Abnormal tuning of saccade-related cells in pontine reticular formation of strabismic monkeys.

PubMed

Walton, Mark M G; Mustari, Michael J

2015-08-01

Strabismus is a common disorder, characterized by a chronic misalignment of the eyes and numerous visual and oculomotor abnormalities. For example, saccades are often highly disconjugate. For humans with pattern strabismus, the horizontal and vertical disconjugacies vary with eye position. In monkeys, manipulations that disturb binocular vision during the first several weeks of life result in a chronic strabismus with characteristics that closely match those in human patients. Early onset strabismus is associated with altered binocular sensitivity of neurons in visual cortex. Here we test the hypothesis that brain stem circuits specific to saccadic eye movements are abnormal. We targeted the pontine paramedian reticular formation, a structure that directly projects to the ipsilateral abducens nucleus. In normal animals, neurons in this structure are characterized by a high-frequency burst of spikes associated with ipsiversive saccades. We recorded single-unit activity from 84 neurons from four monkeys (two normal, one exotrope, and one esotrope), while they made saccades to a visual target on a tangent screen. All 24 neurons recorded from the normal animals had preferred directions within 30° of pure horizontal. For the strabismic animals, the distribution of preferred directions was normal on one side of the brain, but highly variable on the other. In fact, 12/60 neurons recorded from the strabismic animals preferred vertical saccades. Many also had unusually weak or strong bursts. These data suggest that the loss of corresponding binocular vision during infancy impairs the development of normal tuning characteristics for saccade-related neurons in brain stem. Copyright © 2015 the American Physiological Society.

3D morphology reconstruction using linear array CCD binocular stereo vision imaging system

NASA Astrophysics Data System (ADS)

Pan, Yu; Wang, Jinjiang

2018-01-01

Binocular vision imaging system, which has a small field of view, cannot reconstruct the 3-D shape of the dynamic object. We found a linear array CCD binocular vision imaging system, which uses different calibration and reconstruct methods. On the basis of the binocular vision imaging system, the linear array CCD binocular vision imaging systems which has a wider field of view can reconstruct the 3-D morphology of objects in continuous motion, and the results are accurate. This research mainly introduces the composition and principle of linear array CCD binocular vision imaging system, including the calibration, capture, matching and reconstruction of the imaging system. The system consists of two linear array cameras which were placed in special arrangements and a horizontal moving platform that can pick up objects. The internal and external parameters of the camera are obtained by calibrating in advance. And then using the camera to capture images of moving objects, the results are then matched and 3-D reconstructed. The linear array CCD binocular vision imaging systems can accurately measure the 3-D appearance of moving objects, this essay is of great significance to measure the 3-D morphology of moving objects.

Clinical and ocular motor analysis of the infantile nystagmus syndrome in the first 6 months of life.

PubMed

Hertle, R W; Maldanado, V K; Maybodi, M; Yang, D

2002-06-01

The infantile nystagmus syndrome (INS) usually begins in infancy and may or may not be associated with visual sensory system abnormalities. Little is known about its specific waveforms in the first 6 months of life or their relation to the developing visual system. This study identifies the clinical and ocular motility characteristics of the INS and establishes the range of waveforms present in the first 6 months of life. 27 infants with involuntary ocular oscillations typical of INS are included in this analysis. They were evaluated both clinically and with motility recordings. Eye movement analysis was performed off line from computer analysis of digitised data. Variables analysed included age, sex, vision, ocular abnormalities, head position, and null zone, neutral zone characteristics, symmetry, conjugacy, waveforms, frequencies, and foveation times. Ages ranged from 3 to 6.5 months (average 4.9 months). 15 patients (56%) had abnormal vision for age, nine (33%) had strabismus, five (19%) had an anomalous head posture, 13 (48%) had oculographic null and neutral positions, nine (33%) had binocular asymmetry, and only two showed consistent dysconjugacy. Average binocular frequency was 3.3 Hz, monocular frequency 6.6 Hz. Average foveation periods were longer and more "jerk" wave forms were observed in those patients with normal vision. Common clinical characteristics and eye movement waveforms of INS begin in the first few months of infancy and waveform analysis at this time may help with both diagnosis and visual status.

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

PubMed Central

Shooner, Christopher; Kelly, Jenna G.; García-Marín, Virginia; Movshon, J. Anthony; Kiorpes, Lynne

2017-01-01

In amblyopia, a visual disorder caused by abnormal visual experience during development, the amblyopic eye (AE) loses visual sensitivity whereas the fellow eye (FE) is largely unaffected. Binocular vision in amblyopes is often disrupted by interocular suppression. We used 96-electrode arrays to record neurons and neuronal groups in areas V1 and V2 of six female macaque monkeys (Macaca nemestrina) made amblyopic by artificial strabismus or anisometropia in early life, as well as two visually normal female controls. To measure suppressive binocular interactions directly, we recorded neuronal responses to dichoptic stimulation. We stimulated both eyes simultaneously with large sinusoidal gratings, controlling their contrast independently with raised-cosine modulators of different orientations and spatial frequencies. We modeled each eye's receptive field at each cortical site using a difference of Gaussian envelopes and derived estimates of the strength of central excitation and surround suppression. We used these estimates to calculate ocular dominance separately for excitation and suppression. Excitatory drive from the FE dominated amblyopic visual cortex, especially in more severe amblyopes, but suppression from both the FE and AEs was prevalent in all animals. This imbalance created strong interocular suppression in deep amblyopes: increasing contrast in the AE decreased responses at binocular cortical sites. These response patterns reveal mechanisms that likely contribute to the interocular suppression that disrupts vision in amblyopes. SIGNIFICANCE STATEMENT Amblyopia is a developmental visual disorder that alters both monocular vision and binocular interaction. Using microelectrode arrays, we examined binocular interaction in primary visual cortex and V2 of six amblyopic macaque monkeys (Macaca nemestrina) and two visually normal controls. By stimulating the eyes dichoptically, we showed that, in amblyopic cortex, the binocular combination of signals is altered. The excitatory influence of the two eyes is imbalanced to a degree that can be predicted from the severity of amblyopia, whereas suppression from both eyes is prevalent in all animals. This altered balance of excitation and suppression reflects mechanisms that may contribute to the interocular perceptual suppression that disrupts vision in amblyopes. PMID:28743725

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

PubMed

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

2017-08-23

In amblyopia, a visual disorder caused by abnormal visual experience during development, the amblyopic eye (AE) loses visual sensitivity whereas the fellow eye (FE) is largely unaffected. Binocular vision in amblyopes is often disrupted by interocular suppression. We used 96-electrode arrays to record neurons and neuronal groups in areas V1 and V2 of six female macaque monkeys ( Macaca nemestrina ) made amblyopic by artificial strabismus or anisometropia in early life, as well as two visually normal female controls. To measure suppressive binocular interactions directly, we recorded neuronal responses to dichoptic stimulation. We stimulated both eyes simultaneously with large sinusoidal gratings, controlling their contrast independently with raised-cosine modulators of different orientations and spatial frequencies. We modeled each eye's receptive field at each cortical site using a difference of Gaussian envelopes and derived estimates of the strength of central excitation and surround suppression. We used these estimates to calculate ocular dominance separately for excitation and suppression. Excitatory drive from the FE dominated amblyopic visual cortex, especially in more severe amblyopes, but suppression from both the FE and AEs was prevalent in all animals. This imbalance created strong interocular suppression in deep amblyopes: increasing contrast in the AE decreased responses at binocular cortical sites. These response patterns reveal mechanisms that likely contribute to the interocular suppression that disrupts vision in amblyopes. SIGNIFICANCE STATEMENT Amblyopia is a developmental visual disorder that alters both monocular vision and binocular interaction. Using microelectrode arrays, we examined binocular interaction in primary visual cortex and V2 of six amblyopic macaque monkeys ( Macaca nemestrina ) and two visually normal controls. By stimulating the eyes dichoptically, we showed that, in amblyopic cortex, the binocular combination of signals is altered. The excitatory influence of the two eyes is imbalanced to a degree that can be predicted from the severity of amblyopia, whereas suppression from both eyes is prevalent in all animals. This altered balance of excitation and suppression reflects mechanisms that may contribute to the interocular perceptual suppression that disrupts vision in amblyopes. Copyright © 2017 the authors 0270-6474/17/378216-11$15.00/0.

Amblyopia and Binocular Vision

PubMed Central

Birch, Eileen E.

2012-01-01

Amblyopia is the most common cause of monocular visual loss in children, affecting 1.3% to 3.6% of children. Current treatments are effective in reducing the visual acuity deficit but many amblyopic individuals are left with residual visual acuity deficits, ocular motor abnormalities, deficient fine motor skills, and risk for recurrent amblyopia. Using a combination of psychophysical, electrophysiological, imaging, risk factor analysis, and fine motor skill assessment, the primary role of binocular dysfunction in the genesis of amblyopia and the constellation of visual and motor deficits that accompany the visual acuity deficit has been identified. These findings motivated us to evaluate a new, binocular approach to amblyopia treatment with the goals of reducing or eliminating residual and recurrent amblyopia and of improving the deficient ocular motor function and fine motor skills that accompany amblyopia. PMID:23201436

Origins of strabismus and loss of binocular vision

PubMed Central

Bui Quoc, Emmanuel; Milleret, Chantal

2014-01-01

Strabismus is a frequent ocular disorder that develops early in life in humans. As a general rule, it is characterized by a misalignment of the visual axes which most often appears during the critical period of visual development. However other characteristics of strabismus may vary greatly among subjects, for example, being convergent or divergent, horizontal or vertical, with variable angles of deviation. Binocular vision may also vary greatly. Our main goal here is to develop the idea that such “polymorphy” reflects a wide variety in the possible origins of strabismus. We propose that strabismus must be considered as possibly resulting from abnormal genetic and/or acquired factors, anatomical and/or functional abnormalities, in the sensory and/or the motor systems, both peripherally and/or in the brain itself. We shall particularly develop the possible “central” origins of strabismus. Indeed, we are convinced that it is time now to open this “black box” in order to move forward. All of this will be developed on the basis of both presently available data in literature (including most recent data) and our own experience. Both data in biology and medicine will be referred to. Our conclusions will hopefully help ophthalmologists to better understand strabismus and to develop new therapeutic strategies in the future. Presently, physicians eliminate or limit the negative effects of such pathology both on the development of the visual system and visual perception through the use of optical correction and, in some cases, extraocular muscle surgery. To better circumscribe the problem of the origins of strabismus, including at a cerebral level, may improve its management, in particular with respect to binocular vision, through innovating tools by treating the pathology at the source. PMID:25309358

