, gene therapy, and retinal prosthetics have been approved by the US Food and Drug Administration, and are available for clinical use. Countless other therapeutics are in various stages of development, promising a bright future for further improvements in the management of the retinal disease. Herein, we have highlighted several important novel therapies and therapeutic approaches and examine the opportunities and limitations offered by these innovations at the new frontier. KEY MESSAGESNumerous pharmacologic and technologic advancements have been emerging, providing a higher treatment efficacy while decreasing the burden and associated side effects.Anti-vascular endothelial growth factor (anti-VEGF) and its longer-acting agents have dramatically improved visual outcomes and have become a mainstay treatment in various retinal diseases.Gene therapy and retinal prosthesis implantation in the treatment of congenital retinal dystrophy can accomplish the partial restoration of vision and improved daily function in patients with blindness, an unprecedented success in the field of retina.
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Affiliation(s)
- Onnisa Nanegrungsunk
- Doheny Eye Institute, Pasadena, CA, USA.,Department of Ophthalmology, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, CA, USA.,Retina Division, Department of Ophthalmology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Adrian Au
- Stein Eye Institute, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, CA, USA
| | - David Sarraf
- Stein Eye Institute, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, CA, USA
| | - Srinivas R Sadda
- Doheny Eye Institute, Pasadena, CA, USA.,Department of Ophthalmology, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, CA, USA
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2
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Shi L, Jiang Y, Zheng N, Cheng JX, Yang C. High-precision neural stimulation through optoacoustic emitters. NEUROPHOTONICS 2022; 9:032207. [PMID: 35355658 PMCID: PMC8941197 DOI: 10.1117/1.nph.9.3.032207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 02/25/2022] [Indexed: 05/03/2023]
Abstract
Neuromodulation poses an invaluable role in deciphering neural circuits and exploring clinical treatment of neurological diseases. Optoacoustic neuromodulation is an emerging modality benefiting from the merits of ultrasound with high penetration depth as well as the merits of photons with high spatial precision. We summarize recent development in a variety of optoacoustic platforms for neural modulation, including fiber, film, and nanotransducer-based devices, highlighting the key advantages of each platform. The possible mechanisms and main barriers for optoacoustics as a viable neuromodulation tool are discussed. Future directions in fundamental and translational research are proposed.
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Affiliation(s)
- Linli Shi
- Boston University, Department of Chemistry, Boston, Massachusetts, United States
| | - Ying Jiang
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Nan Zheng
- Boston University, Division of Materials Science and Engineering, Boston, Massachusetts, United States
| | - Ji-Xin Cheng
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Boston University, Department of Electrical and Computer Engineering, Boston, Massachusetts, United States
- Address all correspondence to Chen Yang, ; Ji-Xin Cheng,
| | - Chen Yang
- Boston University, Department of Chemistry, Boston, Massachusetts, United States
- Boston University, Department of Electrical and Computer Engineering, Boston, Massachusetts, United States
- Address all correspondence to Chen Yang, ; Ji-Xin Cheng,
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3
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Fauvel T, Chalk M. Human-in-the-loop optimization of visual prosthetic stimulation. J Neural Eng 2022; 19. [PMID: 35667363 DOI: 10.1088/1741-2552/ac7615] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 06/06/2022] [Indexed: 11/12/2022]
Abstract
Retinal prostheses are a promising strategy to restore sight to patients with retinal degenerative diseases. These devices compensate for the loss of photoreceptors by electrically stimulating neurons in the retina. Currently, the visual function that can be recovered with such devices is very limited. This is due, in part, to current spread, unintended axonal activation, and the limited resolution of existing devices. Here we show, using a recent model of prosthetic vision, that optimizing how visual stimuli are encoded by the device can help overcome some of these limitations, leading to dramatic improvements in visual perception. APPROACH We propose a strategy to do this in practice, using patients' feedback in a visual task. The main challenge of our approach comes from the fact that, typically, one only has access to a limited number of noisy responses from patients. We propose two ways to deal with this: first, we use a model of prosthetic vision to constrain and simplify the optimization. We show that, if one knew the parameters of this model for a given patient, it would be possible to greatly improve their perceptual performance. Second we propose a preferential Bayesian optimization to efficiently learn these model parameters for each patient, using minimal trials. MAIN RESULTS To test our approach, we presented healthy subjects with visual stimuli generated by a recent model of prosthetic vision, to replicate the perceptual experience of patients fitted with an implant. Our optimization procedure led to significant and robust improvements in perceived image quality, that transferred to increased performance in other tasks. SIGNIFICANCE Importantly, our strategy is agnostic to the type of prosthesis and thus could readily be implemented in existing implants.
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Affiliation(s)
- Tristan Fauvel
- Institut de la Vision, INSERM, 17 Rue Moreau, Paris, Île-de-France, 75014, FRANCE
| | - Matthew Chalk
- Institut de l a Vision, INSERM, 17 Rue Moreau, Paris, 75014, FRANCE
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Shi L, Jiang Y, Fernandez FR, Chen G, Lan L, Man HY, White JA, Cheng JX, Yang C. Non-genetic photoacoustic stimulation of single neurons by a tapered fiber optoacoustic emitter. LIGHT, SCIENCE & APPLICATIONS 2021; 10:143. [PMID: 34257273 PMCID: PMC8277806 DOI: 10.1038/s41377-021-00580-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 06/09/2021] [Accepted: 06/21/2021] [Indexed: 05/19/2023]
Abstract
Neuromodulation at high spatial resolution poses great significance in advancing fundamental knowledge in the field of neuroscience and offering novel clinical treatments. Here, we developed a tapered fiber optoacoustic emitter (TFOE) generating an ultrasound field with a high spatial precision of 39.6 µm, enabling optoacoustic activation of single neurons or subcellular structures, such as axons and dendrites. Temporally, a single acoustic pulse of sub-microsecond converted by the TFOE from a single laser pulse of 3 ns is shown as the shortest acoustic stimuli so far for successful neuron activation. The precise ultrasound generated by the TFOE enabled the integration of the optoacoustic stimulation with highly stable patch-clamp recording on single neurons. Direct measurements of the electrical response of single neurons to acoustic stimulation, which is difficult for conventional ultrasound stimulation, have been demonstrated. By coupling TFOE with ex vivo brain slice electrophysiology, we unveil cell-type-specific responses of excitatory and inhibitory neurons to acoustic stimulation. These results demonstrate that TFOE is a non-genetic single-cell and sub-cellular modulation technology, which could shed new insights into the mechanism of ultrasound neurostimulation.
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Affiliation(s)
- Linli Shi
- Department of Chemistry, Boston University, 580 Commonwealth Avenue, Boston, MA, 02215, USA
| | - Ying Jiang
- Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, MA, 02215, USA
| | - Fernando R Fernandez
- Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, MA, 02215, USA
- Center for Systems Neuroscience, Boston University, 610 Commonwealth Ave, Boston, MA, 02215, USA
- Neurophotonics Center, Photonics Center, Boston University, 8 St. Mary's Street, Boston, MA, 02215, USA
| | - Guo Chen
- Department of Electrical and Computer Engineering, 8 St. Mary's Street, Boston, MA, 02215, USA
| | - Lu Lan
- Department of Electrical and Computer Engineering, 8 St. Mary's Street, Boston, MA, 02215, USA
| | - Heng-Ye Man
- Center for Systems Neuroscience, Boston University, 610 Commonwealth Ave, Boston, MA, 02215, USA
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA, 02215, USA
| | - John A White
- Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, MA, 02215, USA
- Center for Systems Neuroscience, Boston University, 610 Commonwealth Ave, Boston, MA, 02215, USA
- Neurophotonics Center, Photonics Center, Boston University, 8 St. Mary's Street, Boston, MA, 02215, USA
| | - Ji-Xin Cheng
- Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, MA, 02215, USA.
- Department of Electrical and Computer Engineering, 8 St. Mary's Street, Boston, MA, 02215, USA.
| | - Chen Yang
- Department of Chemistry, Boston University, 580 Commonwealth Avenue, Boston, MA, 02215, USA.
- Department of Electrical and Computer Engineering, 8 St. Mary's Street, Boston, MA, 02215, USA.
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5
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Abbasi B, Rizzo JF. Advances in Neuroscience, Not Devices, Will Determine the Effectiveness of Visual Prostheses. Semin Ophthalmol 2021; 36:168-175. [PMID: 33734937 DOI: 10.1080/08820538.2021.1887902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Background: Innovations in engineering and neuroscience have enabled the development of sophisticated visual prosthetic devices. In clinical trials, these devices have provided visual acuities as high as 20/460, enabled coarse navigation, and even allowed for reading of short words. However, long-term commercial viability arguably rests on attaining even better vision and more definitive improvements in tasks of daily living and quality of life. Purpose: Here we review technological and biological obstacles in the implementation of visual prosthetics. Conclusions: Research in the visual prosthetic field has tackled significant technical challenges, including biocompatibility, signal spread through neural tissue, and inadvertent activation of passing axons; however, significant gaps in knowledge remain in the realm of neuroscience, including the neural code of vision and visual plasticity. We assert that further optimization of prosthetic devices alone will not provide markedly improved visual outcomes without significant advances in our understanding of neuroscience.
