WorldWideScience

Sample records for monocular visual loss

  1. A Case of Recurrent Transient Monocular Visual Loss after Receiving Sildenafil

    Directory of Open Access Journals (Sweden)

    Asaad Ghanem Ghanem

    2011-01-01

    Full Text Available A 53-year-old man was attended to the Clinic Ophthalmic Center, Mansoura University, Egypt, with recurrent transient monocular visual loss after receiving sildenafil citrate (Viagra for erectile dysfunction. Examination for possible risk factors revealed mild hypercholesterolemia. Family history showed that his father had suffered from bilateral nonarteritic anterior ischemic optic neuropathy (NAION. Physicians might look for arteriosclerotic risk factors and family history of NAION among predisposing risk factors before prescribing sildenafil erectile dysfunction drugs.

  2. Visual system plasticity in mammals: the story of monocular enucleation-induced vision loss

    Science.gov (United States)

    Nys, Julie; Scheyltjens, Isabelle; Arckens, Lutgarde

    2015-01-01

    The groundbreaking work of Hubel and Wiesel in the 1960’s on ocular dominance plasticity instigated many studies of the visual system of mammals, enriching our understanding of how the development of its structure and function depends on high quality visual input through both eyes. These studies have mainly employed lid suturing, dark rearing and eye patching applied to different species to reduce or impair visual input, and have created extensive knowledge on binocular vision. However, not all aspects and types of plasticity in the visual cortex have been covered in full detail. In that regard, a more drastic deprivation method like enucleation, leading to complete vision loss appears useful as it has more widespread effects on the afferent visual pathway and even on non-visual brain regions. One-eyed vision due to monocular enucleation (ME) profoundly affects the contralateral retinorecipient subcortical and cortical structures thereby creating a powerful means to investigate cortical plasticity phenomena in which binocular competition has no vote.In this review, we will present current knowledge about the specific application of ME as an experimental tool to study visual and cross-modal brain plasticity and compare early postnatal stages up into adulthood. The structural and physiological consequences of this type of extensive sensory loss as documented and studied in several animal species and human patients will be discussed. We will summarize how ME studies have been instrumental to our current understanding of the differentiation of sensory systems and how the structure and function of cortical circuits in mammals are shaped in response to such an extensive alteration in experience. In conclusion, we will highlight future perspectives and the clinical relevance of adding ME to the list of more longstanding deprivation models in visual system research. PMID:25972788

  3. Does monocular visual space contain planes?

    NARCIS (Netherlands)

    Koenderink, J.J.; Albertazzi, L.; Doorn, A.J. van; Ee, R. van; Grind, W.A. van de; Kappers, A.M.L.; Lappin, J.S.; Norman, J.F.; Oomes, A.H.J.; Pas, S.F. te; Phillips, F.; Pont, S.C.; Richards, W.A.; Todd, J.T.; Verstraten, F.A.J.; Vries, S.C. de

    2010-01-01

    The issue of the existence of planes—understood as the carriers of a nexus of straight lines—in the monocular visual space of a stationary human observer has never been addressed. The most recent empirical data apply to binocular visual space and date from the 1960s (Foley, 1964). This appears to be

  4. Does monocular visual space contain planes?

    NARCIS (Netherlands)

    Koenderink, Jan J.; Albertazzi, Liliana; van Doorn, Andrea J.; van Ee, Raymond; van de Grind, Wim A.; Kappers, Astrid M L; Lappin, Joe S.; Farley Norman, J.; (Stijn) Oomes, A. H J; te Pas, Susan P.; Phillips, Flip; Pont, Sylvia C.; Richards, Whitman A.; Todd, James T.; Verstraten, Frans A J; de Vries, Sjoerd

    The issue of the existence of planes-understood as the carriers of a nexus of straight lines-in the monocular visual space of a stationary human observer has never been addressed. The most recent empirical data apply to binocular visual space and date from the 1960s (Foley, 1964). This appears to be

  5. Monocular Visual Deprivation Suppresses Excitability in Adult Human Visual Cortex

    DEFF Research Database (Denmark)

    Lou, Astrid Rosenstand; Madsen, Kristoffer Hougaard; Paulson, Olaf Bjarne

    2011-01-01

    The adult visual cortex maintains a substantial potential for plasticity in response to a change in visual input. For instance, transcranial magnetic stimulation (TMS) studies have shown that binocular deprivation (BD) increases the cortical excitability for inducing phosphenes with TMS. Here, we...... of visual deprivation has a substantial impact on experience-dependent plasticity of the human visual cortex.......The adult visual cortex maintains a substantial potential for plasticity in response to a change in visual input. For instance, transcranial magnetic stimulation (TMS) studies have shown that binocular deprivation (BD) increases the cortical excitability for inducing phosphenes with TMS. Here, we...... employed TMS to trace plastic changes in adult visual cortex before, during, and after 48 h of monocular deprivation (MD) of the right dominant eye. In healthy adult volunteers, MD-induced changes in visual cortex excitability were probed with paired-pulse TMS applied to the left and right occipital cortex...

  6. Disseminated neurocysticercosis presenting as isolated acute monocular painless vision loss

    Directory of Open Access Journals (Sweden)

    Gaurav M Kasundra

    2014-01-01

    Full Text Available Neurocysticercosis, the most common parasitic infection of the nervous system, is known to affect the brain, eyes, muscular tissues and subcutaneous tissues. However, it is very rare for patients with ocular cysts to have concomitant cerebral cysts. Also, the dominant clinical manifestation of patients with cerebral cysts is either seizures or headache. We report a patient who presented with acute monocular painless vision loss due to intraocular submacular cysticercosis, who on investigation had multiple cerebral parenchymal cysticercal cysts, but never had any seizures. Although such a vision loss after initiation of antiparasitic treatment has been mentioned previously, acute monocular vision loss as the presenting feature of ocular cysticercosis is rare. We present a brief review of literature along with this case report.

  7. SLAMM: Visual monocular SLAM with continuous mapping using multiple maps.

    Directory of Open Access Journals (Sweden)

    Hayyan Afeef Daoud

    Full Text Available This paper presents the concept of Simultaneous Localization and Multi-Mapping (SLAMM. It is a system that ensures continuous mapping and information preservation despite failures in tracking due to corrupted frames or sensor's malfunction; making it suitable for real-world applications. It works with single or multiple robots. In a single robot scenario the algorithm generates a new map at the time of tracking failure, and later it merges maps at the event of loop closure. Similarly, maps generated from multiple robots are merged without prior knowledge of their relative poses; which makes this algorithm flexible. The system works in real time at frame-rate speed. The proposed approach was tested on the KITTI and TUM RGB-D public datasets and it showed superior results compared to the state-of-the-arts in calibrated visual monocular keyframe-based SLAM. The mean tracking time is around 22 milliseconds. The initialization is twice as fast as it is in ORB-SLAM, and the retrieved map can reach up to 90 percent more in terms of information preservation depending on tracking loss and loop closure events. For the benefit of the community, the source code along with a framework to be run with Bebop drone are made available at https://github.com/hdaoud/ORBSLAMM.

  8. A monocular, unconscious form of visual attention

    NARCIS (Netherlands)

    Self, M.W.; Roelfsema, P.R.

    2010-01-01

    Sudden changes in our visual field capture our attention so that we are faster and more accurate in our responses to that region of space. The underlying mechanisms by which these behavioral improvements occur are unknown. Here we investigate the level of the visual system at which attentional

  9. A novel visual-inertial monocular SLAM

    Science.gov (United States)

    Yue, Xiaofeng; Zhang, Wenjuan; Xu, Li; Liu, JiangGuo

    2018-02-01

    With the development of sensors and computer vision research community, cameras, which are accurate, compact, wellunderstood and most importantly cheap and ubiquitous today, have gradually been at the center of robot location. Simultaneous localization and mapping (SLAM) using visual features, which is a system getting motion information from image acquisition equipment and rebuild the structure in unknown environment. We provide an analysis of bioinspired flights in insects, employing a novel technique based on SLAM. Then combining visual and inertial measurements to get high accuracy and robustness. we present a novel tightly-coupled Visual-Inertial Simultaneous Localization and Mapping system which get a new attempt to address two challenges which are the initialization problem and the calibration problem. experimental results and analysis show the proposed approach has a more accurate quantitative simulation of insect navigation, which can reach the positioning accuracy of centimeter level.

  10. Visual Suppression of Monocularly Presented Symbology Against a Fused Background in a Simulation and Training Environment

    National Research Council Canada - National Science Library

    Winterbottom, Marc D; Patterson, Robert; Pierce, Byron J; Taylor, Amanda

    2006-01-01

    .... This may create interocular differences in image characteristics that could disrupt binocular vision by provoking visual suppression, thus reducing visibility of the background scene, monocular symbology...

  11. Monocular Visual Odometry Based on Trifocal Tensor Constraint

    Science.gov (United States)

    Chen, Y. J.; Yang, G. L.; Jiang, Y. X.; Liu, X. Y.

    2018-02-01

    For the problem of real-time precise localization in the urban street, a monocular visual odometry based on Extend Kalman fusion of optical-flow tracking and trifocal tensor constraint is proposed. To diminish the influence of moving object, such as pedestrian, we estimate the motion of the camera by extracting the features on the ground, which improves the robustness of the system. The observation equation based on trifocal tensor constraint is derived, which can form the Kalman filter alone with the state transition equation. An Extend Kalman filter is employed to cope with the nonlinear system. Experimental results demonstrate that, compares with Yu’s 2-step EKF method, the algorithm is more accurate which meets the needs of real-time accurate localization in cities.

  12. Visual Servo Tracking Control of a Wheeled Mobile Robot with a Monocular Fixed Camera

    National Research Council Canada - National Science Library

    Chen, J; Dixon, W. E; Dawson, D. M; Chitrakaran, V. K

    2004-01-01

    In this paper, a visual servo tracking controller for a wheeled mobile robot (WMR) is developed that utilizes feedback from a monocular camera system that is mounted with a fixed position and orientation...

  13. Temporal visual field defects are associated with monocular inattention in chiasmal pathology.

    Science.gov (United States)

    Fledelius, Hans C

    2009-11-01

    Chiasmal lesions have been shown to give rise occasionally to uni-ocular temporal inattention, which cannot be compensated for by volitional eye movement. This article describes the assessments of 46 such patients with chiasmal pathology. It aims to determine the clinical spectrum of this disorder, including interference with reading. Retrospective consecutive observational clinical case study over a 7-year period comprising 46 patients with chiasmal field loss of varying degrees. Observation of reading behaviour during monocular visual acuity testing ascertained from consecutive patients who appeared unable to read optotypes on the temporal side of the chart. Visual fields were evaluated by kinetic (Goldmann) and static (Octopus) techniques. Five patients who clearly manifested this condition are presented in more detail. The results of visual field testing were related to absence or presence of uni-ocular visual inattentive behaviour for distance visual acuity testing and/or reading printed text. Despite normal eye movements, the 46 patients making up the clinical series perceived only optotypes in the nasal part of the chart, in one eye or in both, when tested for each eye in turn. The temporal optotypes were ignored, and this behaviour persisted despite instruction to search for any additional letters temporal to those, which had been seen. This phenomenon of unilateral visual inattention held for both eyes in 18 and was unilateral in the remaining 28 patients. Partial or full reversibility after treatment was recorded in 21 of the 39 for whom reliable follow-up data were available. Reading a text was affected in 24 individuals, and permanently so in six. A neglect-like spatial unawareness and a lack of cognitive compensation for varying degrees of temporal visual field loss were present in all the patients observed. Not only is visual field loss a feature of chiasmal pathology, but the higher visual function of affording attention within the temporal visual

  14. [Effect of acupuncture on pattern-visual evoked potential in rats with monocular visual deprivation].

    Science.gov (United States)

    Yan, Xing-Ke; Dong, Li-Li; Liu, An-Guo; Wang, Jun-Yan; Ma, Chong-Bing; Zhu, Tian-Tian

    2013-08-01

    To explore electrophysiology mechanism of acupuncture for treatment and prevention of visual deprivation effect. Eighteen healthy 15-day Evans rats were randomly divided into a normal group, a model group and an acupuncture group, 6 rats in each one. Deprivation amblyopia model was established by monocular eyelid suture in the model group and acupuncture group. Acupuncture was applied at "Jingming" (BL 1), "Chengqi" (ST 1), "Qiuhou" (EX-HN 7) and "Cuanzhu" (BL 2) in the acupuncture group. The bilateral acupoints were selected alternately, one side for a day, and totally 14 days were required. The effect of acupuncture on visual evoked potential in different spatial frequencies was observed. Under three different kinds of spatial frequencies of 2 X 2, 4 X 4 and 8 X 8, compared with normal group, there was obvious visual deprivation effect in the model group where P1 peak latency was delayed (P0.05). Under spatial frequency of 4 X 4, N1-P1 amplitude value was maximum in the normal group and acupuncture group. With this spatial frequency the rat's eye had best resolving ability, indicating it could be the best spatial frequency for rat visual system. The visual system has obvious electrophysiology plasticity in sensitive period. Acupuncture treatment could adjust visual deprivation-induced suppression and slow of visual response in order to antagonism deprivation effect.

  15. The monocular visual imaging technology model applied in the airport surface surveillance

    Science.gov (United States)

    Qin, Zhe; Wang, Jian; Huang, Chao

    2013-08-01

    At present, the civil aviation airports use the surface surveillance radar monitoring and positioning systems to monitor the aircrafts, vehicles and the other moving objects. Surface surveillance radars can cover most of the airport scenes, but because of the terminals, covered bridges and other buildings geometry, surface surveillance radar systems inevitably have some small segment blind spots. This paper presents a monocular vision imaging technology model for airport surface surveillance, achieving the perception of scenes of moving objects such as aircrafts, vehicles and personnel location. This new model provides an important complement for airport surface surveillance, which is different from the traditional surface surveillance radar techniques. Such technique not only provides clear objects activities screen for the ATC, but also provides image recognition and positioning of moving targets in this area. Thereby it can improve the work efficiency of the airport operations and avoid the conflict between the aircrafts and vehicles. This paper first introduces the monocular visual imaging technology model applied in the airport surface surveillance and then the monocular vision measurement accuracy analysis of the model. The monocular visual imaging technology model is simple, low cost, and highly efficient. It is an advanced monitoring technique which can make up blind spot area of the surface surveillance radar monitoring and positioning systems.

  16. [Acute monocular loss of vision : Differential diagnostic considerations apart from the internistic etiological clarification].

    Science.gov (United States)

    Rickmann, A; Macek, M A; Szurman, P; Boden, K

    2017-08-03

    We report the case of acute painless monocular loss of vision in a 53-year-old man. An interdisciplinary etiological evaluation remained without pathological findings with respect to arterial branch occlusion. A reevaluation of the patient history led to a possible association with the administration of phosphodiesterase type 5 inhibitor (PDE5 inhibitor). A critical review of the literature on PDE5 inhibitor administration with ocular participation was performed.

  17. Monocular and binocular visual impairment in the UK Biobank study: prevalence, associations and diagnoses.

    Science.gov (United States)

    McKibbin, Martin; Farragher, Tracey M; Shickle, Darren

    2018-01-01

    To determine the prevalence of, associations with and diagnoses leading to mild visual impairment or worse (logMAR >0.3) in middle-aged adults in the UK Biobank study. Prevalence estimates for monocular and binocular visual impairment were determined for the UK Biobank participants with fundus photographs and spectral domain optical coherence tomography images. Associations with socioeconomic, biometric, lifestyle and medical variables were investigated for cases with visual impairment and matched controls, using multinomial logistic regression models. Self-reported eye history and image grading results were used to identify the primary diagnoses leading to visual impairment for a sample of 25% of cases. For the 65 033 UK Biobank participants, aged 40-69 years and with fundus images, 6682 (10.3%) and 1677 (2.6%) had mild visual impairment or worse in one or both eyes, respectively. Increasing deprivation, age and ethnicity were independently associated with both monocular and binocular visual impairment. No primary diagnosis for the recorded level of visual impairment could be identified for 49.8% of eyes. The most common identifiable diagnoses leading to visual impairment were cataract, amblyopia, uncorrected refractive error and vitreoretinal interface abnormalities. The prevalence of visual impairment in the UK Biobank study cohort is lower than for population-based studies from other industrialised countries. Monocular and binocular visual impairment are associated with increasing deprivation, age and ethnicity. The UK Biobank dataset does not allow confident identification of the causes of visual impairment, and the results may not be applicable to the wider UK population.

  18. Monocular and binocular visual impairment in the UK Biobank study: prevalence, associations and diagnoses

    Science.gov (United States)

    Farragher, Tracey M; Shickle, Darren

    2018-01-01

    Objective To determine the prevalence of, associations with and diagnoses leading to mild visual impairment or worse (logMAR >0.3) in middle-aged adults in the UK Biobank study. Methods and analysis Prevalence estimates for monocular and binocular visual impairment were determined for the UK Biobank participants with fundus photographs and spectral domain optical coherence tomography images. Associations with socioeconomic, biometric, lifestyle and medical variables were investigated for cases with visual impairment and matched controls, using multinomial logistic regression models. Self-reported eye history and image grading results were used to identify the primary diagnoses leading to visual impairment for a sample of 25% of cases. Results For the 65 033 UK Biobank participants, aged 40–69 years and with fundus images, 6682 (10.3%) and 1677 (2.6%) had mild visual impairment or worse in one or both eyes, respectively. Increasing deprivation, age and ethnicity were independently associated with both monocular and binocular visual impairment. No primary diagnosis for the recorded level of visual impairment could be identified for 49.8% of eyes. The most common identifiable diagnoses leading to visual impairment were cataract, amblyopia, uncorrected refractive error and vitreoretinal interface abnormalities. Conclusions The prevalence of visual impairment in the UK Biobank study cohort is lower than for population-based studies from other industrialised countries. Monocular and binocular visual impairment are associated with increasing deprivation, age and ethnicity. The UK Biobank dataset does not allow confident identification of the causes of visual impairment, and the results may not be applicable to the wider UK population. PMID:29657974

  19. Adaptive Monocular Visual-Inertial SLAM for Real-Time Augmented Reality Applications in Mobile Devices.

    Science.gov (United States)

    Piao, Jin-Chun; Kim, Shin-Dug

    2017-11-07

    Simultaneous localization and mapping (SLAM) is emerging as a prominent issue in computer vision and next-generation core technology for robots, autonomous navigation and augmented reality. In augmented reality applications, fast camera pose estimation and true scale are important. In this paper, we present an adaptive monocular visual-inertial SLAM method for real-time augmented reality applications in mobile devices. First, the SLAM system is implemented based on the visual-inertial odometry method that combines data from a mobile device camera and inertial measurement unit sensor. Second, we present an optical-flow-based fast visual odometry method for real-time camera pose estimation. Finally, an adaptive monocular visual-inertial SLAM is implemented by presenting an adaptive execution module that dynamically selects visual-inertial odometry or optical-flow-based fast visual odometry. Experimental results show that the average translation root-mean-square error of keyframe trajectory is approximately 0.0617 m with the EuRoC dataset. The average tracking time is reduced by 7.8%, 12.9%, and 18.8% when different level-set adaptive policies are applied. Moreover, we conducted experiments with real mobile device sensors, and the results demonstrate the effectiveness of performance improvement using the proposed method.

  20. Estimated Prevalence of Monocular Blindness and Monocular ...

    African Journals Online (AJOL)

    with MB/MSVI; among the 109 (51%) children with MB/MSVI that had a known etiology, trauma. Table 1: Major anatomical site of monocular blindness and monocular severe visual impairment in children. Anatomical cause. Total (%). Corneal scar. 89 (42). Whole globe. 43 (20). Lens. 42 (19). Amblyopia. 16 (8). Retina. 9 (4).

  1. 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.

  2. Incorporating a Wheeled Vehicle Model in a New Monocular Visual Odometry Algorithm for Dynamic Outdoor Environments

    Science.gov (United States)

    Jiang, Yanhua; Xiong, Guangming; Chen, Huiyan; Lee, Dah-Jye

    2014-01-01

    This paper presents a monocular visual odometry algorithm that incorporates a wheeled vehicle model for ground vehicles. The main innovation of this algorithm is to use the single-track bicycle model to interpret the relationship between the yaw rate and side slip angle, which are the two most important parameters that describe the motion of a wheeled vehicle. Additionally, the pitch angle is also considered since the planar-motion hypothesis often fails due to the dynamic characteristics of wheel suspensions and tires in real-world environments. Linearization is used to calculate a closed-form solution of the motion parameters that works as a hypothesis generator in a RAndom SAmple Consensus (RANSAC) scheme to reduce the complexity in solving equations involving trigonometric. All inliers found are used to refine the winner solution through minimizing the reprojection error. Finally, the algorithm is applied to real-time on-board visual localization applications. Its performance is evaluated by comparing against the state-of-the-art monocular visual odometry methods using both synthetic data and publicly available datasets over several kilometers in dynamic outdoor environments. PMID:25256109

  3. Incorporating a Wheeled Vehicle Model in a New Monocular Visual Odometry Algorithm for Dynamic Outdoor Environments

    Directory of Open Access Journals (Sweden)

    Yanhua Jiang

    2014-09-01

    Full Text Available This paper presents a monocular visual odometry algorithm that incorporates a wheeled vehicle model for ground vehicles. The main innovation of this algorithm is to use the single-track bicycle model to interpret the relationship between the yaw rate and side slip angle, which are the two most important parameters that describe the motion of a wheeled vehicle. Additionally, the pitch angle is also considered since the planar-motion hypothesis often fails due to the dynamic characteristics of wheel suspensions and tires in real-world environments. Linearization is used to calculate a closed-form solution of the motion parameters that works as a hypothesis generator in a RAndom SAmple Consensus (RANSAC scheme to reduce the complexity in solving equations involving trigonometric. All inliers found are used to refine the winner solution through minimizing the reprojection error. Finally, the algorithm is applied to real-time on-board visual localization applications. Its performance is evaluated by comparing against the state-of-the-art monocular visual odometry methods using both synthetic data and publicly available datasets over several kilometers in dynamic outdoor environments.

  4. Synaptic Mechanisms of Activity-Dependent Remodeling in Visual Cortex during Monocular Deprivation

    Directory of Open Access Journals (Sweden)

    Cynthia D. Rittenhouse

    2009-01-01

    Full Text Available It has long been appreciated that in the visual cortex, particularly within a postnatal critical period for experience-dependent plasticity, the closure of one eye results in a shift in the responsiveness of cortical cells toward the experienced eye. While the functional aspects of this ocular dominance shift have been studied for many decades, their cortical substrates and synaptic mechanisms remain elusive. Nonetheless, it is becoming increasingly clear that ocular dominance plasticity is a complex phenomenon that appears to have an early and a late component. Early during monocular deprivation, deprived eye cortical synapses depress, while later during the deprivation open eye synapses potentiate. Here we review current literature on the cortical mechanisms of activity-dependent plasticity in the visual system during the critical period. These studies shed light on the role of activity in shaping neuronal structure and function in general and can lead to insights regarding how learning is acquired and maintained at the neuronal level during normal and pathological brain development.

  5. 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.

  6. Layer- and cell-type-specific subthreshold and suprathreshold effects of long-term monocular deprivation in rat visual cortex.

    Science.gov (United States)

    Medini, Paolo

    2011-11-23

    Connectivity and dendritic properties are determinants of plasticity that are layer and cell-type specific in the neocortex. However, the impact of experience-dependent plasticity at the level of synaptic inputs and spike outputs remains unclear along vertical cortical microcircuits. Here I compared subthreshold and suprathreshold sensitivity to prolonged monocular deprivation (MD) in rat binocular visual cortex in layer 4 and layer 2/3 pyramids (4Ps and 2/3Ps) and in thick-tufted and nontufted layer 5 pyramids (5TPs and 5NPs), which innervate different extracortical targets. In normal rats, 5TPs and 2/3Ps are the most binocular in terms of synaptic inputs, and 5NPs are the least. Spike responses of all 5TPs were highly binocular, whereas those of 2/3Ps were dominated by either the contralateral or ipsilateral eye. MD dramatically shifted the ocular preference of 2/3Ps and 4Ps, mostly by depressing deprived-eye inputs. Plasticity was profoundly different in layer 5. The subthreshold ocular preference shift was sevenfold smaller in 5TPs because of smaller depression of deprived inputs combined with a generalized loss of responsiveness, and was undetectable in 5NPs. Despite their modest ocular dominance change, spike responses of 5TPs consistently lost their typically high binocularity during MD. The comparison of MD effects on 2/3Ps and 5TPs, the main affected output cells of vertical microcircuits, indicated that subthreshold plasticity is not uniquely determined by the initial degree of input binocularity. The data raise the question of whether 5TPs are driven solely by 2/3Ps during MD. The different suprathreshold plasticity of the two cell populations could underlie distinct functional deficits in amblyopia.

  7. Visual memory for objects following foveal vision loss.

    Science.gov (United States)

    Geringswald, Franziska; Herbik, Anne; Hofmüller, Wolfram; Hoffmann, Michael B; Pollmann, Stefan

    2015-09-01

    Allocation of visual attention is crucial for encoding items into visual long-term memory. In free vision, attention is closely linked to the center of gaze, raising the question whether foveal vision loss entails suboptimal deployment of attention and subsequent impairment of object encoding. To investigate this question, we examined visual long-term memory for objects in patients suffering from foveal vision loss due to age-related macular degeneration. We measured patients' change detection sensitivity after a period of free scene exploration monocularly with their worse eye when possible, and under binocular vision, comparing sensitivity and eye movements to matched normal-sighted controls. A highly salient cue was used to capture attention to a nontarget location before a target change occurred in half of the trials, ensuring that change detection relied on memory. Patients' monocular and binocular sensitivity to object change was comparable to controls, even after more than 4 intervening fixations, and not significantly correlated with visual impairment. We conclude that extrafoveal vision suffices for efficient encoding into visual long-term memory. (c) 2015 APA, all rights reserved).

  8. Recovery of neurofilament following early monocular deprivation

    Directory of Open Access Journals (Sweden)

    Timothy P O'Leary

    2012-04-01

    Full Text Available A brief period of monocular deprivation in early postnatal life can alter the structure of neurons within deprived-eye-receiving layers of the dorsal lateral geniculate nucleus. The modification of structure is accompanied by a marked reduction in labeling for neurofilament, a protein that composes the stable cytoskeleton and that supports neuron structure. This study examined the extent of neurofilament recovery in monocularly deprived cats that either had their deprived eye opened (binocular recovery, or had the deprivation reversed to the fellow eye (reverse occlusion. The degree to which recovery was dependent on visually-driven activity was examined by placing monocularly deprived animals in complete darkness (dark rearing. The loss of neurofilament and the reduction of soma size caused by monocular deprivation were both ameliorated equally following either binocular recovery or reverse occlusion for 8 days. Though monocularly deprived animals placed in complete darkness showed recovery of soma size, there was a generalized loss of neurofilament labeling that extended to originally non-deprived layers. Overall, these results indicate that recovery of soma size is achieved by removal of the competitive disadvantage of the deprived eye, and occurred even in the absence of visually-driven activity. Recovery of neurofilament occurred when the competitive disadvantage of the deprived eye was removed, but unlike the recovery of soma size, was dependent upon visually-driven activity. The role of neurofilament in providing stable neural structure raises the intriguing possibility that dark rearing, which reduced overall neurofilament levels, could be used to reset the deprived visual system so as to make it more ameliorable with treatment by experiential manipulations.

  9. Long-Term Visual Training Increases Visual Acuity and Long-Term Monocular Deprivation Promotes Ocular Dominance Plasticity in Adult Standard Cage-Raised Mice.

    Science.gov (United States)

    Hosang, Leon; Yusifov, Rashad; Löwel, Siegrid

    2018-01-01

    For routine behavioral tasks, mice predominantly rely on olfactory cues and tactile information. In contrast, their visual capabilities appear rather restricted, raising the question whether they can improve if vision gets more behaviorally relevant. We therefore performed long-term training using the visual water task (VWT): adult standard cage (SC)-raised mice were trained to swim toward a rewarded grating stimulus so that using visual information avoided excessive swimming toward nonrewarded stimuli. Indeed, and in contrast to old mice raised in a generally enriched environment (Greifzu et al., 2016), long-term VWT training increased visual acuity (VA) on average by more than 30% to 0.82 cycles per degree (cyc/deg). In an individual animal, VA even increased to 1.49 cyc/deg, i.e., beyond the rat range of VAs. Since visual experience enhances the spatial frequency threshold of the optomotor (OPT) reflex of the open eye after monocular deprivation (MD), we also quantified monocular vision after VWT training. Monocular VA did not increase reliably, and eye reopening did not initiate a decline to pre-MD values as observed by optomotry; VA values rather increased by continued VWT training. Thus, optomotry and VWT measure different parameters of mouse spatial vision. Finally, we tested whether long-term MD induced ocular dominance (OD) plasticity in the visual cortex of adult [postnatal day (P)162-P182] SC-raised mice. This was indeed the case: 40-50 days of MD induced OD shifts toward the open eye in both VWT-trained and, surprisingly, also in age-matched mice without VWT training. These data indicate that (1) long-term VWT training increases adult mouse VA, and (2) long-term MD induces OD shifts also in adult SC-raised mice.

  10. Normative monocular visual acuity for early treatment diabetic retinopathy study charts in emmetropic children 5 to 12 years of age.

    Science.gov (United States)

    Dobson, Velma; Clifford-Donaldson, Candice E; Green, Tina K; Miller, Joseph M; Harvey, Erin M

    2009-07-01

    To provide normative data for children tested with Early Treatment Diabetic Retinopathy Study (ETDRS) charts. Cross-sectional study. A total of 252 Native American (Tohono O'odham) children aged 5 to 12 years. On the basis of cycloplegic refraction conducted on the day of testing, all were emmetropic (myopia < or =0.25 diopter [D] spherical equivalent, hyperopia < or =1.00 D spherical equivalent, and astigmatism < or =0.50 D in both eyes). Monocular visual acuity was tested at 4 m, using 1 ETDRS chart for the right eye (RE) and another for the left eye (LE). Visual acuity was scored as the total number of letters correctly identified, by naming or matching to letters on a lap card, and as the smallest letter size for which the child identified 3 of 5 letters correctly. Visual acuity results did not differ for the RE versus the LE, so data are reported for the RE only. Mean visual acuity for 5-year-olds (0.16 logarithm of the minimum angle of resolution [logMAR] [20/29]) was significantly worse than for 8-, 9-, 10-, 11-, and 12-year-olds (0.05 logMAR [20/22] or better at each age). The lower 95% prediction limit for determining whether a child has visual acuity within the normal range was 0.38 (20/48) for 5-year-olds and 0.30 (20/40) for 6- to 12-year-olds, which was reduced to 0.32 (20/42) for 5-year-olds and 0.21 (20/32) for 6- to 12-year-olds when recalculated with outlying data points removed. Mean interocular acuity difference did not vary by age, averaging less than 1 logMAR line at each age, with a lower 95% prediction limit of 0.17 log unit (1.7 logMAR lines) across all ages. For monocular visual acuity based on ETDRS charts to be in the normal range, it must be better than 20/50 for 5-year-olds and better than 20/40 for 6- to 12-year-olds. Normal interocular acuity difference includes values of less than 2 logMAR lines. Normative ETDRS visual acuity values are not as good as norms reported for adults, suggesting that a child's visual acuity results should

  11. Effects of brief daily periods of unrestricted vision during early monocular form deprivation on development of visual area 2.

    Science.gov (United States)

    Zhang, Bin; Tao, Xiaofeng; Wensveen, Janice M; Harwerth, Ronald S; Smith, Earl L; Chino, Yuzo M

    2011-09-14

    Providing brief daily periods of unrestricted vision during early monocular form deprivation reduces the depth of amblyopia. To gain insights into the neural basis of the beneficial effects of this treatment, the binocular and monocular response properties of neurons were quantitatively analyzed in visual area 2 (V2) of form-deprived macaque monkeys. Beginning at 3 weeks of age, infant monkeys were deprived of clear vision in one eye for 12 hours every day until 21 weeks of age. They received daily periods of unrestricted vision for 0, 1, 2, or 4 hours during the form-deprivation period. After behavioral testing to measure the depth of the resulting amblyopia, microelectrode-recording experiments were conducted in V2. The ocular dominance imbalance away from the affected eye was reduced in the experimental monkeys and was generally proportional to the reduction in the depth of amblyopia in individual monkeys. There were no interocular differences in the spatial properties of V2 neurons in any subject group. However, the binocular disparity sensitivity of V2 neurons was significantly higher and binocular suppression was lower in monkeys that had unrestricted vision. The decrease in ocular dominance imbalance in V2 was the neuronal change most closely associated with the observed reduction in the depth of amblyopia. The results suggest that the degree to which extrastriate neurons can maintain functional connections with the deprived eye (i.e., reducing undersampling for the affected eye) is the most significant factor associated with the beneficial effects of brief periods of unrestricted vision.

  12. Sudden visual loss after cardiac resynchronization therapy device implantation.

    Science.gov (United States)

    De Vitis, Luigi A; Marchese, Alessandro; Giuffrè, Chiara; Carnevali, Adriano; Querques, Lea; Tomasso, Livia; Baldin, Giovanni; Maestranzi, Gisella; Lattanzio, Rosangela; Querques, Giuseppe; Bandello, Francesco

    2017-03-10

    To report a case of sudden decrease in visual acuity possibly due to a cardiogenic embolism in a patient who underwent cardiac resynchronization therapy (CRT) device implantation. A 62-year-old man with severe left ventricular systolic dysfunction and a left bundle branch block was referred to our department because of a sudden decrease in visual acuity. Nine days earlier, he had undergone cardiac transapical implantation of a CRT device, which was followed, 2 days later, by an inflammatory reaction. The patient underwent several general and ophthalmologic examinations, including multimodal imaging. At presentation, right eye (RE) best-corrected visual acuity (BCVA) was counting fingers and RE pupil was hyporeactive. Fundus examination revealed white-centered hemorrhagic dots suggestive of Roth spots. Fluorescein angiography showed delay in vascular perfusion during early stage, late hyperfluorescence of the macula and optic disk, and peripheral perivascular leakage. The first visual field test showed complete loss of vision RE and a normal left eye. Due to suspected giant cell arteritis, temporal artery biopsy was performed. Thirty minutes after the procedure, an ischemic stroke with right hemisyndrome and aphasia occurred. The RE BCVA worsened to hands motion. Four months later, RE BCVA did not improve, despite improvement in fluorescein angiography inflammatory sign. We report a possible cardiogenic embolism secondary to undiagnosed infective endocarditis causing monocular visual loss after CRT device implantation. It remains unclear how the embolus caused severe functional damage without altering the retinal anatomical structure.

  13. Optic disc boundary segmentation from diffeomorphic demons registration of monocular fundus image sequences versus 3D visualization of stereo fundus image pairs for automated early stage glaucoma assessment

    Science.gov (United States)

    Gatti, Vijay; Hill, Jason; Mitra, Sunanda; Nutter, Brian

    2014-03-01

    Despite the current availability in resource-rich regions of advanced technologies in scanning and 3-D imaging in current ophthalmology practice, world-wide screening tests for early detection and progression of glaucoma still consist of a variety of simple tools, including fundus image-based parameters such as CDR (cup to disc diameter ratio) and CAR (cup to disc area ratio), especially in resource -poor regions. Reliable automated computation of the relevant parameters from fundus image sequences requires robust non-rigid registration and segmentation techniques. Recent research work demonstrated that proper non-rigid registration of multi-view monocular fundus image sequences could result in acceptable segmentation of cup boundaries for automated computation of CAR and CDR. This research work introduces a composite diffeomorphic demons registration algorithm for segmentation of cup boundaries from a sequence of monocular images and compares the resulting CAR and CDR values with those computed manually by experts and from 3-D visualization of stereo pairs. Our preliminary results show that the automated computation of CDR and CAR from composite diffeomorphic segmentation of monocular image sequences yield values comparable with those from the other two techniques and thus may provide global healthcare with a cost-effective yet accurate tool for management of glaucoma in its early stage.

  14. Seeing the sound after visual loss: functional MRI in acquired auditory-visual synesthesia.

    Science.gov (United States)

    Yong, Zixin; Hsieh, Po-Jang; Milea, Dan

    2017-02-01

    Acquired auditory-visual synesthesia (AVS) is a rare neurological sign, in which specific auditory stimulation triggers visual experience. In this study, we used event-related fMRI to explore the brain regions correlated with acquired monocular sound-induced phosphenes, which occurred 2 months after unilateral visual loss due to an ischemic optic neuropathy. During the fMRI session, 1-s pure tones at various pitches were presented to the patient, who was asked to report occurrence of sound-induced phosphenes by pressing one of the two buttons (yes/no). The brain activation during phosphene-experienced trials was contrasted with non-phosphene trials and compared to results obtained in one healthy control subject who underwent the same fMRI protocol. Our results suggest, for the first time, that acquired AVS occurring after visual impairment is associated with bilateral activation of primary and secondary visual cortex, possibly due to cross-wiring between auditory and visual sensory modalities.

  15. Monocular perceptual learning of contrast detection facilitates binocular combination in adults with anisometropic amblyopia.

    Science.gov (United States)

    Chen, Zidong; Li, Jinrong; Liu, Jing; Cai, Xiaoxiao; Yuan, Junpeng; Deng, Daming; Yu, Minbin

    2016-02-01

    Perceptual learning in contrast detection improves monocular visual function in adults with anisometropic amblyopia; however, its effect on binocular combination remains unknown. Given that the amblyopic visual system suffers from pronounced binocular functional loss, it is important to address how the amblyopic visual system responds to such training strategies under binocular viewing conditions. Anisometropic amblyopes (n = 13) were asked to complete two psychophysical supra-threshold binocular summation tasks: (1) binocular phase combination and (2) dichoptic global motion coherence before and after monocular training to investigate this question. We showed that these participants benefited from monocular training in terms of binocular combination. More importantly, the improvements observed with the area under log CSF (AULCSF) were found to be correlated with the improvements in binocular phase combination.

  16. Monocular perceptual learning of contrast detection facilitates binocular combination in adults with anisometropic amblyopia

    OpenAIRE

    Chen, Zidong; Li, Jinrong; Liu, Jing; Cai, Xiaoxiao; Yuan, Junpeng; Deng, Daming; Yu, Minbin

    2016-01-01

    Perceptual learning in contrast detection improves monocular visual function in adults with anisometropic amblyopia; however, its effect on binocular combination remains unknown. Given that the amblyopic visual system suffers from pronounced binocular functional loss, it is important to address how the amblyopic visual system responds to such training strategies under binocular viewing conditions. Anisometropic amblyopes (n?=?13) were asked to complete two psychophysical supra-threshold binoc...

  17. How does glaucoma look?: patient perception of visual field loss.

    Science.gov (United States)

    Crabb, David P; Smith, Nicholas D; Glen, Fiona C; Burton, Robyn; Garway-Heath, David F

    2013-06-01

    To explore patient perception of vision loss in glaucoma and, specifically, to test the hypothesis that patients do not recognize their impairment as a black tunnel effect or as black patches in their field of view. Clinic-based cross-sectional study. Fifty patients (age range, 52-82 years) with visual acuity better than 20/30 and with a range of glaucomatous visual field (VF) defects in both eyes, excluding those with very advanced disease (perimetrically blind). Participants underwent monocular VF testing in both eyes using a Humphrey Field Analyzer (HFA; Carl Zeiss Meditec, Dublin, CA; 24-2 Swedish interactive threshold algorithm standard tests) and other tests of visual function. Participants took part in a recorded interview during which they were asked if they were aware of their VF loss; if so, there were encouraged to describe it in their own words. Participants were shown 6 images modified in a variety of ways on a computer monitor and were asked to select the image that most closely represented their perception of their VF loss. Forced choice of an image best representing glaucomatous vision impairment. Participants had a range of VF defect severity: average HFA mean deviation was -8.7 dB (standard deviation [SD], 5.8 dB) and -10.5 dB (SD, 7.1 dB) in the right and left eyes, respectively. Thirteen patients (26%; 95% confidence interval [CI], 15%-40%) reported being completely unaware of their vision loss. None of the patients chose the images with a distinct black tunnel effect or black patches. Only 2 patients (4%; 95% CI, 0%-14%) chose the image with a tunnel effect with blurred edges. An image depicting blurred patches and another with missing patches was chosen by 54% (95% CI, 39%-68%) and 16% (95% CI, 7%-29%) of the patients, respectively. Content analysis of the transcripts from the recorded interviews indicated a frequent use of descriptors of visual symptoms associated with reported blur and missing features. Patients with glaucoma do not perceive

  18. Causes of visual loss in uveitis

    Directory of Open Access Journals (Sweden)

    Stanković Zora

    2009-01-01

    Full Text Available Background/Aim. Epidemiological studies of blindness in a working age population require a precise definition of the true connection of uveitis and visual damage. Since most patients with more severe types of uveitis are hospitalized in tertiary referral uveitis service, our aim was to determine whether age, sex and age of onset of uveitis, as well as duration of visual loss and its causes influence the degree of visual damage in patients with different types of uveitis. Methods. The data were collected from medical records of 237 patients at the Department for Uveitis of the Institute for Eye Diseases in Belgrade over a three-year period (March 2005 to March 2008. Results. Visual acuity reduction (≤ 0.3 was found in 161/237 (67.9% patients, 85 of whom had visual acuity of ≤ 0.1 later. Working age patients (up to 60 years of age most often suffered from uveitis (173/237; 73%. The highest number of patients with visual loss was in the group suffering from panuveitis (77/94; 81.91%. The age of onset of uveitis and sex have no statistically significant influence on visual loss. The most common causes of visual loss (34/161; 21.1% were cystoid macular oedema (CMO (43/161; 26.7%, cataract (28/161; 17.39% and combination of CMO and cataract. Conclusion. The risk factors for severe visual loss (≤ 0.1 are panuveitis, bilateral inflammation, prolonged visual reduction and a significant number of relapses. The main causes of visual loss in 65.2% of our patients were CMO and cataract.

  19. Loss of Binocular Vision in Monocularly Blind Patients Causes Selective Degeneration of the Superior Lateral Occipital Cortices

    NARCIS (Netherlands)

    Prins, Doety D; Jansonius, Nomdo M.; Cornelissen, Frans W.

    2017-01-01

    PURPOSE. Chronic ocular pathology, such as glaucoma and macular degeneration, is associated with neuroanatomic changes in the visual pathways. It is a challenge to determine the mechanism responsible for these changes. This could be functional deprivation or transsynaptic degeneration. Acquired

  20. A switch from inter-ocular to inter-hemispheric suppression following monocular deprivation in the rat visual cortex

    NARCIS (Netherlands)

    Pietrasanta, M.; Restani, L.; Cerri, C.; Olcese, U.; Medini, P.; Caleo, M.

    2014-01-01

    Binocularity is a key property of primary visual cortex (V1) neurons that is widely used to study synaptic integration in the brain and plastic mechanisms following an altered visual experience. However, it is not clear how the inputs from the two eyes converge onto binocular neurons, and how their

  1. The Effect of Long Term Monocular Occlusion on Vernier Threshold: Elasticity in the Young Adult Visual System.

    Science.gov (United States)

    1986-06-01

    susceptible to an abnormal visual experience, is still not well defined but of importance in the treatment of amblyopia and other anomalies that cause...Toward a New Pupillary Aper- ture", Invest. Opthalmol. Vis. Sci., Dec. 1981, Vol.21, No. 6, pp 869-873. 3. Awaya, S., et. al., " Amblyopia in Man...be- lieve that the attrition of X-cells in the LGB provides a new demonstration of neural plasticity in the adult visual system. (13) Creutzfeldt and

  2. [Visual evoked potentials produced by monocular flash stimuli in the cerebral cortex of the rabbit. I. Typography].

    Science.gov (United States)

    Pérez-Cobo, J C; Ruiz-Beramendi, M; Pérez-Arroyo, M

    1990-12-01

    The visually evoked potentials in the hemisphere contralateral to the stimulated eye in rabbit, can be described topographically as follows. While a positive wave (P1) begins forming in the anterior zones and in the V I binocular zone, the N0 wave, at times very large, is produced in a more occipital zone, which corresponds to the visual streak. Immediately afterwards, the positivity, P1, practically invades the whole of the hemisphere. After this, the N1 wave which is produced in the most posterior parts of the V I, begins forming. The whole phenomenon comes to an end when the P2 wave is generated in the most occipital zones.

  3. Long-Term Visual Training Increases Visual Acuity and Long-Term Monocular Deprivation Promotes Ocular Dominance Plasticity in Adult Standard Cage-Raised Mice

    OpenAIRE

    Hosang, Leon; Yusifov, Rashad; Löwel, Siegrid

    2018-01-01

    Abstract For routine behavioral tasks, mice predominantly rely on olfactory cues and tactile information. In contrast, their visual capabilities appear rather restricted, raising the question whether they can improve if vision gets more behaviorally relevant. We therefore performed long-term training using the visual water task (VWT): adult standard cage (SC)-raised mice were trained to swim toward a rewarded grating stimulus so that using visual information avoided excessive swimming toward ...

  4. Distributed Monocular SLAM for Indoor Map Building

    OpenAIRE

    Ruwan Egodagamage; Mihran Tuceryan

    2017-01-01

    Utilization and generation of indoor maps are critical elements in accurate indoor tracking. Simultaneous Localization and Mapping (SLAM) is one of the main techniques for such map generation. In SLAM an agent generates a map of an unknown environment while estimating its location in it. Ubiquitous cameras lead to monocular visual SLAM, where a camera is the only sensing device for the SLAM process. In modern applications, multiple mobile agents may be involved in the generation of such maps,...

  5. Layer 2/3 synapses in monocular and binocular regions of tree shrew visual cortex express mAChR-dependent long-term depression and long-term potentiation.

    Science.gov (United States)

    McCoy, Portia; Norton, Thomas T; McMahon, Lori L

    2008-07-01

    Acetylcholine is an important modulator of synaptic efficacy and is required for learning and memory tasks involving the visual cortex. In rodent visual cortex, activation of muscarinic acetylcholine receptors (mAChRs) induces a persistent long-term depression (LTD) of transmission at synapses recorded in layer 2/3 of acute slices. Although the rodent studies expand our knowledge of how the cholinergic system modulates synaptic function underlying learning and memory, they are not easily extrapolated to more complex visual systems. Here we used tree shrews for their similarities to primates, including a visual cortex with separate, defined regions of monocular and binocular innervation, to determine whether mAChR activation induces long-term plasticity. We find that the cholinergic agonist carbachol (CCh) not only induces long-term plasticity, but the direction of the plasticity depends on the subregion. In the monocular region, CCh application induces LTD of the postsynaptic potential recorded in layer 2/3 that requires activation of m3 mAChRs and a signaling cascade that includes activation of extracellular signal-regulated kinase (ERK) 1/2. In contrast, layer 2/3 postsynaptic potentials recorded in the binocular region express long-term potentiation (LTP) following CCh application that requires activation of m1 mAChRs and phospholipase C. Our results show that activation of mAChRs induces long-term plasticity at excitatory synapses in tree shrew visual cortex. However, depending on the ocular inputs to that region, variation exists as to the direction of plasticity, as well as to the specific mAChR and signaling mechanisms that are required.

  6. Monocular Elevation Deficiency - Double Elevator Palsy

    Science.gov (United States)

    ... Español Condiciones Chinese Conditions Monocular Elevation Deficiency/ Double Elevator Palsy En Español Read in Chinese What is monocular elevation deficiency (Double Elevator Palsy)? Monocular Elevation Deficiency, also known by the ...

  7. A Case of Complete Recovery of Fluctuating Monocular Blindness Following Endovascular Treatment in Internal Carotid Artery Dissection.

    Science.gov (United States)

    Kim, Ki-Tae; Baik, Seung Guk; Park, Kyung-Pil; Park, Min-Gyu

    2015-09-01

    Monocular blindness may appear as the first symptom of internal carotid artery dissection (ICAD). However, there have been no reports that monocular visual loss repeatedly occurs and disappears in response to postural change in ICAD. A 33-year-old woman presented with transient monocular blindness (TMB) following acute-onset headache. TMB repeatedly occurred in response to postural change. Two days later, she experienced transient dysarthria and right hemiparesis in upright position. Pupil size and light reflex were normal, but a relative afferent pupillary defect was positive in the left eye. Diffusion-weighted imaging showed no acute lesion, but perfusion-weighted imaging showed perfusion delay in the left ICA territory. Digital subtraction angiography demonstrated a false lumen and an intraluminal filling defect in proximal segment of the left ICA. Carotid stenting was performed urgently. After carotid stenting, left relative afferent pupillary defect disappeared and TMB was not provoked anymore by upright posture. At discharge, left visual acuity was completely normalized. Because fluctuating visual symptoms in the ICAD may be associated with hemodynamically unstable status, assessment of the perfusion status should be done quickly. Carotid stenting may be helpful to improve the fluctuating visual symptoms and hemodynamically unstable status in selected patient with the ICAD. Copyright © 2015 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  8. Action Control: Independent Effects of Memory and Monocular Viewing on Reaching Accuracy

    Science.gov (United States)

    Westwood, D.A.; Robertson, C.; Heath, M.

    2005-01-01

    Evidence suggests that perceptual networks in the ventral visual pathway are necessary for action control when targets are viewed with only one eye, or when the target must be stored in memory. We tested whether memory-linked (i.e., open-loop versus memory-guided actions) and monocular-linked effects (i.e., binocular versus monocular actions) on…

  9. Loss of vision: imaging the visual pathways

    International Nuclear Information System (INIS)

    Jaeger, H.R.

    2005-01-01

    This is an overview of diseases presenting with visual impairment, which aims to provide an understanding of the anatomy and pathology of the visual pathways. It discusses the relevant clinical background and neuroimaging findings on CT and standard and advanced MRI of diseases affecting the globe; optic nerve/sheath complex; optic chiasm, tract and radiation; and visual cortex. The overview covers common tumours, trauma, inflammatory and vascular pathology, and conditions such as benign intracranial hypertension and posterior reversible leukoencephalopathy syndrome. (orig.)

  10. Grey and white matter changes in children with monocular amblyopia: voxel-based morphometry and diffusion tensor imaging study.

    Science.gov (United States)

    Li, Qian; Jiang, Qinying; Guo, Mingxia; Li, Qingji; Cai, Chunquan; Yin, Xiaohui

    2013-04-01

    To investigate the potential morphological alterations of grey and white matter in monocular amblyopic children using voxel-based morphometry (VBM) and diffusion tensor imaging (DTI). A total of 20 monocular amblyopic children and 20 age-matched controls were recruited. Whole-brain MRI scans were performed after a series of ophthalmologic exams. The imaging data were processed and two-sample t-tests were employed to identify group differences in grey matter volume (GMV), white matter volume (WMV) and fractional anisotropy (FA). After image screening, there were 12 amblyopic participants and 15 normal controls qualified for the VBM analyses. For DTI analysis, 14 amblyopes and 14 controls were included. Compared to the normal controls, reduced GMVs were observed in the left inferior occipital gyrus, the bilateral parahippocampal gyrus and the left supramarginal/postcentral gyrus in the monocular amblyopic group, with the lingual gyrus presenting augmented GMV. Meanwhile, WMVs reduced in the left calcarine, the bilateral inferior frontal and the right precuneus areas, and growth in the WMVs was seen in the right cuneus, right middle occipital and left orbital frontal areas. Diminished FA values in optic radiation and increased FA in the left middle occipital area and right precuneus were detected in amblyopic patients. In monocular amblyopia, cortices related to spatial vision underwent volume loss, which provided neuroanatomical evidence of stereoscopic defects. Additionally, white matter development was also hindered due to visual defects in amblyopes. Growth in the GMVs, WMVs and FA in the occipital lobe and precuneus may reflect a compensation effect by the unaffected eye in monocular amblyopia.

  11. Selective loss of orientation column maps in visual cortex during brief elevation of intraocular pressure.

    Science.gov (United States)

    Chen, Xin; Sun, Chao; Huang, Luoxiu; Shou, Tiande

    2003-01-01

    To compare the orientation column maps elicited by different spatial frequency gratings in cortical area 17 of cats before and during brief elevation of intraocular pressure (IOP). IOP was elevated by injecting saline into the anterior chamber of a cat's eye through a syringe needle. The IOP was elevated enough to cause a retinal perfusion pressure (arterial pressure minus IOP) of approximately 30 mm Hg during a brief elevation of IOP. The visual stimulus gratings were varied in spatial frequency, whereas other parameters were kept constant. The orientation column maps of the cortical area 17 were monocularly elicited by drifting gratings of different spatial frequencies and revealed by a brain intrinsic signal optical imaging system. These maps were compared before and during short-term elevation of IOP. The response amplitude of the orientation maps in area 17 decreased during a brief elevation of IOP. This decrease was dependent on the retinal perfusion pressure but not on the absolute IOP. The location of the most visible maps was spatial-frequency dependent. The blurring or loss of the pattern of the orientation maps was most severe when high-spatial-frequency gratings were used and appeared most significantly on the posterior part of the exposed cortex while IOP was elevated. However, the basic patterns of the maps remained unchanged. Changes in cortical signal were not due to changes in the optics of the eye with elevation of IOP. A stable normal IOP is essential for maintaining normal visual cortical functions. During a brief and high elevation of IOP, the cortical processing of high-spatial-frequency visual information was diminished because of a selectively functional decline of the retinogeniculocortical X pathway by a mechanism of retinal circulation origin.

  12. Monocular channels have a functional role in endogenous orienting.

    Science.gov (United States)

    Saban, William; Sekely, Liora; Klein, Raymond M; Gabay, Shai

    2018-03-01

    The literature has long emphasized the role of higher cortical structures in endogenous orienting. Based on evolutionary explanation and previous data, we explored the possibility that lower monocular channels may also have a functional role in endogenous orienting of attention. Sensitive behavioral manipulation was used to probe the contribution of monocularly segregated regions in a simple cue - target detection task. A central spatially informative cue, and its ensuing target, were presented to the same or different eyes at varying cue-target intervals. Results indicated that the onset of endogenous orienting was apparent earlier when the cue and target were presented to the same eye. The data provides converging evidence for the notion that endogenous facilitation is modulated by monocular portions of the visual stream. This, in turn, suggests that higher cortical mechanisms are not exclusively responsible for endogenous orienting, and that a dynamic interaction between higher and lower neural levels, might be involved. Copyright © 2018 Elsevier Ltd. All rights reserved.

  13. 3D display system using monocular multiview displays

    Science.gov (United States)

    Sakamoto, Kunio; Saruta, Kazuki; Takeda, Kazutoki

    2002-05-01

    A 3D head mounted display (HMD) system is useful for constructing a virtual space. The authors have researched the virtual-reality systems connected with computer networks for real-time remote control and developed a low-priced real-time 3D display for building these systems. We developed a 3D HMD system using monocular multi-view displays. The 3D displaying technique of this monocular multi-view display is based on the concept of the super multi-view proposed by Kajiki at TAO (Telecommunications Advancement Organization of Japan) in 1996. Our 3D HMD has two monocular multi-view displays (used as a visual display unit) in order to display a picture to the left eye and the right eye. The left and right images are a pair of stereoscopic images for the left and right eyes, then stereoscopic 3D images are observed.

  14. SPECT in patients with cortical visual loss.

    Science.gov (United States)

    Silverman, I E; Galetta, S L; Gray, L G; Moster, M; Atlas, S W; Maurer, A H; Alavi, A

    1993-09-01

    Single-photon emission computed tomography (SPECT) with 99mTc-hexamethylpropyleneamine oxime (HMPAO) was used to investigate changes in cerebral blood flow in seven patients with cortical visual impairment. Traumatic brain injury (TBI) was the cause of cortical damage in two patients, cerebral ischemia in two patients and carbon monoxide (CO) poisoning, status epilepticus and Alzheimer's Disease (AD) each in three separate patients. The SPECT scans of the seven patients were compared to T2-weighted magnetic resonance image (MRI) scans of the brain to determine the correlation between functional and anatomical findings. In six of the seven patients, the qualitative interpretation of the SPECT studies supported the clinical findings (i.e., the visual field defect) by revealing altered regional cerebral blood flow (rCBF) in the appropriate regions of the visual pathway. MR scans in all of the patients, on the other hand, were either normal or disclosed smaller lesions than those detected by SPECT. We conclude that SPECT may reveal altered rCBF in patients with cortical visual impairment of various etiologies, even when MRI studies are normal or nondiagnostic.

  15. Relating binocular and monocular vision in strabismic and anisometropic amblyopia.

    Science.gov (United States)

    Agrawal, Ritwick; Conner, Ian P; Odom, J V; Schwartz, Terry L; Mendola, Janine D

    2006-06-01

    To examine deficits in monocular and binocular vision in adults with amblyopia and to test the following 2 hypotheses: (1) Regardless of clinical subtype, the degree of impairment in binocular integration predicts the pattern of monocular acuity deficits. (2) Subjects who lack binocular integration exhibit the most severe interocular suppression. Seven subjects with anisometropia, 6 subjects with strabismus, and 7 control subjects were tested. Monocular tests included Snellen acuity, grating acuity, Vernier acuity, and contrast sensitivity. Binocular tests included Titmus stereo test, binocular motion integration, and dichoptic contrast masking. As expected, both groups showed deficits in monocular acuity, with subjects with strabismus showing greater deficits in Vernier acuity. Both amblyopic groups were then characterized according to the degree of residual stereoacuity and binocular motion integration ability, and 67% of subjects with strabismus compared with 29% of subjects with anisometropia were classified as having "nonbinocular" vision according to our criterion. For this nonbinocular group, Vernier acuity is most impaired. In addition, the nonbinocular group showed the most dichoptic contrast masking of the amblyopic eye and the least dichoptic contrast masking of the fellow eye. The degree of residual binocularity and interocular suppression predicts monocular acuity and may be a significant etiological mechanism of vision loss.

  16. Short-Term Monocular Deprivation Enhances Physiological Pupillary Oscillations

    Directory of Open Access Journals (Sweden)

    Paola Binda

    2017-01-01

    Full Text Available Short-term monocular deprivation alters visual perception in adult humans, increasing the dominance of the deprived eye, for example, as measured with binocular rivalry. This form of plasticity may depend upon the inhibition/excitation balance in the visual cortex. Recent work suggests that cortical excitability is reliably tracked by dilations and constrictions of the pupils of the eyes. Here, we ask whether monocular deprivation produces a systematic change of pupil behavior, as measured at rest, that is independent of the change of visual perception. During periods of minimal sensory stimulation (in the dark and task requirements (minimizing body and gaze movements, slow pupil oscillations, “hippus,” spontaneously appear. We find that hippus amplitude increases after monocular deprivation, with larger hippus changes in participants showing larger ocular dominance changes (measured by binocular rivalry. This tight correlation suggests that a single latent variable explains both the change of ocular dominance and hippus. We speculate that the neurotransmitter norepinephrine may be implicated in this phenomenon, given its important role in both plasticity and pupil control. On the practical side, our results indicate that measuring the pupil hippus (a simple and short procedure provides a sensitive index of the change of ocular dominance induced by short-term monocular deprivation, hence a proxy for plasticity.

  17. Visual Memory for Objects Following Foveal Vision Loss

    Science.gov (United States)

    Geringswald, Franziska; Herbik, Anne; Hofmüller, Wolfram; Hoffmann, Michael B.; Pollmann, Stefan

    2015-01-01

    Allocation of visual attention is crucial for encoding items into visual long-term memory. In free vision, attention is closely linked to the center of gaze, raising the question whether foveal vision loss entails suboptimal deployment of attention and subsequent impairment of object encoding. To investigate this question, we examined visual…

  18. [Acute visual loss in pregnancy caused by craniopharyngioma].

    Science.gov (United States)

    Grillo-Mallo, E; Jiménez-Benito, J; Diéz-Feijóo, E; Alonso Alonso, I; Ferrero Collado, A; Muñoz Quiñones, S

    2014-04-01

    A 38-year-old female, at 20-weeks gestation, experienced a sudden visual loss and visual-field abnormalities. The neuroimaging tests showed a craniopharyngioma. Surgical removal was performed with a successful outcome as regards the pregnancy and visual function. It is known that pituitary adenomas may grow during pregnancy; however this is unusual in craniopharyngiomas. They usually present with visual problems due to their suprasellar topography. Surgery is the treatment of choice, the outcome essentially depending on its complete resection. Copyright © 2010 Sociedad Española de Oftalmología. Published by Elsevier Espana. All rights reserved.

  19. Distributed Monocular SLAM for Indoor Map Building

    Directory of Open Access Journals (Sweden)

    Ruwan Egodagamage

    2017-01-01

    Full Text Available Utilization and generation of indoor maps are critical elements in accurate indoor tracking. Simultaneous Localization and Mapping (SLAM is one of the main techniques for such map generation. In SLAM an agent generates a map of an unknown environment while estimating its location in it. Ubiquitous cameras lead to monocular visual SLAM, where a camera is the only sensing device for the SLAM process. In modern applications, multiple mobile agents may be involved in the generation of such maps, thus requiring a distributed computational framework. Each agent can generate its own local map, which can then be combined into a map covering a larger area. By doing so, they can cover a given environment faster than a single agent. Furthermore, they can interact with each other in the same environment, making this framework more practical, especially for collaborative applications such as augmented reality. One of the main challenges of distributed SLAM is identifying overlapping maps, especially when relative starting positions of agents are unknown. In this paper, we are proposing a system having multiple monocular agents, with unknown relative starting positions, which generates a semidense global map of the environment.

  20. Experience and information loss in auditory and visual memory.

    Science.gov (United States)

    Gloede, Michele E; Paulauskas, Emily E; Gregg, Melissa K

    2017-07-01

    Recent studies show that recognition memory for sounds is inferior to memory for pictures. Four experiments were conducted to examine the nature of auditory and visual memory. Experiments 1-3 were conducted to evaluate the role of experience in auditory and visual memory. Participants received a study phase with pictures/sounds, followed by a recognition memory test. Participants then completed auditory training with each of the sounds, followed by a second memory test. Despite auditory training in Experiments 1 and 2, visual memory was superior to auditory memory. In Experiment 3, we found that it is possible to improve auditory memory, but only after 3 days of specific auditory training and 3 days of visual memory decay. We examined the time course of information loss in auditory and visual memory in Experiment 4 and found a trade-off between visual and auditory recognition memory: Visual memory appears to have a larger capacity, while auditory memory is more enduring. Our results indicate that visual and auditory memory are inherently different memory systems and that differences in visual and auditory recognition memory performance may be due to the different amounts of experience with visual and auditory information, as well as structurally different neural circuitry specialized for information retention.

  1. Visual loss at presentation in children with pseudotumor cerebri

    Directory of Open Access Journals (Sweden)

    Rana Al-Senawi

    2008-01-01

    Full Text Available Purpose: To describe visual loss at presentation in children with pseudotumor cerebri (PTC, and discuss mechanisms of visual loss and distinguishing features of pediatric PTC. Materials and Methods: Two children with papilledema and visual complaints were referred for ophthalmic evaluation. Both patients underwent a detailed ophthalmic work-up. Results: Patient 1, an 8-year-old girl, presented with a 2-week history of headache, vomiting, and visual impairment in both eyes. The child had no previous medical history. Patient 2, a 9-year-old boy, experienced sudden loss of vision in both eyes one week prior to presentation, along with severe headache and vomiting. He had undergone a renal transplantation one year back, and his current medications included cyclosporine A (CsA and oral prednisolone. Extensive disc swelling, lipid exudation and retinal thickening in the posterior pole were observed in both patients. Lumbar puncture in both showed elevated cerebrospinal fluid pressure. Both were treated with oral acetazolamide. Patient 1 additionally received intravenous methylprednisolone followed by an oral taper. CsA was stopped in patient 2. PTC and papilledema resolved with above measures in both patients, with partial recovery of visual function. Conclusions: PTC in children may have atypical manifestations. Visual acuity may be compromised acutely due to several factors. Patients with PTC and severe visual loss at presentation mandate an aggressive management approach. Use of intravenous steroids may be considered along with acetazolamide. Despite resolution of PTC, sequelae such as optic atrophy or macular scarring may impede eventual visual recovery. Physicians following patients on CsA need to be aware of the possible neuro-ophthalmic complications of the drug.

