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artificial retina

Javier Vicente-Tejedor, Miguel Marchena, Laura Ramírez, Diego García-Ayuso, Violeta Gómez-Vicente, Celia Sánchez-Ramos, Pedro de la Villa, Francisco Germain
Light causes damage to the retina (phototoxicity) and decreases photoreceptor responses to light. The most harmful component of visible light is the blue wavelength (400-500 nm). Different filters have been tested, but so far all of them allow passing a lot of this wavelength (70%). The aim of this work has been to prove that a filter that removes 94% of the blue component may protect the function and morphology of the retina significantly. Three experimental groups were designed. The first group was unexposed to light, the second one was exposed and the third one was exposed and protected by a blue-blocking filter...
2018: PloS One
Lukas Everding, Jörg Conradt
In order to safely navigate and orient in their local surroundings autonomous systems need to rapidly extract and persistently track visual features from the environment. While there are many algorithms tackling those tasks for traditional frame-based cameras, these have to deal with the fact that conventional cameras sample their environment with a fixed frequency. Most prominently, the same features have to be found in consecutive frames and corresponding features then need to be matched using elaborate techniques as any information between the two frames is lost...
2018: Frontiers in Neurorobotics
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
A Soleimani, S H Rasta, T Banaei, A Asgharsharghi Bonab
Introduction: The aim of the present study was to determine burn intensity in retinal laser photocoagulation based on laser parameters; wavelength, power, beam size and pulse duration, using Optical Coherence Tomography (OCT), fundus camera, physical eye model and computer simulation in a clinical study. Materials and Methods: Participants were 10 adult patients between 50-80 years with proliferative diabetic retinopathy. A multicolor-photo coagulator with 532 nm green and 672 nm red for retina photocoagulation in diabetic retinopathy was used to investigate the participants...
December 2017: Journal of Biomedical Physics & Engineering
Sophie Leacock, Parnayan Syed, Victoria M James, Anna Bode, Koichi Kawakami, Angelo Keramidas, Maximiliano Suster, Joseph W Lynch, Robert J Harvey
Inhibitory glycine receptors (GlyRs) are pentameric ligand-gated anion channels with major roles in startle disease/hyperekplexia (GlyR α1), cortical neuronal migration/autism spectrum disorder (GlyR α2), and inflammatory pain sensitization/rhythmic breathing (GlyR α3). However, the role of the GlyR α4 subunit has remained enigmatic, because the corresponding human gene ( GLRA4 ) is thought to be a pseudogene due to an in-frame stop codon at position 390 within the fourth membrane-spanning domain (M4). Despite this, a recent genetic study has implicated GLRA4 in intellectual disability, behavioral problems and craniofacial anomalies...
2018: Frontiers in Molecular Neuroscience
Maesoon Im, Paul Werginz, Shelley Fried
To improve the quality of artificial vision that arises from retinal prostheses, it is important to bring electrically-elicited neural activity more in line with the physiological signaling patterns that arise normally in the healthy retina. Our previous study reported that indirect activation produces a closer match to physiological responses in ON retinal ganglion cells (RGCs) than in OFF cells . This suggests that a preferential activation of ON RGCs would shape the overall retinal response closer to natural signaling...
February 8, 2018: Journal of Neural Engineering
Corey M Rountree, John B Troy, Laxman Saggere
Photoreceptor degenerative diseases cause irreparable blindness through the progressive loss of photoreceptor cells in the retina. Retinal prostheses are an emerging treatment for photoreceptor degenerative diseases that seek to restore vision by artificially stimulating the surviving retinal neurons in the hope of eliciting comprehensible visual perception in patients. Current retinal prostheses have demonstrated success in restoring limited vision to patients using an array of electrodes to electrically stimulate the retina but face substantial physical barriers in restoring high acuity, natural vision to patients...
December 19, 2017: Journal of Visualized Experiments: JoVE
Tanya Orlov, Ehud Zohary
We typically recognize visual objects using the spatial layout of their parts, which are present simultaneously on the retina. Therefore, shape extraction is based on integration of the relevant retinal information over space. The lateral occipital complex (LOC) can represent shape faithfully in such conditions. However, integration over time is sometimes required to determine object shape. To study shape extraction through temporal integration of successive partial shape views, we presented human participants (both men and women) with artificial shapes that moved behind a narrow vertical or horizontal slit...
January 17, 2018: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
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
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
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
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
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
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
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
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
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
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
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
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
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