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https://www.readbyqxmd.com/read/28320674/simulation-study-of-an-ultrasound-retinal-prosthesis-with-a-novel-contact-lens-array-for-noninvasive-retinal-stimulation
#1
Mengdi Gao, Yanyan Yu, Huixia Zhao, Guofeng Li, Hongyang Jiang, Congzhi Wang, Feiyan Cai, Leanne Chan, Bernard Chiu, Wei Qian, Weibao Qiu, Hairong Zheng
Millions of people around the world suffer from varying degrees of vision loss (including complete blindness) because of retinal degenerative diseases. Artificial retinal prosthesis, which is usually based on electrical neurostimulation, are the most advanced technology for different types of retinal degeneration. However, this technology involves placing a device into the eyeball, and such a highly invasive procedure is inevitably highly risk and expensive. Ultrasound has been demonstrated to be a promising technology for noninvasive neurostimulation, making it possible to stimulate the retina and induce action potentials similar to those elicited by light stimulation...
March 15, 2017: IEEE Transactions on Neural Systems and Rehabilitation Engineering
https://www.readbyqxmd.com/read/28269489/eye-movements-as-a-marker-for-visual-prosthesis-spatial-mapping-a-feasibility-study-using-a-blind-patient-implanted-with-the-argus-ii-retinal-prosthesis
#2
Avi Caspi, Jessy Dorn, John B Helder, Kapil D Katyal, Arup Roy
Spatial mapping, the location in space of a perceived location due to an implanted electrode's electrical stimulation is important in the design of visual prostheses. Generally, a visual prosthesis system consists of an implanted electrode array, an external camera that acquires the image, and a transmitter that sends the information to the implanted electrodes. In cortical visual implant, the layout of the implanted array in most cases does not match the retinotopic map and it is necessary to find the location of the percept of each electrode in world coordinates...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28269486/tuning-electrical-stimulation-for-thalamic-visual-prosthesis-an-autoencoder-based-approach
#3
Amr Jawwad, Hossam H Abolfotuh, Bassem Abdullah, Hani M K Mahdi, Seif Eldawlatly
Visual prosthesis holds hope of vision restoration for millions with retinal degenerative diseases. Machine learning techniques such as artificial neural networks could help in improving prosthetic devices as they could learn how the brain encodes information and imitate that code. This paper introduces an autoencoder-based approach for tuning thalamic visual prostheses. The objective of the proposed approach is to estimate electrical stimuli that are equivalent to a given natural visual stimulus, in a way such that they both elicit responses that are as similar as possible when introduced to a Lateral Geniculate Nucleus (LGN) population...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28268360/embedded-clutter-reduction-and-face-detection-algorithms-for-a-visual-prosthesis
#4
Derek M Rollend, Paul E Rosendall, Kevin C Wolfe, Dean M Kleissas, Seth D Billings, Jonathan M Oben, John B Helder, Francesco V Tenore, Philippe M Burlina, Arup Roy, Robert Greenberg, Kapil D Katyal
Retinal prosthetic devices can significantly and positively impact the ability of visually challenged individuals to live a more independent life. We describe a visual processing system which leverages image analysis techniques to produce visual patterns and allows the user to more effectively perceive their environment. These patterns are used to stimulate a retinal prosthesis to allow self guidance and a higher degree of autonomy for the affected individual. Specifically, we describe an image processing pipeline that allows for object and face localization in cluttered environments as well as various contrast enhancement strategies in the "implanted image...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28258971/an-image-processing-strategy-to-extract-important-information-suitable-for-a-low-size-stimulus-pattern-in-a-retinal-prosthesis
#5
Yili Chen, Jixiang Fu, Dawei Chu, Rongmao Li, Yaoqin Xie
BACKGROUND: A retinal prosthesis is designed to help the blind to obtain some sight. It consists of an external part and an internal part. The external part is made up of a camera, an image processor and an RF transmitter. The internal part is made up of an RF receiver, implant chip and microelectrode. METHODS: Currently, the number of microelectrodes is in the hundreds, and we do not know the mechanism for using an electrode to stimulate the optic nerve. A simple hypothesis is that the pixels in an image correspond to the electrode...