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Affiliation(s)
- Bardia Abbasi
- Neuro-Ophthalmology Service, Department of Ophthalmology, Massachusetts Eye and Ear and Harvard Medical School, Boston, MA, USA
| | - Joseph F Rizzo
- Neuro-Ophthalmology Service, Department of Ophthalmology, Massachusetts Eye and Ear and Harvard Medical School, Boston, MA, USA
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Choi KE, Anh VTQ, Kim JT, Yun C, Cha S, Ahn J, Goo YS, Kim SW. An experimental pig model with outer retinal degeneration induced by temporary intravitreal loading of N-methyl-N-nitrosourea during vitrectomy. Sci Rep 2021; 11:258. [PMID: 33420119 PMCID: PMC7794530 DOI: 10.1038/s41598-020-79437-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 12/08/2020] [Indexed: 01/19/2023] Open
Abstract
We aimed to develop an outer retinal degeneration pig model induced by temporary intravitreal loading of N-methyl-N-nitrosourea (MNU) during vitrectomy. In a preliminary experiment involving 5 mini-pig cases to determine the appropriate concentration of MNU, the vitreous cavity of each eye was filled with 4, 8, 10, 12, or 16 mg/mL MNU for 10 min, which was then replaced with a balanced salt solution. Multimodal examinations including spectral-domain optical coherence tomography (OCT) images and full-field electroretinography (ffERG) were obtained at baseline and week 2, week 6, and week 12. The retinal degeneration was classified according to the amplitudes of a dark adaptive (DA) 10.0 a-wave amplitude. The degree of moderate retinal degeneration was defined as DA 10.0 a-wave amplitude ≥ 10% and < 60% of baseline amplitude. The degree of severe degeneration was defined as DA 10.0 a-wave amplitude < 10% of baseline amplitude, noise, or flat signal. Hematoxylin and eosin staining and immunohistochemistry were performed at week 12. The main experiments were conducted first with 10 cases of 5 mg/mL and later with 13 cases of 10 mg/mL. In the preliminary experiment, degree of outer retinal degeneration increased with MNU concentration. Use of 4, 8, 10, 12, and 16 mg/mL MNU showed no, moderate, severe, severe, and atrophic changes, respectively. In the main experiments, there were 9 cases of moderate retinal degeneration and 1 case of severe degeneration in 5 mg/mL MNU group. Two cases of moderate degeneration and 11 of severe degeneration were recorded in 10 mg/mL group. Mean thickness of total retina, inner nuclear layer, and outer nuclear layer decreased at week 2 in both groups. The mean amplitudes on ffERG decreased at week 2. The ffERG and OCT findings did not change from week 2 to week 6 or week 12. The results of staining supported those of ffERG and OCT. Temporal MNU loading in a vitrectomized pig-eye model induced customized outer retinal degeneration with changing the concentration of MNU.
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Affiliation(s)
- Kwang-Eon Choi
- Department of Ophthalmology, Korea University College of Medicine, Seoul, South Korea
| | - Vu Thi Que Anh
- Department of Ophthalmology, Hanoi Medical University, Hanoi, Vietnam
| | - Jee Taek Kim
- Department of Ophthalmology, Chung-Ang University College of Medicine, Seoul, South Korea
| | - Cheolmin Yun
- Department of Ophthalmology, Korea University College of Medicine, Seoul, South Korea
| | - Seongkwang Cha
- Department of Physiology, Chungbuk National University College of Medicine, Cheongju, South Korea
| | - Jungryul Ahn
- Department of Physiology, Chungbuk National University College of Medicine, Cheongju, South Korea
| | - Yong Sook Goo
- Department of Physiology, Chungbuk National University College of Medicine, Cheongju, South Korea.
| | - Seong-Woo Kim
- Department of Ophthalmology, Korea University College of Medicine, Seoul, South Korea.
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7
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Choi KE, Anh VTQ, Seo HW, Kim N, Kim S, Kim SW. Ab-interno surgical technique for the implantation of a wireless subretinal prosthesis in mini-pigs. Sci Rep 2020; 10:18507. [PMID: 33116246 PMCID: PMC7595207 DOI: 10.1038/s41598-020-75579-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Accepted: 10/16/2020] [Indexed: 11/22/2022] Open
Abstract
We sought to describe the surgical techniques required in the ab-interno method to implant subretinal prostheses in mini-pigs and suggest tips to facilitate optimal outcomes. During vitrectomy, the use of valved trocar cannulas was essential to stabilize the detached retina and implanted chip. As a first step in retinal detachment, a 23-gauge cannula with very small amount of viscoelastic material was used to establish the retinal hole and promote retinal detachment. Then, balanced salt solution was applied to increase the retinal detachment and diathermy was used to make opening for subretinal prosthesis. For easy positioning of the subretinal prosthesis, a curved laser probe was adopted when handling the subretinal prosthesis under the retina. After surgery, the sclerotomy sites were tightly sutured to prevent silicone oil leakage. Without special equipment, such as a 41-gauge tip, retinal detachment could be induced easily, while the prosthesis was also successfully inserted and manipulated under the retina without an iatrogenic retinal tear. Two weeks after the operation, the oil fully occupied the intraocular volume without leakage. The subretinal prosthesis remained stable without complication. Understanding the principle of the ab-interno method and considering several tips for improving surgical access may help to enhance surgical success rates of subretinal prostheses implantation.
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Affiliation(s)
- Kwang-Eon Choi
- Department of Ophthalmology, Korea University College of Medicine, Seoul, South Korea
| | - Vu Thi Que Anh
- Department of Ophthalmology, Hanoi Medical University, Hanoi, Vietnam
| | - Hee Won Seo
- Department of Robotics Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, South Korea
| | - Namju Kim
- Department of Robotics Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, South Korea
| | - Sohee Kim
- Department of Robotics Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, South Korea.
| | - Seong-Woo Kim
- Department of Ophthalmology, Korea University College of Medicine, Seoul, South Korea.
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Abstract
With ever-increasing concerns on health and environmental safety, there is a fast-growing interest in new technologies for medical devices and applications. Particularly, wireless power transfer (WPT) technology provides reliable and convenient power charging for implant medical devices without additional surgery. For those WPT medical systems, the width of the human body restricts the charging distance, while the specific absorption rate (SAR) standard limits the intensity of the electromagnetic field. In order to develop a high-efficient charging strategy for medical implants, the key factors of transmission distance, coil structure, resonant frequency, etc. are paid special attention. In this paper, a comprehensive overview of near-field WPT technologies in medical devices is presented and discussed. Also, future development is discussed for the prediction of different devices when embedded in various locations of the human body. Moreover, the key issues including power transfer efficiency and output power are addressed and analyzed. All concerning characteristics of WPT links for medical usage are elaborated and discussed. Thus, this review provides an in-depth investigation and the whole map for WPT technologies applied in medical applications.
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9
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Shim S, Eom K, Jeong J, Kim SJ. Retinal Prosthetic Approaches to Enhance Visual Perception for Blind Patients. MICROMACHINES 2020; 11:E535. [PMID: 32456341 PMCID: PMC7281011 DOI: 10.3390/mi11050535] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 05/22/2020] [Accepted: 05/22/2020] [Indexed: 12/14/2022]
Abstract
Retinal prostheses are implantable devices that aim to restore the vision of blind patients suffering from retinal degeneration, mainly by artificially stimulating the remaining retinal neurons. Some retinal prostheses have successfully reached the stage of clinical trials; however, these devices can only restore vision partially and remain insufficient to enable patients to conduct everyday life independently. The visual acuity of the artificial vision is limited by various factors from both engineering and physiological perspectives. To overcome those issues and further enhance the visual resolution of retinal prostheses, a variety of retinal prosthetic approaches have been proposed, based on optimization of the geometries of electrode arrays and stimulation pulse parameters. Other retinal stimulation modalities such as optics, ultrasound, and magnetics have also been utilized to address the limitations in conventional electrical stimulation. Although none of these approaches have been clinically proven to fully restore the function of a degenerated retina, the extensive efforts made in this field have demonstrated a series of encouraging findings for the next generation of retinal prostheses, and these could potentially enhance the visual acuity of retinal prostheses. In this article, a comprehensive and up-to-date overview of retinal prosthetic strategies is provided, with a specific focus on a quantitative assessment of visual acuity results from various retinal stimulation technologies. The aim is to highlight future directions toward high-resolution retinal prostheses.