The dependence of binocular contrast sensitivities on binocular single vision in normal and amblyopic human subjects

PubMed Central

Hood, A S; Morrison, J D

2002-01-01

We have measured monocular and binocular contrast sensitivities in response to medium to high spatial frequencies of vertical sinusoidal grating patterns in normal subjects, anisometropic amblyopes, strabismic amblyopes and non-amblyopic esotropes. On binocular viewing, contrast sensitivities were slightly but significantly increased in normal subjects, markedly increased in anisometropes and esotropes with anomalous binocular single vision (BSV) and significantly reduced in esotropes and exotropes without BSV. Application of a prismatic correction to the strabismic eye in order to achieve bifoveal stimulation resulted in a significant reduction in contrast sensitivity in esotropes with and without anomalous BSV, in exotropes and in non-amblyopic esotropes. Control experiments in normal subjects with monocular viewing showed that degradative effects of the prism occurred only with high prism powers and at high spatial frequencies, thus establishing that the reduced contrast sensitivities were the consequence of bifoveal stimulation rather than optical degradation. Displacement of the image of the grating pattern by 2 deg in normal subjects and anisometropes by a dichoptic method to simulate a small angle esotropia had no effect on the contrast sensitivities recorded through the companion eye. By contrast, esotropes showed similar reductions in contrast sensitivity to those obtained with the prism experiments, confirming a fundamental difference between subjects with normal and abnormal ocular alignments. The results have thus established a suppressive action of the fovea of the amblyopic eye acting on the companion, non-amblyopic eye and indicate that correction of ocular misalignments in adult esotropes may be disadvantageous to binocular visual performance. PMID:11956347

Efficacy of vision therapy in children with learning disability and associated binocular vision anomalies.

PubMed

Hussaindeen, Jameel Rizwana; Shah, Prerana; Ramani, Krishna Kumar; Ramanujan, Lalitha

To report the frequency of binocular vision (BV) anomalies in children with specific learning disorders (SLD) and to assess the efficacy of vision therapy (VT) in children with a non-strabismic binocular vision anomaly (NSBVA). The study was carried out at a centre for learning disability (LD). Comprehensive eye examination and binocular vision assessment was carried out for 94 children (mean (SD) age: 15 (2.2) years) diagnosed with specific learning disorder. BV assessment was done for children with best corrected visual acuity of ≥6/9 - N6, cooperative for examination and free from any ocular pathology. For children with a diagnosis of NSBVA (n=46), 24 children were randomized to VT and no intervention was provided to the other 22 children who served as experimental controls. At the end of 10 sessions of vision therapy, BV assessment was performed for both the intervention and non-intervention groups. Binocular vision anomalies were found in 59 children (62.8%) among which 22% (n=13) had strabismic binocular vision anomalies (SBVA) and 78% (n=46) had a NSBVA. Accommodative infacility (AIF) was the commonest of the NSBVA and found in 67%, followed by convergence insufficiency (CI) in 25%. Post-vision therapy, the intervention group showed significant improvement in all the BV parameters (Wilcoxon signed rank test, p<0.05) except negative fusional vergence. Children with specific learning disorders have a high frequency of binocular vision disorders and vision therapy plays a significant role in improving the BV parameters. Children with SLD should be screened for BV anomalies as it could potentially be an added hindrance to the reading difficulty in this special population. Copyright © 2017 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.

Deficient Binocular Combination Reveals Mechanisms of Anisometropic Amblyopia: Signal Attenuation and Interocular Inhibition

PubMed Central

Huang, Chang-Bing; Zhou, Jiawei; Lu, Zhong-Lin; Zhou, Yifeng

2012-01-01

Amblyopia is a developmental disorder that results in deficits of monocular and binocular vision. It's presently unclear whether these deficits result from attenuation of signals in the amblyopic eye, inhibition by signals in the fellow eye, or both. In this study, we characterize the mechanisms underlying anisometropic amblyopia using a binocular phase and contrast combination paradigm and a contrast-gain control model. Subjects dichoptically viewed two slightly different images and reported the perceived contrast and phase of the resulting cyclopean percept. We found that the properties of binocular combination were abnormal in many aspects, which is explained by a combination of (1) attenuated monocular signal in the amblyopic eye, (2) stronger interocular contrast-gain control from the fellow eye to the signal in amblyopic eye (direct interocular inhibition), and (3) stronger interocular contrast-gain control from the fellow eye to the contrast gain control signal from the amblyopic eye (indirect interocular inhibition). We conclude that anisometropic amblyopia led to both monocular and interocular deficits. A complete understanding of the mechanisms underlying amblyopia requires studies of both monocular deficits and binocular interactions. PMID:21546609

Amblyopia and binocular vision.

PubMed

Birch, Eileen E

2013-03-01

Amblyopia is the most common cause of monocular visual loss in children, affecting 1.3%-3.6% of children. Current treatments are effective in reducing the visual acuity deficit but many amblyopic individuals are left with residual visual acuity deficits, ocular motor abnormalities, deficient fine motor skills, and risk for recurrent amblyopia. Using a combination of psychophysical, electrophysiological, imaging, risk factor analysis, and fine motor skill assessment, the primary role of binocular dysfunction in the genesis of amblyopia and the constellation of visual and motor deficits that accompany the visual acuity deficit has been identified. These findings motivated us to evaluate a new, binocular approach to amblyopia treatment with the goals of reducing or eliminating residual and recurrent amblyopia and of improving the deficient ocular motor function and fine motor skills that accompany amblyopia. Copyright © 2012 Elsevier Ltd. All rights reserved.

Optimization of Stereo Matching in 3D Reconstruction Based on Binocular Vision

NASA Astrophysics Data System (ADS)

Gai, Qiyang

2018-01-01

Stereo matching is one of the key steps of 3D reconstruction based on binocular vision. In order to improve the convergence speed and accuracy in 3D reconstruction based on binocular vision, this paper adopts the combination method of polar constraint and ant colony algorithm. By using the line constraint to reduce the search range, an ant colony algorithm is used to optimize the stereo matching feature search function in the proposed search range. Through the establishment of the stereo matching optimization process analysis model of ant colony algorithm, the global optimization solution of stereo matching in 3D reconstruction based on binocular vision system is realized. The simulation results show that by the combining the advantage of polar constraint and ant colony algorithm, the stereo matching range of 3D reconstruction based on binocular vision is simplified, and the convergence speed and accuracy of this stereo matching process are improved.

Rebalancing binocular vision in amblyopia.

PubMed

Ding, Jian; Levi, Dennis M

2014-03-01

Humans with amblyopia have an asymmetry in binocular vision: neural signals from the amblyopic eye are suppressed in the cortex by the fellow eye. The purpose of this study was to develop new models and methods for rebalancing this asymmetric binocular vision by manipulating the contrast and luminance in the two eyes. We measured the perceived phase of a cyclopean sinewave by asking normal and amblyopic observers to indicate the apparent location (phase) of the dark trough in the horizontal cyclopean sine wave relative to a black horizontal reference line, and used the same stimuli to measure perceived contrast by matching the binocular combined contrast to a standard contrast presented to one eye. We varied both the relative contrast and luminance of the two eyes' inputs, in order to rebalance the asymmetric binocular vision. Amblyopic binocular vision becomes more and more asymmetric the higher the stimulus contrast or spatial frequency. Reanalysing our previous data, we found that, at a given spatial frequency, the binocular asymmetry could be described by a log-linear formula with two parameters, one for the maximum asymmetry and one for the rate at which the binocular system becomes asymmetric as the contrast increases. Our new data demonstrates that reducing the dominant eye's mean luminance reduces its suppression of the non-dominant eye, and therefore rebalances the asymmetric binocular vision. While the binocular asymmetry in amblyopic vision can be rebalanced by manipulating the relative contrast or luminance of the two eyes at a given spatial frequency and contrast, it is very difficult or even impossible to rebalance the asymmetry for all visual conditions. Nonetheless, wearing a neutral density filter before the dominant eye (or increasing the mean luminance in the non-dominant eye) may be more beneficial than the traditional method of patching the dominant eye for treating amblyopia. © 2014 The Authors Ophthalmic & Physiological Optics © 2014 The College of Optometrists.

Relating binocular and monocular vision in strabismic and anisometropic amblyopia.

PubMed

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

2006-06-01

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

Correcting intermittent central suppression improves binocular marksmanship.

PubMed

Hussey, Eric S

2007-04-01

Intermittent central suppression (ICS) is a defect in normal binocular (two-eyed) vision that causes confusion in visual detail. ICS is a repetitive intermittent loss of visual sensation in the central area of vision. As the central vision of either eye "turns on and off", aiming errors in sight can occur that must be corrected when both eyes are seeing again. Any aiming errors in sight might be expected to interfere with marksmanship during two-eyed seeing. We compared monocular (one-eyed, patched) and binocular (two-eyed) marksmanship with pistol shooting with an Army ROTC cadet before and after successful therapy for diagnosed ICS. Pretreatment, monocular marksmanship was significantly better than binocular marksmanship, suggesting defective binocularity reduced accuracy. After treatment for ICS, binocular and monocular marksmanship were essentially the same. Results confirmed predictions that with increased visual stability from correcting the suppression, binocular and monocular marksmanship accuracies should merge.

Binocular adaptive optics visual simulator.

PubMed

Fernández, Enrique J; Prieto, Pedro M; Artal, Pablo

2009-09-01

A binocular adaptive optics visual simulator is presented. The instrument allows for measuring and manipulating ocular aberrations of the two eyes simultaneously, while the subject performs visual testing under binocular vision. An important feature of the apparatus consists on the use of a single correcting device and wavefront sensor. Aberrations are controlled by means of a liquid-crystal-on-silicon spatial light modulator, where the two pupils of the subject are projected. Aberrations from the two eyes are measured with a single Hartmann-Shack sensor. As an example of the potential of the apparatus for the study of the impact of the eye's aberrations on binocular vision, results of contrast sensitivity after addition of spherical aberration are presented for one subject. Different binocular combinations of spherical aberration were explored. Results suggest complex binocular interactions in the presence of monochromatic aberrations. The technique and the instrument might contribute to the better understanding of binocular vision and to the search for optimized ophthalmic corrections.

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

PubMed

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

2013-04-01

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

Neural mechanisms of oculomotor abnormalities in the infantile strabismus syndrome.