  2. Visual and proprioceptive interaction in patients with bilateral vestibular loss.

    Science.gov (United States)

    Cutfield, Nicholas J; Scott, Gregory; Waldman, Adam D; Sharp, David J; Bronstein, Adolfo M

    2014-01-01

    Following bilateral vestibular loss (BVL) patients gradually adapt to the loss of vestibular input and rely more on other sensory inputs. Here we examine changes in the way proprioceptive and visual inputs interact. We used functional magnetic resonance imaging (fMRI) to investigate visual responses in the context of varying levels of proprioceptive input in 12 BVL subjects and 15 normal controls. A novel metal-free vibrator was developed to allow vibrotactile neck proprioceptive input to be delivered in the MRI system. A high level (100 Hz) and low level (30 Hz) control stimulus was applied over the left splenius capitis; only the high frequency stimulus generates a significant proprioceptive stimulus. The neck stimulus was applied in combination with static and moving (optokinetic) visual stimuli, in a factorial fMRI experimental design. We found that high level neck proprioceptive input had more cortical effect on brain activity in the BVL patients. This included a reduction in visual motion responses during high levels of proprioceptive input and differential activation in the midline cerebellum. In early visual cortical areas, the effect of high proprioceptive input was present for both visual conditions but in lateral visual areas, including V5/MT, the effect was only seen in the context of visual motion stimulation. The finding of a cortical visuo-proprioceptive interaction in BVL patients is consistent with behavioural data indicating that, in BVL patients, neck afferents partly replace vestibular input during the CNS-mediated compensatory process. An fMRI cervico-visual interaction may thus substitute the known visuo-vestibular interaction reported in normal subject fMRI studies. The results provide evidence for a cortical mechanism of adaptation to vestibular failure, in the form of an enhanced proprioceptive influence on visual processing. The results may provide the basis for a cortical mechanism involved in proprioceptive substitution of vestibular

  3. Monocular Perceptual Deprivation from Interocular Suppression Temporarily Imbalances Ocular Dominance.

    Science.gov (United States)

    Kim, Hyun-Woong; Kim, Chai-Youn; Blake, Randolph

    2017-03-20

    Early visual experience sculpts neural mechanisms that regulate the balance of influence exerted by the two eyes on cortical mechanisms underlying binocular vision [1, 2], and experience's impact on this neural balancing act continues into adulthood [3-5]. One recently described, compelling example of adult neural plasticity is the effect of patching one eye for a relatively short period of time: contrary to intuition, monocular visual deprivation actually improves the deprived eye's competitive advantage during a subsequent period of binocular rivalry [6-8], the robust form of visual competition prompted by dissimilar stimulation of the two eyes [9, 10]. Neural concomitants of this improvement in monocular dominance are reflected in measurements of brain responsiveness following eye patching [11, 12]. Here we report that patching an eye is unnecessary for producing this paradoxical deprivation effect: interocular suppression of an ordinarily visible stimulus being viewed by one eye is sufficient to produce shifts in subsequent predominance of that eye to an extent comparable to that produced by patching the eye. Moreover, this imbalance in eye dominance can also be induced by prior, extended viewing of two monocular images differing only in contrast. Regardless of how shifts in eye dominance are induced, the effect decays once the two eyes view stimuli equal in strength. These novel findings implicate the operation of interocular neural gain control that dynamically adjusts the relative balance of activity between the two eyes [13, 14]. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Hard Retinal exudates and visual loss due to papilledema

    International Nuclear Information System (INIS)

    Rush, J.A.

    1982-01-01

    Bilateral papilledema developed in a patient with a cystic, grade 3 astrocytoma of the right frontal lobe. Despite successful neurosurgical treatment, 60 Co radiotherapy, and oral corticosteroid therapy, progressive visual loss occurred. At examination one year later, visual activity was 20/200 and 20/70, and extensive lipid exudates in the peripapillary retina and central macula of each eye were noted. Retinal lipid exudates rarely complicate the course of surviving patients who had papilledema from intracranial tumor; physicians involved in the multispecialty care of such patients should be aware of the possible ocular residuals of persistent papilledema in an otherwise successfully treated patient

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

    OpenAIRE

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

    2016-01-01

    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...

  6. Visual loss in a school for the blind in Nigeria.

    Science.gov (United States)

    Okoye, O I; Aghaji, A E; Ikojo, I N

    2009-01-01

    There are an estimated 1.4 million blind children worldwide, it has been observed that almost 90% of the so-called blind population (children inclusive) do not have total loss of visual function, but retain a degree of usable residual vision. The study aims to determined the sites and causes of visual loss in the students of a school for the blind in Nigeria, and also the proportion of those students who could benefit from low vision devices. Forty-five students of the school were examined using the standard World Health Organization/Prevention of blindness examination record for childhood blindness. Refraction and assessment for low vision devices were conducted, where necessary. Glaucoma/buphthalmos (22.2%) and corneal lesions (20%) were the major causes of vision loss. Six students (13.3%) benefited from spectacles and/or low vision devices. Glaucoma/buphthalmos is assuming great significance in this study population, though most of the causes of vision loss are avoidable (77.7%). There is need for low vision service in the schools for the blind in South East Nigeria.

  7. Dichoptic training in adults with amblyopia: Additional stereoacuity gains over monocular training.

    Science.gov (United States)

    Liu, Xiang-Yun; Zhang, Jun-Yun

    2017-08-04

    Dichoptic training is a recent focus of research on perceptual learning in adults with amblyopia, but whether and how dichoptic training is superior to traditional monocular training is unclear. Here we investigated whether dichoptic training could further boost visual acuity and stereoacuity in monocularly well-trained adult amblyopic participants. During dichoptic training the participants used the amblyopic eye to practice a contrast discrimination task, while a band-filtered noise masker was simultaneously presented in the non-amblyopic fellow eye. Dichoptic learning was indexed by the increase of maximal tolerable noise contrast for successful contrast discrimination in the amblyopic eye. The results showed that practice tripled maximal tolerable noise contrast in 13 monocularly well-trained amblyopic participants. Moreover, the training further improved stereoacuity by 27% beyond the 55% gain from previous monocular training, but unchanged visual acuity of the amblyopic eyes. Therefore our dichoptic training method may produce extra gains of stereoacuity, but not visual acuity, in adults with amblyopia after monocular training. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Information loss in visual assessments of medical images

    International Nuclear Information System (INIS)

    Niimi, Takanaga; Imai, Kuniharu; Maeda, Hisatoshi; Ikeda, Mitsuru

    2007-01-01

    We applied information theory to quantify information losses in assessing contrast-detail (C-D) analysis. Images of a C-D phantom were acquired with a flat panel detector (FPD) and a computed radiography (CR) by changing surface entrance doses. Six phantom radiographs (FPD: five images; CR: one image) were prepared for visual evaluations. Thirteen radiographers and two radiologists participated in the observation test. Detectability was defined as the shortest length of the cylinders of which border the observers could recognize from the background, and was recorded using row number. Information content was defined as the entropy Σp i log(1/p i ) with detection probabilities p i , which were calculated from distribution of detection rate of the ith column. Information loss, in unit of bits, was calculated as the difference between information obtained and information content when all the columns were detected. The information losses decreased with the increase in cylinder diameters and with the increase in surface entrance dose. Because the information loss varies depending on distribution of detection rate, this method of using the information theory was expected to be more sensitive in evaluating the C-D image quality than using the averaged values of detectability

  9. 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.

  10. Attitudes towards and perceptions of visual loss and its causes among Hong Kong Chinese adults.

    Science.gov (United States)

    Lau, Joseph Tak Fai; Lee, Vincent; Fan, Dorothy; Lau, Mason; Michon, John

    2004-06-01

    As part of a study of visual function among Hong Kong Chinese adults, their attitudes and perceptions related to visual loss were examined. These included fear of visual loss, negative functional impacts of visual loss, the relationship between ageing and visual loss and help-seeking behaviours related to visual loss. Demographic factors associated with these variables were also studied. The study population were people aged 40 and above randomly selected from the Shatin district of Hong Kong. The participants underwent eye examinations that included visual acuity, intraocular pressure measurement, visual field, slit-lamp biomicroscopy and ophthalmoscopy. The primary cause of visual disability was recorded. The participants were also asked about their attitudes and perceptions regarding visual loss using a structured questionnaire. The prevalence of bilateral visual disability was 2.2% among adults aged 40 or above and 6.4% among adults aged 60 or above. Nearly 36% of the participants selected blindness as the most feared disabling medical condition, which was substantially higher than conditions such as dementia, loss of limbs, deafness or aphasia. Inability to take care of oneself (21.0%), inconvenience related to mobility (20.2%) and inability to work (14.8%) were the three most commonly mentioned 'worst impact' effects of visual loss. Fully 68% of the participants believed that loss of vision is related to ageing. A majority of participants would seek help and advice from family members in case of visual loss. Visual function is perceived to be very important by Hong Kong Chinese adults. The fear of visual loss is widespread and particularly affects self-care and functional abilities. Visual loss is commonly seen as related to ageing. Attitudes and perceptions in this population may be modified by educational and outreach efforts in order to take advantage of preventive measures.

  11. Bilateral acute visual loss from Rathke's cleft cyst apoplexy in a patient with dengue fever

    Directory of Open Access Journals (Sweden)

    Ana Cláudia De Franco Suzuki

    2014-10-01

    Full Text Available Hemorrhagic complications of optic pathway diseases are extremely rare causes of acute visual loss associated with dengue fever. In this paper we report a patient presenting with dengue fever and bilateral acute visual loss caused by chiasmal compression due to Rathke's cleft cyst apoplexy. Considering the importance of early diagnosis and treatment to visual recovery, apoplexy of sellar and suprasellar tumors should be considered in the differential diagnosis of patients with acute visual loss and dengue fever.

  12. 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.

  13. The Association of Glaucomatous Visual Field Loss and Balance

    Science.gov (United States)

    de Luna, Regina A.; Mihailovic, Aleksandra; Nguyen, Angeline M.; Friedman, David S.; Gitlin, Laura N.; Ramulu, Pradeep Y.

    2017-01-01

    Purpose To relate balance measures to visual field (VF) damage from glaucoma. Methods The OPAL kinematic system measured balance, as root mean square (RMS) sway, on 236 patients with suspect/diagnosed glaucoma. Balance was measured with feet shoulder width apart while standing on a firm/foam surface with eyes opened/closed (Instrumental Clinical Test of Sensory Integration and Balance [ICTSIB] conditions), and eyes open on a firm surface under feet together, semi-tandem, or tandem positions (standing balance conditions). Integrated VF (IVF) sensitivities were calculated by merging right and left eye 24-2 VF data. Results Mean age was 71 years (range, 57–93) and mean IVF sensitivity was 27.1 dB (normal = 31 dB). Lower IVF sensitivity was associated with greater RMS sway during eyes-open foam-surface testing (β = 0.23 z-score units/5 dB IVF sensitivity decrement, P = 0.001), but not during other ICTSIB conditions. Lower IVF sensitivity also was associated with greater RMS sway during feet together standing balance testing (0.10 z-score units/5 dB IVF sensitivity decrement, P = 0.049), but not during other standing balance conditions. Visual dependence of balance was lower in patients with worse IVF sensitivity (β = −21%/5 dB IVF sensitivity decrement, P falls and patients with VF loss from glaucoma may be at higher risk of falls because of poor balance. PMID:28553562

  14. Monocular zones in stereoscopic scenes: A useful source of information for human binocular vision?

    Science.gov (United States)

    Harris, Julie M.

    2010-02-01

    When an object is closer to an observer than the background, the small differences between right and left eye views are interpreted by the human brain as depth. This basic ability of the human visual system, called stereopsis, lies at the core of all binocular three-dimensional (3-D) perception and related technological display development. To achieve stereopsis, it is traditionally assumed that corresponding locations in the right and left eye's views must first be matched, then the relative differences between right and left eye locations are used to calculate depth. But this is not the whole story. At every object-background boundary, there are regions of the background that only one eye can see because, in the other eye's view, the foreground object occludes that region of background. Such monocular zones do not have a corresponding match in the other eye's view and can thus cause problems for depth extraction algorithms. In this paper I will discuss evidence, from our knowledge of human visual perception, illustrating that monocular zones do not pose problems for our human visual systems, rather, our visual systems can extract depth from such zones. I review the relevant human perception literature in this area, and show some recent data aimed at quantifying the perception of depth from monocular zones. The paper finishes with a discussion of the potential importance of considering monocular zones, for stereo display technology and depth compression algorithms.

  15. LASIK monocular en pacientes adultos con ambliopía por anisometropía

    Directory of Open Access Journals (Sweden)

    Alejandro Tamez-Peña

    2017-09-01

    Conclusiones: La cirugía refractiva monocular en pacientes con ambliopía por anisometropía es una opción terapéutica segura y efectiva que ofrece resultados visuales satisfactorios, preservando o incluso mejorando la AVMC preoperatoria.

  16. Localisation accuracy of semi-dense monocular SLAM

    Science.gov (United States)

    Schreve, Kristiaan; du Plessies, Pieter G.; Rätsch, Matthias

    2017-06-01

    Understanding the factors that influence the accuracy of visual SLAM algorithms is very important for the future development of these algorithms. So far very few studies have done this. In this paper, a simulation model is presented and used to investigate the effect of the number of scene points tracked, the effect of the baseline length in triangulation and the influence of image point location uncertainty. It is shown that the latter is very critical, while the other all play important roles. Experiments with a well known semi-dense visual SLAM approach are also presented, when used in a monocular visual odometry mode. The experiments shows that not including sensor bias and scale factor uncertainty is very detrimental to the accuracy of the simulation results.

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

    Directory of Open Access Journals (Sweden)

    Katrin Sippel

    Full Text Available 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 < 0.001. Furthermore, patients who passed the task showed a significantly higher number of glances towards the visual field defect (VFD area than patients who failed (t-test, p < 0.05. According to these results, glaucoma patients with defects in the binocular visual field display on average longer search times in a naturalistic 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.

  18. Monocular oral reading after treatment of dense congenital unilateral cataract

    Science.gov (United States)

    Birch, Eileen E.; Cheng, Christina; Christina, V; Stager, David R.

    2010-01-01

    Background Good long-term visual acuity outcomes for children with dense congenital unilateral cataracts have been reported following early surgery and good compliance with postoperative amblyopia therapy. However, treated eyes rarely achieve normal visual acuity and there has been no formal evaluation of the utility of the treated eye for reading. Methods Eighteen children previously treated for dense congenital unilateral cataract were tested monocularly with the Gray Oral Reading Test, 4th edition (GORT-4) at 7 to 13 years of age using two passages for each eye, one at grade level and one at +1 above grade level. In addition, right eyes of 55 normal children age 7 to 13 served as a control group. The GORT-4 assesses reading rate, accuracy, fluency, and comprehension. Results Visual acuity of treated eyes ranged from 0.1 to 2.0 logMAR and of fellow eyes from −0.1 to 0.2 logMAR. Treated eyes scored significantly lower than fellow and normal control eyes on all scales at grade level and at +1 above grade level. Monocular reading rate, accuracy, fluency, and comprehension were correlated with visual acuity of treated eyes (rs = −0.575 to −0.875, p < 0.005). Treated eyes with 0.1-0.3 logMAR visual acuity did not differ from fellow or normal control eyes in rate, accuracy, fluency, or comprehension when reading at grade level or at +1 above grade level. Fellow eyes did not differ from normal controls on any reading scale. Conclusions Excellent visual acuity outcomes following treatment of dense congenital unilateral cataracts are associated with normal reading ability of the treated eye in school-age children. PMID:20603057

  19. Anisometropia and ptosis in patients with monocular elevation deficiency

    International Nuclear Information System (INIS)

    Zafar, S.N.; Islam, F.; Khan, A.M.

    2016-01-01

    Objective: To determine the effect of ptosis on the refractive error in eyes having monocular elevation deficiency Place and Duration of Study: Al-Shifa Trust Eye Hospital, Rawalpindi, from January 2011 to January 2014. Methodology: Visual acuity, refraction, orthoptic assessment and ptosis evaluation of all patients having monocular elevation deficiency (MED) were recorded. Shapiro-Wilk test was used for tests of normality. Median and interquartile range (IQR) was calculated for the data. Non-parametric variables were compared, using the Wilcoxon signed ranks test. P-values of <0.05 were considered significant. Results: A total of of 41 MED patients were assessed during the study period. Best corrected visual acuity (BCVA) and refractive error was compared between the eyes having MED and the unaffected eyes of the same patient. The refractive status of patients having ptosis with MED were also compared with those having MED without ptosis. Astigmatic correction and vision had significant difference between both the eyes of the patients. Vision was significantly different between the two eyes of patients in both the groups having either presence or absence of ptosis (p=0.04 and p < 0.001, respectively). Conclusion: Significant difference in vision and anisoastigmatism was noted between the two eyes of patients with MED in this study. The presence or absence of ptosis affected the vision but did not have a significant effect on the spherical equivalent (SE) and astigmatic correction between both the eyes. (author)

  20. Acute visual loss and intraretinal hemorrhages associated to energy drink consumption.

    Science.gov (United States)

    Pagano, Christina W; Wu, Max; Wu, Lihteh

    2017-12-01

    To report the association of acute visual loss secondary to intraretinal hemorrhages and energy drink consumption. Case report and literature review. A 48-year-old hypertensive man developed an elevation in systemic blood pressure, tachycardia, and acute visual loss secondary to intraretinal hemorrhages shortly after drinking several cans of energy drinks. High consumption of energy drinks may lead to intraretinal hemorrhages and acute visual loss.

  1. 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.

  2. Effects of extraocular muscle surgery in children with monocular blindness and bilateral nystagmus.

    Science.gov (United States)

    Sturm, Veit; Hejcmanova, Marketa; Landau, Klara

    2014-11-20

    Monocular infantile blindness may be associated with bilateral horizontal nystagmus, a subtype of fusion maldevelopment nystagmus syndrome (FMNS). Patients often adopt a significant anomalous head posture (AHP) towards the fixing eye in order to dampen the nystagmus. This clinical entity has also been reported as unilateral Ciancia syndrome. The aim of the study was to ascertain the clinical features and surgical outcome of patients with FMNS with infantile unilateral visual loss. In this retrospective case series, nine consecutive patients with FMNS with infantile unilateral visual loss underwent strabismus surgery to correct an AHP and/or improve ocular alignment. Outcome measures included amount of AHP and deviation at last follow-up. Eye muscle surgery according to the principles of Kestenbaum resulted in a marked reduction or elimination of the AHP. On average, a reduction of AHP of 1.3°/mm was achieved by predominantly performing combined horizontal recess-resect surgery in the intact eye. In cases of existing esotropia (ET) this procedure also markedly reduced the angle of deviation. A dosage calculation of 3 prism diopters/mm was established. We advocate a tailored surgical approach in FMNS with infantile unilateral visual loss. In typical patients who adopt a significant AHP accompanied by a large ET, we suggest an initial combined recess-resect surgery in the intact eye. This procedure regularly led to a marked reduction of the head turn and ET. In patients without significant strabismus, a full Kestenbaum procedure was successful, while ET in a patient with a minor AHP was corrected by performing a bimedial recession.

  3. A Novel Metric Online Monocular SLAM Approach for Indoor Applications

    Directory of Open Access Journals (Sweden)

    Yongfei Li

    2016-01-01

    Full Text Available Monocular SLAM has attracted more attention recently due to its flexibility and being economic. In this paper, a novel metric online direct monocular SLAM approach is proposed, which can obtain the metric reconstruction of the scene. In the proposed approach, a chessboard is utilized to provide initial depth map and scale correction information during the SLAM process. The involved chessboard provides the absolute scale of scene, and it is seen as a bridge between the camera visual coordinate and the world coordinate. The scene is reconstructed as a series of key frames with their poses and correlative semidense depth maps, using a highly accurate pose estimation achieved by direct grid point-based alignment. The estimated pose is coupled with depth map estimation calculated by filtering over a large number of pixelwise small-baseline stereo comparisons. In addition, this paper formulates the scale-drift model among key frames and the calibration chessboard is used to correct the accumulated pose error. At the end of this paper, several indoor experiments are conducted. The results suggest that the proposed approach is able to achieve higher reconstruction accuracy when compared with the traditional LSD-SLAM approach. And the approach can also run in real time on a commonly used computer.

  4. Cooperative Monocular-Based SLAM for Multi-UAV Systems in GPS-Denied Environments.

    Science.gov (United States)

    Trujillo, Juan-Carlos; Munguia, Rodrigo; Guerra, Edmundo; Grau, Antoni

    2018-04-26

    This work presents a cooperative monocular-based SLAM approach for multi-UAV systems that can operate in GPS-denied environments. The main contribution of the work is to show that, using visual information obtained from monocular cameras mounted onboard aerial vehicles flying in formation, the observability properties of the whole system are improved. This fact is especially notorious when compared with other related visual SLAM configurations. In order to improve the observability properties, some measurements of the relative distance between the UAVs are included in the system. These relative distances are also obtained from visual information. The proposed approach is theoretically validated by means of a nonlinear observability analysis. Furthermore, an extensive set of computer simulations is presented in order to validate the proposed approach. The numerical simulation results show that the proposed system is able to provide a good position and orientation estimation of the aerial vehicles flying in formation.

  5. Frida Kahlo: Visual Articulations of Suffering and Loss.

    Science.gov (United States)

    Nixon, Lois LaCivita

    1996-01-01

    Illustrates the value of interdisciplinary approaches to patient care by exploring visual articulations of suffering as rendered by one artist. Makes general observations about the nature of humanities courses offered to medical students and depicts a visual portrayal of an illness story representing personal perspectives about patient suffering…

  6. The Monocular Duke of Urbino.

    Science.gov (United States)

    Schwartz, Stephen G; Leffler, Christopher T; Chavis, Pamela S; Khan, Faraaz; Bermudez, Dennis; Flynn, Harry W

    2016-01-01

    Federico da Montefeltro (1422-1482), the Duke of Urbino, was a well-known historical figure during the Italian Renaissance. He is the subject of a famous painting by Piero della Francesca (1416-1492), which displays the Duke from the left and highlights his oddly shaped nose. The Duke is known to have lost his right eye due to an injury sustained during a jousting tournament, which is why the painting portrays him from the left. Some historians teach that the Duke subsequently underwent nasal surgery to remove tissue from the bridge of his nose in order to expand his visual field in an attempt to compensate for the lost eye. In theory, removal of a piece of the nose may have expanded the nasal visual field, especially the "eye motion visual field" that encompasses eye movements. In addition, removing part of the nose may have reduced some of the effects of ocular parallax. Finally, shifting of the visual egocenter may have occurred, although this seems likely unrelated to the proposed nasal surgery. Whether or not the Duke actually underwent the surgery cannot be proven, but it seems unlikely that this would have substantially improved his visual function.

  7. Monocular deprivation of Fourier phase information boosts the deprived eye's dominance during interocular competition but not interocular phase combination.

    Science.gov (United States)

    Bai, Jianying; Dong, Xue; He, Sheng; Bao, Min

    2017-06-03

    Ocular dominance has been extensively studied, often with the goal to understand neuroplasticity, which is a key characteristic within the critical period. Recent work on monocular deprivation, however, demonstrates residual neuroplasticity in the adult visual cortex. After deprivation of patterned inputs by monocular patching, the patched eye becomes more dominant. Since patching blocks both the Fourier amplitude and phase information of the input image, it remains unclear whether deprivation of the Fourier phase information alone is able to reshape eye dominance. Here, for the first time, we show that removing of the phase regularity without changing the amplitude spectra of the input image induced a shift of eye dominance toward the deprived eye, but only if the eye dominance was measured with a binocular rivalry task rather than an interocular phase combination task. These different results indicate that the two measurements are supported by different mechanisms. Phase integration requires the fusion of monocular images. The fused percept highly relies on the weights of the phase-sensitive monocular neurons that respond to the two monocular images. However, binocular rivalry reflects the result of direct interocular competition that strongly weights the contour information transmitted along each monocular pathway. Monocular phase deprivation may not change the weights in the integration (fusion) mechanism much, but alters the balance in the rivalry (competition) mechanism. Our work suggests that ocular dominance plasticity may occur at different stages of visual processing, and that homeostatic compensation also occurs for the lack of phase regularity in natural scenes. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

  8. Age norms for monocular grating acuity measured by sweep-VEP in the first three years of age Estudo normativo de acuidade visual de resolução de grades medido pelo PVE de varredura nos três primeiros anos de vida

    Directory of Open Access Journals (Sweden)

    Solange Rios Salomão

    2008-08-01

    Full Text Available PURPOSE: To determine age norms for grating visual acuity and interocular acuity differences measured by the sweep-visually evoked potentials (VEP technique in the first three years of life. METHODS: Monocular grating visual acuity was measured using the sweep-VEP in 67 healthy normal infants and children in the first 36 months of life. RESULTS: Sweep-VEP grating acuity ranged from 0.80 logMAR (20/125 Snellen equivalent in the first month of life to 0.06 logMAR (20/20 Snellen equivalent at 36 months of age. Lower normal limits (95th percentile limit ranged from 0.95 logMAR (20/180 to 0.12 logMAR (20/25 with a progression of approximately 3 octaves in the first 36 months of age. The largest acceptable interocular acuity difference for clinical purposes was 0.10 logMAR. CONCLUSIONS: Age norms for grating acuity along with interocular acuity differences were determined using the sweep-VEP technique. These norms should be incorporated in clinical practice for precise diagnosis of visual status in infants and preverbal children.OBJETIVOS: Propor valores normativos de acuidade visual de grades e sua respectiva diferença interocular medidas pelo potencial visual evocado de varredura nos primeiros três anos de vida. MÉTODOS: Foram avaliadas 67 crianças sadias, sem doenças oculares, que tiveram a acuidade visual medida pelos potenciais evocados visuais de varredura. RESULTADOS: A acuidade visual média variou de 0,80 logMAR (equivalente de Snellen de 20/125 no primeiro mês de vida a 0,06 logMAR (equivalente de Snellen de 20/20 aos 36 meses. Os limites normais inferiores (percentil 95% variaram de 0,95 logMAR (20/180 a 0,12 logMAR (20/25 com progressão de aproximadamente 3 oitavas nos primeiros 36 meses de vida. A diferença interocular máxima aceitável foi de 0,10 logMAR. CONCLUSÕES: Os valores normativos de acuidade visual e de diferença interocular de acuidade foram obtidos pela técnica do potencial visual evocado de varredura. Prop

  9. Audiovisual plasticity following early abnormal visual experience: Reduced McGurk effect in people with one eye.

    Science.gov (United States)

    Moro, Stefania S; Steeves, Jennifer K E

    2018-04-13

    Previously, we have shown that people who have had one eye surgically removed early in life during visual development have enhanced sound localization [1] and lack visual dominance, commonly observed in binocular and monocular (eye-patched) viewing controls [2]. Despite these changes, people with one eye integrate auditory and visual components of multisensory events optimally [3]. The current study investigates how people with one eye perceive the McGurk effect, an audiovisual illusion where a new syllable is perceived when visual lip movements do not match the corresponding sound [4]. We compared individuals with one eye to binocular and monocular viewing controls and found that they have a significantly smaller McGurk effect compared to binocular controls. Additionally, monocular controls tended to perceive the McGurk effect less often than binocular controls suggesting a small transient modulation of the McGurk effect. These results suggest altered weighting of the auditory and visual modalities with both short and long-term monocular viewing. These results indicate the presence of permanent adaptive perceptual accommodations in people who have lost one eye early in life that may serve to mitigate the loss of binocularity during early brain development. Crown Copyright © 2018. Published by Elsevier B.V. All rights reserved.

  10. 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

  11. Monocular depth effects on perceptual fading.

    Science.gov (United States)

    Hsu, Li-Chuan; Kramer, Peter; Yeh, Su-Ling

    2010-08-06

    After prolonged viewing, a static target among moving non-targets is perceived to repeatedly disappear and reappear. An uncrossed stereoscopic disparity of the target facilitates this Motion-Induced Blindness (MIB). Here we test whether monocular depth cues can affect MIB too, and whether they can also affect perceptual fading in static displays. Experiment 1 reveals an effect of interposition: more MIB when the target appears partially covered by, than when it appears to cover, its surroundings. Experiment 2 shows that the effect is indeed due to interposition and not to the target's contours. Experiment 3 induces depth with the watercolor illusion and replicates Experiment 1. Experiments 4 and 5 replicate Experiments 1 and 3 without the use of motion. Since almost any stimulus contains a monocular depth cue, we conclude that perceived depth affects perceptual fading in almost any stimulus, whether dynamic or static. Copyright 2010 Elsevier Ltd. All rights reserved.

  12. On so-called paradoxical monocular stereoscopy.

    Science.gov (United States)

    Koenderink, J J; van Doorn, A J; Kappers, A M

    1994-01-01

    Human observers are apparently well able to judge properties of 'three-dimensional objects' on the basis of flat pictures such as photographs of physical objects. They obtain this 'pictorial relief' without much conscious effort and with little interference from the (flat) picture surface. Methods for 'magnifying' pictorial relief from single pictures include viewing instructions as well as a variety of monocular and binocular 'viewboxes'. Such devices are reputed to yield highly increased pictorial depth, though no methodologies for the objective verification of such claims exist. A binocular viewbox has been reconstructed and pictorial relief under monocular, 'synoptic', and natural binocular viewing is described. The results corroborate and go beyond early introspective reports and turn out to pose intriguing problems for modern research.

  13. Monocular Vision SLAM for Indoor Aerial Vehicles

    Directory of Open Access Journals (Sweden)

    Koray Çelik

    2013-01-01

    Full Text Available This paper presents a novel indoor navigation and ranging strategy via monocular camera. By exploiting the architectural orthogonality of the indoor environments, we introduce a new method to estimate range and vehicle states from a monocular camera for vision-based SLAM. The navigation strategy assumes an indoor or indoor-like manmade environment whose layout is previously unknown, GPS-denied, representable via energy based feature points, and straight architectural lines. We experimentally validate the proposed algorithms on a fully self-contained microaerial vehicle (MAV with sophisticated on-board image processing and SLAM capabilities. Building and enabling such a small aerial vehicle to fly in tight corridors is a significant technological challenge, especially in the absence of GPS signals and with limited sensing options. Experimental results show that the system is only limited by the capabilities of the camera and environmental entropy.

  14. Functional vision loss: a diagnosis of exclusion.

    Science.gov (United States)

    Villegas, Rex B; Ilsen, Pauline F

    2007-10-01

    Most cases of visual acuity or visual field loss can be attributed to ocular pathology or ocular manifestations of systemic pathology. They can also occasionally be attributed to nonpathologic processes or malingering. Functional vision loss is any decrease in vision the origin of which cannot be attributed to a pathologic or structural abnormality. Two cases of functional vision loss are described. In the first, a 58-year-old man presented for a baseline eye examination for enrollment in a vision rehabilitation program. He reported bilateral blindness since a motor vehicle accident with head trauma 4 years prior. Entering visual acuity was "no light perception" in each eye. Ocular health examination was normal and the patient made frequent eye contact with the examiners. He was referred for neuroimaging and electrophysiologic testing. The second case was a 49-year-old man who presented with a long history of intermittent monocular diplopia. His medical history was significant for psycho-medical evaluations and a diagnosis of factitious disorder. Entering uncorrected visual acuities were 20/20 in each eye, but visual field testing found constriction. No abnormalities were found that could account for the monocular diplopia or visual field deficit. A diagnosis of functional vision loss secondary to factitious disorder was made. Functional vision loss is a diagnosis of exclusion. In the event of reduced vision in the context of a normal ocular health examination, all other pathology must be ruled out before making the diagnosis of functional vision loss. Evaluation must include auxiliary ophthalmologic testing, neuroimaging of the visual pathway, review of the medical history and lifestyle, and psychiatric evaluation. Comanagement with a psychiatrist is essential for patients with functional vision loss.

  15. The cost of misremembering: Inferring the loss function in visual working memory.

    Science.gov (United States)

    Sims, Chris R

    2015-03-04

    Visual working memory (VWM) is a highly limited storage system. A basic consequence of this fact is that visual memories cannot perfectly encode or represent the veridical structure of the world. However, in natural tasks, some memory errors might be more costly than others. This raises the intriguing possibility that the nature of memory error reflects the costs of committing different kinds of errors. Many existing theories assume that visual memories are noise-corrupted versions of afferent perceptual signals. However, this additive noise assumption oversimplifies the problem. Implicit in the behavioral phenomena of visual working memory is the concept of a loss function: a mathematical entity that describes the relative cost to the organism of making different types of memory errors. An optimally efficient memory system is one that minimizes the expected loss according to a particular loss function, while subject to a constraint on memory capacity. This paper describes a novel theoretical framework for characterizing visual working memory in terms of its implicit loss function. Using inverse decision theory, the empirical loss function is estimated from the results of a standard delayed recall visual memory experiment. These results are compared to the predicted behavior of a visual working memory system that is optimally efficient for a previously identified natural task, gaze correction following saccadic error. Finally, the approach is compared to alternative models of visual working memory, and shown to offer a superior account of the empirical data across a range of experimental datasets. © 2015 ARVO.

  16. Nonorganic visual loss in a child due to school bullying

    Directory of Open Access Journals (Sweden)

    Dimitrios Karagiannis

    2017-04-01

    Conclusions and importance: School bullying is a potential cause of nonorganic vision loss in children. Correct diagnosis, and support by the parents and teachers might rapidly alleviate the symptoms.

  17. Socio-Demographic Factors Associated With Loss Of Visual Acuity ...

    African Journals Online (AJOL)

    The study was designed to identify the sociodemographic factors, which significantly affect the visual acuity of glaucoma patients at presentation. It is a prospective study of 154 new patients with a diagnosis of primary open angle glaucoma seen over 1 year and 8 months at the eye clinic of the University of Benin Teaching ...

  18. 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...... if they had undergone surgery for epilepsy during 2011-2014, resulting in visual field loss. They were examined with DMCO and results were compared with those obtained with the Humphrey Field Analyzer (30:2 SITA-Fast). DMCO sensitivity and specificity were estimated with 95% confidence intervals. Results...

  19. Adjustment to acquired vision loss in adults presenting for visual disability certification.

    Science.gov (United States)

    Nakade, Aditya; Rohatgi, Jolly; Bhatia, Manjeet S; Dhaliwal, Upreet

    2017-03-01

    Rehabilitation of the visually disabled depends on how they adjust to loss; understanding contributing factors may help in effective rehabilitation. The aim of this study is to assess adjustment to acquired vision loss in adults. This observational study, conducted in the Department of Ophthalmology at a tertiary-level teaching hospital, included thirty persons (25-65 years) with visual disability, might contribute to reducing stress and depression.

  20. Non-visualized pregnancy losses are prognostically important for unexplained recurrent miscarriage

    DEFF Research Database (Denmark)

    Kolte, A M; van Oppenraaij, R H; Quenby, S

    2014-01-01

    consecutive pregnancy losses before 12 weeks' gestation, and we included only women with unexplained RM after thorough evaluation. It is uncertain whether the findings apply to other definitions of RM and among women with known causes for their miscarriages. WIDER IMPLICATIONS OF THE FINDINGS: To our......STUDY QUESTION: Are non-visualized pregnancy losses (biochemical pregnancy loss and failed pregnancy of unknown location combined) in the reproductive history of women with unexplained recurrent miscarriage (RM) negatively associated with the chance of live birth in a subsequent pregnancy? SUMMARY...... ANSWER: Non-visualized pregnancy losses contribute negatively to the chance for live birth: each non-visualized pregnancy loss confers a relative risk (RR) for live birth of 0.90 (95% CI 0.83; 0.97), equivalent to the RR conferred by each additional clinical miscarriage. WHAT IS KNOWN ALREADY: The number...

  1. A case of bilateral visual loss after spinal cord surgery | Shifa | Pan ...

    African Journals Online (AJOL)

    The patient never had a visual impairment in the past. Physical examination, fundal examination and CT scan revealed no primary cause for the visual loss. In this patient the absence of any finding in the optic disc and the retina and the normal CT scan, suggests that the most likely diagnosis is posterior ischemic optic ...

  2. CT and VER follow-up of reversible visual loss with fracture of the optic canal

    International Nuclear Information System (INIS)

    Shaked, A.; Hadani, M.; Feinsod, M.

    1982-01-01

    A patient with fracture of the optic canal who demonstrated spontaneous recovery of useful vision following acute visual loss is reported. Acute stretching of the involved optic nerve was demonstrated by CT. The return of the optic nerve (ON) to its normal position coincided with the recovery of vision. The visual evoced response (VER) was the first parameter to herald the good visual outcome. (Author)

  3. Prevalence and Causes of Visual Loss Among the Indigenous Peoples of the World: A Systematic Review.

    Science.gov (United States)

    Foreman, Joshua; Keel, Stuart; van Wijngaarden, Peter; Bourne, Rupert A; Wormald, Richard; Crowston, Jonathan; Taylor, Hugh R; Dirani, Mohamed

    2018-05-01

    Studies have documented a higher disease burden in indigenous compared with nonindigenous populations, but no global data on the epidemiology of visual loss in indigenous peoples are available. A systematic review of literature on visual loss in the world's indigenous populations could identify major gaps and inform interventions to reduce their burden of visual loss. To conduct a systematic review on the prevalence and causes of visual loss among the world's indigenous populations. A search of databases and alternative sources identified literature on the prevalence and causes of visual loss (visual impairment and blindness) and eye diseases in indigenous populations. Studies from January 1, 1990, through August 1, 2017, that included clinical eye examinations of indigenous participants and, where possible, compared findings with those of nonindigenous populations were included. Methodologic quality of studies was evaluated to reveal gaps in the literature. Limited data were available worldwide. A total of 85 articles described 64 unique studies from 24 countries that examined 79 598 unique indigenous participants. Nineteen studies reported comparator data on 42 085 nonindigenous individuals. The prevalence of visual loss was reported in 13 countries, with visual impairment ranging from 0.6% in indigenous Australian children to 48.5% in native Tibetans 50 years or older. Uncorrected refractive error was the main cause of visual impairment (21.0%-65.1%) in 5 of 6 studies that measured presenting visual acuity. Cataract was the main cause of visual impairment in all 6 studies measuring best-corrected acuity (25.4%-72.2%). Cataract was the leading cause of blindness in 13 studies (32.0%-79.2%), followed by uncorrected refractive error in 2 studies (33.0% and 35.8%). Most countries with indigenous peoples do not have data on the burden of visual loss in these populations. Although existing studies vary in methodologic quality and reliability, they suggest that most

  4. Natural course of visual field loss in patients with Type 2 Usher syndrome.

    Science.gov (United States)

    Fishman, Gerald A; Bozbeyoglu, Simge; Massof, Robert W; Kimberling, William

    2007-06-01

    To evaluate the natural course of visual field loss in patients with Type 2 Usher syndrome and different patterns of visual field loss. Fifty-eight patients with Type 2 Usher syndrome who had at least three visual field measurements during a period of at least 3 years were studied. Kinetic visual fields measured on a standard calibrated Goldmann perimeter with II4e and V4e targets were analyzed. The visual field areas in both eyes were determined by planimetry with the use of a digitalizing tablet and computer software and expressed in square inches. The data for each visual field area measurement were transformed to a natural log unit. Using a mixed model regression analysis, values for the half-life of field loss (time during which half of the remaining field area is lost) were estimated. Three different patterns of visual field loss were identified, and the half-life time for each pattern of loss was calculated. Of the 58 patients, 11 were classified as having pattern type I, 12 with pattern type II, and 14 with pattern type III. Of 21 patients whose visual field loss was so advanced that they could not be classified, 15 showed only a small residual central field (Group A) and 6 showed a residual central field with a peripheral island (Group B). The average half-life times varied between 3.85 and 7.37 for the II4e test target and 4.59 to 6.42 for the V4e target. There was no statistically significant difference in the half-life times between the various patterns of field loss or for the test targets. The average half-life times for visual field loss in patients with Usher syndrome Type 2 were statistically similar among those patients with different patterns of visual field loss. These findings will be useful for counseling patients with Type 2 Usher syndrome as to their prognosis for anticipated visual field loss.

  5. Progressive Susac syndrome with bilateral visual loss and disability.

    Science.gov (United States)

    Entezari, Morteza; Karimi, Saeed; Feizi, Mohammadali

    2016-09-01

    Susac syndrome (SS) is a rare retinal-cochlear-cerebral disease with an unclear etiology. A 35-year-old man presented with sudden painless vision loss in the right eye and 2 months later in the left eye with hemiparesis, behavioral changes, and hearing loss. Ophthalmic examinations revealed multiple branch retinal artery occlusions (BRAOs) in both eyes. Brain magnetic resonance imaging showed inflammatory changes with multiple "punched-out" lesions in the corpus callosum which confirmed the diagnosis of SS. Despite intravenous and oral corticosteroid therapy, the disease progressed with the development of new BRAOs, low vision in both eyes, and disability. Prompt diagnosis and early treatment may save the vision and even patient's life.

  6. Sinonasal carcinoma presenting as chronic sinusitis and sequential bilateral visual loss

    Directory of Open Access Journals (Sweden)

    Wei-Yu Chiang

    2015-01-01

    Full Text Available Sinonasal undifferentiated carcinoma-related rhinogenic optic neuropathy is rare and may lead to visual loss. To the best of our knowledge, this is the first report of bilateral sequential visual loss induced by this etiology. It is important to differentiate between chronic sinusitis and malignancy on the basis of specific findings on magnetic resonance images. Surgical decompression with multidisciplinary therapy, including steroids, chemotherapy, and radiotherapy, is indicated. However, no visual improvement was noted in this case, emphasizing the rapid disease progression and importance of early diagnosis and treatment.

  7. Central and Peripheral Vision Loss Differentially Affects Contextual Cueing in Visual Search

    Science.gov (United States)

    Geringswald, Franziska; Pollmann, Stefan

    2015-01-01

    Visual search for targets in repeated displays is more efficient than search for the same targets in random distractor layouts. Previous work has shown that this contextual cueing is severely impaired under central vision loss. Here, we investigated whether central vision loss, simulated with gaze-contingent displays, prevents the incidental…

  8. Child behavior check list and Korean personality inventory for children with functional visual loss.

    Science.gov (United States)

    Kyung, Sung Eun; Lee, Sang Mi; Lim, Myung Ho

    2014-08-01

    To investigate the clinical psychiatric characteristics of children with the main complaint of functional visual loss, their behavior and personality were evaluated by the means of the Korean child behavior check list (K-CBCL), and the Korean personality inventory for children (KPI-C). The evaluation was carried out by the K-CBCL and the KPI-C, the domestically standardized tools, with 20 child subjects suspected of functional visual loss, among the patients who visited our hospital, between August, 2005 and December, 2012. The control group included 160 children in general schools of the same region. The 20 patients whose main complaint was functional visual loss were diagnosed as having a functional visual disorder. The child patient group showed a higher score for the K-CBCL and KPI-C sub-scales of somatic complaints, social problems, aggressive behavior, internalizing problems, externalizing problems, total behavioral problems, somatization and hyperactivity, than that of the control group. The results of the K-CBCL and KPI-C tests among children with functional visual loss, were significantly different from those of the normal control group. This result suggested that psychological factors may influence children with a main complaint of functional visual loss.

  9. Visual Loss Induced by Adalimumab Used for Plaque Psoriasis

    Directory of Open Access Journals (Sweden)

    Norman Saffra

    2017-03-01

    Full Text Available A 61-year-old Caucasian male with severe plaque psoriasis without joint involvement was initiated on adalimumab therapy. Shortly thereafter he presented to the emergency room with acute loss of vision in the right eye. A comprehensive systemic workup was instituted which included magnetic resonance imaging (MRI with and without gadolinium of the brain and orbits. MRI revealed findings that were consistent with CNS demyelination and retrobulbar optic neuritis. Immediate cessation of adalimumab was instituted without any other systemic therapy. Complete return of vision occurred within 6 weeks. No additional psoriatic or neurologic treatment was instituted, and the patient has remained stable now for 14 months.

  10. Manifolds for pose tracking from monocular video

    Science.gov (United States)

    Basu, Saurav; Poulin, Joshua; Acton, Scott T.

    2015-03-01

    We formulate a simple human-pose tracking theory from monocular video based on the fundamental relationship between changes in pose and image motion vectors. We investigate the natural embedding of the low-dimensional body pose space into a high-dimensional space of body configurations that behaves locally in a linear manner. The embedded manifold facilitates the decomposition of the image motion vectors into basis motion vector fields of the tangent space to the manifold. This approach benefits from the style invariance of image motion flow vectors, and experiments to validate the fundamental theory show reasonable accuracy (within 4.9 deg of the ground truth).

  11. Non-visualized pregnancy losses are prognostically important for unexplained recurrent miscarriage.

    Science.gov (United States)

    Kolte, A M; van Oppenraaij, R H; Quenby, S; Farquharson, R G; Stephenson, M; Goddijn, M; Christiansen, O B

    2014-05-01

    Are non-visualized pregnancy losses (biochemical pregnancy loss and failed pregnancy of unknown location combined) in the reproductive history of women with unexplained recurrent miscarriage (RM) negatively associated with the chance of live birth in a subsequent pregnancy? Non-visualized pregnancy losses contribute negatively to the chance for live birth: each non-visualized pregnancy loss confers a relative risk (RR) for live birth of 0.90 (95% CI 0.83; 0.97), equivalent to the RR conferred by each additional clinical miscarriage. The number of clinical miscarriages prior to referral is an important determinant for live birth in women with RM, whereas the significance of non-visualized pregnancy losses is unknown. A retrospective cohort study comprising 587 women with RM seen in a tertiary RM unit 2000-2010. Data on the outcome of the first pregnancy after referral were analysed for 499 women. The study was conducted in the RM Unit at Rigshospitalet, Copenhagen, Denmark. We included all women with unexplained RM, defined as ≥3 consecutive clinical miscarriages or non-visualized pregnancy losses following spontaneous conception or homologous insemination. The category 'non-visualized pregnancy losses' combines biochemical pregnancy loss (positive hCG, no ultrasound performed) and failed PUL (pregnancy of unknown location, positive hCG, but on ultrasound, no pregnancy location established). Demographics were collected, including BMI, age at first pregnancy after referral and outcome of pregnancies prior to referral. Using our own records and records from other Danish hospitals, we verified the outcome of the first pregnancy after referral. For each non-visualized pregnancy loss and miscarriage in the women's reproductive history, the RR for live birth in the first pregnancy after referral was determined by robust Poisson regression analysis, adjusting for risk factors for negative pregnancy outcome. Non-visualized pregnancy losses constituted 37% of reported

  12. The loss of short-term visual representations over time: decay or temporal distinctiveness?

    Science.gov (United States)

    Mercer, Tom

    2014-12-01

    There has been much recent interest in the loss of visual short-term memories over the passage of time. According to decay theory, visual representations are gradually forgotten as time passes, reflecting a slow and steady distortion of the memory trace. However, this is controversial and decay effects can be explained in other ways. The present experiment aimed to reexamine the maintenance and loss of visual information over the short term. Decay and temporal distinctiveness models were tested using a delayed discrimination task, in which participants compared complex and novel objects over unfilled retention intervals of variable length. Experiment 1 found no significant change in the accuracy of visual memory from 2 to 6 s, but the gap separating trials reliably influenced task performance. Experiment 2 found evidence for information loss at a 10-s retention interval, but temporally separating trials restored the fidelity of visual memory, possibly because temporally isolated representations are distinct from older memory traces. In conclusion, visual representations lose accuracy at some point after 6 s, but only within temporally crowded contexts. These findings highlight the importance of temporal distinctiveness within visual short-term memory. PsycINFO Database Record (c) 2014 APA, all rights reserved.

  13. Auditory, visual, and auditory-visual perceptions of emotions by young children with hearing loss versus children with normal hearing.

    Science.gov (United States)

    Most, Tova; Michaelis, Hilit

    2012-08-01

    This study aimed to investigate the effect of hearing loss (HL) on emotion-perception ability among young children with and without HL. A total of 26 children 4.0-6.6 years of age with prelingual sensory-neural HL ranging from moderate to profound and 14 children with normal hearing (NH) participated. They were asked to identify happiness, anger, sadness, and fear expressed by an actress when uttering the same neutral nonsense sentence. Their auditory, visual, and auditory-visual perceptions of the emotional content were assessed. The accuracy of emotion perception among children with HL was lower than that of the NH children in all 3 conditions: auditory, visual, and auditory-visual. Perception through the combined auditory-visual mode significantly surpassed the auditory or visual modes alone in both groups, indicating that children with HL utilized the auditory information for emotion perception. No significant differences in perception emerged according to degree of HL. In addition, children with profound HL and cochlear implants did not perform differently from children with less severe HL who used hearing aids. The relatively high accuracy of emotion perception by children with HL may be explained by their intensive rehabilitation, which emphasizes suprasegmental and paralinguistic aspects of verbal communication.

  14. Diving-related visual loss in the setting of angioid streaks: report of two cases.

    Science.gov (United States)

    Angulo Bocco, Maria I; Spielberg, Leigh; Coppens, Greet; Catherine, Janet; Verougstraete, Claire; Leys, Anita M

    2012-01-01

    The purpose of this study was to report diving-related visual loss in the setting of angioid streaks. Observational case reports of two patients with angioid streaks suffering sudden visual loss immediately after diving. Two young adult male patients presented with visual loss after diving headfirst. Funduscopy revealed angioid streaks, peau d'orange, subretinal hemorrhages, and ruptures of Bruch membrane. Choroidal neovascularization developed during follow-up. Both patients had an otherwise uneventful personal and familial medical history. In patients with angioid streaks, diving headfirst can lead to subretinal hemorrhages and traumatic ruptures in Bruch membrane and increase the risk of maculopathy. Ophthalmologists should caution patients with angioid streaks against diving headfirst.

  15. Perioperative visual loss with non-ocular surgery: Case report and review of literature

    Directory of Open Access Journals (Sweden)

    Nidhi Pandey

    2014-01-01

    Full Text Available Perioperative visual loss (POVL, a rare but devastating complication, has been reported after spine, cardiac, and head-neck surgeries.The various causes include ischemic optic neuropathy, central or branch retinal artery occlusion, and cortical blindness. The contributory factors described are microvascular diseases and intraoperative hemodynamic compromise. However, the exact association of these factors with post-operative blindness has not yet been confirmed. A case of POVL with caesarian section surgery is being presented. The visual loss occurred due to a combined occlusion of central retinal artery and vein.The causes, presentation, and risk factors of POVL after non-ocular surgery are being discussed.

  16. Evolutionary Interactions Between Visual and Chemical Signals: Chemosignals Compensate for the Loss of a Visual Signal in Male Sceloporus Lizards.

    Science.gov (United States)

    Pruett, Jake A; Zúñiga-Vega, J Jaime; Campos, Stephanie M; Soini, Helena A; Novotny, Milos V; Vital-García, Cuauhcihuatl; Martins, Emília P; Hews, Diana K

    2016-11-01

    Animals rely on multimodal signals to obtain information from conspecifics through alternative sensory systems, and the evolutionary loss of a signal in one modality may lead to compensation through increased use of signals in an alternative modality. We investigated associations between chemical signaling and evolutionary loss of abdominal color patches in males of four species (two plain-bellied and two colorful-bellied) of Sceloporus lizards. We conducted field trials to compare behavioral responses of male lizards to swabs with femoral gland (FG) secretions from conspecific males and control swabs (clean paper). We also analyzed the volatile organic compound (VOC) composition of male FG secretions by stir bar extraction and gas chromatography-mass spectrometry (GC-MS) to test the hypothesis that loss of the visual signal is associated with elaboration of the chemical signal. Males of plain-bellied, but not colorful-bellied species exhibited different rates of visual displays when exposed to swabs of conspecific FG secretions relative to control swabs. The VOC composition of male Sceloporus FG secretions was similar across all four species, and no clear association between relative abundances of VOCs and evolutionary loss of abdominal color patches was observed. The emerging pattern is that behavioral responses to conspecific chemical signals are species- and context-specific in male Sceloporus, and compensatory changes in receivers, but not signalers may be involved in mediating increased responsiveness to chemical signals in males of plain-bellied species.

  17. Postoperative visual loss due to conversion disorder after spine surgery: a case report

    Directory of Open Access Journals (Sweden)

    Dailson Mamede Bezerra

    Full Text Available Abstract Background and objective Patients undergoing spinal surgeries may develop postoperative visual loss. We present a case of total bilateral visual loss in a patient who, despite having clinical and surgical risk factors for organic lesion, evolved with visual disturbance due to conversion disorder. Case report A male patient, 39 years old, 71 kg, 1.72 m, ASA I, admitted to undergo fusion and discectomy at L4-L5 and L5-S1. Venoclysis, cardioscopy, oximetry, NIBP; induction with remifentanil, propofol and rocuronium; intubation with ETT (8.0 mm followed by capnography and urinary catheterization for diuresis. Maintenance with full target-controlled intravenous anesthesia. During fixation and laminectomy, the patient developed severe bleeding and hypovolemic shock. After 30 min, hemostasis and hemodynamic stability was achieved with infusion of norepinephrine, volume expansion, and blood products. In the ICU, the patient developed mental confusion, weakness in the limbs, and bilateral visual loss. It was not possible to identify clinical, laboratory or image findings of organic lesion. He evolved with episodes of anxiety, emotional lability, and language impairment; the hypothesis of conversion syndrome with visual component was raised after psychiatric evaluation. The patient had complete resolution of symptoms after visual education and introduction of low doses of antipsychotic, antidepressant, and benzodiazepine. Other symptoms also regressed, and the patient was discharged 12 days after surgery. After 60 days, the patient had no more symptoms. Conclusions Conversion disorders may have different signs and symptoms of non-organic origin,including visual component. It is noteworthy that the occurrence of this type of visual dysfunc-tion in the postoperative period of spinal surgery is a rare event and should be remembered asa differential diagnosis.

  18. [Postoperative visual loss due to conversion disorder after spine surgery: a case report].

    Science.gov (United States)

    Bezerra, Dailson Mamede; Bezerra, Eglantine Mamede; Silva Junior, Antonio Jorge; Amorim, Marco Aurélio Soares; Miranda, Denismar Borges de

    Patients undergoing spinal surgeries may develop postoperative visual loss. We present a case of total bilateral visual loss in a patient who, despite having clinical and surgical risk factors for organic lesion, evolved with visual disturbance due to conversion disorder. A male patient, 39 years old, 71kg, 1.72 m, ASA I, admitted to undergo fusion and discectomy at L4-L5 and L5-S1. Venoclysis, cardioscopy, oximetry, NIBP; induction with remifentanil, propofol and rocuronium; intubation with ETT (8.0mm) followed by capnography and urinary catheterization for diuresis. Maintenance with full target-controlled intravenous anesthesia. During fixation and laminectomy, the patient developed severe bleeding and hypovolemic shock. After 30minutes, hemostasis and hemodynamic stability was achieved with infusion of norepinephrine, volume expansion, and blood products. In the ICU, the patient developed mental confusion, weakness in the limbs, and bilateral visual loss. It was not possible to identify clinical, laboratory or image findings of organic lesion. He evolved with episodes of anxiety, emotional lability, and language impairment; the hypothesis of conversion syndrome with visual component was raised after psychiatric evaluation. The patient had complete resolution of symptoms after visual education and introduction of low doses of antipsychotic, antidepressant, and benzodiazepine. Other symptoms also regressed, and the patient was discharged 12 days after surgery. After 60 days, the patient had no more symptoms. Conversion disorders may have different signs and symptoms of non-organic origin, including visual component. It is noteworthy that the occurrence of this type of visual dysfunction in the postoperative period of spinal surgery is a rare event and should be remembered as a differential diagnosis. Copyright © 2015 Sociedade Brasileira de Anestesiologia. Publicado por Elsevier Editora Ltda. All rights reserved.

  19. Postoperative visual loss following dorsal root entry zone rhizotomy: A dreaded complication after a benign procedure

    Directory of Open Access Journals (Sweden)

    R K Mishra

    2016-01-01

    Full Text Available Postoperative visual loss (POVL is a rare but grave postoperative complication. It has been mainly reported in patients undergoing cardiac and spinal surgeries. Dorsal root entry zone (DREZ is pain relieving procedure performed in patients with refractory neuropathic pain with minimal complication rate. We present a case of unilateral POVL following DREZ rhizotomy in prone position in a patient having brachial plexus neuropathy. Exact etiology of vision loss was though not clear; hypotension, use of vasopressors and hemodilution may have led to vision loss in this patient. This case report highlights the associated risk factors for development of this hazardous complication.

  20. Electrolyte composition of retro-oil fluid and silicone oil-related visual loss

    NARCIS (Netherlands)

    Scheerlinck, Laura M E; Kuiper, Jonas J W; Liem, Albert T A; Schellekens, Peter A W J F; van Leeuwen, Redmer

    2016-01-01

    PURPOSE: Up to one-third of patients with intra-ocular silicone oil (SO) tamponade for complex macula-on retinal detachment may experience an unexplained visual loss during or after SO tamponade. Although the underlying mechanism is unknown, previous studies suggested that accumulation of retinal

  1. Visual estimation versus gravimetric measurement of postpartum blood loss: a prospective cohort study.

    Science.gov (United States)

    Al Kadri, Hanan M F; Al Anazi, Bedayah K; Tamim, Hani M

    2011-06-01

    One of the major problems in international literature is how to measure postpartum blood loss with accuracy. We aimed in this research to assess the accuracy of visual estimation of postpartum blood loss (by each of two main health-care providers) compared with the gravimetric calculation method. We carried out a prospective cohort study at King Abdulaziz Medical City, Riyadh, Saudi Arabia between 1 November 2009 and 31 December 2009. All women who were admitted to labor and delivery suite and delivered vaginally were included in the study. Postpartum blood loss was visually estimated by the attending physician and obstetrics nurse and then objectively calculated by a gravimetric machine. Comparison between the three methods of blood loss calculation was carried out. A total of 150 patients were included in this study. There was a significant difference between the gravimetric calculated blood loss and both health-care providers' estimation with a tendency to underestimate the loss by about 30%. The background and seniority of the assessing health-care provider did not affect the accuracy of the estimation. The corrected incidence of postpartum hemorrhage in Saudi Arabia was found to be 1.47%. Health-care providers tend to underestimate the volume of postpartum blood loss by about 30%. Training and continuous auditing of the diagnosis of postpartum hemorrhage is needed to avoid missing cases and thus preventing associated morbidity and mortality.

  2. Loss of calretinin immunoreactive fibers in subcortical visual recipient structures of the RCS dystrophic rat.

    Science.gov (United States)

    Vugler, Anthony A; Coffey, Peter J

    2003-11-01

    The retinae of dystrophic Royal College of Surgeons (RCS) rats exhibit progressive photoreceptor degeneration accompanied by pathology of ganglion cells. To date, little work has examined the consequences of retinal degeneration for central visual structures in dystrophic rats. Here, we use immunohistochemistry for calretinin (CR) to label retinal afferents in the superior colliculus (SC), lateral geniculate nucleus, and olivary pretectal nucleus of RCS rats aged between 2 and 26 months of age. Early indications of fiber loss in the medial dystrophic SC were apparent between 9 and 13 months. Quantitative methods reveal a significant reduction in the level of CR immunoreactivity in visual layers of the medial dystrophic SC at 13 months (P animals aged 19-26 months the loss of CR fibers in SC was dramatic, with well-defined patches of fiber degeneration predominating in medial aspects of the structure. This fiber degeneration in SC was accompanied by increased detection of cells immunoreactive for CR. In several animals, regions of fiber loss were also found to contain strongly parvalbumin-immunoreactive cells. Loss of CR fibers was also observed in the lateral geniculate nucleus and olivary pretectal nucleus. Patterns of fiber loss in the dystrophic SC compliment reports of ganglion cell degeneration in these animals and the response of collicular neurons to degeneration is discussed in terms of plasticity of the dystrophic visual system and properties of calcium binding proteins.

  3. Performance of the visual field index in glaucoma patients with moderately advanced visual field loss.

    Science.gov (United States)

    Lee, Jun Mo; Cirineo, Nila; Ramanathan, Meera; Nouri-Mahdavi, Kouros; Morales, Esteban; Coleman, Anne L; Caprioli, Joseph

    2014-01-01

    To explore the relationship between the visual field index (VFI) and the visual field mean deviation (MD) in glaucoma patients with moderately advanced perimetric damage and to identify the magnitude of the boundary effect of VFI that occurred when the VFI estimation strategy changed from pattern deviation probability value to total deviation probability value as the MD crossed -20 dB in longitudinal visual field (VF) series. A retrospective cohort study of longitudinal data analysis. The MD and VFI values obtained from VF tests conducted on 148 eyes of 148 glaucoma patients having an MD around -20 dB were studied. A total of 1286 VFs with MD values within the range of -16 dB to -24 dB were included. The eyes were divided into 2 groups, with the first having serial MDs all better than or all worse than -20 dB and the second with serial MDs crossing the -20 dB value. Change in MD (ΔMD) was defined as the absolute difference between the MD values of 2 consecutive VFs. Based on the 2 VFI values of the same VFs, the absolute value of change in VFI (ΔVFI) was calculated. The means (± standard deviation) for the ΔVFI were 4.17% (± 3.3%) in the group of eyes with MDs on either side of -20 dB, and were 15.8% (± 8.4%) in the group with MDs crossing -20 dB (P values were 6.8%/dB (± 10.5%) when the range of MD falls on either side of -20 dB, and 7.9%/dB (± 6.2%) when the range of MD crosses the -20 dB values (P = .042). The values of the VFI become highly variable in serial VFs of eyes with MDs crossing -20 dB, in comparison to those VFIs associated with MDs on either side of -20 dB. The likelihood for this effect is the change from use of pattern deviation probability value to total deviation probability value in the points included in the calculation of VFI at -20 dB of MD. The development of indices to measure VF rates that are free from this boundary effect in moderately advanced glaucoma is desirable. Copyright © 2014. Published by Elsevier Inc.

  4. Effect of monocular deprivation on rabbit neural retinal cell densities

    Directory of Open Access Journals (Sweden)

    Philip Maseghe Mwachaka

    2015-01-01

    Conclusion: In this rabbit model, monocular deprivation resulted in activity-dependent changes in cell densities of the neural retina in favour of the non-deprived eye along with reduced cell densities in the deprived eye.

  5. 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 ( T C -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).

  6. Effect of Monocular Deprivation on Rabbit Neural Retinal Cell Densities

    OpenAIRE

    Mwachaka, Philip Maseghe; Saidi, Hassan; Odula, Paul Ochieng; Mandela, Pamela Idenya

    2015-01-01

    Purpose: To describe the effect of monocular deprivation on densities of neural retinal cells in rabbits. Methods: Thirty rabbits, comprised of 18 subject and 12 control animals, were included and monocular deprivation was achieved through unilateral lid suturing in all subject animals. The rabbits were observed for three weeks. At the end of each week, 6 experimental and 3 control animals were euthanized, their retinas was harvested and processed for light microscopy. Photomicrographs of ...

  7. Prior rates of visual field loss and lifetime risk of blindness in glaucomatous patients undergoing trabeculectomy.

    Science.gov (United States)

    Foulsham, W S; Fu, L; Tatham, A J

    2015-10-01

    Trend-based analyses examining rates of visual field (VF) loss in glaucoma are useful for predicting risk of vision-related morbidity. Although patients with faster losses are likely to require treatment escalation, little is known about rates that might trigger a decision to intervene surgically. The aims of this study were to investigate prior rates of VF loss in patients attending for trabeculectomy and to estimate, in the absence of surgical intervention, lifetime risk of visual impairment, and blindness. A retrospective analysis of 117 eyes of 86 consecutive patients with glaucoma attending for trabeculectomy, including 53 patients referred from general ophthalmology clinics and 33 patients from specialist glaucoma clinics. Rates of change in standard automated perimetry mean deviation were examined using linear regression and random coefficient models. Risk of lifetime visual impairment and blindness was calculated using life expectancy data. Mean age at surgery was 71.0±9.7 years. Patients were followed for 10.7±7.5 years prior to surgery with an average of seven useable fields per eye. On average patients referred from general clinics lost 1.04 dB/year compared with 0.77 dB/year in those referred from glaucoma clinics (P=0.070). Patients referred from general clinics had more medication changes prior to surgery (3.4 and 2.6 changes, respectively; P=0.004). Given Scottish life expectancy data, untreated, 61 eyes (52%) would have passed the threshold for visual impairment, whereas 40 (34%) would have passed the threshold demarcating blindness. Patients attending for trabeculectomy had faster average rates of field loss prior to surgery than published values for the general glaucoma population with over one-third of eyes studied predicted to have become blind without intervention. Those managed by glaucoma specialists had fewer changes in medication and tended to slower rates of VF loss, although the latter did not reach statistical significance.

  8. Diabetic macular oedema and visual loss: relationship to location, severity and duration

    DEFF Research Database (Denmark)

    Gardner, Thomas W; Larsen, Michael; Girach, Aniz

    2009-01-01

    Abstract. Purpose: To assess the relationship between visual acuity (VA) and diabetic macular oedema (DMO) in relation to the location of retinal thickening and the severity and duration of central macular thickening. Methods: Data from 584 eyes in 340 placebo-treated patients in the 3-years...... (Snellen equivalent = 20/125). Diabetic retinopathy and DMO status were assessed using stereo photographs. Results: Nearly one third of study eyes had foveal centre-involving DMO at the start of the trial. Sustained moderate visual loss was found in 36 eyes, most commonly associated with DMO at the centre...

  9. Effects of sensorineural hearing loss on visually guided attention in a multitalker environment.

    Science.gov (United States)

    Best, Virginia; Marrone, Nicole; Mason, Christine R; Kidd, Gerald; Shinn-Cunningham, Barbara G

    2009-03-01

    This study asked whether or not listeners with sensorineural hearing loss have an impaired ability to use top-down attention to enhance speech intelligibility in the presence of interfering talkers. Listeners were presented with a target string of spoken digits embedded in a mixture of five spatially separated speech streams. The benefit of providing simple visual cues indicating when and/or where the target would occur was measured in listeners with hearing loss, listeners with normal hearing, and a control group of listeners with normal hearing who were tested at a lower target-to-masker ratio to equate their baseline (no cue) performance with the hearing-loss group. All groups received robust benefits from the visual cues. The magnitude of the spatial-cue benefit, however, was significantly smaller in listeners with hearing loss. Results suggest that reduced utility of selective attention for resolving competition between simultaneous sounds contributes to the communication difficulties experienced by listeners with hearing loss in everyday listening situations.

  10. An Approach for Environment Mapping and Control of Wall Follower Cellbot Through Monocular Vision and Fuzzy System

    OpenAIRE

    Farias, Karoline de M.; Rodrigues Junior, WIlson Leal; Bezerra Neto, Ranulfo P.; Rabelo, Ricardo A. L.; Santana, Andre M.

    2017-01-01

    This paper presents an approach using range measurement through homography calculation to build 2D visual occupancy grid and control the robot through monocular vision. This approach is designed for a Cellbot architecture. The robot is equipped with wall following behavior to explore the environment, which enables the robot to trail objects contours, residing in the fuzzy control the responsibility to provide commands for the correct execution of the robot movements while facing the advers...

  11. Binocular contrast discrimination needs monocular multiplicative noise

    Science.gov (United States)

    Ding, Jian; Levi, Dennis M.