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Affiliation(s)
- Shinyong Shim
- Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul 08826, Korea;
- Inter-university Semiconductor Research Center, College of Engineering, Seoul National University, Seoul 08826, Korea
| | - Kyungsik Eom
- Department of Electronics Engineering, College of Engineering, Pusan National University, Busan 46241, Korea
| | - Joonsoo Jeong
- School of Biomedical Convergence Engineering, College of Information and Biomedical Engineering, Pusan National University, Yangsan 50612, Korea
| | - Sung June Kim
- Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul 08826, Korea;
- Inter-university Semiconductor Research Center, College of Engineering, Seoul National University, Seoul 08826, Korea
- Institute on Aging, College of Medicine, Seoul National University, Seoul 08826, Korea
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10
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Shim S, Seo K, Kim SJ. A preliminary implementation of an active intraocular prosthesis as a new image acquisition device for a cortical visual prosthesis. J Artif Organs 2020; 23:262-269. [PMID: 32342231 DOI: 10.1007/s10047-020-01168-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 04/07/2020] [Indexed: 11/30/2022]
Abstract
An active intraocular prosthesis is herein proposed as a new image acquisition device for a cortical visual prosthesis. A conventional intraocular prosthesis is a passive device that helps blind patients underwent eye enucleation to maintain the shape of an eyeball. In contrast, an active intraocular prosthesis, which works as an implantable wireless camera, can capture real-time images and transmit them to a cortical visual prosthesis to restore partial vision of the patients. This active device has distinct advantages in that it can garner a variety of image information while focusing on objects in accordance with natural eye movements, compared with a glasses-mounted camera and implanted micro-photodiodes in typical artificial vision systems. Coated with an epoxy and sealed by an elastomer for biocompatibility as well as durability, the active intraocular prosthesis was fabricated in a spherical form miniaturized enough to be inserted into the eye. Its operation was evaluated by wireless image acquisition displaying a processed gray-scale image. Furthermore, signal-to-noise ratio measurements were conducted to find a reliable communication range of the fabricated prosthesis, while it was covered by an 8-mm-thick biological medium that mimicked in vivo environments. In conclusion, the feasibility of the active intraocular prosthesis to cooperate with a cortical visual prosthesis is discussed.
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Affiliation(s)
- Shinyong Shim
- Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul, 08826, South Korea.,Inter-university Semiconductor Research Center, College of Engineering, Seoul National University, Seoul, 08826, South Korea
| | - Kangmoon Seo
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Seoul National University, Seoul, 08826, South Korea
| | - Sung June Kim
- Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul, 08826, South Korea. .,Inter-university Semiconductor Research Center, College of Engineering, Seoul National University, Seoul, 08826, South Korea. .,Institute on Aging, College of Medicine, Seoul National University, Seoul, 08826, South Korea.
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11
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Crespo-Cano R, Cuenca-Asensi S, Fernández E, Martínez-Álvarez A. Metaheuristic Optimisation Algorithms for Tuning a Bioinspired Retinal Model. SENSORS (BASEL, SWITZERLAND) 2019; 19:E4834. [PMID: 31698827 PMCID: PMC6891458 DOI: 10.3390/s19224834] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 10/31/2019] [Accepted: 11/03/2019] [Indexed: 11/22/2022]
Abstract
A significant challenge in neuroscience is understanding how visual information is encoded in the retina. Such knowledge is extremely important for the purpose of designing bioinspired sensors and artificial retinal systems that will, in so far as may be possible, be capable of mimicking vertebrate retinal behaviour. In this study, we report the tuning of a reliable computational bioinspired retinal model with various algorithms to improve the mimicry of the model. Its main contribution is two-fold. First, given the multi-objective nature of the problem, an automatic multi-objective optimisation strategy is proposed through the use of four biological-based metrics, which are used to adjust the retinal model for accurate prediction of retinal ganglion cell responses. Second, a subset of population-based search heuristics-genetic algorithms (SPEA2, NSGA-II and NSGA-III), particle swarm optimisation (PSO) and differential evolution (DE)-are explored to identify the best algorithm for fine-tuning the retinal model, by comparing performance across a hypervolume metric. Nonparametric statistical tests are used to perform a rigorous comparison between all the metaheuristics. The best results were achieved with the PSO algorithm on the basis of the largest hypervolume that was achieved, well-distributed elements and high numbers on the Pareto front.
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Affiliation(s)
- Rubén Crespo-Cano
- Department of Computer Technology, University of Alicante, 03690 Alicante, Spain; (R.C.-C.); (S.C.-A.)
| | - Sergio Cuenca-Asensi
- Department of Computer Technology, University of Alicante, 03690 Alicante, Spain; (R.C.-C.); (S.C.-A.)
| | - Eduardo Fernández
- Institute of Bioengineering, University Miguel Hernández and CIBER BBN, 03202 Elche (Alicante), Spain;
| | - Antonio Martínez-Álvarez
- Department of Computer Technology, University of Alicante, 03690 Alicante, Spain; (R.C.-C.); (S.C.-A.)
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Nagaraj R, Bijukumar DR, Mathew B, Scott EA, Mathew MT. A review on recent advancements in ophthalmology devices: Currently in market and under clinical trials. J Drug Deliv Sci Technol 2019. [DOI: 10.1016/j.jddst.2019.04.038] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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13
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Abstract
Visual prostheses serve to restore visual function following acquired blindness. Acquired blindness (as opposed to congenital blindness) has many causes, including diseases such as retinitis pigmentosa, glaucoma, and macular degeneration, or trauma such as caused by automobile accident or blast damage from explosions. Many of the blindness-causing diseases target the retina or other ocular structure. Often, despite the loss of sensitivity to light, the remainder of the visual pathway is still functional, enabling electrical devices to deliver effective and meaningful visual information to the brain via arrays of electrodes. These arrays can be placed in any part of the early visual pathway, such as the retina, optic nerve, lateral geniculate nucleus, or visual cortex. A camera or other imaging source is used to drive electrical stimulation of remaining healthy cells or structures to create artificial vision and provide restoration of function. In this review, each approach to visual prostheses is described, including advantages and disadvantages as well as assessments of the current state of the art. Most of the work to-date has been targeting stimulation of (a) the retina, with three devices approved for general use and two more in clinical testing; (b) the lateral geniculate nucleus, with efforts still in the pre-clinical stage; and (c) the cortex, with three devices in clinical testing and none currently approved for general use despite the longest history of investigation of the three major approaches. Each class of device has different medical indications, and different levels of invasiveness required for implantation. All contemporary devices deliver relatively poor vision. There has been remarkable progress since the first proof-of-concept demonstration that used stimulation of the primary visual cortex, with the field exploring all viable options for restoration of function. Much of the progress has been recent, driven by advances in microelectronics and biocompatibility. With three devices currently approved for general use in various parts of the world, and a handful of additional devices well along in the pipeline toward approval, prospects for wide deployment of a device-based therapy to treat acquired blindness are good.
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14
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Ryu SB, Werginz P, Fried SI. Response of Mouse Visual Cortical Neurons to Electric Stimulation of the Retina. Front Neurosci 2019; 13:324. [PMID: 31019449 PMCID: PMC6459047 DOI: 10.3389/fnins.2019.00324] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 03/21/2019] [Indexed: 12/27/2022] Open
Abstract
Retinal prostheses strive to restore vision to the blind by electrically stimulating the neurons that survive the disease process. Clinical effectiveness has been limited however, and much ongoing effort is devoted toward the development of improved stimulation strategies, especially ones that better replicate physiological patterns of neural signaling. Here, to better understand the potential effectiveness of different stimulation strategies, we explore the responses of neurons in the primary visual cortex to electric stimulation of the retina. A 16-channel implantable microprobe was used to record single unit activities in vivo from each layer of the mouse visual cortex. Layers were identified by electrode depth as well as spontaneous rate. Cell types were classified as excitatory or inhibitory based on their spike waveform and as ON, OFF, or ON-OFF based on the polarity of their light response. After classification, electric stimulation was delivered via a wire electrode placed on the surface of cornea (extraocularly) and responses were recorded from the cortex contralateral to the stimulated eye. Responses to electric stimulation were highly similar across cell types and layers. Responses (spike counts) increased as a function of the amplitude of stimulation, and although there was some variance across cells, the sensitivity to amplitude was largely similar across all cell types. Suppression of responses was observed for pulse rates ≥3 pulses per second (PPS) but did not originate in the retina as RGC responses remained stable to rates up to 5 PPS. Low-frequency sinusoids delivered to the retina replicated the out-of-phase responses that occur naturally in ON vs. OFF RGCs. Intriguingly, out-of-phase signaling persisted in V1 neurons, suggesting key aspects of neural signaling are preserved during transmission along visual pathways. Our results describe an approach to evaluate responses of cortical neurons to electric stimulation of the retina. By examining the responses of single cells, we were able to show that some retinal stimulation strategies can indeed better match the neural signaling patterns used by the healthy visual system. Because cortical signaling is better correlated to psychophysical percepts, the ability to evaluate which strategies produce physiological-like cortical responses may help to facilitate better clinical outcomes.
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Affiliation(s)
- Sang Baek Ryu
- Boston VA Healthcare System, Boston, MA, United States.,Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
| | - Paul Werginz
- Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States.,Institute for Analysis and Scientific Computing, Vienna University of Technology, Vienna, Austria
| | - Shelley I Fried
- Boston VA Healthcare System, Boston, MA, United States.,Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
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15
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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: 61] [Impact Index Per Article: 12.2] [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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16
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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: 18] [Impact Index Per Article: 3.0] [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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17
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Weiland JD, Walston ST, Humayun MS. Electrical Stimulation of the Retina to Produce Artificial Vision. Annu Rev Vis Sci 2018; 2:273-294. [PMID: 28532361 DOI: 10.1146/annurev-vision-111815-114425] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Retinal prostheses aim to restore vision to blind individuals suffering from retinal diseases such as retinitis pigmentosa and age-related macular degeneration. These devices function by electrically stimulating surviving retinal neurons, whose activation is interpreted by the brain as a visual percept. Many prostheses are currently under development. They are categorized as epiretinal, subretinal, and suprachoroidal prostheses on the basis of the placement of the stimulating microelectrode array. Each can activate ganglion cells through direct or indirect stimulation. The response of retinal neurons to these modes of stimulation are discussed in detail and are placed in context of the visual percept they are likely to evoke. This article further reviews challenges faced by retinal prosthesis and discusses potential solutions to address them.
