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Color vision

Joern Kuchenbecker
BACKGROUND: Pseudoisochromatic colour plates are constructed according to specific principles. They can be very different in quality. To check the diagnostic quality, they have to be tested on a large number of subjects, but this procedure is can be tedious and expensive. Therefore, the use of a standardised web-based test is recommended. METHODS: Eight Pflüger trident colour plates (including 1 demo plate) according to the Velhagen edition of 1980 were digitised and inserted into a web-based colour vision test (www...
May 22, 2018: Klinische Monatsblätter Für Augenheilkunde
Mohab Eldeeb, Errol W Chan, Amer Omar
SIGNIFICANCE: Hydroxychloroquine retinopathy causes irreversible central visual loss and can progress despite medication discontinuation. Appropriate dosing and recognition of early disease are important to minimize adverse visual sequelae. In 2016, the American Academy of Ophthalmology updated its 2011 recommendations for dosing, screening, and monitoring of hydroxychloroquine retinopathy. PURPOSE: The aim of this study was to report a case of hydroxychloroquine retinopathy in a patient who developed toxicity on a dose meeting safety thresholds from the 2011 guidelines (i...
May 21, 2018: Optometry and Vision Science: Official Publication of the American Academy of Optometry
Lynn Shi, Linus D Sun, Jeffrey G Odel
Purpose: Since its report in one patient more than 70 years ago, digitalis-induced colored muscae volitantes have not surfaced again in the literature. We report here a case of digoxin induced colored floaters. Observations: An 89-year-old man on 0.25 mg digoxin daily developed visual hallucinations and colored floaters. He had floaters in the past but now they were in various colors including yellow, green, blue and red, though predominantly in yellow. These "weirdly" shaped little particles wiggled around as if in a viscous solution and casted shadows in his vision...
June 2018: American Journal of Ophthalmology Case Reports
Elad Moisseiev
Purpose: To describe a new family with benign yellow dot maculopathy. Observations: A young male patient was found to have bilateral multiple small yellow dots in both maculae. Visual acuity and color vision were normal, and no pathological findings were demonstrated on automated visual field, optical coherence tomography (OCT) and electrophysiological testing. Examination of his parents revealed similar findings in his mother, suggesting autosomal dominant inheritance...
June 2018: American Journal of Ophthalmology Case Reports
Gaozhen Liang, Chunwang Dong, Bin Hu, Hongkai Zhu, Haibo Yuan, Yongwen Jiang, Guoshuang Hao
Withering is the first step in the processing of congou black tea. With respect to the deficiency of traditional water content detection methods, a machine vision based NDT (Non Destructive Testing) method was established to detect the moisture content of withered leaves. First, according to the time sequences using computer visual system collected visible light images of tea leaf surfaces, and color and texture characteristics are extracted through the spatial changes of colors. Then quantitative prediction models for moisture content detection of withered tea leaves was established through linear PLS (Partial Least Squares) and non-linear SVM (Support Vector Machine)...
May 18, 2018: Scientific Reports
Alina González-Quevedo, Rosaralis Santiesteban-Freixas, Janis T Eells, Lucimey Lima, Alfredo A Sadun
From 1991 to 1993, an epidemic of optic and peripheral neuropathy-the largest of the century-broke out in Cuba, affecting more than 50,000 people. Initially the main clinical features were decreased visual acuity, central and cecocentral scotomas, impaired color vision and absence of the papillomacular bundle. Later, peripheral and mixed optic-peripheral forms began to appear. Due to the magnitude of the epidemic, the Cuban government requested help from the international community at the 46th World Health Assembly in 1993...
April 2018: MEDICC Review
Claudia Feitosa-Santana, Margaret Lutze, Pablo A Barrionuevo, Dingcai Cao
Based on known color vision theories, there is no complete explanation for the perceptual dichotomy of #TheDress in which most people see either white-and-gold (WG) or blue-and-black (BK). We determined whether some standard color vision tests (i.e., color naming, color matching, anomaloscope settings, unique white settings, and color preferences), as well as chronotypes, could provide information on the color perceptions of #TheDress. Fifty-two young observers were tested. Fifteen of the observers (29%) reported the colors as BK, 21 (40%) as WG, and 16 (31%) reported a different combination of colors...
