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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/28248989/efficacy-of-two-different-thiol-modified-crosslinked-hyaluronate-formulations-as-vitreous-replacement-compared-to-silicone-oil-in-a-model-of-retinal-detachment
#2
Sven Schnichels, Nele Schneider, Christine Hohenadl, José Hurst, Andreas Schatz, Kai Januschowski, Martin S Spitzer
The efficacy of two novel artificial vitreous body substitutes (VBS) consisting of highly biocompatible thiolated cross-linked hyaluronic acid (HA)-based hydrogels in comparison to silicone oil in a model of retinal detachment was investigated. Pars plana vitrectomy (23G) was performed in the right eye of 24 pigmented rabbits. Retinal detachment of two quadrants was induced by creating a small retinotomy near the vascular arcade and injecting balanced salt solution (BSS) subretinally. The retina was reattached by injecting air, which was followed by increasing the infusion pressure, and the retinal tear was treated by endolaser photocoagulation...
2017: PloS One
https://www.readbyqxmd.com/read/28198154/daily-and-seasonal-expression-profile-of-serum-melatonin-and-its-biosynthesizing-enzyme-genes-tph1-aanat1-aanat2-and-hiomt-in-pineal-organ-and-retina-a-study-under-natural-environmental-conditions-in-a-tropical-carp-catla-catla
#3
Chongtham Rajiv, Haobijam Sanjita Devi, Gopinath Mondal, Sijagurumayum Dharmajyoti Devi, Zeeshan Ahmad Khan, Thangal Yumnamcha, Rupjyoti Bharali, Asamanja Chattoraj
The tropical carp Catla catla is gaining importance for the studies of the impact of environmental changes on aquatic animals due to its surface dwelling habitat. To date, no information is available on the transcriptional profile of melatonin biosynthesizing enzyme genes in any tropical carp under either natural or artificial photothermal conditions in pineal and retina. The present study is an attempt to demonstrate the temporal pattern of expression of melatonin biosynthesizing enzyme genes, tryptophan hydroxylase 1 (tph1), arylalkylamine N-acetyltransferase (aanat1 and aanat2), and hydroxyindole-O-methyltransferase (hiomt) collectively and simultaneously in pineal organ and retina in tropical fish, C...
December 2016: Journal of Experimental Zoology. Part A, Ecological Genetics and Physiology
https://www.readbyqxmd.com/read/28179882/connecting-artificial-brains-to-robots-in-a-comprehensive-simulation-framework-the-neurorobotics-platform
#4
Egidio Falotico, Lorenzo Vannucci, Alessandro Ambrosano, Ugo Albanese, Stefan Ulbrich, Juan Camilo Vasquez Tieck, Georg Hinkel, Jacques Kaiser, Igor Peric, Oliver Denninger, Nino Cauli, Murat Kirtay, Arne Roennau, Gudrun Klinker, Axel Von Arnim, Luc Guyot, Daniel Peppicelli, Pablo Martínez-Cañada, Eduardo Ros, Patrick Maier, Sandro Weber, Manuel Huber, David Plecher, Florian Röhrbein, Stefan Deser, Alina Roitberg, Patrick van der Smagt, Rüdiger Dillman, Paul Levi, Cecilia Laschi, Alois C Knoll, Marc-Oliver Gewaltig
Combined efforts in the fields of neuroscience, computer science, and biology allowed to design biologically realistic models of the brain based on spiking neural networks. For a proper validation of these models, an embodiment in a dynamic and rich sensory environment, where the model is exposed to a realistic sensory-motor task, is needed. Due to the complexity of these brain models that, at the current stage, cannot deal with real-time constraints, it is not possible to embed them into a real-world task...