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Affiliation(s)
- James D Weiland
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California 90007; .,USC Roski Eye Institute, University of Southern California, Los Angeles, California 90033.,Institute for Biomedical Therapeutics, University of Southern California, Los Angeles, California 90033
| | - Steven T Walston
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California 90007;
| | - Mark S Humayun
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California 90007; .,USC Roski Eye Institute, University of Southern California, Los Angeles, California 90033.,Institute for Biomedical Therapeutics, University of Southern California, Los Angeles, California 90033
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18
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Li H, Su X, Wang J, Kan H, Han T, Zeng Y, Chai X. Image processing strategies based on saliency segmentation for object recognition under simulated prosthetic vision. Artif Intell Med 2018; 84:64-78. [PMID: 29129481 DOI: 10.1016/j.artmed.2017.11.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2016] [Revised: 11/03/2017] [Accepted: 11/07/2017] [Indexed: 11/19/2022]
Affiliation(s)
- Heng Li
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Xiaofan Su
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Jing Wang
- College of Information Technology, Shanghai Ocean University, Shanghai 201306, China
| | - Han Kan
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Tingting Han
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yajie Zeng
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Xinyu Chai
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
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19
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Weiland JD, Humayun MS, Gonzalez Calle A. The Development of Visual Prosthetic Devices to Restore Vision to the Blind. Neuromodulation 2018. [DOI: 10.1016/b978-0-12-805353-9.00101-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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20
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Rountree CM, Troy JB, Saggere L. Methodology for Biomimetic Chemical Neuromodulation of Rat Retinas with the Neurotransmitter Glutamate In Vitro. J Vis Exp 2017. [PMID: 29286422 DOI: 10.3791/56645] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Photoreceptor degenerative diseases cause irreparable blindness through the progressive loss of photoreceptor cells in the retina. Retinal prostheses are an emerging treatment for photoreceptor degenerative diseases that seek to restore vision by artificially stimulating the surviving retinal neurons in the hope of eliciting comprehensible visual perception in patients. Current retinal prostheses have demonstrated success in restoring limited vision to patients using an array of electrodes to electrically stimulate the retina but face substantial physical barriers in restoring high acuity, natural vision to patients. Chemical neurostimulation using native neurotransmitters is a biomimetic alternative to electrical stimulation and could bypass the fundamental limitations associated with retinal prostheses using electrical neurostimulation. Specifically, chemical neurostimulation has the potential to restore more natural vision with comparable or better visual acuities to patients by injecting very small quantities of neurotransmitters, the same natural agents of communication used by retinal chemical synapses, at much finer resolution than current electrical prostheses. However, as a relatively unexplored stimulation paradigm, there is no established protocol for achieving chemical stimulation of the retina in vitro. The purpose of this work is to provide a detailed framework for accomplishing chemical stimulation of the retina for investigators who wish to study the potential of chemical neuromodulation of the retina or similar neural tissues in vitro. In this work, we describe the experimental setup and methodology for eliciting retinal ganglion cell (RGC) spike responses similar to visual light responses in wild-type and photoreceptor-degenerated wholemount rat retinas by injecting controlled volumes of the neurotransmitter glutamate into the subretinal space using glass micropipettes and a custom multiport microfluidic device. This methodology and protocol are general enough to be adapted for neuromodulation using other neurotransmitters or even other neural tissues.
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Affiliation(s)
- Corey M Rountree
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago
| | - John B Troy
- Department of Biomedical Engineering, Northwestern University
| | - Laxman Saggere
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago;
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21
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Eiber CD, Dokos S, Lovell NH, Suaning GJ. Multipolar Field Shaping in a Suprachoroidal Visual Prosthesis. IEEE Trans Neural Syst Rehabil Eng 2017; 25:2480-2487. [DOI: 10.1109/tnsre.2017.2730880] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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22
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Dias MF, Joo K, Kemp JA, Fialho SL, da Silva Cunha A, Woo SJ, Kwon YJ. Molecular genetics and emerging therapies for retinitis pigmentosa: Basic research and clinical perspectives. Prog Retin Eye Res 2017; 63:107-131. [PMID: 29097191 DOI: 10.1016/j.preteyeres.2017.10.004] [Citation(s) in RCA: 259] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 10/19/2017] [Accepted: 10/25/2017] [Indexed: 02/06/2023]
Abstract
Retinitis Pigmentosa (RP) is a hereditary retinopathy that affects about 2.5 million people worldwide. It is characterized with progressive loss of rods and cones and causes severe visual dysfunction and eventual blindness in bilateral eyes. In addition to more than 3000 genetic mutations from about 70 genes, a wide genetic overlap with other types of retinal dystrophies has been reported with RP. This diversity of genetic pathophysiology makes treatment extremely challenging. Although therapeutic attempts have been made using various pharmacologic agents (neurotrophic factors, antioxidants, and anti-apoptotic agents), most are not targeted to the fundamental cause of RP, and their clinical efficacy has not been clearly proven. Current therapies for RP in ongoing or completed clinical trials include gene therapy, cell therapy, and retinal prostheses. Gene therapy, a strategy to correct the genetic defects using viral or non-viral vectors, has the potential to achieve definitive treatment by replacing or silencing a causative gene. Among many clinical trials of gene therapy for hereditary retinal diseases, a phase 3 clinical trial of voretigene neparvovec (AAV2-hRPE65v2, Luxturna) recently showed significant efficacy for RPE65-mediated inherited retinal dystrophy including Leber congenital amaurosis and RP. It is about to be approved as the first ocular gene therapy biologic product. Despite current limitations such as limited target genes and indicated patients, modest efficacy, and the invasive administration method, development in gene editing technology and novel gene delivery carriers make gene therapy a promising therapeutic modality for RP and other hereditary retinal dystrophies in the future.
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Affiliation(s)
- Marina França Dias
- School of Pharmacy, Federal University of Minas Gerais, Belo Horizonte, Brazil; Department of Pharmaceutical Sciences, University of California, Irvine, CA, USA
| | - Kwangsic Joo
- Department of Ophthalmology, Seoul National University Bundang Hospital, Seongnam, Republic of Korea
| | - Jessica A Kemp
- Department of Pharmaceutical Sciences, University of California, Irvine, CA, USA
| | - Silvia Ligório Fialho
- Pharmaceutical Research and Development, Ezequiel Dias Foundation, Belo Horizonte, Brazil
| | | | - Se Joon Woo
- Department of Pharmaceutical Sciences, University of California, Irvine, CA, USA; Department of Ophthalmology, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
| | - Young Jik Kwon
- Department of Pharmaceutical Sciences, University of California, Irvine, CA, USA; Department of Chemical Engineering and Materials Sciences, University of California, Irvine, CA, USA; Department of Biomedical Engineering, University of California, Irvine, CA, USA; Department of Molecular Biology and Biochemistry, University of California, Irvine, CA, USA.
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23
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Spatiotemporal Pixelization to Increase the Recognition Score of Characters for Retinal Prostheses. SENSORS 2017; 17:s17102439. [PMID: 29073735 PMCID: PMC5677288 DOI: 10.3390/s17102439] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 10/21/2017] [Accepted: 10/22/2017] [Indexed: 11/16/2022]
Abstract
Most of the retinal prostheses use a head-fixed camera and a video processing unit. Some studies proposed various image processing methods to improve visual perception for patients. However, previous studies only focused on using spatial information. The present study proposes a spatiotemporal pixelization method mimicking fixational eye movements to generate stimulation images for artificial retina arrays by combining spatial and temporal information. Input images were sampled with a resolution that was four times higher than the number of pixel arrays. We subsampled this image and generated four different phosphene images. We then evaluated the recognition scores of characters by sequentially presenting phosphene images with varying pixel array sizes (6 × 6, 8 × 8 and 10 × 10) and stimulus frame rates (10 Hz, 15 Hz, 20 Hz, 30 Hz, and 60 Hz). The proposed method showed the highest recognition score at a stimulus frame rate of approximately 20 Hz. The method also significantly improved the recognition score for complex characters. This method provides a new way to increase practical resolution over restricted spatial resolution by merging the higher resolution image into high-frame time slots.
