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https://www.readbyqxmd.com/read/29201260/retinal-prosthesis-system-for-advanced-retinitis-pigmentosa-a-health-technology-assessment-update
#1
(no author information available yet)
Background: Retinitis pigmentosa is a group of inherited disorders characterized by the degeneration of the photoreceptors in the retina, resulting in progressive vision loss. The Argus II system is designed to restore partial functional vision in patients with profound vision loss from advanced retinitis pigmentosa. At present, it is the only treatment option approved by Health Canada for this patient population. In June 2016, Health Quality Ontario published a health technology assessment of the Argus II retinal prosthesis system for patients with advanced retinitis pigmentosa...
2017: Ontario Health Technology Assessment Series
https://www.readbyqxmd.com/read/29184478/visual-prosthesis-interfacing-stimulating-electrodes-with-retinal-neurons-to-restore-vision
#2
REVIEW
Alejandro Barriga-Rivera, Lilach Bareket, Josef Goding, Ulises A Aregueta-Robles, Gregg J Suaning
The bypassing of degenerated photoreceptors using retinal neurostimulators is helping the blind to recover functional vision. Researchers are investigating new ways to improve visual percepts elicited by these means as the vision produced by these early devices remain rudimentary. However, several factors are hampering the progression of bionic technologies: the charge injection limits of metallic electrodes, the mechanical mismatch between excitable tissue and the stimulating elements, neural and electric crosstalk, the physical size of the implanted devices, and the inability to selectively activate different types of retinal neurons...
2017: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/29148158/long-term-anesthetic-protocol-in-rats-feasibility-in-electrophysiology-studies-in-visual-prosthesis
#3
Alejandro Barriga-Rivera, Veronica Tatarinoff, Nigel H Lovell, John W Morley, Gregg J Suaning
Electrical stimulation of excitable cells provides therapeutic benefits for a variety of medical conditions, including restoration of partial vision to those blinded via some types of retinal degeneration. To improve visual percepts elicited by the current technology, researchers are conducting acute electrophysiology experiments, mainly in cats. However, the rat can provide a model of a range of retinal diseases and possesses a sufficiently large eye to be used in this field. This article presents a long-term anesthetic protocol to enable electrophysiology experiments to further the development of visual prostheses...
November 17, 2017: Veterinary Ophthalmology
https://www.readbyqxmd.com/read/29076459/an-optimized-content-aware-image-retargeting-method-toward-expanding-the-perceived-visual-field-of-the-high-density-retinal-prosthesis-recipients
#4
Heng Li, Yajie Zeng, Zhuofan Lu, Xiaofei Cao, Xiaofan Su, Xiaohong Sui, Jing Wang, Xinyu Chai
Retinal prosthesis devices have shown great value in restoring some sight for individuals with profoundly impaired vision, but the visual acuity and visual field provided by prostheses greatly limit recipients' visual experience. In this paper, we employ computer vision approaches to seek to expand the perceptible visual field in patients implanted potentially with a high-density retinal prosthesis while maintaining visual acuity as much as possible. Approach. We propose an optimized content-aware image retargeting method, by introducing salient object detection based on color and intensity-difference contrast, aiming to remap important information of a scene into a small visual field and preserve their original scale as much as possible...
October 27, 2017: Journal of Neural Engineering
https://www.readbyqxmd.com/read/29060685/information-transmission-in-the-primary-visual-cortex-of-retinal-degenerated-rats
#5
Yi Wang, Ke Chen, Leanne L H Chan
To study the information transmission in the primary visual cortex (V1) of retinal degenerated (RD) models, wild type (WT) and RD rats were used in the experiments. The neural response in V1 was recorded extracellularly while the flicker with varied intensity levels was given as the visual stimulus. The mutual information (MI) and normalized mutual information (NMI) were determined for every isolated neuron, in order to quantify the amount and efficiency of information transmission in V1 of both control and experimental groups...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/29060083/testing-stimulus-protocols-in-retinal-prosthesis-patients
#6
A Gonzalez-Calle, J D Weiland
Retinal prostheses have demonstrated the capability to give blind patients the ability to detect motion and locate large objects. High-resolution retinal prostheses require precise activation of retinal cells to elicit a small visual phosphine that can serve as a building block to make patterns. Each electrode should activate only nearby cells, however patients receiving single electrode stimulation often report a streak-shaped phosphene rather than a focal spot. It is important to investigate stimulus paradigms that will provide better control over the spatial patterns of activation...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/29060067/a-comparative-study-of-light-and-electrically-evoked-response-of-retinal-ganglion-cells
