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https://www.readbyqxmd.com/read/28230526/sensitivity-to-image-recurrence-across-eye-movement-like-image-transitions-through-local-serial-inhibition-in-the-retina
#1
Vidhyasankar Krishnamoorthy, Michael Weick, Tim Gollisch
Standard models of stimulus encoding in the retina postulate that image presentations activate neurons according to the increase of preferred contrast inside the receptive field. During natural vision, however, images do not arrive in isolation, but follow each other rapidly, separated by sudden gaze shifts. We here report that, contrary to standard models, specific ganglion cells in mouse retina are suppressed after a rapid image transition by changes in visual patterns across the transition, but respond with a distinct spike burst when the same pattern reappears...
February 23, 2017: ELife
https://www.readbyqxmd.com/read/28229400/trans-synaptic-retrograde-degeneration-in-the-human-visual-system-slow-silent-and-real
#2
REVIEW
Marc Dinkin
Degeneration of neuron and axons following injury to cells with which they synapse is termed trans-synaptic degeneration. This phenomenon may be seen in postsynaptic neurons (anterograde) or in presynaptic neurons (retrograde). Retrograde trans-synaptic degeneration (RTSD) of the retinal ganglion cells and retinal nerve fiber layer following injury to the occipital lobe has been well documented histologically in animal studies, but its occurrence in the human retina was, for many years, felt to be limited to cases of neonatal injury during a critical period of neuronal development...
February 2017: Current Neurology and Neuroscience Reports
https://www.readbyqxmd.com/read/28228269/diverse-central-projection-patterns-of-retinal-ganglion-cells
#3
Emily M Martersteck, Karla E Hirokawa, Mariah Evarts, Amy Bernard, Xin Duan, Yang Li, Lydia Ng, Seung W Oh, Benjamin Ouellette, Joshua J Royall, Michelle Stoecklin, Quanxin Wang, Hongkui Zeng, Joshua R Sanes, Julie A Harris
Understanding how >30 types of retinal ganglion cells (RGCs) in the mouse retina each contribute to visual processing in the brain will require more tools that label and manipulate specific RGCs. We screened and analyzed retinal expression of Cre recombinase using 88 transgenic driver lines. In many lines, Cre was expressed in multiple RGC types and retinal cell classes, but several exhibited more selective expression. We comprehensively mapped central projections from RGCs labeled in 26 Cre lines using viral tracers, high-throughput imaging, and a data processing pipeline...
February 21, 2017: Cell Reports
https://www.readbyqxmd.com/read/28227922/evaluation-of-effects-of-electrical-stimulation-in-the-retina-with-optical-coherence-tomography
#4
A Gonzalez-Calle, J D Weiland, A Gonzalez-Calle, J D Weiland, A Gonzalez-Calle, J D Weiland
Retinal prostheses provide the capability to blind patients to detect motion and locate large objects. To avoid activating axons of passage, which can create streak-like perceptions, long pulse stimulation can be used to bypass axons and achieve focal retinal activation. Safety is a concern because long pulses require more charge than short pulses to elicit a response from neural tissue. Future implants will require smaller electrodes to improve resolution, but increased charge density may result, which is another safety concern...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227742/a-computational-model-of-orientation-dependent-activation-of-retinal-ganglion-cells
#5
Timothy Esler, Anthony N Burkitt, David B Grayden, Robert R Kerr, Bahman Tahayori, Hamish Meffin, Timothy Esler, Anthony N Burkitt, David B Grayden, Robert R Kerr, Bahman Tahayori, Hamish Meffin, Anthony N Burkitt, Timothy Esler, Hamish Meffin, David B Grayden, Robert R Kerr, Bahman Tahayori
Currently, a challenge in electrical stimulation for epiretinal prostheses is the avoidance of stimulation of axons of passage in the nerve fiber layer that originate from distant regions of the ganglion cell layer. A computational model of extracellular stimulation that captures the effect of neurite orientation in anisotropic tissue is developed using a modified version of the standard volume conductor model, known as the cellular composite model, embedded in a four layer model of the retina. Simulations are conducted to investigate the interaction of neural tissue orientation, electrode placement, and stimulation pulse duration and amplitude...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227660/robot-assisted-retinal-vein-cannulation-with-force-based-puncture-detection-micron-vs-the-steady-hand-eye-robot