March 2018: I-Perception
Ichiro Kuriki
The purpose of the present study is to propose a simple algorithm for color appearance simulation under a color illuminant. Achromatic point is a chromaticity of rays that appear neither red nor green, neither blue nor yellow under a given illuminant condition. Saturation and hue of surface colors are evaluated with respect to the achromatic point of the same lightness, while the achromatic point under a colored illuminant depends on the lightness tested. We previously found that this achromatic point locus can be simply approximated as a line with a parallel offset from the lightness axis of CIE LAB space normalized to daylight...
March 2018: I-Perception
Anett Karl, Silke Agte, Astrid Zayas-Santiago, Felix N Makarov, Yomarie Rivera, Jan Benedikt, Mike Francke, Andreas Reichenbach, Serguei N Skatchkov, Andreas Bringmann
It has been shown that mammalian retinal glial (Müller) cells act as living optical fibers that guide the light through the retinal tissue to the photoreceptor cells (Agte et al., 2011; Franze et al., 2007). However, for nonmammalian species it is unclear whether Müller cells also improve the transretinal light transmission. Furthermore, for nonmammalian species there is a lack of ultrastructural data of the retinal cells, which, in general, delivers fundamental information of the retinal function, i.e. the vision of the species...
May 10, 2018: Experimental Eye Research
Samir Hasanov, Elif Demirkilinc Biler, Ahmet Acarer, Cezmi Akkın, Zafer Colakoglu, Onder Uretmen
PURPOSE: To evaluate and follow-up of functional and morphological changes of the optic nerve and ocular structures prospectively in patients with early-stage Parkinson's disease. MATERIALS AND METHODS: Nineteen patients with a diagnosis of early-stage Parkinson's disease and 19 age-matched healthy controls were included in the study. All participants were examined minimum three times at the intervals of at least 6 month following initial examination. Pattern visually evoked potentials (VEP), contrast sensitivity assessments at photopic conditions, color vision tests with Ishihara cards and full-field visual field tests were performed in addition to measurement of retinal nerve fiber layer (RNFL) thickness of four quadrants (top, bottom, nasal, temporal), central and mean macular thickness and macular volumes...
May 9, 2018: International Ophthalmology
Sarah Lumsden, Gabor Rosta, Jean Bismuth, Alan B Lumsden, Zsolt Garami
Dissection of the internal carotid artery (ICA) accounts for 5% to 25% of ischemic strokes in young adults. We report a case of spontaneous recanalization of a traumatic ICA dissection in which carotid duplex (CDU) and transcranial color-coded duplex ultrasound (TCCD) were used. A 47-year-old male presented with intermittent episodes of headache, blurry vision, anisocoria, and loss of taste sensation following a whiplash injury while body surfing. Magnetic resonance angiogram (MRA) of the neck revealed absent flow in the cavernous ICA and a clot at the skull base...
October 2017: Methodist DeBakey Cardiovascular Journal
Samuel B Powell, Roman Garnett, Justin Marshall, Charbel Rizk, Viktor Gruev
With its never-ending blue color, the underwater environment often seems monotonic and featureless. However, to an animal with polarization-sensitive vision, it is anything but bland. The rich repertoire of underwater polarization patterns-a consequence of light's air-to-water transmission and in-water scattering-can be exploited both as a compass and for geolocalization purposes. We demonstrate that, by using a bioinspired polarization-sensitive imager, we can determine the geolocation of an observer based on radial underwater polarization patterns...
April 2018: Science Advances
Alex L White, John Palmer, Geoffrey M Boynton
To test the limits of parallel processing in vision, we investigated whether people can recognize two words at once. Participants viewed brief, masked pairs of words and were instructed in advance to judge both of the words (dual-task condition) or just one of the words (single-task condition). For judgments of semantic category, the dual-task deficit was so large that it supported all-or-none serial processing: Participants could recognize only one word and had to guess about the other. Moreover, participants were more likely to be correct about one word if they were incorrect about the other, which also supports a serial-processing model...
May 1, 2018: Psychological Science
Ivet Rafegas, Maria Vanrell
Convolutional Neural Networks have been proposed as suitable frameworks to model biological vision. Some of these artificial networks showed representational properties that rival primate performances in object recognition. In this paper we explore how color is encoded in a trained artificial network. It is performed by estimating a color selectivity index for each neuron, which allows us to describe the neuron activity to a color input stimuli. The index allows us to classify whether they are color selective or not and if they are of a single or double color...
