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Sample records for visual field change

  1. Visualization of a changing dose field.

    Energy Technology Data Exchange (ETDEWEB)

    Helm, T. M (Terry M.); Kornreich, D. E. (Drew E.)

    2002-01-01

    To help visualize the results of dose modeling for nuclear materials processing opcrations, we have developed an integrated model that uses a simple dosc calculation tool to obtain estimates of the dose field in a complex geomctry and then post-process the data to produce a video of the now time-dependent data. We generate two-dimensional radiation fields within an existing physical cnvironment and then analyze them using three-dimensional visualization techniques. The radiation fields are generated for both neutrons and photons. Standard monoenergetic diffusion theory is used to estimate the neutron dosc fields. The photon dose is estimated using a point-kernel formalism, with photon shielding effects and buildup taken into account. The radiation field dynamics are analyzed by interleaving individual 3D graphic 'snapshots' into a smoothed, lime dependent, video-based display. In-the-room workers are 'seen' in the radiation fields via a graphical, 3D fly-through rendering of the room. Worker dose levels can reveal surprising dependencies on operational source placement, source types, worker alignment, shielding alignments, and indirect operations from external workers.

  2. Visual cortex in aging and Alzheimer's disease: changes in visual field maps and population receptive fields

    Science.gov (United States)

    Brewer, Alyssa A.; Barton, Brian

    2012-01-01

    Although several studies have suggested that cortical alterations underlie such age-related visual deficits as decreased acuity, little is known about what changes actually occur in visual cortex during healthy aging. Two recent studies showed changes in primary visual cortex (V1) during normal aging; however, no studies have characterized the effects of aging on visual cortex beyond V1, important measurements both for understanding the aging process and for comparison to changes in age-related diseases. Similarly, there is almost no information about changes in visual cortex in Alzheimer's disease (AD), the most common form of dementia. Because visual deficits are often reported as one of the first symptoms of AD, measurements of such changes in the visual cortex of AD patients might improve our understanding of how the visual system is affected by neurodegeneration as well as aid early detection, accurate diagnosis and timely treatment of AD. Here we use fMRI to first compare the visual field map (VFM) organization and population receptive fields (pRFs) between young adults and healthy aging subjects for occipital VFMs V1, V2, V3, and hV4. Healthy aging subjects do not show major VFM organizational deficits, but do have reduced surface area and increased pRF sizes in the foveal representations of V1, V2, and hV4 relative to healthy young control subjects. These measurements are consistent with behavioral deficits seen in healthy aging. We then demonstrate the feasibility and first characterization of these measurements in two patients with mild AD, which reveal potential changes in visual cortex as part of the pathophysiology of AD. Our data aid in our understanding of the changes in the visual processing pathways in normal aging and provide the foundation for future research into earlier and more definitive detection of AD. PMID:24570669

  3. Patterns of visual field changes in thyroid eye disease.

    Science.gov (United States)

    Choi, Catherine J; Oropesa, Susel; Callahan, Alison B; Glass, Lora R; Teo, Livia; Cestari, Dean M; Kazim, Michael; Freitag, Suzanne K

    2017-08-01

    This article provides a systematic description of visual field changes in thyroid eye disease-compressive optic neuropathy (TED-CON). A retrospective, non-comparative chart review of patients with TED-CON and documented Humphrey Visual Field 24-2 or 30-2 testing was conducted with IRB approval. Ninety-six visual fields in 68 patients were classified into 7 broad categories (superior, inferior, diffuse, temporal, nasal, central/paracentral, enlarged blind spot) and 17 mutually exclusive patterns from the Ocular Hypertension Treatment Study (OHTS) or "other." Fifty-three of 96 visual fields (55%) showed an inferior defect using the broad categories, with the remaining 6 categories ranging from 2% to 14%. The five most common OHTS patterns were other (28%), partial arcuate (28%), partial peripheral rim (9%), arcuate (8%) and altitudinal (7%). Further sub-classification showed a predominance of inferior visual field defects, ranging from 33% to 93% of each category. Of the 78 visual fields in these five categories combined, 52 (67%) were inferior defects. Inferior defect is the most typical TED-CON-associated visual field change. While the OHTS categories are geared toward classification of glaucomatous patterns, the overall predominance of inferior field defects in TED-CON was clearly demonstrated. These "other" visual field changes showing central inferior defect up to but not crossing the horizontal meridian and not contiguous from blind spot to nasal meridian should be designated as "TED-CON pattern." The high proportion of visual fields falling under the "other" category, however, does demonstrate the need for a more specific and tailored visual field classification system for TED-CON.

  4. Visual field

    Science.gov (United States)

    Perimetry; Tangent screen exam; Automated perimetry exam; Goldmann visual field exam; Humphrey visual field exam ... Confrontation visual field exam. This is a quick and basic check of the visual field. The health care provider ...

  5. Use of optical coherence tomography to evaluate visual acuity and visual field changes in dengue fever.

    Science.gov (United States)

    Rhee, Taek Kwan; Han, Jung Il

    2014-02-01

    Dengue fever is a viral disease that is transmitted by mosquitoes and affects humans. In rare cases, dengue fever can cause visual impairment, which usually occurs within 1 month after contracting dengue fever and ranges from mild blurring of vision to severe blindness. Visual impairment due to dengue fever can be detected through angiography, retinography, optical coherence tomography (OCT) imaging, electroretinography, event electroencephalography (visually evoked potentials), and visual field analysis. The purpose of this study is to report changes in the eye captured using fluorescein angiography, indocyanine green, and OCT in 3 cases of dengue fever visual impairment associated with consistent visual symptoms and similar retinochoroidopathic changes. The OCT results of the three patients with dengue fever showed thinning of the outer retinal layer and disruption of the inner segment/outer segment (IS/OS) junction. While thinning of the retina outer layer is an irreversible process, disruption of IS/OS junction is reported to be reversible. Follow-up examination of individuals with dengue fever and associated visual impairment should involve the use of OCT to evaluate visual acuity and visual field changes in patients with acute choroidal ischemia.

  6. Visual cortex in aging and Alzheimer’s disease: Changes in visual field maps and population receptive fields

    Directory of Open Access Journals (Sweden)

    Alyssa A. Brewer

    2014-02-01

    Full Text Available Although several studies have suggested that cortical alterations underlie such age-related visual deficits as decreased acuity, little is known about what changes actually occur in visual cortex during healthy aging. Two recent studies showed changes in primary visual cortex (V1 during normal aging; however, no studies have characterized the effects of aging on visual cortex beyond V1, important measurements both for understanding the aging process and for comparison to changes in age-related diseases. Similarly, there is almost no information about changes in visual cortex in Alzheimer’s disease (AD, the most common form of dementia. Because visual deficits are often reported as one of the first symptoms of AD, measurements of such changes in the visual cortex of AD patients might improve our understanding of how the visual system is affected by neurodegeneration as well as aid early detection, accurate diagnosis and timely treatment of AD. Here we use fMRI to first compare the visual field map (VFM organization and population receptive fields (pRFs between young adults and healthy aging subjects for occipital VFMs V1, V2, V3, and hV4. Healthy aging subjects do not show major VFM organizational deficits, but do have reduced surface area and increased pRF sizes in the foveal representations of V1, V2, and hV4 relative to healthy young control subjects. These measurements are consistent with behavioral deficits seen in healthy aging. We then demonstrate the feasibility and first characterization of these measurements in two patients with mild AD, which reveal potential changes in visual cortex as part of the pathophysiology of AD. Our data aid in our understanding of the changes in the visual processing pathways in normal aging and provide the foundation for future research into earlier and more definitive detection of AD.

  7. Long term changes in the visual fields of patients with temporal lobe epilepsy using vigabatrin

    NARCIS (Netherlands)

    Hardus, P; Verduin, WM; Postma, G; Stilma, JS; Berendschot, TTJM; van Veelen, CWM

    Aim-To study the long term changes in the concentric contraction of the visual field in patients with temporal lobe epilepsy on vigabatrin medication. Methods-Repeated Goldmann visual field examinations were compared in 27 patients with drug resistant temporal lobe epilepsy and concentric

  8. Learning to Recognize Patterns: Changes in the Visual Field with Familiarity

    Science.gov (United States)

    Bebko, James M.; Uchikawa, Keiji; Saida, Shinya; Ikeda, Mitsuo

    1995-01-01

    Two studies were conducted to investigate changes which take place in the visual information processing of novel stimuli as they become familiar. Japanese writing characters (Hiragana and Kanji) which were unfamiliar to two native English speaking subjects were presented using a moving window technique to restrict their visual fields. Study time for visual recognition was recorded across repeated sessions, and with varying visual field restrictions. The critical visual field was defined as the size of the visual field beyond which further increases did not improve the speed of recognition performance. In the first study, when the Hiragana patterns were novel, subjects needed to see about half of the entire pattern simultaneously to maintain optimal performance. However, the critical visual field size decreased as familiarity with the patterns increased. These results were replicated in the second study with more complex Kanji characters. In addition, the critical field size decreased as pattern complexity decreased. We propose a three component model of pattern perception. In the first stage a representation of the stimulus must be constructed by the subject, and restricting of the visual field interferes dramatically with this component when stimuli are unfamiliar. With increased familiarity, subjects become able to reconstruct a previous representation from very small, unique segments of the pattern, analogous to the informativeness areas hypothesized by Loftus and Mackworth [J. Exp. Psychol., 4 (1978) 565].

  9. The visual development of hand-centered receptive fields in a neural network model of the primate visual system trained with experimentally recorded human gaze changes

    OpenAIRE

    Galeazzi, Juan M.; Navajas, Joaquin; Mender, Bedeho M. W.; Quian Quiroga, Rodrigo; Minini, Loredana; Stringer, Simon M.

    2016-01-01

    ABSTRACT Neurons have been found in the primate brain that respond to objects in specific locations in hand-centered coordinates. A key theoretical challenge is to explain how such hand-centered neuronal responses may develop through visual experience. In this paper we show how hand-centered visual receptive fields can develop using an artificial neural network model, VisNet, of the primate visual system when driven by gaze changes recorded from human test subjects as they completed a jigsaw....

  10. Obstacle Avoidance Behaviour during Locomotion: Strategy Changes as a Result of Visual Field Limitations

    NARCIS (Netherlands)

    Jansen, S.E.M.

    2012-01-01

    In order to walk through structured surroundings without colliding with any obstacles or parts of that environment, humans rely for the most part on the visual system. Therefore, impairment in the acquisition of visual information poses a threat to efficient and save locomotion through structured

  11. The visual development of hand-centered receptive fields in a neural network model of the primate visual system trained with experimentally recorded human gaze changes.

    Science.gov (United States)

    Galeazzi, Juan M; Navajas, Joaquín; Mender, Bedeho M W; Quian Quiroga, Rodrigo; Minini, Loredana; Stringer, Simon M

    2016-01-01

    Neurons have been found in the primate brain that respond to objects in specific locations in hand-centered coordinates. A key theoretical challenge is to explain how such hand-centered neuronal responses may develop through visual experience. In this paper we show how hand-centered visual receptive fields can develop using an artificial neural network model, VisNet, of the primate visual system when driven by gaze changes recorded from human test subjects as they completed a jigsaw. A camera mounted on the head captured images of the hand and jigsaw, while eye movements were recorded using an eye-tracking device. This combination of data allowed us to reconstruct the retinal images seen as humans undertook the jigsaw task. These retinal images were then fed into the neural network model during self-organization of its synaptic connectivity using a biologically plausible trace learning rule. A trace learning mechanism encourages neurons in the model to learn to respond to input images that tend to occur in close temporal proximity. In the data recorded from human subjects, we found that the participant's gaze often shifted through a sequence of locations around a fixed spatial configuration of the hand and one of the jigsaw pieces. In this case, trace learning should bind these retinal images together onto the same subset of output neurons. The simulation results consequently confirmed that some cells learned to respond selectively to the hand and a jigsaw piece in a fixed spatial configuration across different retinal views.

  12. Changes in cortical grey matter density associated with long-standing retinal visual field defects

    NARCIS (Netherlands)

    Boucard, Christine C.; Hernowo, Aditya T.; Maguire, R. Paul; Jansonius, Nomdo M.; Roerdink, Jos B.T.M.; Hooymans, Johanna M.M.; Cornelissen, Frans W.

    Retinal lesions caused by eye diseases such as glaucoma and age-related macular degeneration can, over time, eliminate stimulation of parts of the visual cortex. This could lead to degeneration of inactive cortical neuronal tissue, but this has not been established in humans. Here, we used magnetic

  13. Can Probability Maps of Swept-Source Optical Coherence Tomography Predict Visual Field Changes in Preperimetric Glaucoma?

    Science.gov (United States)

    Lee, Won June; Kim, Young Kook; Jeoung, Jin Wook; Park, Ki Ho

    2017-12-01

    To determine the usefulness of swept-source optical coherence tomography (SS-OCT) probability maps in detecting locations with significant reduction in visual field (VF) sensitivity or predicting future VF changes, in patients with classically defined preperimetric glaucoma (PPG). Of 43 PPG patients, 43 eyes were followed-up on every 6 months for at least 2 years were analyzed in this longitudinal study. The patients underwent wide-field SS-OCT scanning and standard automated perimetry (SAP) at the time of enrollment. With this wide-scan protocol, probability maps originating from the corresponding thickness map and overlapped with SAP VF test points could be generated. We evaluated the vulnerable VF points with SS-OCT probability maps as well as the prevalence of locations with significant VF reduction or subsequent VF changes observed in the corresponding damaged areas of the probability maps. The vulnerable VF points were shown in superior and inferior arcuate patterns near the central fixation. In 19 of 43 PPG eyes (44.2%), significant reduction in baseline VF was detected within the areas of structural change on the SS-OCT probability maps. In 16 of 43 PPG eyes (37.2%), subsequent VF changes within the areas of SS-OCT probability map change were observed over the course of the follow-up. Structural changes on SS-OCT probability maps could detect or predict VF changes using SAP, in a considerable number of PPG eyes. Careful comparison of probability maps with SAP results could be useful in diagnosing and monitoring PPG patients in the clinical setting.

  14. Changes in glance behaviour when using a visual eco-driving system - A field study.

    Science.gov (United States)

    Ahlstrom, Christer; Kircher, Katja

    2017-01-01

    While in-vehicle eco-driving support systems have the potential to reduce greenhouse gas emissions and save fuel, they may also distract drivers, especially if the system makes use of a visual interface. The objective of this study is to investigate the visual behaviour of drivers interacting with such a system, implemented on a five-inch screen mounted above the middle console. Ten drivers participated in a real-world, on-road driving study where they drove a route nine times (2 pre-baseline drives, 5 treatment drives, 2 post-baseline drives). The route was 96 km long and consisted of rural roads, urban roads and a dual-lane motorway. The results show that drivers look at the system for 5-8% of the time, depending on road type, with a glance duration of about 0.6 s, and with 0.05% long glances (>2s) per kilometre. These figures are comparable to what was found for glances to the speedometer in this study. Glance behaviour away from the windscreen is slightly increased in treatment as compared to pre- and post-baseline, mirror glances decreased in treatment and post-baseline compared to pre-baseline, and speedometer glances increased compared to pre-baseline. The eco-driving support system provided continuous information interspersed with additional advice pop-ups (announced by a beep) and feedback pop-ups (no auditory cue). About 20% of sound initiated advice pop-ups were disregarded, and the remaining cases were usually looked at within the first two seconds. About 40% of the feedback pop-ups were disregarded. The amount of glances to the system immediately before the onset of a pop-up was clearly higher for feedback than for advice. All in all, the eco-driving support system under investigation is not likely to have a strong negative impact on glance behaviour. However, there is room for improvements. We recommend that eco-driving information is integrated with the speedometer, that optional activation of sound alerts for intermittent information is made

  15. Intraocular pressure and visual field changes in normal-tension glaucoma patients treated using either unoprostone or latanoprost: a prospective comparative study.

    Science.gov (United States)

    Takemoto, Daisuke; Higashide, Tomomi; Saito, Yoshiaki; Ohkubo, Shinji; Udagawa, Sachiko; Takeda, Hisashi; Sugiyama, Kazuhisa

    2017-01-01

    We conducted a prospective study in patients with normal-tension glaucoma (NTG) who received either isopropyl unoprostone or latanoprost. We compared the drugs in terms of their effects on intraocular pressure (IOP) and visual field loss progression over a 3-year period. Prospective, randomized controlled study. We enrolled 48 patients with newly diagnosed NTG at Kanazawa University Hospital. Eligible patients were randomly allocated (1:1) to receive either unoprostone or latanoprost ophthalmic solutions. The primary outcomes were IOP changes and visual field deterioration within 36 months. Visual field changes were analyzed: the cumulative survival rates were calculated in terms of mean deviation, pattern standard deviation, and total deviation of the upper or lower hemi-visual field, each visual field sector, and guided progression analysis. In addition, we evaluated the progression of glaucomatous optic disc changes using fundus photography and confocal scanning laser ophthalmoscopy. The mean pretreatment IOP was 15.0±2.4 mmHg in the Unoprostone group and 15.2±1.9 mmHg in the Latanoprost group. The mean IOP during the treatment period was 13.7±2.3 mmHg in the Unoprostone group and 13.0±1.8 mmHg in the Latanoprost group. In both groups, the IOP decreased significantly (pvisual field loss progression, there were no significant differences between groups in any parameters of the visual field or guided progression analysis. There were no significant differences between groups in disc changes. No significant differences were found between groups with regard to the visual field and structural progression in patients with NTG, although unoprostone was less effective than latanoprost in lowering the IOP.

  16. [Do patients undergo changes of their personality due to visual field defects? An investigation with FPI-R and NEI-VQ].

    Science.gov (United States)

    Jobke, S; Kasten, E; Sabel, B A

    2008-06-01

    Visual restrictions can lead to anxiety and possibly to social retirement. Therefore it makes sense to assess the patients' degree of handicap. The goal of the present study was to investigate if patients show changes in their personality or a reduced quality of life as a result of their visual field defect. 15 patients with visual field defects were asked to fill out the revised version of the Freiburger Persönlichkeitsinventar (FPI-R) and the National Eye Institute Visual Function Questionnaire (NEI-VFQ). The FPI-R encompasses the standardised recording of many personality traits whereas the NEI-VFQ addresses the visual quality of life. In the total sample all FPI-R scales were appropriate for the study in the inconspicuous standard range. Slight shifts resulted toward increased willingness to make contacts (scale 4, ST 4.2), reduced physical strain (scale 7, ST 4.3) and lower physical discomfort (scale 8, ST 3.7). The size of the visual field defect does not correlate with the satisfaction with life, with the physical discomfort and with the state of health but with the dependency on others (p = 0.047) and with the exertion of their social roles (p = 0.043). The scale "satisfaction with life" of the FPI-R correlated with the scale "psychic condition" of the NEI-VFQ (p = 0.028) and the physical discomfort showed a significant correlation with the scale "eye strain" (p = 0.006) in the NEI-VFQ. Contrary to our presumptions, patients with visual field defects did not show any changes in their personality. It is supposed that they have learned to compensate for their reduced visual functions.

  17. 38 CFR 4.77 - Visual fields.

    Science.gov (United States)

    2010-07-01

    ... DISABILITIES Disability Ratings The Organs of Special Sense § 4.77 Visual fields. (a) Examination of visual... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Visual fields. 4.77... who are well adapted to intraocular lens implant or contact lens correction, visual field examinations...

  18. Visual field changes as an early indicator of glioblastoma multiforme progression: two cases of functional vision changes before MRI detection

    Directory of Open Access Journals (Sweden)

    Xie K

    2015-06-01

    Full Text Available Kate Xie,1,* Catherine Y Liu,1,* Anton N Hasso,2 Robert Wade Crow1 1Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA, USA, 2Department of Radiological Sciences, University of California Irvine Medical Center, Orange, CA, USA *These authors contributed equally to this work Abstract: Glioblastoma multiforme is an aggressive tumor associated with a high rate of recurrence even after maximal therapy. In a disease with poor prognosis and rapid deterioration, early detection of tumor progression is necessary to make timely treatment decisions or to initiate end of life care. We identify two cases where Humphrey visual field testing predated magnetic resonance imaging and positron emission tomography findings of tumor progression by months in glioblastoma multiforme. New or worsening visual field defects may indicate signs of tumor progression in glioblastoma multiforme and should prompt further investigation. Keywords: glioblastoma multiforme, optic pathway, visual field defects

  19. Prism therapy and visual rehabilitation in homonymous visual field loss.

    LENUS (Irish Health Repository)

    O'Neill, Evelyn C

    2011-02-01

    Homonymous visual field defects (HVFD) are common and frequently occur after cerebrovascular accidents. They significantly impair visual function and cause disability particularly with regard to visual exploration. The purpose of this study was to assess a novel interventional treatment of monocular prism therapy on visual functioning in patients with HVFD of varied etiology using vision targeted, health-related quality of life (QOL) questionnaires. Our secondary aim was to confirm monocular and binocular visual field expansion pre- and posttreatment.

  20. A computational theory of visual receptive fields.

    Science.gov (United States)

    Lindeberg, Tony

    2013-12-01

    A receptive field constitutes a region in the visual field where a visual cell or a visual operator responds to visual stimuli. This paper presents a theory for what types of receptive field profiles can be regarded as natural for an idealized vision system, given a set of structural requirements on the first stages of visual processing that reflect symmetry properties of the surrounding world. These symmetry properties include (i) covariance properties under scale changes, affine image deformations, and Galilean transformations of space-time as occur for real-world image data as well as specific requirements of (ii) temporal causality implying that the future cannot be accessed and (iii) a time-recursive updating mechanism of a limited temporal buffer of the past as is necessary for a genuine real-time system. Fundamental structural requirements are also imposed to ensure (iv) mutual consistency and a proper handling of internal representations at different spatial and temporal scales. It is shown how a set of families of idealized receptive field profiles can be derived by necessity regarding spatial, spatio-chromatic, and spatio-temporal receptive fields in terms of Gaussian kernels, Gaussian derivatives, or closely related operators. Such image filters have been successfully used as a basis for expressing a large number of visual operations in computer vision, regarding feature detection, feature classification, motion estimation, object recognition, spatio-temporal recognition, and shape estimation. Hence, the associated so-called scale-space theory constitutes a both theoretically well-founded and general framework for expressing visual operations. There are very close similarities between receptive field profiles predicted from this scale-space theory and receptive field profiles found by cell recordings in biological vision. Among the family of receptive field profiles derived by necessity from the assumptions, idealized models with very good qualitative

  1. OCT and Visual Field Changes as Useful Markers for Follow-up of Axonal Loss in Multiple Sclerosis in Egyptian Patients.

    Science.gov (United States)

    Khalil, Dalia H; Said, Mohamed M; Abdelhakim, Mohamad Amr Salah Eddin; Labeeb, Dalia M

    2017-06-01

    The aim of this work was to correlate optical coherence tomography (OCT) parameters, retinal sensitivity (perimetry) and best-corrected visual acuity (BCVA) with disease duration and neurologic functional disability in Egyptian patients with multiple sclerosis (MS). This is a cross-sectional observational cohort study in which 68 MS patients and 23 healthy controls had full neurologic examination, including expanded disability status scale (EDSS) and full ophthalmologic examination, including functional and structural assessments of the optic nerve through BCVA, visual field examination (SITA), and OCT (Optovue). Retinal nerve fiber layer (RNFL) thickness was significantly decreased in MS eyes. MS eyes had significantly decreased GCC. RNFL thickness was significantly negatively correlated to EDSS and disease duration. GCC was significantly negatively correlated to disease duration. BCVA and retinal sensitivity (MD) were significantly correlated to the MS duration. OCT is a promising tool to detect subclinical changes in RNFL and GCC in Egyptian patients with MS.

  2. The visual light field in real scenes

    NARCIS (Netherlands)

    Xia, L.; Pont, S.C.; Heynderickx, I.E.J.R.

    2014-01-01

    Human observers’ ability to infer the light field in empty space is known as the “visual light field.” While most relevant studies were performed using images on computer screens, we investigate the visual light field in a real scene by using a novel experimental setup. A “probe” and a scene were

  3. COMPARISON OF RNFL THICKNESS AND VISUAL FIELD CHANGES BETWEEN DIABETIC WITHOUT RETINOPATHY AND NONDIABETIC CONTROLS- A CROSS-SECTIONAL STUDY

    Directory of Open Access Journals (Sweden)

    Soumya Swarup Chattopadhyay

    2017-10-01

    Full Text Available BACKGROUND Diabetes mellitus is one of the major component of metabolic syndrome and a leading cause of ocular morbidity in modern era and India will be considered to be the diabetes capital of the world. Before the onset of diabetic retinopathy, other structural and functional changes may predict the visual diminution of the individual. MATERIALS AND METHODS In this cross-sectional study in a tertiary care hospital, after inclusion and exclusion, the age-gender matched groups (diagnosed type 2 diabetes patients without diabetic retinopathy and controls without diabetes were thoroughly examined clinically and by noninvasive and invasive examination (after proper counselling of the patient and informed consent. Then, they are tested for functional loss of retina by Humphrey FDT, GDx VCC. Comparison done between cases and controls as well as poorly-controlled and well-controlled diabetic groups. RESULTS It was found that the average RNFL thickness was significantly reduced in diabetics (mean 53.48, SD 2.69 compared to controls (mean 60.21, SD 1.87 (p7%, the RNFL thickness was significantly reduced (mean 52.23, SD 1.31 compared to diabetics with good metabolic control (mean 56.38, SD 2.92 (p<0.05. In retinal functional testing, it was found that the Humphrey FDT mean deviation (FDT MD and pattern standard deviation (FDT PSD were significantly worse in diabetics (FDT MD- 1.478, SD 0.386, (FDT PSD- 3.485, SD 0.403 compared to normal controls (FDT MD- 0.442, SD 0.536, (FDT PSD- 1.438, SD 0.404. The parameters were also found to be significantly worse in uncontrolled diabetics (p<0.05. CONCLUSION To conclude, without diabetic retinopathy, functional and structural loss in retina in diabetes patients compared to age-sex matched individual and especially in poorly-controlled diabetes should be of concern as there are no detectable vasculopathy. So, early diagnosis and control of diabetes is advocated to control this functional loss

  4. Prism therapy and visual rehabilitation in homonymous visual field loss.

    LENUS (Irish Health Repository)

    O'Neill, Evelyn C

    2012-02-01

    PURPOSE: Homonymous visual field defects (HVFD) are common and frequently occur after cerebrovascular accidents. They significantly impair visual function and cause disability particularly with regard to visual exploration. The purpose of this study was to assess a novel interventional treatment of monocular prism therapy on visual functioning in patients with HVFD of varied etiology using vision targeted, health-related quality of life (QOL) questionnaires. Our secondary aim was to confirm monocular and binocular visual field expansion pre- and posttreatment. METHODS: Twelve patients with acquired, documented HVFD were eligible to be included. All patients underwent specific vision-targeted, health-related QOL questionnaire and monocular and binocular Goldmann perimetry before commencing prism therapy. Patients were fitted with monocular prisms on the side of the HVFD with the base-in the direction of the field defect creating a peripheral optical exotropia and field expansion. After the treatment period, QOL questionnaires and perimetry were repeated. RESULTS: Twelve patients were included in the treatment group, 10 of whom were included in data analysis. Overall, there was significant improvement within multiple vision-related, QOL functioning parameters, specifically within the domains of general health (p < 0.01), general vision (p < 0.05), distance vision (p < 0.01), peripheral vision (p < 0.05), role difficulties (p < 0.05), dependency (p < 0.05), and social functioning (p < 0.05). Visual field expansion was shown when measured monocularly and binocularly during the study period in comparison with pretreatment baselines. CONCLUSIONS: Patients with HVFD demonstrate decreased QOL. Monocular sector prisms can improve the QOL and expand the visual field in these patients.

  5. Diagnostic accuracy of confrontation visual field tests.

    Science.gov (United States)

    Kerr, N M; Chew, S S L; Eady, E K; Gamble, G D; Danesh-Meyer, H V

    2010-04-13

    To determine the diagnostic accuracy of confrontation visual field testing and to compare the accuracy of confrontation tests both individually and in combination. Patients were prospectively recruited from ophthalmology clinics over a 6-month period. All patients underwent SITA-standard 24-2 Humphrey visual field analysis. Two examiners, masked to the automated perimetry results and the results of the other examiner, assessed patients using 7 common confrontation visual field tests. The order of testing was randomized to reduce any learning effect. For each individual test and combination of tests, the sensitivity, specificity, positive predictive value, and negative predictive value were calculated. A total of 301 eyes from 163 patients were included in the study. The average mean deviation was -5.91 +/- 7.72 (SD) dB. Most confrontation tests were insensitive to the identification of field loss. The sensitivity and specificity varied depending on the type, density, and cause of the visual field defect. Kinetic testing with a red target provided the highest sensitivity (74.4%) and specificity (93.0%) of any individual test and when combined with static finger wiggle testing achieved a sensitivity of 78.3% while retaining a specificity of 90.1%. Confrontation visual field tests are insensitive at detecting visual field loss when performed individually and are therefore a poor screening test. Combining confrontation tests is a simple and practical method of improving the sensitivity of confrontation testing.

  6. Influence of hemianopic visual field loss on visual motor control.

    Directory of Open Access Journals (Sweden)

    Diederick C Niehorster

    Full Text Available Homonymous hemianopia (HH is an anisotropic visual impairment characterized by the binocular inability to see one side of the visual field. Patients with HH often misperceive visual space. Here we investigated how HH affects visual motor control.Seven patients with complete HH and no neglect or cognitive decline and seven gender- and age-matched controls viewed displays in which a target moved randomly along the horizontal or the vertical axis. They used a joystick to control the target movement to keep it at the center of the screen. We found that the mean deviation of the target position from the center of the screen along the horizontal axis was biased toward the blind side for five out of seven HH patients. More importantly, while the normal vision controls showed more precise control and larger response amplitudes when the target moved along the horizontal rather than the vertical axis, the control performance of the HH patients was not different between these two target motion experimental conditions.Compared with normal vision controls, HH affected patients' control performance when the target moved horizontally (i.e., along the axis of their visual impairment rather than vertically. We conclude that hemianopia affects the use of visual information for online control of a moving target specific to the axis of visual impairment. The implications of the findings for driving in hemianopic patients are discussed.

  7. Visual fields in a chloroquine treatment

    Directory of Open Access Journals (Sweden)

    García-Domene MC

    2014-09-01

    Full Text Available María del Carmen García-Domene,1,2 María Amparo Díez-Ajenjo,1,3 María Dolores de Fez,4 María José Luque2 1Fisabio Oftalmología Médica, València, 2Departament d'Òptica, Facultat de Física, Universitat de València, Burjassot, 3Clínica Optométrica Fundación Lluís Alcanyís, Valencia, 4Departamento de Óptica, Farmacología y Anatomía, Universidad de Alicante, Alicante, SpainPurpose: In this study, we describe contrast sensitivity losses in the visual field of a patient affected by chloroquine toxicity, measured with stimuli favoring different visual mechanisms. We have compared these results with those of other, usual clinical tests.Methods: The vision of a patient who underwent ten years of chloroquine treatment was analyzed by a battery of clinical tests: visual acuity (VA, Amsler's grid, Farnsworth–Munsell 100-hue test, spectral domain optical coherence tomography, multifocal electroretinogram (ERG, white-on-white and red-on-white Humphrey perimetries, chromatic and achromatic contrast sensitivity perimetry tests, and fluorescein angiography. Measurements were taken just before the cessation of the treatment, and 6 months later.Results: The subjective visual perception of the patient was worse (in comparison with the rest of the visual field at the time of the first visit in the center of the visual field, and was impaired on the second visit. Although standard automated perimetry (SAP was practically normal and ERG results did not worsen with time, VA, Amsler's grid, and visual fields with stimuli favoring the magnocellular and chromatic pathways signalled progressive loss of visual function.Conclusions: Standard tests such as SAP or ERG may not detect visual field losses or progression of existing visual losses in a case of chloroquine toxicity, whereas tests evaluating contrast sensitivity with stimuli favoring different visual mechanisms may be more sensitive.Keywords: visual field, chloroquine, retinal toxicity, retinal

  8. Functional visual fields: relationship of visual field areas to self-reported function.

    Science.gov (United States)

    Subhi, Hikmat; Latham, Keziah; Myint, Joy; Crossland, Michael D

    2017-07-01

    The aim of this study is to relate areas of the visual field to functional difficulties to inform the development of a binocular visual field assessment that can reflect the functional consequences of visual field loss. Fifty-two participants with peripheral visual field loss undertook binocular assessment of visual fields using the 30-2 and 60-4 SITA Fast programs on the Humphrey Field Analyser, and mean thresholds were derived. Binocular visual acuity, contrast sensitivity and near reading performance were also determined. Self-reported overall and mobility function were assessed using the Dutch ICF Activity Inventory. Greater visual field loss (0-60°) was associated with worse self-reported function both overall (R2 = 0.50; p function (R2 = 0.61, p function in multiple regression analyses. Superior and inferior visual field areas related similarly to mobility function (R2 = 0.56, p function in multiple regression analysis. Mean threshold of the binocular visual field to 60° eccentricity is a good predictor of self-reported function overall, and particularly of mobility function. Both the central (0-30°) and peripheral (30-60°) mean threshold are good predictors of self-reported function, but the peripheral (30-0°) field is a slightly better predictor of mobility function, and should not be ignored when considering functional consequences of field loss. The inferior visual field is a slightly stronger predictor of perceived overall and mobility function than the superior field. © 2017 The Authors Ophthalmic & Physiological Optics © 2017 The College of Optometrists.

  9. [The development of a computer-based visual field analyzer].

    Science.gov (United States)

    Yang, D; Hou, W; Peng, C; Mou, Y

    2000-09-01

    Visual field is one of the important visual functions; it is the extent of the visual field defect that can be employed in judging whether the visual function is impaired. The rapid achievements in computer technologies do provide an impulse for improvement of visual field detection, making possible the automatic, rapid, accurate, detailed and large-scaled visual field detection. This paper gives a thorough description about development of the visual field analyzer, model TEC-2A, which is based on PC windows platform, Visual Basic software developing tool, ISA peripheral circuits, standard Goldmann visual field half-ball and standard stimulus.

  10. Remaining visual field and preserved subjective visual functioning prevent mental distress in patients with visual field defects

    Directory of Open Access Journals (Sweden)

    Carolin eGall

    2013-09-01

    Full Text Available Background: Patients with visual field defects after visual pathway lesion may experience reduced vision-related quality of life (vrQoL. It has not been clarified how vrQoL impairments contribute to vision-related mental distress.Methods: 108 subjects with visual field defects caused by optic neuropathies (age M=57.6; SD=13.7 years answered the National Eye Institute Visual-Functioning Questionnaire (NEI-VFQ for vrQoL and the SF-12 Short Form Health Survey for health-related quality of life (hrQoL. A ten item composite of NEI-VFQ visual functioning and five items of mental health symptoms due to vision problems were subjected to Rasch analysis. The test battery comprised static and High Resolution Perimetry (HRP. Regression and path analysis were used to investigate associations between QoL, mental distress and perimetry results.Results: A higher level of visual functioning was associated with monocular impairment and a larger remaining visual field compared to binocular impairment. Subjective visual functioning but not visual field parameters predicted mental health symptoms due to vision problems which was the only variable associated with the SF-12 mental component score. The SF-12 physical component score was less strongly associated with mental health symptoms due to vision problems. Here, reaction time in HRP and mean threshold in perimetry were additional significant variables. Path analysis revealed a significant path of remaining visual field via visual functioning on mental health. Conclusions: Subjective consequences of visual impairments in everyday life impact mental health rather than objective visual function loss as measured by perimetry. Since a higher extent of vrQoL was related to lower levels of mental distress, the maintenance of vrQoL could reduce and prevent mental distress due to vision problems. Patients with persisting visual field defects may benefit from neuropsychological rehabilitation and supportive therapies.

  11. Visualization and processing of tensor fields

    CERN Document Server

    Weickert, Joachim

    2007-01-01

    Presents information on the visualization and processing of tensor fields. This book serves as an overview for the inquiring scientist, as a basic foundation for developers and practitioners, and as a textbook for specialized classes and seminars for graduate and doctoral students.

  12. Change in vision, visual disability, and health after cataract surgery.

    Science.gov (United States)

    Helbostad, Jorunn L; Oedegaard, Maria; Lamb, Sarah E; Delbaere, Kim; Lord, Stephen R; Sletvold, Olav

    2013-04-01

    Cataract surgery improves vision and visual functioning; the effect on general health is not established. We investigated if vision, visual functioning, and general health follow the same trajectory of change the year after cataract surgery and if changes in vision explain changes in visual disability and general health. One-hundred forty-eight persons, with a mean (SD) age of 78.9 (5.0) years (70% bilateral surgery), were assessed before and 6 weeks and 12 months after surgery. Visual disability and general health were assessed by the CatQuest-9SF and the Short Formular-36. Corrected binocular visual acuity, visual field, stereo acuity, and contrast vision improved (P visual acuity evident up to 12 months (P = 0.034). Cataract surgery had an effect on visual disability 1 year later (P visual disability and general health 6 weeks after surgery. Vision improved and visual disability decreased in the year after surgery, whereas changes in general health and visual functioning were short-term effects. Lack of associations between changes in vision and self-reported disability and general health suggests that the degree of vision changes and self-reported health do not have a linear relationship.

  13. [Relationship between visual field index and visual field morphological stages of glaucoma and their diagnostic value].

    Science.gov (United States)

    Hou, X R; Qin, J Y; Ren, Z Q

    2017-02-11

    Objective: To investigate the rationality of visual field morphological stages of glaucoma, its relationship with visual field index and their diagnostic value. Methods: Retrospective series case study. Two hundred and seventy-four glaucoma patients and 100 normal control received visual field examination by Humphrey perimeter using standard automatic perimetry (SAP) program from March 2014 to September 2014. Glaucoma patients were graded into four stages according to characteristic morphological damage of visual field, distribution of mean defect (MD) and visual field index (VFI) of each stage were plotted and receiver operation characteristic curve (ROC) was used to explore its correlation with MD and VFI. The diagnostic value of MD and VFI was also compared. For the comparison of general data of subjects, categorical variables were compared using χ(2) test, numerical variables were compared using F test. MD and VFI were compared using ANOVA among stages according to visual field, followed by multiple comparisons using LSD method. The correlation between MD and VFI and different stages according to visual field defined their diagnostic value, and compared using area under the curve (AUC) of ROC. Results: No characteristic visual field damage was found in normal control group, and MD and VFI was (-0.06±1.24) dB and (99.15±0.76)%, respectively. Glaucomatous visual field damage was graded into early, medium, late and end stage according to morphological characteristic. MD for each stage were (-2.83±2.00) dB, (-9.70±3.68) dB, (-18.46±2.90) dB, and (-27.96±2.76) dB, respectively. VFI for each stage were (93.84±3.61)%, (75.16±10.85)%, (49.36±11.26)% and (17.65±10.59)%, respectively. MD and VFI of each stage of glaucomatous group and normal control group were all significantly different (F=1 165.53 and PAUC(MD) (P<0.05). Conclusions: It is feasible and rational of glaucomatous visual field damage to be graded into early, medium, late and end stage using

  14. Tensor Field Visualization in Geomechanics Applications

    Science.gov (United States)

    Hotz, I.; Feng, L.; Hamann, B.; Joy, K.; Manaker, D.; Billen, M. I.; Kellogg, L. H.

    2004-12-01

    Scalar and vector fields, and especially tensor fields like stress and strain tensor fields, play an important role in the study of geophysics, including earthquakes. For example, time-varying tensor data result from modeling the behavior of bending plates. Application areas we focus on are concerned with a better understanding of bending phenomena in rocks, in the Earth's lithosphere, and in subducting slabs. The associated mathematical models and numerical simulations generate stress and strain data that are tensors. Tensors contain so much information and related components in each point that it is not easy to capture and visualize all information. Typically, researchers plot cross-sections or maps of individual components, which do not allow a view of all the information included in models or observational data. Therefore, it is important to provide scientists with an overview of an entire tensor field. We have developed a tensor field visualization method tailored specifically to the class of tensor fields exhibiting properties similar to stress and strain tensors, which are commonly encountered in geophysics/geomechanics. These tensor fields are characterized by the property that they have positive and negative eigenvalues. The sign of the eigenvalues indicates regions of expansion and compression. To understand field behavior visually, it is important to express these features in an intuitive way. Our technique is a global method providing an overview of an entire tensor field by using a continuous representation. The main idea it to represent a tensor field as a ``texture-deforming operator,'' which resembles deforming a piece of fabric to express the characteristic properties of a tensor field. The texture is stretched or compressed and bended according to the physical meaning of the tensor field. Large positive eigenvalues, which indicate tension, are illustrated by a texture with low density or a stretched piece of fabric. For negative eigenvalues

  15. Testing of visual field with virtual reality goggles in manual and visual grasp modes.

    Science.gov (United States)

    Wroblewski, Dariusz; Francis, Brian A; Sadun, Alfredo; Vakili, Ghazal; Chopra, Vikas

    2014-01-01

    Automated perimetry is used for the assessment of visual function in a variety of ophthalmic and neurologic diseases. We report development and clinical testing of a compact, head-mounted, and eye-tracking perimeter (VirtualEye) that provides a more comfortable test environment than the standard instrumentation. VirtualEye performs the equivalent of a full threshold 24-2 visual field in two modes: (1) manual, with patient response registered with a mouse click, and (2) visual grasp, where the eye tracker senses change in gaze direction as evidence of target acquisition. 59 patients successfully completed the test in manual mode and 40 in visual grasp mode, with 59 undergoing the standard Humphrey field analyzer (HFA) testing. Large visual field defects were reliably detected by VirtualEye. Point-by-point comparison between the results obtained with the different modalities indicates: (1) minimal systematic differences between measurements taken in visual grasp and manual modes, (2) the average standard deviation of the difference distributions of about 5 dB, and (3) a systematic shift (of 4-6 dB) to lower sensitivities for VirtualEye device, observed mostly in high dB range. The usability survey suggested patients' acceptance of the head-mounted device. The study appears to validate the concepts of a head-mounted perimeter and the visual grasp mode.

  16. Testing of Visual Field with Virtual Reality Goggles in Manual and Visual Grasp Modes

    Directory of Open Access Journals (Sweden)

    Dariusz Wroblewski

    2014-01-01

    Full Text Available Automated perimetry is used for the assessment of visual function in a variety of ophthalmic and neurologic diseases. We report development and clinical testing of a compact, head-mounted, and eye-tracking perimeter (VirtualEye that provides a more comfortable test environment than the standard instrumentation. VirtualEye performs the equivalent of a full threshold 24-2 visual field in two modes: (1 manual, with patient response registered with a mouse click, and (2 visual grasp, where the eye tracker senses change in gaze direction as evidence of target acquisition. 59 patients successfully completed the test in manual mode and 40 in visual grasp mode, with 59 undergoing the standard Humphrey field analyzer (HFA testing. Large visual field defects were reliably detected by VirtualEye. Point-by-point comparison between the results obtained with the different modalities indicates: (1 minimal systematic differences between measurements taken in visual grasp and manual modes, (2 the average standard deviation of the difference distributions of about 5 dB, and (3 a systematic shift (of 4–6 dB to lower sensitivities for VirtualEye device, observed mostly in high dB range. The usability survey suggested patients’ acceptance of the head-mounted device. The study appears to validate the concepts of a head-mounted perimeter and the visual grasp mode.

  17. Systematic variation of population receptive field properties across cortical depth in human visual cortex

    NARCIS (Netherlands)

    Fracasso, Alessio; Petridou, N; Dumoulin, Serge O

    2016-01-01

    Receptive fields (RFs) in visual cortex are organized in antagonistic, center-surround, configurations. RF properties change systematically across eccentricity and between visual field maps. However, it is unknown how center-surround configurations are organized in human visual cortex across lamina.

  18. Adaptive Gaze Strategies for Locomotion with Constricted Visual Field

    Directory of Open Access Journals (Sweden)

    Colas N. Authié

    2017-07-01

    Full Text Available In retinitis pigmentosa (RP, loss of peripheral visual field accounts for most difficulties encountered in visuo-motor coordination during locomotion. The purpose of this study was to accurately assess the impact of peripheral visual field loss on gaze strategies during locomotion, and identify compensatory mechanisms. Nine RP subjects presenting a central visual field limited to 10–25° in diameter, and nine healthy subjects were asked to walk in one of three directions—straight ahead to a visual target, leftward and rightward through a door frame, with or without obstacle on the way. Whole body kinematics were recorded by motion capture, and gaze direction in space was reconstructed using an eye-tracker. Changes in gaze strategies were identified in RP subjects, including extensive exploration prior to walking, frequent fixations of the ground (even knowing no obstacle was present, of door edges, essentially of the proximal one, of obstacle edge/corner, and alternating door edges fixations when approaching the door. This was associated with more frequent, sometimes larger rapid-eye-movements, larger movements, and forward tilting of the head. Despite the visual handicap, the trajectory geometry was identical between groups, with a small decrease in walking speed in RPs. These findings identify the adaptive changes in sensory-motor coordination, in order to ensure visual awareness of the surrounding, detect changes in spatial configuration, collect information for self-motion, update the postural reference frame, and update egocentric distances to environmental objects. They are of crucial importance for the design of optimized rehabilitation procedures.

  19. MODELLING SYNERGISTIC EYE MOVEMENTS IN THE VISUAL FIELD

    Directory of Open Access Journals (Sweden)

    BARITZ Mihaela

    2015-06-01

    Full Text Available Some theoretical and practical considerations about eye movements in visual field are presented in the first part of this paper. These movements are developed into human body to be synergistic and are allowed to obtain the visual perception in 3D space. The theoretical background of the eye movements’ analysis is founded on the establishment of movement equations of the eyeball, as they consider it a solid body with a fixed point. The exterior actions, the order and execution of the movements are ensured by the neural and muscular external system and thus the position, stability and movements of the eye can be quantified through the method of reverse kinematic. The purpose of these researches is the development of a simulation model of human binocular visual system, an acquisition methodology and an experimental setup for data processing and recording regarding the eye movements, presented in the second part of the paper. The modeling system of ocular movements aims to establish the binocular synergy and limits of visual field changes in condition of ocular motor dysfunctions. By biomechanical movements of eyeball is established a modeling strategy for different sort of processes parameters like convergence, fixation and eye lens accommodation to obtain responses from binocular balance. The results of modelling processes and the positions of eye ball and axis in visual field are presented in the final part of the paper.

  20. NEW DEFINITIONS OF KINETIC VISUAL ACUITY AND KINETIC VISUAL FIELD AND THEIR AGING EFFECTS

    Directory of Open Access Journals (Sweden)

    Jinglong WU

    2009-01-01

    However, traditional kinetic visual acuity and kinetic visual field measurements do not factor in the effects of individual differences in simple reaction times. This study identifies problems with the traditional method employed to define kinetic visual acuity and kinetic visual fields, and proposes new definitions of kinetic visual acuity and kinetic visual fields that measure simple reaction times and their aging effects. Simple reaction time tests reveal that simple reaction times of senior citizens are longer than those of younger people. The results of appraisal tests between traditional and new kinetic visual acuity definitions demonstrate the appropriateness of the new kinetic visual acuity definition. The study also takes a quantitative look at the aging effects of kinetic visual fields, measuring kinetic visual field characteristics of senior citizens while assessing space dependence, light dependence and index speed dependence of young people. The results obtained show that kinetic visual field ranges decrease with age, particularly in upward visual fields rather than downward visual fields in all target conditions. Visual field angle reductions in the temple sides of upward visual fields were of particular note.

  1. The four-meter confrontation visual field test.

    Science.gov (United States)

    Kodsi, S R; Younge, B R

    1992-01-01

    The 4-m confrontation visual field test has been successfully used at the Mayo Clinic for many years in addition to the standard 0.5-m confrontation visual field test. The 4-m confrontation visual field test is a test of macular function and can identify small central or paracentral scotomas that the examiner may not find when the patient is tested only at 0.5 m. Also, macular sparing in homonymous hemianopias and quadrantanopias may be identified with the 4-m confrontation visual field test. We recommend use of this confrontation visual field test, in addition to the standard 0.5-m confrontation visual field test, on appropriately selected patients to obtain the most information possible by confrontation visual field tests. PMID:1494829

  2. Rapid progressive visual decline and visual field defects in two patients with the Heidenhain variant of Creutzfeld-Jakob disease.

    Science.gov (United States)

    Lenk, Janine; Engellandt, Kay; Terai, Naim; Bottesi, Antonia; Matthé, Egbert

    2018-02-08

    Heidenhain variant of Creutzfeldt-Jakob (HvCJD) is a rare disease, patients presenting with loss of visual acuity and a decline in visual fields. Two patients with rapid loss of visual acuity and declining visual fields presented with homonymic hemianopsia over several weeks. Cranial MRI showed neither stroke nor other morphological changes explaining the severe visual field defects. Neurological examination revealed no pathologies. However, lumbar puncture showed an increase in total protein in cerebrospinal fluid (CSF). Visual field testing revealed further deterioration during follow-up. Several weeks later, patients' behaviour changed markedly, exhibiting aggression, declining memory function and physical degeneration. The suspected diagnosis was the Heidenhain variant of Creutzfeld-Jakob disease (HvCJD). CSF analysis showed evidence of PrP Sc and 14-3-3 protein. Both patients died within 8 weeks of the CJD diagnosis. Loss of visual acuity and a decline in visual fields without corresponding MRI findings and marked changes in behaviour should lead to a diagnosis of HvCJD. Corresponding diagnostic tests should be performed for confirmation. The prognosis for survival is poor and should be immediately communicated to affected patients and their relatives. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. The role of the retino-colliculo-extrastriate pathway in visual awareness and visual field recovery.

    Science.gov (United States)

    Bertini, Caterina; Grasso, Paolo A; Làdavas, Elisabetta

    2016-09-01

    Patients with visual field defects resulting from post-chiasmatic lesions experience loss of visual function in up to one half of their visual field, with consequent impairments in their daily life activities. Therefore, effective strategies for compensating for the visual field loss are of great clinical relevance. After lesions to the primary visual pathway -which conveys visual information from the retina to the lateral geniculate nucleus, the optic radiations and, then, to the striate cortex-an alternative visual pathway, which projects from the superior colliculus to the extrastriate cortex, is usually spared in patients with visual field defects. In the present review, evidence for spared functioning of this alternative pathway in patients with visual field defects will be presented, both in terms of residual visual abilities, without awareness, for stimuli presented in the blind field, and the ability to integrate unseen visual signals presented in the blind field with concurrent auditory stimuli. Crucially, this review will discuss how the spared retino-colliculo-extrastriate pathway might be a useful tool for compensating for the loss of visual perception. Accordingly, evidence for the compensatory effects of systematic multisensory audio-visual stimulation in patients with visual field defects will be reviewed. Copyright © 2016. Published by Elsevier Ltd.

  4. Position matching between the visual fields in strabismus.

    Science.gov (United States)

    Hussain, Zahra; Astle, Andrew T; Webb, Ben S; McGraw, Paul V

    2018-01-01

    The misalignment of visual input in strabismus disrupts positional judgments. We measured positional accuracy in the extrafoveal visual field (1°-7° eccentricity) of a large group of strabismic subjects and a normal control group to identify positional distortions associated with the direction of strabismus. Subjects performed a free localization task in which targets were matched in opposite hemifields whilst fixating on a central cross. The constant horizontal error of each response was taken as a measure of accuracy, in addition to radial and angular error. In monocular conditions, all stimuli were viewed by one eye; thus, the error reflected spatial bias. In dichoptic conditions, the targets were seen by separate eyes; thus, the error reflected the perceived stimulus shift produced by ocular misalignment in addition to spatial bias. In both viewing conditions, both groups showed reliable over- and underestimations of visual field position, here termed a compression of response coordinates. The normal group showed compression in the left periphery, regardless of eye of stimulation. The strabismic group showed a visual field-specific compression that was clearly associated with direction of strabismus. The variation in perceived shift of strabismic subjects was largely accounted for by the biases present in monocular viewing, suggesting that binocular correspondence was uniform in the tested region. The asymmetric strabismic compression could not be reproduced in normal subjects through prism viewing, and its presence across viewing conditions suggests a hemifield-specific change in spatial coding induced by long-standing ocular misalignment.

  5. Confrontation visual field testing in routine ophthalmic practice ...

    African Journals Online (AJOL)

    Background: Visual field testing, aids in detecting, localizing and monitoring diseases of the visual pathway. Early detection may help to preserve the patient's sight or life. In some situations, standard perimetry may not be possible. Aim: To highlight the relevance of confrontation visual field testing (CVF) in routine ...

  6. Individual differences in visual field shape modulate the effects of attention on the lower visual field advantage in crowding.

    Science.gov (United States)

    Fortenbaugh, Francesca C; Silver, Michael A; Robertson, Lynn C

    2015-02-12

    It has previously been reported that visual crowding of a target by flankers is stronger in the upper visual field than in the lower, and this finding has been attributed to greater attentional resolution in the lower hemifield (He, Cavanagh, & Intriligator, 1996). Here we show that the upper/lower asymmetry in visual crowding can be explained by natural variations in the borders of each individual's visual field. Specifically, asymmetry in crowding along the vertical meridian can be almost entirely accounted for by replacing the conventional definition of visual field location, in units of degrees of visual angle, with a definition based on the ratio of the extents of an individual's upper and lower visual field. We also show that the upper/lower crowding asymmetry is eliminated when stimulus eccentricity is expressed in units of percentage of visual field extent but is present when the conventional measure of visual angle is used. We further demonstrate that the relationship between visual field extent and perceptual asymmetry is most evident when participants are able to focus their attention on the target location. These results reveal important influences of visual field boundaries on visual perception, even for visual field locations far from those boundaries. © 2015 ARVO.

  7. Central visual field, visual acuity, and sudden visual loss after glaucoma surgery.

    Science.gov (United States)

    Levene, R Z

    1992-06-01

    The relationship between Snellen visual acuity and central visual field loss as determined by the Humphrey 10-degree test was examined in 96 glaucomatous eyes of 79 patients. The severity of the field defect was determined by the number of affected quadrants, defined as a sensitivity loss of at least 10 decibels from normal at the most central point of 1.4-degree eccentricity. The decrease in median acuity was gradual, one-half line per quadrant for one and two affected quadrants, and an additional one and one-half line to two lines for three and four quadrants. Loss of acuity was disproportionate when both temporal quadrants were affected. The major source of error was difficulty with fixation. One type, a prolonged fixation shift, was not related to short-term fixation losses. There was a significant correlation between acuity and foveal threshold over a wide range of both variables. Sudden visual loss from additional optic nerve damage was studied retrospectively in 96 eyes with advanced glaucoma and a central field defect. A frequency of 3% for any loss of visual acuity and a frequency of 1% for a loss to 20/200 or worse were noted. There were no apparent predictive factors.

  8. Enhanced visual fields in hammerhead sharks.

    Science.gov (United States)

    McComb, D M; Tricas, T C; Kajiura, S M

    2009-12-01

    Several factors that influence the evolution of the unusual head morphology of hammerhead sharks (family Sphyrnidae) are proposed but few are empirically tested. In this study we tested the 'enhanced binocular field' hypothesis (that proposes enhanced frontal binocularity) by comparison of the visual fields of three hammerhead species: the bonnethead shark, Sphyrna tiburo, the scalloped hammerhead shark, Sphyrna lewini, and the winghead shark, Eusphyra blochii, with that of two carcharhinid species: the lemon shark, Negaprion brevirostris, and the blacknose shark, Carcharhinus acronotus. Additionally, eye rotation and head yaw were quantified to determine if species compensate for large blind areas anterior to the head. The winghead shark possessed the largest anterior binocular overlap (48 deg.) and was nearly four times larger than that of the lemon (10 deg.) and blacknose (11 deg.) sharks. The binocular overlap in the scalloped hammerhead sharks (34 deg.) was greater than the bonnethead sharks (13 deg.) and carcharhinid species; however, the bonnethead shark did not differ from the carcharhinids. These results indicate that binocular overlap has increased with lateral head expansion in hammerhead sharks. The hammerhead species did not demonstrate greater eye rotation in the anterior or posterior direction. However, both the scalloped hammerhead and bonnethead sharks exhibited greater head yaw during swimming (16.9 deg. and 15.6 deg., respectively) than the lemon (15.1 deg.) and blacknose (15.0 deg.) sharks, indicating a behavioral compensation for the anterior blind area. This study illustrates the larger binocular overlap in hammerhead species relative to their carcharhinid sister taxa and is consistent with the 'enhanced binocular field' hypothesis.

  9. Lateralized occipital degeneration in posterior cortical atrophy predicts visual field deficits

    Directory of Open Access Journals (Sweden)

    Rebecca S Millington

    2017-01-01

    Conclusions: Detailed brain imaging shows that the asymmetric visual field deficits in patients with PCA reflect the pattern of degeneration of both white and gray matter in the occipital lobe. Understanding the nature of both visual field deficits and the neurodegenerative brain changes in PCA may improve diagnosis and understanding of this disease.

  10. Alterations of color vision and central visual field in patients with Vogt-Koyanagi-Harada syndrome.

    Science.gov (United States)

    Yang, Peizeng; Sun, Min; Liu, Xiaoli; Zhou, Hongyan; Fang, Wang; Wang, Li; Kijlstra, Aize

    2012-06-01

    To investigate the changes of color vision and central visual field in a cohort of patients with Vogt-Koyanagi-Harada (VKH) syndrome. Sixteen VKH patients (32 eyes) were enrolled in this study. All the patients were treated with immunosuppressive agents. The best visual acuity, visual field testing and color vision testing were available from the records in all these patients at different time points, i.e. before treatment and 1 month (±7 days), 3 months (±15 days), 6 months (±20 days) and 12 months (±30 days) after treatment. All patients showed active intraocular inflammation at their first visit. A decreased visual acuity, abnormality of color vision and abnormal visual field were observed at presentation. Visual acuity and color vision rapidly improved at 1 and 3 months and gradually improved thereafter. Visual field defects significantly improved at 6 months and gradually improved thereafter. However, visual field defects were still observed in 27.5% of the tested patients following a 12-month treatment. Color vision returned to the normal level only in about one-third of these patients at this time point. Visual function was severely impaired in VKH patients with active uveitis but rapidly improved following immunosuppressive therapy. Visual fields are much more severely affected by the disease than visual acuity and its improvement lagged behind that of visual acuity and color vision.

  11. Central Field Index Versus Visual Field Index for Central Visual Function in Stable Glaucoma.

    Science.gov (United States)

    Rao, Aparna; Padhy, Debananda; Mudunuri, Harika; Roy, Avik K; Sarangi, Sarada P; Das, Gopinath

    2017-01-01

    To compare the variability of central field index (CFI) versus visual field index (VFI) in stable glaucoma with central fixation involvement. For this retrospective study, we identified multiple visual fields (VFs) of patients with repeatable central fixation involvement on Humphrey VFs (24-2 and 10-2 program) which were stable (clinically and on VFs) over a very short period of 2 to 3 months. The VFI and CFI were calculated as described in earlier reports. We graded the fields as early [mean deviation (MD)>-6 dB], moderate (-6.1 to -12 dB), and severe glaucoma (glaucoma was compared. Relation of the divergence to field indices and clinical parameters were assessed. The intervisit difference for VFI was greater than CFI ranging from -4% to 9% versus -1% to 8% in early (P=0.9), -13% to 18% versus -6% to 17% (P=0.056) in moderate, and -21% to 19% versus -9% to 9% (Pglaucoma. The CFI within each group had narrower range than VFI with maximum range in severe glaucoma (33% to 95%). The divergence of CFI from VFI started at MD 24-2 beyond (worse) -10 dB. This difference between CFI and VFI was associated significantly with number of points with Pglaucoma indicating need for incorporating CFI calculation for monitoring advanced disease in eyes with central defects.

  12. Contralesional Trunk Rotation Dissociates Real vs. Pseudo-Visual Field Defects due to Visual Neglect in Stroke Patients.

    Science.gov (United States)

    Nyffeler, Thomas; Paladini, Rebecca E; Hopfner, Simone; Job, Oliver; Nef, Tobias; Pflugshaupt, Tobias; Vanbellingen, Tim; Bohlhalter, Stephan; Müri, René M; Kerkhoff, Georg; Cazzoli, Dario

    2017-01-01

    In stroke patients, the clinical presentation of visual field defects (VFDs) is frequently accompanied by visual neglect, i.e., the inability to attend and respond to the contralesional space. However, the diagnostic discrimination between the lack of reactions to contralesional stimuli due to VFDs or visual neglect is challenging during clinical examination. This discrimination is particularly relevant, since both clinical pictures are associated with different therapeutic approaches and outcomes. The aim of this study was to systematically investigate the effectiveness of trunk rotation toward the contralesional side-a manipulation dissociating the coordinate system of the trunk from that of the head and eyes-in disentangling real VFDs from "pseudo-VFDs" that occur due to visual neglect. Twenty patients with a left-sided VFD after a right-hemispheric stroke (10 additionally showing visual neglect in neuropsychological testing, VFD + neglect; 10 without neglect, VFD) were tested with Goldmann perimetry in both standard and trunk rotation conditions. In the standard condition, both VFD and VFD + neglect patients showed a conspicuous narrowing of the left visual field. However, trunk rotation triggered strikingly different patterns of change in the two groups: it elicited a significant increase in visual field extension in the VFD + neglect group, but left visual field extension virtually unchanged in the VFD group. Our results highlight contralesional trunk rotation as a simple, viable manipulation to effectively and rapidly disentangle real VFDs from "pseudo-VFDs" (i.e., due to visual neglect) during clinical examination.

  13. The four-meter confrontation visual field test.

    OpenAIRE

    Kodsi, S R; Younge, B R

    1992-01-01

    The 4-m confrontation visual field test has been successfully used at the Mayo Clinic for many years in addition to the standard 0.5-m confrontation visual field test. The 4-m confrontation visual field test is a test of macular function and can identify small central or paracentral scotomas that the examiner may not find when the patient is tested only at 0.5 m. Also, macular sparing in homonymous hemianopias and quadrantanopias may be identified with the 4-m confrontation visual field test....

  14. Age-dependent cortical thinning of peripheral visual field representations in primary visual cortex

    Directory of Open Access Journals (Sweden)

    Joseph Caleb Griffis

    2016-10-01

    Full Text Available The cerebral cortex changes throughout the lifespan, and the cortical grey matter in many brain regions becomes thinner with advancing age. Effects of aging on cortical thickness have been observed in many brain regions, including areas involved in basic perceptual functions such as processing visual inputs. An important property of early visual cortices is their topographic organization – the cortical structure of early visual areas forms a topographic map of retinal inputs. Primary visual cortex (V1 is considered to be the most basic cortical area in the visual processing hierarchy, and is topographically organized from posterior (central visual representation to anterior (peripheral visual representation along the calcarine sulcus. Some studies have reported strong age-dependent cortical thinning in portions of V1 that likely correspond to peripheral visual representations, while there is less evidence of substantial cortical thinning in central V1. However, the effect of aging on cortical thickness in V1 as a function of its topography has not been directly investigated. To address this gap in the literature, we estimated the cortical thickness of different eccentricity sectors in V1 using T1-weighted MRI scans acquired from groups of healthy younger and older adults, and then assessed whether between-group differences in V1 cortical thickness depended on cortical eccentricity. These analyses revealed age-dependent cortical thinning specific to peripheral visual field representations in anterior portions of V1, but did not provide evidence for age-dependent cortical thinning in other portions of V1. Additional analyses found similar effects when analyses were restricted to the gyral crown, sulcul depth, and sulcul wall, indicating that these effects are not likely due to differences in gyral/sulcul contributions to our regions of interest. Importantly, this finding indicates that age-dependent changes in cortical structure may differ among

  15. The nature of the visual field, a phenomenological analysis

    NARCIS (Netherlands)

    Koenderink, Jan; van Doorn, A.J.; Wagemans, Johan

    2015-01-01

    Abstract The visual field is the spatial form of visual awareness, that is, immediate visual experience ignoring qualities and meanings. Such an entity only exists in the discursive representation, for the awareness as such is quality and meaning throughout. Thus the discursive, formal treatment is

  16. Visual advantage in deaf adults linked to retinal changes.

    Directory of Open Access Journals (Sweden)

    Charlotte Codina

    Full Text Available The altered sensory experience of profound early onset deafness provokes sometimes large scale neural reorganisations. In particular, auditory-visual cross-modal plasticity occurs, wherein redundant auditory cortex becomes recruited to vision. However, the effect of human deafness on neural structures involved in visual processing prior to the visual cortex has never been investigated, either in humans or animals. We investigated neural changes at the retina and optic nerve head in profoundly deaf (N = 14 and hearing (N = 15 adults using Optical Coherence Tomography (OCT, an in-vivo light interference method of quantifying retinal micro-structure. We compared retinal changes with behavioural results from the same deaf and hearing adults, measuring sensitivity in the peripheral visual field using Goldmann perimetry. Deaf adults had significantly larger neural rim areas, within the optic nerve head in comparison to hearing controls suggesting greater retinal ganglion cell number. Deaf adults also demonstrated significantly larger visual field areas (indicating greater peripheral sensitivity than controls. Furthermore, neural rim area was significantly correlated with visual field area in both deaf and hearing adults. Deaf adults also showed a significantly different pattern of retinal nerve fibre layer (RNFL distribution compared to controls. Significant correlations between the depth of the RNFL at the inferior-nasal peripapillary retina and the corresponding far temporal and superior temporal visual field areas (sensitivity were found. Our results show that cross-modal plasticity after early onset deafness may not be limited to the sensory cortices, noting specific retinal adaptations in early onset deaf adults which are significantly correlated with peripheral vision sensitivity.

  17. Balance in Parkinson's disease patients changing the visual input.

    Science.gov (United States)

    Suarez, Hamlet; Geisinger, Dario; Ferreira, Enrique D; Nogueira, Santiago; Arocena, Sofia; Roman, Cecilia San; Suarez, Alejo

    2011-01-01

    The description of the postural responses in Parkinson's disease patients when visual information changes from a stable to a moving visual field analyzing the impact on balance in these patients. Limits of Stability, Body center of pressure and balance functional reserve were measured by means of the force platform in 24 Parkinson's patients in stages 1 and 2 of the Boher classification and 19 volunteers as a control group. Both groups were stimulated with 1-Static visual field and 2-horizontal optokinetic stimulation using a virtual reality system. Postural responses were analyzed using the inverted pendulum as mathematical model. While the control group didn't show significant differences on the postural control between the two sensory conditions (COP p=0.0017, BFR p=0.0025), Parkinson's patients presented significant differences in the area of the center of pressure and the balance functional reserve values between static visual field and optokinetic stimulation. (COP p=0.0017, BFR p=0.0025). The results support the hypothesis about the influence of the changes in the visual information in triggering balance control disorders in Parkinson's patients. It is discussed the interest of these fact in the assessment and the rehabilitation programs of this disease.

  18. 21 CFR 886.1360 - Visual field laser instrument.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Visual field laser instrument. 886.1360 Section 886.1360 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1360 Visual field laser instrument...

  19. Early auditory change detection implicitly facilitated by ignored concurrent visual change during a Braille reading task.

