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Sample records for monocular visual loss

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

    Science.gov (United States)

    Petzold, Axel; Islam, Niaz; Plant, G T

    2013-07-01

    The aim of this study was to systematically describe the semiology of non-embolic transient monocular visual field loss (neTMVL). We conducted a retrospective case note analysis of patients from Moorfields Eye Hospital (1995-2007). The variables analysed were age, age of onset, gender, past medical history or family history of migraine, eye affected, onset, duration and offset, perception (pattern, positive and negative symptoms), associated headache and autonomic symptoms, attack frequency, and treatment response to nifedipine. We identified 77 patients (28 male and 49 female). Mean age of onset was 37 years (range 14-77 years). The neTMVL was limited to the right eye in 36 % to the left in 47 % and occurred independently in either eye in 5 % of cases. A past medical history of migraine was present in 12 % and a family history in 8 %. Headache followed neTMVL in 14 % and was associated with autonomic features in 3 %. The neTMB was perceived as grey in 35 %, white in 21 %, black in 16 % and as phosphenes in 9 %. Most frequently neTMVL was patchy 20 %. Recovery of vision frequently resembled attack onset in reverse. In 3 patients without associated headache the loss of vision was permanent. Treatment with nifedipine was initiated in 13 patients with an attack frequency of more than one per week and reduced the attack frequency in all. In conclusion, this large series of patients with neTMVL permits classification into five types of reversible visual field loss (grey, white, black, phosphenes, patchy). Treatment response to nifidipine suggests some attacks to be caused by vasospasm.

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

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    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.

  3. Embolic and nonembolic transient monocular visual field loss: a clinicopathologic review.

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    Petzold, Axel; Islam, Niaz; Hu, Han-Hwa; Plant, Gordon T

    2013-01-01

    Transient monocular blindness and amaurosis fugax are umbrella terms describing a range of patterns of transient monocular visual field loss (TMVL). The incidence rises from ≈1.5/100,000 in the third decade of life to ≈32/100,000 in the seventh decade of life. We review the vascular supply of the retina that provides an anatomical basis for the types of TMVL and discuss the importance of collaterals between the external and internal carotid artery territories and related blood flow phenomena. Next, we address the semiology of TMVL, focusing on onset, pattern, trigger factors, duration, recovery, frequency-associated features such as headaches, and on tests that help with the important differential between embolic and non-embolic etiologies.

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

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    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.

  5. Monocular visual ranging

    Science.gov (United States)

    Witus, Gary; Hunt, Shawn

    2008-04-01

    The vision system of a mobile robot for checkpoint and perimeter security inspection performs multiple functions: providing surveillance video, providing high resolution still images, and providing video for semi-autonomous visual navigation. Mid-priced commercial digital cameras support the primary inspection functions. Semi-autonomous visual navigation is a tertiary function whose purpose is to reduce the burden of teleoperation and free the security personnel for their primary functions. Approaches to robot visual navigation require some form of depth perception for speed control to prevent the robot from colliding with objects. In this paper present the initial results of an exploration of the capabilities and limitations of using a single monocular commercial digital camera for depth perception. Our approach combines complementary methods in alternating stationary and moving behaviors. When the platform is stationary, it computes a range image from differential blur in the image stack collected at multiple focus settings. When the robot is moving, it extracts an estimate of range from the camera auto-focus function, and combines this with an estimate derived from angular expansion of a constellation of visual tracking points.

  6. 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

  7. Visual SLAM for Handheld Monocular Endoscope.

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    Grasa, Óscar G; Bernal, Ernesto; Casado, Santiago; Gil, Ismael; Montiel, J M M

    2014-01-01

    Simultaneous localization and mapping (SLAM) methods provide real-time estimation of 3-D models from the sole input of a handheld camera, routinely in mobile robotics scenarios. Medical endoscopic sequences mimic a robotic scenario in which a handheld camera (monocular endoscope) moves along an unknown trajectory while observing an unknown cavity. However, the feasibility and accuracy of SLAM methods have not been extensively validated with human in vivo image sequences. In this work, we propose a monocular visual SLAM algorithm tailored to deal with medical image sequences in order to provide an up-to-scale 3-D map of the observed cavity and the endoscope trajectory at frame rate. The algorithm is validated over synthetic data and human in vivo sequences corresponding to 15 laparoscopic hernioplasties where accurate ground-truth distances are available. It can be concluded that the proposed procedure is: 1) noninvasive, because only a standard monocular endoscope and a surgical tool are used; 2) convenient, because only a hand-controlled exploratory motion is needed; 3) fast, because the algorithm provides the 3-D map and the trajectory in real time; 4) accurate, because it has been validated with respect to ground-truth; and 5) robust to inter-patient variability, because it has performed successfully over the validation sequences.

  8. 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...... 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....... Stimulus–response curves were constructed by recording the intensity of the reported phosphenes evoked in the contralateral visual field at range of TMS intensities. Phosphene measurements revealed that MD produced a rapid and robust decrease in cortical excitability relative to a control condition without...

  9. A Case of Functional (Psychogenic Monocular Hemianopia Analyzed by Measurement of Hemifield Visual Evoked Potentials

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    Tsuyoshi Yoneda

    2013-12-01

    Full Text Available Purpose: Functional monocular hemianopia is an extremely rare condition, for which measurement of hemifield visual evoked potentials (VEPs has not been previously described. Methods: A 14-year-old boy with functional monocular hemianopia was followed up with Goldmann perimetry and measurement of hemifield and full-field VEPs. Results: The patient had a history of monocular temporal hemianopia of the right eye following headache, nausea and ague. There was no relative afferent pupillary defect, and a color perception test was normal. Goldmann perimetry revealed a vertical monocular temporal hemianopia of the right eye; the hemianopia on the right was also detected with a binocular visual field test. Computed tomography, magnetic resonance imaging (MRI and MR angiography of the brain including the optic chiasm as well as orbital MRI revealed no abnormalities. On the basis of these results, we diagnosed the patient's condition as functional monocular hemianopia. Pattern VEPs according to the International Society for Clinical Electrophysiology of Vision (ISCEV standard were within the normal range. The hemifield pattern VEPs for the right eye showed a symmetrical latency and amplitude for nasal and temporal hemifield stimulation. One month later, the visual field defect of the patient spontaneously disappeared. Conclusions: The latency and amplitude of hemifield VEPs for a patient with functional monocular hemianopia were normal. Measurement of hemifield VEPs may thus provide an objective tool for distinguishing functional hemianopia from hemifield loss caused by an organic lesion.

  10. Altered anterior visual system development following early monocular enucleation

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    Krista R. Kelly

    2014-01-01

    Conclusions: The novel finding of an asymmetry in morphology of the anterior visual system following long-term survival from early monocular enucleation indicates altered postnatal visual development. Possible mechanisms behind this altered development include recruitment of deafferented cells by crossing nasal fibres and/or geniculate cell retention via feedback from primary visual cortex. These data highlight the importance of balanced binocular input during postnatal maturation for typical anterior visual system morphology.

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

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    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.

  12. More clinical observations on migraine associated with monocular visual symptoms in an Indian population

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    Vishal Jogi

    2016-01-01

    Full Text Available Context: Retinal migraine (RM is considered as one of the rare causes of transient monocular visual loss (TMVL and has not been studied in Indian population. Objectives: The study aims to analyze the clinical and investigational profile of patients with RM. Materials and Methods: This is an observational prospective analysis of 12 cases of TMVL fulfilling the International Classification of Headache Disorders-2nd edition (ICHD-II criteria of RM examined in Neurology and Ophthalmology Outpatient Department (OPD of Postgraduate Institute of Medical Education and Research (PGIMER, Chandigarh from July 2011 to October 2012. Results: Most patients presented in 3 rd and 4 th decade with equal sex distribution. Seventy-five percent had antecedent migraine without aura (MoA and 25% had migraine with Aura (MA. Headache was ipsilateral to visual symptoms in 67% and bilateral in 33%. TMVL preceded headache onset in 58% and occurred during headache episode in 42%. Visual symptoms were predominantly negative except in one patient who had positive followed by negative symptoms. Duration of visual symptoms was variable ranging from 30 s to 45 min. None of the patient had permanent monocular vision loss. Three patients had episodes of TMVL without headache in addition to the symptom constellation defining RM. Most of the tests done to rule out alternative causes were normal. Magnetic resonance imaging (MRI brain showed nonspecific white matter changes in one patient. Visual-evoked potential (VEP showed prolonged P100 latencies in two cases. Patent foramen ovale was detected in one patient. Conclusions: RM is a definite subtype of migraine and should remain in the ICHD classification. It should be kept as one of the differential diagnosis of transient monocular vision loss. We propose existence of "acephalgic RM" which may respond to migraine prophylaxis.

  13. Differential processing of binocular and monocular gloss cues in human visual cortex

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    Di Luca, Massimiliano; Ban, Hiroshi; Muryy, Alexander; Fleming, Roland W.

    2016-01-01

    The visual impression of an object's surface reflectance (“gloss”) relies on a range of visual cues, both monocular and binocular. Whereas previous imaging work has identified processing within ventral visual areas as important for monocular cues, little is known about cortical areas involved in processing binocular cues. Here, we used human functional MRI (fMRI) to test for brain areas selectively involved in the processing of binocular cues. We manipulated stereoscopic information to create four conditions that differed in their disparity structure and in the impression of surface gloss that they evoked. We performed multivoxel pattern analysis to find areas whose fMRI responses allow classes of stimuli to be distinguished based on their depth structure vs. material appearance. We show that higher dorsal areas play a role in processing binocular gloss information, in addition to known ventral areas involved in material processing, with ventral area lateral occipital responding to both object shape and surface material properties. Moreover, we tested for similarities between the representation of gloss from binocular cues and monocular cues. Specifically, we tested for transfer in the decoding performance of an algorithm trained on glossy vs. matte objects defined by either binocular or by monocular cues. We found transfer effects from monocular to binocular cues in dorsal visual area V3B/kinetic occipital (KO), suggesting a shared representation of the two cues in this area. These results indicate the involvement of mid- to high-level visual circuitry in the estimation of surface material properties, with V3B/KO potentially playing a role in integrating monocular and binocular cues. PMID:26912596

  14. Differential processing of binocular and monocular gloss cues in human visual cortex.

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    Sun, Hua-Chun; Di Luca, Massimiliano; Ban, Hiroshi; Muryy, Alexander; Fleming, Roland W; Welchman, Andrew E

    2016-06-01

    The visual impression of an object's surface reflectance ("gloss") relies on a range of visual cues, both monocular and binocular. Whereas previous imaging work has identified processing within ventral visual areas as important for monocular cues, little is known about cortical areas involved in processing binocular cues. Here, we used human functional MRI (fMRI) to test for brain areas selectively involved in the processing of binocular cues. We manipulated stereoscopic information to create four conditions that differed in their disparity structure and in the impression of surface gloss that they evoked. We performed multivoxel pattern analysis to find areas whose fMRI responses allow classes of stimuli to be distinguished based on their depth structure vs. material appearance. We show that higher dorsal areas play a role in processing binocular gloss information, in addition to known ventral areas involved in material processing, with ventral area lateral occipital responding to both object shape and surface material properties. Moreover, we tested for similarities between the representation of gloss from binocular cues and monocular cues. Specifically, we tested for transfer in the decoding performance of an algorithm trained on glossy vs. matte objects defined by either binocular or by monocular cues. We found transfer effects from monocular to binocular cues in dorsal visual area V3B/kinetic occipital (KO), suggesting a shared representation of the two cues in this area. These results indicate the involvement of mid- to high-level visual circuitry in the estimation of surface material properties, with V3B/KO potentially playing a role in integrating monocular and binocular cues. Copyright © 2016 the American Physiological Society.

  15. Enhanced monocular visual odometry integrated with laser distance meter for astronaut navigation.

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    Wu, Kai; Di, Kaichang; Sun, Xun; Wan, Wenhui; Liu, Zhaoqin

    2014-03-11

    Visual odometry provides astronauts with accurate knowledge of their position and orientation. Wearable astronaut navigation systems should be simple and compact. Therefore, monocular vision methods are preferred over stereo vision systems, commonly used in mobile robots. However, the projective nature of monocular visual odometry causes a scale ambiguity problem. In this paper, we focus on the integration of a monocular camera with a laser distance meter to solve this problem. The most remarkable advantage of the system is its ability to recover a global trajectory for monocular image sequences by incorporating direct distance measurements. First, we propose a robust and easy-to-use extrinsic calibration method between camera and laser distance meter. Second, we present a navigation scheme that fuses distance measurements with monocular sequences to correct the scale drift. In particular, we explain in detail how to match the projection of the invisible laser pointer on other frames. Our proposed integration architecture is examined using a live dataset collected in a simulated lunar surface environment. The experimental results demonstrate the feasibility and effectiveness of the proposed method.

  16. Acute Myeloid Leukemia Relapse Presenting as Complete Monocular Vision Loss due to Optic Nerve Involvement

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    Shyam A. Patel

    2016-01-01

    Full Text Available Acute myeloid leukemia (AML involvement of the central nervous system is relatively rare, and detection of leptomeningeal disease typically occurs only after a patient presents with neurological symptoms. The case herein describes a 48-year-old man with relapsed/refractory AML of the mixed lineage leukemia rearrangement subtype, who presents with monocular vision loss due to leukemic eye infiltration. MRI revealed right optic nerve sheath enhancement and restricted diffusion concerning for nerve ischemia and infarct from hypercellularity. Cerebrospinal fluid (CSF analysis showed a total WBC count of 81/mcl with 96% AML blasts. The onset and progression of visual loss were in concordance with rise in peripheral blood blast count. A low threshold for diagnosis of CSF involvement should be maintained in patients with hyperleukocytosis and high-risk cytogenetics so that prompt treatment with whole brain radiation and intrathecal chemotherapy can be delivered. This case suggests that the eye, as an immunoprivileged site, may serve as a sanctuary from which leukemic cells can resurge and contribute to relapsed disease in patients with high-risk cytogenetics.

  17. Metabolic Changes in the Bilateral Visual Cortex of the Monocular Blind Macaque: A Multi-Voxel Proton Magnetic Resonance Spectroscopy Study.

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    Wu, Lingjie; Tang, Zuohua; Feng, Xiaoyuan; Sun, Xinghuai; Qian, Wen; Wang, Jie; Jin, Lixin; Jiang, Jingxuan; Zhong, Yufeng

    2017-02-01

    The metabolic changes accompanied with adaptive plasticity in the visual cortex after early monocular visual loss were unclear. In this study, we detected the metabolic changes in bilateral visual cortex of normal (group A) and monocular blind macaque (group B) for studying the adaptive plasticity using multi-voxel proton magnetic resonance spectroscopy ((1)H-MRS) at 32 months after right optic nerve transection. Then, we compared the N-Acetyl aspartate (NAA)/Creatine (Cr), myoinositol (Ins)/Cr, choline (Cho)/Cr and Glx (Glutamate + glutamine)/Cr ratios in the visual cortex between two groups, as well as between the left and right visual cortex of group A and B. Compared with group A, in the bilateral visual cortex, a decreased NAA/Cr and Glx/Cr ratios in group B were found, which was more clearly in the right visual cortex; whereas the Ins/Cr and Cho/Cr ratios of group B were increased. All of these findings were further confirmed by immunohistochemical staining. In conclusion, the difference of metabolic ratios can be detected by multi-voxel (1)H-MRS in the visual cortex between groups A and B, which was valuable for investigating the adaptive plasticity of monocular blind macaque.

  18. Monocular visual scene understanding: understanding multi-object traffic scenes.

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    Wojek, Christian; Walk, Stefan; Roth, Stefan; Schindler, Konrad; Schiele, Bernt

    2013-04-01

    Following recent advances in detection, context modeling, and tracking, scene understanding has been the focus of renewed interest in computer vision research. This paper presents a novel probabilistic 3D scene model that integrates state-of-the-art multiclass object detection, object tracking and scene labeling together with geometric 3D reasoning. Our model is able to represent complex object interactions such as inter-object occlusion, physical exclusion between objects, and geometric context. Inference in this model allows us to jointly recover the 3D scene context and perform 3D multi-object tracking from a mobile observer, for objects of multiple categories, using only monocular video as input. Contrary to many other approaches, our system performs explicit occlusion reasoning and is therefore capable of tracking objects that are partially occluded for extended periods of time, or objects that have never been observed to their full extent. In addition, we show that a joint scene tracklet model for the evidence collected over multiple frames substantially improves performance. The approach is evaluated for different types of challenging onboard sequences. We first show a substantial improvement to the state of the art in 3D multipeople tracking. Moreover, a similar performance gain is achieved for multiclass 3D tracking of cars and trucks on a challenging dataset.

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

    LENUS (Irish Health Repository)

    O'Neill, Evelyn C

    2011-02-01

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

  20. Short-term monocular patching boosts the patched eye’s response in visual cortex

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    Zhou, Jiawei; Baker, Daniel H.; Simard, Mathieu; Saint-Amour, Dave; Hess, Robert F.

    2015-01-01

    Abstract Purpose: Several recent studies have demonstrated that following short-term monocular deprivation in normal adults, the patched eye, rather than the unpatched eye, becomes stronger in subsequent binocular viewing. However, little is known about the site and nature of the underlying processes. In this study, we examine the underlying mechanisms by measuring steady-state visual evoked potentials (SSVEPs) as an index of the neural contrast response in early visual areas. Methods: The experiment consisted of three consecutive stages: a pre-patching EEG recording (14 minutes), a monocular patching stage (2.5 hours) and a post-patching EEG recording (14 minutes; started immediately after the removal of the patch). During the patching stage, a diffuser (transmits light but not pattern) was placed in front of one randomly selected eye. During the EEG recording stage, contrast response functions for each eye were measured. Results: The neural responses from the patched eye increased after the removal of the patch, whilst the responses from the unpatched eye remained the same. Such phenomena occurred under both monocular and dichoptic viewing conditions. Conclusions: We interpret this eye dominance plasticity in adult human visual cortex as homeostatic intrinsic plasticity regulated by an increase of contrast-gain in the patched eye. PMID:26410580

  1. Relationship between monocularly deprivation and amblyopia rats and visual system development

    Institute of Scientific and Technical Information of China (English)

    Yu Ma

    2014-01-01

    Objective:To explore the changes of lateral geniculate body and visual cortex in monocular strabismus and form deprived amblyopic rat, and visual development plastic stage and visual plasticity in adult rats.Methods:A total of60SD rats ages13 d were randomly divided intoA, B,C three groups with20 in each group, groupA was set as the normal control group without any processing, groupB was strabismus amblyopic group, using the unilateral extraocular rectus resection to establish the strabismus amblyopia model, groupC was monocular form deprivation amblyopia group using unilateral eyelid edge resection+ lid suture.At visual developmental early phase(P25), meta phase(P35), late phase(P45) and adult phase(P120), the lateral geniculate body and visual cortex area17 of five rats in each group were exacted forC-fosImmunocytochemistry. Neuron morphological changes in lateral geniculate body and visual cortex was observed, the positive neurons differences ofC-fos expression induced by light stimulation was measured in each group, and the condition of radiation development ofP120 amblyopic adult rats was observed.Results:In groupsB andC,C-fos positive cells were significantly lower thanthe control group atP25(P0.05),C-fos protein positive cells level of groupB was significantly lower than that of groupA(P<0.05).The binoculusC-fos protein positive cells level of groupsB andC were significantly higher than that of control group atP35,P45 andP120 with statistically significant differences(P<0.05).Conclusions:The increasing ofC-fos expression in geniculate body and visual cortex neurons of adult amblyopia suggests the visual cortex neurons exist a certain degree of visual plasticity.

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

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    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.

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

    Science.gov (United States)

    1986-06-01

    experiment, Brown and Salinger (1975) found a decrease of the X-cell 2 population in the lateral geniculate body of the adult cat. These investigators...D.L., and Salinger , W.L., "Loss of X-Cells in Lateral Geniculate Nucleus with Monocular Paralysis. Neural Plasticity in the Adult Cat", Science, 189

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

    LENUS (Irish Health Repository)

    O'Neill, Evelyn C

    2012-02-01

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

  5. The perceived visual direction of monocular objects in random-dot stereograms is influenced by perceived depth and allelotropia.

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    Hariharan-Vilupuru, Srividhya; Bedell, Harold E

    2009-01-01

    The proposed influence of objects that are visible to both eyes on the perceived direction of an object that is seen by only one eye is known as the "capture of binocular visual direction". The purpose of this study was to evaluate whether stereoscopic depth perception is necessary for the "capture of binocular visual direction" to occur. In one pair of experiments, perceived alignment between two nearby monocular lines changed systematically with the magnitude and direction of horizontal but not vertical disparity. In four of the five observers, the effect of horizontal disparity on perceived alignment depended on which eye viewed the monocular lines. In additional experiments, the perceived alignment between the monocular lines changed systematically with the magnitude and direction of both horizontal and vertical disparities when the monocular line separation was increased from 1.1 degrees to 3.3 degrees . These results indicate that binocular capture depends on the perceived depth that results from horizontal retinal image disparity as well as allelotropia, or the averaging of local-sign information. Our data suggest that, during averaging, different weights are afforded to the local-sign information in the two eyes, depending on whether the separation between binocularly viewed targets is horizontal or vertical.

  6. Monocular SLAM for Visual Odometry: A Full Approach to the Delayed Inverse-Depth Feature Initialization Method

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    Rodrigo Munguía

    2012-01-01

    Full Text Available This paper describes in a detailed manner a method to implement a simultaneous localization and mapping (SLAM system based on monocular vision for applications of visual odometry, appearance-based sensing, and emulation of range-bearing measurements. SLAM techniques are required to operate mobile robots in a priori unknown environments using only on-board sensors to simultaneously build a map of their surroundings; this map will be needed for the robot to track its position. In this context, the 6-DOF (degree of freedom monocular camera case (monocular SLAM possibly represents the harder variant of SLAM. In monocular SLAM, a single camera, which is freely moving through its environment, represents the sole sensory input to the system. The method proposed in this paper is based on a technique called delayed inverse-depth feature initialization, which is intended to initialize new visual features on the system. In this work, detailed formulation, extended discussions, and experiments with real data are presented in order to validate and to show the performance of the proposal.

  7. c-FOS expression in the visual system of tree shrews after monocular inactivation.

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    Takahata, Toru; Kaas, Jon H

    2017-01-01

    Tree shrews possess an unusual segregation of ocular inputs to sublayers rather than columns in the primary visual cortex (V1). In this study, the lateral geniculate nucleus (LGN), superior colliculus (SC), pulvinar, and V1 were examined for changes in c-FOS, an immediate-early gene, expression after 1 or 24 hours of monocular inactivation with tetrodotoxin (TTX) in tree shrews. Monocular inactivation greatly reduced gene expression in LGN layers related to the blocked eye, whereas normally high to moderate levels were maintained in the layers that receive inputs from the intact eye. The SC and caudal pulvinar contralateral to the blocked eye had greatly (SC) or moderately (pulvinar) reduced gene expressions reflective of dependence on the contralateral eye. c-FOS expression in V1 was greatly reduced contralateral to the blocked eye, with most of the expression that remained in upper layer 4a and lower 4b and lower layer 6 regions. In contrast, much of V1 contralateral to the active eye showed normal levels of c-FOS expression, including the inner parts of sublayers 4a and 4b and layers 2, 3, and 6. In some cases, upper layer 4a and lower 4b showed a reduction of gene expression. Layers 5 and sublayer 3c had normally low levels of gene expression. The results reveal the functional dominance of the contralateral eye in activating the SC, pulvinar, and V1, and the results from V1 suggest that the sublaminar organization of layer 4 is more complex than previously realized. J. Comp. Neurol. 525:151-165, 2017. © 2016 Wiley Periodicals, Inc.

  8. Brief monocular deprivation as an assay of short-term visual sensory plasticity in schizophrenia – the binocular effect.

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    John J Foxe

    2013-12-01

    Full Text Available Background: Visual sensory processing deficits are consistently observed in schizophrenia, with clear amplitude reduction of the visual evoked potential (VEP during the initial 50-150 milliseconds of processing. Similar deficits are seen in unaffected first-degree relatives and drug-naïve first-episode patients, pointing to these deficits as potential endophenotypic markers. Schizophrenia is also associated with deficits in neural plasticity, implicating dysfunction of both glutamatergic and gabaergic systems. Here, we sought to understand the intersection of these two domains, asking whether short-term plasticity during early visual processing is specifically affected in schizophrenia. Methods: Brief periods of monocular deprivation induce relatively rapid changes in the amplitude of the early VEP – i.e. short-term plasticity. Twenty patients and twenty non-psychiatric controls participated. VEPs were recorded during binocular viewing, and were compared to the sum of VEP responses during brief monocular viewing periods (i.e. Left-eye + Right-eye viewing. Results: Under monocular conditions, neurotypical controls exhibited an effect that patients failed to demonstrate. That is, the amplitude of the summed monocular VEPs was robustly greater than the amplitude elicited binocularly during the initial sensory processing period. In patients, this binocular effect was absent. Limitations: Patients were all medicated. Ideally, this study would also include first-episode unmedicated patients.Conclusions: These results suggest that short-term compensatory mechanisms that allow healthy individuals to generate robust VEPs in the context of monocular deprivation are not effectively activated in patients with schizophrenia. This simple assay may provide a useful biomarker of short-term plasticity in the psychotic disorders and a target endophenotype for therapeutic interventions.

  9. Autoimmunity in visual loss.

    Science.gov (United States)

    Petzold, Axel; Wong, Sui; Plant, Gordon T

    2016-01-01

    There are a number of autoimmune disorders which can affect visual function. There are a very large number of mechanisms in the visual pathway which could potentially be the targets of autoimmune attack. In practice it is the retina and the anterior visual pathway (optic nerve and chiasm) that are recognised as being affected in autoimmune disorders. Multiple Sclerosis is one of the commonest causes of visual loss in young adults because of the frequency of attacks of optic neuritis in that condition, however the basis of the inflammation in Multiple Sclerosis and the confirmation of autoimmunity is lacking. The immune process is known to be highly unusual in that it is not systemic and confined to the CNS compartment. Previously an enigmatic partner to Multiple Sclerosis, Neuromyelitis Optica is now established to be autoimmune and two antibodies - to Aquaporin4 and to Myelin Oligodendrocyte Glycoprotein - have been implicated in the pathogenesis. The term Chronic Relapsing Inflammatory Optic Neuropathy is applied to those cases of optic neuritis which require long term immunosuppression and hence are presumed to be autoimmune but where no autoimmune pathogenesis has been confirmed. Optic neuritis occurring post-infection and post vaccination and conditions such as Systemic Lupus Erythematosus and various vasculitides may cause direct autoimmune attack to visual structures or indirect damage through occlusive vasculopathy. Chronic granulomatous disorders such as Sarcoidosis affect vision commonly by a variety of mechanisms, whether and how these are placed in the autoimmune panoply is unknown. As far as the retina is concerned Cancer Associated Retinopathy and Melanoma Associated Retinopathy are well characterised clinically but a candidate autoantibody (recoverin) is only described in the former disorder. Other, usually monophasic, focal retinal inflammatory disorders (Idiopathic Big Blind Spot Syndrome, Acute Zonal Occult Outer Retinopathy and Acute Macular

  10. P2-1: Visual Short-Term Memory Lacks Sensitivity to Stereoscopic Depth Changes but is Much Sensitive to Monocular Depth Changes

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    Hae-In Kang

    2012-10-01

    Full Text Available Depth from both binocular disparity and monocular depth cues presumably is one of most salient features that would characterize a variety of visual objects in our daily life. Therefore it is plausible to expect that human vision should be good at perceiving objects' depth change arising from binocular disparities and monocular pictorial cues. However, what if the estimated depth needs to be remembered in visual short-term memory (VSTM rather than just perceived? In a series of experiments, we asked participants to remember depth of items in an array at the beginning of each trial. A set of test items followed after the memory array, and the participants were asked to report if one of the items in the test array have changed its depth from the remembered items or not. The items would differ from each other in three different depth conditions: (1 stereoscopic depth under binocular disparity manipulations, (2 monocular depth under pictorial cue manipulations, and (3 both stereoscopic and monocular depth. The accuracy of detecting depth change was substantially higher in the monocular condition than in the binocular condition, and the accuracy in the both-depth condition was moderately improved compared to the monocular condition. These results indicate that VSTM benefits more from monocular depth than stereoscopic depth, and further suggests that storage of depth information into VSTM would require both binocular and monocular information for its optimal memory performance.

  11. Visual task performance using a monocular see-through head-mounted display (HMD) while walking.

    Science.gov (United States)

    Mustonen, Terhi; Berg, Mikko; Kaistinen, Jyrki; Kawai, Takashi; Häkkinen, Jukka

    2013-12-01

    A monocular see-through head-mounted display (HMD) allows the user to view displayed information while simultaneously interacting with the surrounding environment. This configuration lets people use HMDs while they are moving, such as while walking. However, sharing attention between the display and environment can compromise a person's performance in any ongoing task, and controlling one's gait may add further challenges. In this study, the authors investigated how the requirements of HMD-administered visual tasks altered users' performance while they were walking. Twenty-four university students completed 3 cognitive tasks (high- and low-working memory load, visual vigilance) on an HMD while seated and while simultaneously performing a paced walking task in a controlled environment. The results show that paced walking worsened performance (d', reaction time) in all HMD-administered tasks, but visual vigilance deteriorated more than memory performance. The HMD-administered tasks also worsened walking performance (speed, path overruns) in a manner that varied according to the overall demands of the task. These results suggest that people's ability to process information displayed on an HMD may worsen while they are in motion. Furthermore, the use of an HMD can critically alter a person's natural performance, such as their ability to guide and control their gait. In particular, visual tasks that involve constant monitoring of the HMD should be avoided. These findings highlight the need for careful consideration of the type and difficulty of information that can be presented through HMDs while still letting the user achieve an acceptable overall level of performance in various contexts of use. PsycINFO Database Record (c) 2013 APA, all rights reserved.

  12. Monocular Blindness: Is It a Handicap?

    Science.gov (United States)

    Knoth, Sharon

    1995-01-01

    Students with monocular vision may be in need of special assistance and should be evaluated by a multidisciplinary team to determine whether the visual loss is affecting educational performance. This article discusses the student's eligibility for special services, difficulty in performing depth perception tasks, difficulties in specific classroom…

  13. Adult Visual Experience Promotes Recovery of Primary Visual Cortex from Long-Term Monocular Deprivation

    Science.gov (United States)

    Fischer, Quentin S.; Aleem, Salman; Zhou, Hongyi; Pham, Tony A.

    2007-01-01

    Prolonged visual deprivation from early childhood to maturity is believed to cause permanent visual impairment. However, there have been case reports of substantial improvement of binocular vision in human adults following lifelong visual impairment or deprivation. These observations, together with recent findings of adult ocular dominance…

  14. Adult Visual Experience Promotes Recovery of Primary Visual Cortex from Long-Term Monocular Deprivation

    Science.gov (United States)

    Fischer, Quentin S.; Aleem, Salman; Zhou, Hongyi; Pham, Tony A.

    2007-01-01

    Prolonged visual deprivation from early childhood to maturity is believed to cause permanent visual impairment. However, there have been case reports of substantial improvement of binocular vision in human adults following lifelong visual impairment or deprivation. These observations, together with recent findings of adult ocular dominance…

  15. Comparison of the monocular Humphrey visual field and the binocular Humphrey esterman visual field test for driver licensing in glaucoma subjects in Sweden

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    Ayala Marcelo

    2012-08-01

    Full Text Available Abstract Background The purpose of this study was to compare the monocular Humphrey Visual Field (HVF with the binocular Humphrey Esterman Visual Field (HEVF for determining whether subjects suffering from glaucoma fulfilled the new medical requirements for possession of a Swedish driver’s license. Methods HVF SITA Fast 24–2 full threshold (monocularly and HEVF (binocularly were performed consecutively on the same day on 40 subjects with glaucomatous damage of varying degrees in both eyes. Assessment of results was constituted as either “pass” or “fail”, according to the new medical requirements put into effect September 1, 2010 by the Swedish Transport Agency. Results Forty subjects were recruited and participated in the study. Sixteen subjects passed both tests, and sixteen subjects failed both tests. Eight subjects passed the HEFV but failed the HVF. There was a significant difference between HEVF and HVF (χ2, p = 0.004. There were no subjects who passed the HVF, but failed the HEVF. Conclusions The monocular visual field test (HVF gave more specific information about the location and depth of the defects, and therefore is the overwhelming method of choice for use in diagnostics. The binocular visual field test (HEVF seems not be as efficient as the HVF in finding visual field defects in glaucoma subjects, and is therefore doubtful in evaluating visual capabilities in traffic situations.

  16. Comparison of the monocular Humphrey Visual Field and the binocular Humphrey Esterman Visual Field test for driver licensing in glaucoma subjects in Sweden.

    Science.gov (United States)

    Ayala, Marcelo

    2012-08-02

    The purpose of this study was to compare the monocular Humphrey Visual Field (HVF) with the binocular Humphrey Esterman Visual Field (HEVF) for determining whether subjects suffering from glaucoma fulfilled the new medical requirements for possession of a Swedish driver's license. HVF SITA Fast 24-2 full threshold (monocularly) and HEVF (binocularly) were performed consecutively on the same day on 40 subjects with glaucomatous damage of varying degrees in both eyes. Assessment of results was constituted as either "pass" or "fail", according to the new medical requirements put into effect September 1, 2010 by the Swedish Transport Agency. Forty subjects were recruited and participated in the study. Sixteen subjects passed both tests, and sixteen subjects failed both tests. Eight subjects passed the HEFV but failed the HVF. There was a significant difference between HEVF and HVF (χ(2), p = 0.004). There were no subjects who passed the HVF, but failed the HEVF. The monocular visual field test (HVF) gave more specific information about the location and depth of the defects, and therefore is the overwhelming method of choice for use in diagnostics. The binocular visual field test (HEVF) seems not be as efficient as the HVF in finding visual field defects in glaucoma subjects, and is therefore doubtful in evaluating visual capabilities in traffic situations.

  17. 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.

  18. TrkA activation in the rat visual cortex by antirat trkA IgG prevents the effect of monocular deprivation.

    Science.gov (United States)

    Pizzorusso, T; Berardi, N; Rossi, F M; Viegi, A; Venstrom, K; Reichardt, L F; Maffei, L

    1999-01-01

    It has been recently shown that intraventricular injections of nerve growth factor (NGF) prevent the effects of monocular deprivation in the rat. We have tested the localization and the molecular nature of the NGF receptor(s) responsible for this effect by activating cortical trkA receptors in monocularly deprived rats by cortical infusion of a specific agonist of NGF on trkA, the bivalent antirat trkA IgG (RTA-IgG). TrkA protein was detected by immunoblot in the rat visual cortex during the critical period. Rats were monocularly deprived for 1 week (P21-28) and RTA-IgG or control rabbit IgG were delivered by osmotic minipumps. The effects of monocular deprivation on the ocular dominance of visual cortical neurons were assessed by extracellular single cell recordings. We found that the shift towards the ipsilateral, non-deprived eye was largely prevented by RTA-IgG. Infusion of RTA-IgG combined with antibody that blocks p75NTR (REX), slightly reduced RTA-IgG effectiveness in preventing monocular deprivation effects. These results suggest that NGF action in visual cortical plasticity is mediated by cortical TrkA receptors with p75NTR exerting a facilitatory role.

  19. Visual loss after spine surgery

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    Kapil Mohan

    2012-01-01

    Full Text Available Incidence of perioperative visual loss ranges from 0.06% to 0.2% with the most common cause as ischemic optic neuropathy. We report one-year follow up of a 50-years-old hypertensive housewife who underwent lumbar decompression and fusion for degenerative scoliosis, but woke up with painless unilateral visual loss. Fundus examination was normal. Her visual acuity improved from initial finger counting close to face to finger counting at 3 m at 1 year. Identification of high risk patients may help in appropriate preoperative counselling, prevention and early recognition of this devastating complication.

  20. Monocular inhibition reveals temporal and spatial changes in gene expression in the primary visual cortex of marmoset.

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    Yuki eNakagami

    2013-04-01

    Full Text Available We investigated the time course of the expression of several activity-dependent genes evoked by visual inputs in the primary visual cortex (V1 in adult marmosets. In order to examine the rapid time course of activity-dependent gene expression, marmosets were first monocularly inactivated by tetrodotoxin (TTX, kept in darkness for two days, and then exposed to various length of light stimulation. Activity-dependent genes including HTR1B, HTR2A, whose activity-dependency were previously reported by us, and well-known immediate early genes (IEGs, c-FOS, ZIF268, and ARC, were examined by in situ hybridization. Using this system, first, we demonstrated the ocular dominance type of gene expression pattern in V1 under this condition. IEGs were expressed in columnar patterns throughout layers II-VI of all the tested monocular marmosets. Second, we showed the regulation of HTR1B and HTR2A expressions by retinal spontaneous activity, because HTR1B and HTR2A mRNA expressions sustained a certain level regardless of visual stimulation and were inhibited by a blockade of the retinal activity with TTX. Third, IEGs dynamically changed its laminar distribution from half an hour to several hours upon a stimulus onset with the unique time course for each gene. The expression patterns of these genes were different in neurons of each layer as well. These results suggest that the regulation of each neuron in the primary visual cortex of marmosets is subjected to different regulation upon the change of activities from retina. It should be related to a highly differentiated laminar structure of primate visual systems, reflecting the functions of the activity-dependent gene expression in marmoset V1.

  1. Recovery of neurofilament following early monocular deprivation

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    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.

  2. Peculiarities of vernier monocular and binocular visual acuity in the retinal orthogonal meridians in patients with hypermetropic astigmatism

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    Владимир Александрович Коломиец

    2015-06-01

    Full Text Available It was carried out an examination of meridional vernier visual acuity in 100 patients 7-25 years old with a simple and compound hypermetropic astigmatism and refractive ambyiopia. An astigmatic component of refraction was in range 0,5- 2,5 dptr. Visual acuity on the sighting eyes after correction was 0,9- 1,0, on eyes with amblyopia 0,4 - 0,85 relative units.Methods. Visual acuity was defined by the Landolt rings of Sivtsev table. Vernier visual acuity was defined in seconds of arc from 5 km, using special computer program.Result. It was demonstrated that in patients with the simple hypertropic astigmatism diagnosis of meridional amblyopia can be specified by the comparison of data of monocular and binocular vernier visual acuity in orthogonal meridians of retinas.Conclusions. An effect of the rise of meridional binocular visual acuity in one of meridians and its absence in another one allows define selective meridional disturbances of the visual acuity

  3. TrkA activation in the rat visual cortex by antirat trkA IgG prevents the effect of monocular deprivation

    OpenAIRE

    Pizzorusso, Tommaso; Berardi, Nicoletta; Rossi, Francesco M.; Viegi, Alessandro; Venstrom, Kristine; Reichardt, Louis F.; Maffei, Lamberto

    1999-01-01

    It has been recently shown that intraventricular injections of nerve growth factor (NGF) prevent the effects of monocular deprivation in the rat. We have tested the localization and the molecular nature of the NGF receptor(s) responsible for this effect by activating cortical trkA receptors in monocularly deprived rats by cortical infusion of a specific agonist of NGF on trkA, the bivalent antirat trkA IgG (RTA-IgG). TrkA protein was detected by immunoblot in the rat visual cortex during the ...

  4. mRNAs coding for neurotransmitter receptors and voltage-gated sodium channels in the adult rabbit visual cortex after monocular deafferentiation

    Science.gov (United States)

    Nguyen, Quoc-Thang; Matute, Carlos; Miledi, Ricardo

    1998-01-01

    It has been postulated that, in the adult visual cortex, visual inputs modulate levels of mRNAs coding for neurotransmitter receptors in an activity-dependent manner. To investigate this possibility, we performed a monocular enucleation in adult rabbits and, 15 days later, collected their left and right visual cortices. Levels of mRNAs coding for voltage-activated sodium channels, and for receptors for kainate/α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA), N-methyl-d-aspartate (NMDA), γ-aminobutyric acid (GABA), and glycine were semiquantitatively estimated in the visual cortices ipsilateral and contralateral to the lesion by the Xenopus oocyte/voltage-clamp expression system. This technique also allowed us to study some of the pharmacological and physiological properties of the channels and receptors expressed in the oocytes. In cells injected with mRNA from left or right cortices of monocularly enucleated and control animals, the amplitudes of currents elicited by kainate or AMPA, which reflect the abundance of mRNAs coding for kainate and AMPA receptors, were similar. There was no difference in the sensitivity to kainate and in the voltage dependence of the kainate response. Responses mediated by NMDA, GABA, and glycine were unaffected by monocular enucleation. Sodium channel peak currents, activation, steady-state inactivation, and sensitivity to tetrodotoxin also remained unchanged after the enucleation. Our data show that mRNAs for major neurotransmitter receptors and ion channels in the adult rabbit visual cortex are not obviously modified by monocular deafferentiation. Thus, our results do not support the idea of a widespread dynamic modulation of mRNAs coding for receptors and ion channels by visual activity in the rabbit visual system. PMID:9501250

  5. 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.

  6. Effect of field of view and monocular viewing on angular size judgements in an outdoor scene

    Science.gov (United States)

    Denz, E. A.; Palmer, E. A.; Ellis, S. R.

    1980-01-01

    Observers typically overestimate the angular size of distant objects. Significantly, overestimations are greater in outdoor settings than in aircraft visual-scene simulators. The effect of field of view and monocular and binocular viewing conditions on angular size estimation in an outdoor field was examined. Subjects adjusted the size of a variable triangle to match the angular size of a standard triangle set at three greater distances. Goggles were used to vary the field of view from 11.5 deg to 90 deg for both monocular and binocular viewing. In addition, an unrestricted monocular and binocular viewing condition was used. It is concluded that neither restricted fields of view similar to those present in visual simulators nor the restriction of monocular viewing causes a significant loss in depth perception in outdoor settings. Thus, neither factor should significantly affect the depth realism of visual simulators.

  7. Binocularity in the little owl, Athene noctua. II. Properties of visually evoked potentials from the Wulst in response to monocular and binocular stimulation with sine wave gratings.

    Science.gov (United States)

    Porciatti, V; Fontanesi, G; Raffaelli, A; Bagnoli, P

    1990-01-01

    Visually evoked potentials (VEPs) have been recorded from the Wulst surface of the little owl, Athene noctua, in response to counterphase-reversal of sinusoidal gratings with different contrast, spatial frequency and mean luminance, presented either monocularly or binocularly. Monocular full-field stimuli presented to either eye evoked VEPs of similar amplitude, waveform and latency. Under binocular viewing, VEPs approximately doubled in amplitude without waveform changes. VEPs with similar characteristics could be obtained in response to stimulation of the contralateral, but not ipsilateral, hemifield. These results suggest that a 50% recrossing occurs in thalamic efferents and that different ipsilateral and contralateral regions converge onto the same Wulst sites. The VEP amplitude progressively decreased with increase of the spatial frequency beyond 2 cycles/degree, and the high spatial frequency cut-off (VEP acuity) was under binocular viewing (8 cycles/degree) higher than under monocular (5 cycles/degree) viewing (200 cd/m2, 45% contrast). The VEP acuity increased with increase in the contrast and decreased with reduction of the mean luminance. The binocular gain in both VEP amplitude and VEP acuity was largest at the lowest luminance levels. Binocular VEP summation occurred in the medium-high contrast range. With decreased contrast, both monocular and binocular VEPs progressively decreased in amplitude and tended to the same contrast threshold. The VEP contrast threshold depended on the spatial frequency (0.6-1.8% in the range 0.12-2 cycles/degree). Binocular VEPs often showed facilitatory interaction (binocular/monocular amplitude ratio greater than 2), but the binocular VEP amplitude did not change either by changing the stimulus orientation (horizontal vs. vertical gratings) or by inducing different retinal disparities.(ABSTRACT TRUNCATED AT 250 WORDS)

  8. 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.

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

    Science.gov (United States)

    2004-01-01

    41), it is clear that the controller developed in the previous section can not be applied to solve the regulation problem . In this section, an...extension is presented to illustrate how a visual servo controller can be developed to solve the regulation problem for the fixed camera configuration. To

  10. 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.

  11. A novel monocular visual navigation method for cotton-picking robot based on horizontal spline segmentation

    Science.gov (United States)

    Xu, ShengYong; Wu, JuanJuan; Zhu, Li; Li, WeiHao; Wang, YiTian; Wang, Na

    2015-12-01

    Visual navigation is a fundamental technique of intelligent cotton-picking robot. There are many components and cover in the cotton field, which make difficulties of furrow recognition and trajectory extraction. In this paper, a new field navigation path extraction method is presented. Firstly, the color image in RGB color space is pre-processed by the OTSU threshold algorithm and noise filtering. Secondly, the binary image is divided into numerous horizontally spline areas. In each area connected regions of neighboring images' vertical center line are calculated by the Two-Pass algorithm. The center points of the connected regions are candidate points for navigation path. Thirdly, a series of navigation points are determined iteratively on the principle of the nearest distance between two candidate points in neighboring splines. Finally, the navigation path equation is fitted by the navigation points using the least squares method. Experiments prove that this method is accurate and effective. It is suitable for visual navigation in the complex environment of cotton field in different phases.

  12. 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.

  13. Reversible monocular cataract simulating amaurosis fugax.

    Science.gov (United States)

    Paylor, R R; Selhorst, J B; Weinberg, R S

    1985-07-01

    In a patient having brittle, juvenile-onset diabetes, transient monocular visual loss occurred repeatedly whenever there were wide fluctuations in serum glucose. Amaurosis fugax was suspected. The visual loss differed, however, in that it persisted over a period of hours to several days. Direct observation eventually revealed that the relatively sudden change in vision of one eye was associated with opacification of the lens and was not accompanied by an afferent pupillary defect. Presumably, a hyperosmotic gradient had developed with the accumulation of glucose and sorbitol within the lens. Water was drawn inward, altering the composition of the lens fibers and thereby lowering the refractive index, forming a reversible cataract. Hypoglycemia is also hypothesized to have played a role in the formation of a higher osmotic gradient. The unilaterality of the cataract is attributed to variation in the permeability of asymmetric posterior subcapsular cataracts.

  14. Atypical visual loss in giant cell arteritis

    DEFF Research Database (Denmark)

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

    1994-01-01

    in the terminal stage of his disease due to bilateral occipital cortex infarctions, verified by CT-scan. Autopsy revealed involvement of several intracranial arteries. In case No. 2 there was severe unilateral visual loss and cotton-wool exudates in both eyes. Central vision recovered after corticosteroid therapy......; in our experience this is unusual. In case No. 3 irreversible unilateral visual loss was typical for GCA, but the association with polyneuropathy unique. Neurological remission coincided with systemic corticosteroid therapy....

  15. Occipital seizures presenting with bilateral visual loss

    Directory of Open Access Journals (Sweden)

    Hadjikoutis S

    2003-01-01

    Full Text Available Transient visual loss may occur with occipital seizures as an ictal or post-ictal phenomenon. Its duration varies from less than one minute to days, or can be permanent. We describe a 61-year-old man presenting with headache, vomiting and bilateral visual loss. EEG revealed persistent spike discharge in the occipital lobes suggesting occipital seizures. His vision improved with carbamazepine.

  16. Adaptation to Retinal Injury and Visual Loss

    Science.gov (United States)

    1994-06-20

    foveal visual loss is associated reading andincreasedeye fixation duration (Rayner with retinal diseases like macular degeneration or and Bertera, 1979...to visual loss. ൖ. SUBJECT TERMS 15. NUMBER OF PAGES Scotoma, Fovea, Vision, Rehabilitation , Laser, Human 16. PRICE CODE 17. 3ECLRITY...1990) further deter- might be used to explain the left right asymmetry, mined that macular disease scotomasof 5, 10,or2O such as, left-right biases from

  17. Monocular indoor localization techniques for smartphones

    Directory of Open Access Journals (Sweden)

    Hollósi Gergely

    2016-12-01

    Full Text Available In the last decade huge research work has been put to the indoor visual localization of personal smartphones. Considering the available sensor capabilities monocular odometry provides promising solution, even reecting requirements of augmented reality applications. This paper is aimed to give an overview of state-of-the-art results regarding monocular visual localization. For this purpose essential basics of computer vision are presented and the most promising solutions are reviewed.

  18. Reduced responsiveness to long-term monocular deprivation of parvalbumin neurons assessed by c-Fos staining in rat visual cortex.

    Directory of Open Access Journals (Sweden)

    Marco Mainardi

    Full Text Available BACKGROUND: It is generally assumed that visual cortical cells homogeneously shift their ocular dominance (OD in response to monocular deprivation (MD, however little experimental evidence directly supports this notion. By using immunohistochemistry for the activity-dependent markers c-Fos and Arc, coupled with staining for markers of inhibitory cortical sub-populations, we studied whether long-term MD initiated at P21 differentially affects visual response of inhibitory neurons in rat binocular primary visual cortex. METHODOLOGY/PRINCIPAL FINDINGS: The inhibitory markers GAD67, parvalbumin (PV, calbindin (CB and calretinin (CR were used. Visually activated Arc did not colocalize with PV and was discarded from further studies. MD decreased visually induced c-Fos activation in GAD67 and CR positive neurons. The CB population responded to MD with a decrease of CB expression, while PV cells did not show any effect of MD on c-Fos expression. The persistence of c-Fos expression induced by deprived eye stimulation in PV cells is not likely to be due to a particularly low threshold for activity-dependent c-Fos induction. Indeed, c-Fos induction by increasing concentrations of the GABAA antagonist picrotoxin in visual cortical slices was similar between PV cells and the other cortical neurons. CONCLUSION: These data indicate that PV cells are particularly refractory to MD, suggesting that different cortical subpopulation may show different response to MD.

  19. Visual loss after spine surgery: Case report.

    Science.gov (United States)

    Cobar-Bustamante, Andrés E; Cahueque, Mario A; Caldera, Gustavo

    2016-12-01

    The presence of postoperative visual loss is a well-known complication, and described in various reports, its low incidence (0.028-0.2%) makes it extremely rare. Two main causes have been determined: Posterior Ischemic Optic Neuropathy and central Retinal Artery Oclusion. The following is a case report of a 52-year-old patient that presented visual loss after elective spine surgery that had no complications that could initially explain this complication. Studies were performed and evaluations by ophthalmologists determined that the cause of Posterior Ischemic Optic Neuropathy due to multiple risk factors that the patient had previously and during the surgery. After 3 year follow-up the patient still has total visual loss and no other complications were reported.

  20. Monocular deprivation delays the dynamic changes of phosphorylated synapsin Ia/b at site-1 in contralateral visual cortex of juvenile mice.

    Science.gov (United States)

    Fu, Tao; Su, Qing; Xi, Ping; Han, Song; Li, Junfa

    2015-03-01

    Synapsins as a family of presynaptic terminal phosphoprotein participates in neuronal development, but their role in the synaptic plasticity of visual cortex is unclear. In this study, the impact of monocular deprivation (MD) on dynamic changes of isoform-specific protein expression and site 1 phosphorylation of synapsins in visual cortex of the postnatal mice were observed by using the technique of Western blot analysis. The results showed that the total (T-) protein levels of synapsins including the isoform of Ia/b, IIa/b and IIIa were about 21-26% of adult level in visual cortex of mice at postnatal 7 days (P7), and then the T-synapsin Ia/b and IIb could quickly reach adult level at P35. However, the T-synapsin IIa and IIIa increased more slowly (71-74% at P35), and then kept increasing in the visual cortex of mice at P60. Unlike to the changes of T-synapsins, the level of phosphorylated (P-) synapsin Ia/b (not IIa/b and IIIa) at site 1 increased with development to the highest level at P21, and then decreased rapidly to a low level in visual cortex of mice at P35-60. In addition, we found that the levels of P-synapsin Ia/b increased significantly in left visual cortex of P28 and P35 (not P21 and P42) mice with 1-week MD of right eye; and no significant changes of T-synapsins were observed in both left and right sides of visual cortex in P21-42 mice with MD treatment. These results suggested that the isoform-specific protein expression and site-1 phosphorylation of synapsins might play a different role in the synaptic plasticity of visual cortex, and MD delays the dynamic changes of phosphorylated synapsin Ia/b at site-1 in contralateral visual cortex of juvenile mice.

  1. Perioperative visual loss after spine surgery.

    Science.gov (United States)

    Nickels, Travis J; Manlapaz, Mariel R; Farag, Ehab

    2014-04-18

    Perioperative visual loss (POVL) is an uncommon, but devastating complication that remains primarily associated with spine and cardiac surgery. The incidence and mechanisms of visual loss after surgery remain difficult to determine. According to the American Society of Anesthesiologists Postoperative Visual Loss Registry, the most common causes of POVL in spine procedures are the two different forms of ischemic optic neuropathy: anterior ischemic optic neuropathy and posterior ischemic optic neuropathy, accounting for 89% of the cases. Retinal ischemia, cortical blindness, and posterior reversible encephalopathy are also observed, but in a small minority of cases. A recent multicenter case control study has identified risk factors associated with ischemic optic neuropathy for patients undergoing prone spinal fusion surgery. These include obesity, male sex, Wilson frame use, longer anesthetic duration, greater estimated blood loss, and decreased percent colloid administration. These risk factors are thought to contribute to the elevation of venous pressure and interstitial edema, resulting in damage to the optic nerve by compression of the vessels that feed the optic nerve, venous infarction or direct mechanical compression. This review will expand on these findings as well as the recently updated American Society of Anesthesiologists practice advisory on POVL. There are no effective treatment options for POVL and the diagnosis is often irreversible, so efforts must focus on prevention and risk factor modification. The role of crystalloids versus colloids and the use of α-2 agonists to decrease intraocular pressure during prone spine surgery will also be discussed as a potential preventative strategy.

  2. 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

  3. Syndromes of hearing loss associated with visual loss.

    Science.gov (United States)

    Abou-Elhamd, Kamal Ahmed; ElToukhy, Hesham Mohamed; Al-Wadaani, Fahad Abdullah

    2014-04-01

    Patients with hearing loss depend more on their vision on their communication and vice versa. ENT physician faces difficult situation when he or she consults a patient complaining of hearing loss with a problem of vision. The prevalence of ophthalmic abnormalities in deaf population is also higher compared to their hearing peers. This paper is to summarize the common syndromes associated with visual defect according to the site of affection in the eye. Review article. Syndromes which result in deaf blind person are different among adults compared to among children. Rubella syndrome and Down syndrome are the main causes of deaf blind people above 18 years of age. While in children, CHARGE syndrome is the main cause of deaf blind children. ENT physician should be aware of these syndromes for earlier detection of deaf blind persons. Deaf blind people need a great deal of help. Communication and education are crucial for them and need to be properly supported.