March 4, 2017: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/28250420/a-fully-organic-retinal-prosthesis-restores-vision-in-a-rat-model-of-degenerative-blindness
#6
José Fernando Maya-Vetencourt, Diego Ghezzi, Maria Rosa Antognazza, Elisabetta Colombo, Maurizio Mete, Paul Feyen, Andrea Desii, Ambra Buschiazzo, Mattia Di Paolo, Stefano Di Marco, Flavia Ticconi, Laura Emionite, Dmytro Shmal, Cecilia Marini, Ilaria Donelli, Giuliano Freddi, Rita Maccarone, Silvia Bisti, Gianmario Sambuceti, Grazia Pertile, Guglielmo Lanzani, Fabio Benfenati
The degeneration of photoreceptors in the retina is one of the major causes of adult blindness in humans. Unfortunately, no effective clinical treatments exist for the majority of retinal degenerative disorders. Here we report on the fabrication and functional validation of a fully organic prosthesis for long-term in vivo subretinal implantation in the eye of Royal College of Surgeons rats, a widely recognized model of retinitis pigmentosa. Electrophysiological and behavioural analyses reveal a prosthesis-dependent recovery of light sensitivity and visual acuity that persists up to 6-10 months after surgery...
March 6, 2017: Nature Materials
https://www.readbyqxmd.com/read/28227741/eye-movements-as-a-marker-for-visual-prosthesis-spatial-mapping-a-feasibility-study-using-a-blind-patient-implanted-with-the-argus-ii-retinal-prosthesis
#7
Avi Caspi, Jessy Dorn, John B Helder, Kapil D Katyal, Arup Roy, Avi Caspi, Jessy Dorn, John B Helder, Kapil D Katyal, Arup Roy, John B Helder, Kapil D Katyal, Jessy Dorn, Arup Roy, Avi Caspi
Spatial mapping, the location in space of a perceived location due to an implanted electrode's electrical stimulation is important in the design of visual prostheses. Generally, a visual prosthesis system consists of an implanted electrode array, an external camera that acquires the image, and a transmitter that sends the information to the implanted electrodes. In cortical visual implant, the layout of the implanted array in most cases does not match the retinotopic map and it is necessary to find the location of the percept of each electrode in world coordinates...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227738/tuning-electrical-stimulation-for-thalamic-visual-prosthesis-an-autoencoder-based-approach
#8
Amr Jawwad, Hossam H Abolfotuh, Bassem Abdullah, Hani M K Mahdi, Seif Eldawlatly, Amr Jawwad, Hossam H Abolfotuh, Bassem Abdullah, Hani M K Mahdi, Seif Eldawlatly, Amr Jawwad, Hani M K Mahdi, Bassem Abdullah, Seif Eldawlatly, Hossam H Abolfotuh
Visual prosthesis holds hope of vision restoration for millions with retinal degenerative diseases. Machine learning techniques such as artificial neural networks could help in improving prosthetic devices as they could learn how the brain encodes information and imitate that code. This paper introduces an autoencoder-based approach for tuning thalamic visual prostheses. The objective of the proposed approach is to estimate electrical stimuli that are equivalent to a given natural visual stimulus, in a way such that they both elicit responses that are as similar as possible when introduced to a Lateral Geniculate Nucleus (LGN) population...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226523/embedded-clutter-reduction-and-face-detection-algorithms-for-a-visual-prosthesis
#9
Derek M Rollend, Paul E Rosendall, Kevin C Wolfe, Dean M Kleissas, Seth D Billings, Jonathan M Oben, John B Helder, Francesco V Tenore, Philippe M Burlina, Arup Roy, Robert Greenberg, Kapil D Katyal, Derek M Rollend, Paul E Rosendall, Kevin C Wolfe, Dean M Kleissas, Seth D Billings, Jonathan M Oben, John B Helder, Francesco V Tenore, Philippe M Burlina, Arup Roy, Robert Greenberg, Kapil D Katyal, Arup Roy, Dean M Kleissas, John B Helder, Seth D Billings, Robert Greenberg, Philippe M Burlina, Derek M Rollend, Paul E Rosendall, Jonathan M Oben, Kapil D Katyal, Francesco V Tenore, Kevin C Wolfe
Retinal prosthetic devices can significantly and positively impact the ability of visually challenged individuals to live a more independent life. We describe a visual processing system which leverages image analysis techniques to produce visual patterns and allows the user to more effectively perceive their environment. These patterns are used to stimulate a retinal prosthesis to allow self guidance and a higher degree of autonomy for the affected individual. Specifically, we describe an image processing pipeline that allows for object and face localization in cluttered environments as well as various contrast enhancement strategies in the "implanted image...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28209965/high-amplitude-electrical-stimulation-can-reduce-elicited-neuronal-activity-in-visual-prosthesis
#10
Alejandro Barriga-Rivera, Tianruo Guo, Chih-Yu Yang, Amr Al Abed, Socrates Dokos, Nigel H Lovell, John W Morley, Gregg J Suaning
Retinal electrostimulation is promising a successful therapy to restore functional vision. However, a narrow stimulating current range exists between retinal neuron excitation and inhibition which may lead to misperformance of visual prostheses. As the conveyance of representation of complex visual scenes may require neighbouring electrodes to be activated simultaneously, electric field summation may contribute to reach this inhibitory threshold. This study used three approaches to assess the implications of relatively high stimulating conditions in visual prostheses: (1) in vivo, using a suprachoroidal prosthesis implanted in a feline model, (2) in vitro through electrostimulation of murine retinal preparations, and (3) in silico by computing the response of a population of retinal ganglion cells...