PubMed

Walton, Mark M G; Pallus, Adam; Fleuriet, Jérome; Mustari, Michael J; Tarczy-Hornoch, Kristina

2017-07-01

Infantile strabismus is characterized by numerous visual and oculomotor abnormalities. Recently nonhuman primate models of infantile strabismus have been established, with characteristics that closely match those observed in human patients. This has made it possible to study the neural basis for visual and oculomotor symptoms in infantile strabismus. In this review, we consider the available evidence for neural abnormalities in structures related to oculomotor pathways ranging from visual cortex to oculomotor nuclei. These studies provide compelling evidence that a disturbance of binocular vision during a sensitive period early in life, whatever the cause, results in a cascade of abnormalities through numerous brain areas involved in visual functions and eye movements. Copyright © 2017 the American Physiological Society.

When two eyes are better than one in prehension: monocular viewing and end-point variance.

PubMed

Loftus, Andrea; Servos, Philip; Goodale, Melvyn A; Mendarozqueta, Nicole; Mon-Williams, Mark

2004-10-01

Previous research has suggested that binocular vision plays an important role in prehension. It has been shown that removing binocular vision affects (negatively) both the planning and on-line control of prehension. It has been suggested that the adverse impact of removing binocular vision is because monocular viewing results in an underestimation of target distance in visuomotor tasks. This suggestion is based on the observation that the kinematics of prehension are altered when viewing monocularly. We argue that it is not possible to draw unambiguous conclusions regarding the accuracy of distance perception from these data. In experiment 1, we found data that contradict the idea that a consistent visuomotor underestimation of target distance is an inevitable consequence of monocular viewing. Our data did show, however, that positional variance increases under monocular viewing. We provide an alternative explanation for the kinematic changes found when binocular vision is removed. Our account is based on the changes in movement kinematics that occur when end-point variance is altered following the removal of binocular vision. We suggest that the removal of binocular vision leads to greater perceptual uncertainty (e.g. less precise stimulus cues), resulting in changes in the kinematics of the movement (longer duration movements). Our alternative account reconciles some differences within the research literature. We conducted a series of experiments to explore further the issue of when binocular information is advantageous in prehension. Three subsequent experiments were employed which varied binocular/monocular viewing in selectively lit conditions. Experiment 2 explored the differences in prehension measured between monocular and binocular viewing in a full cue environment with a continuous view of the target object. Experiment 3 required participants to reach, under a monocular or binocular view, for a continuously visible self-illuminated target object in an otherwise dark room. In Experiment 3, the participant could neither see the target object nor the reaching hand following initiation of the prehension movement. Our results suggest that binocular vision contributes to prehension by providing additional information (cues) to the nervous system. These cues appear to be weighted differentially according to the particular constellation of stimulus cues available to the participants when reaching to grasp. One constant advantage of a binocular view appears to be the provision of on-line information regarding the position of the hand relative to the target. In reduced cue conditions (i.e. where a view of the target object is lost following initiation of the movement), binocular information regarding target location appears to be particularly useful in the initial programming of reach distance. Our results are a step towards establishing the specific contributions that binocular vision makes to the control of prehension.

A novel vibration measurement and active control method for a hinged flexible two-connected piezoelectric plate

NASA Astrophysics Data System (ADS)

Qiu, Zhi-cheng; Wang, Xian-feng; Zhang, Xian-Min; Liu, Jin-guo

2018-07-01

A novel non-contact vibration measurement method using binocular vision sensors is proposed for piezoelectric flexible hinged plate. Decoupling methods of the bending and torsional low frequency vibration on measurement and driving control are investigated, using binocular vision sensors and piezoelectric actuators. A radial basis function neural network controller (RBFNNC) is designed to suppress both the larger and the smaller amplitude vibrations. To verify the non-contact measurement method and the designed controller, an experimental setup of the flexible hinged plate with binocular vision is constructed. Experiments on vibration measurement and control are conducted by using binocular vision sensors and the designed RBFNNC controllers, compared with the classical proportional and derivative (PD) control algorithm. The experimental measurement results demonstrate that the binocular vision sensors can detect the low-frequency bending and torsional vibration effectively. Furthermore, the designed RBF can suppress the bending vibration more quickly than the designed PD controller owing to the adjustment of the RBF control, especially for the small amplitude residual vibrations.

Research on three-dimensional reconstruction method based on binocular vision

NASA Astrophysics Data System (ADS)

Li, Jinlin; Wang, Zhihui; Wang, Minjun

2018-03-01

As the hot and difficult issue in computer vision, binocular stereo vision is an important form of computer vision,which has a broad application prospects in many computer vision fields,such as aerial mapping,vision navigation,motion analysis and industrial inspection etc.In this paper, a research is done into binocular stereo camera calibration, image feature extraction and stereo matching. In the binocular stereo camera calibration module, the internal parameters of a single camera are obtained by using the checkerboard lattice of zhang zhengyou the field of image feature extraction and stereo matching, adopted the SURF operator in the local feature operator and the SGBM algorithm in the global matching algorithm are used respectively, and the performance are compared. After completed the feature points matching, we can build the corresponding between matching points and the 3D object points using the camera parameters which are calibrated, which means the 3D information.

Clinically Normal Stereopsis Does Not Ensure Performance Benefit from Stereoscopic 3D Depth Cues

DTIC Science & Technology

2014-10-28

Stereopsis, Binocular Vision, Optometry , Depth Perception, 3D vision, 3D human factors, Stereoscopic displays, S3D, Virtual environment 16...Binocular Vision, Optometry , Depth Perception, 3D vision, 3D human factors, Stereoscopic displays, S3D, Virtual environment 1 Distribution A: Approved

Restoration of binocular vision in amblyopia.

PubMed

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

2011-09-01

To develop a treatment for amblyopia based on re-establishing binocular vision. A novel procedure is outlined for measuring and reducing the extent to which the fixing eye suppresses the fellow amblyopic eye in adults with amblyopia. We hypothesize that suppression renders a structurally binocular system, functionally monocular. We demonstrate that strabismic amblyopes can combine information normally between their eyes under viewing conditions where suppression is reduced by presenting stimuli of different contrast to each eye. Furthermore we show that prolonged periods of binocular combination leads to a strengthening of binocular vision in strabismic amblyopes and eventual combination of binocular information under natural viewing conditions (stimuli of the same contrast in each eye). Concomitant improvement in monocular acuity of the amblyopic eye occurs with this reduction in suppression and strengthening of binocular fusion. Additionally, stereoscopic function was established in the majority of patients tested. We have implemented this approach on a headmounted device as well as on a handheld iPod. This provides the basis for a new treatment of amblyopia, one that is purely binocular and aimed at reducing suppression as a first step.

Assessing Binocular Advantage in Aided Vision

DTIC Science & Technology

2014-06-01

2005; 5800:55-64 18. Hayhoe M, Gillam B, Chajka K, Vecellio E. The role of binocular vision in walking. Vis Neurosci 2009 Jan-Feb; 26(1):73-80 19...grains model. Cogn Psychol 2003 Mar; 46(2):101-51 30. Minucci P, Connors M. Reaction time under three viewing conditions: binocular, dominant eye

A binocular iPad treatment for amblyopic children.

PubMed

Li, S L; Jost, R M; Morale, S E; Stager, D R; Dao, L; Stager, D; Birch, E E

2014-10-01

Monocular amblyopia treatment (patching or penalization) does not always result in 6/6 vision and amblyopia often recurs. As amblyopia arises from abnormal binocular visual experience, we evaluated the effectiveness of a novel home-based binocular amblyopia treatment. Children (4-12 y) wore anaglyphic glasses to play binocular games on an iPad platform for 4 h/w for 4 weeks. The first 25 children were assigned to sham games and then 50 children to binocular games. Children in the binocular group had the option of participating for an additional 4 weeks. Compliance was monitored with calendars and tracking fellow eye contrast settings. About half of the children in each group were also treated with patching at a different time of day. Best-corrected visual acuity, suppression, and stereoacuity were measured at baseline, at the 4- and 8-week outcome visits, and 3 months after cessation of treatment. Mean (±SE) visual acuity improved in the binocular group from 0.47±0.03 logMAR at baseline to 0.39±0.03 logMAR at 4 weeks (P<0.001); there was no significant change for the sham group. The effect of binocular games on visual acuity did not differ for children who were patched vs those who were not. The median stereoacuity remained unchanged in both groups. An additional 4 weeks of treatment did not yield additional visual acuity improvement. Visual acuity improvements were maintained for 3 months after the cessation of treatment. Binocular iPad treatment rapidly improved visual acuity, and visual acuity was stable for at least 3 months following the cessation of treatment.

[The lazy eye - contemporary strategies of amblyopia treatment].

PubMed

Sturm, V

2011-02-16

Amblyopia is a condition of decreased monocular or binocular visual acuity caused by form deprivation or abnormal binocular interaction. Amblyopia is the most common cause of monocular vision loss in children with a prevalence of 2 to 5%. During the last decade, several prospective randomized studies have influenced our clinical management. Based on these studies, optimum refractive correction should be prescribed first. However, most patients will need additional occlusion therapy which is still considered the «gold standard» of amblyopia management. Now much lower doses have been shown to be effective. In moderate amblyopia, penalization with atropine is as effective as patching. New treatment modalities including perceptual learning, pharmacotherapy with levodopa and citicholine or transcranial magnetic stimulation have not yet been widely accepted.

The research of binocular vision ranging system based on LabVIEW

NASA Astrophysics Data System (ADS)

Li, Shikuan; Yang, Xu

2017-10-01

Based on the study of the principle of binocular parallax ranging, a binocular vision ranging system is designed and built. The stereo matching algorithm is realized by LabVIEW software. The camera calibration and distance measurement are completed. The error analysis shows that the system fast, effective, can be used in the corresponding industrial occasions.

Binocular Vision

PubMed Central

Blake, Randolph; Wilson, Hugh

2010-01-01

This essay reviews major developments –empirical and theoretical –in the field of binocular vision during the last 25 years. We limit our survey primarily to work on human stereopsis, binocular rivalry and binocular contrast summation, with discussion where relevant of single-unit neurophysiology and human brain imaging. We identify several key controversies that have stimulated important work on these problems. In the case of stereopsis those controversies include position versus phase encoding of disparity, dependence of disparity limits on spatial scale, role of occlusion in binocular depth and surface perception, and motion in 3D. In the case of binocular rivalry, controversies include eye versus stimulus rivalry, role of “top-down” influences on rivalry dynamics, and the interaction of binocular rivalry and stereopsis. Concerning binocular contrast summation, the essay focuses on two representative models that highlight the evolving complexity in this field of study. PMID:20951722

Noisy Spiking in Visual Area V2 of Amblyopic Monkeys.

