keyword
MENU ▼
Read by QxMD icon Read
search

retinal prosthesis

keyword
https://www.readbyqxmd.com/read/29849997/extraspectral-imaging-for-improving-the-perceived-information-presented-in-retinal-prosthesis
#1
Walid Al-Atabany, Musa Al Yaman, Patrick Degenaar
Retinal prosthesis is steadily improving as a clinical treatment for blindness caused by retinitis pigmentosa. However, despite the continued exciting progress, the level of visual return is still very poor. It is also unlikely that those utilising these devices will stop being legally blind in the near future. Therefore, it is important to develop methods to maximise the transfer of useful information extracted from the visual scene. Such an approach can be achieved by digitally suppressing less important visual features and textures within the scene...
2018: Journal of Healthcare Engineering
https://www.readbyqxmd.com/read/29797053/correction-to-light-localization-with-low-contrast-targets-in-a-patient-implanted-with-a-suprachoroidal-transretinal-stimulation-retinal-prosthesis
#2
Takao Endo, Takashi Fujikado, Masakazu Hirota, Hiroyuki Kanda, Takeshi Morimoto, Kohji Nishida
The original publication of this paper contain an error because of an incorrect captured corresponding author.
May 25, 2018: Graefe's Archive for Clinical and Experimental Ophthalmology
https://www.readbyqxmd.com/read/29755278/orbital-tumor-associated-with-a-microphthalmic-eye-and-colobomatous-cleft-pilocytic-astrocytoma-glioma-or-massive-retinal-gliosis
#3
Rita Van Ginderdeuren, Rafael Sciot, Ilse Mombaerts
A 11-year-old boy with congenital microphthalmos of the right eye presented with gradual protrusion of his ocular prosthesis. MRI showed an orbital mass adjacent to the microphthalmic eye. After removal of the eye and the orbital soft tissue mass a gliotic mass, resembling a pilocytic astrocytoma WHO grade 1 (glioma) was diagnosed. Through a colobomatous cleft in the eye the tumour spread in the orbit. There were no clinical signs of neurofibromatosis 1. This case showed a very rare association between a microphthalmic and colobomatous eye and pilocytic astrocytoma, grade 1...
January 2018: Saudi Journal of Ophthalmology: Official Journal of the Saudi Ophthalmological Society
https://www.readbyqxmd.com/read/29737971/differential-electrical-responses-in-retinal-ganglion-cell-subtypes-effects-of-synaptic-blockade-and-stimulating-electrode-location
#4
Chih Yu Yang, David Tsai, Tianruo Guo, Socrates Dokos, Gregg J Suaning, John W Morley, Nigel H Lovell
OBJECTIVE: Visual prostheses have shown promising results in restoring visual perception to blind patients. The ability to differentially activate retinal ganglion cell (RGC) subtypes could further improve the efficacy of these medical devices. APPROACH: Using whole-cell patch clamp, we investigated membrane potential differences between ON and OFF RGCs in the mouse retina when their synaptic inputs were blocked by synaptic blockers, and examined the differences in stimulation thresholds under such conditions...
May 8, 2018: Journal of Neural Engineering
https://www.readbyqxmd.com/read/29721974/current-pharmacological-concepts-in-the-treatment-of-the-retinitis-pigmentosa
#5
Xiu-Feng Huang
Retinitis pigmentosa (RP) encompasses a heterogeneous group of inherited retinal disorders characterized by progressive photoreceptor and/or retinal pigment epithelial (RPE) degenerations with a prevalence approximately 1 in 4000 in the general population. Over 70 causative genes have been defined in RP families, and a number of animal models have been identified so far. However there have been no widely recognized treatments able to recover or reverse the degenerating retina, to prevent the disease deterioration, ultimately to restore the remaining vision...
2018: Advances in Experimental Medicine and Biology
https://www.readbyqxmd.com/read/29679170/light-localization-with-low-contrast-targets-in-a-patient-implanted-with-a-suprachoroidal-transretinal-stimulation-retinal-prosthesis
#6
Takao Endo, Takashi Fujikado, Masakazu Hirota, Hiroyuki Kanda, Takeshi Morimoto, Kohji Nishida
PURPOSE: To evaluate the improvement in targeted reaching movements toward targets of various contrasts in a patient implanted with a suprachoroidal-transretinal stimulation (STS) retinal prosthesis. METHODS: An STS retinal prosthesis was implanted in the right eye of a 42-year-old man with advanced Stargardt disease (visual acuity: right eye, light perception; left eye, hand motion). In localization tests during the 1-year follow-up period, the patient attempted to touch the center of a white square target (visual angle, 10°; contrast, 96, 85, or 74%) displayed at a random position on a monitor...