#6
Berk Gonenc, Nhat Tran, Peter Gehlbach, Russell H Taylor, Iulian Iordachita, Berk Gonenc, Nhat Tran, Peter Gehlbach, Russell H Taylor, Iulian Iordachita, Nhat Tran, Russell H Taylor, Iulian Iordachita, Berk Gonenc, Peter Gehlbach
Retinal vein cannulation is a demanding procedure where therapeutic agents are injected into occluded retina veins. The feasibility of this treatment is limited due to challenges in identifying the moment of venous puncture, achieving cannulation and maintaining it throughout the drug delivery period. In this study, we integrate a force-sensing microneedle with two distinct robotic systems: the handheld micromanipulator Micron, and the cooperatively controlled Steady-Hand Eye Robot (SHER). The sensed tool-to-tissue interaction forces are used to detect venous puncture and extend the robots' standard control schemes with a new position holding mode (PHM) that assists the operator hold the needle position fixed and maintain cannulation for a longer time with less trauma on the vasculature...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227567/a-method-to-assess-the-location-and-positional-stability-of-supra-choroidal-retinal-neuroprostheses
#7
Barry S Gow, Gregg J Suaning, Barry S Gow, Gregg J Suaning, Barry S Gow, Gregg J Suaning
Electrical stimulation of the retina is now firmly established as a means of restoration of rudimentary vision for blindness particularly that caused by retinitis pigmentosa. Of the various approaches, the novel positioning of an ultra-thin stimulating electrode array (SEA) posterior to the choroid has shown promising results. Following their implantation, reliable imaging methods are essential to establish the SEA's location relative to the optic disk and retinal vasculature. Because the opacity of the choroid precludes the use of conventional light-based fundus imaging, we developed an instrument (Wangiscope) that relies on infra-red illumination from LEDs...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227211/an-automatic-quantitative-measurement-method-for-performance-assessment-of-retina-image-registration-algorithms
#8
Ee Ping Ong, Jimmy Addison Lee, Guozhen Xu, Beng Hai Lee, Damon W K Wong, Ee Ping Ong, Jimmy Addison Lee, Guozhen Xu, Beng Hai Lee, Damon W K Wong, Jimmy Addison Lee, Guozhen Xu, Ee Ping Ong, Beng Hai Lee, Damon W K Wong
This paper presents a novel automatic quantitative measurement method for assessment of the performance of image registration algorithms designed for registering retina fundus images. To achieve automatic quantitative measurement, we propose the use of edges and edge dissimilarity measure for determining the performance of retina image registration algorithms. Our input is the registered pair of retina fundus images obtained using any of the existing retina image registration algorithms in the literature. To compute edge dissimilarity score, we propose an edge dissimilarity measure that we called "robustified Hausdorff distance"...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227208/mapping-the-retinas-of-a-patient-using-a-mixed-set-of-fundus-photographs-from-both-eyes
#9
Gwenole Quellec, Mathieu Lamard, Guy Cazuguel, Ali Erginay, Beatrice Cochener, Gwenole Quellec, Mathieu Lamard, Guy Cazuguel, Ali Erginay, Beatrice Cochener, Gwenole Quellec, Guy Cazuguel, Mathieu Lamard, Ali Erginay, Beatrice Cochener
With the increased prevalence of retinal pathologies, automating the detection and progression measurement of these pathologies is becoming more and more relevant. Color fundus photography is the leading modality for assessing retinal pathologies. Because eye fundus cameras have a limited field of view, multiple photographs are taken from each retina during an eye fundus examination. However, operators usually don't indicate which photographs are from the left retina and which ones are from the right retina...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227182/strategies-to-improve-stimulation-efficiency-for-retinal-prostheses
#10
Navya S Davuluri, Kiran Nimmagadda, Artin Petrossians, Mark S Humayun, James D Weiland, Navya S Davuluri, Kiran Nimmagadda, Artin Petrossians, Mark S Humayun, James D Weiland, Mark S Humayun, Kiran Nimmagadda, Navya S Davuluri, James D Weiland, Artin Petrossians