#7
Satarupa Biswas, Debdeep Sikdar, Soumen Das, Manjunatha Mahadevappa
Understanding of the evoked neural discharges from retinal tissues is vital for designing of any retinal prosthesis. In this study, retinal ganglion cell activity to light and electrical stimulus is recorded using multielectrode arrays. For an effective epiretinal prosthetic device, the electrical stimulus through the prosthesis should be able to evoke responses similar to those of light response in normal condition. This pilot study was intended to design the experimental protocol for in-vitro retinal stimulation...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/29060066/flexible-microelectrode-array-for-retinal-prosthesis
#8
Bin Sun, Tengyue Li, Kai Xia, Qi Zeng, Tianzhun Wu, Mark S Humayun
fMEA (flexible microelectrode array) is one of the key implantable components for neural stimulating and recording. For its specific implanted environment, it should be designed and fabricated to meet following requirements such as biocompatibility, high-resolution, flexible and low impedance to ensure safety and long-term effective stimulation. Here we proposed a high resolution (1025-channel) fMEA for artificial retina. The adhesion between its substrate polyimide (PI) and metal was enhanced by using plasma treatment...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/29046507/subretinal-implantation-of-okayama-university-type-retinal-prosthesis-ourep-tm-in-canine-eyes-by-vitrectomy
#9
Toshihiko Matsuo, Tetsuya Uchida, Makoto Nitta, Koichiro Yamashita, Shigiko Takei, Daisuke Ido, Mamoru Tanaka, Masao Oguchi, Toshinori Furukawa
Okayama University-type retinal prosthesis (OUReP(TM)) is a photoelectric dye-coupled polyethylene film which generates electric potential in response to light and stimulates nearby neurons. This study aims to test surgical feasibility of subretinal implantation and functional durability of dye-coupled films in the subretinal space. The dye-coupled films were implanted subretinally by 25-gauge vitrectomy in the right eye of 11 normal beagle dogs: 2 dogs served for film removal after 5-month film implantation, 3 dogs for film removal after 3-month film implantation, 3 dogs for 3-month film implantation and pathological examination, and 3 dogs for sham surgery...
October 18, 2017: Journal of Veterinary Medical Science
https://www.readbyqxmd.com/read/28883759/the-advantage-of-topographic-prominence-adopted-filter-for-the-detection-of-short-latency-spikes-of-retinal-ganglion-cells
#10
Jungryul Ahn, Myoung-Hwan Choi, Kwangsoo Kim, Solomon S Senok, Dong-Il Dan Cho, Kyo-In Koo, Yongsook Goo
Electrical stimulation through retinal prosthesis elicits both short and long-latency retinal ganglion cell (RGC) spikes. Because the short-latency RGC spike is usually obscured by electrical stimulus artifact, it is very important to isolate spike from stimulus artifact. Previously, we showed that topographic prominence (TP) discriminator based algorithm is valid and useful for artifact subtraction. In this study, we compared the performance of forward backward (FB) filter only vs. TP-adopted FB filter for artifact subtraction...
September 2017: Korean Journal of Physiology & Pharmacology
https://www.readbyqxmd.com/read/28878616/interim-results-of-a-multicenter-trial-with-the-new-electronic-subretinal-implant-alpha-ams-in-15-patients-blind-from-inherited-retinal-degenerations
#11
Katarina Stingl, Ruth Schippert, Karl U Bartz-Schmidt, Dorothea Besch, Charles L Cottriall, Thomas L Edwards, Florian Gekeler, Udo Greppmaier, Katja Kiel, Assen Koitschev, Laura Kühlewein, Robert E MacLaren, James D Ramsden, Johann Roider, Albrecht Rothermel, Helmut Sachs, Greta S Schröder, Jan Tode, Nicole Troelenberg, Eberhart Zrenner
Purpose: We assessed the safety and efficacy of a technically advanced subretinal electronic implant, RETINA IMPLANT Alpha AMS, in end stage retinal degeneration in an interim analysis of two ongoing prospective clinical trials. The purpose of this article is to describe the interim functional results (efficacy). Methods: The subretinal visual prosthesis RETINA IMPLANT Alpha AMS (Retina Implant AG, Reutlingen, Germany) was implanted in 15 blind patients with hereditary retinal degenerations at four study sites with a follow-up period of 12 months (www...
2017: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/28793152/identification-of-characters-and-localization-of-images-using-direct-multiple-electrode-stimulation-with-a-suprachoroidal-retinal-prosthesis
#12
Mohit N Shivdasani, Nicholas C Sinclair, Lisa N Gillespie, Matthew A Petoe, Samuel A Titchener, James B Fallon, Thushara Perera, Darien Pardinas-Diaz, Nick M Barnes, Peter J Blamey
Purpose: Retinal prostheses provide vision to blind patients by eliciting phosphenes through electrical stimulation. This study explored whether character identification and image localization could be achieved through direct multiple-electrode stimulation with a suprachoroidal retinal prosthesis. Methods: Two of three retinitis pigmentosa patients implanted with a suprachoroidal electrode array were tested on three psychophysical tasks. Electrode patterns were stimulated to elicit perception of simple characters, following which percept localization was tested using either static or dynamic images...