    Science.gov (United States)

    Aoyama, Atsushi; Haruyama, Tomohiro; Kuriki, Shinya

    2013-09-01

    Unconscious monitoring of multimodal stimulus changes enables humans to effectively sense the external environment. Such automatic change detection is thought to be reflected in auditory and visual mismatch negativity (MMN) and mismatch negativity fields (MMFs). These are event-related potentials and magnetic fields, respectively, evoked by deviant stimuli within a sequence of standard stimuli, and both are typically studied during irrelevant visual tasks that cause the stimuli to be ignored. Due to the sensitivity of MMN/MMF to potential effects of explicit attention to vision, however, it is unclear whether multisensory co-occurring changes can purely facilitate early sensory change detection reciprocally across modalities. We adopted a tactile task involving the reading of Braille patterns as a neutral ignore condition, while measuring magnetoencephalographic responses to concurrent audiovisual stimuli that were infrequently deviated either in auditory, visual, or audiovisual dimensions; 1000-Hz standard tones were switched to 1050-Hz deviant tones and/or two-by-two standard check patterns displayed on both sides of visual fields were switched to deviant reversed patterns. The check patterns were set to be faint enough so that the reversals could be easily ignored even during Braille reading. While visual MMFs were virtually undetectable even for visual and audiovisual deviants, significant auditory MMFs were observed for auditory and audiovisual deviants, originating from bilateral supratemporal auditory areas. Notably, auditory MMFs were significantly enhanced for audiovisual deviants from about 100 ms post-stimulus, as compared with the summation responses for auditory and visual deviants or for each of the unisensory deviants recorded in separate sessions. Evidenced by high tactile task performance with unawareness of visual changes, we conclude that Braille reading can successfully suppress explicit attention and that simultaneous multisensory changes can

  20. Field dependence in visually and nonvisually involved learning disabled children.

    Science.gov (United States)

    Cowen, R J; Harway, N I

    1976-08-01

    39 visually and nonvisually perceptually impaired 8- to 11-yr.-old boys with learning disabilities were compared with a control group of 35 "normal" learners on the Rod-and-frame and Children's Embedded-figures Tests. Previous findings of greater field dependence of learning disabled children are confounded because the experimental tasks involved visual perception. In our study the 27 "visuals" were more field-dependent than either the 12 "nonvisuals" or the controls. The latter groups did not differ significantly from one another, which may in part be a function of the small sample of nonvisual children identified. Alternative explanations, e.g., the visual nature of the field-dependence measures and the lack of reading difficulty of the nonvisual group, are considered. For the visually disabled Ss only Vocabulary scores, suggesting that among such children those with higher verbal intelligence may be more field-independent.

  1. Microprolactinoma with visual field defect: An unsuspected etiology

    Directory of Open Access Journals (Sweden)

    K. V. S. Hari Kumar

    2013-01-01

    Full Text Available Microprolactinomas present usually with menstrual disturbance and galactorrhoea. The presence of visual field defects is not expected in these patients as the tumor does not involve structures outside the sella. Visual field defects in a case of microprolactinoma confuse the clinician and warrant extensive search for an alternate etiology. We present a young lady with microprolactinoma and visual field defects. Etiological work-up revealed a diagnosis of idiopathic intracranial hypertension (IIH associated with microprolactinoma. Treatment with Acetazolamide and Cabergoline completely resolved the clinical symptoms and visual defects. The unusual occurrence of IIH in a case of microprolactinoma as the cause of visual field defect is highlighted in our case report.

  2. Visual field constriction caused by colored contact lenses.

    Science.gov (United States)

    Insler, M S; Hendricks, C; George, D M

    1988-12-01

    Goldmann visual field testing was performed on ten patients while they were wearing the recently released DuraSoft 3 colored soft contact lenses. All patients but one had visual field constriction ranging from 5 degrees to 20 degrees. When the areas inside the three tested isopters were averaged, the amount of field loss ranged from 21% to 47%. Contact lens fitters as well as wearers should be warned of this potential complication.

  3. Change in vision, visual disability, and health after cataract surgery

    National Research Council Canada - National Science Library

    Helbostad, Jorunn L; Oedegaard, Maria; Lamb, Sarah E; Delbaere, Kim; Lord, Stephen R; Sletvold, Olav

    2013-01-01

    .... We investigated if vision, visual functioning, and general health follow the same trajectory of change the year after cataract surgery and if changes in vision explain changes in visual disability and general health...

  4. TACO: Visualizing Changes in Tables Over Time.

    Science.gov (United States)

    Niederer, Christina; Stitz, Holger; Hourieh, Reem; Grassinger, Florian; Aigner, Wolfgang; Streit, Marc

    2017-08-29

    Multivariate, tabular data is one of the most common data structures used in many different domains. Over time, tables can undergo changes in both structure and content, which results in multiple versions of the same table. A challenging task when working with such derived tables is to understand what exactly has changed between versions in terms of additions/deletions, reorder, merge/split, and content changes. For textual data, a variety of commonplace "diff" tools exist that support the task of investigating changes between revisions of a text. Although there are some comparison tools which assist users in inspecting differences between multiple table instances, the resulting visualizations are often difficult to interpret or do not scale to large tables with thousands of rows and columns. To address these challenges, we developed TACO, an interactive comparison tool that visualizes the differences between multiple tables at various levels of detail. With TACO we show (1) the aggregated differences between multiple table versions over time, (2) the aggregated changes between two selected table versions, and (3) detailed changes between the selected tables. To demonstrate the effectiveness of our approach, we show its application by means of two usage scenarios.

  5. Detailed illustration of the visual field representation along the visual pathway to the primary visual cortex: a graphical summary.

    Science.gov (United States)

    Wärntges, Simone; Michelson, Georg

    2014-01-01

    In the literature, different graphic illustrations are available, which depict different parts of the visual pathway in relation to visual field sectors, to retinal sectors, the layers of the lateral geniculate nucleus (LGN), or sections of the primary visual cortex (V1). However, a complete overview is missing, which may be useful for a more precise differentiation of predominantly ophthalmological from intracerebral diseases. It may also be of interest to investigate additional intracerebral reasons that are involved in impaired vision of largely unknown pathophysiology. This work combines the scientific knowledge of partial graphics in one detailed illustration that allows exact follow-up of the neuronal connections from individual visual field sectors to the V1 areas. A selective search for peer-reviewed graphics of the visual pathway was performed in PubMed and Google Pictures. Sixteen different visual field sectors and their 16 corresponding retinal sectors were set in relation to 64 LGN sections and 20 areas of V1. Segmented cross-sectional areas of the optic nerve supplemented the graphical representation of the fiber orientation in relation to the visual field. The detailed illustration of the visual field projection along the visual pathway structures may facilitate a more precise calculation of correlations between morphological and functional measurements of ophthalmological and neuroradiological examinations. © 2013 S. Karger AG, Basel.

  6. Preoperative visual field deficits in temporal lobe epilepsy

    Directory of Open Access Journals (Sweden)

    Sanjeet S. Grewal

    2017-01-01

    Full Text Available Surgical resection and laser thermoablation have been used to treat drug resistant epilepsy with good results. However, they are not without risk. One of the most commonly reported complications of temporal lobe surgery is contralateral superior homonymous quadrantanopsia. We describe a patient with asymptomatic preoperative quadrantanopsia fortuitously discovered as part of our recently modified protocol to evaluate patients prior to temporal lobe epilepsy surgery. This visual field deficit was subtle and not detected on routine clinical neurological examination. While we understand that this is a single case, we advocate further study for more detailed preoperative visual field examinations to characterize the true incidence of postoperative visual field lesions.

  7. Large Field Visualization with Demand-Driven Calculation

    Science.gov (United States)

    Moran, Patrick J.; Henze, Chris

    1999-01-01

    We present a system designed for the interactive definition and visualization of fields derived from large data sets: the Demand-Driven Visualizer (DDV). The system allows the user to write arbitrary expressions to define new fields, and then apply a variety of visualization techniques to the result. Expressions can include differential operators and numerous other built-in functions, ail of which are evaluated at specific field locations completely on demand. The payoff of following a demand-driven design philosophy throughout becomes particularly evident when working with large time-series data, where the costs of eager evaluation alternatives can be prohibitive.

  8. Radial asymmetries in population receptive field size and cortical magnification factor in early visual cortex.

    Science.gov (United States)

    Silva, Maria Fatima; Brascamp, Jan W; Ferreira, Sónia; Castelo-Branco, Miguel; Dumoulin, Serge O; Harvey, Ben M

    2017-11-14

    Human visual cortex does not represent the whole visual field with the same detail. Changes in receptive field size, population receptive field (pRF) size and cortical magnification factor (CMF) with eccentricity are well established, and associated with changes in visual acuity with eccentricity. Visual acuity also changes across polar angle. However, it remains unclear how RF size, pRF size and CMF change across polar angle. Here, we examine differences in pRF size and CMF across polar angle in V1, V2 and V3 using pRF modeling of human fMRI data. In these visual field maps, we find smaller pRFs and larger CMFs in horizontal (left and right) than vertical (upper and lower) visual field quadrants. Differences increase with eccentricity, approximately in proportion to average pRF size and CMF. Similarly, we find larger CMFs in the lower than upper quadrant, and again differences increase with eccentricity. However, pRF size differences between lower and upper quadrants change direction with eccentricity. Finally, we find slightly smaller pRFs in the left than right quadrants of V2 and V3, though this difference is very small, and we find no differences in V1 and no differences in CMF. Moreover, differences in pRF size and CMF vary gradually with polar angle and are not limited to the meridians or visual field map discontinuities. PRF size and CMF differences do not consistently follow patterns of cortical curvature, despite the link between cortical curvature and polar angle in V1. Thus, the early human visual cortex has a radially asymmetric representation of the visual field. These asymmetries may underlie consistent reports of asymmetries in perceptual abilities. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Visual verification of linac light and radiation fields coincidence.

    Science.gov (United States)

    Monti, Angelo F; Frigerio, Milena; Frigerio, Giovanna

    2003-01-01

    X-ray and light field alignment evaluation is carried out during linac quality assurance programs. In this paper, we compare the size of the light field measured by a photodiode and by a more traditional visual observation with the size of the x-ray field. The comparison between actual light field size, measured with the photodiode, and light field size measured by human eye allow us to verify the reliability of human eye in the evaluation of this parameter. The visual field is always larger than real light field; however, it agrees better with the x-ray field. It matches the light field if we take into account the 25% (+/- 1%) of the decrement line of the maximum central lightening; however, this method simulates better the actual field employed in radiation treatments.

  10. Visual Responses in FEF, Unlike V1, Primarily Reflect When the Visual Context Renders a Receptive Field Salient.

    Science.gov (United States)

    Joiner, Wilsaan M; Cavanaugh, James; Wurtz, Robert H; Cumming, Bruce G

    2017-10-11

    When light falls within a neuronal visual receptive field (RF) the resulting activity is referred to as the visual response. Recent work suggests this activity is in response to both the visual stimulation and the abrupt appearance, or salience, of the presentation. Here we present a novel method for distinguishing the two, based on the timing of random and nonrandom presentations. We examined these contributions in frontal eye field (FEF; N = 51) and as a comparison, an early stage in the primary visual cortex (V1; N = 15) of male monkeys (Macaca mulatta). An array of identical stimuli was presented within and outside the neuronal RF while we manipulated salience by varying the time between stimulus presentations. We hypothesized that the rapid presentation would reduce salience (the sudden appearance within the visual field) of a stimulus at any one location, and thus decrease responses driven by salience in the RF. We found that when the interstimulus interval decreased from 500 to 16 ms there was an approximate 79% reduction in the FEF response compared with an estimated 17% decrease in V1. This reduction in FEF response for rapid presentation was evident even when the random sequence preceding a stimulus did not stimulate the RF for 500 ms. The time course of these response changes in FEF suggest that salience is represented much earlier (visual system.SIGNIFICANCE STATEMENT The neuronal responses in early visual processing [e.g., primary visual cortex (V1)] reflect primarily the retinal stimulus. Processing in higher visual areas is modulated by a combination of the visual stimulation and contextual factors, such as salience, but identifying these components separately has been difficult. Here we quantified these contributions at a late stage of visual processing [frontal eye field (FEF)] and as a comparison, an early stage in V1. Our results suggest that as visual information continues through higher levels of processing the neural responses are no longer

  11. Visual Field Measurement with Motion Sensitivity Screening Test in ...

    African Journals Online (AJOL)

    Eye disease is a frequent complication of onchocerciasis in countrise where the disease is highly endemic. It has been shown that early ocular lesions which manifest as visual field defects or reduction in visual acuity can be reversed following treatment with ivermectin. At the community level, it is important to detect ...

  12. Visual field screening with a laptop computer system.

    Science.gov (United States)

    Bruun-Jensen, Jørgen

    2011-09-01

    The aim of this study was to develop a visual field screening system and investigate the importance of using 2 different programs for visual field screening to be used in places in which other perimeters are yet not available. The system consists of a laptop computer with instructions for the patient displayed on the screen and additional equipment to ensure central eye position, eye distance to the screen, optimal optical correction, and light intensity. This visual field screening system combines a screening program consisting of 68 test points with the highest density in areas of high prevalence of visual defects, followed by a supplementary program comprising 82 other test points in a quadratic lattice pattern. The system was compared with Octopus 1-2-3 threshold perimetry, and the applicability of the system when operated by optometrists was evaluated. In the glaucoma clinic at the University Hospital, Rigshospitalet, Denmark, the screening program was used to investigate 98 patients (173 eyes) and to compare the results with those of the Octopus Perimetry Program dG2. The sensitivity of the system was 100% and the specificity was 78%. Subsequently, 18 optometrists in different locations in Denmark tested 1,022 patients (2,036 eyes). Patients contacted these optometrists because of the presence of refractive error, subjective vision problems, or eye symptoms. The screening was used as a part of a routine examination. In 432 eyes (21%), visual defects were detected using the screening program. By re-examining 349 eyes, with the addition of the supplementary program consisting of 82 other test points in a quadratic lattice pattern, the visual field defects were not reproduced in 263 eyes, a reduction of primary positive visual field defects by 75%. The additional supplementary program was not conducted with 38 eyes (2%) because of large visual field defects, high intraocular pressures, cataract, positive family history of glaucoma, lack of time, or poor patient

  13. Progression of visual field defects in leber hereditary optic neuropathy: experience of the LHON treatment trial.

    Science.gov (United States)

    Newman, Nancy J; Biousse, Valérie; Newman, Steven A; Bhatti, M Tariq; Hamilton, Steven R; Farris, Bradley K; Lesser, Robert L; Turbin, Roger E

    2006-06-01

    To describe the visual fields of patients with Leber hereditary optic neuropathy (LHON), a maternally inherited disorder characterized by bilateral, often sequential vision loss, before and during progressive visual deterioration. Prospective longitudinal follow-up of serial visual fields in patients enrolled onto an open-label, nonrandomized pilot study of topical brimonidine purite as prophylactic treatment after first eye involvement in LHON. Nine molecularly confirmed primary mutation patients with LHON with monocular vision loss for less than six months and normal visual function in the other eye were followed prospectively for up to two years. Visual fields were performed on automated perimetry at baseline and on many follow-up visits. Despite normal visual acuity at baseline in all patients, seven patients had some minimal changes in the central visual field of the second eye. All patients had subsequent deterioration of visual acuity, mean deviation, and foveal sensitivity in their second eye. The earliest pattern of abnormality was typically a cecocentral defect enlarging to become a central defect, often with a superior or inferior predilection. The visual field defects in the two eyes of any given patient were remarkably similar. LHON may be a bilateral condition at onset more frequently than appreciated. Automated static perimetry of the "normal" eye may reveal subclinical findings that typically worsen rapidly over weeks to months to similar central scotomatous damage. Quantitative automated static perimetry is helpful in elucidating the natural history of LHON and in understanding the underlying pathology and pathophysiology of this disease.

  14. Corporate visual identity : Case study: changing visual identity

    OpenAIRE

    Nykänen, Heidi

    2013-01-01

    Every company has an identity, which distinguishes it from others. Corporate identity has today an important role in customers’ decision making process, because they do not only buy the product, but they also buy the company with it. Corporate visual identity is the outer side of identity. The main elements of visual identity are name, logo/symbol, colour, typography and slogan. A well designed corporate visual identity represents the company’s identity and business idea. The aim of this...

  15. Rapid confrontation screening for peripheral visual field defects and extinction.

    Science.gov (United States)

    Anderson, Andrew J; Shuey, Neil H; Wall, Michael

    2009-01-01

    Screening for unsuspected visual field defects should form a part of all routine eye examinations. Here, we review a procedure for finger-counting confrontation screening that tests the periphery of all visual field quadrants of each eye, yet requires a total of only four responses from the patient. In addition, the test simultaneously screens for the extinction phenomenon that can accompany unilateral brain damage. Due to its efficiency, we recommend that this procedure form the standard way that screening finger-counting confrontation be performed, with abnormal findings prompting a more detailed assessment of visual fields and further neurological examination as necessary. Our paper is not intended to suggest that finger-counting confrontation is superior to other forms of visual field screening and indeed the literature suggests its sensitivity is limited.

  16. Recognizing patterns of visual field loss using unsupervised machine learning.

    Science.gov (United States)

    Yousefi, Siamak; Goldbaum, Michael H; Zangwill, Linda M; Medeiros, Felipe A; Bowd, Christopher

    2014-03-21

    Glaucoma is a potentially blinding optic neuropathy that results in a decrease in visual sensitivity. Visual field abnormalities (decreased visual sensitivity on psychophysical tests) are the primary means of glaucoma diagnosis. One form of visual field testing is Frequency Doubling Technology (FDT) that tests sensitivity at 52 points within the visual field. Like other psychophysical tests used in clinical practice, FDT results yield specific patterns of defect indicative of the disease. We used Gaussian Mixture Model with Expectation Maximization (GEM), (EM is used to estimate the model parameters) to automatically separate FDT data into clusters of normal and abnormal eyes. Principal component analysis (PCA) was used to decompose each cluster into different axes (patterns). FDT measurements were obtained from 1,190 eyes with normal FDT results and 786 eyes with abnormal (i.e., glaucomatous) FDT results, recruited from a university-based, longitudinal, multi-center, clinical study on glaucoma. The GEM input was the 52-point FDT threshold sensitivities for all eyes. The optimal GEM model separated the FDT fields into 3 clusters. Cluster 1 contained 94% normal fields (94% specificity) and clusters 2 and 3 combined, contained 77% abnormal fields (77% sensitivity). For clusters 1, 2 and 3 the optimal number of PCA-identified axes were 2, 2 and 5, respectively. GEM with PCA successfully separated FDT fields from healthy and glaucoma eyes and identified familiar glaucomatous patterns of loss.

  17. How useful is visual field testing in an African glaucoma clinic?

    Science.gov (United States)

    Lenake, Mpopi; Cook, Colin; Mustak, Hamzah; Du Toit, Nagib

    2014-01-01

    To investigate the usefulness of visual field testing in the diagnosis and subsequent management of glaucoma in a specialist glaucoma clinic at Groote Schuur Hospital, Cape Town, South Africa. A retrospective case note review of 344 patients who attended the glaucoma clinic between January and June 2010. The study population consisted of 201 (58%) females and 143 (42%) males. The diagnoses included 207 (60%) cases with primary open-angle glaucoma, 58 (17%) cases with chronic angle closure glaucoma, 46 (13%) cases with secondary glaucoma, 17 (5%) cases with normal pressure glaucoma, ten (3%) cases with ocular hypertension, and six (2%) glaucoma suspects. Visual field testing contributed to the diagnosis of glaucoma in only 34 (10%) cases. A total number of 2,604 fields were performed. Of these fields, 1,931 (74%) were reliable. A baseline was reached in only 141 (53%) patients. There was evidence of field progression in only 24 (9%) cases. Changes to glaucoma treatment were based on inadequate control of intraocular pressure alone in 309 (90%) patients. Visual field progression contributed to changes in treatment in only 15 (4%) cases. Visual fields are not used in the diagnosis and management of glaucoma in the majority of patients in our clinic. Patients present with advanced disease, which is easily diagnosed without the use of visual fields. Progression of fields seldom contributes to monitoring and intraocular pressure is mainly used to monitor the adequacy of treatment.

  18. Visual Sample Plan (VSP) - FIELDS Integration

    Energy Technology Data Exchange (ETDEWEB)

    Pulsipher, Brent A.; Wilson, John E.; Gilbert, Richard O.; Hassig, Nancy L.; Carlson, Deborah K.; Bing-Canar, John; Cooper, Brian; Roth, Chuck

    2003-04-19

    Two software packages, VSP 2.1 and FIELDS 3.5, are being used by environmental scientists to plan the number and type of samples required to meet project objectives, display those samples on maps, query a database of past sample results, produce spatial models of the data, and analyze the data in order to arrive at defensible decisions. VSP 2.0 is an interactive tool to calculate optimal sample size and optimal sample location based on user goals, risk tolerance, and variability in the environment and in lab methods. FIELDS 3.0 is a set of tools to explore the sample results in a variety of ways to make defensible decisions with quantified levels of risk and uncertainty. However, FIELDS 3.0 has a small sample design module. VSP 2.0, on the other hand, has over 20 sampling goals, allowing the user to input site-specific assumptions such as non-normality of sample results, separate variability between field and laboratory measurements, make two-sample comparisons, perform confidence interval estimation, use sequential search sampling methods, and much more. Over 1,000 copies of VSP are in use today. FIELDS is used in nine of the ten U.S. EPA regions, by state regulatory agencies, and most recently by several international countries. Both software packages have been peer-reviewed, enjoy broad usage, and have been accepted by regulatory agencies as well as site project managers as key tools to help collect data and make environmental cleanup decisions. Recently, the two software packages were integrated, allowing the user to take advantage of the many design options of VSP, and the analysis and modeling options of FIELDS. The transition between the two is simple for the user – VSP can be called from within FIELDS, automatically passing a map to VSP and automatically retrieving sample locations and design information when the user returns to FIELDS. This paper will describe the integration, give a demonstration of the integrated package, and give users download

  19. Brief Novel Visual Experience Fundamentally Changes Synaptic Plasticity in the Mouse Visual Cortex.

    Science.gov (United States)

    Li, Shuo; Wang, Laijian; Tie, Xiaoxiu; Sohya, Kazuhiro; Lin, Xian; Kirkwood, Alfredo; Jiang, Bin

    2017-09-27

    LTP has been known to be a mechanism by which experience modifies synaptic responses in the neocortex. Visual deprivation in the form of dark exposure or dark rearing from birth enhances NMDAR-dependent LTP in layer 2/3 of visual cortex, a process often termed metaplasticity, which may involve changes in NMDAR subunit composition and function. However, the effects of reexposure to light after dark rearing from birth on LTP induction have not been explored. Here, we showed that the light exposure after dark rearing revealed a novel NMDAR independent form of LTP in the layer 2/3 pyramidal cells in visual cortex of mice of both sexes, which is dependent on mGluR5 activation and is associated with intracellular Ca 2+ rise, CaMKII activity, PKC activity, and intact protein synthesis. Moreover, the capacity to induce mGluR-dependent LTP is transient: it only occurs when mice of both sexes reared in the dark from birth are exposed to light for 10-12 h, and it does not occur in vision-experienced, male mice, even after prolonged exposure to dark. Thus, the mGluR5-LTP unmasked by short visual experience can only be observed after dark rearing but not after dark exposure. These results suggested that, as in hippocampus, in layer 2/3 of visual cortex, there is coexistence of two distinct activity-dependent systems of synaptic plasticity, NMDAR-LTP, and mGluR5-LTP. The mGluR5-LTP unmasked by short visual experience may play a critical role in the faster establishment of normal receptive field properties. SIGNIFICANCE STATEMENT LTP has been known to be a mechanism by which experience modifies synaptic responses in the neocortex. Visual deprivation in the form of dark exposure or dark rearing from birth enhances NMDAR-dependent LTP in layer 2/3 of visual cortex, a process often termed metaplasticity. NMDAR-dependent form of LTP in visual cortex has been well characterized. Here, we report that an NMDAR-independent form of LTP can be promoted by novel visual experience on dark

  20. Effect of Cognitive Demand on Functional Visual Field Performance in Senior Drivers with Glaucoma

    Directory of Open Access Journals (Sweden)

    Viswa Gangeddula

    2017-08-01

    Full Text Available Purpose: To investigate the effect of cognitive demand on functional visual field performance in drivers with glaucoma.Method: This study included 20 drivers with open-angle glaucoma and 13 age- and sex-matched controls. Visual field performance was evaluated under different degrees of cognitive demand: a static visual field condition (C1, dynamic visual field condition (C2, and dynamic visual field condition with active driving (C3 using an interactive, desktop driving simulator. The number of correct responses (accuracy and response times on the visual field task were compared between groups and between conditions using Kruskal–Wallis tests. General linear models were employed to compare cognitive workload, recorded in real-time through pupillometry, between groups and conditions.Results: Adding cognitive demand (C2 and C3 to the static visual field test (C1 adversely affected accuracy and response times, in both groups (p < 0.05. However, drivers with glaucoma performed worse than did control drivers when the static condition changed to a dynamic condition [C2 vs. C1 accuracy; glaucoma: median difference (Q1–Q3 3 (2–6.50 vs. controls: 2 (0.50–2.50; p = 0.05] and to a dynamic condition with active driving [C3 vs. C1 accuracy; glaucoma: 2 (2–6 vs. controls: 1 (0.50–2; p = 0.02]. Overall, drivers with glaucoma exhibited greater cognitive workload than controls (p = 0.02.Conclusion: Cognitive demand disproportionately affects functional visual field performance in drivers with glaucoma. Our results may inform the development of a performance-based visual field test for drivers with glaucoma.

  1. Use of computer graphics for visualization of flow fields

    Science.gov (United States)

    Watson, Val; Buning, Pieter; Choi, Diana; Bancroft, Gordon; Merritt, Fergus; Rogers, Stuart

    1987-01-01

    A high-performance graphics workstation has been combined with software developed for flow-field visualization to yield a highly effective tool for analysis of fluid-flow dynamics. After the flow fields are obtained from experimental measurements or computer simulations, the workstation permits one to interactively view the dynamics of the flow fields; e.g., the viewer can zoom into a region or rotate his viewing position about the region to study it in more detail. Several techniques for visualization of flow fields with this workstation are described in this paper and illustrated with a videotape available from the authors. The computer hardware and software required to create effective flow visualization displays are discussed. Additional software and hardware required to create videotapes or 16mm movies are also described. Limitations imposed by current workstation performance is addressed and future workstation performance is forecast.

  2. Alterations of color vision and central visual field in patients with Vogt−Koyanagi−Harada syndrome

    OpenAIRE

    Yang, Peizeng; Sun, Min; Liu, Xiaoli; Zhou, Hongyan; Fang, Wang; WANG, LI; Kijlstra, Aize

    2012-01-01

    Purpose To investigate the changes of color vision and central visual field in a cohort of patients with Vogt–Koyanagi–Harada (VKH) syndrome. Methods Sixteen VKH patients (32 eyes) were enrolled in this study. All the patients were treated with immunosuppressive agents. The best visual acuity, visual field testing and color vision testing were available from the records in all these patients at different time points, i.e. before treatment and 1 month (±7 days), 3 months (±15 days), 6 months (...

  3. Activation in left primary visual cortex representing parafoveal visual field during reading Japanese texts.

    Science.gov (United States)

    Shimada, Yoichi; Hirayama, Kazumi; Nakadomari, Satoshi; Furuta, Ayumu; Misaki, Masaya; Kan, Shigeyuki; Koike, Takahiko; Miyauchi, Satoru; Mori, Etsuro

    2011-08-23

    Activation in the left primary visual cortex (V1) representing the parafoveal field during text reading has been interpreted as attentional modulation in the process of deciding saccadic target for reading ahead. Kanji words serve the main cue to decide the goal of saccades in Japanese. We aimed to determine the exact location of this modulation in the V1 and to determine whether the area of the modulation changes according to the location where the next Kanji word appears or it is fixed on a certain region in V1. Using functional magnetic resonance imaging, we determined the area in V1 representing each eccentricity on the horizontal meridian of the visual field for each participant. Then we investigated brain activation while they were reading two sets of Japanese texts that scrolled leftward as the participants. In set 1, the distance between the heads of adjacent Kanji words was about 3°. In set 2, the distance was about 5°. From the results of these experiments, we obtained activation amplitude of the area corresponding to each eccentricity. We recorded eye movements simultaneously with the acquisition of fMRI data. The maximum peak of the activation was found in the region representing about 4.5° of eccentricity on the horizontal meridian in the left V1 for each participant. The activation pattern did not essentially differ between the two text conditions, although the location of the saccades made for reading next section of the text corresponds to the head of the next Kanji word. The activation modulation during reading Japanese texts occurs in the parafoveal V1 of the left hemisphere. The attentional modulation did not change with the distance to the next goal of saccade but was fixed on the area representing about 4.5° of eccentricity. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Graphics and Flow Visualization of Computer Generated Flow Fields

    Science.gov (United States)

    Kathong, M.; Tiwari, S. N.

    1987-01-01

    Flow field variables are visualized using color representations described on surfaces that are interpolated from computational grids and transformed to digital images. Techniques for displaying two and three dimensional flow field solutions are addressed. The transformations and the use of an interactive graphics program for CFD flow field solutions, called PLOT3D, which runs on the color graphics IRIS workstation are described. An overview of the IRIS workstation is also described.

  5. Semi-automatic measurement of visual verticality perception in humans reveals a new category of visual field dependency

    Directory of Open Access Journals (Sweden)

    C.R. Kaleff

    2011-08-01

    Full Text Available Previous assessment of verticality by means of rod and rod and frame tests indicated that human subjects can be more (field dependent or less (field independent influenced by a frame placed around a tilted rod. In the present study we propose a new approach to these tests. The judgment of visual verticality (rod test was evaluated in 50 young subjects (28 males, ranging in age from 20 to 27 years by randomly projecting a luminous rod tilted between -18 and +18° (negative values indicating left tilts onto a tangent screen. In the rod and frame test the rod was displayed within a luminous fixed frame tilted at +18 or -18°. Subjects were instructed to verbally indicate the rod’s inclination direction (forced choice. Visual dependency was estimated by means of a Visual Index calculated from rod and rod and frame test values. Based on this index, volunteers were classified as field dependent, intermediate and field independent. A fourth category was created within the field-independent subjects for whom the amount of correct guesses in the rod and frame test exceeded that of the rod test, thus indicating improved performance when a surrounding frame was present. In conclusion, the combined use of subjective visual vertical and the rod and frame test provides a specific and reliable form of evaluation of verticality in healthy subjects and might be of use to probe changes in brain function after central or peripheral lesions.

  6. Lateralized visual behavior in bottlenose dolphins (Tursiops truncatus) performing audio-visual tasks: the right visual field advantage.

    Science.gov (United States)

    Delfour, F; Marten, K

    2006-01-10

    Analyzing cerebral asymmetries in various species helps in understanding brain organization. The left and right sides of the brain (lateralization) are involved in different cognitive and sensory functions. This study focuses on dolphin visual lateralization as expressed by spontaneous eye preference when performing a complex cognitive task; we examine lateralization when processing different visual stimuli displayed on an underwater touch-screen (two-dimensional figures, three-dimensional figures and dolphin/human video sequences). Three female bottlenose dolphins (Tursiops truncatus) were submitted to a 2-, 3- or 4-, choice visual/auditory discrimination problem, without any food reward: the subjects had to correctly match visual and acoustic stimuli together. In order to visualize and to touch the underwater target, the dolphins had to come close to the touch-screen and to position themselves using monocular vision (left or right eye) and/or binocular naso-ventral vision. The results showed an ability to associate simple visual forms and auditory information using an underwater touch-screen. Moreover, the subjects showed a spontaneous tendency to use monocular vision. Contrary to previous findings, our results did not clearly demonstrate right eye preference in spontaneous choice. However, the individuals' scores of correct answers were correlated with right eye vision, demonstrating the advantage of this visual field in visual information processing and suggesting a left hemispheric dominance. We also demonstrated that the nature of the presented visual stimulus does not seem to have any influence on the animals' monocular vision choice.

  7. Visual field defects after temporal lobe resection for epilepsy.

    Science.gov (United States)

    Steensberg, Alvilda T; Olsen, Ane Sophie; Litman, Minna; Jespersen, Bo; Kolko, Miriam; Pinborg, Lars H

    2017-11-20

    To determine visual field defects (VFDs) using methods of varying complexity and compare results with subjective symptoms in a population of newly operated temporal lobe epilepsy patients. Forty patients were included in the study. Two patients failed to perform VFD testing. Humphrey Field Analyzer (HFA) perimetry was used as the gold standard test to detect VFDs. All patients performed a web-based visual field test called Damato Multifixation Campimetry Online (DMCO). A bedside confrontation visual field examination ad modum Donders was extracted from the medical records in 27/38 patients. All participants had a consultation by an ophthalmologist. A questionnaire described the subjective complaints. A VFD in the upper quadrant was demonstrated with HFA in 29 (76%) of the 38 patients after surgery. In 27 patients tested ad modum Donders, the sensitivity of detecting a VFD was 13%. Eight patients (21%) had a severe VFD similar to a quadrant anopia, thus, questioning their permission to drive a car. In this group of patients, a VFD was demonstrated in one of five (sensitivity=20%) ad modum Donders and in seven of eight (sensitivity=88%) with DMCO. Subjective symptoms were only reported by 28% of the patients with a VFD and in two of eight (sensitivity=25%) with a severe VFD. Most patients (86%) considered VFD information mandatory. VFD continue to be a frequent adverse event after epilepsy surgery in the medial temporal lobe and may affect the permission to drive a car in at least one in five patients. Subjective symptoms and bedside visual field testing ad modum Donders are not sensitive to detect even a severe VFD. Newly developed web-based visual field test methods appear sensitive to detect a severe VFD but perimetry remains the golden standard for determining if visual standards for driving is fulfilled. Patients consider VFD information as mandatory. Copyright © 2017. Published by Elsevier Ltd.

  8. Visual field defects after temporal lobe resection for epilepsy

    DEFF Research Database (Denmark)

    Steensberg, Alvilda T; Olsen, Ane Sophie; Litman, Minna

    2018-01-01

    of detecting a VFD was 13%. Eight patients (21%) had a severe VFD similar to a quadrant anopia, thus, questioning their permission to drive a car. In this group of patients, a VFD was demonstrated in one of five (sensitivity=20%) ad modum Donders and in seven of eight (sensitivity=88%) with DMCO. Subjective...... the permission to drive a car in at least one in five patients. Subjective symptoms and bedside visual field testing ad modum Donders are not sensitive to detect even a severe VFD. Newly developed web-based visual field test methods appear sensitive to detect a severe VFD but perimetry remains the golden...

  9. Binocular Measures of Visual Acuity and Visual Field versus Binocular Approximations.

    Science.gov (United States)

    Musch, David C; Niziol, Leslie M; Gillespie, Brenda W; Lichter, Paul R; Janz, Nancy K

    2017-07-01

    To assess the relationship of binocular visual function tests with binocular approximations using data from the Collaborative Initial Glaucoma Treatment Study (CIGTS). Case series based on existing data from a clinical trial. Six hundred seven patients with newly diagnosed open-angle glaucoma from the CIGTS. Monocular visual field (VF) and visual acuity (VA) tests were performed at baseline and every 6 months thereafter. Binocular tests of visual function (Esterman VF score, binocular VA) were added to the CIGTS protocol 3 years into the study. The binocular approximations of binocular visual function were better or worse eye, average eye, better or worse location, and binocular summation or pointwise binocular summation. Associations between binocular tests and binocular approximations to represent binocular visual function were assessed with Pearson's correlations (r), as was the relationship between vision-related quality of life (VR QOL; Visual Activities Questionnaire [VAQ] and the 25-item National Eye Institute Visual Function Questionnaire [NEI VFQ-25]) and binocular tests or binocular approximations of visual function. Binocular visual function (VF and VA) and VR QOL. Five hundred seventy-five patients underwent at least 1 binocular visual function test. The Esterman score was correlated significantly with all binocular approximations of VF, with r values ranging from 0.31 (worse-eye mean deviation [MD]) to 0.42 (better-eye MD; P visual functioning. In contrast, we found some benefit in performing binocular VF testing, because the results correlated more closely with reported functioning than binocular approximations. Copyright © 2017 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

  10. How useful is visual field testing in an African glaucoma clinic?

    Directory of Open Access Journals (Sweden)

    Lenake M

    2014-09-01

    Full Text Available Mpopi Lenake,1,2 Colin Cook,1,2 Hamzah Mustak,1,2 Nagib Du Toit1,2 1Division of Ophthalmology, Department of Surgery, Groote Schuur Hospital, Cape Town, South Africa; 2The University of Cape Town, Cape Town, South Africa Purpose: To investigate the usefulness of visual field testing in the diagnosis and subsequent management of glaucoma in a specialist glaucoma clinic at Groote Schuur Hospital, Cape Town, South Africa.Methods: A retrospective case note review of 344 patients who attended the glaucoma clinic between January and June 2010.Results: The study population consisted of 201 (58% females and 143 (42% males. The diagnoses included 207 (60% cases with primary open-angle glaucoma, 58 (17% cases with chronic angle closure glaucoma, 46 (13% cases with secondary glaucoma, 17 (5% cases with normal pressure glaucoma, ten (3% cases with ocular hypertension, and six (2% glaucoma suspects. Visual field testing contributed to the diagnosis of glaucoma in only 34 (10% cases. A total number of 2,604 fields were performed. Of these fields, 1,931 (74% were reliable. A baseline was reached in only 141 (53% patients. There was evidence of field progression in only 24 (9% cases. Changes to glaucoma treatment were based on inadequate control of intraocular pressure alone in 309 (90% patients. Visual field progression contributed to changes in treatment in only 15 (4% cases. Conclusion: Visual fields are not used in the diagnosis and management of glaucoma in the majority of patients in our clinic. Patients present with advanced disease, which is easily diagnosed without the use of visual fields. Progression of fields seldom contributes to monitoring and intraocular pressure is mainly used to monitor the adequacy of treatment. Keywords: Humphrey visual fields, reliability, diagnosis, progression

  11. Novel Texture-based Visualization Methods for High-dimensional Multi-field Data Sets

    Science.gov (United States)

    2013-07-06

    ply research in visualisation and cognitive science to iden- tify four classes of post-processing techniques for visualis- ing two 2D vector fields...visualisations with smooth colour changes are perceived as visually more attractive, and that aesthetics increases the perceived effectiveness of a...fields using Voreen [16] and used concepts from graphics and cognitive psychology to combine them. Except for the bump map, all vector fields were

  12. Prevention of visual field defects after macular hole surgery.

    LENUS (Irish Health Repository)

    Cullinane, A B

    2012-02-03

    BACKGROUND\\/AIM: The pathogenesis of visual field loss associated with macular hole surgery is uncertain but a number of explanations have been proposed, the most convincing of which is the effect of peeling of the posterior hyaloid, causing either direct damage to the nerve fibre layer or to its blood supply at the optic nerve head. The purpose of this preliminary prospective study was to determine the incidence of visual field defects following macular hole surgery in cases in which peeling of the posterior hyaloid was confined only to the area of the macula. METHODS: 102 consecutive eyes that had macular hole surgery had preoperative and postoperative visual field examination using a Humphrey\\'s perimeter. A comparison was made between two groups: I, those treated with vitrectomy with complete posterior cortical vitreous peeling; and II, those treated with a vitrectomy with peeling of the posterior hyaloid in the area of the macula but without attempting a complete posterior vitreous detachment. Specifically, no attempt was made to separate the posterior hyaloid from the optic nerve head. Eyes with stage II or III macular holes were operated. Autologous platelet concentrate and non-expansile gas tamponade was used. Patients were postured prone for 1 week. RESULTS: In group I, 22% of patients were found to have visual field defects. In group II, it was possible to separate the posterior hyaloid from the macula without stripping it from the optic nerve head and in these eyes no pattern of postoperative visual field loss emerged. There were no significant vision threatening complications in this group. The difference in the incidence of visual field loss between group I and group II was significant (p=0.02). The anatomical and visual success rates were comparable between both groups. CONCLUSION: The results from this preliminary study suggest that the complication of visual field loss after macular surgery may be reduced if peeling of the posterior hyaloid is

  13. Clinical treatment options for patients with homonymous visual field defects

    Directory of Open Access Journals (Sweden)

    Alison R Lane

    2008-03-01

    Full Text Available Alison R Lane, Daniel T Smith, Thomas SchenkCognitive Neuroscience Research Unit, Durham University, Durham, UKAbstract: The objective of this review is to evaluate treatments for homonymous visual field defects (HVFDs. We distinguish between three treatments: visual restoration training (VRT, optical aids, and compensatory training. VRT is both the most ambitious and controversial approach, aiming to restore portions of the lost visual field. While early studies suggested that VRT can reduce the visual field defect, recent studies using more reliable means of monitoring the patients’ fixation could not confirm this effect. Studies utilizing modern optical aids have reported some promising results, but the extent to which these aids can reliably reduce the patients’ visual disability has yet to be confirmed. Compensatory approaches, which teach patients more effective ways of using their eyes, are currently the only form of treatment for which behavioral improvements have been demonstrated. However, with the exception of one study using a reading training, placebo-controlled clinical evaluation studies are lacking. It is also not yet clear whether the training benefits found in laboratory tasks lead to reliable improvements in activities of daily living and which of the various forms of compensatory training is the most promising. It is therefore too early to recommend any of the currently available treatment approaches.Keywords: homonymous hemianopia, rehabilitation, treatment outcome

  14. Patterns of non-embolic transient monocular visual field loss

    NARCIS (Netherlands)

    Petzold, A.; Islam, N.; Plant, G.T.

    2013-01-01

    The aim of this study was to systematically describe the semiology of non-embolic transient monocular visual field loss (neTMVL). We conducted a retrospective case note analysis of patients from Moorfields Eye Hospital (1995-2007). The variables analysed were age, age of onset, gender, past medical

  15. Visual field examination in children with brain disorders

    NARCIS (Netherlands)

    Koenraads, Y

    2016-01-01

    The aim of this thesis is to gain more insight in the diagnostic and prognostic implications of visual field (VF) examination in children with brain disorders. Several aspects of VF examination in children with brain disorders were evaluated: All VF examinations that were performed with the

  16. Perception of Biological Motion in Central and Peripheral Visual Fields

    Directory of Open Access Journals (Sweden)

    Laicāne Ilze

    2017-10-01

    Full Text Available Studies analysing biological motion perception based on reduced number of dots have demonstrated that biological motion can be perceived even when only the lower part of the body is visible or when the number of dots representing the object is reduced. What is the minimal amount of information that enables biological motion to be distinguished from its scrambled version? The results of the current experiment demonstrate that biological motion can be distinguished from its scrambled version when the object is formed of approximately 5 (4.7 ± 0.1 dots. Additionally, we also investigated whether the threshold value for biological motion perception differs in central and peripheral visual fields. By using stimulus magnification, we demonstrate that the number of dots sufficient for biological motion perception is similar in the central visual field and near periphery. Hence, stimulus magnification can compensate for reduced task performance in the peripheral visual field. The current results suggest that reduced performance of biological motion perception in the peripheral visual field (as demonstrated in other studies is due to difficulties with the global perception of biological motion.

  17. Visual Working Memory Load-Related Changes in Neural Activity and Functional Connectivity

    OpenAIRE

    Ling Li; Jin-Xiang Zhang; Tao Jiang

    2011-01-01

    BACKGROUND: Visual working memory (VWM) helps us store visual information to prepare for subsequent behavior. The neuronal mechanisms for sustaining coherent visual information and the mechanisms for limited VWM capacity have remained uncharacterized. Although numerous studies have utilized behavioral accuracy, neural activity, and connectivity to explore the mechanism of VWM retention, little is known about the load-related changes in functional connectivity for hemi-field VWM retention. MET...

  18. Superior performance for visually guided pointing in the lower visual field.

    Science.gov (United States)

    Danckert, J; Goodale, M A

    2001-04-01

    The superior hemiretina in primates and humans has a greater density of ganglion cells than the inferior hemiretina, suggesting a bias towards processing information in the lower visual field (loVF). In primates, this over-representation of the loVF is also evident at the level of striate and extrastriate cortex. This is particularly true in some of the visual areas constituting the dorsal "action" pathway, such as area V6A. Here we show that visually guided pointing movements with the hand are both faster and more accurate when performed in the loVF when compared to the same movements made in the upper visual field (upVF). This was true despite the fact that the biomechanics of the movements made did not differ across conditions. The loVF advantage for the control of visually guided pointing movements is unlikely to be due to retinal factors and may instead reflect a functional bias for controlling skilled movements in this region of space. Possible neural correlates for this loVF advantage for visually guided pointing are discussed.

  19. Visual teaching and learning in the fields of engineering

    Directory of Open Access Journals (Sweden)

    Kyvete S. Shatri

    2015-11-01

    Full Text Available Engineering education today is faced with numerous demands that are closely connected with a globalized economy. One of these requirements is to draw the engineers of the future, who are characterized with: strong analytical skills, creativity, ingenuity, professionalism, intercultural communication and leadership. To achieve this effective teaching methods should be used to facilitate and enhance the learning of students and their performance in general, making them able to cope with market demands of a globalized economy. One of these methods is the visualization as a very important method that increases the learning of students. A visual approach in science and in engineering also increases communication, critical thinking and provides analytical approach to various problems. Therefore, this research is aimed to investigate the effect of the use of visualization in the process of teaching and learning in engineering fields and encourage teachers and students to use visual methods for teaching and learning. The results of this research highlight the positive effect that the use of visualization has in the learning process of students and their overall performance. In addition, innovative teaching methods have a good effect in the improvement of the situation. Visualization motivates students to learn, making them more cooperative and developing their communication skills.

  20. Semantic Data And Visualization Techniques Applied To Geologic Field Mapping

    Science.gov (United States)

    Houser, P. I. Q.; Royo-Leon, M.; Munoz, R.; Estrada, E.; Villanueva-Rosales, N.; Pennington, D. D.

    2015-12-01

    Geologic field mapping involves the use of technology before, during, and after visiting a site. Geologists utilize hardware such as Global Positioning Systems (GPS) connected to mobile computing platforms such as tablets that include software such as ESRI's ArcPad and other software to produce maps and figures for a final analysis and report. Hand written field notes contain important information and drawings or sketches of specific areas within the field study. Our goal is to collect and geo-tag final and raw field data into a cyber-infrastructure environment with an ontology that allows for large data processing, visualization, sharing, and searching, aiding in connecting field research with prior research in the same area and/or aid with experiment replication. Online searches of a specific field area return results such as weather data from NOAA and QuakeML seismic data from USGS. These results that can then be saved to a field mobile device and searched while in the field where there is no Internet connection. To accomplish this we created the GeoField ontology service using the Web Ontology Language (OWL) and Protégé software. Advanced queries on the dataset can be made using reasoning capabilities can be supported that go beyond a standard database service. These improvements include the automated discovery of data relevant to a specific field site and visualization techniques aimed at enhancing analysis and collaboration while in the field by draping data over mobile views of the site using augmented reality. A case study is being performed at University of Texas at El Paso's Indio Mountains Research Station located near Van Horn, Texas, an active multi-disciplinary field study site. The user can interactively move the camera around the study site and view their data digitally. Geologist's can check their data against the site in real-time and improve collaboration with another person as both parties have the same interactive view of the data.

  1. Lighting Direction and Visual Field Modulate Perceived Intensity of Illumination

    Directory of Open Access Journals (Sweden)

    Mark E McCourt

    2013-12-01

    Full Text Available When interpreting object shape from shading the visual system exhibits a strong bias that illumination comes from above and slightly from the left. We asked whether such biases in the perceived direction of illumination might also influence its perceived intensity. Arrays of nine cubes were stereoscopically rendered where individual cubes varied in their 3D pose, but possessed identical triplets of visible faces. Arrays were virtually illuminated from one of four directions: Above-Left, Above-Right, Below-Left, and Below-Right (±24.4o azimuth; ±90o elevation. Illumination intensity possessed 15 levels, resulting in mean cube array luminances ranging from 1.31-3.45 cd/m2. A reference array was consistently illuminated from Above-Left at mid-intensity (mean array luminance = 2.38 cd/m2. The reference array’s illumination was compared to that of matching arrays which were illuminated from all four directions at all intensities. Reference and matching arrays appeared in the left and right visual field, respectively, or vice versa. Subjects judged which cube array appeared to be under more intense illumination. Using the method of constant stimuli we determined the illumination level of matching arrays required to establish subjective equality with the reference array as a function of matching cube visual field, illumination elevation, and illumination azimuth. Cube arrays appeared significantly more intensely illuminated when they were situated in the left visual field (p = .017, and when they were illuminated from below (p = .001, and from the left (p = .001. An interaction of modest strength was that the effect of illumination azimuth was greater for matching arrays situated in the left visual field (p = .042. We propose that objects lit from below appear more intensely illuminated than identical objects lit from above due to long-term adaptation to downward lighting. The amplification of perceived intensity of illumination for stimuli

  2. Do small-aperture presbyopic corrections influence the visual field?

    Science.gov (United States)

    Atchison, David A; Blazaki, Stella; Suheimat, Marwan; Plainis, Sotiris; Charman, W Neil

    2016-01-01

    To explore the effect of small-aperture optics, designed to aid presbyopes by increasing ocular depth-of-focus, on measurements of the visual field. Simple theoretical and ray-tracing models were used to predict the impact of different designs of small-aperture contact lenses or corneal inlays on the proportion of light passing through natural pupils of various diameters as a function of the direction in the visual field. The left eyes of five healthy volunteers were tested using three afocal, hand-painted opaque soft contact lenses (www.davidthomas.com). Two were opaque over a 10 mm diameter but had central clear circular apertures of 1.5 and 3.0 mm in diameter. The third had an annular opaque zone with inner and outer diameters of 1.5 and 4.0 mm, approximately simulating the geometry of the KAMRA inlay (www.acufocus.com). A fourth, clear lens was used for comparison purposes. Visual fields along the horizontal meridian were evaluated up to 50° eccentricity with static automated perimetry (Medmont M700, stimulus Goldmann-size III; www.medmont.com). According to ray-tracing, the two lenses with the circular apertures were expected to reduce the relative transmittance of the pupil to zero at specific field angles (around 60° for the conditions of the experimental measurements). In contrast, the annular stop had no effect on the absolute field but relative transmittance was reduced over the central area of the field, the exact effects depending upon the natural pupil diameter. Experimental results broadly agreed with these theoretical expectations. With the 1.5 and 3.0 mm pupils, only minor losses in sensitivity (around 2 dB) in comparison with the clear-lens case occurred across the central 10° radius of field. Beyond this angle, sensitivity losses increased, to reach about 7 dB at the edge of the measured field (50°). The field results with the annular stop showed at most only a slight loss in sensitivity (≤3 dB) across the measured field. The

  3. Development of an LCD-Based Visual Field System.

    Science.gov (United States)

    Joo, Jin Ho; Lee, Jihyoung; You, Heecheon; Kang, Jaheon

    2018-01-15

    The present study investigated the diagnostic effectiveness of an LCD-based visual field testing system (LVF) in comparison with the standard automated perimetry Humphrey Field Analyzer II-750i (HFA). A randomized controlled crossover study was conducted with 202 normal and 128 glaucomatous eyes using both LVF and HFA. The visual field testing systems were compared in terms of mean deviation (MD), pattern standard deviation (PSD), and area under the receiver operating characteristics curve (AUC) of MD and PSD differentiating the normal and glaucomatous eyes. Significant correlations were found between MD measurements from LVF and those from HFA for normal eyes (r = 0.342) and glaucomatous eyes (r = 0.796); slightly higher significant correlations were identified between PSD measurements from LVF and those from HFA for normal eyes (r = 0.363) and glaucomatous eyes (r = 0.828). Furthermore, high AUCs of MD were found as 0.786 for LVF and 0.868 for HFA and AUCs of PSD as 0.913 for LVF and 0.932 for HFA. The comparison results of the present study support the competence of LVF compared with HFA in visual field testing for early detection of glaucoma.

  4. Reducing Visual Discomfort with HMDs Using Dynamic Depth of Field.

    Science.gov (United States)

    Carnegie, Kieran; Rhee, Taehyun

    2015-01-01

    Although head-mounted displays (HMDs) are ideal devices for personal viewing of immersive stereoscopic content, exposure to VR applications on them results in significant discomfort for the majority of people, with symptoms including eye fatigue, headaches, nausea, and sweating. A conflict between accommodation and vergence depth cues on stereoscopic displays is a significant cause of visual discomfort. This article describes the results of an evaluation used to judge the effectiveness of dynamic depth-of-field (DoF) blur in an effort to reduce discomfort caused by exposure to stereoscopic content on HMDs. Using a commercial game engine implementation, study participants report a reduction of visual discomfort on a simulator sickness questionnaire when DoF blurring is enabled. The study participants reported a decrease in symptom severity caused by HMD exposure, indicating that dynamic DoF can effectively reduce visual discomfort.

  5. Invariance of visual operations at the level of receptive fields.

    Directory of Open Access Journals (Sweden)

    Tony Lindeberg

    Full Text Available The brain is able to maintain a stable perception although the visual stimuli vary substantially on the retina due to geometric transformations and lighting variations in the environment. This paper presents a theory for achieving basic invariance properties already at the level of receptive fields. Specifically, the presented framework comprises (i local scaling transformations caused by objects of different size and at different distances to the observer, (ii locally linearized image deformations caused by variations in the viewing direction in relation to the object, (iii locally linearized relative motions between the object and the observer and (iv local multiplicative intensity transformations caused by illumination variations. The receptive field model can be derived by necessity from symmetry properties of the environment and leads to predictions about receptive field profiles in good agreement with receptive field profiles measured by cell recordings in mammalian vision. Indeed, the receptive field profiles in the retina, LGN and V1 are close to ideal to what is motivated by the idealized requirements. By complementing receptive field measurements with selection mechanisms over the parameters in the receptive field families, it is shown how true invariance of receptive field responses can be obtained under scaling transformations, affine transformations and Galilean transformations. Thereby, the framework provides a mathematically well-founded and biologically plausible model for how basic invariance properties can be achieved already at the level of receptive fields and support invariant recognition of objects and events under variations in viewpoint, retinal size, object motion and illumination. The theory can explain the different shapes of receptive field profiles found in biological vision, which are tuned to different sizes and orientations in the image domain as well as to different image velocities in space-time, from a

  6. Visualizing the blind brain: brain imaging of visual field defects from early recovery to rehabilitation techniques

    Directory of Open Access Journals (Sweden)

    Marika eUrbanski

    2014-09-01

    Full Text Available Visual field defects (VFDs are one of the most common consequences observed after brain injury, especially after a stroke in the posterior cerebral artery territory. Less frequently, tumours, traumatic brain injury, brain surgery or demyelination can also determine various visual disabilities, from a decrease in visual acuity to cerebral blindness. VFD is a factor of bad functional prognosis as it compromises many daily life activities (e.g., obstacle avoidance, driving, and reading and therefore the patient’s quality of life. Spontaneous recovery seems to be limited and restricted to the first six months, with the best chance of improvement at one month. The possible mechanisms at work could be partly due to cortical reorganization in the visual areas (plasticity and/or partly to the use of intact alternative visual routes, first identified in animal studies and possibly underlying the phenomenon of blindsight. Despite processes of early recovery, which is rarely complete, and learning of compensatory strategies, the patient’s autonomy may still be compromised at more chronic stages. Therefore, various rehabilitation therapies based on neuroanatomical knowledge have been developed to improve VFDs. These use eye-movement training techniques (e.g., visual search, saccadic eye movements, reading training, visual field restitution (the Vision Restoration Therapy, VRT, or perceptual learning. In this review, we will focus on studies of human adults with acquired VFDs, which have used different imaging techniques (Positron Emission Tomography: PET, Diffusion Tensor Imaging: DTI, functional Magnetic Resonance Imaging: fMRI, MagnetoEncephalography: MEG or neurostimulation techniques (Transcranial Magnetic Stimulation: TMS; transcranial Direct Current Stimulation, tDCS to show brain activations in the course of spontaneous recovery or after specific rehabilitation techniques.

  7. The Worringham and Beringer 'visual field' principle for rotary controls.

    Science.gov (United States)

    Hoffmann, Errol R; Chan, Alan H S

    2013-01-01

    Worringham and Beringer (1989, 1998) developed a very important principle relating compatibility of movement of horizontally moving translational controls to display movements when the operator's view of the display is in a plane different to that of the control. On the basis of past data of the current authors, it is shown that the visual field principle also applies to the operation of vertically moving translational controls and to rotary controls. These additions make the Worringham and Beringer principle the most powerful design principle available for situations where the operator is viewing a display that is not in the same plane as the control. High compatibility between control input and display output is of great importance in machine design. This paper demonstrates that, for cases where the display is not in the same plane as the control, the visual field principle is operational for vertically moving translational controls and rotary controls as well as for horizontally moving translational controls.

  8. Practical landmarks for visual field disability in glaucoma.

    Science.gov (United States)

    Saunders, Luke J; Russell, Richard A; Crabb, David P

    2012-09-01

    To assess whether mean deviation (MD) from automated perimetry is related to the visual field (VF) component for legal fitness to drive (LFTD) in glaucoma patients. Monocular 24-2 VFs of 2604 patients with bilateral VF damage were retrospectively investigated. Integrated visual fields were calculated and used as a surrogate to assess LFTD according to current UK driving licence criteria. The better eye MD (BEMD), worse eye MD (WEMD) and a measure utilising MD of both eyes were compared, to assess respective diagnostic capabilities to predict LFTD (using the integrated visual field surrogate test as the gold standard) and a 'Probability of Failure' (PoF) for various defect levels was calculated. BEMD appears to be a good predictor of the VF component for a patient's LFTD (receiver operating characteristic area under the curve: 96.2%); MDs from both eyes offered no significant extra diagnostic power (area under the curve: 96.4%). PoF for BEMD thresholds of ≤-10 dB and ≤-14 dB were 70 (95% CI 66% to 74%) and 92% (87% to 95%), respectively. There is a strong relationship between BEMD and a patient's LFTD. PoF values for LFTD associated with readily available MD values provide practical landmarks for VF disability in glaucoma.

  9. Comparison of visual field severity classification systems for glaucoma.

    Science.gov (United States)

    Ng, Minna; Sample, Pamela A; Pascual, John P; Zangwill, Linda M; Girkin, Chris A; Liebmann, Jeffrey M; Weinreb, Robert N; Racette, Lyne

    2012-01-01

    To compare categorical severity classification systems for glaucoma. This cross-sectional study included 1,921 eyes (49.5% right eye) from 1,137 participants from the Diagnostic Innovations in Glaucoma Study and African Descent and Glaucoma Evaluation Study. Standard automated perimetry fields were classified using the: (1) Advanced Glaucoma Intervention Study scoring system (AGIS), (2) Glaucoma Severity Staging system (GSS), and (3) Enhanced Glaucoma Severity Staging system (eGSS). Systems were characterized using the following continuous measures of severity: mean deviation, pattern standard deviation, and visual field index. Classifications between systems and with optic disc stereophotograph assessment were compared (κ) and some stages were consolidated to evaluate severity classification across systems (Wilcoxon test). Mean deviation, pattern standard deviation, and visual field index were significantly different between GSS and AGIS, and GSS and eGSS in normal and abnormal fields (PeGSS was substantial (κ=0.715±0.012); agreement between GSS and eGSS (κ=0.559±0.014) and AGIS (κ=0.519±0.016) was moderate. eGSS tended to stage abnormal fields most severely followed by GSS and then AGIS (PeGSS may be the better choice for its ease of use for both clinicians and researchers.

  10. Spatial context learning in visual search and change detection.

    Science.gov (United States)

    Jiang, Yuhong; Song, Joo-Hyun

    2005-10-01

    Humans conduct visual search more efficiently when the same display is presented for a second time, showing learning of repeated spatial contexts. In this study, we investigate spatial context learning in two tasks: visual search and change detection. In both tasks, we ask whether subjects learn to associate the target with the entire spatial layout of a repeated display (configural learning) or with individual distractor locations (nonconfigural learning). We show that nonconfigural learning results from visual search tasks, but not from change detection tasks. Furthermore, a spatial layout acquired in visual search tasks does not enhance change detection on the same display, whereas a spatial layout acquired in change detection tasks moderately enhances visual search. We suggest that although spatial context learning occurs in multiple tasks, the content of learning is, in part, task specific.

  11. 3-D Flow Visualization with a Light-field Camera

    Science.gov (United States)

    Thurow, B.

    2012-12-01

    Light-field cameras have received attention recently due to their ability to acquire photographs that can be computationally refocused after they have been acquired. In this work, we describe the development of a light-field camera system for 3D visualization of turbulent flows. The camera developed in our lab, also known as a plenoptic camera, uses an array of microlenses mounted next to an image sensor to resolve both the position and angle of light rays incident upon the camera. For flow visualization, the flow field is seeded with small particles that follow the fluid's motion and are imaged using the camera and a pulsed light source. The tomographic MART algorithm is then applied to the light-field data in order to reconstruct a 3D volume of the instantaneous particle field. 3D, 3C velocity vectors are then determined from a pair of 3D particle fields using conventional cross-correlation algorithms. As an illustration of the concept, 3D/3C velocity measurements of a turbulent boundary layer produced on the wall of a conventional wind tunnel are presented. Future experiments are planned to use the camera to study the influence of wall permeability on the 3-D structure of the turbulent boundary layer.Schematic illustrating the concept of a plenoptic camera where each pixel represents both the position and angle of light rays entering the camera. This information can be used to computationally refocus an image after it has been acquired. Instantaneous 3D velocity field of a turbulent boundary layer determined using light-field data captured by a plenoptic camera.

  12. Visual field loss morphology in high- and normal-tension glaucoma.

    Science.gov (United States)

    Iester, Michele; De Feo, Fabio; Douglas, Gordon R

    2012-01-01

    Purpose. To determine whether the patterns of visual field damage between high-tension glaucoma (HTG) and normal-tension glaucoma (NTG) are equivalent. Methods. In this retrospective cross-sectional study, fifty-one NTG and 57 HTG patients were recruited. For each recruited patient only the left eye was chosen. Glaucomatous patients had abnormal visual fields and/or glaucomatous changes at the optic nerve head. They were classified as HTG or NTG on the basis of intraocular pressure (IOP) measurements. Patients' visual fields were analyzed by using Humphrey Field Analyzer (HFA), program 30-2, full threshold. The visual field sensitivity values and the pattern deviation map values of the 72 tested points were considered. Then a pointwise analysis and an area analysis, based on the Glaucoma Hemifield test criteria, were performed, and a comparison between the two subgroups was made by Student's t test. Results. Between NTG and HTG, no significant difference was found pointwise for almost all the visual field points, except for two locations. One was under the blind spot, and the other was in the inferior hemifield around the twenty-degree position. When area analysis was considered, three areas showed a significantly different sensitivity between HTG and NTG. Conclusions. These data suggested that there was no relevant difference in the pointwise analysis between NTG and HTG; however, when visual field areas were compared, no difference in paracentral areas was found between NTG and HTG, but superior nasal step and inferior and superior scotomata showed to be deeper in HTG than in NTG.

  13. Connectivity Changes Underlying Neurofeedback Training of Visual Cortex Activity

    Science.gov (United States)

    Scharnowski, Frank; Rosa, Maria Joao; Golestani, Narly; Hutton, Chloe; Josephs, Oliver

    2014-01-01

    Neurofeedback based on real-time functional magnetic resonance imaging (fMRI) is a new approach that allows training of voluntary control over regionally specific brain activity. However, the neural basis of successful neurofeedback learning remains poorly understood. Here, we assessed changes in effective brain connectivity associated with neurofeedback training of visual cortex activity. Using dynamic causal modeling (DCM), we found that training participants to increase visual cortex activity was associated with increased effective connectivity between the visual cortex and the superior parietal lobe. Specifically, participants who learned to control activity in their visual cortex showed increased top-down control of the superior parietal lobe over the visual cortex, and at the same time reduced bottom-up processing. These results are consistent with efficient employment of top-down visual attention and imagery, which were the cognitive strategies used by participants to increase their visual cortex activity. PMID:24609065

  14. Connectivity changes underlying neurofeedback training of visual cortex activity.

    Directory of Open Access Journals (Sweden)

    Frank Scharnowski

    Full Text Available Neurofeedback based on real-time functional magnetic resonance imaging (fMRI is a new approach that allows training of voluntary control over regionally specific brain activity. However, the neural basis of successful neurofeedback learning remains poorly understood. Here, we assessed changes in effective brain connectivity associated with neurofeedback training of visual cortex activity. Using dynamic causal modeling (DCM, we found that training participants to increase visual cortex activity was associated with increased effective connectivity between the visual cortex and the superior parietal lobe. Specifically, participants who learned to control activity in their visual cortex showed increased top-down control of the superior parietal lobe over the visual cortex, and at the same time reduced bottom-up processing. These results are consistent with efficient employment of top-down visual attention and imagery, which were the cognitive strategies used by participants to increase their visual cortex activity.

  15. Early clinical and subclinical visual evoked potential and Humphrey's visual field defects in cryptococcal meningitis.

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    Anand Moodley

    Full Text Available Cryptococcal induced visual loss is a devastating complication in survivors of cryptococcal meningitis (CM. Early detection is paramount in prevention and treatment. Subclinical optic nerve dysfunction in CM has not hitherto been investigated by electrophysiological means. We undertook a prospective study on 90 HIV sero-positive patients with culture confirmed CM. Seventy-four patients underwent visual evoked potential (VEP testing and 47 patients underwent Humphrey's visual field (HVF testing. Decreased best corrected visual acuity (BCVA was detected in 46.5% of patients. VEP was abnormal in 51/74 (68.9% right eyes and 50/74 (67.6% left eyes. VEP P100 latency was the main abnormality with mean latency values of 118.9 (±16.5 ms and 119.8 (±15.7 ms for the right and left eyes respectively, mildly prolonged when compared to our laboratory references of 104 (±10 ms (p<0.001. Subclinical VEP abnormality was detected in 56.5% of normal eyes and constituted mostly latency abnormality. VEP amplitude was also significantly reduced in this cohort but minimally so in the visually unimpaired. HVF was abnormal in 36/47 (76.6% right eyes and 32/45 (71.1% left eyes. The predominant field defect was peripheral constriction with an enlarged blind spot suggesting the greater impact by raised intracranial pressure over that of optic neuritis. Whether this was due to papilloedema or a compartment syndrome is open to further investigation. Subclinical HVF abnormalities were minimal and therefore a poor screening test for early optic nerve dysfunction. However, early optic nerve dysfunction can be detected by testing of VEP P100 latency, which may precede the onset of visual loss in CM.

  16. Changes in weight, papilledema, headache, visual field, and life status in response to diet and metformin in women with idiopathic intracranial hypertension with and without concurrent polycystic ovary syndrome or hyperinsulinemia.

    Science.gov (United States)

    Glueck, Charles J; Golnik, Karl C; Aregawi, Dawit; Goldenberg, Naila; Sieve, Luann; Wang, Ping

    2006-11-01

    The authors hypothesized that a metformin (MET)-diet would improve symptoms of idiopathic intracranial hypertension (IIH) in women who also had polycystic ovary syndrome (PCOS) or hyperinsulinemia without PCOS. Changes in weight, papilledema, headache, visual fields, and overall life status were prospectively assessed in response to 6 to 14 months on 2.25 g/day MET-diet or diet alone in 36 women with IIH, 23 with PCOS, selected by baseline body mass index (BMI) > or = 25, and no previous surgery for IIH. Overall life status was graded using a self-reported 1-5 scale (1 = well, normal activities; 2 = unwell, usual activities; 3 = poor, usual activities; 4 = poor, no usual activities; 5 = totally disabled). Conventional treatment for IIH was maintained unchanged during MET-diet intervention. The diet was hypocaloric (1500 calories/day), high protein (26% of calories), and low carbohydrate (44%). Of the 23 women with PCOS, 20 received MET-diet and 3 diet only (could not tolerate MET). Of the 13 women without PCOS, 7 were hyperinsulinemic and received MET-diet and 6 received diet alone. The 3 treatment groups (diet only [n = 9], PCOS-MET-diet [n = 20], and hyperinsulinemia-MET-diet [n = 7]) did not differ by median entry BMI (33.3, 37.6, and 35.7 kg/m(2)) or by duration of treatment (10.2, 11.4, and 10.9 months). Median percent weight loss was greatest in the PCOS-MET group (7.7%, P = 0.0015), was 3.3% in the diet only group, and 2.4% (P = 0.04) in the hyperinsulinemia-MET group. Papilledema significantly improved in the diet-alone group from 100% at baseline to 13% (P = 0.03), and in the PCOS-MET group from 95% to 30% (P = 0.002). If headache persisted on therapy, it was less intense-less frequent (P = 0.03) in the diet-only group and in the PCOS-MET group (P = 0.04). As many women with IIH have PCOS, and because weight loss is central to IIH treatment, diet-MET is a novel approach to treat IIH in women with concurrent PCOS or hyperinsulinemia without PCOS.