Retinitis Pigmentosa (RP) is a degenerative disease of the retina that leads to vision loss. Retinal prostheses are being developed in order to restore functional vision in patients suffering from RP. We conducted in-vivo experiments in order to identify strategies to efficiently stimulate the retina. We electrically stimulated the retina and measured electrically evoked potentials (EERs) from the superior colliculus of rats. We compared the strength of EERs when voltage-controlled and current-controlled pulses of varying pulse width and charge levels were applied to the retina...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226848/robust-spike-sorting-of-retinal-ganglion-cells-tuned-to-spot-stimuli
#11
Alireza Ghahari, Tudor C Badea, Alireza Ghahari, Tudor C Badea, Alireza Ghahari, Tudor C Badea
We propose an automatic spike sorting approach for the data recorded from a microelectrode array during visual stimulation of wild type retinas with tiled spot stimuli. The approach first detects individual spikes per electrode by their signature local minima. With the mixture probability distribution of the local minima estimated afterwards, it applies a minimum-squared-error clustering algorithm to sort the spikes into different clusters. A template waveform for each cluster per electrode is defined, and a number of reliability tests are performed on it and its corresponding spikes...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226745/in-vivo-characterization-of-genetic-expression-of-virus-transduced-calcium-indicators-in-retinal-ganglion-cells-using-a-low-cost-funduscope
#12
Yao-Chuan Chang, Steven T Walston, Robert H Chow, James D Weiland, Yao-Chuan Chang, Steven T Walston, Robert H Chow, James D Weiland, Robert H Chow, Yao-Chuan Chang, Steven T Walston, James D Weiland
Virus-transduced calcium indicators are effective reporters of neural activity, offering the advantage of cell-specific labeling. To track the level of in vivo expression of genetically encoded calcium indicators (GECIs) in rodent retina, we developed a noninvasive imaging approach based on a custom-modified low-cost and simple fundus system that enabled us to monitor and characterize in vivo bright-field and fluorescence retinal image. The system clearly resolves individual retinal ganglion cells (RGCs) and axons...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226407/relationship-between-functional-and-structural-retinal-changes-in-myopic-eyes
#13
Zafer Fahiem Ismael, Amany Abd El-Fattah El-Shazly, Yousra Ahmed Farweez, Marwa Mahmoud Mohammed Osman
BACKGROUND: The aim of this study was to investigate the retinal structure in different grades of myopia and correlate it with the functional changes detected with multifocal electroretinogram (mf-ERG) and try to show the most important determining factors. METHODS: The study included 80 participants divided into four groups according to their spherical equivalent refractive error, namely, emmetropia (within ± 0.50 D), mild myopia group (greater than -0.50 to -3...
February 22, 2017: Clinical & Experimental Optometry: Journal of the Australian Optometrical Association
https://www.readbyqxmd.com/read/28225725/clinical-features-of-affected-and-undetached-fellow-eyes-in-patients-with-fevr-associated-rhegmatogenous-retinal-detachment
#14
Miner Yuan, Xiaoyan Ding, Yu Yang, Fang Liu, Jiaqing Li, Xiaoling Liang, Xiongze Zhang, Andina Hu, Zijing Li, Zongyi Zhan, Lin Lu
PURPOSE: To report the clinical characteristics of the affected and fellow eyes in patients with familial exudative vitreoretinopathy-associated rhegmatogenous retinal detachment (FEVR-RRD). METHODS: This was a retrospective observational case series. The affected and fellow eyes were given complete examinations. The age, sex, clinical features of the affected eyes, and varied abnormalities of the fellow eyes were analyzed. RESULTS: Forty-three patients with FEVR-RRD were included...
March 2017: Retina
https://www.readbyqxmd.com/read/28225724/outer-retinal-tubulation-in-retinal-dystrophies
#15
Imoro Z Braimah, Sunila Dumpala, Jay Chhablani
BACKGROUND/PURPOSE: To evaluate the occurrence and characteristics of outer retinal tubulation (ORT) in an Indian population with retinal dystrophies. METHODS: In this retrospective study, 309 eyes of 157 patients with retinal dystrophies including retinitis pigmentosa (RP, 183 eyes), Stargardt disease (STGD, 93 eyes) and Best disease (33 eyes) were reviewed. The demographic details, clinical data including visual acuity, treatment history and good quality spectral domain optical coherence tomography (SD-OCT) scans were collected...