PubMed

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

2017-01-25

Interocular decorrelation of input signals in developing visual cortex can cause impaired binocular vision and amblyopia. Although increased intrinsic noise is thought to be responsible for a range of perceptual deficits in amblyopic humans, the neural basis for the elevated perceptual noise in amblyopic primates is not known. Here, we tested the idea that perceptual noise is linked to the neuronal spiking noise (variability) resulting from developmental alterations in cortical circuitry. To assess spiking noise, we analyzed the contrast-dependent dynamics of spike counts and spiking irregularity by calculating the square of the coefficient of variation in interspike intervals (CV 2 ) and the trial-to-trial fluctuations in spiking, or mean matched Fano factor (m-FF) in visual area V2 of monkeys reared with chronic monocular defocus. In amblyopic neurons, the contrast versus response functions and the spike count dynamics exhibited significant deviations from comparable data for normal monkeys. The CV 2 was pronounced in amblyopic neurons for high-contrast stimuli and the m-FF was abnormally high in amblyopic neurons for low-contrast gratings. The spike count, CV 2 , and m-FF of spontaneous activity were also elevated in amblyopic neurons. These contrast-dependent spiking irregularities were correlated with the level of binocular suppression in these V2 neurons and with the severity of perceptual loss for individual monkeys. Our results suggest that the developmental alterations in normalization mechanisms resulting from early binocular suppression can explain much of these contrast-dependent spiking abnormalities in V2 neurons and the perceptual performance of our amblyopic monkeys. Amblyopia is a common developmental vision disorder in humans. Despite the extensive animal studies on how amblyopia emerges, we know surprisingly little about the neural basis of amblyopia in humans and nonhuman primates. Although the vision of amblyopic humans is often described as being noisy by perceptual and modeling studies, the exact nature or origin of this elevated perceptual noise is not known. We show that elevated and noisy spontaneous activity and contrast-dependent noisy spiking (spiking irregularity and trial-to-trial fluctuations in spiking) in neurons of visual area V2 could limit the visual performance of amblyopic primates. Moreover, we discovered that the noisy spiking is linked to a high level of binocular suppression in visual cortex during development. Copyright © 2017 the authors 0270-6474/17/370922-14$15.00/0.

Binocular vision in amblyopia: structure, suppression and plasticity.

PubMed

Hess, Robert F; Thompson, Benjamin; Baker, Daniel H

2014-03-01

The amblyopic visual system was once considered to be structurally monocular. However, it now evident that the capacity for binocular vision is present in many observers with amblyopia. This has led to new techniques for quantifying suppression that have provided insights into the relationship between suppression and the monocular and binocular visual deficits experienced by amblyopes. Furthermore, new treatments are emerging that directly target suppressive interactions within the visual cortex and, on the basis of initial data, appear to improve both binocular and monocular visual function, even in adults with amblyopia. The aim of this review is to provide an overview of recent studies that have investigated the structure, measurement and treatment of binocular vision in observers with strabismic, anisometropic and mixed amblyopia. © 2014 The Authors Ophthalmic & Physiological Optics © 2014 The College of Optometrists.

Colour helps to solve the binocular matching problem

PubMed Central

den Ouden, HEM; van Ee, R; de Haan, EHF

2005-01-01

The spatial differences between the two retinal images, called binocular disparities, can be used to recover the three-dimensional (3D) aspects of a scene. The computation of disparity depends upon the correct identification of corresponding features in the two images. Understanding what image features are used by the brain to solve this binocular matching problem is an important issue in research on stereoscopic vision. The role of colour in binocular vision is controversial and it has been argued that colour is ineffective in achieving binocular vision. In the current experiment subjects were required to indicate the amount of perceived depth. The stimulus consisted of an array of fronto-parallel bars uniformly distributed in a constant sized volume. We studied the perceived depth in those 3D stimuli by manipulating both colour (monochrome, trichrome) and luminance (congruent, incongruent). Our results demonstrate that the amount of perceived depth was influenced by colour, indicating that the visual system uses colour to achieve binocular matching. Physiological data have revealed cortical cells in macaque V2 that are tuned both to binocular disparity and to colour. We suggest that one of the functional roles of these cells may be to help solve the binocular matching problem. PMID:15975983

Colour helps to solve the binocular matching problem.

PubMed

den Ouden, H E M; van Ee, R; de Haan, E H F

2005-09-01

The spatial differences between the two retinal images, called binocular disparities, can be used to recover the three-dimensional (3D) aspects of a scene. The computation of disparity depends upon the correct identification of corresponding features in the two images. Understanding what image features are used by the brain to solve this binocular matching problem is an important issue in research on stereoscopic vision. The role of colour in binocular vision is controversial and it has been argued that colour is ineffective in achieving binocular vision. In the current experiment subjects were required to indicate the amount of perceived depth. The stimulus consisted of an array of fronto-parallel bars uniformly distributed in a constant sized volume. We studied the perceived depth in those 3D stimuli by manipulating both colour (monochrome, trichrome) and luminance (congruent, incongruent). Our results demonstrate that the amount of perceived depth was influenced by colour, indicating that the visual system uses colour to achieve binocular matching. Physiological data have revealed cortical cells in macaque V2 that are tuned both to binocular disparity and to colour. We suggest that one of the functional roles of these cells may be to help solve the binocular matching problem.

Three-dimensional ocular kinematics underlying binocular single vision

PubMed Central

Misslisch, H.

2016-01-01

We have analyzed the binocular coordination of the eyes during far-to-near refixation saccades based on the evaluation of distance ratios and angular directions of the projected target images relative to the eyes' rotation centers. By defining the geometric point of binocular single vision, called Helmholtz point, we found that disparities during fixations of targets at near distances were limited in the subject's three-dimensional visual field to the vertical and forward directions. These disparities collapsed to simple vertical disparities in the projective binocular image plane. Subjects were able to perfectly fuse the vertically disparate target images with respect to the projected Helmholtz point of single binocular vision, independent of the particular location relative to the horizontal plane of regard. Target image fusion was achieved by binocular torsion combined with corrective modulations of the differential half-vergence angles of the eyes in the horizontal plane. Our findings support the notion that oculomotor control combines vergence in the horizontal plane of regard with active torsion in the frontal plane to achieve fusion of the dichoptic binocular target images. PMID:27655969

An assembly system based on industrial robot with binocular stereo vision

NASA Astrophysics Data System (ADS)

Tang, Hong; Xiao, Nanfeng

2017-01-01

This paper proposes an electronic part and component assembly system based on an industrial robot with binocular stereo vision. Firstly, binocular stereo vision with a visual attention mechanism model is used to get quickly the image regions which contain the electronic parts and components. Secondly, a deep neural network is adopted to recognize the features of the electronic parts and components. Thirdly, in order to control the end-effector of the industrial robot to grasp the electronic parts and components, a genetic algorithm (GA) is proposed to compute the transition matrix and the inverse kinematics of the industrial robot (end-effector), which plays a key role in bridging the binocular stereo vision and the industrial robot. Finally, the proposed assembly system is tested in LED component assembly experiments, and the results denote that it has high efficiency and good applicability.

Visual and binocular status in elementary school children with a reading problem.

PubMed

Christian, Lisa W; Nandakumar, Krithika; Hrynchak, Patricia K; Irving, Elizabeth L

2017-11-21

This descriptive study provides a summary of the binocular anomalies seen in elementary school children identified with reading problems. A retrospective chart review of all children identified with reading problems and seen by the University of Waterloo, Optometry Clinic, from September 2012 to June 2013. Files of 121 children (mean age 8.6 years, range 6-14 years) were reviewed. No significant refractive error was found in 81% of children. Five and 8 children were identified as strabismic at distance and near respectively. Phoria test revealed 90% and 65% of patients had normal distance and near phoria. Near point of convergencia (NPC) was <5cm in 68% of children, and 77% had stereoacuity of ≤40seconds of arc. More than 50% of the children had normal fusional vergence ranges except for near positive fusional vergencce (base out) break (46%). Tests for accommodation showed 91% of children were normal for binocular facility, and approximately 70% of children had an expected accuracy of accommodation. Findings indicate that some children with an identified reading problem also present with abnormal binocular test results compared to published normal values. Further investigation should be performed to investigate the relationship between binocular vision function and reading performance. Crown Copyright © 2017. Published by Elsevier España, S.L.U. All rights reserved.

A binocular iPad treatment for amblyopic children

PubMed Central

Li, S L; Jost, R M; Morale, S E; Stager, D R; Dao, L; Stager, D; Birch, E E

2014-01-01

Purpose Monocular amblyopia treatment (patching or penalization) does not always result in 6/6 vision and amblyopia often recurs. As amblyopia arises from abnormal binocular visual experience, we evaluated the effectiveness of a novel home-based binocular amblyopia treatment. Methods Children (4–12 y) wore anaglyphic glasses to play binocular games on an iPad platform for 4 h/w for 4 weeks. The first 25 children were assigned to sham games and then 50 children to binocular games. Children in the binocular group had the option of participating for an additional 4 weeks. Compliance was monitored with calendars and tracking fellow eye contrast settings. About half of the children in each group were also treated with patching at a different time of day. Best-corrected visual acuity, suppression, and stereoacuity were measured at baseline, at the 4- and 8-week outcome visits, and 3 months after cessation of treatment. Results Mean (±SE) visual acuity improved in the binocular group from 0.47±0.03 logMAR at baseline to 0.39±0.03 logMAR at 4 weeks (P<0.001); there was no significant change for the sham group. The effect of binocular games on visual acuity did not differ for children who were patched vs those who were not. The median stereoacuity remained unchanged in both groups. An additional 4 weeks of treatment did not yield additional visual acuity improvement. Visual acuity improvements were maintained for 3 months after the cessation of treatment. Conclusions Binocular iPad treatment rapidly improved visual acuity, and visual acuity was stable for at least 3 months following the cessation of treatment. PMID:25060850

Avian binocular vision: It's not just about what birds can see, it's also about what they can't.