2017: Frontiers in Neurorobotics
https://www.readbyqxmd.com/read/28114567/retinotopic-to-spatiotopic-mapping-in-blind-patients-implanted-with-the-argus-ii-retinal-prosthesis
#5
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/28107513/the-zebrafish-anillin-egfp-reporter-marks-late-dividing-retinal-precursors-and-stem-cells-entering-neuronal-lineages
#6
Meret Cepero Malo, Anne-Laure Duchemin, Luca Guglielmi, Eva Patzel, Saadettin Sel, Gerd U Auffarth, Matthias Carl, Lucia Poggi
Monitoring cycling behaviours of stem and somatic cells in the living animal is a powerful tool to better understand tissue development and homeostasis. The tg(anillin:anillin-eGFP) transgenic line carries the full-length zebrafish F-actin binding protein Anillin fused to eGFP from a bacterial artificial chromosome (BAC) containing Anillin cis-regulatory sequences. Here we report the suitability of the Anillin-eGFP reporter as a direct indicator of cycling cells in the late embryonic and post-embryonic retina...
2017: PloS One
https://www.readbyqxmd.com/read/28060395/design-and-validation-of-a-training-simulator-for-laser-capsulotomy-peripheral-iridotomy-and-retinopexy
#7
Sarah M Simpson, Kelly D Schweitzer, Davin E Johnson
BACKGROUND AND OBJECTIVES: Ophthalmology trainees commonly learn laser procedures on live patients. A simulator for learning peripheral iridotomy (PI), posterior capsulotomy, and retinopexy may improve patient outcomes. MATERIALS AND METHODS: A model eye with artificial tissues was designed. The tissues reacted to laser similarly to human tissues. Inexperienced (n = 6; first- to third-year residents) and experienced (n = 7; fourth- to fifth-year residents and staff) ophthalmic personal were compared on performance of the above laser procedures...
January 1, 2017: Ophthalmic Surgery, Lasers & Imaging Retina
https://www.readbyqxmd.com/read/27958724/engineering-an-artificial-flavoprotein-magnetosensor
#8
Chris Bialas, Lauren E Jarocha, Kevin B Henbest, Tilo M Zollitsch, Goutham Kodali, Christiane R Timmel, Stuart R Mackenzie, P Leslie Dutton, Christopher C Moser, P J Hore
Migratory birds use the Earth's magnetic field as a source of navigational information. This light-dependent magnetic compass is thought to be mediated by cryptochrome proteins in the retina. Upon light activation, electron transfer between the flavin adenine dinucleotide cofactor and tryptophan residues leads to the formation of a spin-correlated radical pair, whose subsequent fate is sensitive to external magnetic fields. To learn more about the functional requirements of this complex chemical compass, we have created a family of simplified, adaptable proteins-maquettes-that contain a single tryptophan residue at different distances from a covalently bound flavin...
December 28, 2016: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/27942525/are-long-stimulus-pulse-durations-the-answer-to-improving-spatial-resolution-in-retinal-prostheses
#9
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/27936751/effective-retinal-penetration-of-lipophilic-and-lipid-conjugated-hydrophilic-agents-delivered-by-engineered-liposomes
#10
Junsung Lee, Unbyeol Goh, Hyoung-Jin Lee, Jiyoung Kim, Moonkyoung Jeong, Ji-Ho Park
Efficient delivery of drugs to the retina is critical but difficult to achieve with current methods. There have been a number of attempts to use intravitreal injection of liposomes, artificial vesicles composed of a phospholipid bilayer, to overcome the limitations of conventional intravitreal injection (short retention time, toxicity, poor penetration, etc.). Here, we report an optimal liposomal formulation that can diffuse through the vitreous humor, deliver the incorporated agents to all retinal layers effectively, and maintain them for a relatively long time...
