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https://www.readbyqxmd.com/read/29140328/retina-simulating-phantom-produced-by-photolithography
#1
Denise Valente, Brian Vohnsen
Cone photoreceptors have a narrow acceptance angle that is well matched to the size of the eye pupil and dampens the visual impact of aberrations and scattering. However, the structure of the human retina is not replicated in existing eye models used to test refractive designs or retinal implants that restore partial vision to the blind. Here, we report on an artificial waveguide-based retinal phantom manufactured by photolithography in photoresist film with dimensions and refractive index contrast similar to the retinal receptor layer...
November 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/29127485/oct-based-deep-learning-algorithm-for-the-evaluation-of-treatment-indication-with-anti-vascular-endothelial-growth-factor-medications
#2
Philipp Prahs, Viola Radeck, Christian Mayer, Yordan Cvetkov, Nadezhda Cvetkova, Horst Helbig, David Märker
PURPOSE: Intravitreal injections with anti-vascular endothelial growth factor (anti-VEGF) medications have become the standard of care for their respective indications. Optical coherence tomography (OCT) scans of the central retina provide detailed anatomical data and are widely used by clinicians in the decision-making process of anti-VEGF indication. In recent years, significant progress has been made in artificial intelligence and computer vision research. We trained a deep convolutional artificial neural network to predict treatment indication based on central retinal OCT scans without human intervention...
November 10, 2017: Graefe's Archive for Clinical and Experimental Ophthalmology
https://www.readbyqxmd.com/read/29073735/spatiotemporal-pixelization-to-increase-the-recognition-score-of-characters-for-retinal-prostheses
#3
Hyun Seok Kim, Kwang Suk Park
Most of the retinal prostheses use a head-fixed camera and a video processing unit. Some studies proposed various image processing methods to improve visual perception for patients. However, previous studies only focused on using spatial information. The present study proposes a spatiotemporal pixelization method mimicking fixational eye movements to generate stimulation images for artificial retina arrays by combining spatial and temporal information. Input images were sampled with a resolution that was four times higher than the number of pixel arrays...
October 24, 2017: Sensors
https://www.readbyqxmd.com/read/29064455/spatiotemporal-pixelization-to-increase-the-recognition-score-of-characters-for-retinal-prostheses
#4
Hyun Seok Kim, Kwang Suk Park
Most of the retinal prostheses use a head-fixed camera and a video processing unit. Some studies proposed various image processing methods to improve visual perception for patients. However, previous studies only focused on using spatial information. The present study proposes a spatiotemporal pixelization method mimicking fixational eye movements to generate stimulation images for artificial retina arrays by combining spatial and temporal information. Input images were sampled with a resolution that was four times higher than the number of pixel arrays...
October 24, 2017: Sensors
https://www.readbyqxmd.com/read/29060066/flexible-microelectrode-array-for-retinal-prosthesis
#5
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/29044990/transcriptome-analysis-for-uvb-induced-phototoxicity-in-mouse-retina
#6
Mi-Jin An, Chul-Hong Kim, Gyu-You Nam, Dae-Hyun Kim, Sangmyung Rhee, Sung-Jin Cho, Jung-Woong Kim
Throughout life, the human eye is continuously exposed to sunlight and artificial lighting. Ambient light exposure can lead to visual impairment and transient or permanent blindness. To mimic benign light stress conditions, Mus musculus eyes were exposed to low-energy UVB radiation, ensuring no severe morphological changes in the retinal structure post-exposure. We performed RNA-seq analysis to reveal the early transcriptional changes and key molecular pathways involved before the activation of the canonical cell death pathway...
October 17, 2017: Environmental Toxicology
https://www.readbyqxmd.com/read/28956858/circadian-rhythms-of-retinomotor-movement-in-a-marine-megapredator-the-atlantic-tarpon-megalops-atlanticus
#7
Kristin L Kopperud, Michael S Grace
Many ecologically and economically important marine fish species worldwide spend portions of their lives in coastal regions that are increasingly inundated by artificial light at night. However, while extensive research illustrates the harmful effects of inappropriate light exposure on biological timing in humans, rodents and birds, comparable studies on marine fish are virtually nonexistent. This study aimed to assess the effects of light on biological clock function in the marine fish retina using the Atlantic tarpon (Megalops atlanticus) as a model...
