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Palanker D. Electronic Retinal Prostheses. Cold Spring Harb Perspect Med 2023; 13:a041525. [PMID: 36781222 PMCID: PMC10411866 DOI: 10.1101/cshperspect.a041525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Retinal prostheses are a promising means for restoring sight to patients blinded by photoreceptor atrophy. They introduce visual information by electrical stimulation of the surviving inner retinal neurons. Subretinal implants target the graded-response secondary neurons, primarily the bipolar cells, which then transfer the information to the ganglion cells via the retinal neural network. Therefore, many features of natural retinal signal processing can be preserved in this approach if the inner retinal network is retained. Epiretinal implants stimulate primarily the ganglion cells, and hence should encode the visual information in spiking patterns, which, ideally, should match the target cell types. Currently, subretinal arrays are being developed primarily for restoration of central vision in patients impaired by age-related macular degeneration (AMD), while epiretinal implants-for patients blinded by retinitis pigmentosa, where the inner retina is less preserved. This review describes the concepts and technologies, preclinical characterization of prosthetic vision and clinical outcomes, and provides a glimpse into future developments.
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Affiliation(s)
- Daniel Palanker
- Department of Ophthalmology and Hansen Experimental Physics Laboratory, Stanford University, Stanford, California 94305, USA
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Chen J, Poulaki V, Kim SJ, Eldred WD, Kane S, Gingerich M, Shire DB, Jensen R, DeWalt G, Kaplan HJ, Rizzo JF. Implantation and Extraction of Penetrating Electrode Arrays in Minipig Retinas. Transl Vis Sci Technol 2020; 9:19. [PMID: 32821491 PMCID: PMC7401973 DOI: 10.1167/tvst.9.5.19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 12/31/2019] [Indexed: 12/12/2022] Open
Abstract
Purpose This work was motivated by the goals of demonstrating methods to fabricate and implant large numbers of penetrating arrays into the retina and the feasibility of extraction. Methods Arrays of inactive, three-dimensional (3D) SU-8 structures were microfabricated onto 13-µm polyimide substrates. Standard vitreoretinal surgical techniques were used with an ab externo approach for subretinal implantation of arrays in 12 mini-pigs. In the first three surgeries, different post-geometries were explored, while a preferred design (128-µm tall, 30-µm diameter, 200-µm spacing) was used for the remaining nine implantations. Two arrays were extracted. Funduscopy, optical coherence tomography (OCT) and immunohistochemistry of the retinae were performed. The unoperated eyes and tissue far from implantation served as controls. A thirteenth pig was implanted with a planar array. Results Ten implant surgeries had no significant complication, and two arrays were successfully extracted. One retinal tear occurred after implantation due to too long posts in an early surgery. In “successful” cases, OCT showed close apposition of the arrays to the retina and integration of the posts, the tops of which were positioned at the junction of the inner plexiform and ganglion cells, without significant gliosis. Conclusions These results provide a proof-of-concept that relatively large numbers of 3D posts can be implanted into, and extracted from, the retina of mini-pigs. Our surgical numbers were relatively small, especially for the extractions, and our conclusions must be viewed with that limitation. Our methods are applicable for human surgeries. Translational Relevance This study provides results of implantation and extraction of relatively large numbers of 3D posts from the retina of minipig eyes. If similar technology were used in humans, a 3D array of this type should lower perceptual thresholds, provide safer long-term stimulation, and perhaps provide better perceptual outcomes.