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24
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Zhao Y, Geng X, Li Q, Jiang G, Gu Y, Lv X. Recognition of a Virtual Scene via Simulated Prosthetic Vision. Front Bioeng Biotechnol 2017; 5:58. [PMID: 29067286 PMCID: PMC5641342 DOI: 10.3389/fbioe.2017.00058] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2017] [Accepted: 09/20/2017] [Indexed: 11/24/2022] Open
Abstract
In order to effectively aid the blind with optimal low-resolution vision and visual recovery training, pathfinding and recognition tests were performed using a simulated visual prosthetic scene. Simple and complex virtual scenes were built using 3DMAX and Unity, and pixelated to three different resolutions (32 × 32, 64 × 64, and 128 × 128) for real-time pixel processing. Twenty subjects were recruited to complete the pathfinding and object recognition tasks within the scene. The recognition accuracy and time required were recorded and analyzed after the trials. In the simple simulated prosthetic vision (SPV) scene, when the resolution was increased from 32 × 32 to 48 × 48, the object recognition time decreased from 92.19 ± 6.97 to 43.05 ± 6.08 s, and the recognition accuracy increased from 51.22 ± 8.53 to 85.52 ± 4.93%. Furthermore, the number of collisions decreased from 10.00 ± 2.31 to 3.00 ± 0.68. When the resolution was increased from 48 × 48 to 64 × 64, the object recognition time further decreased from 43.05 ± 6.08 to 19.46 ± 3.71 s, the recognition accuracy increased from 85.52 ± 4.93 to 96.89 ± 2.06%, and the number of collisions decreased from 3.00 ± 0.68 to 1.00 ± 0.29. In complex scenes, the time required to recognize the room type decreased from 115.00 ± 23.02 to 68.25 ± 17.23 s, and object recognition accuracy increased from 65.69 ± 9.61 to 80.42 ± 7.70% when the resolution increased from 48 × 48 to 64 × 64. When the resolution increased from 64 × 64 to 128 × 128, the time required to recognize the room type decreased from 68.25 ± 17.23 to 44.88 ± 9.94 s, and object recognition accuracy increased from 80.42 ± 7.71 to 85.69 ± 7.39%. Therefore, one can conclude that there are correlations between pathfinding and recognition. When the resolution increased, the time required for recognition decreased, the recognition accuracy increased, and the number of collisions decreased. Although the subjects could partially complete the recognition task at a resolution of 32 × 32, the recognition time was too long and recognition accuracy was not good enough to identify simple scenes. Complex scenes required a resolution of at least 48 × 48 for complete recognition. In addition, increasing the resolution shortened the time required to identify the type of room, and improved the recognition accuracy.
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Affiliation(s)
- Ying Zhao
- School of Information Engineering, University of Science and Technology, Baotou, China
| | - Xiulin Geng
- School of Information Engineering, University of Science and Technology, Baotou, China
| | - Qi Li
- School of Information Engineering, University of Science and Technology, Baotou, China
| | - Guangqi Jiang
- School of Information Engineering, University of Science and Technology, Baotou, China
| | - Yu Gu
- School of Information Engineering, University of Science and Technology, Baotou, China
- School of Computer Engineering and Science, Shanghai University, Shanghai, China
| | - Xiaoqi Lv
- School of Information Engineering, University of Science and Technology, Baotou, China
- School of Computer Engineering and Science, Shanghai University, Shanghai, China
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25
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Mills JO, Jalil A, Stanga PE. Electronic retinal implants and artificial vision: journey and present. Eye (Lond) 2017; 31:1383-1398. [PMID: 28548648 PMCID: PMC5639190 DOI: 10.1038/eye.2017.65] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2016] [Accepted: 01/20/2017] [Indexed: 02/07/2023] Open
Abstract
Retinitis pigmentosa and age-related macular degeneration are two significant causes of severe visual dysfunction. In both, the retinal photoreceptors degenerate, preventing successful conversion of light into electrical energy that is interpreted in the visual cortex as visual function. Artificial vision or visual function began over two centuries ago with the idea of creating artificial light pulses, or phosphenes, through cortical stimulation. The pursuit is now on to improve artificial visual function. Two retinal implants appear the most likely to succeed in the future having undergone multicentre human trials: the Argus II electronic epiretinal device (Second Sight Medical Products, CA, USA) and Alpha-IMS electronic subretinal device (Retina Implant AG, Germany). The trial results to date are encouraging with visual improvement and acceptable safety profiles reported for both devices. At present, the visual function generated by either device does not offer high enough resolution or acuity for a patient to regain a fully functional life. Despite this, both devices not only have the potential, but have actually improved the vision-related quality of life in a significant number of patients implanted. With this in mind, the economic argument is clear. Provided device-life is long enough, its cost should be acceptable for the obtained improvement in the quality of life. The aim of this Review Article is to assist those readers that may be considering offering any of these devices as a treatment for blindness in Retinitis Pigmentosa.
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Affiliation(s)
- J O Mills
- Manchester Royal Eye Hospital, Manchester, UK
- Manchester Vision Regeneration (MVR) Lab at Manchester Royal Eye Hospital, NIHR/ Wellcome Trust Manchester CRF, Manchester Royal Eye Hospital, Manchester, UK
| | - A Jalil
- Manchester Royal Eye Hospital, Manchester, UK
- Manchester Vision Regeneration (MVR) Lab at Manchester Royal Eye Hospital, NIHR/ Wellcome Trust Manchester CRF, Manchester Royal Eye Hospital, Manchester, UK
| | - P E Stanga
- Manchester Royal Eye Hospital, Manchester, UK
- Manchester Vision Regeneration (MVR) Lab at Manchester Royal Eye Hospital, NIHR/ Wellcome Trust Manchester CRF, Manchester Royal Eye Hospital, Manchester, UK
- Manchester Academic Health Science Centre and Centre for Ophthalmology and Vision Research, Institute of Human Development, University of Manchester, Manchester, UK
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26
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Agarwal K, Jegadeesan R, Guo YX, Thakor NV. Wireless Power Transfer Strategies for Implantable Bioelectronics. IEEE Rev Biomed Eng 2017; 10:136-161. [PMID: 28328511 DOI: 10.1109/rbme.2017.2683520] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Neural implants have emerged over the last decade as highly effective solutions for the treatment of dysfunctions and disorders of the nervous system. These implants establish a direct, often bidirectional, interface to the nervous system, both sensing neural signals and providing therapeutic treatments. As a result of the technological progress and successful clinical demonstrations, completely implantable solutions have become a reality and are now commercially available for the treatment of various functional disorders. Central to this development is the wireless power transfer (WPT) that has enabled implantable medical devices (IMDs) to function for extended durations in mobile subjects. In this review, we present the theory, link design, and challenges, along with their probable solutions for the traditional near-field resonant inductively coupled WPT, capacitively coupled short-ranged WPT, and more recently developed ultrasonic, mid-field, and far-field coupled WPT technologies for implantable applications. A comparison of various power transfer methods based on their power budgets and WPT range follows. Power requirements of specific implants like cochlear, retinal, cortical, and peripheral are also considered and currently available IMD solutions are discussed. Patient's safety concerns with respect to electrical, biological, physical, electromagnetic interference, and cyber security from an implanted neurotech device are also explored in this review. Finally, we discuss and anticipate future developments that will enhance the capabilities of current-day wirelessly powered implants and make them more efficient and integrable with other electronic components in IMDs.
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27
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Cheng DL, Greenberg PB, Borton DA. Advances in Retinal Prosthetic Research: A Systematic Review of Engineering and Clinical Characteristics of Current Prosthetic Initiatives. Curr Eye Res 2017; 42:334-347. [PMID: 28362177 DOI: 10.1080/02713683.2016.1270326] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
PURPOSE To date, reviews of retinal prostheses have focused primarily on devices undergoing human trials in the Western Hemisphere and fail to capture significant advances in materials and engineering research in countries such as Japan and Korea, as well as projects in early stages of development. To address these gaps, this systematic review examines worldwide advances in retinal prosthetic research, evaluates engineering characteristics and clinical progress of contemporary device initiatives, and identifies potential directions for future research in the field of retinal prosthetics. METHODS A literature search using PubMed, Google Scholar, and IEEExplore was conducted following the PRISMA Guidelines for Systematic Review. Inclusion criteria were peer-reviewed papers demonstrating progress in human or animal trials and papers discussing the prosthetic engineering design. For each initiative, a description of the device, its engineering considerations, and recent clinical results were provided. RESULTS Ten prosthetic initiatives met our inclusion criteria and were organized by stimulation location. Of these initiatives, four have recently completed human trials, three are undergoing multi- or single-center human trials, and three are undergoing preclinical animal testing. Only the Argus II (FDA 2013, CE 2011) has obtained FDA approval for use in the United States; the Alpha-IMS (CE 2013) has achieved the highest visual acuity using a Landolt-C test to date and is the only device presently undergoing a multicenter clinical trial. CONCLUSION Several distinct approaches to retinal stimulation have been successful in eliciting visual precepts in animals and/or humans. However, many clinical needs are still not met and engineering challenges must be addressed before a retinal prosthesis with the capability to fully and safely restore functional vision can be realized.