April 20, 2018: Graefe's Archive for Clinical and Experimental Ophthalmology
https://www.readbyqxmd.com/read/29625464/safety-studies-for-a-44-channel-suprachoroidal-retinal-prosthesis-a-chronic-passive-study
#7
Carla J Abbott, David A X Nayagam, Chi D Luu, Stephanie B Epp, Richard A Williams, Cesar M Salinas-LaRosa, Joel Villalobos, Ceara McGowan, Mohit N Shivdasani, Owen Burns, Jason Leavens, Jonathan Yeoh, Alice A Brandli, Patrick C Thien, Jenny Zhou, Helen Feng, Chris E Williams, Robert K Shepherd, Penelope J Allen
Purpose: Following successful clinical outcomes of the prototype suprachoroidal retinal prosthesis, Bionic Vision Australia has developed an upgraded 44-channel suprachoroidal retinal prosthesis to provide a wider field of view and more phosphenes. The aim was to evaluate the preclinical passive safety characteristics of the upgraded electrode array. Methods: Ten normal-sighted felines were unilaterally implanted with an array containing platinum electrodes (44 stimulating and 2 returns) on a silicone carrier near the area centralis...
March 1, 2018: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/29564412/implantation-of-multiple-suprachoroidal-electrode-arrays-in-rabbits
#8
Walid Abdallah, Wen Li, James Weiland, Mark Humayun, Hossein Ameri
Purpose: Epiretinal and subretinal prosthesis have been shown to be a valid way to provide some vision to patients with advanced outer retinal degeneration and profound vision loss. However, the field of vision for these patients is markedly limited by the area occupied by the electrode array. In this study, we aimed to evaluate the feasibility of implantation of multiple suprachoroidal electrode arrays in a single eye in order to increase the field of vision in patients implanted with retinal prosthesis...
March 2018: Journal of Current Ophthalmology
https://www.readbyqxmd.com/read/29520006/design-and-validation-of-a-foldable-and-photovoltaic-wide-field-epiretinal-prosthesis
#9
Laura Ferlauto, Marta Jole Ildelfonsa Airaghi Leccardi, Naïg Aurelia Ludmilla Chenais, Samuel Charles Antoine Gilliéron, Paola Vagni, Michele Bevilacqua, Thomas J Wolfensberger, Kevin Sivula, Diego Ghezzi
Retinal prostheses have been developed to fight blindness in people affected by outer retinal layer dystrophies. To date, few hundred patients have received a retinal implant. Inspired by intraocular lenses, we have designed a foldable and photovoltaic wide-field epiretinal prosthesis (named POLYRETINA) capable of stimulating wireless retinal ganglion cells. Here we show that within a visual angle of 46.3 degrees, POLYRETINA embeds 2215 stimulating pixels, of which 967 are in the central area of 5 mm, it is foldable to allow implantation through a small scleral incision, and it has a hemispherical shape to match the curvature of the eye...
March 8, 2018: Nature Communications
https://www.readbyqxmd.com/read/29513646/direct-measurement-of-bipolar-cell-responses-to-electrical-stimulation-in-wholemount-mouse-retina
#10
Steven T Walston, Robert H Chow, James D Weiland
OBJECTIVE: This in vitro investigation examines the response of retinal bipolar cells to extracellular electrical stimulation. APPROACH: In vitro investigations characterizing the response of retinal neurons to electrical stimulation have primarily focused on retinal ganglion cells because they are the output neurons of the retina and their superficial position in the retina makes them readily accessible to in vitro recording techniques. Thus, the majority of information regarding the response of inner retinal neurons has been inferred from ganglion cell activity...