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Affiliation(s)
- Jinghua Chen
- Department of Ophthalmology, University of Florida, College of Medicine, Gainesville, FL, USA
| | - Vasiliki Poulaki
- Boston VA Healthcare System, Ophthalmology, Jamaica Plain, Boston, MA, USA
| | - Seong-Joon Kim
- Department of Ophthalmology, Seoul National University College of Medicine, Seoul, Korea
| | | | | | | | | | - Ralph Jensen
- Boston VA Healthcare System, Ophthalmology, Jamaica Plain, Boston, MA, USA
| | - Gloria DeWalt
- Department of Biology, Boston University, Boston, MA, USA
| | - Henry J Kaplan
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, KY, USA
| | - Joseph F Rizzo
- Department of Ophthalmology, Harvard Medical School and the Massachusetts Eye and Ear, Boston, MA, USA
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Xiao Y, Wang Y, Li F, Lin T, Huffman K, Landeros S, Bosse B, Jing Y, Bartsch DU, Thorogood S, Freeman WR, Cheng L. Acute Rabbit Eye Model for Testing Subretinal Prostheses. Transl Vis Sci Technol 2019; 8:20. [PMID: 31602345 PMCID: PMC6779096 DOI: 10.1167/tvst.8.5.20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 07/23/2019] [Indexed: 11/24/2022] Open
Abstract
Purpose Subretinal prostheses are a novel technology for restoring useful vision in patients with retinitis pigmentosa or age-related macular degeneration. We characterize the surgical implantation technique and functional time window of an acute rabbit eye model for testing of human subretinal prostheses. Methods Retinal prostheses were implanted subretinally in 26 rabbits using a two-step technique. Fundus imaging, fluorescein fundus angiography, and optical coherence topography (OCT) were conducted postoperatively from days 1 to 21 to monitor prosthesis positioning and retinal anatomic changes. Results Successful implantation and excellent retina apposition were achieved in 84.6% of the rabbits. OCTs showed the overlying retina at full thickness for the first 2 days after implantation. Histology confirmed intact inner layers of the overlying retina until day 3. Progressive atrophy of the overlying retina was revealed by repeated OCTs; approximately 40% of the retina thickness remained on postoperative days 5 and 6. Conclusions The two-step implantation technique works well for the rabbit eye model with human prostheses. Rabbit retina may be used for acute electrophysiologic testing of a retinal prosthesis, but is unsuitable for chronic studies due to the merangiotic retina and its limited time window of validity. Translational Relevance The improved efficacy in prosthesis surgery using this technique will circumvent the challenges in animal models that provide human-like features critical for the transition into human clinical trials.
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Affiliation(s)
- Ying Xiao
- Department of Ophthalmology, Jacobs Retina Center at Shiley Eye Institute, University of California, San Diego, La Jolla, CA, USA
| | - Yuqin Wang
- Department of Ophthalmology, Jacobs Retina Center at Shiley Eye Institute, University of California, San Diego, La Jolla, CA, USA
| | - Fangting Li
- Department of Ophthalmology, Jacobs Retina Center at Shiley Eye Institute, University of California, San Diego, La Jolla, CA, USA
| | - Tiezhu Lin
- Department of Ophthalmology, Jacobs Retina Center at Shiley Eye Institute, University of California, San Diego, La Jolla, CA, USA
| | - Kristyn Huffman
- Department of Ophthalmology, Jacobs Retina Center at Shiley Eye Institute, University of California, San Diego, La Jolla, CA, USA
| | - Stephanie Landeros
- Department of Ophthalmology, Jacobs Retina Center at Shiley Eye Institute, University of California, San Diego, La Jolla, CA, USA
| | | | - Yi Jing
- Nanovision Biosciences, Inc., La Jolla, CA, USA
| | - Dirk-Uwe Bartsch
- Department of Ophthalmology, Jacobs Retina Center at Shiley Eye Institute, University of California, San Diego, La Jolla, CA, USA
| | | | - William R Freeman
- Department of Ophthalmology, Jacobs Retina Center at Shiley Eye Institute, University of California, San Diego, La Jolla, CA, USA
| | - Lingyun Cheng
- Department of Ophthalmology, Jacobs Retina Center at Shiley Eye Institute, University of California, San Diego, La Jolla, CA, USA
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Abstract
Sensory neuroprostheses for restoration of vision are a technical approach for treatment of previously untreatable blindness. These systems consist of a technical sensor such as a camera and an implanted multi-electrode array within the visual system. The image information from the sensor is processed with specially designed integrated circuits in such a way that the stimulation pulses can be determined and presented to the implanted multi-electrode matrix. Energy supply and the transfer of the stimulus pulse information is realized either via direct cable connections within the site of the implant or by telemetric inductive links. Currently, two retinal implant systems are approved in the European Union (EU) to be used in blind patients with retinitis pigmentosa. With both systems basic visual functions can be restored. The complication rate is relatively low given the complexity of the surgical procedure. Other systems are still under development but approval studies by several manufacturers and consortia are already in preparation.