  4. Monocular denervation of visual nuclei modulates APP processing and sAPPα production: A possible role on neural plasticity.

    Science.gov (United States)

    Vasques, Juliana Ferreira; Heringer, Pedro Vinícius Bastos; Gonçalves, Renata Guedes de Jesus; Campello-Costa, Paula; Serfaty, Claudio Alberto; Faria-Melibeu, Adriana da Cunha

    2017-08-01

    Amyloid precursor protein (APP) is essential to physiological processes such as synapse formation and neural plasticity. Sequential proteolysis of APP by beta- and gamma-secretases generates amyloid-beta peptide (Aβ), the main component of senile plaques in Alzheimer Disease. Alternative APP cleavage by alpha-secretase occurs within Aβ domain, releasing soluble α-APP (sAPPα), a neurotrophic fragment. Among other functions, sAPPα is important to synaptogenesis, neural survival and axonal growth. APP and sAPPα levels are increased in models of neuroplasticity, which suggests an important role for APP and its metabolites, especially sAPPα, in the rearranging brain. In this work we analyzed the effects of monocular enucleation (ME), a classical model of lesion-induced plasticity, upon APP content, processing and also in secretases levels. Besides, we addressed whether α-secretase activity is crucial for retinotectal remodeling after ME. Our results showed that ME induced a transient reduction in total APP content. We also detected an increase in α-secretase expression and in sAPP production concomitant with a reduction in Aβ and β-secretase contents. These data suggest that ME facilitates APP processing by the non-amyloidogenic pathway, increasing sAPPα levels. Indeed, the pharmacological inhibition of α-secretase activity reduced the axonal sprouting of ipsilateral retinocollicular projections from the intact eye after ME, suggesting that sAPPα is necessary for synaptic structural rearrangement. Understanding how APP processing is regulated under lesion conditions may provide new insights into APP physiological role on neural plasticity. Copyright © 2017 ISDN. Published by Elsevier Ltd. All rights reserved.

  5. A Research on Monocular Visual SLAM Based on SURF Feature%基于SURF特征的单目视觉SLAM方法研究∗

    Institute of Scientific and Technical Information of China (English)

    胡衡; 梁岚珍

    2015-01-01

    Because the visual information is easily affected by external environment factors, therefore the selected feature points of mobile robot based on visual simultaneous localization and map building requires high stability and good robustness. For the problem of monocular visual mobile robot SLAM(Simultaneous Localization and Mapping),a kind of mono-SLAM algorithm based on Extended kalman filter is proposed by using SURF(Speed Up Robust Features) feature points and the inverse depth method. The process of SLAM is completed by fusing the information of SURF features and robot information with EKF. The result of simulation experiment indicates that the proposed algorithm is feasible, and with high localization precision in indoor structured environment.%由于视觉信息很容易受到外界环境因素的影响,因此基于视觉的移动机器人同步定位与地图构建问题所选取的特征点要求具有较高的精确度和良好的鲁棒性。针对单目SLAM问题,提出一种基于扩展卡尔曼滤波器的单目视觉SLAM算法。该算法采用SURF特征点,结合反向深度估计法,应用扩展卡尔曼滤波器融合SURF特征信息与机器人位姿信息完成SLAM过程。仿真实验结果表明,在未知室内结构化环境下,该算法运行可靠,定位精度高。

  6. 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

  7. [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.

  8. 单目视觉里程计/惯性组合导航算法%Algorithm for monocular visual Odometry/SINS integrated navigation

    Institute of Scientific and Technical Information of China (English)

    冯国虎; 吴文启; 曹聚亮; 宋敏

    2011-01-01

    A new algorithm is presented for monocular visual odometry/SINS integrated navigation,in which the camera attitude is provided by the SINS other than visual estimation.The low accuracy of visual attitude estimation which would cause much error for long-range navigation is avoided.After registration and time synchronization,the velocity computation difference between SINS and visual odometry is chosen as observation of integrated navigation.A Kalman filter is used to correct the integrated navigation error including the visual odometry scale factor error.The 22 m indoor and 1412 m outdoor navigation experiments show that the position errors are 3.2% and 4.0% respectively.It can be seen that,compared with Clark's method in which camera attitude estimation is updated periodically with attitude sensors,the proposed algorithm is more accurate and robust with low rate of error growth.The proposed algorithm can be applied to the autonomous navigation of walking robots or wheeled mobile robots in case of serious wheel slip in complex terrain.%提出一种单目视觉里程计/捷联惯性组合导航定位算法.与视觉里程计估计相机姿态不同,惯导系统连续提供相机拍摄时刻对应的三维姿态,克服了单纯由视觉估计相机姿态精度低造成的长距离导航误差大的问题.通过配准和时间同步,用惯导系统解算的速度和视觉里程计计算的速度之差作为组合导航的观测量,采用Kalman滤波修正组合导航系统的误差,同时估计视觉里程计标度因数误差.分别在室内外不同环境下进行了22 m的推车实验和1412m的跑车实验,定位误差分别为3.2%和4.0%.与Clark采用姿态传感器定期更新相机姿态估计结果的方法相比,单目视觉里程计/惯性组合导航定位精度更高,定位误差随距离增长率低,适合步行机器人或轮式移动机器人在复杂地形环境下车轮严重打滑时的自主定位导航.

  9. Localization of monocular stimuli in different depth planes.

    Science.gov (United States)

    Shimono, Koichi; Tam, Wa James; Asakura, Nobuhiko; Ohmi, Masao

    2005-09-01

    We examined the phenomenon in which two physically aligned monocular stimuli appear to be non-collinear when each of them is located in binocular regions that are at different depth planes. Using monocular bars embedded in binocular random-dot areas that are at different depths, we manipulated properties of the binocular areas and examined their effect on the perceived direction and depth of the monocular stimuli. Results showed that (1) the relative visual direction and perceived depth of the monocular bars depended on the binocular disparity and the dot density of the binocular areas, and (2) the visual direction, but not the depth, depended on the width of the binocular regions. These results are consistent with the hypothesis that monocular stimuli are treated by the visual system as binocular stimuli that have acquired the properties of their binocular surrounds. Moreover, partial correlation analysis suggests that the visual system utilizes both the disparity information of the binocular areas and the perceived depth of the monocular bars in determining the relative visual direction of the bars.

  10. Visual loss with papilledema in Guillain-Barre syndrome.

    Directory of Open Access Journals (Sweden)

    Kharbanda P

    2002-10-01

    Full Text Available Papilledema and raised intracranial pressure have been reported in association with Guillain-Barre syndrome. Papilledema is usually asympotomatic or associated with mild visual field defects, without any visual loss. The cerebrospinal fluid protein is usually reported to be high. A case of a 35 year old lady is reported, who presented with headache, diplopia and progressive visual loss in both eyes and limb weakness with hyporeflexia. Optic fundus examination showed bilateral papilledema. She had features of pseudotumor cerebri. Nerve conduction studies were suggestive of polyradiculopathy. The unusual things in this case, were the profound visual loss normal cerebrospinal fluid profiles and the presentation of papilledema before the limb weakness.

  11. Loss of vision: imaging the visual pathways

    Energy Technology Data Exchange (ETDEWEB)

    Jaeger, H.R. [Institute of Neurology, Lysholm Department of Neuroradiology, London (United Kingdom)

    2005-03-01

    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.)

  12. Monocular transparency generates quantitative depth.

    Science.gov (United States)

    Howard, Ian P; Duke, Philip A

    2003-11-01

    Monocular zones adjacent to depth steps can create an impression of depth in the absence of binocular disparity. However, the magnitude of depth is not specified. We designed a stereogram that provides information about depth magnitude but which has no disparity. The effect depends on transparency rather than occlusion. For most subjects, depth magnitude produced by monocular transparency was similar to that created by a disparity-defined depth probe. Addition of disparity to monocular transparency did not improve the accuracy of depth settings. The magnitude of depth created by monocular occlusion fell short of that created by monocular transparency.

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

    Directory of Open Access Journals (Sweden)

    Diederick C Niehorster

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

  14. Identifying preperimetric functional loss in glaucoma: a blue-on-yellow multifocal visual evoked potentials study.

    Science.gov (United States)

    Arvind, Hemamalini; Graham, Stuart; Leaney, John; Grigg, John; Goldberg, Ivan; Billson, Frank; Klistorner, Alexander

    2009-06-01

    To determine the ability of blue-on-yellow multifocal visual evoked potentials (BonY mfVEP) to identify functional loss in preperimetric glaucoma. Prospective case series. Thirty patients with glaucomatous optic discs and normal standard visual fields. All patients underwent BonY mfVEP, dilated optic disc stereophotography, and optical coherence tomography (Fast RNFL protocol). Optic disc photographs were assessed by 2 independent examiners in a masked fashion. The mfVEP amplitude asymmetry and latency values were analyzed and compared topographically with findings of disc assessment. Average retinal nerve fiber layer (RNFL) thickness, RNFL asymmetry, and sectors with RNFL thinning were compared between patients with and without mfVEP defects. Fourteen (46.7%) patients demonstrated significant abnormality on amplitude asymmetry deviation plots of BonY mfVEP. In all 14 cases, the defect was monocular and corresponded to the eye with the worse disc. In 13 of 14 patients, the defect also corresponded to the location of the worst affected rim. Average RNFL thickness of eyes with mfVEP defects was 81.2+/-9.9 microm, significantly lower than that of patients without defects (90+/-10.5 microm; P = 0.035). Mean asymmetry of RNFL (better minus worse eye) also was significantly higher for patients with mfVEP defects compared with those without such defects (9.0+/-6.4 microm vs. 3.0+/-7 microm; P = 0.03). Average latency of both eyes of glaucomatous patients was delayed compared with that of controls, with no difference in latency between worse and better eyes of glaucoma patients. There was no association of latency delay with either the location of disc changes or mfVEP amplitude defects. Amplitude asymmetry of the BonY mfVEP seems to be a promising tool to identify functional loss in preperimetric glaucoma. Proprietary or commercial disclosure may be found after the references.

  15. 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…

  16. Blood Loss Estimation Using Gauze Visual Analogue

    OpenAIRE

    Ali Algadiem; Aleisa; Alsubaie; Buhlaiqah; Algadeeb; Alsneini

    2016-01-01

    Background Estimating intraoperative blood loss can be a difficult task, especially when blood is mostly absorbed by gauze. In this study, we have provided an improved method for estimating blood absorbed by gauze. Objectives To develop a guide to estimate blood absorbed by surgical gauze. Materials and Methods A clinical experiment was conducted using aspirated blood and common su...

  17. Visual acuity and pattern of visual field loss at presentation in pituitary adenoma.

    Science.gov (United States)

    Ogra, Siddharth; Nichols, Andrew D; Stylli, Stanley; Kaye, Andrew H; Savino, Peter J; Danesh-Meyer, Helen V

    2014-05-01

    Our purpose was to analyse the demographics, prevalence and pattern of visual field defects in patients with pituitary adenoma. We prospectively recruited 103 consecutive patients (206 eyes) presenting to a neurosurgical unit with pituitary adenoma. Ophthalmological examination and standard automated perimetry (Humphrey, 24-2 threshold) was performed. Severity of visual field defects was also assessed. The mean population age was 53.9 years (standard deviation=15). Visual loss was the most common reason for presentation (39%) followed by endocrine abnormality (21%) and headache (15%). Patients with endocrine abnormality on presentation were 10.9 years younger than those presenting with visual loss (p=0.001). Bitemporal defects were the most prevalent pattern (n=22, 41%) followed by homonymous defects (n=7, 13%). Of the patients with visual field loss, 33% had unilateral visual field defects. The mean visual acuity in those with bitemporal defects was 6/7.5 with half of these patients having 6/6 vision in both eyes. In conclusion, the majority of patients with pituitary adenoma have visual acuity better than 6/7.5 despite having visual field defects. While a bitemporal pattern of visual field loss is the most common, a significant proportion of patients had unilateral and altitudinal defects. Assessment of the visual field is essential to rule out chiasmal compression.

  18. Monocular alignment in different depth planes.

    Science.gov (United States)

    Shimono, Koichi; Wade, Nicholas J

    2002-04-01

    We examined (a) whether vertical lines at different physical horizontal positions in the same eye can appear to be aligned, and (b), if so, whether the difference between the horizontal positions of the aligned vertical lines can vary with the perceived depth between them. In two experiments, each of two vertical monocular lines was presented (in its respective rectangular area) in one field of a random-dot stereopair with binocular disparity. In Experiment 1, 15 observers were asked to align a line in an upper area with a line in a lower area. The results indicated that when the lines appeared aligned, their horizontal physical positions could differ and the direction of the difference coincided with the type of disparity of the rectangular areas; this is not consistent with the law of the visual direction of monocular stimuli. In Experiment 2, 11 observers were asked to report relative depth between the two lines and to align them. The results indicated that the difference of the horizontal position did not covary with their perceived relative depth, suggesting that the visual direction and perceived depth of the monocular line are mediated via different mechanisms.

  19. 单眼弱视者的空间视觉缺损及其与弱视程度的相关性研究%Correlation between space visual defect of monocular amblyopia and the degree of amblyopia

    Institute of Scientific and Technical Information of China (English)

    杜娟; 罗红

    2015-01-01

    目的:研究单眼弱视者的空间视觉缺损模式及其与弱视程度的相关性,探讨连续全遮盖治疗的临床效果。方法回顾性分析我院2011年8月至2014年4月期间,于我科治疗的65例单眼弱视患者的临床资料,均予以连续全遮盖方式治疗,疗程12周,通过治疗效果,对比患者治疗前后双眼的视力、视锐度、AULCSF (对比敏感度函数的曲线下面积)、Smax (峰值对比敏感度)、Frmax (Smax空间频率)、CutSF (截止空间频率),评价弱视程度对空间视觉缺损所产生的影响。结果经12周治疗后,患者患眼视力、AULCSF、CutSF与治疗前相比较,差异均有统计学意义(P0.05)。视锐度、AULCSF、Smax、Frmax、CutSF在患眼不同弱视程度下差异均有显著统计学意义(P0.05). Visual acuity, AULCSF, Smax, Frmax, CutSF had statistically sig-nificant difference between different degrees of amblyopia (P<0.01), and Smax, Frmax, CutSF decreased with the de-gree of amblyopia eyes increased. Conclusion In patients with monocular amblyopia, AULCSF, Smax, Frmax, CutSF show a trend of consistency with visual sharpness and space visual defects. If the space visual defects deterio-rate, the corresponding degree of amblyopia would get worse. If high frequency contrast and resolution are reduced, the risk of eye spatial frequency will also show low frequency offset. For monocular amblyopia, continuous full cover treatment can improve the visual to the high frequency resolution, and not reduce visual function of eye.

  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

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    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. Visual and proprioceptive interaction in patients with bilateral vestibular loss

    Directory of Open Access Journals (Sweden)

    Nicholas J. Cutfield

    2014-01-01

    Full Text Available 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

  4. Visual evoked potentials monitoring in a case of transient post-operative visual loss

    Directory of Open Access Journals (Sweden)

    Marie Capon

    2016-01-01

    Full Text Available Post-operative visual loss (POVL is a rare, albeit potentially serious complication of general anaesthesia. This report describes the case of a 54-year-old woman who developed transient POVL after general anaesthesia following a left posterior parietal meningioma surgery in the prone position and discusses the usefulness of visual evoked potentials monitoring in such situations.

  5. Loss of Arc renders the visual cortex impervious to the effects of sensory experience or deprivation.

    Science.gov (United States)

    McCurry, Cortina L; Shepherd, Jason D; Tropea, Daniela; Wang, Kuan H; Bear, Mark F; Sur, Mriganka

    2010-04-01

    A myriad of mechanisms have been suggested to account for the full richness of visual cortical plasticity. We found that visual cortex lacking Arc is impervious to the effects of deprivation or experience. Using intrinsic signal imaging and chronic visually evoked potential recordings, we found that Arc(-/-) mice did not exhibit depression of deprived-eye responses or a shift in ocular dominance after brief monocular deprivation. Extended deprivation also failed to elicit a shift in ocular dominance or open-eye potentiation. Moreover, Arc(-/-) mice lacked stimulus-selective response potentiation. Although Arc(-/-) mice exhibited normal visual acuity, baseline ocular dominance was abnormal and resembled that observed after dark-rearing. These data suggest that Arc is required for the experience-dependent processes that normally establish and modify synaptic connections in visual cortex.

  6. Recording of both VEP and multifocal ERG for evaluation of unexplained visual loss electrophysiology in unexplained visual loss.

    Science.gov (United States)

    Renner, Agnes B; Kellner, Ulrich; Tillack, Hilmar; Kraus, Hannelore; Foerster, Michael H

    2005-11-01

    The purpose of this retrospective study was to determine the relevance of both visual-evoked potentials (VEP) and multifocal electroretinography (mfERG) to evaluate unexplained visual loss. Seventy-two consecutive patients (1996-2002) with visual disturbances of unknown origin underwent both VEP and mfERG (ISCEV standard). The mean age was 42.4 years (11.8-74.5) and median visual acuity 0.5 (no light perception - 1.0). Symptoms reported included visual acuity loss (n=69), visual field defects (n=11), disturbances of colour vision, light or dark adaptation (n=10). VEP and mfERG were normal in 43% (n=31). Both VEP and mfERG were pathological in 24% (n=17). In a further 18% (n=13) only the mfERG was pathological and in 15% (n=11) only the VEP was pathological. Macular dysfunction as detected with mfERG was present in 73% of 41 patients with at least one pathological test. Neuroimaging (MRI, CCT) and/or neurological examination was performed in 27/72 patients (38%), to account for unexplained visual loss, prior to the electrophysiological tests; these were normal in all patients. Electrophysiological tests revealed disturbances of the post-retinal visual pathway in only 3/27 patients. In 12/27 patients, mfERG revealed a macular disorder; in a further 12/27 patients VEP and mfERG were normal. The combined evaluation of VEP and mfERG is useful both to establish the area of dysfunction and the normality of the visual system. Electrophysiological testing prior to neuroimaging is recommended for patients where clear clinical signs of cerebral disorders are not evident. This reduces the frequency of unnecessary neuroimaging and associated radiation exposure.

  7. Neuroanatomical changes in patients with loss of visual function

    NARCIS (Netherlands)

    Prins, Doety

    2016-01-01

    Eye diseases that cause loss of visual function are associated with changes in the brain. However, the underlying mechanism of this association is still unclear. Research into this association is important, since the remaining capacity of the brain to conduct and process the input from the eye is

  8. Monocular 3D display system for presenting correct depth

    Science.gov (United States)

    Sakamoto, Kunio; Hosomi, Takashi

    2009-10-01

    The human vision system has visual functions for viewing 3D images with a correct depth. These functions are called accommodation, vergence and binocular stereopsis. Most 3D display system utilizes binocular stereopsis. The authors have developed a monocular 3D vision system with accommodation mechanism, which is useful function for perceiving depth.

  9. Reactivation of thalamocortical plasticity by dark exposure during recovery from chronic monocular deprivation

    Science.gov (United States)

    Montey, Karen L.; Quinlan, Elizabeth M.

    2015-01-01

    Chronic monocular deprivation induces severe amblyopia that is resistant to spontaneous reversal in adulthood. However, dark exposure initiated in adulthood reactivates synaptic plasticity in the visual cortex and promotes recovery from chronic monocular deprivation. Here we show that chronic monocular deprivation significantly decreases the strength of feedforward excitation and significantly decreases the density of dendritic spines throughout the deprived binocular visual cortex. Dark exposure followed by reverse deprivation significantly enhances the strength of thalamocortical synaptic transmission and the density of dendritic spines on principle neurons throughout the depth of the visual cortex. Thus dark exposure reactivates widespread synaptic plasticity in the adult visual cortex, including at thalamocortical synapses, during the recovery from chronic monocular deprivation. PMID:21587234

  10. PSD-95在正常发育和单眼剥夺大鼠视皮层的表达%Expression of PSD-95 in visual cortex of normal and monocular deprived rats

    Institute of Scientific and Technical Information of China (English)

    安喜艳; 赵堪兴

    2011-01-01

    目的 研究突触后致密物(post-synaptic density,PSD)-95在正常发育以及单眼视觉剥夺性大鼠视皮层中的蛋白动态表达情况,以期在突触水平为视觉发育可塑性提供分子基础.方法 健康生后14 d Wistar大鼠35只,随机分成正常组及单眼剥夺组,单眼剥夺组在生后14 d行单眼缝合术制备单眼剥夺模型.动物在同等环境下喂养,分别于生后14 d、21 d、28 d、45 d麻醉、灌注、固定、开颅、冠状切取后部脑组织(单眼剥夺组取剥夺眼对侧脑组织),进行常规HE和免疫组织化学方法染色.结果 HE染色中正常发育大鼠视皮层的神经元分布呈层状,且各层神经元排列整齐;单眼剥夺组大鼠视皮层未见明显异常.正常发育组PSD-95蛋白的表达随年龄呈发育性变化,生后21 d有明显升高(12.47±2.06),28 d(10.54±1.72)、45 d(11.65±1.55)持续在较高水平.PSD-95表达产物在单眼剥夺组较正常组明显减少.生后21 d(4.94±0.57)、28 d(5.20±0.47)、45 d(4.87±0.72)与正常组相比均下降(均为P<0.05).结论 PSD-95可能参与视觉发育敏感期视皮层神经元可塑性的调节.%Objective To study the dynamic expression of post-synaptic density (PSD)-95 in the visual cortex of normal and monocular deprived rats and provide the molecular mechanism of the visual plasticity at the level of synapse. Methods Thirty-five healthy Wistar rats with 14 days old were randomly divided into normal group (N) and monocular deprivation group (MD). The eyelids of MD groups were sutured at postnatal 14 days to obtain animal model. Rats were housed in alike environment, at postnatal 14 days,21 days,28 days,45 days the posterior brain coronally (get the brain opposite to deprived eye in the rats of MD) were cut after anesthesia, perfusion, fixation and opening cranium,the routine HE staining and immunohistochemistry staining were carried out. Results HE staining results showed the neurons of visual cortex in normal rats

  11. 基于单目视觉的移动机器人伺服镇定控制%Monocular camera-based mobile robot visual servo regulation control

    Institute of Scientific and Technical Information of China (English)

    刘阳; 王忠立; 蔡伯根; 闻映红

    2016-01-01

    To solve the monocular camera‐based mobile robot regulation problem ,the kinematic model in camera coordinate was proposed under the condition of unknown range information ,unknown translation parameter between robot and camera frames ,camera with certain dip angle .A robust and adaptive controller was proposed based on the assumptions above .The controller guaranteed exponen‐tial convergence of the system .The performance of the controller was validated by simulation and ex‐periment result ,showing that the controller could guarantees the robot rapidly and smoothly regulate to desired pose .T he controller is also robust to unknow n parameter .%针对轮式移动机器人的单目视觉伺服镇定问题,在深度信息、机器人坐标系与摄像机坐标系间平移参量未知、摄像头光轴具有固定倾角的情况下,建立了移动机器人在摄像机坐标系下的运动模型。针对该模型提出了一种基于平面单应矩阵分解的鲁棒自适应控制方法,保证了误差的全局指数收敛。仿真和实验结果表明:所设计的控制器可以保证移动机器人指数收敛到期望的位姿,同时所设计的鲁棒自适应控制器对参数不确定性具有一定的鲁棒性。

  12. Reorganization of early visual cortex functional connectivity following selective peripheral and central visual loss.

    Science.gov (United States)

    Sabbah, Norman; Sanda, Nicolae; Authié, Colas N; Mohand-Saïd, Saddek; Sahel, José-Alain; Habas, Christophe; Amedi, Amir; Safran, Avinoam B

    2017-02-24

    Behavioral alterations emerging after central or peripheral vision loss suggest that cerebral reorganization occurs for both the afferented and deafferented early visual cortex (EVC). We explored the functional reorganization of the central and peripheral EVC following visual field defects specifically affecting central or peripheral vision. Compared to normally sighted, afferented central and peripheral EVC enhance their functional connectivity with areas involved in visual processing, whereas deafferented central and peripheral EVC increase their functional connectivity with more remote regions. The connectivity pattern of afferented EVC suggests adaptive changes that might enhance the visual processing capacity whereas the connectivity pattern of deafferented EVC may reflect the involvement of these regions in high-order mechanisms. Characterizing and understanding the plastic changes induced by these visual defects is essential for any attempt to develop efficient rehabilitation strategies.

  13. Monocular occlusions determine the perceived shape and depth of occluding surfaces.

    Science.gov (United States)

    Tsirlin, Inna; Wilcox, Laurie M; Allison, Robert S

    2010-06-01

    Recent experiments have established that monocular areas arising due to occlusion of one object by another contribute to stereoscopic depth perception. It has been suggested that the primary role of monocular occlusions is to define depth discontinuities and object boundaries in depth. Here we use a carefully designed stimulus to demonstrate empirically that monocular occlusions play an important role in localizing depth edges and defining the shape of the occluding surfaces in depth. We show that the depth perceived via occlusion in our stimuli is not due to the presence of binocular disparity at the boundary and discuss the quantitative nature of depth perception in our stimuli. Our data suggest that the visual system can use monocular information to estimate not only the sign of the depth of the occluding surface but also its magnitude. We also provide preliminary evidence that perceived depth of illusory occluders derived from monocular information can be biased by binocular features.

  14. Short-Term Monocular Deprivation Enhances Physiological Pupillary Oscillations.

    Science.gov (United States)

    Binda, Paola; Lunghi, Claudia

    2017-01-01

    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.

  15. 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.

  16. The analysis of visual evoked potential in patients with monocular congenital ptosis%单眼先天性上睑下垂患儿图形视觉诱发电位分析

    Institute of Scientific and Technical Information of China (English)

    黄业贤; 周瑾; 胡兰香; 宋生芳; 项道满

    2014-01-01

    目的:探讨单眼先天性上睑下垂患儿图形视觉诱发电位(P-VEP)的特点,评估P-VEP对上睑下垂患儿双眼视觉功能检测的意义。方法对53例2~4岁单眼先天性上睑下垂患儿进行P-VEP检查,比较双眼P-VEP的P100潜伏期及振幅是否存在差异。结果上睑下垂眼VEP P100波潜伏期较正常组延长(P<0.01),振幅低于正常眼(P<0.01)。轻度上睑下垂眼P-VEP P100波振幅与中度及重度相比,差异有统计学意义(P<0.01),中度与重度相比差异无统计学意义,轻度上睑下垂眼P-VEP P100波潜伏期与中度相比差异无统计学意义,与重度比差异有统计学意义(P<0.01),中度与重度比较差异有统计学意义(P<0.05)。结论单眼先天性上睑下垂患者双眼P-VEP P100波振幅及潜伏期存在差异,根据患儿视觉发育程度进行手术时机选择的同时,应注意术后矫正弱视。%Objective To investigate the visual evoked potential (P-VEP) feature in patients with monocular congenital ptosis. To evaluate the significance of P-VEP in binocular vision.MethodsP-VEP response was recorded in 53 monocular congenital ptosis children who were 2-4 years old. Then compared the differences of latency period and waver of P100 wave.ResultsCompared with normal eye,the latency period of ptosis eyes was longer and the amplitude was lower(P<0.01).The differences of amplitude between mild ptosis eyes and midrange or severe ptosis eyes were significant (P<0.01) while they were not significantly between midrange and severe group.The differences of latency period between mild ptosis eyes and midrange eyes were not significant while they were significantlly between midrange and severe group(P<0.01,P<0.05).Conclusion Patients with monocular congenital ptosis edured differences response of P-VEP P100 in amplitude and latency period between two eyes.Attention should be focused on mblyopia after surgery.

  17. Influence of initial visual field sensitivity on visual field loss progression in open angle glaucoma

    Directory of Open Access Journals (Sweden)

    Hentova-Senćanić Paraskeva

    2012-01-01

    Full Text Available Introduction. It is important to know the risk factors for visual field defect progression in order to predict the future development of glaucoma. Objective. To investigate the influence of visual field initial sensitivity on the rate of visual field progression. Methods. A minimum of five visual fields were performed using computerized perimetry (Octopus over a mean follow- up 4-year period (48.85±17.84 months in 64 persons (114 eyes with primary open angle glaucoma. The rate of change of the whole central visual field and each of the seven regions of the field were measured by linear regression analysis of the mean sensitivity value versus time. Based on the slope of the regression line of visual field mean sensitivity over time the eyes were divided into two groups: the group with stable and the group with progressive visual field. The comparison of the mean sensitivity of the whole central visual field between the groups was performed using the Mann-Whitney U-test. The Spearman rang correlation coefficient and the Spearman probability p values were calculated to assess the mean sensitivity of the whole central visual field and of each visual field regions determined at the beginning of the study. Results. The initial mean sensitivity of the whole central visual field was lower in the group with progressive visual field (16.62±6.35 dB. Correlation between the initial mean sensitivity and the slope of the regression line was negative. The lowest mean sensitivity was in the group with progressive visual field in the upper temporal (13.73±7.35 dB, nasal (14.74±7.23 dB and upper nasal (15.03±7.75 dB regions. Conclusion. The lower mean sensitivity value of the visual field, especially in the nasal and upper nasal visual field regions, carries a greater risk for delayed progressive loss of the visual field in persons with glaucoma.

  18. Loss of Nrf2 exacerbates the visual deficits and optic neuritis elicited by experimental autoimmune encephalomyelitis

    Science.gov (United States)

    Larabee, Chelsea M.; Desai, Shruti; Agasing, Agnieshka; Georgescu, Constantin; Wren, Jonathan D.; Axtell, Robert C.

    2016-01-01

    Purpose Optic neuritis, inflammation of the optic nerve, is experienced by most patients with multiple sclerosis (MS) and is typically characterized by episodes of acute, monocular vision loss. These episodes of inflammation can lead to damage or degeneration of the retinal ganglion cells (RGCs), the axons of which comprise the optic nerve. Experimental autoimmune encephalomyelitis (EAE) is a well-established model of MS in which mice are immunized to produce a neuroautoimmunity that recapitulates the cardinal hallmarks of human disease, namely, inflammation, demyelination, and neurodegeneration of the brain, spinal cord, and optic nerve. Inflammation-associated oxidative stress plays a key role in promoting spinal cord damage in EAE. However, the role of oxidative stress in optic neuritis and the associated visual deficits has not been studied. To address this gap in research, we sought to determine how a deficiency in the master antioxidant transcription factor (using nuclear factor-E2-related factor [Nrf2]-deficient mice) affects visual pathology in the EAE model. Methods EAE was induced in 8-week-old wild-type (WT) and Nrf2 knockout (KO) mice by immunization against the myelin oligodendrocyte glycoprotein (MOG) peptide antigen. Motor deficits were monitored daily, as was visual acuity using the established functional optokinetic tracking (OKT) assay. Mice were euthanized 21 days post-immunization for histological analyses. The optic nerves were paraffin-embedded and stained with hematoxylin and eosin (H&E) or immune cell type–specific antibodies to analyze inflammatory infiltrates. The retinas were flatmounted and stained with an RGC-specific antibody, and the RGCs were counted to assess neurodegeneration. T-helper (Th) cell-associated cytokines were measured in spleens with enzyme-linked immunosorbent assay (ELISA). Immune analyses of healthy, non-EAE mice were characterized with flow cytometry to assess the baseline immune cell profiles. Results Female Nrf2

  19. Bayesian depth estimation from monocular natural images.

    Science.gov (United States)

    Su, Che-Chun; Cormack, Lawrence K; Bovik, Alan C

    2017-05-01

    Estimating an accurate and naturalistic dense depth map from a single monocular photographic image is a difficult problem. Nevertheless, human observers have little difficulty understanding the depth structure implied by photographs. Two-dimensional (2D) images of the real-world environment contain significant statistical information regarding the three-dimensional (3D) structure of the world that the vision system likely exploits to compute perceived depth, monocularly as well as binocularly. Toward understanding how this might be accomplished, we propose a Bayesian model of monocular depth computation that recovers detailed 3D scene structures by extracting reliable, robust, depth-sensitive statistical features from single natural images. These features are derived using well-accepted univariate natural scene statistics (NSS) models and recent bivariate/correlation NSS models that describe the relationships between 2D photographic images and their associated depth maps. This is accomplished by building a dictionary of canonical local depth patterns from which NSS features are extracted as prior information. The dictionary is used to create a multivariate Gaussian mixture (MGM) likelihood model that associates local image features with depth patterns. A simple Bayesian predictor is then used to form spatial depth estimates. The depth results produced by the model, despite its simplicity, correlate well with ground-truth depths measured by a current-generation terrestrial light detection and ranging (LIDAR) scanner. Such a strong form of statistical depth information could be used by the visual system when creating overall estimated depth maps incorporating stereopsis, accommodation, and other conditions. Indeed, even in isolation, the Bayesian predictor delivers depth estimates that are competitive with state-of-the-art "computer vision" methods that utilize highly engineered image features and sophisticated machine learning algorithms.

  20. Fungal ball within Onodi cell mucocele causing visual loss.

    Science.gov (United States)

    Cheon, Yong-Il; Hong, Sung-Lyong; Roh, Hwan-Jung; Cho, Kyu-Sup

    2014-03-01

    The Onodi cell is a pneumatized posterior ethmoid cell located laterally and superiorly to the sphenoid sinus and closely related to the optic nerve. A mucocele is a benign, expansile, cystlike lesion of the paranasal sinuses that is filled with mucoid secretion. Therefore, optic neuropathy caused by an infected mucocele in an Onodi cell is uncommon. Furthermore, fungal infection superimposed on an Onodi cell mucocele is extremely rare and has not been reported previously. Here, we describe the first case of fungal ball within Onodi cell mucocele causing visual loss, which was completely removed via transnasal endoscopic approach.

  1. Monocular 3D display unit using soft actuator for parallax image shift

    Science.gov (United States)

    Sakamoto, Kunio; Kodama, Yuuki

    2010-11-01

    The human vision system has visual functions for viewing 3D images with a correct depth. These functions are called accommodation, vergence and binocular stereopsis. Most 3D display system utilizes binocular stereopsis. The authors have developed a monocular 3D vision system with accommodation mechanism, which is useful function for perceiving depth. This vision unit needs an image shift optics for generating monocular parallax images. But conventional image shift mechanism is heavy because of its linear actuator system. To improve this problem, we developed a light-weight 3D vision unit for presenting monocular stereoscopic images using a soft linear actuator made of a polypyrrole film.

  2. Light-weight monocular display unit for 3D display using polypyrrole film actuator

    Science.gov (United States)

    Sakamoto, Kunio; Ohmori, Koji

    2010-10-01

    The human vision system has visual functions for viewing 3D images with a correct depth. These functions are called accommodation, vergence and binocular stereopsis. Most 3D display system utilizes binocular stereopsis. The authors have developed a monocular 3D vision system with accommodation mechanism, which is useful function for perceiving depth. This vision unit needs an image shift optics for generating monocular parallax images. But conventional image shift mechanism is heavy because of its linear actuator system. To improve this problem, we developed a light-weight 3D vision unit for presenting monocular stereoscopic images using a polypyrrole linear actuator.

  3. Visual Loss from Choroidal Melanoma Mimicking Neurological Syndromes

    Directory of Open Access Journals (Sweden)

    Karim Hammamji

    2017-03-01

    Full Text Available Melanoma of the eye is rare, but can mimic a range of disorders. This report highlights 2 cases of choroidal melanoma with vision loss mimicking neurological diagnoses. The first patient is a 41-year-old white male with a known history of multiple sclerosis and a previous episode of optic neuritis in the right eye, who presented with a 6-month history of decreased vision in the same eye, and occasional photopsiae. He was treated with 2 courses of oral steroids for presumed recurrent optic neuritis. After a temporary improvement in his symptoms, his vision worsened, following which he had a head MRI, which revealed a solid intraocular mass. He was subsequently diagnosed with a choroidal melanoma for which he was treated successfully with ruthenium-106 plaque brachytherapy. The second patient is a 57-year-old female, who presented with a progressive cerebellar syndrome under investigation by the neurology service, as well as decreased vision in the right eye. Her visual acuity gradually deteriorated and her neurological assessment, which included a PET-CT, revealed uptake in the right eye. The diagnosis of a choroidal melanoma was made, and following conservative treatment with proton beam radiotherapy, she had an enucleation of the eye. Intraocular tumours can masquerade as many different entities. Unexplained unilateral visual loss, especially if it is atypical for a neurological syndrome, should prompt dilated fundoscopy and referral to an ophthalmologist.

  4. Apparent motion of monocular stimuli in different depth planes with lateral head movements.

    Science.gov (United States)

    Shimono, K; Tam, W J; Ono, H

    2007-04-01

    A stationary monocular stimulus appears to move concomitantly with lateral head movements when it is embedded in a stereogram representing two front-facing rectangular areas, one above the other at two different distances. In Experiment 1, we found that the extent of perceived motion of the monocular stimulus covaried with the amplitude of head movement and the disparity between the two rectangular areas (composed of random dots). In Experiment 2, we found that the extent of perceived motion of the monocular stimulus was reduced compared to that in Experiment 1 when the rectangular areas were defined only by an outline rather than by random dots. These results are discussed using the hypothesis that a monocular stimulus takes on features of the binocular surface area in which it is embedded and is perceived as though it were treated as a binocular stimulus with regards to its visual direction and visual depth.

  5. 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.

  6. Loop Closure Detection Algorithm Based on Monocular Vision Using Visual Dictionary%基于视觉词典的单目视觉闭环检测算法

    Institute of Scientific and Technical Information of China (English)

    梁志伟; 陈燕燕; 朱松豪; 高翔; 徐国政

    2013-01-01

    Aiming at the problem of loop closure detection in monocular simultaneous localization and mapping for mobile robots,a detection algorithm based on visual dictionary (VD) is presented.Firstly,feature extraction is performed for each required image using SURF methods.Subsequently,a fuzzy K-means algorithm is employed to cluster these visual feature vectors into visual words based on VD which is constructed online.To precisely represent the similarities between each visual word and corresponding local visual features,Gaussian mixture model is proposed to learn the probability model of every visual word in bags of visual words.Consequently,every image can be denoted as a probabilistic vector of VD,and thus the similarities between any two images can be computed based on vector inner product.To guarantee the continuity of the closed-loop detection,a Bayesian filter method is applied to fuse historical closed-loop detection information and the obtained similarities to calculate the posterior probability distribution of closed-loop hypothesis.Furthermore,two memory management mechanisms,shallow memory and deep memory,are introduced to improve the process speed of the proposed algorithm.The experimental results demonstrate the validity of the proposed approach.%针对移动机器人单目视觉同步定位与地图构建中的闭环检测问题,文中设计一种基于视觉词典的闭环检测算法.算法对采集的每帧图像通过SURF进行特征提取,应用模糊K均值算法对检测的视觉特征向量进行分类,在线构建表征图像的视觉词典.为精确表征局部视觉特征与视觉单词间的相似关联,利用混合高斯模型建立视觉词典中的每一视觉单词的概率模型,实现图像基于视觉词典的概率向量表示,通过向量的内积来计算图像间的相似度.为保证闭环检测的成功率,应用贝叶斯滤波融合历史闭环检测与相似度信息来计算闭环假设的后验概率分布.另外,引入浅层

  7. Dynamic topography of pattern visual evoked potentials (PVEP) in psychogenic visual loss patients.

    Science.gov (United States)

    Nakamura, A; Tabuchi, A; Matsuda, E; Yamaguchi, W

    2000-09-01

    We investigated to measure the objective visual acuity using pattern visual evoked potentials (PVEP) to help the diagnosis with psychogenic visual loss (PVL) who ranged in age from 7 to 14 years old. Pattern stimuli consisted of black and white checkerboard patterns (39, 26, 15 and 9') with a visual angle of 8 degrees and a contrast level of 15%. The pattern reversal frequency was 0.7 Hz. This resulted in an average of 100 PVEP per session. Visual acuity of 0.1 was consistent with the 39' pattern, 0.2 with the 26' pattern, 0.5 with the 15' pattern, and 1.0 with the 9' pattern. As the results, five PVL patients could measure visual acuity with this method in the present study. The PVEP is useful in evaluating the visual acuity and helped to diagnose the PVL patients. In addition we used the dynamic topography to study the difference in the results of the PVEP. The dynamic topography obtained from the results of the PVEP was analyzed. The flow type of the P100 component diverged into three types (separated type, hollow type and localized type) in the PVL patients and the normal children. The localized type was observed in 59.1% of normal children and in 56.3% of PVL patients. While the separated type was shown in 6.8% of normal children and in 8.3% of PVL patients. There were not significant differences between the PVL patients and the normal children in each type.

  8. Saccade amplitude disconjugacy induced by aniseikonia: role of monocular depth cues.

    Science.gov (United States)

    Pia Bucci, M; Kapoula, Z; Eggert, T

    1999-09-01

    The conjugacy of saccades is rapidly modified if the images are made unequal for the two eyes. Disconjugacy persists even in the absence of disparity which indicates learning. Binocular visual disparity is a major cue to depth and is believed to drive the disconjugacy of saccades to aniseikonic images. The goal of the present study was to test whether monocular depth cues can also influence the disconjugacy of saccades. Three experiments were performed in which subjects were exposed for 15-20 min to a 10% image size inequality. Three different images were used: a grid that contained a single monocular depth cue strongly indicating a frontoparallel plane; a random-dot pattern that contained a less prominent monocular depth cue (absence of texture gradient) which also indicates the frontoparallel plane; and a complex image with several overlapping geometric forms that contained a variety of monocular depth cues. Saccades became disconjugate in all three experiments. The disconjugacy was larger and more persistent for the experiment using the random-dot pattern that had the least prominent monocular depth cues. The complex image which had a large variety of monocular depth cues produced the most variable and less persistent disconjugacy. We conclude that the monocular depth cues modulate the disconjugacy of saccades stimulated by the disparity of aniseikonic images.

  9. How to avoid perioperative visual loss following prone spinal surgery

    Science.gov (United States)

    Epstein, Nancy E.

    2016-01-01

    Background: In a prior article, “Perioperative visual loss (POVL) following prone spinal surgery: A review,” Epstein documented that postoperative visual loss (POVL) occurs in from 0.013% to 0.2% of spine procedures performed in the prone position. POVL is largely attributed to ischemic optic neuropathy (ION), central retinal artery occlusion (CRAO), cortical blindness (CB), direct compression (prone pillows/horseshoe, eye protectors), and rarely, acute angle closure glaucoma. Methods: Risk factors for ION include prolonged surgery, extensive fusions, anemia, hypotension, hypovolemia, diabetes, obesity, use of the Wilson frame, male sex, and microvascular pathology. CRAO may result from improper prone positioning (e.g., eye compression or rotation contributing to jugular/venous or carotid compression), while CB more typically results from both direct compression and obesity. Results: Several preventive/prophylactic measures should limit the risk of POVL. The routine use of an arterial line and continuous intraoperative monitoring document intraoperative hypotension/hypovolemia/anemia that can be immediately corrected with appropriate resuscitative measures. Application of a 3-pin head holder completely eliminates direct eye compression and maintains the neck in a neutral posture, thus avoiding rotation that can contribute to jugular/venous obstruction and/or inadvertent carotid compression. In addition, elevating the head 10° from the horizontal directly reduces intraocular pressure. Conclusions: The best way to avoid POVL following prone spine surgery is to prevent it. Routine use of an arterial line, intraoperative monitoring, a 3-pin head holder, and elevation of the head 10° from the horizontal should limit the risk of encountering POVL after spinal procedures performed in the prone position. PMID:27274406

  10. The effect of induced monocular blur on measures of stereoacuity.

    Science.gov (United States)

    Odell, Naomi V; Hatt, Sarah R; Leske, David A; Adams, Wendy E; Holmes, Jonathan M

    2009-04-01

    To determine the effect of induced monocular blur on stereoacuity measured with real depth and random dot tests. Monocular visual acuity deficits (range, 20/15 to 20/1600) were induced with 7 different Bangerter filters (depth tests and Preschool Randot (PSR) and Distance Randot (DR) random dot tests. Stereoacuity results were grouped as either "fine" (60 and 200 arcsec to nil) stereo. Across visual acuity deficits, stereoacuity was more severely degraded with random dot (PSR, DR) than with real depth (Frisby, FD2) tests. Degradation to worse-than-fine stereoacuity consistently occurred at 0.7 logMAR (20/100) or worse for Frisby, 0.1 logMAR (20/25) or worse for PSR, and 0.1 logMAR (20/25) or worse for FD2. There was no meaningful threshold for the DR because worse-than-fine stereoacuity was associated with -0.1 logMAR (20/15). Course/nil stereoacuity was consistently associated with 1.2 logMAR (20/320) or worse for Frisby, 0.8 logMAR (20/125) or worse for PSR, 1.1 logMAR (20/250) or worse for FD2, and 0.5 logMAR (20/63) or worse for DR. Stereoacuity thresholds are more easily degraded by reduced monocular visual acuity with the use of random dot tests (PSR and DR) than real depth tests (Frisby and FD2). We have defined levels of monocular visual acuity degradation associated with fine and nil stereoacuity. These findings have important implications for testing stereoacuity in clinical populations.

  11. Monocular nasal hemianopia from atypical sphenoid wing meningioma.

    Science.gov (United States)

    Stacy, Rebecca C; Jakobiec, Frederick A; Lessell, Simmons; Cestari, Dean M

    2010-06-01

    Neurogenic monocular nasal field defects respecting the vertical midline are quite uncommon. We report a case of a unilateral nasal hemianopia that was caused by compression of the left optic nerve by a sphenoid wing meningioma. Histological examination revealed that the pathology of the meningioma was consistent with that of an atypical meningioma, which carries a guarded prognosis with increased chance of recurrence. The tumor was debulked surgically, and the patient's visual field defect improved.

  12. Binocular Glaucomatous Visual Field Loss and Its Impact on Visual Exploration - A Supermarket Study

    Science.gov (United States)

    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<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. PMID:25162522

  13. 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.

  14. 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 visual field defect (VFD) area than patients who failed (t-test, p 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.

  15. Dynamic object recognition and tracking of mobile robot by monocular vision

    Science.gov (United States)

    Liu, Lei; Wang, Yongji

    2007-11-01

    Monocular Vision is widely used in mobile robot's motion control for its simple structure and easy using. An integrated description to distinguish and tracking the specified color targets dynamically and precisely by the Monocular Vision based on the imaging principle is the major topic of the paper. The mainline is accordance with the mechanisms of visual processing strictly, including the pretreatment and recognition processes. Specially, the color models are utilized to decrease the influence of the illumination in the paper. Some applied algorithms based on the practical application are used for image segmentation and clustering. After recognizing the target, however the monocular camera can't get depth information directly, 3D Reconstruction Principle is used to calculate the distance and direction from robot to target. To emend monocular camera reading, the laser is used after vision measuring. At last, a vision servo system is designed to realize the robot's dynamic tracking to the moving target.

  16. Dichoptic stimulation improves detection of glaucoma with multifocal visual evoked potentials.

    Science.gov (United States)

    Arvind, Hemamalini; Klistorner, Alexander; Graham, Stuart; Grigg, John; Goldberg, Ivan; Klistorner, Asya; Billson, Frank A

    2007-10-01

    To determine whether simultaneous binocular (dichoptic) stimulation for multifocal visual evoked potentials (mfVEP) detects glaucomatous defects and decreases intereye variability. Twenty-eight patients with glaucoma and 30 healthy subjects underwent mfVEP on monocular and dichoptic stimulation. Dichoptic stimulation was presented with the use of virtual reality goggles (recording time, 7 minutes). Monocular mfVEPs were recorded sequentially for each eye (recording time, 10 minutes). Comparison of mean relative asymmetry coefficient (RAC; calculated as difference in amplitudes between eyes/sum of amplitudes of both eyes at each segment) on monocular and dichoptic mfVEP revealed significantly lower RAC on dichoptic (0.003 +/- 0.03) compared with monocular testing (-0.02 +/- 0.04; P = 0.002). In all 28 patients, dichoptic mfVEP identified defects with excellent topographic correspondence. Of 56 hemifields (28 eyes), 33 had Humphrey visual field (HFA) scotomas, all of which were detected by dichoptic mfVEP. Among 23 hemifields with normal HFA, two were abnormal on monocular and dichoptic mfVEP. Five hemifields (five patients) normal on HFA and monocular mfVEP were abnormal on dichoptic mfVEP. In all five patients, corresponding rim changes were observed on disc photographs. Mean RAC of glaucomatous eyes was significantly higher on dichoptic (0.283 +/- 0.18) compared with monocular (0.199 +/- 0.12) tests (P = 0.0006). Dichoptic mfVEP not only detects HFA losses, it may identify early defects in areas unaffected on HFA and monocular mfVEP while reducing testing time by 30%. Asymmetry was tighter among healthy subjects but wider in patients with glaucoma on simultaneous binocular stimulation, which is potentially a new tool in the early detection of glaucoma.

  17. Perioperative visual loss following prone spinal surgery: A review

    Science.gov (United States)

    Epstein, Nancy E.

    2016-01-01

    Background: Postoperative visual loss (POVL) following prone spine surgery occurs in from 0.013% to 1% of cases and is variously attributed to ischemic optic neuropathy (ION: anterior ION or posterior ION [reported in 1.9/10,000 cases: constitutes 89% of all POVL cases], central retinal artery occlusion [CRAO], central retinal vein occlusion [CRVO], cortical blindness [CB], direct compression [horseshoe, prone pillows, and eye protectors Dupaco Opti-Gard]), and acute angle closure glaucoma (AACG). Methods: Risk factors for ION include prolonged operative times, long-segment spinal instrumentation, anemia, intraoperative hypotension, diabetes, obesity, male sex, using the Wilson frame, microvascular pathology, decreased the percent of colloid administration, and extensive intraoperative blood loss. Risk factors for CRAO more typically include improper positioning during the surgery (e.g., cervical rotation), while those for CB included prone positioning and obesity. Results: POVL may be avoided by greater utilization of crystalloids versus colloids, administration of α-2 agonists (e.g., decreases intraocular pressure), avoidance of catecholamines (e.g., avoid vasoconstrictors), avoiding intraoperative hypotension, and averting anemia. Patients with glaucoma or glaucoma suspects may undergo preoperative evaluation by ophthalmologists to determine whether they require prophylactic treatment prior to prone spinal surgery and whether and if prophylactic treatment is warranted. Conclusions: The best way to avoid POVL is to recognize its multiple etiologies and limit the various risk factors that contribute to this devastating complication of prone spinal surgery. Furthermore, routinely utilizing a 3-pin head holder will completely avoid ophthalmic compression, while maintaining the neck in a neutral posture, largely avoiding the risk of jugular vein and/or carotid artery compromise and thus avoiding increasing IOP. PMID:27274409

  18. Depth Perception and Grasp in Central Field Loss.

    Science.gov (United States)

    Verghese, Preeti; Tyson, Terence L; Ghahghaei, Saeideh; Fletcher, Donald C

    2016-03-01

    We set out to determine whether individuals with central field loss benefit from using two eyes to perform a grasping task. Specifically, we tested the hypothesis that this advantage is correlated with coarse stereopsis, in addition to binocular summation indices of visual acuity, contrast sensitivity, and binocular visual field. Sixteen participants with macular degeneration and nine age-matched controls placed pegs on a pegboard, while their eye and hand movements were recorded. Importantly, the pegboard was placed near eye height, to minimize the contribution of monocular cues to peg position. All participants performed this task binocularly and monocularly. Before the experiment, we performed microperimetry to determine the profile of field loss in each eye and the locations of eccentric fixation (if applicable). In addition, we measured both acuity and contrast sensitivity monocularly and binocularly, and stereopsis by using both a RanDot test and a custom stereo test. Peg-placement time was significantly shorter and participants made significantly fewer errors with binocular than with monocular viewing in both the patient and control groups. Among participants with measurable stereopsis, binocular advantage in peg-placement time was significantly correlated with stereoacuity (ρ = -0.78; P = 0.003). In patients without measurable stereopsis, the binocular advantage was related significantly to the overlap in the scotoma between the two eyes (ρ = -0.81; P = 0.032). The high correlation between grasp performance and stereoacuity indicates that coarse stereopsis may benefit tasks of daily living for individuals with central field loss.

  19. High Accuracy Monocular SFM and Scale Correction for Autonomous Driving.

    Science.gov (United States)

    Song, Shiyu; Chandraker, Manmohan; Guest, Clark C

    2016-04-01

    We present a real-time monocular visual odometry system that achieves high accuracy in real-world autonomous driving applications. First, we demonstrate robust monocular SFM that exploits multithreading to handle driving scenes with large motions and rapidly changing imagery. To correct for scale drift, we use known height of the camera from the ground plane. Our second contribution is a novel data-driven mechanism for cue combination that allows highly accurate ground plane estimation by adapting observation covariances of multiple cues, such as sparse feature matching and dense inter-frame stereo, based on their relative confidences inferred from visual data on a per-frame basis. Finally, we demonstrate extensive benchmark performance and comparisons on the challenging KITTI dataset, achieving accuracy comparable to stereo and exceeding prior monocular systems. Our SFM system is optimized to output pose within 50 ms in the worst case, while average case operation is over 30 fps. Our framework also significantly boosts the accuracy of applications like object localization that rely on the ground plane.

  20. Comparison of Subjective Refraction under Binocular and Monocular Conditions in Myopic Subjects.

    Science.gov (United States)

    Kobashi, Hidenaga; Kamiya, Kazutaka; Handa, Tomoya; Ando, Wakako; Kawamorita, Takushi; Igarashi, Akihito; Shimizu, Kimiya

    2015-07-28

    To compare subjective refraction under binocular and monocular conditions, and to investigate the clinical factors affecting the difference in spherical refraction between the two conditions. We examined thirty eyes of 30 healthy subjects. Binocular and monocular refraction without cycloplegia was measured through circular polarizing lenses in both eyes, using the Landolt-C chart of the 3D visual function trainer-ORTe. Stepwise multiple regression analysis was used to assess the relations among several pairs of variables and the difference in spherical refraction in binocular and monocular conditions. Subjective spherical refraction in the monocular condition was significantly more myopic than that in the binocular condition (p refraction (p = 0.99). The explanatory variable relevant to the difference in spherical refraction between binocular and monocular conditions was the binocular spherical refraction (p = 0.032, partial regression coefficient B = 0.029) (adjusted R(2) = 0.230). No significant correlation was seen with other clinical factors. Subjective spherical refraction in the monocular condition was significantly more myopic than that in the binocular condition. Eyes with higher degrees of myopia are more predisposed to show the large difference in spherical refraction between these two conditions.

  1. 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.