  17. The risk of pedestrian collisions with peripheral visual field loss.

    Science.gov (United States)

    Peli, Eli; Apfelbaum, Henry; Berson, Eliot L; Goldstein, Robert B

    2016-12-01

    Patients with peripheral field loss complain of colliding with other pedestrians in open-space environments such as shopping malls. Field expansion devices (e.g., prisms) can create artificial peripheral islands of vision. We investigated the visual angle at which these islands can be most effective for avoiding pedestrian collisions, by modeling the collision risk density as a function of bearing angle of pedestrians relative to the patient. Pedestrians at all possible locations were assumed to be moving in all directions with equal probability within a reasonable range of walking speeds. The risk density was found to be highly anisotropic. It peaked at ≈45° eccentricity. Increasing pedestrian speed range shifted the risk to higher eccentricities. The risk density is independent of time to collision. The model results were compared to the binocular residual peripheral island locations of 42 patients with forms of retinitis pigmentosa. The natural residual island prevalence also peaked nasally at about 45° but temporally at about 75°. This asymmetry resulted in a complementary coverage of the binocular field of view. Natural residual binocular island eccentricities seem well matched to the collision-risk density function, optimizing detection of other walking pedestrians (nasally) and of faster hazards (temporally). Field expansion prism devices will be most effective if they can create artificial peripheral islands at about 45° eccentricities. The collision risk and residual island findings raise interesting questions about normal visual development.

  18. The role of hemifield sector analysis in multifocal visual evoked potential objective perimetry in the early detection of glaucomatous visual field defects.

    Science.gov (United States)

    Mousa, Mohammad F; Cubbidge, Robert P; Al-Mansouri, Fatima; Bener, Abdulbari

    2013-01-01

    The purpose of this study was to examine the effectiveness of a new analysis method of mfVEP objective perimetry in the early detection of glaucomatous visual field defects compared to the gold standard technique. Three groups were tested in this study; normal controls (38 eyes), glaucoma patients (36 eyes), and glaucoma suspect patients (38 eyes). All subjects underwent two standard 24-2 visual field tests: one with the Humphrey Field Analyzer and a single mfVEP test in one session. Analysis of the mfVEP results was carried out using the new analysis protocol: the hemifield sector analysis protocol. Analysis of the mfVEP showed that the signal to noise ratio (SNR) difference between superior and inferior hemifields was statistically significant between the three groups (analysis of variance, P field defects detected by standard perimetry, was able to differentiate between the three study groups with a clear distinction between normal patients and those with suspected glaucoma, and was able to detect early visual field changes not detected by standard perimetry. In addition, the distinction between normal and glaucoma patients was especially clear and significant using this analysis. The new hemifield sector analysis protocol used in mfVEP testing can be used to detect glaucomatous visual field defects in both glaucoma and glaucoma suspect patients. Using this protocol, it can provide information about focal visual field differences across the horizontal midline, which can be utilized to differentiate between glaucoma and normal subjects. The sensitivity and specificity of the mfVEP test showed very promising results and correlated with other anatomical changes in glaucomatous visual field loss. The intersector analysis protocol can detect early field changes not detected by the standard Humphrey Field Analyzer test.

  19. Visual Field Outcomes for the Idiopathic Intracranial Hypertension Treatment Trial (IIHTT)

    Science.gov (United States)

    Wall, Michael; Johnson, Chris A.; Cello, Kimberly E.; Zamba, K. D.; McDermott, Michael P.; Keltner, John L.

    2016-01-01

    Purpose The Idiopathic Intracranial Hypertension Treatment Trial (IIHTT) showed that acetazolamide provided a modest, significant improvement in mean deviation (MD). Here, we further analyze visual field changes over the 6-month study period. Methods Of 165 subjects with mild visual loss in the IIHTT, 125 had perimetry at baseline and 6 months. We evaluated pointwise linear regression of visual sensitivity versus time to classify test locations in the worst MD (study) eye as improving or not; pointwise changes from baseline to month 6 in decibels; and clinical consensus of change from baseline to 6 months. Results The average study eye had 36 of 52 test locations with improving sensitivity over 6 months using pointwise linear regression, but differences between the acetazolamide and placebo groups were not significant. Pointwise results mostly improved in both treatment groups with the magnitude of the mean change within groups greatest and statistically significant around the blind spot and the nasal area, especially in the acetazolamide group. The consensus classification of visual field change from baseline to 6 months in the study eye yielded percentages (acetazolamide, placebo) of 7.2% and 17.5% worse, 35.1% and 31.7% with no change, and 56.1% and 50.8% improved; group differences were not statistically significant. Conclusions In the IIHTT, compared to the placebo group, the acetazolamide group had a significant pointwise improvement in visual field function, particularly in the nasal and pericecal areas; the latter is likely due to reduction in blind spot size related to improvement in papilledema. (ClinicalTrials.gov number, NCT01003639.) PMID:26934136

  20. Spatial uninformative sounds increase sensitivity for visual motion change

    NARCIS (Netherlands)

    Staufenbiel, Sabine M.; van der Lubbe, Robert Henricus Johannes; Talsma, D.

    2011-01-01

    It has recently been shown that spatially uninformative sounds can cause a visual stimulus to pop out from an array of similar distractor stimuli when that sound is presented in temporal proximity to a feature change in the visual stimulus. Until now, this effect has predominantly been demonstrated

  1. Visualization and unsupervised classification of changes in multispectral satellite imagery

    DEFF Research Database (Denmark)

    Canty, Morton J.; Nielsen, Allan Aasbjerg

    2006-01-01

    The statistical techniques of multivariate alteration detection, minimum/maximum autocorrelation factors transformation, expectation maximization and probabilistic label relaxation are combined in a unified scheme to visualize and to classify changes in multispectral satellite data. The methods...

  2. A Prospective Profile of Visual Field Loss following Stroke: Prevalence, Type, Rehabilitation, and Outcome

    Directory of Open Access Journals (Sweden)

    Fiona J. Rowe

    2013-01-01

    Full Text Available Aims. To profile site of stroke/cerebrovascular accident, type and extent of field loss, treatment options, and outcome. Methods. Prospective multicentre cohort trial. Standardised referral and investigation protocol of visual parameters. Results. 915 patients were recruited with a mean age of 69 years (SD 14. 479 patients (52% had visual field loss. 51 patients (10% had no visual symptoms. Almost half of symptomatic patients (n=226 complained only of visual field loss: almost half (n=226 also had reading difficulty, blurred vision, diplopia, and perceptual difficulties. 31% (n=151 had visual field loss as their only visual impairment: 69% (n=328 had low vision, eye movement deficits, or visual perceptual difficulties. Occipital and parietal lobe strokes most commonly caused visual field loss. Treatment options included visual search training, visual awareness, typoscopes, substitutive prisms, low vision aids, refraction, and occlusive patches. At followup 15 patients (7.5% had full recovery, 78 (39% had improvement, and 104 (52% had no recovery. Two patients (1% had further decline of visual field. Patients with visual field loss had lower quality of life scores than stroke patients without visual impairment. Conclusions. Stroke survivors with visual field loss require assessment to accurately define type and extent of loss, diagnose coexistent visual impairments, and offer targeted treatment.

  3. A Prospective Profile of Visual Field Loss following Stroke: Prevalence, Type, Rehabilitation, and Outcome

    Science.gov (United States)

    Rowe, Fiona J.; Wright, David; Brand, Darren; Jackson, Carole; Harrison, Shirley; Maan, Tallat; Vogwell, Linda; Peel, Sarah; Akerman, Nicola; Shipman, Tracey; Sperring, Una; MacDiarmid, Sonia; Freeman, Cicely

    2013-01-01

    Aims. To profile site of stroke/cerebrovascular accident, type and extent of field loss, treatment options, and outcome. Methods. Prospective multicentre cohort trial. Standardised referral and investigation protocol of visual parameters. Results. 915 patients were recruited with a mean age of 69 years (SD 14). 479 patients (52%) had visual field loss. 51 patients (10%) had no visual symptoms. Almost half of symptomatic patients (n = 226) complained only of visual field loss: almost half (n = 226) also had reading difficulty, blurred vision, diplopia, and perceptual difficulties. 31% (n = 151) had visual field loss as their only visual impairment: 69% (n = 328) had low vision, eye movement deficits, or visual perceptual difficulties. Occipital and parietal lobe strokes most commonly caused visual field loss. Treatment options included visual search training, visual awareness, typoscopes, substitutive prisms, low vision aids, refraction, and occlusive patches. At followup 15 patients (7.5%) had full recovery, 78 (39%) had improvement, and 104 (52%) had no recovery. Two patients (1%) had further decline of visual field. Patients with visual field loss had lower quality of life scores than stroke patients without visual impairment. Conclusions. Stroke survivors with visual field loss require assessment to accurately define type and extent of loss, diagnose coexistent visual impairments, and offer targeted treatment. PMID:24089687

  4. Visual field loss among patients with cytomegalovirus retinitis

    Science.gov (United States)

    Thorne, Jennifer E.; Van Natta, Mark L.; Jabs, Douglas A.; Duncan, Jacque L.; Srivastava, Sunil K.

    2010-01-01

    Purpose To describe visual field (VF) loss among patients with cytomegalovirus (CMV) retinitis and the risk factors for such loss. Design Multicenter, prospective, observational study Participants 476 patients with AIDS and CMV retinitis and VF data Methods Follow-up every 3 months with medical history, ophthalmological examination, Goldman visual fields, and laboratory testing Main outcome measures Incidence of visual field loss in eyes affected with CMV retinitis and characteristics associated with such VF loss Results Over a median follow up of 4 years (range = 0.5 to 9 years), the incidence rates of VF loss to 75% and 50% of normal were 0.22/eye-year (EY, 95% confidence interval [CI]: 0.20, 0.25) and 0.08/EY (95% CI: 0.06, 0.10), respectively. The observed rates were 6- to 7-fold less than those observed rates of VF loss in the era prior to highly active antiretroviral therapy (HAART). Decreased CD4+ T cell count, whether measured at enrollment or over follow up time, was associated with increased rates of VF loss for all VF outcomes in a dose-dependent fashion. Risk factors for VF loss included lower CD4+ T cell count, CMV lesion size >25% of the total retinal area, and active CMV retinitis after controlling for potential confounding. HAART use and immune recovery (CD4+ T cell count >100 cells/μL) were associated with reduced risk of VF loss in multiple regression models. Immune recovery was statistically significantly associated with a lower risk of VF loss to 75% of normal (relative risk [RR] = 0.63 95% CI: 0.49, 0.86 P = 0.003) and to 50% of normal (RR = 0.60 95% CI: 0.44, 0.82 P = 0.001) after controlling for demographic characteristics, human immunodeficiency virus (HIV) viral load, HAART use, CMV lesion location and size, and retinitis activity. Conclusions Cytomegalovirus retinitis was associated with a substantial risk of incident VF loss, but the incidence is approximately 6- fold lower than that observed in the pre-HAART era. Those who have HAART

  5. Segregation of Spontaneous and Training Induced Recovery from Visual Field Defects in Subacute Stroke Patients

    Directory of Open Access Journals (Sweden)

    Douwe P. Bergsma

    2017-12-01

    Full Text Available Whether rehabilitation after stroke profits from an early start is difficult to establish as the contributions of spontaneous recovery and treatment are difficult to tease apart. Here, we use a novel training design to dissociate these components for visual rehabilitation of subacute stroke patients with visual field defects such as hemianopia. Visual discrimination training was started within 6 weeks after stroke in 17 patients. Spontaneous and training-induced recoveries were distinguished by training one-half of the defect for 8 weeks, while monitoring spontaneous recovery in the other (control half of the defect. Next, trained and control regions were swapped, and training continued for another 8 weeks. The same paradigm was also applied to seven chronic patients for whom spontaneous recovery can be excluded and changes in the control half of the defect point to a spillover effect of training. In both groups, field stability was assessed during a no-intervention period. Defect reduction was significantly greater in the trained part of the defect than in the simultaneously untrained part of the defect irrespective of training onset (p = 0.001. In subacute patients, training contributed about twice as much to their defect reduction as the spontaneous recovery. Goal Attainment Scores were significantly and positively correlated with the total defect reduction (p = 0.01, percentage increase reading speed was significantly and positively correlated with the defect reduction induced by training (epoch 1: p = 0.0044; epoch 2: p = 0.023. Visual training adds significantly to the spontaneous recovery of visual field defects, both during training in the early and the chronic stroke phase. However, field recovery as a result of training in this subacute phase was as large as in the chronic phase. This suggests that patients benefited primarily of early onset training by gaining access to a larger visual field sooner.

  6. Vigabatrin : longterm follow-up of electrophysiology and visual field examinations

    NARCIS (Netherlands)

    Hardus, P; Verduin, W; Berendschot, T; Postma, G; Stilma, J; van Veelen, C

    2003-01-01

    Background: To report the results of repeated electrophysiological and visual field examinations in patients with vigabatrin-associated visual field loss (VGB-VFL) and the relationship between these electrophysiological findings, the cumulative dose of vigabatrin and the extent of visual field loss.

  7. Statistical measurements of fast changing electromagnetic fields

    NARCIS (Netherlands)

    Serra, Ramiro; Serra, Ramiro; Leferink, Frank Bernardus Johannes

    2010-01-01

    The present works aims at describing important statistical indexes such as the field uniformity, the field inhomogeneity and the statistics near the cavity walls for a special case of fast changing random electromagnetic fields. We generate this kind of electromagnetic environment by means of a

  8. Correlation between peripapillary retinal nerve fiber layer thickness and visual function changes in patients receiving ethambutol

    Directory of Open Access Journals (Sweden)

    Dialika Dialika

    2015-04-01

    Full Text Available Background: Recent animal studies revealed the decreased amount of retinal ganglion cells after treatment with ethambutol. The aim of this study was to evaluate the changes of peripapillary retinal nerve fiber layer (RNFL thickness in patients receiving ethambutol therapy, as well as to know the correlation of RNFL thickness changes with the changes of visual function.Methods: This was a cohort study on 29 subjects at one tuberculosis treatment center, Jakarta. Subjects underwent RNFL thickness measurement using optical coherence tomography (OCT and several visual function parameters (visual acuity, contrast sensitivity, color sensitivity and visual field before and two-months following ethambutol therapy. Statistical comparison between pre- and post- ethambutol measurements were done using either paired T-test or Wilcoxon test. Correlations between anatomical and functional changes were assessed with Spearman correlation test. Results: There were significant changes of peripapillary RNFL thickness in superior (147 and 141 μm, p = 0.001, nasal (92 and 88 μm, p = 0.045 quadrants and average RNFL thickness (116.77 and 112.65 μm, p = 0.001. No significant correlation between RNFL thickness changes and the changes of visual function parameters (p > 0.05.Conclusion: Ethambutol consumption for two months in recommended dose is still considered safe to human retina and visual status.

  9. Detection and measurement of clinically meaningful visual field progression in clinical trials for glaucoma.

    Science.gov (United States)

    De Moraes, C Gustavo; Liebmann, Jeffrey M; Levin, Leonard A

    2017-01-01

    Glaucomatous visual field progression has both personal and societal costs and therefore has a serious impact on quality of life. At the present time, intraocular pressure (IOP) is considered to be the most important modifiable risk factor for glaucoma onset and progression. Reduction of IOP has been repeatedly demonstrated to be an effective intervention across the spectrum of glaucoma, regardless of subtype or disease stage. In the setting of approval of IOP-lowering therapies, it is expected that effects on IOP will translate into benefits in long-term patient-reported outcomes. Nonetheless, the effect of these medications on IOP and their associated risks can be consistently and objectively measured. This helps to explain why regulatory approval of new therapies in glaucoma has historically used IOP as the outcome variable. Although all approved treatments for glaucoma involve IOP reduction, patients frequently continue to progress despite treatment. It would therefore be beneficial to develop treatments that preserve visual function through mechanisms other than lowering IOP. The United States Food and Drug Administration (FDA) has stated that they will accept a clinically meaningful definition of visual field progression using Glaucoma Change Probability criteria. Nonetheless, these criteria do not take into account the time (and hence, the speed) needed to reach significant change. In this paper we provide an analysis based on the existing literature to support the hypothesis that decreasing the rate of visual field progression by 30% in a trial lasting 12-18 months is clinically meaningful. We demonstrate that a 30% decrease in rate of visual field progression can be reliably projected to have a significant effect on health-related quality of life, as defined by validated instruments designed to measure that endpoint. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Structural and functional changes across the visual cortex of a patient with visual form agnosia.

    Science.gov (United States)

    Bridge, Holly; Thomas, Owen M; Minini, Loredana; Cavina-Pratesi, Cristiana; Milner, A David; Parker, Andrew J

    2013-07-31

    Loss of shape recognition in visual-form agnosia occurs without equivalent losses in the use of vision to guide actions, providing support for the hypothesis of two visual systems (for "perception" and "action"). The human individual DF received a toxic exposure to carbon monoxide some years ago, which resulted in a persisting visual-form agnosia that has been extensively characterized at the behavioral level. We conducted a detailed high-resolution MRI study of DF's cortex, combining structural and functional measurements. We present the first accurate quantification of the changes in thickness across DF's occipital cortex, finding the most substantial loss in the lateral occipital cortex (LOC). There are reduced white matter connections between LOC and other areas. Functional measures show pockets of activity that survive within structurally damaged areas. The topographic mapping of visual areas showed that ordered retinotopic maps were evident for DF in the ventral portions of visual cortical areas V1, V2, V3, and hV4. Although V1 shows evidence of topographic order in its dorsal portion, such maps could not be found in the dorsal parts of V2 and V3. We conclude that it is not possible to understand fully the deficits in object perception in visual-form agnosia without the exploitation of both structural and functional measurements. Our results also highlight for DF the cortical routes through which visual information is able to pass to support her well-documented abilities to use visual information to guide actions.

  11. Visualizing the Entropy Change of a Thermal Reservoir

    Science.gov (United States)

    Langbeheim, Elon; Safran, Samuel A.; Yerushalmi, Edit

    2014-01-01

    When a system exchanges energy with a constant-temperature environment, the entropy of the surroundings changes. A lattice model of a fluid thermal reservoir can provide a visualization of the microscopic changes that occur in the surroundings upon energy transfer from the system. This model can be used to clarify the consistency of phenomena such…

  12. Binocular glaucomatous visual field loss and its impact on visual exploration--a supermarket study.

    Science.gov (United States)

    Sippel, Katrin; Kasneci, Enkelejda; Aehling, Kathrin; Heister, Martin; Rosenstiel, Wolfgang; Schiefer, Ulrich; Papageorgiou, Elena

    2014-01-01

    Advanced glaucomatous visual field loss may critically interfere with quality of life. The purpose of this study was to (i) assess the impact of binocular glaucomatous visual field loss on a supermarket search task as an example of everyday living activities, (ii) to identify factors influencing the performance, and (iii) to investigate the related compensatory mechanisms. Ten patients with binocular glaucoma (GP), and ten healthy-sighted control subjects (GC) were asked to collect twenty different products chosen randomly in two supermarket racks as quickly as possible. The task performance was rated as "passed" or "failed" with regard to the time per correctly collected item. Based on the performance of control subjects, the threshold value for failing the task was defined as μ+3σ (in seconds per correctly collected item). Eye movements were recorded by means of a mobile eye tracker. Eight out of ten patients with glaucoma and all control subjects passed the task. Patients who failed the task needed significantly longer time (111.47 s ±12.12 s) to complete the task than patients who passed (64.45 s ±13.36 s, t-test, p supermarket task. However, a considerable number of patients, who compensate by frequent glancing towards the VFD, showed successful task performance. Therefore, systematic exploration of the VFD area seems to be a "time-effective" compensatory mechanism during the present supermarket task.

  13. High Symmetry of Visual Acuity and Visual Fields in RPGR-Linked Retinitis Pigmentosa.

    Science.gov (United States)

    Bellingrath, Julia-Sophia; Ochakovski, G Alex; Seitz, Immanuel P; Kohl, Susanne; Zrenner, Eberhart; Hanig, Nicola; Prokisch, Holger; Weber, Bernhard H; Downes, Susan M; Ramsden, Simon; MacLaren, Robert E; Fischer, M Dominik

    2017-09-01

    Mutations in retinitis pigmentosa GTPase regulator (RPGR) cause 70% to 90% of X-linked retinitis pigmentosa (XLRP3) cases, making this gene a high-yield target for gene therapy. This study analyzed the utility of relevant clinical biomarkers to assess symmetry and rate of progression in XLRP3. A retrospective, cross-sectional analysis of 50 XLRP3 patients extracted clinical data including visual acuity (VA), visual fields (I4e and III4e targets), foveal thickness, and ERG data points alongside molecular genetic data. Symmetry was assessed by using linear regression analysis. Kaplan-Meier survival curves (KMCs) and generalized linear mixed model calculations were used to describe disease progression. Ninety-six percent of patients exhibited a rod-cone phenotype, and 4% a cone-rod phenotype. Open reading frame 15 (ORF15) was confirmed as a mutational hotspot within RPGR harboring 73% of exonic mutations. Significant variability, but no clear genotype-phenotype relationship, could be shown between mutations located in exons 1-14 versus ORF15. All biomarkers suggested a high degree of symmetry between eyes but demonstrated different estimates of disease progression. VA and foveal thickness, followed by perimetry III4e, were the most useful endpoints to evaluate progression. KMC estimates predicted a loss of 6/6 vision at a mean of 34 years (±2.9; 95% confidence interval). XLRP3 affects retinal structure and function symmetrically, supporting the use of the fellow eye as an internal control in interventional trials. VA and kinetic visual fields (III4e) seem promising functional outcome measures to assess disease progression. KMC analysis predicted the most severe decline in vision between the third and fourth decade of life.

  14. Visual Field Preferences of Object Analysis for Grasping with One Hand

    Directory of Open Access Journals (Sweden)

    Ada eLe

    2014-10-01

    Full Text Available When we grasp an object using one hand, the opposite hemisphere predominantly guides the motor control of grasp movements (Davare et al. 2007; Rice et al. 2007. However, it is unclear whether visual object analysis for grasp control relies more on inputs (a from the contralateral than the ipsilateral visual field, (b from one dominant visual field regardless of the grasping hand, or (c from both visual fields equally. For bimanual grasping of a single object we have recently demonstrated a visual field preference for the left visual field (Le and Niemeier 2013a, 2013b, consistent with a general right-hemisphere dominance for sensorimotor control of bimanual grasps (Le et al., 2013. But visual field differences have never been tested for unimanual grasping. Therefore, here we asked right-handed participants to fixate to the left or right of an object and then grasp the object either with their right or left hand using a precision grip. We found that participants grasping with their right hand performed better with objects in the right visual field: maximum grip apertures (MGAs were more closely matched to the object width and were smaller than for objects in the left visual field. In contrast, when people grasped with their left hand, preferences switched to the left visual field. What is more, MGA scaling showed greater visual field differences compared to right-hand grasping. Our data suggest that, visual object analysis for unimanual grasping shows a preference for visual information from the ipsilateral visual field, and that the left hemisphere is better equipped to control grasps in both visual fields.

  15. Patterns of glaucomatous visual field loss in sita fields automatically identified using independent component analysis.

    Science.gov (United States)

    Goldbaum, Michael H; Jang, Gil-Jin; Bowd, Chris; Hao, Jiucang; Zangwill, Linda M; Liebmann, Jeffrey; Girkin, Christopher; Jung, Tzyy-Ping; Weinreb, Robert N; Sample, Pamela A

    2009-12-01

    To determine if the patterns uncovered with variational Bayesian-independent component analysis-mixture model (VIM) applied to a large set of normal and glaucomatous fields obtained with the Swedish Interactive Thresholding Algorithm (SITA) are distinct, recognizable, and useful for modeling the severity of the field loss. SITA fields were obtained with the Humphrey Visual Field Analyzer (Carl Zeiss Meditec, Inc, Dublin, California) on 1,146 normal eyes and 939 glaucoma eyes from subjects followed by the Diagnostic Innovations in Glaucoma Study and the African Descent and Glaucoma Evaluation Study. VIM modifies independent component analysis (ICA) to develop separate sets of ICA axes in the cluster of normal fields and the 2 clusters of abnormal fields. Of 360 models, the model with the best separation of normal and glaucomatous fields was chosen for creating the maximally independent axes. Grayscale displays of fields generated by VIM on each axis were compared. SITA fields most closely associated with each axis and displayed in grayscale were evaluated for consistency of pattern at all severities. The best VIM model had 3 clusters. Cluster 1 (1,193) was mostly normal (1,089, 95% specificity) and had 2 axes. Cluster 2 (596) contained mildly abnormal fields (513) and 2 axes; cluster 3 (323) held mostly moderately to severely abnormal fields (322) and 5 axes. Sensitivity for clusters 2 and 3 combined was 88.9%. The VIM-generated field patterns differed from each other and resembled glaucomatous defects (eg, nasal step, arcuate, temporal wedge). SITA fields assigned to an axis resembled each other and the VIM-generated patterns for that axis. Pattern severity increased in the positive direction of each axis by expansion or deepening of the axis pattern. VIM worked well on SITA fields, separating them into distinctly different yet recognizable patterns of glaucomatous field defects. The axis and pattern properties make VIM a good candidate as a preliminary process for

  16. 38 CFR 4.76a - Computation of average concentric contraction of visual fields.

    Science.gov (United States)

    2010-07-01

    ... concentric contraction of visual fields. 4.76a Section 4.76a Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS SCHEDULE FOR RATING DISABILITIES Disability Ratings The Organs of Special Sense § 4.76a Computation of average concentric contraction of visual fields. Table III—Normal Visual...

  17. Transfer effects of training-induced visual field recovery in patients with chronic stroke.

    NARCIS (Netherlands)

    Bergsma, D.P.; Elshout, J.A.; Wildt, G.J. van der; Berg, A.V. van den

    2012-01-01

    OBJECTIVE: Visual training of light detection in the transition zone between blind and healthy hemianopic visual fields leads to improvement of color and simple pattern recognition. Recently, we demonstrated that visual field enlargement (VFE) also occurs when an area just beyond the transition zone

  18. Effects of visual-field and matching instruction on event-related potentials and reaction time.

    NARCIS (Netherlands)

    Kok, A.; van de Vijver, R.; Bouma, A.

    1985-01-01

    Vertical letter pairs were presented randomly in the left and right visual hemifields of 20 right-handed male undergraduates in physical-identity match and name-identity match conditions. Reaction times (RTs) showed a right visual-field superiority for name matches and a left visual-field

  19. Receptive fields of visual neurons: the early years.

    Science.gov (United States)

    Spillmann, Lothar

    2014-01-01

    This paper traces the history of the visual receptive field (RF) from Hartline to Hubel and Wiesel. Hartline (1938, 1940) found that an isolated optic nerve fiber in the frog could be excited by light falling on a small circular area of the retina. He called this area the RF, using a term first introduced by Sherrington (1906) in the tactile domain. In 1953 Kuffler discovered the antagonistic center-surround organization of cat RFs, and Barlow, Fitzhugh, and Kuffler (1957) extended this work to stimulus size and state of adaptation. Shortly thereafter, Lettvin and colleagues (1959) in an iconic paper asked "what the frog's eye tells the frog's brain". Meanwhile, Jung and colleagues (1952-1973) searched for the perceptual correlates of neuronal responses, and Jung and Spillmann (1970) proposed the term perceptive field (PF) as a psychophysical correlate of the RF. The Westheimer function (1967) enabled psychophysical measurements of the PF center and surround in human and monkey, which correlated closely with the underlying RF organization. The sixties and seventies were marked by rapid progress in RF research. Hubel and Wiesel (1959-1974), recording from neurons in the visual cortex of the cat and monkey, found elongated RFs selective for the shape, orientation, and position of the stimulus, as well as for movement direction and ocularity. These findings prompted the emergence in visual psychophysics of the concept of feature detectors selective for lines, bars, and edges, and contributed to a model of the RF in terms of difference of Gaussians (DOG) and Fourier channels. The distinction between simple, complex, and hypercomplex neurons followed. Although RF size increases towards the peripheral retina, its cortical representation remains constant due to the reciprocal relationship with the cortical magnification factor (M). This constitutes a uniform yardstick for M-scaled stimuli across the retina. Developmental studies have shown that RF properties are not fixed

  20. GABAA receptors in visual and auditory cortex and neural activity changes during basic visual stimulation

    Science.gov (United States)

    Qin, Pengmin; Duncan, Niall W.; Wiebking, Christine; Gravel, Paul; Lyttelton, Oliver; Hayes, Dave J.; Verhaeghe, Jeroen; Kostikov, Alexey; Schirrmacher, Ralf; Reader, Andrew J.; Northoff, Georg

    2012-01-01

    Recent imaging studies have demonstrated that levels of resting γ-aminobutyric acid (GABA) in the visual cortex predict the degree of stimulus-induced activity in the same region. These studies have used the presentation of discrete visual stimulus; the change from closed eyes to open also represents a simple visual stimulus, however, and has been shown to induce changes in local brain activity and in functional connectivity between regions. We thus aimed to investigate the role of the GABA system, specifically GABAA receptors, in the changes in brain activity between the eyes closed (EC) and eyes open (EO) state in order to provide detail at the receptor level to complement previous studies of GABA concentrations. We conducted an fMRI study involving two different modes of the change from EC to EO: an EO and EC block design, allowing the modeling of the haemodynamic response, followed by longer periods of EC and EO to allow the measuring of functional connectivity. The same subjects also underwent [18F]Flumazenil PET to measure GABAA receptor binding potentials. It was demonstrated that the local-to-global ratio of GABAA receptor binding potential in the visual cortex predicted the degree of changes in neural activity from EC to EO. This same relationship was also shown in the auditory cortex. Furthermore, the local-to-global ratio of GABAA receptor binding potential in the visual cortex also predicted the change in functional connectivity between the visual and auditory cortex from EC to EO. These findings contribute to our understanding of the role of GABAA receptors in stimulus-induced neural activity in local regions and in inter-regional functional connectivity. PMID:23293594

  1. GABAA receptors in visual and auditory cortex and neural activity changes during basic visual stimulation

    Directory of Open Access Journals (Sweden)

    Pengmin eQin

    2012-12-01

    Full Text Available Recent imaging studies have demonstrated that levels of resting GABA in the visual cortex predict the degree of stimulus-induced activity in the same region. These studies have used the presentation of discrete visual stimulus; the change from closed eyes to open also represents a simple visual stimulus, however, and has been shown to induce changes in local brain activity and in functional connectivity between regions. We thus aimed to investigate the role of the GABA system, specifically GABAA receptors, in the changes in brain activity between the eyes closed (EC and eyes open (EO state in order to provide detail at the receptor level to complement previous studies of GABA concentrations. We conducted an fMRI study involving two different modes of the change from EC to EO: An EO and EC block design, allowing the modelling of the haemodynamic response, followed by longer periods of EC and EO to allow the measuring of functional connectivity. The same subjects also underwent [18F]Flumazenil PET measure GABAA receptor binding potentials. It was demonstrated that the local-to-global ratio of GABAA receptor binding potential in the visual cortex predicted the degree of changes in neural activity from EC to EO. This same relationship was also shown in the auditory cortex. Furthermore, the local-to-global ratio of GABAA receptor binding potential in the visual cortex also predicts the change of functional connectivity between visual and auditory cortex from EC to EO. These findings contribute to our understanding of the role of GABAA receptors in stimulus-induced neural activity in local regions and in inter-regional functional connectivity.

  2. Patient with Macular Disease, Good Visual Acuity, and Central Visual Field Disruption and Significant Difficulties with Activities of Daily Living

    Science.gov (United States)

    Fletcher, Donald C.; Schuchard, Ronald A.; Walker, Joseph P.; Raskauskas, Paul A.

    2008-01-01

    It is generally appreciated that patients with macular disease frequently experience reduced visual acuity. It is not as widely appreciated that they often have significant central visual field disruption, which, by itself, can cause significant problems with activities of daily living, such as reading and driving, even when they maintain good…

  3. Accessing long-term memory representations during visual change detection.

    Science.gov (United States)

    Beck, Melissa R; van Lamsweerde, Amanda E

    2011-04-01

    In visual change detection tasks, providing a cue to the change location concurrent with the test image (post-cue) can improve performance, suggesting that, without a cue, not all encoded representations are automatically accessed. Our studies examined the possibility that post-cues can encourage the retrieval of representations stored in long-term memory (LTM). Participants detected changes in images composed of familiar objects. Performance was better when the cue directed attention to the post-change object. Supporting the role of LTM in the cue effect, the effect was similar regardless of whether the cue was presented during the inter-stimulus interval, concurrent with the onset of the test image, or after the onset of the test image. Furthermore, the post-cue effect and LTM performance were similarly influenced by encoding time. These findings demonstrate that monitoring the visual world for changes does not automatically engage LTM retrieval.

  4. Visualizing the Impact of Climate Change with GAIA

    Science.gov (United States)

    Strong, S. B.; Schaefer, R. K.; Kaushiva, A.; Paxton, L. J.; Higgins, A.

    2011-12-01

    The Johns Hopkins University Applied Physics Laboratory is creating an interdisciplinary, collaborative environment to address the impact of climate change on national interests through the Global Assimilation of Information for Action (GAIA) project. The purpose of the GAIA collective is to explore consequences, gaps, and resolutions for specific concerns arising from a changing climate. As part of this exploration, we have begun to develop visualization tools and techniques to illustrate the impact of climate change on subjects ranging from public health to crop production with the intention to better inform scientists, policy-makers, educators, and the public. Here, we present key features of the GAIA visualization website and highlight specific, simplified methods of using climate model, medical, and meteorological data to illustrate the impact of climate change on individuals and society. The GAIA website can be used as a resource for individuals to add information relevant to visualization tools and discuss the use of tools and data in varying contexts. Simple and concise analysis and visualization is required to emphasize the critical importance of climate change adaptation strategies.

  5. Changing fields of rationality - a policy for change?

    Energy Technology Data Exchange (ETDEWEB)

    Strumse, Einar; Westskog, Hege; Winther, Tanja

    2010-07-01

    Work objective: To analyze effective strategies for changing households' energy consumption based on an interdisciplinary model for understanding change. Methodology: In this paper we develop a conceptual model for understanding individuals' energy consumption. We synthesize insights from anthropology, social psychology and economics grasping perspectives from behaviour to practice and from the Bourdieu's fields to rationality thinking in economics. We use this insight to analyze strategies for change. Abstract: In this paper we analyze effective strategies for changing households' energy consumption based on an interdisciplinary model for understanding change. The model focuses on four main categories for understanding individual consumption: a. Material constraints b. Values and identity c. Norms d. Ability These are the main influencing factors of the individual's consumption level, but in interaction with the corresponding group and the societal levels for the same factors. The model can be illustrated. One combination of factors on all levels constitutes a field of rationality. We claim that an important strategy for changing energy consumption towards sustainability is changing the field of rationality of the individual. Changing of rationality fields would from our point of view initiate reflection which is an important condition for changed behavior. One example of changing of fields is information measures that relates energy consumption to the 'citizen' field rather than the 'consumer' field. Hence, according to our conceptual framework - how policy should be framed (information measures for instance ) would be an important knowledge area for design of effective policy measures. (Author)

  6. The relationship between better-eye and integrated visual field mean deviation and visual disability.

    Science.gov (United States)

    Arora, Karun S; Boland, Michael V; Friedman, David S; Jefferys, Joan L; West, Sheila K; Ramulu, Pradeep Y

    2013-12-01

    To determine the extent of difference between better-eye visual field (VF) mean deviation (MD) and integrated VF (IVF) MD among Salisbury Eye Evaluation (SEE) subjects and a larger group of glaucoma clinic subjects and to assess how those measures relate to objective and subjective measures of ability/performance in SEE subjects. Retrospective analysis of population- and clinic-based samples of adults. A total of 490 SEE and 7053 glaucoma clinic subjects with VF loss (MD ≤-3 decibels [dB] in at least 1 eye). Visual field testing was performed in each eye, and IVF MD was calculated. Differences between better-eye and IVF MD were calculated for SEE and clinic-based subjects. In SEE subjects with VF loss, models were constructed to compare the relative impact of better-eye and IVF MD on driving habits, mobility, self-reported vision-related function, and reading speed. Difference between better-eye and IVF MD and relationship of better-eye and IVF MD with performance measures. The median difference between better-eye and IVF MD was 0.41 dB (interquartile range [IQR], -0.21 to 1.04 dB) and 0.72 dB (IQR, 0.04-1.45 dB) for SEE subjects and clinic-based patients with glaucoma, respectively, with differences of ≥ 2 dB between the 2 MDs observed in 9% and 18% of the groups, respectively. Among SEE subjects with VF loss, both MDs demonstrated similar associations with multiple ability and performance metrics as judged by the presence/absence of a statistically significant association between the MD and the metric, the magnitude of observed associations (odds ratios, rate ratios, or regression coefficients associated with 5-dB decrements in MD), and the extent of variability in the metric explained by the model (R(2)). Similar associations of similar magnitude also were noted for the subgroup of subjects with glaucoma and subjects in whom better-eye and IVF MD differed by ≥ 2 dB. The IVF MD rarely differs from better-eye MD, and similar associations between VF loss and

  7. Testing the Visual Soil Assessment tool on Estonian farm fields

    Science.gov (United States)

    Reintam, Endla; Are, Mihkel; Selge, Are

    2017-04-01

    Soil quality estimation plays important role in decision making on farm as well on policy level. Sustaining the production ability and good health of the soil the chemical, physical and biological indicators should be taken into account. The system to use soil chemical parameters is usually quite well established in most European counties, including Estonia. However, measuring soil physical properties, such bulk density, porosity, penetration resistance, structural stability ect is time consuming, needs special tools and is highly weather dependent. In that reason these parameters are excluded from controllable quality parameters in policy in Estonia. Within the project "Interactive Soil Quality Assessment in Europe and China for Agricultural Productivity and Environmental Resilience" (iSQAPER) the visual soil assessment (VSA) tool was developed for easy detection of soil quality as well the different soil friendly agricultural management practices (AMP) were detected. The aim of current study was to test the VSA tool on Estonian farm fields under different management practices and compare the results with laboratory measurements. The main focus was set on soil physical parameters. Next to the VSA, the undisturbed soil samples were collected from the depth of 5-10 cm and 25-30 cm. The study revealed that results of a visually assessed soil physical parameters, such a soil structure, soil structural stability, soil porosity, presence of tillage pan, were confirmed by laboratory measurements in most cases. Soil water stable structure measurement on field (on 1 cm2 net in one 1 l box with 4-6 cm air dry clods for 5-10 min) underestimated very well structured soil on grassland and overestimated the structure aggregates stability of compacted soil. The slightly better soil quality was detected under no-tillage compared to ploughed soils. However, the ploughed soil got higher quality points compared with minimum tillage. The slurry application (organic manuring) had

  8. Differences in visuomotor control between the upper and lower visual fields.

    Science.gov (United States)

    Khan, Michael A; Lawrence, Gavin P

    2005-07-01

    Danckert and Goodale [Exp Brain Res 137:303-308 (2001)] have shown that increases in movement time as target size decreased were greater when movements were performed in the lower compared with upper visual field. On this basis, they suggested that visual feedback processing was more effective in the lower visual field. However, despite the greater influence of target size on movement time for the lower compared to upper visual field, there were no differences in accuracy between visual fields for movements to the smallest targets. In the present study, we investigated whether superior performance would be observed in the lower visual field when movement times were constrained. Analysis of the variability in distance travelled at key kinematic markers (e.g. peak acceleration, peak velocity, and peak negative acceleration) revealed that limb trajectories were more consistent in the lower compared to upper visual field at the late stages of the movement. Also, squared correlation coefficients between the distance travelled at peak velocity and the distance at the end of the movement were smaller for movements performed in the lower visual field. These results imply that superior performance in the lower visual field was due to better utilization of visual feedback during movement execution.

  9. Visual Working Memory Load-Related Changes in Neural Activity and Functional Connectivity

    Science.gov (United States)

    Li, Ling; Zhang, Jin-Xiang; Jiang, Tao

    2011-01-01

    Background Visual working memory (VWM) helps us store visual information to prepare for subsequent behavior. The neuronal mechanisms for sustaining coherent visual information and the mechanisms for limited VWM capacity have remained uncharacterized. Although numerous studies have utilized behavioral accuracy, neural activity, and connectivity to explore the mechanism of VWM retention, little is known about the load-related changes in functional connectivity for hemi-field VWM retention. Methodology/Principal Findings In this study, we recorded electroencephalography (EEG) from 14 normal young adults while they performed a bilateral visual field memory task. Subjects had more rapid and accurate responses to the left visual field (LVF) memory condition. The difference in mean amplitude between the ipsilateral and contralateral event-related potential (ERP) at parietal-occipital electrodes in retention interval period was obtained with six different memory loads. Functional connectivity between 128 scalp regions was measured by EEG phase synchronization in the theta- (4–8 Hz), alpha- (8–12 Hz), beta- (12–32 Hz), and gamma- (32–40 Hz) frequency bands. The resulting matrices were converted to graphs, and mean degree, clustering coefficient and shortest path length was computed as a function of memory load. The results showed that brain networks of theta-, alpha-, beta-, and gamma- frequency bands were load-dependent and visual-field dependent. The networks of theta- and alpha- bands phase synchrony were most predominant in retention period for right visual field (RVF) WM than for LVF WM. Furthermore, only for RVF memory condition, brain network density of theta-band during the retention interval were linked to the delay of behavior reaction time, and the topological property of alpha-band network was negative correlation with behavior accuracy. Conclusions/Significance We suggest that the differences in theta- and alpha- bands between LVF and RVF conditions in

  10. Visual working memory load-related changes in neural activity and functional connectivity.

    Directory of Open Access Journals (Sweden)

    Ling Li

    Full Text Available BACKGROUND: Visual working memory (VWM helps us store visual information to prepare for subsequent behavior. The neuronal mechanisms for sustaining coherent visual information and the mechanisms for limited VWM capacity have remained uncharacterized. Although numerous studies have utilized behavioral accuracy, neural activity, and connectivity to explore the mechanism of VWM retention, little is known about the load-related changes in functional connectivity for hemi-field VWM retention. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we recorded electroencephalography (EEG from 14 normal young adults while they performed a bilateral visual field memory task. Subjects had more rapid and accurate responses to the left visual field (LVF memory condition. The difference in mean amplitude between the ipsilateral and contralateral event-related potential (ERP at parietal-occipital electrodes in retention interval period was obtained with six different memory loads. Functional connectivity between 128 scalp regions was measured by EEG phase synchronization in the theta- (4-8 Hz, alpha- (8-12 Hz, beta- (12-32 Hz, and gamma- (32-40 Hz frequency bands. The resulting matrices were converted to graphs, and mean degree, clustering coefficient and shortest path length was computed as a function of memory load. The results showed that brain networks of theta-, alpha-, beta-, and gamma- frequency bands were load-dependent and visual-field dependent. The networks of theta- and alpha- bands phase synchrony were most predominant in retention period for right visual field (RVF WM than for LVF WM. Furthermore, only for RVF memory condition, brain network density of theta-band during the retention interval were linked to the delay of behavior reaction time, and the topological property of alpha-band network was negative correlation with behavior accuracy. CONCLUSIONS/SIGNIFICANCE: We suggest that the differences in theta- and alpha- bands between LVF and RVF

  11. Moving to higher ground: The dynamic field theory and the dynamics of visual cognition.

    Science.gov (United States)

    Johnson, Jeffrey S; Spencer, John P; Schöner, Gregor

    2008-08-01

    In the present report, we describe a new dynamic field theory that captures the dynamics of visuo-spatial cognition. This theory grew out of the dynamic systems approach to motor control and development, and is grounded in neural principles. The initial application of dynamic field theory to issues in visuo-spatial cognition extended concepts of the motor approach to decision making in a sensori-motor context, and, more recently, to the dynamics of spatial cognition. Here we extend these concepts still further to address topics in visual cognition, including visual working memory for non-spatial object properties, the processes that underlie change detection, and the 'binding problem' in vision. In each case, we demonstrate that the general principles of the dynamic field approach can unify findings in the literature and generate novel predictions. We contend that the application of these concepts to visual cognition avoids the pitfalls of reductionist approaches in cognitive science, and points toward a formal integration of brains, bodies, and behavior.

  12. Effect of osteopathy in the cranial field on visual function--a pilot study.

    Science.gov (United States)

    Sandhouse, Mark E; Shechtman, Diana; Sorkin, Richard; Drowos, Joanna Lauren; Caban-Martinez, Alberto J; Patterson, Michael M; Shallo-Hoffmann, Josephine; Hardigan, Patrick; Snyder, Arthur

    2010-04-01

    The effects of osteopathy in the cranial field on visual function-particularly on changes in the visual field and on the binocular alignment of the eyes-have been poorly characterized in the literature. The authors examined whether osteopathy in the cranial field resulted in an immediate, measurable change in visual function among a sample of adults with cranial asymmetry. Randomized controlled double-blinded pilot clinical trial. Adult volunteers between ages 18 and 35 years who were free of strabismus or active ocular or systemic disease were recruited. Inclusion criteria were refractive error ranging between six diopters of myopia and five diopters of hyperopia, regular astigmatism of any amount, and cranial somatic dysfunction. All subjects were randomly assigned to the treatment or control group. The treatment group received a single intervention of osteopathy in the cranial field to correct cranial dysfunction. The control group received light pressure of a few ounces of force applied to the cranium without osteopathic manipulative treatment. Preintervention and postintervention optometric examinations consisted of distant visual acuity testing, Donder push-up (ie, accommodative system) testing, local stereoacuity testing, pupillary size measurements, and vergence system (ie, cover test with prism neutralization, near point of convergence) testing. Global stereoacuity testing and retinoscopy were performed only in preintervention to determine whether subjects met inclusion criteria. Analysis of variance (ANOVA) was performed for all ocular measures. Twenty-nine subjects completed the trial-15 in the treatment group and 14 in the control group. A hierarchical ANOVA revealed statistically significant effects within the treatment group and within the control group (P visual acuity of the right eye (OD) and left eye (OS), local stereoacuity, pupillary size measured under dim illumination OD and OS, and near point of convergence break and recovery. For the

  13. Temporal modulation visual fields, normal aging, Parkinson's disease and methyl-mercury in the James Bay Cree: a feasibility study

    Directory of Open Access Journals (Sweden)

    Jocelyn Faubert

    2003-01-01

    Full Text Available We assessed temporal modulation visual fields (TMFs for 91 observers including controls, Parkinson patients and members of the James Bay Cree community of Northern Québec suspected of being chronically exposed to relatively low levels of methyl-mercury. The main goal was to establish the feasibility of using such procedures to rapidly evaluate visual function in a large field study with the James Bay Cree community. The results show clear normal aging effects on TMFs and the pattern of loss differed depending on the flicker rates used. Group data comparisons between the controls and the experimental groups showed significant effects only between the Cree and normal controls in the 40 to 49 year-old age category for the low temporal frequency condition (2 Hz. Examples of individual analysis shows a Cree observer with severe visual field constriction at the 2 Hz condition with a normal visual field at the 16 Hz condition and a reverse pattern was demonstrated for a Parkinson's patient where a visual field constriction was evident only for the 16 Hz condition. The general conclusions are: Such a technique can be used to evaluate the visual consequences of neuropathological disorders and it may lead to dissociation between certain neurotoxic and neurodegenerative effects depending on the parameters used; this technique can be used for a large field study because it is rapid and easily understood and performed by the subjects; the TMF procedure used showed good test-retest correlations; normal aging causes changes in TMF profiles but the changes will show different patterns throughout the visual field depending on the parameters used.

  14. Early event related fields during visually evoked pain anticipation.

    Science.gov (United States)

    Gopalakrishnan, Raghavan; Burgess, Richard C; Plow, Ela B; Floden, Darlene P; Machado, Andre G

    2016-03-01

    Pain experience is not only a function of somatosensory inputs. Rather, it is strongly influenced by cognitive and affective pathways. Pain anticipatory phenomena, an important limitation to rehabilitative efforts in the chronic state, are processed by associative and limbic networks, along with primary sensory cortices. Characterization of neurophysiological correlates of pain anticipation, particularly during very early stages of neural processing is critical for development of therapeutic interventions. Here, we utilized magnetoencephalography to study early event-related fields (ERFs) in healthy subjects exposed to a 3 s visual countdown task that preceded a painful stimulus, a non-painful stimulus or no stimulus. We found that the first countdown cue, but not the last cue, evoked critical ERFs signaling anticipation, attention and alertness to the noxious stimuli. Further, we found that P2 and N2 components were significantly different in response to first-cues that signaled incoming painful stimuli when compared to non-painful or no stimuli. The findings indicate that early ERFs are relevant neural substrates of pain anticipatory phenomena and could be potentially serve as biomarkers. These measures could assist in the development of neurostimulation approaches aimed at curbing the negative effects of pain anticipation during rehabilitation. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  15. Action video game players and deaf observers have larger Goldmann visual fields.

    Science.gov (United States)

    Buckley, David; Codina, Charlotte; Bhardwaj, Palvi; Pascalis, Olivier

    2010-03-05

    We used Goldmann kinetic perimetry to compare how training and congenital auditory deprivation may affect the size of the visual field. We measured the ability of action video game players and deaf observers to detect small moving lights at various locations in the central (around 30 degrees from fixation) and peripheral (around 60 degrees ) visual fields. Experiment 1 found that 10 habitual video game players showed significantly larger central and peripheral field areas than 10 controls. In Experiment 2 we found that 13 congenitally deaf observers had significantly larger visual fields than 13 hearing controls for both the peripheral and central fields. Here the greatest differences were found in the lower parts of the fields. Comparison of the two groups showed that whereas VGP players have a more uniform increase in field size in both central and peripheral fields deaf observers show non-uniform increases with greatest increases in lower parts of the visual field.

  16. Homonymous Visual Field Loss and Its Impact on Visual Exploration: A Supermarket Study.

    Science.gov (United States)

    Kasneci, Enkelejda; Sippel, Katrin; Heister, Martin; Aehling, Katrin; Rosenstiel, Wolfgang; Schiefer, Ulrich; Papageorgiou, Elena

    2014-10-01

    Homonymous visual field defects (HVFDs) may critically interfere with quality of life. The aim of this study was to assess the impact of HVFDs on a supermarket search task and to investigate the influence of visual search on task performance. Ten patients with HVFDs (four with a right-sided [HR] and six with a left-sided defect [HL]), and 10 healthy-sighted, sex-, and age-matched control subjects were asked to collect 20 products placed on two supermarket shelves as quickly as possible. Task performance was rated as "passed" or "failed" with regard to the time per correctly collected item (TC -failed = 4.84 seconds based on the performance of healthy subjects). Eye movements were analyzed regarding the horizontal gaze activity, glance frequency, and glance proportion for different VF areas. Seven of 10 HVFD patients (three HR, four HL) passed the supermarket search task. Patients who passed needed significantly less time per correctly collected item and looked more frequently toward the VFD area than patients who failed. HL patients who passed the test showed a higher percentage of glances beyond the 60° VF (P < 0.05). A considerable number of HVFD patients performed successfully and could compensate for the HVFD by shifting the gaze toward the peripheral VF and the VFD area. These findings provide new insights on gaze adaptations in patients with HVFDs during activities of daily living and will enhance the design and development of realistic examination tools for use in the clinical setting to improve daily functioning. (http://www.clinicaltrials.gov, NCT01372319, NCT01372332).

  17. Splitting Attention across the Two Visual Fields in Visual Short-Term Memory

    Science.gov (United States)

    Delvenne, Jean-Francois; Holt, Jessica L.

    2012-01-01

    Humans have the ability to attentionally select the most relevant visual information from their extrapersonal world and to retain it in a temporary buffer, known as visual short-term memory (VSTM). Research suggests that at least two non-contiguous items can be selected simultaneously when they are distributed across the two visual hemifields. In…

  18. The accuracy of confrontation visual field test in comparison with automated perimetry.

    Science.gov (United States)

    Johnson, L. N.; Baloh, F. G.

    1991-01-01

    The accuracy of confrontation visual field testing was determined for 512 visual fields using automated static perimetry as the reference standard. The sensitivity of confrontation testing excluding patchy defects was 40% for detecting anterior visual field defects, 68.3% for posterior defects, and 50% for both anterior and posterior visual field defects combined. The sensitivity within each group varied depending on the type of visual field defect encountered. Confrontation testing had a high sensitivity (75% to 100%) for detecting altitudinal visual loss, central/centrocecal scotoma, and homonymous hemianopsia. Confrontation testing was fairly insensitive (20% to 50% sensitivity) for detecting arcuate scotoma and bitemporal hemianopsia. The specificity of confrontation testing was high at 93.4%. The high positive predictive value (72.6%) and negative predictive value (75.7%) would indicate that visual field defects identified during confrontation testing are often true visual field defects. However, the many limitations of confrontation testing should be remembered, particularly its low sensitivity for detecting visual field loss associated with parasellar tumors, glaucoma, and compressive optic neuropathies. PMID:1800764

  19. Effects of Field of View and Visual Complexity on Virtual Reality Training Effectiveness for a Visual Scanning Task.

    Science.gov (United States)

    Ragan, Eric D; Bowman, Doug A; Kopper, Regis; Stinson, Cheryl; Scerbo, Siroberto; McMahan, Ryan P

    2015-07-01

    Virtual reality training systems are commonly used in a variety of domains, and it is important to understand how the realism of a training simulation influences training effectiveness. We conducted a controlled experiment to test the effects of display and scenario properties on training effectiveness for a visual scanning task in a simulated urban environment. The experiment varied the levels of field of view and visual complexity during a training phase and then evaluated scanning performance with the simulator's highest levels of fidelity and scene complexity. To assess scanning performance, we measured target detection and adherence to a prescribed strategy. The results show that both field of view and visual complexity significantly affected target detection during training; higher field of view led to better performance and higher visual complexity worsened performance. Additionally, adherence to the prescribed visual scanning strategy during assessment was best when the level of visual complexity during training matched that of the assessment conditions, providing evidence that similar visual complexity was important for learning the technique. The results also demonstrate that task performance during training was not always a sufficient measure of mastery of an instructed technique. That is, if learning a prescribed strategy or skill is the goal of a training exercise, performance in a simulation may not be an appropriate indicator of effectiveness outside of training-evaluation in a more realistic setting may be necessary.

  20. Comparison of retinal nerve fibre layer thickness with visual evoked potential and visual field in patients with multiple sclerosis.

    Science.gov (United States)

    Alpay, Atilla; Guney, Tuncer; Unal, Aysun; Ugurbas, Suat H

    2012-01-01

    To evaluate retinal nerve fibre layer thickness and to compare results with visual evoked potentials and visual field in patients with multiple sclerosis. A prospective, case-control study, university hospital setting. Seventy-three eyes of 37 multiple sclerosis patients and 74 eyes of 37 healthy subjects. All patients underwent a complete neurological and ophthalmological examination and peri-papillary retinal nerve fibre layer thickness was evaluated using scanning laser polarimetry (GDx). Furthermore, visual evoked potential and visual field testing were performed. The χ(2) test, Student's t-test, Mann-Whitney U-test and Pearson's correlation coefficient analysis of the GDx, visual evoked potential and visual field testing parameters. GDx measurements showed significantly more retinal nerve fibre layer damage in the patients than in the control groups. Comparison of the GDx parameters between patients with optic neuritis and non-optic neuritis demonstrated a statistically significant difference in symmetry (P = 0.046) and superior/nasal parameters (P = 0.009). A correlation was found between the number, superior and inferior ratio parameters, and P100 amplitude obtained with visual evoked potential in patients with non-optic neuritis. Additionally, there was a correlation between the number, inferior ratio and superior/nasal parameters, and the mean deviation of visual field in the non-optic neuritis group. For retinal nerve fibre layer thickness measurements in multiple sclerosis patients, the GDx, along with other techniques, such as visual evoked potential, can be used as a diagnostic and follow-up criterion, particularly in patients without optic neuritis. © 2011 The Authors. Clinical and Experimental Ophthalmology © 2011 Royal Australian and New Zealand College of Ophthalmologists.

  1. Optic nerve head morphology and visual field function in patients with AIDS and without infectious retinitis.

    Science.gov (United States)

    Kozak, Igor; Ahuja, Alka; Gangaputra, Sapna; Van Natta, Mark L; Thorne, Jennifer E; Freeman, William R

    2012-10-01

    To evaluate morphology of the optic nerve head and visual field in AIDS patients without retinitis. One randomly selected eye from 246 patients with AIDS without retinitis was evaluated from prospective multicenter Longitudinal Studies of Ocular Complications of AIDS. Stereo fundus photographs of OHN and serial VF data over 5-years were analyzed. Main outcomes included vertical cup-to-disc ratio (CDR), mean deviation, and pattern standard deviation scores on VF testing. The median CDR was 0.39 at enrollment and 0.40 at 5-year follow-up. An unadjusted linear regression model revealed a mean change in CDR of 0.004 after 5-years (P = 0.04). After adjustment for practice effect, there were no statistically significant changes in VF performance observed during the 5 years of follow-up. We detected clinically minimal, but statistically significant changes in ONH morphology and no change in VF performance among eyes of patients with AIDS and without retinitis.

  2. Negative Body Image Associated with Changes in the Visual Body Appearance Increases Pain Perception: e107376

    National Research Council Canada - National Science Library

    Michihiro Osumi; Ryota Imai; Kozo Ueta; Satoshi Nobusako; Shu Morioka

    2014-01-01

    .... We hypothesized that a negative body image associated with changing the visual body appearance causes interindividual differences in the analgesic effect although the relationship between the visual...

  3. Negative body image associated with changes in the visual body appearance increases pain perception

    National Research Council Canada - National Science Library

    Osumi, Michihiro; Imai, Ryota; Ueta, Kozo; Nobusako, Satoshi; Morioka, Shu

    2014-01-01

    .... We hypothesized that a negative body image associated with changing the visual body appearance causes interindividual differences in the analgesic effect although the relationship between the visual...

  4. Visual dependence affects postural sway responses to continuous visual field motion in individuals with cerebral palsy.

    Science.gov (United States)

    Yu, Yawen; Lauer, Richard T; Tucker, Carole A; Thompson, Elizabeth D; Keshner, Emily A

    2018-01-17

    The current study aimed to explore the impact of visual dependence on sensorimotor coupling of postural sway and visual motion in adults and teens with spastic cerebral palsy (CP). We hypothesized that individuals with CP would exhibit greater magnitudes of sway than healthy individuals, and the presence of visual dependence (VD) would produce instability in the direction of visual motion. Participants stood in a virtual environment in which the visual scene remained static or continuously rotated 30 degree/second in pitch-up or pitch-down. Increased center of pressure and center of mass responses were observed in the direction of visual scene motion in those with CP. Those with VD exhibited reduced frequency responses in anterior-posterior direction than those who were visually independent. VD suggests deficient sensorimotor integration that could contribute to postural instability and reduced motor function. Individuals with CP who are visually dependent may benefit from more sensory focused rehabilitation strategies. AP, anterior-posterior; CP, cerebral palsy; COM, center of mass; COP, center of pressure; MDF, median frequency; ML, mediolateral; PD, pitch down (nose down) rotation; PU, pitch up (nose up) rotation; RFT, rod and frame test; RMS, root mean square; SLP, slope of the fitted line; TD, typical development; VD, visual dependence; VI, visual independence; VOR, vestibulo-ocular reflex; VPI, visual perceptual impairment.

  5. Colour, face, and visuospatial imagery abilities in low-vision individuals with visual field deficits.

    Science.gov (United States)

    Dulin, David; Cavezian, Céline; Serrière, Coline; Bachoud-Levi, Anne-Catherine; Bartolomeo, Paolo; Chokron, Sylvie

    2011-10-01

    This study investigates to what extent visual perception integrity is necessary for visual mental imagery. Sixteen low-vision participants with severe peripheral visual field loss, 16 with severe central field loss, 6 left brain-damaged patients with right homonymous hemianopia, 6 right brain-damaged patients with left homonymous hemianopia, and 16 normally sighted controls performed perceptual and imagery tasks using colours, faces, and spatial relationships. Results showed that (a) the perceptual and mental image>ry disorders vary according to the type of visual field loss, (b) hemianopics had no more difficulties imagining spatial stimuli in their contralesional hemispace than in their ipsilesional one, and (c) the only hemianopic participant to have perceptual and mental imagery impairments suffered from attentional deficits. Results suggest that (a) visual memory is not definitively established, but rather needs perceptual practice to be maintained, and (b) that visual mental imagery may involve some of the attentional-exploratory mechanisms that are employed in visual behaviour.

  6. About the Role of Visual Field Defects in Pure Alexia

    Science.gov (United States)

    Pflugshaupt, Tobias; Gutbrod, Klemens; Wurtz, Pascal; von Wartburg, Roman; Nyffeler, Thomas; de Haan, Bianca; Karnath, Hans-Otto; Mueri, Rene M.

    2009-01-01

    Pure alexia is an acquired reading disorder characterized by a disproportionate prolongation of reading time as a function of word length. Although the vast majority of cases reported in the literature show a right-sided visual defect, little is known about the contribution of this low-level visual impairment to their reading difficulties. The…

  7. Visual business ecosystem intelligence: lessons from the field.

    Science.gov (United States)

    Basole, Rahul C

    2014-01-01

    Macroscopic insight into business ecosystems is becoming increasingly important. With the emergence of new digital business data, opportunities exist to develop rich, interactive visual-analytics tools. Georgia Institute of Technology researchers have been developing and implementing visual business ecosystem intelligence tools in corporate settings. This article discusses the challenges they faced, the lessons learned, and opportunities for future research.

  8. Corneal hysteresis and visual field asymmetry in open angle glaucoma.

    Science.gov (United States)

    Anand, Aashish; De Moraes, Carlos Gustavo V; Teng, Christopher C; Tello, Celso; Liebmann, Jeffrey M; Ritch, Robert

    2010-12-01

    To investigate the association between corneal biomechanical parameters and asymmetric primary open angle glaucoma (POAG) using the Ocular Response Analyzer (ORA). In a prospective cross-sectional study, ORA parameters were measured in 117 POAG patients with asymmetric visual fields (VF). The asymmetry in VF was defined as a five point difference between the eyes using the Advanced Glaucoma Intervention Study (AGIS) scoring system. Subjects with previous intraocular or refractive surgery, ocular comorbidities and diabetes were excluded. In worse eyes, mean AGIS scores were significantly higher (8.1 ± 4.3 vs. 1.0 ± 1.6; P corneal hysteresis (CH) was significantly lower (8.2 ± 1.9 vs. 8.9 ± 1.9 mm Hg; P corneal resistance factor (P = 0.04) and more myopic mean spherical equivalent (P = 0.02). No difference was seen in the central corneal thickness (CCT; P = 0.63) and Goldmann applanation tonometry (GAT; P = 0.32). On multivariate analysis, only CH retained an association with the worse eye (odds ratio, 25.9; 95% confidence interval, 10.1-66.5). ROC curves showed that only CH and IOP(cc) had a discriminative ability for the eye with worse VF (AUC, 0.82 and 0.70, respectively). Asymmetric POAG was associated with asymmetry in ORA parameters but not in CCT and GAT. Lower CH was associated with worse eyes independently of its effect on IOP measurement and had the best discriminability for the eye with the worse VF.

  9. The effects of compensatory scanning training on mobility in patients with homonymous visual field defects : A randomized controlled Trial

    NARCIS (Netherlands)

    de Haan, Gera; Melis-Dankers, Bart; Brouwer, Wiebo; Tucha, Oliver; Heutink, Joost

    2015-01-01

    Background: Homonymous visual field defects (HVFD) are a common consequence of postchiasmatic acquired brain injury and often lead to mobility-related difficulties. Different types of compensatory scanning training have been developed, aimed at decreasing consequences of the HVFD by changing the use

  10. Identity-expression interaction in face perception: sex, visual field, and psychophysical factors.

    Science.gov (United States)

    Godard, Ornella; Baudouin, Jean-Yves; Bonnet, Philippe; Fiori, Nicole

    2013-01-01

    We investigated the psychophysical factors underlying the identity-emotion interaction in face perception. Visual field and sex were also taken into account. Participants had to judge whether a probe face, presented in either the left or the right visual field, and a central target face belonging to same person while emotional expression varied (Experiment 1) or to judge whether probe and target faces expressed the same emotion while identity was manipulated (Experiment 2). For accuracy we replicated the mutual facilitation effect between identity and emotion; no sex or hemispheric differences were found. Processing speed measurements, however, showed a lesser degree of interference in women than in men, especially for matching identity when faces expressed different emotions after a left visual presentation probe face. Psychophysical indices can be used to determine whether these effects are perceptual (A') or instead arise at a post-perceptual decision-making stage (B"). The influence of identity on the processing of facial emotion seems to be due to perceptual factors, whereas the influence of emotion changes on identity processing seems to be related to decisional factors. In addition, men seem to be more "conservative" after a LVF/RH probe-face presentation when processing identity. Women seem to benefit from better abilities to extract facial invariant aspects relative to identity.

  11. The effect of visual field defects on eye movements and practical fitness to drive

    NARCIS (Netherlands)

    Coeckelbergh, TRM; Cornelissen, FW; Brouwer, WH; Kooijman, AC

    Eye movements Of Subjects with visual field defects due to ocular pathology were monitored while performing a dot counting task and a visual search task. Subjects with peripheral field defects required more fixations, longer search times, made more errors. and had shorter fixation durations than

  12. Perimetry in young and neurologically impaired children : The Behavioral Visual Field (BEFIE) Screening Test revisited

    NARCIS (Netherlands)

    Koenraads, Yvonne; Braun, Kees P J; Van Der Linden, Denise C P; Imhof, Saskia M.; Porro, Giorgio L.

    IMPORTANCE: Visual field examination in young or neurologically impaired children is a challenge. As a result, the Behavioral Visual Field (BEFIE) Screening Test was developed in 1995. OBJECTIVES: To evaluate the applicability of the BEFIE test in a large population of young or neurologically

  13. Active Learning in Neuroscience: A Manipulative to Simulate Visual Field Defects

    Science.gov (United States)

    Li, Andrew Yue-Lin; Carvalho, Helena

    2016-01-01

    Prevalent in 20-57% of stroke patients, visual field defects have been shown to impact quality of life. Studies have shown increased risk of falling, ambulatory difficulties, impaired reading ability, and feelings of panic in crowded or unfamiliar places in patients with visual field defects. Rehabilitation, independence, and mental health may…

  14. Seeing without the Occipito-Parietal Cortex: Simultagnosia as a Shrinkage of the Attentional Visual Field

    OpenAIRE

    Michel, Fran?ois; Henaff, Marie-Anne

    2004-01-01

    Following bi-parietal lesions patient AT showed a severe inability to relocate her attention within a visual field which perimetry proved to be near-normal. An experimental approach with tasks testing visuo-spatial attention demonstrated a shrinkage of A.T.’s attentional visual field. With her visual attention narrowed to a kind of functional tunnel vision, the patient exhibited simultanagnosia (Wolpert, 1924), a symptom previously described in 1909 by Balint under the label of Psychic paraly...