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Affiliation(s)
- P Walter
- Klinik für Augenheilkunde, Uniklinik RWTH Aachen, Pauwelsstr. 30, 52074, Aachen, Deutschland.
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Lohmann TK, Kanda H, Morimoto T, Endo T, Miyoshi T, Nishida K, Kamei M, Walter P, Fujikado T. Surgical feasibility and biocompatibility of wide-field dual-array suprachoroidal-transretinal stimulation prosthesis in middle-sized animals. Graefes Arch Clin Exp Ophthalmol 2015; 254:661-73. [PMID: 26194404 DOI: 10.1007/s00417-015-3104-1] [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: 03/11/2015] [Revised: 06/24/2015] [Accepted: 07/02/2015] [Indexed: 12/17/2022] Open
Abstract
PURPOSE To investigate the safety and efficacy of a newly-developed wide-field dual-array suprachoroidal-transretinal stimulation (STS) prosthesis in middle-sized animals. METHODS The prosthesis consisted of two arrays with 50 to 74 electrodes. To test the feasibility of implanting the prosthesis and its efficacy, the prosthesis was implanted for 14 days into two rabbits. Optical coherence tomography (OCT) and ophthalmoscopy were performed 7 and 14 days after the implantation. Then the rabbits were euthanized, eyes were enucleated, and the posterior segment of the eye was examined histologically. In a second experiment, the arrays were implanted into two cats, and their ability to elicit neural responses was determined by electrically evoked potentials (EEPs) at the chiasm and by optical imaging of the retina. RESULTS All arrays were successfully implanted, and no major complications occurred during the surgery or during the 2-week postoperative period. Neither OCT nor ophthalmoscopy showed any major complications or instability of the arrays. Histological evaluations showed only mild cellular infiltration and overall good retinal preservation. Stimulation of the retina by the arrays evoked EEPs recorded from the chiasm. Retinal imaging showed that the electrical pulses from the arrays altered the retinal images indicating an activation of retinal neurons. The thresholds were as low as 100 μA for a chiasm response and 300 μA for the retinal imaging. CONCLUSION Implantation of a newly-developed dual-array STS prosthesis for 2 weeks in rabbits was feasible surgically, and safe. The results of retinal imaging showed that the dual-array system was able to activate retinal neurons. We conclude that the dual-array design can be implanted without complication and is able to activate retinal neurons and optic nerve axons.
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Affiliation(s)
- Tibor Karl Lohmann
- Department of Applied Visual Science, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Department of Ophthalmology, RWTH Aachen University, Aachen, Germany
| | - Hiroyuki Kanda
- Department of Applied Visual Science, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Takeshi Morimoto
- Department of Applied Visual Science, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Takao Endo
- Department of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Tomomitsu Miyoshi
- Department of Integrative Physiology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Kentaro Nishida
- Department of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Motohiro Kamei
- Department of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Peter Walter
- Department of Ophthalmology, RWTH Aachen University, Aachen, Germany
| | - Takashi Fujikado
- Department of Applied Visual Science, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.
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Jacobson SG, Cideciyan AV, Aguirre GD, Roman AJ, Sumaroka A, Hauswirth WW, Palczewski K. Improvement in vision: a new goal for treatment of hereditary retinal degenerations. Expert Opin Orphan Drugs 2015; 3:563-575. [PMID: 26246977 PMCID: PMC4487613 DOI: 10.1517/21678707.2015.1030393] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Introduction: Inherited retinal degenerations (IRDs) have long been considered untreatable and incurable. Recently, one form of early-onset autosomal recessive IRD, Leber congenital amaurosis (LCA) caused by mutations in RPE65 (retinal pigment epithelium-specific protein 65 kDa) gene, has responded with some improvement of vision to gene augmentation therapy and oral retinoid administration. This early success now requires refinement of such therapeutics to fully realize the impact of these major scientific and clinical advances. Areas covered: Progress toward human therapy for RPE65-LCA is detailed from the understanding of molecular mechanisms to preclinical proof-of-concept research to clinical trials. Unexpected positive and complicating results in the patients receiving treatment are explained. Logical next steps to advance the clinical value of the therapeutics are suggested. Expert opinion: The first molecularly based early-phase therapies for an IRD are remarkably successful in that vision has improved and adverse events are mainly associated with surgical delivery to the subretinal space. Yet, there are features of the gene augmentation therapeutic response, such as slowed kinetics of night vision, lack of foveal cone function improvement and relentlessly progressive retinal degeneration despite therapy, that still require research attention.