May 11, 2018: Vision Research
Shuang Yu, Di Xiao, Yogesan Kanagasingam
In this paper, the automatic detection of neovascularization in the optic disc region (NVD) for color fundus retinal image is presented. NV is the indicator for the onset of proliferative diabetic retinopathy and it is featured by the presence of new vessels in the retina. The new vessels are fragile and pose a high risk for sudden vision loss. Therefore, the importance of accurate and timely detection of NV cannot be underestimated. We propose an automatic image processing procedure for NVD detection that involves vessel segmentation using multilevel Gabor filtering, feature extraction of vessel morphological features and texture features, and image classification with support vector machine...
May 2018: IEEE Journal of Biomedical and Health Informatics
Boštjan Pohlen, Marko Hawlina, Manca Tekavčič Pompe, Igor Kopač
PURPOSE: To evaluate the effect of color-vision deficiencies and type 1 diabetes mellitus (DM) on visual shade-matching ability. MATERIALS AND METHODS: Four groups of participants were investigated: a control group (n = 68); a group with protanomalia (n = 10); a group with deuteranomalia (n = 19); and a group with type 1 DM (n = 13). Color vision was evaluated monocularly using the Ishihara test, Farnsworth-Munsell 100 hue (FM100H) test, Hardy Rand Rittler (HRR) test, and with an HMC Anomaloskop MR (Rayleigh and Moreland tests)...
May 2018: International Journal of Prosthodontics
Abdel-Rahman Badawy, Muhammad Umair Hassan, Mohamed Elsherif, Zubair Ahmed, Ali K Yetisen, Haider Butt
Color vision deficiency (color blindness) is an inherited genetic ocular disorder. While no cure for this disorder currently exists, several methods can be used to increase the color perception of those affected. One such method is the use of color filtering glasses which are based on Bragg filters. While these glasses are effective, they are high cost, bulky, and incompatible with other vision correction eyeglasses. In this work, a rhodamine derivative is incorporated in commercial contact lenses to filter out the specific wavelength bands (≈545-575 nm) to correct color vision blindness...
April 26, 2018: Advanced Healthcare Materials
Alexandre Marcireau, Sio-Hoi Ieng, Camille Simon-Chane, Ryad B Benosman
This paper introduces a color asynchronous neuromorphic event-based camera and a methodology to process color output from the device to perform color segmentation and tracking at the native temporal resolution of the sensor (down to one microsecond). Our color vision sensor prototype is a combination of three Asynchronous Time-based Image Sensors, sensitive to absolute color information. We devise a color processing algorithm leveraging this information. It is designed to be computationally cheap, thus showing how low level processing benefits from asynchronous acquisition and high temporal resolution data...
2018: Frontiers in Neuroscience
D Jackson Coleman, Winston Lee, Stanley Chang, Ronald H Silverman, Harriet O Lloyd, Suzanne Daly, Stephen H Tsang
OBJECTIVE: To evaluate PDE5/6 inhibition with sildenafil to reduce choroidal ischemia and treat age-related macular degeneration. METHODS: Sildenafil was prescribed to treat participants with macular degenerations or macular dystrophies measured by spectral-domain optical coherence tomography, color fundus photography, enhanced depth imaging, and best-corrected visual acuity. RESULTS: No change in calcified drusen was noted. Vitelliform-type soft drusen were not substantially changed...
April 25, 2018: Ophthalmologica. Journal International D'ophtalmologie
Pedro Reino-Pires, Manuel Lopez
OBJECTIVE: We aimed to develop and validate a low cost, do-it-yourself model for neonatal thoracoscopic congenital diaphragmatic hernia (CDH). DESIGN: Volunteers with varying skills in neonatal minimally invasive surgery tested and evaluated the model simulating a neonatal thoracoscopic CDH repair. The model was built from ordinary materials purchased in a dime store: a small food container, a neoprene band simulating a diaphragm, an inflated balloon simulating a spleen, a tissue chord simulating intestine, and a body wash sponge simulating a collapsed lung...
April 20, 2018: Journal of Surgical Education
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