  2. 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...... : The cohort comprised 40 patients (25 female and 15 male) with a mean age of 39 years (range 17-60 years). The mean visual acuity was >1.0 and all eyes had an intraocular pressure

  3. 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…

  4. 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…

  5. [Noradrenaline and plasticity of the visual cortex of the kitten: a reexamination].

    Science.gov (United States)

    Adrien, J; Buisseret, P; Fregnac, Y; Gary-Bobo, E; Imbert, M; Tassin, J P; Trotter, Y

    1982-12-06

    We have undertaken a study of the role of the noradrenergic system in the functional modifications, observed in the primary visual cortex of the Kitten, following monocular deprivation. The lids of one eye were sutured in 5 week old Kittens for a period of 1 or 2 weeks. Noradrenergic depletion was obtained by 6-OHDA injection, either intraventricular or localized in the coeruleus complex. Our results indicate that disappearance of noradrenaline in area 17 does not prevent the loss of binocularity of cortical cells, but appears to limit ocular dominance shifts at a stage equivalent to that observed in the intact Kitten after 6 days of monocular deprivation.

  6. Validation of Data Association for Monocular SLAM

    Directory of Open Access Journals (Sweden)

    Edmundo Guerra

    2013-01-01

    Full Text Available Simultaneous Mapping and Localization (SLAM is a multidisciplinary problem with ramifications within several fields. One of the key aspects for its popularity and success is the data fusion produced by SLAM techniques, providing strong and robust sensory systems even with simple devices, such as webcams in Monocular SLAM. This work studies a novel batch validation algorithm, the highest order hypothesis compatibility test (HOHCT, against one of the most popular approaches, the JCCB. The HOHCT approach has been developed as a way to improve performance of the delayed inverse-depth initialization monocular SLAM, a previously developed monocular SLAM algorithm based on parallax estimation. Both HOHCT and JCCB are extensively tested and compared within a delayed inverse-depth initialization monocular SLAM framework, showing the strengths and costs of this proposal.

  7. 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

    -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...... 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...

  8. Eye movements in chameleons are not truly independent - evidence from simultaneous monocular tracking of two targets.

    Science.gov (United States)

    Katz, Hadas Ketter; Lustig, Avichai; Lev-Ari, Tidhar; Nov, Yuval; Rivlin, Ehud; Katzir, Gadi

    2015-07-01

    Chameleons perform large-amplitude eye movements that are frequently referred to as independent, or disconjugate. When prey (an insect) is detected, the chameleon's eyes converge to view it binocularly and 'lock' in their sockets so that subsequent visual tracking is by head movements. However, the extent of the eyes' independence is unclear. For example, can a chameleon visually track two small targets simultaneously and monocularly, i.e. one with each eye? This is of special interest because eye movements in ectotherms and birds are frequently independent, with optic nerves that are fully decussated and intertectal connections that are not as developed as in mammals. Here, we demonstrate that chameleons presented with two small targets moving in opposite directions can perform simultaneous, smooth, monocular, visual tracking. To our knowledge, this is the first demonstration of such a capacity. The fine patterns of the eye movements in monocular tracking were composed of alternating, longer, 'smooth' phases and abrupt 'step' events, similar to smooth pursuits and saccades. Monocular tracking differed significantly from binocular tracking with respect to both 'smooth' phases and 'step' events. We suggest that in chameleons, eye movements are not simply 'independent'. Rather, at the gross level, eye movements are (i) disconjugate during scanning, (ii) conjugate during binocular tracking and (iii) disconjugate, but coordinated, during monocular tracking. At the fine level, eye movements are disconjugate in all cases. These results support the view that in vertebrates, basic monocular control is under a higher level of regulation that dictates the eyes' level of coordination according to context. © 2015. Published by The Company of Biologists Ltd.

  9. 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.

  10. 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.

  11. Expression of mGluR1 at primary visual cortex of monocular deprivation amblyopia rat and the observing of ultrastructure%代谢性谷氨酸受体1在单眼形觉剥夺弱视大鼠视皮质17区的表达及超微结构观察

    Institute of Scientific and Technical Information of China (English)

    王宗青; 刘向玲; 穆雅林; 刘爱琴; 李晓鹏

    2008-01-01

    Objective To explore the regulation of expression of mGluR1 and the changes of neuron ultrastructure at primary visual cortex of monocular deprivation amblyopia rat within cortical period.Methods Taking randomized concurrent controlled trail.Establishing the model of monocular deprivation amblyopia rat.After proving the model successful by PVEP,all of the rats were randomly divided into three groups:normal visual cortex,experimental visual cortex and experimental opposite visual cortex.Immunocytochemical technology,electron microscope,photography microscope,computer image analysis,SPSS 11.5 and ANOV were used to get the resuhs.Results Compared with the layer Ⅳ of normal visual cortex and experimental opposite visual cortex,the area of immunopositive neurons in layer Ⅳ of experimental visual cortex are deficiency.there is significant difference between them(P<0.01).There are no significant differences between the other four corresponding layers(P>0.05).Morphological abnormals were found in layer Ⅳ of experimental visual cortex by observing of ultrastructure.Conclusion The expression of mGluR1 in layer Ⅳ of primary visual cortex of monocular deprivation amblyopia is reduced.There are morphological abnormals happened in layer Ⅳ of primary visual cortex of monocular derivation amblyopia.Reduced afference of nerve pulse because of monocular deprivation leads to the expression difficiency of mGluR1 in layer Ⅳ of the primary visual cortex,then synaptic plasticity happened,then neurons atrophy occurred may be one of the etiopathogenesis of amblyopia.%目的 探讨视觉形成关键期内单眼形觉剥夺弱视大鼠初级视皮质17区中代谢性谷氨酸受体1(mGluR1)的表达规律及神经元超微结构变化,为临床上揭示弱视的病理机制及防治提供依据.方法 随机对照同期动物实验.方法是建立大鼠单眼形觉剥夺弱视模型,经图形视觉诱发电位检测证实造模成功后,与正常对照组大鼠一起灌注

  12. 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.

  13. Rapid recovery from the effects of early monocular deprivation is enabled by temporary inactivation of the retinas

    Science.gov (United States)

    Fong, Ming-fai; Mitchell, Donald E.; Duffy, Kevin R.; Bear, Mark F.

    2016-01-01

    A half-century of research on the consequences of monocular deprivation (MD) in animals has revealed a great deal about the pathophysiology of amblyopia. MD initiates synaptic changes in the visual cortex that reduce acuity and binocular vision by causing neurons to lose responsiveness to the deprived eye. However, much less is known about how deprivation-induced synaptic modifications can be reversed to restore normal visual function. One theoretically motivated hypothesis is that a period of inactivity can reduce the threshold for synaptic potentiation such that subsequent visual experience promotes synaptic strengthening and increased responsiveness in the visual cortex. Here we have reduced this idea to practice in two species. In young mice, we show that the otherwise stable loss of cortical responsiveness caused by MD is reversed when binocular visual experience follows temporary anesthetic inactivation of the retinas. In 3-mo-old kittens, we show that a severe impairment of visual acuity is also fully reversed by binocular experience following treatment and, further, that prolonged retinal inactivation alone can erase anatomical consequences of MD. We conclude that temporary retinal inactivation represents a highly efficacious means to promote recovery of function. PMID:27856748

  14. MONOCULAR AND BINOCULAR VISION IN THE PERFORMANCE OF A COMPLEX SKILL

    Directory of Open Access Journals (Sweden)

    Thomas Heinen

    2011-09-01

    Full Text Available The goal of this study was to investigate the role of binocular and monocular vision in 16 gymnasts as they perform a handspring on vault. In particular we reasoned, if binocular visual information is eliminated while experts and apprentices perform a handspring on vault, and their performance level changes or is maintained, then such information must or must not be necessary for their best performance. If the elimination of binocular vision leads to differences in gaze behavior in either experts or apprentices, this would answer the question of an adaptive gaze behavior, and thus if this is a function of expertise level or not. Gaze behavior was measured using a portable and wireless eye-tracking system in combination with a movement-analysis system. Results revealed that gaze behavior differed between experts and apprentices in the binocular and monocular conditions. In particular, apprentices showed less fixations of longer duration in the monocular condition as compared to experts and the binocular condition. Apprentices showed longer blink duration than experts in both, the monocular and binocular conditions. Eliminating binocular vision led to a shorter repulsion phase and a longer second flight phase in apprentices. Experts exhibited no differences in phase durations between binocular and monocular conditions. Findings suggest, that experts may not rely on binocular vision when performing handsprings, and movement performance maybe influenced in apprentices when eliminating binocular vision. We conclude that knowledge about gaze-movement relationships may be beneficial for coaches when teaching the handspring on vault in gymnastics

  15. The contribution of monocular depth cues to scene perception by pigeons.

    Science.gov (United States)

    Cavoto, Brian R; Cook, Robert G

    2006-07-01

    The contributions of different monocular depth cues to performance of a scene perception task were investigated in 4 pigeons. They discriminated the sequential depth ordering of three geometric objects in computer-rendered scenes. The orderings of these objects were specified by the combined presence or absence of the pictorial cues of relative density, occlusion, and relative size. In Phase 1, the pigeons learned the task as a direct function of the number of cues present. The three monocular cues contributed equally to the discrimination. Phase 2 established that differential shading on the objects provided an additional discriminative cue. These results suggest that the pigeon visual system is sensitive to many of the same monocular depth cues that are known to be used by humans. The theoretical implications for a comparative psychology of picture processing are considered.

  16. 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.

  17. Progressive Susac syndrome with bilateral visual loss and disability

    Directory of Open Access Journals (Sweden)

    Morteza Entezari

    2016-01-01

    Full Text Available 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.

  18. Perioperative visual loss in ocular and nonocular surgery

    Directory of Open Access Journals (Sweden)

    Kathleen T Berg

    2010-06-01

    Full Text Available Kathleen T Berg, Andrew R Harrison, Michael S LeeDepartment of Ophthalmology, University of Minnesota, Minneapolis, MN, USAAbstract: Incidence estimates for perioperative vision loss (POVL after nonocular surgery range from 0.013% for all surgeries up to 0.2% following spine surgery. The most common neuro-ophthalmologic causes of POVL are the ischemic optic neuropathies (ION, either anterior (AION or posterior (PION. We identified 111 case reports of AION following nonocular surgery in the literature, with most occurring after cardiac surgery, and 165 case reports of PION following nonocular surgery, with most occurring after spine surgery or radical neck dissection. There were an additional 526 cases of ION that did not specify if the diagnosis was AION or PION. We also identified 933 case reports of central retinal artery occlusion (CRAO, 33 cases of pituitary apoplexy, and 245 cases of cortical blindness following nonocular surgery. The incidence of POVL following ocular surgery appears to be much lower than that seen following nonocular surgery. We identified five cases in the literature of direct optic nerve trauma, 47 cases of AION, and five cases of PION following ocular surgery. The specific pathogenesis and risk factors underlying these neuro-ophthalmic complications remain unknown, and physicians should be alert to the potential for loss of vision in the postoperative period.Keywords: perioperative, postoperative, vision loss, ocular surgery, nonocular surgery

  19. 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.

  20. Monocular Video Guided Garment Simulation

    Institute of Scientific and Technical Information of China (English)

    Fa-Ming Li; Xiao-Wu Chen∗; Bin Zhou; Fei-Xiang Lu; Kan Guo; Qiang Fu

    2015-01-01

    We present a prototype to generate a garment-shape sequence guided by a monocular video sequence. It is a combination of a physically-based simulation and a boundary-based modification. Given a garment in the video worn on a mannequin, the simulation generates a garment initial shape by exploiting the mannequin shapes estimated from the video. The modification then deforms the simulated 3D shape into such a shape that matches the garment 2D boundary extracted from the video. According to the matching correspondences between the vertices on the shape and the points on the boundary, the modification is implemented by attracting the matched vertices and their neighboring vertices. For best-matching correspondences and efficient performance, three criteria are introduced to select the candidate vertices for matching. Since modifying each garment shape independently may cause inter-frame oscillations, changes by the modification are also propagated from one frame to the next frame. As a result, the generated garment 3D shape sequence is stable and similar to the garment video sequence. We demonstrate the effectiveness of our prototype with a number of examples.

  1. Binocular and Monocular Depth Cues in Online Feedback Control of 3-D Pointing Movement

    Science.gov (United States)

    Hu, Bo; Knill, David C.

    2012-01-01

    Previous work has shown that humans continuously use visual feedback of the hand to control goal-directed movements online. In most studies, visual error signals were predominantly in the image plane and thus were available in an observer’s retinal image. We investigate how humans use visual feedback about finger depth provided by binocular and monocular depth cues to control pointing movements. When binocularly viewing a scene in which the hand movement was made in free space, subjects were about 60 ms slower in responding to perturbations in depth than in the image plane. When monocularly viewing a scene designed to maximize the available monocular cues to finger depth (motion, changing size and cast shadows), subjects showed no response to perturbations in depth. Thus, binocular cues from the finger are critical to effective online control of hand movements in depth. An optimal feedback controller that takes into account of the low peripheral stereoacuity and inherent ambiguity in cast shadows can explain the difference in response time in the binocular conditions and lack of response in monocular conditions. PMID:21724567

  2. Binocular and monocular depth cues in online feedback control of 3D pointing movement.

    Science.gov (United States)

    Hu, Bo; Knill, David C

    2011-06-30

    Previous work has shown that humans continuously use visual feedback of the hand to control goal-directed movements online. In most studies, visual error signals were predominantly in the image plane and, thus, were available in an observer's retinal image. We investigate how humans use visual feedback about finger depth provided by binocular and monocular depth cues to control pointing movements. When binocularly viewing a scene in which the hand movement was made in free space, subjects were about 60 ms slower in responding to perturbations in depth than in the image plane. When monocularly viewing a scene designed to maximize the available monocular cues to finger depth (motion, changing size, and cast shadows), subjects showed no response to perturbations in depth. Thus, binocular cues from the finger are critical to effective online control of hand movements in depth. An optimal feedback controller that takes into account the low peripheral stereoacuity and inherent ambiguity in cast shadows can explain the difference in response time in the binocular conditions and lack of response in monocular conditions.

  3. Progress in the study of the mechanism of visual cortical excitability and inhibition of balance in the visual cortex of monocular deprivation%单眼形觉剥夺触发视皮层兴奋与抑制平衡突触缩放调节机制的研究进展

    Institute of Scientific and Technical Information of China (English)

    宋德胜; 郭雅图; 陈霞

    2016-01-01

    突触缩放是稳态可塑性研究中最常用的形式,神经系统活动水平全局性的降低(如单眼形觉剥夺)可触发突触缩放机制。稳态可塑性对于维持神经元活动在正常范围内波动是必不可少的,它可以调控由于突触强度增强或减弱引起的过高或过低的神经网络活动水平。大脑皮层的兴奋性与抑制性平衡是维持正常脑功能的前提,而失衡则会诱发癫痫、帕金森及抑郁症等多种神经疾病。抑制性突触的可塑性,在兴奋性与抑制性平衡中扮演着关键角色。业内既往的研究,多数集中在新皮层和海马区的突触缩放稳态的可塑性方面,而对于视皮层区域的研究报导尚少。本文就单眼形觉剥夺触发的视皮层兴奋与抑制平衡稳态突触缩放调节机制的研究进展进行综述。%Synaptic scaling is the most commonly used form in the study of homeostasis , and the reduction in the level of activity of the nervous system ( monocular deprivation ) triggers the mechanism of synaptic scaling .Steady state plasticity is essential for maintaining neuronal activity in the normal range , and it can be regulated by the high or low level of neural network activity caused by the increase or decrease in synaptic strength .The excitatory and inhibitory balance of the cerebral cortex is the premise to maintain the normal function of the brain , and its imbalance will induce epilepsy , Parkinson, depression and other neurological disorders .Inhibitory synaptic plasticity plays a key role in the balance of excitatory and inhibitory properties .Study on the past , the plasticity of synaptic zoom steady state most concentrated in the neocortex and hippocampus , and to study the visual cortex area is less reported .This paper is mainly concerned with the monocular sleep deprivation triggers the progress in the study on the mechanism of regulation of visual cortex balance of excitatory and inhibitory of

  4. Monocular camera and IMU integration for indoor position estimation.

    Science.gov (United States)

    Zhang, Yinlong; Tan, Jindong; Zeng, Ziming; Liang, Wei; Xia, Ye

    2014-01-01

    This paper presents a monocular camera (MC) and inertial measurement unit (IMU) integrated approach for indoor position estimation. Unlike the traditional estimation methods, we fix the monocular camera downward to the floor and collect successive frames where textures are orderly distributed and feature points robustly detected, rather than using forward oriented camera in sampling unknown and disordered scenes with pre-determined frame rate and auto-focus metric scale. Meanwhile, camera adopts the constant metric scale and adaptive frame rate determined by IMU data. Furthermore, the corresponding distinctive image feature point matching approaches are employed for visual localizing, i.e., optical flow for fast motion mode; Canny Edge Detector & Harris Feature Point Detector & Sift Descriptor for slow motion mode. For superfast motion and abrupt rotation where images from camera are blurred and unusable, the Extended Kalman Filter is exploited to estimate IMU outputs and to derive the corresponding trajectory. Experimental results validate that our proposed method is effective and accurate in indoor positioning. Since our system is computationally efficient and in compact size, it's well suited for visually impaired people indoor navigation and wheelchaired people indoor localization.

  5. Surface formation and depth in monocular scene perception.

    Science.gov (United States)

    Albert, M K

    1999-01-01

    The visual perception of monocular stimuli perceived as 3-D objects has received considerable attention from researchers in human and machine vision. However, most previous research has focused on how individual 3-D objects are perceived. Here this is extended to a study of how the structure of 3-D scenes containing multiple, possibly disconnected objects and features is perceived. Da Vinci stereopsis, stereo capture, and other surface formation and interpolation phenomena in stereopsis and structure-from-motion suggest that small features having ambiguous depth may be assigned depth by interpolation with features having unambiguous depth. I investigated whether vision may use similar mechanisms to assign relative depth to multiple objects and features in sparse monocular images, such as line drawings, especially when other depth cues are absent. I propose that vision tends to organize disconnected objects and features into common surfaces to construct 3-D-scene interpretations. Interpolations that are too weak to generate a visible surface percept may still be strong enough to assign relative depth to objects within a scene. When there exists more than one possible surface interpolation in a scene, the visual system's preference for one interpolation over another seems to be influenced by a number of factors, including: (i) proximity, (ii) smoothness, (iii) a preference for roughly frontoparallel surfaces and 'ground' surfaces, (iv) attention and fixation, and (v) higher-level factors. I present a variety of demonstrations and an experiment to support this surface-formation hypothesis.

  6. 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.

  7. Hazard detection with a monocular bioptic telescope.

    Science.gov (United States)

    Doherty, Amy L; Peli, Eli; Luo, Gang

    2015-09-01

    The safety of bioptic telescopes for driving remains controversial. The ring scotoma, an area to the telescope eye due to the telescope magnification, has been the main cause of concern. This study evaluates whether bioptic users can use the fellow eye to detect in hazards driving videos that fall in the ring scotoma area. Twelve visually impaired bioptic users watched a series of driving hazard perception training videos and responded as soon as they detected a hazard while reading aloud letters presented on the screen. The letters were placed such that when reading them through the telescope the hazard fell in the ring scotoma area. Four conditions were tested: no bioptic and no reading, reading without bioptic, reading with a bioptic that did not occlude the fellow eye (non-occluding bioptic), and reading with a bioptic that partially-occluded the fellow eye. Eight normally sighted subjects performed the same task with the partially occluding bioptic detecting lateral hazards (blocked by the device scotoma) and vertical hazards (outside the scotoma) to further determine the cause-and-effect relationship between hazard detection and the fellow eye. There were significant differences in performance between conditions: 83% of hazards were detected with no reading task, dropping to 67% in the reading task with no bioptic, to 50% while reading with the non-occluding bioptic, and 34% while reading with the partially occluding bioptic. For normally sighted, detection of vertical hazards (53%) was significantly higher than lateral hazards (38%) with the partially occluding bioptic. Detection of driving hazards is impaired by the addition of a secondary reading like task. Detection is further impaired when reading through a monocular telescope. The effect of the partially-occluding bioptic supports the role of the non-occluded fellow eye in compensating for the ring scotoma. © 2015 The Authors Ophthalmic & Physiological Optics © 2015 The College of Optometrists.

  8. Bilateral progressive visual loss in an epileptic, mentally retarded boy

    Directory of Open Access Journals (Sweden)

    Silvana Guerriero

    2011-01-01

    Full Text Available Leber′s hereditary optic neuropathy (LHON is a maternally inherited, monosymptomatic disorder, characterized by severe central vision loss and optic atrophy that most frequently affects young men. The classic LHON phenotype is associated to three mitochondrial DNA mutations, mostly homoplasmic, in the Mt-ND4, Mt-ND6, and Mt-ND1 genes, encoding for complex I subunits of the mitochondrial respiratory chain. Rare cases have been described in the literature in association with variable central nervous system involvement in a syndromic form called LHON ′plus.′ In the present study, we report the case of a 16-year-old boy with the 3460/ND1 mutation who presented with epilepsy, migraine, and mental retardation as non-ophthalmic features. We also investigated his relatives who all had the 3460/ND1 mutation.

  9. Visual loss secondary to eosinophilic mucin rhinosinusitis in a woman: a case report

    Directory of Open Access Journals (Sweden)

    Joshi Naresh

    2010-10-01

    Full Text Available Abstract Introduction Eosinophilic mucin rhinosinusitis is an inflammatory pathological condition of the nose and paranasal sinuses. It is rare, occurs in immunocompetent patients and is characterised by peripheral eosinophilia and extensive bilateral sinus disease. To the best of our knowledge, visual loss with this condition has not been previously reported. Case presentation We present the case of a 26-year-old Asian woman with a background history of chronic sinusitis who presented with acute left-sided visual loss. Imaging showed significant opacification in the frontal, ethmoidal and sphenoidal sinuses as well as evidence of a unilateral optic neuritis. Histological analysis of sinus mucin revealed dense eosinophilic infiltrate and, despite medical and surgical intervention, vision was not restored in her left eye. Conclusion We introduce visual loss as a complication of eosinophilic mucin rhinosinusitis. This adds further evidence to previous reports in the literature that optic neuropathy in sinusitis can occur secondary to non-compressive mechanisms. We also describe a rare finding: the vision in this patient did not improve following steroid therapy, antifungal therapy or surgical intervention. There are very few such cases described in the literature. We conclude that chronic sinusitis is an indolent inflammatory process which can cause visual loss and we reiterate the importance of recognizing and considering sinusitis as a cause of visual loss in patients in order that prompt medical and surgical treatment of the underlying disease can be initiated.

  10. Sphenoidal sinus mucocele presenting with acute visual loss in a scuba diver

    Science.gov (United States)

    Mowatt, Lizette; Foster, Tecah

    2013-01-01

    A 43-year-old male scuba diver presented with an acute history of painful unilateral visual loss after scuba diving. He had right-sided retrobulbar pain and headache. He was known to have sinusitis and had transient visual loss in two previous episodes after scuba diving. His visual acuity was hand motions and 20/20 in the right and left eye, respectively. There was no proptosis. He had a right relative afferent pupillary defect. Colour vision was normal in the left eye and absent in the right eye. Fundal examination revealed healthy discs and macula bilaterally. He was assessed as a right optic neuropathy, possibly secondary to compression. An MRI of the brain revealed a large sphenoidal mucocele extending into the right optic foramen. He was treated with oral steroids, antibiotics and nasal decongestants. He underwent endoscopic intranasal sphenoidectomy and marsupialisation with return of his visual acuity to 20/25 in that eye. PMID:23964041

  11. Depth scaling in phantom and monocular gap stereograms using absolute distance information.

    Science.gov (United States)

    Kuroki, Daiichiro; Nakamizo, Sachio

    2006-11-01

    The present study aimed to investigate whether the visual system scales apparent depth from binocularly unmatched features by using absolute distance information. In Experiment 1 we examined the effect of convergence on perceived depth in phantom stereograms [Gillam, B., & Nakayama, K. (1999). Quantitative depth for a phantom surface can be based on cyclopean occlusion cues alone. Vision Research, 39, 109-112.], monocular gap stereograms [Pianta, M. J., & Gillam, B. J. (2003a). Monocular gap stereopsis: manipulation of the outer edge disparity and the shape of the gap. Vision Research, 43, 1937-1950.] and random dot stereograms. In Experiments 2 and 3 we examined the effective range of viewing distances for scaling the apparent depths in these stereograms. The results showed that: (a) the magnitudes of perceived depths increased in all stereograms as the estimate of the viewing distance increased while keeping proximal and/or distal sizes of the stimuli constant, and (b) the effective range of viewing distances was significantly shorter in monocular gap stereograms. The first result indicates that the visual system scales apparent depth from unmatched features as well as that from horizontal disparity, while the second suggests that, at far distances, the strength of the depth signal from an unmatched feature in monocular gap stereograms is relatively weaker than that from horizontal disparity.

  12. TRANSIENT SUDDEN BILATERAL VISUAL LOSS AFTER ORTHOTOPIC HEART TRANSPLANTATION: A CASE REPORT

    Directory of Open Access Journals (Sweden)

    S. K. Forouzannia

    2005-07-01

    Full Text Available Post cardiac surgery ophthalmic complications are uncommon, and sudden visual loss is one of the most important ophthalmic problems in these patients. We report a 54-year-old woman that suffered transient sudden bilateral visual loss seven days after orthotopic heart transplantation. In ophthalmologic examination positive findings were bilateral normal size pupils without direct and indirect pupillary light reflex and bilateral severe diffuse vasospasm of retinal arteries. Other ophthalmologic findings were normal. Problem lasts for 12 hours and resolved spontaneously. Funduscopic examination identified bilateral normal retina at this time and fluorescein angiography revealed normal retinal vasculature. This presentation suggests retinal vasospasm as an unusual benign cause of bilateral sudden visual loss after orthotopic heart transplantation.

  13. 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

  14. Visibility of monocular symbology in transparent head-mounted display applications

    Science.gov (United States)

    Winterbottom, M.; Patterson, R.; Pierce, B.; Gaska, J.; Hadley, S.

    2015-05-01

    With increased reliance on head-mounted displays (HMDs), such as the Joint Helmet Mounted Cueing System and F-35 Helmet Mounted Display System, research concerning visual performance has also increased in importance. Although monocular HMDs have been used successfully for many years, a number of authors have reported significant problems with their use. Certain problems have been attributed to binocular rivalry when differing imagery is presented to the two eyes. With binocular rivalry, the visibility of the images in the two eyes fluctuates, with one eye's view becoming dominant, and thus visible, while the other eye's view is suppressed, which alternates over time. Rivalry is almost certainly created when viewing an occluding monocular HMD. For semi-transparent monocular HMDs, however, much of the scene is binocularly fused, with additional imagery superimposed in one eye. Binocular fusion is thought to prevent rivalry. The present study was designed to investigate differences in visibility between monocularly and binocularly presented symbology at varying levels of contrast and while viewing simulated flight over terrain at various speeds. Visibility was estimated by measuring the presentation time required to identify a test probe (tumbling E) embedded within other static symbology. Results indicated that there were large individual differences, but that performance decreased with decreased test probe contrast under monocular viewing relative to binocular viewing conditions. Rivalry suppression may reduce visibility of semi-transparent monocular HMD imagery. However, factors, such as contrast sensitivity, masking, and conditions such as monofixation, will be important to examine in future research concerning visibility of HMD imagery.

  15. Detection of Visual Field Loss in Pituitary Disease: Peripheral Kinetic Versus Central Static.

    Science.gov (United States)

    Rowe, Fiona J; Cheyne, Christopher P; García-Fiñana, Marta; Noonan, Carmel P; Howard, Claire; Smith, Jayne; Adeoye, Joanne

    2015-06-01

    Visual field assessment is an important clinical evaluation for eye disease and neurological injury. We evaluated Octopus semi-automated kinetic peripheral perimetry (SKP) and Humphrey static automated central perimetry for detection of neurological visual field loss in patients with pituitary disease. We carried out a prospective cross-sectional diagnostic accuracy study comparing Humphrey central 30-2 SITA threshold programme with a screening protocol for SKP on Octopus perimetry. Humphrey 24-2 data were extracted from 30-2 results. Results were independently graded for presence/absence of field defect plus severity of defect. Fifty patients (100 eyes) were recruited (25 males and 25 females), with mean age of 52.4 years (SD = 15.7). Order of perimeter assessment (Humphrey/Octopus first) and order of eye tested (right/left first) were randomised. The 30-2 programme detected visual field loss in 85%, the 24-2 programme in 80%, and the Octopus combined kinetic/static strategy in 100% of eyes. Peripheral visual field loss was missed by central threshold assessment. Qualitative comparison of type of visual field defect demonstrated a match between Humphrey and Octopus results in 58%, with a match for severity of defect in 50%. Tests duration was 9.34 minutes (SD = 2.02) for Humphrey 30-2 versus 10.79 minutes (SD = 4.06) for Octopus perimetry. Octopus semi-automated kinetic perimetry was found to be superior to central static testing for detection of pituitary disease-related visual field loss. Where reliant on Humphrey central static perimetry, the 30-2 programme is recommended over the 24-2 programme. Where kinetic perimetry is available, this is preferable to central static programmes for increased detection of peripheral visual field loss.

  16. TRANSIENT VISUAL LOSS FOLLOWING FORAMEN MAGNUM DECOMPRESSION - SURGERY IN PRONE POSITION: A CASE REPORT

    OpenAIRE

    Nayak,, T. K.; Anantha; Balasubrahmanyam; Patil; Savitha

    2016-01-01

    Perioperative visual loss is an uncommon complication of surgery in the prone position, spinal surgery, and is also reported after cardiac surgery. It is important that the nursing faculty, attending on patients recovering from general anaesthesia for these procedures, check the vision immediately upon recovery. Prompt referral is essential if the patient has a deficit that was not noticed earlier. Visual deficit can be due to ischaemic optic neuropathy (Anterior or posterior), r...

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

    DEFF Research Database (Denmark)

    Ostri, Christoffer; Zibrandtsen, Nathalie; Larsen, Michael;

    2014-01-01

    ) 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....... 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....

  18. Visual loss due to progressive multifocal leukoencephalopathy in a heart transplant patient.

    Science.gov (United States)

    Lewis, A R; Kline, L B; Pinkard, N B

    1993-12-01

    A 59-year-old male heart transplant recipient experienced progressive visual loss following routine cataract surgery with intraocular lens implantation. Cranial magnetic resonance (MR) imaging suggested and brain biopsy confirmed the cause to be progressive multifocal leukoencephalopathy (PML). The patient died 2 months following cataract surgery. This case illustrates that visual failure may be the initial manifestation of PML, and the ophthalmologist should be aware of this central demyelinating disorder when dealing with immunocompromised patients.

  19. Retinal NFL thinning on OCT correlates with visual field loss in pediatric craniopharyngioma.

    Science.gov (United States)

    Bialer, Omer Y; Goldenberg-Cohen, Nitza; Toledano, Helen; Snir, Moshe; Michowiz, Shalom

    2013-12-01

    To investigate the use of peripapillary optical coherence tomography for monitoring optic neuropathy in pediatric craniopharyngioma. Retrospective, consecutive-cohort, single-centre chart analysis. Twenty children with craniopharyngioma treated at a pediatric medical centre from 1999 to 2011. The medical files were reviewed for demographics and optic nerve function. Findings for visual acuity and visual fields were analyzed against repeated optical coherence tomography (OCT) measurements of peripapillary nerve fibre layer thickness (using either time-domain Stratus OCT or spectral-domain Cirrus OCT). Average age at diagnosis was 6.5 ± 3.88 years. The most common presenting symptom was headache; only 1 child complained of visual loss. Mean best corrected visual acuity (logMAR) was 0.036 ± 0.06 in the 17 healthy eyes and 1.05 ± 1.45 in the 23 eyes with optic neuropathy. Positive signs included relative afferent pupillary defect (8/20), visual acuity loss (7/20), temporal visual field loss (bilateral 4/15, unilateral 4/15), papilledema (3/20), and unilateral/bilateral optic disc pallor (14/20). RNFL thickness was significantly lower in eyes with optic neuropathy than in healthy eyes (65 ± 22 µm vs 86.2 ± 29 µm; p = 0.000) and correlated with visual acuity (r = -0.43 to -0.17, p = 0.0001) and presence or absence of a visual field defect (mean difference, 26.1 ± 5.8 µm, p = 0.003). Ten children showed no change in RNFL thickness over time (mean 18 ± 14.2 months). A thinner RNFL on ocular coherence tomography is correlated with poorer visual acuity and visual field loss. Ocular coherence tomography may serve as an objective method to quantify axonal loss caused by craniopharyngioma. Further investigation is needed to determine its use for evaluating progressive axonal loss over time. Copyright © 2013 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.

  20. 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.

  1. 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.

  2. [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

    2016-01-21

    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.

  3. 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.

  4. Disparity biasing in depth from monocular occlusions.

    Science.gov (United States)

    Tsirlin, Inna; Wilcox, Laurie M; Allison, Robert S

    2011-07-15

    Monocular occlusions have been shown to play an important role in stereopsis. Among other contributions to binocular depth perception, monocular occlusions can create percepts of illusory occluding surfaces. It has been argued that the precise location in depth of these illusory occluders is based on the constraints imposed by occlusion geometry. Tsirlin et al. (2010) proposed that when these constraints are weak, the depth of the illusory occluder can be biased by a neighboring disparity-defined feature. In the present work we test this hypothesis using a variety of stimuli. We show that when monocular occlusions provide only partial constraints on the magnitude of depth of the illusory occluders, the perceived depth of the occluders can be biased by disparity-defined features in the direction unrestricted by the occlusion geometry. Using this disparity bias phenomenon we also show that in illusory occluder stimuli where disparity information is present, but weak, most observers rely on disparity while some use occlusion information instead to specify the depth of the illusory occluder. Taken together our experiments demonstrate that in binocular depth perception disparity and monocular occlusion cues interact in complex ways to resolve perceptual ambiguity. Copyright © 2011 Elsevier Ltd. All rights reserved.

  5. Quantification of visual field loss in age-related macular degeneration.

    Directory of Open Access Journals (Sweden)

    Jennifer H Acton

    Full Text Available BACKGROUND: An evaluation of standard automated perimetry (SAP and short wavelength automated perimetry (SWAP for the central 10-2 visual field test procedure in patients with age-related macular degeneration (AMD is presented in order to determine methods of quantifying the central sensitivity loss in patients at various stages of AMD. METHODS: 10-2 SAP and SWAP Humphrey visual fields and stereoscopic fundus photographs were collected in 27 eyes of 27 patients with AMD and 22 eyes of 22 normal subjects. RESULTS: Mean Deviation and Pattern Standard Deviation (PSD varied significantly with stage of disease in SAP (both p<0.001 and SWAP (both p<0.001, but post hoc analysis revealed overlap of functional values among stages. In SWAP, indices of focal loss were more sensitive to detecting differences in AMD from normal. SWAP defects were greater in depth and area than those in SAP. Central sensitivity (within 1° changed by -3.9 and -4.9 dB per stage in SAP and SWAP, respectively. Based on defect maps, an AMD Severity Index was derived. CONCLUSIONS: Global indices of focal loss were more sensitive to detecting early stage AMD from normal. The SWAP sensitivity decline with advancing stage of AMD was greater than in SAP. A new AMD Severity Index quantifies visual field defects on a continuous scale. Although not all patients are suitable for SWAP examinations, it is of value as a tool in research studies of visual loss in AMD.

  6. 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 po

  7. Role of Visual Speech in Phonological Processing by Children with Hearing Loss

    Science.gov (United States)

    Jerger, Susan; Tye-Murray, Nancy; Abdi, Herve

    2009-01-01

    Purpose: This research assessed the influence of visual speech on phonological processing by children with hearing loss (HL). Method: Children with HL and children with normal hearing (NH) named pictures while attempting to ignore auditory or audiovisual speech distractors whose onsets relative to the pictures were either congruent, conflicting in…

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

    NARCIS (Netherlands)

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

    2001-01-01

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

  9. 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

  10. Importance of diazepam administration during electroencephalography in the differential diagnosis of cortical visual loss.

    Science.gov (United States)

    Yis, Uluc; Topcu, Yasemin; Bayram, Erhan; Karakaya, Pakize; Cakmakci, Handan; Kurul, Semra Hiz

    2014-01-01

    A 14-year-old boy presented with acute visual loss due to cortical blindness. Two weeks after the visual symptoms, the patient developed behavioral abnormalities. Brain magnetic resonance imaging (MRI) revealed hyperintense lesions at parieto-occipital lobes on T2-weighted and fluid attenuated inversion recovery images. Sleep and awake electroencephalography (EEG) were normal, but diazepam administration revealed bilateral periodic synchronous complexes occurring every 20 to 30 seconds. Elevated measles antibody titers in cerebrospinal fluid confirmed the diagnosis of subacute sclerosing panencephalitis. We conclude that visual loss due to cortical blindness is an important finding of subacute sclerosing panencephalitis. Diazepam administration during EEG should be a part of investigation in cases with unexplained cortical blindness.

  11. Perception of Acceleration in Motion-In-Depth With Only Monocular and Binocular Information

    Directory of Open Access Journals (Sweden)

    Santiago Estaún

    2003-01-01

    Full Text Available Percepción de la aceleración en el movimiento en profundidad con información monocular y con información monocular y binocular. En muchas ocasiones es necesario adecuar nuestras acciones a objetos que cambian su aceleración. Sin embargo, no se ha encontrado evidencia de una percepción directa de la aceleración. En su lugar, parece ser que somos capaces de detectar cambios de velocidad en el movimiento 2-D dentro de una ventana temporal. Además, resultados recientes sugieren que el movimiento en profundidad se detecta a través de cambios de posición. Por lo tanto, para detectar aceleración en profundidad sería necesario que el sistema visual lleve a cabo algun tipo de cómputo de segundo orden. En dos experimentos, mostramos que los observadores no perciben la aceleración en trayectorias de aproximación, al menos en los rangos que utilizados [600- 800 ms] dando como resultado una sobreestimación del tiempo de llegada. Independientemente de la condición de visibilidad (sólo monocular o monocular más binocular, la respuesta se ajusta a una estrategia de velocidad constante. No obstante, la sobreestimación se reduce cuando la información binocular está disponible.

  12. Rapid improvement in visual loss with cabergoline treatment in a giant prolactinoma case: 5 years survey.

    Science.gov (United States)

    Tasan, Ertugrul; Hanimoglu, Hakan; Turgut, Seda; Ilhan, Mahmut Muzaffer; Evran, Sevket; Kaynar, Mehmet Yasar

    2015-01-01

    Giant prolactinoma is a rare subset of macroadenomas. Limited studies demonstrated which therapy could be successfully used in the first-line therapy of giant prolactinoma. We presented a case with a 54 × 40 × 40 mm pituitary adenoma and optic chiasmatic compression with left sphenoid sinus invasion. The tumor caused a loss of visual field of the right side. Cabergoline treatment was started with dose of 1.5 mg/week. Fifteen days later, the clinical visual acuity examination showed a significant improvement in the patient with visual field defect. After the five years follow-up magnetic resonance imagining showed reduction of the adenoma size (17 × 12 mm) was significant. Our findings suggest that, cabergoline can be used as a first-line therapy in giant prolactinomas because tumoral shrinkage without a surgical procedure and rapid improvement in visual field defect is achieved with this medical treatment.

  13. Monocular vision based navigation method of mobile robot

    Institute of Scientific and Technical Information of China (English)

    DONG Ji-wen; YANG Sen; LU Shou-yin

    2009-01-01

    A trajectory tracking method is presented for the visual navigation of the monocular mobile robot. The robot move along line trajectory drawn beforehand, recognized and stop on the stop-sign to finish special task. The robot uses a forward looking colorful digital camera to capture information in front of the robot, and by the use of HSI model partition the trajectory and the stop-sign out. Then the "sampling estimate" method was used to calculate the navigation parameters. The stop-sign is easily recognized and can identify 256 different signs. Tests indicate that the method can fit large-scale intensity of brightness and has more robustness and better real-time character.

  14. Monocular Obstacle Detection for Real-World Environments

    Science.gov (United States)

    Einhorn, Erik; Schroeter, Christof; Gross, Horst-Michael

    In this paper, we present a feature based approach for monocular scene reconstruction based on extended Kaiman filters (EKF). Our method processes a sequence of images taken by a single camera mounted in front of a mobile robot. Using various techniques we are able to produce a precise reconstruction that is almost free from outliers and therefore can be used for reliable obstacle detection and avoidance. In real-world field tests we show that the presented approach is able to detect obstacles that can not be seen by other sensors, such as laser range finders. Furthermore, we show that visual obstacle detection combined with a laser range finder can increase the detection rate of obstacles considerably, allowing the autonomous use of mobile robots in complex public and home environments.

  15. Frequent Self-Weighing and Visual Feedback for Weight Loss in Overweight Adults

    Directory of Open Access Journals (Sweden)

    Carly R. Pacanowski

    2015-01-01

    Full Text Available Evidence has suggested that self-weighing may be beneficial for weight control in adults, but few studies have independently assessed the contribution of this behavior to weight loss. This study experimentally tested daily self-weighing and visual feedback (the Caloric Titration Method (CTM as a weight loss and weight loss maintenance intervention over 2 years. 162 overweight individuals were randomized to the CTM intervention or delayed treatment control group. In year 1, weight change was compared between groups, and in year 2, the control group started using the CTM while the intervention group continued using the CTM for maintenance. A significant difference in weight loss over the first year (CTM n = 70; 2.6 ± 5.9 kg versus control n = 65; 0.5 ± 4.4 kg, p = 0.019 was qualified by a group × gender × time interaction (p = 0.002 such that men lost more weight using the CTM. In year 2, the CTM group maintained their weight and the control group lost an amount similar to the intervention group in year 1. Daily self-weighing and visual feedback facilitated a minimal amount of weight loss and maintenance of this loss. Future research investigating characteristics of those who benefit from this type of self-directed intervention is warranted.

  16. Monocular and binocular depth discrimination thresholds.

    Science.gov (United States)

    Kaye, S B; Siddiqui, A; Ward, A; Noonan, C; Fisher, A C; Green, J R; Brown, M C; Wareing, P A; Watt, P

    1999-11-01

    Measurement of stereoacuity at varying distances, by real or simulated depth stereoacuity tests, is helpful in the evaluation of patients with binocular imbalance or strabismus. Although the cue of binocular disparity underpins stereoacuity tests, there may be variable amounts of other binocular and monocular cues inherent in a stereoacuity test. In such circumstances, a combined monocular and binocular threshold of depth discrimination may be measured--stereoacuity conventionally referring to the situation where binocular disparity giving rise to retinal disparity is the only cue present. A child-friendly variable distance stereoacuity test (VDS) was developed, with a method for determining the binocular depth threshold from the combined monocular and binocular threshold of depth of discrimination (CT). Subjects with normal binocular function, reduced binocular function, and apparently absent binocularity were included. To measure the threshold of depth discrimination, subjects were required by means of a hand control to align two electronically controlled spheres at viewing distances of 1, 3, and 6m. Stereoacuity was also measured using the TNO, Frisby, and Titmus stereoacuity tests. BTs were calculated according to the function BT= arctan (1/tan alphaC - 1/tan alphaM)(-1), where alphaC and alphaM are the angles subtended at the nodal points by objects situated at the monocular threshold (alphaM) and the combined monocular-binocular threshold (alphaC) of discrimination. In subjects with good binocularity, BTs were similar to their combined thresholds, whereas subjects with reduced and apparently absent binocularity had binocular thresholds 4 and 10 times higher than their combined thresholds (CT). The VDS binocular thresholds showed significantly higher correlation and agreement with the TNO test and the binocular thresholds of the Frisby and Titmus tests, than the corresponding combined thresholds (p = 0.0019). The VDS was found to be an easy to use real depth

  17. Benign pituitary adenoma associated with hyperostosis of the spenoid bone and monocular blindness. Case report.

    Science.gov (United States)

    Milas, R W; Sugar, O; Dobben, G

    1977-01-01

    The authors describe a case of benign chromophobe adenoma associated with hyperostosis of the lesser wing of the sphenoid bone and monocular blindness in a 38-year-old woman. The endocrinological and radiological evaluations were all suggestive of a meningioma. The diagnosis was established by biopsy of the tumor mass. After orbital decompression and removal of the tumor, the patient was treated with radiation therapy. Her postoperative course was uneventful, and her visual defects remained fixed.

  18. Quantitative perceived depth from sequential monocular decamouflage.

    Science.gov (United States)

    Brooks, K R; Gillam, B J

    2006-03-01

    We present a novel binocular stimulus without conventional disparity cues whose presence and depth are revealed by sequential monocular stimulation (delay > or = 80 ms). Vertical white lines were occluded as they passed behind an otherwise camouflaged black rectangular target. The location (and instant) of the occlusion event, decamouflaging the target's edges, differed in the two eyes. Probe settings to match the depth of the black rectangular target showed a monotonic increase with simulated depth. Control tests discounted the possibility of subjects integrating retinal disparities over an extended temporal window or using temporal disparity. Sequential monocular decamouflage was found to be as precise and accurate as conventional simultaneous stereopsis with equivalent depths and exposure durations.

  19. 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.

  20. 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.

  1. Outdoor autonomous navigation using monocular vision

    OpenAIRE

    Royer, Eric; Bom, Jonathan; Dhome, Michel; Thuilot, Benoît; Lhuillier, Maxime; Marmoiton, Francois

    2005-01-01

    International audience; In this paper, a complete system for outdoor robot navigation is presented. It uses only monocular vision. The robot is first guided on a path by a human. During this learning step, the robot records a video sequence. From this sequence, a three dimensional map of the trajectory and the environment is built. When this map has been computed, the robot is able to follow the same trajectory by itself. Experimental results carried out with an urban electric vehicle are sho...

  2. Raised intraocular pressure as a potential risk factor for visual loss in Leber Hereditary Optic Neuropathy.

    Directory of Open Access Journals (Sweden)

    Anais Thouin

    Full Text Available Leber Hereditary Optic Neuropathy (LHON is an important cause of inherited mitochondrial blindness among young adults. The majority of patients carry one of three mitochondrial DNA (mtDNA point mutations: m.3460G>A, m.11778G>A and m.14484T>C, all of which affect critical complex I subunits of the mitochondrial respiratory chain. LHON is characterised by marked incomplete penetrance, clearly implying that the mtDNA mutation is insufficient on its own to trigger retinal ganglion cell dysfunction and visual loss. In this case series of three affected patients harbouring the m.11778G>A mutation, we provide evidence suggesting that raised intraocular pressure could be a risk factor triggering visual loss in at-risk LHON carriers.

  3. Raised intraocular pressure as a potential risk factor for visual loss in Leber Hereditary Optic Neuropathy.

    Science.gov (United States)

    Thouin, Anais; Griffiths, Philip G; Hudson, Gavin; Chinnery, Patrick F; Yu-Wai-Man, Patrick

    2013-01-01

    Leber Hereditary Optic Neuropathy (LHON) is an important cause of inherited mitochondrial blindness among young adults. The majority of patients carry one of three mitochondrial DNA (mtDNA) point mutations: m.3460G>A, m.11778G>A and m.14484T>C, all of which affect critical complex I subunits of the mitochondrial respiratory chain. LHON is characterised by marked incomplete penetrance, clearly implying that the mtDNA mutation is insufficient on its own to trigger retinal ganglion cell dysfunction and visual loss. In this case series of three affected patients harbouring the m.11778G>A mutation, we provide evidence suggesting that raised intraocular pressure could be a risk factor triggering visual loss in at-risk LHON carriers.

  4. The detection of hidden visual loss in optic neuropathy: VISTECH test at variable illuminations.

    Science.gov (United States)

    Leys, M J; Candaele, C M; Uvijls, A G; Heintz, B F; De Rouck, A F; Odom, J V

    1990-01-01

    The sensitivity of the VISTECH chart in the detection of hidden visual loss is debated. We tried to evaluate the diagnostic value of the test by using different illumination levels. Twelve MS-patients with normal acuity but a pathological VEP were examined at 9 different illuminations. We did not identify more abnormalities among patients, using VISTECH test at other illumination levels than the one recommended by the manufacturer.

  5. Topiramate and visual loss in a patient carrying a Leber hereditary optic neuropathy mutation.

    Science.gov (United States)

    Rinalduzzi, Steno; Cipriani, Anna Maria; Accornero, Neri

    2012-04-01

    We describe a 43-year-old patient who experienced visual loss 4 years after beginning antiepileptic therapy with topiramate. Ophthalmological and neurological examinations led to a preliminary diagnosis of bilateral toxic optic neuritis. Mitochondrial genome sequence analysis detected a Leber hereditary optic neuropathy 11778G>A mutation. The possibility that topiramate might favor a conversion disease, alerts physicians to seek a history of blindness in patients undergoing chronic antiepileptic therapy.

  6. Detecting Glaucoma With a Portable Brain-Computer Interface for Objective Assessment of Visual Function Loss.

    Science.gov (United States)

    Nakanishi, Masaki; Wang, Yu-Te; Jung, Tzyy-Ping; Zao, John K; Chien, Yu-Yi; Diniz-Filho, Alberto; Daga, Fabio B; Lin, Yuan-Pin; Wang, Yijun; Medeiros, Felipe A

    2017-06-01

    The current assessment of visual field loss in diseases such as glaucoma is affected by the subjectivity of patient responses and the lack of portability of standard perimeters. To describe the development and initial validation of a portable brain-computer interface (BCI) for objectively assessing visual function loss. This case-control study involved 62 eyes of 33 patients with glaucoma and 30 eyes of 17 healthy participants. Glaucoma was diagnosed based on a masked grading of optic disc stereophotographs. All participants underwent testing with a BCI device and standard automated perimetry (SAP) within 3 months. The BCI device integrates wearable, wireless, dry electroencephalogram and electrooculogram systems and a cellphone-based head-mounted display to enable the detection of multifocal steady state visual-evoked potentials associated with visual field stimulation. The performances of global and sectoral multifocal steady state visual-evoked potentials metrics to discriminate glaucomatous from healthy eyes were compared with global and sectoral SAP parameters. The repeatability of the BCI device measurements was assessed by collecting results of repeated testing in 20 eyes of 10 participants with glaucoma for 3 sessions of measurements separated by weekly intervals. Receiver operating characteristic curves summarizing diagnostic accuracy. Intraclass correlation coefficients and coefficients of variation for assessing repeatability. Among the 33 participants with glaucoma, 19 (58%) were white, 12 (36%) were black, and 2 (6%) were Asian, while among the 17 participants with healthy eyes, 9 (53%) were white, 8 (47%) were black, and none were Asian. The receiver operating characteristic curve area for the global BCI multifocal steady state visual-evoked potentials parameter was 0.92 (95% CI, 0.86-0.96), which was larger than for SAP mean deviation (area under the curve, 0.81; 95% CI, 0.72-0.90), SAP mean sensitivity (area under the curve, 0.80; 95% CI, 0

  7. 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

  8. Visual pathway axonal loss in benign multiple sclerosis: a longitudinal study.

    Science.gov (United States)

    Galetta, Kristin M; Graves, Jennifer; Talman, Lauren S; Lile, Deacon J; Frohman, Elliot M; Calabresi, Peter A; Galetta, Steven L; Balcer, Laura J

    2012-06-01

    Benign multiple sclerosis (MS), traditionally defined as Expanded Disability Status Scale (EDSS) score ≤3 and ≥15-year disease duration, is thought to follow a milder clinical course. We determined the extent of visual pathway axonal loss by optical coherence tomography (OCT) retinal nerve fiber layer (RNFL) thickness in a benign MS cohort and examined the relation to vision and quality of life (QOL). In this longitudinal study of vision in MS at 3 academic centers, a subset of patients with EDSS, visual function, OCT, and QOL assessments was analyzed. Low- and high-contrast letter acuity was performed to assess visual function. RNFL thickness was determined using time-domain OCT. QOL scales included the 25-Item National Eye Institute Visual Functioning Questionnaire (NEI-VFQ-25) and Short Form-36 Health Survey. Among 68 patients (135 eyes) studied longitudinally, 13 (26 eyes) had benign MS using criteria of EDSS score ≤3 and ≥15-year disease duration. Benign MS eyes had as much RNFL thinning (-3.6 μm, P = 0.0008 vs baseline, paired t test) as typical MS eyes (-3.3 μm, P MS (69% vs 33% of eyes). History of ON distinguished benign vs typical MS (P = 0.002) and correlated with RNFL thickness at baseline (P = 0.002) and disease duration (P = 0.03) but not EDSS (P = 0.32, logistic regression). NEI-VFQ-25 scores were also worse for benign MS, accounting for age (75 ± 21 vs 88 ± 11, P = 0.005). Patients with benign MS have RNFL axonal loss that is as marked as that of typical MS and have reduced vision and QOL. While overall neurologic impairment is mild, visual dysfunction, not well captured by the EDSS, accounts for a substantial degree of disability in benign MS.

  9. Acute visual loss with ophthalmoplegia after spinal surgery: report of a case and review of the literature.

    Science.gov (United States)

    Mukherjee, Bipasha; Alam, Mohammad Shahid

    2014-09-01

    We report a case of a 15-year-old boy who presented with profound visual loss and complete ophthalmoplegia after an uneventful spinal surgery for removal of cervical osteoblastoma. Postoperative visual loss following nonocular surgery is, fortunately rare, yet a devastating complication. The most common cause is ischemic optic neuropathy, but it can also be due to central retinal occlusion or cortical blindness. Visual loss in conjunction with ophthalmoplegia is rarely seen, and there are very few reports in the literature. We also review the related literature and highlight the mechanism and preventive measures.

  10. Acute visual loss with ophthalmoplegia after spinal surgery: Report of a case and review of the literature

    Directory of Open Access Journals (Sweden)

    Bipasha Mukherjee

    2014-01-01

    Full Text Available We report a case of a 15-year-old boy who presented with profound visual loss and complete ophthalmoplegia after an uneventful spinal surgery for removal of cervical osteoblastoma. Postoperative visual loss following nonocular surgery is, fortunately rare, yet a devastating complication. The most common cause is ischemic optic neuropathy, but it can also be due to central retinal occlusion or cortical blindness. Visual loss in conjunction with ophthalmoplegia is rarely seen, and there are very few reports in the literature. We also review the related literature and highlight the mechanism and preventive measures.