March 2017: Retina
https://www.readbyqxmd.com/read/28225373/outer-retinal-tubulation-a-case-series
#16
Leticia A Rousso, Julie A Rodman, Brad Sutton, Diana L Shechtman
PURPOSE: The advent of spectral domain optical coherence tomography has led to superb imaging capabilities in addition to enhanced visualization of the retinal layers. Such advancements have led to the identification of a variety of new retinal conditions, including outer retinal tubulations (ORTs). ORTs are ovoid hyporeflective spaces located in the outer retina. The pathogenesis is unclear but seems to involve sublethal injury to the photoreceptors leading to a compensatory reorganization of the photoreceptor layer with the neighboring ellipsoid zone resulting in a hyperreflective border surrounding a central lumen...
March 2017: Optometry and Vision Science: Official Publication of the American Academy of Optometry
https://www.readbyqxmd.com/read/28225372/spherical-soft-contact-lens-designs-and-peripheral-defocus-in-myopic-eyes
#17
Kelly E Moore, Julia S Benoit, David A Berntsen
PURPOSE: Peripheral retinal defocus has been implicated in myopia progression. The effect of commercially available spherical soft contact lenses (SCLs) on peripheral defocus of adult myopic eyes was investigated. METHODS: Twenty-five young adults with spherical equivalent (SE) refractions between -0.50D and -6.00D were enrolled. Cycloplegic autorefraction (right eye) was measured centrally and ±20°, ±30°, and ±40° from the line of sight along the horizontal meridian using an autorefractor...
March 2017: Optometry and Vision Science: Official Publication of the American Academy of Optometry
https://www.readbyqxmd.com/read/28225371/measurement-of-perceived-stress-in-age-related-macular-degeneration
#18
Bradley E Dougherty, San-San L Cooley, Frederick H Davidorf
PURPOSE: To validate the Perceived Stress Scale (PSS) in patients with age-related macular degeneration (AMD) using Rasch analysis. METHODS: Study participants with AMD were recruited from the retina service of the Department of Ophthalmology at the Ohio State University during clinical visits for treatment or observation. Visual acuity with habitual distance correction was assessed. A 10-item version of the PSS was administered in large print or by reading the items to the patient...
March 2017: Optometry and Vision Science: Official Publication of the American Academy of Optometry
https://www.readbyqxmd.com/read/28225234/-renovascular-disease-in-children-a%C3%A2-rare-diagnosis-with-few-symptoms
#19
Hjørdis Thorsteinsdottir, Eric Dorenberg, Pål-Dag Line, Anna Bjerre
BACKGROUND To estimate the prevalence, symptoms, causes and treatment of renovascular disease in children, and also to assess the degree of secondary organ damage to the heart, kidneys and eyes (end organ damage).MATERIAL AND METHOD Retrospective review of data for all children (0 - 16 years) who were examined for resistant hypertension in the period 1998 - 2013 at Oslo University Hospital Rikshospitalet.RESULTS A total of 21 children/adolescents (median age 8.5 years, 11 girls) were assessed and treated for resistant hypertension in the study period...
February 2017: Tidsskrift for Den Norske Lægeforening: Tidsskrift for Praktisk Medicin, Ny Række
https://www.readbyqxmd.com/read/28224388/ocular-safety-of-intravitreal-clindamycin-hydrochloride-released-by-plga-implants
#20
Gabriella M Fernandes-Cunha, Silvia Ligório Fialho, Gisele Rodrigues da Silva, Armando Silva-Cunha, Min Zhao, Francine Behar-Cohen
BACKGROUND: Drug ocular toxicity is a field that requires attention. Clindamycin has been injected intravitreally to treat ocular toxoplasmosis, the most common cause of eye posterior segment infection worldwide. However, little is known about the toxicity of clindamycin to ocular tissues. We have previously showed non intraocular toxicity in rabbit eyes of poly(lactic-co-glycolic acid) (PLGA) implants containing clindamycin hydrochloride (CLH) using only clinical macroscotopic observation...
February 21, 2017: Pharmaceutical Research
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