December 27, 2016: Molecular Pharmaceutics
https://www.readbyqxmd.com/read/27919674/neural-adaptation-to-peripheral-blur-in-myopes-and-emmetropes
#11
Atanu Ghosh, Len Zheleznyak, Antoine Barbot, HaeWon Jung, Geunyoung Yoon
In the presence of optical blur at the fovea, blur adaptation can improve visual acuity (VA) and perceived image quality over time. However, little is known regarding blur adaptation in the peripheral retina. Here, we examined neural adaptation to myopic defocus at the fovea and parafovea (10° temporal retina) in both emmetropes and myopes. During a 60-min adaptation period, subjects (3 emmetropes and 3 myopes) watched movies with +2 diopters of defocus blur through a 6-mm artificial pupil in two separate, counter-balanced sessions for each retinal location...
March 2017: Vision Research
https://www.readbyqxmd.com/read/27836334/enhanced-neural-function-in-highly-aberrated-eyes-following-perceptual-learning-with-adaptive-optics
#12
Ramkumar Sabesan, Antoine Barbot, Geunyoung Yoon
Highly aberrated keratoconic (KC) eyes do not elicit the expected visual advantage from customized optical corrections. This is attributed to the neural insensitivity arising from chronic visual experience with poor retinal image quality, dominated by low spatial frequencies. The goal of this study was to investigate if targeted perceptual learning with adaptive optics (AO) can stimulate neural plasticity in these highly aberrated eyes. The worse eye of 2 KC subjects was trained in a contrast threshold test under AO correction...
March 2017: Vision Research
https://www.readbyqxmd.com/read/27782261/controllable-stationary-photocurrents-generated-from-a-bacteriorhodopsin-upconversion-nanoparticle-based-bionanosystem-under-nir-illumination
#13
Zhisong Lu, Jing Wang, Rui Li, Yan Qiao, Mengyao Zhou, Chang Ming Li
In the past few decades, tremendous effort has been dedicated to develop bacteriorhodopsin (bR)-based photo-electronic devices for generating a stationary photocurrent and further for use as a component of artificial retinas in constant illumination sensing. However, an IR-triggered stationary photocurrent with controllable amplitudes has never been realized to date. Herein, NaYF4:Yb,Er and NaYF4:Yb,Tm upconversion nanoparticles (UCNPs) with green and blue emissions, respectively, were synthesized and further incorporated with bR to build a bionanosystem...
October 26, 2016: Nanoscale
https://www.readbyqxmd.com/read/27751886/photoreceptor-spectral-sensitivity-of-the-compound-eyes-of-black-soldier-fly-hermetia-illucens-informing-the-design-of-led-based-illumination-to-enhance-indoor-reproduction
#14
D G A B Oonincx, N Volk, J J E Diehl, J J A van Loon, G Belušič
Mating in the black soldier fly (BSF) is a visually mediated behaviour that under natural conditions occurs in full sunlight. Artificial light conditions promoting mating by BSF were designed based on the spectral characteristics of the compound eye retina. Electrophysiological measurements revealed that BSF ommatidia contained UV-, blue- and green-sensitive photoreceptor cells, allowing trichromatic vision. An illumination system for indoor breeding based on UV, blue and green LEDs was designed and its efficiency was compared with illumination by fluorescent tubes which have been successfully used to sustain a BSF colony for five years...
December 2016: Journal of Insect Physiology
https://www.readbyqxmd.com/read/27731346/head-mounted-dmd-based-projection-system-for-natural-and-prosthetic-visual-stimulation-in-freely-moving-rats
#15
Tamar Arens-Arad, Nairouz Farah, Shai Ben-Yaish, Alex Zlotnik, Zeev Zalevsky, Yossi Mandel
Novel technologies are constantly under development for vision restoration in blind patients. Many of these emerging technologies are based on the projection of high intensity light patterns at specific wavelengths, raising the need for the development of specialized projection systems. Here we present and characterize a novel projection system that meets the requirements for artificial retinal stimulation in rats and enables the recording of cortical responses. The system is based on a customized miniature Digital Mirror Device (DMD) for pattern projection, in both visible (525 nm) and NIR (915 nm) wavelengths, and a lens periscope for relaying the pattern directly onto the animal's retina...