    2016-01-01

    The effects of signal and noise on contrast discrimination are difficult to separate because of a singularity in the signal-detection-theory model of two-alternative forced-choice contrast discrimination (Katkov, Tsodyks, & Sagi, 2006). In this article, we show that it is possible to eliminate the singularity by combining that model with a binocular combination model to fit monocular, dichoptic, and binocular contrast discrimination. We performed three experiments using identical stimuli to measure the perceived phase, perceived contrast, and contrast discrimination of a cyclopean sine wave. In the absence of a fixation point, we found a binocular advantage in contrast discrimination both at low contrasts (discrimination mechanisms: a nonlinear contrast transducer and multiplicative noise (MN). A binocular combination model (the DSKL model; Ding, Klein, & Levi, 2013b) was first fitted to both the perceived-phase and the perceived-contrast data sets, then combined with either the nonlinear contrast transducer or the MN mechanism to fit the contrast-discrimination data. We found that the best model combined the DSKL model with early MN. Model simulations showed that, after going through interocular suppression, the uncorrelated noise in the two eyes became anticorrelated, resulting in less binocular noise and therefore a binocular advantage in the discrimination task. Combining a nonlinear contrast transducer or MN with a binocular combination model (DSKL) provides a powerful method for evaluating the two putative contrast-discrimination mechanisms. PMID:26982370

  12. Evidence of gradual loss of precision for simple features and complex objects in visual working memory.

    Science.gov (United States)

    Rademaker, Rosanne L; Park, Young Eun; Sack, Alexander T; Tong, Frank

    2018-03-01

    Previous studies have suggested that people can maintain prioritized items in visual working memory for many seconds, with negligible loss of information over time. Such findings imply that working memory representations are robust to the potential contaminating effects of internal noise. However, once visual information is encoded into working memory, one might expect it to inevitably begin degrading over time, as this actively maintained information is no longer tethered to the original perceptual input. Here, we examined this issue by evaluating working memory for single central presentations of an oriented grating, color patch, or face stimulus, across a range of delay periods (1, 3, 6, or 12 s). We applied a mixture-model analysis to distinguish changes in memory precision over time from changes in the frequency of outlier responses that resemble random guesses. For all 3 types of stimuli, participants exhibited a clear and consistent decline in the precision of working memory as a function of temporal delay, as well as a modest increase in guessing-related responses for colored patches and face stimuli. We observed a similar loss of precision over time while controlling for temporal distinctiveness. Our results demonstrate that visual working memory is far from lossless: while basic visual features and complex objects can be maintained in a quite stable manner over time, these representations are still subject to noise accumulation and complete termination. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

  13. Visual Field Defects and Retinal Ganglion Cell Losses in Human Glaucoma Patients

    Science.gov (United States)

    Harwerth, Ronald S.; Quigley, Harry A.

    2007-01-01

    Objective The depth of visual field defects are correlated with retinal ganglion cell densities in experimental glaucoma. This study was to determine whether a similar structure-function relationship holds for human glaucoma. Methods The study was based on retinal ganglion cell densities and visual thresholds of patients with documented glaucoma (Kerrigan-Baumrind, et al.) The data were analyzed by a model that predicted ganglion cell densities from standard clinical perimetry, which were then compared to histologic cell counts. Results The model, without free parameters, produced accurate and relatively precise quantification of ganglion cell densities associated with visual field defects. For 437 sets of data, the unity correlation for predicted vs. measured cell densities had a coefficient of determination of 0.39. The mean absolute deviation of the predicted vs. measured values was 2.59 dB, the mean and SD of the distribution of residual errors of prediction was -0.26 ± 3.22 dB. Conclusions Visual field defects by standard clinical perimetry are proportional to neural losses caused by glaucoma. Clinical Relevance The evidence for quantitative structure-function relationships provides a scientific basis of interpreting glaucomatous neuropathy from visual thresholds and supports the application of standard perimetry to establish the stage of the disease. PMID:16769839

  14. Separating monocular and binocular neural mechanisms mediating chromatic contextual interactions.

    Science.gov (United States)

    D'Antona, Anthony D; Christiansen, Jens H; Shevell, Steven K

    2014-04-17

    When seen in isolation, a light that varies in chromaticity over time is perceived to oscillate in color. Perception of that same time-varying light may be altered by a surrounding light that is also temporally varying in chromaticity. The neural mechanisms that mediate these contextual interactions are the focus of this article. Observers viewed a central test stimulus that varied in chromaticity over time within a larger surround that also varied in chromaticity at the same temporal frequency. Center and surround were presented either to the same eye (monocular condition) or to opposite eyes (dichoptic condition) at the same frequency (3.125, 6.25, or 9.375 Hz). Relative phase between center and surround modulation was varied. In both the monocular and dichoptic conditions, the perceived modulation depth of the central light depended on the relative phase of the surround. A simple model implementing a linear combination of center and surround modulation fit the measurements well. At the lowest temporal frequency (3.125 Hz), the surround's influence was virtually identical for monocular and dichoptic conditions, suggesting that at this frequency, the surround's influence is mediated primarily by a binocular neural mechanism. At higher frequencies, the surround's influence was greater for the monocular condition than for the dichoptic condition, and this difference increased with temporal frequency. Our findings show that two separate neural mechanisms mediate chromatic contextual interactions: one binocular and dominant at lower temporal frequencies and the other monocular and dominant at higher frequencies (6-10 Hz).

  15. Association between visual impairment and patient-reported visual disability at different stages of cataract surgery.

    Science.gov (United States)

    Acosta-Rojas, E Ruthy; Comas, Mercè; Sala, Maria; Castells, Xavier

    2006-10-01

    To evaluate the association between visual impairment (visual acuity, contrast sensitivity, stereopsis) and patient-reported visual disability at different stages of cataract surgery. A cohort of 104 patients aged 60 years and over with bilateral cataract was assessed preoperatively, after first-eye surgery (monocular pseudophakia) and after second-eye surgery (binocular pseudophakia). Partial correlation coefficients (PCC) and linear regression models were calculated. In patients with bilateral cataracts, visual disability was associated with visual acuity (PCC = -0.30) and, to a lesser extent, with contrast sensitivity (PCC = 0.16) and stereopsis (PCC = -0.09). In monocular and binocular pseudophakia, visual disability was more strongly associated with stereopsis (PCC = -0.26 monocular and -0.51 binocular) and contrast sensitivity (PCC = 0.18 monocular and 0.34 binocular) than with visual acuity (PCC = -0.18 monocular and -0.18 binocular). Visual acuity, contrast sensitivity and stereopsis accounted for between 17% and 42% of variance in visual disability. The association of visual impairment with patient-reported visual disability differed at each stage of cataract surgery. Measuring other forms of visual impairment independently from visual acuity, such as contrast sensitivity or stereopsis, could be important in evaluating both needs and outcomes in cataract surgery. More comprehensive assessment of the impact of cataract on patients should include measurement of both visual impairment and visual disability.

  16. REAL TIME SPEED ESTIMATION FROM MONOCULAR VIDEO

    Directory of Open Access Journals (Sweden)

    M. S. Temiz

    2012-07-01

    Full Text Available In this paper, detailed studies have been performed for developing a real time system to be used for surveillance of the traffic flow by using monocular video cameras to find speeds of the vehicles for secure travelling are presented. We assume that the studied road segment is planar and straight, the camera is tilted downward a bridge and the length of one line segment in the image is known. In order to estimate the speed of a moving vehicle from a video camera, rectification of video images is performed to eliminate the perspective effects and then the interest region namely the ROI is determined for tracking the vehicles. Velocity vectors of a sufficient number of reference points are identified on the image of the vehicle from each video frame. For this purpose sufficient number of points from the vehicle is selected, and these points must be accurately tracked on at least two successive video frames. In the second step, by using the displacement vectors of the tracked points and passed time, the velocity vectors of those points are computed. Computed velocity vectors are defined in the video image coordinate system and displacement vectors are measured by the means of pixel units. Then the magnitudes of the computed vectors in the image space are transformed to the object space to find the absolute values of these magnitudes. The accuracy of the estimated speed is approximately ±1 – 2 km/h. In order to solve the real time speed estimation problem, the authors have written a software system in C++ programming language. This software system has been used for all of the computations and test applications.

  17. Adaptive Monocular Visual–Inertial SLAM for Real-Time Augmented Reality Applications in Mobile Devices

    Directory of Open Access Journals (Sweden)

    Jin-Chun Piao

    2017-11-01

    Full Text Available Simultaneous localization and mapping (SLAM is emerging as a prominent issue in computer vision and next-generation core technology for robots, autonomous navigation and augmented reality. In augmented reality applications, fast camera pose estimation and true scale are important. In this paper, we present an adaptive monocular visual–inertial SLAM method for real-time augmented reality applications in mobile devices. First, the SLAM system is implemented based on the visual–inertial odometry method that combines data from a mobile device camera and inertial measurement unit sensor. Second, we present an optical-flow-based fast visual odometry method for real-time camera pose estimation. Finally, an adaptive monocular visual–inertial SLAM is implemented by presenting an adaptive execution module that dynamically selects visual–inertial odometry or optical-flow-based fast visual odometry. Experimental results show that the average translation root-mean-square error of keyframe trajectory is approximately 0.0617 m with the EuRoC dataset. The average tracking time is reduced by 7.8%, 12.9%, and 18.8% when different level-set adaptive policies are applied. Moreover, we conducted experiments with real mobile device sensors, and the results demonstrate the effectiveness of performance improvement using the proposed method.

  18. Monocular tool control, eye dominance, and laterality in New Caledonian crows.

    Science.gov (United States)

    Martinho, Antone; Burns, Zackory T; von Bayern, Auguste M P; Kacelnik, Alex

    2014-12-15

    Tool use, though rare, is taxonomically widespread, but morphological adaptations for tool use are virtually unknown. We focus on the New Caledonian crow (NCC, Corvus moneduloides), which displays some of the most innovative tool-related behavior among nonhumans. One of their major food sources is larvae extracted from burrows with sticks held diagonally in the bill, oriented with individual, but not species-wide, laterality. Among possible behavioral and anatomical adaptations for tool use, NCCs possess unusually wide binocular visual fields (up to 60°), suggesting that extreme binocular vision may facilitate tool use. Here, we establish that during natural extractions, tool tips can only be viewed by the contralateral eye. Thus, maintaining binocular view of tool tips is unlikely to have selected for wide binocular fields; the selective factor is more likely to have been to allow each eye to see far enough across the midsagittal line to view the tool's tip monocularly. Consequently, we tested the hypothesis that tool side preference follows eye preference and found that eye dominance does predict tool laterality across individuals. This contrasts with humans' species-wide motor laterality and uncorrelated motor-visual laterality, possibly because bill-held tools are viewed monocularly and move in concert with eyes, whereas hand-held tools are visible to both eyes and allow independent combinations of eye preference and handedness. This difference may affect other models of coordination between vision and mechanical control, not necessarily involving tools. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Adaptive Monocular Visual–Inertial SLAM for Real-Time Augmented Reality Applications in Mobile Devices

    Science.gov (United States)

    Piao, Jin-Chun; Kim, Shin-Dug

    2017-01-01

    Simultaneous localization and mapping (SLAM) is emerging as a prominent issue in computer vision and next-generation core technology for robots, autonomous navigation and augmented reality. In augmented reality applications, fast camera pose estimation and true scale are important. In this paper, we present an adaptive monocular visual–inertial SLAM method for real-time augmented reality applications in mobile devices. First, the SLAM system is implemented based on the visual–inertial odometry method that combines data from a mobile device camera and inertial measurement unit sensor. Second, we present an optical-flow-based fast visual odometry method for real-time camera pose estimation. Finally, an adaptive monocular visual–inertial SLAM is implemented by presenting an adaptive execution module that dynamically selects visual–inertial odometry or optical-flow-based fast visual odometry. Experimental results show that the average translation root-mean-square error of keyframe trajectory is approximately 0.0617 m with the EuRoC dataset. The average tracking time is reduced by 7.8%, 12.9%, and 18.8% when different level-set adaptive policies are applied. Moreover, we conducted experiments with real mobile device sensors, and the results demonstrate the effectiveness of performance improvement using the proposed method. PMID:29112143

  20. Glaucoma Severity and Participation in Diverse Social Roles: Does Visual Field Loss Matter?

    Science.gov (United States)

    Yang, Yelin; Trope, Graham E; Buys, Yvonne M; Badley, Elizabeth M; Gignac, Monique A M; Shen, Carl; Jin, Ya-Ping

    2016-07-01

    To assess the association between glaucoma severity and participation in diverse social roles. Cross-sectional survey. Individuals with glaucoma, 50+, with visual acuity in the better eye >20/50 were enrolled. They were classified into 3 groups based on visual field loss in the better eye: mild [mean deviation (MD)>-6 dB], moderate (MD, -6 to -12 dB), and severe (MDSocial Role Participation Questionnaire assessed respondents' perceptions of the importance, difficulty, and satisfaction with participation in 11 social role domains (eg, community events, travel). Differences between groups were examined using multivariate linear regression analyses. A total of 118 participants (52% female) were included: 60 mild, 29 moderate, and 29 severe. All social role domains were rated as important by all participants except for education and employment. Women (Psocial activities. Compared with those with mild glaucoma, individuals with severe glaucoma reported significantly more difficulty participating in community/religious/cultural events (Psocial events (P=0.04). Participation in diverse social roles is valued by individuals with glaucoma. Severe visual field loss impedes involvement in and satisfaction with activities in community/religious/cultural events, travelling, and relationships with family members. Appropriate community and targeted interventions are needed to allow people with severe glaucoma to maintain active social participation-a key component to successful aging.

  1. Neurosyphilis manifesting with unilateral visual loss and hyponatremia: a case report

    Directory of Open Access Journals (Sweden)

    Discher Thomas

    2011-01-01

    Full Text Available Abstract Background Syphilis is called the chameleon of the diseases due to its variety of its clinical presentations, potentially affecting every organ of the body. Incidence of this ancient disease is once again on the increase worldwide. Case presentation We here report an unusual case of neurosyphilis manifesting with unilateral visual loss and hyponatremia. The patient also had primary syphilitic lesions and was concomitantly diagnosed with Human Immunodeficiency Virus (HIV, Hepatitis B Virus (HBV and Hepatitis C Virus (HCV infection. Treatment with ceftriaxone and prednisolone, completely resolved the hyponatremia and visual acuity was partially restored. Conclusion Awareness of syphilis as a differential diagnosis is important as previously unreported presentations of neurosyphilis can arise, especially in HIV infected patients.

  2. Profound bilateral visual loss after hysterectomy indicated for severe postpartum haemorrhage

    DEFF Research Database (Denmark)

    Ostri, Christoffer; Zibrandtsen, Nathalie; Larsen, Michael

    2014-01-01

    We present a case of a patient with bilateral posterior ischaemic optic neuropathy in the previously unreported setting of hysterectomy indicated for severe postpartum haemorrhage. The diagnosis was based on clinical and paraclinical examinations, including MRI of the head, electroretinography (ERG....... The diagnosis of perioperative posterior ischaemic optic neuropathy is mostly a clinical diagnosis. However, MRI plays a major role in excluding other causes of visual loss, and VEP, ERG and OCT are valuable supplemental diagnostic tools.......) and visual evoked potentials (VEP) testing. During 1 year of follow-up, repeated optical coherence tomography (OCT) scans demonstrated optic disc atrophy, which was interpreted as a sign of direct retrograde ganglion cell degeneration after ischaemic damage to the retrolaminar part of the optic nerves...

  3. A Highest Order Hypothesis Compatibility Test for Monocular SLAM

    OpenAIRE

    Edmundo Guerra; Rodrigo Munguia; Yolanda Bolea; Antoni Grau

    2013-01-01

    Simultaneous Location and Mapping (SLAM) is a key problem to solve in order to build truly autonomous mobile robots. SLAM with a unique camera, or monocular SLAM, is probably one of the most complex SLAM variants, based entirely on a bearing-only sensor working over six DOF. The monocular SLAM method developed in this work is based on the Delayed Inverse-Depth (DI-D) Feature Initialization, with the contribution of a new data association batch validation technique, the Highest Order Hyp...

  4. Screening in Primary Care for Diabetic Retinopathy, Maculopathy and Visual Loss in South Africa.

    Science.gov (United States)

    Webb, Elizabeth M; Rheeder, Paul; Roux, Polla

    2016-01-01

    The aim of the study was to determine the prevalence of diabetic retinopathy, maculopathy and visual loss in primary care patients and to identify associated risk factors. We conducted a cluster randomised trial at primary care clinics in the Tshwane district in South Africa. Grades of retinopathy and maculopathy (with fundus camera) and visual acuity (Snellen chart) were assessed and, using mobile screening and teleophthalmology, clinical and biochemical testing was conducted to obtain information about glycaemic control and microvascular complications. The prevalence rates for any retinopathy, preproliferative retinopathy and proliferative retinopathy were 24.9, 19.5 and 5.5%, respectively. The prevalence rates of diabetic maculopathy, observable maculopathy and referable maculopathy were 20.8, 11.8 and 9.0%, respectively. The presence of retinopathy was associated with high body mass index, systolic blood pressure, being on insulin treatment, high HbA1c and the presence of neuropathy. High systolic blood pressure, being on insulin treatment, high HbA1c level and high low-density lipoprotein cholesterol level as well as the presence of albuminuria were significant in predicting any diabetic maculopathy. Laser photocoagulation was given to 8.3% of patients from the mobile unit and 12% of patients were referred to the nearest hospital with an outpatient eye clinic for follow-up treatment of various other eye conditions. Using the WHO categories, the study found that 78.1% of diabetes patients had normal vision, 19.3% were visually impaired and 2.2% were severely impaired or blind. High prevalence rates for diabetic retinopathy, maculopathy and visual loss were found and associations were identified. © 2016 S. Karger AG, Basel.

  5. Capturing age-related changes in functional contrast sensitivity with decreasing light levels in monocular and binocular vision.

    Science.gov (United States)

    Gillespie-Gallery, Hanna; Konstantakopoulou, Evgenia; Harlow, Jonathan A; Barbur, John L

    2013-09-09

    It is challenging to separate the effects of normal aging of the retina and visual pathways independently from optical factors, decreased retinal illuminance, and early stage disease. This study determined limits to describe the effect of light level on normal, age-related changes in monocular and binocular functional contrast sensitivity. We recruited 95 participants aged 20 to 85 years. Contrast thresholds for correct orientation discrimination of the gap in a Landolt C optotype were measured using a 4-alternative, forced-choice (4AFC) procedure at screen luminances from 34 to 0.12 cd/m(2) at the fovea and parafovea (0° and ±4°). Pupil size was measured continuously. The Health of the Retina index (HRindex) was computed to capture the loss of contrast sensitivity with decreasing light level. Participants were excluded if they exhibited performance outside the normal limits of interocular differences or HRindex values, or signs of ocular disease. Parafoveal contrast thresholds showed a steeper decline and higher correlation with age at the parafovea than the fovea. Of participants with clinical signs of ocular disease, 83% had HRindex values outside the normal limits. Binocular summation of contrast signals declined with age, independent of interocular differences. The HRindex worsens more rapidly with age at the parafovea, consistent with histologic findings of rod loss and its link to age-related degenerative disease of the retina. The HRindex and interocular differences could be used to screen for and separate the earliest stages of subclinical disease from changes caused by normal aging.

  6. Dry eye disease and work productivity loss in visual display users: the Osaka study.

    Science.gov (United States)

    Uchino, Miki; Uchino, Yuichi; Dogru, Murat; Kawashima, Motoko; Yokoi, Norihiko; Komuro, Aoi; Sonomura, Yukiko; Kato, Hiroaki; Kinoshita, Shigeru; Schaumberg, Debra A; Tsubota, Kazuo

    2014-02-01

    To estimate the impact of dry eye disease (DED) on work performance and productivity in office workers using visual display terminals (VDTs). Cross-sectional study. Six hundred seventy-two Japanese young and middle-aged office workers using VDTs completed a questionnaire that was designed to measured at-work performance deficits and productivity losses using the Japanese version of the Work Limitations Questionnaire, completed by e-mail. Using the Japanese dry eye diagnostic criteria, respondents were classified into 3 groups: definite DED, probable DED, and non DED. Of the 672 office workers, 553 subjects (82.3%), including 366 men and 187 women, completed the questionnaire and underwent clinical evaluation. As for the total workplace productivity loss, the non DED group demonstrated a loss of 3.56%, those with probable DED demonstrated a loss of 4.06%, and those with definite DED demonstrated a loss of 4.82%, indicating significantly worse performance and productivity (P = .014, trend test). For the 4 subscales, DED was associated with significantly lower on-the-job time management (P = .009, trend test) and combined mental performance and interpersonal functioning (P = .011, trend test). After controlling for age, sex, VDT working hours, and diagnosis of DED, time management, physical demands, and mental and interpersonal functioning showed a significant relationship to DED (each P > .05). Annual DED productivity losses were estimated to be $6160 per employee when measured by total production and $1178 per employee calculated by wage. This study indicated that there is a significant impact of DED on the total productivity of Japanese VDT users. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. Visual loss and optic nerve head swelling in thiamine deficiency without prolonged dietary deficiency

    Directory of Open Access Journals (Sweden)

    Gratton SM

    2014-05-01

    Full Text Available Sean M Gratton, Byron L LamBascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, FL, USAAbstract: Visual loss due to optic neuropathy is a rare manifestation of thiamine deficiency. We report a case of a 39-year-old woman with a body mass index (BMI of 29 kg/m2 who developed visual loss and bilateral optic nerve head swelling after a short, self-limited gastrointestinal illness. She was disoriented and inattentive and had absent ankle jerk reflexes, diminished sensation in both legs below the knees, and marked truncal ataxia. Magnetic resonance imaging (MRI showed increased T2-signal in the medial thalami and mammillary bodies. The serum thiamine level was 8 nmol/L (normal 8–30. The diagnosis of thiamine deficiency was made, and the patient’s vision and neurologic symptoms improved significantly with intramuscular thiamine treatment. Thiamine deficiency can occur in the absence of an obvious predisposing factor such as alcoholism or low body weight. The clinician must be aware of the factors that govern vitamin availability and maintain a high index of suspicion to make the diagnosis in such cases.Keywords: optic neuropathy, nutritional deficiency

  8. Sudden unilateral visual loss after autologous fat injection into the nasolabial fold

    Directory of Open Access Journals (Sweden)

    Sang Hyouk Park

    2008-10-01

    Full Text Available Sang Hyouk Park, Hae Jung Sun, Kyung Seek ChoiDepartment of ophthalmology, Soonchunhyang University College of Medicine, Seoul, KoreaAbstract: A 27-year-old female presented with sudden visual loss of her right eye after receiving an autologous fat injection into the right nasolabial fold. Fundus examination of the right eye showed multiple whitish patchy lesions with macular edema. Fluorescein angiogram showed deterioration of choroidal circulation with patchy choroidal filling and arm-to-retina circulation time and retinal arteriovenous passage time were delayed to 30 seconds and 20 seconds, respectively. There was no response in flash visual evoked potential (VEP. High dose steroid therapy (methylprednisolone 1 g/day/i.v. was done and about 2 weeks later, the disc edema subsided and retinal arteriovenous passage time of fluorescein angiogram was normalized but there was no improvement in visual acuity. Absence of a cherry red spot, deterioration of choroidal circulation with patchy choroidal fillings seen in fluorescein angiogram, and no response in flash VEP suggests multiple choroidal infarction due to perfusion defect of the short posterior ciliary artery. The autologous fat injected is thought to have entered the dorsal nasal artery and the retrograde migration of the emboli to the ophthalmic artery might have caused the multiple occlusions of the short posterior ciliary artery.Keywords: autologous fat injection, ciliary artery occlusion, ischemic optic neuropathy

  9. Monocular SLAM for autonomous robots with enhanced features initialization.

    Science.gov (United States)

    Guerra, Edmundo; Munguia, Rodrigo; Grau, Antoni

    2014-04-02

    This work presents a variant approach to the monocular SLAM problem focused in exploiting the advantages of a human-robot interaction (HRI) framework. Based upon the delayed inverse-depth feature initialization SLAM (DI-D SLAM), a known monocular technique, several but crucial modifications are introduced taking advantage of data from a secondary monocular sensor, assuming that this second camera is worn by a human. The human explores an unknown environment with the robot, and when their fields of view coincide, the cameras are considered a pseudo-calibrated stereo rig to produce estimations for depth through parallax. These depth estimations are used to solve a related problem with DI-D monocular SLAM, namely, the requirement of a metric scale initialization through known artificial landmarks. The same process is used to improve the performance of the technique when introducing new landmarks into the map. The convenience of the approach taken to the stereo estimation, based on SURF features matching, is discussed. Experimental validation is provided through results from real data with results showing the improvements in terms of more features correctly initialized, with reduced uncertainty, thus reducing scale and orientation drift. Additional discussion in terms of how a real-time implementation could take advantage of this approach is provided.

  10. A flexible approach to light pen calibration for a monocular-vision-based coordinate measuring system

    International Nuclear Information System (INIS)

    Fu, Shuai; Zhang, Liyan; Ye, Nan; Liu, Shenglan; Zhang, WeiZhong

    2014-01-01

    A monocular-vision-based coordinate measuring system (MVB-CMS) obtains the 3D coordinates of the probe tip center of a light pen by analyzing the monocular image of the target points on the light pen. The light pen calibration, including the target point calibration and the probe tip center calibration, is critical to guarantee the accuracy of the MVB-CMS. The currently used method resorts to special equipment to calibrate the feature points on the light pen in a separate offsite procedure and uses the system camera to calibrate the probe tip center onsite. Instead, a complete onsite light pen calibration method is proposed in this paper. It needs only several auxiliary target points with the same visual features of the light pen targets and two or more cone holes with known distance(s). The target point calibration and the probe tip center calibration are jointly implemented by simply taking two groups of images of the light pen with the camera of the system. The proposed method requires no extra equipment other than the system camera for the calibration, so it is easier to implement and flexible for use. It has been incorporated in a large field-of-view MVB-CMS, which uses active luminous infrared LEDs as the target points. Experimental results demonstrate the accuracy and effectiveness of the proposed method. (paper)

  11. Effects of aging and sensory loss on glial cells in mouse visual and auditory cortices

    Science.gov (United States)

    Tremblay, Marie-Ève; Zettel, Martha L.; Ison, James R.; Allen, Paul D.; Majewska, Ania K.

    2011-01-01

    Normal aging is often accompanied by a progressive loss of receptor sensitivity in hearing and vision, whose consequences on cellular function in cortical sensory areas have remained largely unknown. By examining the primary auditory (A1) and visual (V1) cortices in two inbred strains of mice undergoing either age-related loss of audition (C57BL/6J) or vision (CBA/CaJ), we were able to describe cellular and subcellular changes that were associated with normal aging (occurring in A1 and V1 of both strains) or specifically with age-related sensory loss (only in A1 of C57BL/6J or V1 of CBA/CaJ), using immunocytochemical electron microscopy and light microscopy. While the changes were subtle in neurons, glial cells and especially microglia were transformed in aged animals. Microglia became more numerous and irregularly distributed, displayed more variable cell body and process morphologies, occupied smaller territories, and accumulated phagocytic inclusions that often displayed ultrastructural features of synaptic elements. Additionally, evidence of myelination defects were observed, and aged oligodendrocytes became more numerous and were more often encountered in contiguous pairs. Most of these effects were profoundly exacerbated by age-related sensory loss. Together, our results suggest that the age-related alteration of glial cells in sensory cortical areas can be accelerated by activity-driven central mechanisms that result from an age-related loss of peripheral sensitivity. In light of our observations, these age-related changes in sensory function should be considered when investigating cellular, cortical and behavioral functions throughout the lifespan in these commonly used C57BL/6J and CBA/CaJ mouse models. PMID:22223464

  12. Ganglion cell loss in relation to visual disability in multiple sclerosis.

    Science.gov (United States)

    Walter, Scott D; Ishikawa, Hiroshi; Galetta, Kristin M; Sakai, Reiko E; Feller, Daniel J; Henderson, Sam B; Wilson, James A; Maguire, Maureen G; Galetta, Steven L; Frohman, Elliot; Calabresi, Peter A; Schuman, Joel S; Balcer, Laura J

    2012-06-01

    We used high-resolution spectral-domain optical coherence tomography (SD-OCT) with retinal segmentation to determine how ganglion cell loss relates to history of acute optic neuritis (ON), retinal nerve fiber layer (RNFL) thinning, visual function, and vision-related quality of life (QOL) in multiple sclerosis (MS). Cross-sectional study. A convenience sample of patients with MS (n = 122; 239 eyes) and disease-free controls (n = 31; 61 eyes). Among MS eyes, 87 had a history of ON before enrollment. The SD-OCT images were captured using Macular Cube (200×200 or 512×128) and ONH Cube 200×200 protocols. Retinal layer segmentation was performed using algorithms established for glaucoma studies. Thicknesses of the ganglion cell layer/inner plexiform layer (GCL+IPL), RNFL, outer plexiform/inner nuclear layers (OPL+INL), and outer nuclear/photoreceptor layers (ONL+PRL) were measured and compared in MS versus control eyes and MS ON versus non-ON eyes. The relation between changes in macular thickness and visual disability was also examined. The OCT measurements of GCL+IPL and RNFL thickness; high contrast visual acuity (VA); low-contrast letter acuity (LCLA) at 2.5% and 1.25% contrast; on the 25-item National Eye Institute Visual Function Questionnaire (NEI-VFQ-25) and 10-Item Neuro-Ophthalmic Supplement composite score. Macular RNFL and GCL+IPL were significantly decreased in MS versus control eyes (Pvisual function and vision-specific QOL in MS, and may serve as a useful structural marker of disease. Our findings parallel those of magnetic resonance imaging studies that show gray matter disease is a marker of neurologic disability in MS. Proprietary or commercial disclosure may be found after the references. Copyright © 2012 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

  13. Spatial contrast sensitivity vision loss in children with cortical visual impairment.

    Science.gov (United States)

    Good, William V; Hou, Chuan; Norcia, Anthony M

    2012-11-19

    Although cortical visual impairment (CVI) is the leading cause of bilateral vision impairment in children in Western countries, little is known about the effects of CVI on visual function. The aim of this study was to compare visual evoked potential measures of contrast sensitivity and grating acuity in children with CVI with those of age-matched typically developing controls. The swept parameter visual evoked potential (sVEP) was used to measure contrast sensitivity and grating acuity in 34 children with CVI at 5 months to 5 years of age and in 16 age-matched control children. Contrast thresholds and spatial frequency thresholds (grating acuities) were derived by extrapolating the tuning functions to zero amplitude. These thresholds and maximal suprathreshold response amplitudes were compared between groups. Among 34 children with CVI, 30 had measurable but reduced contrast sensitivity with a median threshold of 10.8% (range 5.0%-30.0% Michelson), and 32 had measurable but reduced grating acuity with median threshold 0.49 logMAR (9.8 c/deg, range 5-14 c/deg). These thresholds were significantly reduced, compared with age-matched control children. In addition, response amplitudes over the entire sweep range for both measures were significantly diminished in children with CVI compared with those of control children. Our results indicate that spatial contrast sensitivity and response amplitudes are strongly affected by CVI. The substantial degree of loss in contrast sensitivity suggests that contrast is a sensitive measure for evaluating vision deficits in patients with CVI.

  14. Data on the effect of conductive hearing loss on auditory and visual cortex activity revealed by intrinsic signal imaging.

    Science.gov (United States)

    Teichert, Manuel; Bolz, Jürgen

    2017-10-01

    This data article provides additional data related to the research article entitled "Simultaneous intrinsic signal imaging of auditory and visual cortex reveals profound effects of acute hearing loss on visual processing" (Teichert and Bolz, 2017) [1]. The primary auditory and visual cortex (A1 and V1) of adult male C57BL/6J mice (P120-P240) were mapped simultaneously using intrinsic signal imaging (Kalatsky and Stryker, 2003) [2]. A1 and V1 activity evoked by combined auditory and visual stimulation were measured before and after conductive hearing loss (CHL) induced by bilateral malleus removal. We provide data showing that A1 responsiveness evoked by sounds of different sound pressure levels (SPL) decreased after CHL whereas visually evoked V1 activity increased after this intervention. In addition, we also provide imaging data on percentage of V1 activity increases after CHL compared to pre-CHL.

  15. Cirurgia monocular para esotropias de grande ângulo: um novo paradigma Monocular surgery for large-angle esotropias: a new paradigm

    Directory of Open Access Journals (Sweden)

    Edmilson Gigante

    2009-02-01

    Full Text Available OBJETIVO: Demonstrar a viabilidade da cirurgia monocular no tratamento das esotropias de grande ângulo, praticando-se amplos recuos do reto medial (6 a 10 mm e grandes ressecções do reto lateral (8 a 10 mm. MÉTODOS: Foram operados, com anestesia geral e sem reajustes per ou pósoperatórios, 46 pacientes com esotropias de 50δ ou mais, relativamente comitantes. Os métodos utilizados para refratometria, medida da acuidade visual e do ângulo de desvio, foram os, tradicionalmente, utilizados em estrabologia. No pós-operatório, além das medidas na posição primária do olhar, foi feita uma avaliação da motilidade do olho operado, em adução e em abdução. RESULTADOS: Foram considerados quatro grupos de estudo, correspondendo a quatro períodos de tempo: uma semana, seis meses, dois anos e quatro a sete anos. Os resultados para o ângulo de desvio pós-cirúrgico foram compatíveis com os da literatura em geral e mantiveram-se estáveis ao longo do tempo. A motilidade do olho operado apresentou pequena limitação em adução e nenhuma em abdução, contrariando o encontrado na literatura estrabológica. Comparando os resultados de adultos com os de crianças e de amblíopes com não amblíopes, não foram encontradas diferenças estatisticamente significativas entre eles. CONCLUSÃO:Em face dos resultados encontrados, entende-se ser possível afirmar que a cirurgia monocular de recuo-ressecção pode ser considerada opção viável para o tratamento das esotropias de grande ângulo, tanto para adultos quanto para crianças, bem como para amblíopes e não amblíopes.PURPOSE: To demonstrate the feasibility of monocular surgery in the treatment of large-angle esotropias through large recessions of the medial rectus (6 to 10 mm and large resections of the lateral rectus (8 to 10 mm. METHODS: 46 patients were submitted to surgery. They had esotropias of 50Δor more that were relatively comitant. The patients were operated under general

  16. Equating spatial summation in visual field testing reveals greater loss in optic nerve disease.

    Science.gov (United States)

    Kalloniatis, Michael; Khuu, Sieu K

    2016-07-01

    To test the hypothesis that visual field assessment in ocular disease measured with target stimuli within or close to complete spatial summation results in larger threshold elevation compared to when measured with the standard Goldmann III target size. The hypothesis predicts a greater loss will be identified in ocular disease. Additionally, we sought to develop a theoretical framework that would allow comparisons of thresholds with disease progression when using different Goldmann targets. The Humphrey Field Analyser (HFA) 30-2 grid was used in 13 patients with early/established optic nerve disease using the current Goldmann III target size or a combination of the three smallest stimuli (target size I, II and III). We used data from control subjects at each of the visual field locations for the different target sizes to establish the number of failed points (events) for the patients with optic nerve disease, as well as global indices for mean deviation (MD) and pattern standard deviation (PSD). The 30-2 visual field testing using alternate target size stimuli showed that all 13 patients displayed more defects (events) compared to the standard Goldmann III target size. The median increase for events was seven additional failed points: (range 1-26). The global indices also increased when the new testing approach was used (MD -3.47 to -6.25 dB and PSD 4.32 to 6.63 dB). Spatial summation mapping showed an increase in critical area (Ac) in disease and overall increase in thresholds when smaller target stimuli were used. When compared to the current Goldmann III paradigm, the use of alternate sized targets within the 30-2 testing protocol revealed a greater loss in patients with optic nerve disease for both event analysis and global indices (MD and PSD). We therefore provide evidence in a clinical setting that target size is important in visual field testing. © 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.

  17. HYPERTENSIVE CHOROIDOPATHY AS AN UNCOMMON CAUSE S OF VISUAL LOSS IN PREGNANCY

    Directory of Open Access Journals (Sweden)

    Bijnya Birajita

    2015-08-01

    Full Text Available INTRODUCTION: HISTORY: A 30 year old lady in her 32 weeks gestation period was referred to our ophthalmology clinic with chief complaints of diminution of vision in both eyes for 4 months duration. Her medical history was suggestive of uncontrolled hypertension. On Ophthalmic evaluation she had best corrected visual acuity of 20/200 in both eyes with normal color vision. Her pupils were bilaterally equal in size and normally reacting to light. The intraocular pressure was within normal range and anterior segment evaluation was within normal limits. Dilated fundus evaluation revealed only arterio - venous crossing changes, mottled retina and resolving hard exudates in both eyes [Fig 1a, & 1 b]. The fundus picture could not explain the severity of vision loss in the patient which prompted us for further workup.

  18. Independent losses of visual perception genes Gja10 and Rbp3 in echolocating bats (Order: Chiroptera.

    Directory of Open Access Journals (Sweden)

    Bin Shen

    Full Text Available A trade-off between the sensory modalities of vision and hearing is likely to have occurred in echolocating bats as the sophisticated mechanism of laryngeal echolocation requires considerable neural processing and has reduced the reliance of echolocating bats on vision for perceiving the environment. If such a trade-off exists, it is reasonable to hypothesize that some genes involved in visual function may have undergone relaxed selection or even functional loss in echolocating bats. The Gap junction protein, alpha 10 (Gja10, encoded by Gja10 gene is expressed abundantly in mammal retinal horizontal cells and plays an important role in horizontal cell coupling. The interphotoreceptor retinoid-binding protein (Irbp, encoded by the Rbp3 gene is mainly expressed in interphotoreceptor matrix and is known to be critical for normal functioning of the visual cycle. We sequenced Gja10 and Rbp3 genes in a taxonomically wide range of bats with divergent auditory characteristics (35 and 18 species for Gja10 and Rbp3, respectively. Both genes have became pseudogenes in species from the families Hipposideridae and Rhinolophidae that emit constant frequency echolocation calls with Doppler shift compensation at high-duty-cycles (the most sophisticated form of biosonar known, and in some bat species that emit echolocation calls at low-duty-cycles. Our study thus provides further evidence for the hypothesis that a trade-off occurs at the genetic level between vision and echolocation in bats.

  19. Independent losses of visual perception genes Gja10 and Rbp3 in echolocating bats (Order: Chiroptera).

    Science.gov (United States)

    Shen, Bin; Fang, Tao; Dai, Mengyao; Jones, Gareth; Zhang, Shuyi

    2013-01-01

    A trade-off between the sensory modalities of vision and hearing is likely to have occurred in echolocating bats as the sophisticated mechanism of laryngeal echolocation requires considerable neural processing and has reduced the reliance of echolocating bats on vision for perceiving the environment. If such a trade-off exists, it is reasonable to hypothesize that some genes involved in visual function may have undergone relaxed selection or even functional loss in echolocating bats. The Gap junction protein, alpha 10 (Gja10, encoded by Gja10 gene) is expressed abundantly in mammal retinal horizontal cells and plays an important role in horizontal cell coupling. The interphotoreceptor retinoid-binding protein (Irbp, encoded by the Rbp3 gene) is mainly expressed in interphotoreceptor matrix and is known to be critical for normal functioning of the visual cycle. We sequenced Gja10 and Rbp3 genes in a taxonomically wide range of bats with divergent auditory characteristics (35 and 18 species for Gja10 and Rbp3, respectively). Both genes have became pseudogenes in species from the families Hipposideridae and Rhinolophidae that emit constant frequency echolocation calls with Doppler shift compensation at high-duty-cycles (the most sophisticated form of biosonar known), and in some bat species that emit echolocation calls at low-duty-cycles. Our study thus provides further evidence for the hypothesis that a trade-off occurs at the genetic level between vision and echolocation in bats.

  20. Visual attention measures predict pedestrian detection in central field loss: a pilot study.

    Science.gov (United States)

    Alberti, Concetta F; Horowitz, Todd; Bronstad, P Matthew; Bowers, Alex R

    2014-01-01

    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, pattention may provide useful measures of functional visual ability of individuals with CFL relevant to more complex mobility tasks.

  1. The structure of visual spaces

    NARCIS (Netherlands)

    Koenderink, J.J.; van Doorn, A.J.

    2008-01-01

    The “visual space” of an optical observer situated at a single, fixed viewpoint is necessarily very ambiguous. Although the structure of the “visual field” (the lateral dimensions, i.e., the “image”) is well defined, the “depth” dimension has to be inferred from the image on the basis of “monocular

  2. A Case Report of Unilateral Severe Visual Loss Along with Bilateral Optic Disc Cupping Secondary to Metastatic Brain Tumor

    Directory of Open Access Journals (Sweden)

    M Mahdavi

    2006-07-01

    Full Text Available Purpose: To report a case of unilateral severe visual loss and bilateral optic disc cupping secondary to brain metastasis of bronchogenic carcinoma Patient and findings: A 48 year-old woman presented with severe visual loss of left eye without redness or pain or any systemic findings .Clinical findings included decreased visual acuity of left eye to 4 m CF and (+3 positive Marcus-Gunn reflex .There was asymmetric optic disc cupping associated with visual field defect in left eye The neurologic investigations showed a secondary metastatic tumor in the brain from bronchogenic carcinoma. Conclusion: Before making a diagnosis of normal -tension glaucoma in asymmetric optic disc cupping and normal intraocular pressure, ophthalmologists should rule out neurologic defects and brain tumors.

  3. Quantitative analysis of retinopathy in type 2 diabetes: identification of prognostic parameters for developing visual loss secondary to diabetic maculopathy

    DEFF Research Database (Denmark)

    Hove, Marianne Nørgaard; Kristensen, Jette Kolding; Lauritzen, Torsten

    2004-01-01

    Purpose: To describe whether quantitative assessment of early changes in the morphology of retinopathy lesions can predict development of vision-threatening diabetic maculopathy. Methods: We used a nested case-control study, and we studied 11 type 2 diabetes patients who had developed visual loss...... secondary to diabetic maculopathy. For each diabetes patient, we also studied three matched control patients who had been followed for a comparable period of time without developing visual loss. Fundus photographs describing the early development of retinopathy were digitized and subjected to a full manual...... from the fovea and the optic disc. Results: In patients who developed visual loss secondary to diabetic maculopathy there was significant early progression in the total area and number of haemorrhages and exudates. The haemorrhages had progressed in all retinal areas except the area around the optic...

  4. Adjustment to acquired vision loss in adults presenting for visual disability certification

    Directory of Open Access Journals (Sweden)

    Aditya Nakade

    2017-01-01

    Full Text Available Context: Rehabilitation of the visually disabled depends on how they adjust to loss; understanding contributing factors may help in effective rehabilitation. Aim: The aim of this study is to assess adjustment to acquired vision loss in adults. Settings and Design: This observational study, conducted in the Department of Ophthalmology at a tertiary-level teaching hospital, included thirty persons (25–65 years with <6/60 in the better eye, and vision loss since ≥6-months. Materials and Methods: Age, gender, rural/urban residence, education, current occupation, binocular distance vision, adjustment (Acceptance and Self-Worth Adjustment Scale, depression (Center for Epidemiologic Studies-Depression Scale, social support (Duke Social Support and Stress Scale, and personality (10-item Personality Inventory scale was recorded. Statistical Analysis: To determine their effect on adjustment, Student's t-test was used for categorical variables, Pearson's correlation for age, and Spearman's correlation for depression, personality trait and social support and stress. Results: Of 30 persons recruited, 24 were men (80%; 24 lived in urban areas (80%; 9 were employed (30%; and 14 (46.6% had studied < Class 3. Adjustment was low (range: 33%–60%; mean: 43.6 ± 5.73. Reported support was low (median: 27.2; interquartile range [IQR]: 18.1–36.3; reported stress was low (median: 0.09; IQR: 0–18.1. Predominant personality traits (max score 14 were “Agreeableness” (average 12.0 ± 1.68 and “Conscientiousness” (average 11.3 ± 2.12. Emotional stability (average 9.2 ± 2.53 was less prominent. Depression score ranged from 17 to 50 (average 31.6 ± 6.01. The factors studied did not influence adjustment. Conclusions: Although adjustment did not vary with factors studied, all patients were depressed. Since perceived support and emotional stability was low, attention could be directed to support networks. Training patients in handling emotions, and training

  5. 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.

  6. Auditory preferences of young children with and without hearing loss for meaningful auditory-visual compound stimuli.

    Science.gov (United States)

    Zupan, Barbra; Sussman, Joan E

    2009-01-01

    Experiment 1 examined modality preferences in children and adults with normal hearing to combined auditory-visual stimuli. Experiment 2 compared modality preferences in children using cochlear implants participating in an auditory emphasized therapy approach to the children with normal hearing from Experiment 1. A second objective in both experiments was to evaluate the role of familiarity in these preferences. Participants were exposed to randomized blocks of photographs and sounds of ten familiar and ten unfamiliar animals in auditory-only, visual-only and auditory-visual trials. Results indicated an overall auditory preference in children, regardless of hearing status, and a visual preference in adults. Familiarity only affected modality preferences in adults who showed a strong visual preference to unfamiliar stimuli only. The similar degree of auditory responses in children with hearing loss to those from children with normal hearing is an original finding and lends support to an auditory emphasis for habilitation. Readers will be able to (1) Describe the pattern of modality preferences reported in young children without hearing loss; (2) Recognize that differences in communication mode may affect modality preferences in young children with hearing loss; and (3) Understand the role of familiarity in modality preferences in children with and without hearing loss.

  7. Is the Charcot and Bernard case (1883) of loss of visual imagery really based on neurological impairment?

    Science.gov (United States)

    Zago, Stefano; Allegri, Nicola; Cristoffanini, Marta; Ferrucci, Roberta; Porta, Mauro; Priori, Alberto

    2011-11-01

    INTRODUCTION. The Charcot and Bernard case of visual imagery, Monsieur X, is a classic case in the history of neuropsychology. Published in 1883, it has been considered the first case of visual imagery loss due to brain injury. Also in recent times a neurological valence has been given to it. However, the presence of analogous cases of loss of visual imagery in the psychiatric field have led us to hypothesise functional origins rather than organic. METHODS. In order to assess the validity of such an inference, we have compared the symptomatology of Monsieur X with that found in cases of loss of visual mental images, both psychiatric and neurological, presented in literature. RESULTS. The clinical findings show strong assonances of the Monsieur X case with the symptoms manifested over time by the patients with functionally based loss of visual imagery. CONCLUSION. Although Monsieur X's damage was initially interpreted as neurological, reports of similar symptoms in the psychiatric field lead us to postulate a functional cause for his impairment as well.

  8. A Highest Order Hypothesis Compatibility Test for Monocular SLAM

    Directory of Open Access Journals (Sweden)

    Edmundo Guerra

    2013-08-01

    Full Text Available Simultaneous Location and Mapping (SLAM is a key problem to solve in order to build truly autonomous mobile robots. SLAM with a unique camera, or monocular SLAM, is probably one of the most complex SLAM variants, based entirely on a bearing-only sensor working over six DOF. The monocular SLAM method developed in this work is based on the Delayed Inverse-Depth (DI-D Feature Initialization, with the contribution of a new data association batch validation technique, the Highest Order Hypothesis Compatibility Test, HOHCT. The Delayed Inverse-Depth technique is used to initialize new features in the system and defines a single hypothesis for the initial depth of features with the use of a stochastic technique of triangulation. The introduced HOHCT method is based on the evaluation of statistically compatible hypotheses and a search algorithm designed to exploit the strengths of the Delayed Inverse-Depth technique to achieve good performance results. This work presents the HOHCT with a detailed formulation of the monocular DI-D SLAM problem. The performance of the proposed HOHCT is validated with experimental results, in both indoor and outdoor environments, while its costs are compared with other popular approaches.

  9. Effect of Monocular Deprivation on Rabbit Neural Retinal Cell Densities.

    Science.gov (United States)

    Mwachaka, Philip Maseghe; Saidi, Hassan; Odula, Paul Ochieng; Mandela, Pamela Idenya

    2015-01-01

    To describe the effect of monocular deprivation on densities of neural retinal cells in rabbits. Thirty rabbits, comprised of 18 subject and 12 control animals, were included and monocular deprivation was achieved through unilateral lid suturing in all subject animals. The rabbits were observed for three weeks. At the end of each week, 6 experimental and 3 control animals were euthanized, their retinas was harvested and processed for light microscopy. Photomicrographs of the retina were taken and imported into FIJI software for analysis. Neural retinal cell densities of deprived eyes were reduced along with increasing period of deprivation. The percentage of reductions were 60.9% (P < 0.001), 41.6% (P = 0.003), and 18.9% (P = 0.326) for ganglion, inner nuclear, and outer nuclear cells, respectively. In non-deprived eyes, cell densities in contrast were increased by 116% (P < 0.001), 52% (P < 0.001) and 59.6% (P < 0.001) in ganglion, inner nuclear, and outer nuclear cells, respectively. In this rabbit model, monocular deprivation resulted in activity-dependent changes in cell densities of the neural retina in favour of the non-deprived eye along with reduced cell densities in the deprived eye.

  10. Could visual neglect induce amblyopia?

    Science.gov (United States)

    Bier, J C; Vokaer, M; Fery, P; Garbusinski, J; Van Campenhoudt, G; Blecic, S A; Bartholomé, E J

    2004-12-01

    Oculomotor nerve disease is a common cause of diplopia. When strabismus is present, absence of diplopia has to induce the research of either uncovering of visual fields or monocular suppression, amblyopia or blindness. We describe the case of a 41-year-old woman presenting with right oculomotor paresis and left object-centred visual neglect due to a right fronto-parietal haemorrhage expanding to the right peri-mesencephalic cisterna caused by the rupture of a right middle cerebral artery aneurysm. She never complained of diplopia despite binocular vision and progressive recovery of strabismus, excluding uncovering of visual fields. Since all other causes were excluded in this case, we hypothesise that the absence of diplopia was due to the object-centred visual neglect. Partial internal right oculomotor paresis causes an ocular deviation in abduction; the image being perceived deviated contralaterally to the left. Thus, in our case, the neglect of the left image is equivalent to a right monocular functional blindness. However, bell cancellation test clearly worsened when assessed in left monocular vision confirming that eye patching can worsen attentional visual neglect. In conclusion, our case argues for the possibility of a functional monocular blindness induced by visual neglect. We think that in presence of strabismus, absence of diplopia should induce the search for hemispatial visual neglect when supratentorial lesions are suspected.

  11. Beyond deficit or compensation: new insights on postural control after long-term total visual loss.

    Science.gov (United States)

    Russo, Maitê M; Lemos, Thiago; Imbiriba, Luís A; Ribeiro, Nathalia L; Vargas, Claudia D

    2017-02-01

    Loss of vision is well known to affect postural control in blind subjects. This effect has classically been framed in terms of deficit or compensation depending on whether body sway increases or decreases in comparison with that of sighted subjects with the eyes open. However, studies have shown that postural responses can be modulated by the context and that changes in postural sway may not necessarily mean a worsened or improved postural control. The goal of our study was to test whether balance is affected by the context in blind subjects. Additional to the quantification of center of pressure (COP) displacement, measurements of body motion (COG) and the correspondent net neuromuscular response (COP-COG) were evaluated in anterior-posterior and medial-lateral directions. Thirty-eight completely blind and thirty-two sighted subjects participated of this study. The volunteers were asked to stand barefoot on a force platform for 60 s in two different conditions: feet apart and feet together. Sighted participants performed the tests with both the eyes open and eyes closed. Results showed that the COP-COG displacements in the blind group were greater than those of the sighted group with eyes open in almost all conditions tested, but not in eyes closed condition. However, the COP and COG results confirmed that the postural responses were context dependent. Together these results suggest that total visual loss does not just lead to a balance deficit or compensation, but to a specific postural signature that might imply in enhancing COP, COG and/or COP-COG in specific postural conditions.

  12. Loss of Visual Working Memory within Seconds: The Combined Use of Refreshable and Non-Refreshable Features

    Science.gov (United States)

    Ricker, Timothy J.; Cowan, Nelson

    2010-01-01

    We reexamine the role of time in the loss of information from working memory, the limited information accessible for cognitive tasks. The controversial issue of whether working memory deteriorates over time was investigated using arrays of unconventional visual characters. Each array was followed by a postperceptual mask, a variable retention…

  13. An Exploration of the Associations among Hearing Loss, Physical Health, and Visual Memory in Adults from West Central Alabama

    Science.gov (United States)

    Hay-McCutcheon, Marcia J.; Hyams, Adriana; Yang, Xin; Parton, Jason; Panasiuk, Brianna; Ondocsin, Sarah; James, Mary Margaret; Scogin, Forrest

    2017-01-01

    Purpose: The purpose of this preliminary study was to explore the associations among hearing loss, physical health, and visual memory in adults living in rural areas, urban clusters, and an urban city in west Central Alabama. Method: Two hundred ninety-seven adults (182 women, 115 men) from rural areas, urban clusters, and an urban city of west…

  14. Incidence, risk factors, and clinical characteristics of unexplained visual loss after intraocular silicone oil for macula-on retinal detachment

    NARCIS (Netherlands)

    Scheerlinck, Laura M.; Schellekens, Peter A.; Liem, Albert T.; Steijns, Daan; van Leeuwen, R

    2016-01-01

    Purpose: To investigate the incidence, risk factors, and clinical characteristics of unexplained visual loss after macula-on rhegmatogenous retinal detachment (RRD). Methods: Retrospective cohort of patients with primary macula-on rhegmatogenous retinal detachment treated by vitrectomy with gas or

  15. Chronic central serous choroidopathy with severe visual loss in hyperopic microphthalmic identical twins

    Directory of Open Access Journals (Sweden)

    Fabry, Annelies

    2011-01-01

    Full Text Available Objective: To report chronic central serous choroidopathy with severe visual loss in hyperopic microphthalmic identical twins. Methods: The index patient was first examined in 1994, at age 31, and has been followed up closely for 17 years. He had repeated fluorescein and indocyanine green angiograms, OCT, ultrasound biometry, and recently also autofluorescence and EDI OCT. His twin brother was first examined in 2010, at age 47, and had a similar extensive exploration. Results: The index patient had a mean refractive error of +6 D OU and VA was 20/32++ in the RE and 20/200 in the LE in 1994. Vision slowly went down to 20/800+ in the RE and 20/600 in the LE in 2011. His twin brother has a mean refractive error of +6 D OU and VA 20/400 OU. Both have a short axial length of the eye, a thick choroid with dilated vessels, and central serous choroidopathy with cystic degeneration of the macula and retina in the posterior pole. Conclusions: We add to the reported complications of microphthalmos, chronic central serous choroidopathy.

  16. Successful treatment of bilateral visual loss caused by HIV-associated optic neuritis

    Directory of Open Access Journals (Sweden)

    Claire Cullen

    2011-12-01

    Full Text Available Optic neuritis is not an uncommon diagnosis in HIV-infected patients, but it is rarely idiopathic. We report a case of a young HIV-infected woman who developed optic neuritis as her presenting manifestation of HIV infection. She had initially experienced sudden-onset right-sided painful visual loss; the left eye had become involved within days. Bilateral swollen discs were apparent on fundoscopy. Investigations were performed for meningitis (including bacterial, cryptococcal, tuberculous and syphilitic types, auto-immune diseases, toxoplasma, rubella, cytomegalovirus, viral hepatitis, HTLV-1/2, HIV-1/2 and syphilis. The only positive result was a reactive HIV enzyme-linked immunosorbent assay. The CD4 count was 85 cells/µl. A post-contrast magnetic resonance imaging scan of the brain illustrated enhancement of the optic nerves. Treatment was 3 days of intravenous methylprednisolone 1 g daily, followed by 11 days of oral prednisone 60 mg daily. Highly active antiretroviral therapy was initiated after 2 weeks. Vision improved from day 6 after commencement of steroid therapy, with ongoing recovery at 5 months.

  17. The Enright phenomenon. Stereoscopic distortion of perceived driving speed induced by monocular pupil dilation.

    Science.gov (United States)

    Carkeet, Andrew; Wood, Joanne M; McNeill, Kylie M; McNeill, Hamish J; James, Joanna A; Holder, Leigh S

    The Enright phenomenon describes the distortion in speed perception experienced by an observer looking sideways from a moving vehicle when viewing with interocular differences in retinal image brightness, usually induced by neutral density filters. We investigated whether the Enright phenomenon could be induced with monocular pupil dilation using tropicamide. We tested 17 visually normal young adults on a closed road driving circuit. Participants were asked to travel at Goal Speeds of 40km/h and 60km/h while looking sideways from the vehicle with: (i) both eyes with undilated pupils; (ii) both eyes with dilated pupils; (iii) with the leading eye only dilated; and (iv) the trailing eye only dilated. For each condition we recorded actual driving speed. With the pupil of the leading eye dilated participants drove significantly faster (by an average of 3.8km/h) than with both eyes dilated (p=0.02); with the trailing eye dilated participants drove significantly slower (by an average of 3.2km/h) than with both eyes dilated (p<0.001). The speed, with the leading eye dilated, was faster by an average of 7km/h than with the trailing eye dilated (p<0.001). There was no significant difference between driving speeds when viewing with both eyes either dilated or undilated (p=0.322). Our results are the first to show a measurable change in driving behaviour following monocular pupil dilation and support predictions based on the Enright phenomenon. Copyright © 2016 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.

  18. Loss of positional information when tracking multiple moving dots: the role of visual memory.

    Science.gov (United States)

    Narasimhan, Sathyasri; Tripathy, Srimant P; Barrett, Brendan T

    2009-01-01

    Pylyshyn, Z.W. and Storm, R.W. (1988) (Tracking multiple independent targets: Evidence for a parallel tracking mechanism. Spatial Vision, 3(3), 179-197) proposed that human observers could simultaneously track up to five dots when presented with an array of dots moving in a random manner. In contrast, Tripathy, S.P., and Barrett, B.T. (2004) (Severe loss of positional information when detecting deviations in multiple trajectories. Journal of Vision, 4(12):4, 1020-1043, http://journalofvision.org/4/14/4/, doi: 10.1167/4.12.4) showed that when a threshold paradigm was employed, observers' ability to track deviations in straight-line trajectories is severely compromised when attending to two or more dots. In this study we present a series of four experiments that investigates the role of attention and visual memory while tracking deviations in multiple trajectories using a threshold paradigm. Our stimuli consisted of several linear, non-parallel, left-to-right trajectories, each moving at the same speed. At the trajectory mid-point (reached simultaneously by all dots), one of the dots (target) deviated clockwise or counter-clockwise. The observers' task was to identify the direction of deviation. The target trajectory was cued in the second half of the trial either by disappearance of distractors at the monitor's mid-line (Experiment 1) or by means of a change in colour of the target (Experiment 2); in both cases deviation thresholds rose steeply when the number of distractor trajectories was increased from 0 (typical threshold approximately 2 degrees) to 3 (typical threshold>20 degrees). When all the trajectories were presented statically in a single frame (Experiment 3), thresholds for identifying the orientation change of the target trajectory remained relatively unchanged as the number of distractor trajectories was increased. When a temporal delay of a few hundred milliseconds was introduced between the first and second halves of trajectories (Experiment 4

  19. Scanning laser polarimetry, but not optical coherence tomography predicts permanent visual field loss in acute nonarteritic anterior ischemic optic neuropathy.

    Science.gov (United States)

    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.

  20. 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.

  1. Smartphone Image Acquisition During Postmortem Monocular Indirect Ophthalmoscopy.

    Science.gov (United States)

    Lantz, Patrick E; Schoppe, Candace H; Thibault, Kirk L; Porter, William T

    2016-01-01

    The medical usefulness of smartphones continues to evolve as third-party applications exploit and expand on the smartphones' interface and capabilities. This technical report describes smartphone still-image capture techniques and video-sequence recording capabilities during postmortem monocular indirect ophthalmoscopy. Using these devices and techniques, practitioners can create photographic documentation of fundal findings, clinically and at autopsy, without the expense of a retinal camera. Smartphone image acquisition of fundal abnormalities can promote ophthalmological telemedicine--especially in regions or countries with limited resources--and facilitate prompt, accurate, and unbiased documentation of retinal hemorrhages in infants and young children. © 2015 American Academy of Forensic Sciences.

  2. Quantifying the impact on navigation performance in visually impaired: Auditory information loss versus information gain enabled through electronic travel aids.

    Directory of Open Access Journals (Sweden)

    Alex Kreilinger

    Full Text Available This study's purpose was to analyze and quantify the impact of auditory information loss versus information gain provided by electronic travel aids (ETAs on navigation performance in people with low vision. Navigation performance of ten subjects (age: 54.9±11.2 years with visual acuities >1.0 LogMAR was assessed via the Graz Mobility Test (GMT. Subjects passed through a maze in three different modalities: 'Normal' with visual and auditory information available, 'Auditory Information Loss' with artificially reduced hearing (leaving only visual information, and 'ETA' with a vibrating ETA based on ultrasonic waves, thereby facilitating visual, auditory, and tactile information. Main performance measures comprised passage time and number of contacts. Additionally, head tracking was used to relate head movements to motion direction. When comparing 'Auditory Information Loss' to 'Normal', subjects needed significantly more time (p<0.001, made more contacts (p<0.001, had higher relative viewing angles (p = 0.002, and a higher percentage of orientation losses (p = 0.011. The only significant difference when comparing 'ETA' to 'Normal' was a reduced number of contacts (p<0.001. Our study provides objective, quantifiable measures of the impact of reduced hearing on the navigation performance in low vision subjects. Significant effects of 'Auditory Information Loss' were found for all measures; for example, passage time increased by 17.4%. These findings show that low vision subjects rely on auditory information for navigation. In contrast, the impact of the ETA was not significant but further analysis of head movements revealed two different coping strategies: half of the subjects used the ETA to increase speed, whereas the other half aimed at avoiding contacts.

  3. Auditory, Visual, and Auditory-Visual Perceptions of Emotions by Young Children with Hearing Loss versus Children with Normal Hearing

    Science.gov (United States)

    Most, Tova; Michaelis, Hilit

    2012-01-01

    Purpose: This study aimed to investigate the effect of hearing loss (HL) on emotion-perception ability among young children with and without HL. Method: A total of 26 children 4.0-6.6 years of age with prelingual sensory-neural HL ranging from moderate to profound and 14 children with normal hearing (NH) participated. They were asked to identify…

  4. Decrease in monocular sleep after sleep deprivation in the domestic chicken

    NARCIS (Netherlands)

    Boerema, AS; Riedstra, B; Strijkstra, AM

    2003-01-01

    We investigated the trade-off between sleep need and alertness, by challenging chickens to modify their monocular sleep. We sleep deprived domestic chickens (Gallus domesticus) to increase their sleep need. We found that in response to sleep deprivation the fraction of monocular sleep within sleep

  5. [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.

  6. A geometric method for computing ocular kinematics and classifying gaze events using monocular remote eye tracking in a robotic environment.

    Science.gov (United States)

    Singh, Tarkeshwar; Perry, Christopher M; Herter, Troy M

    2016-01-26

    Robotic and virtual-reality systems offer tremendous potential for improving assessment and rehabilitation of neurological disorders affecting the upper extremity. A key feature of these systems is that visual stimuli are often presented within the same workspace as the hands (i.e., peripersonal space). Integrating video-based remote eye tracking with robotic and virtual-reality systems can provide an additional tool for investigating how cognitive processes influence visuomotor learning and rehabilitation of the upper extremity. However, remote eye tracking systems typically compute ocular kinematics by assuming eye movements are made in a plane with constant depth (e.g. frontal plane). When visual stimuli are presented at variable depths (e.g. transverse plane), eye movements have a vergence component that may influence reliable detection of gaze events (fixations, smooth pursuits and saccades). To our knowledge, there are no available methods to classify gaze events in the transverse plane for monocular remote eye tracking systems. Here we present a geometrical method to compute ocular kinematics from a monocular remote eye tracking system when visual stimuli are presented in the transverse plane. We then use the obtained kinematics to compute velocity-based thresholds that allow us to accurately identify onsets and offsets of fixations, saccades and smooth pursuits. Finally, we validate our algorithm by comparing the gaze events computed by the algorithm with those obtained from the eye-tracking software and manual digitization. Within the transverse plane, our algorithm reliably differentiates saccades from fixations (static visual stimuli) and smooth pursuits from saccades and fixations when visual stimuli are dynamic. The proposed methods provide advancements for examining eye movements in robotic and virtual-reality systems. Our methods can also be used with other video-based or tablet-based systems in which eye movements are performed in a peripersonal

  7. Ube3a loss increases excitability and blunts orientation tuning in the visual cortex of Angelman syndrome model mice.

    Science.gov (United States)

    Wallace, Michael L; van Woerden, Geeske M; Elgersma, Ype; Smith, Spencer L; Philpot, Benjamin D

    2017-07-01

    Angelman syndrome (AS) is a neurodevelopmental disorder caused by loss of the maternally inherited allele of UBE3A Ube3a STOP/p+ mice recapitulate major features of AS in humans and allow conditional reinstatement of maternal Ube3a with the expression of Cre recombinase. We have recently shown that AS model mice exhibit reduced inhibitory drive onto layer (L)2/3 pyramidal neurons of visual cortex, which contributes to a synaptic excitatory/inhibitory imbalance. However, it remains unclear how this loss of inhibitory drive affects neural circuits in vivo. Here we examined visual cortical response properties in individual neurons to explore the consequences of Ube3a loss on intact cortical circuits and processing. Using in vivo patch-clamp electrophysiology, we measured the visually evoked responses to square-wave drifting gratings in L2/3 regular-spiking (RS) neurons in control mice, Ube3a -deficient mice, and mice in which Ube3a was conditionally reinstated in GABAergic neurons. We found that Ube3a -deficient mice exhibited enhanced pyramidal neuron excitability in vivo as well as weaker orientation tuning. These observations are the first to show alterations in cortical computation in an AS model, and they suggest a basis for cortical dysfunction in AS. NEW & NOTEWORTHY Angelman syndrome (AS) is a severe neurodevelopmental disorder caused by the loss of the gene UBE3A Using electrophysiological recording in vivo, we describe visual cortical dysfunctions in a mouse model of AS. Aberrant cellular properties in AS model mice could be improved by reinstating Ube3a in inhibitory neurons. These findings suggest that inhibitory neurons play a substantial role in the pathogenesis of AS. Copyright © 2017 the American Physiological Society.