  11. For whales and seals the ocean is not blue: a visual pigment loss in marine mammals.

    Science.gov (United States)

    Peichl, L; Behrmann, G; Kröger, R H

    2001-04-01

    Most terrestrial mammals have colour vision based on two spectrally different visual pigments located in two types of retinal cone photoreceptors, i.e. they are cone dichromats with long-to-middle-wave-sensitive (commonly green) L-cones and short-wave-sensitive (commonly blue) S-cones. With visual pigment-specific antibodies, we here demonstrate an absence of S-cones in the retinae of all whales and seals studied. The sample includes seven species of toothed whales (Odontoceti) and five species of marine carnivores (eared and earless seals). These marine mammals have only L-cones (cone monochromacy) and hence are essentially colour-blind. For comparison, the study also includes the wolf, ferret and European river otter (Carnivora) as well as the mouflon and pygmy hippopotamus (Artiodactyla), close terrestrial relatives of the seals and whales, respectively. These have a normal complement of S-cones and L-cones. The S-cone loss in marine species from two distant mammalian orders strongly argues for convergent evolution and an adaptive advantage of that trait in the marine visual environment. To us this suggests that the S-cones may have been lost in all whales and seals. However, as the spectral composition of light in clear ocean waters is increasingly blue-shifted with depth, an S-cone loss would seem particularly disadvantageous. We discuss some hypotheses to explain this paradox.

  12. Driving with central visual field loss I: Impact of central scotoma on response to hazards

    Science.gov (United States)

    Bronstad, P. Matthew; Bowers, Alex R.; Albu, Amanda; Goldstein, Robert; Peli, Eli

    2012-01-01

    Objective To determine how central field loss (CFL) affects reaction time to pedestrians and test the hypothesis that scotomas lateral to the preferred retinal locus will delay detection of hazards approaching from that side. Methods Eleven participants with binocular CFL (scotoma diameter 7°-25°; VA 0.3-1.0 logMAR) using lateral preferred retinal fixation loci and eleven matched controls with normal vision drove in a simulator for about an hour and a half per session, for two sessions a week apart. Participants responded to frequent virtual pedestrians that appeared on either the left or right sides, and approached the participants’ lane on a collision trajectory that, therefore, caused them to remain in approximately the same area of the visual field. Results CFL participants reacted more slowly to pedestrians that appeared in the area of visual field loss than in non-scotomatous areas (4.3 vs. 2.4 seconds, phazard detection even though small eye movements could potentially compensate for the loss. Responses in non-scotomatous areas were also delayed, though to a lesser extent, possibly due to the eccentricity of fixation. Our findings will help practitioners in advising patients with CFL about specific difficulties they may face when driving. PMID:23329309

  13. Kinematic analysis of step ascent among patients with central visual field loss.

    Science.gov (United States)

    Timmis, Matthew A; Scarfe, Amy C; Tabrett, Daryl R; Pardhan, Shahina

    2014-01-01

    Vision is of paramount importance in regulating adaptive gait. Using three-dimensional motion analysis, the current study investigated how central visual field loss (CFL) affects step ascent. Ten patients with chronic CFL (77 ± 10 years) and 13 visual normal participants (72 ± 6 years) walked up to and ascended a single step (of varying height). Movement kinematics assessed the period immediately prior to and during step ascent. Compared to visual normal participants, patients with CFL exhibited a lower lead foot horizontal crossing velocity, increased lead limb swing time and increased head flexion (looking down at more immediate areas of the ground/step). They also took longer to initiate the step up, transfer weight to the lead foot upon landing on the upper level and increased trail limb swing time when negotiating the medium and high step height. Increased variability was also shown in a number of dependent measures. Data indicate that during step ascent, patients with CFL exhibit a cautious stepping strategy when compared to visual normal participants. This cautious strategy becomes increasingly evident when negotiating higher step heights, as shown by an increased planning time prior to entering the relatively unstable period of single support during the step up. The increased variability among CFL patients increases their likelihood of experiencing dynamic instability and falling during step ascent. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Synaptic proteins and choline acetyltransferase loss in visual cortex in dementia with Lewy bodies.

    Science.gov (United States)

    Mukaetova-Ladinska, Elizabeta B; Andras, Alina; Milne, Joan; Abdel-All, Zeinab; Borr, Iwo; Jaros, Evelyn; Perry, Robert H; Honer, William G; Cleghorn, Andrea; Doherty, Jeanette; McIntosh, Gary; Perry, Elaine K; Kalaria, Raj N; McKeith, Ian G

    2013-01-01

    Functional neuroimaging studies have consistently reported abnormalities in the visual cortex in patients with dementia with Lewy bodies (DLB), but their neuropathologic substrates are poorly understood. We analyzed synaptic proteins and choline acetyltransferase (ChAT) in the primary (BA17) and association (BAs18/19) visual cortex in DLB and similar aged control and Alzheimer disease (AD) subjects. We found lower levels of synaptophysin, syntaxin, SNAP-25, and γ-synuclein in DLB subjects versus both aged control (68%-78% and 27%-72% for BA17 and BAs18/19, respectively) and AD cases (54%-67% and 10%-56% for BA17 and BAs18/19, respectively). The loss in ChAT activity in DLB cases was also greater in BA17 (72% and 87% vs AD and control values, respectively) than in BAs18/19 (52% and 65% vs AD and control groups, respectively). The observed synaptic and ChAT changes in the visual cortices were not associated with tau or β-amyloid pathology in the occipital or the frontal, temporal, and parietal neocortex. However, the neocortical densities of LBs, particular those in BA17 and BAs18/19, correlated with lower synaptic and ChAT levels in these brain areas. These findings draw attention to molecular changes within the primary visual cortex in DLB and correlate with the neuroimaging findings within the occipital lobe in patients with this disorder.

  15. Human skeleton proportions from monocular data

    Institute of Scientific and Technical Information of China (English)

    PENG En; LI Ling

    2006-01-01

    This paper introduces a novel method for estimating the skeleton proportions ofa human figure from monocular data.The proposed system will first automatically extract the key frames and recover the perspective camera model from the 2D data.The human skeleton proportions are then estimated from the key frames using the recovered camera model without posture reconstruction. The proposed method is tested to be simple, fast and produce satisfactory results for the input data. The human model with estimated proportions can be used in future research involving human body modeling or human motion reconstruction.

  16. 单目视觉同步定位与地图创建方法综述%A survey of monocular simultaneous localization and mapping

    Institute of Scientific and Technical Information of China (English)

    顾照鹏; 刘宏

    2015-01-01

    随着计算机视觉技术的发展,基于单目视觉的同步定位与地图创建( monocular SLAM)逐渐成为计算机视觉领域的热点问题之一。介绍了单目视觉SLAM方法的分类,从视觉特征检测与匹配、数据关联的优化、特征点深度的获取、地图的尺度控制几个方面阐述了单目视觉SLAM研究的发展现状。最后,介绍了常见的单目视觉与其他传感器结合的SLAM方法,并探讨了单目视觉SLAM未来的研究方向。%With the development of computer vision technology, monocular simultaneous localization and mapping ( monocular SLAM) has gradually become one of the hot issues in the field of computer vision.This paper intro-duces the monocular vision SLAM classification that relates to the present status of research in monocular SLAM methods from several aspects, including visual feature detection and matching, optimization of data association, depth acquisition of feature points, and map scale control.Monocular SLAM methods combining with other sensors are reviewed and significant issues needing further study are discussed.

  17. Orbital Compartment Syndrome Leading to Visual Loss following Orbital Floor Reconstruction.

    Science.gov (United States)

    Susarla, Srinivas M; Nam, Arthur J; Dorafshar, Amir H

    2016-06-01

    Reconstruction of posttraumatic orbital defects carries the attendant risk of injury to the ocular adnexa, globe, and associated neurovascular structures. Blindness following repair of orbital fractures is an infrequent but well-documented phenomenon. Visual acuity loss can be related to direct intraoperative injury to the optic nerve, retinal arterial occlusion, or delayed presentation of acute optic nerve injury. In this report, we document a unique case of acute optic nerve infarction occurring 14 hours following orbital floor exploration and repair in a 56-year-old man.

  18. 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...... the relationship between duration of DMO and progressive vision loss, and the key role of central foveal involvement in patients with diabetic retinopathy. These data will help to develop future strategies to prevent vision loss.......-long Protein Kinase C Diabetic Retinopathy Study (PKC-DRS2) trial were used to investigate the relationship between VA and DMO. Eligible eyes had moderately severe to very severe non-proliferative diabetic retinopathy and VA of at least 45 letters on Early Treatment Diabetic Retinopathy Study (ETDRS) charts...

  19. The locus of color sensation: Cortical color loss and the chromatic visual evoked potential

    Science.gov (United States)

    Crognale, Michael A.; Duncan, Chad S.; Shoenhard, Hannah; Peterson, Dwight J.; Berryhill, Marian E.

    2013-01-01

    Color losses of central origin (cerebral achromatopsia and dyschromatopsia) can result from cortical damage and are most commonly associated with stroke. Such cases have the potential to provide useful information regarding the loci of the generation of the percept of color. One available tool to examine this issue is the chromatic visual evoked potential (cVEP). The cVEP has been used successfully to objectively quantify losses in color vision capacity in both congenital and acquired deficiencies of retinal origin but has not yet been applied to cases of color losses of cortical origin. In addition, it is not known with certainty which cortical sites are responsible for the generation of the cVEP waveform components. Here we report psychophysical and electrophysiological examination of a patient with color deficits resulting from a bilateral cerebral infarct in the ventral occipitotemporal region. Although this patient demonstrated pronounced color losses of a general nature, the waveform of the cVEP remains unaffected. Contrast response functions of the cVEP are also normal for this patient. The results suggest that the percept of color arises after the origin of the cVEP and that normal activity in those areas that give rise to the characteristic negative wave of the cVEP are not sufficient to provide for the normal sensation of color. PMID:23986535

  20. Monocular blur alters the tuning characteristics of stereopsis for spatial frequency and size.

    Science.gov (United States)

    Li, Roger W; So, Kayee; Wu, Thomas H; Craven, Ashley P; Tran, Truyet T; Gustafson, Kevin M; Levi, Dennis M

    2016-09-01

    Our sense of depth perception is mediated by spatial filters at different scales in the visual brain; low spatial frequency channels provide the basis for coarse stereopsis, whereas high spatial frequency channels provide for fine stereopsis. It is well established that monocular blurring of vision results in decreased stereoacuity. However, previous studies have used tests that are broadband in their spatial frequency content. It is not yet entirely clear how the processing of stereopsis in different spatial frequency channels is altered in response to binocular input imbalance. Here, we applied a new stereoacuity test based on narrow-band Gabor stimuli. By manipulating the carrier spatial frequency, we were able to reveal the spatial frequency tuning of stereopsis, spanning from coarse to fine, under blurred conditions. Our findings show that increasing monocular blur elevates stereoacuity thresholds 'selectively' at high spatial frequencies, gradually shifting the optimum frequency to lower spatial frequencies. Surprisingly, stereopsis for low frequency targets was only mildly affected even with an acuity difference of eight lines on a standard letter chart. Furthermore, we examined the effect of monocular blur on the size tuning function of stereopsis. The clinical implications of these findings are discussed.

  1. TRANSIENT VISUAL LOSS FOLLOWING FORAMEN MAGNUM DECOMPRESSION - SURGERY IN PRONE POSITION: A CASE REPORT

    Directory of Open Access Journals (Sweden)

    Nayak

    2016-06-01

    Full Text Available Perioperative visual loss is an uncommon complication of surgery in the prone position, spinal surgery, and is also reported after cardiac surgery. It is important that the nursing faculty, attending on patients recovering from general anaesthesia for these procedures, check the vision immediately upon recovery. Prompt referral is essential if the patient has a deficit that was not noticed earlier. Visual deficit can be due to ischaemic optic neuropathy (Anterior or posterior, retinal artery occlusion (Branch or central, retinal vein occlusion (Branch or central, commotio retinae, pituitary apoplexy and occipital lobe infarction. Each condition has its clinical picture with fundus findings but in posterior ischaemic optic neuropathy (PION, pituitary apoplexy and occipital lobe infarction, the fundus is normal. Fundus finding will be disc pallor (Primary Optic Atrophy, in PION, pituitary apoplexy and occipital lobe infarction and take few weeks or months to appear. The case described outlines how early detection and referral can reduce visual morbidity, salvage vision, improving the quality of life of the patient.

  2. 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

  3. Eyegaze Detection from Monocular Camera Image for Eyegaze Communication System

    Science.gov (United States)

    Ohtera, Ryo; Horiuchi, Takahiko; Kotera, Hiroaki

    An eyegaze interface is one of the key technologies as an input device in the ubiquitous-computing society. In particular, an eyegaze communication system is very important and useful for severely handicapped users such as quadriplegic patients. Most of the conventional eyegaze tracking algorithms require specific light sources, equipment and devices. In this study, a simple eyegaze detection algorithm is proposed using a single monocular video camera. The proposed algorithm works under the condition of fixed head pose, but slight movement of the face is accepted. In our system, we assume that all users have the same eyeball size based on physiological eyeball models. However, we succeed to calibrate the physiologic movement of the eyeball center depending on the gazing direction by approximating it as a change in the eyeball radius. In the gaze detection stage, the iris is extracted from a captured face frame by using the Hough transform. Then, the eyegaze angle is derived by calculating the Euclidean distance of the iris centers between the extracted frame and a reference frame captured in the calibration process. We apply our system to an eyegaze communication interface, and verified the performance through key typing experiments with a visual keyboard on display.

  4. 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.

  5. Evidence against an X-linked visual loss susceptibility locus in Leber hereditary optic neuropathy

    Energy Technology Data Exchange (ETDEWEB)

    Chalmers, R.M.; Davis, M.B.; Sweeney, M.G.; Wood, N.W.; Harding, A.E. [Inst. of Neurology, London (United Kingdom)

    1996-07-01

    Pedigree analysis of British families with Leber hereditary optic neuropathy (LHON) closely fits a model in which a pathogenic mtDNA mutation interacts with an X-linked visual loss susceptibility locus (VLSL). This model predicts that 60% of affected females will show marked skewing of X inactivation. Linkage analysis in British and Italian families with genetically proven LHON has excluded the presence of such a VLSL over 169 cM of the X chromosome both when all families were analyzed together and when only families with the bp 11778 mutation were studied. Further, there was no excess skewing of X inactivation in affected females. There was no evidence for close linkage to three markers in the pseudoautosomal region of the sex chromosomes. The mechanism of incomplete penetrance and male predominance in LHON remains unclear. 27 refs., 1 fig., 3 tabs.

  6. 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.

  7. The incidence of vitreous loss and visual outcome in patients undergoing cataract surgery in a teaching hospital.

    Directory of Open Access Journals (Sweden)

    Kothari Mihir

    2003-01-01

    Full Text Available Purpose: To determine the incidence of vitreous loss in patients undergoing cataract surgery and the visual outcome in a tertiary teaching hospital. Methods: Hospital records of 2095 consecutive patients undergoing cataract surgery between July 1999 and June 2000 were reviewed in this non-concurrent cohort study. Incidence and visual outcome of vitreous loss managed using standard vitrectomy techniques were assessed for different cataract surgical techniques (extracapsular, Blumenthal technique and phacoemulsification as well as at different levels of surgical training. The outcome was compared with matched cases without vitreous loss (controls. Results: Vitreous loss occurred in 160 of 2095 eyes (7.63%; CI -7 to 9.3: 8.3% for ECCE, 8.1% for the Blumenthal technique and 5% with phacoemulsification. Vision ž 6/18 was achieved in 85% of cases and 95% of controls. For experienced surgeons, 95% of the cases and controls had vision ž 6/18. 5.8 % of cases and 0.7% of controls had vision < 6/60. One patient in each group was blind following cataract surgery; both had operable cataracts in the fellow eye. Conclusions: The vitreous loss rate in this tertiary teaching hospital is relatively high. This complication, managed with standard surgical techniques, is compatible with good visual outcome. In eyes with vitreous loss, the final visual acuity achieved by experienced surgeons was similar to that in uncomplicated cases.

  8. 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.

  9. A randomized controlled trial comparing 2 interventions for visual field loss with standard occupational therapy during inpatient stroke rehabilitation.

    Science.gov (United States)

    Mödden, Claudia; Behrens, Marion; Damke, Iris; Eilers, Norbert; Kastrup, Andreas; Hildebrandt, Helmut

    2012-06-01

    Compensatory and restorative treatments have been developed to improve visual field defects after stroke. However, no controlled trials have compared these interventions with standard occupational therapy (OT). A total of 45 stroke participants with visual field defect admitted for inpatient rehabilitation were randomized to restorative computerized training (RT) using computer-based stimulation of border areas of their visual field defects or to a computer-based compensatory therapy (CT) teaching a visual search strategy. OT, in which different compensation strategies were used to train for activities of daily living, served as standard treatment for the active control group. Each treatment group received 15 single sessions of 30 minutes distributed over 3 weeks. The primary outcome measures were visual field expansion for RT, visual search performance for CT, and reading performance for both treatments. Visual conjunction search, alertness, and the Barthel Index were secondary outcomes. Compared with OT, CT resulted in a better visual search performance, and RT did not result in a larger expansion of the visual field. Intragroup pre-post comparisons demonstrated that CT improved all defined outcome parameters and RT several, whereas OT only improved one. CT improved functional deficits after visual field loss compared with standard OT and may be the intervention of choice during inpatient rehabilitation. A larger trial that includes lesion location in the analysis is recommended.

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

    OpenAIRE

    Gillespie-Gallery, H.; Konstantakopoulou, E.; HARLOW, J.A.; Barbur, J. L.

    2013-01-01

    Purpose: 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. Methods: 95 participants aged 20 to 85 were recruited. Contrast thresholds for correct orientation discrimination of the gap in a Landolt C opt...

  11. 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.

  12. Amodal completion with background determines depth from monocular gap stereopsis.

    Science.gov (United States)

    Grove, Philip M; Ben Sachtler, W L; Gillam, Barbara J

    2006-10-01

    Grove, Gillam, and Ono [Grove, P. M., Gillam, B. J., & Ono, H. (2002). Content and context of monocular regions determine perceived depth in random dot, unpaired background and phantom stereograms. Vision Research, 42, 1859-1870] reported that perceived depth in monocular gap stereograms [Gillam, B. J., Blackburn, S., & Nakayama, K. (1999). Stereopsis based on monocular gaps: Metrical encoding of depth and slant without matching contours. Vision Research, 39, 493-502] was attenuated when the color/texture in the monocular gap did not match the background. It appears that continuation of the gap with the background constitutes an important component of the stimulus conditions that allow a monocular gap in an otherwise binocular surface to be responded to as a depth step. In this report we tested this view using the conventional monocular gap stimulus of two identical grey rectangles separated by a gap in one eye but abutting to form a solid grey rectangle in the other. We compared depth seen at the gap for this stimulus with stimuli that were identical except for two additional small black squares placed at the ends of the gap. If the squares were placed stereoscopically behind the rectangle/gap configuration (appearing on the background) they interfered with the perceived depth at the gap. However when they were placed in front of the configuration this attenuation disappeared. The gap and the background were able under these conditions to complete amodally.

  13. Visual field loss in schizophrenia: evaluation of magnocellular pathway dysfunction in schizophrenic patients and their parents

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    Gracitelli CPB

    2013-05-01

    Full Text Available Carolina Pelegrini Barbosa Gracitelli,1 Fabiana Benites Vaz de Lima,2,3 Rodrigo A Bressan,2,3 Augusto Paranhos Junior1 1Department of Ophthalmology, Federal University of São Paulo (UNIFESP, São Paulo, SP, Brazil; 2LiNC – Interdisciplinary Laboratory of Neuroimaging and Cognition, Department of Psychiatry, Federal University of São Paulo (UNIFESP, São Paulo, SP, Brazil; 3PROESQ – Schizophrenia Program, Federal University of São Paulo (UNIFESP, São Paulo, SP, Brazil Purpose: We sought to evaluate the visual pathway deficits in schizophrenic patients, compared with their parents and healthy controls, using Matrix frequency doubling technology (FDT perimetry. Matrix FDT is an ophthalmic test used to detect visual field loss. Method: A total of 13 patients, 13 parents, and 12 healthy controls were enrolled in the study. Participants were subjected to Matrix FDT perimetry in a single test session. We analyzed the mean deviation for each eye and used a generalized estimated equation to evaluate differences among the groups and correct the dependency between the eyes. Results: The global mean deviation (presented as the mean of both eyes was significantly lower in the schizophrenic patients than in their parents or controls. Analysis of the general sensitivity of the fibers crossing the optic chiasm showed a difference between the groups (P = 0.006, indicating that the sensitivity of the fibers crossing the optic chiasm was lower than those which did not cross. But when we analyzed the specific groups, the difference between the fibers was not considerable. Comparison of the right and left hemispheres showed that general sensitivity was lower for the left hemisphere, but when we analyzed specific groups, the difference was not significant (P = 0.29. Conclusion: These findings are suggestive of a lower global sensitivity in schizophrenic patients and their parents compared with controls. This difference may be an endophenotype of schizophrenia

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

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    Concetta F Alberti

    Full Text Available PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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

  15. Visualization

    OpenAIRE

    Balon, Andreja

    1990-01-01

    The present thesis entails the field of visualization which is divided into visualization along traditional lines and visualization in computer science. As the psychological aspect of image is of vital importance for visualization, it is shortly described in the beginning. Visualization in computer science is divided into three main fields: scientific visualization, program visualization and visual programming. An explanation and examples of approach to applications are given for each field....

  16. Visual loss in HIV-associated cryptococcal meningitis: A case series and review of the mechanisms involved

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    Anand Moodley

    2015-04-01

    Full Text Available Permanent visual loss is a devastating yet preventable complication of cryptococcal meningitis. Early and aggressive management of cerebrospinal fluid pressure in conjunction with antifungal therapy is required. Historically, the mechanisms of visual loss in cryptococcal meningitis have included optic neuritis and papilloedema. Hence, the basis of visual loss therapy has been steroid therapy and intracranial pressure lowering without clear guidelines. With the use of high-resolution magnetic resonance imaging of the optic nerve, an additional mechanism has emerged, namely an optic nerve sheath compartment syndrome (ONSCS caused by severely elevated intracranial pressure and fungal loading in the peri-optic space. An improved understanding of these mechanisms and recognition of the important role played by raised intracranial pressure allows for more targeted treatment measures and better outcomes. In the present case series of 90 HIV co-infected patients with cryptococcal meningitis, we present the clinical and electrophysiological manifestations of Cryptococcus-induced visual loss and review the mechanisms involved.

  17. 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 s

  18. Incidence of Glaucomatous Visual Field Loss : A Ten-Year Follow-up from the Rotterdam Study

    NARCIS (Netherlands)

    Czudowska, Monika A.; Ramdas, Wishal D.; Wolfs, Roger C. W.; Hofman, Albert; De Jong, Paulus T. V. M.; Vingerling, Johannes R.; Jansonius, Nomdo M.

    2010-01-01

    Purpose: To determine the 10-year incidence of glaucomatous visual field loss (GVFL) and to investigate the influence of risk factors for open-angle glaucoma on this incidence. Design: Population-based cohort study. Participants: Participants aged >55 years from the Rotterdam Study. Methods: Of the

  19. Incidence of Glaucomatous Visual Field Loss: A Ten-Year Follow-up from the Rotterdam Study

    NARCIS (Netherlands)

    M.A. Czudowska; W.D. Ramdas; R.C.W. Wolfs; A. Hofman; P.T.V.M. de Jong; J.R. Vingerling; N.M. Jansonius

    2010-01-01

    Purpose: To determine the 10-year incidence of glaucomatous visual field loss (GVFL) and to investigate the influence of risk factors for open-angle glaucoma on this incidence. Design: Population-based cohort study. Participants: Participants aged >55 years from the Rotterdam Study. Methods: Of the

  20. Hyperacute Corticosteroid Treatment of Optic Neuritis at the Onset of Pain May Prevent Visual Loss: A Case Series

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    G. T. Plant

    2011-01-01

    Full Text Available Aim. To show that high-dose corticosteroids may prevent visual loss in patients with optic neuritis (ON treated at the prodromal, hyperacute, phase of retrobulbar pain. Method. Prospective case series: patients were recruited with a history of ON associated with pain. The patients were advised to report immediately to the investigators should the pain recur in either eye. Where possible, orbital magnetic resonance imaging (MRI was performed to confirm a recurrence of ON and treatment with high-dose corticosteroids was commenced. Visual function and the patient’s subjective account were monitored. Results. Eight patients (including cases of MS, CRION and NMO presented in the hyperacute phase. MRI confirmed optic nerve inflammation in 5/5. Treatment was commenced immediately, and, in all cases, no visual loss ensued. Conclusion. MRI can be used to confirm acute optic neuritis prior to visual loss in the hyperacute phase. We suggest that treatment with high-dose corticosteroids may abort the attack and prevent loss of vision in patients with ON who are treated at the onset of pain. This has potential implications for the management of acute ON and also for our understanding of the pathogenesis and potential therapeutic targets in the neuroinflammatory conditions associated with ON.

  1. 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

  2. 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

    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…

  3. Bilateral optic nerve head hemangioma in Von Hippel Lindau disease: Report of a case with severe visual loss

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    Abdollahi A

    2001-06-01

    Full Text Available A 22 year-old woman presented with gradual visual loss in her right eye since 1990. Medical and family histories were unremarkable. Her visual acuity was 20/80 and 20/20 in right and left eyes respectively. Slit lamp examination was quite normal with no relative afferent papillary defect.Fundi of both eyes revealed subretinal lesion with optic nerve head involvement and subretinal fluid in papillomacular bundle with macular pucker in right eye. Whole body MRI revealed a large hemangioma in the spinal canal. In 1998 the patient ahsd significant visual loss at both eyes. This is the first report of Von hippel disease with bilateral optic nerve hemangioma in Iran.

  4. Higher resolution stimulus facilitates depth perception: MT+ plays a significant role in monocular depth perception.

    Science.gov (United States)

    Tsushima, Yoshiaki; Komine, Kazuteru; Sawahata, Yasuhito; Hiruma, Nobuyuki

    2014-10-20

    Today, we human beings are facing with high-quality virtual world of a completely new nature. For example, we have a digital display consisting of a high enough resolution that we cannot distinguish from the real world. However, little is known how such high-quality representation contributes to the sense of realness, especially to depth perception. What is the neural mechanism of processing such fine but virtual representation? Here, we psychophysically and physiologically examined the relationship between stimulus resolution and depth perception, with using luminance-contrast (shading) as a monocular depth cue. As a result, we found that a higher resolution stimulus facilitates depth perception even when the stimulus resolution difference is undetectable. This finding is against the traditional cognitive hierarchy of visual information processing that visual input is processed continuously in a bottom-up cascade of cortical regions that analyze increasingly complex information such as depth information. In addition, functional magnetic resonance imaging (fMRI) results reveal that the human middle temporal (MT+) plays a significant role in monocular depth perception. These results might provide us with not only the new insight of our neural mechanism of depth perception but also the future progress of our neural system accompanied by state-of- the-art technologies.

  5. Cortical dynamics of three-dimensional form, color, and brightness perception. 1. Monocular theory

    Energy Technology Data Exchange (ETDEWEB)

    Grossberg, S.

    1987-01-01

    A real-time visual-processing theory is developed to explain how three-dimensional form, color, and brightness percepts are coherently synthesized. The theory describes how several fundamental uncertainty principles that limit the computation of visual information at individual processing stages are resolved through parallel and hierarchical interactions among several processing stages. The theory provides unified analysis and many predictions of data about stereopsis, binocular rivalry, hyperacuity, McCollough effect, textural grouping, border distinctness, surface perception, monocular and binocular brightness percepts, filling-in, metacontrast, transparency, figural aftereffects, lateral inhibition within spatial frequency channels, proximity luminance covariance, tissue contrast, motion segmentation, and illusory figures, as well as about reciprocal interactions among the hypercolumns, blobs, and stripes of cortical areas V1, V2, and V4. Monocular and binocular interactions between a Boundary Contour (BC) System and a Feature Contour (FC) System are developed. The BC System, defined by a hierarchy of oriented interactions, synthesizes an emergent and coherent binocular boundary segmentation from combinations of unoriented and oriented scenic elements.

  6. 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.

  7. Comparison of distance and near visual acuity in patients with vision loss due to cataract.

    Science.gov (United States)

    Mercado, Carmel L; Doroslovački, Pavle; Wang, Jiangxia; Siddiqui, Aazim A; Kolker, Andrew F; Kolker, Richard J

    2017-02-01

    The purpose of this study was to assess whether there is a disparity in distance and near best-corrected visual acuity (BCVA) in cataract eyes. 102 patients with cataract (N = 121 eyes) were seen in clinic between January and November 2013 at the Wilmer Eye Institute Comprehensive Eye Service. An age-related macular degeneration (ARMD) group (N = 27 eyes) was also identified for comparison. Distance and near BCVA were measured as part of the standard ophthalmic evaluation. Snellen measurements were converted to their LogMAR equivalents for statistical analysis. Near was better than distance BCVA with mean difference of 1.38 lines (P distance BCVA disparity is a statistically significant finding seen with cataracts. This may have further implications in patients with both cataract and ARMD as the presence of disparity may suggest a cataract etiology playing a greater role in vision loss. This comparison may be useful for surgical prognostication and as a quick triage tool in conjunction with, or in place of, a potential acuity meter and dilated near-pinhole test.

  8. Brimonidine suppresses loss of retinal neurons and visual function in a murine model of optic neuritis.

    Science.gov (United States)

    Guo, Xiaoli; Namekata, Kazuhiko; Kimura, Atsuko; Noro, Takahiko; Azuchi, Yuriko; Semba, Kentaro; Harada, Chikako; Yoshida, Hiroshi; Mitamura, Yoshinori; Harada, Takayuki

    2015-04-10

    Optic neuritis is inflammation of the optic nerve and is strongly associated with multiple sclerosis (MS), an inflammatory demyelinating syndrome of the central nervous system. It leads to retinal ganglion cell (RGC) death and can cause severe vision loss. Brimonidine (BMD) is a selective α2-adrenergic receptor agonist that is used clinically for the treatment of glaucoma. BMD lowers intraocular pressure, but recent evidence suggests that its therapeutic efficacy may also mediate through mechanisms independent of modulation of intraocular pressure. In this study, we examined the effects of topical administration of BMD on retinal degeneration during optic neuritis in experimental autoimmune encephalomyelitis (EAE), an animal model of MS. EAE was induced with MOG35-55 in C57BL/6J mice and BMD eyedrops were applied daily. In the EAE retina, the number of RGCs was significantly decreased and this effect was suppressed with BMD treatment. Consistent with histological analyses, the visual impairment observed in EAE mice was inhibited with BMD treatment, indicating the functional significance of the neuroprotective effect of BMD. Furthermore, BMD increased the expression level of basic fibroblast growth factor in the EAE retina, particularly in Müller glial cells and RGCs. Our findings suggest that topical administration of BMD may be available for RGC protection during optic neuritis, as well as for glaucoma.

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

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    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.

  10. 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

  11. Regional Cortical Grey Matter Loss in Parkinson's Disease Without Dementia is Independent from Visual Hallucinations

    NARCIS (Netherlands)

    Meppelink, Anne Marthe; de Jong, Bauke M.; Teune, Laura K.; van Laar, Teus

    2011-01-01

    In our previous functional magnetic resonance imaging study, Parkinson's disease (PD) patients with visual hallucinations (VH) showed reduced activations in ventral/ lateral visual association cortices preceding image recognition, compared with both PD patients without VH and healthy controls. The p

  12. 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).

  13. The effect of contrast on monocular versus binocular reading performance.

    Science.gov (United States)

    Johansson, Jan; Pansell, Tony; Ygge, Jan; Seimyr, Gustaf Öqvist

    2014-05-14

    The binocular advantage in reading performance is typically small. On the other hand research shows binocular reading to be remarkably robust to degraded stimulus properties. We hypothesized that this robustness may stem from an increasing binocular contribution. The main objective was to compare monocular and binocular performance at different stimulus contrasts and assess the level of binocular superiority. A secondary objective was to assess any asymmetry in performance related to ocular dominance. In a balanced repeated measures experiment 18 subjects read texts at three levels of contrast monocularly and binocularly while their eye movements were recorded. The binocular advantage increased with reduced contrast producing a 7% slower monocular reading at 40% contrast, 9% slower at 20% contrast, and 21% slower at 10% contrast. A statistically significant interaction effect was found in fixation duration displaying a more adverse effect in the monocular condition at lowest contrast. No significant effects of ocular dominance were observed. The outcome suggests that binocularity contributes increasingly to reading performance as stimulus contrast decreases. The strongest difference between monocular and binocular performance was due to fixation duration. The findings may pose a clinical point that it may be necessary to consider tests at different contrast levels when estimating reading performance. © 2014 ARVO.

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

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    Carolin eGall

    2013-09-01

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

  15. Monocular Road Detection Using Structured Random Forest

    Directory of Open Access Journals (Sweden)

    Liang Xiao

    2016-05-01

    Full Text Available Road detection is a key task for autonomous land vehicles. Monocular vision-based road detection algorithms are mostly based on machine learning approaches and are usually cast as classification problems. However, the pixel-wise classifiers are faced with the ambiguity caused by changes in road appearance, illumination and weather. An effective way to reduce the ambiguity is to model the contextual information with structured learning and prediction. Currently, the widely used structured prediction model in road detection is the Markov random field or conditional random field. However, the random field-based methods require additional complex optimization after pixel-wise classification, making them unsuitable for real-time applications. In this paper, we present a structured random forest-based road-detection algorithm which is capable of modelling the contextual information efficiently. By mapping the structured label space to a discrete label space, the test function of each split node can be trained in a similar way to that of the classical random forests. Structured random forests make use of the contextual information of image patches as well as the structural information of the labels to get more consistent results. Besides this benefit, by predicting a batch of pixels in a single classification, the structured random forest-based road detection can be much more efficient than the conventional pixel-wise random forest. Experimental results tested on the KITTI-ROAD dataset and data collected in typical unstructured environments show that structured random forest-based road detection outperforms the classical pixel-wise random forest both in accuracy and efficiency.

  16. 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.

  17. Ernst Mach and the episode of the monocular depth sensations.

    Science.gov (United States)

    Banks, E C

    2001-01-01

    Although Ernst Mach is widely recognized in psychology for his discovery of the effects of lateral inhibition in the retina ("Mach Bands"), his contributions to the theory of depth perception are not as well known. Mach proposed that steady luminance gradients triggered sensations of depth. He also expanded on Ewald Hering's hypothesis of "monocular depth sensations," arguing that they were subject to the same principle of lateral inhibition as light sensations were. Even after Hermann von Helmholtz's attack on Hering in 1866, Mach continued to develop theories involving the monocular depth sensations, proposing an explanation of perspective drawings in which the mutually inhibiting depth sensations scaled to a mean depth. Mach also contemplated a theory of stereopsis in which monocular depth perception played the primary role. Copyright 2001 John Wiley & Sons, Inc.

  18. Screening intervals for diabetic retinopathy and incidence of visual loss: a systematic review.

    Science.gov (United States)

    Echouffo-Tcheugui, J B; Ali, M K; Roglic, G; Hayward, R A; Narayan, K M

    2013-11-01

    Screening for diabetic retinopathy can help to prevent this complication, but evidence regarding frequency of screening is uncertain. This paper systematically reviews the published literature on the relationship between screening intervals for diabetic retinopathy and the incidence of visual loss. The PubMed and EMBASE databases were searched until December 2012. Twenty five studies fulfilled the inclusion criteria, as these assessed the incidence/prevalence of sight-threatening diabetic retinopathy in relation to screening frequency. The included studies comprised 15 evaluations of real-world screening programmes, three studies modelling the natural history of diabetic retinopathy and seven cost-effectiveness studies. In evaluations of diabetic retinopathy screening programmes, the appropriate screening interval ranged from one to four years, in people with no retinopathy at baseline. Despite study heterogeneity, the overall tendency observed in these programmes was that 2-year screening intervals among people with no diabetic retinopathy at diagnosis were not associated with high incidence of sight-threatening diabetic retinopathy. The modelling studies (non-economic and economic) assessed a range of screening intervals (1-5 years). The aggregated evidence from both the natural history and cost-effectiveness models favors a screening interval >1 year, but ≤2 years. Such an interval would be appropriate, safe and cost-effective for people with no diabetic retinopathy at diagnosis, while screening intervals ≤1 year would be preferable for people with pre-existing diabetic retinopathy. A 2-year screening interval for people with no sight threatening diabetic retinopathy at diagnosis may be safely adopted. For patients with pre-existing diabetic retinopathy, a shorter interval ≤1 year is warranted.

  19. Comparative evaluation of monocular augmented-reality display for surgical microscopes.

    Science.gov (United States)

    Rodriguez Palma, Santiago; Becker, Brian C; Lobes, Louis A; Riviere, Cameron N

    2012-01-01

    Medical augmented reality has undergone much development recently. However, there is a lack of studies quantitatively comparing the different display options available. This paper compares the effects of different graphical overlay systems in a simple micromanipulation task with "soft" visual servoing. We compared positioning accuracy in a real-time visually-guided task using Micron, an active handheld tremor-canceling microsurgical instrument, using three different displays: 2D screen, 3D screen, and microscope with monocular image injection. Tested with novices and an experienced vitreoretinal surgeon, display of virtual cues in the microscope via an augmented reality injection system significantly decreased 3D error (p < 0.05) compared to the 2D and 3D monitors when confounding factors such as magnification level were normalized.

  20. Active 46-year-old man with right-sided visual loss and no family history of stroke · Dx?

    Science.gov (United States)

    Ajayi, Tokunbo; Yang, Hyun-Sik; Bhatia, Ashmeet

    2017-08-01

    A 46-year-old man presented to the emergency department with sudden-onset right-sided visual loss. He had a history of asthma, but no family history of hypercoagulability, deep vein thrombosis, or stroke. The patient had an active lifestyle that included scuba diving, mountain biking, and hockey (coaching and playing). The physical examination revealed a right homonymous upper quadrantanopia. The neurologic examination was within normal limits, except for the visual deficit and unequal pupil size. A computerized tomography scan of the patient's head did not reveal any lesions.

  1. A Comparison of Monocular and Binocular Depth Perception in 5- and 7-Month-Old Infants.

    Science.gov (United States)

    Granrud, Carl E.; And Others

    1984-01-01

    Compares monocular depth perception with binocular depth perception in five- to seven-month-old infants. Reaching preferences (dependent measure) observed in the monocular condition indicated sensitivity to monocular depth information. Binocular viewing resulted in a far more consistent tendency to reach for the nearer object. (Author)

  2. 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…

  3. Quality of Visual Cue Affects Visual Reweighting in Quiet Standing

    Science.gov (United States)

    Moraes, Renato; de Freitas, Paulo Barbosa; Razuk, Milena; Barela, José Angelo

    2016-01-01

    Sensory reweighting is a characteristic of postural control functioning adopted to accommodate environmental changes. The use of mono or binocular cues induces visual reduction/increment of moving room influences on postural sway, suggesting a visual reweighting due to the quality of available sensory cues. Because in our previous study visual conditions were set before each trial, participants could adjust the weight of the different sensory systems in an anticipatory manner based upon the reduction in quality of the visual information. Nevertheless, in daily situations this adjustment is a dynamical process and occurs during ongoing movement. The purpose of this study was to examine the effect of visual transitions in the coupling between visual information and body sway in two different distances from the front wall of a moving room. Eleven young adults stood upright inside of a moving room in two distances (75 and 150 cm) wearing a liquid crystal lenses goggles, which allow individual lenses transition from opaque to transparent and vice-versa. Participants stood still during five minutes for each trial and the lenses status changed every one minute (no vision to binocular vision, no vision to monocular vision, binocular vision to monocular vision, and vice-versa). Results showed that farther distance and monocular vision reduced the effect of visual manipulation on postural sway. The effect of visual transition was condition dependent, with a stronger effect when transitions involved binocular vision than monocular vision. Based upon these results, we conclude that the increased distance from the front wall of the room reduced the effect of visual manipulation on postural sway and that sensory reweighting is stimulus quality dependent, with binocular vision producing a much stronger down/up-weighting than monocular vision. PMID:26939058

  4. The effect of a monocular helmet-mounted display on aircrew health: a 10-year prospective cohort study of Apache AH MK 1 pilots: study midpoint update

    Science.gov (United States)

    Hiatt, Keith L.; Rash, Clarence E.; Watters, Raymond W.; Adams, Mark S.

    2009-05-01

    A collaborative occupational health study has been undertaken by Headquarters Army Aviation, Middle Wallop, UK, and the U.S. Army Aeromedical Research Laboratory, Fort Rucker, Alabama, to determine if the use of the Integrated Helmet and Display Sighting System (IHADSS) monocular helmet-mounted display (HMD) in the Apache AH Mk 1 attack helicopter has any long-term (10-year) effect on visual performance. The test methodology consists primarily of a detailed questionnaire and an annual battery of vision tests selected to capture changes in visual performance of Apache aviators over their flight career (with an emphasis on binocular visual function). Pilots using binocular night vision goggles serve as controls and undergo the same methodology. Currently, at the midpoint of the study, with the exception of a possible colour discrimination effect, there are no data indicating that the long-term use of the IHADSS monocular HMD results in negative effects on vision.

  5. [Impact of follow-up loss over visual deficiency in open-globe ocular trauma].

    Science.gov (United States)

    Lima-Gómez, Virgilio; García-Rubio, Yatzul Zuhaila; Blanco-Hernández, Dulce Milagros Razo

    2013-01-01

    Open-globe ocular trauma causes visual deficiency; calculating the magnitude of the latter often misses the estimation in patients without follow-up. to identify the modification of the postoperative proportion of visual deficiency in open-globe ocular trauma, which would introduce considering the proportion estimated in patients without follow-up. Non-interventional, retrospective, longitudinal, analytical study. Visual outcome in eyes with open-globe trauma, with and without follow-up, was calculated using the Ocular Trauma Score. The observed postoperative proportion of visual deficiency was identified in eyes with follow-up; in eyes without follow-up, the postoperative proportion of visual deficiency was estimated using an analysis of scenarios: best (Ocular Trauma Score), mean (that of eyes with follow-up) and worst (last observation/no visual improvement). The estimated proportion of visual deficiency was added to that observed in eyes with follow-up, and the resulting proportion was compared with that expected in the sample, using the Ocular Trauma Score (χ(2)). 104 eyes, 70 without follow-up and 34 without it. In eyes with follow-up the expected proportion of visual deficiency was 58.6%, and the observed one was 71.4% (p = 0.1); the estimated proportion of visual deficiency in eyes without follow-up was 76.5%. The resulting postoperative proportion of visual deficiency in the sample would be 73.1%, which would overcome that expected by the Ocular Trauma Score (59.6%, p = 0.04). In open-globe ocular trauma, the efficacy of surgery to reduce the proportion of visual deficiency would decrease with regard to the standard expected by the Ocular Trauma Score, if the deficiency estimated in eyes without follow-up were considered.

  6. An orientation to vision loss program: meeting the needs of newly visually impaired older adults.

    Science.gov (United States)

    Kleinschmidt, J J

    1996-08-01

    An Orientation to Vision Loss program was developed to meet the needs of individuals, and their families, new to the difficult experience of vision loss. Program components address: education regarding services and resources, issues around the emotional response to vision loss and adjustment, tips and ideas for daily functioning, and enhancing families' awareness of how the vision loss "looks." Peer counselors co-facilitate the experience. Evaluations have been overwhelmingly positive, with participants expressing satisfaction and recognizing value in their participation.

  7. The Influence of Monocular Spatial Cues on Vergence Eye Movements in Monocular and Binocular Viewing of 3-D and 2-D Stimuli.

    Science.gov (United States)

    Batvinionak, Anton A; Gracheva, Maria A; Bolshakov, Andrey S; Rozhkova, Galina I

    2015-01-01

    The influence of monocular spatial cues on the vergence eye movements was studied in two series of experiments: (I) the subjects were viewing a 3-D video and also its 2-D version-binocularly and monocularly; and (II) in binocular and monocular viewing conditions, the subjects were presented with stationary 2-D stimuli containing or not containing some monocular indications of spatial arrangement. The results of the series (I) showed that, in binocular viewing conditions, the vergence eye movements were only present in the case of 3-D but not 2-D video, while in the course of monocular viewing of 2-D video, some regular vergence eye movements could be revealed, suggesting that the occluded eye position could be influenced by the spatial organization of the scene reconstructed on the basis of the monocular depth information provided by the viewing eye. The data obtained in series (II), in general, seem to support this hypothesis. © The Author(s) 2015.

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

    Directory of Open Access Journals (Sweden)

    Praveena Manogaran

    2016-01-01

    Conclusions: The relationship between reductions in OCT measures of neuro-axonal health in the anterior visual pathway and MRI-based measures of myelin health in the posterior visual pathway suggests that these measures may be linked through bidirectional axonal degeneration.

  9. 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.

  10. Monocular Vision: Occupational Limitations and Current Standards

    Science.gov (United States)

    2011-03-01

    Kumagai, J. K., Williams, S., and Kline, D. (2005), Vision standards for aircrew: Visual acuity for pilots, (DRDC-TORONTO-CR-2005-142), Greenley ...Canadian Forces aircrew, (DRDC-TORONTO-CR-2006-255), Greenley and Associate Inc., Ottawa. Lövsund, P., Hedin, A., and Törnros, J. (1991), Effects...Williams, S., Casson, E., Brooks, J., Greenley , M., and Nadeau, J. (2003), Visual acuity standard for divers, Greenley & Associates Incorporated

  11. Parallax error in the monocular head-mounted eye trackers

    DEFF Research Database (Denmark)

    Mardanbeigi, Diako; Witzner Hansen, Dan

    2012-01-01

    This paper investigates the parallax error, which is a common problem of many video-based monocular mobile gaze trackers. The parallax error is defined and described using the epipolar geometry in a stereo camera setup. The main parameters that change the error are introduced and it is shown how...

  12. Monocular SLAM for Autonomous Robots with Enhanced Features Initialization

    Directory of Open Access Journals (Sweden)

    Edmundo Guerra

    2014-04-01

    Full Text Available 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.

  13. 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.

  14. 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

  15. Patients with central visual field loss adopt a cautious gait strategy during tasks that present a high risk of falling.

    Science.gov (United States)

    Timmis, Matthew A; Pardhan, Shahina

    2012-06-26

    To investigate how patients with central visual field loss (CFL) complete adaptive gait tasks when compared to visual normals and determine whether task difficulty significantly affects movement control. Ten patients with CFL and 12 visual normals negotiated a floor-based obstacle (of different heights, 5 and 10 cm) and also walked across an unobstructed laboratory (no obstacle present). Analysis assessed the kinematics of human movement for each task. During obstacle crossing, compared to visual normals, patients with CFL lifted their lead and trail foot significantly higher to avoid the obstacle, reduced horizontal crossing velocity (only significant at low obstacle height), and increased head flexion to look down at more immediate areas of the ground (P walking only trials there was no significant difference between the two groups in any of the kinematic measures. CONCLUSIONS; Compared to visual normals, patients with CFL adopt a cautious gait strategy during tasks that present a high risk of falling, such as obstacle crossing. However, under conditions that present a low risk of tripping or falling, such as level walking, differences appear minimal.

  16. Pleasant Music Overcomes the Loss of Awareness in Patients with Visual Neglect

    National Research Council Canada - National Science Library

    David Soto; María J. Funes; Azucena Guzmán-García; Tracy Warbrick; Pia Rotshtein; Glyn W. Humphreys; Bill Thompson

    2009-01-01

    .... We report that the patients showed enhanced visual awareness when tasks were performed under preferred music conditions relative to when tasks were performed either with unpreferred music or in silence...

  17. Monocular and binocular edges enhance the perception of stereoscopic slant.

    Science.gov (United States)

    Wardle, Susan G; Palmisano, Stephen; Gillam, Barbara J

    2014-07-01

    Gradients of absolute binocular disparity across a slanted surface are often considered the basis for stereoscopic slant perception. However, perceived stereo slant around a vertical axis is usually slow and significantly under-estimated for isolated surfaces. Perceived slant is enhanced when surrounding surfaces provide a relative disparity gradient or depth step at the edges of the slanted surface, and also in the presence of monocular occlusion regions (sidebands). Here we investigate how different kinds of depth information at surface edges enhance stereo slant about a vertical axis. In Experiment 1, perceived slant decreased with increasing surface width, suggesting that the relative disparity between the left and right edges was used to judge slant. Adding monocular sidebands increased perceived slant for all surface widths. In Experiment 2, observers matched the slant of surfaces that were isolated or had a context of either monocular or binocular sidebands in the frontal plane. Both types of sidebands significantly increased perceived slant, but the effect was greater with binocular sidebands. These results were replicated in a second paradigm in which observers matched the depth of two probe dots positioned in front of slanted surfaces (Experiment 3). A large bias occurred for the surface without sidebands, yet this bias was reduced when monocular sidebands were present, and was nearly eliminated with binocular sidebands. Our results provide evidence for the importance of edges in stereo slant perception, and show that depth from monocular occlusion geometry and binocular disparity may interact to resolve complex 3D scenes. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Visual dysfunction among former microelectronics assembly workers.

    Science.gov (United States)

    Mergler, D; Huel, G; Bowler, R; Frenette, B; Cone, J

    1991-01-01

    Although known neurotoxins with potential ophthalmotoxic properties are commonly used in microelectronics assembly, there has been no systematic study of visual disturbances among past or present workers in this industry. The objective of the present study was to compare visual functions, using a matched-pair design, between former workers from a microelectronics plant and a local reference population. From an initial population of 180 former workers and 157 potential referents, 54 pairs were matched for age (+/- 3 y), education (+/- 2 y), sex, ethnic origin, and number of children. Near and far visual acuity, chromatic discrimination, and near contrast sensitivity were assessed monocularly. Paired comparisons (Signed-rank Wilcoxon test) revealed that the former microelectronics workers had significantly lower contrast sensitivity, particularly in the intermediate frequencies, independently of near visual acuity loss. There were no differences for far visual acuity in both eyes. Even though near visual acuity and color vision were compromised among the former workers, the differences were only significant for one eye, as was the prevalence of acquired dyschromatopsia (chi-square for matched pairs, p less than .001). These findings suggest a pattern of contrast sensitivity deficits consistent with impairment to foveal and/or neuro-optic pathways among these former microelectronics workers. Exposure to ophthalmotoxic chemicals is proposed as the most probable risk factor.

  19. 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

  20. Navigation system for a small size lunar exploration rover with a monocular omnidirectional camera

    Science.gov (United States)

    Laîné, Mickaël.; Cruciani, Silvia; Palazzolo, Emanuele; Britton, Nathan J.; Cavarelli, Xavier; Yoshida, Kazuya

    2016-07-01

    A lunar rover requires an accurate localisation system in order to operate in an uninhabited environment. However, every additional piece of equipment mounted on it drastically increases the overall cost of the mission. This paper reports a possible solution for a micro-rover using a sole monocular omnidirectional camera. Our approach relies on a combination of feature tracking and template matching for Visual Odometry. The results are afterwards refined using a Graph-Based SLAM algorithm, which also provides a sparse reconstruction of the terrain. We tested the algorithm on a lunar rover prototype in a lunar analogue environment and the experiments show that the estimated trajectory is accurate and the combination with the template matching algorithm allows an otherwise poor detection of spot turns.

  1. Visual Loss, Retinal Hemorrhages, and Optic Disc Edema Resulting From Thiamine Deficiency Following Bariatric Surgery Complicated by Prolonged Vomiting

    Science.gov (United States)

    Lawton, Andrew W.; Frisard, Nicholas E.

    2017-01-01

    Background: Vision loss resulting from thiamine deficiency is a recognized complication of bariatric surgery. Most patients with such vision loss have Wernicke encephalopathy with characteristic changes seen on neuroimaging. Other patients may have retinal hemorrhages, optic disc edema, and peripheral neuropathy without Wernicke encephalopathy. The risk for thiamine deficiency is potentiated by the presence of prolonged vomiting. Case Report: A 37-year-old female presented with abrupt onset of vision loss and peripheral neuropathy following bariatric surgery. She had a history of prolonged vomiting postoperatively. Examination of the posterior segment of the eye revealed optic disc edema and large retinal hemorrhages bilaterally. Metabolic workup demonstrated thiamine deficiency. She responded quickly to parenteral thiamine therapy with recovery of normal vision and resolution of ophthalmologic findings. Conclusion: Patients who undergo bariatric surgery and have a thiamine deficiency can present with visual symptoms and ophthalmologic findings only visible by fundoscopy prior to developing more severe and potentially irreversible complications from the vitamin deficiency. Early detection of intraocular changes resulting from thiamine deficiency and initiation of therapy could prevent more devastating neurologic manifestations. Our case supports the consideration of a prospective study aimed at determining the true incidence of ocular and visual changes such as retinal hemorrhage, optic disc edema, and peripapillary telangiectasia in patients following bariatric surgery.