October 12, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27698742/blood-filled-cerebrospinal-fluid-enhanced-pericyte-microvasculature-contraction-in-rat-retina-a-novel-in-vitro-study-of-subarachnoid-hemorrhage
#16
Zhi Liu, Qiang Li, Gaoyu Cui, Gang Zhu, Weihua Tang, Hengli Zhao, John H Zhang, Yujie Chen, Hua Feng
Previously, it was widely accepted that the delayed ischemic injury and poor clinical outcome following subarachnoid hemorrhage (SAH) was caused by cerebral vasospasm. This classical theory was challenged by a clazosentan clinical trial, which failed to improve patient outcome, despite reversing angiographic vasospasm. One possible explanation for the results of this trial is the changes in microcirculation following SAH, particularly in pericytes, which are the primary cell type controlling microcirculation in the brain parenchyma...
October 2016: Experimental and Therapeutic Medicine
https://www.readbyqxmd.com/read/27479580/-stem-cells-for-retina-replacement
#17
I P Seitz, K Achberger, S Liebau, M D Fischer
In ophthalmology, regenerative medicine is rapidly becoming a reality. Cell based treatment strategies in end stage retinal degeneration may be of therapeutic value, whatever the mechanism of disease mechanism. However, while corneal transplantation is commonly performed with excellent results, many obstacles must be overcome before retinal transplants can become clinically useful. The major problems are the production of appropriate transplants and functional integration in situ. New technologies allow the production of autologous transplants by inducing pluripotency in adult somatic cells...
December 2016: Klinische Monatsblätter Für Augenheilkunde
https://www.readbyqxmd.com/read/27463221/ocular-penetration-and-pharmacokinetics-of-ripasudil-following-topical-administration-to-rabbits
#18
Tomoyuki Isobe, Taku Kasai, Hiroyuki Kawai
PURPOSE: We evaluated the ocular pharmacokinetics of ripasudil (K-115), a selective Rho-associated coiled-coil containing protein kinase (ROCK) inhibitor, following topical administration to rabbits. METHODS: We determined the ocular distribution of [(14)C]ripasudil by whole-head autoradiography and the radioactivity of each ocular tissue after single and multiple instillation of [(14)C]ripasudil to pigmented rabbits. We also measured the aqueous humor concentrations after concomitant instillation of ripasudil and a combination agent (0...
September 2016: Journal of Ocular Pharmacology and Therapeutics
https://www.readbyqxmd.com/read/27354187/automatic-tuning-of-a-retina-model-for-a-cortical-visual-neuroprosthesis-using-a-multi-objective-optimization-genetic-algorithm
#19
Antonio Martínez-Álvarez, Rubén Crespo-Cano, Ariadna Díaz-Tahoces, Sergio Cuenca-Asensi, José Manuel Ferrández Vicente, Eduardo Fernández
The retina is a very complex neural structure, which contains many different types of neurons interconnected with great precision, enabling sophisticated conditioning and coding of the visual information before it is passed via the optic nerve to higher visual centers. The encoding of visual information is one of the basic questions in visual and computational neuroscience and is also of seminal importance in the field of visual prostheses. In this framework, it is essential to have artificial retina systems to be able to function in a way as similar as possible to the biological retinas...
November 2016: International Journal of Neural Systems
https://www.readbyqxmd.com/read/27284072/optic-flow-stabilizes-flight-in-ruby-throated-hummingbirds
#20
Ivo G Ros, Andrew A Biewener
Flying birds rely on visual cues for retinal image stabilization by negating rotation-induced optic flow, the motion of the visual panorama across the retina, through corrective eye and head movements. In combination with vestibular and proprioceptive feedback, birds may also use visual cues to stabilize their body during flight. Here, we test whether artificially induced wide-field motion generated through projected visual patterns elicits maneuvers in body orientation and flight position, in addition to stabilizing vision...
August 15, 2016: Journal of Experimental Biology
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