  8. Late-onset progressive visual loss in a man with unusual MRI findings: MS, Harding's, Leber's or Leber's Plus?

    LENUS (Irish Health Repository)

    Cawley, N

    2012-02-01

    Leber\\'s hereditary optic neuropathy (LHON) is a maternally inherited disorder, typically presenting in the second and third decade. We report the case of an elderly gentleman with significant vascular risk factors, presenting with slowly progressive, bilateral, visual loss with high signal lesions in the pericallosal and periventricular deep white matter on MRI brain studies. Possible diagnoses included late-onset MS, ischaemic optic neuropathies, a mitochondrial disorder or an overlap syndrome such as Harding\\'s disease.

  9. CORRELATION OF CLINICAL AND STRUCTURAL PROGRESSION WITH VISUAL ACUITY LOSS IN MACULAR TELANGIECTASIA TYPE 2: MacTel Project Report No. 6-The MacTel Research Group.

    Science.gov (United States)

    Peto, Tunde; Heeren, Tjebo F C; Clemons, Traci E; Sallo, Ferenc B; Leung, Irene; Chew, Emily Y; Bird, Alan C

    2018-01-01

    To evaluate progression of macular telangiectasia Type 2 lesions and their correlation with visual acuity. An international multicenter prospective study with annual examinations including best-corrected visual acuity (BCVA), fundus photography, fluorescein angiography, and optical coherence tomography images graded centrally. Mixed models were used to estimate progression rates, and a generalized linear model to compute the relative risk of BCVA loss, loss of ellipsoid zone (EZ) reflectivity, development of pigment plaques, or neovascularization. One thousand and fourteen eyes of 507 participants were followed for 4.2 ± 1.6 years. Best-corrected visual acuity decreased 1.07 ± 0.05 letters (mean ± SE) per year. Of all eyes, 15% lost ≥15 letters after 5 years. Of the eyes without EZ loss, 76% developed a noncentral loss. Of the eyes with noncentral loss, 45% progressed to central EZ loss. The rate of BCVA loss in eyes with noncentral EZ loss at baseline was similar to eyes without EZ loss. The rate of BCVA loss was significantly higher in eyes with central EZ loss at baseline (-1.40 ± 0.14 letters, P structural component reflecting visual function. Its presence in the fovea significantly correlates with worse visual prognosis.

  10. The threshold for conscious report: Signal loss and response bias in visual and frontal cortex.

    Science.gov (United States)

    van Vugt, Bram; Dagnino, Bruno; Vartak, Devavrat; Safaai, Houman; Panzeri, Stefano; Dehaene, Stanislas; Roelfsema, Pieter R

    2018-05-04

    Why are some visual stimuli consciously detected, whereas others remain subliminal? We investigated the fate of weak visual stimuli in the visual and frontal cortex of awake monkeys trained to report stimulus presence. Reported stimuli were associated with strong sustained activity in the frontal cortex, and frontal activity was weaker and quickly decayed for unreported stimuli. Information about weak stimuli could be lost at successive stages en route from the visual to the frontal cortex, and these propagation failures were confirmed through microstimulation of area V1. Fluctuations in response bias and sensitivity during perception of identical stimuli were traced back to prestimulus brain-state markers. A model in which stimuli become consciously reportable when they elicit a nonlinear ignition process in higher cortical areas explained our results. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  11. A Simple Method for Estimating the Economic Cost of Productivity Loss Due to Blindness and Moderate to Severe Visual Impairment.

    Science.gov (United States)

    Eckert, Kristen A; Carter, Marissa J; Lansingh, Van C; Wilson, David A; Furtado, João M; Frick, Kevin D; Resnikoff, Serge

    2015-01-01

    To estimate the annual loss of productivity from blindness and moderate to severe visual impairment (MSVI) using simple models (analogous to how a rapid assessment model relates to a comprehensive model) based on minimum wage (MW) and gross national income (GNI) per capita (US$, 2011). Cost of blindness (COB) was calculated for the age group ≥50 years in nine sample countries by assuming the loss of current MW and loss of GNI per capita. It was assumed that all individuals work until 65 years old and that half of visual impairment prevalent in the ≥50 years age group is prevalent in the 50-64 years age group. For cost of MSVI (COMSVI), individual wage and GNI loss of 30% was assumed. Results were compared with the values of the uncorrected refractive error (URE) model of productivity loss. COB (MW method) ranged from $0.1 billion in Honduras to $2.5 billion in the United States, and COMSVI ranged from $0.1 billion in Honduras to $5.3 billion in the US. COB (GNI method) ranged from $0.1 million in Honduras to $7.8 billion in the US, and COMSVI ranged from $0.1 billion in Honduras to $16.5 billion in the US. Most GNI method values were near equivalent to those of the URE model. Although most people with blindness and MSVI live in developing countries, the highest productivity losses are in high income countries. The global economy could improve if eye care were made more accessible and more affordable to all.

  12. Visual speech alters the discrimination and identification of non-intact auditory speech in children with hearing loss.

    Science.gov (United States)

    Jerger, Susan; Damian, Markus F; McAlpine, Rachel P; Abdi, Hervé

    2017-03-01

    Understanding spoken language is an audiovisual event that depends critically on the ability to discriminate and identify phonemes yet we have little evidence about the role of early auditory experience and visual speech on the development of these fundamental perceptual skills. Objectives of this research were to determine 1) how visual speech influences phoneme discrimination and identification; 2) whether visual speech influences these two processes in a like manner, such that discrimination predicts identification; and 3) how the degree of hearing loss affects this relationship. Such evidence is crucial for developing effective intervention strategies to mitigate the effects of hearing loss on language development. Participants were 58 children with early-onset sensorineural hearing loss (CHL, 53% girls, M = 9;4 yrs) and 58 children with normal hearing (CNH, 53% girls, M = 9;4 yrs). Test items were consonant-vowel (CV) syllables and nonwords with intact visual speech coupled to non-intact auditory speech (excised onsets) as, for example, an intact consonant/rhyme in the visual track (Baa or Baz) coupled to non-intact onset/rhyme in the auditory track (/-B/aa or/-B/az). The items started with an easy-to-speechread/B/or difficult-to-speechread/G/onset and were presented in the auditory (static face) vs. audiovisual (dynamic face) modes. We assessed discrimination for intact vs. non-intact different pairs (e.g., Baa:/-B/aa). We predicted that visual speech would cause the non-intact onset to be perceived as intact and would therefore generate more same-as opposed to different-responses in the audiovisual than auditory mode. We assessed identification by repetition of nonwords with non-intact onsets (e.g.,/-B/az). We predicted that visual speech would cause the non-intact onset to be perceived as intact and would therefore generate more Baz-as opposed to az- responses in the audiovisual than auditory mode. Performance in the audiovisual mode showed more same

  13. Visual Speech Alters the Discrimination and Identification of Non-Intact Auditory Speech in Children with Hearing Loss

    Science.gov (United States)

    Jerger, Susan; Damian, Markus F.; McAlpine, Rachel P.; Abdi, Hervé

    2017-01-01

    Objectives Understanding spoken language is an audiovisual event that depends critically on the ability to discriminate and identify phonemes yet we have little evidence about the role of early auditory experience and visual speech on the development of these fundamental perceptual skills. Objectives of this research were to determine 1) how visual speech influences phoneme discrimination and identification; 2) whether visual speech influences these two processes in a like manner, such that discrimination predicts identification; and 3) how the degree of hearing loss affects this relationship. Such evidence is crucial for developing effective intervention strategies to mitigate the effects of hearing loss on language development. Methods Participants were 58 children with early-onset sensorineural hearing loss (CHL, 53% girls, M = 9;4 yrs) and 58 children with normal hearing (CNH, 53% girls, M = 9;4 yrs). Test items were consonant-vowel (CV) syllables and nonwords with intact visual speech coupled to non-intact auditory speech (excised onsets) as, for example, an intact consonant/rhyme in the visual track (Baa or Baz) coupled to non-intact onset/rhyme in the auditory track (/–B/aa or /–B/az). The items started with an easy-to-speechread /B/ or difficult-to-speechread /G/ onset and were presented in the auditory (static face) vs. audiovisual (dynamic face) modes. We assessed discrimination for intact vs. non-intact different pairs (e.g., Baa:/–B/aa). We predicted that visual speech would cause the non-intact onset to be perceived as intact and would therefore generate more same—as opposed to different—responses in the audiovisual than auditory mode. We assessed identification by repetition of nonwords with non-intact onsets (e.g., /–B/az). We predicted that visual speech would cause the non-intact onset to be perceived as intact and would therefore generate more Baz—as opposed to az— responses in the audiovisual than auditory mode. Results

  14. A low cost PSD-based monocular motion capture system

    Science.gov (United States)

    Ryu, Young Kee; Oh, Choonsuk

    2007-10-01

    This paper describes a monocular PSD-based motion capture sensor to employ with commercial video game systems such as Microsoft's XBOX and Sony's Playstation II. The system is compact, low-cost, and only requires a one-time calibration at the factory. The system includes a PSD(Position Sensitive Detector) and active infrared (IR) LED markers that are placed on the object to be tracked. The PSD sensor is placed in the focal plane of a wide-angle lens. The micro-controller calculates the 3D position of the markers using only the measured intensity and the 2D position on the PSD. A series of experiments were performed to evaluate the performance of our prototype system. From the experimental results we see that the proposed system has the advantages of the compact size, the low cost, the easy installation, and the high frame rates to be suitable for high speed motion tracking in games.

  15. Visual loss, homonymous hemianopia, and unilateral optic neuropathy as the presenting symptoms of vertebrobasilar dolichoectasia

    DEFF Research Database (Denmark)

    Mortzos, Panteleimon; Sørensen, Torben Lykke

    2013-01-01

    Vertebrobasilar dolichoectasia (VBD) is a relatively rare disorder for which unfortunately there is no treatment. Here we describe a case of simultaneous pre- and postchiasmal visual pathway pathology secondary to a space occupying VBD. In addition our patient demonstrates one of the very few cas...... of VBD compression of the retrochiasmal pathway with no other cranial nerve involvement....

  16. Longitudinal study of visual function in patients with relapsing-remitting multiple sclerosis with and without a history of optic neuritis.

    Science.gov (United States)

    González Gómez, A; García-Ben, A; Soler García, A; García-Basterra, I; Padilla Parrado, F; García-Campos, J M

    2017-03-15

    The contrast sensitivity test determines the quality of visual function in patients with multiple sclerosis (MS). The purpose of this study is to analyse changes in visual function in patients with relapsing-remitting MS with and without a history of optic neuritis (ON). We conducted a longitudinal study including 61 patients classified into 3 groups as follows: a) disease-free patients (control group); b) patients with MS and no history of ON; and c) patients with MS and a history of unilateral ON. All patients underwent baseline and 6-year follow-up ophthalmologic examinations, which included visual acuity and monocular and binocular Pelli-Robson contrast sensitivity tests. Monocular contrast sensitivity was significantly lower in MS patients with and without a history of ON than in controls both at baseline (P=.00 and P=.01, respectively) and at 6 years (P=.01 and P=.02). Patients with MS and no history of ON remained stable throughout follow-up whereas those with a history of ON displayed a significant loss of contrast sensitivity (P=.01). Visual acuity and binocular contrast sensitivity at baseline and at 6 years was significantly lower in the group of patients with a history of ON than in the control group (P=.003 and P=.002 vs P=.006 and P=.005) and the group with no history of ON (P=.04 and P=.038 vs P=.008 and P=.01). However, no significant differences were found in follow-up results (P=.1 and P=.5). Monocular Pelli-Robson contrast sensitivity test may be used to detect changes in visual function in patients with ON. Copyright © 2017 The Author(s). Publicado por Elsevier España, S.L.U. All rights reserved.

  17. Visual attention mitigates information loss in small- and large-scale neural codes.

    Science.gov (United States)

    Sprague, Thomas C; Saproo, Sameer; Serences, John T

    2015-04-01

    The visual system transforms complex inputs into robust and parsimonious neural codes that efficiently guide behavior. Because neural communication is stochastic, the amount of encoded visual information necessarily decreases with each synapse. This constraint requires that sensory signals are processed in a manner that protects information about relevant stimuli from degradation. Such selective processing--or selective attention--is implemented via several mechanisms, including neural gain and changes in tuning properties. However, examining each of these effects in isolation obscures their joint impact on the fidelity of stimulus feature representations by large-scale population codes. Instead, large-scale activity patterns can be used to reconstruct representations of relevant and irrelevant stimuli, thereby providing a holistic understanding about how neuron-level modulations collectively impact stimulus encoding. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Visual attention mitigates information loss in small- and large-scale neural codes

    Science.gov (United States)

    Sprague, Thomas C; Saproo, Sameer; Serences, John T

    2015-01-01

    Summary The visual system transforms complex inputs into robust and parsimonious neural codes that efficiently guide behavior. Because neural communication is stochastic, the amount of encoded visual information necessarily decreases with each synapse. This constraint requires processing sensory signals in a manner that protects information about relevant stimuli from degradation. Such selective processing – or selective attention – is implemented via several mechanisms, including neural gain and changes in tuning properties. However, examining each of these effects in isolation obscures their joint impact on the fidelity of stimulus feature representations by large-scale population codes. Instead, large-scale activity patterns can be used to reconstruct representations of relevant and irrelevant stimuli, providing a holistic understanding about how neuron-level modulations collectively impact stimulus encoding. PMID:25769502

  19. Braille Reading Accuracy of Students Who Are Visually Impaired: The Effects of Gender, Age at Vision Loss, and Level of Education

    Science.gov (United States)

    Argyropoulos, Vassilis; Papadimitriou, Vassilios

    2015-01-01

    Introduction: The present study assesses the performance of students who are visually impaired (that is, those who are blind or have low vision) in braille reading accuracy and examines potential correlations among the error categories on the basis of gender, age at loss of vision, and level of education. Methods: Twenty-one visually impaired…

  20. Energy loss and online directional track visualization of fast electrons with the pixel detector Timepix

    Czech Academy of Sciences Publication Activity Database

    Granja, C.; Krist, Pavel; Chvátil, David; Šolc, J.; Pospíšil, S.; Jakubek, J.; Opalka, L.

    2013-01-01

    Roč. 59, DEC (2013), s. 245-261 ISSN 1350-4487 Institutional support: RVO:61389005 Keywords : interaction of radiation with matter * dE/dx detectors * particle tracking detectors * hybrid pixel detectors * active nuclear emulsion * energy loss Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.140, year: 2013

  1. Functional assessment of the visual pathway with multifocal visual evoked potentials, and their relationship with disability in patients with multiple sclerosis.

    Science.gov (United States)

    Blanco, Román; Pérez-Rico, Consuelo; Puertas-Muñoz, Inmaculada; Ayuso-Peralta, Lucía; Boquete, Luciano; Arévalo-Serrano, Juan

    2014-02-01

    To objectively evaluate the visual function, and the relationship between disability and optic nerve dysfunction, in patients with multiple sclerosis (MS) and optic neuritis (ON), using multifocal visual evoked potentials (mfVEP). This observational, cross-sectional study assessed 28 consecutive patients with clinically definite MS, according to the McDonald criteria, and 19 age-matched healthy subjects. Disability was recorded using the Expanded Disability Status Scale (EDSS) score. The patients' mfVEP were compared to their clinical, psychophysical (Humphrey perimetry) and structural (optic coherence tomography (OCT)) diagnostic test data. We observed a significant agreement between mfVEP amplitude and Humphrey perimetry/OCT in MS-ON eyes, and between mfVEP amplitude and OCT in MS but non-ON eyes. We found significant differences in EDSS score between patients with abnormal and normal mfVEP amplitudes. Abnormal mfVEP amplitude defects (from interocular and monocular probability analysis) were found in 67.9% and 73.7% of the MS-ON and MS-non-ON group eyes, respectively. Delayed mfVEP latencies (interocular and monocular probability analysis) were seen in 70.3% and 73.7% of the MS-ON and MS-non-ON groups, respectively. We found a significant relationship between mfVEP amplitude and disease severity, as measured by EDSS score, that suggested there is a role for mfVEP amplitude as a functional biomarker of axonal loss in MS.

  2. Ergonomic evaluation of ubiquitous computing with monocular head-mounted display

    Science.gov (United States)

    Kawai, Takashi; Häkkinen, Jukka; Yamazoe, Takashi; Saito, Hiroko; Kishi, Shinsuke; Morikawa, Hiroyuki; Mustonen, Terhi; Kaistinen, Jyrki; Nyman, Göte

    2010-01-01

    In this paper, the authors conducted an experiment to evaluate the UX in an actual outdoor environment, assuming the casual use of monocular HMD to view video content while short walking. In conducting the experiment, eight subjects were asked to view news videos on a monocular HMD while walking through a large shopping mall. Two types of monocular HMDs and a hand-held media player were used, and the psycho-physiological responses of the subjects were measured before, during, and after the experiment. The VSQ, SSQ and NASA-TLX were used to assess the subjective workloads and symptoms. The objective indexes were heart rate and stride and a video recording of the environment in front of the subject's face. The results revealed differences between the two types of monocular HMDs as well as between the monocular HMDs and other conditions. Differences between the types of monocular HMDs may have been due to screen vibration during walking, and it was considered as a major factor in the UX in terms of the workload. Future experiments to be conducted in other locations will have higher cognitive loads in order to study the performance and the situation awareness to actual and media environments.

  3. Experience-independent development of the hamster circadian visual system.

    Directory of Open Access Journals (Sweden)

    August Kampf-Lassin

    2011-04-01

    Full Text Available Experience-dependent functional plasticity is a hallmark of the primary visual system, but it is not known if analogous mechanisms govern development of the circadian visual system. Here we investigated molecular, anatomical, and behavioral consequences of complete monocular light deprivation during extended intervals of postnatal development in Syrian hamsters. Hamsters were raised in constant darkness and opaque contact lenses were applied shortly after eye opening and prior to the introduction of a light-dark cycle. In adulthood, previously-occluded eyes were challenged with visual stimuli. Whereas image-formation and motion-detection were markedly impaired by monocular occlusion, neither entrainment to a light-dark cycle, nor phase-resetting responses to shifts in the light-dark cycle were affected by prior monocular deprivation. Cholera toxin-b subunit fluorescent tract-tracing revealed that in monocularly-deprived hamsters the density of fibers projecting from the retina to the suprachiasmatic nucleus (SCN was comparable regardless of whether such fibers originated from occluded or exposed eyes. In addition, long-term monocular deprivation did not attenuate light-induced c-Fos expression in the SCN. Thus, in contrast to the thalamocortical projections of the primary visual system, retinohypothalamic projections terminating in the SCN develop into normal adult patterns and mediate circadian responses to light largely independent of light experience during development. The data identify a categorical difference in the requirement for light input during postnatal development between circadian and non-circadian visual systems.

  4. Crossmodal plasticity in auditory, visual and multisensory cortical areas following noise-induced hearing loss in adulthood.

    Science.gov (United States)

    Schormans, Ashley L; Typlt, Marei; Allman, Brian L

    2017-01-01

    Complete or partial hearing loss results in an increased responsiveness of neurons in the core auditory cortex of numerous species to visual and/or tactile stimuli (i.e., crossmodal plasticity). At present, however, it remains uncertain how adult-onset partial hearing loss affects higher-order cortical areas that normally integrate audiovisual information. To that end, extracellular electrophysiological recordings were performed under anesthesia in noise-exposed rats two weeks post-exposure (0.8-20 kHz at 120 dB SPL for 2 h) and age-matched controls to characterize the nature and extent of crossmodal plasticity in the dorsal auditory cortex (AuD), an area outside of the auditory core, as well as in the neighboring lateral extrastriate visual cortex (V2L), an area known to contribute to audiovisual processing. Computer-generated auditory (noise burst), visual (light flash) and combined audiovisual stimuli were delivered, and the associated spiking activity was used to determine the response profile of each neuron sampled (i.e., unisensory, subthreshold multisensory or bimodal). In both the AuD cortex and the multisensory zone of the V2L cortex, the maximum firing rates were unchanged following noise exposure, and there was a relative increase in the proportion of neurons responsive to visual stimuli, with a concomitant decrease in the number of neurons that were solely responsive to auditory stimuli despite adjusting the sound intensity to account for each rat's hearing threshold. These neighboring cortical areas differed, however, in how noise-induced hearing loss affected audiovisual processing; the total proportion of multisensory neurons significantly decreased in the V2L cortex (control 38.8 ± 3.3% vs. noise-exposed 27.1 ± 3.4%), and dramatically increased in the AuD cortex (control 23.9 ± 3.3% vs. noise-exposed 49.8 ± 6.1%). Thus, following noise exposure, the cortical area showing the greatest relative degree of multisensory convergence

  5. A Frontal Lobe Meningioma in a Child Leading to Visual Loss

    Directory of Open Access Journals (Sweden)

    Nedime Sahinoglu-Keşkek

    2015-01-01

    Full Text Available Objective. Meningiomas are benign primary meningeal tumors and are seen rare in children and adolescents. Clinical Presentation and Intervention. A 15-year-old Turkish boy reported a 1-month history of headache and blurred vision in both eyes. His visual acuity was 0.3 in both eyes with papilledema. Magnetic resonance imaging showed a 77×97×77 mm intracranial-extra-axial frontal lesion which compresses the chiasm. He was diagnosed with intracranial meningioma and referred to neurosurgery clinic. Conclusion. Ophthalmologists should be aware of the fact that papilledema and low vision can be caused by an intracranial tumor which compresses optic chiasm.

  6. Sleep deprivation accelerates delay-related loss of visual short-term memories without affecting precision.

    Science.gov (United States)

    Wee, Natalie; Asplund, Christopher L; Chee, Michael W L

    2013-06-01

    Visual short-term memory (VSTM) is an important measure of information processing capacity and supports many higher-order cognitive processes. We examined how sleep deprivation (SD) and maintenance duration interact to influence the number and precision of items in VSTM using an experimental design that limits the contribution of lapses at encoding. For each trial, participants attempted to maintain the location and color of three stimuli over a delay. After a retention interval of either 1 or 10 seconds, participants reported the color of the item at the cued location by selecting it on a color wheel. The probability of reporting the probed item, the precision of report, and the probability of reporting a nonprobed item were determined using a mixture-modeling analysis. Participants were studied twice in counterbalanced order, once after a night of normal sleep and once following a night of sleep deprivation. Sleep laboratory. Nineteen healthy college age volunteers (seven females) with regular sleep patterns. Approximately 24 hours of total SD. SD selectively reduced the number of integrated representations that can be retrieved after a delay, while leaving the precision of object information in the stored representations intact. Delay interacted with SD to lower the rate of successful recall. Visual short-term memory is compromised during sleep deprivation, an effect compounded by delay. However, when memories are retrieved, they tend to be intact.

  7. The prevalence of vision loss due to ocular trauma in the Australian National Eye Health Survey.

    Science.gov (United States)

    Keel, Stuart; Xie, Jing; Foreman, Joshua; Taylor, Hugh R; Dirani, Mohamed

    2017-11-01

    To determine the prevalence of vision loss due to ocular trauma in Australia. The National Eye Health Survey (NEHS) is a population-based cross-sectional study that examined 3098 non-Indigenous Australians (aged 50-98 years) and 1738 Indigenous Australians (aged 40-92 years) living in 30 randomly selected sites, stratified by remoteness. An eye was considered to have vision loss due to trauma if the best-corrected visual acuity was worse than 6/12 and the main cause was attributed to ocular trauma. This determination was made by two independent ophthalmologists and any disagreements were adjudicated by a third senior ophthalmologist. The sampling weight adjusted prevalence of vision loss due to ocular trauma in non-Indigenous Australians aged 50 years and older and Indigenous Australians aged 40 years and over was 0.24% (95%CI: 0.10, 0.52) and 0.79% (95%CI: 0.56, 1.13), respectively. Trauma was attributed as an underlying cause of bilateral vision loss in one Indigenous participant, with all other cases being monocular. Males displayed a higher prevalence of vision loss from ocular trauma than females in both the non-Indigenous (0.47% vs. 1.25%, p=0.03) and Indigenous populations (0.12% vs. 0.38%, p=0.02). After multivariate adjustments, residing in Very Remote geographical areas was associated with higher odds of vision loss from ocular trauma. We estimate that 2.4 per 1000 non-Indigenous and 7.9 per 1000 Indigenous Australian adults have monocular vision loss due to a previous severe ocular trauma. Our findings indicate that males, Indigenous Australians and those residing in Very Remote communities may benefit from targeted health promotion to improve awareness of trauma prevention strategies. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Thin minimal rim width at Bruch’s membrane opening is associated with glaucomatous paracentral visual field loss

    Directory of Open Access Journals (Sweden)

    Taniguchi EV

    2017-12-01

    Full Text Available Elise V Taniguchi,1–3 Eleftherios I Paschalis,1,2 Dejiao Li,1,4 Kouros Nouri-Mahdavi,5 Stacey C Brauner,1 Scott H Greenstein,1 Angela V Turalba,1 Janey L Wiggs,1 Louis R Pasquale,1,6 Lucy Q Shen1 1Department of Ophthalmology, Harvard Medical School, Massachusetts Eye and Ear, Boston, MA, 2Boston Keratoprosthesis Laboratory, Massachusetts Eye and Ear – Schepens Eye Research Institute, Harvard Medical School, Boston, MA, USA; 3Department of Ophthalmology, Universidade Federal de São Paulo, São Paulo, Brazil; 4Department of Ophthalmology, Beijing China-Japan Friendship Hospital, Beijing, People’s Republic of China; 5Department of Ophthalmology, David Geffen School of Medicine and Stein Eye Institute, Los Angeles, CA, USA; 6Channing Division of Network Medicine, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA Purpose: To compare optic nerve head (ONH measurements in glaucomatous eyes with paracentral visual field (VF loss to eyes with peripheral VF loss and controls.Methods: Open-angle glaucoma (OAG patients with early paracentral VF loss or isolated peripheral VF loss as well as control subjects underwent ONH imaging with swept-source optical coherence tomography (OCT and retinal nerve fiber layer (RNFL imaging with spectral-domain OCT. Minimum rim width at Bruch’s membrane opening (BMO-MRW, lamina cribrosa depth (LCD, and RNFL thickness were compared among the glaucoma and control groups with one-way analysis of variance, Kruskal–Wallis test, and multiple regression analysis.Results: Twenty-nine eyes from 29 OAG patients (15 early paracentral and 14 isolated peripheral VF loss and 20 eyes of 20 control subjects were included. The early paracentral and isolated peripheral VF loss groups had similar VF mean deviation (MD (–5.3±2.7 dB and –3.7±3.0 dB, p=0.15, respectively. Global BMO-MRW was lower in OAG eyes than in controls (193.8±40.0 vs 322.7±62.2 µm, p<0.001, but similar

  9. Quantifying visual pathway axonal and myelin loss in multiple sclerosis and neuromyelitis optica.

    Science.gov (United States)

    Manogaran, Praveena; Vavasour, Irene M; Lange, Alex P; Zhao, Yinshan; McMullen, Katrina; Rauscher, Alexander; Carruthers, Robert; Li, David K B; Traboulsee, Anthony L; Kolind, Shannon H

    2016-01-01

    The optic nerve is frequently injured in multiple sclerosis and neuromyelitis optica, resulting in visual dysfunction, which may be reflected by measures distant from the site of injury. To determine how retinal nerve fiber layer as a measure of axonal health, and macular volume as a measure of neuronal health are related to changes in myelin water fraction in the optic radiations of multiple sclerosis and neuromyelitis optica participants with and without optic neuritis and compared to healthy controls. 12 healthy controls, 42 multiple sclerosis (16 with optic neuritis), and 10 neuromyelitis optica participants (8 with optic neuritis) were included in this study. Optical coherence tomography assessment involved measurements of the segmented macular layers (total macular, ganglion cell layer, inner plexiform layer, and inner nuclear layer volume) and paripapillary retinal nerve fiber layer thickness. The MRI protocol included a 32-echo T2-relaxation GRASE sequence. Average myelin water fraction values were calculated within the optic radiations as a measure of myelin density. Multiple sclerosis and neuromyelitis optica eyes with optic neuritis history had lower retinal nerve fiber layer thickness, total macular, ganglion cell and inner plexiform layer volumes compared to eyes without optic neuritis history and controls. Inner nuclear layer volume increased in multiple sclerosis with optic neuritis history (mean = 0.99 mm(3), SD = 0.06) compared to those without (mean = 0.97 mm(3), SD = 0.06; p = 0.003). Mean myelin water fraction in the optic radiations was significantly lower in demyelinating diseases (neuromyelitis optica: mean = 0.098, SD = 0.01, multiple sclerosis with optic neuritis history: mean = 0.096, SD = 0.01, multiple sclerosis without optic neuritis history: mean = 0.098, SD = 0.02; F3,55 = 3.35, p = 0.03) compared to controls. Positive correlations between MRI and optical coherence tomography measures were also apparent

  10. Dissociable loss of the representations in visual short-term memory.

    Science.gov (United States)

    Li, Jie

    2016-01-01

    The present study investigated in what manner the information in visual short-term memory (VSTM) is lost. Participants memorized four items, one of which was given higher priority later by a retro-cue. Then participants were required to detect a possible change, which could be either a large or small change, occurred to one of the items. The results showed that the detection performance for the small change of the uncued items was poorer than the cued item, yet large change that occurred to all four memory items could be detected perfectly, indicating that the uncued representations lost some detailed information yet still had some basic features retained in VSTM. The present study suggests that after being encoded into VSTM, the information is not lost in an object-based manner; rather, features of an item are still dissociable, so that they can be lost separately.

  11. Observation of mass loss in R CrB during the visual light minimum

    International Nuclear Information System (INIS)

    Kameswara Rao, N.

    1981-01-01

    Visual light minima of R CrB stars are thought to be caused by the formation of circumstellar dust. It has been observed at the time of the light minimum that there is difference in the reddening between the descending and the rising branches of the light curves. The extinction during the descending branch tends to be neutral with not much of colour change, while there occurs redder colours during the recovery part of the light curve (Forrest 1974). It is probable that the gas causing the broad emission lines with Ne approximately 5 x 10 11 cm -3 also produces the neutral extinction due to electron scattering. An extinction of 4.5 mag can result if this region is assumed to extend to 2R. (Auth.)

  12. Stereo using monocular cues within the tensor voting framework.

    Science.gov (United States)

    Mordohai, Philippos; Medioni, Gérard

    2006-06-01

    We address the fundamental problem of matching in two static images. The remaining challenges are related to occlusion and lack of texture. Our approach addresses these difficulties within a perceptual organization framework, considering both binocular and monocular cues. Initially, matching candidates for all pixels are generated by a combination of matching techniques. The matching candidates are then embedded in disparity space, where perceptual organization takes place in 3D neighborhoods and, thus, does not suffer from problems associated with scanline or image neighborhoods. The assumption is that correct matches produce salient, coherent surfaces, while wrong ones do not. Matching candidates that are consistent with the surfaces are kept and grouped into smooth layers. Thus, we achieve surface segmentation based on geometric and not photometric properties. Surface overextensions, which are due to occlusion, can be corrected by removing matches whose projections are not consistent in color with their neighbors of the same surface in both images. Finally, the projections of the refined surfaces on both images are used to obtain disparity hypotheses for unmatched pixels. The final disparities are selected after a second tensor voting stage, during which information is propagated from more reliable pixels to less reliable ones. We present results on widely used benchmark stereo pairs.

  13. Implementation of a method to visualize noise-induced hearing loss in mass stranded cetaceans

    Science.gov (United States)

    Morell, Maria; Brownlow, Andrew; McGovern, Barry; Raverty, Stephen A.; Shadwick, Robert E.; André, Michel

    2017-02-01

    Assessment of the impact of noise over-exposure in stranded cetaceans is challenging, as the lesions that lead to hearing loss occur at the cellular level and inner ear cells are very sensitive to autolysis. Distinguishing ante-mortem pathology from post-mortem change has been a major constraint in diagnosing potential impact. Here, we outline a methodology applicable to the detection of noise-induced hearing loss in stranded cetaceans. Inner ears from two mass strandings of long-finned pilot whales in Scotland were processed for scanning electron microscopy observation. In one case, a juvenile animal, whose ears were fixed within 4 hours of death, revealed that many sensory cells at the apex of the cochlear spiral were missing. In this case, the absence of outer hair cells would be compatible with overexposure to underwater noise, affecting the region which transduces the lowest frequencies of the pilot whales hearing spectrum. Perfusion of cochlea with fixative greatly improved preservation and enabled diagnostic imaging of the organ of Corti, even 30 hours after death. This finding supports adopting a routine protocol to detect the pathological legacy of noise overexposure in mass stranded cetaceans as a key to understanding the complex processes and implications that lie behind such stranding events.

  14. Comparison of peripapillary retinal nerve fiber layer loss and visual outcome in fellow eyes following sequential bilateral non-arteritic anterior ischemic optic neuropathy.

    Science.gov (United States)

    Dotan, Gad; Kesler, Anat; Naftaliev, Elvira; Skarf, Barry

    2015-05-01

    To report on the correlation of structural damage to the axons of the optic nerve and visual outcome following bilateral non-arteritic anterior ischemic optic neuropathy. A retrospective review of the medical records of 25 patients with bilateral sequential non-arteritic anterior ischemic optic neuropathy was performed. Outcome measures were peripapillary retinal nerve fiber layer thickness measured with the Stratus optical coherence tomography scanner, visual acuity and visual field loss. Median peripapillary retinal nerve fiber layer (RNFL) thickness, mean deviation (MD) of visual field, and visual acuity of initially involved NAION eyes (54.00 µm, -17.77 decibels (dB), 0.4, respectively) were comparable to the same parameters measured following development of second NAION event in the other eye (53.70 µm, p = 0.740; -16.83 dB, p = 0.692; 0.4, p = 0.942, respectively). In patients with bilateral NAION, there was a significant correlation of peripapillary RNFL thickness (r = 0.583, p = 0.002) and MD of the visual field (r = 0.457, p = 0.042) for the pairs of affected eyes, whereas a poor correlation was found in visual acuity of these eyes (r = 0.279, p = 0.176). Peripapillary RNFL thickness following NAION was positively correlated with MD of visual field (r = 0.312, p = 0.043) and negatively correlated with logMAR visual acuity (r = -0.365, p = 0.009). In patients who experience bilateral NAION, the magnitude of RNFL loss is similar in each eye. There is a greater similarity in visual field loss than in visual acuity between the two affected eyes with NAION of the same individual.

  15. 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.

  16. Occurrence of CYP1B1 Mutations in Juvenile Open-Angle Glaucoma With Advanced Visual Field Loss.

    Science.gov (United States)

    Souzeau, Emmanuelle; Hayes, Melanie; Zhou, Tiger; Siggs, Owen M; Ridge, Bronwyn; Awadalla, Mona S; Smith, James E H; Ruddle, Jonathan B; Elder, James E; Mackey, David A; Hewitt, Alex W; Healey, Paul R; Goldberg, Ivan; Morgan, William H; Landers, John; Dubowsky, Andrew; Burdon, Kathryn P; Craig, Jamie E

    2015-07-01

    Juvenile open-angle glaucoma (JOAG) is a severe neurodegenerative eye disorder in which most of the genetic contribution remains unexplained. To assess the prevalence of pathogenic CYP1B1 sequence variants in an Australian cohort of patients with JOAG and severe visual field loss. For this cohort study, we recruited 160 patients with JOAG classified as advanced (n = 118) and nonadvanced (n = 42) through the Australian and New Zealand Registry of Advanced Glaucoma from January 1, 2007, through April 1, 2014. Eighty individuals with no evidence of glaucoma served as a control group. We defined JOAG as diagnosis before age 40 years and advanced JOAG as visual field loss in 2 of the 4 central fixation squares on a reliable visual field test result. We performed direct sequencing of the entire coding region of CYP1B1. Data analysis was performed in October 2014. Identification and characterization of CYP1B1 sequence variants. We identified 7 different pathogenic variants among 8 of 118 patients with advanced JOAG (6.8%) but none among the patients with nonadvanced JOAG. Three patients were homozygous or compound heterozygous for CYP1B1 pathogenic variants, which provided a likely basis for their disease. Five patients were heterozygous. The allele frequency among the patients with advanced JOAG (11 in 236 [4.7%]) was higher than among our controls (1 in 160 [0.6%]; P = .02; odds ratio, 7.8 [95% CI, 0.02-1.0]) or among the control population from the Exome Aggregation Consortium database (2946 of 122 960 [2.4%]; P = .02; odds ratio, 2.0 [95% CI, 0.3-0.9]). Individuals with CYP1B1 pathogenic variants, whether heterozygous or homozygous, had worse mean (SD) deviation on visual fields (-24.5 [5.1] [95% CI, -31.8 to -17.2] vs -15.6 [10.0] [95% CI, -17.1 to -13.6] dB; F1,126 = 5.90; P = .02; partial ηp2 = 0.05) and were younger at diagnosis (mean [SD] age, 23.1 [8.4] [95% CI, 17.2-29.1] vs 31.5 [8.0] [95% CI, 30.1-33.0] years; F1,122 = 7

  17. Bilateral visual loss and cerebral infarction after spleen embolization in a trauma patient with idiopathic thrombocytopenic purpura: A case report.

    Science.gov (United States)

    Wang, Wei-Ting; Li, Yu-Yu; Lin, Wan-Ching; Chen, Jen-Yin; Lan, Kuo-Mao; Sun, Cheuk-Kwan; Hung, Kuo-Chuan

    2018-04-01

    Splenic artery embolization (SAE) is a common procedure in trauma patients with blunt splenic injuries. We report a case of acute ischemic stroke following orthopedic surgery in a patient with post-SAE reactive thrombocytosis. A 37-year-old woman with idiopathic thrombocytopenic purpura (ITP) suffered from multiple trauma scheduled for open reduction and internal fixation for right tibial and left radius fracture five days after SAE. The patient did not have any thromboembolic complications, although the platelet counts increased from 43 × 10/L to 568 × 10/L within two days after SAE. Surgery was completed under general anesthesia with tracheal intubation without complications. The patient complained of visual loss followed by limb weakness on the fourth and eighth hour postoperatively. Magnetic resonance imaging (MRI) of head demonstrated ischemic change over bilateral basal ganglia, and occipital areas, suggesting the diagnosis of cortical blindness. To suppress platelet count and avoid platelet hyper-aggregation, anti-platelet drug (i.e., oral aspirin 100 mg daily), hydration, and hydroxyurea (i.e., 20 mg/kg daily) were used for the treatment of reactive thrombocytosis. Although right-sided hemiparesis persisted, the patient reported mild visual recovery. She was discharged four months after SAE with active rehabilitation. Our report highlights an increased risk of acute arterial thromboembolic events in patients with reactive thrombocytosis, especially those undergoing surgery.

  18. A novel continuous colour mapping approach for visualization of facial skin hydration and transepidermal water loss for four ethnic groups.

    Science.gov (United States)

    Voegeli, R; Rawlings, A V; Seroul, P; Summers, B

    2015-12-01

    The aim of this exploratory study was to develop a novel colour mapping approach to visualize and interpret the complexity of facial skin hydration and barrier properties of four ethnic groups (Caucasians, Indians, Chinese and Black Africans) living in Pretoria, South Africa. We measured transepidermal water loss (TEWL) and skin capacitance on 30 pre-defined sites on the forehead, cheek, jaw and eye areas of sixteen women (four per ethnic group) and took digital images of their faces. Continuous colour maps were generated by interpolating between each measured value and superimposing the values on the digital images. The complexity of facial skin hydration and skin barrier properties is revealed by these measurements and visualized by the continuous colour maps of the digital images. Overall, the Caucasian subjects had the better barrier properties followed by the Black African subjects, Chinese subjects and Indian subjects. Nevertheless, the two more darkly pigmented ethnic groups had superior skin hydration properties. Subtle differences were seen when examining the different facial sites. There exists remarkable skin capacitance and TEWL gradients within short distances on selected areas of the face. These gradients are distinctive in the different ethnic groups. In contrast to other reports, we found that darkly pigmented skin does not always have a superior barrier function and differences in skin hydration values are complex on the different parts of the face among the different ethnic groups. © 2015 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

  19. Living with vision loss

    Science.gov (United States)

    Diabetes - vision loss; Retinopathy - vision loss; Low vision; Blindness - vision loss ... of visual aids. Some options include: Magnifiers High power reading glasses Devices that make it easier to ...

  20. Monocular display unit for 3D display with correct depth perception

    Science.gov (United States)

    Sakamoto, Kunio; Hosomi, Takashi

    2009-11-01

    A study of virtual-reality system has been popular and its technology has been applied to medical engineering, educational engineering, a CAD/CAM system and so on. The 3D imaging display system has two types in the presentation method; one is a 3-D display system using a special glasses and the other is the monitor system requiring no special glasses. A liquid crystal display (LCD) recently comes into common use. It is possible for this display unit to provide the same size of displaying area as the image screen on the panel. A display system requiring no special glasses is useful for a 3D TV monitor, but this system has demerit such that the size of a monitor restricts the visual field for displaying images. Thus the conventional display can show only one screen, but it is impossible to enlarge the size of a screen, for example twice. To enlarge the display area, the authors have developed an enlarging method of display area using a mirror. Our extension method enables the observers to show the virtual image plane and to enlarge a screen area twice. In the developed display unit, we made use of an image separating technique using polarized glasses, a parallax barrier or a lenticular lens screen for 3D imaging. The mirror can generate the virtual image plane and it enlarges a screen area twice. Meanwhile the 3D display system using special glasses can also display virtual images over a wide area. In this paper, we present a monocular 3D vision system with accommodation mechanism, which is useful function for perceiving depth.

  1. Driving with binocular visual field loss? A study on a supervised on-road parcours with simultaneous eye and head tracking.

    Directory of Open Access Journals (Sweden)

    Enkelejda Kasneci

    Full Text Available Post-chiasmal visual pathway lesions and glaucomatous optic neuropathy cause binocular visual field defects (VFDs that may critically interfere with quality of life and driving licensure. The aims of this study were (i to assess the on-road driving performance of patients suffering from binocular visual field loss using a dual-brake vehicle, and (ii to investigate the related compensatory mechanisms. A driving instructor, blinded to the participants' diagnosis, rated the driving performance (passed/failed of ten patients with homonymous visual field defects (HP, including four patients with right (HR and six patients with left homonymous visual field defects (HL, ten glaucoma patients (GP, and twenty age and gender-related ophthalmologically healthy control subjects (C during a 40-minute driving task on a pre-specified public on-road parcours. In order to investigate the subjects' visual exploration ability, eye movements were recorded by means of a mobile eye tracker. Two additional cameras were used to monitor the driving scene and record head and shoulder movements. Thus this study is novel as a quantitative assessment of eye movements and an additional evaluation of head and shoulder was performed. Six out of ten HP and four out of ten GP were rated as fit to drive by the driving instructor, despite their binocular visual field loss. Three out of 20 control subjects failed the on-road assessment. The extent of the visual field defect was of minor importance with regard to the driving performance. The site of the homonymous visual field defect (HVFD critically interfered with the driving ability: all failed HP subjects suffered from left homonymous visual field loss (HL due to right hemispheric lesions. Patients who failed the driving assessment had mainly difficulties with lane keeping and gap judgment ability. Patients who passed the test displayed different exploration patterns than those who failed. Patients who passed focused longer on

  2. 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 (R 2 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.

  3. Preliminary Results for a Monocular Marker-Free Gait Measurement System

    Directory of Open Access Journals (Sweden)

    Jane Courtney

    2006-01-01

    Full Text Available This paper presents results from a novel monocular marker-free gait measurement system. The system was designed for physical and occupational therapists to monitor the progress of patients through therapy. It is based on a novel human motion capturemethod derived from model-based tracking. Testing is performed on two monocular, sagittal-view, sample gait videos – one with both the environment and the subject’s appearance and movement restricted and one in a natural environment with unrestrictedclothing and motion. Results of the modelling, tracking and analysis stages are presented along with standard gait graphs and parameters.

  4. Pediatric Oculomotor Findings during Monocular Videonystagmography: A Developmental Study.

    Science.gov (United States)

    Doettl, Steven M; Plyler, Patrick N; McCaslin, Devin L; Schay, Nancy L

    2015-09-01

    The differential diagnosis of a dizzy patient >4 yrs old is often aided by videonystagmography (VNG) testing to provide a global assessment of peripheral and central vestibular function. Although the value of a VNG evaluation is well-established, it remains unclear if the VNG test battery is as applicable to the pediatric population as it is for adults. Oculomotor testing specifically, as opposed to spontaneous, positional, and caloric testing, is dependent upon neurologic function. Thus, age and corresponding neuromaturation may have a significant effect on oculomotor findings. The purpose of this investigation was to describe the effect of age on various tests of oculomotor function during a monocular VNG examination. Specifically, this study systematically characterized the impact of age on saccade tracking, smooth pursuit tracking, and optokinetic (OPK) nystagmus. The present study used a prospective, repeated measures design. A total of 62 healthy participants were evaluated. Group 1 consisted of 29 4- to 6-yr-olds. Group 2 consisted of 33 21- to 44-yr-olds. Each participant completed a standard VNG oculomotor test battery including saccades, smooth pursuit, and OPK testing in randomized order using a commercially available system. The response metrics saccade latency, accuracy, and speed, smooth pursuit gain, OPK nystagmus gain, speed and asymmetry ratios were collected and analyzed. Significant differences were noted between groups for saccade latency, smooth pursuit gain, and OPK asymmetry ratios. Saccade latency was significantly longer for the pediatric participants compared to the adult participants. Smooth pursuit gain was significantly less for the pediatric participants compared to the adult participants. The pediatric participants also demonstrated increased OPK asymmetry ratios compared to the adult participants. Significant differences were noted between the pediatric and adult participants for saccade latency, smooth pursuit gain, and OPK

  5. Working Memory and Speech Recognition in Noise under Ecologically Relevant Listening Conditions: Effects of Visual Cues and Noise Type among Adults with Hearing Loss

    Science.gov (United States)

    Miller, Christi W.; Stewart, Erin K.; Wu, Yu-Hsiang; Bishop, Christopher; Bentler, Ruth A.; Tremblay, Kelly

    2017-01-01

    Purpose: This study evaluated the relationship between working memory (WM) and speech recognition in noise with different noise types as well as in the presence of visual cues. Method: Seventy-six adults with bilateral, mild to moderately severe sensorineural hearing loss (mean age: 69 years) participated. Using a cross-sectional design, 2…

  6. Late subsequent ocular morbidity in retinopathy of prematurity patients, with emphasis on visual loss caused by insidious 'involutive' pathology: an observational series

    DEFF Research Database (Denmark)

    Fledelius, Hans C; Jensen, Hanne

    2011-01-01

    This paper discusses late complications in eyes of surviving premature infants typically occurring years into the steady state attained after the initial ophthalmic events associated with preterm birth. The study focuses on insidious visual loss, as well as eventual vitreoretinal and anterior...

  7. Severe structural and functional visual system damage leads to profound loss of vision-related quality of life in patients with neuromyelitis optica spectrum disorders.

    Science.gov (United States)

    Schmidt, Felix; Zimmermann, Hanna; Mikolajczak, Janine; Oertel, Frederike C; Pache, Florence; Weinhold, Maria; Schinzel, Johann; Bellmann-Strobl, Judith; Ruprecht, Klemens; Paul, Friedemann; Brandt, Alexander U

    2017-01-01

    Neuromyelitis optica spectrum disorders (NMOSD) are characterized by devastating optic neuritis attacks causing more structural damage and visual impairment than in multiple sclerosis (MS). The objective of this study was to compare vision-related quality of life in NMOSD and MS patients and correlate it to structural retinal damage and visual function. Thirty-one NMOSD and 31 matched MS patients were included. Vision-related quality of life was assessed with the 39-item National Eye Institute Visual Function Questionnaire (NEI-VFQ). All patients underwent retinal optical coherence tomography and visual acuity and contrast sensitivity measurements. Vision-related quality of life was reduced in NMOSD compared to MS patients. This difference was driven by a higher incidence of bilateral and more severe optic neuritis in the NMOSD group. Retinal thinning and visual impairment were significantly greater in the NMOSD cohort. Lower vision-related quality of life was associated with more retinal damage and reduced visual function as assessed by visual acuity and contrast sensitivity. NMOSD-related bilateral ON-attacks cause severe structural damage and visual impairment that lead to severe loss of vision-related quality of life. The NEI-VFQ is a helpful tool to monitor vision-related quality of life in NMOSD patients. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Evidence for Non-Opponent Coding of Colour Information in Human Visual Cortex: Selective Loss of "Green" Sensitivity in a Subject with Damaged Ventral Occipito-Temporal Cortex.

    Science.gov (United States)

    Rauscher, Franziska G; Plant, Gordon T; James-Galton, Merle; Barbur, John L

    2011-01-01

    Damage to ventral occipito-temporal extrastriate visual cortex leads to the syndrome of prosopagnosia often with coexisting cerebral achromatopsia. A patient with this syndrome resulting in a left upper homonymous quadrantanopia, prosopagnosia, and incomplete achromatopsia is described. Chromatic sensitivity was assessed at a number of locations in the intact visual field using a dynamic luminance contrast masking technique that isolates the use of colour signals. In normal subjects chromatic detection thresholds form an elliptical contour when plotted in the Commission Internationale d'Eclairage, (x-y), chromaticity diagram. Because the extraction of colour signals in early visual processing involves opponent mechanisms, subjects with Daltonism (congenital red/green loss of sensitivity) show symmetric increase in thresholds towards the long wavelength ("red") and middle wavelength ("green") regions of the spectrum locus. This is also the case with acquired loss of chromatic sensitivity as a result of retinal or optic nerve disease. Our patient's results were an exception to this rule. Whilst his chromatic sensitivity in the central region of the visual field was reduced symmetrically for both "red/green" and "yellow/blue" directions in colour space, the subject's lower left quadrant showed a marked asymmetry in "red/green" thresholds with the greatest loss of sensitivity towards the "green" region of the spectrum locus. This spatially localized asymmetric loss of "green" but not "red" sensitivity has not been reported previously in human vision. Such loss is consistent with selective damage of neural substrates in the visual cortex that process colour information, but are spectrally non-opponent.

  9. Distance and velocity estimation using optical flow from a monocular camera

    NARCIS (Netherlands)

    Ho, H.W.; de Croon, G.C.H.E.; Chu, Q.

    2016-01-01

    Monocular vision is increasingly used in Micro Air Vehicles for navigation. In particular, optical flow, inspired by flying insects, is used to perceive vehicles’ movement with respect to the surroundings or sense changes in the environment. However, optical flow does not directly provide us the

  10. Distance and velocity estimation using optical flow from a monocular camera

    NARCIS (Netherlands)

    Ho, H.W.; de Croon, G.C.H.E.; Chu, Q.

    2017-01-01

    Monocular vision is increasingly used in micro air vehicles for navigation. In particular, optical flow, inspired by flying insects, is used to perceive vehicle movement with respect to the surroundings or sense changes in the environment. However, optical flow does not directly provide us the

  11. Three dimensional monocular human motion analysis in end-effector space

    DEFF Research Database (Denmark)

    Hauberg, Søren; Lapuyade, Jerome; Engell-Nørregård, Morten Pol

    2009-01-01

    In this paper, we present a novel approach to three dimensional human motion estimation from monocular video data. We employ a particle filter to perform the motion estimation. The novelty of the method lies in the choice of state space for the particle filter. Using a non-linear inverse kinemati...

  12. Transient monocular blindness and the risk of vascular complications according to subtype : a prospective cohort study

    NARCIS (Netherlands)

    Volkers, Eline J; Donders, Richard C J M; Koudstaal, Peter J; van Gijn, Jan; Algra, Ale; Jaap Kappelle, L

    Patients with transient monocular blindness (TMB) can present with many different symptoms, and diagnosis is usually based on the history alone. In this study, we assessed the risk of vascular complications according to different characteristics of TMB. We prospectively studied 341 consecutive

  13. Transient monocular blindness and the risk of vascular complications according to subtype: a prospective cohort study

    NARCIS (Netherlands)

    Volkers, E.J. (Eline J.); R. Donders (Rogier); P.J. Koudstaal (Peter Jan); van Gijn, J. (Jan); A. Algra (Ale); L. Jaap Kappelle

    2016-01-01

    textabstractPatients with transient monocular blindness (TMB) can present with many different symptoms, and diagnosis is usually based on the history alone. In this study, we assessed the risk of vascular complications according to different characteristics of TMB. We prospectively studied 341

  14. The effects of left and right monocular viewing on hemispheric activation.

    Science.gov (United States)

    Wang, Chao; Burtis, D Brandon; Ding, Mingzhou; Mo, Jue; Williamson, John B; Heilman, Kenneth M

    2018-03-01

    Prior research has revealed that whereas activation of the left hemisphere primarily increases the activity of the parasympathetic division of the autonomic nervous system, right-hemisphere activation increases the activity of the sympathetic division. In addition, each hemisphere primarily receives retinocollicular projections from the contralateral eye. A prior study reported that pupillary dilation was greater with left- than with right-eye monocular viewing. The goal of this study was to test the alternative hypotheses that this asymmetric pupil dilation with left-eye viewing was induced by activation of the right-hemispheric-mediated sympathetic activity, versus a reduction of left-hemisphere-mediated parasympathetic activity. Thus, this study was designed to learn whether there are changes in hemispheric activation, as measured by alteration of spontaneous alpha activity, during right versus left monocular viewing. High-density electroencephalography (EEG) was recorded from healthy participants viewing a crosshair with their right, left, or both eyes. There was a significantly less alpha power over the right hemisphere's parietal-occipital area with left and binocular viewing than with right-eye monocular viewing. The greater relative reduction of right-hemisphere alpha activity during left than during right monocular viewing provides further evidence that left-eye viewing induces greater increase in right-hemisphere activation than does right-eye viewing.

  15. Depth of Monocular Elements in a Binocular Scene: The Conditions for da Vinci Stereopsis

    Science.gov (United States)

    Cook, Michael; Gillam, Barbara

    2004-01-01

    Quantitative depth based on binocular resolution of visibility constraints is demonstrated in a novel stereogram representing an object, visible to 1 eye only, and seen through an aperture or camouflaged against a background. The monocular region in the display is attached to the binocular region, so that the stereogram represents an object which…

  16. Fast detection and modeling of human-body parts from monocular video

    NARCIS (Netherlands)

    Lao, W.; Han, Jungong; With, de P.H.N.; Perales, F.J.; Fisher, R.B.

    2009-01-01

    This paper presents a novel and fast scheme to detect different body parts in human motion. Using monocular video sequences, trajectory estimation and body modeling of moving humans are combined in a co-operating processing architecture. More specifically, for every individual person, features of

  17. Fusion and rivalry are dependent on the perceptual meaning of visual stimuli.

    Science.gov (United States)

    Andrews, Timothy J; Lotto, R Beau

    2004-03-09

    We view the world with two eyes and yet are typically only aware of a single, coherent image. Arguably the simplest explanation for this is that the visual system unites the two monocular stimuli into a common stream that eventually leads to a single coherent sensation. However, this notion is inconsistent with the well-known phenomenon of rivalry; when physically different stimuli project to the same retinal location, the ensuing perception alternates between the two monocular views in space and time. Although fundamental for understanding the principles of binocular vision and visual awareness, the mechanisms under-lying binocular rivalry remain controversial. Specifically, there is uncertainty about what determines whether monocular images undergo fusion or rivalry. By taking advantage of the perceptual phenomenon of color contrast, we show that physically identical monocular stimuli tend to rival-not fuse-when they signify different objects at the same location in visual space. Conversely, when physically different monocular stimuli are likely to represent the same object at the same location in space, fusion is more likely to result. The data suggest that what competes for visual awareness in the two eyes is not the physical similarity between images but the similarity in their perceptual/empirical meaning.

  18. c-Fos and Arc/Arg3.1 expression in auditory and visual cortices after hearing loss: Evidence of sensory crossmodal reorganization in adult rats.

    Science.gov (United States)

    Pernia, M; Estevez, S; Poveda, C; Plaza, I; Carro, J; Juiz, J M; Merchan, M A

    2017-08-15

    Cross-modal reorganization in the auditory and visual cortices has been reported after hearing and visual deficits mostly during the developmental period, possibly underlying sensory compensation mechanisms. However, there are very few data on the existence or nature and timeline of such reorganization events during sensory deficits in adulthood. In this study, we assessed long-term changes in activity-dependent immediate early genes c-Fos and Arc/Arg3.1 in auditory and neighboring visual cortical areas after bilateral deafness in young adult rats. Specifically, we analyzed qualitatively and quantitatively c-Fos and Arc/Arg3.1 immunoreactivity at 15 and 90 days after cochlea removal. We report extensive, global loss of c-Fos and Arc/Arg3.1 immunoreactive neurons in the auditory cortex 15 days after permanent auditory deprivation in adult rats, which is partly reversed 90 days after deafness. Simultaneously, the number and labeling intensity of c-Fos- and Arc/Arg3.1-immunoreactive neurons progressively increase in neighboring visual cortical areas from 2 weeks after deafness and these changes stabilize three months after inducing the cochlear lesion. These findings support plastic, compensatory, long-term changes in activity in the auditory and visual cortices after auditory deprivation in the adult rats. Further studies may clarify whether those changes result in perceptual potentiation of visual drives on auditory regions of the adult cortex. © 2017 The Authors The Journal of Comparative Neurology Published by Wiley Periodicals, Inc.

  19. Visual servo control for a human-following robot

    CSIR Research Space (South Africa)

    Burke, Michael G

    2011-03-01

    Full Text Available This thesis presents work completed on the design of control and vision components for use in a monocular vision-based human-following robot. The use of vision in a controller feedback loop is referred to as vision-based or visual servo control...

  20. Chronic intraventricular administration of lysergic acid diethylamide (LSD) affects the sensitivity of cortical cells to monocular deprivation.

    Science.gov (United States)

    McCall, M A; Tieman, D G; Hirsch, H V

    1982-11-04

    In kittens, but not in adult cats, depriving one eye of pattern vision by suturing the lids shut (monocular deprivation or MD) for one week reduces the proportion of binocular units in the visual cortex. A sensitivity of cortical units in adult cats to MD can be produced by infusing exogenous monoamines into the visual cortex. Since LSD interacts with monoamines, we have examined the effects of chronic administration of LSD on the sensitivity to MD for cortical cells in adult cats. Cats were assigned randomly to one of four conditions: MD/LSD, MD/No-LSD, No-MD/LSD, No-MD/No-LSD. An osmotic minipump delivered either LSD or the vehicle solution alone during a one-week period of MD. The animals showed no obvious anomalies during the administration of the drug. After one week the response properties of single units in area 17 of the visual cortex were studied without knowledge of the contents of the individual minipumps. With the exception of ocular dominance, the response properties of units recorded in all animals did not differ from normal. In the control animals (MD/No-LSD, No-MD/LSD, No-MD/No-LSD) the average proportion of binocular cells was 78%; similar to that observed for normal adult cats. However, in the experimental animals, which received LSD during the period of MD, only 52% of the cells were binocular. Our results suggest that chronic intraventricular administration of LSD affects either directly or indirectly the sensitivity of cortical neurons to MD.

  1. Retinotopic maps and foveal suppression in the visual cortex of amblyopic adults.

    Science.gov (United States)

    Conner, Ian P; Odom, J Vernon; Schwartz, Terry L; Mendola, Janine D

    2007-08-15

    Amblyopia is a developmental visual disorder associated with loss of monocular acuity and sensitivity as well as profound alterations in binocular integration. Abnormal connections in visual cortex are known to underlie this loss, but the extent to which these abnormalities are regionally or retinotopically specific has not been fully determined. This functional magnetic resonance imaging (fMRI) study compared the retinotopic maps in visual cortex produced by each individual eye in 19 adults (7 esotropic strabismics, 6 anisometropes and 6 controls). In our standard viewing condition, the non-tested eye viewed a dichoptic homogeneous mid-level grey stimulus, thereby permitting some degree of binocular interaction. Regions-of-interest analysis was performed for extrafoveal V1, extrafoveal V2 and the foveal representation at the occipital pole. In general, the blood oxygenation level-dependent (BOLD) signal was reduced for the amblyopic eye. At the occipital pole, population receptive fields were shifted to represent more parafoveal locations for the amblyopic eye, compared with the fellow eye, in some subjects. Interestingly, occluding the fellow eye caused an expanded foveal representation for the amblyopic eye in one early-onset strabismic subject with binocular suppression, indicating real-time cortical remapping. In addition, a few subjects actually showed increased activity in parietal and temporal cortex when viewing with the amblyopic eye. We conclude that, even in a heterogeneous population, abnormal early visual experience commonly leads to regionally specific cortical adaptations.

  2. Relationship between the Retinal Nerve Fibre Layer (RNFL parameters and Visual field loss in established glaucoma patients in South Indian population

    Directory of Open Access Journals (Sweden)

    Elangovan Suma, Puri K Sanjeev

    2013-10-01

    Full Text Available Purpose: Optical coherence tomography (OCT and Scanning LASER polarimetry (GDX-VCC are newer techniques to analyse retinal nerve fibre loss in glaucoma. This study aims to evaluate the relationship between the Retinal Nerve Fibre Layer(RNFL parameters measured using Stratus-OCT and GDx-VCC and visual field loss by Octopus interzeag perimetry in established glaucoma patients in South Indian Population. Materials and methods: Prospectively planned cross sectional study of 67 eyes of 34 established glaucoma patients on medical management. The mean age of patients was 46.911 years (SD+13.531. A complete ophthalmic examination, automated perimetry with octopus interzeag 1-2-3 perimeter, retinal nerve fibre analysis with GDx VCC and Stratus OCT was done. The differences between the mean RNFL parameters in the presence or absence of field defects were evaluated. Results: The data analysed were mean deviation, loss variance, OCT total average nerve fibre thickness, GDX VCC- TSNIT average and Nerve fibre indicator (NFI.The data were split into two subgroups on the basis of presence or absence of visual field defect and analysed. The difference between the mean value of NFI between the subgroups was highly significant with a p value < 0.01.The OCT parameter Total average nerve fiber layer thickness differed significantly between the two subgroups (p value <0.05. The mean GDx TSNIT average did not differ significantly between the two subgroups. Conclusion: The total average nerve fibre thickness by OCT correlated better with visual field loss than the GDX TSNIT average .Among the GDx parameters, the NFI was found to be a better indicator of visual field damage than the average thickness.

  3. Ocular Complications Following Autologous Fat Injections into Facial Area: Case Report of a Recovery from Visual Loss After Ophthalmic Artery Occlusion and a Review of the Literature.

    Science.gov (United States)

    Szantyr, Aleksandra; Orski, Michał; Marchewka, Ida; Szuta, Mariusz; Orska, Małgorzata; Zapała, Jan

    2017-06-01

    With the increase in popularity of the use of cosmetic fillers in plastic and esthetic surgery, the possibility of severe ocular complications should not be neglected. Of the fillers used, autologous fat is the most common to cause permanent visual deterioration, one of the most severe complications associated with the use of cosmetic fillers. Here we present the first report of a complete recovery of visual acuity from an instance of visual loss with no light perception caused by ophthalmic artery occlusion of the right eye following autologous fat injection in the facial area. Immediate ophthalmological intervention and comprehensive therapy with prostaglandins and vinpocetine made it possible to restore retinal perfusion and achieve complete recovery of visual acuity. Awareness of the iatrogenic artery occlusions associated with facial fillers and the need for immediate treatment should be popularized among injectors to prevent devastating consequences, such as permanent vision loss. Level of Evidence V This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

  4. The Advanced Glaucoma Intervention Study (AGIS): 12. Baseline risk factors for sustained loss of visual field and visual acuity in patients with advanced glaucoma.

    Science.gov (United States)

    2002-10-01

    To examine the relationships between baseline risk factors and sustained decrease of visual field (SDVF) and sustained decrease of visual acuity (SDVA). Cohort study of participants in the Advanced Glaucoma Intervention Study (AGIS). This multicenter study enrolled patients between 1988 and 1992 and followed them until 2001; 789 eyes of 591 patients with advanced glaucoma were randomly assigned to one of two surgical sequences, argon laser trabeculoplasty (ALT)-trabeculectomy-trabeculectomy (ATT) or trabeculectomy-ALT-trabeculectomy (TAT). This report is based on data from 747 eyes. Eyes were offered the next intervention in the sequence upon failure of the previous intervention. Failure was based on recurrent intraocular pressure elevation, visual field defect, and disk rim criteria. Study visits occurred every 6 months; potential follow-up ranged from 8 to 13 years. For each intervention sequence, Cox multiple regression analyses were used to examine the baseline characteristics for association with two vision outcomes: SDVF and SDVA. The magnitude of the association is measured by the hazard ratio (HR), where HR for binary variables is the relative change in the hazard (or risk) of the outcome in eyes with the factor divided by the hazard in eyes without the factor, and HR for continuous variables is the relative change in the hazard (or risk) of the outcome in eyes with a unit increase in the factor. Characteristics associated with increased SDVF risk in the ATT sequence are: less baseline visual field defect (hazard ratio [HR] = 0.86, P <.001, 95% CI = 0.82-0.90), male gender (HR = 2.23, P <.001, 1.54-3.23), and worse baseline visual acuity (HR = 0.96, P =.001, 0.94-0.98); in the TAT sequence: less baseline visual field defect (HR = 0.93, P =.001, 0.89-0.97) and diabetes (HR = 1.87, P =.007, 1.18-2.97). Characteristics associated with increased SDVA risk in both treatment sequences are better baseline acuity (ATT: HR = 1.05, P <.001, 1.02-1.09; TAT: HR = 1

  5. Distance Estimation by Fusing Radar and Monocular Camera with Kalman Filter

    OpenAIRE

    Feng, Yuxiang; Pickering, Simon; Chappell, Edward; Iravani, Pejman; Brace, Christian

    2017-01-01

    The major contribution of this paper is to propose a low-cost accurate distance estimation approach. It can potentially be used in driver modelling, accident avoidance and autonomous driving. Based on MATLAB and Python, sensory data from a Continental radar and a monocular dashcam were fused using a Kalman filter. Both sensors were mounted on a Volkswagen Sharan, performing repeated driving on a same route. The established system consists of three components, radar data processing, camera dat...