  2. Quality of life in patients with age-related macular degeneration with monocular and binocular legal blindness Qualidade de vida de pacientes com degeneração macular relacionada à idade com cegueira legal monocular e binocular

    Directory of Open Access Journals (Sweden)

    Roberta Ferrari Marback

    2007-01-01

    Full Text Available OBJECTIVE: To evaluate the quality of life for persons affected by age-related macular degeneration that results in monocular or binocular legal blindness. METHODS: An analytic transversal study using the National Eye Institute Visual Functioning Questionnaire (NEI VFQ-25 was performed. Inclusion criteria were persons of both genders, aged more than 50 years old, absence of cataracts, diagnosis of age-related monocular degeneration in at least one eye and the absence of other macular diseases. The control group was paired by sex, age and no ocular disease. RESULTS: Group 1 (monocular legal blindness was composed of 54 patients (72.22% females and 27.78% males, aged 51 to 87 years old, medium age 74.61 ± 7.27 years; group 2 (binocular legal blindness was composed of 54 patients (46.30% females and 53.70% males aged 54 to 87 years old, medium age 75.61 ± 6.34 years. The control group was composed of 40 patients (40% females and 60% males, aged 50 to 81 years old, medium age 65.65 ± 7.56 years. The majority of the scores were statistically significantly higher in group 1 and the control group in relation to group 2 and higher in the control group when compared to group 1. CONCLUSIONS: It was evident that the quality of life of persons with binocular blindness was more limited in relation to persons with monocular blindness. Both groups showed significant impairment in quality of life when compared to normal persons.OBJETIVO: Avaliar a qualidade de vida de portadores de degeneração macular relacionada à idade com cegueira legal monocular e binocular. MÉTODOS: Foi realizado estudo transversal analítico por meio do questionário National Eye Institute Visual Functioning Questionnaire (NEI VFQ-25. Os critérios de inclusão foram: indivíduos de ambos os sexos, idade maior que 50 anos, ausência de catarata, diagnóstico de degeneração macular relacionada à idade avançada em pelo menos um dos olhos, sem outras maculopatias. O Grupo Controle

  3. Alveolar rhabdomyosarcoma of the sphenoid sinus mimicking optic neuritis presenting with intermittent visual loss in an adult

    Directory of Open Access Journals (Sweden)

    Liu W

    2016-10-01

    Full Text Available Wendong Liu,1 Libin Jiang,1 Yulan Jin,2 Bentao Yang,3 Timothy YY Lai4 1Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Sciences Key Laboratory, 2Department of Pathology, 3Department of Radiology, Beijing Tongren Hospital, Capital Medical University, Beijing, 4Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, People’s Republic of China Abstract: A 23-year-old male with intermittent visual loss in his left eye for 4 months was originally treated as optic neuritis elsewhere. Upon presentation to our hospital (Beijing Tongren Hospital, his left eye visual acuity was reduced to hand motion at face. The left eye ocular motility was limited in upgaze, downgaze, adduction, and abduction. Computed tomography and magnetic resonance imaging revealed lesions in the sphenoid and ethmoid sinuses, orbital apex and carvernous sinus invading adjacent extraocular muscles. Endoscopic ethmo-sphenoidostomy and debulking surgery was performed and histopathology of the specimen demonstrated alveolar rhabdomyosarcoma. Despite having treatment with a combination of orbital radiation therapy and systemic chemotherapy, the patient developed generalized metastasis with cachexia and the left eye became no light perception due to optic atrophy. Keywords: alveolar rhabdomyosarcoma, sphenoid sinus, optic neuritis, misdiagnosis

  4. Branch retinal vein thrombosis and visual loss probably associated with pegylated interferon therapy of chronic hepatitis C

    Institute of Scientific and Technical Information of China (English)

    Luciana Lofego Gon(c)alves; Alberto Queiroz Farias; Patrícia Lofego Gon(c)alves; Elbio Antonio D'Amico; Flair José Carrilho

    2006-01-01

    Ophthalmological complications with interferon therapy are usually mild and reversible, not requiring the withdrawal of the treatment. We report a case of a patient who had visual loss probably associated with interferon therapy. Chronic hepatitis C virus infection (genotype 1a) was diagnosed in a 33-year old asymptomatic man. His past medical history was unremarkable and previous routine ophthalmologic check-up was normal. Pegylated interferon alpha and ribavirin were started. Three weeks later he reported painless reduction of vision. Ophthalmologic examination showed extensive intraretinal hemorrhages and cottonwool spots, associated with inferior branch retinal vein thrombosis. Antiviral therapy was immediately discontinued, but one year later he persists with severely decreased visual acuity. This case illustrates the possibility of unlredictable and severe complications during pegylated interferon therapy.

  5. Mitochondrial dysfunction due to Leber's hereditary optic neuropathy as a cause of visual loss during assessment for epilepsy surgery.

    Science.gov (United States)

    Niehusmann, Pitt; Surges, Rainer; von Wrede, Randi D; Elger, Christian E; Wellmer, Jörg; Reimann, Jens; Urbach, Horst; Vielhaber, Stefan; Bien, Christian G; Kunz, Wolfram S

    2011-01-01

    Assessment for epilepsy surgery may require invasive measures such as implantation of intracranial electrodes or the Wada test. These investigations are commonly well tolerated. However, complications, including visual disturbances of various etiologies, have been reported. Here we describe two patients with pharmacoresistant temporal lobe epilepsy (TLE) who displayed loss of vision in the context of presurgical assessment and in whom mutations associated with Leber's hereditary optic neuropathy (LHON) were detected. Genetic analysis revealed in one patient the frequent mitochondrial G11778A LHON mutation in ND4. In the second patient, the mitochondrial C4640A mutation in ND2 was detected. This rare LHON mutation enhanced the sensitivity of the patient's muscle and brain tissue to amobarbital, a known blocker of the mitochondrial respiratory chain. Mitochondrial dysfunction has been reported in epilepsy. Thus, the presence of LHON mutations can be a rare cause of visual disturbances in patients with epilepsy and may have predisposed to development of epilepsy.

  6. Visual symptoms and G-induced loss of consciousness in 594 Chinese Air Force aircrew--a questionnaire survey.

    Science.gov (United States)

    Cao, Xin-Sheng; Wang, Yong-Chun; Xu, Li; Yang, Chang-Bing; Wang, Bing; Geng, Jie; Gao, Yuan; Wu, Yan-Hong; Wang, Xiao-Ying; Zhang, Shu; Sun, Xi-Qing

    2012-02-01

    A questionnaire survey was performed for the first time to assess the prevalence of visual symptoms and G-induced loss of consciousness (G-LOC) due to +Gz exposure in the Chinese Air Force (CAF) to determine the effectiveness of current G tolerance training. Responses were received from 594 individuals. Among them, 302 reported at least one episode of some sort of symptoms related to +Gz, including 110 (18.5%) with visual blurring, 231 (38.9%) with greyout, 111 (18.7%) with blackout, and 49 (8.2%) with G-LOC. Incidences were most common in aircrew with 250-1,000 flying hours (53.6%) and were more prevalent in those with fewer on type flying hours (p aircrew. There remains considerable scope for +Gz education, particularly in the early centrifuge training and selection of rational physical exercises.

  7. Alveolar rhabdomyosarcoma of the sphenoid sinus mimicking optic neuritis presenting with intermittent visual loss in an adult

    Science.gov (United States)

    Liu, Wendong; Jiang, Libin; Jin, Yulan; Yang, Bentao; Lai, Timothy YY

    2016-01-01

    A 23-year-old male with intermittent visual loss in his left eye for 4 months was originally treated as optic neuritis elsewhere. Upon presentation to our hospital (Beijing Tongren Hospital), his left eye visual acuity was reduced to hand motion at face. The left eye ocular motility was limited in upgaze, downgaze, adduction, and abduction. Computed tomography and magnetic resonance imaging revealed lesions in the sphenoid and ethmoid sinuses, orbital apex and carvernous sinus invading adjacent extraocular muscles. Endoscopic ethmo-sphenoidostomy and debulking surgery was performed and histopathology of the specimen demonstrated alveolar rhabdomyosarcoma. Despite having treatment with a combination of orbital radiation therapy and systemic chemotherapy, the patient developed generalized metastasis with cachexia and the left eye became no light perception due to optic atrophy. PMID:27932889

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

    NARCIS (Netherlands)

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

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

  9. The Effect of a Monocular Helmet-Mounted Display on Aircrew Health: A Cohort Study of Apache AH Mk 1 Pilots Four-Year Review

    Science.gov (United States)

    2009-12-01

    conventional Snellen charts (Bailey and Lovie, 1976). This test was conducted monocularly for both left and right eyes using the habitual correction...from logMAR to Snellen acuity (20/xx) is accomplished using the formula to determine the Snellen denominator: xx = 20 x 10 logMAR. For the...last measurement cycle, values were available for all 23 control subjects. For the right eye, the mean visual acuity was 0.08 logMAR ( Snellen

  10. Visual Field Loss in a Case of Recurrent Cystic Craniopharyngioma During Concomitant Treatment With Pegylated Interferon α-2b.

    Science.gov (United States)

    Tiedemann, Laura M; Manley, Peter; Smith, Edward R; Dagi, Linda R

    2016-01-01

    A 13-year-old male with suprasellar cystic craniopharyngioma initially controlled with sequential subtotal resections and proton-beam irradiation was later treated with intracystic pegylated interferon α-2b due to progression and a lack of further surgical options. After initial successful control of recurrent cyst enlargement and stabilization of the ophthalmic examination, progressive and irreversible visual field loss ensued. Imaging revealed intracranial leakage from the intracystic catheter, and direct administration of interferon α-2b was discontinued. Given the recent interest in interferon α-2b, oncologists are advised to vigilantly monitor patients for signs of local toxicity that may result from unintended leakage during intracystic delivery.

  11. Acuity-independent effects of visual deprivation on human visual cortex.

    Science.gov (United States)

    Hou, Chuan; Pettet, Mark W; Norcia, Anthony M

    2014-07-29

    Visual development depends on sensory input during an early developmental critical period. Deviation of the pointing direction of the two eyes (strabismus) or chronic optical blur (anisometropia) separately and together can disrupt the formation of normal binocular interactions and the development of spatial processing, leading to a loss of stereopsis and visual acuity known as amblyopia. To shed new light on how these two different forms of visual deprivation affect the development of visual cortex, we used event-related potentials (ERPs) to study the temporal evolution of visual responses in patients who had experienced either strabismus or anisometropia early in life. To make a specific statement about the locus of deprivation effects, we took advantage of a stimulation paradigm in which we could measure deprivation effects that arise either before or after a configuration-specific response to illusory contours (ICs). Extraction of ICs is known to first occur in extrastriate visual areas. Our ERP measurements indicate that deprivation via strabismus affects both the early part of the evoked response that occurs before ICs are formed as well as the later IC-selective response. Importantly, these effects are found in the normal-acuity nonamblyopic eyes of strabismic amblyopes and in both eyes of strabismic patients without amblyopia. The nonamblyopic eyes of anisometropic amblyopes, by contrast, are normal. Our results indicate that beyond the well-known effects of strabismus on the development of normal binocularity, it also affects the early stages of monocular feature processing in an acuity-independent fashion.

  12. Monocular and binocular steady-state flicker VEPs: frequency-response functions to sinusoidal and square-wave luminance modulation.

    Science.gov (United States)

    Nicol, David S; Hamilton, Ruth; Shahani, Uma; McCulloch, Daphne L

    2011-02-01

    Steady-state VEPs to full-field flicker (FFF) using sinusoidally modulated light were compared with those elicited by square-wave modulated light across a wide range of stimulus frequencies with monocular and binocular FFF stimulation. Binocular and monocular VEPs were elicited in 12 adult volunteers to FFF with two modes of temporal modulation: sinusoidal or square-wave (abrupt onset and offset, 50% duty cycle) at ten temporal frequencies ranging from 2.83 to 58.8 Hz. All stimuli had a mean luminance of 100 cd/m(2) with an 80% modulation depth (20-180 cd/m(2)). Response magnitudes at the stimulus frequency (F1) and at the double and triple harmonics (F2 and F3) were compared. For both sinusoidal and square-wave flicker, the FFF-VEP magnitudes at F1 were maximal for 7.52 Hz flicker. F2 was maximal for 5.29 Hz flicker, and F3 magnitudes are largest for flicker stimulation from 3.75 to 7.52 Hz. Square-wave flicker produced significantly larger F1 and F2 magnitudes for slow flicker rates (up to 5.29 Hz for F1; at 2.83 and 3.75 Hz for F2). The F3 magnitudes were larger overall for square-wave flicker. Binocular FFF-VEP magnitudes are larger than those of monocular FFF-VEPs, and the amount of this binocular enhancement is not dependant on the mode of flicker stimulation (mean binocular: monocular ratio 1.41, 95% CI: 1.2-1.6). Binocular enhancement of F1 for 21.3 Hz flicker was increased to a factor of 2.5 (95% CI: 1.8-3.5). In the healthy adult visual system, FFF-VEP magnitudes can be characterized by the frequency-response functions of F1, F2 and F3. Low-frequency roll-off in the FFF-VEP magnitudes is greater for sinusoidal flicker than for square-wave flicker for rates ≤ 5.29 Hz; magnitudes for higher-frequency flicker are similar for the two types of flicker. Binocular FFF-VEPs are larger overall than those recorded monocularly, and this binocular summation is enhanced at 21.3 Hz in the mid-frequency range.

  13. 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…

  14. fMRI investigation of monocular pattern rivalry.

    Science.gov (United States)

    Mendola, Janine D; Buckthought, Athena

    2013-01-01

    In monocular pattern rivalry, a composite image is shown to both eyes. The patient experiences perceptual alternations in which the two stimulus components alternate in clarity or salience. We used fMRI at 3T to image brain activity while participants perceived monocular rivalry passively or indicated their percepts with a task. The stimulus patterns were left/right oblique gratings, face/house composites, or a nonrivalrous control stimulus that did not support the perception of transparency or image segmentation. All stimuli were matched for luminance, contrast, and color. Compared with the control stimulus, the cortical activation for passive viewing of grating rivalry included dorsal and ventral extrastriate cortex, superior and inferior parietal regions, and multiple sites in frontal cortex. When the BOLD signal for the object rivalry task was compared with the grating rivalry task, a similar whole-brain network was engaged, but with significantly greater activity in extrastriate regions, including V3, V3A, fusiform face area (FFA), and parahippocampal place area (PPA). In addition, for the object rivalry task, FFA activity was significantly greater during face-dominant periods whereas parahippocampal place area activity was greater during house-dominant periods. Our results demonstrate that slight stimulus changes that trigger monocular rivalry recruit a large whole-brain network, as previously identified for other forms of bistability. Moreover, the results indicate that rivalry for complex object stimuli preferentially engages extrastriate cortex. We also establish that even with natural viewing conditions, endogenous attentional fluctuations in monocular pattern rivalry will differentially drive object-category-specific cortex, similar to binocular rivalry, but without complete suppression of the nondominant image.

  15. A smart telerobotic system driven by monocular vision

    Science.gov (United States)

    Defigueiredo, R. J. P.; Maccato, A.; Wlczek, P.; Denney, B.; Scheerer, J.

    1994-01-01

    A robotic system that accepts autonomously generated motion and control commands is described. The system provides images from the monocular vision of a camera mounted on a robot's end effector, eliminating the need for traditional guidance targets that must be predetermined and specifically identified. The telerobotic vision system presents different views of the targeted object relative to the camera, based on a single camera image and knowledge of the target's solid geometry.

  16. Building a 3D scanner system based on monocular vision.

    Science.gov (United States)

    Zhang, Zhiyi; Yuan, Lin

    2012-04-10

    This paper proposes a three-dimensional scanner system, which is built by using an ingenious geometric construction method based on monocular vision. The system is simple, low cost, and easy to use, and the measurement results are very precise. To build it, one web camera, one handheld linear laser, and one background calibration board are required. The experimental results show that the system is robust and effective, and the scanning precision can be satisfied for normal users.

  17. Indoor monocular mobile robot navigation based on color landmarks

    Institute of Scientific and Technical Information of China (English)

    LUO Yuan; ZHANG Bai-sheng; ZHANG Yi; LI Ling

    2009-01-01

    A robot landmark navigation system based on monocular camera was researched theoretically and experimentally. First the landmark setting and its data structure in programming was given; then the coordinates of them getting by robot and global localization of the robot was described; finally experiments based on Pioneer III mobile robot show that this system can work well at different topographic situation without lose of signposts.

  18. O impacto da visão monocular congênita versus adquirida na qualidade de visão autorrelatada

    Directory of Open Access Journals (Sweden)

    Marcelo Caram Ribeiro Fernandes

    2010-12-01

    Full Text Available Objetivos: Quando a visão de um olho está preservada (visão monocular e há alto risco, baixo prognóstico e/ou recursos limitados para a cirurgia do olho contralateral, não é claro se o beneficio da binocularidade supera o da reorientação para visão monocular. O objetivo é quantificar o impacto da qualidade de visão referida entre a condição binocular e monocular e, nesse último caso, entre congênita e adquirida. Métodos: Pacientes com acuidade visual (AV com AV>0,5 em cada olho foram submetidos ao questionário estruturado de 14 perguntas (VF-14, onde a pontuação de 0 a 100 indica o nível de satisfação do paciente com sua visão, variando de baixo a alto respectivamente. Dados epidemiológicos e pontuações dos quatro grupos foram registrados e submetidos à análise estatística. Resultados: A entrevista pelo VF-14 com 56 indivíduos revelou que a pontuação mais alta foi similar entre os controles e os portadores de visão monocular congênita, e níveis intermediários e baixos foram obtidos por indivíduos com visão monocular adquirida e cegos bilaterais, respectivamente (p<0,001. As atividades mais difíceis para os indivíduos com visão monocular adquirida foram identificar letras pequenas, reconhecer pessoas, distinguir sinais de trânsito e assistir TV. Conclusão: O estudo confirmou que a perda da visão tem impacto desfavorável no desempenho referido das atividades sendo maior na visão monocular adquirida do que na congênita. Os dados sugerem que medidas de reabilitação devem ser consideradas para melhorar a qualidade da visão em doenças intratáveis ou de alto risco ou de baixo prognóstico.

  19. 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.

  20. 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.

  1. Duality in binocular rivalry: distinct sensitivity of percept sequence and percept duration to imbalance between monocular stimuli.

    Directory of Open Access Journals (Sweden)

    Chen Song

    Full Text Available BACKGROUND: Visual perception is usually stable and accurate. However, when the two eyes are simultaneously presented with conflicting stimuli, perception falls into a sequence of spontaneous alternations, switching between one stimulus and the other every few seconds. Known as binocular rivalry, this visual illusion decouples subjective experience from physical stimulation and provides a unique opportunity to study the neural correlates of consciousness. The temporal properties of this alternating perception have been intensively investigated for decades, yet the relationship between two fundamental properties - the sequence of percepts and the duration of each percept - remains largely unexplored. METHODOLOGY/PRINCIPAL FINDINGS: Here we examine the relationship between the percept sequence and the percept duration by quantifying their sensitivity to the strength imbalance between two monocular stimuli. We found that the percept sequence is far more susceptible to the stimulus imbalance than does the percept duration. The percept sequence always begins with the stronger stimulus, even when the stimulus imbalance is too weak to cause a significant bias in the percept duration. Therefore, introducing a small stimulus imbalance affects the percept sequence, whereas increasing the imbalance affects the percept duration, but not vice versa. To investigate why the percept sequence is so vulnerable to the stimulus imbalance, we further measured the interval between the stimulus onset and the first percept, during which subjects experienced the fusion of two monocular stimuli. We found that this interval is dramatically shortened with increased stimulus imbalance. CONCLUSIONS/SIGNIFICANCE: Our study shows that in binocular rivalry, the strength imblanace between monocular stimuli has a much greater impact on the percept sequence than on the percept duration, and increasing this imbalance can accelerate the process responsible for the percept sequence.

  2. Reversible binocular visual loss in temporal association with artesunate-amodiaquine treatment in a child on mefloquine chemoprophylaxis.

    Science.gov (United States)

    Adjei, G O; Adabayeri, V M; Annobil, S H

    2012-09-01

    A case of an acute reversible visual loss in a 10-year-old child who was on mefloquine prophylaxis, and was treated with artesunate-amodiaquine for an acute febrile illness diagnosed clinically as uncomplicated malaria, is reported. On admission the patient could not perceive light and had bilateral papilloedema. She was treated with dexamethasone and recovered her sight gradually over a 21-day period. There has been no previous report to our knowledge, of an association between acute visual loss and mefloquine, amodiaquine, or artesunate in the published literature, even though mefloquine is associated with blurring of vision, and antimalarials of the quinoline class have been associated with retinopathy (during long term use). While causality is difficult to ascribe in this case, it may be prudent to avoid the use of quinoline-based antimalarials for treating acute malaria in travelers taking mefloquine prophylaxis, because information on the safety of concurrent use of artemisinin combination therapies and mefloquine, or other recommended prophylactic regimens, is limited.

  3. 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.

  4. Applying theories and interventions from behavioral medicine to understand and reduce visual field variability in patients with vision loss.

    Science.gov (United States)

    Rozanski, Collin; Haythornthwaite, Jennifer A; Dagnelie, Gislin; Bittner, Ava K

    2014-08-01

    Visual field (VF) test results are often unreliable in visually impaired patients, but continue to be a cornerstone of clinical trials and play a vital role in clinical decision making since they are the primary method to determine patients' functional vision loss or progression. Currently, patients are typically asked to perform VF tasks with minimal instruction or consideration of their psychological experience during the test. The gradual loss of vision due to retinal diseases, such as retinitis pigmentosa (RP), age-related macular degeneration (AMD), or glaucoma can contribute to the experience of negative psychosocial states, such as anxiety, stress, and depression, as well as diminished quality of life. We hypothesize that VF testing elicits test performance anxiety and perception of functional losses of vision, which induces distracting negative thoughts that result in increased VF test variability. Resources for processing and responding to vision-related information may be diverted from task-relevant VF stimuli to task-irrelevant ones, such as internal worry and test anxiety, thereby resulting in VF test performance decrements. We present a theoretical model to support the hypothesis that VF variability is linked to patients' negative thoughts during VF testing. This conceptual framework provides a basis for the development of coping strategies and mindfulness-based interventions to be evaluated in future research aimed at improving psychosocial states and VF reliability in visually-impaired patients. It would be highly significant to intervene by modifying negative thoughts during VF testing to reduce test variability in glaucoma patients who are progressively losing vision to a blinding eye disease, but whose vision loss has not been accurately identified and treated early enough due to variable VF results. In clinical trials of potential interventions for RP and non-neovascular AMD, reducing VF variability would effectively increase the precision for

  5. Applying Theories and Interventions from Behavioral Medicine to Understand and Reduce Visual Field Variability in Patients with Vision Loss

    Science.gov (United States)

    Rozanski, Collin; Haythornthwaite, Jennifer A.; Dagnelie, Gislin; Bittner, Ava K.

    2014-01-01

    Visual field (VF) test results are often unreliable in visually impaired patients, but continue to be a cornerstone of clinical trials and play a vital role in clinical decision making since they are the primary method to determine patients’ functional vision loss or progression. Currently, patients are typically asked to perform VF tasks with minimal instruction or consideration of their psychological experience during the test. The gradual loss of vision due to retinal diseases, such as retinitis pigmentosa (RP), age-related macular degeneration (AMD), or glaucoma can contribute to the experience of negative psychosocial states, such as anxiety, stress, and depression, as well as diminished quality of life. We hypothesize that VF testing elicits test performance anxiety and perception of functional losses of vision, which induces distracting negative thoughts that result in increased VF test variability. Resources for processing and responding to vision-related information may be diverted from task-relevant VF stimuli to task-irrelevant ones, such as internal worry and test anxiety, thereby resulting in VF test performance decrements. We present a theoretical model to support the hypothesis that VF variability is linked to patients’ negative thoughts during VF testing. This conceptual framework provides a basis for the development of coping strategies and mindfulness-based interventions to be evaluated in future research aimed at improving psychosocial states and VF reliability in visually-impaired patients. It would be highly significant to intervene by modifying negative thoughts during VF testing to reduce test variability in glaucoma patients who are progressively losing vision to a blinding eye disease, but whose vision loss has not been accurately identified and treated early enough due to variable VF results. In clinical trials of potential interventions for RP and non-neovascular AMD, reducing VF variability would effectively increase the precision

  6. [Synergy of vision and extraocular proprioception in the mechanisms of functional plasticity of the primary visual cortex in the kitten].

    Science.gov (United States)

    Trotter, Y; Fregnac, Y; Buisseret, P

    1983-01-01

    In 6 week old dark reared kittens, a visual monocular exposure for 6 hrs. elicits major functional modifications in the primary visual cortex. Most cells become orientation selective and are activated through the open eye only. However, if a unilateral section of the ophthalmic branch of the fifth nerve is performed 1 week before the monocular exposure, these modifications are less pronounced, particularly when carried out on the same side as the open eye. Moreover, if the ophthalmic branch has been cut bilaterally, visual monocular exposure has almost no effect: cortical cells remain non selective to orientation and binocularly activated.

  7. 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.

  8. Binocular function during unequal monocular input.

    Science.gov (United States)

    Kim, Taekjun; Freeman, Ralph D

    2017-02-01

    The fine task of stereoscopic depth discrimination in human subjects requires a functional binocular system. Behavioral investigations show that relatively small binocular abnormalities can diminish stereoscopic acuity. Clinical evaluations are consistent with this observation. Neurons in visual cortex represent the first stage of processing of the binocular system. Cells at this level are generally acutely sensitive to differences in relative depth. However, an apparent paradox in previous work demonstrates that tuning for binocular disparities remains relatively constant even when large contrast differences are imposed between left and right eye stimuli. This implies a range of neural binocular function that is at odds with behavioral findings. To explore this inconsistency, we have conducted psychophysical tests by which human subjects view vertical sinusoidal gratings drifting in opposite directions to left and right eyes. If the opposite drifting gratings are integrated in visual cortex, as wave theory and neurophysiological data predict, the subjects should perceive a fused stationary grating that is counter-phasing in place. However, this behavioral combination may not occur if there are differences in contrast and therefore signal strength between left and right eye stimuli. As expected for the control condition, our results show fused counter-phase perception for equal inter-ocular grating contrasts. Our experimental tests show a striking retention of counter-phase perception even for relatively large differences in inter-ocular contrast. This finding demonstrates that binocular integration, although relatively coarse, can occur during substantial differences in left and right eye signal strength. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  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. A Robust Approach for a Filter-Based Monocular Simultaneous Localization and Mapping (SLAM System

    Directory of Open Access Journals (Sweden)

    Antoni Grau

    2013-07-01

    Full Text Available Simultaneous localization and mapping (SLAM is an important problem to solve in robotics theory in order to build truly autonomous mobile robots. This work presents a novel method for implementing a SLAM system based on a single camera sensor. The SLAM with a single camera, or monocular SLAM, is probably one of the most complex SLAM variants. In this case, a single camera, which is freely moving through its environment, represents the sole sensor input to the system. The sensors have a large impact on the algorithm used for SLAM. Cameras are used more frequently, because they provide a lot of information and are well adapted for embedded systems: they are light, cheap and power-saving. Nevertheless, and unlike range sensors, which provide range and angular information, a camera is a projective sensor providing only angular measurements of image features. Therefore, depth information (range cannot be obtained in a single step. In this case, special techniques for feature system-initialization are needed in order to enable the use of angular sensors (as cameras in SLAM systems. The main contribution of this work is to present a novel and robust scheme for incorporating and measuring visual features in filtering-based monocular SLAM systems. The proposed method is based in a two-step technique, which is intended to exploit all the information available in angular measurements. Unlike previous schemes, the values of parameters used by the initialization technique are derived directly from the sensor characteristics, thus simplifying the tuning of the system. The experimental results show that the proposed method surpasses the performance of previous schemes.

  11. A robust approach for a filter-based monocular simultaneous localization and mapping (SLAM) system.

    Science.gov (United States)

    Munguía, Rodrigo; Castillo-Toledo, Bernardino; Grau, Antoni

    2013-07-03

    Simultaneous localization and mapping (SLAM) is an important problem to solve in robotics theory in order to build truly autonomous mobile robots. This work presents a novel method for implementing a SLAM system based on a single camera sensor. The SLAM with a single camera, or monocular SLAM, is probably one of the most complex SLAM variants. In this case, a single camera, which is freely moving through its environment, represents the sole sensor input to the system. The sensors have a large impact on the algorithm used for SLAM. Cameras are used more frequently, because they provide a lot of information and are well adapted for embedded systems: they are light, cheap and power-saving. Nevertheless, and unlike range sensors, which provide range and angular information, a camera is a projective sensor providing only angular measurements of image features. Therefore, depth information (range) cannot be obtained in a single step. In this case, special techniques for feature system-initialization are needed in order to enable the use of angular sensors (as cameras) in SLAM systems. The main contribution of this work is to present a novel and robust scheme for incorporating and measuring visual features in filtering-based monocular SLAM systems. The proposed method is based in a two-step technique, which is intended to exploit all the information available in angular measurements. Unlike previous schemes, the values of parameters used by the initialization technique are derived directly from the sensor characteristics, thus simplifying the tuning of the system. The experimental results show that the proposed method surpasses the performance of previous schemes.

  12. [Laser pointers are not toys; eye injury with permanent loss of visual acuity].

    Science.gov (United States)

    Keunen, Jan E E; Delbecq, Ann-Laure M H; Cruysberg, J R M Hans; van Meurs, Jan C; Gan, Ivan M; Berendschot, Tos T J M

    2014-01-01

    In the nineteen-nineties, there was much hype in the European media about presumed laser pointer maculopathy. However, the recent introduction of more powerful and therefore more dangerous laser pointers and their easy availability on the internet necessitates vigilance on the issue. This is an urgent matter, as here we report three cases of proven maculopathy due to an unsafe laser pointer. Three boys aged 13, 9 and 12 years used an unsafe laser pointer as a toy and looked repeatedly into the pointer, resulting in a permanent reduction in visual acuity due to macular damage. Laser pointers are not designed to be children's toys or instruments to annoy people in a crowd. Health authorities and the ophthalmic community should be aware of the potential danger of improper use of high-output laser pointers and warn the general public before the widespread availability of unsafe laser pointers and consequently laser pointer-induced macular damage becomes a true social problem.

  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. 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

    2017-01-01

    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. PMID:28165504

  15. 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.

  16. Progressive memory loss for one year and visual changes for three months

    Directory of Open Access Journals (Sweden)

    Si-yuan FAN

    2014-08-01

    Full Text Available A 49-year-old Chinese male presented with memory loss and vision disturbances. Neurological examination revealed bilateral positive Babinski signs. Cognitive assessments showed cognitive impairments. Neuroimaging studies showed high-intensity signals on bilateral parietal lobes, occipital lobes, temporal lobes, the splenium of the corpus callosum, and pyramidal tracts. Plasma very long chain fatty acids (VLCFA assay was ordered and demonstrated abnormally high concentrations of C26:0, and abnormally high ratios of C24:0 and C26:0 to C22:0. This diagnosis was also supported by the pathogenic mutation detected in the ACBD1 gene. There was no significant adrenal insufficiency, so replacement therapy was not initiated. doi: 10.3969/j.issn.1672-6731.2014.08.018

  17. Visual loss due to paranasal sinus invasive aspergillosis in a diabetic patient.

    Science.gov (United States)

    Rallis, George; Gkinis, George; Dais, Panayotis; Stathopoulos, Panagiotis

    2014-01-01

    Aspergillus species are commonly found in the soil and decaying organic matter. The spores can be typically inhaled or ingested, yet disease due to tissue invasion is rarely seen in the immunocompetent host. In the immunocompromised patient, there has been an increased incidence of invasive aspergillosis in the last 20 years. Invasive aspergillosis of the maxillary sinus with orbital and cranial spread can be lethal, therefore, necessitates early diagnosis and prompt treatment. The predilection of Aspergillus for infiltration of blood vessels can result in serious ocular complications which can lead to loss of vision. We present the case of an uncontrolled diabetic patient with invasive maxillary sinus aspergillosis and extension to the orbital contents. Our purpose was to emphasize the need of early recognition and prompt initiation of combined antifungal treatment and surgical intervention with the intent to preserve the involved vital structures.

  18. Early magnocellular loss in glaucoma demonstrated using the pseudorandomly stimulated flash visual evoked potential.

    Science.gov (United States)

    Klistorner, A I; Graham, S L

    1999-04-01

    Components of the pseudorandomly stimulated flash visual evoked potential (VEP) have now been identified that appear to arise predominantly from each of the magnocellular (M-cell) and parvocellular (P-cell) systems. In this study, the relative damage to magnocellular and parvocellular systems at different stages of glaucoma using pseudorandomly stimulated flash VEP was investigated. Pseudorandomly stimulated flash VEP was recorded in 15 normal eyes and 28 eyes with different stages of glaucoma using the VERIS-3 recording system (Electro-Diagnostic Imaging, San Francisco, CA). Two levels of luminance contrast of the stimulus (32% and 99%) were tested. The first slice of the second-order kernel from only the central (8 degrees) stimulated area was extracted for analysis. Data recorded from normal eyes demonstrated early saturation of the response/contrast function of the first slice of the second-order kernel. The ratio of the VEP amplitude recorded at 32% and 99% of the luminance contrast was close to unity. In eyes with early glaucoma, although the amplitude of the responses to both low- and high-contrast stimulation decreased, the relative reduction of the low-contrast VEP (M-cell) was more prominent. However, the amplitude of the high-contrast response (P-cell) declined more rapidly later in the disease. These results are consistent with relatively earlier damage of the magnocellular pathway in glaucoma.

  19. 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.

  20. 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

  1. 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 d

  2. Deformable Surface 3D Reconstruction from Monocular Images

    CERN Document Server

    Salzmann, Matthieu

    2010-01-01

    Being able to recover the shape of 3D deformable surfaces from a single video stream would make it possible to field reconstruction systems that run on widely available hardware without requiring specialized devices. However, because many different 3D shapes can have virtually the same projection, such monocular shape recovery is inherently ambiguous. In this survey, we will review the two main classes of techniques that have proved most effective so far: The template-based methods that rely on establishing correspondences with a reference image in which the shape is already known, and non-rig

  3. Automatic gear sorting system based on monocular vision

    Directory of Open Access Journals (Sweden)

    Wenqi Wu

    2015-11-01

    Full Text Available An automatic gear sorting system based on monocular vision is proposed in this paper. A CCD camera fixed on the top of the sorting system is used to obtain the images of the gears on the conveyor belt. The gears׳ features including number of holes, number of teeth and color are extracted, which is used to categorize the gears. Photoelectric sensors are used to locate the gears׳ position and produce the trigger signals for pneumatic cylinders. The automatic gear sorting is achieved by using pneumatic actuators to push different gears into their corresponding storage boxes. The experimental results verify the validity and reliability of the proposed method and system.

  4. Visual Impairment, Hearing Loss and Cognitive Function in an Older Population: Longitudinal Findings from the Blue Mountains Eye Study.

    Directory of Open Access Journals (Sweden)

    Thomas Hong

    Full Text Available The presence of visual impairment (VI and hearing loss (HL with may be a marker for subsequent cognitive decline over time in older people. A prospective, longitudinal population-based study of the 3654 participants of the Blue Mountains Eye Study were assessed for the associations between VI and HL and a decline in mini-mental state examination (MMSE scores over a duration of 10 years from the 5-year (baseline of this report to the 15-year follow-up visits. MMSE was assessed at the 5-, 10- and 15-year follow-up visits. A decline ≥3 scores from 5-year to 10- or 15-year visits indicated possible cognitive decline. VI was defined as best-corrected visual acuity 40 decibels in the worse-ear and dual sensory impairment (DSI was defined by the co-presence of VI and HL, detected at 5-year follow-up (baseline of this report. Participants with no VI and HL over the same 5- or 10-year corresponding period were controls. Associations of VI, HL and DSI with possible cognitive decline were assessed using logistic regression models adjusting for age and sex after excluding subjects with a stroke history. The presence of VI, HL or DSI was not associated with possible cognitive decline over 5 years (odds ratio (OR 0.84, 95% confidence-intervals (CI 0.40-1.79, OR 1.02, 95% CI 0.61-1.70 and 1.41, 95% CI 0.54-3.72, respectively or 10 years (OR 1.09, 95% CI 0.52-2.30, OR 1.09, 95% CI 0.65-1.82 and 1.15, 95% CI 0.28-4.73, respectively. There were no changes to these findings after adjustment for other potential confounders. Age was significantly associated with possible cognitive decline (OR 1.07, 95% CI 1.04-1.10 for both periods. Neither visual impairment, hearing loss nor dual sensory impairment was independently associated with subsequent decline in cognition.

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

    Directory of Open Access Journals (Sweden)

    August Kampf-Lassin

    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.

  6. Monocular accommodation condition in 3D display types through geometrical optics

    Science.gov (United States)

    Kim, Sung-Kyu; Kim, Dong-Wook; Park, Min-Chul; Son, Jung-Young

    2007-09-01

    Eye fatigue or strain phenomenon in 3D display environment is a significant problem for 3D display commercialization. The 3D display systems like eyeglasses type stereoscopic or auto-stereoscopic multiview, Super Multi-View (SMV), and Multi-Focus (MF) displays are considered for detail calculation about satisfaction level of monocular accommodation by geometrical optics calculation means. A lens with fixed focal length is used for experimental verification about numerical calculation of monocular defocus effect caused by accommodation at three different depths. And the simulation and experiment results consistently show relatively high level satisfaction about monocular accommodation at MF display condition. Additionally, possibility of monocular depth perception, 3D effect, at monocular MF display is discussed.

  7. Impact of superior and inferior visual field loss on hazard detection in a computer-based driving test.

    Science.gov (United States)

    Glen, Fiona C; Smith, Nicholas D; Crabb, David P

    2015-05-01

    Binocular visual field (VF) loss is linked to driving impairment, guiding authorities to implement fitness to drive requirements for VFs. Yet, evidence is limited regarding the specific types of VF defect that impede driving. This study used a novel gaze-contingent display to test the hypothesis that superior VF loss impacts detection of driving hazards more than inferior loss. The Hazard Perception Test (HPT) is a computer-based component of the UK examination for learner drivers. It measures the response rate for detecting hazards in a series of real-life driving films, yielding a score out of 75, calculated based on the efficiency of detecting 15 hazards. Thirty UK drivers with healthy vision completed three versions of the HPT in a random order. In two versions, a computer set-up incorporating an eye-tracker modified a simulated VF defect in the superior and inferior VFs, respectively, according to the users' real-time gaze as they completed the HPT. The other version was unmodified to measure the baseline performance. Participants' mean score at baseline was 49/75 (SD=9). Mean (SD) performance fell by 18% (40(11)) when viewing films with a superior defect and 12% with an inferior defect (43(10)). These average differences were statistically significant (p<0.001; 95% CI for mean difference=1-7) CONCLUSIONS: In this study, simulated VF defects impaired the ability to detect driving hazards relative to participants' normal performances, with superior defects having more impact than inferior defects. These results could help inform the design of fairer tests of the VF component for fitness to drive. 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.

  8. Diffusion tensor imaging correlates of visual impairment in multiple sclerosis and chronic optic neuritis.

    Science.gov (United States)

    Kolbe, Scott C; Marriott, Mark; Walt, Anneke van der; Fielding, Joanne; Klistorner, Alexander; Mitchell, Peter J; Butzkueven, Helmut; Kilpatrick, Trevor J; Egan, Gary F

    2012-02-21

    To compare white matter (WM) injuries associated with vision loss in multiple sclerosis (MS) and optic neuritis (ON). Twenty-three patients with clinically definite relapsing-remitting MS and chronic unilateral ON and 14 neurologically healthy volunteers were monocularly tested with Sloan 100%, 2.5%, and 1.25% contrast visual acuity charts. Primary visual pathway and whole-brain WM injury were assessed with optical coherence tomography (OCT) and diffusion tensor imaging (DTI). OCT and DTI correlates of high- and low-contrast visual impairment were identified using correlation analyses. The MS patients displayed significantly reduced retinal nerve fiber layer (RNFL) thickness and altered optic nerve and radiation DTI measures compared with the controls. In the patients, 2.5% and 1.25% contrast letter acuity in the unaffected eye correlated significantly and independently with optic nerve and optic radiation DTI measures. Visual acuity in affected eyes did not correlate with optic nerve or optic radiation DTI measures, but did correlate with DTI measures in prefrontal and temporal brain regions that were shown to connect structurally to visual cortices. In unaffected eyes, visual impairment was associated with WM injury in the visual pathway. In contrast, irrecoverable visual impairment after ON was associated with injury to frontal WM, which potentially impairs the capacity for remapping visual processing.

  9. Stereoscopic 3D-scene synthesis from a monocular camera with an electrically tunable lens

    Science.gov (United States)

    Alonso, Julia R.

    2016-09-01

    3D-scene acquisition and representation is important in many areas ranging from medical imaging to visual entertainment application. In this regard, optical imaging acquisition combined with post-capture processing algorithms enable the synthesis of images with novel viewpoints of a scene. This work presents a new method to reconstruct a pair of stereoscopic images of a 3D-scene from a multi-focus image stack. A conventional monocular camera combined with an electrically tunable lens (ETL) is used for image acquisition. The captured visual information is reorganized considering a piecewise-planar image formation model with a depth-variant point spread function (PSF) along with the known focusing distances at which the images of the stack were acquired. The consideration of a depth-variant PSF allows the application of the method to strongly defocused multi-focus image stacks. Finally, post-capture perspective shifts, presenting each eye the corresponding viewpoint according to the disparity, are generated by simulating the displacement of a synthetic pinhole camera. The procedure is performed without estimation of the depth-map or segmentation of the in-focus regions. Experimental results for both real and synthetic data images are provided and presented as anaglyphs, but it could easily be implemented in 3D displays based in parallax barrier or polarized light.

  10. Inter-ocular contrast normalization in human visual cortex.

    Science.gov (United States)

    Moradi, Farshad; Heeger, David J

    2009-03-20

    The brain combines visual information from the two eyes and forms a coherent percept, even when inputs to the eyes are different. However, it is not clear how inputs from the two eyes are combined in visual cortex. We measured fMRI responses to single gratings presented monocularly, or pairs of gratings presented monocularly or dichoptically with several combinations of contrasts. Gratings had either the same orientation or orthogonal orientations (i.e., plaids). Observers performed a demanding task at fixation to minimize top-down modulation of the stimulus-evoked responses. Dichoptic presentation of compatible gratings (same orientation) evoked greater activity than monocular presentation of a single grating only when contrast was low (presentation of orthogonal gratings evoked greater activity than monocular presentation of a single grating for all contrasts. However, activity evoked by dichoptic plaids was equal to that evoked by monocular plaids. Introducing an onset asynchrony (stimulating one eye 500 ms before the other, which under attentive vision results in flash suppression) had no impact on the results; the responses to dichoptic and monocular plaids were again equal. We conclude that when attention is diverted, inter-ocular suppression in V1 can be explained by a normalization model in which the mutual suppression between orthogonal orientations does not depend on the eye of origin, nor on the onset times, and cross-orientation suppression is weaker than inter-ocular (same orientation) suppression.

  11. 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

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

    Science.gov (United States)

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

    2014-01-01

    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 the

  13. Human Pose Estimation from Monocular Images: A Comprehensive Survey

    Directory of Open Access Journals (Sweden)

    Wenjuan Gong

    2016-11-01

    Full Text Available Human pose estimation refers to the estimation of the location of body parts and how they are connected in an image. Human pose estimation from monocular images has wide applications (e.g., image indexing. Several surveys on human pose estimation can be found in the literature, but they focus on a certain category; for example, model-based approaches or human motion analysis, etc. As far as we know, an overall review of this problem domain has yet to be provided. Furthermore, recent advancements based on deep learning have brought novel algorithms for this problem. In this paper, a comprehensive survey of human pose estimation from monocular images is carried out including milestone works and recent advancements. Based on one standard pipeline for the solution of computer vision problems, this survey splits the problem into several modules: feature extraction and description, human body models, and modeling methods. Problem modeling methods are approached based on two means of categorization in this survey. One way to categorize includes top-down and bottom-up methods, and another way includes generative and discriminative methods. Considering the fact that one direct application of human pose estimation is to provide initialization for automatic video surveillance, there are additional sections for motion-related methods in all modules: motion features, motion models, and motion-based methods. Finally, the paper also collects 26 publicly available data sets for validation and provides error measurement methods that are frequently used.

  14. Axonal loss in non-optic neuritis eyes of patients with multiple sclerosis linked to delayed visual evoked potential.

    Science.gov (United States)

    Klistorner, Alexandr; Garrick, Raymond; Barnett, Michael H; Graham, Stuart L; Arvind, Hemamalini; Sriram, Prema; Yiannikas, Con

    2013-01-15

    Recent studies demonstrate significant thinning of the retinal nerve fiber layer (RNFL) in multiple sclerosis (MS) non-optic neuritis (MS-NON) eyes. However, the pathologic basis of this reduction is not clear. The aim of the current study was to investigate the relationship of the RNFL thickness in MS-NON eyes with latency delay of the multifocal visual evoked potential (mfVEP), a surrogate marker of the visual pathway demyelination. Total and temporal RNFL thickness and latency of the mfVEP in 45 MS-NON eyes of 45 patients with relapsing-remitting MS and 25 eyes of age- and gender-matched controls were measured and analyzed. There was significant reduction of total and temporal RNFL thickness (p = 0.015 and p = 0.006, respectively) and significant latency delay (p < 0.0001) in MS-NON eyes. Both total and temporal RNFL thickness were associated with latency of the mfVEP (r2 = 0.43, p < 0.0001 and r2 = 0.36, p = 0.001, respectively). MS-NON eyes with normal latency (n = 26) showed no significant reduction of RNFL thickness compared with controls (p = 0.44 and p = 0.1 for total and temporal RNFL, respectively), whereas eyes with delayed latency (n = 19) demonstrated significantly thinner RNFL (p = 0.001 and p = 0.0005). MS-NON eyes with delayed latency also had significantly thinner RNFL compared with those with normal latencies (p = 0.013 and p = 0.02). In patients with no previous optic neuritis in either eye, delayed latency and reduced RNFL were bilateral whenever present. The study demonstrated significant association between RNFL loss and a latency delay of the mfVEP in MS-NON eyes.

  15. A Re-Evaluation of Achromatic Spatiotemporal Vision: Nonoriented Filters are Monocular, they Adapt and Can be Used for Decision-Making at High Flicker Speeds

    Directory of Open Access Journals (Sweden)

    Tim S. Meese

    2011-05-01

    Full Text Available Masking, adaptation, and summation paradigms have been used to investigate the characteristics of early spatiotemporal vision. Each has been taken to provide evidence for (i oriented and (ii nonoriented spatial filtering mechanisms. However, subsequent findings suggest that the evidence for nonoriented mechanisms has been misinterpreted: possibly, those experiments revealed the characteristics of suppression (e.g., gain control not excitation, or merely the isotropic subunits of the oriented detecting-mechanisms. To shed light on this, we used all three paradigms to focus on the “high-speed” corner of spatiotemporal vision (low spatial frequency, high temporal frequency where cross-oriented achromatic effects are greatest. We used flickering Gabor patches as targets and a 2IFC procedure for monocular, binocular and dichoptic stimulus presentations. To account for our results we devised a simple model involving an isotropic monocular filter-stage feeding orientation-tuned binocular filters. Both filter stages are adaptable and their outputs are available to the decision-stage following nonlinear contrast transduction. However, the monocular isotropic filters adapt only to high-speed stimuli—consistent with a magnocellular sub-cortical substrate—and benefit decision making only for high-speed stimuli. According to this model, the visual processes revealed by masking, adaptation and summation are related but not identical.

  16. 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.

  17. Postoperative visual loss following cerebral arteriovenous malformation surgery: a case report [v2; ref status: indexed, http://f1000r.es/308

    Directory of Open Access Journals (Sweden)

    Nicolai Goettel

    2014-03-01

    Full Text Available We report the case of a 46 year-old woman presenting with unilateral postoperative visual loss after right frontal craniotomy for resection of an arteriovenous malformation in the supine position. The intraoperative course was uneventful with maintenance of hemodynamic stability. Blood loss was 300 ml; postoperative hemoglobin was 12.4 g/dl. In the recovery room, the patient reported loss of vision in her right eye. Ophthalmologic examination revealed decreased visual acuity, color vision, and visual field. Assessment of the retina was normal, but the patient showed a relative afferent pupillary defect consistent with the clinical diagnosis of ischemic optic neuropathy. Postoperative computer tomogram showed normal perfusion of ophthalmic artery and vein, no hemorrhage or signs of cerebral ischemia or edema. The patient recovered most of her vision 3 months after surgery. Anesthesiologists should be aware that this condition may follow uncomplicated intracranial surgeries in the supine position, and should obtain prompt ophthalmologic consultation when a patient develops postoperative visual loss.

  18. 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...

  19. Central serous retinopathy with permanent visual deficit in a commercial air transport pilot: a case report.

    Science.gov (United States)

    Newman, David G

    2002-11-01

    This report describes a case of central serous retinopathy (CSR) in the right eye of a commercial air transport pilot which resulted in a permanent reduction in visual acuity and the loss of his license. The previously fit and well pilot developed sudden loss of central vision, which resolved spontaneously. He then went on to experience recurrent episodes of fluctuating visual acuity (down to 6/60) and visual dysfunction in the right eye. His left eye remained unaffected. Eventually his condition stabilized, and he was left with a permanent reduction in right visual acuity (6/36) with intact peripheral visual fields and a completely normal left eye. After a period of grounding of 12 mo, he sought to have his license reinstated. He was considered to be a functionally monocular pilot, and as such was granted a conditional Class 1 medical category. The aeromedical disposition of this pilot and the issues involved in determining the fitness to fly of pilots with permanent visual defects arising from CSR are discussed.

  20. Novel approach for mobile robot localization using monocular vision

    Science.gov (United States)

    Zhong, Zhiguang; Yi, Jianqiang; Zhao, Dongbin; Hong, Yiping

    2003-09-01

    This paper presents a novel approach for mobile robot localization using monocular vision. The proposed approach locates a robot relative to the target to which the robot moves. Two points are selected from the target as two feature points. Once the coordinates in an image of the two feature points are detected, the position and motion direction of the robot can be determined according to the detected coordinates. Unlike those reported geometry pose estimation or landmarks matching methods, this approach requires neither artificial landmarks nor an accurate map of indoor environment. It needs less computation and can simplify greatly the localization problem. The validity and flexibility of the proposed approach is demonstrated by experiments performed on real images. The results show that this new approach is not only simple and flexible but also has high localization precision.

  1. 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.

  2. Markerless monocular tracking system for guided external eye surgery.

    Science.gov (United States)

    Monserrat, C; Rupérez, M J; Alcañiz, M; Mataix, J

    2014-12-01

    This paper presents a novel markerless monocular tracking system aimed at guiding ophthalmologists during external eye surgery. This new tracking system performs a very accurate tracking of the eye by detecting invariant points using only textures that are present in the sclera, i.e., without using traditional features like the pupil and/or cornea reflections, which remain partially or totally occluded in most surgeries. Two known algorithms that compute invariant points and correspondences between pairs of images were implemented in our system: Scalable Invariant Feature Transforms (SIFT) and Speed Up Robust Features (SURF). The results of experiments performed on phantom eyes show that, with either algorithm, the developed system tracks a sphere at a 360° rotation angle with an error that is lower than 0.5%. Some experiments have also been carried out on images of real eyes showing promising behavior of the system in the presence of blood or surgical instruments during real eye surgery.

  3. Monocular 3D scene reconstruction at absolute scale

    Science.gov (United States)

    Wöhler, Christian; d'Angelo, Pablo; Krüger, Lars; Kuhl, Annika; Groß, Horst-Michael

    In this article we propose a method for combining geometric and real-aperture methods for monocular three-dimensional (3D) reconstruction of static scenes at absolute scale. Our algorithm relies on a sequence of images of the object acquired by a monocular camera of fixed focal setting from different viewpoints. Object features are tracked over a range of distances from the camera with a small depth of field, leading to a varying degree of defocus for each feature. Information on absolute depth is obtained based on a Depth-from-Defocus approach. The parameters of the point spread functions estimated by Depth-from-Defocus are used as a regularisation term for Structure-from-Motion. The reprojection error obtained from bundle adjustment and the absolute depth error obtained from Depth-from-Defocus are simultaneously minimised for all tracked object features. The proposed method yields absolutely scaled 3D coordinates of the scene points without any prior knowledge about scene structure and camera motion. We describe the implementation of the proposed method both as an offline and as an online algorithm. Evaluating the algorithm on real-world data, we demonstrate that it yields typical relative scale errors of a few per cent. We examine the influence of random effects, i.e. the noise of the pixel grey values, and systematic effects, caused by thermal expansion of the optical system or by inclusion of strongly blurred images, on the accuracy of the 3D reconstruction result. Possible applications of our approach are in the field of industrial quality inspection; in particular, it is preferable to stereo cameras in industrial vision systems with space limitations or where strong vibrations occur.

  4. RBF-Based Monocular Vision Navigation for Small Vehicles in Narrow Space below Maize Canopy

    Directory of Open Access Journals (Sweden)

    Lu Liu

    2016-06-01

    Full Text Available Maize is one of the major food crops in China. Traditionally, field operations are done by manual labor, where the farmers are threatened by the harsh environment and pesticides. On the other hand, it is difficult for large machinery to maneuver in the field due to limited space, particularly in the middle and late growth stage of maize. Unmanned, compact agricultural machines, therefore, are ideal for such field work. This paper describes a method of monocular visual recognition to navigate small vehicles between narrow crop rows. Edge detection and noise elimination were used for image segmentation to extract the stalks in the image. The stalk coordinates define passable boundaries, and a simplified radial basis function (RBF-based algorithm was adapted for path planning to improve the fault tolerance of stalk coordinate extraction. The average image processing time, including network latency, is 220 ms. The average time consumption for path planning is 30 ms. The fast processing ensures a top speed of 2 m/s for our prototype vehicle. When operating at the normal speed (0.7 m/s, the rate of collision with stalks is under 6.4%. Additional simulations and field tests further proved the feasibility and fault tolerance of our method.

  5. Why is binocular rivalry uncommon? Discrepant monocular images in the real world

    Directory of Open Access Journals (Sweden)

    Derek Henry Arnold

    2011-10-01

    Full Text Available When different images project to corresponding points in the two eyes they can instigate a phenomenon called binocular rivalry (BR, wherein each image seems to intermittently disappear such that only one of the two images is seen at a time. Cautious readers may have noted an important caveat in the opening sentence – this situation can instigate BR, but usually it doesn’t. Unmatched monocular images are frequently encountered in daily life due to either differential occlusions of the two eyes or because of selective obstructions of just one eye, but this does not tend to induce BR. Here I will explore the reasons for this and discuss implications for BR in general. It will be argued that BR is resolved in favour of the instantaneously stronger neural signal, and that this process is driven by an adaptation that enhances the visibility of distant fixated objects over that of more proximate obstructions of an eye. Accordingly, BR would reflect the dynamics of an inherently visual operation that usually deals with real-world constraints.

  6. DEPRIVATION AND STRABISMIC AMBLYOPIA: ABNORMALITIES IN GENICULOCORTICAL VISUAL PATHWAYS

    Directory of Open Access Journals (Sweden)

    S. V. Alekseenko

    2015-01-01

    Full Text Available Background: There are inconsistent data on the changes of functional performance in subcortical structures of visual system caused by early binocular vision impairment. Aim: To study neuronal functional activity of the dorsal lateral geniculate nucleus (LGNd in monocularly deprived cats and strabismic cats. Materials and methods: 4 cats with monocular convergent strabismus, 7 cats with monocular divergent strabismus, 3 monocularly deprived cats and 4 intact cats were studied. Histochemical method was used to detect cytochrome oxidase – the mitochondrial enzyme of respiratory chain correlating with neuronal functional activity. Optical density in ocular-specific layers A and A1 was measured on the images of stained LGNd sections, and the contrast was calculated. Results: Relative reduction of functional activity in the layers innervated from deprived and squinted eyes was demonstrated in LGNd bilaterally. In strabismic animals, the changes were observed only in the projection of the central part of the visual field, whereas in monocularly deprived animals the changes were in the projection of the whole visual field. Conclusion: These findings indicate differences between the mechanisms determining the development of strabismic and deprivation amblyopia. Thus, in amblyopia, preservation of peripheral stereoscopic vision is possible.