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Affiliation(s)
- Derrick L Cheng
- a Alpert Medical School , Brown University , Providence , RI , USA
| | - Paul B Greenberg
- b Section of Ophthalmology , Providence VA Medical Center , Providence , RI , USA.,c Division of Ophthalmology, Alpert Medical School , Brown University , Providence , RI , USA
| | - David A Borton
- d School of Engineering , Brown University , Providence , RI , USA.,e Brown Institute for Brain Science , Brown University , Providence , RI , USA
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28
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Goetz GA, Palanker DV. Electronic approaches to restoration of sight. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2016; 79:096701. [PMID: 27502748 PMCID: PMC5031080 DOI: 10.1088/0034-4885/79/9/096701] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Retinal prostheses are a promising means for restoring sight to patients blinded by the gradual atrophy of photoreceptors due to retinal degeneration. They are designed to reintroduce information into the visual system by electrically stimulating surviving neurons in the retina. This review outlines the concepts and technologies behind two major approaches to retinal prosthetics: epiretinal and subretinal. We describe how the visual system responds to electrical stimulation. We highlight major differences between direct encoding of the retinal output with epiretinal stimulation, and network-mediated response with subretinal stimulation. We summarize results of pre-clinical evaluation of prosthetic visual functions in- and ex vivo, as well as the outcomes of current clinical trials of various retinal implants. We also briefly review alternative, non-electronic, approaches to restoration of sight to the blind, and conclude by suggesting some perspectives for future advancement in the field.
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Affiliation(s)
- G A Goetz
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA. Neurosurgery, Stanford University, Stanford, CA 94305, USA
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29
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Ha S, Khraiche ML, Akinin A, Jing Y, Damle S, Kuang Y, Bauchner S, Lo YH, Freeman WR, Silva GA, Cauwenberghs G. Towards high-resolution retinal prostheses with direct optical addressing and inductive telemetry. J Neural Eng 2016; 13:056008. [PMID: 27529371 DOI: 10.1088/1741-2560/13/5/056008] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Despite considerable advances in retinal prostheses over the last two decades, the resolution of restored vision has remained severely limited, well below the 20/200 acuity threshold of blindness. Towards drastic improvements in spatial resolution, we present a scalable architecture for retinal prostheses in which each stimulation electrode is directly activated by incident light and powered by a common voltage pulse transferred over a single wireless inductive link. APPROACH The hybrid optical addressability and electronic powering scheme provides separate spatial and temporal control over stimulation, and further provides optoelectronic gain for substantially lower light intensity thresholds than other optically addressed retinal prostheses using passive microphotodiode arrays. The architecture permits the use of high-density electrode arrays with ultra-high photosensitive silicon nanowires, obviating the need for excessive wiring and high-throughput data telemetry. Instead, the single inductive link drives the entire array of electrodes through two wires and provides external control over waveform parameters for common voltage stimulation. MAIN RESULTS A complete system comprising inductive telemetry link, stimulation pulse demodulator, charge-balancing series capacitor, and nanowire-based electrode device is integrated and validated ex vivo on rat retina tissue. SIGNIFICANCE Measurements demonstrate control over retinal neural activity both by light and electrical bias, validating the feasibility of the proposed architecture and its system components as an important first step towards a high-resolution optically addressed retinal prosthesis.
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Affiliation(s)
- Sohmyung Ha
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, 92093 USA. Institute of Engineering in Medicine, University of California, San Diego, La Jolla, CA, 92093 USA
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30
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Werginz P, Rattay F. The impact of calcium current reversal on neurotransmitter release in the electrically stimulated retina. J Neural Eng 2016; 13:046013. [DOI: 10.1088/1741-2560/13/4/046013] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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31
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Svechtarova MI, Buzzacchera I, Toebes BJ, Lauko J, Anton N, Wilson CJ. Sensor Devices Inspired by the Five Senses: A Review. ELECTROANAL 2016. [DOI: 10.1002/elan.201600047] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
| | | | - B. Jelle Toebes
- NovioSense BV; Transistorweg 5 6534 AT Nijmegen The Netherlands
| | - Jan Lauko
- NovioSense BV; Transistorweg 5 6534 AT Nijmegen The Netherlands
| | - Nicoleta Anton
- Universitatea de Medicina si Farmacie Grigore T.; Popa, Str. Universitatii nr. 16 700115 Iasi Romania
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32
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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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Zapf MPH, Boon MY, Lovell NH, Suaning GJ. Assistive peripheral phosphene arrays deliver advantages in obstacle avoidance in simulated end-stage retinitis pigmentosa: a virtual-reality study. J Neural Eng 2016; 13:026022. [PMID: 26902525 DOI: 10.1088/1741-2560/13/2/026022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE The prospective efficacy of peripheral retinal prostheses for guiding orientation and mobility in the absence of residual vision, as compared to an implant for the central visual field (VF), was evaluated using simulated prosthetic vision (SPV). APPROACH Sighted volunteers wearing a head-mounted display performed an obstacle circumvention task under SPV. Mobility and orientation performance with three layouts of prosthetic vision were compared: peripheral prosthetic vision of higher visual acuity (VA) but limited VF, of wider VF but limited VA, as well as centrally restricted prosthetic vision. Learning curves using these layouts were compared fitting an exponential model to the mobility and orientation measures. MAIN RESULTS Using peripheral layouts, performance was superior to the central layout. Walking speed with both higher-acuity and wider-angle layouts was 5.6% higher, and mobility errors reduced by 46.4% and 48.6%, respectively, as compared to the central layout. The wider-angle layout yielded the least number of collisions, 63% less than the higher-acuity and 73% less than the central layout. Using peripheral layouts, the number of visual-scanning related head movements was 54.3% (higher-acuity) and 60.7% (wider-angle) lower, as compared to the central layout, and the ratio of time standing versus time walking was 51.9% and 61.5% lower, respectively. Learning curves did not differ between layouts, except for time standing versus time walking, where both peripheral layouts achieved significantly lower asymptotic values compared to the central layout. SIGNIFICANCE Beyond complementing residual vision for an improved performance, peripheral prosthetic vision can effectively guide mobility in the later stages of retinitis pigmentosa (RP) without residual vision. Further, the temporal dynamics of learning peripheral and central prosthetic vision are similar. Therefore, development of a peripheral retinal prosthesis and early implantation to alleviate VF constriction in RP should be considered to extend the target group and the time of benefit for potential retinal prosthesis implantees.
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Affiliation(s)
- Marc Patrick H Zapf
- Graduate School of Biomedical Engineering, UNSW Australia, Sydney 2052, Australia
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Adekunle AN, Adkins A, Wang W, Kaplan HJ, de Castro JF, Lee SJ, Huie P, Palanker D, McCall M, Pardue MT. Integration of Perforated Subretinal Prostheses With Retinal Tissue. Transl Vis Sci Technol 2015; 4:5. [PMID: 26290776 DOI: 10.1167/tvst.4.4.5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 07/03/2015] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To investigate the integration of subretinal implants containing full-depth perforations of various widths with rat and pig retina across weeks of implantation. METHODS In transgenic P23H rhodopsin line 1 (TgP23H-1) rats and wild-type (WT) pigs, we examined four subretinal implant designs: solid inactive polymer arrays (IPA), IPAs with 5- or 10-μm wide perforations, and active bipolar photovoltaic arrays (bPVA) with 5-μm perforations. We surgically placed the implants into the subretinal space using an external approach in rats or a vitreoretinal approach in pigs. Implant placement in the subretinal space was verified with optical coherence tomography and retinal perfusion was characterized with fluorescein angiography. Rats were sacrificed 8 or 16 weeks post-implantation (wpi) and pigs 2, 4, or 8 wpi, and retinas evaluated at the light microscopic level. RESULTS Regardless of implant design, retinas of both species showed normal vasculature. In TgP23H-1 retinas implanted with 10-μm perforated IPAs, inner nuclear layer (INL) cells migrated through the perforations by 8 wpi, resulting in significant INL thinning by 16 wpi. Additionally, these retinas showed greater pseudo-rosette formation and fibrosis compared with retinas with solid or 5-μm perforated IPAs. TgP23H-1 retinas with bPVAs showed similar INL migration to retinas with 5-μm perforated IPAs, with less fibrosis and rosette formation. WT pig retina with perforated IPAs maintained photoreceptors, showed no migration, and less pseudo-rosette formation, but more fibrosis compared with implanted TgP23H-1 rat retinas. CONCLUSIONS In retinas with photoreceptor degeneration, solid implants, or those with 5-μm perforations lead to the best biocompatibility.