  15. Between the Text and the Image. The Changes of the (Fairy Tale) Narrative in Visual Communication

    OpenAIRE

    Ovčáčková, Johanka

    2015-01-01

    Between the Text and the Image / The Changes of the (Fairy Tale) Narrative in Visual Communication KEY WORDS / Culture, Semiotic, Visuality, Empirical Spectator, Sign, Interpretation, Fairy Tale Narrative, Everydayness, Thinking, Visual Literacy, Communicatin, Advertisment, Commercial Communi- cation, Visual Communication, Visual Culture, Visual Literacy, Creativity ABSTRACT / The thesis "Between the Text and the Image" attempts to capture the visual world of our everyda- yness through the ey...

  16. Dominant visual frames in climate change news stories: implications for formative evaluation in climate change campaigns

    National Research Council Canada - National Science Library

    Rebich-Hespanha, Stacy; Rice, Ronald E

    2016-01-01

    ..., science and climate change communication, and the role of formative evaluation in communication campaigns in general and climate change campaigns in particular. We then describe dominant climate change visual frames identified through previous research, suggest possible considerations in formative evaluation of each dominant frame, and outlin...

  17. Visual field examination method using virtual reality glasses compared with the Humphrey perimeter.

    Science.gov (United States)

    Tsapakis, Stylianos; Papaconstantinou, Dimitrios; Diagourtas, Andreas; Droutsas, Konstantinos; Andreanos, Konstantinos; Moschos, Marilita M; Brouzas, Dimitrios

    2017-01-01

    To present a visual field examination method using virtual reality glasses and evaluate the reliability of the method by comparing the results with those of the Humphrey perimeter. Virtual reality glasses, a smartphone with a 6 inch display, and software that implements a fast-threshold 3 dB step staircase algorithm for the central 24° of visual field (52 points) were used to test 20 eyes of 10 patients, who were tested in a random and consecutive order as they appeared in our glaucoma department. The results were compared with those obtained from the same patients using the Humphrey perimeter. High correlation coefficient (r=0.808, Pvirtual reality visual field test and the Humphrey perimeter visual field. Visual field examination results using virtual reality glasses have a high correlation with the Humphrey perimeter allowing the method to be suitable for probable clinical use.

  18. Different developmental trajectories across feature types support a dynamic field model of visual working memory development.

    Science.gov (United States)

    Simmering, Vanessa R; Miller, Hilary E; Bohache, Kevin

    2015-05-01

    Research on visual working memory has focused on characterizing the nature of capacity limits as "slots" or "resources" based almost exclusively on adults' performance with little consideration for developmental change. Here we argue that understanding how visual working memory develops can shed new light onto the nature of representations. We present an alternative model, the Dynamic Field Theory (DFT), which can capture effects that have been previously attributed either to "slot" or "resource" explanations. The DFT includes a specific developmental mechanism to account for improvements in both resolution and capacity of visual working memory throughout childhood. Here we show how development in the DFT can account for different capacity estimates across feature types (i.e., color and shape). The current paper tests this account by comparing children's (3, 5, and 7 years of age) performance across different feature types. Results showed that capacity for colors increased faster over development than capacity for shapes. A second experiment confirmed this difference across feature types within subjects, but also showed that the difference can be attenuated by testing memory for less familiar colors. Model simulations demonstrate how developmental changes in connectivity within the model-purportedly arising through experience-can capture differences across feature types.

  19. Comparison of Diagnostic Accuracy between Octopus 900 and Goldmann Kinetic Visual Fields

    Directory of Open Access Journals (Sweden)

    Fiona J. Rowe

    2014-01-01

    Full Text Available Purpose. To determine diagnostic accuracy of kinetic visual field assessment by Octopus 900 perimetry compared with Goldmann perimetry. Methods. Prospective cross section evaluation of 40 control subjects with full visual fields and 50 patients with known visual field loss. Comparison of test duration and area measurement of isopters for Octopus 3, 5, and 10°/sec stimulus speeds. Comparison of test duration and type of visual field classification for Octopus versus Goldmann perimetry. Results were independently graded for presence/absence of field defect and for type and location of defect. Statistical evaluation comprised of ANOVA and paired t test for evaluation of parametric data with Bonferroni adjustment. Bland Altman and Kappa tests were used for measurement of agreement between data. Results. Octopus 5°/sec perimetry had comparable test duration to Goldmann perimetry. Octopus perimetry reliably detected type and location of visual field loss with visual fields matched to Goldmann results in 88.8% of results (K=0.775. Conclusions. Kinetic perimetry requires individual tailoring to ensure accuracy. Octopus perimetry was reproducible for presence/absence of visual field defect. Our screening protocol when using Octopus perimetry is 5°/sec for determining boundaries of peripheral isopters and 3°/sec for blind spot mapping with further evaluation of area of field loss for defect depth and size.

  20. Medical review licensing outcomes in drivers with visual field loss in Victoria, Australia

    Science.gov (United States)

    Muir, Carlyn; Charlton, Judith L; Odell, Morris; Keeffe, Jill; Wood, Joanne; Bohensky, Megan; Fildes, Brian; Oxley, Jennifer; Bentley, Sharon; Rizzo, Matthew

    2017-01-01

    Background Good vision is essential for safe driving and studies have associated visual impairment with an increased crash risk. Currently, there is little information about the medical review of drivers with visual field loss. This study examines the prevalence of visual field loss among drivers referred for medical review in one Australian jurisdiction and investigates factors associated with licence outcome in this group. Methods A random sample of 10,000 (31.25 per cent) medical review cases was extracted for analysis from the Victorian licensing authority. Files were screened for the presence of six visual field-related medical conditions. Data were captured on a range of variables, including referral source, age, gender, health status, crash history and licence outcome. Prevalence analyses were univariate and descriptive. Logistic regression was used to assess factors associated with licence outcomes in the visual field loss group. Results Approximately 1.9 per cent of the 10,000 medical review cases screened had a visual field loss condition identified (n=194). Among the visual field loss group, 57.2 per cent were permitted to continue driving (conditional/unconditional licence). Primary referral sources were the police, self-referrals and general medical practitioners. Key factors associated with licence test outcomes were visual field condition, age group, crash involvement and referral to the Driver Licensing Authority’s Medical Advisors. Those who were younger had a crash involvement triggering referral and those who were referred to the Medical Advisors were more likely to have a positive licensing outcome. Conclusion The evidence base for making licensing decisions is complicated by the variable causes, patterns, progressions and measuring technologies for visual field loss. This study highlighted that the involvement of an expert medical advisory service in Victoria resulted in an increased likelihood that drivers with visual field loss will be

  1. The efficacy of a novel mobile phone application for goldmann ptosis visual field interpretation.

    Science.gov (United States)

    Maamari, Robi N; D'Ambrosio, Michael V; Joseph, Jeffrey M; Tao, Jeremiah P

    2014-01-01

    To evaluate the efficacy of a novel mobile phone application that calculates superior visual field defects on Goldmann visual field charts. Experimental study in which the mobile phone application and 14 oculoplastic surgeons interpreted the superior visual field defect in 10 Goldmann charts. Percent error of the mobile phone application and the oculoplastic surgeons' estimates were calculated compared with computer software computation of the actual defects. Precision and time efficiency of the application were evaluated by processing the same Goldmann visual field chart 10 repeated times. The mobile phone application was associated with a mean percent error of 1.98% (95% confidence interval[CI], 0.87%-3.10%) in superior visual field defect calculation. The average mean percent error of the oculoplastic surgeons' visual estimates was 19.75% (95% CI, 14.39%-25.11%). Oculoplastic surgeons, on average, underestimated the defect in all 10 Goldmann charts. There was high interobserver variance among oculoplastic surgeons. The percent error of the 10 repeated measurements on a single chart was 0.93% (95% CI, 0.40%-1.46%). The average time to process 1 chart was 12.9 seconds (95% CI, 10.9-15.0 seconds). The mobile phone application was highly accurate, precise, and time-efficient in calculating the percent superior visual field defect using Goldmann charts. Oculoplastic surgeon visual interpretations were highly inaccurate, highly variable, and usually underestimated the field vision loss.

  2. Visualizing Change Management as Academic Competence of Customer

    OpenAIRE

    Demina, Alla

    2009-01-01

    The goal of this final year project was visualizing the Master’s Degree research in Change Management done by Remco Meisner and Roelof van Cleef at the VU University Amsterdam. The main goal of the project was to use a model called MINCE which is meant for evaluating the maturity level of organizations and to suggest ways to achieve a desired state. A short film was created. The target group consisted of students of the change management department at the VU University Amsterdam and the ...

  3. Direct Visualization of Local Electromagnetic Field Structures by Scanning Transmission Electron Microscopy.

    Science.gov (United States)

    Shibata, Naoya; Findlay, Scott D; Matsumoto, Takao; Kohno, Yuji; Seki, Takehito; Sánchez-Santolino, Gabriel; Ikuhara, Yuichi

    2017-07-18

    The functional properties of materials and devices are critically determined by the electromagnetic field structures formed inside them, especially at nanointerface and surface regions, because such structures are strongly associated with the dynamics of electrons, holes and ions. To understand the fundamental origin of many exotic properties in modern materials and devices, it is essential to directly characterize local electromagnetic field structures at such defect regions, even down to atomic dimensions. In recent years, rapid progress in the development of high-speed area detectors for aberration-corrected scanning transmission electron microscopy (STEM) with sub-angstrom spatial resolution has opened new possibilities to directly image such electromagnetic field structures at very high-resolution. In this Account, we give an overview of our recent development of differential phase contrast (DPC) microscopy for aberration-corrected STEM and its application to many materials problems. In recent years, we have developed segmented-type STEM detectors which divide the detector plane into 16 segments and enable simultaneous imaging of 16 STEM images which are sensitive to the positions and angles of transmitted/scattered electrons on the detector plane. These detectors also have atomic-resolution imaging capability. Using these segmented-type STEM detectors, we show DPC STEM imaging to be a very powerful tool for directly imaging local electromagnetic field structures in materials and devices in real space. For example, DPC STEM can clearly visualize the local electric field variation due to the abrupt potential change across a p-n junction in a GaAs semiconductor, which cannot be observed by normal in-focus bright-field or annular type dark-field STEM imaging modes. DPC STEM is also very effective for imaging magnetic field structures in magnetic materials, such as magnetic domains and skyrmions. Moreover, real-time imaging of electromagnetic field structures can

  4. Memory strength versus memory variability in visual change detection.

    Science.gov (United States)

    Nosofsky, Robert M; Gold, Jason

    2016-01-01

    Observers made change-detection judgments for colored squares in a paradigm that manipulated the retention interval, the magnitude of change, and objective change probability. The probability of change judgments increased across the retention interval for “same” and “small-change” test items but stayed the same or decreased for “large-change” and “far” test items. A variety of formal models were fitted to the individual-subject data. The modeling results provided evidence that, beyond changes in visual-memory precision, there were decreases in memory strength of individual study items across the retention interval. In addition, the modeling results provided evidence of a zero-information, absence-of-memory state that required guessing. The data were not sufficiently strong to sharply distinguish whether the losses in memory strength across the retention interval were continuous in nature or all-or-none. The authors argue that the construct of memory strength as distinct from memory variability is an important component of the nature of forgetting from visual working memory.

  5. The role of hemifield sector analysis in multifocal visual evoked potential objective perimetry in the early detection of glaucomatous visual field defects

    Directory of Open Access Journals (Sweden)

    Mousa MF

    2013-05-01

    % respectively and 89% and 79% in glaucoma suspects. These results showed that the new analysis protocol was able to confirm existing visual field defects detected by standard perimetry, was able to differentiate between the three study groups with a clear distinction between normal patients and those with suspected glaucoma, and was able to detect early visual field changes not detected by standard perimetry. In addition, the distinction between normal and glaucoma patients was especially clear and significant using this analysis.Conclusion: The new hemifield sector analysis protocol used in mfVEP testing can be used to detect glaucomatous visual field defects in both glaucoma and glaucoma suspect patients. Using this protocol, it can provide information about focal visual field differences across the horizontal midline, which can be utilized to differentiate between glaucoma and normal subjects. The sensitivity and specificity of the mfVEP test showed very promising results and correlated with other anatomical changes in glaucomatous visual field loss. The intersector analysis protocol can detect early field changes not detected by the standard Humphrey Field Analyzer test.Keywords: objective perimetry, multifocal VEP, visual field testing, glaucomatous field loss, glaucoma suspect, SAP, HFA

  6. A lower visual field advantage for endpoint stability but no advantage for online movement precision.

    Science.gov (United States)

    Krigolson, Olav; Heath, Matthew

    2006-03-01

    It has been proposed that visually guided reaching movements performed in the lower visual field (LVF) of peripersonal space are more effective and efficient than their upper visual field (UVF) counterparts (Danckert and Goodale 2001). In the present investigation we sought to determine whether this purported visual field asymmetry reflects advantaged processing of online visual feedback. To accomplish that objective, participants performed discrete reaching movements to each of three target locations in the LVF and UVF. In addition, reaches were completed under conditions wherein target location remained constant throughout a reaching response (i.e., control trials) and a separate condition wherein target location unexpectedly perturbed at movement onset (i.e., experimental trials). We reasoned that the target perturbation paradigm would provide a novel means to assess a possible superior-inferior visual field asymmetry for online reaching control. In terms of the impact of a target perturbation, both visual fields demonstrated equal proficiency integrating visual feedback for online limb adjustments. Interestingly, however, the spatial distribution of movement endpoints in the LVF was less than UVF counterparts (cf. Binsted and Heath 2005). Taken together, the present findings suggest that although LVF and UVF reaches readily use visual feedback to accommodate an unexpected target perturbation, reaches in the LVF elicit advantaged spatial benefits influencing the effectiveness of online limb corrections.

  7. Chromatic and achromatic visual fields in relation to choroidal thickness in patients with high myopia: A pilot study.

    Science.gov (United States)

    García-Domene, M C; Luque, M J; Díez-Ajenjo, M A; Desco-Esteban, M C; Artigas, J M

    2018-01-30

    To analyse the relationship between the choroidal thickness and the visual perception of patients with high myopia but without retinal damage. All patients underwent ophthalmic evaluation including a slit lamp examination and dilated ophthalmoscopy, subjective refraction, best corrected visual acuity, axial length, optical coherence tomography, contrast sensitivity function and sensitivity of the visual pathways. We included eleven eyes of subjects with high myopia. There are statistical correlations between choroidal thickness and almost all the contrast sensitivity values. The sensitivity of magnocellular and koniocellular pathways is the most affected, and the homogeneity of the sensibility of the magnocellular pathway depends on the choroidal thickness; when the thickness decreases, the sensitivity impairment extends from the center to the periphery of the visual field. Patients with high myopia without any fundus changes have visual impairments. We have found that choroidal thickness correlates with perceptual parameters such as contrast sensitivity or mean defect and pattern standard deviation of the visual fields of some visual pathways. Our study shows that the magnocellular and koniocellular pathways are the most affected, so that these patients have impairment in motion perception and blue-yellow contrast perception. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  8. Inferior visual field reductions are associated with poorer functional status among older adults with glaucoma.

    Science.gov (United States)

    Black, Alex A; Wood, Joanne M; Lovie-Kitchin, Jan E

    2011-05-01

    To examine the relationship between visual impairment and functional status in a community-dwelling sample of older adults with glaucoma. This study included 74 community-dwelling older adults with open-angle glaucoma (aged 74 ± 6 years). Assessment of central vision included high-contrast visual acuity and Pelli-Robson contrast sensitivity. Binocular integrated visual fields were derived from merged monocular Humphrey Field Analyser visual field plots. Functional status outcome measures included physical performance tests (6-min walk test, timed up and go test and lower limb strength), a physical activity questionnaire (Physical Activity Scale for the Elderly) and an overall functional status score. Correlation and linear regression analyses, adjusting for age and gender, examined the association between visual impairment and functional status outcomes. Greater levels of visual impairment were significantly associated with lower levels of functional status among community-dwelling older adults with glaucoma, independent of age and gender. Specifically, lower levels of visual function were associated with slower timed up and go performance, weaker lower limb strength, lower self-reported physical activity, and lower overall functional status scores. Of the components of vision examined, the inferior visual field and contrast factors were the strongest predictors of these functional outcomes, whereas the superior visual field factor was not related to functional status. Greater visual impairment, particularly in the inferior visual field and loss of contrast sensitivity, was associated with poorer functional status among older adults with glaucoma. The findings of this study highlight the potential links between visual impairment and the onset of functional decline. Interventions which promote physical activity among older adults with glaucoma may assist in preventing functional decline, frailty and falls, and improve overall health and well-being. © 2011 The

  9. Visual sensitivity of frontal eye field neurons during the preparation of saccadic eye movements.

    Science.gov (United States)

    Krock, Rebecca M; Moore, Tirin

    2016-12-01

    Primate vision is continuously disrupted by saccadic eye movements, and yet this disruption goes unperceived. One mechanism thought to reduce perception of this self-generated movement is saccadic suppression, a global loss of visual sensitivity just before, during, and after saccadic eye movements. The frontal eye field (FEF) is a candidate source of neural correlates of saccadic suppression previously observed in visual cortex, because it contributes to the generation of visually guided saccades and modulates visual cortical responses. However, whether the FEF exhibits a perisaccadic reduction in visual sensitivity that could be transmitted to visual cortex is unknown. To determine whether the FEF exhibits a signature of saccadic suppression, we recorded the visual responses of FEF neurons to brief, full-field visual probe stimuli presented during fixation and before onset of saccades directed away from the receptive field in rhesus macaques (Macaca mulatta) We measured visual sensitivity during both epochs and found that it declines before saccade onset. Visual sensitivity was significantly reduced in visual but not visuomotor neurons. This reduced sensitivity was also present in visual neurons with no movement-related modulation during visually guided saccades and thus occurred independently from movement-related activity. Across the population of visual neurons, sensitivity began declining ∼80 ms before saccade onset. We also observed a similar presaccadic reduction in sensitivity to isoluminant, chromatic stimuli. Our results demonstrate that the signaling of visual information by FEF neurons is reduced during saccade preparation, and thus these neurons exhibit a signature of saccadic suppression. Copyright © 2016 the American Physiological Society.

  10. Visual Field Progression in Patients with Primary Angle-Closure Glaucoma Using Pointwise Linear Regression Analysis.

    Science.gov (United States)

    Verma, Sushma; Nongpiur, Monisha E; Atalay, Eray; Wei, Xin; Husain, Rahat; Goh, David; Perera, Shamira A; Aung, Tin

    2017-07-01

    To evaluate visual field (VF) progression and rate of glaucomatous VF loss in patients with primary angle-closure glaucoma (PACG) using pointwise linear regression (PLR) trend analysis. Clinic-based retrospective study. Primary angle-closure glaucoma patients with 5 or more reliable VF tests and with 5 years or more of follow-up. Visual field progression was assessed by PROGRESSOR software version 3.7 (Medisoft, Leeds, United Kingdom) and was defined by the presence of at least 2 adjacent testing points located within the same hemifield that showed progression with a change of -1 dB/year or more (P regression analysis to determine the variables associated with rapid progression (defined as mean slope of progressing points ≥-1.5 dB/year). Visual field progression and rate of VF loss. Of the 1296 patients who were assessed, 398 (30.7%) fulfilled the inclusion criteria of 5 or more VFs and 5 years or more of follow-up. Visual field progression was observed in 63 of 398 eyes (15.8%) according to the PLR criteria. The overall mean rate of VF change for these patients was -0.12±0.51 dB/year over a mean follow-up period of 10.4±3.7 years. There were no significant differences in the age, gender distribution, follow-up duration, or number of VFs between those who showed progression and those who did not (all P > 0.05). The most common sector of VF progression was the superior arcuate area (65%). Rapid progression was found in 36 patients (57%). Multiple logistic regression analysis revealed older age and higher vertical cup-to-disc ratio (VCDR) at presentation as predictors of rapid progression (all P < 0.005) in the progressing group (n = 63). In patients with PACG being managed in a hospital setting, VF progression was noted in 15.8%, and the overall rate of VF loss was -0.12±0.51 dB/year. The superior arcuate was the most common sector of progression. Older age and higher VCDR at presentation were associated with rapid progression. Copyright © 2017 American

  11. Perception of geometrical arrays tachistoscopically exposed in right and left visual fields.

    Science.gov (United States)

    Fudin, R; Feldman, D B

    1975-06-01

    Geometrical stimuli (48 6-item arrays of familiar forms, e.g., circle), tachistoscopically presented in the right or left visual field, were more accurately perceived in the right than left visual field by 15 college students. Targets about half the length of the displays exposed here were perceived with equal facility in both visual fields (Bryden, 1960). Results suggest that length of array might affect the difference in perceptual accuracy of forms shown in the right and left visual fields. Figures in the right visual field were predominantly processed from left to right, and forms in the left visual field from right to left. Since more symbols were identified in the right than left visual field, the left to right encoding sequence may be more efficient than a right to left movement. Limited experience of most Ss in reading symbols from left to right is probably only one factor. Extensive experience reading alphabetical material from left to right might have developed the physiological mechanism underpinning this sequence more than the one serving the opposite movement.

  12. Morphology, orthography, and the two hemispheres: A divided visual field study with Hindi/Urdu biliterates.

    Science.gov (United States)

    Rao, Chaitra; Vaid, Jyotsna

    2017-04-01

    Although identical on the spoken level, Hindi and Urdu differ markedly on the written level in terms of reading/writing direction and orthographic depth, with discernible processing consequences. The present study used a divided field paradigm to study the impact of writing system characteristics of Hindi and Urdu on word naming latencies in skilled biliterate users of these languages. Hindi (read/written from left to right) was hypothesized to show a larger right field advantage than Urdu (read/written from right to left); Hindi words sharing form overlap with primes were expected to show a significant priming effect in the left visual field, but a significant right field effect for morphologically-primed naming. Both these expectations were confirmed. An overall right field advantage was obtained for one syllable Hindi and Urdu words; two syllable Urdu words showed either no visual field differences or a left field advantage, and the right field advantage for Hindi was significantly greater for two syllable than one syllable words. Further, Hindi words showed significant form priming (relative to control stimuli) in the left visual field and significant morphological priming (relative to form priming) in the right visual field. By contrast, Urdu words showed no significant form priming in either visual field, and significantly greater morphological than form priming in the left visual field. These results are taken to suggest that visual field asymmetries in word naming are sensitive to differences in reading habit-related scanning biases and to orthographic depth-related differences in word recognition processes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Retrobulbar blood flow and visual field alterations after acute ethanol ingestion

    Directory of Open Access Journals (Sweden)

    Weber A

    2013-08-01

    Full Text Available Anke Weber, Andreas Remky, Marion Bienert, Klaudia Huber-van der Velden, Thomas Kirschkamp, Corinna Rennings, Gernot Roessler, Niklas Plange Department of Ophthalmology, RWTH Aachen University, Aachen, Germany Background: The purpose of this study was to test the effect of ethyl alcohol on the koniocellular and magnocellular pathway of visual function and to investigate the relationship between such visual field changes and retrobulbar blood flow in healthy subjects. Methods: In 12 healthy subjects (mean age 32 ± 4 years, color Doppler imaging, short-wavelength automated perimetry, and frequency doubling perimetry was performed before and 60 minutes after oral intake of 80 mL of 40 vol% ethanol. Mean and pattern standard deviations for short-wavelength automated and frequency doubling perimetry were assessed. End diastolic velocity (EDV and peak systolic velocity (PSV were measured in the central retinal and ophthalmic arteries using color Doppler imaging. Systemic blood pressure, heart rate, intraocular pressure, and blood alcohol concentration were determined. Results: Mean PSV and EDV in the central retinal artery showed a significant increase after alcohol intake (P = 0.03 and P = 0.02, respectively. Similarly, we found a significant acceleration of blood flow velocity in the ophthalmic artery (P = 0.02 for PSV; P = 0.04 for EDV. Mean intraocular pressure decreased by 1.0 mmHg after alcohol ingestion (P = 0.01. Retinal sensitivity in short-wavelength automated perimetry did not alter, whereas in frequency doubling perimetry, the mean deviation decreased significantly. Systolic and diastolic blood pressure did not change significantly. Mean blood alcohol concentration was 0.38 ± 0.16 g/L. Conclusion: Although ethanol is known to cause peripheral vasodilation, our subjects had no significant drop in systemic blood pressure. However, a significant increase of blood flow velocity was seen in the retrobulbar vessels. Regarding visual function

  14. Spatial Visualization Abilities of Field Dependent/Independent Preservice Teachers

    Science.gov (United States)

    Yazici, Ersen

    2014-01-01

    Introduction: Spatial skills have been a significant area of research in educational psychology for more years and it has two major dimensions as spatial visualization and spatial orientation. Mathematics educators acknowledge the influence of cognitive styles in the learning of mathematics. There are various recognized cognitive styles in the…

  15. Pupillary anomaly masquerading as a glaucomatous visual field defect: a case report

    Directory of Open Access Journals (Sweden)

    Tey Adrian

    2004-06-01

    Full Text Available Abstract Background Patients are often referred to ophthalmologists with focal visual field defects on routine testing, possibly related to a potential diagnosis of glaucoma. However, examination of the individual patient's ocular characteristics as well as facial characteristics may often reveal a cause of the visual field defect. Case presentation We describe a patient who was found to have a superior visual field defect on routine testing by the optician. Repeat perimetry with pharmacological dilatation of the pupil revealed that the cause of the field defect was related to an eccentric inferiorly displaced pupil, secondary to trauma some years previously. Discussion Individual patient characteristics, including both ocular, as well as facial, need to be considered, when interpreting any visual field defect.

  16. Developmental changes in cytosolic coupling between epidermis cells as visualized by photoactivation of fluorescein

    DEFF Research Database (Denmark)

    Liu, Xiangdong; Martens, Helle; Schulz, Alexander

    Developmental changes in cytosolic coupling between epidermis cells as visualized by photoactivation of fluorescein.......Developmental changes in cytosolic coupling between epidermis cells as visualized by photoactivation of fluorescein....

  17. Can DMCO Detect Visual Field Loss in Neurological Patients? A Secondary Validation Study

    DEFF Research Database (Denmark)

    Olsen, Ane Sophie; Steensberg, Alvilda Thougaard; la Cour, Morten

    2017-01-01

    Unrecognized visual field loss is caused by a range of blinding eye conditions as well as serious brain diseases. The commonest cause of asymptomatic visual field loss is glaucoma. No screening tools have been proven cost-effective. Damato Multifixation Campimetry Online (DMCO), an inexpensive...... online test, has been evaluated as a future cost-beneficial tool to detect glaucoma. To further validate DMCO, this study aimed to test DMCO in a preselected population with neurological visual field loss. Methods : The study design was an evaluation of a diagnostic test. Patients were included...

  18. CLOCK CHART(®): a novel multi-stimulus self-check visual field screener.

    Science.gov (United States)

    Matsumoto, Chota; Eura, Mariko; Okuyama, Sachiko; Takada, Sonoko; Arimura-Koike, Eiko; Hashimoto, Shigeki; Tanabe, Fumi; Shimomura, Yoshikazu

    2015-05-01

    CLOCK CHART(®) is a multi-stimulus-type self-check visual field screening sheet developed by our group. The test chart is rotated during the examination, and the visual field abnormalities are pointed out by the patients themselves. In this study, we evaluated the clinical usefulness of this chart in patients with glaucoma. We studied 114 eyes of 114 glaucoma patients (average age 60.0 ± 11.1 years) and 45 eyes of 45 normal individuals (average age 45.0 ± 16.4 years) using CLOCK CHART(®). The static visual fields were obtained using the Octopus 101 G2 program and classified using the Aulhorn classification as modified by Greve (stages 0-I to IV) and by mean defect (MD; early 12 dB).The sensitivity and specificity of CLOCK CHART(®) for detecting visual field abnormalities were evaluated within the entire 25° field and at the 5°, 10°, 15°, 20°, and 25° eccentricity zones. The visual field agreement between the results of CLOCK CHART(®) and the static visual fields were also evaluated. In glaucomatous eyes, the sensitivity of CLOCK CHART(®) was 85, 93, and 100 % for Greve stages I, II and III-VI, respectively, and 87, 93, and 97 % for the MD value in early, moderate, and severe eyes, respectively. The agreement of the visual field defect area in CLOCK CHART(®) with the static fields was 85 and 100 % with Greve stages 0-I to I and II-VI, respectively, and 91, 96, and 96 % in early, moderate and severe glaucomatous eyes according to MD, respectively. The specificity of CLOCK CHART(®) was 89 %. CLOCK CHART(®) is a simple and reliable self-check screening chart for detecting visual field abnormalities in patients with glaucoma.

  19. The Variation in Spatial Visualization Abilities of College Male and Female Students in STEM Fields versus Non-STEM Fields

    Science.gov (United States)

    Sharobeam, Monir H.

    2016-01-01

    The purpose of this study was to determine whether there is a difference in spatial visualization ability between college students in STEM (science, technology, engineering, and mathematics) fields and those in non-STEM fields. The study also examined whether such a difference can be identified across gender. The study included over 850 male and…

  20. Electric field changes and cloud electrical structure

    Science.gov (United States)

    Krider, E. Philip

    1989-09-01

    The NASA Kennedy Space Center and Cape Canaveral Air Force Station are currently operating a large network of electric field mills to detect lightning and electrified clouds that might present hazards to ground operations, launches, and landings. Here we summarize recent results of least squares analyses of multistation measurements of field changes that were produced by cloud-to-ground (Q model) and intracloud (P model) lightning. The values of the optimum parameters of 113 lightning events that occurred in one small storm on July 11, 1978, and a portion of a large storm on July 6, 1978, are tabulated and graphed. We note that, in both storms, there is considerable symmetry in the direction of P vectors around the Q region and that this pattern is consistent with the classic double-dipole model of thundercloud charges. We note also that the vertical separation of the Q and P regions depends on the storm intensity.

  1. How visual attention is modified by disparities and textures changes?

    Science.gov (United States)

    Khaustova, Dar'ya; Fournier, Jérome; Wyckens, Emmanuel; Le Meur, Olivier

    2013-03-01

    The 3D image/video quality of experience is a multidimensional concept that depends on 2D image quality, depth quantity and visual comfort. The relationship between these parameters is not yet clearly defined. From this perspective, we aim to understand how texture complexity, depth quantity and visual comfort influence the way people observe 3D content in comparison with 2D. Six scenes with different structural parameters were generated using Blender software. For these six scenes, the following parameters were modified: texture complexity and the amount of depth changing the camera baseline and the convergence distance at the shooting side. Our study was conducted using an eye-tracker and a 3DTV display. During the eye-tracking experiment, each observer freely examined images with different depth levels and texture complexities. To avoid memory bias, we ensured that each observer had only seen scene content once. Collected fixation data were used to build saliency maps and to analyze differences between 2D and 3D conditions. Our results show that the introduction of disparity shortened saccade length; however fixation durations remained unaffected. An analysis of the saliency maps did not reveal any differences between 2D and 3D conditions for the viewing duration of 20 s. When the whole period was divided into smaller intervals, we found that for the first 4 s the introduced disparity was conducive to the section of saliency regions. However, this contribution is quite minimal if the correlation between saliency maps is analyzed. Nevertheless, we did not find that discomfort (comfort) had any influence on visual attention. We believe that existing metrics and methods are depth insensitive and do not reveal such differences. Based on the analysis of heat maps and paired t-tests of inter-observer visual congruency values we deduced that the selected areas of interest depend on texture complexities.

  2. Short-term enhancement of visual field sensitivity in glaucomatous eyes following surgical intraocular pressure reduction.

    Science.gov (United States)

    Wright, Tracy M; Goharian, Iman; Gardiner, Stuart K; Sehi, Mitra; Greenfield, David S

    2015-02-01

    To examine the hypothesis that surgical intraocular pressure (IOP) reduction leads to enhancement of visual field (VF) sensitivity in glaucomatous eyes. Prospective case-control study. Patients with uncontrolled IOP requiring trabeculectomy or aqueous drainage device were enrolled. Controls consisted of medically treated glaucoma patients with stable IOP and no change in medical therapy during follow-up. Two baseline preoperative VFs and 3 follow-up VF examinations at 1, 2, and 3 months postoperatively were used for analysis. The same number of VF examinations measured within an 18-month interval was used for control eyes. VF locations with significant change were defined as exceeding 95% test-retest confidence limits based upon the mean sensitivity using the 2 baseline VF exams. The number of significantly changing locations per eye and changes in mean and pattern standard deviation (PSD) from the mean baseline fields were compared between groups using a Poisson generalized estimating equation model. Thirty eyes of 30 surgically treated glaucoma patients and 41 eyes of 28 stable controls were enrolled. Postoperative IOP was decreased at follow-up 3 compared with baseline (P IOP in glaucomatous eyes and may represent a potential biomarker for retinal ganglion cell response to therapeutic interventions in glaucoma. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Clinical effect of Xueshuantong combined with calcium dobesilate on visual field defect caused by diabetic retinopathy

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    Sai-Yun Xiao

    2015-06-01

    Full Text Available AIM: To research the clinical curative effect of Xueshuantong combined with calcium dobesilate on visual field defect caused by diabetic retinopathy. METHODS: Sixty-four cases with diabetic retinopathy treated in our hospital patients were selected as the research objects. They were randomly divided into observation group and control group. The control group was treated with Xueshuantong, and the observation group was treated with combined treatment of calcium dobesilate. After 5mo, the clinical efficacy was compared between the two groups of diabetic retinopathy, and before and after treatment fundus photography, fluorescein angiography and visual field changes, observation of patients with adverse reactions and recurrence were performed. RESULTS: The condition of patients was improved, and the effective rate of treatment group was 97%, and higher than that of the control group 78%, the differences were statistically significant(PPPPCONCLUSION: The patients with diabetic retinopathy treated with Xueshuantong combined with calcium dobesilate achieve satisfactory effect, and it can effectively reduce the recurrence rate and the adverse reactions, and improve the clinical symptoms. It would be widely applied in clinical practice.

  4. Cupping reversal in pediatric glaucoma--evaluation of the retinal nerve fiber layer and visual field.

    Science.gov (United States)

    Ely, Amanda L; El-Dairi, Mays A; Freedman, Sharon F

    2014-11-01

    To identify optic nerve head (ONH) cupping reversal and associated optical coherence tomography (OCT) and Humphrey visual field changes in pediatric glaucoma. Retrospective observational case series. Sequential surgical cases of juvenile open-angle glaucoma (OAG) or primary congenital glaucoma (PCG) with sustained postoperative intraocular pressure (IOP) reduction. Group 1 had preoperative and postoperative ONH photographs and OCT; Group 2 had preoperative clinical ONH assessment and postoperative imaging. Cupping evaluation was confirmed by masked glaucoma and neuro-ophthalmology specialists. Of 80 cases, 9 eyes (9 children) met criteria for Group 1; 24 eyes (19 children) met criteria for Group 2. Group 1: Five of 9 eyes (56%) demonstrated cupping reversal, with preoperative vs postoperative mean IOP 34.2 ± 6.6 mm Hg vs 10.6 ± 4.1 mm Hg (P cupping reversal, with preoperative vs postoperative mean IOP 36.1 ± 8.9 mm Hg vs 13.3 ± 2.1 mm Hg (P cup-to-disc ratio. Limitations include small numbers, few reliable Humphrey visual fields, and absent preoperative imaging (Group 2). Some eyes with IOP reduction and ONH cupping reversal show continued RNFL thinning postoperatively. The preoperative ONH cup-to-disc ratio predicted the postoperative RNFL better than the postoperative "reversed and smaller" cup-to-disc ratio. Cupping reversal in pediatric glaucoma may not predict improved ONH health and deserves further study. Copyright © 2014 Elsevier Inc. All rights reserved.

  5. Right Visual Field Advantage for Perceived Contrast: Correlation with an Auditory Bias and Handedness

    Science.gov (United States)

    Railo, H.; Tallus, J.; Hamalainen, H.

    2011-01-01

    Studies have suggested that supramodal attentional resources are biased rightward due to asymmetric spatial fields of the two hemispheres. This bias has been observed especially in right-handed subjects. We presented left and right-handed subjects with brief uniform grey visual stimuli in either the left or right visual hemifield. Consistent with…

  6. Long-term occupational exposure to organic solvents affects color vision, contrast sensitivity and visual fields.

    Directory of Open Access Journals (Sweden)

    Thiago Leiros Costa

    Full Text Available The purpose of this study was to evaluate the visual outcome of chronic occupational exposure to a mixture of organic solvents by measuring color discrimination, achromatic contrast sensitivity and visual fields in a group of gas station workers. We tested 25 workers (20 males and 25 controls with no history of chronic exposure to solvents (10 males. All participants had normal ophthalmologic exams. Subjects had worked in gas stations on an average of 9.6 ± 6.2 years. Color vision was evaluated with the Lanthony D15d and Cambridge Colour Test (CCT. Visual field assessment consisted of white-on-white 24-2 automatic perimetry (Humphrey II-750i. Contrast sensitivity was measured for sinusoidal gratings of 0.2, 0.5, 1.0, 2.0, 5.0, 10.0 and 20.0 cycles per degree (cpd. Results from both groups were compared using the Mann-Whitney U test. The number of errors in the D15d was higher for workers relative to controls (p<0.01. Their CCT color discrimination thresholds were elevated compared to the control group along the protan, deutan and tritan confusion axes (p<0.01, and their ellipse area and ellipticity were higher (p<0.01. Genetic analysis of subjects with very elevated color discrimination thresholds excluded congenital causes for the visual losses. Automated perimetry thresholds showed elevation in the 9°, 15° and 21° of eccentricity (p<0.01 and in MD and PSD indexes (p<0.01. Contrast sensitivity losses were found for all spatial frequencies measured (p<0.01 except for 0.5 cpd. Significant correlation was found between previous working years and deutan axis thresholds (rho = 0.59; p<0.05, indexes of the Lanthony D15d (rho=0.52; p<0.05, perimetry results in the fovea (rho= -0.51; p<0.05 and at 3, 9 and 15 degrees of eccentricity (rho= -0.46; p<0.05. Extensive and diffuse visual changes were found, suggesting that specific occupational limits should be created.

  7. The subtlety of simple eyes: the tuning of visual fields to perceptual challenges in birds

    Science.gov (United States)

    Martin, Graham R.

    2014-01-01

    Birds show interspecific variation both in the size of the fields of individual eyes and in the ways that these fields are brought together to produce the total visual field. Variation is found in the dimensions of all main parameters: binocular region, cyclopean field and blind areas. There is a phylogenetic signal with respect to maximum width of the binocular field in that passerine species have significantly broader field widths than non-passerines; broadest fields are found among crows (Corvidae). Among non-passerines, visual fields show considerable variation within families and even within some genera. It is argued that (i) the main drivers of differences in visual fields are associated with perceptual challenges that arise through different modes of foraging, and (ii) the primary function of binocularity in birds lies in the control of bill position rather than in the control of locomotion. The informational function of binocular vision does not lie in binocularity per se (two eyes receiving slightly different information simultaneously about the same objects from which higher-order depth information is extracted), but in the contralateral projection of the visual field of each eye. Contralateral projection ensures that each eye receives information from a symmetrically expanding optic flow-field from which direction of travel and time to contact targets can be extracted, particularly with respect to the control of bill position. PMID:24395967

  8. The subtlety of simple eyes: the tuning of visual fields to perceptual challenges in birds.

    Science.gov (United States)

    Martin, Graham R

    2014-01-01

    Birds show interspecific variation both in the size of the fields of individual eyes and in the ways that these fields are brought together to produce the total visual field. Variation is found in the dimensions of all main parameters: binocular region, cyclopean field and blind areas. There is a phylogenetic signal with respect to maximum width of the binocular field in that passerine species have significantly broader field widths than non-passerines; broadest fields are found among crows (Corvidae). Among non-passerines, visual fields show considerable variation within families and even within some genera. It is argued that (i) the main drivers of differences in visual fields are associated with perceptual challenges that arise through different modes of foraging, and (ii) the primary function of binocularity in birds lies in the control of bill position rather than in the control of locomotion. The informational function of binocular vision does not lie in binocularity per se (two eyes receiving slightly different information simultaneously about the same objects from which higher-order depth information is extracted), but in the contralateral projection of the visual field of each eye. Contralateral projection ensures that each eye receives information from a symmetrically expanding optic flow-field from which direction of travel and time to contact targets can be extracted, particularly with respect to the control of bill position.

  9. Visual field examination using a video projector: comparison with Humphrey perimeter

    OpenAIRE

    Brouzas, Dimitrios; Tsapakis, Stylianos; Nitoda, Eirini; Moschos, Marilita M

    2014-01-01

    Dimitrios Brouzas, Stylianos Tsapakis, Eirini Nitoda, Marilita M Moschos First Department of Ophthalmology, Medical School, University of Athens, Greece Purpose: To present a method of visual field examination using a video projector. Also, we compare our results with those of a Humphrey perimeter, which is accepted as standard in automated perimetry. Materials and methods: Software implementing a full-threshold 4-2-step staircase algorithm for the central 30-2 of the visual field (76 points...

  10. Normal Threshold Size of Stimuli in Children Using a Game-Based Visual Field Test.

    Science.gov (United States)

    Wang, Yanfang; Ali, Zaria; Subramani, Siddharth; Biswas, Susmito; Fenerty, Cecilia; Henson, David B; Aslam, Tariq

    2017-06-01

    The aim of this study was to demonstrate and explore the ability of novel game-based perimetry to establish normal visual field thresholds in children. One hundred and eighteen children (aged 8.0 ± 2.8 years old) with no history of visual field loss or significant medical history were recruited. Each child had one eye tested using a game-based visual field test 'Caspar's Castle' at four retinal locations 12.7° (N = 118) from fixation. Thresholds were established repeatedly using up/down staircase algorithms with stimuli of varying diameter (luminance 20 cd/m2, duration 200 ms, background luminance 10 cd/m2). Relationships between threshold and age were determined along with measures of intra- and intersubject variability. The Game-based visual field test was able to establish threshold estimates in the full range of children tested. Threshold size reduced with increasing age in children. Intrasubject variability and intersubject variability were inversely related to age in children. Normal visual field thresholds were established for specific locations in children using a novel game-based visual field test. These could be used as a foundation for developing a game-based perimetry screening test for children.

  11. Comprehensive visual field test & diagnosis system in support of astronaut health and performance

    Science.gov (United States)

    Fink, Wolfgang; Clark, Jonathan B.; Reisman, Garrett E.; Tarbell, Mark A.

    Long duration spaceflight, permanent human presence on the Moon, and future human missions to Mars will require autonomous medical care to address both expected and unexpected risks. An integrated non-invasive visual field test & diagnosis system is presented for the identification, characterization, and automated classification of visual field defects caused by the spaceflight environment. This system will support the onboard medical provider and astronauts on space missions with an innovative, non-invasive, accurate, sensitive, and fast visual field test. It includes a database for examination data, and a software package for automated visual field analysis and diagnosis. The system will be used to detect and diagnose conditions affecting the visual field, while in space and on Earth, permitting the timely application of therapeutic countermeasures before astronaut health or performance are impaired. State-of-the-art perimetry devices are bulky, thereby precluding application in a spaceflight setting. In contrast, the visual field test & diagnosis system requires only a touchscreen-equipped computer or touchpad device, which may already be in use for other purposes (i.e., no additional payload), and custom software. The system has application in routine astronaut assessment (Clinical Status Exam), pre-, in-, and post-flight monitoring, and astronaut selection. It is deployable in operational space environments, such as aboard the International Space Station or during future missions to or permanent presence on the Moon and Mars.

  12. Specvis: Free and open-source software for visual field examination.

    Directory of Open Access Journals (Sweden)

    Piotr Dzwiniel

    Full Text Available Visual field impairment affects more than 100 million people globally. However, due to the lack of the access to appropriate ophthalmic healthcare in undeveloped regions as a result of associated costs and expertise this number may be an underestimate. Improved access to affordable diagnostic software designed for visual field examination could slow the progression of diseases, such as glaucoma, allowing for early diagnosis and intervention. We have developed Specvis, a free and open-source application written in Java programming language that can run on any personal computer to meet this requirement (http://www.specvis.pl/. Specvis was tested on glaucomatous, retinitis pigmentosa and stroke patients and the results were compared to results using the Medmont M700 Automated Static Perimeter. The application was also tested for inter-test intrapersonal variability. The results from both validation studies indicated low inter-test intrapersonal variability, and suitable reliability for a fast and simple assessment of visual field impairment. Specvis easily identifies visual field areas of zero sensitivity and allows for evaluation of its levels throughout the visual field. Thus, Specvis is a new, reliable application that can be successfully used for visual field examination and can fill the gap between confrontation and perimetry tests. The main advantages of Specvis over existing methods are its availability (free, affordability (runs on any personal computer, and reliability (comparable to high-cost solutions.

  13. Visual fields, eye movements, and scanning behavior of a sit-and-wait predator, the black phoebe (Sayornis nigricans).

    Science.gov (United States)

    Gall, Megan D; Fernández-Juricic, Esteban

    2010-01-01

    Foraging mode influences the dominant sensory modality used by a forager and likely the strategies of information gathering used in foraging and anti-predator contexts. We assessed three components of visual information gathering in a sit-and-wait avian predator, the black phoebe (Sayornis nigricans): configuration of the visual field, degree of eye movement, and scanning behavior through head-movement rates. We found that black phoebes have larger lateral visual fields than similarly sized ground-foraging passerines, as well as relatively narrower binocular and blind areas. Black phoebes moved their eyes, but eye movement amplitude was relatively smaller than in other passerines. Black phoebes may compensate for eye movement constraints with head movements. The rate of head movements increased before attacking prey in comparison to non-foraging contexts and before movements between perches. These findings suggest that black phoebes use their lateral visual fields, likely subtended by areas of high acuity in the retina, to track prey items in a three-dimensional space through active head movements. These head movements may increase depth perception, motion detection and tracking. Studying information gathering through head movement changes, rather than body posture changes (head-up, head-down) as generally presented in the literature, may allow us to better understand the mechanisms of information gathering from a comparative perspective.

  14. No evidence of a lower visual field specialization for visuomotor control.

    Science.gov (United States)

    Binsted, Gord; Heath, Matthew

    2005-03-01

    The lower visual field (loVF) has been hypothesized to demonstrate specialization for skilled, visually guided action. According to Danckert and Goodale, this visual field asymmetry indirectly suggests that the loVF has privileged connections to visuomotor networks within the dorsal visual pathway. Here we attempted to replicate the loVF advantage during the execution of a discrete aiming movement to targets of various widths (index of difficulty ranging from 1.5 to 5 bits). In addition, we employed trials in which vision of the target object was available or unavailable during the reaching movement to determine whether or not the purported visual field asymmetry reflects enhanced central planning (i.e., feedforward) or online control (i.e., feedback) processes. Reaching trajectories were examined for indicators of online amendments, and movement times and endpoint characteristics were examined to quantify possible visual field asymmetries in relative speed/accuracy trade-offs. In terms of reaching kinematics, it was found that vision of the target during the reaching movement resulted in greater online control of the reaching trajectory; however, no significant main effects or interactions involving visual field were observed. In other words, fixating in the upper or the lower region of peripersonal space did not influence the nature of reaching control (i.e., feedback vs. feedforward). Most importantly, our movement time and endpoint accuracy data elicited a robust speed/accuracy trade-off in both upper and lower regions of working space. Thus, and contrary to previous findings (such as those reported by Danckert and Goodale), the indices of difficulty coupled with the discrete aiming task used here did not elicit a lower visual field advantage for visually guided action.

  15. Visualizing projected Climate Changes - the CMIP5 Multi-Model Ensemble

    Science.gov (United States)

    Böttinger, Michael; Eyring, Veronika; Lauer, Axel; Meier-Fleischer, Karin

    2017-04-01

    Large ensembles add an additional dimension to climate model simulations. Internal variability of the climate system can be assessed for example by multiple climate model simulations with small variations in the initial conditions or by analyzing the spread in large ensembles made by multiple climate models under common protocols. This spread is often used as a measure of uncertainty in climate projections. In the context of the fifth phase of the WCRP's Coupled Model Intercomparison Project (CMIP5), more than 40 different coupled climate models were employed to carry out a coordinated set of experiments. Time series of the development of integral quantities such as the global mean temperature change for all models visualize the spread in the multi-model ensemble. A similar approach can be applied to 2D-visualizations of projected climate changes such as latitude-longitude maps showing the multi-model mean of the ensemble by adding a graphical representation of the uncertainty information. This has been demonstrated for example with static figures in chapter 12 of the last IPCC report (AR5) using different so-called stippling and hatching techniques. In this work, we focus on animated visualizations of multi-model ensemble climate projections carried out within CMIP5 as a way of communicating climate change results to the scientific community as well as to the public. We take a closer look at measures of robustness or uncertainty used in recent publications suitable for animated visualizations. Specifically, we use the ESMValTool [1] to process and prepare the CMIP5 multi-model data in combination with standard visualization tools such as NCL and the commercial 3D visualization software Avizo to create the animations. We compare different visualization techniques such as height fields or shading with transparency for creating animated visualization of ensemble mean changes in temperature and precipitation including corresponding robustness measures. [1] Eyring, V

  16. [Responses of rabbit's visual cortex neurons to changes in intensity and orientation of visual stimuli].

    Science.gov (United States)

    Polianskiĭ, V B; Alymkulov, D E; Evtikhin, D V; Sokolov, E N; Chernyshev, B V

    2010-01-01

    Changes in the number of spikes in the early phasic discharge (50-90 ms from stimuli replacement) of neurons in the rabbit's primary visual cortex were studied under conditions of an instant change in a flashing-line pattern. We used three type of stimulation: lines with different orientations (0-90 degrees) but constant intensity; lines with constant orientation but different intensities; complex stimuli with different intensities and different orientations of lines. Factor analysis made it possible to reconstruct two-dimensional sensory spaces of orientations in 13 of 43 analyzed neurons (30%). In 5 of 30 analyzed neurons (16.6%), both two-dimensional spaces of orientations and two-dimensional spaces of intensities were revealed. Achromatic spaces were reconstructed during changes in the lines of varying intensities but constant orientation. In experiments with complex stimuli, the intensity of lines with orientations varying from 0 to 38.58 degree was 5 cd/m2. The intensity of lines with orientations varying from 51.44 to 90 degrees was 15 cd/m2. In the sensorial space, stimuli with different intensities were located on the plane formed by the first and second significant factors in opposite quadrants, whereas within each quadrant, the stimuli were arranged closely to their orientation from minimum to maximum. We suggest that this type of sensory space reflects the interaction between intensity and orientation attributes of visual stimuli with the factor of intensity prevailing over the factor of orientation. Only 7 (12%) neurons with such complex spaces were found.

  17. Damage visualization enhancement by the wave field filtering and processing

    Science.gov (United States)

    Kudela, Pawel; Radzienski, Maciej; Ostachowicz, Wieslaw

    2012-04-01

    The aim of this paper is to present methods for enhancing damage visualization in structures based on wave propagation phenomenon. The method utilizes filtering and processing of full wavefield acquired by the laser vibrometer. Laser vibrometer allows to register full wavefield in elements of a structure instead of single point measurements acquired by e.g. piezoelectric sensor. In this way new possibilities for Nondestructive Evaluation arise enabling visualization of elastic waves interacting with various types of damages. Measurements obtained with a scanning laser vibrometer can be combined with effective signal and imaging processing algorithms to support damage identification. In this paper new method for wave filtering of propagating waves is tested on both numerical results and experimental data obtained from laser vibrometry measurements of composite plates. Processing of signals registered at a rectangular grid of measurement points covering inspected area of the plate involve 2D DFFT (Discrete Fast Fourier Transform), wavenumber filtering and inverse DFFT. As a result new damage index is proposed and compared with other methods like RMS and frequency-wavenumber filtering.

  18. Characterization of field compaction using shrinkage analysis and visual soil examination

    Science.gov (United States)

    Johannes, Alice; Keller, Thomas; Weisskopf, Peter; Schulin, Rainer; Boivin, Pascal

    2016-04-01

    Visual field examination of soil structure can be very useful in extension work, because it is easy to perform, does not require equipment or lab analyses and the result is immediately available. The main limitations of visual methods are subjectivity and variation with field conditions. To provide reliable reference information, methods for objective and quantitative assessment of soil structure quality are still necessary. Soil shrinkage analysis (ShA) (Braudeau et al., 2004) provides relevant parameters for soil functions that allow precise and accurate assessment of soil compaction. To test it, we applied ShA to samples taken from a soil structure observatory (SSO) set up in 2014 on a loamy soil in Zurich, Switzerland to quantify the structural recovery of compacted agricultural soil. The objective in this presentation is to compare the ability of a visual examination method and ShA to assess soil compaction and structural recovery on the SSO field plots. Eighteen undisturbed soil samples were taken in the topsoil (5-10 cm) and 9 samples in the subsoil (30-35 cm) of compacted plots and control. Each sample went through ShA, followed by a visual examination of the sample and analysis of soil organic carbon and texture. ShA combines simultaneous shrinkage with water retention measurements and, in addition to soil properties such as bulk density, coarse and fine porosity, also provides information on hydrostructural stability and plasma and structural porosity. For visual examination the VESS method of Ball et al. (2007) was adapted to core samples previously equilibrated at -100 hPa matric potential. The samples were randomly and anonymously scored to avoid subjectivity and were equilibrated to insure comparable conditions. Compaction decreased the total specific volume, as well as air and water content at all matric potentials. Structural porosity was reduced, while plasma porosity remained unchanged. Compaction also changed the shape of the shrinkage curve: (i

  19. Photography and new media - changes in visual narrative approach.

    OpenAIRE

    Zoulová, Tereza

    2012-01-01

    The work deals with the changes that brought the photos to new media. In summary provides insight into history of first attempts in this field to the invention and development of digital camera. It also deals with the presentation of photographs at the time of new media. It especially pays attention to the Internet, which greatly contributed to the mass dissemination of images of both professional photographers and the amateur. It points out that availability of digital cameras and the Intern...

  20. A new system for quantitative evaluation of infant gaze capabilities in a wide visual field.

    Science.gov (United States)

    Pratesi, Andrea; Cecchi, Francesca; Beani, Elena; Sgandurra, Giuseppina; Cioni, Giovanni; Laschi, Cecilia; Dario, Paolo

    2015-09-07

    The visual assessment of infants poses specific challenges: many techniques that are used on adults are based on the patient's response, and are not suitable for infants. Significant advances in the eye-tracking have made this assessment of infant visual capabilities easier, however, eye-tracking still requires the subject's collaboration, in most cases and thus limiting the application in infant research. Moreover, there is a lack of transferability to clinical practice, and thus it emerges the need for a new tool to measure the paradigms and explore the most common visual competences in a wide visual field. This work presents the design, development and preliminary testing of a new system for measuring infant's gaze in the wide visual field called CareToy C: CareToy for Clinics. The system is based on a commercial eye tracker (SmartEye) with six cameras running at 60 Hz, suitable for measuring an infant's gaze. In order to stimulate the infant visually and audibly, a mechanical structure has been designed to support five speakers and five screens at a specific distance (60 cm) and angle: one in the centre, two on the right-hand side and two on the left (at 30° and 60° respectively). Different tasks have been designed in order to evaluate the system capability to assess the infant's gaze movements during different conditions (such as gap, overlap or audio-visual paradigms). Nine healthy infants aged 4-10 months were assessed as they performed the visual tasks at random. We developed a system able to measure infant's gaze in a wide visual field covering a total visual range of ±60° from the centre with an intermediate evaluation at ±30°. Moreover, the same system, thanks to different integrated software, was able to provide different visual paradigms (as gap, overlap and audio-visual) assessing and comparing different visual and multisensory sub-competencies. The proposed system endowed the integration of a commercial eye-tracker into a purposive setup in

  1. Scopic Regime Change: The War of Terror, Visual Culture, and Art Education

    Science.gov (United States)

    Darts, David; Tavin, Kevin; Sweeny, Robert W.; Derby, John

    2008-01-01

    This study examines visual dimensions and pedagogical repercussions of the war of terror. Iconographies of threat and prophylaxis are explored through a discussion of the actuarial gaze and the terr(or)itorialization of the visual field. Specific visual culture fallout from the war of terror is examined, including artistic responses and…

  2. Visualizing Robustness of Critical Points for 2D Time-Varying Vector Fields

    KAUST Repository

    Wang, B.

    2013-06-01

    Analyzing critical points and their temporal evolutions plays a crucial role in understanding the behavior of vector fields. A key challenge is to quantify the stability of critical points: more stable points may represent more important phenomena or vice versa. The topological notion of robustness is a tool which allows us to quantify rigorously the stability of each critical point. Intuitively, the robustness of a critical point is the minimum amount of perturbation necessary to cancel it within a local neighborhood, measured under an appropriate metric. In this paper, we introduce a new analysis and visualization framework which enables interactive exploration of robustness of critical points for both stationary and time-varying 2D vector fields. This framework allows the end-users, for the first time, to investigate how the stability of a critical point evolves over time. We show that this depends heavily on the global properties of the vector field and that structural changes can correspond to interesting behavior. We demonstrate the practicality of our theories and techniques on several datasets involving combustion and oceanic eddy simulations and obtain some key insights regarding their stable and unstable features. © 2013 The Author(s) Computer Graphics Forum © 2013 The Eurographics Association and Blackwell Publishing Ltd.

  3. Videotaped evaluation of eyedrop instillation in glaucoma patients with visual impairment or moderate to severe visual field loss.

    Science.gov (United States)

    Hennessy, Amy L; Katz, Joanne; Covert, David; Protzko, Colleen; Robin, Alan L

    2010-12-01

    Objectively evaluate the ability of visually disabled glaucoma patients to successfully administer a single drop onto their eye. Prospective, observational study. Experienced glaucoma patients with Early Treatment of Diabetic Retinopathy Study visual acuity (VA) of ≤ 6/18 (≤ 20/60) ≥ 1 eye, or moderate or severe visual field damage in ≥ 1 eye. Subjects were "low vision" (20/60 ≤ VA 6 months. Subjects used a mean of 1.9 ± 1.1 bottles of intraocular pressure-lowering medications to treat their glaucoma. Seventy-six percent (155/204) of subjects had severe visual field damage, with a mean deviation of -14.5 ± 8.0. Twenty-six percent (54/204) had acuity of ≤ 20/200 in ≥ 1 eye, and subjects had a mean logarithm of minimal angle of resolution acuity of 0.8 ± 0.9. Seventy-one percent of subjects were able to get a drop onto the eye; only 39% instilled 1 drop onto the eye without touching the ocular surface, instilling a mean 1.4 ± 1.0 drops, using 1.2 ± 0.6 attempts. Of the 142 subjects who denied touching the bottle to the ocular surface, 24% did touch the bottle to the eye. Multiple factors were tested for ability to predict successful application of an eyedrop; however, only age (visually impaired glaucoma patients, we evaluated the difficulty this population has instilling eyedrops, most important, the use of multiple drops per instillation, potential contamination of a chronically used bottle, and poor patient understanding of the situation. Ability to self-administer eyedrops and cost considerations of wasted drops must be thought out before institution of glaucoma therapy. Efforts to determine better methods of eyedrop administration need to be undertaken. Copyright © 2010 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

  4. Characteristics of eye-position gain field populations determine geometry of visual space

    Directory of Open Access Journals (Sweden)

    Sidney R Lehky

    2016-01-01

    Full Text Available We have previously demonstrated differences in eye-position spatial maps for anterior inferotemporal cortex (AIT in the ventral stream and lateral intraparietal cortex (LIP in the dorsal stream, based on population decoding of gaze angle modulations of neural visual responses (i.e., eye-position gain fields. Here we explore the basis of such spatial encoding differences through modeling of gain field characteristics. We created a population of model neurons, each having a different eye-position gain field. This population was used to reconstruct eye-position visual space using multidimensional scaling. As gain field shapes have never been well established experimentally, we examined different functions, including planar, sigmoidal, elliptical, hyperbolic, and mixtures of those functions. All functions successfully recovered positions, indicating weak constraints on allowable gain field shapes. We then used a genetic algorithm to modify the characteristics of model gain field populations until the recovered spatial maps closely matched those derived from monkey neurophysiological data in AIT and LIP. The primary differences found between model AIT and LIP gain fields were that AIT gain fields were more foveally dominated. That is, gain fields in AIT operated on smaller spatial scales and smaller dispersions than in LIP. Thus we show that the geometry of eye-position visual space depends on the population characteristics of gain fields, and that differences in gain field characteristics for different cortical areas may underlie differences in the representation of space.

  5. Challenges to the Common Clinical Paradigm for Diagnosis of Glaucomatous Damage With OCT and Visual Fields.

    Science.gov (United States)

    Hood, Donald C; De Moraes, Carlos Gustavo

    2018-02-01

    The most common clinical paradigm (CCP) for diagnosing glaucoma includes a visual field (VF) with a 6° test grid (e.g., the 24-2 or 30-2 test pattern) and an optical coherence tomography (OCT) scan of the optic disc. Furthermore, these tests are assessed based upon quantitative metrics (e.g., the pattern standard deviation [PSD] of the VF and the global retinal nerve fiber thickness of the OCT disc scan). This CCP is facing three challenges. First, the macular region (i.e., ±8° from fixation) is affected early in the glaucomatous process, and the CCP can miss and/or underestimate the damage. Second, use of the typical VF and OCT metrics underestimates the degree of agreement between structural (OCT) and functional (VF) damage. Third, resolution of the OCT scan has improved, and local glaucomatous damage can be visualized like never before. However, the clinician often does not look at the OCT scan image. Together these challenges argue for a modification of the VF test pattern and OCT protocol, replacement of metrics with a comparison of abnormal regions on VF and OCT, and careful inspection of actual OCT scan images. In principle, the CCP could be modified easily. In practice, change is facing a number of impediments.

  6. Determination of relative CMRO2 from CBF and BOLD changes: significant increase of oxygen consumption rate during visual stimulation

    DEFF Research Database (Denmark)

    Kim, S.G.; Rostrup, Egill; Larsson, H.B.

    1999-01-01

    be estimated during neural activity using a reference condition obtained with known CMRO2 change. In this work, nine subjects were studied at a magnetic field of 1.5 T; each subject underwent inhalation of a 5% carbon dioxide gas mixture as a reference and two visual stimulation studies. Relative CBF and BOLD...

  7. Visualizing Special Relativity: The Field of An Electric Dipole Moving at Relativistic Speed

    Science.gov (United States)

    Smith, Glenn S.

    2011-01-01

    The electromagnetic field is determined for a time-varying electric dipole moving with a constant velocity that is parallel to its moment. Graphics are used to visualize this field in the rest frame of the dipole and in the laboratory frame when the dipole is moving at relativistic speed. Various phenomena from special relativity are clearly…

  8. The effectiveness of visual simulation training in improving inner circle fielding performance in cricket

    NARCIS (Netherlands)

    Hopwood, M.; Mann, D.L.; Farrow, D.; Neilsen, T.

    2011-01-01

    This study examined the effectiveness of visual-perceptual training for improving fielding performance in cricket. Twelve highly-skilled cricket players completed a video-based decision-making test and an in-situ fielding test before and after a six-week training intervention. During this period,

  9. Visual Field Losses in Patients with Migraine without Aura and Tension-Type Headache.

    Science.gov (United States)

    Yener, Arif Ü; Korucu, Osman

    2017-04-01

    The aim of the study was to compare the visual fields during pain attacks in the patients with migraine without aura and tension-type headache using automated perimetry. In this study 25 patients with migraine and 25 patients with tension-type headache were evaluated.The optic disc, macula and retina were assessed and patients with normal values were enrolled into the study. Intraocular pressure of all patients were measured. Furthermore, visual field test was applied to both groups using Humphrey field analyzer (Carl-Zeiss Meditec, model-745 i, Dublin, CA, USA). Both mean deviation and pattern standart deviation values of these two goups were not statistically significant.

  10. Age-related changes in visual exploratory behavior in a natural scene setting.

    Science.gov (United States)

    Hamel, Johanna; De Beukelaer, Sophie; Kraft, Antje; Ohl, Sven; Audebert, Heinrich J; Brandt, Stephan A

    2013-01-01

    Diverse cognitive functions decline with increasing age, including the ability to process central and peripheral visual information in a laboratory testing situation (useful visual field of view). To investigate whether and how this influences activities of daily life, we studied age-related changes in visual exploratory behavior in a natural scene setting: a driving simulator paradigm of variable complexity was tested in subjects of varying ages with simultaneous eye- and head-movement recordings via a head-mounted camera. Detection and reaction times were also measured by visual fixation and manual reaction. We considered video computer game experience as a possible influence on performance. Data of 73 participants of varying ages were analyzed, driving two different courses. We analyzed the influence of route difficulty level, age, and eccentricity of test stimuli on oculomotor and driving behavior parameters. No significant age effects were found regarding saccadic parameters. In the older subjects head-movements increasingly contributed to gaze amplitude. More demanding courses and more peripheral stimuli locations induced longer reaction times in all age groups. Deterioration of the functionally useful visual field of view with increasing age was not suggested in our study group. However, video game-experienced subjects revealed larger saccade amplitudes and a broader distribution of fixations on the screen. They reacted faster to peripheral objects suggesting the notion of a general detection task rather than perceiving driving as a central task. As the video game-experienced population consisted of younger subjects, our study indicates that effects due to video game experience can easily be misinterpreted as age effects if not accounted for. We therefore view it as essential to consider video game experience in all testing methods using virtual media.

  11. Age-related changes in visual exploratory behavior in a natural scene setting

    Directory of Open Access Journals (Sweden)

    Johanna eHamel

    2013-06-01

    Full Text Available Diverse cognitive functions decline with increasing age, including the ability to process central and peripheral visual information in a laboratory testing situation (useful visual field of view. To investigate whether and how this influences activities of daily life, we studied age-related changes in visual exploratory behavior in a natural scene setting: a driving simulator paradigm of variable complexity was tested in subjects of varying ages with simultaneous eye- and head-movement recordings via a head-mounted camera. Detection and reaction times were also measured by visual fixation and manual reaction. We considered video computer game experience as a possible influence on performance. Data of 73 participants of varying ages were analyzed, driving two different courses. We analyzed the influence of route difficulty level, age and eccentricity of test stimuli on oculomotor and driving behavior parameters. No significant age effects were found regarding saccadic parameters. In the older subjects head-movements increasingly contributed to gaze amplitude. More demanding courses and more peripheral stimuli locations, induced longer reaction times in all age groups. Deterioration of the functionally useful visual field of view with increasing age was not suggested in our study group. However, video game-experienced subjects revealed larger saccade amplitudes and a broader distribution of fixations on the screen. They reacted faster to peripheral objects suggesting the notion of a general detection task rather than perceiving driving as a central task. As the video game experienced population consisted of younger subjects, our study indicates that effects due to video game experience can easily be misinterpreted as age effects if not accounted for. We therefore view it as essential to consider video game experience in all testing methods using virtual media.

  12. Visualizing intramyocardial steam formation with a radiofrequency ablation catheter incorporating near-field ultrasound.