February 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28203188/endoscope-assisted-and-controlled-argus-ii-epiretinal-prosthesis-implantation-in-late-stage-retinitis-pigmentosa-a-report-of-2-cases
#11
Emin Özmert, Sibel Demirel
Several different approaches for restoring sight in subjects who are blind due to outer retinal degeneration are currently under investigation, including stem cell therapy, gene therapy, and visual prostheses. Although many different types of visual prostheses have shown promise, to date, the Argus II Epiretinal Prosthesis System, developed in a clinical setting over the course of 10 years, is the world's first and only retinal prosthesis that has been approved by the United States Food and Drug Administration (FDA) and has been given the CE-Mark for sale within the European Economic Area (EEA)...
September 2016: Case Reports in Ophthalmology
https://www.readbyqxmd.com/read/28181076/visual-evoked-potential-in-rcs-rats-with-okayama-university-type-retinal-prosthesis-ourep%C3%A2-implantation
#12
Alamusi, Toshihiko Matsuo, Osamu Hosoya, Tetsuya Uchida
Photoelectric dye-coupled polyethylene film, designated Okayama University type-retinal prosthesis or OUReP™, generates light-evoked surface electric potentials and stimulates neurons. The dye-coupled films or plain films were implanted subretinally in both eyes of 10 Royal College of Surgeons rats with hereditary retinal dystrophy at the age of 6 weeks. Visual evoked potentials in response to monocular flashing light stimuli were recorded from cranially-fixed electrodes, 4 weeks and 8 weeks after the implantation...
February 8, 2017: Journal of Artificial Organs: the Official Journal of the Japanese Society for Artificial Organs
https://www.readbyqxmd.com/read/28135031/retinal-prosthesis-that-incorporates-the-organization-of-the-nerve-fibre-layer
#13
REVIEW
Thomas FitzGibbon
Recent efforts to restore partial vision in blind patients have made significant progress. Currently, prosthetic design concentrates on stimulating as many foveal retinal ganglion cells as possible but is hampered by stimulation of the nerve fibre layer. This results in a nonvisuotopic arrangement of phosphenes (stimulation percepts). This article suggests that by extending the stimulation area well beyond the fovea and stimulating the nerve fibre layer, axons from any remaining ganglion cells in more peripheral regions of the retina (low acuity) can be used to generate a visuotopic map...
January 30, 2017: Clinical & Experimental Ophthalmology
https://www.readbyqxmd.com/read/28114567/retinotopic-to-spatiotopic-mapping-in-blind-patients-implanted-with-the-argus-ii-retinal-prosthesis
#14
Avi Caspi, Arup Roy, Jessy D Dorn, Robert J Greenberg
Purpose: To quantify the precision of mapping from retinotopic (retina-centered) to spatiotopic (world-centered) coordinates in blind humans implanted with a retinal prosthesis device. Additionally, to demonstrate that an eye tracker can be calibrated on sightless patients based on the percept from a visual implant. Methods: We directly activated epiretinal electrodes to create retinotopic stimuli and recorded the location of the percept at world-based coordinates...
January 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/28113816/versatile-stimulation-back-end-with-programmable-exponential-current-pulse-shapes-for-a-retinal-visual-prosthesis
#15
Mohammad Hossein Maghami, Amir M Sodagar, Mohamad Sawan
No abstract text is available yet for this article.