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Affiliation(s)
| | - Alice Adkins
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Medical Center, Atlanta, GA, USA
| | - Wei Wang
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, KY, USA
| | - Henry J Kaplan
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, KY, USA
| | | | - Sang Joon Lee
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, KY, USA ; Department of Ophthalmology, Kosin University, Busan, Korea
| | - Philip Huie
- Department of Ophthalmology, Stanford University, Palo Alto, CA, USA ; Hansen Experimental Physics Laboratory, Stanford University, Palo Alto, CA, USA
| | - Daniel Palanker
- Department of Ophthalmology, Stanford University, Palo Alto, CA, USA ; Hansen Experimental Physics Laboratory, Stanford University, Palo Alto, CA, USA
| | - Maureen McCall
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, KY, USA ; Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, KY, USA
| | - Machelle T Pardue
- Department of Ophthalmology, Emory University, Atlanta, GA, USA ; Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Medical Center, Atlanta, GA, USA
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Zapf MPH, Boon MY, Lovell NH, Suaning GJ. Assistive peripheral prosthetic vision aids perception and mobility in outdoor environments: A virtual-reality simulation study. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2015; 2015:1638-1641. [PMID: 26736589 DOI: 10.1109/embc.2015.7318689] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Retinitis pigmentosa (RP) causes visual field (VF) constriction due to progressive loss of photoreceptors, typically from the retinal periphery to the fovea. Retinal prostheses offer vision restoration via electrode implantation and stimulation near the fovea, thereby eliciting articifial percepts, so-called phosphenes in the center VF. Although foveal photoreceptors can persist for prolonged periods of time, bionic therapy is usually restricted to stages of RP with complete vision loss. However, persons with RP experience mobility impairment from peripherally restricted VFs much earlier. Consequently, the amount of visual scanning necessary for navigation is increased, and maintaining a steady pace is challenging. Receiving a retinal implant at this early stage might be feasible. We investigated the potential of a peripheral visual prosthesis coexisting with central residual vision to facilitate scene perception and mobility. Simulating prosthetic and residual vision in a virtual mobility environment, we found that assistive phosphene layouts were associated with reductions in visual scanning-related head movements of up to 42.1%, body rotations of up to 30%, and up to 45% lower frequency of stopping when circumventing low-lying obstacles, pedestrians and following a path. Further research on early implantation of retinal prostheses for the peripheral VF is therefore advised.
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Zapf MPH, Boon MY, Matteucci PB, Lovell NH, Suaning GJ. Towards an assistive peripheral visual prosthesis for long-term treatment of retinitis pigmentosa: evaluating mobility performance in immersive simulations. J Neural Eng 2015; 12:036001. [DOI: 10.1088/1741-2560/12/3/036001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Ahn KN, Ahn JY, Kim JH, Cho K, Koo KI, Senok SS, Goo YS. Effect of Stimulus Waveform of Biphasic Current Pulse on Retinal Ganglion Cell Responses in Retinal Degeneration (rd1) mice. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2015; 19:167-75. [PMID: 25729279 PMCID: PMC4342737 DOI: 10.4196/kjpp.2015.19.2.167] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 01/08/2015] [Accepted: 01/22/2015] [Indexed: 11/15/2022]
Abstract
A retinal prosthesis is being developed for the restoration of vision in patients with retinitis pigmentosa (RP) and age-related macular degeneration (AMD). Determining optimal electrical stimulation parameters for the prosthesis is one of the most important elements for the development of a viable retinal prosthesis. Here, we investigated the effects of different charge-balanced biphasic pulses with regard to their effectiveness in evoking retinal ganglion cell (RGC) responses. Retinal degeneration (rd1) mice were used (n=17). From the ex-vivo retinal preparation, retinal patches were placed ganglion cell layer down onto an 8×8 multielectrode array (MEA) and RGC responses were recorded while applying electrical stimuli. For asymmetric pulses, 1st phase of the pulse is the same with symmetric pulse but the amplitude of 2nd phase of the pulse is less than 10 µA and charge balanced condition is satisfied by lengthening the duration of the pulse. For intensities (or duration) modulation, duration (or amplitude) of the pulse was fixed to 500 µs (30 µA), changing the intensities (or duration) from 2 to 60 µA (60 to 1000 µs). RGCs were classified as response-positive when PSTH showed multiple (3~4) peaks within 400 ms post stimulus and the number of spikes was at least 30% more than that for the immediate pre-stimulus 400 ms period. RGC responses were well modulated both with anodic and cathodic phase-1st biphasic pulses. Cathodic phase-1st pulses produced significantly better modulation of RGC activity than anodic phase-1st pulses regardless of symmetry of the pulse.
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Affiliation(s)
- Kun No Ahn
- Department of Physiology, Chungbuk National University School of Medicine, Cheongju 362-763, Korea
| | - Jeong Yeol Ahn
- Department of Physiology, Chungbuk National University School of Medicine, Cheongju 362-763, Korea
| | - Jae-hyung Kim
- Department of Ophthalmology, Chungbuk National University School of Medicine, Cheongju 362-763, Korea
| | - Kyoungrok Cho
- Department of Information and Communication Engineering, Chungbuk National University College of Electrical and Computer Engineering, Cheongju 362-763, Korea
| | - Kyo-in Koo
- Department of Electrical Engineering, University of Ulsan, Ulsan 680-749, Korea
| | - Solomon S. Senok
- Devision of Neuroscience, Alfaisal University College of Medicine, Riyadh 11533, Kingdom of Saudi Arabia
| | - Yong Sook Goo
- Department of Physiology, Chungbuk National University School of Medicine, Cheongju 362-763, Korea
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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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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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McCarthy C, Walker JG, Lieby P, Scott A, Barnes N. Mobility and low contrast trip hazard avoidance using augmented depth. J Neural Eng 2014; 12:016003. [DOI: 10.1088/1741-2560/12/1/016003] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Abramian M, Lovell NH, Morley JW, Suaning GJ, Dokos S. Activation and inhibition of retinal ganglion cells in response to epiretinal electrical stimulation: a computational modelling study. J Neural Eng 2014; 12:016002. [PMID: 25426958 DOI: 10.1088/1741-2560/12/1/016002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Retinal prosthetic devices aim to restore sight in visually impaired people by means of electrical stimulation of surviving retinal ganglion cells (RGCs). This modelling study aims to demonstrate that RGC inhibition caused by high-intensity cathodic pulses greatly influences their responses to epiretinal electrical stimulation and to investigate the impact of this inhibition on spatial activation profiles as well as their implications for retinal prosthetic device design. Another aim is to take advantage of this inhibition to reduce axonal activation in the nerve fibre layer. APPROACH A three-dimensional finite-element model of epiretinal electrical stimulation was utilized to obtain RGC activation and inhibition threshold profiles for a range of parameters. MAIN RESULTS RGC activation and inhibition thresholds were highly dependent on cell and stimulus parameters. Activation thresholds were 1.5, 3.4 and 11.3 μA for monopolar electrodes with 5, 20 and 50 μm radii, respectively. Inhibition to activation threshold ratios were mostly within the range 2-10. Inhibition significantly altered spatial patterns of RGC activation. With concentric electrodes and appropriately high levels of stimulus amplitudes, activation of passing axons was greatly reduced. SIGNIFICANCE RGC inhibition significantly impacts their spatial activation profiles, and therefore it most likely influences patterns of perceived phosphenes induced by retinal prosthetic devices. Thus this inhibition should be taken into account in future studies concerning retinal prosthesis development. It might be possible to utilize this inhibitory effect to bypass activation of passing axons and selectively stimulate RGCs near their somas and dendrites to achieve more localized phosphenes.
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Affiliation(s)
- Miganoosh Abramian
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Australia
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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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Light JG, Fransen JW, Adekunle AN, Adkins A, Pangeni G, Loudin J, Mathieson K, Palanker DV, McCall MA, Pardue MT. Inner retinal preservation in rat models of retinal degeneration implanted with subretinal photovoltaic arrays. Exp Eye Res 2014; 128:34-42. [PMID: 25224340 DOI: 10.1016/j.exer.2014.09.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 09/09/2014] [Accepted: 09/11/2014] [Indexed: 11/26/2022]
Abstract
Photovoltaic arrays (PVA) implanted into the subretinal space of patients with retinitis pigmentosa (RP) are designed to electrically stimulate the remaining inner retinal circuitry in response to incident light, thereby recreating a visual signal when photoreceptor function declines or is lost. Preservation of inner retinal circuitry is critical to the fidelity of this transmitted signal to ganglion cells and beyond to higher visual targets. Post-implantation loss of retinal interneurons or excessive glial scarring could diminish and/or eliminate PVA-evoked signal transmission. As such, assessing the morphology of the inner retina in RP animal models with subretinal PVAs is an important step in defining biocompatibility and predicting success of signal transmission. In this study, we used immunohistochemical methods to qualitatively and quantitatively compare inner retinal morphology after the implantation of a PVA in two RP models: the Royal College of Surgeons (RCS) or transgenic S334ter-line 3 (S334ter-3) rhodopsin mutant rat. Two PVA designs were compared. In the RCS rat, we implanted devices in the subretinal space at 4 weeks of age and histologically examined them at 8 weeks of age and found inner retinal morphology preservation with both PVA devices. In the S334ter-3 rat, we implanted devices at 6-12 weeks of age and again, inner retinal morphology was generally preserved with either PVA design 16-26 weeks post-implantation. Specifically, the length of rod bipolar cells and numbers of cholinergic amacrine cells were maintained along with their characteristic inner plexiform lamination patterns. Throughout the implanted retinas we found nonspecific glial reaction, but none showed additional glial scarring at the implant site. Our results indicate that subretinally implanted PVAs are well-tolerated in rodent RP models and that the inner retinal circuitry is preserved, consistent with our published results showing implant-evoked signal transmission.