    Science.gov (United States)

    Wright, Matthew; Harks, Erik; Deladi, Szabolcs; Fokkenrood, Steven; Zuo, Fei; Van Dusschoten, Anneke; Kolen, Alexander F; Belt, Harm; Sacher, Frederic; Hocini, Mélèze; Haïssaguerre, Michel; Jaïs, Pierre

    2013-12-01

    Steam pops are a risk of irrigated RF ablation even when limiting power delivery. There is currently no way to predict gas formation during ablation. It would be useful to visualize intramyocardial gas formation prior to a steam pop occurring using near-field ultrasound integrated into a RF ablation catheter. In an in vivo open-chest ovine model (n = 9), 86 lesions were delivered to the epicardial surface of the ventricles. Energy was delivered for 15-60 seconds, to achieve lesions with and without steam pops, based on modeling data. The ultrasound image was compared to a digital audio recording from within the pericardium by a blinded observer. Of 86 lesions, 28 resulted in an audible steam pop. For lesions that resulted in a steam pop compared to those that did not (n = 58), the mean power delivered was 8.0 ± 1.8 W versus 6.7 ± 2.0 W, P = 0.006. A change in US contrast due to gas formation in the tissue occurred in all lesions that resulted in a steam pop. In 4 ablations, a similar change in US contrast was observed in the tissue and RF delivery was stopped; in these cases, no pop occurred. The mean depth of gas formation was 0.9 ± 0.8 mm, which correlated with maximal temperature predicted by modeling. Changes in US contrast occurred 7.6 ± 7.2 seconds before the impedance rise and 7.9 ± 6.2 seconds (0.1-17.0) before an audible pop. Integrated US in an RF ablation catheter is able to visualize gas formation intramyocardially several seconds prior to a steam pop occurring. This technology may help prevent complications arising from steam pops. © 2013 Wiley Periodicals, Inc.

  13. Hawk eyes I: diurnal raptors differ in visual fields and degree of eye movement.

    Directory of Open Access Journals (Sweden)

    Colleen T O'Rourke

    Full Text Available BACKGROUND: Different strategies to search and detect prey may place specific demands on sensory modalities. We studied visual field configuration, degree of eye movement, and orbit orientation in three diurnal raptors belonging to the Accipitridae and Falconidae families. METHODOLOGY/PRINCIPAL FINDINGS: We used an ophthalmoscopic reflex technique and an integrated 3D digitizer system. We found inter-specific variation in visual field configuration and degree of eye movement, but not in orbit orientation. Red-tailed Hawks have relatively small binocular areas (∼33° and wide blind areas (∼82°, but intermediate degree of eye movement (∼5°, which underscores the importance of lateral vision rather than binocular vision to scan for distant prey in open areas. Cooper's Hawks' have relatively wide binocular fields (∼36°, small blind areas (∼60°, and high degree of eye movement (∼8°, which may increase visual coverage and enhance prey detection in closed habitats. Additionally, we found that Cooper's Hawks can visually inspect the items held in the tip of the bill, which may facilitate food handling. American Kestrels have intermediate-sized binocular and lateral areas that may be used in prey detection at different distances through stereopsis and motion parallax; whereas the low degree eye movement (∼1° may help stabilize the image when hovering above prey before an attack. CONCLUSIONS: We conclude that: (a there are between-species differences in visual field configuration in these diurnal raptors; (b these differences are consistent with prey searching strategies and degree of visual obstruction in the environment (e.g., open and closed habitats; (c variations in the degree of eye movement between species appear associated with foraging strategies; and (d the size of the binocular and blind areas in hawks can vary substantially due to eye movements. Inter-specific variation in visual fields and eye movements can influence

  14. Hawk eyes I: diurnal raptors differ in visual fields and degree of eye movement.

    Science.gov (United States)

    O'Rourke, Colleen T; Hall, Margaret I; Pitlik, Todd; Fernández-Juricic, Esteban

    2010-09-22

    Different strategies to search and detect prey may place specific demands on sensory modalities. We studied visual field configuration, degree of eye movement, and orbit orientation in three diurnal raptors belonging to the Accipitridae and Falconidae families. We used an ophthalmoscopic reflex technique and an integrated 3D digitizer system. We found inter-specific variation in visual field configuration and degree of eye movement, but not in orbit orientation. Red-tailed Hawks have relatively small binocular areas (∼33°) and wide blind areas (∼82°), but intermediate degree of eye movement (∼5°), which underscores the importance of lateral vision rather than binocular vision to scan for distant prey in open areas. Cooper's Hawks' have relatively wide binocular fields (∼36°), small blind areas (∼60°), and high degree of eye movement (∼8°), which may increase visual coverage and enhance prey detection in closed habitats. Additionally, we found that Cooper's Hawks can visually inspect the items held in the tip of the bill, which may facilitate food handling. American Kestrels have intermediate-sized binocular and lateral areas that may be used in prey detection at different distances through stereopsis and motion parallax; whereas the low degree eye movement (∼1°) may help stabilize the image when hovering above prey before an attack. We conclude that: (a) there are between-species differences in visual field configuration in these diurnal raptors; (b) these differences are consistent with prey searching strategies and degree of visual obstruction in the environment (e.g., open and closed habitats); (c) variations in the degree of eye movement between species appear associated with foraging strategies; and (d) the size of the binocular and blind areas in hawks can vary substantially due to eye movements. Inter-specific variation in visual fields and eye movements can influence behavioral strategies to visually search for and track prey while

  15. Field visual perspective during autobiographical memory recall is less frequent among patients with schizophrenia.

    Science.gov (United States)

    Potheegadoo, Jevita; Berna, Fabrice; Cuervo-Lombard, Christine; Danion, Jean-Marie

    2013-10-01

    There is growing interest in clinical research regarding the visual perspective adopted during memory retrieval, because it reflects individuals' self-attitude towards their memories of past personal events. Several autobiographical memory deficits, including low specificity of personal memories, have been identified in schizophrenia, but visual perspective during autobiographical memory retrieval has not yet been investigated in patients. The aim of this study was therefore to investigate the visual perspective with which patients visualize themselves when recalling autobiographical memories and to assess the specificity of their memories which is a major determinant of visual perspective. Thirty patients with schizophrenia and 30 matched controls recalled personal events from 4 life periods. After each recall, they were asked to report their visual perspective (Field or Observer) associated with the event. The specificity of their memories was assessed by independent raters. Our results showed that patients reported significantly fewer Field perspectives than comparison participants. Patients' memories, whether recalled with Field or Observer perspectives, were less specific and less detailed. Our results indicate that patients with schizophrenia adopt Field perspectives less frequently than comparison participants, and that this may contribute to a weakened sense of the individual of being an actor of his past events, and hence to a reduced sense of self. They suggest that this may be related to low specificity of memories and that all the important aspects involved in re-experiencing autobiographical events are impaired in patients with schizophrenia. © 2013 Elsevier B.V. All rights reserved.

  16. Correlation between optic nerve head structural parameters and glaucomatous visual field indices

    Directory of Open Access Journals (Sweden)

    Mizumoto K

    2014-06-01

    Full Text Available Kyoichi Mizumoto,1 Masahiko Gosho,2 Masahiro Zako1 1Department of Ophthalmology, Aichi Medical University, Nagakute, Aichi, Japan; 2Advanced Medical Research Center, Aichi Medical University, Nagakute, Aichi, Japan Abstract: We examined associations between optic nerve head structural parameters and glaucomatous visual field indices. The study population included patients with glaucomatous optic neuropathy who were evaluated at Aichi Medical University, Nagakute, Aichi, Japan, from October 2010 to January 2011. A total of 57 eyes from 33 patients were assessed. We measured visual field using a Humphrey field analyzer, peripapillary retinal nerve fiber layer thickness (RNFL-T, and Bruch’s membrane opening-minimum rim width (BMO-MRW using spectral domain optical coherence tomography, and rim area with referring three-dimensional photography. Spearman’s rank correlation coefficients were calculated between the threshold of visual sensitivity or total deviation of visual field and the following five optic nerve head structural parameters: RNFL-T length, BMO-MRW length, rim area, and calculated RNFL-T and BMO-MRW volumes (each length multiplied by rim area. The Akaike information criterion was calculated to determine which structural parameter was the best predictor of each visual field index. Threshold of visual sensitivity had correlation coefficients of 0.23 with global sector of RNFL-T, 0.32 with BMO-MRW, 0.14 with rim area, 0.21 with RNFL-T volume, and 0.26 with BMO-MRW volume. The correlation coefficients for each parameter with total deviation of visual field were 0.22, 0.33, 0.28, 0.36, and 0.37, respectively. The Akaike information criterion of BMO-MRW showed the smallest values in analyses of both threshold of visual sensitivity and total deviation. The present results show that RNFL-T volume and BMO-MRW volume were more strongly correlated with total deviation than BMO-MRW, but BMO-MRW appeared to be the best predictor of the

  17. Effect of sleep deprivation and driving duration on the useful visual field in younger and older subjects during simulator driving.

    Science.gov (United States)

    Rogé, Joceline; Pébayle, Thierry; El Hannachi, Saida; Muzet, Alain

    2003-06-01

    Nine older subjects (40-51 years) and 10 younger subjects (18-30 years) took part in two one-hour driving sessions. They performed a very monotonous task during which they had to follow a vehicle either after a complete night of sleep or after one night of sleep deprivation. While driving their useful visual field was assessed by introducing signals that would appear on the whole road scene. The analysis of the data indicates that the ability to process peripheral signals deteriorates with age, driving duration and sleep deprivation. However, the effects of these three variables on the peripheral visual ability are not similar in a dual task. The driver's useful visual field changes with age and prolongation of the monotonous driving activity according to a tunnel vision phenomenon. On the other hand, a sleep debt deteriorates the useful visual field according to a general interference phenomenon. These results are discussed in terms of decrease in the level of arousal and increase of fatigue.

  18. Stimulus-driven changes in the direction of neural priming during visual word recognition.

    Science.gov (United States)

    Pas, Maciej; Nakamura, Kimihiro; Sawamoto, Nobukatsu; Aso, Toshihiko; Fukuyama, Hidenao

    2016-01-15

    Visual object recognition is generally known to be facilitated when targets are preceded by the same or relevant stimuli. For written words, however, the beneficial effect of priming can be reversed when primes and targets share initial syllables (e.g., "boca" and "bono"). Using fMRI, the present study explored neuroanatomical correlates of this negative syllabic priming. In each trial, participants made semantic judgment about a centrally presented target, which was preceded by a masked prime flashed either to the left or right visual field. We observed that the inhibitory priming during reading was associated with a left-lateralized effect of repetition enhancement in the inferior frontal gyrus (IFG), rather than repetition suppression in the ventral visual region previously associated with facilitatory behavioral priming. We further performed a second fMRI experiment using a classical whole-word repetition priming paradigm with the same hemifield procedure and task instruction, and obtained well-known effects of repetition suppression in the left occipito-temporal cortex. These results therefore suggest that the left IFG constitutes a fast word processing system distinct from the posterior visual word-form system and that the directions of repetition effects can change with intrinsic properties of stimuli even when participants' cognitive and attentional states are kept constant. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Visual field differences in visual word recognition can emerge purely from perceptual learning: evidence from modeling Chinese character pronunciation.

    Science.gov (United States)

    Hsiao, Janet Hui-Wen

    2011-11-01

    In Chinese orthography, a dominant character structure exists in which a semantic radical appears on the left and a phonetic radical on the right (SP characters); a minority opposite arrangement also exists (PS characters). As the number of phonetic radical types is much greater than semantic radical types, in SP characters the information is skewed to the right, whereas in PS characters it is skewed to the left. Through training a computational model for SP and PS character recognition that takes into account of the locations in which the characters appear in the visual field during learning, but does not assume any fundamental hemispheric processing difference, we show that visual field differences can emerge as a consequence of the fundamental structural differences in information between SP and PS characters, as opposed to the fundamental processing differences between the two hemispheres. This modeling result is also consistent with behavioral naming performance. This work provides strong evidence that perceptual learning, i.e., the information structure of word stimuli to which the readers have long been exposed, is one of the factors that accounts for hemispheric asymmetry effects in visual word recognition. Copyright © 2011 Elsevier Inc. All rights reserved.

  20. Effects of Visual Speech on Early Auditory Evoked Fields - From the Viewpoint of Individual Variance.

    Directory of Open Access Journals (Sweden)

    Izumi Yahata

    Full Text Available The effects of visual speech (the moving image of the speaker's face uttering speech sound on early auditory evoked fields (AEFs were examined using a helmet-shaped magnetoencephalography system in 12 healthy volunteers (9 males, mean age 35.5 years. AEFs (N100m in response to the monosyllabic sound /be/ were recorded and analyzed under three different visual stimulus conditions, the moving image of the same speaker's face uttering /be/ (congruent visual stimuli or uttering /ge/ (incongruent visual stimuli, and visual noise (still image processed from speaker's face using a strong Gaussian filter: control condition. On average, latency of N100m was significantly shortened in the bilateral hemispheres for both congruent and incongruent auditory/visual (A/V stimuli, compared to the control A/V condition. However, the degree of N100m shortening was not significantly different between the congruent and incongruent A/V conditions, despite the significant differences in psychophysical responses between these two A/V conditions. Moreover, analysis of the magnitudes of these visual effects on AEFs in individuals showed that the lip-reading effects on AEFs tended to be well correlated between the two different audio-visual conditions (congruent vs. incongruent visual stimuli in the bilateral hemispheres but were not significantly correlated between right and left hemisphere. On the other hand, no significant correlation was observed between the magnitudes of visual speech effects and psychophysical responses. These results may indicate that the auditory-visual interaction observed on the N100m is a fundamental process which does not depend on the congruency of the visual information.

  1. Automated static perimetry: the influence of myopic anisometropia on evaluation of visual field.

    Science.gov (United States)

    Perić, Sanja; Cerovski, Branimir; Perić, Porin; Skegro, Ivan; Tiljak, Hrvoje

    2013-04-01

    The aim of study was to establish which level of myopic refractive error influences visual field defects in automated static perimetry, if these defects are typical, and if optimal correction normalized the visual field. The study included 100 patients (200 eyes) divided into three groups according to the severity of the myopic refractive error: group A (till -3.25 Dsph), group B (-3.50 Dsph to -5.25 Dsph) and group C (-5.50 Dsph to -8.00 Dsph). The control group included 20 emmetropes (40 eyes). This study confirms that optimal corrected and uncorrected myopia up to -3.25 Dsph does not produce quantitative visual field defects, when tested by static automated perimetry. Even in optimally corrected myopics, with myopia higher than -5.50 Dsph, visual field defects on gray scale can be found. Defects are in the intermediary zone with more prominent defects in the upper quadrants. Visual field indices (MD, MS, LV RF) were completely normalized.

  2. Apparent motion from outside the visual field, retinotopic cortices may register extra-retinal positions.

    Directory of Open Access Journals (Sweden)

    Martin Szinte

    Full Text Available Observers made a saccade between two fixation markers while a probe was flashed sequentially at two locations on a side screen. The first probe was presented in the far periphery just within the observer's visual field. This target was extinguished and the observers made a large saccade away from the probe, which would have left it far outside the visual field if it had still been present. The second probe was then presented, displaced from the first in the same direction as the eye movement and by about the same distance as the saccade step. Because both eyes and probes shifted by similar amounts, there was little or no shift between the first and second probe positions on the retina. Nevertheless, subjects reported seeing motion corresponding to the spatial displacement not the retinal displacement. When the second probe was presented, the effective location of the first probe lay outside the visual field demonstrating that apparent motion can be seen from a location outside the visual field to a second location inside the visual field. Recent physiological results suggest that target locations are "remapped" on retinotopic representations to correct for the effects of eye movements. Our results suggest that the representations on which this remapping occurs include locations that fall beyond the limits of the retina.

  3. Overview of long-term field experiments in Germany - metadata visualization

    Science.gov (United States)

    Muqit Zoarder, Md Abdul; Heinrich, Uwe; Svoboda, Nikolai; Grosse, Meike; Hierold, Wilfried

    2017-04-01

    BonaRes ("soil as a sustainable resource for the bioeconomy") is conducting to collect data and metadata of agricultural long-term field experiments (LTFE) of Germany. It is funded by the German Federal Ministry of Education and Research (BMBF) under the umbrella of the National Research Strategy BioEconomy 2030. BonaRes consists of ten interdisciplinary research project consortia and the 'BonaRes - Centre for Soil Research'. BonaRes Data Centre is responsible for collecting all LTFE data and regarding metadata into an enterprise database upon higher level of security and visualization of the data and metadata through data portal. In the frame of the BonaRes project, we are compiling an overview of long-term field experiments in Germany that is based on a literature review, the results of the online survey and direct contacts with LTFE operators. Information about research topic, contact person, website, experiment setup and analyzed parameters are collected. Based on the collected LTFE data, an enterprise geodatabase is developed and a GIS-based web-information system about LTFE in Germany is also settled. Various aspects of the LTFE, like experiment type, land-use type, agricultural category and duration of experiment, are presented in thematic maps. This information system is dynamically linked to the database, which means changes in the data directly affect the presentation. An easy data searching option using LTFE name, -location or -operators and the dynamic layer selection ensure a user-friendly web application. Dispersion and visualization of the overlapping LTFE points on the overview map are also challenging and we make it automatized at very zoom level which is also a consistent part of this application. The application provides both, spatial location and meta-information of LTFEs, which is backed-up by an enterprise geodatabase, GIS server for hosting map services and Java script API for web application development.

  4. The Effect of Attentional Cueing and Spatial Uncertainty in Visual Field Testing.

    Directory of Open Access Journals (Sweden)

    Jack Phu

    Full Text Available To determine the effect of reducing spatial uncertainty by attentional cueing on contrast sensitivity at a range of spatial locations and with different stimulus sizes.Six observers underwent perimetric testing with the Humphrey Visual Field Analyzer (HFA full threshold paradigm, and the output thresholds were compared to conditions where stimulus location was verbally cued to the observer. We varied the number of points cued, the eccentric and spatial location, and stimulus size (Goldmann size I, III and V. Subsequently, four observers underwent laboratory-based psychophysical testing on a custom computer program using Method of Constant Stimuli to determine the frequency-of-seeing (FOS curves with similar variables.We found that attentional cueing increased contrast sensitivity when measured using the HFA. We report a difference of approximately 2 dB with size I at peripheral and mid-peripheral testing locations. For size III, cueing had a greater effect for points presented in the periphery than in the mid-periphery. There was an exponential decay of the effect of cueing with increasing number of elements cued. Cueing a size V stimulus led to no change. FOS curves generated from laboratory-based psychophysical testing confirmed an increase in contrast detection sensitivity under the same conditions. We found that the FOS curve steepened when spatial uncertainty was reduced.We show that attentional cueing increases contrast sensitivity when using a size I or size III test stimulus on the HFA when up to 8 points are cued but not when a size V stimulus is cued. We show that this cueing also alters the slope of the FOS curve. This suggests that at least 8 points should be used to minimise potential attentional factors that may affect measurement of contrast sensitivity in the visual field.

  5. Low-level Active Visual Navigation: Increasing robustness of vision-based localization using potential fields

    OpenAIRE

    Rodrigues, Romulo T.; Basiri, Meysam; Aguiar, A. Pedro; Miraldo, Pedro

    2018-01-01

    This paper proposes a low-level visual navigation algorithm to improve visual localization of a mobile robot. The algorithm, based on artificial potential fields, associates each feature in the current image frame with an attractive or neutral potential energy, with the objective of generating a control action that drives the vehicle towards the goal, while still favoring feature-rich areas within a local scope, \\replaced{thus improving}{improving in this way} the localization performance. On...

  6. Response properties of local field potentials and multiunit activity in the mouse visual cortex.

    Science.gov (United States)

    Land, R; Engler, G; Kral, A; Engel, A K

    2013-12-19

    Extracellular local field potentials (LFPs) and multiunit activity (MUA) reflect the spatially integrated activity of multiple neurons in a given cortical structure. In the cat and primate visual cortices, these signals exhibit selectivity for visual stimulus features, such as orientation, direction of motion or spatial frequency. In the mouse visual cortex, a model which has been increasingly used in visual neuroscience, the visual stimulus selectivity of population signals has not been examined in detail. We recorded LFPs and MUA using multielectrode arrays and two derived measures, the high-pass filtered continuous MUA and the bipolar first spatial derivative of the LFP, in the visual cortex of isoflurane-anesthetized C57Bl/6 mice. We analyzed the onset latency and characterized the receptive fields in addition to the direction, orientation, and spatial and temporal frequency preferences of these signals. Population signals exhibited onset latencies as short as ∼30ms and possessed receptive fields as large as ∼38° with MUA receptive fields smaller than those of LFPs. All four population signals exhibited similar spatial frequency preferences (∼0.1 cycles per degree) and temporal frequency preferences (∼1 cycle per second). However, for all population signals, spatial and frequency tunings were broad and orientation and direction of motion preferences were absent. The characterization of the visual stimulus selectivity of LFPs and MUA in the mouse visual cortex should provide information regarding their usability in characterizing stimulus properties and disclose possible limitations. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

  7. Relationship between visual field loss and contrast threshold elevation in glaucoma

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    Jay JL

    2005-09-01

    Full Text Available Abstract Background There is a considerable body of literature which indicates that contrast thresholds for the detection of sinusoidal grating patterns are abnormally high in glaucoma, though just how these elevations are related to the location of visual field loss remains unknown. Our aim, therefore, has been to determine the relationship between contrast threshold elevation and visual field loss in corresponding regions of the peripheral visual field in glaucoma patients. Methods Contrast thresholds were measured in arcuate regions of the superior, inferior, nasal and temporal visual field in response to laser interference fringes presented in the Maxwellian view. The display consisted of vertical green stationary laser interference fringes of spatial frequency 1.0 c deg-1 which appeared in a rotatable viewing area in the form of a truncated quadrant extending from 10 to 20° from fixation which was marked with a central fixation light. Results were obtained from 36 normal control subjects in order to provide a normal reference for 21 glaucoma patients and 5 OHT (ocular hypertensive patients for whom full clinical data, including Friedmann visual fields, had been obtained. Results Abnormally high contrast thresholds were identified in 20 out of 21 glaucoma patients and in 2 out of 5 OHT patients when compared with the 95% upper prediction limit for normal values from one eye of the 36 normal age-matched control subjects. Additionally, inter-ocular differences in contrast threshold were also abnormally high in 18 out of 20 glaucoma patients who had vision in both eyes compared with the 95% upper prediction limit. Correspondence between abnormally high contrast thresholds and visual field loss in the truncated quadrants was significant in 5 patients, borderline in 4 patients and absent in 9 patients. Conclusion While the glaucoma patients tested in our study invariably had abnormally high contrast thresholds in one or more of the truncated

  8. The Effects of Compensatory Scanning Training on Mobility in Patients with Homonymous Visual Field Defects: A Randomized Controlled Trial.

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    Gera A de Haan

    Full Text Available Homonymous visual field defects (HVFD are a common consequence of postchiasmatic acquired brain injury and often lead to mobility-related difficulties. Different types of compensatory scanning training have been developed, aimed at decreasing consequences of the HVFD by changing visual scanning.The aim of the present study is to examine the effects of a compensatory scanning training program using horizontal scanning on mobility-related activities and participation in daily life.The main interest of this study is to assess the effectiveness of training on mobility-related activities and participation in daily life. Visual scanning tests, such as dot counting and visual search, and control measures for visual functions and reading have been included as well. First, it is examined how performance on scanning and mobility-related measures is affected in patients with HVFD by comparing scores with scores of a healthy control group (n = 25. Second, the effect of training is assessed using an RCT design, in which performance of 26 patients before and after training is compared to performance of 23 patients in a waiting list control group.Self-reported improvements after training were found, accompanied by improvements in detecting peripheral stimuli and avoiding obstacles during walking, especially in dual task situations in which a second task limits the attentional capacity available for compensatory scanning. Training only improved mobility-related activities in which detection of peripheral stimuli is important, while no improvement was found on tests that require other visual skills, such as reading, visual counting and visual search.This is the first RCT to evaluate the effects of a compensatory scanning training that is based on a systematic horizontal scanning rhythm. This training improved mobility-related activities. The results suggest that different types of compensatory scanning strategies are appropriate for different types of activities

  9. The Effects of Compensatory Scanning Training on Mobility in Patients with Homonymous Visual Field Defects: A Randomized Controlled Trial

    Science.gov (United States)

    de Haan, Gera A.; Melis-Dankers, Bart J. M.; Brouwer, Wiebo H.; Tucha, Oliver; Heutink, Joost

    2015-01-01

    Introduction Homonymous visual field defects (HVFD) are a common consequence of postchiasmatic acquired brain injury and often lead to mobility-related difficulties. Different types of compensatory scanning training have been developed, aimed at decreasing consequences of the HVFD by changing visual scanning. Aim The aim of the present study is to examine the effects of a compensatory scanning training program using horizontal scanning on mobility-related activities and participation in daily life. Method The main interest of this study is to assess the effectiveness of training on mobility-related activities and participation in daily life. Visual scanning tests, such as dot counting and visual search, and control measures for visual functions and reading have been included as well. First, it is examined how performance on scanning and mobility-related measures is affected in patients with HVFD by comparing scores with scores of a healthy control group (n = 25). Second, the effect of training is assessed using an RCT design, in which performance of 26 patients before and after training is compared to performance of 23 patients in a waiting list control group. Results Self-reported improvements after training were found, accompanied by improvements in detecting peripheral stimuli and avoiding obstacles during walking, especially in dual task situations in which a second task limits the attentional capacity available for compensatory scanning. Training only improved mobility-related activities in which detection of peripheral stimuli is important, while no improvement was found on tests that require other visual skills, such as reading, visual counting and visual search. Conclusion This is the first RCT to evaluate the effects of a compensatory scanning training that is based on a systematic horizontal scanning rhythm. This training improved mobility-related activities. The results suggest that different types of compensatory scanning strategies are appropriate for

  10. Developing Aesthetically Compelling Visualizations for Documenting and Communicating Alaskan Glacier and Landscape Change

    Science.gov (United States)

    Molnia, B. F.

    2016-12-01

    For 50 years I have investigated glacier dynamics and attempted to convey this information to others. Since 2000, my focus has been on capturing and documenting decadal and century-scale Alaskan glacier and landscape change using precision repeat photography and on broadly communicate these results through simple, aesthetically compelling, unambiguous visualizations. As a young geologist, I spent the summer of 1968 on the Juneau Icefield, photographing its surface features and margins. Since then, I have taken 150,000 photographs of Alaskan glaciers and collected 5,000 historical Alaskan photographs taken by other, the earliest dating back to 1883. This database and my passion for photographing glaciers became the basis for an on-going investigation aimed at visually documenting glacier and landscapes change at more than 200 previously photographed Alaskan locations in Glacier Bay and Kenai Fjords National Parks, Prince William Sound, and the Coast Mountains. Repeat photography is a technique in which a historical and a modern photograph, both having similar fields of view, are compared and contrasted to quantitatively and qualitatively determine their similarities and differences. In precision repeat photography, both photographs have the same field of view, ideally being photographed from the identical location. Since 2000, I have conducted nearly 20 field campaigns to systematically revisit and re-photograph more than 225 fields of view previously captured in the historical photographs. As aesthetics are important in successfully communicating what has changed, substantial time and effort is invested in capturing new, comparable, generally cloud free photographs at each revisited site. The resulting modern images are then paired with similar field-of-view historical images to produce compelling, aesthetic photo pairs which depict long-term glacier, landscape, and ecosystem changes. As a few sites have multiple historical images, photo triplets or quadruplets are

  11. Thickness and clearance visualization based on distance field of 3D objects

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    Masatomo Inui

    2015-07-01

    Full Text Available This paper proposes a novel method for visualizing the thickness and clearance of 3D objects in a polyhedral representation. The proposed method uses the distance field of the objects in the visualization. A parallel algorithm is developed for constructing the distance field of polyhedral objects using the GPU. The distance between a voxel and the surface polygons of the model is computed many times in the distance field construction. Similar sets of polygons are usually selected as close polygons for close voxels. By using this spatial coherence, a parallel algorithm is designed to compute the distances between a cluster of close voxels and the polygons selected by the culling operation so that the fast shared memory mechanism of the GPU can be fully utilized. The thickness/clearance of the objects is visualized by distributing points on the visible surfaces of the objects and painting them with a unique color corresponding to the thickness/clearance values at those points. A modified ray casting method is developed for computing the thickness/clearance using the distance field of the objects. A system based on these algorithms can compute the distance field of complex objects within a few minutes for most cases. After the distance field construction, thickness/clearance visualization at a near interactive rate is achieved.

  12. Structural and functional correlates of visual field asymmetry in the human brain by diffusion kurtosis MRI and functional MRI.

    Science.gov (United States)

    O'Connell, Caitlin; Ho, Leon C; Murphy, Matthew C; Conner, Ian P; Wollstein, Gadi; Cham, Rakie; Chan, Kevin C

    2016-11-09

    Human visual performance has been observed to show superiority in localized regions of the visual field across many classes of stimuli. However, the underlying neural mechanisms remain unclear. This study aims to determine whether the visual information processing in the human brain is dependent on the location of stimuli in the visual field and the corresponding neuroarchitecture using blood-oxygenation-level-dependent functional MRI (fMRI) and diffusion kurtosis MRI, respectively, in 15 healthy individuals at 3 T. In fMRI, visual stimulation to the lower hemifield showed stronger brain responses and larger brain activation volumes than the upper hemifield, indicative of the differential sensitivity of the human brain across the visual field. In diffusion kurtosis MRI, the brain regions mapping to the lower visual field showed higher mean kurtosis, but not fractional anisotropy or mean diffusivity compared with the upper visual field. These results suggested the different distributions of microstructural organization across visual field brain representations. There was also a strong positive relationship between diffusion kurtosis and fMRI responses in the lower field brain representations. In summary, this study suggested the structural and functional brain involvements in the asymmetry of visual field responses in humans, and is important to the neurophysiological and psychological understanding of human visual information processing.

  13. Cases of advanced visual field loss at referral to glaucoma clinics - more men than women?

    Science.gov (United States)

    Crabb, David P; Saunders, Luke J; Edwards, Laura A

    2017-01-01

    In many medical conditions 'late presentation' of disease is more of a problem for men than women. Risk of sight loss from glaucoma is certainly greater in those detected with advanced disease. We performed a retrospective study to test the hypothesis that men are more likely than women to have advanced visual field loss at referral to glaucoma clinics. We used 152 918 Humphrey visual fields from 32 147 patients from three regionally different hospitals in England; no other clinical data were made available apart from patient's age, sex and examination dates. The study population was defined as patients with measureable visual field loss in at least one eye at referral to glaucoma clinics. Cases of advanced visual field loss as defined by the Enhanced Glaucoma Severity Staging method at the first visit to secondary care were used as a proxy measure for late presentation of glaucoma. Age-adjusted relative risk (RR) was calculated as the ratio of the proportion of men to women with this proxy measure. Median (interquartile range) age and MD (worse eye) for 3733 men and 4264 women was 72 (63, 79) and 74 (64, 81) years and -6.4 (-11.7, -3.8) and -6.3 (-11.0, -3.8) dB respectively. Overall proportion of patients with advanced visual field loss at referral to glaucoma clinics was slightly higher in men (25.0%) than in women (22.3%); this difference was statistically significant (p glaucoma is 16% (95% confidence interval: 7-25%) more likely to be a man than a woman. A large number of patients with glaucomatous visual field defects are estimated to have advanced loss in at least one eye on referral to secondary care in England; risk for men more likely presenting with late disease is slightly greater than for women. © 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.

  14. Comparación de la atención visual y campo visual en deportistas en función del nivel de pericia. (Comparison of the visual attention and visual field in athletes depending on their expertise level.

    Directory of Open Access Journals (Sweden)

    Luis Casáis Martínez

    2011-05-01

    Full Text Available ResumenEn los deportes de equipo, el jugador debe de ser capaz de observar lo que ocurre en su entorno a través de un óptimo campo visual para mantener un nivel de atención en todas sus acciones. El objetivo de la presente investigación es comparar la atención visual y campo visual entre deportistas expertos y deportistas amateur. La muestra (N = 60 está formada por 36 deportistas con experiencia y 24 deportistas sin experiencia. El procedimiento utilizado para evaluar el campo visual es la técnica de tarea dual. las variables independientes son el nivel de pericia y la amplitud del campo visual. Las variables dependientes son el éxito (tasa de acierto en una tarea de doble atención y el tiempo de reacción de los estímulos periféricos. Los resultados afirman que los deportistas expertos obtienen menores errores en la tarea atencional que los deportistas no expertos y menor tiempo de reacción visual (p AbstractIn team sports, the player must be able to observe what is happening in his environment, through an optimal visual field, to maintain a level of care in all actions. The aim of this research is to compare the visual attention and the degree of the visual field between experienced athletes and amateur athletes. The sample (N = 60 is composed of 36 experienced athletes and 24 amateur atheletes. The procedure used to evaluate the visual field is the dual task technique. The independent variables are the type of sport and the amplitude of the visual field. The dependent variables are the number of successful (i.e., success rate in a dual attention task and the reaction time of peripheral stimuli. Our data show that, to stimuli located in their visual field, the experienced atheletes get both fewer errors in the attentional task and a shorter visual reaction time than novice athletes (p doi:10.5232/ricyde2011.02305

  15. Change in dynamic visual acuity (DVA) by pupil dilation.

    Science.gov (United States)

    Ueda, Tetsuo; Nawa, Yoshiaki; Yukawa, Eiichi; Taketani, Futoshi; Hara, Yoshiaki

    2006-01-01

    This study was conducted to assess dynamic visual acuity (DVA) under pupil dilation. Pupil dilation may negatively affect driving performance. Thirty healthy young adults (mean age 29.4 years) with pupil dilation participated in this study as the Mydrin P group. In addition to them, 15 healthy young adults (mean age 28.5 years) without pupil dilation were enrolled as the control group. DVA was measured binocularly with free-head viewing at 0, 30, 60, 120, and 360 min after mydriatic drop instillation in both eyes. Pupil size was measured at each time. In the Mydrin P group, DVA significantly improved at 30, 60, and 120 min (ANOVA; p DVA did not significantly change at all measured times (ANOVA; p > .9). DVA was significantly (p DVA was related to the enlargement of the pupil. This study suggests that the pupil size is one factor that may affect DVA. Potential applications of this study include useful information to assess the effect of pupil dilation on driving performance.

  16. Balance in Parkinson's disease patients changing the visual input Equilíbrio na doença de Parkinson alterando as informações visuais

    OpenAIRE

    Hamlet Suarez; Dario Geisinger; Enrique D. Ferreira; Santiago Nogueira; Sofia Arocena; Cecilia San Roman; Alejo Suarez

    2011-01-01

    The description of the postural responses in Parkinson's disease patients when visual information changes from a stable to a moving visual field analyzing the impact on balance in these patients. METHODS (CLINICAL): Limits of Stability, Body center of pressure and balance functional reserve were measured by means of the force platform in 24 Parkinson´s patients in stages 1 and 2 of the Boher classification and 19 volunteers as a control group. Both groups were stimulated with 1-Static visual ...

  17. Demonstration of Cue Recruitment: Change in Visual Appearance by Means of Pavlovian Conditioning

    National Research Council Canada - National Science Library

    Qi Haijiang; Jeffrey A. Saunders; Rebecca W. Stone; Benjamin T. Backus

    2006-01-01

    .... Here we describe a "cue recruitment" experiment, which is a straightforward adaptation of Pavlov's classical conditioning experiment, that we used to measure changes in visual appearance caused...

  18. Dorsal visual pathway changes in patients with comitant extropia.

    Directory of Open Access Journals (Sweden)

    Xiaohe Yan

    Full Text Available BACKGROUND: Strabismus is a disorder in which the eyes are misaligned. Persistent strabismus can lead to stereopsis impairment. The effect of strabismus on human brain is not unclear. The present study is to investigate whether the brain white structures of comitant exotropia patients are impaired using combined T1-weighted imaging and diffusion tensor imaging (DTI. PRINCIPAL FINDINGS: Thirteen patients with comitant strabismus and twelve controls underwent magnetic resonance imaging (MRI with acquisition of T1-weighted and diffusion tensor images. T1-weighted images were used to analyze the change in volume of white matter using optimized voxel-based morphology (VBM and diffusion tensor images were used to detect the change in white matter fibers using voxel-based analysis of DTI in comitant extropia patients. VBM analysis showed that in adult strabismus, white matter volumes were smaller in the right middle occipital gyrus, right occipital lobe/cuneus, right supramarginal gyrus, right cingulate gyrus, right frontal lobe/sub-gyral, right inferior temporal gyrus, left parahippocampa gyrus, left cingulate gyrus, left occipital lobe/cuneus, left middle frontal gyrus, left inferior parietal lobule, and left postcentral gyrus, while no brain region with greater white matter volume was found. Voxel-based analysis of DTI showed lower fractional anisotropy (FA values in the right middle occipital gyrus and right supramarginal gyrus in strabismus patients, while brain region with increased FA value was found in the right inferior frontal gyrus. CONCLUSION: By combining VBM and voxel-based analysis of DTI results, the study suggests that the dorsal visual pathway was abnormal or impaired in patients with comitant exotropia.

  19. Factors Affecting Visual Field Outcome Post-Surgery in Sellar Region Tumors: Retrospective Study.

    Science.gov (United States)

    Sriram, Prabu Rau; Sellamuthu, Puliventhan; Ghani, Abdul Rahman Izani

    2017-12-01

    Despite the broad category of differentials for sellar region, most of them present with similar clinical signs and symptoms. Headache and visual disturbance are among the frequently seen as presenting symptom. Visual field (VF) assessment is one of the crucial component of neuroophtalmologic assessment and mean deviation (MD) value from automated perimetry allows quantification of the visual field defect. We formulated a study to look into the factors that affect the visual field outcome after surgery. All patients with sellar region tumor who has underwent surgery in Queen Elizabeth Hospital from July 2010 to July 2016 were retrospectively analysed through hospital notes. VF assessment via Humphrey visual assessment for these patient pre and post-surgery were reviewed for MD value. Eighty four patients were recruited and out of them, 151 eyes were taken into analysis after excluding eyes with missing data. Mean age of patients were 45.4 years with 70.2% of them were male. Visual disturbance is the commonest presenting symptom with mean duration of symptom prior to surgery is 9.7 months. Majority of them were pituitary adenomas (75%) followed by sellar meningioma (19%), craniopharyngioma (4.8%), and rathke cleft cyst (1.2%). 70.9% of patients showed improvement in VF based on MD outcome. Mean MD for pre surgery and post-surgery were -14.0 dB and -12.4 dB, respectively. Univariate analysis reveals younger age, female sex, shorter duration of symptom, pituitary adenoma, transsphenoidal approach, and transcranial approach favours improvement in VF. Multivariate analysis shows only shorter symptom duration, transphenoidal approach, and transcranial approach are significant for favourable VF outcome when other factors adjusted. Symptom duration and surgical approach were independent factors that affects the visual field after surgery in patients with sellar region tumors.

  20. Effect of Size Change and Brightness Change of Visual Stimuli on Loudness Perception and Pitch Perception of Auditory Stimuli

    Directory of Open Access Journals (Sweden)

    Syouya Tanabe

    2011-10-01

    Full Text Available People obtain a lot of information from visual and auditory sensation on daily life. Regarding the effect of visual stimuli on perception of auditory stimuli, studies of phonological perception and sound localization have been made in great numbers. This study examined the effect of visual stimuli on perception in loudness and pitch of auditory stimuli. We used the image of figures whose size or brightness was changed as visual stimuli, and the sound of pure tone whose loudness or pitch was changed as auditory stimuli. Those visual and auditory stimuli were combined independently to make four types of audio-visual multisensory stimuli for psychophysical experiments. In the experiments, participants judged change in loudness or pitch of auditory stimuli, while they judged the direction of size change or the kind of a presented figure in visual stimuli. Therefore they cannot neglect visual stimuli while they judged auditory stimuli. As a result, perception in loudness and pitch were promoted significantly around their difference limen, when the image was getting bigger or brighter, compared with the case in which the image had no changes. This indicates that perception in loudness and pitch were affected by change in size and brightness of visual stimuli.

  1. Lower corneal hysteresis is associated with more rapid glaucomatous visual field progression.

    Science.gov (United States)

    De Moraes, Carlos V Gustavo; Hill, Victoria; Tello, Celso; Liebmann, Jeffrey M; Ritch, Robert

    2012-01-01

    We investigated the correlation between central corneal thickness (CCT) and corneal hysteresis (CH) and their relationship with the rate of visual field (VF) change. Glaucoma patients who underwent complete ophthalmic examination and tonometry using both the Goldmann applanation tonometer and the Ocular Response Analyzer were prospectively enrolled. Only eyes with ≥5 SITA Standard 24-2 VF tests were included. Automated pointwise linear regression analysis was used to determine VF progression. One hundred fifty-three eyes (153 patients; mean age, 61.3 ± 14.0 y; mean number of VF, 8.5 ± 3.4; mean follow-up time, 5.3 ± 2.0 y) met the enrollment criteria. The mean global rate of VF change was -0.34 ± 0.7 dB/y. Twenty-five eyes (16%) reached a progression endpoint. Progressing eyes had lower CCT (525.0 ± 34.2 vs 542.3 ± 3 8.5 μm, P=0.04) and lower CH (7.5 ± 1.4 vs 9.0 ± 1.8 mm Hg, PCorneal biomechanical and physical properties, such as CH and CCT, are highly correlated and associated with VF progression. As CH may describe corneal properties more completely than thickness alone, it may be a parameter that is better associated with progression.

  2. Evaluation of Visual Field and Imaging Outcomes for Glaucoma Clinical Trials (An American Ophthalomological Society Thesis)

    Science.gov (United States)

    Garway-Heath, David F.; Quartilho, Ana; Prah, Philip; Crabb, David P.; Cheng, Qian; Zhu, Haogang

    2017-01-01

    Purpose To evaluate the ability of various visual field (VF) analysis methods to discriminate treatment groups in glaucoma clinical trials and establish the value of time-domain optical coherence tomography (TD OCT) imaging as an additional outcome. Methods VFs and retinal nerve fibre layer thickness (RNFLT) measurements (acquired by TD OCT) from 373 glaucoma patients in the UK Glaucoma Treatment Study (UKGTS) at up to 11 scheduled visits over a 2 year interval formed the cohort to assess the sensitivity of progression analysis methods. Specificity was assessed in 78 glaucoma patients with up to 11 repeated VF and OCT RNFLT measurements over a 3 month interval. Growth curve models assessed the difference in VF and RNFLT rate of change between treatment groups. Incident progression was identified by 3 VF-based methods: Guided Progression Analysis (GPA), ‘ANSWERS’ and ‘PoPLR’, and one based on VFs and RNFLT: ‘sANSWERS’. Sensitivity, specificity and discrimination between treatment groups were evaluated. Results The rate of VF change was significantly faster in the placebo, compared to active treatment, group (−0.29 vs +0.03 dB/year, Pstatistical significance; sANSWERS did not discriminate treatment groups. Conclusions Although the VF progression-detection method including VF and RNFLT measurements is more sensitive, it does not improve discrimination between treatment arms. PMID:29085257

  3. Functional visual fields: a cross-sectional UK study to determine which visual field paradigms best reflect difficulty with mobility function.

    Science.gov (United States)

    Subhi, Hikmat; Latham, Keziah; Myint, Joy; Crossland, Michael

    2017-11-20

    To develop an appropriate method of assessing visual field (VF) loss which reflects its functional consequences, this study aims to determine which method(s) of assessing VF best reflect mobility difficulty. This cross-sectional observational study took place within a single primary care setting. Participants attended a single session at a University Eye Clinic, Cambridge, UK, with data collected by a single researcher (HS), a qualified optometrist. 50 adult participants with peripheral field impairment were recruited for this study. Individuals with conditions not primarily affecting peripheral visual function, such as macular degeneration, were excluded from the study. Participants undertook three custom and one standard binocular VF tests assessing VF to 60°, and also integrated monocular threshold 24-2 visual fields (IVF). Primary VF outcomes were average mean threshold, percentage of stimuli seen and VF area. VF outcomes were compared with self-reported mobility function assessed with the Independent Mobility Questionnaire, and time taken and patient acceptability were also considered. Receiver operating characteristic (ROC) curves determined which tests best predicted difficulty with mobility tasks. Greater VF loss was associated with greater self-reported mobility difficulty with all field paradigms (R2 0.38-0.48, all Pmobility tasks in ROC analysis. Mean duration of the tests ranged from 1 min 26 s (±9 s) for kinetic assessment to 9 min 23 s (±24 s) for IVF. The binocular VF tests extending to 60° eccentricity all relate similarly to self-reported mobility function, and slightly better than integrated monocular VFs. A kinetic assessment of VF area is quicker than and as effective at predicting mobility function as static threshold assessment. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  4. Emotion separation is completed early and it depends on visual field presentation.

    Directory of Open Access Journals (Sweden)

    Lichan Liu

    Full Text Available It is now apparent that the visual system reacts to stimuli very fast, with many brain areas activated within 100 ms. It is, however, unclear how much detail is extracted about stimulus properties in the early stages of visual processing. Here, using magnetoencephalography we show that the visual system separates different facial expressions of emotion well within 100 ms after image onset, and that this separation is processed differently depending on where in the visual field the stimulus is presented. Seven right-handed males participated in a face affect recognition experiment in which they viewed happy, fearful and neutral faces. Blocks of images were shown either at the center or in one of the four quadrants of the visual field. For centrally presented faces, the emotions were separated fast, first in the right superior temporal sulcus (STS; 35-48 ms, followed by the right amygdala (57-64 ms and medial pre-frontal cortex (83-96 ms. For faces presented in the periphery, the emotions were separated first in the ipsilateral amygdala and contralateral STS. We conclude that amygdala and STS likely play a different role in early visual processing, recruiting distinct neural networks for action: the amygdala alerts sub-cortical centers for appropriate autonomic system response for fight or flight decisions, while the STS facilitates more cognitive appraisal of situations and links appropriate cortical sites together. It is then likely that different problems may arise when either network fails to initiate or function properly.

  5. Active control of the visual field in the starfish Acanthaster planci.

    Science.gov (United States)

    Beer, S; Wentzel, C; Petie, R; Garm, A

    2016-10-01

    Photoreception in echinoderms has been studied for several years with a focus on the dermal photoreceptors of echinoids. Even though spatial vision has been proposed for this dermal photosystem, by far the most advanced system is found in a number of asteroids where an unpaired tube foot at the tip of each arm carries a proper eye, also known as the optical cushion. The eyes resemble compound eyes, except for the lack of true optics, and they typically have between 50 and 250 ommatidia each. These eyes have been known for two centuries but no visually guided behaviors were known in starfish until recently when it was shown that both Linckia laevigata and Acanthaster planci navigate their coral reef habitat using vision. Here we investigate the visual system of A. planci and find that they have active control of their visual field. The distalmost tube foot holding the eye is situated on a movable knob, which bends to adjust the vertical angle of the visual field. On the leading arms the visual field is directed 33° above the horizon, whereas the eyes on the trailing arms are directed 44° above horizontal on average. When the animal traverses an obstacle the knob bends and counteracts most of the arm bending. Further, we examined a previously described behavior, rhythmic arm elevation, and suggest that it allows the animal to scan the surroundings while preventing photoreceptor adaptation and optimizing image contrast. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. A Field Trip to the Moon: Using Cutting-Edge Scientific Visualizations in Astronomy Education

    Science.gov (United States)

    Wyatt, Ryan; Connolly, R.

    2007-05-01

    Visualizations of 3-D models and astronomical data bring the Universe to life for audiences in an immediate and personal way. Computer-generated visuals can now depict space exploration and current astronomical discoveries with unprecedented fidelity, placing complex concepts within reach and communicating the excitement of discovery and exploration to a wide range of ages. Since 1998, the American Museum of Natural History (AMNH) has mapped three-dimensional data groups ranging in scale from the solar neighborhood to the large-scale structure of the Universe: this “Digital Universe” provides the foundation for much of our visualization work. With support from NASA’s Exploration Systems Mission Directorate (ESMD), AMNH and NASA’s Marshall Space Flight Center have utilized this technology to develop an experiential “journey” to the Moon for the immersive planetarium environment. We will present selected visualizations from A Field Trip to the Moon, as well as results from the evaluation research. We describe best-practice teaching strategies for using visualizations to support learning, including strategies to scaffold with authentic activities, use real-world observations, and to create opportunities for questioning and the reporting of findings. Visualizations add a new dimension to teaching and outreach. But more important than simply the presence of technology in the classroom is its implementation, and we will recommend methods for using visualizations effectively to support project-based learning and inquiry.

  7. GABA(A) receptors in visual and auditory cortex and neural activity changes during basic visual stimulation.

    Science.gov (United States)

    Qin, Pengmin; Duncan, Niall W; Wiebking, Christine; Gravel, Paul; Lyttelton, Oliver; Hayes, Dave J; Verhaeghe, Jeroen; Kostikov, Alexey; Schirrmacher, Ralf; Reader, Andrew J; Northoff, Georg

    2012-01-01

    Recent imaging studies have demonstrated that levels of resting γ-aminobutyric acid (GABA) in the visual cortex predict the degree of stimulus-induced activity in the same region. These studies have used the presentation of discrete visual stimulus; the change from closed eyes to open also represents a simple visual stimulus, however, and has been shown to induce changes in local brain activity and in functional connectivity between regions. We thus aimed to investigate the role of the GABA system, specifically GABA(A) receptors, in the changes in brain activity between the eyes closed (EC) and eyes open (EO) state in order to provide detail at the receptor level to complement previous studies of GABA concentrations. We conducted an fMRI study involving two different modes of the change from EC to EO: an EO and EC block design, allowing the modeling of the haemodynamic response, followed by longer periods of EC and EO to allow the measuring of functional connectivity. The same subjects also underwent [(18)F]Flumazenil PET to measure GABA(A) receptor binding potentials. It was demonstrated that the local-to-global ratio of GABA(A) receptor binding potential in the visual cortex predicted the degree of changes in neural activity from EC to EO. This same relationship was also shown in the auditory cortex. Furthermore, the local-to-global ratio of GABA(A) receptor binding potential in the visual cortex also predicted the change in functional connectivity between the visual and auditory cortex from EC to EO. These findings contribute to our understanding of the role of GABA(A) receptors in stimulus-induced neural activity in local regions and in inter-regional functional connectivity.

  8. The changing visual profile of children attending a regional specialist school for the visually impaired in Northern Ireland.

    Science.gov (United States)

    McClelland, Julie; Saunders, Kathryn J; Hill, Nan; Magee, Anne; Shannon, Myrtle; Jackson, A Jonathan

    2007-11-01

    To investigate the changing profile of children attending a special school for visually impaired children over a 30-year period. Between 1975 and 2004, 266 children were identified as having been students in the introductory years to secondary education at Jordanstown School. School records and records from the Regional Paediatric Low Vision Clinic at the Royal Victoria Hospital, Belfast were examined to obtain data regarding age, primary ophthalmic diagnosis, visual acuity and any additional impairment. There was no statistically significant change in mean visual acuity of the children entering the secondary school over this period (p > 0.1). Albinism was the most common single condition (20.3%). Notable also was the reduction in incidence of visual impairment following congenital glaucoma and cataract and the corresponding increase in cortical visual impairment (CVI) during this period. During the last 30 years medical/surgical treatment has reduced the impact of treatable conditions (e.g. cataract) on visual impairment to the extent that their prevalence within this school has decreased. Consequently, children with non-treatable conditions (e.g. albinism) constitute a larger proportion of the school population. An increase in the proportion of children with CVI and learning disability in the school was noted.

  9. Seeing without the Occipito-Parietal Cortex: Simultagnosia as a Shrinkage of the Attentional Visual Field

    Directory of Open Access Journals (Sweden)

    François Michel

    2004-01-01

    Full Text Available Following bi-parietal lesions patient AT showed a severe inability to relocate her attention within a visual field which perimetry proved to be near-normal. An experimental approach with tasks testing visuo-spatial attention demonstrated a shrinkage of A.T.’s attentional visual field. With her visual attention narrowed to a kind of functional tunnel vision, the patient exhibited simultanagnosia (Wolpert, 1924, a symptom previously described in 1909 by Balint under the label of Psychic paralysis of “Gaze”. In striking contrast AT showed an efficient and effortless perception of complex natural scenes, which, according to recent work in normal subjects, necessitate few if any attentional resources.

  10. Seeing without the Occipito-Parietal Cortex: Simultagnosia as a Shrinkage of the Attentional Visual Field

    Science.gov (United States)

    Michel, François; Henaff, Marie-Anne

    2004-01-01

    Following bi-parietal lesions patient AT showed a severe inability to relocate her attention within a visual field which perimetry proved to be near-normal. An experimental approach with tasks testing visuo-spatial attention demonstrated a shrinkage of A.T.’s attentional visual field. With her visual attention narrowed to a kind of functional tunnel vision, the patient exhibited simultanagnosia (Wolpert, 1924), a symptom previously described in 1909 by Balint under the label of Psychic paralysis of “Gaze”. In striking contrast AT showed an efficient and effortless perception of complex natural scenes, which, according to recent work in normal subjects, necessitate few if any attentional resources. PMID:15201489

  11. Seeing without the occipito-parietal cortex: Simultagnosia as a shrinkage of the attentional visual field.

    Science.gov (United States)

    Michel, François; Henaff, Marie-Anne

    2004-01-01

    Following bi-parietal lesions patient AT showed a severe inability to relocate her attention within a visual field which perimetry proved to be near-normal. An experimental approach with tasks testing visuo-spatial attention demonstrated a shrinkage of A.T.'s attentional visual field. With her visual attention narrowed to a kind of functional tunnel vision, the patient exhibited simultanagnosia (Wolpert, 1924), a symptom previously described in 1909 by Balint under the label of Psychic paralysis of "Gaze". In striking contrast AT showed an efficient and effortless perception of complex natural scenes, which, according to recent work in normal subjects, necessitate few if any attentional resources. Copyright 2004 IOS Press

  12. Evaluation of changes in retinal nerve fiber layer thickness and visual functions in cases of optic neuritis and multiple sclerosis

    Directory of Open Access Journals (Sweden)

    Rohit Saxena

    2013-01-01

    Full Text Available Context: Retinal nerve fiber layer (RNFL thinning has been demonstrated in cases of optic neuritis (ON and multiple sclerosis (MS in Caucasian eyes, but no definite RNFL loss pattern or association with visual functions is known in Indian eyes. Aim : To evaluate RNFL thickness in cases of ON and MS, and to correlate it with visual function changes in Indian patients. Settings and Design: Cross-sectional case-control study at a tertiary level institution . Materials and Methods: Cases consisted of patients of (i typical ON without a recent episode (n = 30:39 ON eyes and 21 fellow eyes, (ii MS without ON (n = 15;30 eyes while the controls were age-matched (n = 15; 30 eyes. RNFL thickness was measured using the Stratus 3 °CT. The visual functions tested included the best-corrected visual acuity (BCVA, contrast sensitivity, stereopsis, visual evoked responses, and visual fields. Statistical analysis used: Intergroup analysis was done using ANOVA and Pearson′s correlation coefficient used for associations. Results: RNFL thickness was reduced significantly in the ON and MS patients compared to the controls (P-0.001. Maximum loss is in the temporal quadrant. Lower visual function scores are associated with reduced average overall RNFL thickness. In ON group, RNFL thinning is associated with severe visual field defects while contrast sensitivity has strongest correlation with RNFL in the MS group. Conclusions:RNFL thickness is reduced in ON and MS cases in a pattern similar to Caucasians and is associated with the magnitude of impairment of other visual parameters. Contrast sensitivity and stereoacuity are useful tests to identify subclinical optic nerve involvement in multiple sclerosis.

  13. Autonomous visual exploration creates developmental change in familiarity and novelty seeking behaviors

    Directory of Open Access Journals (Sweden)

    Sammy ePerone

    2013-09-01

    Full Text Available What motivates children to radically transform themselves during early development? We addressed this question in the domain of infant visual exploration. Over the first year, infants’ exploration shifts from familiarity to novelty seeking. This shift is delayed in preterm relative to term infants and is stable within individuals over the course of the first year. Laboratory tasks have shed light on the nature of this familiarity-to-novelty shift, but it is not clear what motivates the infant to change her exploratory style. We probed this by letting a Dynamic Neural Field (DNF model of visual exploration develop itself via accumulating experience in a virtual world. We then situated it in a canonical laboratory task. Much like infants, the model exhibited a familiarity-to-novelty shift. When we manipulated the initial conditions of the model, the model’s performance was developmentally delayed much like preterm infants. This delay was overcome by enhancing the model’s experience during development. We also found that the model’s performance was stable at the level of the individual. Our simulations indicate that novelty seeking emerges with no explicit motivational source via the accumulation of visual experience within a complex, dynamical exploratory system.

  14. Embolic and Nonembolic Transient Monocular Visual Field Loss: A Clinicopathologic Review

    NARCIS (Netherlands)

    Petzold, A.; Islam, N.; Hu, H.H.; Plant, G.T.

    2013-01-01

    Transient monocular blindness and amaurosis fugax are umbrella terms describing a range of patterns of transient monocular visual field loss (TMVL). The incidence rises from ≈1.5/100,000 in the third decade of life to ≈32/100,000 in the seventh decade of life. We review the vascular supply of the

  15. Visualizing MR diffusion tensor fields by dynamic fiber tracking and uncertainty mapping

    NARCIS (Netherlands)

    Ehricke, HH; Klose, U; Grodd, W

    Recent advances in magnetic resonance imaging have provided methods for the acquisition of high-resolution diffusion tensor fields. Their 3D-visualization with streamline-based techniques-called fiber tracking-allow analysis of cerebral white matter tracts for diagnostic, therapeutic as well as

  16. Visual Field Loss Morphology in High- and Normal-Tension Glaucoma

    Directory of Open Access Journals (Sweden)

    Michele Iester

    2012-01-01

    Conclusions. These data suggested that there was no relevant difference in the pointwise analysis between NTG and HTG; however, when visual field areas were compared, no difference in paracentral areas was found between NTG and HTG, but superior nasal step and inferior and superior scotomata showed to be deeper in HTG than in NTG.

  17. Difficulties in daily life reported by patients with homonymous visual field defects

    NARCIS (Netherlands)

    Heutink, Jochem; de Haan, Gera; Melis-Dankers, Bart; Brouwer, Wiebo; Tucha, Oliver

    2015-01-01

    Background: Homonymous visual field defects (HVFDs) are a common consequence of posterior brain injury and may have a substantial influence on ADL and participation in society. In this study we analysed self-reported visionrelated difficulties in daily life in a group of patients with HVFDs.

  18. The value of electrophysiology results in patients with epilepsy and vigabatrin associated visual field loss

    NARCIS (Netherlands)

    Hardus, P; Verduin, WM; Berendschot, TTJM; Kamermans, M; Postma, G; Stilma, JS; van Veelen, CWM

    Purpose: To determine the value of electrophysiological findings in patients with temporal lobe epilepsy and to relate these findings to the amount of concentric contraction of the visual field and the use of vigabatrin, Methods: Electro-retinograms and electro-oculograms were done on 30 patients,

  19. Who Should Be Served? A Dilemma in the Field of Blindness and Visual Impairment

    Science.gov (United States)

    Pogrund, Rona L.

    2017-01-01

    As much as the field of visual impairment has advanced over the last half century and as growing populations of children and adults continue to be served by its practitioners, the issue of personnel shortages to meet the diverse needs of students and consumers seems to continue. More vision professionals are being trained than ever, but it seems…

  20. Visual field loss associated with vigabatrin : Quantification and relation to dosage

    NARCIS (Netherlands)

    Hardus, P; Verduin, WM; Engelsman, M; Edelbroek, PM; Segers, JP; Berendschot, TTJM; Stilma, JS

    Purpose: To describe the correlation between visual field loss and the duration, dosage. and total amount of vigabatrin (VGB) medication in a group of patients with epilepsy. Co-medication of antiepileptic drugs (AEDs) and compliance were also studied. Methods: Ninety-two patients (53 male and 39

  1. Visual field defect as a presenting sign for hemorrhagic stroke caused by sildenafil

    Directory of Open Access Journals (Sweden)

    Mehdizadeh Morteza

    2008-01-01

    Full Text Available Herein, we describe the presenting symptoms, history, ophthalmic examination, visual fields and brain magnetic resonance imaging of a patient who developed left homonymous hemianopia due to right occipital lobe hemorrhage after ingestion of sildenafil citrate (Novagra Forte. To the best of our knowledge, association of homonymous hemianopia with sildenafil usage has not been reported before.

  2. Perimetry in young and neurologically impaired children: the Behavioral Visual Field (BEFIE) Screening Test revisited.

    Science.gov (United States)

    Koenraads, Yvonne; Braun, Kees P J; van der Linden, Denise C P; Imhof, Saskia M; Porro, Giorgio L

    2015-03-01

    Visual field examination in young or neurologically impaired children is a challenge. As a result, the Behavioral Visual Field (BEFIE) Screening Test was developed in 1995. To evaluate the applicability of the BEFIE test in a large population of young or neurologically impaired children, its reliability and consistency of findings across time, and its potential diagnostic value compared with standard conventional perimetry. The BEFIE tests were performed at an academic tertiary center and measured the peripheral visual field extension in degrees by observing an individual's response to a stimulus on a graded arc that moved from the periphery to the center of the visual field along different meridians. Patient files from all children who underwent this test were retrospectively analyzed. In total, 1788 BEFIE tests were performed in 835 children (median age, 3.4 years). Reliability and results of all tests were longitudinally evaluated. The diagnostic value of the BEFIE test was assessed by comparing monocular BEFIE test results with those of standard conventional perimetry in children who underwent both. Of 1788 tests, 74% (95% CI, 72%-76%) were considered reliable from the age of 4 months and older, with increasing success with higher ages; 56% reliable in children younger than 1 year; 71% reliable in children between 1 and 2 years; and more than 75% reliable in children 2 years and older (Spearman r = 0.506; P = .11). Peripheral visual field defects were found in 28% (95% CI, 25%-31%) of all first reliable tests. In 75% of children who underwent serial testing, results were consistent and there were good explanations in the case of discrepancies. Comparison of monocular BEFIE tests with standard conventional perimetry results in 147 eyes yielded a positive predictive value of 98% (95% CI, 94%-100%), negative predictive value of 66% (95% CI, 56%-75%), specificity of 98% (95% CI, 95%-100%), sensitivity of 60% (95% CI, 50%-71%), and superior sensitivity of 80

  3. Cognitive and psychological science insights to improve climate change data visualization

    Science.gov (United States)

    Harold, Jordan; Lorenzoni, Irene; Shipley, Thomas F.; Coventry, Kenny R.

    2016-12-01

    Visualization of climate data plays an integral role in the communication of climate change findings to both expert and non-expert audiences. The cognitive and psychological sciences can provide valuable insights into how to improve visualization of climate data based on knowledge of how the human brain processes visual and linguistic information. We review four key research areas to demonstrate their potential to make data more accessible to diverse audiences: directing visual attention, visual complexity, making inferences from visuals, and the mapping between visuals and language. We present evidence-informed guidelines to help climate scientists increase the accessibility of graphics to non-experts, and illustrate how the guidelines can work in practice in the context of Intergovernmental Panel on Climate Change graphics.

  4. Visual, keratometric and corneal biomechanical changes after intacs SK implantation for moderate to severe keratoconus

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Zare

    2016-01-01

    Conclusion: Visual, refractive and keratometric indices remarkably improved in a parallel fashion. CRF was inversely associated with CCT. Changes in CRF represent the trend of changes in corneal biomechanics and thickness during the early postoperative months.

  5. Evaluation of Visual Field and Imaging Outcomes for Glaucoma Clinical Trials (An American Ophthalomological Society Thesis).

    Science.gov (United States)

    Garway-Heath, David F; Quartilho, Ana; Prah, Philip; Crabb, David P; Cheng, Qian; Zhu, Haogang

    2017-08-01

    To evaluate the ability of various visual field (VF) analysis methods to discriminate treatment groups in glaucoma clinical trials and establish the value of time-domain optical coherence tomography (TD OCT) imaging as an additional outcome. VFs and retinal nerve fibre layer thickness (RNFLT) measurements (acquired by TD OCT) from 373 glaucoma patients in the UK Glaucoma Treatment Study (UKGTS) at up to 11 scheduled visits over a 2 year interval formed the cohort to assess the sensitivity of progression analysis methods. Specificity was assessed in 78 glaucoma patients with up to 11 repeated VF and OCT RNFLT measurements over a 3 month interval. Growth curve models assessed the difference in VF and RNFLT rate of change between treatment groups. Incident progression was identified by 3 VF-based methods: Guided Progression Analysis (GPA), 'ANSWERS' and 'PoPLR', and one based on VFs and RNFLT: 'sANSWERS'. Sensitivity, specificity and discrimination between treatment groups were evaluated. The rate of VF change was significantly faster in the placebo, compared to active treatment, group (-0.29 vs +0.03 dB/year, P <.001); the rate of RNFLT change was not different (-1.7 vs -1.1 dB/year, P =.14). After 18 months and at 95% specificity, the sensitivity of ANSWERS and PoPLR was similar (35%); sANSWERS achieved a sensitivity of 70%. GPA, ANSWERS and PoPLR discriminated treatment groups with similar statistical significance; sANSWERS did not discriminate treatment groups. Although the VF progression-detection method including VF and RNFLT measurements is more sensitive, it does not improve discrimination between treatment arms.

  6. Current status of visual field examination in Andalusia, Spain: the SICVA Study.

    Science.gov (United States)

    Benítez-del-Castillo, Javier; Regi, Teresa

    2014-01-01

    To ascertain the frequency of visual field examination (VFE) in patients attending public Andalusian hospitals (the SICVA study). This was a multicenter, observational, retrospective study of patients with documented and/or suspected glaucoma subject to campimetric monitoring for longer than 2 years. The numbers of VFEs performed in the first 2 years and in the complete follow-up period were analyzed. Data on VFE reliability were studied and VFE change was collected based on the Glaucoma Staging System 2. A total of 722 eyes (from 467 consecutive patients), 349 with suspected and 373 with documented glaucoma, were included. Mean patient age was 65.9 years (SD = 11.3), and median follow-up time was 56 months (P25 = 36, P75 = 84). Three (P25 = 2, P75 = 4) VFEs were performed in the first 2 years of follow-up in the overall sample, as compared to 2 VFEs (P25 = 2, P75 = 4) in patients with suspected glaucoma, and 3 VFEs (P25 = 2, P75 = 4) in those with documented glaucoma (pAndalusia differs from the standards recommended by the European Glaucoma Society to assess progression in the first 2 years of patient follow-up.

  7. Retinotopic mapping of the human visual cortex at a magnetic field strength of 7T.

    Science.gov (United States)

    Hoffmann, Michael B; Stadler, Jörg; Kanowski, Martin; Speck, Oliver

    2009-01-01

    fMRI-based retinotopic mapping data obtained at a magnetic field strength of 7T are evaluated and compared to 3T acquisitions. With established techniques retinotopic mapping data were obtained in four subjects for 25 slices parallel to the calcarine sulcus at 7 and 3T for three voxel sizes (2.5(3), 1.4(3), and 1.1(3)mm(3)) and in two subjects for 49 slices at 7T for 2.5(3)mm(3) voxels. The data were projected to the flattened representation of T1 weighted images acquired at 3T. The obtained retinotopic maps allowed for the identification of visual areas in the occipito-parietal cortex. The mean coherence increased with magnetic field strength and with voxel size. At 7T, the occipital cortex could be sampled with high sensitivity in a short single session at high resolution. Alternatively, at lower resolution simultaneous mapping of a great expanse of occipito-parietal cortex was possible. Retinotopic mapping at 7T aids a detailed description of the visual areas. Here, recent findings of multiple stimulus-driven retinotopic maps along the intraparietal sulcus are supported. Retinotopic mapping at 7T opens the possibility to detail our understanding of the cortical visual field representations in general and of their plasticity in visual system pathologies.