  6. Autocalibrating vision guided navigation of unmanned air vehicles via tactical monocular cameras in GPS denied environments

    Science.gov (United States)

    Celik, Koray

    This thesis presents a novel robotic navigation strategy by using a conventional tactical monocular camera, proving the feasibility of using a monocular camera as the sole proximity sensing, object avoidance, mapping, and path-planning mechanism to fly and navigate small to medium scale unmanned rotary-wing aircraft in an autonomous manner. The range measurement strategy is scalable, self-calibrating, indoor-outdoor capable, and has been biologically inspired by the key adaptive mechanisms for depth perception and pattern recognition found in humans and intelligent animals (particularly bats), designed to assume operations in previously unknown, GPS-denied environments. It proposes novel electronics, aircraft, aircraft systems, systems, and procedures and algorithms that come together to form airborne systems which measure absolute ranges from a monocular camera via passive photometry, mimicking that of a human-pilot like judgement. The research is intended to bridge the gap between practical GPS coverage and precision localization and mapping problem in a small aircraft. In the context of this study, several robotic platforms, airborne and ground alike, have been developed, some of which have been integrated in real-life field trials, for experimental validation. Albeit the emphasis on miniature robotic aircraft this research has been tested and found compatible with tactical vests and helmets, and it can be used to augment the reliability of many other types of proximity sensors.

  7. Monocular distance estimation from optic flow during active landing maneuvers

    International Nuclear Information System (INIS)

    Van Breugel, Floris; Morgansen, Kristi; Dickinson, Michael H

    2014-01-01

    Vision is arguably the most widely used sensor for position and velocity estimation in animals, and it is increasingly used in robotic systems as well. Many animals use stereopsis and object recognition in order to make a true estimate of distance. For a tiny insect such as a fruit fly or honeybee, however, these methods fall short. Instead, an insect must rely on calculations of optic flow, which can provide a measure of the ratio of velocity to distance, but not either parameter independently. Nevertheless, flies and other insects are adept at landing on a variety of substrates, a behavior that inherently requires some form of distance estimation in order to trigger distance-appropriate motor actions such as deceleration or leg extension. Previous studies have shown that these behaviors are indeed under visual control, raising the question: how does an insect estimate distance solely using optic flow? In this paper we use a nonlinear control theoretic approach to propose a solution for this problem. Our algorithm takes advantage of visually controlled landing trajectories that have been observed in flies and honeybees. Finally, we implement our algorithm, which we term dynamic peering, using a camera mounted to a linear stage to demonstrate its real-world feasibility. (paper)

  8. Comparison of Threshold Saccadic Vector Optokinetic Perimetry (SVOP) and Standard Automated Perimetry (SAP) in Glaucoma. Part II: Patterns of Visual Field Loss and Acceptability.

    Science.gov (United States)

    McTrusty, Alice D; Cameron, Lorraine A; Perperidis, Antonios; Brash, Harry M; Tatham, Andrew J; Agarwal, Pankaj K; Murray, Ian C; Fleck, Brian W; Minns, Robert A

    2017-09-01

    We compared patterns of visual field loss detected by standard automated perimetry (SAP) to saccadic vector optokinetic perimetry (SVOP) and examined patient perceptions of each test. A cross-sectional study was done of 58 healthy subjects and 103 with glaucoma who were tested using SAP and two versions of SVOP (v1 and v2). Visual fields from both devices were categorized by masked graders as: 0, normal; 1, paracentral defect; 2, nasal step; 3, arcuate defect; 4, altitudinal; 5, biarcuate; and 6, end-stage field loss. SVOP and SAP classifications were cross-tabulated. Subjects completed a questionnaire on their opinions of each test. We analyzed 142 (v1) and 111 (v2) SVOP and SAP test pairs. SVOP v2 had a sensitivity of 97.7% and specificity of 77.9% for identifying normal versus abnormal visual fields. SAP and SVOP v2 classifications showed complete agreement in 54% of glaucoma patients, with a further 23% disagreeing by one category. On repeat testing, 86% of SVOP v2 classifications agreed with the previous test, compared to 91% of SAP classifications; 71% of subjects preferred SVOP compared to 20% who preferred SAP. Eye-tracking perimetry can be used to obtain threshold visual field sensitivity values in patients with glaucoma and produce maps of visual field defects, with patterns exhibiting close agreement to SAP. Patients preferred eye-tracking perimetry compared to SAP. This first report of threshold eye tracking perimetry shows good agreement with conventional automated perimetry and provides a benchmark for future iterations.

  9. Refractive error, visual acuity and causes of vision loss in children in Shandong, China. The Shandong Children Eye Study.

    Directory of Open Access Journals (Sweden)

    Jian Feng Wu

    Full Text Available PURPOSE: To examine the prevalence of refractive errors and prevalence and causes of vision loss among preschool and school children in East China. METHODS: Using a random cluster sampling in a cross-sectional school-based study design, children with an age of 4-18 years were selected from kindergartens, primary schools, and junior and senior high schools in the rural Guanxian County and the city of Weihai. All children underwent a complete ocular examination including measurement of uncorrected (UCVA and best corrected visual acuity (BCVA and auto-refractometry under cycloplegia. Myopia was defined as refractive error of ≤-0.5 diopters (D, high myopia as ≤ -6.0D, and amblyopia as BCVA ≤ 20/32 without any obvious reason for vision reduction and with strabismus or refractive errors as potential reasons. RESULTS: Out of 6364 eligible children, 6026 (94.7% children participated. Prevalence of myopia (overall: 36.9 ± 0.6%;95% confidence interval (CI:36.0,38.0 increased (P<0.001 from 1.7 ± 1.2% (95%CI:0.0,4.0 in the 4-years olds to 84.6 ± 3.2% (95%CI:78.0,91.0 in 17-years olds. Myopia was associated with older age (OR:1.56;95%CI:1.52,1.60;P<0.001, female gender (OR:1.22;95%CI:1.08,1.39;P = 0.002 and urban region (OR:2.88;95%CI:2.53,3.29;P<0.001. Prevalence of high myopia (2.0 ± 0.2% increased from 0.7 ± 0.3% (95%CI:0.1,1.3 in 10-years olds to 13.9 ± 3.0 (95%CI:7.8,19.9 in 17-years olds. It was associated with older age (OR:1.50;95%CI:1.41,1.60;P<0.001 and urban region (OR:3.11;95%CI:2.08,4.66;P<0.001. Astigmatism (≥ 0.75D (36.3 ± 0.6%;95%CI:35.0,38.0 was associated with older age (P<0.001;OR:1.06;95%CI:1.04,1.09, more myopic refractive error (P<0.001;OR:0.94;95%CI:0.91,0.97 and urban region (P<0.001;OR:1.47;95%CI:1.31,1.64. BCVA was ≤ 20/40 in the better eye in 19 (0.32% children. UCVA ≤ 20/40 in at least one eye was found in 2046 (34.05% children, with undercorrected refractive error as cause in 1975 (32.9% children. Amblyopia

  10. Monocular Vision-Based Robot Localization and Target Tracking

    Directory of Open Access Journals (Sweden)

    Bing-Fei Wu

    2011-01-01

    Full Text Available This paper presents a vision-based technology for localizing targets in 3D environment. It is achieved by the combination of different types of sensors including optical wheel encoders, an electrical compass, and visual observations with a single camera. Based on the robot motion model and image sequences, extended Kalman filter is applied to estimate target locations and the robot pose simultaneously. The proposed localization system is applicable in practice because it is not necessary to have the initializing setting regarding starting the system from artificial landmarks of known size. The technique is especially suitable for navigation and target tracing for an indoor robot and has a high potential extension to surveillance and monitoring for Unmanned Aerial Vehicles with aerial odometry sensors. The experimental results present “cm” level accuracy of the localization of the targets in indoor environment under a high-speed robot movement.

  11. Visual acuity loss associated with excessive “dry macula” in exudative age-related macular degeneration

    Directory of Open Access Journals (Sweden)

    Takahashi H

    2018-02-01

    Full Text Available Hidenori Takahashi,1–3 Yuji Inoue,1,2 Xue Tan,2,3 Satoru Inoda,1 Shinichi Sakamoto,1 Yusuke Arai,1 Yasuo Yanagi,4–6 Yujiro Fujino,2,3 Hidetoshi Kawashima1 1Department of Ophthalmology, Jichi Medical University, Shimotsuke, 2Department of Ophthalmology, The University of Tokyo, Bunkyo, 3Department of Ophthalmology, Japan Community Health Care Organization Tokyo Shinjuku Medical Center, Shinjuku, Japan; 4Medical Retina, Singapore National Eye Centre, 5Medical Retina, Singapore Eye Research Institute, 6Eye-ACP, Duke NUS Medical School, National University of Singapore, Singapore Purpose: To investigate the correlation between visual acuity and central macular thickness (CMT and choroidal thickness (CCT in patients with wet age-related macular degeneration (AMD. Methods: In this retrospective analysis, 14 eyes that received >10 ranibizumab injections (based on pro re nata [PRN] regimen and maintained initial visual acuity gain were analyzed. The following 5 parameters were measured at the foveal center: CMT (distance from the inner limiting membrane [ILM] to Bruch’s membrane; central retinal thickness (CRT; distance from the ILM to the inner limit of the retinal pigment epithelium or subretinal fluid [SRF]; SRF thickness (SRFT; pigment epithelium detachment thickness (PEDT; and CCT. The correlation between the logarithm of the minimum angle of resolution (logMAR best-corrected visual acuity (BCVA and the 5 parameters was examined with generalized estimating equations. Results: CMT, CRT, and CCT were negatively correlated with logMAR BCVA (P=0.031, 0.023, and 0.036, respectively when only CMT values less than the thickness that maximized visual acuity for each eye were used for the analysis. Each 100-µm reduction in CMT, CRT, or CCT improved logMAR BCVA by -0.1, -0.08, or -0.07, respectively. SRFT and PEDT were not correlated with BCVA. The median CMT that maximized the visual acuity was 230 µm. Conclusion: Dry macula with CMT <230 µm was

  12. Return of visual function after bilateral visual loss following flow diversion embolization of a giant ophthalmic aneurysm due to both reduction in mass effect and reduction in aneurysm pulsation.

    Science.gov (United States)

    Patel, Saharsh; Fargen, Kyle M; Peters, Keith; Krall, Peter; Samy, Hazem; Hoh, Brian L

    2015-01-01

    Large and giant paraclinoid aneurysms are challenging to treat by either surgical or endovascular means. Visual dysfunction secondary to optic nerve compression and its relationship with aneurysm size, pulsation and thrombosis is poorly understood. We present a patient with a giant paraclinoid aneurysm resulting in bilateral visual loss that worsened following placement of a Pipeline Embolization Device and adjunctive coiling. Visual worsening occurred in conjunction with aneurysm thrombosis, increase in maximal aneurysm diameter and new adjacent edema. Her visual function spontaneously improved in a delayed fashion to better than pre-procedure, in conjunction with reduced aneurysmal mass effect, size and pulsation artifact on MRI. This report documents detailed ophthalmologic and MRI evidence for the role of thrombosis, aneurysm mass effect and aneurysm pulsation as causative etiologies for both cranial nerve dysfunction and delayed resolution following flow diversion treatment of large cerebral aneurysms. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  13. Auditory Preferences of Young Children with and without Hearing Loss for Meaningful Auditory-Visual Compound Stimuli

    Science.gov (United States)

    Zupan, Barbra; Sussman, Joan E.

    2009-01-01

    Experiment 1 examined modality preferences in children and adults with normal hearing to combined auditory-visual stimuli. Experiment 2 compared modality preferences in children using cochlear implants participating in an auditory emphasized therapy approach to the children with normal hearing from Experiment 1. A second objective in both…

  14. [Objective assessment of disorders of visual perception following unilateral vestibular loss. Studies of the so-called Dandy symptom].

    Science.gov (United States)

    Stoll, W; Werner, F; Kauffmann, G

    1991-02-01

    Visual ability and compensatory eye movements during defined vertical oscillation were investigated in 20 patients with unilateral lesions of labyrinthine function and in 20 normal subjects. Oscillation frequencies were performed at the rate of 1 to 1.5 Hz with an amplitude of 5 cm, comparative to head locomotions of a running person. In synchronism with this, the visual function was tested with Landolt rings. Patients complaining of subjective visual disturbance during walking and running, also presented a measurable blur of vision under test conditions. In addition, eye movements were recorded and classified into three types. However, these eye movements showed no relation to gaze function. Our results suggest that the otolith-ocular reflex may participate in adjusting the vertical eye position during vertical stimulations at low frequencies. The effect of visual disturbances in patients with labyrinthine lesions is explained by the "efference-copy" initially described by von Holst. The efference-copy is responsible for the neutralisation of provoked retinal perceptions.

  15. Google Glass Glare: disability glare produced by a head-mounted visual display.

    Science.gov (United States)

    Longley, Chris; Whitaker, David

    2016-03-01

    Head mounted displays are a type of wearable technology - a market that is projected to expand rapidly over the coming years. Probably the most well known example is the device Google Glass (or 'Glass'). Here we investigate the extent to which the device display can interfere with normal visual function by producing monocular disability glare. Contrast sensitivity was measured in two normally sighted participants, 32 and 52 years of age. Data were recorded for the right eye, the left eye and then again in a binocular condition. Measurements were taken both with and without the Glass in place, across a range of stimulus luminance levels using a two-alternative forced-choice methodology. The device produced a significant reduction in contrast sensitivity in the right eye (>0.5 log units). The level of disability glare increased as stimulus luminance was reduced in a manner consistent with intraocular light scatter, resulting in a veiling retinal illuminance. Sensitivity in the left eye was unaffected. A significant reduction in binocular contrast sensitivity occurred at lower luminance levels due to a loss of binocular summation, although binocular sensitivity was not found to fall below the sensitivity of the better monocular level (binocular inhibition). Head mounted displays such as Google Glass have the potential to cause significant disability glare in the eye exposed to the visual display, particularly under conditions of low luminance. They can also cause a more modest binocular reduction in sensitivity by eliminating the benefits of binocular summation. © 2015 The Authors Ophthalmic & Physiological Optics © 2015 The College of Optometrists.

  16. Correlation between local glaucomatous visual field defects and loss of nerve fiber layer thickness measured with polarimetry and spectral domain OCT.

    Science.gov (United States)

    Horn, Folkert K; Mardin, Christian Y; Laemmer, Robert; Baleanu, Delia; Juenemann, Anselm M; Kruse, Friedrich E; Tornow, Ralf P

    2009-05-01

    To study the correlation between local perimetric field defects and glaucoma-induced thickness reduction of the nerve layer measured in the peripapillary area with scanning laser polarimetry (SLP) and spectral domain optical coherence tomography (SOCT) and to compare the results with those of a theoretical model. The thickness of the retinal nerve fiber layer was determined in 32 sectors (11.25 degrees each) by using SLP with variable cornea compensation (GDxVCC; Laser Diagnostics, San Diego, CA) and the newly introduced high-resolution SOCT (Spectralis; Heidelberg Engineering, Heidelberg, Germany). Eighty-eight healthy subjects served as control subjects, to determine the thickness deviation in patients with glaucoma. The relationship between glaucomatous nerve fiber reduction and visual field losses was calculated in six nerve fiber bundle-related areas. Sixty-four patients at different stages of open-angle glaucoma and 26 patients with ocular hypertension underwent perimetry (Octopus G1; Haag-Streit, Köniz, Switzerland) and measurements with the two morphometric techniques. Sector-shaped analyses between local perimetric losses and reduction of the retinal nerve fiber layer thickness showed a significant association for corresponding areas except for the central visual field in SLP. Correlation coefficients were highest in the area of the nasal inferior visual field (SOCT, -0.81; SLP, -0.57). A linear model describes the association between structural and functional damage. Localized perimetric defects can be explained by reduced nerve fiber layer thickness. The data indicate that the present SOCT is useful for determining the functional-structural relationship in peripapillary areas and that association between perimetric defects and corresponding nerve fiber losses is stronger for SOCT than for the present SLP. (ClinicalTrials.gov number, NCT00494923.).

  17. Psychophysical research progress of interocular suppression in amblyopic visual system

    OpenAIRE

    Jing-Jing Li; Yi Huang

    2016-01-01

    Some recent animal experiments and psychophysical studies indicate that patients with amblyopia have a structurally intact binocular visual system that is rendered functionally monocular due to suppression, and interocular suppression is a key mechanism in visual deficits experienced by patients with amblyopia. The aim of this review is to provide an overview of recent psychophysical findings that have investigated the important role of interocular suppression in amblyopia, the measurement an...

  18. Can perceptual learning be used to treat amblyopia beyond the critical period of visual development?

    Science.gov (United States)

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

    2011-11-01

    Amblyopia presents early in childhood and affects approximately 3% of western populations. The monocular visual acuity loss is conventionally treated during the 'critical periods' of visual development by occluding or penalising the fellow eye to encourage use of the amblyopic eye. Despite the measurable success of this approach in many children, substantial numbers of people still suffer with amblyopia later in life because either they were never diagnosed in childhood, did not respond to the original treatment, the amblyopia was only partially remediated, or their acuity loss returned after cessation of treatment. In this review, we consider whether the visual deficits of this largely overlooked amblyopic group are amenable to conventional and innovative therapeutic interventions later in life, well beyond the age at which treatment is thought to be effective. There is a considerable body of evidence that residual plasticity is present in the adult visual brain and this can be harnessed to improve function in adults with amblyopia. Perceptual training protocols have been developed to optimise visual gains in this clinical population. Results thus far are extremely encouraging; marked visual improvements have been demonstrated, the perceptual benefits transfer to new visual tasks and appear to be relatively enduring. The essential ingredients of perceptual training protocols are being incorporated into video game formats, facilitating home-based interventions. Many studies support perceptual training as a tool for improving vision in amblyopes beyond the critical period. Should this novel form of treatment stand up to the scrutiny of a randomised controlled trial, clinicians may need to re-evaluate their therapeutic approach to adults with amblyopia. Ophthalmic & Physiological Optics © 2011 The College of Optometrists.

  19. Can perceptual learning be used to treat amblyopia beyond the critical period of visual development?

    Science.gov (United States)

    Astle, Andrew T.; Webb, Ben S.; McGraw, Paul V.

    2012-01-01

    Background Amblyopia presents early in childhood and affects approximately 3% of western populations. The monocular visual acuity loss is conventionally treated during the “critical periods” of visual development by occluding or penalising the fellow eye to encourage use of the amblyopic eye. Despite the measurable success of this approach in many children, substantial numbers of people still suffer with amblyopia later in life because either they were never diagnosed in childhood, did not respond to the original treatment, the amblyopia was only partially remediated, or their acuity loss returned after cessation of treatment. Purpose In this review, we consider whether the visual deficits of this largely overlooked amblyopic group are amenable to conventional and innovative therapeutic interventions later in life, well beyond the age at which treatment is thought to be effective. Recent findings There is a considerable body of evidence that residual plasticity is present in the adult visual brain and this can be harnessed to improve function in adults with amblyopia. Perceptual training protocols have been developed to optimise visual gains in this clinical population. Results thus far are extremely encouraging: marked visual improvements have been demonstrated, the perceptual benefits transfer to new visual tasks and appear to be relatively enduring. The essential ingredients of perceptual training protocols are being incorporated into video game formats, facilitating home-based interventions. Summary Many studies support perceptual training as a tool for improving vision in amblyopes beyond the critical period. Should this novel form of treatment stand up to the scrutiny of a randomised controlled trial, clinicians may need to re-evaluate their therapeutic approach to adults with amblyopia. PMID:21981034

  20. Delayed Monocular SLAM Approach Applied to Unmanned Aerial Vehicles.

    Science.gov (United States)

    Munguia, Rodrigo; Urzua, Sarquis; Grau, Antoni

    2016-01-01

    In recent years, many researchers have addressed the issue of making Unmanned Aerial Vehicles (UAVs) more and more autonomous. In this context, the state estimation of the vehicle position is a fundamental necessity for any application involving autonomy. However, the problem of position estimation could not be solved in some scenarios, even when a GPS signal is available, for instance, an application requiring performing precision manoeuvres in a complex environment. Therefore, some additional sensory information should be integrated into the system in order to improve accuracy and robustness. In this work, a novel vision-based simultaneous localization and mapping (SLAM) method with application to unmanned aerial vehicles is proposed. One of the contributions of this work is to design and develop a novel technique for estimating features depth which is based on a stochastic technique of triangulation. In the proposed method the camera is mounted over a servo-controlled gimbal that counteracts the changes in attitude of the quadcopter. Due to the above assumption, the overall problem is simplified and it is focused on the position estimation of the aerial vehicle. Also, the tracking process of visual features is made easier due to the stabilized video. Another contribution of this work is to demonstrate that the integration of very noisy GPS measurements into the system for an initial short period of time is enough to initialize the metric scale. The performance of this proposed method is validated by means of experiments with real data carried out in unstructured outdoor environments. A comparative study shows that, when compared with related methods, the proposed approach performs better in terms of accuracy and computational time.

  1. Delayed Monocular SLAM Approach Applied to Unmanned Aerial Vehicles.

    Directory of Open Access Journals (Sweden)

    Rodrigo Munguia

    Full Text Available In recent years, many researchers have addressed the issue of making Unmanned Aerial Vehicles (UAVs more and more autonomous. In this context, the state estimation of the vehicle position is a fundamental necessity for any application involving autonomy. However, the problem of position estimation could not be solved in some scenarios, even when a GPS signal is available, for instance, an application requiring performing precision manoeuvres in a complex environment. Therefore, some additional sensory information should be integrated into the system in order to improve accuracy and robustness. In this work, a novel vision-based simultaneous localization and mapping (SLAM method with application to unmanned aerial vehicles is proposed. One of the contributions of this work is to design and develop a novel technique for estimating features depth which is based on a stochastic technique of triangulation. In the proposed method the camera is mounted over a servo-controlled gimbal that counteracts the changes in attitude of the quadcopter. Due to the above assumption, the overall problem is simplified and it is focused on the position estimation of the aerial vehicle. Also, the tracking process of visual features is made easier due to the stabilized video. Another contribution of this work is to demonstrate that the integration of very noisy GPS measurements into the system for an initial short period of time is enough to initialize the metric scale. The performance of this proposed method is validated by means of experiments with real data carried out in unstructured outdoor environments. A comparative study shows that, when compared with related methods, the proposed approach performs better in terms of accuracy and computational time.

  2. [From gene to disease; genetic causes of hearing loss and visual impairment sometimes accompanied by vestibular problems (Usher syndrome)

    NARCIS (Netherlands)

    Pennings, R.J.E.; Kremer, J.M.J.; Deutman, A.F.; Kimberling, W.J.; Cremers, C.W.R.J.

    2002-01-01

    Usher syndrome is an autosomal recessively inherited disease, characterised by sensorineural hearing loss, tapetoretinal degeneration and in some cases vestibular problems. Based on the clinical heterogeneity, the disease can be classified into three clinical types (I, II and III), which have their

  3. Visual feedback attenuates mean concentric barbell velocity loss, and improves motivation, competitiveness, and perceived workload in male adolescent athletes.

    Science.gov (United States)

    Weakley, Jonathon Js; Wilson, Kyle M; Till, Kevin; Read, Dale B; Darrall-Jones, Joshua; Roe, Gregory; Phibbs, Padraic J; Jones, Ben

    2017-07-12

    It is unknown whether instantaneous visual feedback of resistance training outcomes can enhance barbell velocity in younger athletes. Therefore, the purpose of this study was to quantify the effects of visual feedback on mean concentric barbell velocity in the back squat, and to identify changes in motivation, competitiveness, and perceived workload. In a randomised-crossover design (Feedback vs. Control) feedback of mean concentric barbell velocity was or was not provided throughout a set of 10 repetitions in the barbell back squat. Magnitude-based inferences were used to assess changes between conditions, with almost certainly greater differences in mean concentric velocity between the Feedback (0.70 ±0.04 m·s) and Control (0.65 ±0.05 m·s) observed. Additionally, individual repetition mean concentric velocity ranged from possibly (repetition number two: 0.79 ±0.04 vs. 0.78 ±0.04 m·s) to almost certainly (repetition number 10: 0.58 ±0.05 vs. 0.49 ±0.05 m·s) greater when provided feedback, while almost certain differences were observed in motivation, competitiveness, and perceived workload, respectively. Providing adolescent male athletes with visual kinematic information while completing resistance training is beneficial for the maintenance of barbell velocity during a training set, potentially enhancing physical performance. Moreover, these improvements were observed alongside increases in motivation, competitiveness and perceived workload providing insight into the underlying mechanisms responsible for the performance gains observed. Given the observed maintenance of barbell velocity during a training set, practitioners can use this technique to manipulate training outcomes during resistance training.

  4. A Small Disc Area Is a Risk Factor for Visual Field Loss Progression in Primary Open-Angle Glaucoma: The Glaucoma Stereo Analysis Study.

    Science.gov (United States)

    Kitaoka, Yasushi; Tanito, Masaki; Yokoyama, Yu; Nitta, Koji; Katai, Maki; Omodaka, Kazuko; Nakazawa, Toru

    2018-01-01

    The Glaucoma Stereo Analysis Study, a cross-sectional multicenter collaborative study, used a stereo fundus camera (nonmyd WX) to assess various morphological parameters of the optic nerve head (ONH) in glaucoma patients. We compared the associations of each parameter between the visual field loss progression group and no-progression group. The study included 187 eyes of 187 patients with primary open-angle glaucoma or normal-tension glaucoma. We divided the mean deviation (MD) slope values of all patients into the progression group (field progression and patient characteristics or each ONH parameter were analyzed with Spearman's rank correlation coefficient. The MD slope averages in the progression group and no-progression group were -0.58 ± 0.28 dB/year and 0.05 ± 0.26 dB/year, respectively. Among disc parameters, vertical disc width (diameter), disc area, cup area, and cup volume in the progression group were significantly less than those in the no-progression group. Logistic regression analysis revealed a significant association between the visual field progression and disc area (odds ratio 0.49/mm 2 disc area). A smaller disc area may be associated with more rapid glaucomatous visual field progression.

  5. Uptake of diuron and concomitant loss of photosynthetic activity in leaves as visualized by imaging the red chlorophyll fluorescence.

    Science.gov (United States)

    Lichtenthaler, Hartmut K; Langsdorf, Gabriele; Buschmann, Claus

    2013-10-01

    The principles of the chlorophyll (Chl) fluorescence induction kinetics (known as Kautsky effect) and their change by the photosystem II herbicide diuron are presented together with the Chl fluorescence emission spectra of a normal and diuron-inhibited leaf. By imaging the Chl fluorescence emission of green leaves the successive uptake of diuron and the concomitant loss of photosynthetic quantum conversion from the leaf base to the leaf tip are documented.

  6. A Small Disc Area Is a Risk Factor for Visual Field Loss Progression in Primary Open-Angle Glaucoma: The Glaucoma Stereo Analysis Study

    Directory of Open Access Journals (Sweden)

    Yasushi Kitaoka

    2018-01-01

    Full Text Available Purpose. The Glaucoma Stereo Analysis Study, a cross-sectional multicenter collaborative study, used a stereo fundus camera (nonmyd WX to assess various morphological parameters of the optic nerve head (ONH in glaucoma patients. We compared the associations of each parameter between the visual field loss progression group and no-progression group. Methods. The study included 187 eyes of 187 patients with primary open-angle glaucoma or normal-tension glaucoma. We divided the mean deviation (MD slope values of all patients into the progression group (<−0.3 dB/year and no-progression group (≧−0.3 dB/year. ONH morphological parameters were calculated with prototype analysis software. The correlations between glaucomatous visual field progression and patient characteristics or each ONH parameter were analyzed with Spearman’s rank correlation coefficient. Results. The MD slope averages in the progression group and no-progression group were −0.58 ± 0.28 dB/year and 0.05 ± 0.26 dB/year, respectively. Among disc parameters, vertical disc width (diameter, disc area, cup area, and cup volume in the progression group were significantly less than those in the no-progression group. Logistic regression analysis revealed a significant association between the visual field progression and disc area (odds ratio 0.49/mm2 disc area. Conclusion. A smaller disc area may be associated with more rapid glaucomatous visual field progression.

  7. ORB-SLAM2: an Open-Source SLAM System for Monocular, Stereo and RGB-D Cameras

    OpenAIRE

    Mur-Artal, Raul; Tardos, Juan D.

    2016-01-01

    We present ORB-SLAM2 a complete SLAM system for monocular, stereo and RGB-D cameras, including map reuse, loop closing and relocalization capabilities. The system works in real-time on standard CPUs in a wide variety of environments from small hand-held indoors sequences, to drones flying in industrial environments and cars driving around a city. Our back-end based on bundle adjustment with monocular and stereo observations allows for accurate trajectory estimation with metric scale. Our syst...

  8. Comparison of Risk Factor Profiles for Primary Open-Angle Glaucoma Subtypes Defined by Pattern of Visual Field Loss: A Prospective Study.

    Science.gov (United States)

    Kang, Jae H; Loomis, Stephanie J; Rosner, Bernard A; Wiggs, Janey L; Pasquale, Louis R

    2015-04-01

    We explored whether risk factor associations differed by primary open-angle glaucoma (POAG) subtypes defined by visual field (VF) loss pattern (i.e., paracentral or peripheral). We included 77,157 women in the Nurses' Health Study (NHS) and 42,773 men in the Health Professionals Follow-up Study (HPFS 1986-2010), and incident medical record confirmed cases of paracentral (n = 440) and peripheral (n = 865) POAG subtypes. We evaluated African heritage, glaucoma family history, body mass index (BMI), mean arterial blood pressure, diabetes mellitus, physical activity, smoking, caffeine intake, and alcohol intake. We used competing risk Cox regression analyses modeling age as the metameter and stratified by age, cohort, and event type. We sequentially identified factors with the least significant differences in associations with POAG subtypes ("stepwise down" approach with P for heterogeneity [P-het] 0.10) adverse associations with both POAG subtypes were observed with glaucoma family history, diabetes, African heritage, greater caffeine intake, and higher mean arterial pressure. These data indicate that POAG with early paracentral VF loss has distinct as well as common determinants compared with POAG with peripheral VF loss.

  9. High resolution depth reconstruction from monocular images and sparse point clouds using deep convolutional neural network

    Science.gov (United States)

    Dimitrievski, Martin; Goossens, Bart; Veelaert, Peter; Philips, Wilfried

    2017-09-01

    Understanding the 3D structure of the environment is advantageous for many tasks in the field of robotics and autonomous vehicles. From the robot's point of view, 3D perception is often formulated as a depth image reconstruction problem. In the literature, dense depth images are often recovered deterministically from stereo image disparities. Other systems use an expensive LiDAR sensor to produce accurate, but semi-sparse depth images. With the advent of deep learning there have also been attempts to estimate depth by only using monocular images. In this paper we combine the best of the two worlds, focusing on a combination of monocular images and low cost LiDAR point clouds. We explore the idea that very sparse depth information accurately captures the global scene structure while variations in image patches can be used to reconstruct local depth to a high resolution. The main contribution of this paper is a supervised learning depth reconstruction system based on a deep convolutional neural network. The network is trained on RGB image patches reinforced with sparse depth information and the output is a depth estimate for each pixel. Using image and point cloud data from the KITTI vision dataset we are able to learn a correspondence between local RGB information and local depth, while at the same time preserving the global scene structure. Our results are evaluated on sequences from the KITTI dataset and our own recordings using a low cost camera and LiDAR setup.

  10. An Analytical Measuring Rectification Algorithm of Monocular Systems in Dynamic Environment

    Directory of Open Access Journals (Sweden)

    Deshi Li

    2016-01-01

    Full Text Available Range estimation is crucial for maintaining a safe distance, in particular for vision navigation and localization. Monocular autonomous vehicles are appropriate for outdoor environment due to their mobility and operability. However, accurate range estimation using vision system is challenging because of the nonholonomic dynamics and susceptibility of vehicles. In this paper, a measuring rectification algorithm for range estimation under shaking conditions is designed. The proposed method focuses on how to estimate range using monocular vision when a shake occurs and the algorithm only requires the pose variations of the camera to be acquired. Simultaneously, it solves the problem of how to assimilate results from different kinds of sensors. To eliminate measuring errors by shakes, we establish a pose-range variation model. Afterwards, the algebraic relation between distance increment and a camera’s poses variation is formulated. The pose variations are presented in the form of roll, pitch, and yaw angle changes to evaluate the pixel coordinate incensement. To demonstrate the superiority of our proposed algorithm, the approach is validated in a laboratory environment using Pioneer 3-DX robots. The experimental results demonstrate that the proposed approach improves in the range accuracy significantly.

  11. Higher Brain Functions Served by the Lowly Rodent Primary Visual Cortex

    Science.gov (United States)

    Gavornik, Jeffrey P.; Bear, Mark F.

    2014-01-01

    It has been more than 50 years since the first description of ocular dominance plasticity--the profound modification of primary visual cortex (V1) following temporary monocular deprivation. This discovery immediately attracted the intense interest of neurobiologists focused on the general question of how experience and deprivation modify the brain…

  12. [From gene to disease; genetic causes of hearing loss and visual impairment sometimes accompanied by vestibular problems (Usher syndrome)].

    Science.gov (United States)

    Pennings, R J E; Kremer, H; Deutman, A F; Kimberling, W J; Cremers, C W R J

    2002-12-07

    Usher syndrome is an autosomal recessively inherited disease, characterised by sensorineural hearing loss, tapetoretinal degeneration and in some cases vestibular problems. Based on the clinical heterogeneity, the disease can be classified into three clinical types (I, II and III), which have their own genetic subtypes (Usher 1A-Usher IG, Usher 2A-Usher 2C and Usher 3). The majority of the Usher type I cases are caused by mutations in the MYO7A gene (Usher 1B) while mutations in the USH2A gene (Usher 2A) are the cause of most cases of type II. Usher syndrome type III, caused by mutations in the USH3 gene, is frequently seen only in Finland.

  13. A Proposed Treatment for Visual Field Loss caused by Traumatic Brain Injury using Interactive Visuotactile Virtual Environment

    Science.gov (United States)

    Farkas, Attila J.; Hajnal, Alen; Shiratuddin, Mohd F.; Szatmary, Gabriella

    In this paper, we propose a novel approach of using interactive virtual environment technology in Vision Restoration Therapy caused by Traumatic Brain Injury. We called the new system Interactive Visuotactile Virtual Environment and it holds a promise of expanding the scope of already existing rehabilitation techniques. Traditional vision rehabilitation methods are based on passive psychophysical training procedures, and can last up to six months before any modest improvements can be seen in patients. A highly immersive and interactive virtual environment will allow the patient to practice everyday activities such as object identification and object manipulation through the use 3D motion sensoring handheld devices such data glove or the Nintendo Wiimote. Employing both perceptual and action components in the training procedures holds the promise of more efficient sensorimotor rehabilitation. Increased stimulation of visual and sensorimotor areas of the brain should facilitate a comprehensive recovery of visuomotor function by exploiting the plasticity of the central nervous system. Integrated with a motion tracking system and an eye tracking device, the interactive virtual environment allows for the creation and manipulation of a wide variety of stimuli, as well as real-time recording of hand-, eye- and body movements and coordination. The goal of the project is to design a cost-effective and efficient vision restoration system.

  14. Assessment of patient perception of glaucomatous visual field loss and its association with disease severity using Amsler grid.

    Directory of Open Access Journals (Sweden)

    Kenji Fujitani

    Full Text Available To investigate patients' perception of glaucomatous VF loss and its association with glaucoma severity using the Amsler grid test.In this prospective cross-sectional study, glaucoma patients with abnormal 10-2 Humphrey Swedish Interactive Threshold Algorithm-standard VF tests were enrolled consecutively. All patients underwent a black-on-white Amsler grid test for each eligible eye. They were asked to outline any perceived scotomas (areas with abnormal grid lines on the grid and then describe verbally their perception of the scotomas. Examiners asked patients to clarify their descriptions. All descriptions used by patients were recorded in their own words, which were then sorted into descriptor categories according to similar themes. The number of descriptor categories was counted for each eye. 10-2 VF mean deviation (MD was compared among eyes that reported different number of descriptor categories. The mean 10-2 VF MD values were compared among different descriptor categories.Fifty glaucoma patients (88 eyes were included. Patients used a total of 44 different descriptors for their scotomas. Patients' descriptors were classified into categories that incorporated similar themes, resulting in 4 overarching descriptor categories: Missing/White, Blurry/Gray, Black, and Not Aware. Fifty-two eyes reported one descriptor category and 19 eyes reported two descriptor categories (mean number of descriptor categories = 1.27±0.45. Eyes that reported two descriptor categories had worse VF MD than those that reported one (-17.86±10.31 dB vs. -12.08±7.53 dB; p = 0.012. When eyes were organized according to its combination of descriptor categories, each eye naturally sorted into one of the following 5 groups, in frequency order: Missing/White (27 eyes; 31%, Blurry/Gray (21 eyes; 24%, combined Missing/White and Blurry/Gray (19 eyes; 21%, Not Aware (17 eyes; 19%, and Black (4 eyes; 5%. The mean 10-2 VF MD severity order was Black (-21.18±10.59 dB, combined

  15. a Variant of Lsd-Slam Capable of Processing High-Speed Low-Framerate Monocular Datasets

    Science.gov (United States)

    Schmid, S.; Fritsch, D.

    2017-11-01

    We develop a new variant of LSD-SLAM, called C-LSD-SLAM, which is capable of performing monocular tracking and mapping in high-speed low-framerate situations such as those of the KITTI datasets. The methods used here are robust against the influence of erronously triangulated points near the epipolar direction, which otherwise causes tracking divergence.

  16. Charles Miller Fisher: the 65th anniversary of the publication of his groundbreaking study "Transient Monocular Blindness Associated with Hemiplegia".

    Science.gov (United States)

    Araújo, Tiago Fernando Souza de; Lange, Marcos; Zétola, Viviane H; Massaro, Ayrton; Teive, Hélio A G

    2017-10-01

    Charles Miller Fisher is considered the father of modern vascular neurology and one of the giants of neurology in the 20th century. This historical review emphasizes Prof. Fisher's magnificent contribution to vascular neurology and celebrates the 65th anniversary of the publication of his groundbreaking study, "Transient Monocular Blindness Associated with Hemiplegia."

  17. P3-4: Binocular Visual Acuity in Exotropia

    Directory of Open Access Journals (Sweden)

    Heekyung Yang

    2012-10-01

    Full Text Available Purpose: To investigate binocular interaction of visual acuity in patients with intermittent exotropia and its relationship with accommodative responses during binocular vision. Methods: Sixty-seven patients with intermittent exotropia of 8 years or older were included. Binocular visual acuity (BVA and monocular visual acuity (MVA were measured in sequence. Accommodative responses of both eyes were measured using the WAM-5500 autorefractor/keratometer (GrandSeiko, Fukuyama, Japan during binocular and monocular viewing conditions at 6 m. Accommodative responses during binocular vision were calculated using the difference between the refractive errors of binocular and monocular vision. Main outcome measures: Binocular interactions of visual acuity were categorized as binocular summation, equivalency, or inhibition. The prevalence of the 3 patterns of binocular interaction was investigated. Accommodative responses were correlated with differences between BVA and better MVA. Results: Most patients (41 patients, 61.2% showed binocular equivalency. Binocular inhibition and summation were noted in 6 (9.0% and 20 (29.9% patients, respectively. Linear regression analysis revealed a significant correlation between binocular interaction and accommodative responses during binocular vision (p < .001. Accommodative responses significantly correlated with the angle of exodeviation at distance (p = .002. Conclusions: In patients with intermittent exotropia, binocular inhibition is associated with increased accommodation and a larger angle of exodeviation, suggesting that accommodative convergence is a mechanism that maintains ocular alignment. Thus, BVA inhibition may be attributed to diminishing fusional control in patients with intermittent exotropia.

  18. Reduction in spontaneous firing of mouse excitatory layer 4 cortical neurons following visual classical conditioning

    Science.gov (United States)

    Bekisz, Marek; Shendye, Ninad; Raciborska, Ida; Wróbel, Andrzej; Waleszczyk, Wioletta J.

    2017-08-01

    The process of learning induces plastic changes in neuronal network of the brain. Our earlier studies on mice showed that classical conditioning in which monocular visual stimulation was paired with an electric shock to the tail enhanced GABA immunoreactivity within layer 4 of the monocular part of the primary visual cortex (V1), contralaterally to the stimulated eye. In the present experiment we investigated whether the same classical conditioning paradigm induces changes of neuronal excitability in this cortical area. Two experimental groups were used: mice that underwent 7-day visual classical conditioning and controls. Patch-clamp whole-cell recordings were performed from ex vivo slices of mouse V1. The slices were perfused with the modified artificial cerebrospinal fluid, the composition of which better mimics the brain interstitial fluid in situ and induces spontaneous activity. The neuronal excitability was characterized by measuring the frequency of spontaneous action potentials. We found that layer 4 star pyramidal cells located in the monocular representation of the "trained" eye in V1 had lower frequency of spontaneous activity in comparison with neurons from the same cortical region of control animals. Weaker spontaneous firing indicates decreased general excitability of star pyramidal neurons within layer 4 of the monocular representation of the "trained" eye in V1. Such effect could result from enhanced inhibitory processes accompanying learning in this cortical area.

  19. Real-Time Algorithm for Relative Position Estimation Between Person and Robot Using a Monocular Camera

    International Nuclear Information System (INIS)

    Lee, Jung Uk; Sun, Ju Young; Won, Mooncheol

    2013-01-01

    In this paper, we propose a real-time algorithm for estimating the relative position of a person with respect to a robot (camera) using a monocular camera. The algorithm detects the head and shoulder regions of a person using HOG (Histogram of Oriented Gradient) feature vectors and an SVM (Support Vector Machine) classifier. The size and location of the detected area are used for calculating the relative distance and angle between the person and the camera on a robot. To increase the speed of the algorithm, we use a GPU and NVIDIA's CUDA library; the resulting algorithm speed is ∼ 15 Hz. The accuracy of the algorithm is compared with the output of a SICK laser scanner

  20. A method of real-time detection for distant moving obstacles by monocular vision

    Science.gov (United States)

    Jia, Bao-zhi; Zhu, Ming

    2013-12-01

    In this paper, we propose an approach for detection of distant moving obstacles like cars and bicycles by a monocular camera to cooperate with ultrasonic sensors in low-cost condition. We are aiming at detecting distant obstacles that move toward our autonomous navigation car in order to give alarm and keep away from them. Method of frame differencing is applied to find obstacles after compensation of camera's ego-motion. Meanwhile, each obstacle is separated from others in an independent area and given a confidence level to indicate whether it is coming closer. The results on an open dataset and our own autonomous navigation car have proved that the method is effective for detection of distant moving obstacles in real-time.

  1. Real-Time Algorithm for Relative Position Estimation Between Person and Robot Using a Monocular Camera

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jung Uk [Samsung Electroics, Suwon (Korea, Republic of); Sun, Ju Young; Won, Mooncheol [Chungnam Nat' l Univ., Daejeon (Korea, Republic of)

    2013-12-15

    In this paper, we propose a real-time algorithm for estimating the relative position of a person with respect to a robot (camera) using a monocular camera. The algorithm detects the head and shoulder regions of a person using HOG (Histogram of Oriented Gradient) feature vectors and an SVM (Support Vector Machine) classifier. The size and location of the detected area are used for calculating the relative distance and angle between the person and the camera on a robot. To increase the speed of the algorithm, we use a GPU and NVIDIA's CUDA library; the resulting algorithm speed is ∼ 15 Hz. The accuracy of the algorithm is compared with the output of a SICK laser scanner.

  2. Real Time 3D Facial Movement Tracking Using a Monocular Camera

    Directory of Open Access Journals (Sweden)

    Yanchao Dong

    2016-07-01

    Full Text Available The paper proposes a robust framework for 3D facial movement tracking in real time using a monocular camera. It is designed to estimate the 3D face pose and local facial animation such as eyelid movement and mouth movement. The framework firstly utilizes the Discriminative Shape Regression method to locate the facial feature points on the 2D image and fuses the 2D data with a 3D face model using Extended Kalman Filter to yield 3D facial movement information. An alternating optimizing strategy is adopted to fit to different persons automatically. Experiments show that the proposed framework could track the 3D facial movement across various poses and illumination conditions. Given the real face scale the framework could track the eyelid with an error of 1 mm and mouth with an error of 2 mm. The tracking result is reliable for expression analysis or mental state inference.

  3. Detection and Tracking Strategies for Autonomous Aerial Refuelling Tasks Based on Monocular Vision

    Directory of Open Access Journals (Sweden)

    Yingjie Yin

    2014-07-01

    Full Text Available Detection and tracking strategies based on monocular vision are proposed for autonomous aerial refuelling tasks. The drogue attached to the fuel tanker aircraft has two important features. The grey values of the drogue's inner part are different from the external umbrella ribs, as shown in the image. The shape of the drogue's inner dark part is nearly circular. According to crucial prior knowledge, the rough and fine positioning algorithms are designed to detect the drogue. Particle filter based on the drogue's shape is proposed to track the drogue. A strategy to switch between detection and tracking is proposed to improve the robustness of the algorithms. The inner dark part of the drogue is segmented precisely in the detecting and tracking process and the segmented circular part can be used to measure its spatial position. The experimental results show that the proposed method has good performance in real-time and satisfied robustness and positioning accuracy.

  4. Robot Navigation Control Based on Monocular Images: An Image Processing Algorithm for Obstacle Avoidance Decisions

    Directory of Open Access Journals (Sweden)

    William Benn

    2012-01-01

    Full Text Available This paper covers the use of monocular vision to control autonomous navigation for a robot in a dynamically changing environment. The solution focused on using colour segmentation against a selected floor plane to distinctly separate obstacles from traversable space: this is then supplemented with canny edge detection to separate similarly coloured boundaries to the floor plane. The resulting binary map (where white identifies an obstacle-free area and black identifies an obstacle could then be processed by fuzzy logic or neural networks to control the robot’s next movements. Findings show that the algorithm performed strongly on solid coloured carpets, wooden, and concrete floors but had difficulty in separating colours in multicoloured floor types such as patterned carpets.

  5. Improvements in clinical and functional vision and perceived visual disability after first and second eye cataract surgery

    OpenAIRE

    Elliott, D.; Patla, A.; Bullimore, M.

    1997-01-01

    AIMS—To determine the improvements in clinical and functional vision and perceived visual disability after first and second eye cataract surgery.
METHODS—Clinical vision (monocular and binocular high and low contrast visual acuity, contrast sensitivity, and disability glare), functional vision (face identity and expression recognition, reading speed, word acuity, and mobility orientation), and perceived visual disability (Activities of Daily Vision Scale) were measured in 25 subjects before a...

  6. The Effects of Scattered Light from Optical Components on Visual Function

    Science.gov (United States)

    2016-02-01

    zones (e.g., 0-5° vs 5-10°) occurs, then the general distribution of scatter, uniform or not, or that some ratio of scatter between different angular...affect the sensitivity of the eye and none reported having refractive surgery within the past year (photorefractive keratectomy ( PRK ) or laser...assisted in situ keratomileusis ( LASIK )). They performed all the visual function tasks monocularly, using the right eye. 2.3 Visual Function Assessment

  7. Neuronal Responses in Visual Area V2 (V2) of Macaque Monkeys with Strabismic Amblyopia

    OpenAIRE

    Bi, H.; Zhang, B.; Tao, X.; Harwerth, R. S.; Smith, E. L.; Chino, Y. M.

    2011-01-01

    Amblyopia, a developmental disorder of spatial vision, is thought to result from a cascade of cortical deficits over several processing stages beginning at the primary visual cortex (V1). However, beyond V1, little is known about how cortical development limits the visual performance of amblyopic primates. We quantitatively analyzed the monocular and binocular responses of V1 and V2 neurons in a group of strabismic monkeys exhibiting varying depths of amblyopia. Unlike in V1, the relative eff...

  8. The groningen longitudinal glaucoma study III. The predictive value of frequency-doubling perimetry and GDx nerve fibre analyser test results for the development of glaucomatous visual field loss

    NARCIS (Netherlands)

    Heeg, G. P.; Jansonius, N. M.

    Purpose To investigate whether frequency-doubling perimetry (FDT) and nerve fibre analyser (GDx) test results are able to predict glaucomatous visual field loss in glaucoma suspect patients. Methods A large cohort of glaucoma suspect patients (patients with ocular hypertension or a positive family

  9. Cross-orientation masking in human color vision: application of a two-stage model to assess dichoptic and monocular sources of suppression.

    Science.gov (United States)

    Kim, Yeon Jin; Gheiratmand, Mina; Mullen, Kathy T

    2013-05-28

    Cross-orientation masking (XOM) occurs when the detection of a test grating is masked by a superimposed grating at an orthogonal orientation, and is thought to reveal the suppressive effects mediating contrast normalization. Medina and Mullen (2009) reported that XOM was greater for chromatic than achromatic stimuli at equivalent spatial and temporal frequencies. Here we address whether the greater suppression found in binocular color vision originates from a monocular or interocular site, or both. We measure monocular and dichoptic masking functions for red-green color contrast and achromatic contrast at three different spatial frequencies (0.375, 0.75, and 1.5 cpd, 2 Hz). We fit these functions with a modified two-stage masking model (Meese & Baker, 2009) to extract the monocular and interocular weights of suppression. We find that the weight of monocular suppression is significantly higher for color than achromatic contrast, whereas dichoptic suppression is similar for both. These effects are invariant across spatial frequency. We then apply the model to the binocular masking data using the measured values of the monocular and interocular sources of suppression and show that these are sufficient to account for color binocular masking. We conclude that the greater strength of chromatic XOM has a monocular origin that transfers through to the binocular site.

  10. SLAM-based dense surface reconstruction in monocular Minimally Invasive Surgery and its application to Augmented Reality.

    Science.gov (United States)

    Chen, Long; Tang, Wen; John, Nigel W; Wan, Tao Ruan; Zhang, Jian Jun

    2018-05-01

    While Minimally Invasive Surgery (MIS) offers considerable benefits to patients, it also imposes big challenges on a surgeon's performance due to well-known issues and restrictions associated with the field of view (FOV), hand-eye misalignment and disorientation, as well as the lack of stereoscopic depth perception in monocular endoscopy. Augmented Reality (AR) technology can help to overcome these limitations by augmenting the real scene with annotations, labels, tumour measurements or even a 3D reconstruction of anatomy structures at the target surgical locations. However, previous research attempts of using AR technology in monocular MIS surgical scenes have been mainly focused on the information overlay without addressing correct spatial calibrations, which could lead to incorrect localization of annotations and labels, and inaccurate depth cues and tumour measurements. In this paper, we present a novel intra-operative dense surface reconstruction framework that is capable of providing geometry information from only monocular MIS videos for geometry-aware AR applications such as site measurements and depth cues. We address a number of compelling issues in augmenting a scene for a monocular MIS environment, such as drifting and inaccurate planar mapping. A state-of-the-art Simultaneous Localization And Mapping (SLAM) algorithm used in robotics has been extended to deal with monocular MIS surgical scenes for reliable endoscopic camera tracking and salient point mapping. A robust global 3D surface reconstruction framework has been developed for building a dense surface using only unorganized sparse point clouds extracted from the SLAM. The 3D surface reconstruction framework employs the Moving Least Squares (MLS) smoothing algorithm and the Poisson surface reconstruction framework for real time processing of the point clouds data set. Finally, the 3D geometric information of the surgical scene allows better understanding and accurate placement AR augmentations

  11. Evidence for Non-Opponent Coding of Colour Information in Human Visual Cortex: Selective Loss of “Green” Sensitivity in a Subject with Damaged Ventral Occipito-Temporal Cortex

    Science.gov (United States)

    Rauscher, Franziska G.; Plant, Gordon T.; James-Galton, Merle; Barbur, John L.

    2011-01-01

    Damage to ventral occipito-temporal extrastriate visual cortex leads to the syndrome of prosopagnosia often with coexisting cerebral achromatopsia. A patient with this syndrome resulting in a left upper homonymous quadrantanopia, prosopagnosia, and incomplete achromatopsia is described. Chromatic sensitivity was assessed at a number of locations in the intact visual field using a dynamic luminance contrast masking technique that isolates the use of colour signals. In normal subjects chromatic detection thresholds form an elliptical contour when plotted in the Commission Internationale d’Eclairage, (x-y), chromaticity diagram. Because the extraction of colour signals in early visual processing involves opponent mechanisms, subjects with Daltonism (congenital red/green loss of sensitivity) show symmetric increase in thresholds towards the long wavelength (“red”) and middle wavelength (“green”) regions of the spectrum locus. This is also the case with acquired loss of chromatic sensitivity as a result of retinal or optic nerve disease. Our patient’s results were an exception to this rule. Whilst his chromatic sensitivity in the central region of the visual field was reduced symmetrically for both “red/green” and “yellow/blue” directions in colour space, the subject’s lower left quadrant showed a marked asymmetry in “red/green” thresholds with the greatest loss of sensitivity towards the “green” region of the spectrum locus. This spatially localized asymmetric loss of “green” but not “red” sensitivity has not been reported previously in human vision. Such loss is consistent with selective damage of neural substrates in the visual cortex that process colour information, but are spectrally non-opponent. PMID:27956924

  12. Disambiguation of Necker cube rotation by monocular and binocular depth cues: relative effectiveness for establishing long-term bias.

    Science.gov (United States)

    Harrison, Sarah J; Backus, Benjamin T; Jain, Anshul

    2011-05-11

    The apparent direction of rotation of perceptually bistable wire-frame (Necker) cubes can be conditioned to depend on retinal location by interleaving their presentation with cubes that are disambiguated by depth cues (Haijiang, Saunders, Stone, & Backus, 2006; Harrison & Backus, 2010a). The long-term nature of the learned bias is demonstrated by resistance to counter-conditioning on a consecutive day. In previous work, either binocular disparity and occlusion, or a combination of monocular depth cues that included occlusion, internal occlusion, haze, and depth-from-shading, were used to control the rotation direction of disambiguated cubes. Here, we test the relative effectiveness of these two sets of depth cues in establishing the retinal location bias. Both cue sets were highly effective in establishing a perceptual bias on Day 1 as measured by the perceived rotation direction of ambiguous cubes. The effect of counter-conditioning on Day 2, on perceptual outcome for ambiguous cubes, was independent of whether the cue set was the same or different as Day 1. This invariance suggests that a common neural population instantiates the bias for rotation direction, regardless of the cue set used. However, in a further experiment where only disambiguated cubes were presented on Day 1, perceptual outcome of ambiguous cubes during Day 2 counter-conditioning showed that the monocular-only cue set was in fact more effective than disparity-plus-occlusion for causing long-term learning of the bias. These results can be reconciled if the conditioning effect of Day 1 ambiguous trials in the first experiment is taken into account (Harrison & Backus, 2010b). We suggest that monocular disambiguation leads to stronger bias either because it more strongly activates a single neural population that is necessary for perceiving rotation, or because ambiguous stimuli engage cortical areas that are also engaged by monocularly disambiguated stimuli but not by disparity-disambiguated stimuli

  13. Generalization of Figure-Ground Segmentation from Binocular to Monocular Vision in an Embodied Biological Brain Model

    Science.gov (United States)

    2011-08-01

    figure and ground the luminance cue breaks down and gestalt contours can fail to pop out. In this case we rely on color, which, having weak stereopsis...REPORT Generalization of Figure - Ground Segmentation from Monocular to Binocular Vision in an Embodied Biological Brain Model 14. ABSTRACT 16. SECURITY...U.S. Army Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 15. SUBJECT TERMS figure - ground , neural network, object

  14. Evaluation of the Role of Monocular Video Game Play as an Adjuvant to Occlusion Therapy in the Management of Anisometropic Amblyopia.

    Science.gov (United States)

    Singh, Archita; Sharma, Pradeep; Saxena, Rohit

    2017-07-01

    To evaluate the role of monocular video game play as an adjuvant to occlusion therapy in the treatment of anisometropic amblyopia. In a prospective randomized study design, 68 children with ages ranging from 6 to 14 years who had anisometropic amblyopia with a best corrected visual acuity (BCVA) in the amblyopic eye of better than 6/36 and worse than 6/12 and no manifest strabismus were recruited. They were randomly allocated into two groups: 34 children received 1 hour per day of video game play for the first month plus 6 hours per day of occlusion therapy (video game and occlusion group) and 34 children received 6 hours per day of occlusion therapy alone (occlusion only group). Patients were then evaluated at baseline and 1 and 3 months after treatment for BCVA, stereoacuity, and contrast sensitivity. In the video game and occlusion group, BCVA improved from 0.61 ± 0.12 logarithm of the minimum angle of resolution (logMAR) at baseline to 0.51 ± 0.14 logMAR (P = .001) at 1 month and 0.40 ± 0.15 logMAR (P = .001) at 3 months. In the occlusion only group, BCVA improved from 0.65 ± 0.09 logMAR at baseline to 0.60 ± 0.10 logMAR (P = .001) at 1 month and 0.48 ± 0.10 logMAR (P = .001) at 3 months. There was significantly more improvement in the video game and occlusion group compared to the occlusion only group (P = .003 at 1 month and P = .027 at 3 months). Video game play plus occlusion therapy enhances the visual recovery in anisometropic amblyopia. [J Pediatr Ophthalmol Strabismus. 2017;54(4):244-249.]. Copyright 2017, SLACK Incorporated.

  15. Color vision loss in patients treated with chloroquine

    Directory of Open Access Journals (Sweden)

    Ventura Dora F.

    2003-01-01

    Full Text Available Patients that make use of chloroquine or hydroxychloroquine, drugs which are frequently administered for treatment of rheumatoid arthritis, lupus erithromatosus or malaria, may suffer alterations in color vision and in contrast sensitivity. The present work evaluates the visual function of these patients in a joint study of the University of São Paulo (USP, in São Paulo, and of the Federal University of Pará (UFPA, in Belém. Thirty two chloroquine user patients without alterations in the eye fundus exam were evaluated in São Paulo (n=10; aged 38 to 71 years; mean=55,8 years and in Belém (n=22; aged 20 to 67; mean=40 years. The prescribed accumulated chloroquine dose was 45 to 430 g (mean=213 g; sd = 152 g for the São Paulo group, and 36 to 540 g (mean=174 g; sd=183 g for the Belém group. Tests were performed monocularly with corrected eye refractive state. Color discrimination was evaluated using the Cambridge Colour Test (CCT: the color discrimination threshold was measured first in the protan, deutan and tritan axes and, in succession, three MacAdam's ellipses were determined. The patient's color vision was also evaluated with color arrangement tests: the Farnsworth-Munsell 100 Hue (FM100, the Farnsworth-Munsell D15, and the Lanthony Desaturated (D15d tests. We also measured the contrast sensitivity for black-and-white sine wave grating of twenty two patients. The results were compared with controls without ophthalmologic or neuro-ophthalmologic pathologies. Twenty four patients presented acquired dyschromatopsia. There were cases of selective loss (11 patients and of diffuse loss (13 patients. Although losses were present in the FM100 there was no correlation between the FM100 error score and the ellipse area measured by the CCT. Moreover, three patients that scored normal in the FM100, failed to reach normal threshold in the CCT. The Lanthony test was less sensitive than the other two tests, since it failed to indicate loss in about

  16. Stage of visual field loss and age at diagnosis in 1988 patients with different glaucomas: implications for glaucoma screening and driving ability.

    Science.gov (United States)

    Gramer, Gwendolyn; Gramer, Eugen

    2018-04-01

    To compare stage of visual field loss (VFL) and age at diagnosis between patients with different types of glaucoma with regard to glaucoma screening and driving ability. In a cross-sectional study of 1988 consecutive patients with different types of glaucoma VFL at diagnosis and age at diagnosis were assessed. Patients with binocular advanced or severe VFL were classified unable, patients with no VFL in one eye and VFL I-V (Aulhorn classification) in the other eye able, all other constellations questionably able to drive. There were significant differences in age at diagnosis between different glaucomas and between patients with different stages of VFL at diagnosis. Age-related assessment of VFL at diagnosis in normal tension glaucoma (NTG) compared to primary open-angle glaucoma (POAG) showed that NTG is not a disease of the elderly but a disease with late diagnosis at severe VFL. In POAG a solely age-related glaucoma screening, e.g. from the age of 50 years, does not sufficiently lead to diagnosis at an early stage of the disease. In POAG solely based on binocular VFL 11.5% of patients were judged unable, 29.2% questionably able to drive, in NTG 19.6%/43.1%, pigmentary glaucoma 16%/22%, pseudoexfoliation glaucoma 9.1%/16.7%, and in primary angle-closure glaucoma 14.6%/30%. Depending on type of glaucoma more than 50% of patients require counselling regarding safe driving as part of clinical care. A disease-specific, age-related perimetric examination considering additional risk factors like family history of glaucoma is essential for early detection of glaucoma and road safety.

  17. Visual Occlusion During Minimally Invasive Surgery: A Contemporary Review of Methods to Reduce Laparoscopic and Robotic Lens Fogging and Other Sources of Optical Loss.

    Science.gov (United States)

    Manning, Todd G; Perera, Marlon; Christidis, Daniel; Kinnear, Ned; McGrath, Shannon; O'Beirne, Richard; Zotov, Paul; Bolton, Damien; Lawrentschuk, Nathan

    2017-04-01

    Maintenance of optimal vision during minimally invasive surgery is crucial to maintaining operative awareness, efficiency, and safety. Hampered vision is commonly caused by laparoscopic lens fogging (LLF), which has prompted the development of various antifogging fluids and warming devices. However, limited comparative evidence exists in contemporary literature. Despite technologic advancements there remains no consensus as to superior methods to prevent LLF or restore visual acuity once LLF has occurred. We performed a review of literature to present the current body of evidence supporting the use of numerous techniques. A standardized Preferred Reporting Items for Systematic Reviews and Meta-Analysis review was performed, and PubMed, Embase, Web of Science, and Google Scholar were searched. Articles pertaining to mechanisms and prevention of LLF were reviewed. We applied no limit to year of publication or publication type and all articles encountered were included in final review. Limited original research and heterogenous outcome measures precluded meta-analytical assessment. Vision loss has a multitude of causes and although scientific theory can be applied to in vivo environments, no authors have completely characterized this complex problem. No method to prevent or correct LLF was identified as superior to others and comparative evidence is minimal. Robotic LLF was poorly investigated and aside from a single analysis has not been directly compared to standard laparoscopic fogging in any capacity. Obscured vision during surgery is hazardous and typically caused by LLF. The etiology of LLF despite application of scientific theory is yet to be definitively proven in the in vivo environment. Common methods of prevention of LLF or restoration of vision due to LLF have little evidence-based data to support their use. A multiarm comparative in vivo analysis is required to formally assess these commonly used techniques in both standard and robotic laparoscopes.

  18. Automatic Human Facial Expression Recognition Based on Integrated Classifier From Monocular Video with Uncalibrated Camera

    Directory of Open Access Journals (Sweden)

    Yu Tao

    2017-01-01

    Full Text Available An automatic recognition framework for human facial expressions from a monocular video with an uncalibrated camera is proposed. The expression characteristics are first acquired from a kind of deformable template, similar to a facial muscle distribution. After associated regularization, the time sequences from the trait changes in space-time under complete expressional production are then arranged line by line in a matrix. Next, the matrix dimensionality is reduced by a method of manifold learning of neighborhood-preserving embedding. Finally, the refined matrix containing the expression trait information is recognized by a classifier that integrates the hidden conditional random field (HCRF and support vector machine (SVM. In an experiment using the Cohn–Kanade database, the proposed method showed a comparatively higher recognition rate than the individual HCRF or SVM methods in direct recognition from two-dimensional human face traits. Moreover, the proposed method was shown to be more robust than the typical Kotsia method because the former contains more structural characteristics of the data to be classified in space-time

  19. Monocular Vision System for Fixed Altitude Flight of Unmanned Aerial Vehicles

    Directory of Open Access Journals (Sweden)

    Kuo-Lung Huang

    2015-07-01

    Full Text Available The fastest and most economical method of acquiring terrain images is aerial photography. The use of unmanned aerial vehicles (UAVs has been investigated for this task. However, UAVs present a range of challenges such as flight altitude maintenance. This paper reports a method that combines skyline detection with a stereo vision algorithm to enable the flight altitude of UAVs to be maintained. A monocular camera is mounted on the downside of the aircraft’s nose to collect continuous ground images, and the relative altitude is obtained via a stereo vision algorithm from the velocity of the UAV. Image detection is used to obtain terrain images, and to measure the relative altitude from the ground to the UAV. The UAV flight system can be set to fly at a fixed and relatively low altitude to obtain the same resolution of ground images. A forward-looking camera is mounted on the upside of the aircraft’s nose. In combination with the skyline detection algorithm, this helps the aircraft to maintain a stable flight pattern. Experimental results show that the proposed system enables UAVs to obtain terrain images at constant resolution, and to detect the relative altitude along the flight path.