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Affiliation(s)
- Jacob G Light
- Ophthalmology, Emory University, USA; Rehab R&D Center of Excellence, Atlanta VA Medical Center, USA
| | - James W Fransen
- Anatomical Sciences & Neurobiology, University of Louisville, USA
| | | | - Alice Adkins
- Rehab R&D Center of Excellence, Atlanta VA Medical Center, USA
| | - Gobinda Pangeni
- Ophthalmology & Visual Sciences, University of Louisville, USA
| | - James Loudin
- Hansen Experimental Physics Laboratory, Stanford University, USA
| | - Keith Mathieson
- Hansen Experimental Physics Laboratory, Stanford University, USA; Institute of Photonics, University of Strathclyde, UK
| | - Daniel V Palanker
- Hansen Experimental Physics Laboratory, Stanford University, USA; Ophthalmology, Stanford University, USA
| | - Maureen A McCall
- Anatomical Sciences & Neurobiology, University of Louisville, USA; Ophthalmology & Visual Sciences, University of Louisville, USA
| | - Machelle T Pardue
- Ophthalmology, Emory University, USA; Rehab R&D Center of Excellence, Atlanta VA Medical Center, USA.
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Abstract
Retinal implants present an innovative way of restoring sight in degenerative retinal diseases. Previous reviews of research progress were written by groups developing their own devices. This systematic review objectively compares selected models by examining publications describing five representative retinal prostheses: Argus II, Boston Retinal Implant Project, Epi-Ret 3, Intelligent Medical Implants (IMI) and Alpha-IMS (Retina Implant AG). Publications were analysed using three criteria for interim success: clinical availability, vision restoration potential and long-term biocompatibility. Clinical availability: Argus II is the only device with FDA approval. Argus II and Alpha-IMS have both received the European CE Marking. All others are in clinical trials, except the Boston Retinal Implant, which is in animal studies. Vision restoration: resolution theoretically correlates with electrode number. Among devices with external cameras, the Boston Retinal Implant leads with 100 electrodes, followed by Argus II with 60 electrodes and visual acuity of 20/1262. Instead of an external camera, Alpha-IMS uses a photodiode system dependent on natural eye movements and can deliver visual acuity up to 20/546. Long-term compatibility: IMI offers iterative learning; Epi-Ret 3 is a fully intraocular device; Alpha-IMS uses intraocular photosensitive elements. Merging the results of these three criteria, Alpha-IMS is the most likely to achieve long-term success decades later, beyond current clinical availability.
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Maidenbaum S, Abboud S, Amedi A. Sensory substitution: closing the gap between basic research and widespread practical visual rehabilitation. Neurosci Biobehav Rev 2013; 41:3-15. [PMID: 24275274 DOI: 10.1016/j.neubiorev.2013.11.007] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2013] [Revised: 10/06/2013] [Accepted: 11/08/2013] [Indexed: 11/25/2022]
Abstract
Sensory substitution devices (SSDs) have come a long way since first developed for visual rehabilitation. They have produced exciting experimental results, and have furthered our understanding of the human brain. Unfortunately, they are still not used for practical visual rehabilitation, and are currently considered as reserved primarily for experiments in controlled settings. Over the past decade, our understanding of the neural mechanisms behind visual restoration has changed as a result of converging evidence, much of which was gathered with SSDs. This evidence suggests that the brain is more than a pure sensory-machine but rather is a highly flexible task-machine, i.e., brain regions can maintain or regain their function in vision even with input from other senses. This complements a recent set of more promising behavioral achievements using SSDs and new promising technologies and tools. All these changes strongly suggest that the time has come to revive the focus on practical visual rehabilitation with SSDs and we chart several key steps in this direction such as training protocols and self-train tools.
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Affiliation(s)
- Shachar Maidenbaum
- Department of Medical Neurobiology, The Institute for Medical Research Israel-Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 91220, Israel
| | - Sami Abboud
- Department of Medical Neurobiology, The Institute for Medical Research Israel-Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 91220, Israel
| | - Amir Amedi
- Department of Medical Neurobiology, The Institute for Medical Research Israel-Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 91220, Israel; The Edmond and Lily Safra Center for Brain Sciences (ELSC), The Hebrew University of Jerusalem, Jerusalem 91220, Israel.
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Shepherd RK, Shivdasani MN, Nayagam DAX, Williams CE, Blamey PJ. Visual prostheses for the blind. Trends Biotechnol 2013; 31:562-71. [PMID: 23953722 DOI: 10.1016/j.tibtech.2013.07.001] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 07/04/2013] [Accepted: 07/05/2013] [Indexed: 10/26/2022]
Abstract
After more than 40 years of research, visual prostheses are moving from the laboratory into the clinic. These devices are designed to provide prosthetic vision to the blind by stimulating localized neural populations in one of the retinotopically organized structures of the visual pathway - typically the retina or visual cortex. The long gestation of this research reflects the many significant technical challenges encountered including surgical access, mechanical stability, hardware miniaturization, hermetic encapsulation, high-density electrode arrays, and signal processing. This review provides an introduction to the pathophysiology of blindness; an overview of existing visual prostheses, their advantages and drawbacks; the perceptual effects evoked by electrical stimulation; as well as the role played by plasticity and training in clinical outcomes.
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Affiliation(s)
- Robert K Shepherd
- Bionics Institute, 384-388 Albert St East Melbourne, 3002, Victoria, Australia; Medical Bionics Department, University of Melbourne, 384-388 Albert St East Melbourne, 3002, Victoria, Australia.
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Psychophysically determined full-field stimulus thresholds (FST) in retinitis pigmentosa: relationships with electroretinography and visual field outcomes. Doc Ophthalmol 2013; 127:123-9. [PMID: 23733195 DOI: 10.1007/s10633-013-9393-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 05/23/2013] [Indexed: 12/27/2022]
Abstract
PURPOSE The purpose of this study is to describe the relationships between full-field stimulus threshold (FST), electroretinography (ERG), and visual field (VF) outcomes in retinitis pigmentosa (RP). METHODS Data from 47 patients with RP (n = 94 eyes) were evaluated. Patients were submitted to comprehensive ophthalmological examination including measurement of best-corrected visual acuity (BCVA), 30-2 threshold static VF, and microperimetry. Full-field ERG (ISCEV standard) was recorded, and achromatic FST was measured using a Diagnosys Espion system with the ColorDome™ LED full-field stimulator (Diagnosys LLC, Lowell, MA, USA). RESULTS BCVA mean ± SD was 0.31 ± 0.03 logMAR, and FST mean ± SD was -18.45 ± 9.53 dB. No significant correlation was found between BCVA and FST. In contrast, statistically significant correlations were found between FST and static 30-2 VF mean deviation (r = -0.389; P < 0.01), microperimetry mean threshold (r = -0.607; P < 0.01). Dark and light-adapted ERGs were detectable in 28 and 48 eyes, respectively. Nevertheless, considering only the eyes with recordable ERG responses, moderate correlations were found between combined dark-adapted a-wave amplitude (r = -0.560; P < 0.01), b-wave amplitude (r = -0.643; P < 0.001), 30-Hz flicker response (r = -0.501; P < 0.01), and FST, and high correlation with FST for cone b-wave amplitude (r = -0.715; P < 0.01). CONCLUSIONS FST could be successfully determined in RP patients with a wide range of vision loss. FST results showed stronger correlations with full-field ERG amplitude than with sensitivity measured with visual field tests. FST is as an alternative to VF or ERG for assessment of retinal function in patients unable to do visual fields or with non-detectable ERGs.
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Lu Y, Yan Y, Chai X, Ren Q, Chen Y, Li L. Electrical stimulation with a penetrating optic nerve electrode array elicits visuotopic cortical responses in cats. J Neural Eng 2013; 10:036022. [DOI: 10.1088/1741-2560/10/3/036022] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Stingl K, Zrenner E. Electronic Approaches to Restitute Vision in Patients with Neurodegenerative Diseases of the Retina. Ophthalmic Res 2013; 50:215-20. [DOI: 10.1159/000354424] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 07/15/2013] [Indexed: 11/19/2022]
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Neural stimulation for visual rehabilitation: advances and challenges. ACTA ACUST UNITED AC 2012; 107:421-31. [PMID: 23148976 DOI: 10.1016/j.jphysparis.2012.10.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Revised: 10/04/2012] [Accepted: 10/23/2012] [Indexed: 02/07/2023]
Abstract
Blindness affects tens of million people worldwide and its prevalence constantly increases along with population aging. In some pathologies leading to vision loss, prosthetic approaches are currently the only hope for the patient to recover some visual perception. Here, we review the latest advances in visual prosthetic strategies with their respective strength and weakness. The principle is to electrically stimulate neurons along the visual pathway. Ocular approaches target the remaining retinal cells whereas brain stimulation aims at stimulating higher visual structures directly. Even though ocular approaches are less invasive and easier to implement, brain stimulation can be applied to diseases where the connection between the retina and the brain is lost such as in glaucoma and could therefore benefit to patients with different pathologies. Today, numbers of groups are investigating these strategies and the first devices start being commercialized. However, critical bottlenecks still impair our scientific efforts towards efficient visual implants. These challenges include electrode miniaturization, material optimization, multiplexing of stimulation channels and encoding of visual information into electrical stimuli.
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