  7. Audio-visual speechreading in a group of hearing aid users. The effects of onset age, handicap age, and degree of hearing loss.

    Science.gov (United States)

    Tillberg, I; Rönnberg, J; Svärd, I; Ahlner, B

    1996-01-01

    Speechreading ability was investigated among hearing aid users with different time of onset and different degree of hearing loss. Audio-visual and visual-only performance were assessed. One group of subjects had been hearing-impaired for a large part of their lives, and the impairments appeared early in life. The other group of subjects had been impaired for a fewer number of years, and the impairments appeared later in life. Differences between the groups were obtained. There was no significant difference on the audio-visual test between the groups in spite of the fact that the early onset group scored very poorly auditorily. However, the early-onset group performed significantly better on the visual test. It was concluded that the visual information constituted the dominant coding strategy for the early onset group. An interpretation chiefly in terms of early onset may be the most appropriate, since dB loss variations as such are not related to speechreading skill.

  8. Partial Visual Loss Affects Self-reports of Hearing Abilities Measured Using a Modified Version of the Speech, Spatial, and Qualities of Hearing Questionnaire.

    Science.gov (United States)

    Kolarik, Andrew J; Raman, Rajiv; Moore, Brian C J; Cirstea, Silvia; Gopalakrishnan, Sarika; Pardhan, Shahina

    2017-01-01

    We assessed how visually impaired (VI) people perceived their own auditory abilities using an established hearing questionnaire, the Speech, Spatial, and Qualities of Hearing Scale (SSQ), that was adapted to make it relevant and applicable to VI individuals by removing references to visual aspects while retaining the meaning of the original questions. The resulting questionnaire, the SSQvi, assessed perceived hearing ability in diverse situations including the ability to follow conversations with multiple speakers, assessing how far away a vehicle is, and the ability to perceptually segregate simultaneous sounds. The SSQvi was administered to 33 VI and 33 normally sighted participants. All participants had normal hearing or mild hearing loss, and all VI participants had some residual visual ability. VI participants gave significantly higher (better) scores than sighted participants for: (i) one speech question, indicating less difficulty in following a conversation that switches from one person to another, (ii) one spatial question, indicating less difficulty in localizing several talkers, (iii) three qualities questions, indicating less difficulty with segregating speech from music, hearing music more clearly, and better speech intelligibility in a car. These findings are consistent with the perceptual enhancement hypothesis, that certain auditory abilities are improved to help compensate for loss of vision, and show that full visual loss is not necessary for perceived changes in auditory ability to occur for a range of auditory situations. For all other questions, scores were not significantly different between the two groups. Questions related to effort, concentration, and ignoring distracting sounds were rated as most difficult for VI participants, as were situations involving divided-attention contexts with multiple streams of speech, following conversations in noise and in echoic environments, judging elevation or distance, and externalizing sounds. The

  9. The effect of monocular depth cues on the detection of moving objects by moving observers

    National Research Council Canada - National Science Library

    Royden, Constance S; Parsons, Daniel; Travatello, Joshua

    2016-01-01

    ... and thus is an ambiguous cue. We tested whether the addition of information about the distance of objects from the observer, in the form of monocular depth cues, aided detection of moving objects...

  10. The role of monocularly visible regions in depth and surface perception.

    Science.gov (United States)

    Harris, Julie M; Wilcox, Laurie M

    2009-11-01

    The mainstream of binocular vision research has long been focused on understanding how binocular disparity is used for depth perception. In recent years, researchers have begun to explore how monocular regions in binocularly viewed scenes contribute to our perception of the three-dimensional world. Here we review the field as it currently stands, with a focus on understanding the extent to which the role of monocular regions in depth perception can be understood using extant theories of binocular vision.

  11. Bilateral paraneoplastic optic neuropathy and unilateral retinal compromise in association with prostate cancer: a differential diagnostic challenge in a patient with unexplained visual loss.

    Science.gov (United States)

    Carboni, Giovannella; Forma, Gina; Bond, April D; Adamus, Grazyna; Iannaccone, Alessandro

    2012-08-01

    We report a 77-year-old Caucasian man with a 1-year complaint of unexplained visual loss and a 4-year history of prostate cancer. A complete ophthalmologic exam, Goldmann visual fields (GVFs), intravenous fluorescein angiography (IVFA), macular and disc optical coherence tomography (OCT), pattern-reversal visual evoked potentials (PVEPs), and flash electroretinograms (ERGs) were performed. On examination, visual acuity was reduced bilaterally. Fundus exam showed juxtapapillary changes (OS > OD) and, in OS, disc pallor, peripheral RPE dropout and whitish retinal discoloration along the arcades. OCTs were normal OU. Cancer-associated retinopathy (CAR) was suspected. A flash ERG was normal OD and markedly reduced and electronegative OS. An IVFA showed bilateral juxtapapillary staining and changes highly suggestive of sequelae of central retinal artery occlusion (CRAO) OS , in which a cilioretinal artery existed along the papillomacular bundle. GVFs showed bilateral blind spot enlargement and centrocecal scotomas, and PVEPs were delayed. These findings suggested cancer-associated optic neuropathy (CAON), confirmed by presence of anti-optic nerve autoantibodies (auto-Abs). No anti-retinal auto-Abs were found. CAON is a less common paraneoplastic manifestation than CAR and it is rarely observed in association with prostate cancer. A combination of visual function testing methods permitted the recognition, in this highly unusual case, of the concurrent presence of unilateral ERG changes most likely attributable to CRAO complications in OS, in all likelihood unrelated to CAON, and not to be confused with unilateral CAR. Auto-Ab testing in combination with visual function tests helps achieve a better understanding of the pathophysiology of vision loss in paraneoplastic visual syndromes.

  12. Content and context of monocular regions determine perceived depth in random dot, unpaired background and phantom stereograms.

    Science.gov (United States)

    Grove, Philip M; Gillam, Barbara; Ono, Hiroshi

    2002-07-01

    Perceived depth was measured for three-types of stereograms with the colour/texture of half-occluded (monocular) regions either similar to or dissimilar to that of binocular regions or background. In a two-panel random dot stereogram the monocular region was filled with texture either similar or different to the far panel or left blank. In unpaired background stereograms the monocular region either matched the background or was different in colour or texture and in phantom stereograms the monocular region matched the partially occluded object or was a different colour or texture. In all three cases depth was considerably impaired when the monocular texture did not match either the background or the more distant surface. The content and context of monocular regions as well as their position are important in determining their role as occlusion cues and thus in three-dimensional layout. We compare coincidence and accidental view accounts of these effects.

  13. 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.

  14. 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 .

  15. Development of a monocular vision system for robotic drilling

    Institute of Scientific and Technical Information of China (English)

    Wei-dong ZHU; Biao MEI; Guo-rui YAN; Ying-lin KE

    2014-01-01

    Robotic drilling for aerospace structures demands a high positioning accuracy of the robot, which is usually achieved through error measurement and compensation. In this paper, we report the development of a practical monocular vision system for measurement of the relative error between the drill tool center point (TCP) and the reference hole. First, the principle of relative error measurement with the vision system is explained, followed by a detailed discussion on the hardware components, software components, and system integration. The elliptical contour extraction algorithm is presented for accurate and robust reference hole detection. System calibration is of key importance to the measurement accuracy of a vision system. A new method is proposed for the simultaneous calibration of camera internal parameters and hand-eye relationship with a dedicated calibration board. Extensive measurement experiments have been performed on a robotic drilling system. Experimental results show that the measurement accuracy of the developed vision system is higher than 0.15 mm, which meets the requirement of robotic drilling for aircraft structures.

  16. Deep monocular 3D reconstruction for assisted navigation in bronchoscopy.

    Science.gov (United States)

    Visentini-Scarzanella, Marco; Sugiura, Takamasa; Kaneko, Toshimitsu; Koto, Shinichiro

    2017-07-01

    In bronchoschopy, computer vision systems for navigation assistance are an attractive low-cost solution to guide the endoscopist to target peripheral lesions for biopsy and histological analysis. We propose a decoupled deep learning architecture that projects input frames onto the domain of CT renderings, thus allowing offline training from patient-specific CT data. A fully convolutional network architecture is implemented on GPU and tested on a phantom dataset involving 32 video sequences and [Formula: see text]60k frames with aligned ground truth and renderings, which is made available as the first public dataset for bronchoscopy navigation. An average estimated depth accuracy of 1.5 mm was obtained, outperforming conventional direct depth estimation from input frames by 60%, and with a computational time of [Formula: see text]30 ms on modern GPUs. Qualitatively, the estimated depth and renderings closely resemble the ground truth. The proposed method shows a novel architecture to perform real-time monocular depth estimation without losing patient specificity in bronchoscopy. Future work will include integration within SLAM systems and collection of in vivo datasets.

  17. Global localization from monocular SLAM on a mobile phone.

    Science.gov (United States)

    Ventura, Jonathan; Arth, Clemens; Reitmayr, Gerhard; Schmalstieg, Dieter

    2014-04-01

    We propose the combination of a keyframe-based monocular SLAM system and a global localization method. The SLAM system runs locally on a camera-equipped mobile client and provides continuous, relative 6DoF pose estimation as well as keyframe images with computed camera locations. As the local map expands, a server process localizes the keyframes with a pre-made, globally-registered map and returns the global registration correction to the mobile client. The localization result is updated each time a keyframe is added, and observations of global anchor points are added to the client-side bundle adjustment process to further refine the SLAM map registration and limit drift. The end result is a 6DoF tracking and mapping system which provides globally registered tracking in real-time on a mobile device, overcomes the difficulties of localization with a narrow field-of-view mobile phone camera, and is not limited to tracking only in areas covered by the offline reconstruction.

  18. 3D environment capture from monocular video and inertial data

    Science.gov (United States)

    Clark, R. Robert; Lin, Michael H.; Taylor, Colin J.

    2006-02-01

    This paper presents experimental methods and results for 3D environment reconstruction from monocular video augmented with inertial data. One application targets sparsely furnished room interiors, using high quality handheld video with a normal field of view, and linear accelerations and angular velocities from an attached inertial measurement unit. A second application targets natural terrain with manmade structures, using heavily compressed aerial video with a narrow field of view, and position and orientation data from the aircraft navigation system. In both applications, the translational and rotational offsets between the camera and inertial reference frames are initially unknown, and only a small fraction of the scene is visible in any one video frame. We start by estimating sparse structure and motion from 2D feature tracks using a Kalman filter and/or repeated, partial bundle adjustments requiring bounded time per video frame. The first application additionally incorporates a weak assumption of bounding perpendicular planes to minimize a tendency of the motion estimation to drift, while the second application requires tight integration of the navigational data to alleviate the poor conditioning caused by the narrow field of view. This is followed by dense structure recovery via graph-cut-based multi-view stereo, meshing, and optional mesh simplification. Finally, input images are texture-mapped onto the 3D surface for rendering. We show sample results from multiple, novel viewpoints.

  19. Mobile Robot Hierarchical Simultaneous Localization and Mapping Using Monocular Vision

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A hierarchical mobile robot simultaneous localization and mapping (SLAM) method that allows us to obtain accurate maps was presented. The local map level is composed of a set of local metric feature maps that are guaranteed to be statistically independent. The global level is a topological graph whose arcs are labeled with the relative location between local maps. An estimation of these relative locations is maintained with local map alignment algorithm, and more accurate estimation is calculated through a global minimization procedure using the loop closure constraint. The local map is built with Rao-Blackwellised particle filter (RBPF), where the particle filter is used to extending the path posterior by sampling new poses. The landmark position estimation and update is implemented through extended Kalman filter (EKF). Monocular vision mounted on the robot tracks the 3D natural point landmarks, which are structured with matching scale invariant feature transform (SIFT) feature pairs. The matching for multi-dimension SIFT features is implemented with a KD-tree in the time cost of O(lbN). Experiment results on Pioneer mobile robot in a real indoor environment show the superior performance of our proposed method.

  20. Surgical outcome in monocular elevation deficit: A retrospective interventional study

    Directory of Open Access Journals (Sweden)

    Bandyopadhyay Rakhi

    2008-01-01

    Full Text Available Background and Aim: Monocular elevation deficiency (MED is characterized by a unilateral defect in elevation, caused by paretic, restrictive or combined etiology. Treatment of this multifactorial entity is therefore varied. In this study, we performed different surgical procedures in patients of MED and evaluated their outcome, based on ocular alignment, improvement in elevation and binocular functions. Study Design: Retrospective interventional study. Materials and Methods: Twenty-eight patients were included in this study, from June 2003 to August 2006. Five patients underwent Knapp procedure, with or without horizontal squint surgery, 17 patients had inferior rectus recession, with or without horizontal squint surgery, three patients had combined inferior rectus recession and Knapp procedure and three patients had inferior rectus recession combined with contralateral superior rectus or inferior oblique surgery. The choice of procedure was based on the results of forced duction test (FDT. Results: Forced duction test was positive in 23 cases (82%. Twenty-four of 28 patients (86% were aligned to within 10 prism diopters. Elevation improved in 10 patients (36% from no elevation above primary position (-4 to only slight limitation of elevation (-1. Five patients had preoperative binocular vision and none gained it postoperatively. No significant postoperative complications or duction abnormalities were observed during the follow-up period. Conclusion: Management of MED depends upon selection of the correct surgical technique based on employing the results of FDT, for a satisfactory outcome.

  1. Endonasal endoscopic transsphenoidal chiasmapexy using a clival cranial base cranioplasty for visual loss from massive empty sella following macroprolactinoma treatment with bromocriptine: case report.

    Science.gov (United States)

    Alvarez Berastegui, G Rene; Raza, Shaan M; Anand, Vijay K; Schwartz, Theodore H

    2016-04-01

    Visual deterioration after dopamine-agonist treatment of prolactinomas associated with empty sella syndrome and secondary optic apparatus traction is a rare event. Chiasmapexy has been described as a viable treatment option, although few cases exist in the literature. Here, a novel endonasal endoscopic approach to chiasmapexy is described and its efficacy is demonstrated in a case report. A 55-year-old female patient with a history of a giant prolactinoma and 14 years of treatment using dopaminergic agonist therapy presented to our institution with a 1-month history of visual changes. Neuroophthalmological examination confirmed severe bitemporal field defects, and MRI revealed a large empty sella with downward optic chiasmal herniation. Endoscopic endonasal chiasmapexy was performed by elevating the chiasm with lumbar drainage and filling the clival and sellar defect with an extradural liquid (HydroSet; a cranioplasty bone cement), and a piece of AlloDerm was used to cover and cushion the chiasm. Postoperative imaging demonstrated successful anatomical elevation of the optic apparatus, and the patient showed functional improvement in the visual field at 3 months postoperatively. Although rare, massive empty sellar and chiasmal descent from macroadenoma treatment can result in progressive visual loss. Here, a novel technique of endonasal endoscopic extradural cranioplasty aided by lumbar drainage is reported, which appears to be an effective technique for stabilizing and possibly reversing anatomical and visual deterioration.

  2. 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.

  3. 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

  4. The precision of binocular and monocular depth judgments in natural settings.

    Science.gov (United States)

    McKee, Suzanne P; Taylor, Douglas G

    2010-08-01

    We measured binocular and monocular depth thresholds for objects presented in a real environment. Observers judged the depth separating a pair of metal rods presented either in relative isolation, or surrounded by other objects, including a textured surface. In the isolated setting, binocular thresholds were greatly superior to the monocular thresholds by as much as a factor of 18. The presence of adjacent objects and textures improved the monocular thresholds somewhat, but the superiority of binocular viewing remained substantial (roughly a factor of 10). To determine whether motion parallax would improve monocular sensitivity for the textured setting, we asked observers to move their heads laterally, so that the viewing eye was displaced by 8-10 cm; this motion produced little improvement in the monocular thresholds. We also compared disparity thresholds measured with the real rods to thresholds measured with virtual images in a standard mirror stereoscope. Surprisingly, for the two naive observers, the stereoscope thresholds were far worse than the thresholds for the real rods-a finding that indicates that stereoscope measurements for unpracticed observers should be treated with caution. With practice, the stereoscope thresholds for one observer improved to almost the precision of the thresholds for the real rods.

  5. 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.

  6. Monocular distance estimation with optical flow maneuvers and efference copies: a stability-based strategy.

    Science.gov (United States)

    de Croon, Guido C H E

    2016-01-07

    The visual cue of optical flow plays an important role in the navigation of flying insects, and is increasingly studied for use by small flying robots as well. A major problem is that successful optical flow control seems to require distance estimates, while optical flow is known to provide only the ratio of velocity to distance. In this article, a novel, stability-based strategy is proposed for monocular distance estimation, relying on optical flow maneuvers and knowledge of the control inputs (efference copies). It is shown analytically that given a fixed control gain, the stability of a constant divergence control loop only depends on the distance to the approached surface. At close distances, the control loop starts to exhibit self-induced oscillations. The robot can detect these oscillations and hence be aware of the distance to the surface. The proposed stability-based strategy for estimating distances has two main attractive characteristics. First, self-induced oscillations can be detected robustly by the robot and are hardly influenced by wind. Second, the distance can be estimated during a zero divergence maneuver, i.e., around hover. The stability-based strategy is implemented and tested both in simulation and on board a Parrot AR drone 2.0. It is shown that the strategy can be used to: (1) trigger a final approach response during a constant divergence landing with fixed gain, (2) estimate the distance in hover, and (3) estimate distances during an entire landing if the robot uses adaptive gain control to continuously stay on the 'edge of oscillation.'

  7. Refractive error and monocular viewing strengthen the hollow-face illusion.

    Science.gov (United States)

    Hill, Harold; Palmisano, Stephen; Matthews, Harold

    2012-01-01

    We measured the strength of the hollow-face illusion--the 'flipping distance' at which perception changes between convex and concave--as a function of a lens-induced 3 dioptre refractive error and monocular/binocular viewing. Refractive error and closing one eye both strengthened the illusion to approximately the same extent. The illusion was weakest viewed binocularly without refractive error and strongest viewed monocularly with it. This suggests binocular cues disambiguate the illusion at greater distances than monocular cues, but that both are disrupted by refractive error. We argue that refractive error leaves the ambiguous low-spatial-frequency shading information critical to the illusion largely unaffected while disrupting other, potentially disambiguating, depth/distance cues.

  8. A new combination of monocular and stereo cues for dense disparity estimation

    Science.gov (United States)

    Mao, Miao; Qin, Kaihuai

    2013-07-01

    Disparity estimation is a popular and important topic in computer vision and robotics. Stereo vision is commonly done to complete the task, but most existing methods fail in textureless regions and utilize numerical methods to interpolate into these regions. Monocular features are usually ignored, which may contain helpful depth information. We proposed a novel method combining monocular and stereo cues to compute dense disparities from a pair of images. The whole image regions are categorized into reliable regions (textured and unoccluded) and unreliable regions (textureless or occluded). Stable and accurate disparities can be gained at reliable regions. Then for unreliable regions, we utilize k-means to find the most similar reliable regions in terms of monocular cues. Our method is simple and effective. Experiments show that our method can generate a more accurate disparity map than existing methods from images with large textureless regions, e.g. snow, icebergs.

  9. A perda da visão: estratégias de prevenção Visual loss: prevention strategies

    Directory of Open Access Journals (Sweden)

    Edméa Rita Temporini

    2004-08-01

    Full Text Available INTRODUÇÃO: A perda visual representa conseqüências adversas para o indivíduo e sociedade. O aumento da população mundial, com proporção maior de idosos, acarreta aumento de indivíduos com perda visual. A identificação e tratamento precoces de distúrbios oculares na infância constituem prioridades de programas de prevenção da cegueira. Medidas preventivas para doenças oculares devem ser planejadas e estabelecidas. COMENTÁRIOS: Apresentam-se estimativas referentes à prevalência da cegueira e de baixa visão realizadas pela Organização Mundial de Saúde. Discutem-se aspectos relacionados à problemática e estratégias com vistas ao planejamento de programas preventivos. Ressalta-se a necessidade de realizar pesquisas epidemiológicas e operacionais para conhecimento da realidade, formação de recursos humanos e aperfeiçoamento da infra-estrutura de serviços especializados. Destaca-se a importância de identificar fatores psicossocioculturais para direcionar tais intervenções.INTRODUCTION: Visual loss represents an adversity for the affected person and society as a whole. As the world's population increases and as a greater proportion survives into late adulthood, the number of people with visual loss will inexorably rise. The control of blindness in children is a priority within any blindness prevention programme. Preventive measures have to be planned and established. COMMENTS: The World Health Organization estimates on blindness and low vision are discussed and some strategies and planning of preventive programs are pointed out. Epidemiological and operational researches would contribute to health system needs, assessment and program management. Identifying social and cultural factors would better direct interventional efforts of blindness prevention.

  10. Living with vision loss

    Science.gov (United States)

    Diabetes - vision loss; Retinopathy - vision loss; Low vision; Blindness - vision loss ... Low vision is a visual disability. Wearing regular glasses or contacts does not help. People with low vision have ...

  11. Induction of Monocular Stereopsis by Altering Focus Distance: A Test of Ames's Hypothesis.

    Science.gov (United States)

    Vishwanath, Dhanraj

    2016-03-01

    Viewing a real three-dimensional scene or a stereoscopic image with both eyes generates a vivid phenomenal impression of depth known as stereopsis. Numerous reports have highlighted the fact that an impression of stereopsis can be induced in the absence of binocular disparity. A method claimed by Ames (1925) involved altering accommodative (focus) distance while monocularly viewing a picture. This claim was tested on naïve observers using a method inspired by the observations of Gogel and Ogle on the equidistance tendency. Consistent with Ames's claim, most observers reported that the focus manipulation induced an impression of stereopsis comparable to that obtained by monocular-aperture viewing.

  12. Elimination of aniseikonia in monocular aphakia with a contact lens-spectacle combination.

    Science.gov (United States)

    Schechter, R J

    1978-01-01

    Correction of monocular aphakia with contact lenses generally results in aniseikonia in the range of 7--9%; with correction by intraocular lenses, aniseikonia is approximately 2%. We present a new method of correcting aniseikonia in monocular aphakics using a contact lens-spectacle combination. A formula is derived wherein the contact lens is deliberately overcorrected; this overcorrection is then neutralized by the appropriate spectacle lens, to be worn over the contact lens. Calculated results with this system over a wide range of possible situations consistently results in an aniseikonia of 0.1%.

  13. END-TO-END DEPTH FROM MOTION WITH STABILIZED MONOCULAR VIDEOS

    Directory of Open Access Journals (Sweden)

    C. Pinard

    2017-08-01

    Full Text Available We propose a depth map inference system from monocular videos based on a novel dataset for navigation that mimics aerial footage from gimbal stabilized monocular camera in rigid scenes. Unlike most navigation datasets, the lack of rotation implies an easier structure from motion problem which can be leveraged for different kinds of tasks such as depth inference and obstacle avoidance. We also propose an architecture for end-to-end depth inference with a fully convolutional network. Results show that although tied to camera inner parameters, the problem is locally solvable and leads to good quality depth prediction.

  14. Development of monocular and binocular multi-focus 3D display systems using LEDs

    Science.gov (United States)

    Kim, Sung-Kyu; Kim, Dong-Wook; Son, Jung-Young; Kwon, Yong-Moo

    2008-04-01

    Multi-focus 3D display systems are developed and a possibility about satisfaction of eye accommodation is tested. The multi-focus means the ability of monocular depth cue to various depth levels. By achieving the multi-focus function, we developed 3D display systems for one eye and both eyes, which can satisfy accommodation to displayed virtual objects within defined depth. The monocular accommodation and the binocular convergence 3D effect of the system are tested and a proof of the satisfaction of the accommodation and experimental result of the binocular 3D fusion are given as results by using the proposed 3D display systems.

  15. Visualization analysis of research frontiers and trends in nerve regeneration and osseoperception in the repair of tooth loss.

    Science.gov (United States)

    Zhang, Xiaoge; Tang, Tian; Zhao, Zhihe; Zheng, Leilei; Ding, Yin

    2014-11-15

    This study analyzed 85 articles indexed by the Web of Science concerning nerve regeneration and osseoperception during tooth loss repair. Using the Web of Science database and Citespace III software, a document co-citation network map was drawn by document co-citation analysis and word frequency analysis methods. Combined with emergent node secondary literature retrieval, subject headings with apparent changing word frequency trends were retrieved so as to identify research frontiers and development trends. Research frontiers and hotspots for neuronal calcium sensor protein were quantitatively explored to forecast future research developments in nerve regeneration and osseoperception during repair of tooth loss.

  16. Visualization analysis of research frontiers and trends in nerve regeneration and osseoperception in the repair of tooth loss

    Institute of Scientific and Technical Information of China (English)

    Xiaoge Zhang; Tian Tang; Zhihe Zhao; Leilei Zheng; Yin Ding

    2014-01-01

    This study analyzed 85 articles indexed by the Web of Science concerning nerve regeneration and osseoperception during tooth loss repair. Using the Web of Science database and Citespace III software, a document co-citation network map was drawn by document co-citation analysis and word frequency analysis methods. Combined with emergent node secondary literature retrieval, subject headings with apparent changing word frequency trends were retrieved so as to identify research frontiers and development trends. Research frontiers and hotspots for neuronal calcium sensor protein were quantitatively explored to forecast future research developments in nerve regeneration and osseoperception during repair of tooth loss.

  17. Objective assessment of topical anti-inflammatory drug activity on experimentally induced nickel contact dermatitis: comparison between visual scoring, colorimetry, laser Doppler velocimetry and transepidermal water loss.

    Science.gov (United States)

    Queille-Roussel, C; Duteil, L; Padilla, J M; Poncet, M; Czernielewski, J

    1990-01-01

    Four topical anti-inflammatory drugs were investigated for their effect on allergic contact dermatitis. Nickel dermatitis was chosen for its high incidence in European healthy volunteers. Experimental lesions were treated twice daily with two steroids, two non-steroidal anti-inflammatory drugs and a blank base for 4.5 days without occlusion. The influence of treatments was assessed by daily visual grading and one site was left untreated for comparison over the same period. To quantify drug activities objectively, skin colour (colorimetry), skin blood flow (laser Doppler velocimetry) and transepidermal water loss (evaporimetry) were measured before drugs were first applied, then 6 hr after the last application. As expected, only Dermoval cream significantly improved the spontaneous clinical evolution in comparison with the other creams (Hydrocortisone Aster à 1%. Parfenac, indomethacin 2.5% and Skinbase) and the untreated site. Colorimetric parameter a* (redness) and L* (luminance) showed more differences between treatments than the other criteria and a close relationship was obtained between these two parameters and skin blood flow, all three being highly correlated to visual grading. Transepidermal water loss appeared less related to clinical improvement but this parameter could prove helpful for detecting compounds which could be irritant to diseased skin.

  18. 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.

  19. Stochastically optimized monocular vision-based navigation and guidance

    Science.gov (United States)

    Watanabe, Yoko

    The objective of this thesis is to design a relative navigation and guidance law for unmanned aerial vehicles, or UAVs, for vision-based control applications. The autonomous operation of UAVs has progressively developed in recent years. In particular, vision-based navigation, guidance and control has been one of the most focused on research topics for the automation of UAVs. This is because in nature, birds and insects use vision as the exclusive sensor for object detection and navigation. Furthermore, it is efficient to use a vision sensor since it is compact, light-weight and low cost. Therefore, this thesis studies the monocular vision-based navigation and guidance of UAVs. Since 2-D vision-based measurements are nonlinear with respect to the 3-D relative states, an extended Kalman filter (EKF) is applied in the navigation system design. The EKF-based navigation system is integrated with a real-time image processing algorithm and is tested in simulations and flight tests. The first closed-loop vision-based formation flight between two UAVs has been achieved, and the results are shown in this thesis to verify the estimation performance of the EKF. In addition, vision-based 3-D terrain recovery was performed in simulations to present a navigation design which has the capability of estimating states of multiple objects. In this problem, the statistical z-test is applied to solve the correspondence problem of relating measurements and estimation states. As a practical example of vision-based control applications for UAVs, a vision-based obstacle avoidance problem is specially addressed in this thesis. A navigation and guidance system is designed for a UAV to achieve a mission of waypoint tracking while avoiding unforeseen stationary obstacles by using vision information. An EKF is applied to estimate each obstacles' position from the vision-based information. A collision criteria is established by using a collision-cone approach and a time-to-go criterion. A minimum

  20. Combined Intracorneal and Subconjunctival Bevacizumab Injections for Recurrent Visual Loss and Intraocular Hemorrhage from Vascularized Fibrous Downgrowth

    Directory of Open Access Journals (Sweden)

    Ahmad M. Mansour

    2014-01-01

    Full Text Available Background: Epithelial and fibrous downgrowths result from persistently leaky wounds with conjunctival or corneal epithelium and fibroblasts growing over corneal endothelium, iris and angle structures, leading to corneal edema and difficult-to-control glaucoma. Therapies have included en bloc resection, cryotherapy, endolaser or external photocoagulation and either 5-fluorouracil or mitomycin C injections. A new complication and a novel therapy are presented. Case Presentation: A 44-year-old uniocular housewife sustained a large corneoscleral laceration following a fall. She underwent primary suturing and was subsequently referred for repair of retinal detachment. She underwent resuturing of her gaping wound, pars plana vitrectomy and scleral buckle. Postoperative visual acuity was 6/120 due to a large macular hole. Visual acuity dropped to hand motion 5 times in a recurrent fashion due to diffuse intraocular hemorrhage. Vascularized fibrous downgrowth was the identifiable source of bleeding into the anterior and posterior chambers. This was controlled by 21 intracorneal and subconjunctival bevacizumab injections over 2.5 years of therapy. Conclusion: Repeated bevacizumab injections can control intraocular bleeding from new vessels accompanying fibrous downgrowth with preservation of vision.

  1. 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…

  2. 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…

  3. 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.

  4. Dendritic pathology and spinal loss in the visual cortex in Alzheimer's disease: a Golgi study in pathology.

    Science.gov (United States)

    Mavroudis, Ioannis A; Fotiou, Dimitrios F; Manani, Marina G; Njaou, Samuel N; Frangou, Domna; Costa, Vasiliki G; Baloyannis, Stavros J

    2011-07-01

    Alzheimer's disease is a neurodegenerative disorder characterized by progressive decline in memory, loss of professional skills, impairment of judgement and behavior, and decline in social performances. In terms of neuropathology, the morphological hallmarks of the disease are the accumulation of alpha-beta peptide and the neurofibrillary degeneration, associated with synaptic alterations, involving mostly the dendritic spines. This study is based on the morphological analysis of 10 brains, 5 of which were obtained from patients who suffered from Alzheimer's disease and 5 from nondemented senile individuals used as control group. The segments taken in major from the occipital lobe were studied with the use of Golgi method, as well as Gallyas' and Bielschowski' s staining methods. In most of the pyramidal cells in the affected brains, there seems to be important spine loss and extensive dendrite pathology. Apical dendrites are distorted and tortuous. Horizontal dendritic arborization is severely decreased leading to an amputated, bell-shaped cell soma. Senile plaques have been often revealed, and neurofibrillary changes have also been noticed.

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

    DEFF Research Database (Denmark)

    Fledelius, Hans C

    2009-01-01

    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 disorde...

  6. Loss of visual evoked potential following temporary occlusion of the superior hypophyseal artery during aneurysm clip placement surgery. Case report.

    Science.gov (United States)

    Goto, Tetsuya; Tanaka, Yuichiro; Kodama, Kunihiko; Kusano, Yoshikazu; Sakai, Keiichi; Hongo, Kazuhiro

    2007-10-01

    The authors report a case in which a 62-year-old woman with a history of subarachnoid hemorrhage due to a ruptured aneurysm was found to have a de novo paraclinoid aneurysm in the right internal carotid artery during a routine medical examination. Surgical clip placement was performed via a contralateral pterional approach under visual evoked potential (VEP) monitoring. The superior hypophyseal artery (SHA) was found to originate from the aneurysm body. The artery was temporarily occluded prior to application of the clip to the aneurysm neck. The VEP signal was lost 3 minutes after the SHA was occluded, and the potentials gradually recovered 10 minutes after the artery was released. The disappearance of VEP signal was reproducible with SHA occlusion. The clip was applied to the aneurysm body to preserve the origin of the SHA. The patient did not have any deterioration of vision after surgery. Intraoperative VEP monitoring can be used to help determine whether the SHA can be sacrificed safely.

  7. 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.

  8. Evidence against an X-linked locus close to DXS7 determining visual loss susceptibility in British and Italian families with Leber hereditary optic neuropathy

    Energy Technology Data Exchange (ETDEWEB)

    Sweeney, M.G.; Davis, M.B.; Lashwood, A.; Brockington, M.; Harding, A.E. (Institute of Neurology, Queen Square, London (United Kingdom)); Toscano, A. (Clinica Neurologica, Messina (Italy))

    1992-10-01

    Leber hereditary optic neuropathy (LHON) is associated with mutations of mtDNA, but two features of LHON pedigrees are not explicable solely on the basis of mitochondrial inheritance. There is a large excess of affected males, and not all males at risk develop the disease. These observations could be explained by the existence of an X-linked visual loss susceptibility gene. This hypothesis was supported by linkage studies in Finland, placing the susceptibility locus at DXS7, with a maximum lod score of 2.48 at a recombination fraction of 0. Linkage studies in 1 Italian and 12 British families with LHON, analyzed either together or separately depending on the associated mtDNA mutation, have excluded the presence of such a locus from an interval of about 30 cM around DXS7 in these kindreds, with a total lod score of -26.51 at a recombination fraction of 0. 17 refs., 2 figs., 1 tab.

  9. Retinal lesions induce fast intrinsic cortical plasticity in adult mouse visual system.

    Science.gov (United States)

    Smolders, Katrien; Vreysen, Samme; Laramée, Marie-Eve; Cuyvers, Annemie; Hu, Tjing-Tjing; Van Brussel, Leen; Eysel, Ulf T; Nys, Julie; Arckens, Lutgarde

    2016-09-01

    Neuronal activity plays an important role in the development and structural-functional maintenance of the brain as well as in its life-long plastic response to changes in sensory stimulation. We characterized the impact of unilateral 15° laser lesions in the temporal lower visual field of the retina, on visually driven neuronal activity in the afferent visual pathway of adult mice using in situ hybridization for the activity reporter gene zif268. In the first days post-lesion, we detected a discrete zone of reduced zif268 expression in the contralateral hemisphere, spanning the border between the monocular segment of the primary visual cortex (V1) with extrastriate visual area V2M. We could not detect a clear lesion projection zone (LPZ) in areas lateral to V1 whereas medial to V2M, agranular and granular retrosplenial cortex showed decreased zif268 levels over their full extent. All affected areas displayed a return to normal zif268 levels, and this was faster in higher order visual areas than in V1. The lesion did, however, induce a permanent LPZ in the retinorecipient layers of the superior colliculus. We identified a retinotopy-based intrinsic capacity of adult mouse visual cortex to recover from restricted vision loss, with recovery speed reflecting the areal cortical magnification factor. Our observations predict incomplete visual field representations for areas lateral to V1 vs. lack of retinotopic organization for areas medial to V2M. The validation of this mouse model paves the way for future interrogations of cortical region- and cell-type-specific contributions to functional recovery, up to microcircuit level.

  10. Visualization of inner ear dysplasias in patients with sensorineural hearing loss. High-resolution MR imaging and volume-rendered reconstructions

    Energy Technology Data Exchange (ETDEWEB)

    Klingebiel, R.; Bockmuehl, U. [Charite CM, Humboldt Univ., Berlin (Germany). Dept. of Radiology; Werbs, M. [Charite CM, Humboldt Univ., Berlin (Germany). ENT Dept.; Freigang, B. [O. von Guericke Univ., Magdeburg (Germany). ENT Dept.; Vorwerk, W. [St. Salvator Krankenhaus, Halberstadt (Germany). ENT Dept.; Thieme, N.; Lehmann, R. [Charite CM, Humboldt Univ., Berlin (Germany). Dept. of Radiology

    2001-11-01

    Purpose: We evaluated a data acquisition and post-processing protocol for inner ear (IE) assessment by MR imaging in patients, suffering from various labyrinth malformations. Material and Methods: MR IE studies of 158 consecutive patients (316 IEs) suffering from sensorineural hearing loss without evidence of an acoustic neurinoma were reviewed for pathologies of the IE and internal acoustic meatus. High-resolution MR data of all abnormal IE studies (n=45) were post-processed to previously standardized 3D volume rendered (VR) reconstructions. Results: In 9 patients (5.7%) the following IE dysplasias were detected: malformation of the cochlea (6 IEs), vestibulum (4 IEs), semicircular canals (12 IEs) and vestibular aqueduct/endolymphatic sac (10 IEs). One patient showed evidence of an aplasia of the vestibulocochlear nerve. In 4 patients multiple IE dysplasias were encountered. Comprehensive 3D visualization of all labyrinthine dysplasias was achieved by the use of two VR reconstructions. The overall time for bilateral IE assessment amounted to 30-35 min. Conclusion: The imaging protocol allows for rapid and comprehensive visualization of various IE dysplasias, based on a limited number of VR reconstructions.

  11. Cataract surgery: emotional reactions of patients with monocular versus binocular vision Cirurgia de catarata: aspectos emocionais de pacientes com visão monocular versus binocular

    Directory of Open Access Journals (Sweden)

    Roberta Ferrari Marback

    2012-12-01

    Full Text Available PURPOSE: To analyze emotional reactions related to cataract surgery in two groups of patients (monocular vision - Group 1; binocular vision - Group 2. METHODS: A transversal comparative study was performed using a structured questionnaire from a previous exploratory study before cataract surgery. RESULTS: 206 patients were enrolled in the study, 96 individuals in Group 1 (69.3 ± 10.4 years and 110 in Group 2 (68.2 ± 10.2 years. Most patients in group 1 (40.6% and 22.7% of group 2, reported fear of surgery (pOBJETIVO: Verificar reações emocionais relacionadas à cirurgia de catarata entre pacientes com visão monocular (Grupo 1 e binocular (Grupo 2. MÉTODOS: Foi realizado um estudo tranversal, comparativo por meio de um questionário estruturado respondido por pacientes antes da cirurgia de catarata. RESULTADOS: A amostra foi composta de 96 pacientes no Grupo 1 (69.3 ± 10.4 anos e 110 no Grupo 2 (68.2 ± 10.2 anos. Consideravam apresentar medo da cirugia 40.6% do Grupo 1 e 22.7% do Grupo 2 (p<0.001 e entre as principais causas do medo, a possibilidade de perda da visão, complicações cirúrgicas e a morte durante o procedimento foram apontadas. Os sentimentos mais comuns entre os dois grupos foram dúvidas a cerca dos resultados da cirurgia e o nervosismo diante do procedimento. CONCLUSÃO: Pacientes com visão monocular apresentaram mais medo e dúvidas relacionadas à cirurgia de catarata comparados com aqueles com visão binocular. Portanto, é necessário que os médicos considerem estas reações emocionais e invistam mais tempo para esclarecer os riscos e benefícios da cirurgia de catarata.

  12. Cirurgia monocular para esotropias de grande ângulo: histórico e novos paradigmas Monocular surgery for large-angle esotropias: review and new paradigms

    Directory of Open Access Journals (Sweden)

    Edmilson Gigante

    2010-08-01

    Full Text Available As primitivas cirurgias de estrabismo, as miotomias e as tenotomias, eram feitas, simplesmente, seccionando-se o músculo ou o seu tendão, sem nenhuma sutura. Estas cirurgias eram feitas, geralmente, em um só olho, tanto em pequenos como em grandes desvios e os resultados eram pouco previsíveis. Jameson, em 1922, propôs uma nova técnica cirúrgica, usando suturas e fixando, na esclera, o músculo seccionado, tornando a cirurgia mais previsível. Para as esotropias, praticou recuos de, no máximo, 5 mm para o reto medial, o que se tornou uma regra para os demais cirurgiões que o sucederam, sendo impossível, a partir daí, a correção de esotropias de grande ângulo com cirurgia monocular. Rodriguez-Vásquez, em 1974, superou o parâmetro de 5 mm, propondo amplos recuos dos retos mediais (6 a 9 mm para o tratamento da síndrome de Ciancia, com bons resultados. Os autores revisaram a literatura, ano a ano, objetivando comparar os vários trabalhos e, com isso, concluíram que a cirurgia monocular de recuo-ressecção pode constituir uma opção viável para o tratamento cirúrgico das esotropias de grande ângulo.The primitive strabismus surgeries, myotomies and tenotomies, were performed simply by sectioning the muscle or its tendon without any suture. Such surgeries were usually performed in just one eye both in small and in large angles with not really predictable results. In 1922, Jameson introduced a new surgery technique using sutures and fixing the sectioned muscle to the sclera, increasing surgery predictability. For the esotropias he carried out no more than 5 mm recession of the medial rectus, which became a rule for the surgeons who followed him, which made it impossible from then on to correct largeangle esotropias with a monocular surgery. Rodriguez-Vásquez, in 1974, exceeded the 5 mm parameter by proposing large recessions of the medial recti (6 to 9 mm to treat the Ciancia syndrome with good results. The authors revised the

  13. Evaluación de la reproducibilidad de la retinoscopia dinámica monocular de Merchán

    Directory of Open Access Journals (Sweden)

    Lizbeth Acuña

    2010-08-01

    Full Text Available Objetivo: Evaluar la reproducibilidad de la retinoscopia dinámica monocular y su nivel de acuerdo con la retinoscopia estática binocular y monocular, retinoscopia de Nott y Método Estimado Monocular (MEM. Métodos: Se determinó la reproducibilidad entre los evaluadores y entre los métodos por medio del coeficiente de correlación intraclase (CCI y se establecieron los límites de acuerdo de Bland y Altman. Resultados: Se evaluaron 126 personas entre 5 y 39 años y se encontró una baja reproducibilidad interexaminador de la retinoscopia dinámica monocular en ambos ojos CCI ojo derecho: 0.49 (IC95% 0.36; 0.51; ojo izquierdo 0.51 (IC95% 0.38; 0.59. El límite de acuerdo entre evaluadores fue ±1.25 D. Al evaluar la reproducibilidad entre la retinoscopia dinámica monocular y la estática se observó que la mayor reproducibilidad se obtuvo con la estática binocular y monocular y, en visión próxima, entre el método estimado monocular y la retinoscopia de Nott. Conclusiones: La retinoscopia dinámica monocular no es una prueba reproducible y presenta diferencias clínicas significativas para determinar el estado refractivo, en cuanto a poder dióptrico y tipo de ametropía, por tanto, no se puede considerar dentro de la batería de exámenes aplicados para determinar diagnósticos y correcciones refractivas tanto en la visión lejana como en la visión próxima.

  14. Evaluación de la reproducibilidad de la retinoscopia dinámica monocular de Merchán

    Directory of Open Access Journals (Sweden)

    Lizbeth Acuña

    2009-12-01

    Full Text Available Objetivo: Evaluar la reproducibilidad de la retinoscopia dinámica monocular y su nivel de acuerdo con la retinoscopia estática binocular y monocular, retinoscopia de Nott y Método Estimado Monocular (MEM.Métodos: Se determinó la reproducibilidad entre los evaluadores y entre los métodos por medio del coeficiente de correlación intraclase (CCI y se establecieron los límites de acuerdo de Bland y Altman.Resultados: Se evaluaron 126 personas entre 5 y 39 años y se encontró una baja reproducibilidad interexaminador de la retinoscopia dinámica monocular en ambos ojos CCI ojo derecho: 0.49 (IC95% 0.36; 0.51; ojo izquierdo 0.51 (IC95% 0.38; 0.59. El límite de acuerdo entre evaluadores fue ±1.25 D. Al evaluar la reproducibilidad entre la retinoscopia dinámica monocular y la estática se observó que la mayor reproducibilidad se obtuvo con la estática binocular y monocular y, en visión próxima, entre el método estimado monocular y la retinoscopia de Nott.Conclusiones: La retinoscopia dinámica monocular no es una prueba reproducible y presenta diferencias clínicas significativas para determinar el estado refractivo, en cuanto a poder dióptrico y tipo de ametropía, por tanto, no se puede considerar dentro de la batería de exámenes aplicados para determinar diagnósticos y correcciones refractivas tanto en la visión lejana como en la visión próxima.

  15. A Two-Stage Bayesian Network Method for 3D Human Pose Estimation from Monocular Image Sequences

    Directory of Open Access Journals (Sweden)

    Wang Yuan-Kai

    2010-01-01

    Full Text Available Abstract This paper proposes a novel human motion capture method that locates human body joint position and reconstructs the human pose in 3D space from monocular images. We propose a two-stage framework including 2D and 3D probabilistic graphical models which can solve the occlusion problem for the estimation of human joint positions. The 2D and 3D models adopt directed acyclic structure to avoid error propagation of inference. Image observations corresponding to shape and appearance features of humans are considered as evidence for the inference of 2D joint positions in the 2D model. Both the 2D and 3D models utilize the Expectation Maximization algorithm to learn prior distributions of the models. An annealed Gibbs sampling method is proposed for the two-stage method to inference the maximum posteriori distributions of joint positions. The annealing process can efficiently explore the mode of distributions and find solutions in high-dimensional space. Experiments are conducted on the HumanEva dataset with image sequences of walking motion, which has challenges of occlusion and loss of image observations. Experimental results show that the proposed two-stage approach can efficiently estimate more accurate human poses.

  16. Induction of Monocular Stereopsis by Altering Focus Distance: A Test of Ames’s Hypothesis

    Directory of Open Access Journals (Sweden)

    Dhanraj Vishwanath

    2016-04-01

    Full Text Available Viewing a real three-dimensional scene or a stereoscopic image with both eyes generates a vivid phenomenal impression of depth known as stereopsis. Numerous reports have highlighted the fact that an impression of stereopsis can be induced in the absence of binocular disparity. A method claimed by Ames (1925 involved altering accommodative (focus distance while monocularly viewing a picture. This claim was tested on naïve observers using a method inspired by the observations of Gogel and Ogle on the equidistance tendency. Consistent with Ames’s claim, most observers reported that the focus manipulation induced an impression of stereopsis comparable to that obtained by monocular-aperture viewing.

  17. A monocular vision system based on cooperative targets detection for aircraft pose measurement

    Science.gov (United States)

    Wang, Zhenyu; Wang, Yanyun; Cheng, Wei; Chen, Tao; Zhou, Hui

    2017-08-01

    In this paper, a monocular vision measurement system based on cooperative targets detection is proposed, which can capture the three-dimensional information of objects by recognizing the checkerboard target and calculating of the feature points. The aircraft pose measurement is an important problem for aircraft’s monitoring and control. Monocular vision system has a good performance in the range of meter. This paper proposes an algorithm based on coplanar rectangular feature to determine the unique solution of distance and angle. A continuous frame detection method is presented to solve the problem of corners’ transition caused by symmetry of the targets. Besides, a displacement table test system based on three-dimensional precision and measurement system human-computer interaction software has been built. Experiment result shows that it has a precision of 2mm in the range of 300mm to 1000mm, which can meet the requirement of the position measurement in the aircraft cabin.

  18. Monocular trajectory intersection method for 3D motion measurement of a point target

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    This article proposes a monocular trajectory intersection method,a videometrics measurement with a mature theoretical system to solve the 3D motion parameters of a point target.It determines the target’s motion parameters including its 3D trajectory and velocity by intersecting the parametric trajectory of a motion target and series of sight-rays by which a motion camera observes the target,in contrast with the regular intersection method for 3D measurement by which the sight-rays intersect at one point.The method offers an approach to overcome the technical failure of traditional monocular measurements for the 3D motion of a point target and thus extends the application fields of photogrammetry and computer vision.Wide application is expected in passive observations of motion targets on various mobile beds.

  19. A Novel Ship-Bridge Collision Avoidance System Based on Monocular Computer Vision

    Directory of Open Access Journals (Sweden)

    Yuanzhou Zheng

    2013-06-01

    Full Text Available The study aims to investigate the ship-bridge collision avoidance. A novel system for ship-bridge collision avoidance based on monocular computer vision is proposed in this study. In the new system, the moving ships are firstly captured by the video sequences. Then the detection and tracking of the moving objects have been done to identify the regions in the scene that correspond to the video sequences. Secondly, the quantity description of the dynamic states of the moving objects in the geographical coordinate system, including the location, velocity, orientation, etc, has been calculated based on the monocular vision geometry. Finally, the collision risk is evaluated and consequently the ship manipulation commands are suggested, aiming to avoid the potential collision. Both computer simulation and field experiments have been implemented to validate the proposed system. The analysis results have shown the effectiveness of the proposed system.

  20. Depth measurement using monocular stereo vision system: aspect of spatial discretization

    Science.gov (United States)

    Xu, Zheng; Li, Chengjin; Zhao, Xunjie; Chen, Jiabo

    2010-11-01

    The monocular stereo vision system, consisting of single camera with controllable focal length, can be used in 3D reconstruction. Applying the system for 3D reconstruction, must consider effects caused by digital camera. There are two possible methods to make the monocular stereo vision system. First one the distance between the target object and the camera image plane is constant and lens moves. The second method assumes that the lens position is constant and the image plane moves in respect to the target. In this paper mathematical modeling of two approaches is presented. We focus on iso-disparity surfaces to define the discretization effect on the reconstructed space. These models are implemented and simulated on Matlab. The analysis is used to define application constrains and limitations of these methods. The results can be also used to enhance the accuracy of depth measurement.

  1. Monocular trajectory intersection method for 3D motion measurement of a point target

    Institute of Scientific and Technical Information of China (English)

    YU QiFeng; SHANG Yang; ZHOU Jian; ZHANG XiaoHu; LI LiChun

    2009-01-01

    This article proposes a monocular trajectory intersection method,a videometrics measurement with a mature theoretical system to solve the 3D motion parameters of a point target.It determines the target's motion parameters including its 3D trajectory and velocity by intersecting the parametric trajectory of a motion target and series of sight-rays by which a motion camera observes the target,in contrast with the regular intersection method for 3D measurement by which the sight-rays intersect at one point.The method offers an approach to overcome the technical failure of traditional monocular measurements for the 3D motion of a point target and thus extends the application fields of photogrammetry and computer vision.Wide application is expected in passive observations of motion targets on various mobile beds.

  2. Large-scale monocular FastSLAM2.0 acceleration on an embedded heterogeneous architecture

    Science.gov (United States)

    Abouzahir, Mohamed; Elouardi, Abdelhafid; Bouaziz, Samir; Latif, Rachid; Tajer, Abdelouahed

    2016-12-01

    Simultaneous localization and mapping (SLAM) is widely used in many robotic applications and autonomous navigation. This paper presents a study of FastSLAM2.0 computational complexity based on a monocular vision system. The algorithm is intended to operate with many particles in a large-scale environment. FastSLAM2.0 was partitioned into functional blocks allowing a hardware software matching on a CPU-GPGPU-based SoC architecture. Performances in terms of processing time and localization accuracy were evaluated using a real indoor dataset. Results demonstrate that an optimized and efficient CPU-GPGPU partitioning allows performing accurate localization results and high-speed execution of a monocular FastSLAM2.0-based embedded system operating under real-time constraints.

  3. 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.

  4. Measuring method for the object pose based on monocular vision technology

    Science.gov (United States)

    Sun, Changku; Zhang, Zimiao; Wang, Peng

    2010-11-01

    Position and orientation estimation of the object, which can be widely applied in the fields as robot navigation, surgery, electro-optic aiming system, etc, has an important value. The monocular vision positioning algorithm which is based on the point characteristics is studied and new measurement method is proposed in this paper. First, calculate the approximate coordinates of the five reference points which can be used as the initial value of iteration in the camera coordinate system according to weakp3p; Second, get the exact coordinates of the reference points in the camera coordinate system through iterative calculation with the constraints relationship of the reference points; Finally, get the position and orientation of the object. So the measurement model of monocular vision is constructed. In order to verify the accuracy of measurement model, a plane target using infrared LED as reference points is designed to finish the verification of the measurement method and the corresponding image processing algorithm is studied. And then The monocular vision experimental system is established. Experimental results show that the translational positioning accuracy reaches +/-0.05mm and rotary positioning accuracy reaches +/-0.2o .

  5. Proteolytic regulation of synaptic plasticity in the mouse primary visual cortex: analysis of matrix metalloproteinase 9 deficient mice.

    Science.gov (United States)

    Kelly, Emily A; Russo, Amanda S; Jackson, Cory D; Lamantia, Cassandra E; Majewska, Ania K

    2015-01-01

    The extracellular matrix (ECM) is known to play important roles in regulating neuronal recovery from injury. The ECM can also impact physiological synaptic plasticity, although this process is less well understood. To understand the impact of the ECM on synaptic function and remodeling in vivo, we examined ECM composition and proteolysis in a well-established model of experience-dependent plasticity in the visual cortex. We describe a rapid change in ECM protein composition during Ocular Dominance Plasticity (ODP) in adolescent mice, and a loss of ECM remodeling in mice that lack the extracellular protease, matrix metalloproteinase-9 (MMP9). Loss of MMP9 also attenuated functional ODP following monocular deprivation (MD) and reduced excitatory synapse density and spine density in sensory cortex. While we observed no change in the morphology of existing dendritic spines, spine dynamics were altered, and MMP9 knock-out (KO) mice showed increased turnover of dendritic spines over a period of 2 days. We also analyzed the effects of MMP9 loss on microglia, as these cells are involved in extracellular remodeling and have been recently shown to be important for synaptic plasticity. MMP9 KO mice exhibited very limited changes in microglial morphology. Ultrastructural analysis, however, showed that the extracellular space surrounding microglia was increased, with concomitant increases in microglial inclusions, suggesting possible changes in microglial function in the absence of MMP9. Taken together, our results show that MMP9 contributes to ECM degradation, synaptic dynamics and sensory-evoked plasticity in the mouse visual cortex.

  6. 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…

  7. A Semi-Persistent Adult Ocular Dominance Plasticity in Visual Cortex Is Stabilized by Activated CREB

    Science.gov (United States)

    Barco, Angel; Kandel, Eric R.; Gordon, Barbara; Lickey, Marvin E.; Suzuki, Seigo; Pham, Tony A.; Graham, Sarah J.

    2004-01-01

    The adult cerebral cortex can adapt to environmental change. Using monocular deprivation as a paradigm, we find that rapid experience-dependent plasticity exists even in the mature primary visual cortex. However, adult cortical plasticity differs from developmental plasticity in two important ways. First, the effect of adult, but not juvenile…

  8. 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…

  9. Optimization of Visual Training for Full Recovery from Severe Amblyopia in Adults

    Science.gov (United States)

    Eaton, Nicolette C.; Sheehan, Hanna Marie; Quinlan, Elizabeth M.