March 7, 2018: Journal of Neural Engineering
https://www.readbyqxmd.com/read/29511183/nanowire-arrays-restore-vision-in-blind-mice
#11
Jing Tang, Nan Qin, Yan Chong, Yupu Diao, Yiliguma, Zhexuan Wang, Tian Xue, Min Jiang, Jiayi Zhang, Gengfeng Zheng
The restoration of light response with complex spatiotemporal features in retinal degenerative diseases towards retinal prosthesis has proven to be a considerable challenge over the past decades. Herein, inspired by the structure and function of photoreceptors in retinas, we develop artificial photoreceptors based on gold nanoparticle-decorated titania nanowire arrays, for restoration of visual responses in the blind mice with degenerated photoreceptors. Green, blue and near UV light responses in the retinal ganglion cells (RGCs) are restored with a spatial resolution better than 100 µm...
March 6, 2018: Nature Communications
https://www.readbyqxmd.com/read/29494655/minimizing-activation-of-overlying-axons-with-epiretinal-stimulation-the-role-of-fiber-orientation-and-electrode-configuration
#12
Timothy B Esler, Robert R Kerr, Bahman Tahayori, David B Grayden, Hamish Meffin, Anthony N Burkitt
Currently, a challenge in electrical stimulation of the retina with a visual prosthesis (bionic eye) is to excite only the cells lying directly under the electrode in the ganglion cell layer, while avoiding excitation of axon bundles that pass over the surface of the retina in the nerve fiber layer. Stimulation of overlying axons results in irregular visual percepts, limiting perceptual efficacy. This research explores how differences in fiber orientation between the nerve fiber layer and ganglion cell layer leads to differences in the electrical activation of the axon initial segment and axons of passage...
2018: PloS One
https://www.readbyqxmd.com/read/29453455/temporal-structure-in-spiking-patterns-of-ganglion-cells-defines-perceptual-thresholds-in-rodents-with-subretinal-prosthesis
#13
Elton Ho, Henri Lorach, Georges Goetz, Florian Laszlo, Xin Lei, Theodore Kamins, Jean-Charles Mariani, Alexander Sher, Daniel Palanker
Subretinal prostheses are designed to restore sight in patients blinded by retinal degeneration using electrical stimulation of the inner retinal neurons. To relate retinal output to perception, we studied behavioral thresholds in blind rats with photovoltaic subretinal prostheses stimulated by full-field pulsed illumination at 20 Hz, and measured retinal ganglion cell (RGC) responses to similar stimuli ex-vivo. Behaviorally, rats exhibited startling response to changes in brightness, with an average contrast threshold of 12%, which could not be explained by changes in the average RGC spiking rate...
February 16, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29443363/sheets-glide-assisted-intraocular-placement-of-the-argus-ii-retinal-prosthesis
#14
Avni P Finn, Lejla Vajzovic
BACKGROUND AND OBJECTIVE: As an increasing number of vitreoretinal surgeons are implanting retinal prosthesis devices, the need to share surgical techniques to ease implantation in challenging scenarios grows. The authors share a technique to aide in overcoming a challenge associated with uveal prolapse in a patient undergoing Argus II retinal prosthesis (Second Sight Medical Products, Sylmar, CA) implantation. PATIENTS AND METHODS: A surgical technique is discussed and demonstrated using a video (Video available at www...
February 1, 2018: Ophthalmic Surgery, Lasers & Imaging Retina
https://www.readbyqxmd.com/read/29438279/recent-updates-on-treatment-of-ocular-microbial-infections-by-stem-cell-therapy-a-review
#15
REVIEW
Seoh Wei Teh, Pooi Ling Mok, Munirah Abd Rashid, Mae-Lynn Catherine Bastion, Normala Ibrahim, Akon Higuchi, Kadarkarai Murugan, Rajan Mariappan, Suresh Kumar Subbiah
Ocular microbial infection has emerged as a major public health crisis during the past two decades. A variety of causative agents can cause ocular microbial infections; which are characterized by persistent and destructive inflammation of the ocular tissue; progressive visual disturbance; and may result in loss of visual function in patients if early and effective treatments are not received. The conventional therapeutic approaches to treat vision impairment and blindness resulting from microbial infections involve antimicrobial therapy to eliminate the offending pathogens or in severe cases; by surgical methods and retinal prosthesis replacing of the infected area...