  8. Neurons in Primate Visual Cortex Alternate between Responses to Multiple Stimuli in Their Receptive Field

    Science.gov (United States)

    Li, Kang; Kozyrev, Vladislav; Kyllingsbæk, Søren; Treue, Stefan; Ditlevsen, Susanne; Bundesen, Claus

    2016-01-01

    A fundamental question concerning representation of the visual world in our brain is how a cortical cell responds when presented with more than a single stimulus. We find supportive evidence that most cells presented with a pair of stimuli respond predominantly to one stimulus at a time, rather than a weighted average response. Traditionally, the firing rate is assumed to be a weighted average of the firing rates to the individual stimuli (response-averaging model) (Bundesen et al., 2005). Here, we also evaluate a probability-mixing model (Bundesen et al., 2005), where neurons temporally multiplex the responses to the individual stimuli. This provides a mechanism by which the representational identity of multiple stimuli in complex visual scenes can be maintained despite the large receptive fields in higher extrastriate visual cortex in primates. We compare the two models through analysis of data from single cells in the middle temporal visual area (MT) of rhesus monkeys when presented with two separate stimuli inside their receptive field with attention directed to one of the two stimuli or outside the receptive field. The spike trains were modeled by stochastic point processes, including memory effects of past spikes and attentional effects, and statistical model selection between the two models was performed by information theoretic measures as well as the predictive accuracy of the models. As an auxiliary measure, we also tested for uni- or multimodality in interspike interval distributions, and performed a correlation analysis of simultaneously recorded pairs of neurons, to evaluate population behavior. PMID:28082892

  9. CORRELATION BETWEEN STRUCTURAL RETINAL NERVE FIBRE LAYER THICKNESS AND FUNCTIONAL VISUAL FIELD LOSS IN PRIMARY OPEN ANGLE GLAUCOMA

    Directory of Open Access Journals (Sweden)

    A. Arun

    2015-04-01

    Full Text Available Background: Glaucoma is characterized by progressive degeneration of retinal ganglion cells and their axons that leads to nerve fiber layer loss, optic disc cupping, and consecutive glaucomatous visual field changes. Study is done in Department of ophthalmology, S.V.R.R Government General Hospital, S.V.Medical College Tirupati. A total of 52 eyes of 29 patients were included in the study. Mean age of the patients included in the study is 64.14+/- 11.43 years. Majority were male patients (68.96%. Female patients were only 31.04%.

  10. [Regularities of structural and functional visual system changes in patients with myopic refraction and presbyopia].

    Science.gov (United States)

    Rozanova, O I; Seliverstova, N N; Shchuko, A G; Malyshev, V V

    2013-01-01

    Two age groups of 57 patients with noncomplicated low or moderate myopia were examined to reveal the regularities of structural and functional visual system changes in patients with myopic refraction and presbyopia. Characteristics of visual impression, anatomic and physiologic parameters were studied. Presbyopia development in patients with myopic refraction was found to occur on the background of significant changes in anatomic proportions and optic parameters of the eye, decrease of functional capability of visual system and development of abnormal functional system of visual perception. The key mechanisms of presbyopia development in myopia besides the accommodation decrease are pupil dysfunction and binocular interactions disintegration i. e. all the near vision reflex components.

  11. Impact of visual cues on directional benefit and preference: Part II--field tests.

    Science.gov (United States)

    Wu, Yu-Hsiang; Bentler, Ruth A

    2010-02-01

    The field tests performed in the current investigation examined how visual cues impact the benefit provided by directional (DIR) microphone hearing aids in the real world. Specifically, the study tested the hypotheses that (1) the provision of visual cues would reduce the preference for DIR processing (re: omnidirectional [OMNI] microphone) and (2) laboratory audiovisual (AV) testing would predict real-world outcomes better than auditory-only testing. The same 24 hearing-impaired adults enrolled in the laboratory testing of this study compared microphone modes (DIR versus OMNI processing) in their everyday activities three times a day for 4 wk using paper and pencil journals. In each comparison, the participants were asked to identify an environment that favored DIR processing (e.g., the talker standing in front of the user and noise at his or her back), listen to speech amid noise via both the DIR and OMNI microphone modes, and then record the preferred microphone mode in the journal. To further understand what the listeners based their preference on, the participants were also asked to provide the reasons for their preferences. Microphone modes were compared when the listeners' eyes were either open or closed. The field results first suggested that OMNI processing was more frequently preferred over DIR processing. Visual cues were not found to have a significant effect on preference for DIR processing. Furthermore, the analysis revealed that when listeners indicated "louder" or "less internal noise" as the reasons for their microphone preference, the likelihood of preferring the OMNI mode increased significantly, suggesting that OMNI processing was preferred for its louder output and lower internal circuit noise level. Finally, the preference score obtained by the laboratory preference judgment task under the AV condition was shown to be the best predictor of microphone preference in the real world. The field data did not reveal the effect of visual cues on

  12. Evaluation of hemifield sector analysis protocol in multifocal visual evoked potential objective perimetry for the diagnosis and early detection of glaucomatous field defects.

    Science.gov (United States)

    Mousa, Mohammad F; Cubbidge, Robert P; Al-Mansouri, Fatima; Bener, Abdulbari

    2014-02-01

    Multifocal visual evoked potential (mfVEP) is a newly introduced method used for objective visual field assessment. Several analysis protocols have been tested to identify early visual field losses in glaucoma patients using the mfVEP technique, some were successful in detection of field defects, which were comparable to the standard automated perimetry (SAP) visual field assessment, and others were not very informative and needed more adjustment and research work. In this study we implemented a novel analysis approach and evaluated its validity and whether it could be used effectively for early detection of visual field defects in glaucoma. Three groups were tested in this study; normal controls (38 eyes), glaucoma patients (36 eyes) and glaucoma suspect patients (38 eyes). All subjects had a two standard Humphrey field analyzer (HFA) test 24-2 and a single mfVEP test undertaken in one session. Analysis of the mfVEP results was done using the new analysis protocol; the hemifield sector analysis (HSA) protocol. Analysis of the HFA was done using the standard grading system. Analysis of mfVEP results showed that there was a statistically significant difference between the three groups in the mean signal to noise ratio (ANOVA test, p field defects in both glaucoma and glaucoma suspect patients. Using this protocol can provide information about focal visual field differences across the horizontal midline, which can be utilized to differentiate between glaucoma and normal subjects. Sensitivity and specificity of the mfVEP test showed very promising results and correlated with other anatomical changes in glaucoma field loss.

  13. Changes in brain morphology in albinism reflect reduced visual acuity.

    Science.gov (United States)

    Bridge, Holly; von dem Hagen, Elisabeth A H; Davies, George; Chambers, Claire; Gouws, Andre; Hoffmann, Michael; Morland, Antony B

    2014-07-01

    Albinism, in humans and many animal species, has a major impact on the visual system, leading to reduced acuity, lack of binocular function and nystagmus. In addition to the lack of a foveal pit, there is a disruption to the routing of the nerve fibers crossing at the optic chiasm, resulting in excessive crossing of fibers to the contralateral hemisphere. However, very little is known about the effect of this misrouting on the structure of the post-chiasmatic visual pathway, and the occipital lobes in particular. Whole-brain analyses of cortical thickness in a large cohort of subjects with albinism showed an increase in cortical thickness, relative to control subjects, particularly in posterior V1, corresponding to the foveal representation. Furthermore, mean cortical thickness across entire V1 was significantly greater in these subjects compared to controls and negatively correlated with visual acuity in albinism. Additionally, the group with albinism showed decreased gyrification in the left ventral occipital lobe. While the increase in cortical thickness in V1, also found in congenitally blind subjects, has been interpreted to reflect a lack of pruning, the decreased gyrification in the ventral extrastriate cortex may reflect the reduced input to the foveal regions of the ventral visual stream. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Getting the picture and changing the picture: visual methodologies ...

    African Journals Online (AJOL)

    what I set out to do is lay bare some of the key elements of working with the visual as a set of methodologies and practices. In particular, I address educational research in South Africa at a time when questions of the social responsibility of the academic researcher (including postgraduate students as new researchers, ...

  15. How Information Visualization Systems Change Users' Understandings of Complex Data

    Science.gov (United States)

    Allendoerfer, Kenneth Robert

    2009-01-01

    User-centered evaluations of information systems often focus on the usability of the system rather its usefulness. This study examined how a using an interactive knowledge-domain visualization (KDV) system affected users' understanding of a domain. Interactive KDVs allow users to create graphical representations of domains that depict important…

  16. Auditory-Visual Perception of Changing Distance by Human Infants.

    Science.gov (United States)

    Walker-Andrews, Arlene S.; Lennon, Elizabeth M.

    1985-01-01

    Examines, in two experiments, 5-month-old infants' sensitivity to auditory-visual specification of distance and direction of movement. One experiment presented two films with soundtracks in either a match or mismatch condition; the second showed the two films side-by-side with a single soundtrack appropriate to one. Infants demonstrated visual…

  17. Testing a Conceptual Change Model Framework for Visual Data

    Science.gov (United States)

    Finson, Kevin D.; Pedersen, Jon E.

    2015-01-01

    An emergent data analysis technique was employed to test the veracity of a conceptual framework constructed around visual data use and instruction in science classrooms. The framework incorporated all five key components Vosniadou (2007a, 2007b) described as existing in a learner's schema: framework theory, presuppositions, conceptual domains,…

  18. Can Visual Field Progression be Predicted by Confocal Scanning Laser Ophthalmoscopic Imaging of the Optic Nerve Head in Glaucoma? (An American Ophthalmological Society Thesis).

    Science.gov (United States)

    Danias, John; Serle, Janet

    2015-01-01

    To determine whether confocal scanning laser ophthalmoscopic imaging (Heidelberg retinal tomography [HRT]) can predict visual field change in glaucoma. The study included 561 patients with glaucoma or ocular hypertension whose clinical course was followed at the Mount Sinai Faculty practice. Humphrey visual fields (HVFs) and HRT images were collected on one randomly selected eye per patient. Glaucoma progression was determined by the presence of two sequential statistically significant negative slopes in mean deviation (MD) or visual field index (VFI) at any point during the study period. Trend-based analysis on HRT parameters was used to determine progressive changes and whether these occurred before or after HVF change. Sensitivity and specificity of HRT to predict HVF change were calculated. HVF rate of change was correlated to the rate of change detected by HRT imaging. Approximately 17% of patients progressed by either MD or VFI criteria. MD and VFI correlated highly and identified overlapping sets of patients as progressing. HRT global parameters had poor sensitivity (∼42%) and moderate specificity (∼67%) to predict HVF progression. Regional stereometric parameters were more sensitive (69%-78%) but significantly less specific (24%-27%). Sensitivity of global stereometric parameters in detecting HVF change was not significantly affected by the level of visual field damage (P=.3, Fisher exact test). HVF rate of change did not correlate with rate of change of HRT parameters. Trend-based analysis of HRT parameters has poor sensitivity and specificity in predicting HVF change. This may be related specifically to HRT imaging or may reflect the fact that in some patients with glaucoma, functional changes precede structural alterations.

  19. Re-Examining Format Distortion and Orthographic Neighbourhood Size Effects in the Left, Central and Right Visual Fields

    Science.gov (United States)

    Mano, Quintino R.; Patrick, Cory J.; Andresen, Elizabeth N.; Capizzi, Kyle; Biagioli, Raschel; Osmon, David C.

    2010-01-01

    Research has shown orthographic neighbourhood size effects (ONS) in the left visual field (LVF) but not in the right visual field (RVF). An earlier study examined the combined effects of ONS and font distortion in the LVF and RVF, but did not find an interaction. The current lexical decision experiment re-examined the interaction between ONS and…

  20. Limits on perceptual encoding can be predicted from known receptive field properties of human visual cortex.

    Science.gov (United States)

    Cohen, Michael A; Rhee, Juliana Y; Alvarez, George A

    2016-01-01

    Human cognition has a limited capacity that is often attributed to the brain having finite cognitive resources, but the nature of these resources is usually not specified. Here, we show evidence that perceptual interference between items can be predicted by known receptive field properties of the visual cortex, suggesting that competition within representational maps is an important source of the capacity limitations of visual processing. Across the visual hierarchy, receptive fields get larger and represent more complex, high-level features. Thus, when presented simultaneously, high-level items (e.g., faces) will often land within the same receptive fields, while low-level items (e.g., color patches) will often not. Using a perceptual task, we found long-range interference between high-level items, but only short-range interference for low-level items, with both types of interference being weaker across hemifields. Finally, we show that long-range interference between items appears to occur primarily during perceptual encoding and not during working memory maintenance. These results are naturally explained by the distribution of receptive fields and establish a link between perceptual capacity limits and the underlying neural architecture. (c) 2015 APA, all rights reserved).

  1. Axial Myopia Is Associated with Visual Field Prognosis of Primary Open-Angle Glaucoma

    Science.gov (United States)

    Qiu, Chen; Qian, Shaohong; Sun, Xinghuai; Zhou, Chuandi; Meng, Fanrong

    2015-01-01

    Purpose To identify whether myopia was associated with the visual field (VF) progression of primary open-angle glaucoma (POAG). Methods A total of 270 eyes of 270 POAG followed up for more than 3 years with ≥9 reliable VFs by Octopus perimetry were retrospectively reviewed. Myopia was divided into: mild myopia (-2.99 diopter [D], 0), moderate myopia (-5.99, 3.00 D), marked myopia (-9.00, -6.00 D) and non-myopia (0 D or more). An annual change in the mean defect (MD) slope >0.22 dB/y and 0.30 dB/y was defined as fast progression, respectively. Logistic regression was performed to determine prognostic factors for VF progression. Results For the cutoff threshold at 0.22 dB/y, logistic regression showed that vertical cup-to-disk ratio (VCDR; p = 0.004) and the extent of myopia (p = 0.002) were statistically significant. When logistic regression was repeated after excluding the extent of myopia, axial length (AL; p = 0.008, odds ratio [OR] = 0.796) reached significance, as did VCDR (p = 0.001). Compared to eyes with AL≤23 mm, the OR values were 0.334 (p = 0.059), 0.309 (p = 0.044), 0.266 (p = 0.019), 0.260 (p = 0.018), respectively, for 23 26 mm. The significance of vertical cup-to-disk ratio of (p = 0.004) and the extent of myopia (p = 0.008) did not change for the cutoff threshold at 0.30dB/y. Conclusions VCDR and myopia were associated with VF prognosis of POAG. Axial myopia may be a protective factor against VF progression. PMID:26214313

  2. Tolerable rates of visual field progression in a population-based sample of patients with glaucoma.

    Science.gov (United States)

    Salonikiou, Angeliki; Founti, Panayiota; Kilintzis, Vassilis; Antoniadis, Antonis; Anastasopoulos, Eleftherios; Pappas, Theofanis; Raptou, Anastasia; Topouzis, Fotis

    2017-09-28

    To provide population-based data on the maximum tolerable rate of progression to avoid visual impairment (maxTRoP_VI) and blindness (maxTRoP_BL) from open-angle glaucoma (OAG). Participants with OAG in the Thessaloniki Eye Study (cross-sectional, population-based study in a European population) were included in the analysis. Visual impairment was defined as mean deviation (MD) equal to or worse than -12 dB and blindness as MD equal to or worse than -24 dB. Additional thresholds for visual impairment were tested. For each participant maxTRoP_VI was defined as the rate of progression which would not lead to visual impairment during expected lifetime. MaxTRoP_BL was defined accordingly. Both parameters were calculated for each OAG subject using age, sex, MD and life expectancy data. The eye with the better MD per subject was included in the analysis. Among 135 subjects with OAG, 123 had reliable visual fields and were included in the analysis. The mean age was 73±6 years and the median MD was -3.65±5.28 dB. Among those, 69.1% would have a maxTRoP_VI slower than -1 dB/year and 18.7% would have a maxTRoP_VI between -1 and -2 dB/year. Also, 72.4% would have a maxTRoP_BL slower than -2 dB/year. For all tested thresholds for visual impairment, approximately 86% of the OAG study participants would not be able to tolerate a rate of progression equal to or faster than -2 dB/year. The majority of patients with glaucoma in our study would have a maximum tolerable rate of progression slower than -1 dB/year in their better eye. Patient-tailored strategies to monitor the visual field are important, but raise the issue of feasibility with regard to the number of visual field tests needed. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  3. Changing Struggles for Relevance in Eight Fields of Natural Science

    Science.gov (United States)

    Hessels, Laurens K.; van Lente, Harro; Grin, John; Smits, Ruud E. H. M.

    2011-01-01

    This paper investigates the consequences of institutional changes on academic research practices in eight fields of natural science in the Netherlands. The authors analyse the similarities and differences among the dynamics of these different fields and reflect on possible explanations for the changes observed. The study shows that the increasing…

  4. The global structure of the visual light field and its relation to the physical light field

    NARCIS (Netherlands)

    Kartashova, T.; Sekulovski, D; de Ridder, H.; te Pas, SF; Pont, S.C.

    2016-01-01

    Human observers have been demonstrated to be sensitive to the local (physical) light field, or more
    precisely, to the primary direction, intensity, and diffuseness of the light at a point in a space. In the
    present study we focused on the question of whether it is possible to reconstruct the

  5. The global structure of the visual light field and its relation to the physical light field

    NARCIS (Netherlands)

    Kartashova, Tatiana; Sekulovski, Dragan; de Ridder, Huib; te Pas, S.F.|info:eu-repo/dai/nl/111010853; Pont, S.C.

    2016-01-01

    Human observers have been demonstrated to be sensitive to the local (physical) light field, or more precisely, to the primary direction, intensity, and diffuseness of the light at a point in a space. In the present study we focused on the question of whether it is possible to reconstruct the global

  6. The feasibility of an infrared system for real-time visualization and mapping of ultrasound fields

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, Adam; Nunn, John, E-mail: adam.shaw@npl.co.u [National Physical Laboratory, Teddington, Middlesex, TW11 0LW (United Kingdom)

    2010-06-07

    In treatment planning for ultrasound therapy, it is desirable to know the 3D structure of the ultrasound field. However, mapping an ultrasound field in 3D is very slow, with even a single planar raster scan taking typically several hours. Additionally, hydrophones that are used for field mapping are expensive and can be damaged in some therapy fields. So there is value in rapid methods which enable visualization and mapping of the ultrasound field in about 1 min. In this note we explore the feasibility of mapping the intensity distribution by measuring the temperature distribution produced in a thin sheet of absorbing material. A 0.2 mm thick acetate sheet forms a window in the wall of a water tank containing the transducer. The window is oriented at 45{sup 0} to the beam axis, and the distance from the transducer to the window can be varied. The temperature distribution is measured with an infrared camera; thermal images of the inclined plane could be viewed in real time or images could be captured for later analysis and 3D field reconstruction. We conclude that infrared thermography can be used to gain qualitative information about ultrasound fields. Thermal images are easily visualized with good spatial and thermal resolutions (0.044 mm and 0.05 {sup 0}C in our system). The focus and field structure such as side lobes can be identified in real time from the direct video output. 3D maps and image planes at arbitrary orientations to the beam axis can be obtained and reconstructed within a few minutes. In this note we are primarily interested in the technique for characterization of high intensity focused ultrasound (HIFU) fields, but other applications such as physiotherapy fields are also possible. (note)

  7. A study on the natural history of scanning behaviour in patients with visual field defects after stroke.

    Science.gov (United States)

    Loetscher, Tobias; Chen, Celia; Wignall, Sophie; Bulling, Andreas; Hoppe, Sabrina; Churches, Owen; Thomas, Nicole A; Nicholls, Michael E R; Lee, Andrew

    2015-04-24

    A visual field defect (VFD) is a common consequence of stroke with a detrimental effect upon the survivors' functional ability and quality of life. The identification of effective treatments for VFD is a key priority relating to life post-stroke. Understanding the natural evolution of scanning compensation over time may have important ramifications for the development of efficacious therapies. The study aims to unravel the natural history of visual scanning behaviour in patients with VFD. The assessment of scanning patterns in the acute to chronic stages of stroke will reveal who does and does not learn to compensate for vision loss. Eye-tracking glasses are used to delineate eye movements in a cohort of 100 stroke patients immediately after stroke, and additionally at 6 and 12 months post-stroke. The longitudinal study will assess eye movements in static (sitting) and dynamic (walking) conditions. The primary outcome constitutes the change of lateral eye movements from the acute to chronic stages of stroke. Secondary outcomes include changes of lateral eye movements over time as a function of subgroup characteristics, such as side of VFD, stroke location, stroke severity and cognitive functioning. The longitudinal comparison of patients who do and do not learn compensatory scanning techniques may reveal important prognostic markers of natural recovery. Importantly, it may also help to determine the most effective treatment window for visual rehabilitation.

  8. Bright-field Nanoscopy: Visualizing Nano-structures with Localized Optical Contrast Using a Conventional Microscope.

    Science.gov (United States)

    Suran, Swathi; Bharadwaj, Krishna; Raghavan, Srinivasan; Varma, Manoj M

    2016-04-26

    Most methods for optical visualization beyond the diffraction limit rely on fluorescence emission by molecular tags. Here, we report a method for visualization of nanostructures down to a few nanometers using a conventional bright-field microscope without requiring additional molecular tags such as fluorophores. The technique, Bright-field Nanoscopy, is based on the strong thickness dependent color of ultra-thin germanium on an optically thick gold film. We demonstrate the visualization of grain boundaries in chemical vapour deposited single layer graphene and the detection of single 40 nm Ag nanoparticles. We estimate a size detection limit of about 2 nm using this technique. In addition to visualizing nano-structures, this technique can be used to probe fluid phenomena at the nanoscale, such as transport through 2D membranes. We estimated the water transport rate through a 1 nm thick polymer film using this technique, as an illustration. Further, the technique can also be extended to study the transport of specific ions in the solution. It is anticipated that this technique will find use in applications ranging from single-nanoparticles resolved sensing to studying nanoscale fluid-solid interface phenomena.

  9. Probability and Visual Aids for Assessing Intervention Effectiveness in Single-Case Designs: A Field Test.

    Science.gov (United States)

    Manolov, Rumen; Jamieson, Matthew; Evans, Jonathan J; Sierra, Vicenta

    2015-09-01

    Single-case data analysis still relies heavily on visual inspection, and, at the same time, it is not clear to what extent the results of different quantitative procedures converge in identifying an intervention effect and its magnitude when applied to the same data; this is the type of evidence provided here for two procedures. One of the procedures, included due to the importance of providing objective criteria to visual analysts, is a visual aid fitting and projecting split-middle trend while taking into account data variability. The other procedure converts several different metrics into probabilities making their results comparable. In the present study, we expore to what extend these two procedures coincide in the magnitude of intervention effect taking place in a set of studies stemming from a recent meta-analysis. The procedures concur to a greater extent with the values of the indices computed and with each other and, to a lesser extent, with our own visual analysis. For distinguishing smaller from larger effects, the probability-based approach seems somewhat better suited. Moreover, the results of the field test suggest that the latter is a reasonably good mechanism for translating different metrics into similar labels. User friendly R code is provided for promoting the use of the visual aid, together with a quantification based on nonoverlap and the label provided by the probability approach. © The Author(s) 2015.

  10. Audio-visual object search is changed by bilingual experience.

    Science.gov (United States)

    Chabal, Sarah; Schroeder, Scott R; Marian, Viorica

    2015-11-01

    The current study examined the impact of language experience on the ability to efficiently search for objects in the face of distractions. Monolingual and bilingual participants completed an ecologically-valid, object-finding task that contained conflicting, consistent, or neutral auditory cues. Bilinguals were faster than monolinguals at locating the target item, and eye movements revealed that this speed advantage was driven by bilinguals' ability to overcome interference from visual distractors and focus their attention on the relevant object. Bilinguals fixated the target object more often than did their monolingual peers, who, in contrast, attended more to a distracting image. Moreover, bilinguals', but not monolinguals', object-finding ability was positively associated with their executive control ability. We conclude that bilinguals' executive control advantages extend to real-world visual processing and object finding within a multi-modal environment.

  11. Association between rates of binocular visual field loss and vision-related quality of life in patients with glaucoma.

    Science.gov (United States)

    Lisboa, Renato; Chun, Yeoun Sook; Zangwill, Linda M; Weinreb, Robert N; Rosen, Peter N; Liebmann, Jeffrey M; Girkin, Christopher A; Medeiros, Felipe A

    2013-04-01

    It is reasonable to hypothesize that for 2 patients with similar degrees of integrated binocular visual field (BVF) loss, the patient with a history of faster disease progression will report worse vision-related quality of life (VRQOL) than the patient with slowly progressing damage. However, to our knowledge, this hypothesis has not been investigated in the literature. To evaluate the association between binocular rates of visual field change and VRQOL in patients with glaucoma. DESIGN Observational cohort study. Patients were recruited from the Diagnostic Innovations in Glaucoma Study and the African Descent and Glaucoma Evaluation Study. The study included 796 eyes of 398 patients with diagnosed or suspected glaucoma followed up from October 1, 1998, until January 31, 2012, for a mean (SD) of 7.3 (2.0) years. The VRQOL was evaluated using the 25-item National Eye Institute Visual Function Questionnaire (NEI VFQ-25) at the last follow-up visit. The NEI VFQ-25 was completed for all patients during the period extending from December 1, 2009, through January 31, 2012. Integrated BVFs were calculated from the monocular fields of each patient. Linear regression of mean deviation values was used to evaluate rates of BVF change during the follow-up period. Logistic regression models were used to investigate the association between abnormal VRQOL and rates of BVF change, while adjusting for potentially confounding socioeconomic and demographic variables. Thirty-two patients (8.0%) had abnormal VRQOL as determined by the results of the NEI VFQ-25. Patients with abnormal VRQOL had significantly faster rates of BVF change than those with normal VRQOL (-0.18 vs -0.06 dB/y; P < .001). Rates of BVF change were significantly associated with abnormality in VRQOL (odds ratio = 1.31 per 0.1 dB/y faster; P = .04), after adjustment for confounding variables. Patients with faster rates of BVF change were at higher risk of reporting abnormal VRQOL. Assessment of rates of BVF change

  12. The left visual-field advantage in rapid visual presentation is amplified rather than reduced by posterior-parietal rTMS

    DEFF Research Database (Denmark)

    Verleger, Rolf; Möller, Friderike; Kuniecki, Michal

    2010-01-01

    In the present task, series of visual stimuli are rapidly presented left and right, containing two target stimuli, T1 and T2. In previous studies, T2 was better identified in the left than in the right visual field. This advantage of the left visual field might reflect dominance exerted...... by the right over the left hemisphere. If so, then repetitive transcranial magnetic stimulation (rTMS) to the right parietal cortex might release the left hemisphere from right-hemispheric control, thereby improving T2 identification in the right visual field. Alternatively or additionally, the asymmetry in T2...... identification might reflect capacity limitations of the left hemisphere, which might be aggravated by rTMS to the left parietal cortex. Therefore, rTMS pulses were applied during each trial, beginning simultaneously with T1 presentation. rTMS was directed either to P4 or to P3 (right or left parietal cortex...

  13. Efficient Multi-Concept Visual Classifier Adaptation in Changing Environments

    Science.gov (United States)

    2016-09-01

    ketplaces such as Amazon Mechanical Turk has become a popular way to collect large sets of annotated visual data.13,39 This technique allows the label...release; distribution is unlimited. inside, kitchen outside, mountain (a) Scene images and labels animal, dog , dachshund vehicle, bike, mountain-bike (b...the object labeling example, dog ∈ Y . The goal of partitional grouping techniques is to find a partition ofK groups such that each group maps to a

  14. Propulsion Physics Under the Changing Density Field Model

    Science.gov (United States)

    Robertson, Glen A.

    2011-01-01

    To grow as a space faring race, future spaceflight systems will requires new propulsion physics. Specifically a propulsion physics model that does not require mass ejection without limiting the high thrust necessary to accelerate within or beyond our solar system and return within a normal work period or lifetime. In 2004 Khoury and Weltman produced a density dependent cosmology theory they called Chameleon Cosmology, as at its nature, it is hidden within known physics. This theory represents a scalar field within and about an object, even in the vacuum. Whereby, these scalar fields can be viewed as vacuum energy fields with definable densities that permeate all matter; having implications to dark matter/energy with universe acceleration properties; implying a new force mechanism for propulsion physics. Using Chameleon Cosmology, the author has developed a new propulsion physics model, called the Changing Density Field (CDF) Model. This model relates to density changes in these density fields, where the density field density changes are related to the acceleration of matter within an object. These density changes in turn change how an object couples to the surrounding density fields. Whereby, thrust is achieved by causing a differential in the coupling to these density fields about an object. Since the model indicates that the density of the density field in an object can be changed by internal mass acceleration, even without exhausting mass, the CDF model implies a new propellant-less propulsion physics model

  15. Whole-field visual motion drives swimming in larval zebrafish via a stochastic process.

    Science.gov (United States)

    Portugues, Ruben; Haesemeyer, Martin; Blum, Mirella L; Engert, Florian

    2015-05-01

    Caudo-rostral whole-field visual motion elicits forward locomotion in many organisms, including larval zebrafish. Here, we investigate the dependence on the latency to initiate this forward swimming as a function of the speed of the visual motion. We show that latency is highly dependent on speed for slow speeds (1.5 s, which is much longer than neuronal transduction processes. What mechanisms underlie these long latencies? We propose two alternative, biologically inspired models that could account for this latency to initiate swimming: an integrate and fire model, which is history dependent, and a stochastic Poisson model, which has no history dependence. We use these models to predict the behavior of larvae when presented with whole-field motion of varying speed and find that the stochastic process shows better agreement with the experimental data. Finally, we discuss possible neuronal implementations of these models. © 2015. Published by The Company of Biologists Ltd.

  16. Receptive field properties of neurons in the primary visual cortex under photopic and scotopic lighting conditions

    OpenAIRE

    Duffy, Kevin R.; Hubel, David H.

    2007-01-01

    Knowledge of the physiology of the primate visual cortex (area V-1) comes mostly from studies done in photopic conditions, in which retinal cones are active and rods play little or no part. Conflicting results have come from research into the effects of dark adaptation on receptive field organization of cells in the retina and the lateral geniculate nucleus. These studies claim either that the effect of the surround disappears with dark adaptation or that it does not. The current study has as...

  17. Field: a new meta-authoring platform for data-intensive scientific visualization

    Science.gov (United States)

    Downie, M.; Ameres, E.; Fox, P. A.; Goebel, J.; Graves, A.; Hendler, J.

    2012-12-01

    This presentation will demonstrate a new platform for data-intensive scientific visualization, called Field, that rethinks the problem of visual data exploration. Several new opportunities for scientific visualization present themselves here at this moment in time. We believe that when taken together they may catalyze a transformation of the practice of science and to begin to seed a technical culture within science that fuses data analysis, programming and myriad visual strategies. It is at integrative levels that the principle challenges exist, for many fundamental technical components of our field are now well understood and widely available. File formats from CSV through HDF all have broad library support; low-level high-performance graphics APIs (OpenGL) are in a period of stable growth; and a dizzying ecosystem of analysis and machine learning libraries abound. The hardware of computer graphics offers unprecedented computing power within commodity components; programming languages and platforms are coalescing around a core set of umbrella runtimes. Each of these trends are each set to continue — computer graphics hardware is developing at a super-Moore-law rate, and trends in publication and dissemination point only towards an increasing amount of access to code and data. The critical opportunity here for scientific visualization is, we maintain, not a in developing a new statistical library, nor a new tool centered on a particular technique, but rather new visual, "live" programming environment that is promiscuous in its scope. We can identify the necessarily methodological practice and traditions required here not in science or engineering but in the "live-coding" practices prevalent in the fields of digital art and design. We can define this practice as an approach to programming that is live, iterative, integrative, speculative and exploratory. "Live" because it is exclusively practiced in real-time (often during performance); "iterative", because

  18. The research and application of visual saliency and adaptive support vector machine in target tracking field.

    Science.gov (United States)

    Chen, Yuantao; Xu, Weihong; Kuang, Fangjun; Gao, Shangbing

    2013-01-01

    The efficient target tracking algorithm researches have become current research focus of intelligent robots. The main problems of target tracking process in mobile robot face environmental uncertainty. They are very difficult to estimate the target states, illumination change, target shape changes, complex backgrounds, and other factors and all affect the occlusion in tracking robustness. To further improve the target tracking's accuracy and reliability, we present a novel target tracking algorithm to use visual saliency and adaptive support vector machine (ASVM). Furthermore, the paper's algorithm has been based on the mixture saliency of image features. These features include color, brightness, and sport feature. The execution process used visual saliency features and those common characteristics have been expressed as the target's saliency. Numerous experiments demonstrate the effectiveness and timeliness of the proposed target tracking algorithm in video sequences where the target objects undergo large changes in pose, scale, and illumination.

  19. The Research and Application of Visual Saliency and Adaptive Support Vector Machine in Target Tracking Field

    Directory of Open Access Journals (Sweden)

    Yuantao Chen

    2013-01-01

    Full Text Available The efficient target tracking algorithm researches have become current research focus of intelligent robots. The main problems of target tracking process in mobile robot face environmental uncertainty. They are very difficult to estimate the target states, illumination change, target shape changes, complex backgrounds, and other factors and all affect the occlusion in tracking robustness. To further improve the target tracking’s accuracy and reliability, we present a novel target tracking algorithm to use visual saliency and adaptive support vector machine (ASVM. Furthermore, the paper’s algorithm has been based on the mixture saliency of image features. These features include color, brightness, and sport feature. The execution process used visual saliency features and those common characteristics have been expressed as the target’s saliency. Numerous experiments demonstrate the effectiveness and timeliness of the proposed target tracking algorithm in video sequences where the target objects undergo large changes in pose, scale, and illumination.

  20. Development of a Visual Inspection Data Collection Tool for Evaluation of Fielded PV Module Condition

    Energy Technology Data Exchange (ETDEWEB)

    Packard, C. E.; Wohlgemuth, J. H.; Kurtz, S. R.

    2012-08-01

    A visual inspection data collection tool for the evaluation of fielded photovoltaic (PV) modules has been developed to facilitate describing the condition of PV modules with regard to field performance. The proposed data collection tool consists of 14 sections, each documenting the appearance or properties of a part of the module. This report instructs on how to use the collection tool and defines each attribute to ensure reliable and valid data collection. This tool has been evaluated through the inspection of over 60 PV modules produced by more than 20 manufacturers and fielded at two different sites for varying periods of time. Aggregated data from such a single data collection tool has the potential to enable longitudinal studies of module condition over time, technology evolution, and field location for the enhancement of module reliability models.

  1. Polarization visualization of changes of anisotropic meat structure

    Science.gov (United States)

    Blokhina, Anastasia A.; Ryzhova, Victoria A.; Kleshchenok, Maksim A.; Lobanova, Anastasiya Y.

    2017-06-01

    The main aspect in developing methods for optical diagnostics and visualization of biological tissues using polarized radiation is the transformation analysis of the state of light polarization when it is scattered by the medium. The polarization characteristic spatial distributions of the detected scattered radiation, in particular the degree of depolarization, have a pronounced anisotropy. The presence of optical anisotropy can provide valuable additional information on the structural features of the biological object and its physiological status. Analysis of the polarization characteristics of the scattered radiation of biological tissues in some cases provides a qualitatively new results in the study of biological samples. These results can be used in medicine and food industry.

  2. How 3D immersive visualization is changing medical diagnostics

    Science.gov (United States)

    Koning, Anton H. J.

    2011-03-01

    Originally the only way to look inside the human body without opening it up was by means of two dimensional (2D) images obtained using X-ray equipment. The fact that human anatomy is inherently three dimensional leads to ambiguities in interpretation and problems of occlusion. Three dimensional (3D) imaging modalities such as CT, MRI and 3D ultrasound remove these drawbacks and are now part of routine medical care. While most hospitals 'have gone digital', meaning that the images are no longer printed on film, they are still being viewed on 2D screens. However, this way valuable depth information is lost, and some interactions become unnecessarily complex or even unfeasible. Using a virtual reality (VR) system to present volumetric data means that depth information is presented to the viewer and 3D interaction is made possible. At the Erasmus MC we have developed V-Scope, an immersive volume visualization system for visualizing a variety of (bio-)medical volumetric datasets, ranging from 3D ultrasound, via CT and MRI, to confocal microscopy, OPT and 3D electron-microscopy data. In this talk we will address the advantages of such a system for both medical diagnostics as well as for (bio)medical research.

  3. Assessment of visual space recognition of patients with unilateral spatial neglect and visual field defects using a head mounted display system.

    Science.gov (United States)

    Sugihara, Shunichi; Tanaka, Toshiaki; Miyasaka, Tomoya; Izumi, Takashi; Shimizu, Koichi

    2016-01-01

    [Purpose] The purpose of this study was the development of a method for presenting diverse visual information and assessing visual space recognition using a new head mounted display (HMD) system. [Subjects] Eight patients: four with unilateral spatial neglect (USN) and four with visual field defects (VFD). [Methods] A test sheet was placed on a desk, and its image was projected on the display of the HMD. Then, space recognition assessment was conducted using a cancellation test and motion analysis of the eyeballs and head under four conditions with images reduced in size and shifted. [Results] Leftward visual search was dominant in VFD patients, while rightward visual search was dominant in USN patients. The angular velocity of leftward eye movement during visual search of the right sheet decreased in both patient types. Motion analysis revealed a tendency of VFD patients to rotate the head in the affected direction under the left reduction condition, whereas USN patients rotated it in the opposite direction of the neglect. [Conclusion] A new HMD system was developed for presenting diverse visual information and assessing visual space recognition which identified the differences in the disturbance of visual space recognition of VFD and USN patients were indicated.

  4. Corporate rebranding: effects of corporate visual identity changes on employees and consumers

    NARCIS (Netherlands)

    Bolhuis, W.; de Jong, Menno D.T.; van den Bosch, A.L.M.

    2015-01-01

    Many organizations invest periodically in a new corporate visual identity (CVI). This study investigates the main effects of CVI changes in four organizations, taking into account three independent variables: stakeholder type (employees vs. consumers), the specific organization, and communication

  5. Visualization of the electric field evoked by transcranial electric stimulation during a craniotomy using the finite element method.

    Science.gov (United States)

    Tomio, Ryosuke; Akiyama, Takenori; Horikoshi, Tomo; Ohira, Takayuki; Yoshida, Kazunari

    2015-12-30

    Transcranial MEP (tMEP) monitoring is more readily performed than cortical MEP (cMEP), however, tMEP is considered as less accurate than cMEP. The craniotomy procedure and changes in CSF levels must affect current spread. These changes can impair the accuracy. The aim of this study was to investigate the influence of skull deformation and cerebrospinal fluid (CSF) decrease on tMEP monitoring during frontotemporal craniotomy. We used the finite element method to visualize the electric field in the brain, which was generated by transcranial electric stimulation, using realistic 3-dimensional head models developed from T1-weighted images. Surfaces of 5 layers of the head were separated as accurately as possible. We created 3 brain types and 5 craniotomy models. The electric field in the brain radiates out from the cortex just below the electrodes. When the CSF layer is thick, a decrease in CSF volume and depression of CSF surface level during the craniotomy has a major impact on the electric field. When the CSF layer is thin and the distance between the skull and brain is short, the craniotomy has a larger effect on the electric field than the CSF decrease. So far no report in the literature the electric field during intraoperative tMEP using a 3-dimensional realistic head model. Our main finding was that the intensity of the electric field in the brain is most affected by changes in the thickness and volume of the CSF layer. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. The trait of sensory processing sensitivity and neural responses to changes in visual scenes

    OpenAIRE

    Jagiellowicz, Jadzia; Xu, Xiaomeng; Aron, Arthur; Aron, Elaine; Cao, Guikang; Feng, Tingyong; Weng, Xuchu

    2010-01-01

    This exploratory study examined the extent to which individual differences in sensory processing sensitivity (SPS), a temperament/personality trait characterized by social, emotional and physical sensitivity, are associated with neural response in visual areas in response to subtle changes in visual scenes. Sixteen participants completed the Highly Sensitive Person questionnaire, a standard measure of SPS. Subsequently, they were tested on a change detection task while undergoing functional m...

  7. Efficient Incorporation of Markov Random Fields in Change Detection

    DEFF Research Database (Denmark)

    Aanæs, Henrik; Nielsen, Allan Aasbjerg; Carstensen, Jens Michael

    2009-01-01

    Many change detection algorithms work by calculating the probability of change on a pixel-wise basis. This is a disadvantage since one is usually looking for regions of change, and such information is not used in pixel-wise classification - per definition. This issue becomes apparent in the face...... of noise, implying that the pixel-wise classifier is also noisy. There is thus a need for incorporating local homogeneity constraints into such a change detection framework. For this modelling task Markov Random Fields are suitable. Markov Random Fields have, however, previously been plagued by lack...... of efficient optimization methods or numerical solvers. We here address the issue of efficient incorporation of local homogeneity constraints into change detection algorithms. We do this by exploiting recent advances in graph based algorithms for Markov Random Fields. This is combined with an IR-MAD change...

  8. Motion-based super-resolution in the peripheral visual field.

    Science.gov (United States)

    Patrick, Jonathan A; Roach, Neil W; McGraw, Paul V

    2017-08-01

    Improvements in foveal acuity for moving targets have been interpreted as evidence for the ability of the visual system to combine information over space and time, in order to reconstruct the image at a higher resolution (super-resolution). Here, we directly test whether this occurs in the peripheral visual field and discuss its potential for improving functional capacity in ocular disease. The effect of motion on visual acuity was first compared under conditions in which performance was limited either by natural undersampling in the retinal periphery or by the presence of overlaid masks with opaque elements to simulate retinal loss. To equate the information content of moving and static sequences, we next manipulated the dynamic properties of the masks. Finally, we determined the dependence of motion-related improvements on the object of motion (target or mask) and its trajectory (smooth or jittered). Motion improved visual acuity for masked but not unmasked peripheral targets. Equating the information content of moving and static conditions removed some but not all of this benefit. Residual motion-related improvements were largest in conditions in which the target moved along a consistent and predictable path. Our results show that motion can improve peripheral acuity in situations in which performance is limited by abnormal undersampling. These findings are consistent with the operation of a super-resolution system and could have important implications for any pathology that alters the regular sampling properties of the retinal mosaic.

  9. Altered Balance of Receptive Field Excitation and Suppression in Visual Cortex of Amblyopic Macaque Monkeys.

    Science.gov (United States)

    Hallum, Luke E; Shooner, Christopher; Kumbhani, Romesh D; Kelly, Jenna G; García-Marín, Virginia; Majaj, Najib J; Movshon, J Anthony; Kiorpes, Lynne

    2017-08-23

    In amblyopia, a visual disorder caused by abnormal visual experience during development, the amblyopic eye (AE) loses visual sensitivity whereas the fellow eye (FE) is largely unaffected. Binocular vision in amblyopes is often disrupted by interocular suppression. We used 96-electrode arrays to record neurons and neuronal groups in areas V1 and V2 of six female macaque monkeys ( Macaca nemestrina ) made amblyopic by artificial strabismus or anisometropia in early life, as well as two visually normal female controls. To measure suppressive binocular interactions directly, we recorded neuronal responses to dichoptic stimulation. We stimulated both eyes simultaneously with large sinusoidal gratings, controlling their contrast independently with raised-cosine modulators of different orientations and spatial frequencies. We modeled each eye's receptive field at each cortical site using a difference of Gaussian envelopes and derived estimates of the strength of central excitation and surround suppression. We used these estimates to calculate ocular dominance separately for excitation and suppression. Excitatory drive from the FE dominated amblyopic visual cortex, especially in more severe amblyopes, but suppression from both the FE and AEs was prevalent in all animals. This imbalance created strong interocular suppression in deep amblyopes: increasing contrast in the AE decreased responses at binocular cortical sites. These response patterns reveal mechanisms that likely contribute to the interocular suppression that disrupts vision in amblyopes. SIGNIFICANCE STATEMENT Amblyopia is a developmental visual disorder that alters both monocular vision and binocular interaction. Using microelectrode arrays, we examined binocular interaction in primary visual cortex and V2 of six amblyopic macaque monkeys ( Macaca nemestrina ) and two visually normal controls. By stimulating the eyes dichoptically, we showed that, in amblyopic cortex, the binocular combination of signals is

  10. Visual field meridians modulate the reallocation of object-based attention.

    Science.gov (United States)

    Barnas, Adam J; Greenberg, Adam S

    2016-10-01

    Object-based attention (OBA) enhances processing within the boundaries of a selected object. Larger OBA effects have been observed for horizontal compared to vertical rectangles, which were eliminated when controlling for attention shifts across the visual field meridians. We aimed to elucidate the modulatory role of the meridians on OBA. We hypothesized that the contralateral organization of visual cortex accounts for these differences in OBA prioritization. Participants viewed "L"-shaped objects and, following a peripheral cue at the object vertex, detected the presence of a target at the cued location (valid), or at a non-cued location (invalid) offset either horizontally or vertically. In Experiment 1, the single displayed object contained components crossing both meridians. In Experiment 2, one cued object and one non-cued object were displayed such that both crossed the meridians. In Experiment 3, one cued object was sequestered into one screen quadrant, with its vertex either near or far from fixation. Results from Experiments 1 and 2 revealed a horizontal shift advantage (faster RTs for horizontal shifts across the vertical meridian compared to vertical shifts across the horizontal meridian), regardless of whether shifts take place within a cued object (Experiment 1) or between objects (Experiment 2). Results from Experiment 3 revealed no difference between horizontal and vertical shifts for objects that were positioned far from fixation, although the horizontal shift advantage reappeared for objects near fixation. These findings suggest a critical modulatory role of visual field meridians in the efficiency of reorienting object-based attention.

  11. Attentional and emotional prioritization of the sounds occurring outside the visual field.

    Science.gov (United States)

    Asutay, Erkin; Västfjäll, Daniel

    2015-06-01

    The ability to detect and localize sounds in an environment is critical for survival. Localizing sound sources is a computational challenge for the human brain because the auditory cortex seems to lack a topographical space representation. However, attention and task demands can modulate localization performance. Here, we investigated whether the localization performance for sounds occurring directly in front of or behind people could be modulated by emotional salience and sound-source location. We measured auditory-induced emotion by ecological sounds occurring in the frontal or rear perceptual fields, and employed a speeded localization task. The results showed that both localization speed and accuracy were higher, and that stronger negative emotions were induced when sound sources were behind the participants. Our results provide clear behavioral evidence that auditory attention can be influenced by sound-source location. Importantly, we also show that the effect of spatial location on attention is mediated by emotion, which is in line with the argument that emotional information is prioritized in processing. Auditory system functions as an alarm system and is in charge of detecting possible salient events, and alarming for an attention shift. Further, spatial processing in the auditory dorsal pathway has a function of guiding the visual system to a particular location of interest. Thus, an auditory bias toward the space outside the visual field can be useful, so that visual attention could be quickly shifted in case of emotionally significant information. (c) 2015 APA, all rights reserved).

  12. Visual Aid to Demonstrate Change of State and Gas Pressure with Temperature

    Science.gov (United States)

    Ghaffari, Shahrokh

    2011-01-01

    Demonstrations are used in chemistry lectures to improve conceptual understanding by direct observation. The visual aid described here is designed to demonstrate the change in state of matter with the change of temperature and the change of pressure with temperature. Temperature is presented by the rate of airflow and pressure is presented by…

  13. Evaluating the use of uncertainty visualization for exploratory analysis of land cover change: A qualitative expert user study

    Science.gov (United States)

    Kinkeldey, Christoph; Schiewe, Jochen; Gerstmann, Henning; Götze, Christian; Kit, Oleksandr; Lüdeke, Matthias; Taubenböck, Hannes; Wurm, Michael

    2015-11-01

    Extensive research on geodata uncertainty has been conducted in the past decades, mostly related to modeling, quantifying, and communicating uncertainty. But findings on if and how users can incorporate this information into spatial analyses are still rare. In this paper we address these questions with a focus on land cover change analysis. We conducted semi-structured interviews with three expert groups dealing with change analysis in the fields of climate research, urban development, and vegetation monitoring. During the interviews we used a software prototype to show change scenarios that the experts had analyzed before, extended by visual depiction of uncertainty related to land cover change. This paper describes the study, summarizes results, and discusses findings as well as the study method. Participants came up with several ideas for applications that could be supported by uncertainty, for example, identification of erroneous change, description of change detection algorithm characteristics, or optimization of change detection parameters. Regarding the aspect of reasoning with uncertainty in land cover change data the interviewees saw potential in better-informed hypotheses and insights about change. Communication of uncertainty information to users was seen as critical, depending on the users' role and expertize. We judge semi-structured interviews to be suitable for the purpose of this study and emphasize the potential of qualitative methods (workshops, focus groups etc.) for future uncertainty visualization studies.

  14. Factors affecting eye drop instillation in glaucoma patients with visual field defect.

    Directory of Open Access Journals (Sweden)

    Tomoko Naito

    Full Text Available To investigate the success rate of eye drop instillation in glaucoma patients with visual field defect as well as non-glaucoma volunteers. Factors that may affect the success rate of eye drop instillation were also evaluated.A prospective, observational study.Seventy-eight glaucoma patients and 85 non-glaucoma volunteers were recruited in this study.Open angle glaucoma patients with visual field defect as well as non-glaucoma volunteers were asked to video record their procedures of eye drop instillation using a 5-mL plastic bottle of artificial tear solution. Success of eye drop instillation was judged on video based on the first one drop of solution successfully applied on the cornea, by two investigators.Success rate of eye drop instillation in glaucoma patients and non-glaucoma volunteers. Factors related to success rate of eye drop instillation, such as visual field defect and clinical characteristics, were also analyzed using multivariable logistic regression.No significant deference in mean age was observed between two groups (glaucoma: 64.5 ± 14.4 years, non-glaucoma: 60.9 ± 14.1 years, P = 0.1156. Success rate of eye drop instillation was significantly lower (P = 0.0215 in glaucoma patients (30/78; 38.5% than in non-glaucoma volunteers (48/85; 56.5%. The most frequent reason of instillation failure in glaucoma patients was touching the bulbar conjunctiva, cornea, eyelid or eyelashes with the tip of the bottle (29.5%. Multivariable logistic regression analysis identified lower corrected visual acuity (VA (≤ 1.0; odds ratio [OR] = 0.20, 95% confidence interval [CI] 0.04-0.93, P = 0.0411, lower mean deviation (MD (< -12 dB; OR = 0.20, 95% CI 0.05-0.86, P = 0.0307 and visual field defect (VFD in the inferior hemifield (OR = 0.11, 95% CI 0.02-0.34, P < 0.001 to be significantly related to instillation failure in glaucoma patients.Success rate of eye drop instillation was significantly lower in glaucoma patients than in non

  15. Comparison of corneal biomechanical properties in normal tension glaucoma patients with different visual field progression speed.

    Science.gov (United States)

    Hong, Ying; Shoji, Nobuyuki; Morita, Tetsuya; Hirasawa, Kazunori; Matsumura, Kazuhiro; Kasahara, Masayuki; Shimizu, Kimiya

    2016-01-01

    To compare the corneal biomechanical properties difference by ocular response analyzer (ORA) in normal tension glaucoma (NTG) patients with different visual field (VF) progression speed. NTG patients with well-controlled Goldmann applanation tonometer (GAT) who routinely consulted Kitasato University Hospital Glaucoma Department between January 2010 and February 2014 were enrolled. GAT and ORA parameters including corneal compensated intraocular pressure (IOPcc), Goldmann estimated intraocular pressure (IOPg), corneal hysteresis (CH), corneal resistance factor (CRF) were recorded. VF was tested by Swedish interactive threshold algorithm (SITA)-standard 30-2 fields. All patients underwent VF measurement regularly and GAT did not exceed 15 mm Hg at any time during the 3y follow up. Patients were divided into four groups according to VF change over 3y, and ORA findings were compared between the upper 25(th) percentile group (slow progression group) and the lower 25(th) percentile group (rapid progression group). Eighty-two eyes of 56 patients were studied. There were 21 eyes (21 patients) each in rapid and slow progression groups respectively. GAT, IOPcc, IOPg, CH, CRF were 12.1±1.4 mm Hg, 15.8±1.8 mm Hg, 12.8±2.0 mm Hg, 8.4±1.1 mm Hg, 7.9±1.3 mm Hg respectively in rapid progression group and 11.5±1.3 mm Hg, 13.5±2.1 mm Hg, 11.2±1.6 mm Hg, 9.3±1.1 mm Hg, 8.2±0.9 mm Hg respectively in slow progression group (P=0.214, <0.001, 0.007, 0.017, 0.413, respectively). In bivariate correlation analysis, IOPcc, IOPcc-GAT and CH were significant correlated with mΔMD (r=-0.292, -0.312, 0.228 respectively, P=0.008, 0.004, 0.039 respectively). Relatively rapid VF progression occurred in NTG patients whose IOPcc are rather high, CH are rather low and the difference between IOPcc and GAT are relatively large. Higher IOPcc and lower CH are associated with VF progression in NTG patients. This study suggests that GAT measures might underestimate the IOP in such patients.

  16. Near-field visualization of plasmonic lenses: an overall analysis of characterization errors

    Directory of Open Access Journals (Sweden)

    Jing Wang

    2015-10-01

    Full Text Available Many factors influence the near-field visualization of plasmonic structures that are based on perforated elliptical slits. Here, characterization errors are experimentally analyzed in detail from both fabrication and measurement points of view. Some issues such as geometrical parameter, probe–sample surface interaction, misalignment, stigmation, and internal stress, have influence on the final near-field probing results. In comparison to the theoretical ideal case of near-field probing of the structures, numerical calculation is carried out on the basis of a finite-difference and time-domain (FDTD algorithm so as to support the error analyses. The analyses performed on the basis of both theoretical calculation and experimental probing can provide a helpful reference for the researchers probing their plasmonic structures and nanophotonic devices.

  17. Changing struggles for relevance in eight fields of natural science

    NARCIS (Netherlands)

    Hessels, L.K.; van Lente, H.; Grin, J.; Smits, R.E.H.M.

    2011-01-01

    This paper investigates the consequences of institutional changes on academic research practices in eight fields of natural science in the Netherlands. The authors analyse the similarities and differences among the dynamics of these different fields and reflect on possible explanations for the

  18. Director field model of the primary visual cortex for contour detection.

    Directory of Open Access Journals (Sweden)

    Vijay Singh

    Full Text Available We aim to build the simplest possible model capable of detecting long, noisy contours in a cluttered visual scene. For this, we model the neural dynamics in the primate primary visual cortex in terms of a continuous director field that describes the average rate and the average orientational preference of active neurons at a particular point in the cortex. We then use a linear-nonlinear dynamical model with long range connectivity patterns to enforce long-range statistical context present in the analyzed images. The resulting model has substantially fewer degrees of freedom than traditional models, and yet it can distinguish large contiguous objects from the background clutter by suppressing the clutter and by filling-in occluded elements of object contours. This results in high-precision, high-recall detection of large objects in cluttered scenes. Parenthetically, our model has a direct correspondence with the Landau-de Gennes theory of nematic liquid crystal in two dimensions.

  19. Hearing brighter: changing in-depth visual perception through looming sounds.

    Science.gov (United States)

    Sutherland, Clare A M; Thut, Gregor; Romei, Vincenzo

    2014-09-01

    Rapidly approaching (looming) sounds are ecologically salient stimuli that are perceived as nearer than they are due to overestimation of their loudness change and underestimation of their distance (Neuhoff, 1998; Seifritz et al., 2002). Despite evidence for crossmodal influence by looming sounds onto visual areas (Romei, Murray, Cappe, & Thut, 2009, 2013; Tyll et al., 2013), it is unknown whether such sounds bias visual percepts in similar ways. Nearer objects appear to be larger and brighter than distant objects. If looming sounds impact visual processing, then visual stimuli paired with looming sounds should be perceived as brighter and larger, even when the visual stimuli do not provide motion cues, i.e. are static. In Experiment 1 we found that static visual objects paired with looming tones (but not static or receding tones) were perceived as larger and brighter than their actual physical properties, as if they appear closer to the observer. In a second experiment, we replicate and extend the findings of Experiment 1. Crucially, we did not find evidence of such bias by looming sounds when visual processing was disrupted via masking or when catch trials were presented, ruling out simple response bias. Finally, in a third experiment we found that looming tones do not bias visual stimulus characteristics that do not carry visual depth information such as shape, providing further evidence that they specifically impact in-depth visual processing. We conclude that looming sounds impact visual perception through a mechanism transferring in-depth sound motion information onto the relevant in-depth visual dimensions (such as size and luminance but not shape) in a crossmodal remapping of information for a genuine, evolutionary advantage in stimulus detection. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Electric-field-assisted crystallisation in phase-change materials

    Energy Technology Data Exchange (ETDEWEB)

    Kohary, Krisztian; Diosdado, Jorge A.V.; Ashwin, Peter; Wright, C. David [College of Engineering, Mathematics, and Physical Sciences, University of Exeter (United Kingdom)

    2012-10-15

    Phase-change materials are of intense research interest due mainly to their use in phase-change memory (PCM) devices that are emerging as a promising technology for future non-volatile, solid-state, electrical storage. Electrically driven transitions from the amorphous to the crystalline phase in such devices exhibit characteristic threshold switching. Several alternative electronic explanations for the origins of this characteristic behaviour have been put forward, for example Poole-Frenkel effects, delocalisation of tail states, field emission processes and space charge limited currents [for a full discussion, see Radielli et al., J. Appl. Phys. 103, 111101 (2008) and Simon et al., MRS Proc. 1251, H01-H011 (2010)]. However, an alternative to these conventional electronic models of threshold switching is based on electric field induced lowering of the system free energy, leading to the field induced nucleation of conducting crystal filaments. In this paper we investigate this alternative view. We present a detailed kinetics study of crystallisation in the presence of an electric field for the phase-change material Ge{sub 2}Sb{sub 2}Te{sub 5}. We derive quantitative crystallisation maps to show the effects of both temperature and electric field on crystallisation and we identify field ranges and parameter values where the electric field might play a significant role. Then we carry out physically realistic simulations of the threshold switching process in typical phase-change device structures, both with and without electric field dependent energy contributions to the system free energy. Our results show that threshold switching can be obtained by a mechanism driven purely by electric field induced nucleation, but the fields so required are large, of the order of 300 MV m{sup -1}, and significantly larger than the experimentally measured threshold fields. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Categorical Perception of Colour in the Left and Right Visual Field Is Verbally Mediated: Evidence from Korean

    Science.gov (United States)

    Roberson, Debi; Pak, Hyensou; Hanley, J. Richard

    2008-01-01

    In this study we demonstrate that Korean (but not English) speakers show Categorical perception (CP) on a visual search task for a boundary between two Korean colour categories that is not marked in English. These effects were observed regardless of whether target items were presented to the left or right visual field. Because this boundary is…

  2. Genre Differences on Visual Perception of Color Range and Depth of Field

    Directory of Open Access Journals (Sweden)

    Luisa Ballesteros

    2003-07-01

    Full Text Available Visual perception is the result of the integration of various related factors of the observed object and its environment. In this study we evaluated the impact of tridimensional form on color perception and the angle from the horizontal plane of a set of similar objets on the depth of field perception between young men and women. A panel half magenta and half white placed at the end of a black box, folded either concaved or convexed to alter the chromatic effect perceived were used to determine tridimensional form on color perception. Four sets of identical sticks where the angle from the horizontal plane varied for each, were used to determine the effect of spatial distribution of depth of field perception. The parameters taking into account were age, genre, associated visual defects for each individual evaluated. Our results show that the tridimensional form alters color perception but the range of color perceived was larger for women whereas depending on the angle from the horizontal plane we found genre differences on the depth of field perception.

  3. Surround modulation characteristics of local field potential and spiking activity in primary visual cortex of cat.

    Science.gov (United States)

    Zhang, Li; Li, Bing

    2013-01-01

    In primary visual cortex, spiking activity that evoked by stimulus confined in receptive field can be modulated by surround stimulus. This center-surround interaction is hypothesized to be the basis of visual feature integration and segregation. Spiking output has been extensively reported to be surround suppressive. However, less is known about the modulation properties of the local field potential (LFP), which generally reflects synaptic inputs. We simultaneously recorded spiking activity and LFP in the area 17 of anesthetized cats to examine and compare their modulation characteristics. When the stimulus went beyond the classical receptive field, LFP exhibited decreased power along the gamma band (30-100 Hz) in most of our recording sites. Further investigation revealed that suppression of the LFP gamma mean power (gLFP) depended on the angle between the center and surround orientations. The strongest suppression was induced when center and surround orientations were parallel. Moreover, the surround influence of the gLFP exhibited an asymmetric spatial organization. These results demonstrate that the gLFP has similar but not identical surround modulation properties, as compared to the spiking activity. The spatiotemporal integration of LFP implies that the oscillation and synchronization of local synaptic inputs may have important functions in surround modulation.

  4. RGB-NDVI colour composites for visualizing forest change dynamics

    Science.gov (United States)

    Sader, S. A.; Winne, J. C.

    1992-01-01

    The study presents a simple and logical technique to display and quantify forest change using three dates of satellite imagery. The normalized difference vegetation index (NDVI) was computed for each date of imagery to define high and low vegetation biomass. Color composites were generated by combining each date of NDVI with either the red, green, or blue (RGB) image planes in an image display monitor. Harvest and regeneration areas were quantified by applying a modified parallelepiped classification creating an RGB-NDVI image with 27 classes that were grouped into nine major forest change categories. Aerial photographs and stand history maps are compared with the forest changes indicated by the RGB-NDVI image. The utility of the RGB-NDVI technique for supporting forest inventories and updating forest resource information systems are presented and discussed.

  5. Right visual field advantage in parafoveal processing: evidence from eye-fixation-related potentials.

    Science.gov (United States)

    Simola, Jaana; Holmqvist, Kenneth; Lindgren, Magnus

    2009-11-01

    Readers acquire information outside the current eye fixation. Previous research indicates that having only the fixated word available slows reading, but when the next word is visible, reading is almost as fast as when the whole line is seen. Parafoveal-on-foveal effects are interpreted to reflect that the characteristics of a parafoveal word can influence fixation on a current word. Prior studies also show that words presented to the right visual field (RVF) are processed faster and more accurately than words in the left visual field (LVF). This asymmetry results either from an attentional bias, reading direction, or the cerebral asymmetry of language processing. We used eye-fixation-related potentials (EFRP), a technique that combines eye-tracking and electroencephalography, to investigate visual field differences in parafoveal-on-foveal effects. After a central fixation, a prime word appeared in the middle of the screen together with a parafoveal target that was presented either to the LVF or to the RVF. Both hemifield presentations included three semantic conditions: the words were either semantically associated, non-associated, or the target was a non-word. The participants began reading from the prime and then made a saccade towards the target, subsequently they judged the semantic association. Between 200 and 280ms from the fixation onset, an occipital P2 EFRP-component differentiated between parafoveal word and non-word stimuli when the parafoveal word appeared in the RVF. The results suggest that the extraction of parafoveal information is affected by attention, which is oriented as a function of reading direction.

  6. Change in psychological problems of adolescents with and without visual impairment.

    Science.gov (United States)

    Pinquart, Martin; Pfeiffer, Jens P

    2014-07-01

    The present study analyzed change in psychological problems of German adolescents with and without visual impairment across a 2-year interval. A total of 182 adolescents with severe visual impairment and 560 sighted adolescents provided longitudinal data. At the start of the study, adolescents with visual impairment had, on average, elevated scores on all difficulties scales of the Strengths and Difficulties Questionnaire (SDQ) (Goodman R, J Child Psychol Psychiat 38:581-586), 1997 and about 39 % of them scored in the abnormal range of one or more scales as compared to 30.5 % of their sighted peers (p visual impairment and with early onset of visual impairment in particular, may benefit from psychological interventions aimed at preventing and reducing psychological problems and increasing the ability to cope with stressors associated with vision loss.

  7. Electron holographic visualization of collective motion of electrons through electric field variation.

    Science.gov (United States)

    Shindo, Daisuke; Aizawa, Shinji; Akase, Zentaro; Tanigaki, Toshiaki; Murakami, Yasukazu; Park, Hyun Soon

    2014-08-01

    This study demonstrates the accumulation of electron-induced secondary electrons by utilizing a simple geometrical configuration of two branches of a charged insulating biomaterial. The collective motion of these secondary electrons between the branches has been visualized by analyzing the reconstructed amplitude images obtained using in situ electron holography. In order to understand the collective motion of secondary electrons, the trajectories of these electrons around the branches have also been simulated by taking into account the electric field around the charged branches on the basis of Maxwell's equations.

  8. visual methods, social change and collective learning over time

    African Journals Online (AJOL)

    Other constraints, such as structural violence and institutional racism, can also intersect with the possibility of making tangible change through educational research using ... prevention efforts and to break the stigma of AIDS. It was the beginning of work with a group of around 50 racially diverse young people from Atlantis, ...

  9. Duration-Related Variations in Archaeal Communities after a Change from Upland Fields to Paddy Fields.

    Science.gov (United States)

    Jiang, Nan; Wei, Kai; Chen, Lijun; Chen, Rui

    2016-05-28

    Archaea substantially contribute to global geochemical cycling and energy cycling and are impacted by land-use change. However, the response of archaeal communities to a change from upland field to paddy field has been poorly characterized. Here, soil samples were collected at two depths (0-20 cm and 20-40 cm) from one upland field and six paddy fields that were established on former upland fields at different times (1, 5, 10, 20, 30, and 40 years before the study). Barcoded pyrosequencing was employed to assess the archaeal communities from the samples at taxonomic resolutions from phylum to genus levels. The total archaeal operational taxonomic unit (OTU) richness showed a significant positive correlation with the land-use change duration. Two phyla, Euryarchaeota and Crenarchaeota, were recorded throughout the study. Both the relative abundance and OTU richness of Euryarchaeota increased at both depths but increased more steadily at the subsurface rather than at the surface. However, these data of Crenarchaeota were the opposite. Additionally, the archaeal composition exhibited a significant relationship with C/N ratios, total phosphorus, soil pH, Olsen phosphorus, and the land-use change duration at several taxonomic resolutions. Our results emphasize that after a change from upland fields to paddy fields, the archaeal diversity and composition changed, and the duration is an important factor in addition to the soil chemical properties.

  10. The eyes have it: regulatory and structural changes both underlie cichlid visual pigment diversity.

    Directory of Open Access Journals (Sweden)

    Christopher M Hofmann

    2009-12-01

    Full Text Available A major goal of evolutionary biology is to unravel the molecular genetic mechanisms that underlie functional diversification and adaptation. We investigated how changes in gene regulation and coding sequence contribute to sensory diversification in two replicate radiations of cichlid fishes. In the clear waters of Lake Malawi, differential opsin expression generates diverse visual systems, with sensitivities extending from the ultraviolet to the red regions of the spectrum. These sensitivities fall into three distinct clusters and are correlated with foraging habits. In the turbid waters of Lake Victoria, visual sensitivity is constrained to longer wavelengths, and opsin expression is correlated with ambient light. In addition to regulatory changes, we found that the opsins coding for the shortest- and longest-wavelength visual pigments have elevated numbers of potentially functional substitutions. Thus, we present a model of sensory evolution in which both molecular genetic mechanisms work in concert. Changes in gene expression generate large shifts in visual pigment sensitivity across the collective opsin spectral range, but changes in coding sequence appear to fine-tune visual pigment sensitivity at the short- and long-wavelength ends of this range, where differential opsin expression can no longer extend visual pigment sensitivity.

  11. Climate change effects at your doorstep: Geographic visualization to support Nordic homeowners in adapting to climate change

    DEFF Research Database (Denmark)

    Neset, Tina; Glaas, Erik; Ballantyne, Anne Gammelgaard

    2016-01-01

    ™ is a web-based visualization tool designed to improve Nordic homeowners’ understanding of climate change vulnerability and to support their adaptive actions. VisAdapt is structured to enable individual users to explore several climate change impact parameters, including temperature and precipitation...... and user experience, a general conclusion is that a geographic visualization tool, like VisAdapt, can make climate change effects and adaptation alternatives tangible and initiate discussions and collaborative reflections.......The complexity of climate information, particularly as related to climate scenarios, impacts, and action alternatives, poses significant challenges for science communication. This study presents a geographic visualization approach involving lay audiences to address these challenges. VisAdapt...