    2016-01-01

    The severe amblyopia induced by chronic monocular deprivation is highly resistant to reversal in adulthood. Here we use a rodent model to show that recovery from deprivation amblyopia can be achieved in adults by a two-step sequence, involving enhancement of synaptic plasticity in the visual cortex by dark exposure followed immediately by visual…

  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. Driving with Central Visual Field Loss II: How Scotomas above or below the Preferred Retinal Locus (PRL) Affect Hazard Detection in a Driving Simulator.

    Science.gov (United States)

    Bronstad, P Matthew; Albu, Amanda; Bowers, Alex R; Goldstein, Robert; Peli, Eli

    2015-01-01

    We determined whether binocular central scotomas above or below the preferred retinal locus affect detection of hazards (pedestrians) approaching from the side. Seven participants with central field loss (CFL), and seven age-and sex-matched controls with normal vision (NV), each completed two sessions of 5 test drives (each approximately 10 minutes long) in a driving simulator. Participants pressed the horn when detecting pedestrians that appeared at one of four eccentricities (-14°, -4°, left, 4°, or 14°, right, relative to car heading). Pedestrians walked or ran towards the travel lane on a collision course with the participant's vehicle, thus remaining in the same area of the visual field, assuming participant's steady forward gaze down the travel lane. Detection rates were nearly 100% for all participants. CFL participant reaction times were longer (median 2.27s, 95% CI 2.13 to 2.47) than NVs (median 1.17s, 95%CI 1.10 to 2.13; difference pretinal locus delay reaction times to a greater extent; however, taken together, the results of our studies suggest that any binocular CFL might negatively impact timely hazard detection while driving and should be a consideration when evaluating vision for driving.

  12. Daily mixed visual experience that prevents amblyopia in cats does not always allow the development of good binocular depth perception.

    Science.gov (United States)

    Mitchell, Donald E; Kennie, Jan; Schwarzkopf, D Samuel; Sengpiel, Frank

    2009-05-21

    Kittens reared with mixed daily visual input that consists of episodes of normal (binocular) exposure followed by abnormal (monocular) exposure can develop normal visual acuity in both eyes if the length of the former exposure exceeds a critical amount. However, later studies of the tuning of cells in primary visual cortex of animals reared in this manner revealed that their responses to interocular differences in phase were not reliable suggesting that their binocular depth perception may not be normal. We examined this possibility in 3 kittens reared with mixed daily visual exposure (2 hrs binocular vision followed by 5 hrs monocular exposure) that allowed development of normal visual acuity in both eyes. Measurements made of the threshold differences in depth that could be perceived under monocular and binocular viewing revealed a 10-fold superiority of binocular over monocular depth thresholds in one animal while the depth thresholds of the other two animals were poor and there was no binocular superiority. Thus, there was evidence that only one animal possessed stereopsis while the other two were likely stereoblind. While 2 hrs of daily binocular vision protected against the development of amblyopia, the poor outcome with respect to stereopsis points to the need for additional measures to promote binocular vision.

  13. A model of neural mechanisms in monocular transparent motion perception.

    Science.gov (United States)

    Raudies, Florian; Neumann, Heiko

    2010-01-01

    Transparent motion is perceived when multiple motions are presented in the same part of visual space that move in different directions or with different speeds. Several psychophysical as well as physiological experiments have studied the conditions under which motion transparency occurs. Few computational mechanisms have been proposed that allow to segregate multiple motions. We present a novel neural model which investigates the necessary mechanisms underlying initial motion detection, the required representations for velocity coding, and the integration and segregation of motion stimuli to account for the perception of transparent motion. The model extends a previously developed architecture for neural computations along the dorsal pathway, particularly, in cortical areas V1, MT, and MSTd. It emphasizes the role of feedforward cascade processing and feedback from higher to earlier processing stages for selective feature enhancement and tuning. Our results demonstrate that the model reproduces several key psychophysical findings in perceptual motion transparency using random dot stimuli. Moreover, the model is able to process transparent motion as well as opaque surface motion in real-world sequences of 3-d scenes. As a main thesis, we argue that the perception of transparent motion relies on the representation of multiple velocities at one spatial location; however, this feature is necessary but not sufficient to perceive transparency. It is suggested that the activations simultaneously representing multiple activities are subsequently integrated by separate mechanisms leading to the segregation of different overlapping segments.

  14. Effect of fixation tasks on multifocal visual evoked potentials.

    Science.gov (United States)

    Martins, Alessandra; Klistorner, Alexander; Graham, Stuart; Billson, Frank

    2005-10-01

    This study investigated the effects of cognitive influence on the multifocal visual evoked potential (mVEP) at different levels of eccentricity. Three different foveal fixation conditions were utilized involving varying levels of task complexity. A more complex visual fixation task has been known to suppress peripheral signals in subjective testing. Twenty normal subjects had monocular mVEPs recorded using the AccuMap objective perimeter. This allowed simultaneous stimulation of 58 segments of the visual field to an eccentricity of 24 degrees. The mVEP was recorded using three different fixation conditions in random order. During task 1 the subject passively viewed the central fixation area. For task 2 alternating numbers were displayed within the fixation area; the subject on viewing the number '3' in the central fixation area indicated recognition by pressing a button. Throughout task 3, numbers were displayed as in task 2. The subject had the cognitive task of summating all the numbers. Analysis revealed that the increased attention and concentration demanded by tasks 2 and 3 in comparison with task 1 resulted in significantly enhanced central amplitudes of 9.41% (Mann-Whitney P = 0.0002) and 13.45% (P = 0.0002), respectively. These amplitudes became reduced in the periphery and approached those of task 1, resulting in no significant difference between the three tasks. Latencies demonstrated no significant difference between each task nor at any eccentricity (P > 0.05). As the complexity of each task increased the amount of alpha rhythm was significantly reduced. Our findings indicate that task 1 required a minimal demand of cognition and was associated with the greatest amount of alpha rhythm. It was also the most difficult to perform because of loss of interest. The other two tasks required a greater demand of higher order cognitive skills resulting in significantly enhanced amplitudes centrally and the attenuation of alpha rhythm. Therefore, amplitudes are

  15. 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.

  16. 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...

  17. Learning Depth from Single Monocular Images Using Deep Convolutional Neural Fields.

    Science.gov (United States)

    Liu, Fayao; Shen, Chunhua; Lin, Guosheng; Reid, Ian

    2016-10-01

    In this article, we tackle the problem of depth estimation from single monocular images. Compared with depth estimation using multiple images such as stereo depth perception, depth from monocular images is much more challenging. Prior work typically focuses on exploiting geometric priors or additional sources of information, most using hand-crafted features. Recently, there is mounting evidence that features from deep convolutional neural networks (CNN) set new records for various vision applications. On the other hand, considering the continuous characteristic of the depth values, depth estimation can be naturally formulated as a continuous conditional random field (CRF) learning problem. Therefore, here we present a deep convolutional neural field model for estimating depths from single monocular images, aiming to jointly explore the capacity of deep CNN and continuous CRF. In particular, we propose a deep structured learning scheme which learns the unary and pairwise potentials of continuous CRF in a unified deep CNN framework. We then further propose an equally effective model based on fully convolutional networks and a novel superpixel pooling method, which is about 10 times faster, to speedup the patch-wise convolutions in the deep model. With this more efficient model, we are able to design deeper networks to pursue better performance. Our proposed method can be used for depth estimation of general scenes with no geometric priors nor any extra information injected. In our case, the integral of the partition function can be calculated in a closed form such that we can exactly solve the log-likelihood maximization. Moreover, solving the inference problem for predicting depths of a test image is highly efficient as closed-form solutions exist. Experiments on both indoor and outdoor scene datasets demonstrate that the proposed method outperforms state-of-the-art depth estimation approaches.

  18. Driving with Central Visual Field Loss II: How Scotomas above or below the Preferred Retinal Locus (PRL Affect Hazard Detection in a Driving Simulator.

    Directory of Open Access Journals (Sweden)

    P Matthew Bronstad

    Full Text Available We determined whether binocular central scotomas above or below the preferred retinal locus affect detection of hazards (pedestrians approaching from the side. Seven participants with central field loss (CFL, and seven age-and sex-matched controls with normal vision (NV, each completed two sessions of 5 test drives (each approximately 10 minutes long in a driving simulator. Participants pressed the horn when detecting pedestrians that appeared at one of four eccentricities (-14°, -4°, left, 4°, or 14°, right, relative to car heading. Pedestrians walked or ran towards the travel lane on a collision course with the participant's vehicle, thus remaining in the same area of the visual field, assuming participant's steady forward gaze down the travel lane. Detection rates were nearly 100% for all participants. CFL participant reaction times were longer (median 2.27s, 95% CI 2.13 to 2.47 than NVs (median 1.17s, 95%CI 1.10 to 2.13; difference p<0.01, and CFL participants would have been unable to stop for 21% of pedestrians, compared with 3% for NV, p<0.001. Although the scotomas were not expected to obscure pedestrian hazards, gaze tracking revealed that scotomas did sometimes interfere with detection; late reactions usually occurred when pedestrians were entirely or partially obscured by the scotoma (time obscured correlated with reaction times, r = 0.57, p<0.001. We previously showed that scotomas lateral to the preferred retinal locus delay reaction times to a greater extent; however, taken together, the results of our studies suggest that any binocular CFL might negatively impact timely hazard detection while driving and should be a consideration when evaluating vision for driving.

  19. Neural correlates of monocular and binocular depth cues based on natural images: a LORETA analysis.

    Science.gov (United States)

    Fischmeister, Florian Ph S; Bauer, Herbert

    2006-10-01

    Functional imaging studies investigating perception of depth rely solely on one type of depth cue based on non-natural stimulus material. To overcome these limitations and to provide a more realistic and complete set of depth cues natural stereoscopic images were used in this study. Using slow cortical potentials and source localization we aimed to identify the neural correlates of monocular and binocular depth cues. This study confirms and extends functional imaging studies, showing that natural images provide a good, reliable, and more realistic alternative to artificial stimuli, and demonstrates the possibility to separate the processing of different depth cues.

  20. 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...... solver allows us to perform the filtering in end-effector space. This effectively reduces the dimensionality of the state space while still allowing for the estimation of a large set of motions. Preliminary experiments with the strategy show good results compared to a full-pose tracker....

  1. Effect of ophthalmic filter thickness on predicted monocular dichromatic luminance and chromaticity discrimination.

    Science.gov (United States)

    Richer, S P; Little, A C; Adams, A J

    1984-11-01

    The majority of ophthalmic filters, whether they be in the form of spectacles or contact lenses, are absorbance type filters. Although color vision researchers routinely provide spectrophotometric transmission profiles of filters, filter thickness is rarely specified. In this paper, colorimetric tools and volume color theory are used to show that the color of a filter as well as its physical properties are altered dramatically by changes in thickness. The effect of changes in X-Chrom filter thickness on predicted monocular dichromatic luminance and chromaticity discrimination is presented.

  2. Estimating 3D positions and velocities of projectiles from monocular views.

    Science.gov (United States)

    Ribnick, Evan; Atev, Stefan; Papanikolopoulos, Nikolaos P

    2009-05-01

    In this paper, we consider the problem of localizing a projectile in 3D based on its apparent motion in a stationary monocular view. A thorough theoretical analysis is developed, from which we establish the minimum conditions for the existence of a unique solution. The theoretical results obtained have important implications for applications involving projectile motion. A robust, nonlinear optimization-based formulation is proposed, and the use of a local optimization method is justified by detailed examination of the local convexity structure of the cost function. The potential of this approach is validated by experimental results.

  3. Monocular feature tracker for low-cost stereo vision control of an autonomous guided vehicle (AGV)

    Science.gov (United States)

    Pearson, Chris M.; Probert, Penelope J.

    1994-02-01

    We describe a monocular feature tracker (MFT), the first stage of a low cost stereoscopic vision system for use on an autonomous guided vehicle (AGV) in an indoor environment. The system does not require artificial markings or other beacons, but relies upon accurate knowledge of the AGV motion. Linear array cameras (LAC) are used to reduce the data and processing bandwidths. The limited information given by LAC require modelling of the expected features. We model an obstacle as a vertical line segment touching the floor, and can distinguish between these obstacles and most other clutter in an image sequence. Detection of these obstacles is sufficient information for local AGV navigation.

  4. Infants' ability to respond to depth from the retinal size of human faces: comparing monocular and binocular preferential-looking.

    Science.gov (United States)

    Tsuruhara, Aki; Corrow, Sherryse; Kanazawa, So; Yamaguchi, Masami K; Yonas, Albert

    2014-11-01

    To examine sensitivity to pictorial depth cues in young infants (4 and 5 months-of-age), we compared monocular and binocular preferential looking to a display on which two faces were equidistantly presented and one was larger than the other, depicting depth from the size of human faces. Because human faces vary little in size, the correlation between retinal size and distance can provide depth information. As a result, adults perceive a larger face as closer than a smaller one. Although binocular information for depth provided information that the faces in our display were equidistant, under monocular viewing, no such information was provided. Rather, the size of the faces indicated that one was closer than the other. Infants are known to look longer at apparently closer objects. Therefore, we hypothesized that infants would look longer at a larger face in the monocular than in the binocular condition if they perceived depth from the size of human faces. Because the displays were identical in the two conditions, any difference in looking-behavior between monocular and binocular viewing indicated sensitivity to depth information. Results showed that 5-month-old infants preferred the larger, apparently closer, face in the monocular condition compared to the binocular condition when static displays were presented. In addition, when presented with a dynamic display, 4-month-old infants showed a stronger 'closer' preference in the monocular condition compared to the binocular condition. This was not the case when the faces were inverted. These results suggest that even 4-month-old infants respond to depth information from a depth cue that may require learning, the size of faces. Copyright © 2014 Elsevier Inc. All rights reserved.

  5. Infants’ ability to respond to depth from the retinal size of human faces: Comparing monocular and binocular preferential-looking

    Science.gov (United States)

    Tsuruhara, Aki; Corrow, Sherryse; Kanazawa, So; Yamaguchi, Masami K.; Yonas, Albert

    2014-01-01

    To examine sensitivity to pictorial depth cues in young infants (4 and 5 months-of-age), we compared monocular and binocular preferential looking to a display on which two faces were equidistantly presented and one was larger than the other, depicting depth from the size of human faces. Because human faces vary little in size, the correlation between retinal size and distance can provide depth information. As a result, adults perceive a larger face as closer than a smaller one. Although binocular information for depth provided information that the faces in our display were equidistant, under monocular viewing, no such information was provided. Rather, the size of the faces indicated that one was closer than the other. Infants are known to look longer at apparently closer objects. Therefore, we hypothesized that infants would look longer at a larger face in the monocular than in the binocular condition if they perceived depth from the size of human faces. Because the displays were identical in the two conditions, any difference in looking-behavior between monocular and binocular viewing indicated sensitivity to depth information. Results showed that 5-month-old infants preferred the larger, apparently closer, face in the monocular condition compared to the binocular condition when static displays were presented. In addition, when presented with a dynamic display, 4-month-old infants showed a stronger ‘closer’ preference in the monocular condition compared to the binocular condition. This was not the case when the faces were inverted. These results suggest that even 4-month-old infants respond to depth information from a depth cue that may require learning, the size of faces. PMID:25113916

  6. Visual fields of four batoid fishes: a comparative study.

    Science.gov (United States)

    McComb, D Michelle; Kajiura, Stephen M

    2008-02-01

    The visual fields of elasmobranch fishes are not well characterized even though this is a fundamental element of the visual system. The batoid fishes (skates, rays) form a monophyletic clade within the subclass Elasmobranchii and exhibit a broad range of morphologies and corresponding ecologies. We hypothesized that their visual field characteristics would reflect their diverse morphology and ecology. This was tested by quantifying the monocular, binocular and cyclopean horizontal and vertical visual fields of four batoid species (Raja eglanteria, Urobatis jamaicensis, Dasyatis sabina and Rhinoptera bonasus) that encompassed a range from a basal skate to a more derived ray. The horizontal and vertical visual fields differed significantly among species; however, all species possessed horizontal anterior and dorsal binocular overlaps. Urobatis jamaicensis, a small reef-associated stingray, demonstrated a 360 degrees panoramic visual field in the horizontal plane, and R. bonasus, a schooling benthopelagic ray, a 360 degrees panoramic view in the vertical plane. Large anterior binocular overlaps were measured in D. sabina (72 degrees ) and R. bonasus (46 degrees ) but came at the expense of large posterior blind areas. The anterior binocular overlaps in R. eglanteria (28 degrees ) and U. jamaicensis (34 degrees ) were smaller but were coupled with large monocular fields that provided expansive peripheral views. The most phylogenetically basal species, the clearnose skate (Raja eglanteria), had the most reduced visual field in contrast to the more derived ray species. To our knowledge, this study represents the first comparative assessment of visual fields in basal vertebrates.

  7. Compromises in the visual field with the M43 aviation mask.

    Science.gov (United States)

    Wingert, T A; McAlister, W H; Bachman, W G

    1994-02-01

    This study evaluated peripheral vision through the M43 protective mask currently worn by aviators in the AH-64 Apache helicopter. A Humphrey Visual Field Analyzer was used to measure the sensitivity of a subject's visual field with and without the mask. The results were analyzed using Dicon's Fieldview software. The monocular visual field was reduced for each eye when wearing the mask, especially superiorly and nasally. The overall size of the visual field was not reduced when both eyes were open; however, the quality of the visual field was reduced. The area of binocular vision (central binocular vision fusion field subserving stereopsis) was restricted to the central 30 degrees.

  8. Visual Map Shifts based on Whisker-Guided Cues in the Young Mouse Visual Cortex

    Directory of Open Access Journals (Sweden)

    Kohei Yoshitake

    2013-12-01

    Full Text Available Mice navigate nearby space using their vision and whiskers, and young mice learn to integrate these heterogeneous inputs in perceptual space. We found that cortical responses were depressed in the primary visual cortex of young mice after wearing a monocular prism. This depression was uniformly observed in the primary visual cortex and was eliminated by whisker trimming or lesions in the posterior parietal cortex. Compensatory visual map shifts of responses elicited via the eye that had worn the prism were also observed. As a result, cortical responses elicited via each eye were clearly separated when a visual stimulus was placed in front of the mice. A comparison of response areas before and after prism wearing indicated that the map shifts were produced by depression with spatial eccentricity. Visual map shifts based on whisker-guided cues may serve as a model for investigating the cellular and molecular mechanisms underlying higher sensory integration in the mammalian brain.

  9. 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.

  10. Stereo improves 3D shape discrimination even when rich monocular shape cues are available.

    Science.gov (United States)

    Lee, Young Lim; Saunders, Jeffrey A

    2011-08-17

    We measured the ability to discriminate 3D shapes across changes in viewpoint and illumination based on rich monocular 3D information and tested whether the addition of stereo information improves shape constancy. Stimuli were images of smoothly curved, random 3D objects. Objects were presented in three viewing conditions that provided different 3D information: shading-only, stereo-only, and combined shading and stereo. Observers performed shape discrimination judgments for sequentially presented objects that differed in orientation by rotation of 0°-60° in depth. We found that rotation in depth markedly impaired discrimination performance in all viewing conditions, as evidenced by reduced sensitivity (d') and increased bias toward judging same shapes as different. We also observed a consistent benefit from stereo, both in conditions with and without change in viewpoint. Results were similar for objects with purely Lambertian reflectance and shiny objects with a large specular component. Our results demonstrate that shape perception for random 3D objects is highly viewpoint-dependent and that stereo improves shape discrimination even when rich monocular shape cues are available.

  11. A trajectory and orientation reconstruction method for moving objects based on a moving monocular camera.

    Science.gov (United States)

    Zhou, Jian; Shang, Yang; Zhang, Xiaohu; Yu, Wenxian

    2015-03-09

    We propose a monocular trajectory intersection method to solve the problem that a monocular moving camera cannot be used for three-dimensional reconstruction of a moving object point. The necessary and sufficient condition of when this method has the unique solution is provided. An extended application of the method is to not only achieve the reconstruction of the 3D trajectory, but also to capture the orientation of the moving object, which would not be obtained by PnP problem methods due to lack of features. It is a breakthrough improvement that develops the intersection measurement from the traditional "point intersection" to "trajectory intersection" in videometrics. The trajectory of the object point can be obtained by using only linear equations without any initial value or iteration; the orientation of the object with poor conditions can also be calculated. The required condition for the existence of definite solution of this method is derived from equivalence relations of the orders of the moving trajectory equations of the object, which specifies the applicable conditions of the method. Simulation and experimental results show that it not only applies to objects moving along a straight line, or a conic and another simple trajectory, but also provides good result for more complicated trajectories, making it widely applicable.

  12. Monocular 3D Reconstruction and Augmentation of Elastic Surfaces with Self-Occlusion Handling.

    Science.gov (United States)

    Haouchine, Nazim; Dequidt, Jeremie; Berger, Marie-Odile; Cotin, Stephane

    2015-12-01

    This paper focuses on the 3D shape recovery and augmented reality on elastic objects with self-occlusions handling, using only single view images. Shape recovery from a monocular video sequence is an underconstrained problem and many approaches have been proposed to enforce constraints and resolve the ambiguities. State-of-the art solutions enforce smoothness or geometric constraints, consider specific deformation properties such as inextensibility or resort to shading constraints. However, few of them can handle properly large elastic deformations. We propose in this paper a real-time method that uses a mechanical model and able to handle highly elastic objects. The problem is formulated as an energy minimization problem accounting for a non-linear elastic model constrained by external image points acquired from a monocular camera. This method prevents us from formulating restrictive assumptions and specific constraint terms in the minimization. In addition, we propose to handle self-occluded regions thanks to the ability of mechanical models to provide appropriate predictions of the shape. Our method is compared to existing techniques with experiments conducted on computer-generated and real data that show the effectiveness of recovering and augmenting 3D elastic objects. Additionally, experiments in the context of minimally invasive liver surgery are also provided and results on deformations with the presence of self-occlusions are exposed.

  13. Mobile Target Tracking Based on Hybrid Open-Loop Monocular Vision Motion Control Strategy

    Directory of Open Access Journals (Sweden)

    Cao Yuan

    2015-01-01

    Full Text Available This paper proposes a new real-time target tracking method based on the open-loop monocular vision motion control. It uses the particle filter technique to predict the moving target’s position in an image. Due to the properties of the particle filter, the method can effectively master the motion behaviors of the linear and nonlinear. In addition, the method uses the simple mathematical operation to transfer the image information in the mobile target to its real coordinate information. Therefore, it requires few operating resources. Moreover, the method adopts the monocular vision approach, which is a single camera, to achieve its objective by using few hardware resources. Firstly, the method evaluates the next time’s position and size of the target in an image. Later, the real position of the objective corresponding to the obtained information is predicted. At last, the mobile robot should be controlled in the center of the camera’s vision. The paper conducts the tracking test to the L-type and the S-type and compares with the Kalman filtering method. The experimental results show that the method achieves a better tracking effect in the L-shape experiment, and its effect is superior to the Kalman filter technique in the L-type or S-type tracking experiment.

  14. Cataract surgery: emotional reactions of patients with monocular versus binocular vision

    Directory of Open Access Journals (Sweden)

    Roberta Ferrari Marback

    2012-12-01

    Full Text Available PURPOSE: To analyze emotional reactions related to cataract surgery in two groups of patients (monocular vision - Group 1; binocular vision - Group 2. METHODS: A transversal comparative study was performed using a structured questionnaire from a previous exploratory study before cataract surgery. RESULTS: 206 patients were enrolled in the study, 96 individuals in Group 1 (69.3 ± 10.4 years and 110 in Group 2 (68.2 ± 10.2 years. Most patients in group 1 (40.6% and 22.7% of group 2, reported fear of surgery (p<0.001. The most important causes of fear were: possibility of blindness, ocular complications and death during surgery. The most prevalent feelings among the groups were doubts about good results and nervousness. CONCLUSION: Patients with monocular vision reported more fear and doubts related to surgical outcomes. Thus, it is necessary that phisycians considers such emotional reactions and invest more time than usual explaining the risks and the benefits of cataract surgery.Ouvir

  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. The prevalence of perioperative visual loss in the United States: a 10-year study from 1996 to 2005 of spinal, orthopedic, cardiac, and general surgery.

    Science.gov (United States)

    Shen, Yang; Drum, Melinda; Roth, Steven

    2009-11-01

    Perioperative visual loss (POVL) accompanying nonocular surgery is a rare and potentially devastating complication but its frequency in commonly performed inpatient surgery is not well defined. We used the Nationwide Inpatient Sample to estimate the rate of POVL in the United States among the eight most common nonocular surgeries. More than 5.6 million patients in the Nationwide Inpatient Sample who underwent principal procedures of knee arthroplasty, cholecystectomy, hip/femur surgical treatment, spinal fusion, appendectomy, colorectal resection, laminectomy without fusion, coronary artery bypass grafting, and cardiac valve procedures from 1996 to 2005 were included. Rates of POVL, defined as any discharge with an International Classification of Diseases, Ninth Revision, Clinical Modification code of ischemic optic neuropathy (ION), cortical blindness (CB), or retinal vascular occlusion (RVO), were estimated. Potential risk factors were assessed by univariate and multivariable analyses. Cardiac and spinal fusion surgery had the highest rates of POVL. The national estimate in cardiac surgery was 8.64/10,000 and 3.09/10,000 in spinal fusion. By contrast, POVL after appendectomy was 0.12/10,000. Those undergoing cardiac surgery, spinal fusion, and orthopedic surgery had a significantly increased risk of developing ION, RVO, or CB. Patients younger than 18 yr had the highest risk for POVL, because of higher risk for CB, whereas those older than 50 yr were at greater risk of developing ION and RVO. Other significant positive predictors for some diagnoses of POVL were male gender, Charlson comorbidity index, anemia, and blood transfusion. There was no increased risk associated with hospital surgical volume. During the 10 yr from 1996 to 2005, there was an overall decrease in POVL in the procedures we studied. The results confirm the clinical suspicion that the risk of POVL is higher in cardiac and spine fusion surgery and show for the first time a higher risk of this

  17. Intermittent exotropia: comparative surgical results of lateral recti-recession and monocular recess-resect Exotropia intermitente: comparação dos resultados cirúrgicos entre retrocesso dos retos laterais e retrocesso-ressecção monocular

    Directory of Open Access Journals (Sweden)

    Vanessa Macedo Batista Fiorelli

    2007-06-01

    Full Text Available PURPOSE: To compare the results between recession of the lateral recti and monocular recess-resect procedure for the correction of the basic type of intermittent exotropia. METHODS: 115 patients with intermittent exotropia were submitted to surgery. The patients were divided into 4 groups, according to the magnitude of preoperative deviation and the surgical procedure was subsequently performed. Well compensated orthophoria or exo-or esophoria were considered surgical success, with minimum of 1 year follow-up after the operation. RESULTS: Success was obtained in 69% of the patients submitted to recession of the lateral recti, and in 77% submitted to monocular recess-resect. In the groups with deviations between 12 PD and 25 PD, surgical success was observed in 74% of the patients submitted to recession of the lateral recti and in 78% of the patients submitted to monocular recess-resect. (p=0.564. In the group with deviations between 26 PD and 35 PD, surgical success was observed in 65% out of the patients submitted to recession of the lateral recti and in 75% of the patients submitted to monocular recess-resect. (p=0.266. CONCLUSION: recession of lateral recti and monocular recess-resect were equally effective in correcting basic type intermittent exotropia according to its preoperative deviation in primary position.OBJETIVO: Comparar os resultados entre o retrocesso dos retos laterais e retrocesso-ressecção monocular, para correção de exotropia intermitente do tipo básico. MÉTODOS: Foram selecionados 115 prontuários de pacientes portadores de exotropia intermitente do tipo básico submetidos a cirurgia no período entre janeiro de 1991 e dezembro de 2001. Os planejamentos cirúrgicos seguiram orientação do setor de Motilidade Extrínseca Ocular da Clínica Oftalmológica da Santa Casa de São Paulo e basearam-se na magnitude do desvio na posição primária do olhar. Os pacientes foram divididos em 4 grupos, de acordo com a magnitude

  18. Visual-tracking-based robot vision system

    Science.gov (United States)

    Deng, Keqiang; Wilson, Joseph N.; Ritter, Gerhard X.

    1992-11-01

    There are two kinds of depth perception for robot vision systems: quantitative and qualitative. The first one can be used to reconstruct the visible surfaces numerically while the second to describe the visible surfaces qualitatively. In this paper, we present a qualitative vision system suitable for intelligent robots. The goal of such a system is to perceive depth information qualitatively using monocular 2-D images. We first establish a set of propositions relating depth information, such as 3-D orientation and distance, to the changes of image region caused by camera motion. We then introduce an approximation-based visual tracking system. Given an object, the tracking system tracks its image while moving the camera in a way dependent upon the particular depth property to be perceived. Checking the data generated by the tracking system with our propositions provides us the depth information about the object. The visual tracking system can track image regions in real-time even as implemented on a PC AT clone machine, and mobile robots can naturally provide the inputs to our visual tracking system, therefore, we are able to construct a real-time, cost effective, monocular, qualitative and 3-dimensional robot vision system. To verify our idea, we present examples of perception of planar surface orientation, distance, size, dimensionality and convexity/concavity.

  19. 2D-to-3D conversion by using visual attention analysis

    Science.gov (United States)

    Kim, Jiwon; Baik, Aron; Jung, Yong Ju; Park, Dusik

    2010-02-01

    This paper proposes a novel 2D-to-3D conversion system based on visual attention analysis. The system was able to generate stereoscopic video from monocular video in a robust manner with no human intervention. According to our experiment, visual attention information can be used to provide rich 3D experience even when depth cues from monocular view are not enough. Using the algorithm introduced in the paper, 3D display users can watch 2D media in 3D. In addition, the algorithm can be embedded into 3D displays in order to deliver better viewing experience with more immersive feeling. Using visual attention information to give a 3D effect is first tried in this research as far as we know.

  20. Measuring perceived depth in natural images and study of its relation with monocular and binocular depth cues

    Science.gov (United States)

    Lebreton, Pierre; Raake, Alexander; Barkowsky, Marcus; Le Callet, Patrick

    2014-03-01

    The perception of depth in images and video sequences is based on different depth cues. Studies have considered depth perception threshold as a function of viewing distance (Cutting and Vishton, 1995), the combination of different monocular depth cues and their quantitative relation with binocular depth cues and their different possible type of interactions (Landy, l995). But these studies only consider artificial stimuli and none of them attempts to provide a quantitative contribution of monocular and binocular depth cues compared to each other in the specific context of natural images. This study targets this particular application case. The evaluation of the strength of different depth cues compared to each other using a carefully designed image database to cover as much as possible different combinations of monocular (linear perspective, texture gradient, relative size and defocus blur) and binocular depth cues. The 200 images were evaluated in two distinct subjective experiments to evaluate separately perceived depth and different monocular depth cues. The methodology and the description of the definition of the different scales will be detailed. The image database (DC3Dimg) is also released for the scientific community.

  1. Accurate and Robust Attitude Estimation Using MEMS Gyroscopes and a Monocular Camera

    Science.gov (United States)

    Kobori, Norimasa; Deguchi, Daisuke; Takahashi, Tomokazu; Ide, Ichiro; Murase, Hiroshi

    In order to estimate accurate rotations of mobile robots and vehicle, we propose a hybrid system which combines a low-cost monocular camera with gyro sensors. Gyro sensors have drift errors that accumulate over time. On the other hand, a camera cannot obtain the rotation continuously in the case where feature points cannot be extracted from images, although the accuracy is better than gyro sensors. To solve these problems we propose a method for combining these sensors based on Extended Kalman Filter. The errors of the gyro sensors are corrected by referring to the rotations obtained from the camera. In addition, by using the reliability judgment of camera rotations and devising the state value of the Extended Kalman Filter, even when the rotation is not continuously observable from the camera, the proposed method shows a good performance. Experimental results showed the effectiveness of the proposed method.

  2. Extracting hand articulations from monocular depth images using curvature scale space descriptors

    Institute of Scientific and Technical Information of China (English)

    Shao-fan WANG[1; Chun LI[1; De-hui KONG[1; Bao-cai YIN[2,1,3

    2016-01-01

    We propose a framework of hand articulation detection from a monocular depth image using curvature scale space (CSS) descriptors. We extract the hand contour from an input depth image, and obtain the fingertips and finger-valleys of the contour using the local extrema of a modified CSS map of the contour. Then we recover the undetected fingertips according to the local change of depths of points in the interior of the contour. Compared with traditional appearance-based approaches using either angle detectors or convex hull detectors, the modified CSS descriptor extracts the fingertips and finger-valleys more precisely since it is more robust to noisy or corrupted data; moreover, the local extrema of depths recover the fingertips of bending fingers well while traditional appearance-based approaches hardly work without matching models of hands. Experimental results show that our method captures the hand articulations more precisely compared with three state-of-the-art appearance-based approaches.

  3. Extracting hand articulations from monocular depth images using curvature scale space descriptors

    Institute of Scientific and Technical Information of China (English)

    Shao-fan WANG; Chun LI; De-hui KONG; Bao-cai YIN

    2016-01-01

    We propose a framework of hand articulation detection from a monocular depth image using curvature scale space (CSS) descriptors. We extract the hand contour from an input depth image, and obtain the fingertips and finger-valleys of the contour using the local extrema of a modified CSS map of the contour. Then we recover the undetected fingertips according to the local change of depths of points in the interior of the contour. Compared with traditional appearance-based approaches using either angle detectors or convex hull detectors, the modified CSS descriptor extracts the fingertips and finger-valleys more precisely since it is more robust to noisy or corrupted data;moreover, the local extrema of depths recover the fingertips of bending fingers well while traditional appearance-based approaches hardly work without matching models of hands. Experimental results show that our method captures the hand articulations more precisely compared with three state-of-the-art appearance-based approaches.

  4. Mobile Robot Simultaneous Localization and Mapping Based on a Monocular Camera

    Directory of Open Access Journals (Sweden)

    Songmin Jia

    2016-01-01

    Full Text Available This paper proposes a novel monocular vision-based SLAM (Simultaneous Localization and Mapping algorithm for mobile robot. In this proposed method, the tracking and mapping procedures are split into two separate tasks and performed in parallel threads. In the tracking thread, a ground feature-based pose estimation method is employed to initialize the algorithm for the constraint moving of the mobile robot. And an initial map is built by triangulating the matched features for further tracking procedure. In the mapping thread, an epipolar searching procedure is utilized for finding the matching features. A homography-based outlier rejection method is adopted for rejecting the mismatched features. The indoor experimental results demonstrate that the proposed algorithm has a great performance on map building and verify the feasibility and effectiveness of the proposed algorithm.

  5. The effect of monocular depth cues on the detection of moving objects by moving observers.

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    Royden, Constance S; Parsons, Daniel; Travatello, Joshua

    2016-07-01

    An observer moving through the world must be able to identify and locate moving objects in the scene. In principle, one could accomplish this task by detecting object images moving at a different angle or speed than the images of other items in the optic flow field. While angle of motion provides an unambiguous cue that an object is moving relative to other items in the scene, a difference in speed could be due to a difference in the depth of the objects and thus is an ambiguous cue. We tested whether the addition of information about the distance of objects from the observer, in the form of monocular depth cues, aided detection of moving objects. We found that thresholds for detection of object motion decreased as we increased the number of depth cues available to the observer.

  6. 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.

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

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    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.

  8. Robust Range Estimation with a Monocular Camera for Vision-Based Forward Collision Warning System

    Directory of Open Access Journals (Sweden)

    Ki-Yeong Park

    2014-01-01

    Full Text Available We propose a range estimation method for vision-based forward collision warning systems with a monocular camera. To solve the problem of variation of camera pitch angle due to vehicle motion and road inclination, the proposed method estimates virtual horizon from size and position of vehicles in captured image at run-time. The proposed method provides robust results even when road inclination varies continuously on hilly roads or lane markings are not seen on crowded roads. For experiments, a vision-based forward collision warning system has been implemented and the proposed method is evaluated with video clips recorded in highway and urban traffic environments. Virtual horizons estimated by the proposed method are compared with horizons manually identified, and estimated ranges are compared with measured ranges. Experimental results confirm that the proposed method provides robust results both in highway and in urban traffic environments.

  9. Indoor Mobile Robot Navigation by Central Following Based on Monocular Vision

    Science.gov (United States)

    Saitoh, Takeshi; Tada, Naoya; Konishi, Ryosuke

    This paper develops the indoor mobile robot navigation by center following based on monocular vision. In our method, based on the frontal image, two boundary lines between the wall and baseboard are detected. Then, the appearance based obstacle detection is applied. When the obstacle exists, the avoidance or stop movement is worked according to the size and position of the obstacle, and when the obstacle does not exist, the robot moves at the center of the corridor. We developed the wheelchair based mobile robot. We estimated the accuracy of the boundary line detection, and obtained fast processing speed and high detection accuracy. We demonstrate the effectiveness of our mobile robot by the stopping experiments with various obstacles and moving experiments.

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

    Science.gov (United States)

    Dong, Yanchao; Wang, Yanming; Yue, Jiguang; Hu, Zhencheng

    2016-07-25

    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.

  11. Short-term monocular deprivation strengthens the patched eye's contribution to binocular combination.

    Science.gov (United States)

    Zhou, Jiawei; Clavagnier, Simon; Hess, Robert F

    2013-04-18

    Binocularity is a fundamental property of primate vision. Ocular dominance describes the perceptual weight given to the inputs from the two eyes in their binocular combination. There is a distribution of sensory dominance within the normal binocular population with most subjects having balanced inputs while some are dominated by the left eye and some by the right eye. Using short-term monocular deprivation, the sensory dominance can be modulated as, under these conditions, the patched eye's contribution is strengthened. We address two questions: Is this strengthening a general effect such that it is seen for different types of sensory processing? And is the strengthening specific to pattern deprivation, or does it also occur for light deprivation? Our results show that the strengthening effect is a general finding involving a number of sensory functions, and it occurs as a result of both pattern and light deprivation.

  12. Visual Performance after Bilateral Implantation of a Four-Haptic Diffractive Toric Multifocal Intraocular Lens in High Myopes

    Science.gov (United States)

    Chan, Vincent K. C.

    2016-01-01

    Background. The vision with diffractive toric multifocal intraocular lenses after cataract surgery in long eyes has not been studied previously. Objectives. To report visual performance after bilateral implantation of a diffractive toric multifocal intraocular lens in high myopes. Methods. Prospective, observational case series to include patients with axial length of ≥26 mm and corneal astigmatism of >1 dioptre who underwent bilateral AT LISA 909M implantation. Postoperative examinations included photopic and mesopic distance, intermediate, and near visual acuity; photopic contrast sensitivity; visual symptoms (0–5); satisfaction (1–5); and spectacle independence rate. Results. Twenty-eight eyes (14 patients) were included. Postoperatively, mean photopic monocular uncorrected distance, intermediate, and near visual acuities (logMAR) were 0.12 ± 0.20 (standard deviation), 0.24 ± 0.16, and 0.29 ± 0.21, respectively. Corresponding binocular values were −0.01 ± 0.14, 0.13 ± 0.12, and 0.20 ± 0.19, respectively. One eye (4%) had one-line loss in vision. Under mesopic condition, intermediate vision and near vision decreased significantly (all P ≤ 0.001). Contrast sensitivity at all spatial frequencies did not improve significantly under binocular condition (all P > 0.05). Median scores for halos, night glare, starbursts, and satisfaction were 0.50, 0.00, 0.00, and 4.25, respectively. Ten patients (71%) reported complete spectacle independence. Conclusions. Bilateral implantation of the intraocular lens in high myopes appeared to be safe and achieved good visual performance and high satisfaction. PMID:27563460

  13. Visual Performance after Bilateral Implantation of a Four-Haptic Diffractive Toric Multifocal Intraocular Lens in High Myopes.

    Science.gov (United States)

    Chang, John S M; Chan, Vincent K C; Ng, Jack C M; Law, Antony K P

    2016-01-01

    Background. The vision with diffractive toric multifocal intraocular lenses after cataract surgery in long eyes has not been studied previously. Objectives. To report visual performance after bilateral implantation of a diffractive toric multifocal intraocular lens in high myopes. Methods. Prospective, observational case series to include patients with axial length of ≥26 mm and corneal astigmatism of >1 dioptre who underwent bilateral AT LISA 909M implantation. Postoperative examinations included photopic and mesopic distance, intermediate, and near visual acuity; photopic contrast sensitivity; visual symptoms (0-5); satisfaction (1-5); and spectacle independence rate. Results. Twenty-eight eyes (14 patients) were included. Postoperatively, mean photopic monocular uncorrected distance, intermediate, and near visual acuities (logMAR) were 0.12 ± 0.20 (standard deviation), 0.24 ± 0.16, and 0.29 ± 0.21, respectively. Corresponding binocular values were -0.01 ± 0.14, 0.13 ± 0.12, and 0.20 ± 0.19, respectively. One eye (4%) had one-line loss in vision. Under mesopic condition, intermediate vision and near vision decreased significantly (all P ≤ 0.001). Contrast sensitivity at all spatial frequencies did not improve significantly under binocular condition (all P > 0.05). Median scores for halos, night glare, starbursts, and satisfaction were 0.50, 0.00, 0.00, and 4.25, respectively. Ten patients (71%) reported complete spectacle independence. Conclusions. Bilateral implantation of the intraocular lens in high myopes appeared to be safe and achieved good visual performance and high satisfaction.

  14. Bilateral Visual Loss as Presenting Symptom of Posterior Reversible Encephalopathy Syndrome in a Patient with HIV/Tuberculosis Coinfection: A Case Report

    Directory of Open Access Journals (Sweden)

    S. Guerriero

    2012-01-01

    Full Text Available Posterior reversible encephalopathy syndrome (PRES is a neurotoxic state accompanied by a unique brain imaging pattern. This cliniconeuroradiological entity usually presents with visual disturbances (cortical blindness, homonymous hemianopia, visual neglect, and blurred vision along with neurotoxic manifestations. Only a few cases of PRES have previously been reported in patients with advanced HIV disease. The authors describe a case of posterior reversible encephalopathy syndrome (PRES in a patient with advanced HIV/TBC infection who developed a neurotoxic state following TB and ART therapy initiation. They present a comprehensive review of the literature and discuss the pathogenetic hypotheses.

  15. Monocular discs in the occlusion zones of binocular surfaces do not have quantitative depth--a comparison with Panum's limiting case.

    Science.gov (United States)

    Gillam, Barbara; Cook, Michael; Blackburn, Shane

    2003-01-01

    Da Vinci stereopsis is defined as apparent depth seen in a monocular object laterally adjacent to a binocular surface in a position consistent with its occlusion by the other eye. It is widely regarded as a new form of quantitative stereopsis because the depth seen is quantitatively related to the lateral separation of the monocular element and the binocular surface (Nakayama and Shimojo 1990 Vision Research 30 1811-1825). This can be predicted on the basis that the more separated the monocular element is from the surface the greater its minimum depth behind the surface would have to be to account for its monocular occlusion. Supporting evidence, however, has used narrow bars as the monocular elements, raising the possibility that quantitative depth as a function of separation could be attributable to Panum's limiting case (double fusion) rather than to a new form of stereopsis. We compared the depth performance of monocular objects fusible with the edge of the surface in the contralateral eye (lines) and non-fusible objects (disks) and found that, although the fusible objects showed highly quantitative depth, the disks did not, appearing behind the surface to the same degree at all separations from it. These findings indicate that, although there is a crude sense of depth for discrete monocular objects placed in a valid position for uniocular occlusion, depth is not quantitative. They also indicate that Panum's limiting case is not, as has sometimes been claimed, itself a case of da Vinci stereopsis since fusibility is a critical factor for seeing quantitative depth in discrete monocular objects relative to a binocular surface.

  16. Transposição monocular vertical dos músculos retos horizontais em pacientes esotrópicos portadores de anisotropia em A Monocular vertical displacement of the horizontal rectus muscles in esotropic patients with "A" pattern

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    Ana Carolina Toledo Dias

    2004-10-01

    Full Text Available OBJETIVO: Estudar a eficácia da transposição vertical monocular dos mús-culos retos horizontais, proposta por Goldstein, em pacientes esotrópicos portadores de anisotropia em A, sem hiperfunção de músculos oblíquos. MÉTODOS: Foram analisados, retrospectivamente, 23 prontuários de pacientes esotrópicos portadores de anisotropia em A > 10delta, submetidos a transposição vertical monocular dos músculos retos horizontais. Os pacientes foram divididos em 2 grupos, de acordo com a magnitude da incomitância pré-operatória; grupo 1 era composto de pacientes com desvio entre 11delta e 20delta e grupo 2 entre 21delta e 30delta. Foram considerados co-mo resultados satisfatórios as correções com A PURPOSE: To report the effectiveness of the vertical monocular displacement of the horizontal rectus muscles, proposed by Goldstein, in esotropic patients with A pattern, without oblique muscle overaction. METHODS: A retrospective study was performed using the charts of 23 esotropic patients with A pattern > 10delta, submitted to vertical monocular displacement of the horizontal rectus muscles. The patients were divided into 2 groups in agreement with the magnitude of the preoperative deviation, group 1 (11delta to 20delta and group 2 (21delta to 30delta. Satisfactory results were considered when corrections A < 10delta or V < 15delta were obtained. RESULTS: The average of absolute correction was, in group 1, 16.5delta and, in group 2, 16.6delta. In group 1, 91.6% of the patients presented satisfactory surgical results and in group 2, 81.8% (p = 0.468. CONCLUSION: The surgical procedure, proposed by Goldstein, is effective and there was no statistical difference between the magnitude of the preoperative anisotropia and the obtained correction.

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

    Science.gov (United States)

    Matuzevicius, Dalius; Vaitkevicius, Henrikas

    2014-03-01

    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.

  18. 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

  19. Design of a noninvasive face mask for ocular occlusion in rats and assessment in a visual discrimination paradigm.

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    Hager, Audrey M; Dringenberg, Hans C

    2012-12-01

    The rat visual system is structured such that the large (>90 %) majority of retinal ganglion axons reach the contralateral lateral geniculate nucleus (LGN) and visual cortex (V1). This anatomical design allows for the relatively selective activation of one cerebral hemisphere under monocular viewing conditions. Here, we describe the design of a harness and face mask allowing simple and noninvasive monocular occlusion in rats. The harness is constructed from synthetic fiber (shoelace-type material) and fits around the girth region and neck, allowing for easy adjustments to fit rats of various weights. The face mask consists of soft rubber material that is attached to the harness by Velcro strips. Eyeholes in the mask can be covered by additional Velcro patches to occlude either one or both eyes. Rats readily adapt to wearing the device, allowing behavioral testing under different types of viewing conditions. We show that rats successfully acquire a water-maze-based visual discrimination task under monocular viewing conditions. Following task acquisition, interocular transfer was assessed. Performance with the previously occluded, "untrained" eye was impaired, suggesting that training effects were partially confined to one cerebral hemisphere. The method described herein provides a simple and noninvasive means to restrict visual input for studies of visual processing and learning in various rodent species.

  20. 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.

  1. Perception of scene-relative object movement: Optic flow parsing and the contribution of monocular depth cues.

    Science.gov (United States)

    Warren, Paul A; Rushton, Simon K

    2009-05-01

    We have recently suggested that the brain uses its sensitivity to optic flow in order to parse retinal motion into components arising due to self and object movement (e.g. Rushton, S. K., & Warren, P. A. (2005). Moving observers, 3D relative motion and the detection of object movement. Current Biology, 15, R542-R543). Here, we explore whether stereo disparity is necessary for flow parsing or whether other sources of depth information, which could theoretically constrain flow-field interpretation, are sufficient. Stationary observers viewed large field of view stimuli containing textured cubes, moving in a manner that was consistent with a complex observer movement through a stationary scene. Observers made speeded responses to report the perceived direction of movement of a probe object presented at different depths in the scene. Across conditions we varied the presence or absence of different binocular and monocular cues to depth order. In line with previous studies, results consistent with flow parsing (in terms of both perceived direction and response time) were found in the condition in which motion parallax and stereoscopic disparity were present. Observers were poorer at judging object movement when depth order was specified by parallax alone. However, as more monocular depth cues were added to the stimulus the results approached those found when the scene contained stereoscopic cues. We conclude that both monocular and binocular static depth information contribute to flow parsing. These findings are discussed in the context of potential architectures for a model of the flow parsing mechanism.

  2. Measuring young infants' sensitivity to height-in-the-picture-plane by contrasting monocular and binocular preferential-looking.

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    Tsuruhara, Aki; Corrow, Sherryse; Kanazawa, So; Yamaguchi, Masami K; Yonas, Albert

    2014-01-01

    To examine young infants' sensitivity to a pictorial depth cue, we compared monocular and binocular preferential looking to objects of which depth was specified by height-in-the-picture-plane. For adults, this cue generates the perception that a lower object is closer than a higher object. This study showed that 4- and 5-month-old infants fixated the lower, apparently closer, figure more often under the monocular than binocular presentation providing evidence of their sensitivity to the pictorial depth cue. Because the displays were identical in the two conditions except for binocular information for depth, the difference in looking-behavior indicated sensitivity to depth information, excluding a possibility that they responded to 2D characteristics. This study also confirmed the usefulness of the method, preferential looking with a monocular and binocular comparison, to examine sensitivity to a pictorial depth cue in young infants, who are too immature to reach reliably for the closer of two objects. © 2013 Wiley Periodicals, Inc.

  3. Proteolytic Regulation of Synaptic Plasticity in the Mouse Primary Visual Cortex: Analysis of Matrix Metalloproteinase 9 Deficient Mice.

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    Emily A Kelly

    2015-09-01

    Full Text Available The extracellular matrix (ECM is known to play important roles in regulating neuronal recovery from injury. The ECM can also impact physiological synaptic plasticity, although this process is less well understood. To understand the impact of the ECM on synaptic function and remodeling in vivo, we examined ECM composition and proteolysis in a well-established model of experience-dependent plasticity in the visual cortex. We describe a rapid change in ECM protein composition during ocular dominance plasticity in adolescent mice, and a loss of ECM remodeling in mice that lack the extracellular protease, matrix metalloproteinase-9 (MMP9. Loss of MMP9 also attenuated functional ocular dominance plasticity following monocular deprivation and reduced excitatory synapse density and spine density in sensory cortex. While we observed no change in the morphology of existing dendritic spines, spine dynamics were altered, and MMP9 knock-out (KO mice showed increased turnover of dendritic spines over a period of 2 days. We also analyzed the effects of MMP9 loss on microglia, as these cells are involved in extracellular remodeling and have been recently shown to be important for synaptic plasticity. MMP9 KO mice exhibited very limited changes in microglial morphology. Ultrastructural analysis, however, showed that the extracellular space surrounding microglia was increased, with concomitant increases in microglial inclusions, suggesting possible changes in microglial function in the absence of MMP9. Taken together, our results show that MMP9 contributes to ECM degradation, synaptic dynamics and sensory-evoked plasticity in the mouse visual cortex.

  4. Visual Field Testing with Head-Mounted Perimeter ‘imo’

    Science.gov (United States)

    Matsumoto, Chota; Yamao, Sayaka; Nomoto, Hiroki; Takada, Sonoko; Okuyama, Sachiko; Kimura, Shinji; Yamanaka, Kenzo; Aihara, Makoto; Shimomura, Yoshikazu

    2016-01-01

    Purpose We developed a new portable head-mounted perimeter, “imo”, which performs visual field (VF) testing under flexible conditions without a dark room. Besides the monocular eye test, imo can present a test target randomly to either eye without occlusion (a binocular random single eye test). The performance of imo was evaluated. Methods Using full HD transmissive LCD and high intensity LED backlights, imo can display a test target under the same test conditions as the Humphrey Field Analyzer (HFA). The monocular and binocular random single eye tests by imo and the HFA test were performed on 40 eyes of 20 subjects with glaucoma. VF sensitivity results by the monocular and binocular random single eye tests were compared, and these test results were further compared to those by the HFA. The subjects were asked whether they noticed which eye was being tested during the test. Results The mean sensitivity (MS) obtained with the HFA highly correlated with the MS by the imo monocular test (R: r = 0.96, L: r = 0.94, P < 0.001) and the binocular random single eye test (R: r = 0.97, L: r = 0.98, P < 0.001). The MS values by the monocular and binocular random single eye tests also highly correlated (R: r = 0.96, L: r = 0.95, P < 0.001). No subject could detect which eye was being tested during the examination. Conclusions The perimeter imo can obtain VF sensitivity highly compatible to that by the standard automated perimeter. The binocular random single eye test provides a non-occlusion test condition without the examinee being aware of the tested eye. PMID:27564382

  5. [EXPERIMENTAL TESTING OF THE OPERATOR'S PERCEPTION OF SYMBOLIC INFORMATION ON THE HELMET-MOUNTED DISPLAY DEPENDING ON THE STRUCTURAL COMPLEXITY OF VISUAL ENVIRONMENT].

    Science.gov (United States)

    Lapa, V V; Ivanov, A I; Davydov, V V; Ryabinin, V A; Golosov S Yu

    2015-01-01

    The experiments showed that pilot's perception of symbolic information on the helmet-mounted display (HMD) depends on type of HMD (mono- or binocular), and structural complexity of the background image. Complex background extends time and increases errors in perception, particularly when monocular HMD is used. In extremely complicated visual situations (symbolic information on a background intricately structured by supposition of a TV image on real visual environment) significantly increases time and lowers precision of symbols perception no matter what the HMD type.

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

    Science.gov (United States)

    Huang, Kuo-Lung; Chiu, Chung-Cheng; Chiu, Sheng-Yi; Teng, Yao-Jen; Hao, Shu-Sheng

    2015-07-13

    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.

  7. 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

  8. A Monocular Vision Sensor-Based Obstacle Detection Algorithm for Autonomous Robots

    Science.gov (United States)

    Lee, Tae-Jae; Yi, Dong-Hoon; Cho, Dong-Il “Dan”

    2016-01-01

    This paper presents a monocular vision sensor-based obstacle detection algorithm for autonomous robots. Each individual image pixel at the bottom region of interest is labeled as belonging either to an obstacle or the floor. While conventional methods depend on point tracking for geometric cues for obstacle detection, the proposed algorithm uses the inverse perspective mapping (IPM) method. This method is much more advantageous when the camera is not high off the floor, which makes point tracking near the floor difficult. Markov random field-based obstacle segmentation is then performed using the IPM results and a floor appearance model. Next, the shortest distance between the robot and the obstacle is calculated. The algorithm is tested by applying it to 70 datasets, 20 of which include nonobstacle images where considerable changes in floor appearance occur. The obstacle segmentation accuracies and the distance estimation error are quantitatively analyzed. For obstacle datasets, the segmentation precision and the average distance estimation error of the proposed method are 81.4% and 1.6 cm, respectively, whereas those for a conventional method are 57.5% and 9.9 cm, respectively. For nonobstacle datasets, the proposed method gives 0.0% false positive rates, while the conventional method gives 17.6%. PMID:26938540

  9. 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.