PubMed

Tyrrell, Luke P; Fernández-Juricic, Esteban

2017-01-01

With the exception of primates, most vertebrates have laterally placed eyes. Binocular vision in vertebrates has been implicated in several functions, including depth perception, contrast discrimination, etc. However, the blind area in front of the head that is proximal to the binocular visual field is often neglected. This anterior blind area is important when discussing the evolution of binocular vision because its relative length is inversely correlated with the width of the binocular field. Therefore, species with wider binocular fields also have shorter anterior blind areas and objects along the mid-sagittal plane can be imaged at closer distances. Additionally, the anterior blind area is of functional significance for birds because the beak falls within this blind area. We tested for the first time some specific predictions about the functional role of the anterior blind area in birds controlling for phylogenetic effects. We used published data on visual field configuration in 40 species of birds and measured beak and skull parameters from museum specimens. We found that birds with proportionally longer beaks have longer anterior blind areas and thus narrower binocular fields. This result suggests that the anterior blind area and beak visibility do play a role in shaping binocular fields, and that binocular field width is not solely determined by the need for stereoscopic vision. In visually guided foragers, the ability to see the beak-and how much of the beak can be seen-varies predictably with foraging habits. For example, fish- and insect-eating specialists can see more of their own beak than birds eating immobile food can. But in non-visually guided foragers, there is no consistent relationship between the beak and anterior blind area. We discuss different strategies-wide binocular fields, large eye movements, and long beaks-that minimize the potential negative effects of the anterior blind area. Overall, we argue that there is more to avian binocularity than meets the eye.

Experience-driven plasticity in binocular vision

PubMed Central

Klink, P. Christiaan; Brascamp, Jan W.; Blake, Randolph; van Wezel, Richard J.A.

2010-01-01

Summary Experience-driven neuronal plasticity allows the brain to adapt its functional connectivity to recent sensory input. Here we use binocular rivalry [1], an experimental paradigm where conflicting images are presented to the individual eyes, to demonstrate plasticity in the neuronal mechanisms that convert visual information from two separated retinas into single perceptual experiences. Perception during binocular rivalry tended to initially consist of alternations between exclusive representations of monocularly defined images, but upon prolonged exposure, mixture percepts became more prevalent. The completeness of suppression, reflected in the incidence of mixture percepts, plausibly reflects the strength of inhibition that likely plays a role in binocular rivalry [2]. Recovery of exclusivity was possible, but required highly specific binocular stimulation. Documenting the prerequisites for these observed changes in perceptual exclusivity, our experiments suggest experience-driven plasticity at interocular inhibitory synapses, driven by the (lack of) correlated activity of neurons representing the conflicting stimuli. This form of plasticity is consistent with a previously proposed, but largely untested, anti-Hebbian learning mechanism for inhibitory synapses in vision [3, 4]. Our results implicate experience-driven plasticity as one governing principle in the neuronal organization of binocular vision. PMID:20674360

Asymmetric Dichoptic Masking in Visual Cortex of Amblyopic Macaque Monkeys

PubMed Central

Shooner, Christopher; Hallum, Luke E.; García-Marín, Virginia; Kiorpes, Lynne

2017-01-01

In amblyopia, abnormal visual experience leads to an extreme form of eye dominance, in which vision through the nondominant eye is degraded. A key aspect of this disorder is perceptual suppression: the image seen by the stronger eye often dominates during binocular viewing, blocking the image of the weaker eye from reaching awareness. Interocular suppression is the focus of ongoing work aimed at understanding and treating amblyopia, yet its physiological basis remains unknown. We measured binocular interactions in visual cortex of anesthetized amblyopic monkeys (female Macaca nemestrina), using 96-channel “Utah” arrays to record from populations of neurons in V1 and V2. In an experiment reported recently (Hallum et al., 2017), we found that reduced excitatory input from the amblyopic eye (AE) revealed a form of balanced binocular suppression that is unaltered in amblyopia. Here, we report on the modulation of the gain of excitatory signals from the AE by signals from its dominant fellow eye (FE). Using a dichoptic masking technique, we found that AE responses to grating stimuli were attenuated by the presentation of a noise mask to the FE, as in a normal control animal. Responses to FE stimuli, by contrast, could not be masked from the AE. We conclude that a weakened ability of the amblyopic eye to modulate cortical response gain creates an imbalance of suppression that favors the dominant eye. SIGNIFICANCE STATEMENT In amblyopia, vision in one eye is impaired as a result of abnormal early visual experience. Behavioral observations in humans with amblyopia suggest that much of their visual loss is due to active suppression of their amblyopic eye. Here we describe experiments in which we studied binocular interactions in macaques with experimentally induced amblyopia. In normal monkeys, the gain of neuronal response to stimulation of one eye is modulated by contrast in the other eye, but in monkeys with amblyopia the balance of gain modulation is altered so that the weaker, amblyopic eye has little effect while the stronger fellow eye has a strong effect. This asymmetric suppression may be a key component of the perceptual losses in amblyopia. PMID:28760867

Asymmetric Dichoptic Masking in Visual Cortex of Amblyopic Macaque Monkeys.

PubMed

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

2017-09-06

In amblyopia, abnormal visual experience leads to an extreme form of eye dominance, in which vision through the nondominant eye is degraded. A key aspect of this disorder is perceptual suppression: the image seen by the stronger eye often dominates during binocular viewing, blocking the image of the weaker eye from reaching awareness. Interocular suppression is the focus of ongoing work aimed at understanding and treating amblyopia, yet its physiological basis remains unknown. We measured binocular interactions in visual cortex of anesthetized amblyopic monkeys (female Macaca nemestrina ), using 96-channel "Utah" arrays to record from populations of neurons in V1 and V2. In an experiment reported recently (Hallum et al., 2017), we found that reduced excitatory input from the amblyopic eye (AE) revealed a form of balanced binocular suppression that is unaltered in amblyopia. Here, we report on the modulation of the gain of excitatory signals from the AE by signals from its dominant fellow eye (FE). Using a dichoptic masking technique, we found that AE responses to grating stimuli were attenuated by the presentation of a noise mask to the FE, as in a normal control animal. Responses to FE stimuli, by contrast, could not be masked from the AE. We conclude that a weakened ability of the amblyopic eye to modulate cortical response gain creates an imbalance of suppression that favors the dominant eye. SIGNIFICANCE STATEMENT In amblyopia, vision in one eye is impaired as a result of abnormal early visual experience. Behavioral observations in humans with amblyopia suggest that much of their visual loss is due to active suppression of their amblyopic eye. Here we describe experiments in which we studied binocular interactions in macaques with experimentally induced amblyopia. In normal monkeys, the gain of neuronal response to stimulation of one eye is modulated by contrast in the other eye, but in monkeys with amblyopia the balance of gain modulation is altered so that the weaker, amblyopic eye has little effect while the stronger fellow eye has a strong effect. This asymmetric suppression may be a key component of the perceptual losses in amblyopia. Copyright © 2017 the authors 0270-6474/17/378734-08$15.00/0.

Night myopia is reduced in binocular vision.

PubMed

Chirre, Emmanuel; Prieto, Pedro M; Schwarz, Christina; Artal, Pablo

2016-06-01

Night myopia, which is a shift in refraction with light level, has been widely studied but still lacks a complete understanding. We used a new infrared open-view binocular Hartmann-Shack wave front sensor to quantify night myopia under monocular and natural binocular viewing conditions. Both eyes' accommodative response, aberrations, pupil diameter, and convergence were simultaneously measured at light levels ranging from photopic to scotopic conditions to total darkness. For monocular vision, reducing the stimulus luminance resulted in a progression of the accommodative state that tends toward the subject's dark focus or tonic accommodation and a change in convergence following the induced accommodative error. Most subjects presented a myopic shift of accommodation that was mitigated in binocular vision. The impact of spherical aberration on the focus shift was relatively small. Our results in monocular conditions support the hypothesis that night myopia has an accommodative origin as the eye progressively changes its accommodation state with decreasing luminance toward its resting state in total darkness. On the other hand, binocularity restrains night myopia, possibly by using fusional convergence as an additional accommodative cue, thus reducing the potential impact of night myopia on vision at low light levels.

Viewing geometry determines the contribution of binocular vision to the online control of grasping.

PubMed

Keefe, Bruce D; Watt, Simon J

2017-12-01

Binocular vision is often assumed to make a specific, critical contribution to online visual control of grasping by providing precise information about the separation between digits and object. This account overlooks the 'viewing geometry' typically encountered in grasping, however. Separation of hand and object is rarely aligned precisely with the line of sight (the visual depth dimension), and analysis of the raw signals suggests that, for most other viewing angles, binocular feedback is less precise than monocular feedback. Thus, online grasp control relying selectively on binocular feedback would not be robust to natural changes in viewing geometry. Alternatively, sensory integration theory suggests that different signals contribute according to their relative precision, in which case the role of binocular feedback should depend on viewing geometry, rather than being 'hard-wired'. We manipulated viewing geometry, and assessed the role of binocular feedback by measuring the effects on grasping of occluding one eye at movement onset. Loss of binocular feedback resulted in a significantly less extended final slow-movement phase when hand and object were separated primarily in the frontoparallel plane (where binocular information is relatively imprecise), compared to when they were separated primarily along the line of sight (where binocular information is relatively precise). Consistent with sensory integration theory, this suggests the role of binocular (and monocular) vision in online grasp control is not a fixed, 'architectural' property of the visuo-motor system, but arises instead from the interaction of viewer and situation, allowing robust online control across natural variations in viewing geometry.

Bilateral symmetry in vision and influence of ocular surgical procedures on binocular vision: A topical review.

PubMed

Arba Mosquera, Samuel; Verma, Shwetabh

2016-01-01

We analyze the role of bilateral symmetry in enhancing binocular visual ability in human eyes, and further explore how efficiently bilateral symmetry is preserved in different ocular surgical procedures. The inclusion criterion for this review was strict relevance to the clinical questions under research. Enantiomorphism has been reported in lower order aberrations, higher order aberrations and cone directionality. When contrast differs in the two eyes, binocular acuity is better than monocular acuity of the eye that receives higher contrast. Anisometropia has an uncommon occurrence in large populations. Anisometropia seen in infancy and childhood is transitory and of little consequence for the visual acuity. Binocular summation of contrast signals declines with age, independent of inter-ocular differences. The symmetric associations between the right and left eye could be explained by the symmetry in pupil offset and visual axis which is always nasal in both eyes. Binocular summation mitigates poor visual performance under low luminance conditions and strong inter-ocular disparity detrimentally affects binocular summation. Considerable symmetry of response exists in fellow eyes of patients undergoing myopic PRK and LASIK, however the method to determine whether or not symmetry is maintained consist of comparing individual terms in a variety of ad hoc ways both before and after the refractive surgery, ignoring the fact that retinal image quality for any individual is based on the sum of all terms. The analysis of bilateral symmetry should be related to the patients' binocular vision status. The role of aberrations in monocular and binocular vision needs further investigation. Copyright © 2016 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.