  12. Visual Half-Field Experiments Are a Good Measure of Cerebral Language Dominance if Used Properly: Evidence from fMRI

    Science.gov (United States)

    Hunter, Zoe R.; Brysbaert, Marc

    2008-01-01

    Traditional neuropsychology employs visual half-field (VHF) experiments to assess cerebral language dominance. This approach is based on the assumption that left cerebral dominance for language leads to faster and more accurate recognition of words in the right visual half-field (RVF) than in the left visual half-field (LVF) during tachistoscopic…

  13. Retrobulbar Hemodynamics and Visual Field Progression in Normal Tension Glaucoma: A Long-Term Follow-Up Study

    Directory of Open Access Journals (Sweden)

    D. Kuerten

    2015-01-01

    Full Text Available Purpose. Vascular risk factors are important factors in the pathogenesis of glaucoma. The purpose of this research was to investigate retrobulbar hemodynamics and visual field progression in patients with normal tension glaucoma (NTG. Patients and Methods. 31 eyes of 16 patients with NTG were included in a retrospective long-term follow-up study. Colour Doppler imaging was performed at baseline to determine various CDI parameters in the different retrobulbar vessels. The rate of visual field progression was determined using the Visual Field Index (VFI progression rate per year (in %. To be included in the analysis, patients had at least 4 visual field examinations with a follow-up of at least 2 years. Results. Mean follow-up was 7.6 ± 4.1 years with an average of 10 ± 5 visual field tests. The mean MD (mean defect at baseline was −7.61 ± 7.49 dB. The overall VFI progression was −1.14 ± 1.40% per year. A statistical significant correlation between VFI progression and the RI of the NPCA and PSV of the CRA was found. Conclusion. Long-term visual field progression may be linked to impaired retrobulbar hemodynamics in patients with NTG only to a limited degree. Interpretation of the data for an individual patient seems to be limited due to the variability of parameters.

  14. Visual acuity loss and OCT changes as initial signs of leukaemia

    Science.gov (United States)

    Ortiz, Jose M; Ruiz-Moreno, Jose M; Pozo-Martos, Paola; Montero, Javier A

    2010-01-01

    AIM To report two cases where decreased visual acuity was the first symptom of leukaemia and optical coherence tomography (OCT) allowed identification and localization of the retinal lesions. METHODS Retrospective, interventional, case reports. RESULTS One case of lymphoblastic acute leukaemia and chronic lymphoid leukaemia were diagnosed following decreased visual acuity. OCT showed macular serous detachment in the first case. The second case presented hypo fluorescent retinal infiltrates which appeared as hyper reflective lesions by OCT. Retinal changes disappeared and visual acuity was recovered following complete remission of the neoplasm. CONCLUSION OCT is a valuable, non invasive diagnostic tool permitting detection, localization and follow-up of ocular dissemination of neoplasms. PMID:22553573

  15. Short Latency Gray Matter Changes in Voxel-Based Morphometry following High Frequent Visual Stimulation

    OpenAIRE

    Steffen Naegel; Tim Hagenacker; Nina Theysohn; Hans-Christoph Diener; Zaza Katsarava; Mark Obermann; Dagny Holle

    2017-01-01

    Magnetic resonance imaging studies using voxel-based morphometry (VBM) detected structural changes in the human brain within periods of months or weeks. The underlying molecular mechanisms of VBM findings remain unresolved. We showed that simple visual stimulation by an alternating checkerboard leads to instant, short-lasting alterations of the primary and secondary visual cortex detected by VBM. The rapidness of occurrence (i.e., within 10 minutes) rather excludes most of the proposed physio...

  16. Involvement of the visual change detection process in facilitating perceptual alternation in the bistable image.

    Science.gov (United States)

    Urakawa, Tomokazu; Bunya, Mao; Araki, Osamu

    2017-08-01

    A bistable image induces one of two perceptual alternatives. When the bistable visual image is continuously viewed, the percept of the image alternates from one possible percept to the other. Perceptual alternation was previously reported to be induced by an exogenous perturbation in the bistable image, and this perturbation was theoretically interpreted to cause neural noise, prompting a transition between two stable perceptual states. However, little is known experimentally about the visual processing of exogenously driven perceptual alternation. Based on the findings of a previous behavioral study (Urakawa et al. in Perception 45:474-482, 2016), the present study hypothesized that the automatic visual change detection process, which is relevant to the detection of a visual change in a sequence of visual events, has an enhancing effect on the induction of perceptual alternation, similar to neural noise. In order to clarify this issue, we developed a novel experimental paradigm in which visual mismatch negativity (vMMN), an electroencephalographic brain response that reflects visual change detection, was evoked while participants continuously viewed the bistable image. In terms of inter-individual differences in neural and behavioral data, we found that enhancements in the peak amplitude of vMMN1, early vMMN at a latency of approximately 150 ms, correlated with increases in the proportion of perceptual alternation across participants. Our results indicate the involvement of automatic visual change detection in the induction of perceptual alternation, similar to neural noise, thereby providing a deeper insight into the neural mechanisms underlying exogenously driven perceptual alternation in the bistable image.

  17. Comparative Visualization of Vector Field Ensembles Based on Longest Common Subsequence

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Richen; Guo, Hanqi; Zhang, Jiang; Yuan, Xiaoru

    2016-04-19

    We propose a longest common subsequence (LCS) based approach to compute the distance among vector field ensembles. By measuring how many common blocks the ensemble pathlines passing through, the LCS distance defines the similarity among vector field ensembles by counting the number of sharing domain data blocks. Compared to the traditional methods (e.g. point-wise Euclidean distance or dynamic time warping distance), the proposed approach is robust to outlier, data missing, and sampling rate of pathline timestep. Taking the advantages of smaller and reusable intermediate output, visualization based on the proposed LCS approach revealing temporal trends in the data at low storage cost, and avoiding tracing pathlines repeatedly. Finally, we evaluate our method on both synthetic data and simulation data, which demonstrate the robustness of the proposed approach.

  18. Primary Generators of Visually Evoked Field Potentials Recorded in the Macaque Auditory Cortex.

    Science.gov (United States)

    Kajikawa, Yoshinao; Smiley, John F; Schroeder, Charles E

    2017-10-18

    Prior studies have reported "local" field potential (LFP) responses to faces in the macaque auditory cortex and have suggested that such face-LFPs may be substrates of audiovisual integration. However, although field potentials (FPs) may reflect the synaptic currents of neurons near the recording electrode, due to the use of a distant reference electrode, they often reflect those of synaptic activity occurring in distant sites as well. Thus, FP recordings within a given brain region (e.g., auditory cortex) may be "contaminated" by activity generated elsewhere in the brain. To determine whether face responses are indeed generated within macaque auditory cortex, we recorded FPs and concomitant multiunit activity with linear array multielectrodes across auditory cortex in three macaques (one female), and applied current source density (CSD) analysis to the laminar FP profile. CSD analysis revealed no appreciable local generator contribution to the visual FP in auditory cortex, although we did note an increase in the amplitude of visual FP with cortical depth, suggesting that their generators are located below auditory cortex. In the underlying inferotemporal cortex, we found polarity inversions of the main visual FP components accompanied by robust CSD responses and large-amplitude multiunit activity. These results indicate that face-evoked FP responses in auditory cortex are not generated locally but are volume-conducted from other face-responsive regions. In broader terms, our results underscore the caution that, unless far-field contamination is removed, LFPs in general may reflect such "far-field" activity, in addition to, or in absence of, local synaptic responses.SIGNIFICANCE STATEMENT Field potentials (FPs) can index neuronal population activity that is not evident in action potentials. However, due to volume conduction, FPs may reflect activity in distant neurons superimposed upon that of neurons close to the recording electrode. This is problematic as the

  19. [Clinico-statistical study on availability of Esterman disability score for assessment of mobility difficulty in patients with visual field loss].

    Science.gov (United States)

    Yamagata, Yoshitaka; Terada, Yuko; Suzuki, Atsushi; Mimura, Osamu

    2010-01-01

    The visual efficiency scale currently adopted to determine the legal grade of visual disability associated with visual field loss in Japan is not appropriate for the evaluation of disability regarding daily living activities. We investigated whether Esterman disability score (EDS) is suitable for the assessment of mobility difficulty in patients with visual field loss. The correlation between the EDS calculated from Goldmann's kinetic visual field and the degree of subjective mobility difficulty determined by a questionnaire was investigated in 164 patients with visual field loss. The correlation between the EDS determined using a program built into the Humphrey field analyzer and that calculated from Goldmann's kinetic visual field was also investigated. The EDS based on the kinetic visual field was correlated well with the degree of subjective mobility difficulty, and the EDS measured using the Humphrey field analyzer could be estimated from the kinetic visual field-based EDS. Instead of the currently adopted visual efficiency scale, EDS should be employed for the assessment of mobility difficulty in patients with visual field loss, also to establish new judgment criteria concerning the visual field.

  20. A Methodology of Image Segmentation for High Resolution Remote Sensing Image Based on Visual System and Markov Random Field

    Directory of Open Access Journals (Sweden)

    XU Miaozhong

    2015-02-01

    Full Text Available In consideration of the visual system's tremendous ability to perceive and identify the information, a new image segmentation method is presented which simulates the mechanism of visual system for the high resolution remote sensing image segmentation with Markov random field model. Firstly, the characteristics of the visual system have been summarized as: hierarchy, learning ability, feature detection capability and sparse coding property. Secondly, the working mechanism of visual system is simulated by wavelet transform, unsupervised clustering algorithm, feature analysis and Laplace distribution. Then, the segmentation is achieved by the visual mechanism and the Markov random field. Different satellites remote sensing images are adopted as the experimental data, and the segmentation results demonstrate the proposed method have good performance in high resolution remote sensing images.

  1. Low-cost, smartphone based frequency doubling technology visual field testing using virtual reality (Conference Presentation)

    Science.gov (United States)

    Alawa, Karam A.; Sayed, Mohamed; Arboleda, Alejandro; Durkee, Heather A.; Aguilar, Mariela C.; Lee, Richard K.

    2017-02-01

    Glaucoma is the leading cause of irreversible blindness worldwide. Due to its wide prevalence, effective screening tools are necessary. The purpose of this project is to design and evaluate a system that enables portable, cost effective, smartphone based visual field screening based on frequency doubling technology. The system is comprised of an Android smartphone to display frequency doubling stimuli and handle processing, a Bluetooth remote for user input, and a virtual reality headset to simulate the exam. The LG Nexus 5 smartphone and BoboVR Z3 virtual reality headset were used for their screen size and lens configuration, respectively. The system is capable of running the C-20, N-30, 24-2, and 30-2 testing patterns. Unlike the existing system, the smartphone FDT tests both eyes concurrently by showing the same background to both eyes but only displaying the stimulus to one eye at a time. Both the Humphrey Zeiss FDT and the smartphone FDT were tested on five subjects without a history of ocular disease with the C-20 testing pattern. The smartphone FDT successfully produced frequency doubling stimuli at the correct spatial and temporal frequency. Subjects could not tell which eye was being tested. All five subjects preferred the smartphone FDT to the Humphrey Zeiss FDT due to comfort and ease of use. The smartphone FDT is a low-cost, portable visual field screening device that can be used as a screening tool for glaucoma.

  2. An eye movement study on the role of the visual field defect in pure alexia.

    Directory of Open Access Journals (Sweden)

    Tobias Bormann

    Full Text Available Pure alexia is a severe impairment of word reading which is usually accompanied by a right-sided visual field defect. Patients with pure alexia exhibit better preserved writing and a considerable word length effect, claimed to result from a serial letter processing strategy. Two experiments compared the eye movements of four patients with pure alexia to controls with simulated visual field defects (sVFD when reading single words. Besides differences in response times and differential effects of word length on word reading in both groups, fixation durations and the occurrence of a serial, letter-by-letter fixation strategy were investigated. The analyses revealed quantitative and qualitative differences between pure alexic patients and unimpaired individuals reading with sVFD. The patients with pure alexia read words slower and exhibited more fixations. The serial, letter-by-letter fixation strategy was observed only in the patients but not in the controls with sVFD. It is argued that the VFD does not cause pure alexic reading.

  3. The optomotor response of the praying mantis is driven predominantly by the central visual field.

    Science.gov (United States)

    Nityananda, Vivek; Tarawneh, Ghaith; Errington, Steven; Serrano-Pedraza, Ignacio; Read, Jenny

    2017-01-01

    The optomotor response has been widely used to investigate insect sensitivity to contrast and motion. Several studies have revealed the sensitivity of this response to frequency and contrast, but we know less about the spatial integration underlying this response. Specifically, few studies have investigated how the horizontal angular extent of stimuli influences the optomotor response. We presented mantises with moving gratings of varying horizontal extents at three different contrasts in the central or peripheral regions of their visual fields. We assessed the relative effectivity of different regions to elicit the optomotor response and modelled the dependency of the response on the angular extent subtended by stimuli at these different regions. Our results show that the optomotor response is governed by stimuli in the central visual field and not in the periphery. The model also shows that in the central region, the probability of response increases linearly with increase in horizontal extent up to a saturation point. Furthermore, the dependency of the optomotor response on the angular extent of the stimulus is modulated by contrast. We discuss the implications of our results for different modes of stimulus presentation and for models of the underlying mechanisms of motion detection in the mantis.

  4. Regional Relationship between Macular Retinal Thickness and Corresponding Central Visual Field Sensitivity in Glaucoma Patients

    Science.gov (United States)

    Wu, Shiu-Chen

    2017-01-01

    Purpose. To investigate the relationship between macular retinal thickness (MRT) and central visual field sensitivity (VFS) in patients with glaucoma. Methods. This retrospective study enrolled patients diagnosed with open-angle glaucoma. All study patients underwent Humphrey 10-2 visual field (VF) test and Spectralis spectral-domain optical coherence tomography (SD-OCT) exam for MRT measurement. Results. Sixty-eight eyes of 68 patients were examined. The correlation coefficients between VFS and MRT were 0.331 (P = 0.006) and 0.491 (P = 0.000) in the superior and inferior hemispheres, respectively. The average MRT in the eyes with abnormal 10-2 VF hemifields was significantly thinner than that in the eyes without abnormal hemifields in both hemispheres (P = 0.005 and 0.000 in the superior and inferior hemisphere, resp.). The average MRT values with an optimal sensitivity-specificity balance for discriminating the abnormal VF hemifield from the normal hemifield were 273.5 μm and 255.5 μm in the superior and inferior hemisphere, respectively. The area under the receiver operating characteristic curve was 0.701 in the superior hemisphere and 0.784 in the inferior hemisphere (both P MRT measured through SD-OCT was significantly correlated with central VFS. Lower MRT values might be a warning sign for central VF defects in glaucoma patients. PMID:28421139

  5. Stage II Chronic Maxillary Atelectasis Associated with Subclinical Visual Field Defect

    Directory of Open Access Journals (Sweden)

    Mangussi-Gomes, João

    2013-09-01

    Full Text Available Introduction: Chronic maxillary atelectasis (CMA is characterized by a persistent decrease in the maxillary sinus volume due to inward bowing of its walls. According to its severity, it may be classified into three clinical-radiological stages. Objective: To report a case of stage II CMA associated with subclinical visual field defect. Case Report: A 34-year-old woman presented with a 15-year history of recurrent episodes of sinusitis and intermittent right facial discomfort for the past 5 years. She denied visual complaints, and no facial deformities were observed on physical examination. Paranasal sinus computed tomography (CT demonstrated a completely opacified right maxillary sinus with inward bowing of its walls, suggesting the diagnosis of stage II CMA. A computerized campimetry (CC disclosed a scotoma adjacent to the blind spot of the right eye, indicating a possible damage to the optic nerve. The patient was submitted to functional endoscopic sinus surgery, with drainage of a thick mucous fluid from the sinus. She did well after surgery and has been asymptomatic since then. Postoperative CT was satisfactory and CC was normal. Discussion: CMA occurs because of a persistent ostiomeatal obstruction, which creates negative pressure inside the sinus. It is associated with nasosinusal symptoms but had never been described in association with any visual field defect. It can be divided into stage I (membranous deformity, stage II (bony deformity, and stage III (clinical deformity. The silent sinus syndrome is a special form of CMA. This term should only be used to describe those cases with spontaneous enophthalmos, hypoglobus, and/or midfacial deformity in the absence of nasosinusal symptoms.

  6. Is Seeing Believing? The Process of Change During Cognitive-behavioural Therapy for Distressing Visual Hallucinations.

    Science.gov (United States)

    Wilson, Rea; Collerton, Daniel; Freeston, Mark; Christodoulides, Thomas; Dudley, Robert

    2016-07-01

    People with psychosis often report distressing visual hallucinations (VH). In contrast to auditory hallucinations, there is little empirical evidence on effective interventions. The effectiveness of a novel-focused cognitive-behavioural therapy (CBT) intervention for VH was explored using a multiple baseline single case design with four participants. Change to individual appraisals, emotional and behavioural responses to VH were measured with daily diaries kept throughout the baseline and intervention phase lasting up to 16 sessions. Maintenance of change was tracked during a follow-up period of one month. Changes in appraisals, distress and response in accordance with the theory was evident in two out of four of the cases. However, change occurred within the baseline phase that limited the conclusions that change could be attributed to CBT alone. There was some evidence of clinically significant change and reliable change for two out of four of the cases at follow-up on one of the standardized psychiatric assessments. The research reported here has theoretical and clinical implications for refinement of the model and interventions for distressing VH. Copyright © 2015 John Wiley & Sons, Ltd. Distressing visual hallucinations (VH) are a relatively common symptom of psychosis. Visual hallucinations seem to be associated with greater impairment and disability. We have no specific treatment for VH. The appraisal of the visual experience and the behavioural response is important in maintaining the distress. Cognitive-behavioural therapy for VH at present has limited value. Copyright © 2015 John Wiley & Sons, Ltd.

  7. Cortical visual evoked potentials recorded after optic tract near field stimulation during GPi-DBS in non-cooperative patients.

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    Landi, Andrea; Pirillo, David; Cilia, Roberto; Antonini, Angelo; Sganzerla, Erik P

    2011-02-01

    Neurophysiologic monitoring during deep brain stimulation (DBS) interventions in the globus pallidus internum (Gpi) for the treatment of Parkinson's disease or primary dystonia is generally based upon microelectrode recordings (MER); moreover, MER request sophisticated technology and high level trained personnel for a reliable monitoring. Recordings of cortical visual evoked potentials (CVEPs) obtained after stimulation of the optic tract may be a potential option to MER; since optic tract lies just beneath the best target for Gpi DBS, changes in CVEPs during intraoperative exploration may drive a correct electrode positioning. Cortical VEPs from optic tract stimulation (OT C-CEPs) have been recorded in seven patients during GPi-DBS for the treatment of Parkinson's disease and primary dystonia under general sedation. OT C-VEPs were obtained after near-field monopolar stimulation of the optic tract; recording electrodes were at the scalp. Cortical responses after optic tract versus standard visual stimulation were compared. After intraoperative near-field OT stimulation a biphasic wave, named N40-P70, was detected in all cases. N40-P70 neither change in morphology nor in latency at different depths, but increased in amplitude approaching the optic tract. The electrode tip was positioned just 1mm above the point where OT-CVEPs showed the larger amplitude. No MERs were obtained in these patients; OT CVEPs were the only method to detect the Gpi before positioning the electrodes. OT CVEPs seem to be as reliable as MER to detail the optimal target in Gpi surgery: in addition they are less expensive, faster to perform and easier to decode. Copyright © 2010. Published by Elsevier B.V.

  8. Interactive terrain visualization enables virtual field work during rapid scientific response to the 2010 Haiti earthquake

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    Cowgill, Eric; Bernardin, Tony S.; Oskin, Michael E.; Bowles, Christopher; Yikilmaz, M. Burak; Kreylos, Oliver; Elliott, Austin J.; Bishop, Scott; Gold, Ryan D.; Morelan, Alexander; Bawden, Gerald W.; Hamann, Bernd; Kellogg, Louise

    2012-01-01

    The moment magnitude (Mw) 7.0 12 January 2010 Haiti earthquake is the first major earthquake for which a large-footprint LiDAR (light detection and ranging) survey was acquired within several weeks of the event. Here, we describe the use of virtual reality data visualization to analyze massive amounts (67 GB on disk) of multiresolution terrain data during the rapid scientific response to a major natural disaster. In particular, we describe a method for conducting virtual field work using both desktop computers and a 4-sided, 22 m3 CAVE immersive virtual reality environment, along with KeckCAVES (Keck Center for Active Visualization in the Earth Sciences) software tools LiDAR Viewer, to analyze LiDAR point-cloud data, and Crusta, for 2.5 dimensional surficial geologic mapping on a bare-earth digital elevation model. This system enabled virtual field work that yielded remote observations of the topographic expression of active faulting within an ∼75-km-long section of the eastern Enriquillo–Plantain Garden fault spanning the 2010 epicenter. Virtual field observations indicated that the geomorphic evidence of active faulting and ancient surface rupture varies along strike. Landform offsets of 6–50 m along the Enriquillo–Plantain Garden fault east of the 2010 epicenter and closest to Port-au-Prince attest to repeated recent surface-rupturing earthquakes there. In the west, the fault trace is well defined by displaced landforms, but it is not as clear as in the east. The 2010 epicenter is within a transition zone between these sections that extends from Grand Goâve in the west to Fayette in the east. Within this transition, between L'Acul (lat 72°40′W) and the Rouillone River (lat 72°35′W), the Enriquillo–Plantain Garden fault is undefined along an embayed low-relief range front, with little evidence of recent surface rupture. Based on the geometry of the eastern and western faults that show evidence of recent surface rupture, we propose that the 2010

  9. A tomographic visualization of electric discharge sound fields in atmospheric pressure plasma using laser diffraction

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    Nakamiya, Toshiyuki; Mitsugi, Fumiaki; Iwasaki, Yoichiro; Ikegami, Tomoaki; Tsuda, Ryoichi; Sonoda, Yoshito; Danuta Stryczewska, Henryka

    2013-02-01

    The phase modulation of transparent gas can be detected using Fraunhofer diffraction technique, which we call optical wave microphone (OWM). The OWM is suitable for the detection of sonic wave from audible sound to ultrasonic wave. Because this technique has no influence on sound field or electric field during the measurement, we have applied it to the sound detection for the electric discharges. There is almost no research paper that uses the discharge sound to examine the electrical discharge phenomenon. Two-dimensional visualization of the sound field using the OWM is also possible when the computerized tomography (CT) is combined. In this work, coplanar dielectric barrier discharge sin different gases of Ar, N2, He were characterized via the OWM as well as applied voltage and discharge current. This is the first report to investigate the influence of the type of the atmospheric gas on the two-dimensional sound field distribution for the coplanar dielectric barrier discharge using the OWM with CT. Contribution to the Topical Issue "13th International Symposium on High Pressure Low Temperature Plasma Chemistry (Hakone XIII)", Edited by Nicolas Gherardi, Henryca Danuta Stryczewska and Yvan Ségui.

  10. Receptive field properties of neurons in the primary visual cortex under photopic and scotopic lighting conditions.

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    Duffy, Kevin R; Hubel, David H

    2007-09-01

    Knowledge of the physiology of the primate visual cortex (area V-1) comes mostly from studies done in photopic conditions, in which retinal cones are active and rods play little or no part. Conflicting results have come from research into the effects of dark adaptation on receptive field organization of cells in the retina and the lateral geniculate nucleus. These studies claim either that the effect of the surround disappears with dark adaptation or that it does not. The current study has as its objective a comparison of responses of V-1 cells in awake-alert macaque monkeys under conditions of light and dark adaptation. We reasoned that basic receptive field properties of V-1 cells such as orientation selectivity, direction selectivity, and end-stopping should be preserved in scotopic conditions if the receptive field organization of antecedent cells is maintained in dim light. Our results indicate that dark adaptation does not alter basic V-1 receptive field characteristics such as selectivity for orientation, direction, and bar length.

  11. Early visual cortical structural changes in diabetic patients without diabetic retinopathy.

    Science.gov (United States)

    Ferreira, Fábio S; Pereira, João M S; Reis, Aldina; Sanches, Mafalda; Duarte, João V; Gomes, Leonor; Moreno, Carolina; Castelo-Branco, Miguel

    2017-11-01

    It is known that diabetic patients have changes in cortical morphometry as compared to controls, but it remains to be clarified whether the visual cortex is a disease target, even when diabetes complications such as retinopathy are absent. Therefore, we compared type 2 diabetes patients without diabetic retinopathy with control subjects using magnetic resonance imaging to assess visual cortical changes when retinal damage is not yet present. We performed T1-weighted imaging in 24 type 2 diabetes patients without diabetic retinopathy and 27 age- and gender-matched controls to compare gray matter changes in the occipital cortex between groups using voxel based morphometry. Patients without diabetic retinopathy showed reduced gray matter volume in the occipital lobe when compared with controls. Reduced gray matter volume in the occipital cortex was found in diabetic patients without retinal damage. We conclude that cortical early visual processing regions may be affected in diabetic patients even before retinal damage occurs.

  12. Feature Optimization for Long-Range Visual Homing in Changing Environments

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    Qidan Zhu

    2014-02-01

    Full Text Available This paper introduces a feature optimization method for robot long-range feature-based visual homing in changing environments. To cope with the changing environmental appearance, the optimization procedure is introduced to distinguish the most relevant features for feature-based visual homing, including the spatial distribution, selection and updating. In the previous research on feature-based visual homing, less effort has been spent on the way to improve the feature distribution to get uniformly distributed features, which are closely related to homing performance. This paper presents a modified feature extraction algorithm to decrease the influence of anisotropic feature distribution. In addition, the feature selection and updating mechanisms, which have hardly drawn any attention in the domain of feature-based visual homing, are crucial in improving homing accuracy and in maintaining the representation of changing environments. To verify the feasibility of the proposal, several comprehensive evaluations are conducted. The results indicate that the feature optimization method can find optimal feature sets for feature-based visual homing, and adapt the appearance representation to the changing environments as well.

  13. Negative body image associated with changes in the visual body appearance increases pain perception.

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    Osumi, Michihiro; Imai, Ryota; Ueta, Kozo; Nobusako, Satoshi; Morioka, Shu

    2014-01-01

    Changing the visual body appearance by use of as virtual reality system, funny mirror, or binocular glasses has been reported to be helpful in rehabilitation of pain. However, there are interindividual differences in the analgesic effect of changing the visual body image. We hypothesized that a negative body image associated with changing the visual body appearance causes interindividual differences in the analgesic effect although the relationship between the visual body appearance and analgesic effect has not been clarified. We investigated whether a negative body image associated with changes in the visual body appearance increased pain. Twenty-five healthy individuals participated in this study. To evoke a negative body image, we applied the method of rubber hand illusion. We created an "injured rubber hand" to evoke unpleasantness associated with pain, a "hairy rubber hand" to evoke unpleasantness associated with embarrassment, and a "twisted rubber hand" to evoke unpleasantness associated with deviation from the concept of normality. We also created a "normal rubber hand" as a control. The pain threshold was measured while the participant observed the rubber hand using a device that measured pain caused by thermal stimuli. Body ownership experiences were elicited by observation of the injured rubber hand and hairy rubber hand as well as the normal rubber hand. Participants felt more unpleasantness by observing the injured rubber hand and hairy rubber hand than the normal rubber hand and twisted rubber hand (pbody appearance associated with pain can increase pain sensitivity.

  14. Explicit behavioral detection of visual changes develops without their implicit neurophysiological detectability

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    Pessi eLyyra

    2012-03-01

    Full Text Available Change blindness is a failure of explicitly detecting changes between consecutively presented images when separated, e.g., by a brief blank screen. There is a growing body of evidence of implicit detection of even explicitly undetectable changes, pointing to the possibility of the implicit change detection as a prerequisite for its explicit counterpart. We recorded event-related potentials (ERPs of the electroencephalography in adults during an oddball-variant of change blindness flicker paradigm. In this variant, rare pictures with a change were interspersed with frequent pictures with no change. In separate stimulus blocks, the blank screen between the change and no-change picture was either of 100 ms or 500 ms in duration. In both stimulus conditions the participants eventually explicitly detect the changed pictures, the blank screen of the longer duration only requiring in average 10 % longer exposure to the picture series until the ability emerged. However, during the change blindness, ERPs were displaced towards negative polarity at 200–260 ms after the stimulus onset (visual mismatch negativity only with the blank screens of the shorter ISI. Our finding of ‘implicit change blindness’ for pictorial material that, nevertheless, successfully prepares the visual system for explicit change detection suggests that implicit change detection may not be a necessary condition for explicit change detection and that they may recruit at least partially distinct memory mechanisms.

  15. Early visual learning induces long-lasting connectivity changes during rest in the human brain.

    Science.gov (United States)

    Urner, Maren; Schwarzkopf, Dietrich Samuel; Friston, Karl; Rees, Geraint

    2013-08-15

    Spontaneous fluctuations in resting state activity can change in response to experience-dependent plasticity and learning. Visual learning is fast and can be elicited in an MRI scanner. Here, we showed that a random dot motion coherence task can be learned within one training session. While the task activated primarily visual and parietal brain areas, learning related changes in neural activity were observed in the hippocampus. Crucially, even this rapid learning affected resting state dynamics both immediately after the learning and 24h later. Specifically, the hippocampus changed its coupling with the striatum, in a way that was best explained as a consolidation of early learning related changes. Our findings suggest that long-lasting changes in neuronal coupling are accompanied by changes in resting state activity. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. Longitudinal changes in microperimetry and low luminance visual acuity in age-related macular degeneration.

    Science.gov (United States)

    Wu, Zhichao; Ayton, Lauren N; Luu, Chi D; Guymer, Robyn H

    2015-04-01

    There is a need for more sensitive measures of disease in intermediate age-related macular degeneration (AMD) to evaluate novel interventions more effectively and expediently. To determine if microperimetry and low luminance visual acuity can detect functional changes over a short duration of follow-up. Prospective longitudinal examination of 49 participants with consecutive AMD and 10 healthy participants in a research clinic from May 1, 2012, to December 31, 2013. Forty-one participants had intermediate AMD, 8 had nonfoveal geographic atrophy due to AMD. Participants underwent microperimetry examinations in 1 eye during a 12-month period at 6-month intervals for participants with AMD and at baseline and 12 months for control participants; low luminance visual acuity was performed at baseline and at 12 months for all participants. Changes in pathological features of intermediate AMD eyes were determined using side-by-side comparisons of color fundus photographs from the initial and final visit as remaining stable, progressed, or improved. Microperimetric sensitivity and low luminance visual acuity. A reduction in mean (SE) microperimetric pointwise sensitivity was identified at 12 months compared with the baseline for intermediate AMD eyes graded as stable (-0.31 dB [0.10 dB]; P = .003) or worsened (-0.42 dB [0.12 dB]; P visual acuity or low luminance visual acuity were identified in all groups over the 12-month period (P ≥ .07). Microperimetry detected subtle changes in visual function over a 12-month period in eyes with intermediate AMD but visual acuity measures did not identify any such changes. These findings suggest that microperimetry is worth exploring as a method for assessing the efficacy of novel interventions for intermediate AMD potentially requiring a shorter duration of follow-up.

  17. Visual attention measures predict pedestrian detection in central field loss: a pilot study.

    Directory of Open Access Journals (Sweden)

    Concetta F Alberti

    Full Text Available The ability of visually impaired people to deploy attention effectively to maximize use of their residual vision in dynamic situations is fundamental to safe mobility. We conducted a pilot study to evaluate whether tests of dynamic attention (multiple object tracking; MOT and static attention (Useful Field of View; UFOV were predictive of the ability of people with central field loss (CFL to detect pedestrian hazards in simulated driving.11 people with bilateral CFL (visual acuity 20/30-20/200 and 11 age-similar normally-sighted drivers participated. Dynamic and static attention were evaluated with brief, computer-based MOT and UFOV tasks, respectively. Dependent variables were the log speed threshold for 60% correct identification of targets (MOT and the increase in the presentation duration for 75% correct identification of a central target when a concurrent peripheral task was added (UFOV divided and selective attention subtests. Participants drove in a simulator and pressed the horn whenever they detected pedestrians that walked or ran toward the road. The dependent variable was the proportion of timely reactions (could have stopped in time to avoid a collision.UFOV and MOT performance of CFL participants was poorer than that of controls, and the proportion of timely reactions was also lower (worse (84% and 97%, respectively; p = 0.001. For CFL participants, higher proportions of timely reactions correlated significantly with higher (better MOT speed thresholds (r = 0.73, p = 0.01, with better performance on the UFOV divided and selective attention subtests (r = -0.66 and -0.62, respectively, p<0.04, with better contrast sensitivity scores (r = 0.54, p = 0.08 and smaller scotomas (r = -0.60, p = 0.05.Our results suggest that brief laboratory-based tests of visual attention may provide useful measures of functional visual ability of individuals with CFL relevant to more complex mobility tasks.

  18. Vision-related quality of life in first stroke patients with homonymous visual field defects

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    Sabel Bernhard A

    2010-03-01

    Full Text Available Abstract Background To evaluate vision-related and health-related quality of life (VRQoL, HRQoL in first stroke patients with homonymous visual field defects (VFD with respect to the extent of the lesion. Since VFD occur in approximately 10% of stroke patients the main purpose of the study was to investigate the additional impact of VFD in stroke patients hypothesizing that VFD causes diminished VRQoL. Methods In 177 first stroke patients with persisting VFD 2.5 years after posterior-parietal lesions VRQoL was assessed by the National-Eye-Institute-Visual-Functioning-Questionnaire (NEI-VFQ and HRQoL by the Medical-Outcome-Study Short-Form-36 Health-Survey (SF-36. Questionnaire results of VFD-patients were compared with age- and sex-matched healthy controls and with general non-selected stroke samples as published elsewhere. VFD-type and visual acuity were partially correlated with questionnaire results. Results Compared to healthy controls VFD-patients had lower NEI-VFQ scores except ocular pain (Z-range -11.34 to -3.35 and lower SF-36 scores except emotional role limitations (Z-range -7.21 to -3.34. VFD-patients were less impaired in SF-36 scores than general stroke patients one month post lesion (6/8 subscales but had lower SF-36 scores compared to stroke patients six months post lesion (5/8 subscales. Visual acuity significantly correlated with NEI-VFQ scores (r-range 0.27 to 0.48 and VFD-type with SF-36 mental subscales (r-range -0.26 to -0.36. Conclusions VFD-patients showed substantial reductions of VRQoL and HRQoL compared to healthy normals, but better HRQoL compared to stroke patients one month post lesion. VFD-patients (although their lesion age was four times higher had significantly lower HRQoL than a general stroke population at six months post-stroke. This indicates that the stroke-related subjective level of HRQoL impairment is significantly exacerbated by VFD. While VRQoL was primarily influenced by visual acuity, mental

  19. Multisensory Attention in Motion: Uninformative Sounds Increase the Detectability of Direction Changes of Moving Visual Stimuli

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    Durk Talsma

    2011-10-01

    Full Text Available It has recently been shown that spatially uninformative sounds can cause a visual stimulus to pop-out from an array of similar distractor stimuli when that sound is presented near simultaneously with a feature change in the visual stimulus. Until now, this effect has only been shown for stimuli that remain at a fixed position. Here we extend these results by showing that auditory stimuli can also improve the detectability of visual stimulus features related to motion. To accomplish this we presented moving visual stimuli (small dots on a computer screen. At a random moment during a trial, one of these stimuli could abruptly start moving in an orthogonal direction. Participants' task was to indicate whether such a change in direction had occurred or not by making a corresponding button press. When a sound (a short 1000Hz tone pip was presented simultaneously with a motion change, participants were able to detect this motion direction change among a significantly higher number of distractor stimuli, compared to when the sound was absent. When the number of distractor stimuli was kept constant, detection accuracy was significantly higher when the tone was present, compared to when it was absent. Using signal detection theory, we determined that this change in accuracy was reflected in an increase in d“, while we found no evidence to suggest that participants' response bias (as reflected nearly equal beta parameters, changed due to the presence of the sounds.

  20. Relationship between Visual Dysfunction and Retinal Changes in Patients with Multiple Sclerosis.

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    Maria Satue

    Full Text Available To evaluate structural changes in the retina and their correlation with visual dysfunction in patients with multiple sclerosis.Patients with multiple sclerosis (n = 84 and healthy controls (n = 84 underwent structural evaluation of the retinal nerve fiber layer, and macular and ganglion cell layer thicknesses using Spectral domain optical coherence tomography (SD-OCT. All subjects underwent high and low contrast visual acuity, color vision (using the Farnsworth and L´Anthony desaturated D15 color tests, and contrast sensitivity vision using the Pelli Robson chart and CSV 1000E test.Macular, retinal nerve fiber layer, and ganglion cell layer thinning was observed in multiple sclerosis patients compared to healthy controls (p<0.05. High- and low-contrast visual acuity and contrast sensitivity vision at four different spatial frequencies were significantly reduced in comparison with healthy subjects (p<0.05. Macular, retinal nerve fiber layer and ganglion cell layer measurements correlated with high and low contrast visual acuity, and contrast sensitivity vision. Contrast sensitivity vision was the functional parameter that most strongly correlated with the structural measurements in multiple sclerosis and was associated with ganglion cell layer measurements. The L´Anthony color vision score (age-corrected color confusion index was associated with macular measurements.Patients with multiple sclerosis had visual dysfunction that correlated with structural changes evaluated by SD-OCT. Macular and ganglion cell layer measurements may be good indicators of visual impairment in multiple sclerosis patients.

  1. Precision Analysis of Visual Odometry Based on Disparity Changing

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    Fu, C. Y.; Tsay, J. R.

    2017-08-01

    This thesis aims to analyze the precision of Position and orientation of cameras on Mobile Mapping System (MMS) determined by disparity based VO (DBVO). Dual forwards taken cameras on MMS are applied to obtain a sequence of stereo pairs. The Interior Orientation Parameters (IOPs) and Relative Orientation Parameters (ROPs) are derived in advance. The pose estimation is achieved by DBVO without additional control data. The procedure of DBVO consists of four steps. First up, keypoint detection and matching is conducted to obtain tie points in consecutive images. Then, image rectification is implemented to transform tie points into epipolar image space. Next, parallax equation is applied to estimate the 3D coordinates of interest points in epipolar image 3D space. Since their image points have different disparity in neighboring stereo pairs, the 3D coordinates of interest points in neighboring pairs are different as well. Finally, 3D conformal transformation is employed to derive the transformation parameters between neighboring pairs according to changing of coordinates of interest points. The posteriori STDs are adopted to assess the quality of transformation. Besides, check data of ground trajectory derived by photo triangulation are applied to evaluate the result. The relative errors of horizontal and vertical translations derived by DBVO are 2 % and 3 % in non-viewing direction. However, the translation in viewing direction and three rotation angles derived by DBVO have significant systematic errors about 1 m, 3°, 3° and 10° respectively. The influence of error propagation is not significant according to the chart of error distance ratio. In open area, the trajectory of INS/GPS is similar to ground truth, while the trajectory derived by DBVO has 44 % relative error. In residential district, the trajectory derived by INS/GPS has drift error about 2 m, while the relative error of the trajectory derived by DBVO decreases to 38 %. It is presumed that

  2. Scanning laser polarimetry, but not optical coherence tomography predicts permanent visual field loss in acute nonarteritic anterior ischemic optic neuropathy.

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    Kupersmith, Mark J; Anderson, Susan; Durbin, Mary; Kardon, Randy

    2013-08-15

    Scanning laser polarimetry (SLP) reveals abnormal retardance of birefringence in locations of the edematous peripapillary retinal nerve fiber layer (RNFL), which appear thickened by optical coherence tomography (OCT), in nonarteritic anterior ischemic optic neuropathy (NAION). We hypothesize initial sector SLP RNFL abnormalities will correlate with long-term regional visual field loss due to ischemic injury. We prospectively performed automated perimetry, SLP, and high definition OCT (HD-OCT) of the RNFL in 25 eyes with acute NAION. We grouped visual field threshold and RNFL values into Garway-Heath inferior/superior disc sectors and corresponding superior/inferior field regions. We compared sector SLP RNFL thickness with corresponding visual field values at presentation and at >3 months. At presentation, 12 eyes had superior sector SLP reduction, 11 of which had inferior field loss. Six eyes, all with superior field loss, had inferior sector SLP reduction. No eyes had reduced OCT-derived RNFL acutely. Eyes with abnormal field regions had corresponding SLP sectors thinner (P = 0.003) than for sectors with normal field regions. During the acute phase, the SLP-derived sector correlated with presentation (r = 0.59, P = 0.02) and with >3-month after presentation (r = 0.44, P = 0.02) corresponding superior and inferior field thresholds. Abnormal RNFL birefringence occurs in sectors corresponding to regional visual field loss during acute NAION when OCT-derived RNFL shows thickening. Since the visual field deficits show no significant recovery, SLP can be an early marker for axonal injury, which may be used to assess recovery potential at RNFL locations with respect to new treatments for acute NAION.

  3. Design and implementation of visualization methods for the CHANGES Spatial Decision Support System

    Science.gov (United States)

    Cristal, Irina; van Westen, Cees; Bakker, Wim; Greiving, Stefan

    2014-05-01

    The CHANGES Spatial Decision Support System (SDSS) is a web-based system aimed for risk assessment and the evaluation of optimal risk reduction alternatives at local level as a decision support tool in long-term natural risk management. The SDSS use multidimensional information, integrating thematic, spatial, temporal and documentary data. The role of visualization in this context becomes of vital importance for efficiently representing each dimension. This multidimensional aspect of the required for the system risk information, combined with the diversity of the end-users imposes the use of sophisticated visualization methods and tools. The key goal of the present work is to exploit efficiently the large amount of data in relation to the needs of the end-user, utilizing proper visualization techniques. Three main tasks have been accomplished for this purpose: categorization of the end-users, the definition of system's modules and the data definition. The graphical representation of the data and the visualization tools were designed to be relevant to the data type and the purpose of the analysis. Depending on the end-users category, each user should have access to different modules of the system and thus, to the proper visualization environment. The technologies used for the development of the visualization component combine the latest and most innovative open source JavaScript frameworks, such as OpenLayers 2.13.1, ExtJS 4 and GeoExt 2. Moreover, the model-view-controller (MVC) pattern is used in order to ensure flexibility of the system at the implementation level. Using the above technologies, the visualization techniques implemented so far offer interactive map navigation, querying and comparison tools. The map comparison tools are of great importance within the SDSS and include the following: swiping tool for comparison of different data of the same location; raster subtraction for comparison of the same phenomena varying in time; linked views for comparison

  4. Predictive Factors for Visual Field Conversion: Comparison of Scanning Laser Polarimetry and Optical Coherence Tomography.

    Science.gov (United States)

    Diekmann, Theresa; Schrems-Hoesl, Laura M; Mardin, Christian Y; Laemmer, Robert; Horn, Folkert K; E Kruse, Friedrich; Schrems, Wolfgang A

    2017-11-30

    The purpose of this study was to compare the ability of scanning laser polarimetry (SLP) and spectral-domain optical coherence tomography (SD-OCT) to predict future visual field conversion of subjects with ocular hypertension and early glaucoma. All patients were recruited from the Erlangen glaucoma registry and examined using standard automated perimetry, 24-hour intraocular pressure profile, and optic disc photography. Peripapillary retinal nerve fiber layer thickness (RNFL) measurements were obtained by SLP (GDx-VCC) and SD-OCT (Spectralis OCT). Positive and negative predictive values (PPV, NPV) were calculated for morphologic parameters of SLP and SD-OCT. Kaplan-Meier survival curves were plotted and log-rank tests were performed to compare the survival distributions. Contingency tables and Venn-diagrams were calculated to compare the predictive ability. The study included 207 patients-75 with ocular hypertension, 85 with early glaucoma, and 47 controls. Median follow-up was 4.5 years. A total of 29 patients (14.0%) developed visual field conversion during follow-up. SLP temporal-inferior RNFL [0.667; 95% confidence interval (CI), 0.281-0.935] and SD-OCT temporal-inferior RNFL (0.571; 95% CI, 0.317-0.802) achieved the highest PPV; nerve fiber indicator (0.923; 95% CI, 0.876-0.957) and SD-OCT mean (0.898; 95% CI, 0.847-0.937) achieved the highest NPV of all investigated parameters. The Kaplan-Meier curves confirmed significantly higher survival for subjects within normal limits of measurements of both devices (P<0.001). Venn diagrams tested with McNemar test statistics showed no significant difference for PPV (P=0.219) or NPV (P=0.678). Both GDx-VCC and SD-OCT demonstrate comparable results in predicting future visual field conversion if taking typical scans for GDx-VCC. In addition, the likelihood ratios suggest that GDx-VCC's nerve fiber indicator<30 may be the most useful parameter to confirm future nonconversion. (http://www.ClinicalTrials.gov number, NTC

  5. Disproportionate distribution of field potentials across the toad's tectal visual map in response to diffuse light ON and OFF stimulations.

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    Schwippert, W W; Beneke, T W; Ewert, J P

    1996-01-01

    In toads Bufo marinus and Bufo bufo spinosus, field potentials (FPs) were recorded from the surface of the optic tectum at different sites of the visual map in response to a sudden diffuse darkening (OFF) and lightening (ON) of the visual field of the contralateral eye. The OFF and ON responses were differently pronounced or even failed to occur. The latency of the former was significantly less than the one of the latter. FP amplitudes of the OFF and ON responses were strongest in the representation of a horizonto-superior anterio-lateral portion of the visual field and weakest toward the posterior field of vision. This phenomenon suggests various interpretations for subsequent experiments.

  6. Treatment of severe glaucomatous visual field deficit by chiropractic spinal manipulative therapy: a prospective case study and discussion.

    Science.gov (United States)

    Wingfield, B R; Gorman, R F

    2000-01-01

    To discuss the case of a patient with severely reduced visual fields arising from terminal glaucomatous retinal damage and the treatment of this condition by spinal manipulation. A 25-year-old uniocular female patient with congenital glaucoma sought chiropractic treatment for spinal pain, headache, and classic migraine. Advanced optic disk cupping was present, and loss of vision was near complete. A 3-degree island of central vision and a small area of peripheral light sensitivity had remained relatively stable for 3 years after a trabeculectomy procedure that had resulted in intraocular hypotony. It was considered possible that chiropractic spinal manipulative therapy may have a positive outcome in visual performance. Before commencing chiropractic spinal manipulative therapy, an ophthalmologic examination was performed, and visual performance was monitored through a course of treatment. Immediately after the first treatment, significant visual field improvement was recorded in the remaining eye. Maximal improvement of vision was achieved after 1 week (4 treatment sessions). Total monocular visual field had increased from approximately 2% to approximately 20% of normal. Corrected central acuity had improved from 6/12 to 6/9. Independent reexamination by the patient's regular ophthalmic surgeon confirmed the results. Recovery of vision in this patient was an unexpected and remarkable outcome, raising the question of whether chiropractic spinal manipulative therapy may be of value in the management of glaucomatous visual field loss. More intensive research is required.

  7. Flexibility in Visual Working Memory: Accurate Change Detection in the Face of Irrelevant Variations in Position.

    Science.gov (United States)

    Woodman, Geoffrey F; Vogel, Edward K; Luck, Steven J

    2012-01-13

    Many recent studies of visual working memory have used change-detection tasks in which subjects view sequential displays and are asked to report whether they are identical or if one object has changed. A key question is whether the memory system used to perform this task is sufficiently flexible to detect changes in object identity independent of spatial transformations, but previous research has yielded contradictory results. To address this issue, the present study compared standard change-detection tasks with tasks in which the objects varied in size or position between successive arrays. Performance was nearly identical across the standard and transformed tasks unless the task implicitly encouraged spatial encoding. These results resolve the discrepancies in prior studies and demonstrate that the visual working memory system can detect changes in object identity across spatial transformations.

  8. Change blindness in children with ADHD: a selective impairment in visual search?

    Science.gov (United States)

    Maccari, Lisa; Casagrande, Maria; Martella, Diana; Anolfo, Mariagrazia; Rosa, Caterina; Fuentes, Luis J; Pasini, Augusto

    2013-10-01

    This study evaluated change blindness and visual search efficiency in children with ADHD in searching for central and marginal changes. A total of 36 drug-naïve children (18 ADHD/18 controls) performed a flicker task that included changes in objects of central or marginal interest. The task required observers to search for a change until they detected it. Children with ADHD performed more slowly and less accurately than did typically developing children, specifically in detecting marginal-interest changes. In contrast to more standard visual search tasks, flicker tasks seem to be more sensitive to highlight focused attention deficits in children diagnosed with ADHD. Concretely, ADHD attentional deficits were more apparent when the task involved serial top-down strategies.

  9. Gaze patterns predicting successful collision avoidance in patients with homonymous visual field defects.

    Science.gov (United States)

    Papageorgiou, Eleni; Hardiess, Gregor; Mallot, Hanspeter A; Schiefer, Ulrich

    2012-07-15

    Aim of the present study was to identify efficient compensatory gaze patterns applied by patients with homonymous visual field defects (HVFDs) under virtual reality (VR) conditions in a dynamic collision avoidance task. Thirty patients with HVFDs due to vascular brain lesions and 30 normal subjects performed a collision avoidance task with moving objects at an intersection under two difficulty levels. Based on their performance (i.e. the number of collisions), patients were assigned to either an "adequate" (HVFD(A)) or "inadequate" (HVFD(I)) subgroup by the median split method. Eye and head tracking data were available for 14 patients and 19 normal subjects. Saccades, fixations, mean number of gaze shifts, scanpath length and the mean gaze eccentricity, were compared between HVFD(A), HVFD(I) patients and normal subjects. For both difficulty levels, the gaze patterns of HVFD(A) patients (N=5) compared to HVFD(I) patients (N=9) were characterized by longer saccadic amplitudes towards both the affected and the intact side, larger mean gaze eccentricity, more gaze shifts, longer scanpaths and more fixations on vehicles but fewer fixations on the intersection. Both patient groups displayed more fixations in the affected compared to the intact hemifield. Fixation number, fixation duration, scanpath length, and number of gaze shifts were similar between HVFD(A) patients and normal subjects. Patients with HVFDs who adapt successfully to their visual deficit, display distinct gaze patterns characterized by increased exploratory eye and head movements, particularly towards moving objects of interest on their blind side. In the context of a dynamic environment, efficient compensation in patients with HVFDs is possible by means of gaze scanning. This strategy allows continuous update of the moving objects' spatial location and selection of the task-relevant ones, which will be represented in visual working memory. Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. Changes in visual object recognition precede the shape bias in early noun learning

    Directory of Open Access Journals (Sweden)

    Meagan N Yee

    2012-12-01

    Full Text Available Two of the most formidable skills that characterize human beings are language and our prowess in visual object recognition. They may also be developmentally intertwined. Two experiments, a large sample cross-sectional study and a smaller sample 6-month longitudinal study of 18- 24 month olds tested a hypothesized developmental link between changes in the visual object representation and noun learning. Previous findings in visual object recognition indicate that children’s ability to recognize common basic level categories from sparse structural shape representations of object shape emerges between the ages of 18 and 24 months, is related to noun vocabulary size, and is lacking in children with language delay. Other research shows that in artificial noun learning tasks, during this same developmental period, young children systematically generalize object names by shape, that this shape bias predicts future noun learning, and is lacking in children with language delay. The two experiments examine the developmental relation between visual object recognition and the shape bias for the first time. The results show that developmental changes in visual object recognition systematically preceded the emergence of the shape bias. The results suggest a developmental pathway in which early changes in visual object recognition that are themselves linked to category learning enable the discovery of higher-order regularities in category structure and thus the shape bias in novel noun learning tasks. The proposed developmental pathway has implications for understanding the role of specific experience in the development of both visual object recognition and the shape bias in early noun learning.

  11. Changing visual perspective changes processing style: A distinct pathway by which imagery guides cognition.

    Science.gov (United States)

    Shaeffer, Eric M; Libby, Lisa K; Eibach, Richard P

    2015-06-01

    Action images can be depicted either from the actor's first-person or an observer's third-person visual perspective. This research demonstrates that visual perspective of action imagery influences the extent to which people process actions abstractly. Two experiments presented photographs of everyday actions, manipulating their visual perspective (first-person vs. third-person), holding constant the scope and objects depicted. Subsequently, participants interpreted actions unrelated to the images. Across both experiments, viewing third-person (vs. first-person) photographs caused participants to construe the unrelated actions more abstractly. This carryover effect demonstrates a shift in processing style, sheds light on an underlying mechanism of perspective effects, and suggests that imagery is a more versatile cognitive tool than traditionally assumed. (c) 2015 APA, all rights reserved).

  12. Period Changes of 23 Field RR Lyrae Stars

    Directory of Open Access Journals (Sweden)

    Soo-Chang Rey

    1994-12-01

    Full Text Available The secular period behavior of 23 field RR Lyrae stars is studied in order to determine if the observed period changes could be attributed, at least in the mean, to stellar evolution. The sample of stars is subdivided into two Oosterhoff groups based on the metallicity and period-shift. Despite the small sample size, we found a distinct bias toward positive period changes in the group variables. The period changes of the group variables in globular clusters. This provides yet another support for the Lee, Demarque, and Zinn(1990 evolutionary models of RR Lyrae stars and their explanation of the Sandage period-shift effect.

  13. The insulin-mediated modulation of visually evoked magnetic fields is reduced in obese subjects.

    Directory of Open Access Journals (Sweden)

    Martina Guthoff

    Full Text Available BACKGROUND: Insulin is an anorexigenic hormone that contributes to the termination of food intake in the postprandial state. An alteration in insulin action in the brain, named "cerebral insulin resistance", is responsible for overeating and the development of obesity. METHODOLOGY/PRINCIPAL FINDINGS: To analyze the direct effect of insulin on food-related neuronal activity we tested 10 lean and 10 obese subjects. We conducted a magnetencephalography study during a visual working memory task in both the basal state and after applying insulin or placebo spray intranasally to bypass the blood brain barrier. Food and non-food pictures were presented and subjects had to determine whether or not two consecutive pictures belonged to the same category. Intranasal insulin displayed no effect on blood glucose, insulin or C-peptide concentrations in the periphery; however, it led to an increase in the components of evoked fields related to identification and categorization of pictures (at around 170 ms post stimuli in the visual ventral stream in lean subjects when food pictures were presented. In contrast, insulin did not modulate food-related brain activity in obese subjects. CONCLUSIONS/SIGNIFICANCE: We demonstrated that intranasal insulin increases the cerebral processing of food pictures in lean whereas this was absent in obese subjects. This study further substantiates the presence of a "cerebral insulin resistance" in obese subjects and might be relevant in the pathogenesis of obesity.

  14. Visualization maps for the evolution of research hotspots in the field of regional health information networks.

    Science.gov (United States)

    Wang, Yanjun; Zheng, Jianzhong; Zhang, Ailian; Zhou, Wei; Dong, Haiyuan

    2017-04-11

    The aim of this study was to reveal research hotspots in the field of regional health information networks (RHINs) and use visualization techniques to explore their evolution over time and differences between countries. We conducted a literature review for a 50-year period and compared the prevalence of certain index terms during the periods 1963-1993 and 1994-2014 and in six countries. We applied keyword frequency analysis, keyword co-occurrence analysis, multidimensional scaling analysis, and network visualization technology. The total number of keywords was found to increase with time. From 1994 to 2014, the research priorities shifted from hospital planning to community health planning. The number of keywords reflecting information-based research increased. The density of the knowledge network increased significantly, and partial keywords condensed into knowledge groups. All six countries focus on keywords including Information Systems; Telemedicine; Information Service; Medical Records Systems, Computerized; Internet; etc.; however, the level of development and some research priorities are different. RHIN research has generally increased in popularity over the past 50 years. The research hotspots are evolving and are at different levels of development in different countries. Knowledge network mapping and perceptual maps provide useful information for scholars, managers, and policy-makers.

  15. Millisecond Coupling of Local Field Potentials to Synaptic Currents in the Awake Visual Cortex.

    Science.gov (United States)

    Haider, Bilal; Schulz, David P A; Häusser, Michael; Carandini, Matteo

    2016-04-06

    The cortical local field potential (LFP) is a common measure of population activity, but its relationship to synaptic activity in individual neurons is not fully established. This relationship has been typically studied during anesthesia and is obscured by shared slow fluctuations. Here, we used patch-clamp recordings in visual cortex of anesthetized and awake mice to measure intracellular activity; we then applied a simple method to reveal its coupling to the simultaneously recorded LFP. LFP predicted membrane potential as accurately as synaptic currents, indicating a major role for synaptic currents in the relationship between cortical LFP and intracellular activity. During anesthesia, cortical LFP predicted excitation far better than inhibition; during wakefulness, it predicted them equally well, and visual stimulation further enhanced predictions of inhibition. These findings reveal a central role for synaptic currents, and especially inhibition, in the relationship between the subthreshold activity of individual neurons and the cortical LFP during wakefulness. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  16. Improved visualization of vertebrate nuclear pore complexes by field emission scanning electron microscopy.

    Science.gov (United States)

    Shaulov, Lihi; Harel, Amnon

    2012-03-07

    Field emission scanning electron microscopy (FESEM) can provide high-resolution three-dimensional surface imaging of many biological structures, including nuclear envelopes and nuclear pore complexes (NPCs). For this purpose, it is important to preserve NPCs as close as possible to their native morphology, embedded in undamaged nuclear membranes. We present optimized methodologies for FESEM imaging in a cell-free reconstitution system and for the direct visualization of mammalian cell nuclei. The use of anchored chromatin templates in the cell-free system is particularly advantageous for imaging fragile intermediates inhibited at early stages of assembly. Our new method for exposing the surface of mammalian nuclei results in an unprecedented quality of NPC images, avoiding detergent-induced and physical damage. These new methodologies pave the way for the combined use of FESEM imaging with biochemical and genetic manipulation, in cell-free systems and in mammalian cells. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Spatial frequency tuning functions and contrast sensitivity at different eccentricities in the visual field

    Energy Technology Data Exchange (ETDEWEB)

    Chen, H.W.; Aine, C.J.; Flynn, E.R.; Wood, C.C.

    1996-07-01

    The human luminance spatial frequency contrast sensitivity function (CSF) has been well studied using psychophysical measurements by detecting spatial frequency (SF) grating patterns at threshold. Threshold CSFs at different eccentricities have proven to be quite useful in both basic and clinical vision research. However, near threshold, the CSF is measured at a linear area of the saturating contrast-response curve. In contrast, most of our everyday vision may be at suprathreshold levels, and thus may function most of the time at the nonlinear area of the contrast-response curve. In this study, in order to better characterize the CSF at normal contrast levels, we measured the SF tuning functions as well as the CR functions at different suprathreshold contrast levels and different eccentricities of the visual field using noninvasive MEG techniques. In this study, in addition to peak analysis, we have developed more reliable averaged power analysis methods where the average power can be calculated from the entire waveforms.

  18. Preschool Teaching Staff’s Opinions on the Importance of Preschool Curricular Fields of Activities, Art Genres and Visual Arts Fields

    Directory of Open Access Journals (Sweden)

    Tomaž Zupančič

    2015-12-01

    Full Text Available This article presents preschool teachers’ and assistant teachers’ opinions on the importance of selected fields of educational work in kindergartens. The article first highlights the importance of activities expressing artistic creativity within modern curriculums. Then, it presents an empirical study that examines the preschool teachers’ and assistant teachers’ opinions on the importance of the educational fields, art genres, and visual arts fields. In research hypotheses, we presumed that preschool teachers find individual educational fields, individual art genres, and individual visual arts activities to be of different importance; consequently, education in kindergarten does not achieve the requisite holism. The study is based on the descriptive and causal-non-experimental method. We have determined that the greatest importance is attributed to movement and language, followed by nature, society, art and mathematics. Within art genres, the greatest importance is attributed to visual arts and music and the least to audio-visual activities. Within visual arts, drawing and painting are considered to be the most important and sculpting the least. These findings can support future studies and deliberation on the possible effects on practice in terms of requisitely holistically planned preschool education.

  19. Regional cosmic ray induced ionization and geomagnetic field changes

    Directory of Open Access Journals (Sweden)

    G. A. Kovaltsov

    2007-08-01

    Full Text Available Cosmic ray induced ionization (CRII is an important factor of outer space influences on atmospheric properties. Variations of CRII are caused by two different processes – solar activity variations, which modulate the cosmic ray flux in interplanetary space, and changes of the geomagnetic field, which affects the cosmic ray access to Earth. Migration of the geomagnetic dipole axis may greatly alter CRII in some regions on a time scale of centuries and longer. Here we present a study of CRII regional effects of the geomagnetic field changes during the last millennium for two regions: Europe and the Far East. We show that regional effects of the migration of the geomagnetic dipole axis may overcome global changes due to solar activity variations.

  20. New techniques for the scientific visualization of three-dimensional multi-variate and vector fields

    Energy Technology Data Exchange (ETDEWEB)

    Crawfis, Roger A. [Univ. of California, Davis, CA (United States)

    1995-10-01

    Volume rendering allows us to represent a density cloud with ideal properties (single scattering, no self-shadowing, etc.). Scientific visualization utilizes this technique by mapping an abstract variable or property in a computer simulation to a synthetic density cloud. This thesis extends volume rendering from its limitation of isotropic density clouds to anisotropic and/or noisy density clouds. Design aspects of these techniques are discussed that aid in the comprehension of scientific information. Anisotropic volume rendering is used to represent vector based quantities in scientific visualization. Velocity and vorticity in a fluid flow, electric and magnetic waves in an electromagnetic simulation, and blood flow within the body are examples of vector based information within a computer simulation or gathered from instrumentation. Understand these fields can be crucial to understanding the overall physics or physiology. Three techniques for representing three-dimensional vector fields are presented: Line Bundles, Textured Splats and Hair Splats. These techniques are aimed at providing a high-level (qualitative) overview of the flows, offering the user a substantial amount of information with a single image or animation. Non-homogenous volume rendering is used to represent multiple variables. Computer simulations can typically have over thirty variables, which describe properties whose understanding are useful to the scientist. Trying to understand each of these separately can be time consuming. Trying to understand any cause and effect relationships between different variables can be impossible. NoiseSplats is introduced to represent two or more properties in a single volume rendering of the data. This technique is also aimed at providing a qualitative overview of the flows.

  1. Informative features of local field potential signals in primary visual cortex during natural image stimulation.

    Science.gov (United States)

    Seyedhosseini, Mojtaba; Shushruth, S; Davis, Tyler; Ichida, Jennifer M; House, Paul A; Greger, Bradley; Angelucci, Alessandra; Tasdizen, Tolga

    2015-03-01

    The local field potential (LFP) is of growing importance in neurophysiology as a metric of network activity and as a readout signal for use in brain-machine interfaces. However, there are uncertainties regarding the kind and visual field extent of information carried by LFP signals, as well as the specific features of the LFP signal conveying such information, especially under naturalistic conditions. To address these questions, we recorded LFP responses to natural images in V1 of awake and anesthetized macaques using Utah multielectrode arrays. First, we have shown that it is possible to identify presented natural images from the LFP responses they evoke using trained Gabor wavelet (GW) models. Because GW models were devised to explain the spiking responses of V1 cells, this finding suggests that local spiking activity and LFPs (thought to reflect primarily local synaptic activity) carry similar visual information. Second, models trained on scalar metrics, such as the evoked LFP response range, provide robust image identification, supporting the informative nature of even simple LFP features. Third, image identification is robust only for the first 300 ms following image presentation, and image information is not restricted to any of the spectral bands. This suggests that the short-latency broadband LFP response carries most information during natural scene viewing. Finally, best image identification was achieved by GW models incorporating information at the scale of ∼ 0.5° in size and trained using four different orientations. This suggests that during natural image viewing, LFPs carry stimulus-specific information at spatial scales corresponding to few orientation columns in macaque V1. Copyright © 2015 the American Physiological Society.

  2. Unsupervised Gaussian Mixture-Model With Expectation Maximization for Detecting Glaucomatous Progression in Standard Automated Perimetry Visual Fields.

    Science.gov (United States)

    Yousefi, Siamak; Balasubramanian, Madhusudhanan; Goldbaum, Michael H; Medeiros, Felipe A; Zangwill, Linda M; Weinreb, Robert N; Liebmann, Jeffrey M; Girkin, Christopher A; Bowd, Christopher

    2016-05-01

    To validate Gaussian mixture-model with expectation maximization (GEM) and variational Bayesian independent component analysis mixture-models (VIM) for detecting glaucomatous progression along visual field (VF) defect patterns (GEM-progression of patterns (POP) and VIM-POP). To compare GEM-POP and VIM-POP with other methods. GEM and VIM models separated cross-sectional abnormal VFs from 859 eyes and normal VFs from 1117 eyes into abnormal and normal clusters. Clusters were decomposed into independent axes. The confidence limit (CL) of stability was established for each axis with a set of 84 stable eyes. Sensitivity for detecting progression was assessed in a sample of 83 eyes with known progressive glaucomatous optic neuropathy (PGON). Eyes were classified as progressed if any defect pattern progressed beyond the CL of stability. Performance of GEM-POP and VIM-POP was compared to point-wise linear regression (PLR), permutation analysis of PLR (PoPLR), and linear regression (LR) of mean deviation (MD), and visual field index (VFI). Sensitivity and specificity for detecting glaucomatous VFs were 89.9% and 93.8%, respectively, for GEM and 93.0% and 97.0%, respectively, for VIM. Receiver operating characteristic (ROC) curve areas for classifying progressed eyes were 0.82 for VIM-POP, 0.86 for GEM-POP, 0.81 for PoPLR, 0.69 for LR of MD, and 0.76 for LR of VFI. GEM-POP was significantly more sensitive to PGON than PoPLR and linear regression of MD and VFI in our sample, while providing localized progression information. Detection of glaucomatous progression can be improved by assessing longitudinal changes in localized patterns of glaucomatous defect identified by unsupervised machine learning.

  3. Interactive 3D visualization of structural changes in the brain of a person with corticobasal syndrome

    Directory of Open Access Journals (Sweden)

    Claudia eHänel

    2014-05-01

    Full Text Available The visualization of the progression of brain tissue loss, which occurs in neurodegenerative diseases like corticobasal syndrome (CBS, is an important prerequisite to understand the course and the causes of this neurodegenerative disorder. Common workflows for visual analysis are often based on single 2D sections since in 3D visualizations more internally situated structures may be occluded by structures near the surface. The reduction of dimensions from 3D to 2D allows for an holistic view onto internal and external structures, but results in a loss of spatial information. Here, we present an application with two 3D visualization designs to resolve these challenges. First, in addition to the volume changes, the semi-transparent anatomy is displayed with an anatomical section and cortical areas for spatial orientation. Second, the principle of importance-driven volume rendering is adapted to give an unrestricted line-of-sight to relevant structures by means of a frustum-like cutout. To strengthen the benefits of the 3D visualization, we decided to provide the application next to standard desktop environments in immersive virtual environments with stereoscopic viewing as well. This improves the depth perception in general and in particular for the second design. Thus, the application presented in this work allows for aneasily comprehensible visual analysis of the extent of brain degeneration and the corresponding affected regions.

  4. Applying Theories and Interventions from Behavioral Medicine to Understand and Reduce Visual Field Variability in Patients with Vision Loss

    OpenAIRE

    Rozanski, Collin; Haythornthwaite, Jennifer A.; Dagnelie, Gislin; Bittner, Ava K.

    2014-01-01

    Visual field (VF) test results are often unreliable in visually impaired patients, but continue to be a cornerstone of clinical trials and play a vital role in clinical decision making since they are the primary method to determine patients’ functional vision loss or progression. Currently, patients are typically asked to perform VF tasks with minimal instruction or consideration of their psychological experience during the test. The gradual loss of vision due to retinal diseases, such as ret...