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Affiliation(s)
- Samuel G Jacobson
- University of Pennsylvania, Scheie Eye Institute, Perelman School of Medicine, Department of Ophthalmology , Philadelphia, PA, USA
| | - Artur V Cideciyan
- University of Pennsylvania, Scheie Eye Institute, Perelman School of Medicine, Department of Ophthalmology , Philadelphia, PA, USA
| | - Gustavo D Aguirre
- University of Pennsylvania, School of Veterinary Medicine, Section of Ophthalmology , Philadelphia, PA, USA
| | - Alejandro J Roman
- University of Pennsylvania, Scheie Eye Institute, Perelman School of Medicine, Department of Ophthalmology , Philadelphia, PA, USA
| | - Alexander Sumaroka
- University of Pennsylvania, Scheie Eye Institute, Perelman School of Medicine, Department of Ophthalmology , Philadelphia, PA, USA
| | | | - Krzysztof Palczewski
- Case Western University, School of Medicine, Cleveland Center for Membrane and Structural Biology, Department of Pharmacology , Cleveland, OH, USA
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Van Gelder RN. Photochemical approaches to vision restoration. Vision Res 2015; 111:134-41. [PMID: 25680758 DOI: 10.1016/j.visres.2015.02.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 01/06/2015] [Accepted: 02/02/2015] [Indexed: 11/18/2022]
Abstract
Photoswitches are traditional pharmacologic agonists, antagonists, or channel blockers that are covalently modified with an azobenzene derivative. Azobenzene undergoes wavelength-dependent isomerization between cis and trans conformation. For some photoswitches, only one of these configurations is biologically active, resulting in light-dependent activation or inhibition of function. Photoswitches that feature a quaternary ammonium coupled to the azobenzene moiety cause light-dependent neuronal depolarization due to blockage of voltage-gated potassium channels. Two photoswitch strategies have been pursued. In the one-component strategy, the photoswitch is applied to native receptors; in the two-component strategy, the photoswitch is combined with virally-mediated expression of a genetically modified receptor, to which the photoswitch may covalently bind. The former approach is simpler but the latter allows precise anatomic targeting of photoswitch activity. Acrylamide-azobenzene-quaternary ammonium (AAQ) is the prototypical first-generation one-component photoswitch. When applied to retinas with outer retinal degeneration, ganglion cell firing occurs in response to blue light, and is abrogated by green light. In vivo, AAQ restored pupillary light responses and behavioral light responses in blind animals. DENAQ is a prototypical second generation one-component photoswitch. It features spontaneous thermal relaxation so cell firing ceases in dark, and features a red-shifted activation spectrum. Interestingly, DENAQ only photoswitches in retinas with outer retinal degeneration. MAG is a photoswitched glutamate analog which covalently binds to a modified ionotropic glutamate receptor, LiGluR. When applied together, MAG and LiGluR also rescue physiologic and behavioral light responses in blind mice. Together, photoswitch compounds offer a potentially useful approach to restoration of vision in outer retinal degeneration.
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Affiliation(s)
- Russell N Van Gelder
- Department of Ophthalmology, University of Washington School of Medicine, United States; Department of Pathology, University of Washington School of Medicine, United States; Department of Biological Structure, University of Washington School of Medicine, United States.