August 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/28744551/neural-responses-to-multielectrode-stimulation-of-healthy-and-degenerate-retina
#13
Kerry J Halupka, Carla J Abbott, Yan T Wong, Shaun L Cloherty, David B Grayden, Anthony N Burkitt, Evgeni N Sergeev, Chi D Luu, Alice Brandli, Penelope J Allen, Hamish Meffin, Mohit N Shivdasani
Purpose: Simultaneous stimulation of multiple retinal electrodes in normally sighted animals shows promise in improving the resolution of retinal prostheses. However, the effects of simultaneous stimulation on degenerate retinae remain unknown. Therefore, we investigated the characteristics of cortical responses to multielectrode stimulation of the degenerate retina. Methods: Four adult cats were bilaterally implanted with retinal electrode arrays in the suprachoroidal space after unilateral adenosine triphosphate (ATP)-induced retinal photoreceptor degeneration...
July 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/28742044/multipolar-field-shaping-in-a-suprachoroidal-visual-prosthesis
#14
Calvin D Eiber, Socrates Dokos, Nigel H Lovell, Gregg J Suaning
Visual prostheses are now an available mobility aid for patients blinded by degenerative retinal diseases. However, the spatial resolution of existing devices is still insufficient to deliver normal levels of mobility vision without stimulation strategies which enable existing devices to deliver several different percepts per stimulation site. A stimulation strategy in which field shaping is achieved by incorporating multipolar (bipolar and tripolar) stimulation could convey additional information to a user of a visual prosthesis, as compared to monopolar stimulation, is investigated...
July 24, 2017: IEEE Transactions on Neural Systems and Rehabilitation Engineering
https://www.readbyqxmd.com/read/28660276/determining-the-contribution-of-retinotopic-discrimination-to-localization-performance-with-a-suprachoroidal-retinal-prosthesis
#15
Matthew A Petoe, Chris D McCarthy, Mohit N Shivdasani, Nicholas C Sinclair, Adele F Scott, Lauren N Ayton, Nick M Barnes, Robyn H Guymer, Penelope J Allen, Peter J Blamey
Purpose: With a retinal prosthesis connected to a head-mounted camera, subjects can perform low vision tasks using a combination of electrode discrimination and head-directed localization. The objective of the present study was to investigate the contribution of retinotopic electrode discrimination (perception corresponding to the arrangement of the implanted electrodes with respect to their position beneath the retina) to visual performance for three recipients of a 24-channel suprachoroidal retinal implant...
June 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/28612755/learning-to-see-again-biological-constraints-on-cortical-plasticity-and-the-implications-for-sight-restoration-technologies
#16
Michael Beyeler, Ariel Rokem, Geoffrey M Boynton, Ione Fine
The 'bionic eye'-so long a dream of the future-is finally becoming a reality with retinal prostheses available to patients in both the US and Europe. However, clinical experience with these implants has made it apparent that the visual information provided by these devices differs substantially from normal sight. Consequently, the ability of patients to learn to make use of this abnormal retinal input plays a critical role in whether or not some functional vision is successfully regained. The goal of the present review is to summarize the vast basic science literature on developmental and adult cortical plasticity with an emphasis on how this literature might relate to the field of prosthetic vision...
October 2017: Journal of Neural Engineering
https://www.readbyqxmd.com/read/28532361/electrical-stimulation-of-the-retina-to-produce-artificial-vision
#17
James D Weiland, Steven T Walston, Mark S Humayun
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...
October 14, 2016: Annual Review of Vision Science
https://www.readbyqxmd.com/read/28530688/a-second-shot-at-sight-using-a-fully-organic-retinal-prosthesis
#18
Dustin M Graham
No abstract text is available yet for this article.
May 22, 2017: Lab Animal
https://www.readbyqxmd.com/read/28530256/can-the-onset-of-orbital-cancer-be-the-result-of-a-prosthetic-eye
#19
A Croce, V Mastronardi, M Laus, E Festa Kotelnikova
Orbital exenteration is a disfiguring procedure performed for unresponsive orbital infections and control of recurrent benign tumours and malignancies arising from the eyelids (basal cell carcinoma, squamous cell carcinoma, conjunctival malignant melanoma), lachrymal glands (adenoid cystic carcinoma) or surrounding sinuses. In extremely rare cases the use of a prosthetic eye after enucleation can lead to anophthalmic socket tumours. We report the case of a 54-year-old man who had left eye enucleation due to recurring events of retinal detachment and who developed an invasive fast growing epidermoid carcinoma 30 years later...
May 22, 2017: Acta Otorhinolaryngologica Italica
https://www.readbyqxmd.com/read/28426627/high-visual-acuity-retinal-prosthesis-understanding-limitations-and-advancements-toward-functional-prosthetic-vision
#20
Samir Damle, Yu-Hwa Lo, William R Freeman
No abstract text is available yet for this article.
August 2017: Retina
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