  10. A Height Estimation Approach for Terrain Following Flights from Monocular Vision

    Directory of Open Access Journals (Sweden)

    Igor S. G. Campos

    2016-12-01

    Full Text Available In this paper, we present a monocular vision-based height estimation algorithm for terrain following flights. The impressive growth of Unmanned Aerial Vehicle (UAV usage, notably in mapping applications, will soon require the creation of new technologies to enable these systems to better perceive their surroundings. Specifically, we chose to tackle the terrain following problem, as it is still unresolved for consumer available systems. Virtually every mapping aircraft carries a camera; therefore, we chose to exploit this in order to use presently available hardware to extract the height information toward performing terrain following flights. The proposed methodology consists of using optical flow to track features from videos obtained by the UAV, as well as its motion information to estimate the flying height. To determine if the height estimation is reliable, we trained a decision tree that takes the optical flow information as input and classifies whether the output is trustworthy or not. The classifier achieved accuracies of 80 % for positives and 90 % for negatives, while the height estimation algorithm presented good accuracy.

  11. A Height Estimation Approach for Terrain Following Flights from Monocular Vision.

    Science.gov (United States)

    Campos, Igor S G; Nascimento, Erickson R; Freitas, Gustavo M; Chaimowicz, Luiz

    2016-12-06

    In this paper, we present a monocular vision-based height estimation algorithm for terrain following flights. The impressive growth of Unmanned Aerial Vehicle (UAV) usage, notably in mapping applications, will soon require the creation of new technologies to enable these systems to better perceive their surroundings. Specifically, we chose to tackle the terrain following problem, as it is still unresolved for consumer available systems. Virtually every mapping aircraft carries a camera; therefore, we chose to exploit this in order to use presently available hardware to extract the height information toward performing terrain following flights. The proposed methodology consists of using optical flow to track features from videos obtained by the UAV, as well as its motion information to estimate the flying height. To determine if the height estimation is reliable, we trained a decision tree that takes the optical flow information as input and classifies whether the output is trustworthy or not. The classifier achieved accuracies of 80 % for positives and 90 % for negatives, while the height estimation algorithm presented good accuracy.

  12. Maximum Likelihood Estimation of Monocular Optical Flow Field for Mobile Robot Ego-motion

    Directory of Open Access Journals (Sweden)

    Huajun Liu

    2016-01-01

    Full Text Available This paper presents an optimized scheme of monocular ego-motion estimation to provide location and pose information for mobile robots with one fixed camera. First, a multi-scale hyper-complex wavelet phase-derived optical flow is applied to estimate micro motion of image blocks. Optical flow computation overcomes the difficulties of unreliable feature selection and feature matching of outdoor scenes; at the same time, the multi-scale strategy overcomes the problem of road surface self-similarity and local occlusions. Secondly, a support probability of flow vector is defined to evaluate the validity of the candidate image motions, and a Maximum Likelihood Estimation (MLE optical flow model is constructed based not only on image motion residuals but also their distribution of inliers and outliers, together with their support probabilities, to evaluate a given transform. This yields an optimized estimation of inlier parts of optical flow. Thirdly, a sampling and consensus strategy is designed to estimate the ego-motion parameters. Our model and algorithms are tested on real datasets collected from an intelligent vehicle. The experimental results demonstrate the estimated ego-motion parameters closely follow the GPS/INS ground truth in complex outdoor road scenarios.

  13. Cross-Covariance Estimation for Ekf-Based Inertial Aided Monocular Slam

    Science.gov (United States)

    Kleinert, M.; Stilla, U.

    2011-04-01

    Repeated observation of several characteristically textured surface elements allows the reconstruction of the camera trajectory and a sparse point cloud which is often referred to as "map". The extended Kalman filter (EKF) is a popular method to address this problem, especially if real-time constraints have to be met. Inertial measurements as well as a parameterization of the state vector that conforms better to the linearity assumptions made by the EKF may be employed to reduce the impact of linearization errors. Therefore, we adopt an inertial-aided monocular SLAM approach where landmarks are parameterized in inverse depth w.r.t. the coordinate system in which they were observed for the first time. In this work we present a method to estimate the cross-covariances between landmarks which are introduced in the EKF state vector for the first time and the old filter state that can be applied in the special case at hand where each landmark is parameterized w.r.t. an individual coordinate system.

  14. 3D Reconstruction from a Single Still Image Based on Monocular Vision of an Uncalibrated Camera

    Directory of Open Access Journals (Sweden)

    Yu Tao

    2017-01-01

    Full Text Available we propose a framework of combining Machine Learning with Dynamic Optimization for reconstructing scene in 3D automatically from a single still image of unstructured outdoor environment based on monocular vision of an uncalibrated camera. After segmenting image first time, a kind of searching tree strategy based on Bayes rule is used to identify the hierarchy of all areas on occlusion. After superpixel segmenting image second time, the AdaBoost algorithm is applied in the integration detection to the depth of lighting, texture and material. Finally, all the factors above are optimized with constrained conditions, acquiring the whole depthmap of an image. Integrate the source image with its depthmap in point-cloud or bilinear interpolation styles, realizing 3D reconstruction. Experiment in comparisons with typical methods in associated database demonstrates our method improves the reasonability of estimation to the overall 3D architecture of image’s scene to a certain extent. And it does not need any manual assist and any camera model information.

  15. Exploiting Depth From Single Monocular Images for Object Detection and Semantic Segmentation

    Science.gov (United States)

    Cao, Yuanzhouhan; Shen, Chunhua; Shen, Heng Tao

    2017-02-01

    Augmenting RGB data with measured depth has been shown to improve the performance of a range of tasks in computer vision including object detection and semantic segmentation. Although depth sensors such as the Microsoft Kinect have facilitated easy acquisition of such depth information, the vast majority of images used in vision tasks do not contain depth information. In this paper, we show that augmenting RGB images with estimated depth can also improve the accuracy of both object detection and semantic segmentation. Specifically, we first exploit the recent success of depth estimation from monocular images and learn a deep depth estimation model. Then we learn deep depth features from the estimated depth and combine with RGB features for object detection and semantic segmentation. Additionally, we propose an RGB-D semantic segmentation method which applies a multi-task training scheme: semantic label prediction and depth value regression. We test our methods on several datasets and demonstrate that incorporating information from estimated depth improves the performance of object detection and semantic segmentation remarkably.

  16. A Height Estimation Approach for Terrain Following Flights from Monocular Vision

    Science.gov (United States)

    Campos, Igor S. G.; Nascimento, Erickson R.; Freitas, Gustavo M.; Chaimowicz, Luiz

    2016-01-01

    In this paper, we present a monocular vision-based height estimation algorithm for terrain following flights. The impressive growth of Unmanned Aerial Vehicle (UAV) usage, notably in mapping applications, will soon require the creation of new technologies to enable these systems to better perceive their surroundings. Specifically, we chose to tackle the terrain following problem, as it is still unresolved for consumer available systems. Virtually every mapping aircraft carries a camera; therefore, we chose to exploit this in order to use presently available hardware to extract the height information toward performing terrain following flights. The proposed methodology consists of using optical flow to track features from videos obtained by the UAV, as well as its motion information to estimate the flying height. To determine if the height estimation is reliable, we trained a decision tree that takes the optical flow information as input and classifies whether the output is trustworthy or not. The classifier achieved accuracies of 80% for positives and 90% for negatives, while the height estimation algorithm presented good accuracy. PMID:27929424

  17. A Monocular Vision Sensor-Based Obstacle Detection Algorithm for Autonomous Robots

    Directory of Open Access Journals (Sweden)

    Tae-Jae Lee

    2016-03-01

    Full Text Available This paper presents a monocular vision sensor-based obstacle detection algorithm for autonomous robots. Each individual image pixel at the bottom region of interest is labeled as belonging either to an obstacle or the floor. While conventional methods depend on point tracking for geometric cues for obstacle detection, the proposed algorithm uses the inverse perspective mapping (IPM method. This method is much more advantageous when the camera is not high off the floor, which makes point tracking near the floor difficult. Markov random field-based obstacle segmentation is then performed using the IPM results and a floor appearance model. Next, the shortest distance between the robot and the obstacle is calculated. The algorithm is tested by applying it to 70 datasets, 20 of which include nonobstacle images where considerable changes in floor appearance occur. The obstacle segmentation accuracies and the distance estimation error are quantitatively analyzed. For obstacle datasets, the segmentation precision and the average distance estimation error of the proposed method are 81.4% and 1.6 cm, respectively, whereas those for a conventional method are 57.5% and 9.9 cm, respectively. For nonobstacle datasets, the proposed method gives 0.0% false positive rates, while the conventional method gives 17.6%.

  18. Development of an indoor positioning and navigation system using monocular SLAM and IMU

    Science.gov (United States)

    Mai, Yu-Ching; Lai, Ying-Chih

    2016-07-01

    The positioning and navigation systems based on Global Positioning System (GPS) have been developed over past decades and have been widely used for outdoor environment. However, high-rise buildings or indoor environments can block the satellite signal. Therefore, many indoor positioning methods have been developed to respond to this issue. In addition to the distance measurements using sonar and laser sensors, this study aims to develop a method by integrating a monocular simultaneous localization and mapping (MonoSLAM) algorithm with an inertial measurement unit (IMU) to build an indoor positioning system. The MonoSLAM algorithm measures the distance (depth) between the image features and the camera. With the help of Extend Kalman Filter (EKF), MonoSLAM can provide real-time position, velocity and camera attitude in world frame. Since the feature points will not always appear and can't be trusted at any time, a wrong estimation of the features will cause the estimated position diverge. To overcome this problem, a multisensor fusion algorithm was applied in this study by using the multi-rate Kalman Filter. Finally, from the experiment results, the proposed system was verified to be able to improve the reliability and accuracy of the MonoSLAM by integrating the IMU measurements.

  19. EARLY CRT MONITORING USING TIME-DOMAIN OPTICAL COHERENCE TOMOGRAPHY DOES NOT ADD TO VISUAL ACUITY FOR PREDICTING VISUAL LOSS IN PATIENTS WITH CENTRAL RETINAL VEIN OCCLUSION TREATED WITH INTRAVITREAL RANIBIZUMAB: A Secondary Analysis of Trial Data.

    Science.gov (United States)

    Bell, Katy J L; Hayen, Andrew; Glasziou, Paul; Mitchell, Andrew S; Farris, Maria; Wright, Jonathan; Duerr, Hans-Peter; Mitchell, Paul; Irwig, Les

    2017-03-01

    Our primary purpose was to assess the clinical (predictive) validity of central retinal thickness (CRT) and best corrected visual acuity (BCVA) at 1 week and 1 month after starting treatment with ranibizumab for central retinal vein occlusion. The authors also assessed detectability of response to treatment. The authors used data from 325 participants in the CRUISE study, which included measurement of time-domain CRT and BCVA at baseline, 1 week, 1 month, and 6 months postrandomization. Analysis of covariance models were fitted to assess clinical validity, and distributions of change were constructed to assess detectability of response. There was no evidence that 1-week CRT, and very strong evidence that 1-week BCVA were associated with baseline-adjusted BCVA at 6 months (P = 0.17 and P central retinal vein occlusion patients seemed more informative than time-domain optical coherence tomography monitoring.

  20. Relationship of Visual Cortex Function and Visual Acuity in Anisometropic Amblyopic Children

    Directory of Open Access Journals (Sweden)

    Chuanming Li, Lin Cheng, Qiongwu Yu, Bing Xie, Jian Wang

    2012-01-01

    Full Text Available Purpose: To detect the functional deficit of the visual cortex in anisometropic amblyopia children using functional magnetic resonance imaging (fMRI technique, and investigate the relationship between visual acuity and visual cortex function.Methods: Blood oxygenation level-dependent fMRI (BOLD-fMRI was performed in ten monocular anisometropic amblyopia children and ten normal controls. fMRI images were acquired in two runs with visual stimulation delivered separately through the sound and amblyopic eyes. Measurements were performed in cortical activation of striate and extrastriate areas at the occipital lobe. The relationship between cortex function and visual acuity was analyzed by Pearson partial analysis.Results: The activation areas of both the striate and extrastriate cortices in the amblyopic eyes were significantly lower than that of the sound fellow eyes. No relationship was found between the striate and extrastriate cortex activation. No relationship was found between the visual cortical activation of striate, extrastriate areas and visual acuity of anisometropic amblyopes.Conclusions: BOLD-fMRI revealed the independent striate and extrastriate cortical deficits in anisometropic amblyopes. In addition, the visual acuity lesion and the striate and extrastriate cortical deficits were not parallel, and results of fMRI examination have much potential value in the evaluation of amblyopia.

  1. LASIK monocular en pacientes adultos con ambliopía por anisometropía

    National Research Council Canada - National Science Library

    Alejandro Tamez-Peña; José Nava-García; Jaime Torres-Gómez; Christian Cadena-Garza; Denise Loya-García; Julio C. Hernández-Camarena; Jorge E. Valdez-García

    2017-01-01

    ...), la agudeza visual sin corrección (AVSC) y la agudeza visual mejor corregida (AVMC). La agudeza visual medida por la cartilla de Snellen fue convertida a LogMAR con fines de análisis estadístico. Resultados...

  2. 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 ... conversations when two or more people are talking Difficulty ...

  3. 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.

  4. VALIDEZ DE LA ESTIMACIÓN VISUAL COMO MÉTODO DIAGNÓSTICO DE LA HEMORRAGIA POSTPARTO SEVERA EN UN HOSPITAL UNIVERSITARIO. BOGOTÁ. 2007 Validity of visual estimation of blood loss as diagnostic tool in severe post partum hemorrhage in an university hospital. Bogotá. 2007

    Directory of Open Access Journals (Sweden)

    Jorge Andrés Rubio-Romero

    2010-07-01

    immediately after vaginal delivery. Material and methods. A diagnostic accuracy study was carried out in a cohort of pregnant women who had a vaginal delivery at an university hospital. It was approved by the ethics and investigation committees of participating institutions. A complex gold standard combining clinical and laboratory signs was defined: need of therapeutic maneuvers for treatment of post partum hemorrhage, drop of 10% or more of previous hematocrit or need of transfusion. Results. Incidence of SPPH was 10,7% of the 168 patients included. Median volume of estimated blood loss was 375 mL while median real observed blood volume was 475 mL. For the diagnosis of SPPH, estimated blood loss greater than 500 mL had a sensitivity and specificity of 77,8 y 73,3% respectively. For estimated blood loss greater than 800 mL, sensitivity and specificity were 44,4 and 94%. This cut point is the one that better classifies puerperal women requiring initial treatment for diagnose an abnormal hemorrhage of the post partum. Conclusions. Visual estimation of blood loss during delivery is a poorly sensitive and specific diagnostic test for the diagnosis of SPPH due to underestimation of the real magnitude of the blood loss occurred. Key words: validity of tests, reproducibility of results, sensitivity and specificity, postpartum hemorrhage. Rubio-Romero JA, Guevara-Cruz OA, Gaitán- Duarte H. Validity of visual estimation of blood loss as diagnostic tool in severe post partum hemorrhage in an university hospital. Bogotá. 2007. Rev.Fac.Med. 2010; 58: 173-184.

  5. 2-[123I]-iodolisuride SPET visualizes dopaminergic loss in de-novo parkinsonian patients: is it a marker of striatal pre-synaptic degeneration?

    Science.gov (United States)

    Müller, T; Eising, E G; Reiners, C; Przuntek, H; Jacob, M; Kuhn, W

    1997-12-01

    The aim of this study was to assess the correlation between the functional integrity and density of striatal dopaminergic receptors and clinical data in 15 de-novo patients with idiopathic Parkinson's disease by single photon emission tomography (SPET) using 2-[123I]-iodolisuride (ILIS), a tracer based on the D2-dopamine receptor agonist lisuride. Deficient striatal uptake of ILIS correlated with the severity of the disorder, scored by the Unified Parkinson's Disease Rating Scale (UPDRS) (n = 15; ratio of ILIS uptake: basal ganglia/cerebellum [B/C] & UPDRS I-III, Spearman R = -0.562, P = 0.013), Beck's Depression Inventory (BDI) (n = 12; B/C & BDI, Spearman R = -0.825, P = 0.0009) and the ZUNG Depression Scale (ZDS) (n = 11; B/C & ZDS, Spearman R = -0.7425, P = 0.008). Experimental data indicate that lisuride shows a higher affinity for pre-synaptic dopaminergic autoreceptors than for post-synaptic D2-dopamine receptors under conditions of low applied ILIS concentrations as in this study. From the results of this study and these experimental data, we speculate that ILIS-SPET can visualize pre-synaptic striatal dopaminergic degeneration in Parkinson's disease.

  6. 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.

  7. Obstacle Detection and Avoidance System Based on Monocular Camera and Size Expansion Algorithm for UAVs

    Science.gov (United States)

    Al-Kaff, Abdulla; García, Fernando; Martín, David; De La Escalera, Arturo; Armingol, José María

    2017-01-01

    One of the most challenging problems in the domain of autonomous aerial vehicles is the designing of a robust real-time obstacle detection and avoidance system. This problem is complex, especially for the micro and small aerial vehicles, that is due to the Size, Weight and Power (SWaP) constraints. Therefore, using lightweight sensors (i.e., Digital camera) can be the best choice comparing with other sensors; such as laser or radar.For real-time applications, different works are based on stereo cameras in order to obtain a 3D model of the obstacles, or to estimate their depth. Instead, in this paper, a method that mimics the human behavior of detecting the collision state of the approaching obstacles using monocular camera is proposed. The key of the proposed algorithm is to analyze the size changes of the detected feature points, combined with the expansion ratios of the convex hull constructed around the detected feature points from consecutive frames. During the Aerial Vehicle (UAV) motion, the detection algorithm estimates the changes in the size of the area of the approaching obstacles. First, the method detects the feature points of the obstacles, then extracts the obstacles that have the probability of getting close toward the UAV. Secondly, by comparing the area ratio of the obstacle and the position of the UAV, the method decides if the detected obstacle may cause a collision. Finally, by estimating the obstacle 2D position in the image and combining with the tracked waypoints, the UAV performs the avoidance maneuver. The proposed algorithm was evaluated by performing real indoor and outdoor flights, and the obtained results show the accuracy of the proposed algorithm compared with other related works. PMID:28481277

  8. Avoiding monocular artifacts in clinical stereotests presented on column-interleaved digital stereoscopic displays.

    Science.gov (United States)

    Serrano-Pedraza, Ignacio; Vancleef, Kathleen; Read, Jenny C A

    2016-11-01

    New forms of stereoscopic 3-D technology offer vision scientists new opportunities for research, but also come with distinct problems. Here we consider autostereo displays where the two eyes' images are spatially interleaved in alternating columns of pixels and no glasses or special optics are required. Column-interleaved displays produce an excellent stereoscopic effect, but subtle changes in the angle of view can increase cross talk or even interchange the left and right eyes' images. This creates several challenges to the presentation of cyclopean stereograms (containing structure which is only detectable by binocular vision). We discuss the potential artifacts, including one that is unique to column-interleaved displays, whereby scene elements such as dots in a random-dot stereogram appear wider or narrower depending on the sign of their disparity. We derive an algorithm for creating stimuli which are free from this artifact. We show that this and other artifacts can be avoided by (a) using a task which is robust to disparity-sign inversion-for example, a disparity-detection rather than discrimination task-(b) using our proposed algorithm to ensure that parallax is applied symmetrically on the column-interleaved display, and (c) using a dynamic stimulus to avoid monocular artifacts from motion parallax. In order to test our recommendations, we performed two experiments using a stereoacuity task implemented with a parallax-barrier tablet. Our results confirm that these recommendations eliminate the artifacts. We believe that these recommendations will be useful to vision scientists interested in running stereo psychophysics experiments using parallax-barrier and other column-interleaved digital displays.

  9. Obstacle Detection and Avoidance System Based on Monocular Camera and Size Expansion Algorithm for UAVs.

    Science.gov (United States)

    Al-Kaff, Abdulla; García, Fernando; Martín, David; De La Escalera, Arturo; Armingol, José María

    2017-05-07

    One of the most challenging problems in the domain of autonomous aerial vehicles is the designing of a robust real-time obstacle detection and avoidance system. This problem is complex, especially for the micro and small aerial vehicles, that is due to the Size, Weight and Power (SWaP) constraints. Therefore, using lightweight sensors (i.e., Digital camera) can be the best choice comparing with other sensors; such as laser or radar.For real-time applications, different works are based on stereo cameras in order to obtain a 3D model of the obstacles, or to estimate their depth. Instead, in this paper, a method that mimics the human behavior of detecting the collision state of the approaching obstacles using monocular camera is proposed. The key of the proposed algorithm is to analyze the size changes of the detected feature points, combined with the expansion ratios of the convex hull constructed around the detected feature points from consecutive frames. During the Aerial Vehicle (UAV) motion, the detection algorithm estimates the changes in the size of the area of the approaching obstacles. First, the method detects the feature points of the obstacles, then extracts the obstacles that have the probability of getting close toward the UAV. Secondly, by comparing the area ratio of the obstacle and the position of the UAV, the method decides if the detected obstacle may cause a collision. Finally, by estimating the obstacle 2D position in the image and combining with the tracked waypoints, the UAV performs the avoidance maneuver. The proposed algorithm was evaluated by performing real indoor and outdoor flights, and the obtained results show the accuracy of the proposed algorithm compared with other related works.

  10. 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.

  11. Visual Impairment

    Science.gov (United States)

    ... Surgery? Choosing the Right Sport for You Shyness Visual Impairment KidsHealth > For Teens > Visual Impairment Print A A ... with the brain, making vision impossible. What Is Visual Impairment? Many people have some type of visual problem ...

  12. Visual field

    Science.gov (United States)

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

  13. Sensor Fusion of Monocular Cameras and Laser Rangefinders for Line-Based Simultaneous Localization and Mapping (SLAM Tasks in Autonomous Mobile Robots

    Directory of Open Access Journals (Sweden)

    Xinzheng Zhang

    2012-01-01

    Full Text Available This paper presents a sensor fusion strategy applied for Simultaneous Localization and Mapping (SLAM in dynamic environments. The designed approach consists of two features: (i the first one is a fusion module which synthesizes line segments obtained from laser rangefinder and line features extracted from monocular camera. This policy eliminates any pseudo segments that appear from any momentary pause of dynamic objects in laser data. (ii The second characteristic is a modified multi-sensor point estimation fusion SLAM (MPEF-SLAM that incorporates two individual Extended Kalman Filter (EKF based SLAM algorithms: monocular and laser SLAM. The error of the localization in fused SLAM is reduced compared with those of individual SLAM. Additionally, a new data association technique based on the homography transformation matrix is developed for monocular SLAM. This data association method relaxes the pleonastic computation. The experimental results validate the performance of the proposed sensor fusion and data association method.

  14. The Energy Spectrum of Ultra-High-Energy Cosmic Rays Measured by the Telescope Array FADC Fluorescence Detectors in Monocular Mode

    CERN Document Server

    Abu-Zayyad, T; Allen, M; Anderson, R; Azuma, R; Barcikowski, E; Belz, J W; Bergman, D R; Blake, S A; Cady, R; Cheon, B G; Chiba, J; Chikawa, M; Cho, E J; Cho, W R; Fujii, H; Fujii, T; Fukuda, T; Fukushima, M; Hanlon, W; Hayashi, K; Hayashi, Y; Hayashida, N; Hibino, K; Hiyama, K; Honda, K; Iguchi, T; Ikeda, D; Ikuta, K; Inoue, N; Ishii, T; Ishimori, R; Ito, H; Ivanov, D; Iwamoto, S; Jui, C C H; Kadota, K; Kakimoto, F; Kalashev, O; Kanbe, T; Kasahara, K; Kawai, H; Kawakami, S; Kawana, S; Kido, E; Kim, H B; Kim, H K; Kim, J H; Kitamoto, K; Kitamura, S; Kitamura, Y; Kobayashi, K; Kobayashi, Y; Kondo, Y; Kuramoto, K; Kuzmin, V; Kwon, Y J; Lan, J; Lim, S I; Lundquist, J P; Machida, S; Martens, K; Matsuda, T; Matsuura, T; Matsuyama, T; Matthews, J N; Myers, I; Minamino, M; Miyata, K; Murano, Y; Nagataki, S; Nakamura, T; Nam, S W; Nonaka, T; Ogio, S; Ogura, J; Ohnishi, M; Ohoka, H; Oki, K; Oku, D; Okuda, T; Ono, M; Oshima, A; Ozawa, S; Park, I H; Pshirkov, M S; Rodriguez, D C; Roh, S Y; Rubtsov, G; Ryu, D; Sagawa, H; Sakurai, N; Sampson, A L; Scott, L M; Shah, P D; Shibata, F; Shibata, T; Shimodaira, H; Shin, B K; Shin, J I; Shirahama, T; Smith, J D; Sokolsky, P; Sonley, T J; Springer, R W; Stokes, B T; Stratton, S R; Stroman, T A; Suzuki, S; Takahashi, Y; Takeda, M; Taketa, A; Takita, M; Tameda, Y; Tanaka, H; Tanaka, K; Tanaka, M; Thomas, S B; Thomson, G B; Tinyakov, P; Tkachev, I; Tokuno, H; Tomida, T; Troitsky, S; Tsunesada, Y; Tsutsumi, K; Tsuyuguchi, Y; Uchihori, Y; Udo, S; Ukai, H; Vasiloff, G; Wada, Y; Wong, T; Yamakawa, Y; Yamane, R; Yamaoka, H; Yamazaki, K; Yang, J; Yoneda, Y; Yoshida, S; Yoshii, H; Zollinger, R; Zundel, Z

    2013-01-01

    We present a measurement of the energy spectrum of ultra-high-energy cosmic rays performed by the Telescope Array experiment using monocular observations from its two new FADC-based fluorescence detectors. After a short description of the experiment, we describe the data analysis and event reconstruction procedures. Since the aperture of the experiment must be calculated by Monte Carlo simulation, we describe this calculation and the comparisons of simulated and real data used to verify the validity of the aperture calculation. Finally, we present the energy spectrum calculated from the merged monocular data sets of the two FADC-based detectors, and also the combination of this merged spectrum with an independent, previously published monocular spectrum measurement performed by Telescope Array's third fluorescence detector (Abu-Zayyad {\\it et al.}, {Astropart. Phys.} 39 (2012), 109). This combined spectrum corroborates the recently published Telescope Array surface detector spectrum (Abu-Zayyad {\\it et al.}, ...

  15. Sensor fusion of monocular cameras and laser rangefinders for line-based Simultaneous Localization and Mapping (SLAM) tasks in autonomous mobile robots.

    Science.gov (United States)

    Zhang, Xinzheng; Rad, Ahmad B; Wong, Yiu-Kwong

    2012-01-01

    This paper presents a sensor fusion strategy applied for Simultaneous Localization and Mapping (SLAM) in dynamic environments. The designed approach consists of two features: (i) the first one is a fusion module which synthesizes line segments obtained from laser rangefinder and line features extracted from monocular camera. This policy eliminates any pseudo segments that appear from any momentary pause of dynamic objects in laser data. (ii) The second characteristic is a modified multi-sensor point estimation fusion SLAM (MPEF-SLAM) that incorporates two individual Extended Kalman Filter (EKF) based SLAM algorithms: monocular and laser SLAM. The error of the localization in fused SLAM is reduced compared with those of individual SLAM. Additionally, a new data association technique based on the homography transformation matrix is developed for monocular SLAM. This data association method relaxes the pleonastic computation. The experimental results validate the performance of the proposed sensor fusion and data association method.

  16. Modeling Of A Monocular, Full-Color, Laser-Scanning, Helmet-Mounted Display for Aviator Situational Awareness

    Science.gov (United States)

    2017-03-27

    USAARL Report No. 2017-10 Modeling of a Monocular, Full-Color, Laser- Scanning, Helmet-Mounted Display for Aviator Situational Awareness By Thomas...Mounted Display for Aviator Situational Awareness N/A N/A N/A N/A N/A N/A Harding, Thomas H. Raatz, Maria E. Martin, John S. Rash, Clarence E. U.S...Huntsville, AL 35806-3302 PM Air Warrior, PEO Soldier Approved for public release; distribution unlimited. The modeling data and analysis presented in

  17. [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.

  18. The Corpus Callosum and the Visual Cortex: Plasticity Is a Game for Two

    Directory of Open Access Journals (Sweden)

    Marta Pietrasanta

    2012-01-01

    Full Text Available Throughout life, experience shapes and selects the most appropriate brain functional connectivity to adapt to a changing environment. An ideal system to study experience-dependent plasticity is the visual cortex, because visual experience can be easily manipulated. In this paper, we focus on the role of interhemispheric, transcallosal projections in experience-dependent plasticity of the visual cortex. We review data showing that deprivation of sensory experience can modify the morphology of callosal fibres, thus altering the communication between the two hemispheres. More importantly, manipulation of callosal input activity during an early critical period alters developmental maturation of functional properties in visual cortex and modifies its ability to remodel in response to experience. We also discuss recent data in rat visual cortex, demonstrating that the corpus callosum plays a role in binocularity of cortical neurons and is involved in the plastic shift of eye preference that follows a period of monocular eyelid suture (monocular deprivation in early age. Thus, experience can modify the fine connectivity of the corpus callosum, and callosal connections represent a major pathway through which experience can mediate functional maturation and plastic rearrangements in the visual cortex.

  19. 基于单应性矩阵的室内移动机器人视觉定位研究%Study on Visual Positioning Based on Homography for Indoor Mobile Robot

    Institute of Scientific and Technical Information of China (English)

    徐德; 涂志国; 谭民

    2005-01-01

    Monocular visual positioning for indoor mobile robot is concerned in this paper. A new visual positioning method based on homography matrix in Euclidean space is proposed. It can calculate the position and pose of the mobile robot according to the intrinsic parameters of camera and two position-known points in a plane. It is very simple and low cost in computation. The experimental results show its effectiveness.

  20. Integration of monocular motion signals and the analysis of interocular velocity differences for the perception of motion-in-depth.

    Science.gov (United States)

    Shioiri, Satoshi; Kakehi, Daisuke; Tashiro, Tomoyoshi; Yaguchi, Hirohisa

    2009-12-09

    We investigated how the mechanism for perceiving motion-in-depth based on interocular velocity differences (IOVDs) integrates signals from the motion spatial frequency (SF) channels. We focused on the question whether this integration is implemented before or after the comparison of the velocity signals from the two eyes. We measured spatial frequency selectivity of the MAE of motion in depth (3D MAE). The 3D MAE showed little spatial frequency selectivity, whereas the 2D lateral MAE showed clear spatial frequency selectivity in the same condition. This indicates that the outputs of the monocular motion SF channels are combined before analyzing the IOVD. The presumption was confirmed by the disappearance of the 3D MAE after exposure to superimposed gratings with different spatial frequencies moving in opposite directions. The direction of the 2D MAE depended on the test spatial frequency in the same condition. These results suggest that the IOVD is calculated at a relatively later stage of the motion analysis, and that some monocular information is preserved even after the integration of the motion SF channel outputs.

  1. Real-time drogue recognition and 3D locating for UAV autonomous aerial refueling based on monocular machine vision

    Institute of Scientific and Technical Information of China (English)

    Wang Xufeng; Kong Xingwei; Zhi Jianhui; Chen Yong; Dong Xinmin

    2015-01-01

    Drogue recognition and 3D locating is a key problem during the docking phase of the autonomous aerial refueling (AAR). To solve this problem, a novel and effective method based on monocular vision is presented in this paper. Firstly, by employing computer vision with red-ring-shape feature, a drogue detection and recognition algorithm is proposed to guarantee safety and ensure the robustness to the drogue diversity and the changes in environmental condi-tions, without using a set of infrared light emitting diodes (LEDs) on the parachute part of the dro-gue. Secondly, considering camera lens distortion, a monocular vision measurement algorithm for drogue 3D locating is designed to ensure the accuracy and real-time performance of the system, with the drogue attitude provided. Finally, experiments are conducted to demonstrate the effective-ness of the proposed method. Experimental results show the performances of the entire system in contrast with other methods, which validates that the proposed method can recognize and locate the drogue three dimensionally, rapidly and precisely.

  2. Ground moving target geo-location from monocular camera mounted on a micro air vehicle

    Science.gov (United States)

    Guo, Li; Ang, Haisong; Zheng, Xiangming

    2011-08-01

    The usual approaches to unmanned air vehicle(UAV)-to-ground target geo-location impose some severe constraints to the system, such as stationary objects, accurate geo-reference terrain database, or ground plane assumption. Micro air vehicle(MAV) works with characteristics including low altitude flight, limited payload and onboard sensors' low accuracy. According to these characteristics, a method is developed to determine the location of ground moving target which imaged from the air using monocular camera equipped on MAV. This method eliminates the requirements for terrain database (elevation maps) and altimeters that can provide MAV's and target's altitude. Instead, the proposed method only requires MAV flight status provided by its inherent onboard navigation system which includes inertial measurement unit(IMU) and global position system(GPS). The key is to get accurate information on the altitude of the ground moving target. First, Optical flow method extracts background static feature points. Setting a local region around the target in the current image, The features which are on the same plane with the target in this region are extracted, and are retained as aided features. Then, inverse-velocity method calculates the location of these points by integrated with aircraft status. The altitude of object, which is calculated by using position information of these aided features, combining with aircraft status and image coordinates, geo-locate the target. Meanwhile, a framework with Bayesian estimator is employed to eliminate noise caused by camera, IMU and GPS. Firstly, an extended Kalman filter(EKF) provides a simultaneous localization and mapping solution for the estimation of aircraft states and aided features location which defines the moving target local environment. Secondly, an unscented transformation(UT) method determines the estimated mean and covariance of target location from aircraft states and aided features location, and then exports them for the

  3. Differential effects of head-mounted displays on visual performance.

    Science.gov (United States)

    Schega, Lutz; Hamacher, Daniel; Erfuth, Sandra; Behrens-Baumann, Wolfgang; Reupsch, Juliane; Hoffmann, Michael B

    2014-01-01

    Head-mounted displays (HMDs) virtually augment the visual world to aid visual task completion. Three types of HMDs were compared [look around (LA); optical see-through with organic light emitting diodes and virtual retinal display] to determine whether LA, leaving the observer functionally monocular, is inferior. Response times and error rates were determined for a combined visual search and Go-NoGo task. The costs of switching between displays were assessed separately. Finally, HMD effects on basic visual functions were quantified. Effects of HMDs on visual search and Go-NoGo task were small, but for LA display-switching costs for the Go-NoGo-task the effects were pronounced. Basic visual functions were most affected for LA (reduced visual acuity and visual field sensitivity, inaccurate vergence movements and absent stereo-vision). LA involved comparatively high switching costs for the Go-NoGo task, which might indicate reduced processing of external control cues. Reduced basic visual functions are a likely cause of this effect.

  4. Altered neuronal architecture and plasticity in the visual cortex of adult MMP-3-deficient mice.

    Science.gov (United States)

    Aerts, Jeroen; Nys, Julie; Moons, Lieve; Hu, Tjing-Tjing; Arckens, Lutgarde

    2015-09-01

    Matrix metalloproteinases (MMPs) are Zn(2+)-dependent endopeptidases considered to be essential for normal brain development and neuroplasticity by modulating extracellular matrix proteins, receptors, adhesion molecules, growth factors and cytoskeletal proteins. Specifically, MMP-3 has recently been implicated in synaptic plasticity, hippocampus-dependent learning and neuronal development and migration in the cerebellum. However, the function(s) of this enzyme in the neocortex is understudied. Therefore, we explored the phenotypical characteristics of the neuronal architecture and the capacity for experience-dependent cortical plasticity in the visual cortex of adult MMP-3-deficient (MMP-3(-/-)) mice. Golgi-Cox stainings revealed a significant reduction in apical dendritic length and an increased number of apical obliques for layer V pyramidal neurons in the visual cortex of adult MMP-3(-/-) mice compared to wild-type (WT) animals. In addition, a significant upregulation of both phosphorylated and non-phosphorylated neurofilament protein (NF)-high, phosphorylated NF-medium, NF-low and α-internexin was detected in the visual cortex of MMP-3(-/-) mice. To assess the effect of MMP-3 deficiency on cortical plasticity, we monocularly enucleated adult MMP-3(-/-) mice and analyzed the reactivation of the contralateral visual cortex 7 weeks post-enucleation. In contrast to previous results in C57Bl/6J adult mice, activity remained confined to the binocular zone and did not expand into the monocular regions indicative for an aberrant open-eye potentiation. Permanent hypoactivity in the monocular cortex lateral and medial to V1 also indicated a lack of cross-modal plasticity. These observations demonstrate that genetic inactivation of MMP-3 has profound effects on the structural integrity and plasticity response of the visual cortex of adult mice.

  5. Dichoptic suppression of mfVEP amplitude: effect of retinal eccentricity and simulated unilateral visual impairment.

    Science.gov (United States)

    Leaney, John; Klistorner, Alexander; Arvind, Hemamalini; Graham, Stuart L

    2010-12-01

    To investigate the effect of retinal eccentricity on the phenomenon of dichoptic suppression of the mfVEP amplitude and to examine the relationship between the degree of simulated unilateral visual impairment and the possible release of dichoptic suppression in the contralateral eye. Eight subjects with corrected visual acuity (VAc) >6/6 and stereoacuity >60 sec arc underwent monocular and dichoptic pattern-pulse mfVEP. Dichoptic stimulation was repeated with refractively induced blur of one eye with +4-D and +6-D lenses above distance correction. Dichoptic recording resulted in significant reduction of averaged mfVEP amplitude (19.8% ± 4.9%, paired t-test, P = 0.00003). The magnitude of suppression, while statistically significant at all eccentricities, was significantly larger in the central part of the visual field and diminished toward the periphery. Refractive blur, used to simulate visual impairment produced variable degrees of amplitude reduction in the blurred eye and resulted in amplitude increases in the contralateral eye. There was a highly significant correlation between the magnitude of amplitude reduction in the blurred eye and increase in amplitude (i.e., release of dichoptic suppression) in the contralateral eye (r = 0.91, P < 0.0001). The study demonstrated that dichoptic stimulation results in eccentricity-dependent suppression of mfVEP amplitude. Factors affecting visual performance of one eye (monocular blur) promote the release of dichoptic suppression in the fellow (unaffected) eye. This phenomenon leads to an increase in intereye asymmetry and therefore may improve early detection of ocular diseases, especially monocular pathologic processes.

  6. Pattern adaptation of relay cells in the lateral geniculate nucleus of binocular and monocular vision-deprived cats%双眼和单眼视觉剥夺猫外膝体细胞的图形适应

    Institute of Scientific and Technical Information of China (English)

    王伟; 寿天德

    2000-01-01

    为测定丘脑外膝体细胞的图形适应是否依赖于早期视觉经验, 在细胞外记录了双眼和单眼缝合的猫外膝体中继细胞对长时间运动光栅刺激的反应. 在双眼剥夺猫,占68%的记录到的细胞在30 s内反应下降到稳定值,其平均反应值下降33%,适应程度较正常猫显著.在单眼剥夺猫,记录到的剥夺眼驱动的和非剥夺眼驱动的细胞中,分别有占53%和44%的细胞显示图形适应, 两者差别不大.研究表明, 早期视剥夺能增强或保持图形适应, 提示图形适应是外膝体细胞常见的固有性质,可能主要由遗传因素所决定.%To test whether the pattern adaptation in thalamus is dependent upon postnatal visual experience during early life, the responses of relay cells to prolonged drifting grating stimulation were recorded extracellularly from the dorsal lateral geniculate nucleus (dLGN) of cats reared with binocular and monocular lid suture. In binocular vision-deprived cats, 68% of cells recorded showed significant adaptation to prolonged grating stimuli within 30 s, with a mean response decrease of 33%, and then stabilized gradually. This adaptation was stronger than that of relay cells in normal cats. In monocular vision-deprived cats, 53% of the cells driven by the deprived eye showed similar adaptation as did 44% of the cells driven by the non-deprived eye. These results indicate that pattern adaptation could be maintained or even enhanced after visual deprivation in early life. It is suggested that pattern adaptation is a general and intrinsic property of the dLGN cells, which may be mainly determined by genetic factors.

  7. Naso-Temporal Asymmetries: Suppression of Emotional Faces in the Temporal Visual Hemifield

    Science.gov (United States)

    Framorando, David; Bapst, Mylène; Vuille, Nathalie; Pegna, Alan J.

    2017-01-01

    An ongoing debate exists regarding the possible existence of a retino-tectal visual pathway projecting to the amygdala, which would rapidly process information involving threatening or behaviorally-relevant stimuli. It has been suggested that this route might be responsible for the involuntary capture of attention by potentially dangerous stimuli. In separate studies, anatomical evidence has suggested that the retino-tectal pathway relies essentially on projections from the nasal hemiretina (temporal visual field). In this study, we chose to take advantage of this anatomical difference to further investigate whether emotional facial expressions are indeed processed through a subcortical pathway. Using EEG, participants performed a monocular spatial attention paradigm in which lateralized, task-irrelevant distractors were presented, followed by a target. The distractors were fearful faces that appeared either in nasal or temporal visual hemifield (by virtue of their monocular presentations), while the neutral face was presented simultaneously on the opposite side. Participants were asked to identify a target letter that appeared subsequently in the nasal or temporal visual hemifield. Event-related potentials (ERPs) results revealed that fearful faces appearing in the temporal visual hemifield produced a strong inhibitory response, while a negative deflection reflecting attentional capture followed presentations of fear in the nasal hemifield. These effects can be explained by a greater sensitivity of the subcortical pathway for emotional stimuli. Fearful faces conveyed through this route are processed more effectively, consequently necessitating more vigorous suppression in order for targets to be dealt with adequately. PMID:28197067

  8. Visual map shifts based on whisker-guided cues in the young mouse visual cortex.

    Science.gov (United States)

    Yoshitake, Kohei; Tsukano, Hiroaki; Tohmi, Manavu; Komagata, Seiji; Hishida, Ryuichi; Yagi, Takeshi; Shibuki, Katsuei

    2013-12-12

    Mice navigate nearby space using their vision and whiskers, and young mice learn to integrate these heterogeneous inputs in perceptual space. We found that cortical responses were depressed in the primary visual cortex of young mice after wearing a monocular prism. This depression was uniformly observed in the primary visual cortex and was eliminated by whisker trimming or lesions in the posterior parietal cortex. Compensatory visual map shifts of responses elicited via the eye that had worn the prism were also observed. As a result, cortical responses elicited via each eye were clearly separated when a visual stimulus was placed in front of the mice. A comparison of response areas before and after prism wearing indicated that the map shifts were produced by depression with spatial eccentricity. Visual map shifts based on whisker-guided cues may serve as a model for investigating the cellular and molecular mechanisms underlying higher sensory integration in the mammalian brain. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

  9. Visual impairment secondary to congenital glaucoma in children: visual responses, optical correction and use of low vision AIDS.

    Science.gov (United States)

    Haddad, Maria Aparecida Onuki; Sampaio, Marcos Wilson; Oltrogge, Ernst Werner; Kara-José, Newton; Betinjane, Alberto Jorge

    2009-01-01

    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. To analyze data concerning visual response, the use of optical correction and prescribed low vision aids in a population of children with congenital glaucoma. The authors analyzed data from 100 children with congenital glaucoma to assess best corrected visual acuity, prescribed optical correction and low vision aids. 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 x 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. 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.

  10. Hair Loss

    Science.gov (United States)

    ... loss at the scarred areas. These conditions include lichen planus, some types of lupus and sarcoidosis. Hair- ... increase your risk of hair loss, including: Family history Age Poor nutrition Certain medical conditions, such as ...

  11. Hearing Loss

    Science.gov (United States)

    ... effects on your hearing — ringing in the ear (tinnitus) or hearing loss — can occur if you take ... adults with hearing loss, commonly reported problems include: Depression Anxiety An often false sense that others are ...

  12. Visual acuity evaluated by pattern-reversal visual-evoked potential is affected by check size/visual angle

    Institute of Scientific and Technical Information of China (English)

    Xiping Chen; Qianqian Li; Xiaoqin Liu; Li Yang; Wentao Xia; Luyang Tao

    2012-01-01

    Objective To systemically explore the range of visual angles that affect visual acuity,and to establish the relationship between the P 1 component (peak latency ~100 ms) of the pattern-reversal visual-evoked potential (PRVEP) and the visual acuity at particular visual angles.Methods Two hundred and ten volunteers were divided into seven groups,according to visual acuity as assessed by the standard logarithmic visual acuity chart (SLD-II).For each group,the PRVEP components were elicited in response to visual angle presentations at 8°,4°,2°,1 °/60′,30′,15′,and 7.5′,in the whiteblack chess-board reversal mode with a contrast level of 100% at a frequency of 2 Hz.Visual stimuli were presented monocularly,and 200 presentations were averaged for each block of trials.The early and stable component P1 was recorded at the mid-line of the occipital region (Oz) and analyzed with SPSS 13.00.Results (1) Oz had the maximum P1 amplitude;there was no significant difference between genders or for interocular comparison in normal controls and subjects with optic myopia.(2) The P1 latency decreased slowly below 30′,then increased rapidly.The P1 amplitude initially increased with check size,and was maximal at ~1° and ~30′.(3) The P1 latency in the group with visual acuity ≤0.2 was significantly different at 8°,15′ and 7.5′,while the amplitude differed at all visual angles,compared with the group with normal vision.Diferences in P1 for the groups with 0.5 and 0.6 acuity were only present at visual angles <1°.(4) Regression analysis showed that the P 1 latency and amplitude were associated with visual acuity over the full range of visual angles.There was a moderate correlation at visual angles <30′.Regression equations were calculated for the P1 components and visual acuity,based on visual angle.Conclusion (1) Visual angle should be taken into consideration when exploring the function of the visual pathway,especially visual acuity.A visual angle

  13. 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.

  14. 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

  15. 伊朗亚兹德2005至2006年住院患者外伤性视力丧失的研究%Traumatic visual loss of inpatients in Yazd, Iran from 2005 to 2006

    Institute of Scientific and Technical Information of China (English)

    Mohammad Reza Besharati; Mohammad Reza Shoja; Maryam Kheirandish; Leila Shirani; Ziba Parizi

    2008-01-01

    目的:调查伊朗亚兹德2005/2006住院患者外伤性视力丧失的情况,并探讨造成视力丧失的原因和预防方法.方法:回顾性分析2005-08/2006-08期间在Shahid Sa-doughi医院住院的所有眼外伤患者(70例)的临床资料,包括年龄、性别、致伤原因、损伤类型、初次治疗的时间、入院和出院时的视力、手术处理程序和最终结果.而且,采用国际上公认的BETY制定的分类标准对眼外伤进行分类.结果:以简易方法选取了共70例眼外伤患者,男女性别比例为2.8:1.眼外伤最频繁的致伤原因是金属物体(34.3%),尤其是在≤10a和≥30a的年龄组,其次是事故(22.8%)和袭击(17.2%).大多数病例(51.4%)等候初次治疗的时间为6~24h.38.6%的病例为眼钝挫伤,其余61.4%的病例为眼穿通伤.在眼钝挫伤和穿通伤病例中,最终视力状况最多为光感(51.8%,41.8%),最少为手动(7.5%,4.7%).手术结果保留眼球且视力基本满意的占72.9%,眼球摘除的占24.2%.结论:鉴于眼外伤发生率高,而且往往造成严重的视力丧失,在大多数事故中,父母的关注、眼部安全保护措施和及早治疗应被视为能否最终保留眼球的重要因素.%· AIM: To investigate the conditions of traumatic visual loss of inpatients in Yazd, Iran from 2005 to 2006, and to explore the possible causes and preventive methods. · METHODS: We retrospectively analyzed data on all patients with eye injuries (70 cases) hospitalized at Shahid Sadoughi Hospital between August 2005 and August 2006, including age, gender, causes, type of injury, time of initial treatment, visual acuity during admission and discharge, surgical procedures, and final outcome. Furthermore, standardized international classifi-cation of ocular trauma (Birmingham Eye Trauma Terminology) was used for eye injury categorization. · RESULTS: A total of 70 inpatients with ocular injuries were selected by simple approach. The male/female ratio was 2.8 to 1. The

  16. Effects of colored light, color of comparison stimulus, and illumination on error in perceived depth with binocular and monocular viewing.

    Science.gov (United States)

    Huang, Kuo-Chen

    2007-06-01

    Two experiments assessed the effects of colored light, color of a comparison stimulus, and illumination on error in perceived depth with binocular and monocular vision. Exp. 1 assessed effects of colored light, color of comparison stimulus, and source of depth cues on error in perceived depth. A total of 29 women and 19 men, Taiwanese college or graduate students ages 20 to 30 years (M=24.0, SD= 2.5) participated; they were randomly divided into five groups, each being assigned to one of five possible colored light conditions. Analyses showed color of the comparison stimulus significantly affected the error in perceived depth, as this error was significantly greater for a red comparison stimulus than for blue and yellow comparison stimuli. Colored light significantly affected error in perceived depth since error under white and yellow light was significantly less than that under green light. Moreover, error in perceived depth under white light was significantly less than that under blue light but not sensitive to white, yellow, and red light. Error in perceived depth for binocular viewing was significantly less than that for monocular viewing but not sex. In Exp. 2, the effect of illumination on error in perceived depth was explored with 21 women and 15 men, Taiwanese college students with a mean age of 19.8 yr. (SD= 1.1). Analysis indicated that illumination significantly affected error in perceived depth, as error for a 40-W condition was significantly greater than under 20- and 60-W conditions, although the latter were not different.

  17. Plasticity of the visual cortex and treatment of amblyopia.

    Science.gov (United States)

    Sengpiel, Frank

    2014-09-22

    Over the last 50 years, research into the developmental plasticity of the visual cortex has led to a growing understanding of first the causes and then of the underlying cellular mechanisms of amblyopia or 'lazy eye', the commonest childhood disorder of vision. While it is widely believed that amblyopia cannot be treated successfully after the age of about 7, recent animal studies have demonstrated that visual cortex plasticity can be restored or enhanced later in life, paving the way for new strategies for the treatment of amblyopia that attempt to remove molecular brakes on plasticity. In addition, both animal and human work has established that amblyopia is not simply a monocular deficit, and therefore the most promising new non-invasive approaches force the two eyes to cooperate as opposed to conventional procedures that severely penalise the good eye. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Visual agnosia.

    Science.gov (United States)

    Álvarez, R; Masjuan, J

    2016-03-01

    Visual agnosia is defined as an impairment of object recognition, in the absence of visual acuity or cognitive dysfunction that would explain this impairment. This condition is caused by lesions in the visual association cortex, sparing primary visual cortex. There are 2 main pathways that process visual information: the ventral stream, tasked with object recognition, and the dorsal stream, in charge of locating objects in space. Visual agnosia can therefore be divided into 2 major groups depending on which of the two streams is damaged. The aim of this article is to conduct a narrative review of the various visual agnosia syndromes, including recent developments in a number of these syndromes.

  19. Frequency-doubling technology perimetry and multifocal visual evoked potential in glaucoma, suspected glaucoma, and control patients

    Directory of Open Access Journals (Sweden)

    Kanadani FN

    2014-07-01

    Full Text Available Fabio N Kanadani,1 Paulo AA Mello,1 Syril K Dorairaj,2 Tereza CM Kanadani31Federal University of Sao Paulo, Sao Paulo, Brazil; 2Mayo Clinic, Department of Ophthalmology, Jacksonville, Florida, USA; 3Sao Jose University Hospital, Belo Horizonte, BrazilIntroduction: The gold standard in functional glaucoma evaluation is standard automated perimetry (SAP. However, SAP depends on the reliability of the patients’ responses and other external factors; therefore, other technologies have been developed for earlier detection of visual field changes in glaucoma patients. The frequency-doubling perimetry (FDT is believed to detect glaucoma earlier than SAP. The multifocal visual evoked potential (mfVEP is an objective test for functional evaluation.Objective: To evaluate the sensitivity and specificity of FDT and mfVEP tests in normal, suspect, and glaucomatous eyes and compare the monocular and interocuar mf VEP.Methods: Ninety-five eyes from 95 individuals (23 controls, 33 glaucoma suspects, 39 glaucomatous were enrolled. All participants underwent a full ophthalmic examination, followed by SAP, FDT, and mfVEP tests. Results: The area under the curve for mean deviation and pattern standard deviation were 0.756 and 0.761, respectively, for FDT, 0.564 and 0.512 for signal and alpha for interocular mfVEP, and 0.568 and 0.538 for signal and alpha for monocular mfVEP. This difference between monocular and interocular mfVEP was not significant. Conclusion: The FDT matrix was superior to mfVEP in glaucoma detection. The difference between monocular and interocular mfVEP in the diagnosis of glaucoma was not significant. Keywords: standard automated perimetry, electrophysiology, glaucomatous eyes

  20. Experience-dependent expression of Nogo-A and Nogo receptor in the developing rat visual cortex

    Institute of Scientific and Technical Information of China (English)

    Xiaoying Wu; Yulin Luo; Shuangzhen Liu; Kuanshu Li

    2012-01-01

    Nogo-A and Nogo receptor (NgR) expression in the visual cortex following a critical developmental period (postnatal days 20-60) has been previously shown. However, little is known regarding Nogo-A and NgR expression between postnatal day 0 and initiation of the critical period. The present study analyzed Nogo-A and NgR expression at four different time points: postnatal day 0 (P0), before critical period (P14), during critical period (P28), and after critical period (P60). Results showed significantly increased Nogo-A mRNA and protein expression levels in the visual cortex following birth, and expression levels remained steady between P28 and P60. NgR mRNA or protein expression was dramatically upregulated with age and peaked at P14 or P28, respectively, and maintained high expression to P60. In addition, Nogo-A and NgR expression was analyzed in each visual cortex layer in normal developing rats and rats with monocular deprivation. Monocular deprivation decreased Nogo-A and NgR mRNA and protein expression in the rat visual cortex, in particular in layers II-III and IV in the visual cortex contralateral to the deprived eye. These findings suggested that Nogo-A and NgR regulated termination of the critical period in experience- dependent visual cortical plasticity.