March 30, 2016: IEEE Transactions on Neural Systems and Rehabilitation Engineering
https://www.readbyqxmd.com/read/28009400/optical-coherence-tomography-imaging-in-the-management-of-the-argus-ii-retinal-prosthesis-system
#16
Francesco Parmeggiani, Katia De Nadai, Angela Piovan, Andrea Binotto, Sara Zamengo, Marzio Chizzolini
PURPOSE: To report a real-life experience with the Argus II retinal prosthesis system in blind patients with end-stage retinitis pigmentosa (RP) or choroideremia (CHM), focusing on the pivotal role of optical coherence tomography (OCT) in both preoperative and postoperative management. METHODS: This hospital-based case series included 3 blind patients who were uneventfully implanted with Argus II epiretinal device. These patients (2 with RP and 1 with CHM) were selected during the Argus™ II Retinal Prosthesis System PostMarket Surveillance Study Protocol...
January 19, 2017: European Journal of Ophthalmology
https://www.readbyqxmd.com/read/27942525/are-long-stimulus-pulse-durations-the-answer-to-improving-spatial-resolution-in-retinal-prostheses
#17
COMMENT
Matthew A Petoe, Mohit N Shivdasani
Retinal prostheses can provide artificial vision to patients with degenerate retinae by electrically stimulating the remaining inner retinal neurons. The evoked perception is generally adequate for light localization, but of limited spatial resolution owing to the indiscriminate activation of multiple retinal cell types, leading to distortions in the perceived image. Here we present a perspective on a recent work by Weitz and colleagues who demonstrate a focal confinement of retinal ganglion cell (RGC) activation when using extended pulse durations in the stimulation waveform...
November 2016: Annals of Translational Medicine
https://www.readbyqxmd.com/read/27929043/differential-stimulation-of-the-retina-with-subretinally-injected-exogenous-neurotransmitter-a-biomimetic-alternative-to-electrical-stimulation
#18
Corey M Rountree, Samsoon Inayat, John B Troy, Laxman Saggere
Subretinal stimulation of the retina with neurotransmitters, the normal means of conveying visual information, is a potentially better alternative to electrical stimulation widely used in current retinal prostheses for treating blindness from photoreceptor degenerative diseases. Yet, no subretinal electrical or chemical stimulation study has stimulated the OFF and ON pathways differentially through inner retinal activation. Here, we demonstrate the feasibility of differentially stimulating retinal ganglion cells (RGCs) through the inner nuclear layer of the retina with glutamate, a primary neurotransmitter chemical, in a biomimetic way...
December 8, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27916963/neuron-stimulation-device-integrated-with-silicon-nanowire-based-photodetection-circuit-on-a-flexible-substrate
#19
Suk Won Jung, Jong Yoon Shin, Kilwha Pi, Yong Sook Goo, Dong-Il Dan Cho
This paper proposes a neural stimulation device integrated with a silicon nanowire (SiNW)-based photodetection circuit for the activation of neurons with light. The proposed device is comprised of a voltage divider and a current driver in which SiNWs are used as photodetector and field-effect transistors; it has the functions of detecting light, generating a stimulation signal in proportion to the light intensity, and transmitting the signal to a micro electrode. To show the applicability of the proposed neural stimulation device as a high-resolution retinal prosthesis system, a high-density neural stimulation device with a unit cell size of 110 × 110 μ m and a resolution of 32 × 32 was fabricated on a flexible film with a thickness of approximately 50 μm...
December 1, 2016: Sensors
https://www.readbyqxmd.com/read/27900949/prediction-of-cortical-responses-to-simultaneous-electrical-stimulation-of-the-retina
#20
Kerry J Halupka, Mohit N Shivdasani, Shaun L Cloherty, David B Grayden, Yan T Wong, Anthony N Burkitt, Hamish Meffin
OBJECTIVE: Simultaneous electrical stimulation of multiple electrodes has shown promise in diversifying the responses that can be elicited by retinal prostheses compared to interleaved single electrode stimulation. However, the effects of interactions between electrodes are not well understood and clinical trials with simultaneous stimulation have produced inconsistent results. We investigated the effects of multiple electrode stimulation of the retina by developing a model of cortical responses to retinal stimulation...
November 30, 2016: Journal of Neural Engineering
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