  5. Performance of an iPad Application to Detect Moderate and Advanced Visual Field Loss in Nepal.

    Science.gov (United States)

    Johnson, Chris A; Thapa, Suman; George Kong, Yu Xiang; Robin, Alan L

    2017-10-01

    To evaluate the accuracy and efficiency of Visual Fields Easy (VFE), a free iPad app, for performing suprathreshold perimetric screening. Prospective, cross-sectional validation study. We performed screening visual fields using a calibrated iPad 2 with the VFE application on 206 subjects (411 eyes): 210 normal (NL), 183 glaucoma (GL), and 18 diabetic retinopathy (DR) at Tilganga Institute of Ophthalmology, Kathmandu, Nepal. We correlated the results with a Humphrey Field Analyzer using 24-2 SITA Standard tests on 373 of these eyes (198 NL, 160 GL, 15 DR). The number of missed locations on the VFE correlated with mean deviation (MD, r = 0.79), pattern standard deviation (PSD, r = 0.60), and number of locations that were worse than the 95% confidence limits for total deviation (r = 0.51) and pattern deviation (r = 0.68) using SITA Standard. iPad suprathreshold perimetry was able to detect most visual field deficits with moderate (MD of -6 to -12 dB) and advanced (MD worse than -12 dB) loss, but had greater difficulty in detecting early (MD better than -6 dB) loss, primarily owing to an elevated false-positive response rate. The average time to perform the Visual Fields Easy test was 3 minutes, 18 seconds (standard deviation = 16.88 seconds). The Visual Fields Easy test procedure is a portable, fast, effective procedure for detecting moderate and advanced visual field loss. Improvements are currently underway to monitor eye and head tracking during testing, reduce testing time, improve performance, and eliminate the need to touch the video screen surface. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Evaluation of local field potential signals in decoding of visual attention.

    Science.gov (United States)

    Seif, Zahra; Daliri, Mohammad Reza

    2015-10-01

    In the field of brain research, attention as one of the main issues in cognitive neuroscience is an important mechanism to be studied. The complicated structure of the brain cannot process all the information it receives at any moment. Attention, in fact, is considered as a possible useful mechanism in which brain concentrates on the processing of important information which is required at any certain moment. The main goal of this study is decoding the location of visual attention from local field potential signals recorded from medial temporal (MT) area of a macaque monkey. To this end, feature extraction and feature selection are applied in both the time and the frequency domains. After applying feature extraction methods such as the short time Fourier transform, continuous wavelet transform (CWT), and wavelet energy (scalogram), feature selection methods are evaluated. Feature selection methods used here are T-test, Entropy, receiver operating characteristic, and Bhattacharyya. Subsequently, different classifiers are utilized in order to decode the location of visual attention. At last, the performances of the employed classifiers are compared. The results show that the maximum information about the visual attention in area MT exists in the low frequency features. Interestingly, low frequency features over all the time-axis and all of the frequency features at the initial time interval in the spectrogram domain contain the most valuable information related to the decoding of spatial attention. In the CWT and scalogram domains, this information exists in the low frequency features at the initial time interval. Furthermore, high performances are obtained for these features in both the time and the frequency domains. Among different employed classifiers, the best achieved performance which is about 84.5 % belongs to the K-nearest neighbor classifier combined with the T-test method for feature selection in the time domain. Additionally, the best achieved result (82

  7. "We grew as we grew": visual methods, social change and collective learning over time

    Directory of Open Access Journals (Sweden)

    Shannon Walsh

    2012-01-01

    Full Text Available Educational research using visual methods has the power to transform the society in which we live and the communities in which we work. We must not naively imagine that having the desire to make change in people's lives will mean that it will happen, as sometimes there may be surprising, unintended negative repercussions as well. Other constraints, such as structural violence and institutional racism, can also intersect with the possibility of making tangible change through educational research using visual methods. Qualitative assessment with a longitudinal approach is one approach that can reveal both the impact, and the limitations, of educational research on social change. I discuss these issues through grounded examples from an HIV educational project that used visual methodologies with a group of youths in Cape Town, South Africa over a number of years. Almost ten years later we interviewed three of theformer participants about what impact the work has had on their lives. Each has travelled a differentjourney and been faced with different constraints that have implications for the effectiveness of such work. Where are they now, and as adults, what do they have to say about the visual methodologies, memory, and social change?

  8. “We grew as we grew”: visual methods, social change and collective ...

    African Journals Online (AJOL)

    is one approach that can reveal both the impact, and the limitations, of educational research on social change. I discuss these issues through grounded examples from an HIV educational project that used visual methodologies with a group of youths in Cape Town, South Africa over a number of years. Almost ten years later ...

  9. Visual working memory and threat monitoring: Spider fearfuls show disorder-specific change detection

    NARCIS (Netherlands)

    Reinecke, A.; Becker, E.S.; Rinck, M.

    2010-01-01

    Previous studies of biased information processing in anxiety addressed biases of attention and memory, but little is known about the processes taking place between them: visual working memory (VWM) and monitoring of threat. We investigated these processes with a change detection paradigm. In

  10. Visualizing Nanocatalysts in Action from Color Change Reaction to Magnetic Recycling and Reuse

    Science.gov (United States)

    Hudson, Reuben; Bishop, Alexandra; Glaisher, Samuel; Katz, Jeffrey L.

    2015-01-01

    A demonstration to highlight the utility and ease of handling environmentally benign magnetically recoverable nanoparticle catalysts is described. The demonstration offers two powerful visuals. The first is a color change oxidation of tetramethylbenzidine by hydrogen peroxide catalyzed by Fe[subscript 3]O[subscript 4] nanoparticles. The second,…

  11. Measuring Change with Multiple Visual Analogue Scales: Application to Tense Arousal

    OpenAIRE

    Vautier, Stéphane

    2011-01-01

    International audience; Although the visual analogue scale (VAS) may be useful for measuring change on subjective and potentially transient phenomena, there is concern about the reliability and construct validity of the associated measurement variables. The present study reports evidence for tau-equivalence of change scores associated with VASs designed for assessing tense arousal with synonymous indicators. This psychometric property allows an estimation of the truescore structure of the cro...

  12. Effect of Ginkgo biloba on visual field and contrast sensitivity in Chinese patients with normal tension glaucoma: a randomized, crossover clinical trial.

    Science.gov (United States)

    Guo, Xinxing; Kong, Xiangbin; Huang, Rui; Jin, Ling; Ding, Xiaohu; He, Mingguang; Liu, Xing; Patel, Mehul Chimanlal; Congdon, Nathan G

    2014-01-07

    We evaluated the effect of ginkgo biloba extract on visual field defect and contrast sensitivity in a Chinese cohort with normal tension glaucoma. In this prospective, randomized, placebo-controlled crossover study, patients newly diagnosed with normal tension glaucoma, either in a tertiary glaucoma clinic (n = 5) or in a cohort undergoing routine general physical examinations in a primary care clinic (n = 30), underwent two 4-week phases of treatment, separated by a washout period of 8 weeks. Randomization determined whether ginkgo biloba extract (40 mg, 3 times per day) or placebo (identical-appearing tablets) was received first. Primary outcomes were change in contrast sensitivity and mean deviation on 24-2 SITA standard visual field testing, while secondary outcomes included IOP and self-reported adverse events. A total of 35 patients with mean age 63.7 (6.5) years were randomized to the ginkgo biloba extract-placebo (n = 18) or the placebo-ginkgo biloba extract (n = 17) sequence. A total of 28 patients (80.0%, 14 in each group) who completed testing did not differ at baseline in age, sex, visual field mean deviation, contrast sensitivity, IOP, or blood pressure. Changes in visual field and contrast sensitivity did not differ by treatment received or sequence (P > 0.2 for all). Power to have detected a difference in mean defect as large as previously reported was 80%. In contrast to some previous reports, ginkgo biloba extract treatment had no effect on mean defect or contrast sensitivity in this group of normal tension glaucoma patients. (http://www.chictr.org number, ChiCTR-TRC-08000724).

  13. Visual representation of knowledge in the field of Library and Information Science of IRAN

    Directory of Open Access Journals (Sweden)

    Afsoon Sabetpour

    2015-05-01

    Full Text Available Purpose: The present research has been done to visual representation of knowledge and determination vacuum and density points of scientific trends of faculty members of state universities of IRAN in Library & Information Science field. Method: Curriculum Vitae of each faculty member with census method were collected and its content analyzed. Then using a checklist, the rate scientific tendencies were extracted. NodeXL software was deployed to map out the levels. Results: The results showed that the trends are concentrated in Scientometrics, Research method in Library & Information Science, information organization, information resources, psychology, Education, Management, the Web, Knowledge management, Academic Libraries, Information services, Information Theories and collection management. Apparently, the Library & Information Science community of experts pays little or no attention to the Library & Information Science applications in the fields of chemistry, Cartography, museum, law, art, school libraries as well as to independent subject clusters such as minorities in library, information architecture, mentoring in library science, library automation, preservation, oral history, cybernetics, copyright, information marketing and information economy. Lack of efforts on these areas is remarkable.

  14. Communicating Climate Change through ICT-Based Visualization: Towards an Analytical Framework

    Directory of Open Access Journals (Sweden)

    Björn-Ola Linnér

    2013-11-01

    Full Text Available The difficulties in communicating climate change science to the general public are often highlighted as one of the hurdles for support of enhanced climate action. The advances of interactive visualization using information and communication technology (ICT are claimed to be a game-changer in our ability to communicate complex issues. However, new analytical frameworks are warranted to analyse the role of such technologies. This paper develops a novel framework for analyzing the content, form, context and relevance of ICT-based visualization of climate change, based on insights from literature on climate change communication. Thereafter, we exemplify the analytical framework by applying it to a pilot case of ICT-based climate visualization in a GeoDome. Possibilities to use affordable advanced ICT-based visualization devices in science and policy communication are rapidly expanding. We thus see wider implications and applications of the analytical framework not only for other ICT environments but also other issue areas in sustainability communication.

  15. Negative body image associated with changes in the visual body appearance increases pain perception.

    Directory of Open Access Journals (Sweden)

    Michihiro Osumi

    Full Text Available Changing the visual body appearance by use of as virtual reality system, funny mirror, or binocular glasses has been reported to be helpful in rehabilitation of pain. However, there are interindividual differences in the analgesic effect of changing the visual body image. We hypothesized that a negative body image associated with changing the visual body appearance causes interindividual differences in the analgesic effect although the relationship between the visual body appearance and analgesic effect has not been clarified. We investigated whether a negative body image associated with changes in the visual body appearance increased pain. Twenty-five healthy individuals participated in this study. To evoke a negative body image, we applied the method of rubber hand illusion. We created an "injured rubber hand" to evoke unpleasantness associated with pain, a "hairy rubber hand" to evoke unpleasantness associated with embarrassment, and a "twisted rubber hand" to evoke unpleasantness associated with deviation from the concept of normality. We also created a "normal rubber hand" as a control. The pain threshold was measured while the participant observed the rubber hand using a device that measured pain caused by thermal stimuli. Body ownership experiences were elicited by observation of the injured rubber hand and hairy rubber hand as well as the normal rubber hand. Participants felt more unpleasantness by observing the injured rubber hand and hairy rubber hand than the normal rubber hand and twisted rubber hand (p<0.001. The pain threshold was lower under the injured rubber hand condition than with the other conditions (p<0.001. We conclude that a negative body appearance associated with pain can increase pain sensitivity.

  16. Eye movements and reading in glaucoma: observations on patients with advanced visual field loss.

    Science.gov (United States)

    Burton, Robyn; Smith, Nicholas D; Crabb, David P

    2014-10-01

    To investigate the relationship between reading speed and eye movements in patients with advanced glaucomatous visual field (VF) defects and age-similar visually healthy people. Eighteen patients with advanced bilateral VF defects (mean age: 71, standard deviation [SD]: 7 years) and 39 controls (mean age: 67, SD: 8 years) had reading speed measured using short passages of text on a computer set-up incorporating eye tracking. Scanpaths were plotted and analysed from these experiments to derive measures of 'perceptual span' (total number of letters read per number of saccades) and 'text saturation' (the distance between the first and last fixation on lines of text). Another eye movement measure, termed 'saccadic frequency' (total number of saccades made to read a single word), was derived from a separate lexical decision task, where words were presented in isolation. Significant linear association was demonstrated between perceptual span and reading speed in patients (R (2) = 0.42) and controls (R (2) = 0.56). Linear association between saccadic frequency during the LDT and reading speed was also found in patients (R (2) = 0.42), but not in controls (R (2) = 0.02). Patients also exhibited greater average text saturation than controls (P = 0.004). Some, but not all, patients with advanced VF defects read slower than controls using short text passages. Differences in eye movement behaviour may partly account for this variability in patients. These patients were shown to saturate lines of text more during reading, which may explain previously-reported difficulties with sustained reading.

  17. Visual long-term memory and change blindness: Different effects of pre- and post-change information on one-shot change detection using meaningless geometric objects.

    Science.gov (United States)

    Nishiyama, Megumi; Kawaguchi, Jun

    2014-11-01

    To clarify the relationship between visual long-term memory (VLTM) and online visual processing, we investigated whether and how VLTM involuntarily affects the performance of a one-shot change detection task using images consisting of six meaningless geometric objects. In the study phase, participants observed pre-change (Experiment 1), post-change (Experiment 2), or both pre- and post-change (Experiment 3) images appearing in the subsequent change detection phase. In the change detection phase, one object always changed between pre- and post-change images and participants reported which object was changed. Results showed that VLTM of pre-change images enhanced the performance of change detection, while that of post-change images decreased accuracy. Prior exposure to both pre- and post-change images did not influence performance. These results indicate that pre-change information plays an important role in change detection, and that information in VLTM related to the current task does not always have a positive effect on performance. Copyright © 2014 Elsevier Inc. All rights reserved.

  18. The correlation between glaucomatous visual field loss and vision-related quality of life.

    Science.gov (United States)

    Orta, Asli Ö F; Öztürker, Zeynep K; Erkul, Sezin Ö; Bayraktar, Şükrü; Yilmaz, Omer F

    2015-01-01

    To evaluate the vision-related quality of life (QoL) of glaucoma patients in terms of the correlation between visual field (VF) loss and National Eye Institute Visual Functioning Questionnaire-39 (NEI VFQ-39) survey. A total of 244 glaucoma patients were examined with monocular Humphrey 24-2 central full threshold and Esterman binocular VF tests. Patients were grouped according to their monocular VFs done by Advanced Glaucoma Intervention Study (AGIS) classification and Esterman binocular VF efficiency scores. NEI VFQ-39 was applied for the evaluation of vision-related QoL. NEI VFQ-39 subscales and total scores were evaluated and the highest mean average values were in "color vision" (92.00±16.59) and "social functioning" (90.74±15.98). The lowest mean average values were in "general health" (54.76±18.86) and "general vision" (66.03±17.59). All the subscales except "general health" and "ocular pain" showed positive correlations with the monocular and Esterman binocular VF groupings. Pearson correlation analysis between NEI VFQ-39 subscales and the AGIS VF classification-based groups indicated that the subscales had statistically significant negative correlations except the "general health" (r=-0.151, P=0.018) and "ocular pain" (r=-0.048, P=0.455). The highest correlation with AGIS VF classification was in "driving" (r=-0.477, P=0.001) and "general vision" (r=-0.446, P=0.000) subscales. There was statistically significant correlation between NEI VFQ-39 subscales and Esterman binocular VF groups except "general health" (r=-0.064, P=0.318) and "ocular pain" (r=-0.062, P=0.337). The highest negative correlation was in "distant activities" (r=-0.522, P=0.000) and the lowest negative correlation was in "color vision" (r=-0.416, P=0.000) subscales. The highest correlation between binocular distant and binocular near-visual acuities was in "distant activities" and the lowest correlation was in "role difficulties" subscales. There is statistically significant

  19. The local and non-local components of the local field potential in awake primate visual cortex.

    Science.gov (United States)

    Gawne, Timothy J

    2010-12-01

    The Local Field Potential (LFP) is the analog signal recorded from a microelectrode inserted into cortex, typically in the frequency band of approximately 1 to 200 Hz. Here visual stimuli were flashed on in the receptive fields of primary visual cortical neurons in awake behaving macaques, and both isolated single units (neurons) and the LFP signal were recorded from the same unipolar microelectrode. The fall-off of single unit activity as a visual stimulus was moved from near the center to near the edge of the receptive field paralleled the fall-off of the stimulus-locked (evoked) LFP response. This suggests that the evoked LFP strongly reflects local neuronal activity. However, the evoked LFP could be significant even when the visual stimulus was completely outside the receptive field and the single unit response had fallen to zero, although this phenomenon was variable. Some of the non-local components of the LFP may be related to the slow distributed, or non-retinotopic, LFP signal previously observed in anesthetized animals. The induced (not time-locked to stimulus onset) component of the LFP showed significant increases only for stimuli within the receptive field of the single units. While the LFP primarily reflects local neuronal activity, it can also reflect neuronal activity at more distant sites, although these non-local components are typically more variable, slower, and weaker than the local components.

  20. Visualizing an Iterative, Dynamic Model for Improving Leadership-Employee Communication in the Organizational Change process

    DEFF Research Database (Denmark)

    Broillet, Alexandra; Barchilon, Marian; Kampf, Constance Elizabeth

    2012-01-01

    /user metaphor from the technical communication field. These perspectives broaden Change Management to include production and reception of messages about change through a link to 1) sensemaking, 2) Change Management ethos and 3) cultural resources for action available in the organization. We use a series...

  1. How do field of view and resolution affect the information content of panoramic scenes for visual navigation? A computational investigation.

    Science.gov (United States)

    Wystrach, Antoine; Dewar, Alex; Philippides, Andrew; Graham, Paul

    2016-02-01

    The visual systems of animals have to provide information to guide behaviour and the informational requirements of an animal's behavioural repertoire are often reflected in its sensory system. For insects, this is often evident in the optical array of the compound eye. One behaviour that insects share with many animals is the use of learnt visual information for navigation. As ants are expert visual navigators it may be that their vision is optimised for navigation. Here we take a computational approach in asking how the details of the optical array influence the informational content of scenes used in simple view matching strategies for orientation. We find that robust orientation is best achieved with low-resolution visual information and a large field of view, similar to the optical properties seen for many ant species. A lower resolution allows for a trade-off between specificity and generalisation for stored views. Additionally, our simulations show that orientation performance increases if different portions of the visual field are considered as discrete visual sensors, each giving an independent directional estimate. This suggests that ants might benefit by processing information from their two eyes independently.

  2. Visualization and other emerging technologies as change makers for oral cancer prevention.

    Science.gov (United States)

    Rosin, Miriam P; Poh, Catherine F; Guillard, Martial; Williams, P Michele; Zhang, Lewei; MacaUlay, Calum

    2007-03-01

    The genomic era has fueled a rapid emergence of new information at the molecular level with a great potential for developing innovative approaches to detection, risk assessment, and management of oral cancers and premalignant disease. As yet, however, little research has been done on complementary approaches that would use different technology in conjunction with molecular approaches to create a rapid and cost-effective strategy for patient assessment and management. In our ongoing 8-year longitudinal study, a set of innovative technologies is being validated alone and in combination to best correlate with patient outcome. The plan is to use these devices in a step-by-step sequence to guide key clinicopathological decisions on patient risk and treatment. The devices include a hand-held visualization device that makes use of tissue autofluorescence to detect and delineate abnormal lesions and fields requiring follow-up, to be used in conjunction with optical contrast agents such as toluidine blue. In addition, two semi-automated high-resolution computer microscopy systems will be used to quantitate the protein expression phenotype of cell nuclei in tissue sections and exfoliated cell brushings. Previously identified risk-associated molecular changes are being used to validate these systems as well as to establish their place in a population-based triage program that will filter out high-risk cases in the community and funnel them to dysplasia clinics where higher-cost molecular tools will guide intervention. A critical development for the translation of this technology into community settings is the establishment of an effective methodology for education and training of health practitioners on the front lines.

  3. Development of Window-based program for analysis and visualization of two-dimensional stress field in digital photoelasticity

    Directory of Open Access Journals (Sweden)

    Pichet Pinit

    2009-07-01

    Full Text Available This paper describes the development of a Window-based framework for analyzing and visualizing two-dimensional stress field in digital photoelasticity. The program is implemented as stand-alone software. The program contains mainly two parts: computational part and visual part supplemented with several image-processing functions. The computation method used in the program for retrieval of photoelastic parameters (isoclinic and isochromatic parameters is the phase stepping method. The visualization links between the results and the user by a gray scale or color map of such parameters, which is very convenient to the user for physical interpretation. With the Windows-based framework, additional modules eithercomputation or visualization can be simply added to the program.

  4. Relationship between Visual Dysfunction and Retinal Changes in Patients with Multiple Sclerosis.

    Science.gov (United States)

    Satue, Maria; Rodrigo, Maria Jesus; Otin, Sofia; Bambo, Maria Pilar; Fuertes, Maria Isabel; Ara, Jose Ramon; Martin, Jesus; Polo, Vicente; Larrosa, Jose Manuel; Pablo, Luis; Garcia-Martin, Elena

    2016-01-01

    To evaluate structural changes in the retina and their correlation with visual dysfunction in patients with multiple sclerosis. Patients with multiple sclerosis (n = 84) and healthy controls (n = 84) underwent structural evaluation of the retinal nerve fiber layer, and macular and ganglion cell layer thicknesses using Spectral domain optical coherence tomography (SD-OCT). All subjects underwent high and low contrast visual acuity, color vision (using the Farnsworth and L´Anthony desaturated D15 color tests), and contrast sensitivity vision using the Pelli Robson chart and CSV 1000E test. Macular, retinal nerve fiber layer, and ganglion cell layer thinning was observed in multiple sclerosis patients compared to healthy controls (pvision at four different spatial frequencies were significantly reduced in comparison with healthy subjects (pvision. Contrast sensitivity vision was the functional parameter that most strongly correlated with the structural measurements in multiple sclerosis and was associated with ganglion cell layer measurements. The L´Anthony color vision score (age-corrected color confusion index) was associated with macular measurements. Patients with multiple sclerosis had visual dysfunction that correlated with structural changes evaluated by SD-OCT. Macular and ganglion cell layer measurements may be good indicators of visual impairment in multiple sclerosis patients.

  5. Subtle changes in the landmark panorama disrupt visual navigation in a nocturnal bull ant.

    Science.gov (United States)

    Narendra, Ajay; Ramirez-Esquivel, Fiorella

    2017-04-05

    The ability of ants to navigate when the visual landmark information is altered has often been tested by creating large and artificial discrepancies in their visual environment. Here, we had an opportunity to slightly modify the natural visual environment around the nest of the nocturnal bull ant Myrmecia pyriformis We achieved this by felling three dead trees, two located along the typical route followed by the foragers of that particular nest and one in a direction perpendicular to their foraging direction. An image difference analysis showed that the change in the overall panorama following the removal of these trees was relatively little. We filmed the behaviour of ants close to the nest and tracked their entire paths, both before and after the trees were removed. We found that immediately after the trees were removed, ants walked slower and were less directed. Their foraging success decreased and they looked around more, including turning back to look towards the nest. We document how their behaviour changed over subsequent nights and discuss how the ants may detect and respond to a modified visual environment in the evening twilight period.This article is part of the themed issue 'Vision in dim light'. © 2017 The Author(s).

  6. Effect of Visual Angle on the Head Movement Caused by Changing Binocular Disparity

    Directory of Open Access Journals (Sweden)

    Toru Maekawa

    2011-10-01

    Full Text Available It has been shown that vertical binocular disparity has no or little effect on the perception of visual direction (Banks et al., 2002. On the other hand, our previous study has reported that a continuous change of vertical disparity causes an involuntary sway of the head (Maekawa et al., 2009. We predict that the difference between those results attributes to the dissociation between the processes for perception and action in the brain. The aim of this study is to investigate in more details the condition that influences the process of disparity information. The present experiment particularly varied the visual angle of stimulus presentation and measured the head movement and body sway caused by changing vertical disparity. Results showed that the head movement was greater as the visual angle of the stimulus was smaller. It has been reported that stimulus of only small visual angle affect depth perception (Erklens et al., 1995. Thus, our result suggests that perception and action produced by vertical disparity are consistent as far as the effect of the stimulus size is concerned.

  7. A cosmogenic radionuclide perspective on Holocene geomagnetic field changes in comparison to new geomagnetic field reconstructions

    Science.gov (United States)

    Muscheler, Raimund; Nilsson, Andreas; Suttie, Neil

    2017-04-01

    The solar and geomagnetic shielding modulates the spectrum of galactic cosmic rays reaching Earth. In the Earth's atmosphere galactic cosmic rays produce cosmogenic radionuclides that, therefore, provide the possibility to reconstruct the geomagnetic field intensity back into the past. Cosmogenic radionuclide records offer a complementary view on the history of the geomagnetic field since the cosmic ray shielding is mainly sensitive to the dipolar component of the Earth magnetic field. In addition, cosmogenic radionuclides records for the Holocene have a very high temporal resolution potentially allowing us to investigate rapid changes in the Earth's magnetic field. However, the solar influence and the geochemical behavior of cosmogenic radionuclides have to be accounted for when interpreting such records in terms of geomagnetic field changes. The solar component is usually expected to act on shorter time scales and, therefore, assumed to be of minor importance for the longer-term variations in cosmogenic radionuclide records. The geochemical component can be investigated by joint analysis of 10Be and 14C records that have a completely different geochemical behavior. The reliability of these approaches and the impact on the radionuclide-based geomagnetic field reconstructions will be discussed. In addition, we will compare cosmogenic radionuclide-based reconstructions to the output of state-of-the-art reconstructions of the geomagnetic dipole field based on lake sediments and archaeomagnetic data. The dipole moment in these models remains poorly constrained, but in combination with radionuclides, they allow us to put realistic bounds on the amplitude of Holocene dipole variations. We will show the agreements and disagreements and will discuss possible reasons for the observed differences.

  8. Visualization and Transparentization of the Structure and Stress Field of Aggregated Geomaterials Through 3D Printing and Photoelastic Techniques

    Science.gov (United States)

    Ju, Yang; Wang, Li; Xie, Heping; Ma, Guowei; Zheng, Zemin; Mao, Lingtao

    2017-06-01

    Natural resource reservoirs usually consist of heterogeneous aggregated geomaterials containing a large number of randomly distributed particles with irregular geometry. As a result, the accurate characterization of the stress field, which essentially governs the mechanical behaviour of such geomaterials, through analytical and experimental methods, is considerably difficult. Physical visualization of the stress field is a promising method to quantitatively characterize and reveal the evolution and distribution of stress in aggregated geomaterials subjected to excavation loads. This paper presents a novel integration of X-ray computed tomography (CT) imaging, three-dimensional (3D) printing, and photoelastic testing for the transparentization and visualization of the aggregated structure and stress field of heterogeneous geomaterials. In this study, a glutenite rock sample was analysed by CT to acquire the 3D aggregate structure, following which 3D printing was adopted to produce transparent models with the same aggregate structure as that of the glutenite sample. Uniaxial compression tests incorporated with photoelastic techniques were performed on the transparent models to acquire and visualize the stress distribution of the aggregated models at various loading stages. The effect of randomly distributed aggregates on the stress field characteristics of the models, occurrence of plastic zones, and fracture initiation was analysed. The stress field characteristics of the aggregated models were analysed using the finite element method (FEM). The failure process was simulated using the distinct element method (DEM). Both FEM and DEM results were compared with the experimental observations. The results showed that the proposed method can very well visualize the stress field of aggregated solids during uniaxial loading. The results of the visualization tests were in good agreement with those of the numerical simulations.

  9. Regional neural response differences in the determination of faces or houses positioned in a wide visual field.

    Science.gov (United States)

    Wang, Bin; Yan, Tianyi; Wu, Jinglong; Chen, Kewei; Imajyo, Satoshi; Ohno, Seiichiro; Kanazawa, Susumu

    2013-01-01

    In human visual cortex, the primary visual cortex (V1) is considered to be essential for visual information processing; the fusiform face area (FFA) and parahippocampal place area (PPA) are considered as face-selective region and places-selective region, respectively. Recently, a functional magnetic resonance imaging (fMRI) study showed that the neural activity ratios between V1 and FFA were constant as eccentricities increasing in central visual field. However, in wide visual field, the neural activity relationships between V1 and FFA or V1 and PPA are still unclear. In this work, using fMRI and wide-view present system, we tried to address this issue by measuring neural activities in V1, FFA and PPA for the images of faces and houses aligning in 4 eccentricities and 4 meridians. Then, we further calculated ratio relative to V1 (RRV1) as comparing the neural responses amplitudes in FFA or PPA with those in V1. We found V1, FFA, and PPA showed significant different neural activities to faces and houses in 3 dimensions of eccentricity, meridian, and region. Most importantly, the RRV1s in FFA and PPA also exhibited significant differences in 3 dimensions. In the dimension of eccentricity, both FFA and PPA showed smaller RRV1s at central position than those at peripheral positions. In meridian dimension, both FFA and PPA showed larger RRV1s at upper vertical positions than those at lower vertical positions. In the dimension of region, FFA had larger RRV1s than PPA. We proposed that these differential RRV1s indicated FFA and PPA might have different processing strategies for encoding the wide field visual information from V1. These different processing strategies might depend on the retinal position at which faces or houses are typically observed in daily life. We posited a role of experience in shaping the information processing strategies in the ventral visual cortex.

  10. Scattered depressions with temporal preponderance in visual field test coexisting with optic disc temporal atrophy in cerebral arteriovenous malformation

    Directory of Open Access Journals (Sweden)

    Gokce G

    2013-10-01

    Full Text Available Gokcen Gokce,1 Nisa Cem Oren,2 Osman Melih Ceylan,3 Tarkan Mumcuoglu,3 Volkan Hurmeric3 1Sarikamis Military Hospital, Department of Ophthalmology, 2Department of Radiology, Kars, 3Gulhane Military Medical Academy, Department of Ophthalmology, Ankara, Turkey Abstract: In this article, the unusual association of optic disc temporal atrophy associated with scattered depressions with temporal preponderance in visual field test resembling incomplete bitemporal hemianopsia is reported. A 22-year-old man with cerebral arteriovenous malformation (AVM, which was located adjacent to the inferomedial portion of the posterior limb of the right internal capsule at the level of lateral ventricle, revealed interesting and unexpected ophthalmological findings. Possible mechanisms including anatomical variant, previously larger AVM, and retrograde optic neuropathy were mentioned. This case also highlighted that the usual complaint of visual disturbance might associate with unusual visual field defect in cerebral AVMs. Keywords: arteriovenous malformation, bitemporal hemianopsia, optic chiasm, optic nerve, vascular steal

  11. Training compensatory viewing strategies : feasiblity and effect on practical fitness to drive in subjects with visual field defects

    NARCIS (Netherlands)

    Coeckelbergh, Tanja R.M.; Brouwer, Wiebo H.; Cornelissen, Frans W.; Kooijman, Aart C.

    2002-01-01

    Fifty-one subjects with visual field defects were trained to use compensatory viewing strategies.The subjects were referred to the training program by an official driving examiner of the Dutch Central Bureau of Driving Licenses. Three training programs were compared: laboratory training, mobility

  12. Visual Field x Response Hand Interactions and Level Priming in the Processing of Laterally Presented Hierarchical Stimuli

    Science.gov (United States)

    Wendt, Mike; Vietze, Ina; Kluwe, Rainer H.

    2007-01-01

    Hemisphere-specific processing of laterally presented global and local stimulus levels was investigated by (a) examining interactions between the visual field of stimulus presentation and the response hand and (b) comparing intra- with inter-hemispheric effects of level priming (i.e. faster and more accurate performance when the target level…

  13. Hemispheric Specialization for Language According to Grapho-Phonemic Transformation and Gender. A Divided Visual Field Experiment

    Science.gov (United States)

    Cousin, Emilie; Perrone, Marcela; Baciu, Monica

    2009-01-01

    This behavioral study aimed at assessing the effect of two variables on the degree of hemispheric specialization for language. One of them was the "grapho-phonemic translation (transformation)" (letter-sound mapping) and the other was the participants' "gender". The experiment was conducted with healthy volunteers. A divided visual field procedure…

  14. Risk Factors for Visual Field Progression in the Groningen Longitudinal Glaucoma Study : A Comparison of Different Statistical Approaches

    NARCIS (Netherlands)

    Wesselink, Christiaan; Marcus, Michael W.; Jansonius, Nomdo M.

    2012-01-01

    Purpose: To identify risk factors for visual field progression in glaucoma and to compare different statistical approaches with this risk factor analysis. Patients and Methods: We included 221 eyes of 221 patients. Progression was analyzed using Nonparametric Progression Analysis applied to Humphrey

  15. The frequency of occurrence, types, and characteristics of visual field defects in acquired brain injury: a retrospective analysis.

    Science.gov (United States)

    Suchoff, Irwin B; Kapoor, Neera; Ciuffreda, Kenneth J; Rutner, Daniella; Han, Esther; Craig, Shoshana

    2008-05-01

    The purpose of this retrospective study was to determine the frequency of occurrence of visual field defects in a sample of visually symptomatic, ambulatory outpatients who have acquired brain injury (ABI), either traumatic brain injury (TBI) or cerebral vascular accident (CVA). The medical records of 220 individuals with TBI (n=160) or CVA (n=60) were reviewed retrospectively. This was determined by a computer-based query spanning the years 2000 through 2003. The individuals' records were reviewed to determine the frequency of targeted visual field defects that were classified as scattered, restricted, homonymous, nonhomonymous, and visual neglect. The altitudinal and lateral characteristics of these defects were also determined. In the total ABI sample of 220, some 102 (46.36%) individuals had 1 of the targeted defects diagnosed. These defects were present in 62 (38.75%) of the TBI subgroup and in 40 (66.67%) of the CVA subgroup. The most frequent defects in the TBI group were scattered (58.06%) followed by homonymous (22.58%). In the CVA group, the most numerous were homonymous (47.5%), with scattered and nonhomonymous accounting for 20% each. The uniqueness of the current study is that it reports the frequency of occurrence of specified visual field defects in the total ABI sample and in the TBI and CVA subgroups. This enabled comparisons with other studies that generally have reported on just 1 of these groupings. The current results are in accord with most of the other studies that are reviewed. The findings of this study should alert the reader to the high frequency of occurrence of visual field defects in the ABI population, and make the reader aware of the adverse effects they can have on quality of life and rehabilitation.

  16. Influence of script direction on word processing modes in left and right visual fields.

    Science.gov (United States)

    Siéroff, Eric; Slama, Yael

    2017-11-15

    Word processing in left (LVF) and right (RVF) visual fields may be affected by left hemisphere activation during reading and by script direction. We evaluated the effect of script direction by presenting words in left-to-right (French) and right-to-left (Hebrew) scripts to bilingual French participants. Words of different lengths were presented in the LVF and the RVF in a naming task. Results showed (1) a stronger word length effect in the LVF than in the RVF in French, and no difference of word length effect between LVF and RVF in Hebrew; (2) a first-letter advantage only in the LVF in French and in the RVF in Hebrew, showing an effect of script direction on letter processing; and (3) a stronger advantage of external over internal letters in words presented in the LVF than in the RVF for both languages, showing a left hemisphere influence on letter activation. Thus, script direction and left hemisphere activation may affect different processes when reading words in LVF and RVF. Selective attention may orient and redistribute a processing "window" over the letter string according to script direction, and the modulation of attentional resources is influenced by left hemisphere activation.

  17. Effective visualization of stereo particle image velocimetry vector fields of a turbulent boundary layer

    Science.gov (United States)

    Longmire, E. K.; Ganapathisubramani, B.; Marusic, I.; Urness, T.; Interrante, V.

    2003-06-01

    Stereo particle image velocimetry datasets contain three-dimensional information over a plane, from which multiple quantities can be derived at each point. The task of visualizing these different parameters simultaneously is challenging, and this inhibits our ability to analyse and derive firm conclusions about the physics of the flow. Currently, the common approach is to view each parameter separately in different images. Such an approach is very inefficient, especially for large fields of view where many important structures and features co-exist. In this paper we discuss several ways in which the primary quantities can be viewed simultaneously in the same image. The simplest method is to use different colours for each parameter and to overlay all the different colours on one image. The limitations of such an approach will be described. Other methods considered involve using texture generated from a line integral convolution algorithm to convey instantaneous velocity direction and magnitude. Animated texture is also described, together with variants involving combined colour and out-of-plane height. The use of height in tandem with colour and animated texture is a useful method in distinguishing the different parameters in the regions of overlap.

  18. Natural, but not artificial, facial movements elicit the left visual field bias in infant face scanning

    Science.gov (United States)

    Xiao, Naiqi G.; Quinn, Paul C.; Wheeler, Andrea; Pascalis, Olivier; Lee, Kang

    2014-01-01

    A left visual field (LVF) bias has been consistently reported in eye movement patterns when adults look at face stimuli, which reflects hemispheric lateralization of face processing and eye movements. However, the emergence of the LVF attentional bias in infancy is less clear. The present study investigated the emergence and development of the LVF attentional bias in infants from 3 to 9 months of age with moving face stimuli. We specifically examined the naturalness of facial movements in infants’ LVF attentional bias by comparing eye movement patterns in naturally and artificially moving faces. Results showed that 3- to 5-month-olds exhibited the LVF attentional bias only in the lower half of naturally moving faces, but not in artificially moving faces. Six- to 9-month-olds showed the LVF attentional bias in both the lower and upper face halves only in naturally moving, but not in artificially moving faces. These results suggest that the LVF attentional bias for face processing may emerge around 3 months of age and is driven by natural facial movements. The LVF attentional bias reflects the role of natural face experience in real life situations that may drive the development of hemispheric lateralization of face processing in infancy. PMID:25064049

  19. Binocular correspondence and the range of fusible horizontal disparities in the central visual field.

    Science.gov (United States)

    Harrold, Ashleigh L; Grove, Philip M

    2015-01-01

    Binocular disparities underlie precise stereoscopic depth perception but only over a finite range. At large disparities, objects appear diplopic, and depth perception is degraded. Measurements of the range of horizontal disparities for which single vision is experienced have previously been restricted to the horizontal plane of regard. We extended these mappings, in two experiments, to the upper and lower visual fields and eccentric meridians. In Experiment 1, we measured empirical corresponding points and fusional limits at identical elevations in the median plane for 20 participants. We observed a vertical shear in binocular correspondence consistent with a backward inclined empirical vertical horopter and the fusional range centered upon it. In Experiment 2, we mapped the vertical horopter and fusional limits for a second set of elevations in the median plane and at two additional eccentricities and found a similar pattern of results as in Experiment 1. For 23 of 25 participants in this study, we found that the relationship between measurements of the vertical horopter and fusional range is similar to the established relationship between Panum's fusional range and the horizontal horopter. Our data replicate previous findings that the vertical horopter is inclined top back. We are the first to illustrate that the fusional range of horizontal disparities is approximately centered upon the vertical horopter in the median plane and along eccentric meridians.

  20. Comparison of Glaucoma Progression Detection by Optical Coherence Tomography and Visual Field.

    Science.gov (United States)

    Zhang, Xinbo; Dastiridou, Anna; Francis, Brian A; Tan, Ou; Varma, Rohit; Greenfield, David S; Schuman, Joel S; Huang, David

    2017-12-01

    To compare longitudinal glaucoma progression detection using optical coherence tomography (OCT) and visual field (VF). Validity assessment. We analyzed subjects with more than 4 semi-annual follow-up visits (every 6 months) in the multicenter Advanced Imaging for Glaucoma Study. Fourier-domain optical coherence tomography (OCT) was used to map the thickness of the peripapillary retinal nerve fiber layer (NFL) and ganglion cell complex (GCC). OCT-based progression detection was defined as a significant negative trend for either NFL or GCC. VF progression was reached if either the event or trend analysis reached significance. The analysis included 356 glaucoma suspect/preperimetric glaucoma (GS/PPG) eyes and 153 perimetric glaucoma (PG) eyes. Follow-up length was 54.1 ± 16.2 months for GS/PPG eyes and 56.7 ± 16.0 for PG eyes. Progression was detected in 62.1% of PG eyes and 59.8% of GS/PPG eyes by OCT, significantly (P glaucoma. While the utility of NFL declines in advanced glaucoma, GCC remains a sensitive progression detector from early to advanced stages. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Regional vascular density-visual field sensitivity relationship in glaucoma according to disease severity.

    Science.gov (United States)

    Shin, Joong Won; Lee, Jiyun; Kwon, Junki; Choi, Jaewan; Kook, Michael S

    2017-12-01

    To study whether there are global and regional relationships between peripapillary vascular density (pVD) assessed by optical coherence tomography angiography (OCT-A) and visual field (VF) mean sensitivity at different glaucoma stages. Microvascular images and peripapillary retinal nerve fibre layer (pRNFL) thicknesses were obtained using a Cirrus OCT-A device in 91 glaucoma subjects. The pVD was measured at various spatial locations according to the Garway-Heath map, using a MATLAB software (The MathWorks, Natick, Massachusetts). VF mean sensitivity (VFMS) was recorded in the 1/L scale. Global and regional vasculature-function (pVD vs VFMS) relationships were assessed in separate patient groups at mild and moderate-to-advanced stages of glaucoma. The pVDs at superotemporal and inferotemporal regions were significantly associated with corresponding VFMS in mild glaucoma (pglaucoma, there were significant associations between pVD and VFMS, regardless of location. The association between global pVD and VFMS was significantly stronger than that between global pRNFL thickness and VFMS in moderate-to-advanced stage glaucoma (p glaucoma. OCT-A may be useful in monitoring glaucoma at various stages. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  2. Spatial spread of local field potential is band-pass in the primary visual cortex.

    Science.gov (United States)

    Dubey, Agrita; Ray, Supratim

    2016-10-01

    Local field potential (LFP) is a valuable tool in understanding brain function and in brain machine-interfacing applications. However, there is no consensus on the spatial extent of the cortex that contributes to the LFP (its "spatial spread"), with different studies reporting values between a few hundred micrometers and several millimeters. Furthermore, the dependency of the spatial spread on frequency, which could reflect properties of the network architecture and extracellular medium, is not well studied, with theory and models predicting either "all-pass" (frequency-independent) or "low-pass" behavior. Surprisingly, we found the LFP spread to be "band-pass" in the primate primary visual cortex, with the greatest spread in the high-gamma range (60-150 Hz). This was accompanied by an increase in phase coherency across neighboring sites in the same frequency range, consistent with the findings of a recent model that reconciles previous studies by suggesting that spatial spread depends on neuronal correlations. Copyright © 2016 the American Physiological Society.

  3. Addressing the difficulty of changing fields in geophysics

    Science.gov (United States)

    Civilini, F.; Savage, M. K.

    2014-12-01

    Geophysics is a wonderfully diverse field of study, encompassing a variety of disciplines greatly different from one other. Even within the same discipline, various branches of study can have drastically different vocabulary and methodologies. The difficulty of breaking this "jargon" barrier is also an important reminder for scientists of how critical it is to clearly and concisely convey information. This presentation will focus on strategies that students can focus on to ease a transition between fields in geophysics. I believe that a student changing disciplines should proceed in the following steps: [1] Do a cursory literature review to find a review paper of the desired topic and work backwards through the details until a level of understanding or recognition is reached, [2] Obtain a clear physical understanding of the data and methods of the proposed study, and [3] Establish a support network through the research group or elsewhere which will recognize the areas in which the student is behind and offer remedies in a supportive and productive manner. These strategies are based on my own personal experience changing from music to geophysics in my undergrad and working on projects spanning various subdisciplines of geophysics during my Masters and PhD. It is worthwhile for research groups to spend the time to mentor students switching from other disciplines because those students will in time be able to observe the research in a different way than their peers, and easily adapt to changes of direction within the research.

  4. Grammatical number agreement processing using the visual half-field paradigm: an event-related brain potential study.

    Science.gov (United States)

    Kemmer, Laura; Coulson, Seana; Kutas, Marta

    2014-02-01

    Despite indications in the split-brain and lesion literatures that the right hemisphere is capable of some syntactic analysis, few studies have investigated right hemisphere contributions to syntactic processing in people with intact brains. Here we used the visual half-field paradigm in healthy adults to examine each hemisphere's processing of correct and incorrect grammatical number agreement marked either lexically, e.g., antecedent/reflexive pronoun ("The grateful niece asked herself/*themselves…") or morphologically, e.g., subject/verb ("Industrial scientists develop/*develops…"). For reflexives, response times and accuracy of grammaticality decisions suggested similar processing regardless of visual field of presentation. In the subject/verb condition, we observed similar response times and accuracies for central and right visual field (RVF) presentations. For left visual field (LVF) presentation, response times were longer and accuracy rates were reduced relative to RVF presentation. An event-related brain potential (ERP) study using the same materials revealed similar ERP responses to the reflexive pronouns in the two visual fields, but very different ERP effects to the subject/verb violations. For lexically marked violations on reflexives, P600 was elicited by stimuli in both the LVF and RVF; for morphologically marked violations on verbs, P600 was elicited only by RVF stimuli. These data suggest that both hemispheres can process lexically marked pronoun agreement violations, and do so in a similar fashion. Morphologically marked subject/verb agreement errors, however, showed a distinct LH advantage. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. [Change to "prevention of the avoidable blindness and visual impairment" from "prevention of blindness"].

    Science.gov (United States)

    Zhao, Jialiang

    2015-07-01

    The formulation on the eye health by WHO had an obvious change in recent years. Before 2006, WHO and WHA solutions clearly put forward the prevention of blindness. After 2006, WHO and WHA solutions on the eye health emphasized the elimination of the avoidable blindness and visual impairment. This change extends the scope of eye health, reflects the important progress on the global eye health, and also reflects the social progress and the increase to the need on eye health by the public. This change conforms to the actual situation in China. It is necessary to adopt elimination of the avoidable blindness and visual impairment as the priorities in eye health in making the 13th national plan of blindness prevention. This change is not merely a matter of wording, but also a great change in the working content in eye health. The change demonstrates the deep development on the eye health, and may benefit more people and promote the further development of eye health and ophthalmology in China.

  6. Visual Acuity Changes during Pregnancy and Postpartum: A Cross-Sectional Study in Iran

    Directory of Open Access Journals (Sweden)

    Khashayar Mehdizadehkashi

    2014-01-01

    Full Text Available In this research, we represent the changes in visual acuity during pregnancy and after delivery. Changes as myopic shift start during second trimester and will be stopped after delivery; however it is obtained that women will have the same refractive error as what they had in the first trimester, after postpartum. So, any change in their spectacle prescription during this period is forbidden. As a result, not only changing in hormones can cause myopic shift in vision, but also overweight has its retributive role. What we are trying to do is to notify gynecologists and optometrists to be aware of these changes, so as to leave spectacle prescription writing to the session after postpartum period.

  7. Visual acuity changes during pregnancy and postpartum: a cross-sectional study in Iran.

    Science.gov (United States)

    Mehdizadehkashi, Khashayar; Chaichian, Shahla; Mehdizadehkashi, Abolfazl; Jafarzadepour, Ebrahim; Tamannaie, Zeinab; Moazzami, Bahram; Pishgahroudsari, Mohaddeseh

    2014-01-01

    In this research, we represent the changes in visual acuity during pregnancy and after delivery. Changes as myopic shift start during second trimester and will be stopped after delivery; however it is obtained that women will have the same refractive error as what they had in the first trimester, after postpartum. So, any change in their spectacle prescription during this period is forbidden. As a result, not only changing in hormones can cause myopic shift in vision, but also overweight has its retributive role. What we are trying to do is to notify gynecologists and optometrists to be aware of these changes, so as to leave spectacle prescription writing to the session after postpartum period.

  8. Steady-state multifocal visual evoked potential (ssmfVEP) using dartboard stimulation as a possible tool for objective visual field assessment.

    Science.gov (United States)

    Horn, Folkert K; Selle, Franziska; Hohberger, Bettina; Kremers, Jan

    2016-02-01

    To investigate whether a conventional, monitor-based multifocal visual evoked potential (mfVEP) system can be used to record steady-state mfVEP (ssmfVEP) in healthy subjects and to study the effects of temporal frequency, electrode configuration and alpha waves. Multifocal pattern reversal VEP measurements were performed at 58 dartboard fields using VEP recording equipment. The responses were measured using m-sequences with four pattern reversals per m-step. Temporal frequencies were varied between 6 and 15 Hz. Recordings were obtained from nine normal subjects with a cross-shaped, four-electrode device (two additional channels were derived). Spectral analyses were performed on the responses at all locations. The signal to noise ratio (SNR) was computed for each response using the signal amplitude at the reversal frequency and the noise at the neighbouring frequencies. Most responses in the ssmfVEP were significantly above noise. The SNR was largest for an 8.6-Hz reversal frequency. The individual alpha electroencephalogram (EEG) did not strongly influence the results. The percentage of the records in which each of the 6 channels had the largest SNR was between 10.0 and 25.2 %. Our results in normal subjects indicate that reliable mfVEP responses can be achieved by steady-state stimulation using a conventional dartboard stimulator and multi-channel electrode device. The ssmfVEP may be useful for objective visual field assessment as spectrum analysis can be used for automated evaluation of responses. The optimal reversal frequency is 8.6 Hz. Alpha waves have only a minor influence on the analysis. Future studies must include comparisons with conventional mfVEP and psychophysical visual field tests.

  9. Rapid mapping of compound eye visual sampling parameters with FACETS, a highly automated wide-field goniometer.

    Science.gov (United States)

    Douglass, John K; Wehling, Martin F

    2016-12-01

    A highly automated goniometer instrument (called FACETS) has been developed to facilitate rapid mapping of compound eye parameters for investigating regional visual field specializations. The instrument demonstrates the feasibility of analyzing the complete field of view of an insect eye in a fraction of the time required if using non-motorized, non-computerized methods. Faster eye mapping makes it practical for the first time to employ sample sizes appropriate for testing hypotheses about the visual significance of interspecific differences in regional specializations. Example maps of facet sizes are presented from four dipteran insects representing the Asilidae, Calliphoridae, and Stratiomyidae. These maps provide the first quantitative documentation of the frontal enlarged-facet zones (EFZs) that typify asilid eyes, which, together with the EFZs in male Calliphoridae, are likely to be correlated with high-spatial-resolution acute zones. The presence of EFZs contrasts sharply with the almost homogeneous distribution of facet sizes in the stratiomyid. Moreover, the shapes of EFZs differ among species, suggesting functional specializations that may reflect differences in visual ecology. Surveys of this nature can help identify species that should be targeted for additional studies, which will elucidate fundamental principles and constraints that govern visual field specializations and their evolution.

  10. Visualizing olfactory learning functional imaging of experience-induced olfactory bulb changes.

    Science.gov (United States)

    Fletcher, Max L; Bendahmane, Mounir

    2014-01-01

    The anatomical organization of sensory neuron input allows odor information to be transformed into odorant-specific spatial maps of mitral/tufted cell glomerular activity. In other sensory systems, neuronal representations of sensory stimuli can be reorganized or enhanced following learning or experience. Similarly, several studies have demonstrated both structural and physiological experience-induced changes throughout the olfactory system. As experience-induced changes within this circuit likely serve as an initial site for odor memory formation, the olfactory bulb is an ideal site for optical imaging studies of olfactory learning, as they allow for the visualization of experience-induced changes in the glomerular circuit following learning and how these changes impact of odor representations with the bulb. Presently, optical imaging techniques have been used to visualize experience-induced changes in glomerular odor representations in a variety of paradigms in short-term habituation, chronic odor exposure, and olfactory associative conditioning. © 2014 Elsevier B.V. All rights reserved.

  11. EEG oscillations reflect visual short-term memory processes for the change detection in human faces.

    Science.gov (United States)

    Park, Hyoung-Dong; Min, Byoung-Kyong; Lee, Kyoung-Min

    2010-11-01

    People often fail to notice a large change in the visual scene when the change occurs during a brief interruption of the viewing. Since the change is well above perceptual threshold in continuous viewing, the failure (termed change blindness) has been attributed to abnormal visual short-term memory (VSTM). However, it is still unclear where the abnormality lies among the phases in VSTM, namely, encoding, maintenance, and retrieval-comparison. EEG oscillations, especially the gamma activity, have been suggested as neural signatures of VSTM, but have not been examined in the context of change blindness. Thus, we asked in the present study whether change detection or failure is correlated with EEG oscillatory activities and, if so, whether the timing and the spatial distribution of the oscillations could pin-point the abnormal phase of VSTM in change blindness. While on EEG recording, subjects watched morphed pictures of human faces in trials which consisted of a 200-ms initial image display, a 500-ms blank period, and a 200-ms comparison image display. The two images were either the same or clearly different above threshold. Trials with different images were classified as hit or missed, based on subjects' responses, and EEG data were compared between the two types of trials. Enhanced gamma activity was observed in the right temporal-parietal region during all periods in the hit trials compared to the missed ones. Frontal theta activity was increased during initial image encoding, whereas beta activity was decreased during maintenance and retrieval-comparison in the hit trials. These results point to weak encoding of initial images as the culprit for a later failure in change detection, while abnormal processing in subsequent phases of VSTM may result from the weak encoding and also contribute to change blindness. Copyright 2010 Elsevier Inc. All rights reserved.

  12. Visual receptive field properties of cells in the optic tectum of the archer fish

    NARCIS (Netherlands)

    M. Ben-Tov (Mor); I. Kopilevich (Ivgeny); O. Donchin (Opher); O. Ben-Shahar (Ohad); C. Giladi (Chen); R. Segev (Ronen)

    2013-01-01

    textabstractThe archer fish is well known for its extreme visual behavior in shooting water jets at prey hanging on vegetation above water. This fish is a promising model in the study of visual system function because it can be trained to respond to artificial targets and thus to provide valuable

  13. V4 receptive field dynamics as predicted by a systems-level model of visual attention using feedback from the frontal eye field.

    Science.gov (United States)

    Hamker, Fred H; Zirnsak, Marc

    2006-11-01

    Visual attention is generally considered to facilitate the processing of the attended stimulus. Its mechanisms, however, are still under debate. We have developed a systems-level model of visual attention which predicts that attentive effects emerge by the interactions between different brain areas. Recent physiological studies have provided evidence that attention also alters the receptive field structure. For example, V4 receptive fields typically shrink and shift towards the saccade target around saccade onset. We show that receptive field dynamics are inherently predicted by the mechanism of feedback in our model. According to the model an oculomotor feedback signal from an area involved in the competition for the saccade target location, e.g. the frontal eye field, enhances the gain of V4 cells. V4 receptive field dynamics can be observed after pooling the gain modulated responses to obtain a certain degree of spatial invariance. The time course of the receptive field dynamics in the model resemble those obtained from macaque V4.

  14. The attenuation surface for contrast sensitivity has the form of a witch's hat within the central visual field.

    Science.gov (United States)

    Baldwin, Alex S; Meese, Tim S; Baker, Daniel H

    2012-10-25

    Over the full visual field, contrast sensitivity is fairly well described by a linear decline in log sensitivity as a function of eccentricity (expressed in grating cycles). However, many psychophysical studies of spatial visual function concentrate on the central ±4.5 deg (or so) of the visual field. As the details of the variation in sensitivity have not been well documented in this region we did so for small patches of target contrast at several spatial frequencies (0.7-4 c/deg), meridians (horizontal, vertical, and oblique), orientations (horizontal, vertical, and oblique), and eccentricities (0-18 cycles). To reduce the potential effects of stimulus uncertainty, circular markers surrounded the targets. Our analysis shows that the decline in binocular log sensitivity within the central visual field is bilinear: The initial decline is steep, whereas the later decline is shallow and much closer to the classical results. The bilinear decline was approximately symmetrical in the horizontal meridian and declined most steeply in the superior visual field. Further analyses showed our results to be scale-invariant and that this property could not be predicted from cone densities. We used the results from the cardinal meridians to radially interpolate an attenuation surface with the shape of a witch's hat that provided good predictions for the results from the oblique meridians. The witch's hat provides a convenient starting point from which to build models of contrast sensitivity, including those designed to investigate signal summation and neuronal convergence of the image contrast signal. Finally, we provide Matlab code for constructing the witch's hat.

  15. The Changing Side of Art Education and A Restructuring Proposal for a New for Turkey Visual Arts Education

    OpenAIRE

    Mamur, Nuray

    2015-01-01

    Today, depending on the rapid advancement in technology and informatics, and the globalization, necessity for the increasing lifelong education requires change universities and various training programs. One of these programs, depending on the increase in the visual saturation, is undoubtedly the visual arts education, Today, in the context of the productions of contemporary art, changing aesthetic judgments, and social change,  arts education, there is a need to rethink on the content of art...

  16. A comparison of the sensitivity of EQ-5D, SF-6D and TTO utility values to changes in vision and perceived visual function in patients with primary open-angle glaucoma

    Directory of Open Access Journals (Sweden)

    Bozzani Fiammetta Maria

    2012-08-01

    Full Text Available Abstract Background Economic viability of treatments for primary open-angle glaucoma (POAG should be assessed objectively to prioritise health care interventions. This study aims to identify the methods for eliciting utility values (UVs most sensitive to differences in visual field and visual functioning in patients with POAG. As a secondary objective, the dimensions of generic health-related and vision-related quality of life most affected by progressive vision loss will be identified. Methods A total of 132 POAG patients were recruited. Three sets of utility values (EuroQoL EQ-5D, Short Form SF-6D, Time Trade Off and a measure of perceived visual functioning from the National Eye Institute Visual Function Questionnaire (VFQ-25 were elicited during face-to-face interviews. The sensitivity of UVs to differences in the binocular visual field, visual acuity and visual functioning measures was analysed using non-parametric statistical methods. Results Median utilities were similar across Integrated Visual Field score quartiles for EQ-5D (P = 0.08 whereas SF-6D and Time-Trade-Off UVs significantly decreased (p = 0.01 and p = 0.001, respectively. The VFQ-25 score varied across Integrated Visual Field and binocular visual acuity groups and was associated with all three UVs (P ≤ 0.001; most of its vision-specific sub-scales were associated with the vision markers. The most affected dimension was driving. A relationship with vision markers was found for the physical component of SF-36 and not for any dimension of EQ-5D. Conclusions The Time-Trade-Off was more sensitive than EQ-5D and SF-6D to changes in vision and visual functioning associated with glaucoma progression but could not measure quality of life changes in the mildest disease stages.

  17. Architecture of a spatial data service system for statistical analysis and visualization of regional climate changes

    Science.gov (United States)

    Titov, A. G.; Okladnikov, I. G.; Gordov, E. P.

    2017-11-01

    The use of large geospatial datasets in climate change studies requires the development of a set of Spatial Data Infrastructure (SDI) elements, including geoprocessing and cartographical visualization web services. This paper presents the architecture of a geospatial OGC web service system as an integral part of a virtual research environment (VRE) general architecture for statistical processing and visualization of meteorological and climatic data. The architecture is a set of interconnected standalone SDI nodes with corresponding data storage systems. Each node runs a specialized software, such as a geoportal, cartographical web services (WMS/WFS), a metadata catalog, and a MySQL database of technical metadata describing geospatial datasets available for the node. It also contains geospatial data processing services (WPS) based on a modular computing backend realizing statistical processing functionality and, thus, providing analysis of large datasets with the results of visualization and export into files of standard formats (XML, binary, etc.). Some cartographical web services have been developed in a system’s prototype to provide capabilities to work with raster and vector geospatial data based on OGC web services. The distributed architecture presented allows easy addition of new nodes, computing and data storage systems, and provides a solid computational infrastructure for regional climate change studies based on modern Web and GIS technologies.

  18. Change of Paradigm for the Reversed Field Pinch

    Science.gov (United States)

    Escande, D. F.

    2010-11-01

    The reversed field pinch (RFP) is a magnetic configuration germane to the tokamak, but it produces most of its magnetic field by the currents flowing inside the plasma; external coils provide only a small edge toroidal field whose sign is reversed with respect to the central one, whence the name of the configuration. Because of the presence of magnetic turbulence and chaos, the RFP had been considered for a long period as a terrible confinement configuration. However, recently a change of paradigm occurred for this device. Indeed, when the toroidal current is increased in the RFX-mod RFP in Padua (Italy), a self-organized helical state with an internal transport barrier (ITB) develops, and a broad zone of the plasma becomes hot (above 1 keV for a magnetic field above 0.8 T). The present theoretical picture of the RFP mainly comes from three-dimensional nonlinear visco-resistive MHD simulations whose dynamics has strong similarities with the experimental one, and triggered the experimental search for RFP states with improved confinement. The RFP ohmic state involves a helical electrostatic potential generating, as an electric drift, the so-called dynamo velocity field. The magnetic topology can bifurcate from a magnetic island to kink-like magnetic surfaces with higher resilience to magnetic chaos. This theoretical scenario was found to be relevant when ITB's enclosing a broad hot domain were discovered. The ITBs occur in the vicinity of the maximum of the safety factor. The new paradigm for the RFP supports its reappraisal as a low-external field, non-disruptive, ohmically heated approach to magnetic fusion, exploiting both self-organization and technological simplicity. Furthermore the RFP has the same Greenwald density limit as the tokamak, and it is an excellent test bed for the efficient control of multiple resistive wall modes. Its helical magnetic structure makes it germane to the stellarator too. As a result the RFP is also useful to bring support to the

  19. Corneal Biomechanical Parameters and Asymmetric Visual Field Damage in Patients with Untreated Normal Tension Glaucoma.

    Science.gov (United States)

    Li, Bai-Bing; Cai, Yu; Pan, Ying-Zi; Li, Mei; Qiao, Rong-Hua; Fang, Yuan; Tian, Tian

    2017-02-05

    High intraocular pressure (IOP) and low central corneal thickness (CCT) are important validated risk factors for glaucoma, and some studies also have suggested that eyes with more deformable corneas may be in higher risk of the development and worsening of glaucoma. In the present study, we aimed to evaluate the association between corneal biomechanical parameters and asymmetric visual field (VF) damage using a Corvis-ST device in patients with untreated normal tension glaucoma (NTG). In this observational, cross-sectional study, 44 newly diagnosed NTG patients were enrolled. Of these, 31 had asymmetric VF damage, which was defined as a 5-point difference between the eyes according to the Advanced Glaucoma Intervention Study scoring system. Corneal biomechanical parameters were obtained using a Corvis-ST device, such as time from start until the first and second applanation is reached (time A1 and time A2, respectively), cord length of the first and second applanation (length A1 and length A2, respectively), corneal speed during the first and second applanation (velocity A1 and velocity A2, respectively), time from start until highest concavity is reached (time HC), maximum amplitude at the apex of highest concavity (def ampl HC), distance between the two peaks at highest concavity (peak dist HC), and central concave curvature at its highest concavity (radius HC). Time A1 (7.19 ± 0.28 vs. 7.37 ± 0.41 ms, P = 0.010), length A1 (1.73 [1.70-1.76] vs. 1.78 [1.76-1.79] mm, P = 0.007), length A2 (1.58 [1.46-1.70] vs. 1.84 [1.76-1.92] mm, Pcorneal response parameters but not IOP or CCT between the paired eyes of NTG patients with asymmetric VF damage. We suggest that the shape of the cornea is more easily altered in the worse eyes of asymmetric NTG patients.

  20. Enhancement of Visual Field Predictions with Pointwise Exponential Regression (PER) and Pointwise Linear Regression (PLR).

    Science.gov (United States)

    Morales, Esteban; de Leon, John Mark S; Abdollahi, Niloufar; Yu, Fei; Nouri-Mahdavi, Kouros; Caprioli, Joseph

    2016-03-01

    The study was conducted to evaluate threshold smoothing algorithms to enhance prediction of the rates of visual field (VF) worsening in glaucoma. We studied 798 patients with primary open-angle glaucoma and 6 or more years of follow-up who underwent 8 or more VF examinations. Thresholds at each VF location for the first 4 years or first half of the follow-up time (whichever was greater) were smoothed with clusters defined by the nearest neighbor (NN), Garway-Heath, Glaucoma Hemifield Test (GHT), and weighting by the correlation of rates at all other VF locations. Thresholds were regressed with a pointwise exponential regression (PER) model and a pointwise linear regression (PLR) model. Smaller root mean square error (RMSE) values of the differences between the observed and the predicted thresholds at last two follow-ups indicated better model predictions. The mean (SD) follow-up times for the smoothing and prediction phase were 5.3 (1.5) and 10.5 (3.9) years. The mean RMSE values for the PER and PLR models were unsmoothed data, 6.09 and 6.55; NN, 3.40 and 3.42; Garway-Heath, 3.47 and 3.48; GHT, 3.57 and 3.74; and correlation of rates, 3.59 and 3.64. Smoothed VF data predicted better than unsmoothed data. Nearest neighbor provided the best predictions; PER also predicted consistently more accurately than PLR. Smoothing algorithms should be used when forecasting VF results with PER or PLR. The application of smoothing algorithms on VF data can improve forecasting in VF points to assist in treatment decisions.

  1. Relationship between visual field progression and baseline refraction in primary open-angle glaucoma.

    Science.gov (United States)

    Naito, Tomoko; Yoshikawa, Keiji; Mizoue, Shiro; Nanno, Mami; Kimura, Tairo; Suzumura, Hirotaka; Umeda, Yuzo; Shiraga, Fumio

    2016-01-01

    To analyze the relationship between visual field (VF) progression and baseline refraction in Japanese patients with primary open-angle glaucoma (POAG) including normal-tension glaucoma. In this retrospective study, the subjects were patients with POAG who had undergone VF tests at least ten times with a Humphrey Field Analyzer (Swedish interactive thresholding algorithm standard, Central 30-2 program). VF progression was defined as a significantly negative value of mean deviation (MD) slope at the final VF test. Multivariate logistic regression models were applied to detect an association between MD slope deterioration and baseline refraction. A total of 156 eyes of 156 patients were included in this analysis. Significant deterioration of MD slope was observed in 70 eyes of 70 patients (44.9%), whereas no significant deterioration was evident in 86 eyes of 86 patients (55.1%). The eyes with VF progression had significantly higher baseline refraction compared to those without apparent VF progression (-1.9±3.8 diopter [D] vs -3.5±3.4 D, P=0.0048) (mean ± standard deviation). When subject eyes were classified into four groups by the level of baseline refraction applying spherical equivalent (SE): no myopia (SE > -1D), mild myopia (-1D ≥ SE > -3D), moderate myopia (-3D ≥ SE > -6D), and severe myopia (-6D ≥ SE), the Cochran-Armitage trend analysis showed a decreasing trend in the proportion of MD slope deterioration with increasing severity of myopia (P=0.0002). The multivariate analysis revealed that baseline refraction (P=0.0108, odds ratio [OR]: 1.13, 95% confidence interval [CI]: 1.03-1.25) and intraocular pressure reduction rate (P=0.0150, OR: 0.97, 95% CI: 0.94-0.99) had a significant association with MD slope deterioration. In the current analysis of Japanese patients with POAG, baseline refraction was a factor significantly associated with MD slope deterioration as well as intraocular pressure reduction rate. When baseline refraction was classified into

  2. From Agents to Continuous Change via Aesthetics: Learning Mechanics with Visual Agentbased Computational Modeling

    CERN Document Server

    Sengupta, Pratim; Wright, Mason

    2013-01-01

    Novice learners find motion as a continuous process of change challenging to understand. In this paper, we present a pedagogical approach based on agent-based, visual programming to address this issue. Integrating Logo programming with curricular science has been shown to be challenging in previous research on educational computing. We present a new Logo-based visual programming language - ViMAP - and, a sequence of learning activities involving programming and modeling, designed specifically to support seamless integration between programming and learning kinematics. We describe relevant affordances of the ViMAP environment that supports such seamless integration. We then present ViMAP-MoMo, a curricular unit designed in ViMAP for modeling kinematics, for a wide range of students (elementary - high school). The main contribution of this paper is that we describe in detail a sequence