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Majdi JA, Minnikanti S, Peixoto N, Agrawal A, Cohen ED. Access resistance of stimulation electrodes as a function of electrode proximity to the retina. J Neural Eng 2014; 12:016006. [DOI: 10.1088/1741-2560/12/1/016006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Kitiratschky VBD, Stingl K, Wilhelm B, Peters T, Besch D, Sachs H, Gekeler F, Bartz-Schmidt KU, Zrenner E. Safety evaluation of "retina implant alpha IMS"--a prospective clinical trial. Graefes Arch Clin Exp Ophthalmol 2014; 253:381-7. [PMID: 25219982 DOI: 10.1007/s00417-014-2797-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2013] [Revised: 08/28/2014] [Accepted: 08/29/2014] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND To restore vision in patients with retinitis pigmentosa, several types of electronic devices have been developed to stimulate neurons at different levels along the visual pathway. Subretinal stimulation of the retina with the Retina Implant Alpha IMS (Retina Implant AG, Reutlingen, Germany) has been demonstrated to provide useful vision in daily life. Here we evaluated the safety of this device. METHODS An interventional, prospective, multi-center, single-arm study was conducted in patients with retinitis pigmentosa with the Retina Implant Alpha IMS. The results from the first nine patients of a single center regarding safety of the device are reported. Any untoward medical occurrence related or unrelated to the tested device was documented and evaluated. RESULTS Nine adult subjects were included in the study at the Tübingen site. Seventy-five adverse events occurred in total, and 53 affected the eye and its adnexa. Thirty-one ocular adverse events had a relationship to the implant that was classified as "certain" while 19 had a probable or possible relationship; three had no relationship to the implant. Thirty-nine ocular adverse events resolved without sequelae, two resolved with sequelae, 11 remained unresolved, and in one the status was unknown. The intensity of ocular adverse events was mild in the majority of cases (n = 45), while six were of moderate and two of severe intensity. There was no non-ocular adverse event with certain relationship to the device. One subject lost light perception (without light localization) in her study eye. CONCLUSIONS In conclusion, this prospective study, "Safety and Efficacy of Subretinal Implants for Partial Restoration of Vision in Blind Patients," shows that the Retina Implant Alpha IMS is an option for restoring vision using a subretinal stimulation device with a clinically acceptable safety profile.
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Stingl K, Bartz-Schmidt KU, Besch D, Braun A, Bruckmann A, Gekeler F, Greppmaier U, Hipp S, Hörtdörfer G, Kernstock C, Koitschev A, Kusnyerik A, Sachs H, Schatz A, Stingl KT, Peters T, Wilhelm B, Zrenner E. Artificial vision with wirelessly powered subretinal electronic implant alpha-IMS. Proc Biol Sci 2013; 280:20130077. [PMID: 23427175 PMCID: PMC3619489 DOI: 10.1098/rspb.2013.0077] [Citation(s) in RCA: 229] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
This study aims at substituting the essential functions of photoreceptors in patients who are blind owing to untreatable forms of hereditary retinal degenerations. A microelectronic neuroprosthetic device, powered via transdermal inductive transmission, carrying 1500 independent microphotodiode-amplifier-electrode elements on a 9 mm2 chip, was subretinally implanted in nine blind patients. Light perception (8/9), light localization (7/9), motion detection (5/9, angular speed up to 35 deg s−1), grating acuity measurement (6/9, up to 3.3 cycles per degree) and visual acuity measurement with Landolt C-rings (2/9) up to Snellen visual acuity of 20/546 (corresponding to decimal 0.037 or corresponding to 1.43 logMAR (minimum angle of resolution)) were restored via the subretinal implant. Additionally, the identification, localization and discrimination of objects improved significantly (n = 8; p < 0.05 for each subtest) in repeated tests over a nine-month period. Three subjects were able to read letters spontaneously and one subject was able to read letters after training in an alternative-force choice test. Five subjects reported implant-mediated visual perceptions in daily life within a field of 15° of visual angle. Control tests were performed each time with the implant's power source switched off. These data show that subretinal implants can restore visual functions that are useful for daily life.
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Affiliation(s)
- Katarina Stingl
- Centre for Ophthalmology, University of Tübingen, Schleichstraße 12-16, Tübingen, Germany
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Rountree CM, Inayat S, Troy JB, Saggere L. Development of a chemical retinal prosthesis: stimulation of rat retina with glutamate. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2013; 2013:3134-3137. [PMID: 24110392 DOI: 10.1109/embc.2013.6610205] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Retinal degenerative diseases cause partial or total blindness and affect millions of people worldwide, yet currently have no treatment. Retinal prostheses using electrical stimulation are being developed but face significant problems moving forward. Here we propose using chemical stimulation, via the neurotransmitter glutamate, to modulate retinal ganglion cell (RGC) spike rates. Our results demonstrate that it is feasible to stimulate RGCs in an explanted retina using focal ejections of glutamate from either subretinal or epiretinal sides. Preliminary evidence suggests we are primarily activating RGCs as opposed to bipolar cells. This is an important first step in the development of a chemical retinal prosthesis based on microelectromechanical systems (MEMS) technology.
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