Symptomatology associated with accommodative and binocular vision anomalies.

PubMed

García-Muñoz, Ángel; Carbonell-Bonete, Stela; Cacho-Martínez, Pilar

2014-01-01

To determine the symptoms associated with accommodative and non-strabismic binocular dysfunctions and to assess the methods used to obtain the subjects' symptoms. We conducted a scoping review of articles published between 1988 and 2012 that analysed any aspect of the symptomatology associated with accommodative and non-strabismic binocular dysfunctions. The literature search was performed in Medline (PubMed), CINAHL, PsycINFO and FRANCIS. A total of 657 articles were identified, and 56 met the inclusion criteria. We found 267 different ways of naming the symptoms related to these anomalies, which we grouped into 34 symptom categories. Of the 56 studies, 35 employed questionnaires and 21 obtained the symptoms from clinical histories. We found 11 questionnaires, of which only 3 had been validated: the convergence insufficiency symptom survey (CISS V-15) and CIRS parent version, both specific for convergence insufficiency, and the Conlon survey, developed for visual anomalies in general. The most widely used questionnaire (21 studies) was the CISS V-15. Of the 34 categories of symptoms, the most frequently mentioned were: headache, blurred vision, diplopia, visual fatigue, and movement or flicker of words at near vision, which were fundamentally related to near vision and binocular anomalies. There is a wide disparity of symptoms related to accommodative and binocular dysfunctions in the scientific literature, most of which are associated with near vision and binocular dysfunctions. The only psychometrically validated questionnaires that we found (n=3) were related to convergence insufficiency and to visual dysfunctions in general and there no specific questionnaires for other anomalies. Copyright © 2014. Published by Elsevier Espana.

A new form of rapid binocular plasticity in adult with amblyopia

PubMed Central

Zhou, Jiawei; Thompson, Benjamin; Hess, Robert F.

2013-01-01

Amblyopia is a neurological disorder of binocular vision affecting up to 3% of the population resulting from a disrupted period of early visual development. Recently, it has been shown that vision can be partially restored by intensive monocular or dichoptic training (4–6 weeks). This can occur even in adults owing to a residual degree of brain plasticity initiated by repetitive and successive sensory stimulation. Here we show that the binocular imbalance that characterizes amblyopia can be reduced by occluding the amblyopic eye with a translucent patch for as little as 2.5 hours, suggesting a degree of rapid binocular plasticity in adults resulting from a lack of sensory stimulation. The integrated binocular benefit is larger in our amblyopic group than in our normal control group. We propose that this rapid improvement in function, as a result of reduced sensory stimulation, represents a new form of plasticity operating at a binocular site. PMID:24026421

A new form of rapid binocular plasticity in adult with amblyopia.

PubMed

Zhou, Jiawei; Thompson, Benjamin; Hess, Robert F

2013-01-01

Amblyopia is a neurological disorder of binocular vision affecting up to 3% of the population resulting from a disrupted period of early visual development. Recently, it has been shown that vision can be partially restored by intensive monocular or dichoptic training (4-6 weeks). This can occur even in adults owing to a residual degree of brain plasticity initiated by repetitive and successive sensory stimulation. Here we show that the binocular imbalance that characterizes amblyopia can be reduced by occluding the amblyopic eye with a translucent patch for as little as 2.5 hours, suggesting a degree of rapid binocular plasticity in adults resulting from a lack of sensory stimulation. The integrated binocular benefit is larger in our amblyopic group than in our normal control group. We propose that this rapid improvement in function, as a result of reduced sensory stimulation, represents a new form of plasticity operating at a binocular site.

A note on image degradation, disability glare, and binocular vision

NASA Astrophysics Data System (ADS)

Rajaram, Vandana; Lakshminarayanan, Vasudevan

2013-08-01

Disability glare due to scattering of light causes a reduction in visual performance due to a luminous veil over the scene. This causes problem such as contrast detection. In this note, we report a study of the effect of this veiling luminance on human stereoscopic vision. We measured the effect of glare on the horopter measured using the apparent fronto-parallel plane (AFPP) criterion. The empirical longitudinal horopter measured using the AFPP criterion was analyzed using the so-called analytic plot. The analytic plot parameters were used for quantitative measurement of binocular vision. Image degradation plays a major effect on binocular vision as measured by the horopter. Under the conditions tested, it appears that if vision is sufficiently degraded then the addition of disability glare does not seem to significantly cause any further compromise in depth perception as measured by the horopter.

Eye–Hand Coordination Skills in Children with and without Amblyopia

PubMed Central

Suttle, Catherine M.; Melmoth, Dean R.; Finlay, Alison L.; Sloper, John J.

2011-01-01

Purpose. To investigate whether binocular information provides benefits for programming and guidance of reach-to-grasp movements in normal children and whether these eye–hand coordination skills are impaired in children with amblyopia and abnormal binocularity. Methods. Reach-to-grasp performance of the preferred hand in binocular versus monocular (dominant or nondominant eye occluded) conditions to different objects (two sizes, three locations, and two to three repetitions) was quantified by using a 3D motion-capture system. The participants were 36 children (age, 5–11 years) and 11 adults who were normally sighted and 21 children (age, 4–8 years) who had strabismus and/or anisometropia. Movement kinematics and error rates were compared for each viewing condition within and between subject groups. Results. The youngest control subjects used a mainly programmed (ballistic) strategy and collided with the objects more often when viewing with only one eye, while older children progressively incorporated visual feedback to guide their reach and, eventually, their grasp, resulting in binocular advantages for both movement components resembling those of adult performance. Amblyopic children were the worst performers under all viewing conditions, even when using the dominant eye. They spent almost twice as long in the final approach to the objects and made many (1.5–3 times) more errors in reach direction and grip positioning than their normal counterparts, these impairments being most marked in those with the poorest binocularity, regardless of the severity or cause of their amblyopia. Conclusions. The importance of binocular vision for eye–hand coordination normally increases with age and use of online movement guidance. Restoring binocularity in children with amblyopia may improve their poor hand action control. PMID:21212188

Impairment of acquired color vision in multiple sclerosis: an early diagnostic sign linked to the greatness of disease.

PubMed

Piro, Anna; Tagarelli, Antonio; Nicoletti, Giuseppe; Scannapieco, Sara; Polidoro, Serena; Valentino, Paola; Quattrone, Aldo

2018-02-01

To assess the type and degree of both red-green and blue-yellow color vision deficiencies of Calabrian males affected by multiple sclerosis. Eighty Calabrian male patients were enrolled (age range 18-70 years; mean age 40.6 ± 12.4 years) showing a disease duration mean of 10.6 ± 8.2 years (range = 0.5-46 years) coming from the Institute of Neurology, Magna Graecia University, Catanzaro. Optic neuritis present in the medical histories of the 21 patients does not influence color vision. Excluding seven colorblind subjects and one affected by a bilateral maculopathy, the analyzed sample group was 72. Seventy controls were matched for age and sex. An ophthalmologist examined all patients and controls in order to rule out diabetic retinopathy, cataracts, senile maculopathy, or ocular fundus' anomalies. The Ishihara test identified the colorblind patients. The City University Test screened for people with abnormal color vision by grading the severity of color vision deficiency. The second part of the City University Test as well as the Farnsworth Test confirmed both the color vision deficiency type and degree. Fifty-one percentage (37/72) of the patients showing a color vision deficiency were subdivided into two subgroups: subgroup one showed red-green deficiency (57%, 21/37); subgroup two showed a coupled red-green and blue-yellow deficiency (43%, 16/37). Furthermore, we found two distinct curves showing a groove within the first 10 years of the disease. Both monocular and binocular analyses allowed us to identify the patients showing the monocular color vision deficiency, but they were well compensated by binocular vision. We think that the majority of the patients with the red-green deficiency will develop the coupled red-green and blue-yellow deficiency in the latter years of multiple sclerosis.

Spatial-frequency dependent binocular imbalance in amblyopia

PubMed Central

Kwon, MiYoung; Wiecek, Emily; Dakin, Steven C.; Bex, Peter J.

2015-01-01

While amblyopia involves both binocular imbalance and deficits in processing high spatial frequency information, little is known about the spatial-frequency dependence of binocular imbalance. Here we examined binocular imbalance as a function of spatial frequency in amblyopia using a novel computer-based method. Binocular imbalance at four spatial frequencies was measured with a novel dichoptic letter chart in individuals with amblyopia, or normal vision. Our dichoptic letter chart was composed of band-pass filtered letters arranged in a layout similar to the ETDRS acuity chart. A different chart was presented to each eye of the observer via stereo-shutter glasses. The relative contrast of the corresponding letter in each eye was adjusted by a computer staircase to determine a binocular Balance Point at which the observer reports the letter presented to either eye with equal probability. Amblyopes showed pronounced binocular imbalance across all spatial frequencies, with greater imbalance at high compared to low spatial frequencies (an average increase of 19%, p < 0.01). Good test-retest reliability of the method was demonstrated by the Bland-Altman plot. Our findings suggest that spatial-frequency dependent binocular imbalance may be useful for diagnosing amblyopia and as an outcome measure for recovery of binocular vision following therapy. PMID:26603125

Spatial-frequency dependent binocular imbalance in amblyopia.

PubMed

Kwon, MiYoung; Wiecek, Emily; Dakin, Steven C; Bex, Peter J

2015-11-25

While amblyopia involves both binocular imbalance and deficits in processing high spatial frequency information, little is known about the spatial-frequency dependence of binocular imbalance. Here we examined binocular imbalance as a function of spatial frequency in amblyopia using a novel computer-based method. Binocular imbalance at four spatial frequencies was measured with a novel dichoptic letter chart in individuals with amblyopia, or normal vision. Our dichoptic letter chart was composed of band-pass filtered letters arranged in a layout similar to the ETDRS acuity chart. A different chart was presented to each eye of the observer via stereo-shutter glasses. The relative contrast of the corresponding letter in each eye was adjusted by a computer staircase to determine a binocular Balance Point at which the observer reports the letter presented to either eye with equal probability. Amblyopes showed pronounced binocular imbalance across all spatial frequencies, with greater imbalance at high compared to low spatial frequencies (an average increase of 19%, p < 0.01). Good test-retest reliability of the method was demonstrated by the Bland-Altman plot. Our findings suggest that spatial-frequency dependent binocular imbalance may be useful for diagnosing amblyopia and as an outcome measure for recovery of binocular vision following therapy.