September 28, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28900776/haloarchaea-worth-exploring-for-their-biotechnological-potential
#8
REVIEW
Aparna Singh, Anil K Singh
Halophilic archaea are unique microorganisms adapted to survive under high salt conditions and biomolecules produced by them may possess unusual properties. Haloarchaeal metabolites are stable at high salt and temperature conditions that are useful for industrial applications. Proteins and enzymes of this group of archaea are functional under salt concentrations at which bacterial counterparts fail to be active. Such properties makes haloarchaeal enzymes suitable for salt-based applications and their use under dehydrating conditions...
September 12, 2017: Biotechnology Letters
https://www.readbyqxmd.com/read/28871236/non-visual-photopigments-effects-of-constant-light-emitting-diode-light-exposure-on-the-inner-retina-of-wistar-rats
#9
María M Benedetto, Mario E Guido, María A Contin
The retina is part of the central nervous system specially adapted to capture light photons and transmit this information to the brain through photosensitive retinal cells involved in visual and non-visual activities. However, excessive light exposure may accelerate genetic retinal diseases or induce photoreceptor cell (PRC) death, finally leading to retinal degeneration (RD). Light pollution (LP) caused by the characteristic use of artificial light in modern day life may accelerate degenerative diseases or promote RD and circadian desynchrony...
2017: Frontiers in Neurology
https://www.readbyqxmd.com/read/28794849/scaffolds-for-retinal-pigment-epithelial-cell-transplantation-in-age-related-macular-degeneration
#10
REVIEW
Corina E White, Ronke M Olabisi
In several retinal degenerative diseases, including age-related macular degeneration, the retinal pigment epithelium, a highly functionalized cell monolayer, becomes dysfunctional. These retinal diseases are marked by early retinal pigment epithelium dysfunction reducing its ability to maintain a healthy retina, hence making the retinal pigment epithelium an attractive target for treatment. Cell therapies, including bolus cell injections, have been investigated with mixed results. Since bolus cell injection does not promote the proper monolayer architecture, scaffolds seeded with retinal pigment epithelium cells and then implanted have been increasingly investigated...
January 2017: Journal of Tissue Engineering
https://www.readbyqxmd.com/read/28782627/electrical-stimulation-of-different-retinal-components-and-the-effect-of-asymmetric-pulses
#11
Dorit Raz-Prag, Giora Beit-Yaakov, Yael Hanein
BACKGROUND: High resolution electrical stimulation of neural tissue is a fundamental challenge in applications such as deep brain stimulation and artificial vision. In artificial vision, achieving and validating local selective epi-retinal stimulation of different layers in the retina is particularly challenging owing to plurality of retinal cell types and delocalized wiring. RESULTS: Strong selectivity and non-localized responses to epi-retinal stimulation, over a wide range of realistic stimulation parameters, was achieved and validated using asymmetric pulses...
November 1, 2017: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/28777356/health-effects-of-carotenoids-during-pregnancy-and-lactation
#12
REVIEW
Monika A Zielińska, Aleksandra Wesołowska, Beata Pawlus, Jadwiga Hamułka
Adequate nutrition is particularly important during pregnancy since it is needed not only for maintaining the health of the mother, but also determines the course of pregnancy and its outcome, fetus development as well as the child's health after birth and during the later period of life. Data coming from epidemiological and interventions studies support the observation that carotenoids intake provide positive health effects in adults and the elderly population. These health effects are the result of their antioxidant and anti-inflammatory properties...
August 4, 2017: Nutrients
https://www.readbyqxmd.com/read/28751652/fractal-electrodes-as-a-generic-interface-for-stimulating-neurons
#13
W J Watterson, R D Montgomery, R P Taylor
The prospect of replacing damaged body parts with artificial implants is being transformed from science fiction to science fact through the increasing application of electronics to interface with human neurons in the limbs, the brain, and the retina. We propose bio-inspired electronics which adopt the fractal geometry of the neurons they interface with. Our focus is on retinal implants, although performance improvements will be generic to many neuronal types. The key component is a multifunctional electrode; light passes through this electrode into a photodiode which charges the electrode...
July 27, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28612282/probing-of-peripheral-blood-mononuclear-cells-anchoring-on-tnf-alpha-challenged-vascular-endothelia-in-an-in-vitro-model-of-the-retinal-microvascular
#14
Yuan Li, Yao Lu, Qiong Chen, Yuejun Kang, Ling Yu
Retinopathy is a complication of diabetes that affects the eyes; it stems from damage to the microvasculature of the retina and eventually compromises vision. The diagnosis of retinopathy is difficult to make because there are no early symptoms or warning signs. Dysfunction of the retina's microvascular networks is believed to be associated with inflammatory cytokines and tumor necrosis factor alpha (TNF-α). To investigate the effect of these cytokines, such as TNF-α, a polydimethylsiloxane (PDMS)/glass hydride microfluidic device reflecting the physiological structure of the retina's microvasculature was developed...