  20. Chromatic and achromatic monocular deprivation produce separable changes of eye dominance in adults.

    Science.gov (United States)

    Zhou, Jiawei; Reynaud, Alexandre; Kim, Yeon Jin; Mullen, Kathy T; Hess, Robert F

    2017-11-29

    Temporarily depriving one eye of its input, in whole or in part, results in a transient shift in eye dominance in human adults, with the patched eye becoming stronger and the unpatched eye weaker. However, little is known about the role of colour contrast in these behavioural changes. Here, we first show that the changes in eye dominance and contrast sensitivity induced by monocular eye patching affect colour and achromatic contrast sensitivity equally. We next use dichoptic movies, customized and filtered to stimulate the two eyes differentially. We show that a strong imbalance in achromatic contrast between the eyes, with no colour content, also produces similar, unselective shifts in eye dominance for both colour and achromatic contrast sensitivity. Interestingly, if this achromatic imbalance is paired with similar colour contrast in both eyes, the shift in eye dominance is selective, affecting achromatic but not chromatic contrast sensitivity and revealing a dissociation in eye dominance for colour and achromatic image content. On the other hand, a strong imbalance in chromatic contrast between the eyes, with no achromatic content, produces small, unselective changes in eye dominance, but if paired with similar achromatic contrast in both eyes, no changes occur. We conclude that perceptual changes in eye dominance are strongly driven by interocular imbalances in achromatic contrast, with colour contrast having a significant counter balancing effect. In the short term, eyes can have different dominances for achromatic and chromatic contrast, suggesting separate pathways at the site of these neuroplastic changes. © 2017 The Author(s).

  1. Optimization of dynamic envelope measurement system for high speed train based on monocular vision

    Science.gov (United States)

    Wu, Bin; Liu, Changjie; Fu, Luhua; Wang, Zhong

    2018-01-01

    The definition of dynamic envelope curve is the maximum limit outline caused by various adverse effects during the running process of the train. It is an important base of making railway boundaries. At present, the measurement work of dynamic envelope curve of high-speed vehicle is mainly achieved by the way of binocular vision. There are some problems of the present measuring system like poor portability, complicated process and high cost. A new measurement system based on the monocular vision measurement theory and the analysis on the test environment is designed and the measurement system parameters, the calibration of camera with wide field of view, the calibration of the laser plane are designed and optimized in this paper. The accuracy has been verified to be up to 2mm by repeated tests and experimental data analysis. The feasibility and the adaptability of the measurement system is validated. There are some advantages of the system like lower cost, a simpler measurement and data processing process, more reliable data. And the system needs no matching algorithm.

  2. Real-Time Vehicle Speed Estimation Based on License Plate Tracking in Monocular Video Sequences

    Directory of Open Access Journals (Sweden)

    Aleksej MAKAROV

    2016-02-01

    Full Text Available A method of estimating the vehicle speed from images obtained by a fixed over-the-road monocular camera is presented. The method is based on detecting and tracking vehicle license plates. The contrast between the license plate and its surroundings is enhanced using infrared light emitting diodes and infrared camera filters. A range of the license plate height values is assumed a priori. The camera vertical angle of view is measured prior to installation. The camera tilt is continuously measured by a micro-electromechanical sensor. The distance of the license plate from the camera is theoretically derived in terms of its pixel coordinates. Inaccuracies due to the frame rate drift, to the tilt and the angle of view measurement errors, to edge pixel detection and to a coarse assumption of the vehicle license plate height are analyzed and theoretically formulated. The resulting system is computationally efficient, inexpensive and easy to install and maintain along with the existing ALPR cameras.

  3. Monocular-Based 6-Degree of Freedom Pose Estimation Technology for Robotic Intelligent Grasping Systems

    Directory of Open Access Journals (Sweden)

    Tao Liu

    2017-02-01

    Full Text Available Industrial robots are expected to undertake ever more advanced tasks in the modern manufacturing industry, such as intelligent grasping, in which robots should be capable of recognizing the position and orientation of a part before grasping it. In this paper, a monocular-based 6-degree of freedom (DOF pose estimation technology to enable robots to grasp large-size parts at informal poses is proposed. A camera was mounted on the robot end-flange and oriented to measure several featured points on the part before the robot moved to grasp it. In order to estimate the part pose, a nonlinear optimization model based on the camera object space collinearity error in different poses is established, and the initial iteration value is estimated with the differential transformation. Measuring poses of the camera are optimized based on uncertainty analysis. Also, the principle of the robotic intelligent grasping system was developed, with which the robot could adjust its pose to grasp the part. In experimental tests, the part poses estimated with the method described in this paper were compared with those produced by a laser tracker, and results show the RMS angle and position error are about 0.0228° and 0.4603 mm. Robotic intelligent grasping tests were also successfully performed in the experiments.

  4. A special role for binocular visual input during development and as a component of occlusion therapy for treatment of amblyopia.

    Science.gov (United States)

    Mitchell, Donald E

    2008-01-01

    To review work on animal models of deprivation amblyopia that points to a special role for binocular visual input in the development of spatial vision and as a component of occlusion (patching) therapy for amblyopia. The studies reviewed employ behavioural methods to measure the effects of various early experiential manipulations on the development of the visual acuity of the two eyes. Short periods of concordant binocular input, if continuous, can offset much longer daily periods of monocular deprivation to allow the development of normal visual acuity in both eyes. It appears that the visual system does not weigh all visual input equally in terms of its ability to impact on the development of vision but instead places greater weight on concordant binocular exposure. Experimental models of patching therapy for amblyopia imposed on animals in which amblyopia had been induced by a prior period of early monocular deprivation, indicate that the benefits of patching therapy may be only temporary and decline rapidly after patching is discontinued. However, when combined with critical amounts of binocular visual input each day, the benefits of patching can be both heightened and made permanent. Taken together with demonstrations of retained binocular connections in the visual cortex of monocularly deprived animals, a strong argument is made for inclusion of specific training of stereoscopic vision for part of the daily periods of binocular exposure that should be incorporated as part of any patching protocol for amblyopia.

  5. [Visual development and amblyopia prophylaxis in pediatric glaucoma].

    Science.gov (United States)

    Steffen, H

    2011-07-01

    In children with congenital glaucoma the functional long-term result is often disappointing even if the intraocular pressure is well controlled. The reason for this discrepancy is attributed to amblyogenic factors responsible for interfering with normal visual development. These amblyogenic factors are corneal edema, irregular astigmatism and non-corrected ametropia as monocular causes. Binocular causes are anisometropia-induced suppression and strabismus. Full ametropic correction and a very early prophylaxis and treatment of amblyopia with a close follow-up are mandatory to reduce amblyogenic visual impairment in children with congenital glaucoma.

  6. Psychophysical research progress of interocular suppression in amblyopic visual system

    Directory of Open Access Journals (Sweden)

    Jing-Jing Li

    2016-03-01

    Full Text Available Some recent animal experiments and psychophysical studies indicate that patients with amblyopia have a structurally intact binocular visual system that is rendered functionally monocular due to suppression, and interocular suppression is a key mechanism in visual deficits experienced by patients with amblyopia. The aim of this review is to provide an overview of recent psychophysical findings that have investigated the important role of interocular suppression in amblyopia, the measurement and modulation of suppression, and new dichoptic treatment intervention that directly target suppression.

  7. Extended Kalman filter-based methods for pose estimation using visual, inertial and magnetic sensors: comparative analysis and performance evaluation.

    Science.gov (United States)

    Ligorio, Gabriele; Sabatini, Angelo Maria

    2013-02-04

    In this paper measurements from a monocular vision system are fused with inertial/magnetic measurements from an Inertial Measurement Unit (IMU) rigidly connected to the camera. Two Extended Kalman filters (EKFs) were developed to estimate the pose of the IMU/camera sensor moving relative to a rigid scene (ego-motion), based on a set of fiducials. The two filters were identical as for the state equation and the measurement equations of the inertial/magnetic sensors. The DLT-based EKF exploited visual estimates of the ego-motion using a variant of the Direct Linear Transformation (DLT) method; the error-driven EKF exploited pseudo-measurements based on the projection errors from measured two-dimensional point features to the corresponding three-dimensional fiducials. The two filters were off-line analyzed in different experimental conditions and compared to a purely IMU-based EKF used for estimating the orientation of the IMU/camera sensor. The DLT-based EKF was more accurate than the error-driven EKF, less robust against loss of visual features, and equivalent in terms of computational complexity. Orientation root mean square errors (RMSEs) of 1° (1.5°), and position RMSEs of 3.5 mm (10 mm) were achieved in our experiments by the DLT-based EKF (error-driven EKF); by contrast, orientation RMSEs of 1.6° were achieved by the purely IMU-based EKF.

  8. Monocular and binocular development in children with albinism, infantile nystagmus syndrome, and normal vision.

    Science.gov (United States)

    Huurneman, Bianca; Boonstra, F Nienke

    2013-12-01

    To compare interocular acuity differences, crowding ratios, and binocular summation ratios in 4- to 8-year-old children with albinism (n = 16), children with infantile nystagmus syndrome (n = 10), and children with normal vision (n = 72). Interocular acuity differences and binocular summation ratios were compared between groups. Crowding ratios were calculated by dividing the single Landolt C decimal acuity with the crowded Landolt C decimal acuity mono- and binocularly. A linear regression analysis was conducted to investigate the contribution of 5 predictors to the monocular and binocular crowding ratio: nystagmus amplitude, nystagmus frequency, strabismus, astigmatism, and anisometropia. Crowding ratios were higher under mono- and binocular viewing conditions for children with infantile nystagmus syndrome than for children with normal vision. Children with albinism showed higher crowding ratios in their poorer eye and under binocular viewing conditions than children with normal vision. Children with albinism and children with infantile nystagmus syndrome showed larger interocular acuity differences than children with normal vision (0.1 logMAR in our clinical groups and 0.0 logMAR in children with normal vision). Binocular summation ratios did not differ between groups. Strabismus and nystagmus amplitude predicted the crowding ratio in the poorer eye (p = 0.015 and p = 0.005, respectively). The crowding ratio in the better eye showed a marginally significant relation with nystagmus frequency and depth of anisometropia (p = 0.082 and p = 0.070, respectively). The binocular crowding ratio was not predicted by any of the variables. Children with albinism and children with infantile nystagmus syndrome show larger interocular acuity differences than children with normal vision. Strabismus and nystagmus amplitude are significant predictors of the crowding ratio in the poorer eye.

  9. Joint optic disc and cup boundary extraction from monocular fundus images.

    Science.gov (United States)

    Chakravarty, Arunava; Sivaswamy, Jayanthi

    2017-08-01

    Accurate segmentation of optic disc and cup from monocular color fundus images plays a significant role in the screening and diagnosis of glaucoma. Though optic cup is characterized by the drop in depth from the disc boundary, most existing methods segment the two structures separately and rely only on color and vessel kink based cues due to the lack of explicit depth information in color fundus images. We propose a novel boundary-based Conditional Random Field formulation that extracts both the optic disc and cup boundaries in a single optimization step. In addition to the color gradients, the proposed method explicitly models the depth which is estimated from the fundus image itself using a coupled, sparse dictionary trained on a set of image-depth map (derived from Optical Coherence Tomography) pairs. The estimated depth achieved a correlation coefficient of 0.80 with respect to the ground truth. The proposed segmentation method outperformed several state-of-the-art methods on five public datasets. The average dice coefficient was in the range of 0.87-0.97 for disc segmentation across three datasets and 0.83 for cup segmentation on the DRISHTI-GS1 test set. The method achieved a good glaucoma classification performance with an average AUC of 0.85 for five fold cross-validation on RIM-ONE v2. We propose a method to jointly segment the optic disc and cup boundaries by modeling the drop in depth between the two structures. Since our method requires a single fundus image per eye during testing it can be employed in the large-scale screening of glaucoma where expensive 3D imaging is unavailable. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Noisy Spiking in Visual Area V2 of Amblyopic Monkeys.

    Science.gov (United States)

    Wang, Ye; Zhang, Bin; Tao, Xiaofeng; Wensveen, Janice M; Smith, Earl L; Chino, Yuzo M

    2017-01-25

    Interocular decorrelation of input signals in developing visual cortex can cause impaired binocular vision and amblyopia. Although increased intrinsic noise is thought to be responsible for a range of perceptual deficits in amblyopic humans, the neural basis for the elevated perceptual noise in amblyopic primates is not known. Here, we tested the idea that perceptual noise is linked to the neuronal spiking noise (variability) resulting from developmental alterations in cortical circuitry. To assess spiking noise, we analyzed the contrast-dependent dynamics of spike counts and spiking irregularity by calculating the square of the coefficient of variation in interspike intervals (CV 2 ) and the trial-to-trial fluctuations in spiking, or mean matched Fano factor (m-FF) in visual area V2 of monkeys reared with chronic monocular defocus. In amblyopic neurons, the contrast versus response functions and the spike count dynamics exhibited significant deviations from comparable data for normal monkeys. The CV 2 was pronounced in amblyopic neurons for high-contrast stimuli and the m-FF was abnormally high in amblyopic neurons for low-contrast gratings. The spike count, CV 2 , and m-FF of spontaneous activity were also elevated in amblyopic neurons. These contrast-dependent spiking irregularities were correlated with the level of binocular suppression in these V2 neurons and with the severity of perceptual loss for individual monkeys. Our results suggest that the developmental alterations in normalization mechanisms resulting from early binocular suppression can explain much of these contrast-dependent spiking abnormalities in V2 neurons and the perceptual performance of our amblyopic monkeys. Amblyopia is a common developmental vision disorder in humans. Despite the extensive animal studies on how amblyopia emerges, we know surprisingly little about the neural basis of amblyopia in humans and nonhuman primates. Although the vision of amblyopic humans is often described as

  11. Vector model for mapping of visual space to subjective 4-D sphere

    International Nuclear Information System (INIS)

    Matuzevicius, Dalius; Vaitkevicius, Henrikas

    2014-01-01

    Here we present a mathematical model of binocular vision that maps a visible physical world to a subjective perception of it. The subjective space is a set of 4-D vectors whose components are outputs of four monocular neurons from each of the two eyes. Monocular neurons have one of the four types of concentric receptive fields with Gabor-like weighting coefficients. Next this vector representation of binocular vision is implemented as a pool of neurons where each of them is selective to the object's particular location in a 3-D visual space. Formally each point of the visual space is being projected onto a 4-D sphere. Proposed model allows determination of subjective distances in depth and direction, provides computational means for determination of Panum's area and explains diplopia and allelotropia

  12. [The 8-year follow-up study for clinical diagnostic potentials of frequency-doubling technology perimetry for perimetrically normal eyes of open-angle glaucoma patients with unilateral visual field loss].

    Science.gov (United States)

    Fan, X; Wu, L L; Xiao, G G; Ma, Z Z; Liu, F

    2018-03-11

    Objective: To analyze potentials of frequency-doubling technology perimetry (FDP) for diagnosing open-angle glaucoma (OAG) in perimetrically normal eyes of OAG patients diagnosed with standard automated perimetry (SAP) and relating factors from abnormalities on FDP to visual field loss on SAP. Methods: A prospective cohort study. Sixty-eight eyes of 68 OAG patients visiting the ophthalmic clinic of Peking University Third Hospital during November 2003 and October 2007 [32 primary open-angle glaucoma patients and 36 normal tension glaucoma patients, 32 males and 36 females, with an average age of (59±13) years] with unilateral field loss detected by SAP (Octopus101 tG2 program) were examined with the FDP N-30 threshold program (Humphrey Instruments) at baseline. Two groups, FDP positive group and FDP negative group, were divided based on the FDP results, and visual field examinations were followed by a series of SAP examinations for the perimetrically normal eyes over 8 years. During the follow-up, the difference of the converting rate of SAP tests between the two groups was analyzed. Differences between "convertors" and "non-convertors" of SAP tests in the FDP positive group, such as the cup-to-disk ratio and glaucomatous optic neuropathy rate, were also compared with the independent-sample t test or Wilcoxon two-sample test for continuous variable data and the χ(2) test or Fisher exact test for classified variable data and rates. Results: Forty-eight perimetrically normal eyes of 48 participants had complete data and a qualifying follow-up. Baseline FDP results were positive in 33 eyes and negative in 15 eyes. Of the eyes with positive FDP results, 22 eyes developed abnormal SAP results after 4.0 to 90.0 months (median 14.5 months) , whereas none of the eyes with negative FDP results developed abnormal SAP results. For perimetrically normal eyes in the FDP positive group, "converters" showed a greater cup-to-disk ratio (0.73±0.09 vs . 0.63±0.14, Wilcoxon two

  13. Size-Dependent Axonal Bouton Dynamics following Visual Deprivation In Vivo

    Directory of Open Access Journals (Sweden)

    Rosanna P. Sammons

    2018-01-01

    Full Text Available Persistent synapses are thought to underpin the storage of sensory experience, yet little is known about their structural plasticity in vivo. We investigated how persistent presynaptic structures respond to the loss of primary sensory input. Using in vivo two-photon (2P imaging, we measured fluctuations in the size of excitatory axonal boutons in L2/3 of adult mouse visual cortex after monocular enucleation. The average size of boutons did not change after deprivation, but the range of bouton sizes was reduced. Large boutons decreased, and small boutons increased. Reduced bouton variance was accompanied by a reduced range of correlated calcium-mediated neural activity in L2/3 of awake animals. Network simulations predicted that size-dependent plasticity may promote conditions of greater bidirectional plasticity. These predictions were supported by electrophysiological measures of short- and long-term plasticity. We propose size-dependent dynamics facilitate cortical reorganization by maximizing the potential for bidirectional plasticity.

  14. Recognition versus Resolution: a Comparison of Visual Acuity Results Using Two Alternative Test Chart Optotype

    OpenAIRE

    Jonathan S. Pointer

    2008-01-01

    Purpose: To quantify the difference between recognition (letter) and resolution (Landolt) visual acuity (VA) in a group of normally sighted subjects. Is it reasonable to assume that the two acuity measures are clinically equivalent? Methods: A pair of 6 m acuity test charts was produced: one comprised letters and the other Landolt broken rings. Construction of both charts conformed to the logMAR design format. Monocular VA was determined for the dominant eye of 300 screened and normally si...

  15. Gain-scheduling control of a monocular vision-based human-following robot

    CSIR Research Space (South Africa)

    Burke, Michael G

    2011-08-01

    Full Text Available , R. and Zisserman, A. (2004). Multiple View Geometry in Computer Vision. Cambridge University Press, 2nd edition. Hutchinson, S., Hager, G., and Corke, P. (1996). A tutorial on visual servo control. IEEE Trans. on Robotics and Automation, 12... environment, in a passive manner, at relatively high speeds and low cost. The control of mobile robots using vision in the feed- back loop falls into the well-studied field of visual servo control. Two primary approaches are used: image-based visual...

  16. Associations between speech understanding and auditory and visual tests of verbal working memory: effects of linguistic complexity, task, age, and hearing loss.

    Science.gov (United States)

    Smith, Sherri L; Pichora-Fuller, M Kathleen

    2015-01-01

    Listeners with hearing loss commonly report having difficulty understanding speech, particularly in noisy environments. Their difficulties could be due to auditory and cognitive processing problems. Performance on speech-in-noise tests has been correlated with reading working memory span (RWMS), a measure often chosen to avoid the effects of hearing loss. If the goal is to assess the cognitive consequences of listeners' auditory processing abilities, however, then listening working memory span (LWMS) could be a more informative measure. Some studies have examined the effects of different degrees and types of masking on working memory, but less is known about the demands placed on working memory depending on the linguistic complexity of the target speech or the task used to measure speech understanding in listeners with hearing loss. Compared to RWMS, LWMS measures using different speech targets and maskers may provide a more ecologically valid approach. To examine the contributions of RWMS and LWMS to speech understanding, we administered two working memory measures (a traditional RWMS measure and a new LWMS measure), and a battery of tests varying in the linguistic complexity of the speech materials, the presence of babble masking, and the task. Participants were a group of younger listeners with normal hearing and two groups of older listeners with hearing loss (n = 24 per group). There was a significant group difference and a wider range in performance on LWMS than on RWMS. There was a significant correlation between both working memory measures only for the oldest listeners with hearing loss. Notably, there were only few significant correlations among the working memory and speech understanding measures. These findings suggest that working memory measures reflect individual differences that are distinct from those tapped by these measures of speech understanding.

  17. Associations between speech understanding and auditory and visual tests of verbal working memory: effects of linguistic complexity, task, age, and hearing loss

    Science.gov (United States)

    Smith, Sherri L.; Pichora-Fuller, M. Kathleen

    2015-01-01

    Listeners with hearing loss commonly report having difficulty understanding speech, particularly in noisy environments. Their difficulties could be due to auditory and cognitive processing problems. Performance on speech-in-noise tests has been correlated with reading working memory span (RWMS), a measure often chosen to avoid the effects of hearing loss. If the goal is to assess the cognitive consequences of listeners’ auditory processing abilities, however, then listening working memory span (LWMS) could be a more informative measure. Some studies have examined the effects of different degrees and types of masking on working memory, but less is known about the demands placed on working memory depending on the linguistic complexity of the target speech or the task used to measure speech understanding in listeners with hearing loss. Compared to RWMS, LWMS measures using different speech targets and maskers may provide a more ecologically valid approach. To examine the contributions of RWMS and LWMS to speech understanding, we administered two working memory measures (a traditional RWMS measure and a new LWMS measure), and a battery of tests varying in the linguistic complexity of the speech materials, the presence of babble masking, and the task. Participants were a group of younger listeners with normal hearing and two groups of older listeners with hearing loss (n = 24 per group). There was a significant group difference and a wider range in performance on LWMS than on RWMS. There was a significant correlation between both working memory measures only for the oldest listeners with hearing loss. Notably, there were only few significant correlations among the working memory and speech understanding measures. These findings suggest that working memory measures reflect individual differences that are distinct from those tapped by these measures of speech understanding. PMID:26441769

  18. A Monocular Vision Measurement System of Three-Degree-of-Freedom Air-Bearing Test-Bed Based on FCCSP

    Science.gov (United States)

    Gao, Zhanyu; Gu, Yingying; Lv, Yaoyu; Xu, Zhenbang; Wu, Qingwen

    2018-06-01

    A monocular vision-based pose measurement system is provided for real-time measurement of a three-degree-of-freedom (3-DOF) air-bearing test-bed. Firstly, a circular plane cooperative target is designed. An image of a target fixed on the test-bed is then acquired. Blob analysis-based image processing is used to detect the object circles on the target. A fast algorithm (FCCSP) based on pixel statistics is proposed to extract the centers of object circles. Finally, pose measurements can be obtained when combined with the centers and the coordinate transformation relation. Experiments show that the proposed method is fast, accurate, and robust enough to satisfy the requirement of the pose measurement.

  19. Measuring Algorithm for the Distance to a Preceding Vehicle on Curve Road Using On-Board Monocular Camera

    Science.gov (United States)

    Yu, Guizhen; Zhou, Bin; Wang, Yunpeng; Wun, Xinkai; Wang, Pengcheng

    2015-12-01

    Due to more severe challenges of traffic safety problems, the Advanced Driver Assistance Systems (ADAS) has received widespread attention. Measuring the distance to a preceding vehicle is important for ADAS. However, the existing algorithm focuses more on straight road sections than on curve measurements. In this paper, we present a novel measuring algorithm for the distance to a preceding vehicle on a curve road using on-board monocular camera. Firstly, the characteristics of driving on the curve road is analyzed and the recognition of the preceding vehicle road area is proposed. Then, the vehicle detection and distance measuring algorithms are investigated. We have verified these algorithms on real road driving. The experimental results show that this method proposed in the paper can detect the preceding vehicle on curve roads and accurately calculate the longitudinal distance and horizontal distance to the preceding vehicle.

  20. Self-supervised learning as an enabling technology for future space exploration robots: ISS experiments on monocular distance learning

    Science.gov (United States)

    van Hecke, Kevin; de Croon, Guido C. H. E.; Hennes, Daniel; Setterfield, Timothy P.; Saenz-Otero, Alvar; Izzo, Dario

    2017-11-01

    Although machine learning holds an enormous promise for autonomous space robots, it is currently not employed because of the inherent uncertain outcome of learning processes. In this article we investigate a learning mechanism, Self-Supervised Learning (SSL), which is very reliable and hence an important candidate for real-world deployment even on safety-critical systems such as space robots. To demonstrate this reliability, we introduce a novel SSL setup that allows a stereo vision equipped robot to cope with the failure of one of its cameras. The setup learns to estimate average depth using a monocular image, by using the stereo vision depths from the past as trusted ground truth. We present preliminary results from an experiment on the International Space Station (ISS) performed with the MIT/NASA SPHERES VERTIGO satellite. The presented experiments were performed on October 8th, 2015 on board the ISS. The main goals were (1) data gathering, and (2) navigation based on stereo vision. First the astronaut Kimiya Yui moved the satellite around the Japanese Experiment Module to gather stereo vision data for learning. Subsequently, the satellite freely explored the space in the module based on its (trusted) stereo vision system and a pre-programmed exploration behavior, while simultaneously performing the self-supervised learning of monocular depth estimation on board. The two main goals were successfully achieved, representing the first online learning robotic experiments in space. These results lay the groundwork for a follow-up experiment in which the satellite will use the learned single-camera depth estimation for autonomous exploration in the ISS, and are an advancement towards future space robots that continuously improve their navigation capabilities over time, even in harsh and completely unknown space environments.

  1. Visual Structure and Function in Collision Sport Athletes.

    Science.gov (United States)

    Leong, Danielle; Morettin, Christina; Messner, Leonard V; Steinmetz, Robert J; Pang, Yi; Galetta, Steven L; Balcer, Laura J

    2017-09-06

    Vision-based measures have been shown to be useful markers in multiple sclerosis (MS), Alzheimer and Parkinson disease. Therefore, these testing paradigms may have applications to populations explaining repetitive head trauma that has been associated with long-term neurodegenerative sequelae. We investigated retinal structure and visual function in professional collision sport athletes compared to age- and race-matched control participants. In this cross-sectional study, participants underwent spectral-domain optical coherence tomography (OCT) measurements of peripapillary retinal nerve fiber layer (RNFL) and macular ganglion cell complex (GCC = ganglion cell + inner plexiform layers) thickness. High-contrast visual acuity (100% level), low-contrast letter acuity (LCLA) (1.25% and 2.5% levels), and King-Devick Test of rapid number naming performance were administered. Vision-specific quality of life (QOL) measures were assessed. Among 46 collision sport athletes (boxing, n = 14; football, n = 29; ice hockey, n = 3) and 104 control participants, average RNFL thickness was a significant predictor of athlete vs control status with athletes demonstrating 4.8-μm of thinning compared to controls (P = 0.01, generalized estimating equation [GEE] models accounting for age and within-subject, intereye correlations). Athlete vs control status was not a predictor of RNFL thickness for the subgroup of football players in this cohort (P = 0.60). Binocular (P = 0.001) and monocular (P = 0.02) LCLA at 2.5% contrast and vision-specific QOL (P = 0.04) were significant predictors of athlete vs control status (GEE models accounting for age and within-subject, intereye correlations). Rapid number naming performance times were not significantly different between the control and athlete groups. This study showed that retinal axonal and neuronal loss is present among collision sport athletes, with most notable differences seen in boxers. These findings are accompanied by reductions in

  2. Head Worn Display System for Equivalent Visual Operations

    Science.gov (United States)

    Cupero, Frank; Valimont, Brian; Wise, John; Best. Carl; DeMers, Bob

    2009-01-01

    Head-Worn Displays or so-called, near-to-eye displays have potentially significant advantages in terms of cost, overcoming cockpit space constraints, and for the display of spatially-integrated information. However, many technical issues need to be overcome before these technologies can be successfully introduced into commercial aircraft cockpits. The results of three activities are reported. First, the near-to-eye display design, technological, and human factors issues are described and a literature review is presented. Second, the results of a fixed-base piloted simulation, investigating the impact of near to eye displays on both operational and visual performance is reported. Straight-in approaches were flown in simulated visual and instrument conditions while using either a biocular or a monocular display placed on either the dominant or non-dominant eye. The pilot's flight performance, visual acuity, and ability to detect unsafe conditions on the runway were tested. The data generally supports a monocular design with minimal impact due to eye dominance. Finally, a method for head tracker system latency measurement is developed and used to compare two different devices.

  3. Cortical Visual Impairment

    Science.gov (United States)

    ... resolves by one year of life. Is “cortical blindness” the same thing as CVI? Cortical blindness is ... What visual characteristics are associated with CVI? • Distinct color preferences • Variable level of vision loss, often demonstrating ...

  4. Nogo Receptor 1 Confines a Disinhibitory Microcircuit to the Critical Period in Visual Cortex.

    Science.gov (United States)

    Stephany, Céleste-Élise; Ikrar, Taruna; Nguyen, Collins; Xu, Xiangmin; McGee, Aaron W

    2016-10-26

    A characteristic of the developing mammalian visual system is a brief interval of plasticity, termed the "critical period," when the circuitry of primary visual cortex is most sensitive to perturbation of visual experience. Depriving one eye of vision (monocular deprivation [MD]) during the critical period alters ocular dominance (OD) by shifting the responsiveness of neurons in visual cortex to favor the nondeprived eye. A disinhibitory microcircuit involving parvalbumin-expressing (PV) interneurons initiates this OD plasticity. The gene encoding the neuronal nogo-66-receptor 1 (ngr1/rtn4r) is required to close the critical period. Here we combined mouse genetics, electrophysiology, and circuit mapping with laser-scanning photostimulation to investigate whether disinhibition is confined to the critical period by ngr1 We demonstrate that ngr1 mutant mice retain plasticity characteristic of the critical period as adults, and that ngr1 operates within PV interneurons to restrict the loss of intracortical excitatory synaptic input following MD in adult mice, and this disinhibition induces a "lower PV network configuration" in both critical-period wild-type mice and adult ngr1 -/- mice. We propose that ngr1 limits disinhibition to close the critical period for OD plasticity and that a decrease in PV expression levels reports the diminished recent cumulative activity of these interneurons. Life experience refines brain circuits throughout development during specified critical periods. Abnormal experience during these critical periods can yield enduring maladaptive changes in neural circuits that impair brain function. In the developing visual system, visual deprivation early in life can result in amblyopia (lazy-eye), a prevalent childhood disorder comprising permanent deficits in spatial vision. Here we identify that the nogo-66 receptor 1 gene restricts an early and essential step in OD plasticity to the critical period. These findings link the emerging circuit

  5. Significant correlations between optic nerve head microcirculation and visual field defects and nerve fiber layer loss in glaucoma patients with myopic glaucomatous disk

    Directory of Open Access Journals (Sweden)

    Yokoyama Y

    2011-12-01

    Full Text Available Yu Yokoyama, Naoko Aizawa, Naoki Chiba, Kazuko Omodaka, Masahiko Nakamura, Takaaki Otomo, Shunji Yokokura, Nobuo Fuse, Toru NakazawaDepartment of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, JapanBackground: Eyes with glaucoma are characterized by optic neuropathy with visual field defects in the areas corresponding to the optic disk damage. The exact cause for the glaucomatous optic neuropathy has not been determined. Myopia has been shown to be a risk factor for glaucoma. The purpose of this study was to determine whether a significant correlation existed between the microcirculation of the optic disk and the visual field defects and the retinal nerve fiber layer thickness (RNFLT in glaucoma patients with myopic optic disks.Methods: Sixty eyes of 60 patients with myopic disks were studied; 36 eyes with glaucoma (men:women = 19:17 and 24 eyes with no ocular diseases (men:women = 14:10. The mean deviation (MD determined by the Humphrey field analyzer, and the peripapillary RNFLT determined by the Stratus-OCT were compared between the two groups. The ocular circulation was determined by laser speckle flowgraphy (LSFG, and the mean blur rate (MBR was compared between the two groups. The correlations between the RNFLT and MBR of the corresponding areas of the optic disk and between MD and MBR of the optic disk in the glaucoma group were determined by simple regression analyses.Results: The average MBR for the entire optic disk was significantly lower in the glaucoma group than that in the control group. The differences of the MBR for the tissue in the superior, inferior, and temporal quadrants of the optic disk between the two groups were significant. The MBR for the entire optic disk was significantly correlated with the MD (r = 0.58, P = 0.0002 and the average RNFLT (r = 0.53, P = 0.0008. The tissue MBR of the optic disk was significantly correlated with the RNFLT in the superior, inferior, and temporal quadrants

  6. Hearing loss

    Science.gov (United States)

    Decreased hearing; Deafness; Loss of hearing; Conductive hearing loss; Sensorineural hearing loss; Presbycusis ... Symptoms of hearing loss may include: Certain sounds seeming too loud Difficulty following conversations when two or more people are talking ...

  7. Delayed visual maturation in infants: a disorder of figure-ground separation?

    Science.gov (United States)

    Harris, C M; Kriss, A; Shawkat, F; Taylor, D; Russell-Eggitt, I

    1996-01-01

    Delayed visual maturation (DVM) is characterised by visual unresponsiveness in early infancy, which subsequently improves spontaneously to normal levels. We studied the optokinetic response and recorded pattern reversal VEPs in six infants with DVM (aged 2-4 months) when they were at the stage of complete visual unresponsiveness. Although no saccades or visual tracking with the eyes or head could be elicited to visual objects, a normal full-field rapid buildup OKN response occurred when viewing biocularly or during monocular stimulation in the temporo-nasal direction of the viewing eye. Almost no monocular OKN could be elicited in the naso-temporal direction, which was significantly poorer than normal age-matched infants. No OKN quick phases were missed, and there were no other signs of "ocular motor apraxia." VEPs were normal in amplitude and latency for age. It appears, therefore, that infants with DVM are delayed in orienting to local regions of the visual field, but can respond to full-field motion. The presence of normal OKN quick-phases and slow-phases suggests normal brain stem function, and the presence of normal pattern VEPs suggests a normal retino-geniculo-striate pathway. These oculomotor and electrophysiological findings suggest delayed development of extra-striate cortical structures, possibly involving either an abnormality in figure-ground segregation or in attentional pathways.

  8. Position estimation and driving of an autonomous vehicle by monocular vision

    Science.gov (United States)

    Hanan, Jay C.; Kayathi, Pavan; Hughlett, Casey L.

    2007-04-01

    Automatic adaptive tracking in real-time for target recognition provided autonomous control of a scale model electric truck. The two-wheel drive truck was modified as an autonomous rover test-bed for vision based guidance and navigation. Methods were implemented to monitor tracking error and ensure a safe, accurate arrival at the intended science target. Some methods are situation independent relying only on the confidence error of the target recognition algorithm. Other methods take advantage of the scenario of combined motion and tracking to filter out anomalies. In either case, only a single calibrated camera was needed for position estimation. Results from real-time autonomous driving tests on the JPL simulated Mars yard are presented. Recognition error was often situation dependent. For the rover case, the background was in motion and may be characterized to provide visual cues on rover travel such as rate, pitch, roll, and distance to objects of interest or hazards. Objects in the scene may be used as landmarks, or waypoints, for such estimations. As objects are approached, their scale increases and their orientation may change. In addition, particularly on rough terrain, these orientation and scale changes may be unpredictable. Feature extraction combined with the neural network algorithm was successful in providing visual odometry in the simulated Mars environment.

  9. Pregnancy Loss

    Science.gov (United States)

    ... To receive Pregnancy email updates Enter email Submit Pregnancy loss Pregnancy loss is a harsh reality faced ... have successful pregnancies. Expand all | Collapse all Why pregnancy loss happens As many as 10 to 15 ...

  10. [Progressive visual agnosia].

    Science.gov (United States)

    Sugimoto, Azusa; Futamura, Akinori; Kawamura, Mitsuru

    2011-10-01

    Progressive visual agnosia was discovered in the 20th century following the discovery of classical non-progressive visual agnosia. In contrast to the classical type, which is caused by cerebral vascular disease or traumatic injury, progressive visual agnosia is a symptom of neurological degeneration. The condition of progressive visual loss, including visual agnosia, and posterior cerebral atrophy was named posterior cortical atrophy (PCA) by Benson et al. (1988). Progressive visual agnosia is also observed in semantic dementia (SD) and other degenerative diseases, but there is a difference in the subtype of visual agnosia associated with these diseases. Lissauer (1890) classified visual agnosia into apperceptive and associative types, and it in most cases, PCA is associated with the apperceptive type. However, SD patients exhibit symptoms of associative visual agnosia before changing to those of semantic memory disorder. Insights into progressive visual agnosia have helped us understand the visual system and discover how we "perceive" the outer world neuronally, with regard to consciousness. Although PCA is a type of atypical dementia, its diagnosis is important to enable patients to live better lives with appropriate functional support.

  11. Combined lateral rectus augmented transposition and inferior rectus recession for monocular elevation deficiency.

    Science.gov (United States)

    Jayakumar, Manjula; Kumar, Dhivya Ashok; Agarwal, Amar

    2018-04-01

    We report the case of a 21-year-old woman who presented with a drooping right upper eyelid and smaller-appearing right eye, evident since birth. Her visual acuity was 20/30 in the right eye and 20/20 in the left eye. In primary gaze she had a hypotropia of 25 Δ , with a marked elevation limitation and associated true upper lid ptosis of 3 mm. Under local anesthesia, the lateral rectus muscle was transposed to the superior rectus muscle and was augmented by a nonabsorbable suture attaching the superior rectus muscle and lateral rectus muscle 8 mm posterior to the insertion, accompanied by an inferior rectus recession. One year after surgery she was orthophoric in primary position and showed improvement in elevation. The surgical procedure can be performed at the same time as the inferior rectus recession and reduces the risk of anterior segment ischemia. Copyright © 2018 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.

  12. Control monocular 3D dinámico basado en imagen

    Directory of Open Access Journals (Sweden)

    Luis Hernández Santana

    2011-09-01

    Full Text Available Normal 0 21 false false false MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabla normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} En este trabajo se presenta un sistema de control servovisual para regulación de posición de un robot manipulador con cámara en mano que se mueve en el espacio cartesiano 3D. El objetivo es control el robot de tal forma que la imagen de una esfera en movimiento se mantenga en el centro del plano imagen con radio constante. Se propone una estrategia de control con dos lazos en cascada, el lazo interno resuelve el control articular y el lazo externo implementa el control con realimentación visual. El robot y el sistema de visión son modelados para pequeñas variaciones alrededor del punto de operación para control de posición. Para estas condiciones se muestran la estabilidad del sistema y la respuesta en estado estable para trayectorias del objeto. Para ilustrar las prestaciones del sistema, se presentan los resultados experimentales para un manipulador ASEAIRB6.

  13. 6DoF object pose measurement by a monocular manifold-based pattern recognition technique

    International Nuclear Information System (INIS)

    Kouskouridas, Rigas; Charalampous, Konstantinos; Gasteratos, Antonios

    2012-01-01

    In this paper, a novel solution to the compound problem of object recognition and 3D pose estimation is presented. An accurate measurement of the geometrical configuration of a recognized target, relative to a known coordinate system, is of fundamental importance and constitutes a prerequisite for several applications such as robot grasping or obstacle avoidance. The proposed method lays its foundations on the following assumptions: (a) the same object captured under varying viewpoints and perspectives represents data that could be projected onto a well-established and highly distinguishable subspace; (b) totally different objects observed under the same viewpoints and perspectives share identical 3D pose that can be sufficiently modeled to produce a generalized model. Toward this end, we propose an advanced architecture that allows both recognizing patterns and providing efficient solution for 6DoF pose estimation. We employ a manifold modeling architecture that is grounded on a part-based representation of an object, which in turn, is accomplished via an unsupervised clustering of the extracted visual cues. The main contributions of the proposed framework are: (a) the proposed part-based architecture requires minimum supervision, compared to other contemporary solutions, whilst extracting new features encapsulating both appearance and geometrical attributes of the objects; (b) contrary to related projects that extract high-dimensional data, thus, increasing the complexity of the system, the proposed manifold modeling approach makes use of low dimensionality input vectors; (c) the formulation of a novel input–output space mapping that outperforms the existing dimensionality reduction schemes. Experimental results justify our theoretical claims and demonstrate the superiority of our method comparing to other related contemporary projects. (paper)

  14. Analysis the macular ganglion cell complex thickness in monocular strabismic amblyopia patients by Fourier-domain OCT

    Directory of Open Access Journals (Sweden)

    Hong-Wei Deng

    2014-11-01

    Full Text Available AIM: To detect the macular ganglion cell complex thickness in monocular strabismus amblyopia patients, in order to explore the relationship between the degree of amblyopia and retinal ganglion cell complex thickness, and found out whether there is abnormal macular ganglion cell structure in strabismic amblyopia. METHODS: Using a fourier-domain optical coherence tomography(FD-OCTinstrument iVue®(Optovue Inc, Fremont, CA, Macular ganglion cell complex(mGCCthickness was measured and statistical the relation rate with the best vision acuity correction was compared Gman among 26 patients(52 eyesincluded in this study. RESULTS: The mean thickness of the mGCC in macular was investigated into three parts: centrial, inner circle(3mmand outer circle(6mm. The mean thicknesses of mGCC in central, inner and outer circle was 50.74±21.51μm, 101.4±8.51μm, 114.2±9.455μm in the strabismic amblyopia eyes(SAE, and 43.79±11.92μm,92.47±25.01μm, 113.3±12.88μm in the contralateral sound eyes(CSErespectively. There was no statistically significant difference among the eyes(P>0.05. But the best corrected vision acuity had a good correlation rate between mGcc thicknesses, which was better relative for the lower part than the upper part.CONCLUSION:There is a relationship between the amblyopia vision acuity and the mGCC thickness. Although there has not statistically significant difference of the mGCC thickness compared with the SAE and CSE. To measure the macular center mGCC thickness in clinic may understand the degree of amblyopia.

  15. Atypical visual loss in giant cell arteritis

    DEFF Research Database (Denmark)

    Thystrup, Jan Deichmann; Knudsen, G M; Mogensen, A M

    1994-01-01

    Three patients with atypical ocular involvement due to histologically verified giant cell arteritis are reported. Prior to diagnosis, the first patient had periods of amaurosis fugax. He presented with normal vision. In spite of high-dose systemic corticosteroid therapy, he became blind in the te......Three patients with atypical ocular involvement due to histologically verified giant cell arteritis are reported. Prior to diagnosis, the first patient had periods of amaurosis fugax. He presented with normal vision. In spite of high-dose systemic corticosteroid therapy, he became blind...

  16. Sparse coding can predict primary visual cortex receptive field changes induced by abnormal visual input.

    Science.gov (United States)

    Hunt, Jonathan J; Dayan, Peter; Goodhill, Geoffrey J

    2013-01-01

    Receptive fields acquired through unsupervised learning of sparse representations of natural scenes have similar properties to primary visual cortex (V1) simple cell receptive fields. However, what drives in vivo development of receptive fields remains controversial. The strongest evidence for the importance of sensory experience in visual development comes from receptive field changes in animals reared with abnormal visual input. However, most sparse coding accounts have considered only normal visual input and the development of monocular receptive fields. Here, we applied three sparse coding models to binocular receptive field development across six abnormal rearing conditions. In every condition, the changes in receptive field properties previously observed experimentally were matched to a similar and highly faithful degree by all the models, suggesting that early sensory development can indeed be understood in terms of an impetus towards sparsity. As previously predicted in the literature, we found that asymmetries in inter-ocular correlation across orientations lead to orientation-specific binocular receptive fields. Finally we used our models to design a novel stimulus that, if present during rearing, is predicted by the sparsity principle to lead robustly to radically abnormal receptive fields.

  17. Audio-visual interactions uniquely contribute to resolution of visual conflict in people possessing absolute pitch.

    Directory of Open Access Journals (Sweden)

    Sujin Kim

    Full Text Available Individuals possessing absolute pitch (AP are able to identify a given musical tone or to reproduce it without reference to another tone. The present study sought to learn whether this exceptional auditory ability impacts visual perception under stimulus conditions that provoke visual competition in the form of binocular rivalry. Nineteen adult participants with 3-19 years of musical training were divided into two groups according to their performance on a task involving identification of the specific note associated with hearing a given musical pitch. During test trials lasting just over half a minute, participants dichoptically viewed a scrolling musical score presented to one eye and a drifting sinusoidal grating presented to the other eye; throughout the trial they pressed buttons to track the alternations in visual awareness produced by these dissimilar monocular stimuli. On "pitch-congruent" trials, participants heard an auditory melody that was congruent in pitch with the visual score, on "pitch-incongruent" trials they heard a transposed auditory melody that was congruent with the score in melody but not in pitch, and on "melody-incongruent" trials they heard an auditory melody completely different from the visual score. For both groups, the visual musical scores predominated over the gratings when the auditory melody was congruent compared to when it was incongruent. Moreover, the AP participants experienced greater predominance of the visual score when it was accompanied by the pitch-congruent melody compared to the same melody transposed in pitch; for non-AP musicians, pitch-congruent and pitch-incongruent trials yielded equivalent predominance. Analysis of individual durations of dominance revealed differential effects on dominance and suppression durations for AP and non-AP participants. These results reveal that AP is accompanied by a robust form of bisensory interaction between tonal frequencies and musical notation that boosts

  18. A new binocular approach to the treatment of amblyopia in adults well beyond the critical period of visual development.

    Science.gov (United States)

    Hess, R F; Mansouri, B; Thompson, B

    2010-01-01

    The present treatments for amblyopia are predominantly monocular aiming to improve the vision in the amblyopic eye through either patching of the fellow fixing eye or visual training of the amblyopic eye. This approach is problematic, not least of which because it rarely results in establishment of binocular function. Recently it has shown that amblyopes possess binocular cortical mechanisms for both threshold and suprathreshold stimuli. We outline a novel procedure for measuring the extent to which the fixing eye suppresses the fellow amblyopic eye, rendering what is a structurally binocular system, functionally monocular. Here we show that prolonged periods of viewing (under the artificial conditions of stimuli of different contrast in each eye) during which information from the two eyes is combined leads to a strengthening of binocular vision in strabismic amblyopes and eventual combination of binocular information under natural viewing conditions (stimuli of the same contrast in each eye). Concomitant improvement in monocular acuity of the amblyopic eye occurs with this reduction in suppression and strengthening of binocular fusion. Furthermore, in a majority of patients tested, stereoscopic function is established. This provides the basis for a new treatment of amblyopia, one that is purely binocular and aimed at reducing suppression as a first step.

  19. Perfil morfofuncional de pacientes com retinopatia diabética sem baixa acuidade visual severa em hospital público de referência em diabetes no Brasil Morpho-functional profile of patients with diabetic retinopathy without severe loss of visual acuity in a public hospital of reference in diabetes in Brazil

    Directory of Open Access Journals (Sweden)

    Alípio de Sousa Neto

    2010-02-01

    que o grupo da endocrinologia.OBJECTIVE: To demonstrate the morpho-functional profile of the evaluation of patients with diabetic retinopathy without severe loss of visual acuity in a public hospital of reference in endocrinology, determining in this sample, the relation between the time of diabetes, age and visual acuity with the retinal thickness measured by the optical Coherence tomography (OCT and fundus picture (FP. METHODS: Prospective, linear study was carried through, in transversal cut of 61 consecutive patients with diabetic retinopathy registered in the HRT, and refered from the services of ophthalmology and endocrinology. Patients had been submitted to a complete ophthalmic evaluation including clinical history, visual acuity with correction and pin hole. The patients who had presented diabetic retinopathy, with transparent media, without previous surgery, nor previous Laser photocoagulation and with visual acuity better than 20/100 at Snelen scale, had been included in the study. After the elimination of the patients who had not obeyed the inclusion/exclusion criteria 109 eyes of 55 patients then had been submitted the OCT and FP for evaluation of the presence or absence of edema by the FP and of the quantitative evaluation (measured of the retinal thickness of the 9 regions of the pelo Early Tratment Diabetic Retinophaty Study (ETDRS, and of the qualitative evaluation (presence or absence of retinal edema for the central slit, number 1. RESULTS: The average time of diabetes was of 12 years, varying of 23 to 86 years old. 51% were female, and 49% male. The OCT demonstrated discrete reduction of the retinal thickness with elapsing of the age. The patients of the ophthalmology had greaters values of retinal thickness of what of the group of the endocrinology. The evaluation of the visual acuity improved with pin hole in 47% (51/109. The endocrinology group were 45% (23/50 of the eyes and the ophthalmology group were 55% (28/59. Only 22% (24/109 of the eyes

  20. Visual abilities in two raptors with different ecology.

    Science.gov (United States)

    Potier, Simon; Bonadonna, Francesco; Kelber, Almut; Martin, Graham R; Isard, Pierre-François; Dulaurent, Thomas; Duriez, Olivier

    2016-09-01

    Differences in visual capabilities are known to reflect differences in foraging behaviour even among closely related species. Among birds, the foraging of diurnal raptors is assumed to be guided mainly by vision but their foraging tactics include both scavenging upon immobile prey and the aerial pursuit of highly mobile prey. We studied how visual capabilities differ between two diurnal raptor species of similar size: Harris's hawks, Parabuteo unicinctus, which take mobile prey, and black kites, Milvus migrans, which are primarily carrion eaters. We measured visual acuity, foveal characteristics and visual fields in both species. Visual acuity was determined using a behavioural training technique; foveal characteristics were determined using ultra-high resolution spectral-domain optical coherence tomography (OCT); and visual field parameters were determined using an ophthalmoscopic reflex technique. We found that these two raptors differ in their visual capacities. Harris's hawks have a visual acuity slightly higher than that of black kites. Among the five Harris's hawks tested, individuals with higher estimated visual acuity made more horizontal head movements before making a decision. This may reflect an increase in the use of monocular vision. Harris's hawks have two foveas (one central and one temporal), while black kites have only one central fovea and a temporal area. Black kites have a wider visual field than Harris's hawks. This may facilitate the detection of conspecifics when they are scavenging. These differences in the visual capabilities of these two raptors may reflect differences in the perceptual demands of their foraging behaviours. © 2016. Published by The Company of Biologists Ltd.

  1. Experiencing Loss

    DEFF Research Database (Denmark)

    Kristiansen, Maria; Younis, Tarek; Hassani, Amani

    2015-01-01

    In this article, we explore how Islam, minority status and refugee experiencesintersect in shaping meaning-making processes following bereavement. We do this througha phenomenological analysis of a biographical account of personal loss told by Aisha, a Muslim Palestinian refugee living in Denmark......, who narrates her experience of losing herhusband to lung cancer. By drawing on a religious framework, Aisha creates meaning fromher loss, which enables her to incorporate this loss into her life history and sustain agency.Her narrative invites wider audiences to witness her tale of overcoming loss...

  2. Percepção monocular da profundidade ou relevo na ilusão da máscara côncava na esquizofrenia

    Directory of Open Access Journals (Sweden)

    Arthur Alves

    2014-03-01

    Full Text Available Este trabalho foi desenvolvido com o propósito de investigar a percepção monocular da profundidade ou relevo da máscara côncava por 29 indivíduos saudáveis, sete indivíduos com esquizofrenia sob uso de antipsicótico por um período inferior ou igual a quatro semanas e 29 sob uso de antipsicótico por um período superior a quatro semanas. Os três grupos classificaram o reverso de uma máscara policromada em duas situações de iluminação, por cima e por baixo. Os resultados indicaram que a maioria dos indivíduos com esquizofrenia inverteu a profundidade da máscara côncava na condição de observação monocular e perceberam-na como convexa, sendo, portanto, suscetíveis à ilusão da máscara côncava. Os indivíduos com esquizofrenia sob uso de medicação antipsicótica pelo período superior a quatro semanas estimaram a convexidade da máscara côncava iluminada por cima em menor comprimento comparados aos indivíduos saudáveis.

  3. Developmental and visual input-dependent regulation of the CB1 cannabinoid receptor in the mouse visual cortex.

    Directory of Open Access Journals (Sweden)

    Taisuke Yoneda

    Full Text Available The mammalian visual system exhibits significant experience-induced plasticity in the early postnatal period. While physiological studies have revealed the contribution of the CB1 cannabinoid receptor (CB1 to developmental plasticity in the primary visual cortex (V1, it remains unknown whether the expression and localization of CB1 is regulated during development or by visual experience. To explore a possible role of the endocannabinoid system in visual cortical plasticity, we examined the expression of CB1 in the visual cortex of mice. We found intense CB1 immunoreactivity in layers II/III and VI. CB1 mainly localized at vesicular GABA transporter-positive inhibitory nerve terminals. The amount of CB1 protein increased throughout development, and the specific laminar pattern of CB1 appeared at P20 and remained until adulthood. Dark rearing from birth to P30 decreased the amount of CB1 protein in V1 and altered the synaptic localization of CB1 in the deep layer. Dark rearing until P50, however, did not influence the expression of CB1. Brief monocular deprivation for 2 days upregulated the localization of CB1 at inhibitory nerve terminals in the deep layer. Taken together, the expression and the localization of CB1 are developmentally regulated, and both parameters are influenced by visual experience.

  4. Math for visualization, visualizing math

    NARCIS (Netherlands)

    Wijk, van J.J.; Hart, G.; Sarhangi, R.

    2013-01-01

    I present an overview of our work in visualization, and reflect on the role of mathematics therein. First, mathematics can be used as a tool to produce visualizations, which is illustrated with examples from information visualization, flow visualization, and cartography. Second, mathematics itself

  5. Visual art and visual perception

    NARCIS (Netherlands)

    Koenderink, Jan J.

    2015-01-01

    Visual art and visual perception ‘Visual art’ has become a minor cul-de-sac orthogonal to THE ART of the museum directors and billionaire collectors. THE ART is conceptual, instead of visual. Among its cherished items are the tins of artist’s shit (Piero Manzoni, 1961, Merda d’Artista) “worth their

  6. Memory loss

    Science.gov (United States)

    ... barbiturates or ( hypnotics ) ECT (electroconvulsive therapy) (most often short-term memory loss) Epilepsy that is not well controlled Illness that ... appointment. Medical history questions may include: Type of memory loss, such as short-term or long-term Time pattern, such as how ...

  7. Flow visualization

    CERN Document Server

    Merzkirch, Wolfgang

    1974-01-01

    Flow Visualization describes the most widely used methods for visualizing flows. Flow visualization evaluates certain properties of a flow field directly accessible to visual perception. Organized into five chapters, this book first presents the methods that create a visible flow pattern that could be investigated by visual inspection, such as simple dye and density-sensitive visualization methods. It then deals with the application of electron beams and streaming birefringence. Optical methods for compressible flows, hydraulic analogy, and high-speed photography are discussed in other cha

  8. Multifocal visual evoked potentials for quantifying optic nerve dysfunction in patients with optic disc drusen

    DEFF Research Database (Denmark)

    Malmqvist, Lasse; de Santiago, Luis; Boquete, Luciano

    2017-01-01

    and 22 control subjects were examined. Mean amplitude, mean inner ring (IR) amplitude (0.87-5.67° of visual field) and mean outer ring amplitude (5.68-24° of visual field) were calculated using signal-to-noise ratio (SNR) and peak-to-peak analysis. Monocular latency was calculated using second peak......PURPOSE: To explore the applicability of multifocal visual evoked potentials (mfVEPs) for research and clinical diagnosis in patients with optic disc drusen (ODD). This is the first assessment of mfVEP amplitude in patients with ODD. METHODS: MfVEP amplitude and latency from 33 patients with ODD......, full eye and IR. In the control group, SNR intersubject variability was 17.6% and second peak latency intersubject variability was 2.8%. CONCLUSION: Decreased mfVEP amplitude in patients with ODD suggests a direct mechanical compression of the optic nerve axons. Our results suggest that mfVEP amplitude...

  9. Visual field

    Science.gov (United States)

    ... your visual field. How the Test is Performed Confrontation visual field exam. This is a quick and ... to achieve this important distinction for online health information and services. Learn more about A.D.A. ...

  10. Localization from Visual Landmarks on a Free-Flying Robot

    Science.gov (United States)

    Coltin, Brian; Fusco, Jesse; Moratto, Zack; Alexandrov, Oleg; Nakamura, Robert

    2016-01-01

    We present the localization approach for Astrobee, a new free-flying robot designed to navigate autonomously on the International Space Station (ISS). Astrobee will accommodate a variety of payloads and enable guest scientists to run experiments in zero-g, as well as assist astronauts and ground controllers. Astrobee will replace the SPHERES robots which currently operate on the ISS, whose use of fixed ultrasonic beacons for localization limits them to work in a 2 meter cube. Astrobee localizes with monocular vision and an IMU, without any environmental modifications. Visual features detected on a pre-built map, optical flow information, and IMU readings are all integrated into an extended Kalman filter (EKF) to estimate the robot pose. We introduce several modifications to the filter to make it more robust to noise, and extensively evaluate the localization algorithm.

  11. VISIDEP™: visual image depth enhancement by parallax induction

    Science.gov (United States)

    Jones, Edwin R.; McLaurin, A. P.; Cathey, LeConte

    1984-05-01

    The usual descriptions of depth perception have traditionally required the simultaneous presentation of disparate views presented to separate eyes with the concomitant demand that the resulting binocular parallax be horizontally aligned. Our work suggests that the visual input information is compared in a short-term memory buffer which permits the brain to compute depth as it is normally perceived. However, the mechanism utilized is also capable of receiving and processing the stereographic information even when it is received monocularly or when identical inputs are simultaneously fed to both eyes. We have also found that the restriction to horizontally displaced images is not a necessary requirement and that improvement in image acceptability is achieved by the use of vertical parallax. Use of these ideas permit the presentation of three-dimensional scenes on flat screens in full color without the encumbrance of glasses or other viewing aids.

  12. Weight Loss

    Science.gov (United States)

    ... Rights Employment Discrimination Health Care Professionals Law Enforcement Driver's License For Lawyers Food & Fitness Home Food MyFoodAdvisor ... Fit Types of Activity Weight Loss Assess Your Lifestyle Getting Started Food Choices In My Community Home ...

  13. History of falling and visual ability among independently living elderly in Sweden.

    Science.gov (United States)

    Källstrand-Eriksson, Jeanette; Hildingh, Cathrine; Bengtsson, Boel

    2016-01-01

    The aim of this study was to assess the performance-based visual ability among independently living elderly subjects and to investigate whether there was any association between visual ability and falls. A total of 298 randomly selected subjects aged 70-85 years were invited for an examination including monocular and binocular visual acuity (VA), contrast sensitivity (CS), stereoscopic vision, and monocular visual fields (VFs), which were integrated to estimate the binocular VFs. Type of lenses used in their habitual correction was noted. Out of the 212 subjects who were examined, 38% reported at least one fall and 48% of these reported at least two falls during the last 2 years. Most subjects had normal results; 90% had normal binocular VA, 85% had normal binocular CS, and ~80% had positive stereopsis. Twenty-nine subjects had VF defects in the lower quadrants of the binocular VF, and 14 of these reported at least one fall. A significant association was seen between one fall or more and VA better eye, the odds ratio (OR) was 2.26, P=0.013, and between recurrent falls and lack of stereoscopic vision, the OR was 3.23, P=0.002; no other functional test showed any significant association with recurrent falls. The ORs were 1.58 for worse binocular VA, 0.60 for worse binocular CS, and 0.71 for non-normal stereoscopic vision for at least one fall, but wide confidence intervals made it difficult to draw firm conclusions about any association. Bifocal or progressive spectacles were worn by 71% with no significant difference between fallers and nonfallers (P=0.078). Even though ~40% of the total sample had experienced one or more falls, the only visual function test significantly associated with falls were VA better eye, lack of stereoscopic vision, and recurrent falls. Our results suggest that there may be more powerful predictors of falling than decreased visual ability.

  14. Retrospective Comparison of Visual Outcomes After KAMRA Corneal Inlay Implantation With Simultaneous PRK or LASIK.

    Science.gov (United States)

    Moshirfar, Majid; Bean, Andrew E; Albarracin, Julio C; Rebenitsch, Ronald L; Wallace, Ryan T; Birdsong, Orry C

    2018-05-01

    To report a retrospective study of simultaneous LASIK versus photorefractive keratectomy (PRK) with accompanying small-aperture cornea inlay implantation (KAMRA; AcuFocus, Inc., Irvine, CA) in treating presbyopia. Simultaneous LASIK/inlay and simultaneous PRK/inlay was performed on 79 and 47 patients, respectively. Follow-up examinations were conducted at 1, 3, and 6 months postoperatively. The main outcome measures were safety, efficacy, predictability, and stability with primary emphasis on monocular uncorrected near visual acuity (UNVA). Both groups met U.S. Food and Drug Administration criteria for efficacy with 95% and 55% of the LASIK/inlay group and 83% and 52% of the PRK/inlay group having a monocular UNVA of 20/40 (J5) and 20/25 (J2), respectively, at 6-month follow-up. Ninety-two percent of the LASIK/inlay group and 95% of the PRK/inlay group had a UDVA of 20/40 or better at 6 months. Two eyes lost one line of corrected distance visual acuity (CDVA). Mild hyperopic shift was noted in both groups at 6 months. Simultaneous PRK/inlay and LASIK/inlay meet the U.S. Food and Drug Administration standards for efficacy and safety based on 6-month preliminary results and have similar outcomes to emmetropic eyes. [J Refract Surg. 2018;34(5):310-315.]. Copyright 2018, SLACK Incorporated.

  15. Data visualization

    CERN Document Server

    Azzam, Tarek

    2013-01-01

    Do you communicate data and information to stakeholders? In Part 1, we introduce recent developments in the quantitative and qualitative data visualization field and provide a historical perspective on data visualization, its potential role in evaluation practice, and future directions. Part 2 delivers concrete suggestions for optimally using data visualization in evaluation, as well as suggestions for best practices in data visualization design. It focuses on specific quantitative and qualitative data visualization approaches that include data dashboards, graphic recording, and geographic information systems (GIS). Readers will get a step-by-step process for designing an effective data dashboard system for programs and organizations, and various suggestions to improve their utility.

  16. Visual Literacy and Visual Thinking.

    Science.gov (United States)

    Hortin, John A.

    It is proposed that visual literacy be defined as the ability to understand (read) and use (write) images and to think and learn in terms of images. This definition includes three basic principles: (1) visuals are a language and thus analogous to verbal language; (2) a visually literate person should be able to understand (read) images and use…

  17. Visual Literacy and Visual Culture.

    Science.gov (United States)

    Messaris, Paul

    Familiarity with specific images or sets of images plays a role in a culture's visual heritage. Two questions can be asked about this type of visual literacy: Is this a type of knowledge that is worth building into the formal educational curriculum of our schools? What are the educational implications of visual literacy? There is a three-part…

  18. Hidden loss

    DEFF Research Database (Denmark)

    Kieffer-Kristensen, Rikke; Johansen, Karen Lise Gaardsvig

    2013-01-01

    to participate. RESULTS: All children were affected by their parents' ABI and the altered family situation. The children's expressions led the authors to identify six themes, including fear of losing the parent, distress and estrangement, chores and responsibilities, hidden loss, coping and support. The main......PRIMARY OBJECTIVE: The purpose of this study was to listen to and learn from children showing high levels of post-traumatic stress symptoms after parental acquired brain injury (ABI), in order to achieve an in-depth understanding of the difficulties the children face in their everyday lives...... finding indicates that the children experienced numerous losses, many of which were often suppressed or neglected by the children to protect the ill parents. CONCLUSIONS: The findings indicated that the children seemed to make a special effort to hide their feelings of loss and grief in order to protect...

  19. Visual outcome and optical quality after bilateral implantation of aspheric diffractive multifocal, aspheric monofocal and spherical monofocal intraocular lenses: a prospective comparison

    Directory of Open Access Journals (Sweden)

    Ke Yao

    2013-06-01

    Full Text Available AIM: To evaluate the visual function after bilateral implantation of aspheric diffractive multifocal Tecnis ZMA00, aspheric monofocal ZA9003 versus spherical monofocal Akreos Adapt intraocular lenses (IOLs.METHODS: Tecnis ZMA00, Tecnis ZA9003 or Akreos Adapt IOLs were bilaterally implanted in 180 eyes from 90 patients. The following parameters were assessed 3 months postoperatively: monocular and binocular uncorrected visual acuity (UCVA and distance-corrected visual acuity (DCVA for distance, intermediate and near, spherical aberration (SA, contrast and glare sensitivity, near point refractive power, uncorrected and best-corrected near stereoscopic acuity (NSA. Patient satisfaction was assessed by a questionnaire.RESULTS: Three months postoperatively, the monocular and binocular UCVA and DCVA at near of Tecnis ZMA00 were significantly better than other two groups. The mean SA for 5.0mm optical zone in Tecnis ZMA00 and Tecnis ZA9003 was significantly lower than that in Akreos Adapt. Mean contrast sensitivity and glare sensitivity were better for Tecnis ZA9003 group than for other two groups. Patients with Tecnis ZMA00 had higher monocular and binocular near point refractive power and uncorrected NSA than monofocal groups. The patients in Tecnis ZMA00 had higher mean values for halo compared with other two groups.CONCLUSION: Tecnis ZMA00 provided better near VA and uncorrected NSA and higher near point refractive power than monofocal IOLs and patients were spectacle independent. The IOLs with Tecnis aspheric design improved contrast and glare sensitivity. Patients with Tecnis ZMA00 reported more disturbances on visual phenomena of halo.