Combining zonal refractive and diffractive aspheric multifocal intraocular lenses.

PubMed

Muñoz, Gonzalo; Albarrán-Diego, César; Javaloy, Jaime; Sakla, Hani F; Cerviño, Alejandro

2012-03-01

To assess visual performance with the combination of a zonal refractive aspheric multifocal intraocular lens (MIOL) (Lentis Mplus, Oculentis GmbH) and a diffractive aspheric MIOL (Acri.Lisa 366, Acri.Tech GmbH). This prospective interventional cohort study comprised 80 eyes from 40 cataract patients (mean age: 65.5±7.3 years) who underwent implantation of the Lentis Mplus MIOL in one eye and Acri.Lisa 366 MIOL in the fellow eye. The main outcome measures were refraction; monocular and binocular uncorrected and corrected distance, intermediate, and near visual acuities; monocular and binocular defocus curves; binocular photopic contrast sensitivity function compared to a monofocal intraocular lens (IOL) control group (40 age-matched pseudophakic patients implanted with the AR-40e [Abbott Medical Optics]); and quality of vision questionnaire. Binocular uncorrected visual acuities were 0.12 logMAR (0.76 decimal) or better at all distances measured between 6 m and 33 cm. The Lentis Mplus provided statistically significant better vision than the Acri.Lisa at distances between 2 m and 40 cm, and the Acri.Lisa provided statistically significant better vision than the Lentis Mplus at 33 cm. Binocular defocus curve showed little drop-off at intermediate distances. Photopic contrast sensitivity function for distance and near were similar to the monofocal IOL control group except for higher frequencies. Moderate glare (15%), night vision problems (12.5%), and halos (10%) were reported. Complete independence of spectacles was achieved by 92.5% of patients. The combination of zonal refractive aspheric and diffractive aspheric MIOLs resulted in excellent uncorrected binocular distance, intermediate, and near vision, with low incidence of significant photic phenomena and high patient satisfaction. Copyright 2012, SLACK Incorporated.

ANOMALOUS HEAD POSTURES IN STRABISMUS AND NYSTAGMUS - DIAGNOSIS AND MANAGEMENT -

PubMed Central

Teodorescu, Luminita

2015-01-01

Abnormal head positions are adopted in order to improve visual acuity, to avoid diplopia or to obtain a more comfortable binocular vision. The head can be turned or tilted toward right or left, with the chin rotated up or downwards or combination of these positions. The ophthalmologic examination including the assessment of versions leads to the diagnosis. When versions are free, the cause may be congenital nystagmus or strabismus with large angle. When versions are limited we suspect paralytic or restrictive strabismus. The head tilted to one shoulder suggests cyclotropia (IV Nerve Palsy) or congenital nystagmus. We present few of the above cases. An adequate surgical treatment can improve or correct the ocular deviation, diplopia and the abnormal head posture. Conclusions: The abnormal head posture must be assessed and treated early in order to correct the ocular position and head posture. All patient presenting abnormal head position HAD TO BE investigated by an ophthalmologist. PMID:26978880

Smooth Pursuit Eye Movements in Children with Strabismus and in Children with Vergence Deficits

PubMed Central

Lions, Cynthia; Bui-Quoc, Emmanuel; Wiener-Vacher, Sylvette; Seassau, Magali; Bucci, Maria Pia

2013-01-01

Purpose The objective of our study was to examine horizontal smooth pursuit performance in strabismic children and in children with vergence deficits, and to compare these data with those recorded in a group of control age-matched children. Methods Binocular eye movements were recorded by video-oculography in ten strabismic children (mean age: 9.8±0.8) and seven children with vergence deficits (mean age: 10.8±0.6). Data were compared to that of age-matched control children (mean age: 9.8±0.8 years). Results Catch-up saccades amplitude in strabismic children and in children with vergence deficits were significantly higher than in control age-matched children. Moreover, in strabismic children the amplitude of catch-up saccades was significantly higher in rightward than in leftward direction. The number of catch-up saccades was also significantly higher in rightward than in leftward direction. The gain value of pursuits in rightward direction was significantly higher in the right eye than in the left one; for the right eye, the gain value was significantly higher in rightward than in leftward direction. Binocular coordination of pursuit was better in control age-matched children than in children with vergence deficits and than in strabismic children. Conclusions Binocular coordination of pursuit is abnormal in children with vergence deficits and worse in strabismic children. Binocular vision plays an important role in improving binocular coordination of pursuit. PMID:24376777

From dichoptic to dichotic: historical contrasts between binocular vision and binaural hearing.

PubMed

Wade, Nicholas J; Ono, Hiroshi

2005-01-01

Phenomena involving vision with two eyes have been commented upon for several thousand years whereas those concerned with hearing with two ears have a much more recent history. Studies of binocular vision and binaural hearing are contrasted with respect to the singleness of the percept, experimental manipulations of dichoptic and dichotic stimuli, eye and ear dominance, spatial localisation, and the instruments used to stimulate the paired organs. One of the principal phenomena that led to studies of dichotic hearing was dichoptic colour mixing. There was similar disagreement regarding whether colours or sounds could be combined when presented to different paired organs. Direction and distance in visual localisation were analysed before those for auditory localisation, partly due to difficulties in controlling the stimuli. Instruments for investigating binocular vision, like the stereoscope and pseudoscope, were invented before those for binaural hearing, like the stethophone and pseudophone.

Camera calibration method of binocular stereo vision based on OpenCV

NASA Astrophysics Data System (ADS)

Zhong, Wanzhen; Dong, Xiaona

2015-10-01

Camera calibration, an important part of the binocular stereo vision research, is the essential foundation of 3D reconstruction of the spatial object. In this paper, the camera calibration method based on OpenCV (open source computer vision library) is submitted to make the process better as a result of obtaining higher precision and efficiency. First, the camera model in OpenCV and an algorithm of camera calibration are presented, especially considering the influence of camera lens radial distortion and decentering distortion. Then, camera calibration procedure is designed to compute those parameters of camera and calculate calibration errors. High-accurate profile extraction algorithm and a checkboard with 48 corners have also been used in this part. Finally, results of calibration program are presented, demonstrating the high efficiency and accuracy of the proposed approach. The results can reach the requirement of robot binocular stereo vision.

Association between fine motor skills and binocular visual function in children with reading difficulties.

PubMed

Niechwiej-Szwedo, Ewa; Alramis, Fatimah; Christian, Lisa W

2017-12-01

Performance of fine motor skills (FMS) assessed by a clinical test battery has been associated with reading achievement in school-age children. However, the nature of this association remains to be established. The aim of this study was to assess FMS in children with reading difficulties using two experimental tasks, and to determine if performance is associated with reduced binocular function. We hypothesized that in comparison to an age- and sex-matched control group, children identified with reading difficulties will perform worse only on a motor task that has been shown to rely on binocular input. To test this hypothesis, motor performance was assessed using two tasks: bead-threading and peg-board in 19 children who were reading below expected grade and age-level. Binocular vision assessment included tests for stereoacuity, fusional vergence, amplitude of accommodation, and accommodative facility. In comparison to the control group, children with reading difficulties performed significantly worse on the bead-threading task. In contrast, performance on the peg-board task was similar in both groups. Accommodative facility was the only measure of binocular function significantly associated with motor performance. Findings from our exploratory study suggest that normal binocular vision may provide an important sensory input for the optimal development of FMS and reading. Given the small sample size tested in the current study, further investigation to assess the contribution of binocular vision to the development and performance of FMS and reading is warranted. Copyright © 2017 Elsevier B.V. All rights reserved.

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

PubMed

Mitchell, Donald E

2008-01-01

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

Brief Daily Periods of Unrestricted Vision Can Prevent Form-Deprivation Amblyopia

PubMed Central

Wensveen, Janice M.; Harwerth, Ronald S.; Hung, Li-Fang; Ramamirtham, Ramkumar; Kee, Chea-su; Smith, Earl L.

2006-01-01

PURPOSE To characterize how the mechanisms that produce unilateral form-deprivation amblyopia integrate the effects of normal and abnormal vision over time, the effects of brief daily periods of unrestricted vision on the spatial vision losses produced by monocular form deprivation were investigated in infant monkeys. METHODS Beginning at 3 weeks of age, unilateral form deprivation was initiated in 18 infant monkeys by securing a diffuser spectacle lens in front of one eye and a clear plano lens in front of the fellow eye. During the treatment period (18 weeks), three infants wore the diffusers continuously. For the other experimental infants, the diffusers were removed daily and replaced with clear, zero-powered lenses for 1 (n = 5), 2 (n = 6), or 4 (n = 4) hours. Four infants reared with binocular zero-powered lenses and four normally reared monkeys provided control data. RESULTS The degree of amblyopia varied significantly with the daily duration of unrestricted vision. Continuous form deprivation caused severe amblyopia. However, 1 hour of unrestricted vision reduced the degree of amblyopia by 65%, 2 hours reduced the deficits by 90%, and 4 hours preserved near-normal spatial contrast sensitivity. CONCLUSIONS The severely amblyogenic effects of form deprivation in infant primates are substantially reduced by relatively short daily periods of unrestricted vision. The manner in which the mechanisms responsible for amblyopia integrate the effects of normal and abnormal vision over time promotes normal visual development and has important implications for the management of human infants with conditions that potentially cause amblyopia. PMID:16723458

Binocular Vision in Chronic Fatigue Syndrome.