September 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28611460/chlorophyll-derivatives-enhance-invertebrate-red-light-and-ultraviolet-phototaxis
#15
Andrea Degl'Innocenti, Leonardo Rossi, Alessandra Salvetti, Attilio Marino, Gabriella Meloni, Barbara Mazzolai, Gianni Ciofani
Chlorophyll derivatives are known to enhance vision in vertebrates. They are thought to bind visual pigments (i.e., opsins apoproteins bound to retinal chromophores) directly within the retina. Consistent with previous findings in vertebrates, here we show that chlorin e6 - a chlorophyll derivative - enhances photophobicity in a flatworm (Dugesia japonica), specifically when exposed to UV radiation (λ = 405 nm) or red light (λ = 660 nm). This is the first report of chlorophyll derivatives acting as modulators of invertebrate phototaxis, and in general the first account demonstrating that they can artificially alter animal response to light at a behavioral level...
June 13, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28575952/biocompatibility-and-neurotoxicity-of-magnesium-alloys-potentially-used-for-neural-repairs
#16
Jianjun Fei, Xiaoxiao Wen, Xiao Lin, Saijilafu, Weihua Wang, Olga Ren, Xinjian Chen, Lili Tan, Ke Yang, Huilin Yang, Lei Yang
Nerve injury, especially the large-size nerve damage, is a serious problem affecting millions of people. Entubulation of two ends of the injured nerve by using an implantable device, e.g., nerve guidance conduit (NGC), to guide the regeneration of nerve tissue is a promising approach for treating the large-size nerve defect. Magnesium (Mg) and its alloys are biodegradable, conductive, and own good mechanical properties. Mg(2+) ion, one of the main degradation products of Mg and its alloys, was reported to promote the proliferation of neural stem cells and their neurite production...
September 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28566464/activation-of-ganglion-cells-and-axon-bundles-using-epiretinal-electrical-stimulation
#17
Lauren E Grosberg, Karthik Ganesan, Georges A Goetz, Sasidhar S Madugula, Nandita Bhaskhar, Victoria Fan, Peter Li, Pawel Hottowy, Wladyslaw Dabrowski, Alexander Sher, Alan M Litke, Subhasish Mitra, E J Chichilnisky
Epiretinal prostheses for treating blindness activate axon bundles, causing large, arc-shaped visual percepts that limit the quality of artificial vision. Improving the function of epiretinal prostheses therefore requires understanding and avoiding axon bundle activation. This study introduces a method to detect axon bundle activation on the basis of its electrical signature and uses the method to test whether epiretinal stimulation can directly elicit spikes in individual retinal ganglion cells without activating nearby axon bundles...
September 1, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28548648/electronic-retinal-implants-and-artificial-vision-journey-and-present
#18
REVIEW
J O Mills, A Jalil, P E Stanga
Retinitis pigmentosa and age-related macular degeneration are two significant causes of severe visual dysfunction. In both, the retinal photoreceptors degenerate, preventing successful conversion of light into electrical energy that is interpreted in the visual cortex as visual function. Artificial vision or visual function began over two centuries ago with the idea of creating artificial light pulses, or phosphenes, through cortical stimulation. The pursuit is now on to improve artificial visual function. Two retinal implants appear the most likely to succeed in the future having undergone multicentre human trials: the Argus II electronic epiretinal device (Second Sight Medical Products, CA, USA) and Alpha-IMS electronic subretinal device (Retina Implant AG, Germany)...
October 2017: Eye
https://www.readbyqxmd.com/read/28541930/progress-in-artificial-vision-through-suprachoroidal-retinal-implants
#19
Lilach Bareket, Alejandro Barriga-Rivera, Marc Patrick Zapf, Nigel H Lovell, Gregg J Suaning
Retinal implants have proven their ability to restore visual sensation to people with degenerative retinopathy, characterized by photoreceptor cell death and the retina's inability to sense light. Retinal bionics operate by electrically stimulating the surviving neurons in the retina, thus triggering the transfer of visual sensory information to the brain. Suprachoroidal implants were first investigated in Australia in the 1950s. In this approach, the neuromodulation hardware is positioned between the sclera and the choroid, thus providing significant surgical and safety benefits for patients, with the potential to maintain residual vision combined with the artificial input from the device...
August 2017: Journal of Neural Engineering
https://www.readbyqxmd.com/read/28532361/electrical-stimulation-of-the-retina-to-produce-artificial-vision
#20
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
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