  20. Analysis of the Relationship Between Training Experience and Visual Sensory Functions in Athletes from Different Sports

    Directory of Open Access Journals (Sweden)

    Lesiakowski Piotr

    2017-06-01

    Full Text Available Introduction. Gaining insight into the mechanisms and scope of possible adaptations of visual functions to the conditions determined by the demands imposed by sports training seems to be very interesting not only from a cognitive point of view, but also with respect to the practical applications of the findings of such investigations in the training process. The aim of the study was to assess the function of early visual processing in athletes representing different sports disciplines with varying training experience. Material and methods. The study involved 95 athletes practising football (n = 24, volleyball (n = 22, boxing (n = 26, and rowing (n = 23. The bioelectric function of the visual pathway was assessed based on recordings of visual evoked potentials (VEPs. The regions which were stimulated were the peripheral and central areas of the retina. During the test, we recorded the amplitude (μV and latency (ms of the P100 component of the VEP waveform for both monocular stimulation (for the dominant and non-dominant eye and binocular stimulation. Results. Lower VEP P100 amplitude values were found for the peripheral and central locations for monocular and binocular viewing in more experienced volleyball players and rowers (p 0.05 in intragroup variability in VEP P100 latency in relation to training experience in any of the sports disciplines examined. Conclusions. Training experience has an influence on the early stage of sensory processing with respect to neural activity. Training experience has been found to differentiate athletes in terms of the temporal parameters of the visual evoked potentials recorded in the current study only to a limited extent.

  1. Traffic Visualization

    DEFF Research Database (Denmark)

    Picozzi, Matteo; Verdezoto, Nervo; Pouke, Matti

    2013-01-01

    In this paper, we present a space-time visualization to provide city's decision-makers the ability to analyse and uncover important "city events" in an understandable manner for city planning activities. An interactive Web mashup visualization is presented that integrates several visualization...... techniques to give a rapid overview of traffic data. We illustrate our approach as a case study for traffic visualization systems, using datasets from the city of Oulu that can be extended to other city planning activities. We also report the feedback of real users (traffic management employees, traffic police...

  2. Visualization Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Evaluates and improves the operational effectiveness of existing and emerging electronic warfare systems. By analyzing and visualizing simulation results...

  3. Distributed Visualization

    Data.gov (United States)

    National Aeronautics and Space Administration — Distributed Visualization allows anyone, anywhere, to see any simulation, at any time. Development focuses on algorithms, software, data formats, data systems and...

  4. Visual impairment secondary to congenital glaucoma in children: visual responses, optical correction and use of low vision AIDS

    Directory of Open Access Journals (Sweden)

    Maria Aparecida Onuki Haddad

    2009-01-01

    Full Text Available INTRODUCTION: Congenital glaucoma is frequently associated with visual impairment due to optic nerve damage, corneal opacities, cataracts and amblyopia. Poor vision in childhood is related to global developmental problems, and referral to vision habilitation/rehabilitation services should be without delay to promote efficient management of the impaired vision. OBJECTIVE: To analyze data concerning visual response, the use of optical correction and prescribed low vision aids in a population of children with congenital glaucoma. METHOD: The authors analyzed data from 100 children with congenital glaucoma to assess best corrected visual acuity, prescribed optical correction and low vision aids. RESULTS: Fifty-five percent of the sample were male, 43% female. The mean age was 6.3 years. Two percent presented normal visual acuity levels, 29% mild visual impairment, 28% moderate visual impairment, 15% severe visual impairment, 11% profound visual impairment, and 15% near blindness. Sixty-eight percent received optical correction for refractive errors. Optical low vision aids were adopted for distance vision in 34% of the patients and for near vision in 6%. A manual monocular telescopic system with 2.8 × magnification was the most frequently prescribed low vision aid for distance, and for near vision a +38 diopter illuminated stand magnifier was most frequently prescribed. DISCUSSION AND CONCLUSION: Careful low vision assessment and the appropriate prescription of optical corrections and low vision aids are mandatory in children with congenital glaucoma, since this will assist their global development, improving efficiency in daily life activities and promoting social and educational inclusion.

  5. Visual Impairment

    Science.gov (United States)

    ... site Sitio para adolescentes Body Mind Sexual Health Food & Fitness Diseases & Conditions Infections Drugs & Alcohol School & Jobs Sports Expert Answers (Q&A) Staying Safe Videos for Educators Search English Español Visual Impairment KidsHealth / For Teens / Visual Impairment What's in ...

  6. Visual attention

    NARCIS (Netherlands)

    Evans, K.K.; Horowitz, T.S.; Howe, P.; Pedersini, R.; Reijnen, E.; Pinto, Y.; Wolfe, J.M.

    2011-01-01

    A typical visual scene we encounter in everyday life is complex and filled with a huge amount of perceptual information. The term, ‘visual attention’ describes a set of mechanisms that limit some processing to a subset of incoming stimuli. Attentional mechanisms shape what we see and what we can act

  7. Recovery from optic neuritis: an ROI-based analysis of LGN and visual cortical areas

    DEFF Research Database (Denmark)

    Korsholm, Kirsten; Madsen, Kristoffer Hougaard; Frederiksen, Jette L

    2007-01-01

    in the ROIs and compared activation during monocular stimulation of the affected and unaffected eye. In the acute phase the activation of LGN during visual stimulation of the affected eye was significantly reduced (P difference in LGN activation between...... the affected and unaffected eye diminished during recovery, and after 180 days the difference was no longer significant (P = 0.59). The decreased difference during recovery was mainly due to an increase in the fMRI signal when stimulating the affected eye, but included a component of a decreasing fMRI signal...... from LGN when stimulating the unaffected eye. In LOC, V1 and V2 activation during visual stimulation of the affected eye in the acute phase was significantly reduced (P difference diminished with no significant differences left after 180...

  8. Visual Education

    DEFF Research Database (Denmark)

    Buhl, Mie; Flensborg, Ingelise

    2010-01-01

    The intrinsic breadth of various types of images creates new possibilities and challenges for visual education. The digital media have moved the boundaries between images and other kinds of modalities (e.g. writing, speech and sound) and have augmented the possibilities for integrating the functi......The intrinsic breadth of various types of images creates new possibilities and challenges for visual education. The digital media have moved the boundaries between images and other kinds of modalities (e.g. writing, speech and sound) and have augmented the possibilities for integrating...... to emerge in the interlocutory space of a global visual repertoire and diverse local interpretations. The two perspectives represent challenges for future visual education which require visual competences, not only within the arts but also within the subjects of natural sciences, social sciences, languages...

  9. Visual cognition

    Science.gov (United States)

    Cavanagh, Patrick

    2011-01-01

    Visual cognition, high-level vision, mid-level vision and top-down processing all refer to decision-based scene analyses that combine prior knowledge with retinal input to generate representations. The label “visual cognition” is little used at present, but research and experiments on mid- and high-level, inference-based vision have flourished, becoming in the 21st century a significant, if often understated part, of current vision research. How does visual cognition work? What are its moving parts? This paper reviews the origins and architecture of visual cognition and briefly describes some work in the areas of routines, attention, surfaces, objects, and events (motion, causality, and agency). Most vision scientists avoid being too explicit when presenting concepts about visual cognition, having learned that explicit models invite easy criticism. What we see in the literature is ample evidence for visual cognition, but few or only cautious attempts to detail how it might work. This is the great unfinished business of vision research: at some point we will be done with characterizing how the visual system measures the world and we will have to return to the question of how vision constructs models of objects, surfaces, scenes, and events. PMID:21329719

  10. Visual cognition.

    Science.gov (United States)

    Cavanagh, Patrick

    2011-07-01

    Visual cognition, high-level vision, mid-level vision and top-down processing all refer to decision-based scene analyses that combine prior knowledge with retinal input to generate representations. The label "visual cognition" is little used at present, but research and experiments on mid- and high-level, inference-based vision have flourished, becoming in the 21st century a significant, if often understated part, of current vision research. How does visual cognition work? What are its moving parts? This paper reviews the origins and architecture of visual cognition and briefly describes some work in the areas of routines, attention, surfaces, objects, and events (motion, causality, and agency). Most vision scientists avoid being too explicit when presenting concepts about visual cognition, having learned that explicit models invite easy criticism. What we see in the literature is ample evidence for visual cognition, but few or only cautious attempts to detail how it might work. This is the great unfinished business of vision research: at some point we will be done with characterizing how the visual system measures the world and we will have to return to the question of how vision constructs models of objects, surfaces, scenes, and events. Copyright © 2011 Elsevier Ltd. All rights reserved.

  11. [Visual diagnosis: Waardenburg syndrome].

    Science.gov (United States)

    Hager, T; Walter, H-S; Seitz, B; Käsmann-Kellner, B

    2010-07-01

    Waardenburg syndrome (WS) is a rare disease characterized by a sensorineural hearing loss and pigment anomalies of the iris, skin and hair due to mutations in PAX3. WS can be subdivided into four groups according to major and minor clinical signs. We report the case of a 2 1/2-year-old coloured patient who presented in our department of paediatric ophthalmology for a syndrome search. The patient presented with hearing loss, brilliant blue iris colour and dystopia canthorum. The patient was slightly hypermetropic. Visual acuity was within normal limits according to the Cardiff acuity test. The ocular fundus examination revealed no abnormalities. According to the major and minor criteria defined by the Waardenburg consortium our patient showed the major criteria of WS1, i.e. hearing loss, hypopigmentation of the pigment epithelium of the iris and dystopic canthi. Diagnosis of WS is usually based on the clinical presentation. An additional molecular genetic analysis is possible.

  12. A Visual-Aided Inertial Navigation and Mapping System

    Directory of Open Access Journals (Sweden)

    Rodrigo Munguía

    2016-05-01

    Full Text Available State estimation is a fundamental necessity for any application involving autonomous robots. This paper describes a visual-aided inertial navigation and mapping system for application to autonomous robots. The system, which relies on Kalman filtering, is designed to fuse the measurements obtained from a monocular camera, an inertial measurement unit (IMU and a position sensor (GPS. The estimated state consists of the full state of the vehicle: the position, orientation, their first derivatives and the parameter errors of the inertial sensors (i.e., the bias of gyroscopes and accelerometers. The system also provides the spatial locations of the visual features observed by the camera. The proposed scheme was designed by considering the limited resources commonly available in small mobile robots, while it is intended to be applied to cluttered environments in order to perform fully vision-based navigation in periods where the position sensor is not available. Moreover, the estimated map of visual features would be suitable for multiple tasks: i terrain analysis; ii three-dimensional (3D scene reconstruction; iii localization, detection or perception of obstacles and generating trajectories to navigate around these obstacles; and iv autonomous exploration. In this work, simulations and experiments with real data are presented in order to validate and demonstrate the performance of the proposal.

  13. 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.

  14. Light and dark adaptation of visually perceived eye level controlled by visual pitch.

    Science.gov (United States)

    Matin, L; Li, W

    1995-01-01

    The pitch of a visual field systematically influences the elevation at which a monocularly viewing subject sets a target so as to appear at visually perceived eye level (VPEL). The deviation of the setting from true eye level average approximately 0.6 times the angle of pitch while viewing a fully illuminated complexly structured visual field and is only slightly less with one or two pitched-from-vertical lines in a dark field (Matin & Li, 1994a). The deviation of VPEL from baseline following 20 min of dark adaptation reaches its full value less than 1 min after the onset of illumination of the pitched visual field and decays exponentially in darkness following 5 min of exposure to visual pitch, either 30 degrees topbackward or 20 degrees topforward. The magnitude of the VPEL deviation measured with the dark-adapted right eye following left-eye exposure to pitch was 85% of the deviation that followed pitch exposure of the right eye itself. Time constants for VPEL decay to the dark baseline were the same for same-eye and cross-adaptation conditions and averaged about 4 min. The time constants for decay during dark adaptation were somewhat smaller, and the change during dark adaptation extended over a 16% smaller range following the viewing of the dim two-line pitched-from-vertical stimulus than following the viewing of the complex field. The temporal course of light and dark adaptation of VPEL is virtually identical to the course of light and dark adaptation of the scotopic luminance threshold following exposure to the same luminance. We suggest that, following rod stimulation along particular retinal orientations by portions of the pitched visual field, the storage of the adaptation process resides in the retinogeniculate system and is manifested in the focal system as a change in luminance threshold and in the ambient system as a change in VPEL. The linear model previously developed to account for VPEL, which was based on the interaction of influences from the

  15. Early monocular defocus disrupts the normal development of receptive-field structure in V2 neurons of macaque monkeys.

    Science.gov (United States)

    Tao, Xiaofeng; Zhang, Bin; Shen, Guofu; Wensveen, Janice; Smith, Earl L; Nishimoto, Shinji; Ohzawa, Izumi; Chino, Yuzo M

    2014-10-08

    Experiencing different quality images in the two eyes soon after birth can cause amblyopia, a developmental vision disorder. Amblyopic humans show the reduced capacity for judging the relative position of a visual target in reference to nearby stimulus elements (position uncertainty) and often experience visual image distortion. Although abnormal pooling of local stimulus information by neurons beyond striate cortex (V1) is often suggested as a neural basis of these deficits, extrastriate neurons in the amblyopic brain have rarely been studied using microelectrode recording methods. The receptive field (RF) of neurons in visual area V2 in normal monkeys is made up of multiple subfields that are thought to reflect V1 inputs and are capable of encoding the spatial relationship between local stimulus features. We created primate models of anisometropic amblyopia and analyzed the RF subfield maps for multiple nearby V2 neurons of anesthetized monkeys by using dynamic two-dimensional noise stimuli and reverse correlation methods. Unlike in normal monkeys, the subfield maps of V2 neurons in amblyopic monkeys were severely disorganized: subfield maps showed higher heterogeneity within each neuron as well as across nearby neurons. Amblyopic V2 neurons exhibited robust binocular suppression and the strength of the suppression was positively correlated with the degree of hereogeneity and the severity of amblyopia in individual monkeys. Our results suggest that the disorganized subfield maps and robust binocular suppression of amblyopic V2 neurons are likely to adversely affect the higher stages of cortical processing resulting in position uncertainty and image distortion. Copyright © 2014 the authors 0270-6474/14/3413840-15$15.00/0.

  16. Visual cognition

    Energy Technology Data Exchange (ETDEWEB)

    Pinker, S.

    1985-01-01

    This book consists of essays covering issues in visual cognition presenting experimental techniques from cognitive psychology, methods of modeling cognitive processes on computers from artificial intelligence, and methods of studying brain organization from neuropsychology. Topics considered include: parts of recognition; visual routines; upward direction; mental rotation, and discrimination of left and right turns in maps; individual differences in mental imagery, computational analysis and the neurological basis of mental imagery: componental analysis.

  17. [Impact of Different Percent Tissue Altered Values on Visual Outcome after Refractive Small Incision Lenticule Extraction (ReLEx SMILE)].

    Science.gov (United States)

    Breyer, D R H; Hagen, P; Kaymak, H; Klabe, K; Auffarth, G U; Kretz, F T A

    2017-01-01

    Purpose   To compare the visual outcomes after ReLEx SMILE treatment of eyes with low and high PTA values (PTA: percent tissue altered) within a follow-up period of up to 3 years and to assess whether a high PTA value might contribute to the development of keratectasia, as is the case for LASIK. Methods   This retrospective analysis comprises results from 313 eyes (189 patients) with a PTA value of less than 40 % and of 373 eyes (213 patients) with a PTA value of at least 40 %. Preoperatively and up to 3 years after SMILE surgery, refraction values, monocular corrected (CDVA) and uncorrected distant visual acuity (UDVA) and wavefront data were evaluated. Results   One to 3 years after surgery, the group with PTA lines in 1.1 % (0.0 %) of the cases. Loss of one line occurred in 1.1 % (3.6 %) of the eyes, whereas 97.7 % (96.4 %) remained unchanged or gained lines. With respect to predictability of the spherical equivalent, 92.0 % (78.6 %) of the eyes were within ± 0.5D and 97.7 % (92.9 %) were within ± 1.0D. The group with high PTA values displayed a slightly but significantly greater undercorrection of about 0,25D. 74.4 % (71.8 %) achieved UDVA of at least 20/20 and 96.5 % (87.1 %) achieved at least 20/25. The mean UDVA was - 0.03 ± 0.10logMAR (0.01 ± 0.12logMAR) and its mean difference to the preoperative CDVA was 0.00 ± 0.09logMAR (0.03 ± 0.12logMAR). Conclusion   ReLEx SMILE is a safe and effective corneal refractive treatment, even for PTA values of 40 % and more. Eyes with high PTA values did not display any evidence of keratectasia development within the 3-year follow-up of this study. Georg Thieme Verlag KG Stuttgart · New York.

  18. Visual search, visual streams, and visual architectures.

    Science.gov (United States)

    Green, M

    1991-10-01

    Most psychological, physiological, and computational models of early vision suggest that retinal information is divided into a parallel set of feature modules. The dominant theories of visual search assume that these modules form a "blackboard" architecture: a set of independent representations that communicate only through a central processor. A review of research shows that blackboard-based theories, such as feature-integration theory, cannot easily explain the existing data. The experimental evidence is more consistent with a "network" architecture, which stresses that: (1) feature modules are directly connected to one another, (2) features and their locations are represented together, (3) feature detection and integration are not distinct processing stages, and (4) no executive control process, such as focal attention, is needed to integrate features. Attention is not a spotlight that synthesizes objects from raw features. Instead, it is better to conceptualize attention as an aperture which masks irrelevant visual information.

  19. Visual evoked potentials in patients after methanol poisoning.

    Science.gov (United States)

    Urban, Pavel; Zakharov, Sergey; Diblík, Pavel; Pelclová, Daniela; Ridzoň, Petr

    2016-01-01

    We report the results of the visual evoked potentials (VEP) examination in patients after severe poisoning by methanol. The group of 47 patients (38 males and 9 females) was assembled out of persons who survived an outbreak of poisoning by the methanol adulterated alcohol beverages, which happened in the Czech Republic in 2012-2013. The visual evoked potentials examination was performed using monocular checkerboard pattern-reversal stimulation. Two criteria of abnormality were chosen: missing evoked response, and wave P1 latency > 117 ms. Non-parametric statistical methods (median, range, and the median test) were used to analyze factors influencing the VEP abnormality. The visual evoked potential was abnormal in 20 patients (43%), 5 of them had normal visual acuity on the Snellen chart. The VEP abnormality did not correlate significantly with initial serum concentrations of methanol, formic acid or lactate; however, it showed statistically significant inverse relation to the initial serum pH: the subgroup with the abnormal VEP had significantly lower median pH in comparison with the subgroup with the normal VEP (7.16 vs. 7.34, p = 0.04). The abnormality was not related to chronic alcohol abuse. The visual evoked potentials examination appeared sensitive enough to detected even subclinical impairment of the optic system. Metabolic acidosis is likely to be the key factor related to the development of visual damage induced by methanol. The examination performed with a delay of 1-9 months after the poisoning documented the situation relatively early after the event. It is considered as a baseline for the planned long-term follow-up of the patients, which will make it possible to assess the dynamics of the observed changes, their reversibility, and the occurrence of potential late sequelae. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

  20. Visualizing water

    Science.gov (United States)

    Baart, F.; van Gils, A.; Hagenaars, G.; Donchyts, G.; Eisemann, E.; van Velzen, J. W.

    2016-12-01

    A compelling visualization is captivating, beautiful and narrative. Here we show how melding the skills of computer graphics, art, statistics, and environmental modeling can be used to generate innovative, attractive and very informative visualizations. We focus on the topic of visualizing forecasts and measurements of water (water level, waves, currents, density, and salinity). For the field of computer graphics and arts, water is an important topic because it occurs in many natural scenes. For environmental modeling and statistics, water is an important topic because the water is essential for transport, a healthy environment, fruitful agriculture, and a safe environment.The different disciplines take different approaches to visualizing water. In computer graphics, one focusses on creating water as realistic looking as possible. The focus on realistic perception (versus the focus on the physical balance pursued by environmental scientists) resulted in fascinating renderings, as seen in recent games and movies. Visualization techniques for statistical results have benefited from the advancement in design and journalism, resulting in enthralling infographics. The field of environmental modeling has absorbed advances in contemporary cartography as seen in the latest interactive data-driven maps. We systematically review the design emerging types of water visualizations. The examples that we analyze range from dynamically animated forecasts, interactive paintings, infographics, modern cartography to web-based photorealistic rendering. By characterizing the intended audience, the design choices, the scales (e.g. time, space), and the explorability we provide a set of guidelines and genres. The unique contributions of the different fields show how the innovations in the current state of the art of water visualization have benefited from inter-disciplinary collaborations.

  1. Visual comparison for information visualization

    KAUST Repository

    Gleicher, M.; Albers, D.; Walker, R.; Jusufi, I.; Hansen, C. D.; Roberts, J. C.

    2011-01-01

    Data analysis often involves the comparison of complex objects. With the ever increasing amounts and complexity of data, the demand for systems to help with these comparisons is also growing. Increasingly, information visualization tools support such comparisons explicitly, beyond simply allowing a viewer to examine each object individually. In this paper, we argue that the design of information visualizations of complex objects can, and should, be studied in general, that is independently of what those objects are. As a first step in developing this general understanding of comparison, we propose a general taxonomy of visual designs for comparison that groups designs into three basic categories, which can be combined. To clarify the taxonomy and validate its completeness, we provide a survey of work in information visualization related to comparison. Although we find a great diversity of systems and approaches, we see that all designs are assembled from the building blocks of juxtaposition, superposition and explicit encodings. This initial exploration shows the power of our model, and suggests future challenges in developing a general understanding of comparative visualization and facilitating the development of more comparative visualization tools. © The Author(s) 2011.

  2. Visual comparison for information visualization

    KAUST Repository

    Gleicher, M.

    2011-09-07

    Data analysis often involves the comparison of complex objects. With the ever increasing amounts and complexity of data, the demand for systems to help with these comparisons is also growing. Increasingly, information visualization tools support such comparisons explicitly, beyond simply allowing a viewer to examine each object individually. In this paper, we argue that the design of information visualizations of complex objects can, and should, be studied in general, that is independently of what those objects are. As a first step in developing this general understanding of comparison, we propose a general taxonomy of visual designs for comparison that groups designs into three basic categories, which can be combined. To clarify the taxonomy and validate its completeness, we provide a survey of work in information visualization related to comparison. Although we find a great diversity of systems and approaches, we see that all designs are assembled from the building blocks of juxtaposition, superposition and explicit encodings. This initial exploration shows the power of our model, and suggests future challenges in developing a general understanding of comparative visualization and facilitating the development of more comparative visualization tools. © The Author(s) 2011.

  3. Graph Structure-Based Simultaneous Localization and Mapping Using a Hybrid Method of 2D Laser Scan and Monocular Camera Image in Environments with Laser Scan Ambiguity

    Directory of Open Access Journals (Sweden)

    Taekjun Oh

    2015-07-01

    Full Text Available Localization is an essential issue for robot navigation, allowing the robot to perform tasks autonomously. However, in environments with laser scan ambiguity, such as long corridors, the conventional SLAM (simultaneous localization and mapping algorithms exploiting a laser scanner may not estimate the robot pose robustly. To resolve this problem, we propose a novel localization approach based on a hybrid method incorporating a 2D laser scanner and a monocular camera in the framework of a graph structure-based SLAM. 3D coordinates of image feature points are acquired through the hybrid method, with the assumption that the wall is normal to the ground and vertically flat. However, this assumption can be relieved, because the subsequent feature matching process rejects the outliers on an inclined or non-flat wall. Through graph optimization with constraints generated by the hybrid method, the final robot pose is estimated. To verify the effectiveness of the proposed method, real experiments were conducted in an indoor environment with a long corridor. The experimental results were compared with those of the conventional GMappingapproach. The results demonstrate that it is possible to localize the robot in environments with laser scan ambiguity in real time, and the performance of the proposed method is superior to that of the conventional approach.

  4. Modification of visual function by early visual experience.

    Science.gov (United States)

    Blakemore, C

    1976-07-01

    Physiological experiments, involving recording from the visual cortex in young kittens and monkeys, have given new insight into human developmental disorders. In the visual cortex of normal cats and monkeys most neurones are selectively sensitive to the orientation of moving edges and they receive very similar signals from both eyes. Even in very young kittens without visual experience, most neurones are binocularly driven and a small proportion of them are genuinely orientation selective. There is no passive maturation of the system in the absence of visual experience, but even very brief exposure to patterned images produces rapid emergence of the adult organization. These results are compared to observations on humans who have "recovered" from early blindness. Covering one eye in a kitten or a monkey, during a sensitive period early in life, produces a virtually complete loss of input from that eye in the cortex. These results can be correlated with the production of "stimulus deprivation amblyopia" in infants who have had one eye patched. Induction of a strabismus causes a loss of binocularity in the visual cortex, and in humans it leads to a loss of stereoscopic vision and binocular fusion. Exposing kittens to lines of one orientation modifies the preferred orientations of cortical cells and there is an analogous "meridional amblyopia" in astigmatic humans. The existence of a sensitive period in human vision is discussed, as well as the possibility of designing remedial and preventive treatments for human developmental disorders.

  5. Clinical profile and visual outcome of ocular injuries in a rural area of western India.

    Science.gov (United States)

    Misra, Somen; Nandwani, Rupali; Gogri, Pratik; Misra, Neeta

    2013-01-01

    Ocular trauma is a major cause of visual impairment and morbidity worldwide. To identify the various type of ocular injury in a rural area, determine the presence of any associated visual damage and assess the final visual outcome after treatment. Hospital-based, prospective study conducted over a period of two years. A total of 60 patients of ocular trauma were included. Ocular injuries were more commonly seen in adult (55 per cent) patients who were associated with agricultural work (43.33 per cent). They were more common in male patients (71.67 per cent). Closed globe injury (68.33 per cent) was more common than open globe injury (31.67 per cent). Both in open and closed globe injuries, the commonest object causing injury was a wooden stick. Just 26.7 per cent of the patients had a visual acuity better than 6/60 at presentation; while after completed treatment at two months follow-up, 68.3 per cent had best corrected visual acuity better than 6/60. Agricultural trauma is an important cause of monocular blindness in rural India. The visual outcome depends upon the site and size of the injury and the extent of the ocular damage.

  6. Activity-dependent regulation of MHC class I expression in the developing primary visual cortex of the common marmoset monkey

    Directory of Open Access Journals (Sweden)

    Schlumbohm Christina

    2011-01-01

    Full Text Available Abstract Background Several recent studies have highlighted the important role of immunity-related molecules in synaptic plasticity processes in the developing and adult mammalian brains. It has been suggested that neuronal MHCI (major histocompatibility complex class I genes play a role in the refinement and pruning of synapses in the developing visual system. As a fast evolutionary rate may generate distinct properties of molecules in different mammalian species, we studied the expression of MHCI molecules in a nonhuman primate, the common marmoset monkey (Callithrix jacchus. Methods and results Analysis of expression levels of MHCI molecules in the developing visual cortex of the common marmoset monkeys revealed a distinct spatio-temporal pattern. High levels of expression were detected very early in postnatal development, at a stage when synaptogenesis takes place and ocular dominance columns are formed. To determine whether the expression of MHCI molecules is regulated by retinal activity, animals were subjected to monocular enucleation. Levels of MHCI heavy chain subunit transcripts in the visual cortex were found to be elevated in response to monocular enucleation. Furthermore, MHCI heavy chain immunoreactivity revealed a banded pattern in layer IV of the visual cortex in enucleated animals, which was not observed in control animals. This pattern of immunoreactivity indicated that higher expression levels were associated with retinal activity coming from the intact eye. Conclusions These data demonstrate that, in the nonhuman primate brain, expression of MHCI molecules is regulated by neuronal activity. Moreover, this study extends previous findings by suggesting a role for neuronal MHCI molecules during synaptogenesis in the visual cortex.

  7. Causes of visual loss and their risk factors: an incidence summary from the Barbados Eye Studies Causas de la pérdida visual y sus factores de riesgo: resumen de la incidencia a partir de los Estudios de Oftalmología de Barbados

    Directory of Open Access Journals (Sweden)

    M. Cristina Leske

    2010-04-01

    Full Text Available OBJECTIVES: To summarize incidence and risk factors for each main cause of visual loss in an African-Caribbean population and discuss the implications of these data from a public health perspective. METHODS: A nationally representative cohort (n = 4 709; ages 40-84 years at baseline had ophthalmic and other examinations over 9 years. Incidence rates were estimated by the product-limit approach. Risk factors were evaluated from Cox regression models. RESULTS: Average incidence was ~ 0.1% per year for blindness (OBJETIVO: Presentar un resumen de la incidencia y los factores de riesgo de cada causa principal de pérdida de la visión en una población afrocaribeña y examinar las implicaciones de estos datos desde una perspectiva de salud pública. MÉTODOS: En una cohorte representativa al nivel nacional (n = 4 709; edades de 40 a 84 años al inicio se hicieron exploraciones oftálmicas y de otros tipos durante nueve años. Se calcularon las tasas de incidencia mediante el método del producto-límite. Los factores de riesgo se evaluaron mediante modelos de regresión de Cox. RESULTADOS: La incidencia promedio fue ~ 0,1% al año para la ceguera (< 6/120 y de 0,7% al año para la visión deficiente (< 6/18 a 6/120, que aumentó de manera pronunciada con la edad (P < 0,05 y afectó a la calidad de vida relacionada (P < 0,05. Las cataratas y el glaucoma de ángulo abierto relacionados con la edad representaron 73,2% de los casos de ceguera, y 8,9% de los casos de retinopatía diabética; las cataratas causaron dos tercios de los casos de visión deficiente. La incidencia media fue de 5,1% al año en todos los cambios del cristalino (opacidades graduables o no graduables o afaquia, y de 0,4% al año en la cirugía de cataratas. La incidencia del glaucoma de ángulo abierto definitivo fue de 0,5% al año (0,9% en el caso de la sospecha o la probabilidad; 53% de los pacientes afectados no era conciente. Las personas que padecían diabetes tenían una

  8. Callosal Influence on Visual Receptive Fields Has an Ocular, an Orientation-and Direction Bias

    Directory of Open Access Journals (Sweden)

    Sergio A. Conde-Ocazionez

    2018-04-01

    Full Text Available One leading hypothesis on the nature of visual callosal connections (CC is that they replicate features of intrahemispheric lateral connections. However, CC act also in the central part of the binocular visual field. In agreement, early experiments in cats indicated that they provide the ipsilateral eye part of binocular receptive fields (RFs at the vertical midline (Berlucchi and Rizzolatti, 1968, and play a key role in stereoscopic function. But until today callosal inputs to receptive fields activated by one or both eyes were never compared simultaneously, because callosal function has been often studied by cutting or lesioning either corpus callosum or optic chiasm not allowing such a comparison. To investigate the functional contribution of CC in the intact cat visual system we recorded both monocular and binocular neuronal spiking responses and receptive fields in the 17/18 transition zone during reversible deactivation of the contralateral hemisphere. Unexpectedly from many of the previous reports, we observe no change in ocular dominance during CC deactivation. Throughout the transition zone, a majority of RFs shrink, but several also increase in size. RFs are significantly more affected for ipsi- as opposed to contralateral stimulation, but changes are also observed with binocular stimulation. Noteworthy, RF shrinkages are tiny and not correlated to the profound decreases of monocular and binocular firing rates. They depend more on orientation and direction preference than on eccentricity or ocular dominance of the receiving neuron's RF. Our findings confirm that in binocularly viewing mammals, binocular RFs near the midline are constructed via the direct geniculo-cortical pathway. They also support the idea that input from the two eyes complement each other through CC: Rather than linking parts of RFs separated by the vertical meridian, CC convey a modulatory influence, reflecting the feature selectivity of lateral circuits, with a

  9. Visual cognition

    Energy Technology Data Exchange (ETDEWEB)

    Pinker, S.

    1985-01-01

    This collection of research papers on visual cognition first appeared as a special issue of Cognition: International Journal of Cognitive Science. The study of visual cognition has seen enormous progress in the past decade, bringing important advances in our understanding of shape perception, visual imagery, and mental maps. Many of these discoveries are the result of converging investigations in different areas, such as cognitive and perceptual psychology, artificial intelligence, and neuropsychology. This volume is intended to highlight a sample of work at the cutting edge of this research area for the benefit of students and researchers in a variety of disciplines. The tutorial introduction that begins the volume is designed to help the nonspecialist reader bridge the gap between the contemporary research reported here and earlier textbook introductions or literature reviews.

  10. Visualizing Transformation

    DEFF Research Database (Denmark)

    Pedersen, Pia

    2012-01-01

    Transformation, defined as the step of extracting, arranging and simplifying data into visual form (M. Neurath, 1974), was developed in connection with ISOTYPE (International System Of TYpographic Picture Education) and might well be the most important legacy of Isotype to the field of graphic...... design. Recently transformation has attracted renewed interest because of the book The Transformer written by Robin Kinross and Marie Neurath. My on-going research project, summarized in this paper, identifies and depicts the essential principles of data visualization underlying the process...... of transformation with reference to Marie Neurath’s sketches on the Bilston Project. The material has been collected at the Otto and Marie Neurath Collection housed at the University of Reading, UK. By using data visualization as a research method to look directly into the process of transformation, the project...

  11. Visual rehabilitation: visual scanning, multisensory stimulation and vision restoration trainings

    Directory of Open Access Journals (Sweden)

    Neil M. Dundon

    2015-07-01

    Full Text Available Neuropsychological training methods of visual rehabilitation for homonymous vision loss caused by postchiasmatic damage fall into two fundamental paradigms: compensation and restoration. Existing methods can be classified into three groups: Visual Scanning Training (VST, Audio-Visual Scanning Training (AViST and Vision Restoration Training (VRT. VST and AViST aim at compensating vision loss by training eye scanning movements, whereas VRT aims at improving lost vision by activating residual visual functions by training light detection and discrimination of visual stimuli. This review discusses the rationale underlying these paradigms and summarizes the available evidence with respect to treatment efficacy. The issues raised in our review should help guide clinical care and stimulate new ideas for future research uncovering the underlying neural correlates of the different treatment paradigms. We propose that both local within-system interactions (i.e., relying on plasticity within peri-lesional spared tissue and changes in more global between-system networks (i.e., recruiting alternative visual pathways contribute to both vision restoration and compensatory rehabilitation that ultimately have implications for the rehabilitation of cognitive functions.

  12. Vision In Stroke cohort: Profile overview of visual impairment.

    Science.gov (United States)

    Rowe, Fiona J

    2017-11-01

    To profile the full range of visual disorders from a large prospective observation study of stroke survivors referred by stroke multidisciplinary teams to orthoptic services with suspected visual problems. Multicenter prospective study undertaken in 20 acute Trust hospitals. Standardized screening/referral forms and investigation forms documented data on referral signs and symptoms plus type and extent of visual impairment. Of 1,345 patients referred with suspected visual impairment, 915 were recruited (59% men; mean age at stroke onset 69 years [SD 14]). Initial visual assessment was at median 22 days post stroke onset. Eight percent had normal visual assessment. Of 92% with confirmed visual impairment, 24% had reduced central visual acuity visual field loss was present in 52%, most commonly homonymous hemianopia. Fifteen percent had visual inattention and 4.6% had other visual perceptual disorders. Overall 84% were visually symptomatic with visual field loss the most common complaint followed by blurred vision, reading difficulty, and diplopia. Treatment options were provided to all with confirmed visual impairment. Targeted advice was most commonly provided along with refraction, prisms, and occlusion. There are a wide range of visual disorders that occur following stroke and, frequently, with visual symptoms. There are equally a wide variety of treatment options available for these individuals. All stroke survivors require screening for visual impairment and warrant referral for specialist assessment and targeted treatment specific to the type of visual impairment.

  13. Visual attention.

    Science.gov (United States)

    Evans, Karla K; Horowitz, Todd S; Howe, Piers; Pedersini, Roccardo; Reijnen, Ester; Pinto, Yair; Kuzmova, Yoana; Wolfe, Jeremy M

    2011-09-01

    A typical visual scene we encounter in everyday life is complex and filled with a huge amount of perceptual information. The term, 'visual attention' describes a set of mechanisms that limit some processing to a subset of incoming stimuli. Attentional mechanisms shape what we see and what we can act upon. They allow for concurrent selection of some (preferably, relevant) information and inhibition of other information. This selection permits the reduction of complexity and informational overload. Selection can be determined both by the 'bottom-up' saliency of information from the environment and by the 'top-down' state and goals of the perceiver. Attentional effects can take the form of modulating or enhancing the selected information. A central role for selective attention is to enable the 'binding' of selected information into unified and coherent representations of objects in the outside world. In the overview on visual attention presented here we review the mechanisms and consequences of selection and inhibition over space and time. We examine theoretical, behavioral and neurophysiologic work done on visual attention. We also discuss the relations between attention and other cognitive processes such as automaticity and awareness. WIREs Cogni Sci 2011 2 503-514 DOI: 10.1002/wcs.127 For further resources related to this article, please visit the WIREs website. Copyright © 2011 John Wiley & Sons, Ltd.

  14. Visualizing Series

    Science.gov (United States)

    Unal, Hasan

    2008-01-01

    The importance of visualisation and multiple representations in mathematics has been stressed, especially in a context of problem solving. Hanna and Sidoli comment that "Diagrams and other visual representations have long been welcomed as heuristic accompaniments to proof, where they not only facilitate the understanding of theorems and their…

  15. Método computadorizado para medida da acuidade visual A computerized method for visual acuity assessment

    Directory of Open Access Journals (Sweden)

    Patrícia Katayama Kjaer Arippol

    2006-12-01

    Full Text Available OBJETIVO: Elaborar e validar teste computadorizado para medida da acuidade visual de escolares. MÉTODOS: Foi elaborado teste computadorizado para determinação da acuidade visual utilizando os padrões das tabelas logarítmicas impressas adotadas na clínica oftalmológica. Foram avaliados 90 alunos da primeira série do ensino básico, oito estudantes do curso de Tecnologia Oftálmica da UNIFESP-EPM e 10 pacientes do ambulatório de Estrabismo do Departamento de Oftalmologia da UNIFESP-EPM. Todos os sujeitos foram avaliados pelo mesmo examinador e submetidos ao exame de acuidade visual monocular, pela tabela logarítmica de optotipos E impressa e do novo teste computadorizado no mesmo momento. Os participantes forneceram os seus consentimentos após esclarecimento. RESULTADOS: As análises estatísticas revelaram correlação excelente (r>0,75 entre os dois métodos, apesar da leve tendência apresentada pelo teste computadorizado em superestimar a acuidade visual quando comparado com o padrão-ouro. O teste computadorizado apresentou sensibilidade de 100% e especificidade de 94%. CONCLUSÕES: Os resultados obtidos nos permitem dizer que o teste computadorizado pode ser utilizado como novo recurso para triagem da qualidade visual dos escolares, por ser método rápido, de fácil aplicação, barato, automático e atrativo para as crianças. A automatização desvincula o aplicador da interpretação das respostas dadas pelo aluno testado, garante padronização do procedimento, que favorece as análises de acompanhamento e pode ser realizado por diferentes examinadores. Para melhor compreensão da efetividade do teste como instrumento de triagem visual, seria interessante instituí-lo nas escolas do curso básico, após treinamento dos professores para sua aplicação.PURPOSE: To elaborate and to validate a computerized test for visual acuity screening of school-age children. METHODS: We have created a computerized test for visual acuity

  16. Vision in avian emberizid foragers: maximizing both binocular vision and fronto-lateral visual acuity.

    Science.gov (United States)

    Moore, Bret A; Pita, Diana; Tyrrell, Luke P; Fernández-Juricic, Esteban

    2015-05-01

    Avian species vary in their visual system configuration, but previous studies have often compared single visual traits between two to three distantly related species. However, birds use different visual dimensions that cannot be maximized simultaneously to meet different perceptual demands, potentially leading to trade-offs between visual traits. We studied the degree of inter-specific variation in multiple visual traits related to foraging and anti-predator behaviors in nine species of closely related emberizid sparrows, controlling for phylogenetic effects. Emberizid sparrows maximize binocular vision, even seeing their bill tips in some eye positions, which may enhance the detection of prey and facilitate food handling. Sparrows have a single retinal center of acute vision (i.e. fovea) projecting fronto-laterally (but not into the binocular field). The foveal projection close to the edge of the binocular field may shorten the time to gather and process both monocular and binocular visual information from the foraging substrate. Contrary to previous work, we found that species with larger visual fields had higher visual acuity, which may compensate for larger blind spots (i.e. pectens) above the center of acute vision, enhancing predator detection. Finally, species with a steeper change in ganglion cell density across the retina had higher eye movement amplitude, probably due to a more pronounced reduction in visual resolution away from the fovea, which would need to be moved around more frequently. The visual configuration of emberizid passive prey foragers is substantially different from that of previously studied avian groups (e.g. sit-and-wait and tactile foragers). © 2015. Published by The Company of Biologists Ltd.

  17. Optimization of Visual Information Presentation for Visual Prosthesis

    Directory of Open Access Journals (Sweden)

    Fei Guo

    2018-01-01

    Full Text Available Visual prosthesis applying electrical stimulation to restore visual function for the blind has promising prospects. However, due to the low resolution, limited visual field, and the low dynamic range of the visual perception, huge loss of information occurred when presenting daily scenes. The ability of object recognition in real-life scenarios is severely restricted for prosthetic users. To overcome the limitations, optimizing the visual information in the simulated prosthetic vision has been the focus of research. This paper proposes two image processing strategies based on a salient object detection technique. The two processing strategies enable the prosthetic implants to focus on the object of interest and suppress the background clutter. Psychophysical experiments show that techniques such as foreground zooming with background clutter removal and foreground edge detection with background reduction have positive impacts on the task of object recognition in simulated prosthetic vision. By using edge detection and zooming technique, the two processing strategies significantly improve the recognition accuracy of objects. We can conclude that the visual prosthesis using our proposed strategy can assist the blind to improve their ability to recognize objects. The results will provide effective solutions for the further development of visual prosthesis.

  18. Optimization of Visual Information Presentation for Visual Prosthesis

    Science.gov (United States)

    Gao, Yong

    2018-01-01

    Visual prosthesis applying electrical stimulation to restore visual function for the blind has promising prospects. However, due to the low resolution, limited visual field, and the low dynamic range of the visual perception, huge loss of information occurred when presenting daily scenes. The ability of object recognition in real-life scenarios is severely restricted for prosthetic users. To overcome the limitations, optimizing the visual information in the simulated prosthetic vision has been the focus of research. This paper proposes two image processing strategies based on a salient object detection technique. The two processing strategies enable the prosthetic implants to focus on the object of interest and suppress the background clutter. Psychophysical experiments show that techniques such as foreground zooming with background clutter removal and foreground edge detection with background reduction have positive impacts on the task of object recognition in simulated prosthetic vision. By using edge detection and zooming technique, the two processing strategies significantly improve the recognition accuracy of objects. We can conclude that the visual prosthesis using our proposed strategy can assist the blind to improve their ability to recognize objects. The results will provide effective solutions for the further development of visual prosthesis. PMID:29731769

  19. Effects of Fluoxetine and Visual Experience on Glutamatergic and GABAergic Synaptic Proteins in Adult Rat Visual Cortex123

    Science.gov (United States)

    Beshara, Simon; Beston, Brett R.; Pinto, Joshua G. A.

    2015-01-01

    Abstract Fluoxetine has emerged as a novel treatment for persistent amblyopia because in adult animals it reinstates critical period-like ocular dominance plasticity and promotes recovery of visual acuity. Translation of these results from animal models to the clinic, however, has been challenging because of the lack of understanding of how this selective serotonin reuptake inhibitor affects glutamatergic and GABAergic synaptic mechanisms that are essential for experience-dependent plasticity. An appealing hypothesis is that fluoxetine recreates a critical period (CP)-like state by shifting synaptic mechanisms to be more juvenile. To test this we studied the effect of fluoxetine treatment in adult rats, alone or in combination with visual deprivation [monocular deprivation (MD)], on a set of highly conserved presynaptic and postsynaptic proteins (synapsin, synaptophysin, VGLUT1, VGAT, PSD-95, gephyrin, GluN1, GluA2, GluN2B, GluN2A, GABAAα1, GABAAα3). We did not find evidence that fluoxetine shifted the protein amounts or balances to a CP-like state. Instead, it drove the balances in favor of the more mature subunits (GluN2A, GABAAα1). In addition, when fluoxetine was paired with MD it created a neuroprotective-like environment by normalizing the glutamatergic gain found in adult MDs. Together, our results suggest that fluoxetine treatment creates a novel synaptic environment dominated by GluN2A- and GABAAα1-dependent plasticity. PMID:26730408

  20. Motor skills of children with unilateral visual impairment in the Infant Aphakia Treatment Study.

    Science.gov (United States)

    Celano, Marianne; Hartmann, E Eugenie; DuBois, Lindreth G; Drews-Botsch, Carolyn

    2016-02-01

    To assess motor functioning in children aged 4 years 6 months enrolled in the Infant Aphakia Treatment Study, and to determine contributions of visual acuity and stereopsis to measured motor skills. One hundred and four children (53% female) with unilateral aphakia randomized to intraocular lens or contact lens treatment were evaluated at 4 years 6 months (age range 4y 6mo-4y 11mo) for monocular recognition visual acuity, motor skills, and stereopsis by a traveling examiner masked to treatment condition. Motor skills were assessed with the Movement Assessment Battery for Children--Second Edition (MABC-2). Visual acuity was operationalized as log10 of the minimum angle of resolution (logMAR) value for treated eye, best logMAR value for either eye, and intraocular logMAR difference. Student's t-tests showed no significant differences in MABC-2 scores between the intraocular lens and contact lens groups. The mean total score was low (6.43; 18th centile) compared with the normative reference group. Motor functioning was not related to visual acuity in the treated eye or to intraocular logMAR difference, but was predicted in a regression model by the better visual acuity of either eye (usually the fellow eye), even after accounting for the influence of age at surgery, examiner, orthotropic ocular alignment, and stereopsis. Children with unilateral congenital cataract may have delayed motor functioning at 4 years 6 months, which may adversely affect their social and academic functioning. © 2015 Mac Keith Press.

  1. Hair Loss (Alopecia)

    Science.gov (United States)

    ... care Kids’ zone Video library Find a dermatologist Hair loss Overview Hereditary hair loss: Millions of men ... of hair loss can often be successfully treated. Hair loss: Overview Also called alopecia (al-o-PEE- ...

  2. Visual hierarchical processing and lateralization of cognitive functions through domestic chicks' eyes.

    Directory of Open Access Journals (Sweden)

    Cinzia Chiandetti

    Full Text Available Hierarchical stimuli have proven effective for investigating principles of visual organization in humans. A large body of evidence suggests that the analysis of the global forms precedes the analysis of the local forms in our species. Studies on lateralization also indicate that analytic and holistic encoding strategies are separated between the two hemispheres of the brain. This raises the question of whether precedence effects may reflect the activation of lateralized functions within the brain. Non-human animals have perceptual organization and functional lateralization that are comparable to that of humans. Here we trained the domestic chick in a concurrent discrimination task involving hierarchical stimuli. Then, we evaluated the animals for analytic and holistic encoding strategies in a series of transformational tests by relying on a monocular occlusion technique. A local precedence emerged in both the left and the right hemisphere, adding further evidence in favour of analytic processing in non-human animals.

  3. Perceived change in orientation from optic flow in the central visual field

    Science.gov (United States)

    Dyre, Brian P.; Andersen, George J.

    1988-01-01

    The effects of internal depth within a simulation display on perceived changes in orientation have been studied. Subjects monocularly viewed displays simulating observer motion within a volume of randomly positioned points through a window which limited the field of view to 15 deg. Changes in perceived spatial orientation were measured by changes in posture. The extent of internal depth within the display, the presence or absence of visual information specifying change in orientation, and the frequency of motion supplied by the display were examined. It was found that increased sway occurred at frequencies equal to or below 0.375 Hz when motion at these frequencies was displayed. The extent of internal depth had no effect on the perception of changing orientation.

  4. Visual Storytelling

    OpenAIRE

    Ting-Hao; Huang; Ferraro, Francis; Mostafazadeh, Nasrin; Misra, Ishan; Agrawal, Aishwarya; Devlin, Jacob; Girshick, Ross; He, Xiaodong; Kohli, Pushmeet; Batra, Dhruv; Zitnick, C. Lawrence; Parikh, Devi; Vanderwende, Lucy; Galley, Michel

    2016-01-01

    We introduce the first dataset for sequential vision-to-language, and explore how this data may be used for the task of visual storytelling. The first release of this dataset, SIND v.1, includes 81,743 unique photos in 20,211 sequences, aligned to both descriptive (caption) and story language. We establish several strong baselines for the storytelling task, and motivate an automatic metric to benchmark progress. Modelling concrete description as well as figurative and social language, as prov...

  5. Flow visualization

    International Nuclear Information System (INIS)

    Weinstein, L.M.

    1991-01-01

    Flow visualization techniques are reviewed, with particular attention given to those applicable to liquid helium flows. Three techniques capable of obtaining qualitative and quantitative measurements of complex 3D flow fields are discussed including focusing schlieren, particle image volocimetry, and holocinematography (HCV). It is concluded that the HCV appears to be uniquely capable of obtaining full time-varying, 3D velocity field data, but is limited to the low speeds typical of liquid helium facilities. 8 refs

  6. History of falling and visual ability among independently living elderly in Sweden

    Directory of Open Access Journals (Sweden)

    Källstrand-Eriksson J

    2016-07-01

    Full Text Available Jeanette Källstrand-Eriksson,1 Cathrine Hildingh,1 Boel Bengtsson2 1School of Health and Welfare, Halmstad University, Halmstad, 2Department of Clinical Sciences in Malmö, Ophthalmology, Lund University, Malmö, Sweden Purpose: The aim of this study was to assess the performance-based visual ability among independently living elderly subjects and to investigate whether there was any association between visual ability and falls.Subjects and methods: A total of 298 randomly selected subjects aged 70–85 years were invited for an examination including monocular and binocular visual acuity (VA, contrast sensitivity (CS, stereoscopic vision, and monocular visual fields (VFs, which were integrated to estimate the binocular VFs. Type of lenses used in their habitual correction was noted.Results: Out of the 212 subjects who were examined, 38% reported at least one fall and 48% of these reported at least two falls during the last 2 years. Most subjects had normal results; 90% had normal binocular VA, 85% had normal binocular CS, and ~80% had positive stereopsis. Twenty-nine subjects had VF defects in the lower quadrants of the binocular VF, and 14 of these reported at least one fall. A significant association was seen between one fall or more and VA better eye, the odds ratio (OR was 2.26, P=0.013, and between recurrent falls and lack of stereoscopic vision, the OR was 3.23, P=0.002; no other functional test showed any significant association with recurrent falls. The ORs were 1.58 for worse binocular VA, 0.60 for worse binocular CS, and 0.71 for non-normal stereoscopic vision for at least one fall, but wide confidence intervals made it difficult to draw firm conclusions about any association. Bifocal or progressive spectacles were worn by 71% with no significant difference between fallers and nonfallers (P=0.078.Conclusion: Even though ~40% of the total sample had experienced one or more falls, the only visual function test significantly associated

  7. The relationship between nonverbal cognitive functions and hearing loss

    NARCIS (Netherlands)

    Zekveld, A.A.; Deijen, J.B.; Goverts, S.T.; Kramer, S.E.

    2007-01-01

    Purpose: This study investigated the relationship between hearing loss and memory and attention when nonverbal, visually presented cognitive tests are used. Method: Hearing loss (pure-tone audiometry) and IQ were measured in 30 participants with mild to severe hearing loss. Participants performed

  8. Benefit of bi-ocular visual stimulation for postural control in children with strabismus.

    Science.gov (United States)

    Gaertner, Chrystal; Creux, Charlotte; Espinasse-Berrod, Marie-Andrée; Orssaud, Christophe; Dufier, Jean-Louis; Kapoula, Zoï

    2013-01-01

    Vision is important for postural control as is shown by the Romberg quotient (RQ): with eyes closed, postural instability increases relative to eyes open (RQ = 2). Yet while fixating at far distance, postural stability is similar with eyes open and eyes closed (RQ = 1). Postural stability can be better with both eyes viewing than one eye, but such effect is not consistent among healthy subjects. The first goal of the study is to test the RQ as a function of distance for children with convergent versus divergent strabismus. The second goal is to test whether vision from two eyes relative to vision from one eye provides better postural stability. Thirteen children with divergent strabismus and eleven with convergent strabismus participated in this study. Posturtography was done with the Techno concept device. Experiment 1, four conditions: fixation at 40 cm and at 200 cm both with eyes open and eyes covered (evaluation of RQ). Experiment 2, six conditions: fixation at 40 cm and at 200 cm, with both eyes viewing or under monocular vision (dominant and non-dominant eye). For convergent strabismus, the groups mean value of RQ was 1.3 at near and 0.94 at far distance; for divergent, it was 1.06 at near and 1.68 at far. For all children, the surface of body sway was significantly smaller under both eyes viewing than monocular viewing (either eye). Increased RQ value at near for convergent and at far for divergent strabismus is attributed to the influence of the default strabismus angle and to better use of ocular motor signals. Vision with the two eyes improves postural control for both viewing distances and for both types of strabismus. Such benefit can be due to complementary mechanisms: larger visual field, better quality of fixation and vergence angle due to the use of visual inputs from both eyes.

  9. Benefit of bi-ocular visual stimulation for postural control in children with strabismus.

    Directory of Open Access Journals (Sweden)

    Chrystal Gaertner

    Full Text Available Vision is important for postural control as is shown by the Romberg quotient (RQ: with eyes closed, postural instability increases relative to eyes open (RQ = 2. Yet while fixating at far distance, postural stability is similar with eyes open and eyes closed (RQ = 1. Postural stability can be better with both eyes viewing than one eye, but such effect is not consistent among healthy subjects. The first goal of the study is to test the RQ as a function of distance for children with convergent versus divergent strabismus. The second goal is to test whether vision from two eyes relative to vision from one eye provides better postural stability. Thirteen children with divergent strabismus and eleven with convergent strabismus participated in this study. Posturtography was done with the Techno concept device. Experiment 1, four conditions: fixation at 40 cm and at 200 cm both with eyes open and eyes covered (evaluation of RQ. Experiment 2, six conditions: fixation at 40 cm and at 200 cm, with both eyes viewing or under monocular vision (dominant and non-dominant eye. For convergent strabismus, the groups mean value of RQ was 1.3 at near and 0.94 at far distance; for divergent, it was 1.06 at near and 1.68 at far. For all children, the surface of body sway was significantly smaller under both eyes viewing than monocular viewing (either eye. Increased RQ value at near for convergent and at far for divergent strabismus is attributed to the influence of the default strabismus angle and to better use of ocular motor signals. Vision with the two eyes improves postural control for both viewing distances and for both types of strabismus. Such benefit can be due to complementary mechanisms: larger visual field, better quality of fixation and vergence angle due to the use of visual inputs from both eyes.

  10. Visual performance after the implantation of a new trifocal intraocular lens

    Directory of Open Access Journals (Sweden)

    Vryghem JC

    2013-10-01

    Full Text Available Jérôme C Vryghem,1,2 Steven Heireman1,21Brussels Eye Doctors, Brussels, Belgium; 2Clinique Saint-Jean, Brussels, BelgiumPurpose: To evaluate the subjective and objective visual results after the implantation of a new trifocal diffractive intraocular lens.Methods: A new trifocal diffractive intraocular lens was designed combining two superimposed diffractive profiles: one with +1.75 diopters (D addition for intermediate vision and the other with +3.50 D addition for near vision. Fifty eyes of 25 patients that were operated on by one surgeon are included in this study. The uncorrected and best distance-corrected monocular and binocular, near, intermediate, and distance visual acuities, contrast sensitivity, and defocus curves were measured 6 months postoperatively. In addition to the standard clinical follow-up, a questionnaire evaluating individual satisfaction and quality of life was submitted to the patients.Results: The mean age of patients at the time of surgery was 70 ± 10 years. The mean uncorrected and corrected monocular distance visual acuity (VA were LogMAR 0.06 ± 0.10 and LogMAR 0.00 ± 0.08, respectively. The outcomes for the binocular uncorrected distance visual acuity were almost the same (LogMAR −0.04 ± 0.09. LogMAR −010 ± 0.15 and 0.02 ± 0.06 were measured for the binocular uncorrected intermediate and near VA, respectively. The distance-corrected visual acuity was maintained in mesopic conditions. The contrast sensitivity was similar to that obtained after implantation of a bifocal intraocular lens and did not decrease in mesopic conditions. The binocular defocus curve confirms good VA even in the intermediate distance range, with a moderate decrease of less than LogMAR 0.2 at −1.5 D, with respect to the best distance VA at 0 D defocus. Patient satisfaction was high. No discrepancy between the objective and subjective outcomes was evidenced.Conclusion: The introduction of a third focus in diffractive multifocal

  11. Visual dysfunction, neurodegenerative diseases, and aging.

    Science.gov (United States)

    Jackson, Gregory R; Owsley, Cynthia

    2003-08-01

    The four most common sight-threatening conditions in older adults in North America are cataract, ARM, glaucoma, and diabetic retinopathy. Even in their moderate stages, these conditions cause visual sensory impairments and reductions in health-related quality of life, including difficulties in daily tasks and psychosocial problems. Many older adults are free from these conditions, yet still experience a variety of visual perceptual problems resulting from aging-related changes in the optics of the eye and degeneration of the visual neural pathways. These problems consist of impairments in visual acuity, contrast sensitivity, color discrimination, temporal sensitivity, motion perception, peripheral visual field sensitivity, and visual processing speed. PD causes a progressive loss of dopaminergic cells predominantly in the retina and possibly in other areas of the visual system. This retinal dopamine deficiency produces selective spatial-temporal abnormalities in retinal ganglion cell function, probably arising from altered receptive field organization in the PD retina. The cortical degeneration characteristics of AD, including neurofibrillary tangles and neuritic plaques, also are present in the visual cortical areas, especially in the visual association areas. The most prominent electrophysiologic change in AD is a delay in the P2 component of the flash VEP. Deficits in higher-order visual abilities typically are compromised in AD, including problems with visual attention, perceiving structure from motion, visual memory, visual learning, reading, and object and face perception. There have been reports of a visual variant of AD in which these types of visual problems are the initial and most prominent signs of the disease. Visual sensory impairments (e.g., contrast sensitivity or achromatopsia) also have been reported but are believed more reflective of cortical disturbances than of AD-associated optic neuropathy.

  12. Visual complications following irradiation for pituitary adenomas and craniopharyngiomas

    International Nuclear Information System (INIS)

    Harris, J.R.; Levene, M.B.

    1976-01-01

    Of 55 patients with pituitary adenomas or craniopharyngiomas treated with irradiation, a retrospective study revealed that 5 sustained a visual loss compatible with radiation damage to the optic nerve. No patient who received less than 250 rads/day fractions showed such visual loss. Within the range of total dosages used in this series, total dose was not an important determinant of this complication. The time to occurrence of visual disturbance ranged from 5 to 34 months following therapy

  13. Suppression of metabolic activity caused by infantile strabismus and strabismic amblyopia in striate visual cortex of macaque monkeys.

    Science.gov (United States)

    Wong, Agnes M F; Burkhalter, Andreas; Tychsen, Lawrence

    2005-02-01

    Suppression is a major sensorial abnormality in humans and monkeys with infantile strabismus. We previously reported evidence of metabolic suppression in the visual cortex of strabismic macaques, using the mitochondrial enzyme cytochrome oxidase as an anatomic label. The purpose of this study was to further elucidate alterations in cortical metabolic activity, with or without amblyopia. Six macaque monkeys were used in the experiments (four strabismic and two control). Three of the strabismic monkeys had naturally occurring, infantile strabismus (two esotropic, one exotropic). The fourth strabismic monkey had infantile microesotropia induced by alternating monocular occlusion in the first months of life. Ocular motor behaviors and visual acuity were tested after infancy in each animal, and development of stereopsis was recorded during infancy in one strabismic and one control monkey. Ocular dominance columns (ODCs) of the striate visual cortex (area V1) were labeled using cytochrome oxidase (CO) histochemistry alone, or CO in conjunction with an anterograde tracer ([H 3 ]proline or WGA-HRP) injected into one eye. Each of the strabismic monkeys showed inequalities of metabolic activity in ODCs of opposite ocularity, visible as rows of lighter CO staining, corresponding to ODCs of lower metabolic activity, alternating with rows of darker CO staining, corresponding to ODCs of higher metabolic activity. In monkeys who had infantile strabismus and unilateral amblyopia, lower metabolic activity was found in (suppressed) ODCs driven by the nondominant eye in each hemisphere. In monkeys who had infantile esotropia and alternating fixation (no amblyopia), metabolic activity was lower in ODCs driven by the ipsilateral eye in each hemisphere. The suppression included a monocular core zone at the center of ODCs and binocular border zones at the boundaries of ODCs. This suppression was not evident in the monocular lamina of the LGN, indicating an intracortical rather than

  14. Attentional load modulates responses of human primary visual cortex to invisible stimuli.

    Science.gov (United States)

    Bahrami, Bahador; Lavie, Nilli; Rees, Geraint

    2007-03-20

    Visual neuroscience has long sought to determine the extent to which stimulus-evoked activity in visual cortex depends on attention and awareness. Some influential theories of consciousness maintain that the allocation of attention is restricted to conscious representations [1, 2]. However, in the load theory of attention [3], competition between task-relevant and task-irrelevant stimuli for limited-capacity attention does not depend on conscious perception of the irrelevant stimuli. The critical test is whether the level of attentional load in a relevant task would determine unconscious neural processing of invisible stimuli. Human participants were scanned with high-field fMRI while they performed a foveal task of low or high attentional load. Irrelevant, invisible monocular stimuli were simultaneously presented peripherally and were continuously suppressed by a flashing mask in the other eye [4]. Attentional load in the foveal task strongly modulated retinotopic activity evoked in primary visual cortex (V1) by the invisible stimuli. Contrary to traditional views [1, 2, 5, 6], we found that availability of attentional capacity determines neural representations related to unconscious processing of continuously suppressed stimuli in human primary visual cortex. Spillover of attention to cortical representations of invisible stimuli (under low load) cannot be a sufficient condition for their awareness.

  15. Microsurgical clipping of ophthalmic artery aneurysms: surgical results and visual outcomes with 208 aneurysms.

    Science.gov (United States)

    Kamide, Tomoya; Tabani, Halima; Safaee, Michael M; Burkhardt, Jan-Karl; Lawton, Michael T

    2018-01-26

    OBJECTIVE While most paraclinoid aneurysms can be clipped with excellent results, new postoperative visual deficits are a concern. New technology, including flow diverters, has increased the popularity of endovascular therapy. However, endovascular treatment of paraclinoid aneurysms is not without procedural risks, is associated with higher rates of incomplete aneurysm occlusion and recurrence, and may not address optic nerve compression symptoms that surgical debulking can. The increasing endovascular management of paraclinoid aneurysms should be justified by comparisons to surgical benchmarks. The authors, therefore, undertook this study to define patient, visual, and aneurysm outcomes in the most common type of paraclinoid aneurysm: ophthalmic artery (OphA) aneurysms. METHODS Results from microsurgical clipping of 208 OphA aneurysms in 198 patients were retrospectively reviewed. Patient demographics, aneurysm morphology (size, calcification, etc.), clinical characteristics, and patient outcomes were recorded and analyzed. RESULTS Despite 20% of these aneurysms being large or giant in size, complete aneurysm occlusion was accomplished in 91% of 208 cases, with OphA patency preserved in 99.5%. The aneurysm recurrence rate was 3.1% and the retreatment rate was 0%. Good outcomes (modified Rankin Scale score 0-2) were observed in 96.2% of patients overall and in all 156 patients with unruptured aneurysms. New visual field defects (hemianopsia or quadrantanopsia) were observed in 8 patients (3.8%), decreased visual acuity in 5 (2.4%), and monocular blindness in 9 (4.3%). Vision improved in 9 (52.9%) of the 17 patients with preoperative visual deficits. CONCLUSIONS The most important risk associated with clipping OphA aneurysms is a new visual deficit. Meticulous microsurgical technique is necessary during anterior clinoidectomy, aneurysm dissection, and clip application to optimize visual outcomes, and aggressive medical management postoperatively might potentially

  16. Visualization rhetoric: framing effects in narrative visualization.

    Science.gov (United States)

    Hullman, Jessica; Diakopoulos, Nicholas

    2011-12-01

    Narrative visualizations combine conventions of communicative and exploratory information visualization to convey an intended story. We demonstrate visualization rhetoric as an analytical framework for understanding how design techniques that prioritize particular interpretations in visualizations that "tell a story" can significantly affect end-user interpretation. We draw a parallel between narrative visualization interpretation and evidence from framing studies in political messaging, decision-making, and literary studies. Devices for understanding the rhetorical nature of narrative information visualizations are presented, informed by the rigorous application of concepts from critical theory, semiotics, journalism, and political theory. We draw attention to how design tactics represent additions or omissions of information at various levels-the data, visual representation, textual annotations, and interactivity-and how visualizations denote and connote phenomena with reference to unstated viewing conventions and codes. Classes of rhetorical techniques identified via a systematic analysis of recent narrative visualizations are presented, and characterized according to their rhetorical contribution to the visualization. We describe how designers and researchers can benefit from the potentially positive aspects of visualization rhetoric in designing engaging, layered narrative visualizations and how our framework can shed light on how a visualization design prioritizes specific interpretations. We identify areas where future inquiry into visualization rhetoric can improve understanding of visualization interpretation. © 2011 IEEE

  17. Understanding Grief and Loss

    Science.gov (United States)

    ... the process of adapting to life after a loss. It is influenced by each person’s society, culture, and religion. Bereavement is the state of having experienced a loss. Common grief reactions Reactions to loss are called ...