February 13, 2018: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/29426448/the-toronto-experience-with-the-argus-ii-retinal-prosthesis-new-technology-new-hope-for-patients
#16
Robert G Devenyi, Joshua Manusow, Beatrice E Patino, Mohamed Mongy, Michelle Markowitz, Samuel N Markowitz
Surgical restoration of vision with retinal prostheses is a new and developing technology currently available in a select group of countries, Canada among them. The Argus II retinal prosthesis is the first commercially available device for restoration of vision in patients with Retinitis Pigmentosa or with similar retinal pathology who still have minimal residual native vision. The surgery is complex and requires training however it is within the abilities of any experienced retina surgeon. Surgical experience builds up with each case and in our patients length of surgery constantly went down...
February 2018: Canadian Journal of Ophthalmology. Journal Canadien D'ophtalmologie
https://www.readbyqxmd.com/read/29426432/rehabilitation-of-lost-functional-vision-with-the-argus-ii-retinal-prosthesis
#17
Michelle Markowitz, Mark Rankin, Mohamed Mongy, Beatrice E Patino, Joshua Manusow, Robert G Devenyi, Samuel N Markowitz
The Argus II retinal prosthesis is the first commercially available device for restoration of vision in patients with Retinitis Pigmentosa or with similar retinal pathology who still have minimal residual native vision. The technology is able to restore vision with production of artificial visual percepts which usually are given adequate useful interpretation by the visual system in most implanted patients. The technology usually produces visual perception at the level of shape identification or better in some cases enabling in many less dependence on vision substitution devices and skills...
February 2018: Canadian Journal of Ophthalmology. Journal Canadien D'ophtalmologie
https://www.readbyqxmd.com/read/29392324/eye-movement-control-in-the-argus-ii-retinal-prosthesis-enables-reduced-head-movement-and-better-localization-precision
#18
Avi Caspi, Arup Roy, Varalakshmi Wuyyuru, Paul E Rosendall, Jason W Harper, Kapil D Katyal, Michael P Barry, Gislin Dagnelie, Robert J Greenberg
Purpose: Visual scanning by sighted individuals is done using eye and head movements. In contrast, scanning using the Argus II is solely done by head movement, since eye movements can introduce localization errors. Here, we tested if a scanning mode utilizing eye movements increases visual stability and reduces head movements in Argus II users. Methods: Eye positions were measured in real-time and were used to shift the region of interest (ROI) that is sent to the implant within the wide field of view (FOV) of the scene camera...
February 1, 2018: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/29388561/optimization-of-pillar-electrodes-in-subretinal-prosthesis-for-enhanced-proximity-to-target-neurons
#19
Thomas Flores, Xin Lei, Tiffany Huang, Henri Lorach, Roopa Dalal, Ludwig Galambos, Theodore Kamins, Keith Mathieson, Daniel Palanker
OBJECTIVE: High-resolution prosthetic vision requires dense stimulating arrays with small electrodes. However, such miniaturization reduces electrode capacitance and penetration of electric field into tissue. We evaluate potential solutions to these problems with subretinal implants based on utilization of pillar electrodes. APPROACH: To study integration of three-dimensional (3D) implants with retinal tissue, we fabricated arrays with varying pillar diameter, pitch, and height, and implanted beneath the degenerate retina in rats (Royal College of Surgeons, RCS)...
February 1, 2018: Journal of Neural Engineering
https://www.readbyqxmd.com/read/29311491/visual-evoked-potential-in-rabbits-eyes-with-subretinal-implantation-by-vitrectomy-of-okayama-university-type-retinal-prosthesis-ourep-tm
#20
Toshihiko Matsuo, Tetsuya Uchida, Koichiro Yamashita, Shigiko Takei, Daisuke Ido, Mamoru Tanaka, Masao Oguchi, Toshinori Furukawa
Okayama University-type retinal prosthesis (OURePTM ) 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 for subretinal film implantation and to examine functional durability of films in subretinal space. Dye-coupled films were implanted subretinally by vitrectomy in the right eye of normal white rabbits: 8 rabbits for 1 month and 8 rabbits for 6 months. The implanted films were removed by vitrectomy in 4 of these 8 rabbits in 1-month or 6-month implantation group...
February 9, 2018: Journal of Veterinary Medical Science
keyword
keyword
51544
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"