  18. Economic Loan Loss Provision and Expected Loss

    Directory of Open Access Journals (Sweden)

    Stefan Hlawatsch

    2010-10-01

    Full Text Available The intention of a loan loss provision is the anticipation of the loan's expected losses by adjusting the book value of the loan. Furthermore, this loan loss provision has to be compared to the expected loss according to Basel II and, in the case of a difference, liable equity has to be adjusted. This however assumes that the loan loss provision and the expected loss are based on a similar economic rationale, which is only valid conditionally in current loan loss provisioning methods according to IFRS. Therefore, differences between loan loss provisions and expected losses should only result from different approaches regarding the parameter estimation within each model and not due to different assumptions regarding the outcome of the model. The provisioning and accounting model developed in this paper overcomes the before-mentioned shortcomings and is consistent with an economic rationale of expected losses. Additionally, this model is based on a close-to-market valuation of the loan that is in favor of the basic idea of IFRS. Suggestions for changes in current accounting and capital requirement rules are provided.

  19. [Are Visual Field Defects Reversible? - Visual Rehabilitation with Brains].

    Science.gov (United States)

    Sabel, B A

    2017-02-01

    Visual field defects are considered irreversible because the retina and optic nerve do not regenerate. Nevertheless, there is some potential for recovery of the visual fields. This can be accomplished by the brain, which analyses and interprets visual information and is able to amplify residual signals through neuroplasticity. Neuroplasticity refers to the ability of the brain to change its own functional architecture by modulating synaptic efficacy. This is actually the neurobiological basis of normal learning. Plasticity is maintained throughout life and can be induced by repetitively stimulating (training) brain circuits. The question now arises as to how plasticity can be utilised to activate residual vision for the treatment of visual field loss. Just as in neurorehabilitation, visual field defects can be modulated by post-lesion plasticity to improve vision in glaucoma, diabetic retinopathy or optic neuropathy. Because almost all patients have some residual vision, the goal is to strengthen residual capacities by enhancing synaptic efficacy. New treatment paradigms have been tested in clinical studies, including vision restoration training and non-invasive alternating current stimulation. While vision training is a behavioural task to selectively stimulate "relative defects" with daily vision exercises for the duration of 6 months, treatment with alternating current stimulation (30 min. daily for 10 days) activates and synchronises the entire retina and brain. Though full restoration of vision is not possible, such treatments improve vision, both subjectively and objectively. This includes visual field enlargements, improved acuity and reaction time, improved orientation and vision related quality of life. About 70 % of the patients respond to the therapies and there are no serious adverse events. Physiological studies of the effect of alternating current stimulation using EEG and fMRI reveal massive local and global changes in the brain. These include

  20. Pattern reversal visual evoked potentials in migraine subjects without aura

    Directory of Open Access Journals (Sweden)

    Pedro F. Moreira Filho

    1994-12-01

    Full Text Available Twenty seven patients with migraine without aura were investigated. The age was between 12 and 54 years; 5 were men and 22 women. The diagnosis of migraine was made according to the classification proposed by the International Headache Society. The method of visual evoked potential was performed with pattern reversal (VEP-PR, with monocular stimulation. The stimulation was performed with pattern reversal with 4x4 cm black and white and red and green squared screen placed 1 meter from the nasion at stimulus frequency 1/s; 128 individual trials were analysed. The VEP-PR with black/white and red/green study showed a significant increase of value of the P-100 latency in 10 migraine patients. In 8 cases the LP100 in VEP-PR black/white was normal but in VEP-PR red/green the LP100 showed increase. Specifically in 1 of our cases, LP100 were normal in VEP-PR black/white but in the red/green there were no reproductice waves. On basis of these observations we consider that the method of VEP-PR is an useful instrument for investigation of migraine patients without aura.

  1. Distributed consensus with visual perception in multi-robot systems

    CERN Document Server

    Montijano, Eduardo

    2015-01-01

    This monograph introduces novel responses to the different problems that arise when multiple robots need to execute a task in cooperation, each robot in the team having a monocular camera as its primary input sensor. Its central proposition is that a consistent perception of the world is crucial for the good development of any multi-robot application. The text focuses on the high-level problem of cooperative perception by a multi-robot system: the idea that, depending on what each robot sees and its current situation, it will need to communicate these things to its fellows whenever possible to share what it has found and keep updated by them in its turn. However, in any realistic scenario, distributed solutions to this problem are not trivial and need to be addressed from as many angles as possible. Distributed Consensus with Visual Perception in Multi-Robot Systems covers a variety of related topics such as: ·         distributed consensus algorithms; ·         data association and robustne...

  2. Accuracy of Blood Loss Measurement during Cesarean Delivery

    OpenAIRE

    Doctorvaladan, Sahar V.; Jelks, Andrea T.; Hsieh, Eric W.; Thurer, Robert L.; Zakowski, Mark I.; Lagrew, David C.

    2017-01-01

    Objective?This study aims to compare the accuracy of visual, quantitative gravimetric, and colorimetric methods used to determine blood loss during cesarean delivery procedures employing a hemoglobin extraction assay as the reference standard. Study Design?In 50 patients having cesarean deliveries blood loss determined by assays of hemoglobin content on surgical sponges and in suction canisters was compared with obstetricians' visual estimates, a quantitative gravimetric method, and the blood...

  3. Visual literacy in HCI

    NARCIS (Netherlands)

    Overton, K.; Sosa-Tzec, O.; Smith, N.; Blevis, E.; Odom, W.; Hauser, S.; Wakkary, R.L.

    2016-01-01

    The goal of this workshop is to develop ideas about and expand a research agenda for visual literacy in HCI. By visual literacy, we mean the competency (i) to understand visual materials, (ii) to create visuals materials, and (iii) to think visually [2]. There are three primary motivations for this

  4. 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.

  5. Using virtual reality to test the regularity priors used by the human visual system

    Science.gov (United States)

    Palmer, Eric; Kwon, TaeKyu; Pizlo, Zygmunt

    2017-09-01

    Virtual reality applications provide an opportunity to test human vision in well-controlled scenarios that would be difficult to generate in real physical spaces. This paper presents a study intended to evaluate the importance of the regularity priors used by the human visual system. Using a CAVE simulation, subjects viewed virtual objects in a variety of experimental manipulations. In the first experiment, the subject was asked to count the objects in a scene that was viewed either right-side-up or upside-down for 4 seconds. The subject counted more accurately in the right-side-up condition regardless of the presence of binocular disparity or color. In the second experiment, the subject was asked to reconstruct the scene from a different viewpoint. Reconstructions were accurate, but the position and orientation error was twice as high when the scene was rotated by 45°, compared to 22.5°. Similarly to the first experiment, there was little difference between monocular and binocular viewing. In the third experiment, the subject was asked to adjust the position of one object to match the depth extent to the frontal extent among three objects. Performance was best with symmetrical objects and became poorer with asymmetrical objects and poorest with only small circular markers on the floor. Finally, in the fourth experiment, we demonstrated reliable performance in monocular and binocular recovery of 3D shapes of objects standing naturally on the simulated horizontal floor. Based on these results, we conclude that gravity, horizontal ground, and symmetry priors play an important role in veridical perception of scenes.

  6. Multifocal visual evoked responses to dichoptic stimulation using virtual reality goggles: Multifocal VER to dichoptic stimulation.

    Science.gov (United States)

    Arvind, Hemamalini; Klistorner, Alexander; Graham, Stuart L; Grigg, John R

    2006-05-01

    Multifocal visual evoked potentials (mfVEPs) have demonstrated good diagnostic capabilities in glaucoma and optic neuritis. This study aimed at evaluating the possibility of simultaneously recording mfVEP for both eyes with dichoptic stimulation using virtual reality goggles and also to determine the stimulus characteristics that yield maximum amplitude. ten healthy volunteers were recruited and temporally sparse pattern pulse stimuli were presented dichoptically using virtual reality goggles. Experiment 1 involved recording responses to dichoptically presented checkerboard stimuli and also confirming true topographic representation by switching off specific segments. Experiment 2 involved monocular stimulation and comparison of amplitude with Experiment 1. In Experiment 3, orthogonally oriented gratings were dichoptically presented. Experiment 4 involved dichoptic presentation of checkerboard stimuli at different levels of sparseness (5.0 times/s, 2.5 times/s, 1.66 times/s and 1.25 times/s), where stimulation of corresponding segments of two eyes were separated by 16.7, 66.7,116.7 & 166.7 ms respectively. Experiment 1 demonstrated good traces in all regions and confirmed topographic representation. However, there was suppression of amplitude of responses to dichoptic stimulation by 17.9+/-5.4% compared to monocular stimulation. Experiment 3 demonstrated similar suppression between orthogonal and checkerboard stimuli (p = 0.08). Experiment 4 demonstrated maximum amplitude and least suppression (4.8%) with stimulation at 1.25 times/s with 166.7 ms separation between eyes. It is possible to record mfVEP for both eyes during dichoptic stimulation using virtual reality goggles, which present binocular simultaneous patterns driven by independent sequences. Interocular suppression can be almost eliminated by using a temporally sparse stimulus of 1.25 times/s with a separation of 166.7 ms between stimulation of corresponding segments of the two eyes.

  7. Hair loss in women.

    Science.gov (United States)

    Harfmann, Katya L; Bechtel, Mark A

    2015-03-01

    Hair loss is a common cause of morbidity for many women. As a key member of the woman's health care team, the obstetrician/gynecologist may be the first person to evaluate the complaint of hair loss. Common types of nonscarring hair loss, including female pattern hair loss and telogen effluvium, may be diagnosed and managed by the obstetrician/gynecologist. A systematic approach to diagnosis and management of these common forms of hair loss is presented.

  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 (R 2 = 0.50; p function (R 2 = 0.61, p function in multiple regression analyses. Superior and inferior visual field areas related similarly to mobility function (R 2 = 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. Vitreous loss-causes, associations, and outcomes: Eight-year analysis in Melaka Hospital

    Directory of Open Access Journals (Sweden)

    Thanigasalam Thevi

    2018-01-01

    CONCLUSION: Vitreous loss occurred in almost all types of cataract surgeries, especially by junior surgeons, among those aged <40 years and significantly caused poor visual outcome compared to other complications. Pseudoexfoliation had higher occurrence of vitreous loss. Vitreous loss patients had impaired/poor visual outcome due to preexisting comorbidity and astigmatism. Patients at risk and junior surgeons should be closely monitored to improve outcomes. Further studies need to be done to see why and when the vitreous loss occurred.

  10. Visual Memories Bypass Normalization.

    Science.gov (United States)

    Bloem, Ilona M; Watanabe, Yurika L; Kibbe, Melissa M; Ling, Sam

    2018-05-01

    How distinct are visual memory representations from visual perception? Although evidence suggests that briefly remembered stimuli are represented within early visual cortices, the degree to which these memory traces resemble true visual representations remains something of a mystery. Here, we tested whether both visual memory and perception succumb to a seemingly ubiquitous neural computation: normalization. Observers were asked to remember the contrast of visual stimuli, which were pitted against each other to promote normalization either in perception or in visual memory. Our results revealed robust normalization between visual representations in perception, yet no signature of normalization occurring between working memory stores-neither between representations in memory nor between memory representations and visual inputs. These results provide unique insight into the nature of visual memory representations, illustrating that visual memory representations follow a different set of computational rules, bypassing normalization, a canonical visual computation.

  11. Learning Visualizations by Analogy: Promoting Visual Literacy through Visualization Morphing.

    Science.gov (United States)

    Ruchikachorn, Puripant; Mueller, Klaus

    2015-09-01

    We propose the concept of teaching (and learning) unfamiliar visualizations by analogy, that is, demonstrating an unfamiliar visualization method by linking it to another more familiar one, where the in-betweens are designed to bridge the gap of these two visualizations and explain the difference in a gradual manner. As opposed to a textual description, our morphing explains an unfamiliar visualization through purely visual means. We demonstrate our idea by ways of four visualization pair examples: data table and parallel coordinates, scatterplot matrix and hyperbox, linear chart and spiral chart, and hierarchical pie chart and treemap. The analogy is commutative i.e. any member of the pair can be the unfamiliar visualization. A series of studies showed that this new paradigm can be an effective teaching tool. The participants could understand the unfamiliar visualization methods in all of the four pairs either fully or at least significantly better after they observed or interacted with the transitions from the familiar counterpart. The four examples suggest how helpful visualization pairings be identified and they will hopefully inspire other visualization morphings and associated transition strategies to be identified.

  12. SEISMIC RISK CARTOGRAPHIC VISUALIZATION FOR CRISIS MANAGEMENT

    Directory of Open Access Journals (Sweden)

    Nina I. Frolova

    2014-01-01

    Full Text Available Earthquake loss estimations before future events and following strong earthquakesin emergency mode and their corresponding visualization are extremely important for properdecision on preventive measures and effective response in order to save lives and properties. The paper addresses the methodological issues of seismic risk and vulnerability assessment, mapping with GIS technology application. Requirements for simulation models,databases used at different levels, as well as ways of visualizations oriented for EmergencyManagement Agencies, as well federal and local authorities are discussed. Examples ofmapping at the different levels: global, country, region and urban one are given and theinfluence of input data uncertainties on the reliability of loss computations is analyzed.

  13. Line-based monocular graph SLAM algorithm%基于图优化的单目线特征SLAM算法

    Institute of Scientific and Technical Information of China (English)

    董蕊芳; 柳长安; 杨国田; 程瑞营

    2017-01-01

    A new line based 6-DOF monocular algorithm for using graph simultaneous localization and mapping(SLAM) algoritm was proposed.First,the straight line were applied as a feature instead of points,due to a map consisting of a sparse set of 3D points is unable to describe the structure of the surrounding world.Secondly,most of previous line-based SLAM algorithms were focused on filtering-based solutions suffering from the inconsistent when applied to the inherently non-linear SLAM problem,in contrast,the graph-based solution was used to improve the accuracy of the localization and the consistency of mapping.Thirdly,a special line representation was exploited for combining the Plücker coordinates with the Cayley representation.The Plücker coordinates were used for the 3D line projection function,and the Cayley representation helps to update the line parameters during the non-linear optimization process.Finally,the simulation experiment shows that the proposed algorithm outperforms odometry and EKF-based SLAM in terms of the pose estimation,while the sum of the squared errors (SSE) and root-mean-square error (RMSE) of proposed method are 2.5% and 10.5% of odometry,and 22.4% and 33% of EKF-based SLAM.The reprojection error is only 45.5 pixels.The real image experiment shows that the proposed algorithm obtains only 958 cm2 and 3.941 3 cm the SSE and RMSE of pose estimation.Therefore,it can be concluded that the proposed algorithm is effective and accuracy.%提出了基于图优化的单目线特征同时定位和地图构建(SLAM)的方法.首先,针对主流视觉SLAM算法因采用点作为特征而导致构建的点云地图稀疏、难以准确表达环境结构信息等缺点,采用直线作为特征来构建地图.然后,根据现有线特征的SLAM算法都是基于滤波器的SLAM框架、存在线性化及更新效率的问题,采用基于图优化的SLAM解决方案以提高定位精度及地图构建的一致性和准确性.将线特征的Plücker坐

  14. Stimulus-dependent modulation of spontaneous low-frequency oscillations in the rat visual cortex.

    Science.gov (United States)

    Huang, Liangming; Liu, Yadong; Gui, Jianjun; Li, Ming; Hu, Dewen

    2014-08-06

    Research on spontaneous low-frequency oscillations is important to reveal underlying regulatory mechanisms in the brain. The mechanism for the stimulus modulation of low-frequency oscillations is not known. Here, we used the intrinsic optical imaging technique to examine stimulus-modulated low-frequency oscillation signals in the rat visual cortex. The stimulation was presented monocularly as a flashing light with different frequencies and intensities. The phases of low-frequency oscillations in different regions tended to be synchronized and the rhythms typically accelerated within a 30-s period after stimulation. These phenomena were confined to visual stimuli with specific flashing frequencies (12.5-17.5 Hz) and intensities (5-10 mA). The acceleration and synchronization induced by the flashing frequency were more marked than those induced by the intensity. These results show that spontaneous low-frequency oscillations can be modulated by parameter-dependent flashing lights and indicate the potential utility of the visual stimulus paradigm in exploring the origin and function of low-frequency oscillations.

  15. Within- and cross-modal distance information disambiguate visual size-change perception.

    Directory of Open Access Journals (Sweden)

    Peter W Battaglia

    2010-03-01

    Full Text Available Perception is fundamentally underconstrained because different combinations of object properties can generate the same sensory information. To disambiguate sensory information into estimates of scene properties, our brains incorporate prior knowledge and additional "auxiliary" (i.e., not directly relevant to desired scene property sensory information to constrain perceptual interpretations. For example, knowing the distance to an object helps in perceiving its size. The literature contains few demonstrations of the use of prior knowledge and auxiliary information in combined visual and haptic disambiguation and almost no examination of haptic disambiguation of vision beyond "bistable" stimuli. Previous studies have reported humans integrate multiple unambiguous sensations to perceive single, continuous object properties, like size or position. Here we test whether humans use visual and haptic information, individually and jointly, to disambiguate size from distance. We presented participants with a ball moving in depth with a changing diameter. Because no unambiguous distance information is available under monocular viewing, participants rely on prior assumptions about the ball's distance to disambiguate their -size percept. Presenting auxiliary binocular and/or haptic distance information augments participants' prior distance assumptions and improves their size judgment accuracy-though binocular cues were trusted more than haptic. Our results suggest both visual and haptic distance information disambiguate size perception, and we interpret these results in the context of probabilistic perceptual reasoning.

  16. Reorganization of Visual Callosal Connections Following Alterations of Retinal Input and Brain Damage

    Science.gov (United States)

    Restani, Laura; Caleo, Matteo

    2016-01-01

    Vision is a very important sensory modality in humans. Visual disorders are numerous and arising from diverse and complex causes. Deficits in visual function are highly disabling from a social point of view and in addition cause a considerable economic burden. For all these reasons there is an intense effort by the scientific community to gather knowledge on visual deficit mechanisms and to find possible new strategies for recovery and treatment. In this review, we focus on an important and sometimes neglected player of the visual function, the corpus callosum (CC). The CC is the major white matter structure in the brain and is involved in information processing between the two hemispheres. In particular, visual callosal connections interconnect homologous areas of visual cortices, binding together the two halves of the visual field. This interhemispheric communication plays a significant role in visual cortical output. Here, we will first review the essential literature on the physiology of the callosal connections in normal vision. The available data support the view that the callosum contributes to both excitation and inhibition to the target hemisphere, with a dynamic adaptation to the strength of the incoming visual input. Next, we will focus on data showing how callosal connections may sense visual alterations and respond to the classical paradigm for the study of visual plasticity, i.e., monocular deprivation (MD). This is a prototypical example of a model for the study of callosal plasticity in pathological conditions (e.g., strabismus and amblyopia) characterized by unbalanced input from the two eyes. We will also discuss the findings of callosal alterations in blind subjects. Noteworthy, we will discuss data showing that inter-hemispheric transfer mediates recovery of visual responsiveness following cortical damage. Finally, we will provide an overview of how callosal projections dysfunction could contribute to pathologies such as neglect and occipital

  17. PREGNANCY LOSS IN MARES

    Directory of Open Access Journals (Sweden)

    Tibary A

    2015-12-01

    Full Text Available Pregnancy loss is an important aspect of equine practice due to the economic and emotional loss that it engenders. Pregnancy loss is often divided in two categories: early pregnancy loss (EPL or embryonic death (ED (first 42 days and fetal losses (after 42 days. Diagnosis of the causes of pregnancy loss is often very challenging. Many of the causes of EPL remain poorly documented but studies on embryo development and embryo-uterine interaction have been able to shed some light on predisposing factors. Fetal losses or abortions are dominated by infectious causes and particularly bacterial placentitis. Detailed reviews of pregnancy loss were recently published by the authors (Tibary et al., 2012; Tibary and Pearson, 2012; Tibary et al., 2014. The objective of this paper is to provide an overview of the epidemiology, etiology, diagnosis and prevention of pregnancy loss in the mare.

  18. Armstrong Laboratory Space Visual Function Tester Program

    Science.gov (United States)

    Oneal, Melvin R.; Task, H. Lee; Gleason, Gerald A.

    1992-01-01

    Viewgraphs on space visual function tester program are presented. Many astronauts and cosmonauts have commented on apparent changes in their vision while on-orbit. Comments have included descriptions of earth features and objects that would suggest enhanced distance visual acuity. In contrast, some cosmonaut observations suggest a slight loss in their object discrimination during initial space flight. Astronauts have also mentioned a decreased near vision capability that did not recover to normal until return to earth. Duntley space vision experiment, USSR space vision experiments, and visual function testers are described.

  19. Case Report: Successful treatment of bilateral visual loss caused by ...

    African Journals Online (AJOL)

    Investigations were performed for meningitis (including bacterial, cryptococcal, tuberculous and syphilitic types), auto-immune diseases, toxoplasma, rubella, cytomegalovirus, viral hepatitis, HTLV-1/2, HIV-1/2 and syphilis. The only positive result was a reactive HIV enzymelinked immunosorbent assay. The CD4 count was ...

  20. Corona helps curb losses

    Energy Technology Data Exchange (ETDEWEB)

    Laasonen, M.; Lahtinen, M.; Lustre, L.

    1996-11-01

    The greatest power losses in electricity transmission arise through a phenomenon called load losses. Corona losses caused by the surface discharge of electricity also constitute a considerable cost item. IVS, the nationwide network company, is investigating corona- induced losses, and has also commissioned similar research from IVO International, the Technical Research Centre of Finland (VTT) and from Tampere University of Technology. The research work strives to gain more in-depth knowledge on the phenomenon of frosting and its impact on corona losses. The correct prediction of frost helps reduce corona losses, while also cutting costs considerably. (orig.)

  1. Interhemispheric Transfer Time Asymmetry of Visual Information Depends on Eye Dominance: An Electrophysiological Study.

    Science.gov (United States)

    Chaumillon, Romain; Blouin, Jean; Guillaume, Alain

    2018-01-01

    The interhemispheric transfer of information is a fundamental process in the human brain. When a visual stimulus appears eccentrically in one visual-hemifield, it will first activate the contralateral hemisphere but also the ipsilateral one with a slight delay due to the interhemispheric transfer. This interhemispheric transfer of visual information is believed to be faster from the right to the left hemisphere in right-handers. Such an asymmetry is considered as a relevant fact in the context of the lateralization of the human brain. We show here using current source density (CSD) analyses of visually evoked potential (VEP) that, in right-handers and, to a lesser extent in left-handers, this asymmetry is in fact dependent on the sighting eye dominance, the tendency we have to prefer one eye for monocular tasks. Indeed, in right-handers, a faster interhemispheric transfer of visual information from the right to left hemisphere was observed only in participants with a right dominant eye (DE). Right-handers with a left DE showed the opposite pattern, with a faster transfer from the left to the right hemisphere. In left-handers, albeit a smaller number of participants has been tested and hence confirmation is required, only those with a right DE showed an asymmetrical interhemispheric transfer with a faster transfer from the right to the left hemisphere. As a whole these results demonstrate that eye dominance is a fundamental determinant of asymmetries in interhemispheric transfer of visual information and suggest that it is an important factor of brain lateralization.

  2. Interhemispheric Transfer Time Asymmetry of Visual Information Depends on Eye Dominance: An Electrophysiological Study

    Directory of Open Access Journals (Sweden)

    Romain Chaumillon

    2018-02-01

    Full Text Available The interhemispheric transfer of information is a fundamental process in the human brain. When a visual stimulus appears eccentrically in one visual-hemifield, it will first activate the contralateral hemisphere but also the ipsilateral one with a slight delay due to the interhemispheric transfer. This interhemispheric transfer of visual information is believed to be faster from the right to the left hemisphere in right-handers. Such an asymmetry is considered as a relevant fact in the context of the lateralization of the human brain. We show here using current source density (CSD analyses of visually evoked potential (VEP that, in right-handers and, to a lesser extent in left-handers, this asymmetry is in fact dependent on the sighting eye dominance, the tendency we have to prefer one eye for monocular tasks. Indeed, in right-handers, a faster interhemispheric transfer of visual information from the right to left hemisphere was observed only in participants with a right dominant eye (DE. Right-handers with a left DE showed the opposite pattern, with a faster transfer from the left to the right hemisphere. In left-handers, albeit a smaller number of participants has been tested and hence confirmation is required, only those with a right DE showed an asymmetrical interhemispheric transfer with a faster transfer from the right to the left hemisphere. As a whole these results demonstrate that eye dominance is a fundamental determinant of asymmetries in interhemispheric transfer of visual information and suggest that it is an important factor of brain lateralization.

  3. Interhemispheric Transfer Time Asymmetry of Visual Information Depends on Eye Dominance: An Electrophysiological Study

    Science.gov (United States)

    Chaumillon, Romain; Blouin, Jean; Guillaume, Alain

    2018-01-01

    The interhemispheric transfer of information is a fundamental process in the human brain. When a visual stimulus appears eccentrically in one visual-hemifield, it will first activate the contralateral hemisphere but also the ipsilateral one with a slight delay due to the interhemispheric transfer. This interhemispheric transfer of visual information is believed to be faster from the right to the left hemisphere in right-handers. Such an asymmetry is considered as a relevant fact in the context of the lateralization of the human brain. We show here using current source density (CSD) analyses of visually evoked potential (VEP) that, in right-handers and, to a lesser extent in left-handers, this asymmetry is in fact dependent on the sighting eye dominance, the tendency we have to prefer one eye for monocular tasks. Indeed, in right-handers, a faster interhemispheric transfer of visual information from the right to left hemisphere was observed only in participants with a right dominant eye (DE). Right-handers with a left DE showed the opposite pattern, with a faster transfer from the left to the right hemisphere. In left-handers, albeit a smaller number of participants has been tested and hence confirmation is required, only those with a right DE showed an asymmetrical interhemispheric transfer with a faster transfer from the right to the left hemisphere. As a whole these results demonstrate that eye dominance is a fundamental determinant of asymmetries in interhemispheric transfer of visual information and suggest that it is an important factor of brain lateralization. PMID:29515351

  4. Hearing loss in Usher syndrome type II is nonprogressive.

    Science.gov (United States)

    Reisser, Christoph F V; Kimberling, William J; Otterstedde, Christian R

    2002-12-01

    Usher syndrome is an autosomal recessive disorder characterized by sensorineural hearing loss and progressive visual loss secondary to retinitis pigmentosa. In the literature, a possible progression of the moderate to severe hearing loss in Usher syndrome type II (Usher II) is controversial. We studied the development of the hearing loss of 125 patients with a clinical diagnosis of Usher syndrome type II intraindividually and interindividually by repeatedly performing complete audiological and neuro-otologic examinations. Our data show a very characteristic slope of the hearing curve in all Usher II patients and no clinically relevant progression of the hearing loss over up to 17 years. The subjective impression of a deterioration of the communicative abilities of Usher II patients must therefore be attributed to the progressive visual loss. The patients should be reassured that changes in their hearing abilities are unlikely and should be provided with optimally fitted modern hearing aids.

  5. Telogen Effluvium Hair Loss

    Science.gov (United States)

    ... Category: Share: Yes No, Keep Private Telogen Effluvium Hair Loss Share | It is normal to lose up to ... months after the "shock". This sudden increase in hair loss, usually described as the hair coming out in ...

  6. Recurrent pregnancy loss

    DEFF Research Database (Denmark)

    Egerup, P; Kolte, A M; Larsen, E C

    2016-01-01

    STUDY QUESTION: Is there a different prognostic impact for consecutive and non-consecutive early pregnancy losses in women with secondary recurrent pregnancy loss (RPL)? SUMMARY ANSWER: Only consecutive early pregnancy losses after the last birth have a statistically significant negative prognostic...... impact in women with secondary RPL. WHAT IS KNOWN ALREADY: The risk of a new pregnancy loss increases with the number of previous pregnancy losses in patients with RPL. Second trimester losses seem to exhibit a stronger negative impact than early losses. It is unknown whether the sequence of pregnancy...... losses plays a role for the prognosis in patients with a prior birth. STUDY DESIGN, SIZE, DURATION: This retrospective cohort study of pregnancy outcome in patients with unexplained secondary RPL included in three previously published, Danish double-blinded placebo-controlled trials of intravenous...

  7. Genes and Hearing Loss

    Science.gov (United States)

    ... ENTCareers Marketplace Find an ENT Doctor Near You Genes and Hearing Loss Genes and Hearing Loss Patient ... mutation may only have dystopia canthorum. How Do Genes Work? Genes are a road map for the ...

  8. Menopause and Bone Loss

    Science.gov (United States)

    Fact Sheet & Menopause Bone Loss How are bone loss and menopause related? Throughout life your body keeps a balance between the ... lose bone faster than it can be replaced. Menopause—the time when menstrual periods end, which usually ...

  9. OI Issues: Hearing Loss

    Science.gov (United States)

    ... signals normally to the brain. In addition, hearing losses are classified according to the degree of severity: • Mild, • Moderate, • Severe, • Profound. Hearing losses are also classified according to the sound frequency ...

  10. Early Pregnancy Loss

    Science.gov (United States)

    ... go on to have successful pregnancies. Repeated pregnancy losses are rare. Testing and evaluation can be done ... find a cause if you have several pregnancy losses. Even if no cause is found, most couples ...

  11. Occupational hearing loss

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/001048.htm Occupational hearing loss To use the sharing features on this page, please enable JavaScript. Occupational hearing loss is damage to the inner ear from noise ...

  12. Pregnancy Loss and Miscarriage

    Science.gov (United States)

    ... D linked to miscarriage among women with prior pregnancy loss Release: Anti-HIV drug combination does not increase preterm birth risk, study suggests Release: Elevated blood pressure before pregnancy may increase chance of pregnancy loss All related ...

  13. Coping with Memory Loss

    Science.gov (United States)

    ... Consumers Home For Consumers Consumer Updates Coping With Memory Loss Share Tweet Linkedin Pin it More sharing ... be evaluated by a health professional. What Causes Memory Loss? Anything that affects cognition—the process of ...

  14. Weight Loss Surgery

    Science.gov (United States)

    Weight loss surgery helps people with extreme obesity to lose weight. It may be an option if you cannot lose weight ... obesity. There are different types of weight loss surgery. They often limit the amount of food you ...

  15. Myopic loss aversion revisited

    OpenAIRE

    Blavatskyy, Pavlo; Pogrebna, Ganna

    2009-01-01

    In this paper we reexamine several experimental papers on myopic loss aversion by analyzing individual rather than aggregate choice patterns. We find that the behavior of the majority of subjects is inconsistent with the hypothesis of myopic loss aversion.

  16. REORGANIZATION OF VISUAL CALLOSAL CONNECTIONS FOLLOWING ALTERATIONS OF RETINAL INPUT AND BRAIN DAMAGE

    Directory of Open Access Journals (Sweden)

    LAURA RESTANI

    2016-11-01

    Full Text Available Vision is a very important sensory modality in humans. Visual disorders are numerous and arising from diverse and complex causes. Deficits in visual function are highly disabling from a social point of view and in addition cause a considerable economic burden. For all these reasons there is an intense effort by the scientific community to gather knowledge on visual deficit mechanisms and to find possible new strategies for recovery and treatment. In this review we focus on an important and sometimes neglected player of the visual function, the corpus callosum (CC. The CC is the major white matter structure in the brain and is involved in information processing between the two hemispheres. In particular, visual callosal connections interconnect homologous areas of visual cortices, binding together the two halves of the visual field. This interhemispheric communication plays a significant role in visual cortical output. Here, we will first review essential literature on the physiology of the callosal connections in normal vision. The available data support the view that the callosum contributes to both excitation and inhibition to the target hemisphere, with a dynamic adaptation to the strength of the incoming visual input. Next, we will focus on data showing how callosal connections may sense visual alterations and respond to the classical paradigm for the study of visual plasticity, i.e. monocular deprivation. This is a prototypical example of a model for the study of callosal plasticity in pathological conditions (e.g. strabismus and amblyopia characterized by unbalanced input from the two eyes. We will also discuss findings of callosal alterations in blind subjects. Noteworthy, we will discuss data showing that inter-hemispheric transfer mediates recovery of visual responsiveness following cortical damage. Finally, we will provide an overview of how callosal projections dysfunction could contribute to pathologies such as neglect and occipital

  17. Help! It's Hair Loss!

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español Hair Loss KidsHealth / For Kids / Hair Loss What's in this ... head are in the resting phase. What Causes Hair Loss? Men, especially older men, are the ones who ...

  18. Proven Weight Loss Methods

    Science.gov (United States)

    Fact Sheet Proven Weight Loss Methods What can weight loss do for you? Losing weight can improve your health in a number of ways. It can lower ... at www.hormone.org/Spanish . Proven Weight Loss Methods Fact Sheet www.hormone.org

  19. Introduction: Critical Visual Theory

    Directory of Open Access Journals (Sweden)

    Peter Ludes

    2014-03-01

    Full Text Available The studies selected for publication in this special issue on Critical Visual Theory can be divided into three thematic groups: (1 image making as power making, (2 commodification and recanonization, and (3 approaches to critical visual theory. The approaches to critical visual theory adopted by the authors of this issue may be subsumed under the following headings (3.1 critical visual discourse and visual memes in general and Anonymous visual discourse in particular, (3.2 collective memory and gendered gaze, and (3.3 visual capitalism, global north and south.

  20. Emergent risk factors associated with eyeball loss and ambulatory vision loss after globe injuries.

    Science.gov (United States)

    Hyun Lee, Seung; Ahn, Jae Kyoun

    2010-07-01

    The objective of this study was to evaluate risk factors associated with eyeball loss and ambulatory vision loss on emergent examination of patients with ocular trauma. We reviewed the medical records of 1,875 patients hospitalized in a single tertiary referral center between January 2003 and December 2007. Emergent examinations included a history of trauma, elapsed time between injury and hospital arrival, visible intraocular tissues, and initial visual acuity (VA) using a penlight. The main outcome measures were ocular survival and ambulatory vision survival (>20/200) at 1 year after trauma using univariate and multivariate regression analysis. The ocular trauma scores were significantly higher in open globe injuries than in closed globe injuries (p eyeball loss. Elapsed time more than 12 hours and visible intraocular tissues were the significant risk factors associated with ambulatory vision loss. The most powerful predictor of eyeball loss and ambulatory vision loss was eyeball rupture. In closed globe injuries, there were no significant risk factors of eyeball loss, whereas initial vision less than LP and the presence of relative afferent pupillary defect were the significant risk factors associated with ambulatory vision loss. An initial VA less than LP using a penlight, a history of golf ball injury, and elapsed time more than 12 hours between ocular trauma and hospital arrival were associated with eyeball loss and ambulatory vision loss. Physicians should bear these factors in mind so that they can more effectively counsel patients with such injuries.

  1. Visual acuity at 10 years in Cryotherapy for Retinopathy of Prematurity (CRYO-ROP) study eyes: effect of retinal residua of retinopathy of prematurity.

    Science.gov (United States)

    Dobson, Velma; Quinn, Graham E; Summers, C Gail; Hardy, Robert J; Tung, Betty

    2006-02-01

    To describe recognition (letter) acuity at age 10 years in eyes with and without retinal residua of retinopathy of prematurity (ROP). Presence and severity of ROP residua were documented by a study ophthalmologist. Masked testers measured monocular recognition visual acuity (Early Treatment of Diabetic Retinopathy Study) when the children were 10 years old. Two hundred forty-seven of 255 surviving Cryotherapy for Retinopathy of Prematurity (CRYO-ROP) randomized trial patients participated. A reference group of 102 of 104 Philadelphia-based CRYO-ROP study participants who did not develop ROP was also tested. More severe retinal residua were associated with worse visual acuity, regardless of whether retinal ablation was performed to treat the severe acute-phase ROP. However, within each ROP residua category, there was a wide range of visual acuity results. This is the first report of the relation between visual acuity (Early Treatment of Diabetic Retinopathy Study charts) and structural abnormalities related to ROP in a large group of eyes that developed threshold ROP in the perinatal period. Visual deficits are greater in eyes with more severe retinal residua than in eyes with mild or no residua. However, severity of ROP residua does not predict the visual acuity of an individual eye because within a single residua category, acuity may range from near normal to blind.

  2. [The influence of IOL implantation on visual acuity, contrast sensitivity and colour vision 2 and 4 months after cataract surgery].

    Science.gov (United States)

    Ventruba, J

    2006-04-01

    To assess the change in visual acuity, contrast sensitivity and colour vision in relation to the time after cataract surgery and to the type of implanted IOL, and to compare visual functions by patients with one and two pseudophakic eyes. 45 cataract patients were examined before and then 2 and 4 month after the cataract surgery. Visual acuity (VA) was tested on logMAR optotype chart with Landolt rings, contrast sensitivity (CS) was tested on the Pelli-Robson chart and the SWCT chart. For colour vision (CV) testing, the standard Farnsworth D-15 test and the desaturated Lanthony D-15 test were used. The patients were divided into two groups--a group with one pseudophakic eye and a group with two pseudophakic eyes, and also according to the type of IOL--PMMA or hydrophobic acrylate that had been implanted. Control group was composed of phakic subjects with no ocular pathology. After the cataract surgery, in both groups there was a significant improvement in monocular and binocular VA (p test (p test (p tested by means of psychophysical methods of VA, CS and CV significantly improve and are stable 2 month after the surgery. The second eye surgery improves binocular visual functions the level of which doesn't differ from that of normal phakic subjects. There was no influence of the type of IOL on final state of VA, CS or CV.

  3. Cortical visual impairment

    OpenAIRE

    Koželj, Urša

    2013-01-01

    In this thesis we discuss cortical visual impairment, diagnosis that is in the developed world in first place, since 20 percent of children with blindness or low vision are diagnosed with it. The objectives of the thesis are to define cortical visual impairment and the definition of characters suggestive of the cortical visual impairment as well as to search for causes that affect the growing diagnosis of cortical visual impairment. There are a lot of signs of cortical visual impairment. ...

  4. Relativity of Visual Communication

    OpenAIRE

    Arto Mutanen

    2016-01-01

    Communication is sharing and conveying information. In visual communication especially visual messages have to be formulated and interpreted. The interpretation is relative to a method of information presentation method which is human construction. This holds also in the case of visual languages. The notions of syntax and semantics for visual languages are not so well founded as they are for natural languages. Visual languages are both syntactically and semantically dense. The density is conn...

  5. Energy losses in switches

    International Nuclear Information System (INIS)

    Martin, T.H.; Seamen, J.F.; Jobe, D.O.

    1993-01-01

    The authors experiments show energy losses between 2 and 10 times that of the resistive time predictions. The experiments used hydrogen, helium, air, nitrogen, SF 6 polyethylene, and water for the switching dielectric. Previously underestimated switch losses have caused over predicting the accelerator outputs. Accurate estimation of these losses is now necessary for new high-efficiency pulsed power devices where the switching losses constitute the major portion of the total energy loss. They found that the switch energy losses scale as (V peak I peak ) 1.1846 . When using this scaling, the energy losses in any of the tested dielectrics are almost the same. This relationship is valid for several orders of magnitude and suggested a theoretical basis for these results. Currents up to .65 MA, with voltages to 3 MV were applied to various gaps during these experiments. The authors data and the developed theory indicates that the switch power loss continues for a much longer time than the resistive time, with peak power loss generally occurring at peak current in a ranging discharge instead of the early current time. All of the experiments were circuit code modeled after developing a new switch loss version based on the theory. The circuit code predicts switch energy loss and peak currents as a function of time. During analysis of the data they noticed slight constant offsets between the theory and data that depended on the dielectric. They modified the plasma conductivity for each tested dielectric to lessen this offset

  6. Beam Loss in Linacs

    CERN Document Server

    Plum, M.A.

    2016-01-01

    Beam loss is a critical issue in high-intensity accelerators, and much effort is expended during both the design and operation phases to minimize the loss and to keep it to manageable levels. As new accelerators become ever more powerful, beam loss becomes even more critical. Linacs for H- ion beams, such as the one at the Oak Ridge Spallation Neutron Source, have many more loss mechanisms compared to H+ (proton) linacs, such as the one being designed for the European Spallation Neutron Source. Interesting H- beam loss mechanisms include residual gas stripping, H+ capture and acceleration, field stripping, black-body radiation and the recently discovered intra-beam stripping mechanism. Beam halo formation, and ion source or RF turn on/off transients, are examples of beam loss mechanisms that are common for both H+ and H- accelerators. Machine protection systems play an important role in limiting the beam loss.

  7. Visualization tools for insurance risk processes

    OpenAIRE

    Krzysztof Burnecki; Rafal Weron

    2006-01-01

    This chapter develops on risk processes which, perhaps, are most suitable for computer visualization of all insurance objects. At the same time, risk processes are basic instruments for any non-life actuary – they are vital for calculating the amount of loss that an insurance company may incur.

  8. Bilateral Simultaneous Macular Infarction with Spontaneous Visual ...

    African Journals Online (AJOL)

    2018-01-30

    Jan 30, 2018 ... eyes and near acuity was; right eye: N24, left eye: N36. ... Keywords: Macular infarction, macular ischemia, sickle cell, visual loss ... and build upon the work non-commercially, as long as the author is credited and the new.

  9. Visualization analysis and design

    CERN Document Server

    Munzner, Tamara

    2015-01-01

    Visualization Analysis and Design provides a systematic, comprehensive framework for thinking about visualization in terms of principles and design choices. The book features a unified approach encompassing information visualization techniques for abstract data, scientific visualization techniques for spatial data, and visual analytics techniques for interweaving data transformation and analysis with interactive visual exploration. It emphasizes the careful validation of effectiveness and the consideration of function before form. The book breaks down visualization design according to three questions: what data users need to see, why users need to carry out their tasks, and how the visual representations proposed can be constructed and manipulated. It walks readers through the use of space and color to visually encode data in a view, the trade-offs between changing a single view and using multiple linked views, and the ways to reduce the amount of data shown in each view. The book concludes with six case stu...

  10. Relativity of Visual Communication

    Directory of Open Access Journals (Sweden)

    Arto Mutanen

    2016-03-01

    Full Text Available Communication is sharing and conveying information. In visual communication especially visual messages have to be formulated and interpreted. The interpretation is relative to a method of information presentation method which is human construction. This holds also in the case of visual languages. The notions of syntax and semantics for visual languages are not so well founded as they are for natural languages. Visual languages are both syntactically and semantically dense. The density is connected to the compositionality of the (pictorial languages. In the paper Charles Sanders Peirce’s theory of signs will be used in characterizing visual languages. This allows us to relate visual languages to natural languages. The foundation of information presentation methods for visual languages is the logic of perception, but only if perception is understood as propositional perception. This allows us to understand better the relativity of information presentation methods, and hence to evaluate the cultural relativity of visual communication.

  11. Prevalence of high astigmatism, eyeglass wear, and poor visual acuity among Native American grade school children.

    Science.gov (United States)

    Harvey, Erin M; Dobson, Velma; Miller, Joseph M

    2006-04-01

    The purpose of this study was to examine the prevalence of astigmatism and poor visual acuity and rate of eyeglass wear in grade school children who are members of a Native American tribe reported to have a high prevalence of large amounts of astigmatism. Vision screening was conducted on 1,327 first through eighth grade children attending school on the Tohono O'odham Reservation. Noncycloplegic autorefraction was conducted on the right and left eye of each child using the Nikon Retinomax K+ autorefractor, and monocular recognition acuity was tested using ETDRS logarithm of the minimum angle of resolution (logMAR) letter charts. Tohono O'odham children had a high prevalence of high astigmatism (42% had > or = 1.00 D in the right or left eye) and the axis of astigmatism was uniformly with-the-rule. However, only a small percentage of children arrived at the vision screening wearing glasses, and the prevalence of poor visual acuity (20/40 or worse in either eye) was high (35%). There was a significant relation between amount of astigmatism and uncorrected visual acuity with each additional diopter of astigmatism resulting in an additional 1 logMAR line reduction in visual acuity. Uncorrected astigmatism and poor visual acuity are prevalent among Tohono O'odham children. The results highlight the importance of improving glasses-wearing compliance, determining barriers to receiving eye care, and initiating public education programs regarding the importance of early identification and correction of astigmatism in Tohono O'odham children.

  12. Neurons Responsive to Global Visual Motion Have Unique Tuning Properties in Hummingbirds.

    Science.gov (United States)

    Gaede, Andrea H; Goller, Benjamin; Lam, Jessica P M; Wylie, Douglas R; Altshuler, Douglas L

    2017-01-23

    Neurons in animal visual systems that respond to global optic flow exhibit selectivity for motion direction and/or velocity. The avian lentiformis mesencephali (LM), known in mammals as the nucleus of the optic tract (NOT), is a key nucleus for global motion processing [1-4]. In all animals tested, it has been found that the majority of LM and NOT neurons are tuned to temporo-nasal (back-to-front) motion [4-11]. Moreover, the monocular gain of the optokinetic response is higher in this direction, compared to naso-temporal (front-to-back) motion [12, 13]. Hummingbirds are sensitive to small visual perturbations while hovering, and they drift to compensate for optic flow in all directions [14]. Interestingly, the LM, but not other visual nuclei, is hypertrophied in hummingbirds relative to other birds [15], which suggests enhanced perception of global visual motion. Using extracellular recording techniques, we found that there is a uniform distribution of preferred directions in the LM in Anna's hummingbirds, whereas zebra finch and pigeon LM populations, as in other tetrapods, show a strong bias toward temporo-nasal motion. Furthermore, LM and NOT neurons are generally classified as tuned to "fast" or "slow" motion [10, 16, 17], and we predicted that most neurons would be tuned to slow visual motion as an adaptation for slow hovering. However, we found the opposite result: most hummingbird LM neurons are tuned to fast pattern velocities, compared to zebra finches and pigeons. Collectively, these results suggest a role in rapid responses during hovering, as well as in velocity control and collision avoidance during forward flight of hummingbirds. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Refractive error and visual impairment in school children in Northern Ireland.

    Science.gov (United States)

    O'Donoghue, L; McClelland, J F; Logan, N S; Rudnicka, A R; Owen, C G; Saunders, K J

    2010-09-01

    To describe the prevalence of refractive error (myopia and hyperopia) and visual impairment in a representative sample of white school children. The Northern Ireland Childhood Errors of Refraction study, a population-based cross-sectional study, examined 661 white 12-13-year-old and 392 white 6-7-year-old children between 2006 and 2008. Procedures included assessment of monocular logarithm of the minimum angle of resolution (logMAR), visual acuity (unaided and presenting) and binocular open-field cycloplegic (1% cyclopentolate) autorefraction. Myopia was defined as -0.50DS or more myopic spherical equivalent refraction (SER) in either eye, hyperopia as > or =+2.00DS SER in either eye if not previously classified as myopic. Visual impairment was defined as >0.30 logMAR units (equivalent to 6/12). Levels of myopia were 2.8% (95% CI 1.3% to 4.3%) in younger and 17.7% (95% CI 13.2% to 22.2%) in older children: corresponding levels of hyperopia were 26% (95% CI 20% to 33%) and 14.7% (95% CI 9.9% to 19.4%). The prevalence of presenting visual impairment in the better eye was 3.6% in 12-13-year-old children compared with 1.5% in 6-7-year-old children. Almost one in four children fails to bring their spectacles to school. This study is the first to provide robust population-based data on the prevalence of refractive error and visual impairment in Northern Irish school children. Strategies to improve compliance with spectacle wear are required.

  14. Visual function and long-term chloroquine treatment

    African Journals Online (AJOL)

    Amsler grids and a further battery offour tests of macular function (visual evoked potentials, criti- cal flicker fusion threshold, Cambridge contrast sensitivity and the macular dazzle test) were administered. No case of retinal pigmentary abnonnalities plus visual loss was found, but 2 patients were advised to cease chloroquine.

  15. Losses as ecological guides: minor losses lead to maximization and not to avoidance.

    Science.gov (United States)

    Yechiam, Eldad; Retzer, Matan; Telpaz, Ariel; Hochman, Guy

    2015-06-01

    Losses are commonly thought to result in a neuropsychological avoidance response. We suggest that losses also provide ecological guidance by increasing focus on the task at hand, and that this effect may override the avoidance response. This prediction was tested in a series of studies. In Study 1a we found that minor losses did not lead to an avoidance response. Instead, they guided participants to make advantageous choices (in terms of expected value) and to avoid disadvantageous choices. Moreover, losses were associated with less switching between options after the first block of exploration. In Study 1b we found that this effect was not simply a by-product of the increase in visual contrast with losses. In Study 1c we found that the effect of losses did not emerge when alternatives did not differ in their expected value but only in their risk level. In Study 2 we investigated the autonomic arousal dynamics associated with this behavioral pattern via pupillometric responses. The results showed increased pupil diameter following losses compared to gains. However, this increase was not associated with a tendency to avoid losses, but rather with a tendency to select more advantageously. These findings suggest that attention and reasoning processes induced by losses can out-weigh the influence of affective processes leading to avoidance. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Visualizing the Verbal and Verbalizing the Visual.

    Science.gov (United States)

    Braden, Roberts A.

    This paper explores relationships of visual images to verbal elements, beginning with a discussion of visible language as represented by words printed on the page. The visual flexibility inherent in typography is discussed in terms of the appearance of the letters and the denotative and connotative meanings represented by type, typographical…

  17. A Visual Test for Visual "Literacy."

    Science.gov (United States)

    Messaris, Paul

    Four different principles of visual manipulation constitute a minimal list of what a visually "literate" viewer should know about, but certain problems exist which are inherent in measuring viewers' awareness of each of them. The four principles are: (1) paraproxemics, or camera work which derives its effectiveness from an analogy to the…

  18. Interaction for visualization

    CERN Document Server

    Tominski, Christian

    2015-01-01

    Visualization has become a valuable means for data exploration and analysis. Interactive visualization combines expressive graphical representations and effective user interaction. Although interaction is an important component of visualization approaches, much of the visualization literature tends to pay more attention to the graphical representation than to interaction.The goal of this work is to strengthen the interaction side of visualization. Based on a brief review of general aspects of interaction, we develop an interaction-oriented view on visualization. This view comprises five key as

  19. Visual memory and visual perception: when memory improves visual search.

    Science.gov (United States)

    Riou, Benoit; Lesourd, Mathieu; Brunel, Lionel; Versace, Rémy

    2011-08-01

    This study examined the relationship between memory and perception in order to identify the influence of a memory dimension in perceptual processing. Our aim was to determine whether the variation of typical size between items (i.e., the size in real life) affects visual search. In two experiments, the congruency between typical size difference and perceptual size difference was manipulated in a visual search task. We observed that congruency between the typical and perceptual size differences decreased reaction times in the visual search (Exp. 1), and noncongruency between these two differences increased reaction times in the visual search (Exp. 2). We argue that these results highlight that memory and perception share some resources and reveal the intervention of typical size difference on the computation of the perceptual size difference.

  20. Drugs and hair loss.

    Science.gov (United States)

    Patel, Mansi; Harrison, Shannon; Sinclair, Rodney

    2013-01-01

    Hair loss is a common complaint, both in men and women, and use of prescription medications is widespread. When there is a temporal association between the onset of hair loss and commencement of a medication, the medication is commonly thought to have caused the hair loss. However, hair loss and in particular telogen effluvium may occur in response to a number of triggers including fever, hemorrhage, severe illness, stress, and childbirth, and a thorough exclusion of these potential confounders is necessary before the hair loss can be blamed on the medication. Certain medications are known to cause hair loss by a variety of mechanisms including anagen arrest, telogen effluvium, or accentuation of androgenetic alopecia by androgens. Crown Copyright © 2013. Published by Elsevier Inc. All rights reserved.

  1. Handbook on loss reserving

    CERN Document Server

    Schmidt, Klaus; Schnaus, Anja

    2016-01-01

    This handbook presents the basic aspects of actuarial loss reserving. Besides the traditional methods, it also includes a description of more recent ones and a discussion of certain problems occurring in actuarial practice, like inflation, scarce data, large claims, slow loss development, the use of market statistics, the need for simulation techniques and the task of calculating best estimates and ranges of future losses. In property and casualty insurance the provisions for payment obligations from losses that have occurred but have not yet been settled usually constitute the largest item on the liabilities side of an insurer's balance sheet. For this reason, the determination and evaluation of these loss reserves is of considerable economic importance for every property and casualty insurer. Actuarial students, academics as well as practicing actuaries will benefit from this overview of the most important actuarial methods of loss reserving by developing an understanding of the underlying stochastic models...

  2. Gene Expression Patterns Underlying the Reinstatement of Plasticity in the Adult Visual System

    Directory of Open Access Journals (Sweden)

    Ettore Tiraboschi

    2013-01-01

    Full Text Available The nervous system is highly sensitive to experience during early postnatal life, but this phase of heightened plasticity decreases with age. Recent studies have demonstrated that developmental-like plasticity can be reactivated in the visual cortex of adult animals through environmental or pharmacological manipulations. These findings provide a unique opportunity to study the cellular and molecular mechanisms of adult plasticity. Here we used the monocular deprivation paradigm to investigate large-scale gene expression patterns underlying the reinstatement of plasticity produced by fluoxetine in the adult rat visual cortex. We found changes, confirmed with RT-PCRs, in gene expression in different biological themes, such as chromatin structure remodelling, transcription factors, molecules involved in synaptic plasticity, extracellular matrix, and excitatory and inhibitory neurotransmission. Our findings reveal a key role for several molecules such as the metalloproteases Mmp2 and Mmp9 or the glycoprotein Reelin and open up new insights into the mechanisms underlying the reopening of the critical periods in the adult brain.

  3. Unifying Terrain Awareness for the Visually Impaired through Real-Time Semantic Segmentation

    Directory of Open Access Journals (Sweden)

    Kailun Yang

    2018-05-01

    Full Text Available Navigational assistance aims to help visually-impaired people to ambulate the environment safely and independently. This topic becomes challenging as it requires detecting a wide variety of scenes to provide higher level assistive awareness. Vision-based technologies with monocular detectors or depth sensors have sprung up within several years of research. These separate approaches have achieved remarkable results with relatively low processing time and have improved the mobility of impaired people to a large extent. However, running all detectors jointly increases the latency and burdens the computational resources. In this paper, we put forward seizing pixel-wise semantic segmentation to cover navigation-related perception needs in a unified way. This is critical not only for the terrain awareness regarding traversable areas, sidewalks, stairs and water hazards, but also for the avoidance of short-range obstacles, fast-approaching pedestrians and vehicles. The core of our unification proposal is a deep architecture, aimed at attaining efficient semantic understanding. We have integrated the approach in a wearable navigation system by incorporating robust depth segmentation. A comprehensive set of experiments prove the qualified accuracy over state-of-the-art methods while maintaining real-time speed. We also present a closed-loop field test involving real visually-impaired users, demonstrating the effectivity and versatility of the assistive framework.

  4. Real-time markerless tracking for augmented reality: the virtual visual servoing framework.

    Science.gov (United States)

    Comport, Andrew I; Marchand, Eric; Pressigout, Muriel; Chaumette, François

    2006-01-01

    Tracking is a very important research subject in a real-time augmented reality context. The main requirements for trackers are high accuracy and little latency at a reasonable cost. In order to address these issues, a real-time, robust, and efficient 3D model-based tracking algorithm is proposed for a "video see through" monocular vision system. The tracking of objects in the scene amounts to calculating the pose between the camera and the objects. Virtual objects can then be projected into the scene using the pose. Here, nonlinear pose estimation is formulated by means of a virtual visual servoing approach. In this context, the derivation of point-to-curves interaction matrices are given for different 3D geometrical primitives including straight lines, circles, cylinders, and spheres. A local moving edges tracker is used in order to provide real-time tracking of points normal to the object contours. Robustness is obtained by integrating an M-estimator into the visual control law via an iteratively reweighted least squares implementation. This approach is then extended to address the 3D model-free augmented reality problem. The method presented in this paper has been validated on several complex image sequences including outdoor environments. Results show the method to be robust to occlusion, changes in illumination, and mistracking.

  5. Neuronal responses in visual area V2 (V2) of macaque monkeys with strabismic amblyopia.

    Science.gov (United States)

    Bi, H; Zhang, B; Tao, X; Harwerth, R S; Smith, E L; Chino, Y M

    2011-09-01

    Amblyopia, a developmental disorder of spatial vision, is thought to result from a cascade of cortical deficits over several processing stages beginning at the primary visual cortex (V1). However, beyond V1, little is known about how cortical development limits the visual performance of amblyopic primates. We quantitatively analyzed the monocular and binocular responses of V1 and V2 neurons in a group of strabismic monkeys exhibiting varying depths of amblyopia. Unlike in V1, the relative effectiveness of the affected eye to drive V2 neurons was drastically reduced in the amblyopic monkeys. The spatial resolution and the orientation bias of V2, but not V1, neurons were subnormal for the affected eyes. Binocular suppression was robust in both cortical areas, and the magnitude of suppression in individual monkeys was correlated with the depth of their amblyopia. These results suggest that the reduced functional connections beyond V1 and the subnormal spatial filter properties of V2 neurons might have substantially limited the sensitivity of the amblyopic eyes and that interocular suppression was likely to have played a key role in the observed alterations of V2 responses and the emergence of amblyopia.

  6. Visual Artist or Visual Designer? Visual Communication Design Education

    OpenAIRE

    Arsoy, Aysu

    2010-01-01

    ABSTRACT: Design tools and contents have been digitalized, forming the contemporary fields of the visual arts and design. Corporate culture demands techno-social experts who understand the arts, design, culture and society, while also having a high level of technological proficiency. New departments have opened offering alternatives in art and design education such as Visual Communication Design (VCD) and are dedicated to educating students in the practical aspect of using digital technologi...

  7. Visual performance in cataract patients with low levels of postoperative astigmatism: full correction versus spherical equivalent correction

    Directory of Open Access Journals (Sweden)

    Lehmann RP

    2012-03-01

    Full Text Available Robert P Lehmann1, Diane M Houtman21Lehmann Eye Center, Nacogdoches, TX, 2Alcon Research Ltd, Fort Worth, TX, USAPurpose: To evaluate whether visual performance could be improved in pseudophakic subjects by correcting low levels of postoperative astigmatism.Methods: An exploratory, noninterventional study was conducted using subjects who had been implanted with an aspheric intraocular lens and had 0.5–0.75 diopter postoperative astigmatism. Monocular visual performance using full correction was compared with visual performance using spherical equivalent correction. Testing consisted of high- and low-contrast visual acuity, contrast sensitivity, and reading acuity and speed using the Radner Reading Charts.Results: Thirty-eight of 40 subjects completed testing. Visual acuities at three contrast levels (100%, 25%, and 9% were significantly better using full correction than when using spherical equivalent correction (all P < 0.001. For contrast sensitivity testing under photopic, mesopic, and mesopic with glare conditions, only one out of twelve outcomes demonstrated a significant improvement with full correction compared with spherical equivalent correction (at six cycles per degree under mesopic without glare conditions, P = 0.046. Mean reading speed was numerically faster with full correction across all print sizes, reaching statistical significance at logarithm of the reading acuity determination (logRAD 0.2, 0.7, and 1.1 (P , 0.05. Statistically significant differences also favored full correction in logRAD score (P = 0.0376, corrected maximum reading speed (P < 0.001, and logarithm of the minimum angle of resolution/logRAD ratio (P < 0.001.Conclusions: In this study of pseudophakic subjects with low levels of postoperative astigmatism, full correction yielded significantly better reading performance and high- and low-contrast visual acuity than spherical equivalent correction, suggesting that cataractous patients may benefit from surgical

  8. Localización y mapeo visual monocular para robot móvil terrestre aplicado a la inspección ultrasónica aeronáutica

    OpenAIRE

    Rodríguez Plaza, Óscar Tomás

    2016-01-01

    En el ámbito de la robótica de servicio, actualmente no existe una solución automatizada para la inspección ultrasónica de las partes de material compuesto de una aeronave durante las operaciones de mantenimiento que realiza la aerolínea. El desarrollo de las nuevas técnicas de acoplamiento acústico en seco en el método de inspección no destructiva por ultrasonidos, está conduciendo a posibilitar su uso con soluciones de menor coste respecto a las técnicas tradicionales, sin perder eficaci...

  9. Visual acuity test

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/003396.htm Visual acuity test To use the sharing features on this page, please enable JavaScript. The visual acuity test is used to determine the smallest ...

  10. The Visual System

    Medline Plus

    Full Text Available ... to blinding eye diseases, visual disorders, mechanisms of visual function, preservation of sight, and the special health problems and requirements of the blind.” ... Clinical Studies Publications Catalog Photos ...

  11. Topological Methods for Visualization

    Energy Technology Data Exchange (ETDEWEB)

    Berres, Anne Sabine [Los Alamos National Lab. (LANL), Los Alamos, NM (United Stat

    2016-04-07

    This slide presentation describes basic topological concepts, including topological spaces, homeomorphisms, homotopy, betti numbers. Scalar field topology explores finding topological features and scalar field visualization, and vector field topology explores finding topological features and vector field visualization.

  12. The Visual System

    Medline Plus

    Full Text Available ... National Eye Institute’s mission is to “conduct and support research, training, health information dissemination, and other programs with respect to blinding eye diseases, visual disorders, mechanisms of visual function, preservation of sight, ...

  13. Constructing visual representations

    DEFF Research Database (Denmark)

    Huron, Samuel; Jansen, Yvonne; Carpendale, Sheelagh

    2014-01-01

    tangible building blocks. We learned that all participants, most of whom had little experience in visualization authoring, were readily able to create and talk about their own visualizations. Based on our observations, we discuss participants’ actions during the development of their visual representations......The accessibility of infovis authoring tools to a wide audience has been identified as a major research challenge. A key task in the authoring process is the development of visual mappings. While the infovis community has long been deeply interested in finding effective visual mappings......, comparatively little attention has been placed on how people construct visual mappings. In this paper, we present the results of a study designed to shed light on how people transform data into visual representations. We asked people to create, update and explain their own information visualizations using only...

  14. The Visual System

    Medline Plus

    Full Text Available ... NIH), the National Eye Institute’s mission is to “conduct and support research, training, health information dissemination, and other programs with respect to blinding eye diseases, visual disorders, mechanisms of visual function, preservation of ...

  15. Visualization of Social Networks

    NARCIS (Netherlands)

    Boertjes, E.M.; Kotterink, B.; Jager, E.J.

    2011-01-01

    Current visualizations of social networks are mostly some form of node-link diagram. Depending on the type of social network, this can be some treevisualization with a strict hierarchical structure or a more generic network visualization.

  16. Visual Control of Locomotion

    National Research Council Canada - National Science Library

    Loomis, Jack M; Beall, Andrew C

    2005-01-01

    The accomplishments were threefold. First, a software tool for rendering virtual environments was developed, a tool useful for other researchers interested in visual perception and visual control of action...

  17. Visual explorer facilitator's guide

    CERN Document Server

    Palus, Charles J

    2010-01-01

    Grounded in research and practice, the Visual Explorer™ Facilitator's Guide provides a method for supporting collaborative, creative conversations about complex issues through the power of images. The guide is available as a component in the Visual Explorer Facilitator's Letter-sized Set, Visual Explorer Facilitator's Post card-sized Set, Visual Explorer Playing Card-sized Set, and is also available as a stand-alone title for purchase to assist multiple tool users in an organization.

  18. Thinking in z-space: flatness and spatial narrativity

    Science.gov (United States)

    Zone, Ray

    2012-03-01

    Now that digital technology has accessed the Z-space in cinema, narrative artistry is at a loss. Motion picture professionals no longer can readily resort to familiar tools. A new language and new linguistics for Z-axis storytelling are necessary. After first examining the roots of monocular thinking in painting, prior modes of visual narrative in twodimensional cinema obviating true binocular stereopsis can be explored, particularly montage, camera motion and depth of field, with historic examples. Special attention is paid to the manner in which monocular cues for depth have been exploited to infer depth on a planar screen. Both the artistic potential and visual limitations of actual stereoscopic depth as a filmmaking language are interrogated. After an examination of the historic basis of monocular thinking in visual culture, a context for artistic exploration of the use of the z-axis as a heightened means of creating dramatic and emotional impact upon the viewer is illustrated.

  19. Creativity, visualization abilities, and visual cognitive style.

    Science.gov (United States)

    Kozhevnikov, Maria; Kozhevnikov, Michael; Yu, Chen Jiao; Blazhenkova, Olesya

    2013-06-01

    Despite the recent evidence for a multi-component nature of both visual imagery and creativity, there have been no systematic studies on how the different dimensions of creativity and imagery might interrelate. The main goal of this study was to investigate the relationship between different dimensions of creativity (artistic and scientific) and dimensions of visualization abilities and styles (object and spatial). In addition, we compared the contributions of object and spatial visualization abilities versus corresponding styles to scientific and artistic dimensions of creativity. Twenty-four undergraduate students (12 females) were recruited for the first study, and 75 additional participants (36 females) were recruited for an additional experiment. Participants were administered a number of object and spatial visualization abilities and style assessments as well as a number of artistic and scientific creativity tests. The results show that object visualization relates to artistic creativity and spatial visualization relates to scientific creativity, while both are distinct from verbal creativity. Furthermore, our findings demonstrate that style predicts corresponding dimension of creativity even after removing shared variance between style and visualization ability. The results suggest that styles might be a more ecologically valid construct in predicting real-life creative behaviour, such as performance in different professional domains. © 2013 The British Psychological Society.

  20. Visual attention and stability

    NARCIS (Netherlands)

    Mathot, Sebastiaan; Theeuwes, Jan

    2011-01-01

    In the present review, we address the relationship between attention and visual stability. Even though with each eye, head and body movement the retinal image changes dramatically, we perceive the world as stable and are able to perform visually guided actions. However, visual stability is not as