PubMed

Godts, Daisy; Moorkens, Greta; Mathysen, Danny G P

2016-01-01

To compare binocular vision measurements between Chronic Fatigue Syndrome (CFS) patients and healthy controls. Forty-one CFS patients referred by the Reference Centre for Chronic Fatigue Syndrome of the Antwerp University Hospital and forty-one healthy volunteers, matched for age and gender, underwent a complete orthoptic examination. Data of visual acuity, eye position, fusion amplitude, stereopsis, ocular motility, convergence, and accommodation were compared between both groups. Patients with CFS showed highly significant smaller fusion amplitudes (P < 0.001), reduced convergence capacity (P < 0.001), and a smaller accommodation range (P < 0.001) compared to the control group. In patients with CFS binocular vision, convergence and accommodation should be routinely examined. CFS patients will benefit from reading glasses either with or without prism correction in an earlier stage compared to their healthy peers. Convergence exercises may be beneficial for CFS patients, despite the fact that they might be very tiring. Further research will be necessary to draw conclusions about the efficacy of treatment, especially regarding convergence exercises. To our knowledge, this is the first prospective study evaluating binocular vision in CFS patients. © 2016 Board of regents of the University of Wisconsin System, American Orthoptic Journal, Volume 66, 2016, ISSN 0065-955X, E-ISSN 1553-4448.

A trunk ranging system based on binocular stereo vision

NASA Astrophysics Data System (ADS)

Zhao, Xixuan; Kan, Jiangming

2017-07-01

Trunk ranging is an essential function for autonomous forestry robots. Traditional trunk ranging systems based on personal computers are not convenient in practical application. This paper examines the implementation of a trunk ranging system based on the binocular vision theory via TI's DaVinc DM37x system. The system is smaller and more reliable than that implemented using a personal computer. It calculates the three-dimensional information from the images acquired by binocular cameras, producing the targeting and ranging results. The experimental results show that the measurement error is small and the system design is feasible for autonomous forestry robots.

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

PubMed

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

2010-01-01

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

Miniaturized haploscope for testing binocular vision

NASA Technical Reports Server (NTRS)

Decker, T. A.

1973-01-01

Device can reproduce virtually all binocular stimulus conditions (target configuration, vergence angle, and accommodative distance) used to test binocular performance. All subsystems of electronic controls are open-loop and solid-state-controlled and, with the exception of vergence angle drive, utilize dc stepping motors as prime movers. Arrangement is also made for readouts of each variable.

A rapid quantification of binocular misalignment without recording eye movements: Vertical and torsional alignment nulling.

PubMed

Beaton, Kara H; Shelhamer, Mark J; Roberts, Dale C; Schubert, Michael C

2017-05-01

Small, innate asymmetries between the left and right otolith organs can cause ocular misalignment with symptoms that include double vision and motion sickness. Additionally, ocular misalignment affects nearly 5% of the US population. We have developed a portable, non-invasive technology that uses subjective perception of binocular visual signals to estimate relative binocular alignment. The Vertical Alignment Nulling (VAN) and Torsional Alignment Nulling (TAN) tests ask subjects to view one red and one blue line on a tablet computer while looking through color-matched red and blue filters so that each eye sees only one of the lines. Subjects align the red and blue lines, which are initially vertically offset from one another during VAN or rotated relative to one another during TAN, until they perceive a single continuous line. Ocular misalignments are inferred from actual offsets in the final line positions. During testing, all binocular visual cues are eliminated by employing active-matrix organic light-emitting diode (AMOLED) technology and testing in darkness. VAN and TAN can accurately account for visual offsets induced by prisms, and test-retest reliability is excellent, with resolution better than many current standard clinical tests. VAN and TAN tests are similar to the clinical Lancaster red-green test. However, VAN and TAN employ inexpensive, hand-held hardware that can be self-administered with results that are quickly quantifiable. VAN and TAN provide simple, sensitive, and quantitative measures of binocular positioning alignment that may be useful for detecting subtle abnormalities in ocular positioning. Copyright © 2017 Elsevier B.V. All rights reserved.

Individual Objective and Subjective Fixation Disparity in Near Vision

PubMed Central

Jaschinski, Wolfgang

2017-01-01

Binocular vision refers to the integration of images in the two eyes for improved visual performance and depth perception. One aspect of binocular vision is the fixation disparity, which is a suboptimal condition in individuals with respect to binocular eye movement control and subsequent neural processing. The objective fixation disparity refers to the vergence angle between the visual axes, which is measured with eye trackers. Subjective fixation disparity is tested with two monocular nonius lines which indicate the physical nonius separation required for perceived alignment. Subjective and objective fixation disparity represent the different physiological mechanisms of motor and sensory fusion, but the precise relation between these two is still unclear. This study measures both types of fixation disparity at viewing distances of 40, 30, and 24 cm while observers fixated a central stationary fusion target. 20 young adult subjects with normal binocular vision were tested repeatedly to investigate individual differences. For heterophoria and subjective fixation disparity, this study replicated that the binocular system does not properly adjust to near targets: outward (exo) deviations typically increase as the viewing distance is shortened. This exo proximity effect—however—was not found for objective fixation disparity, which–on the average–was zero. But individuals can have reliable outward (exo) or inward (eso) vergence errors. Cases with eso objective fixation disparity tend to have less exo states of subjective fixation disparity and heterophoria. In summary, the two types of fixation disparity seem to respond in a different way when the viewing distance is shortened. Motor and sensory fusion–as reflected by objective and subjective fixation disparity–exhibit complex interactions that may differ between individuals (eso versus exo) and vary with viewing distance (far versus near vision). PMID:28135308

Trifocal intraocular lenses: a comparison of the visual performance and quality of vision provided by two different lens designs.

PubMed

Gundersen, Kjell G; Potvin, Rick

2017-01-01

To compare two different diffractive trifocal intraocular lens (IOL) designs, evaluating longer-term refractive outcomes, visual acuity (VA) at various distances, low contrast VA and quality of vision. Patients with binocularly implanted trifocal IOLs of two different designs (FineVision [FV] and Panoptix [PX]) were evaluated 6 months to 2 years after surgery. Best distance-corrected and uncorrected VA were tested at distance (4 m), intermediate (80 and 60 cm) and near (40 cm). A binocular defocus curve was collected with the subject's best distance correction in place. The preferred reading distance was determined along with the VA at that distance. Low contrast VA at distance was also measured. Quality of vision was measured with the National Eye Institute Visual Function Questionnaire near subset and the Quality of Vision questionnaire. Thirty subjects in each group were successfully recruited. The binocular defocus curves differed only at vergences of -1.0 D (FV better, P =0.02), -1.5 and -2.00 D (PX better, P <0.01 for both). Best distance-corrected and uncorrected binocular vision were significantly better for the PX lens at 60 cm ( P <0.01) with no significant differences at other distances. The preferred reading distance was between 42 and 43 cm for both lenses, with the VA at the preferred reading distance slightly better with the PX lens ( P =0.04). There were no statistically significant differences by lens for low contrast VA ( P =0.1) or for quality of vision measures ( P >0.3). Both trifocal lenses provided excellent distance, intermediate and near vision, but several measures indicated that the PX lens provided better intermediate vision at 60 cm. This may be important to users of tablets and other handheld devices. Quality of vision appeared similar between the two lens designs.

Research on detection method of UAV obstruction based on binocular vision

NASA Astrophysics Data System (ADS)

Zhu, Xiongwei; Lei, Xusheng; Sui, Zhehao

2018-04-01

For the autonomous obstacle positioning and ranging in the process of UAV (unmanned aerial vehicle) flight, a system based on binocular vision is constructed. A three-stage image preprocessing method is proposed to solve the problem of the noise and brightness difference in the actual captured image. The distance of the nearest obstacle is calculated by using the disparity map that generated by binocular vision. Then the contour of the obstacle is extracted by post-processing of the disparity map, and a color-based adaptive parameter adjustment algorithm is designed to extract contours of obstacle automatically. Finally, the safety distance measurement and obstacle positioning during the UAV flight process are achieved. Based on a series of tests, the error of distance measurement can keep within 2.24% of the measuring range from 5 m to 20 m.

Sensory Eye Dominance in Treated Anisometropic Amblyopia

PubMed Central

Chen, Yao

2017-01-01

Amblyopia results from inadequate visual experience during the critical period of visual development. Abnormal binocular interactions are believed to play a critical role in amblyopia. These binocular deficits can often be resolved, owing to the residual visual plasticity in amblyopes. In this study, we quantitatively measured the sensory eye dominance in treated anisometropic amblyopes to determine whether they had fully recovered. Fourteen treated anisometropic amblyopes with normal or corrected to normal visual acuity participated, and their sensory eye dominance was assessed by using a binocular phase combination paradigm. We found that the two eyes were unequal in binocular combination in most (11 out of 14) of our treated anisometropic amblyopes, but none of the controls. We concluded that the treated anisometropic amblyopes, even those with a normal range of visual acuity, exhibited abnormal binocular processing. Our results thus suggest that there is potential for improvement in treated anisometropic amblyopes that may further enhance their binocular visual functioning. PMID:28573051

Oscillopsia in "inverse latent" infantile nystagmus syndrome.

PubMed

Abel, Larry A; Malesic, Linda A

2007-11-01

A possibly unique individual with infantile nystagmus syndrome presented with incessant oscillopsia but good stereopsis when viewing binocularly; her nystagmus was greatly reduced with left eye occlusion. We have attempted to explain this and to identify an intervention that preserves binocular vision while maximizing perceptual stability. Eye movements were recorded and analyzed for duration of foveation (% time when the target was on or near the fovea and the eye was moving at < or = 4 degrees /sec) under different viewing conditions. Changes in foveation were compared with the patient's reports of her perceptual stability. In her right gaze null with her right eye fixating, foveation was 52.9%. This fell to 32.3% for the same eye in primary position and to 0.8% when viewing binocularly in primary position. When viewing binocularly oscillopsia was incessant; when viewing with her right eye vision was stable except in left gaze. Prism correction of her phoria greatly reduced her oscillopsia when viewing binocularly while preserving stereopsis; foveation went up to 33.7%. The patient's ability to maintain good foveation only when viewing with her right eye forces her to choose between stereopsis and stable vision. This may result from the rare combination of (1) requiring good foveation for oscillopsia suppression and (2) nystagmus deteriorating under the stress of maintaining binocularity. There may be many other infantile nystagmus syndrome patients who do not develop oscillopsia but may suffer sufficient asthenopia from a phoria to exacerbate their nystagmus.

Comparison of a hydrogel corneal inlay and monovision laser in situ keratomileusis in presbyopic patients: focus on visual performance and optical quality.

PubMed

Verdoorn, Cornelis

2017-01-01

To compare the visual performance and optical quality after Raindrop Near Vision Inlay implantation or monovision LASIK for the correction of presbyopia. In this retrospective case-series study, patients previously treated in the nondominant eye with monovision LASIK were compared with patients previously implanted with Raindrop Near Vision Inlay. The study enrolled 16 inlay and 15 monovision LASIK patients. Uncorrected near visual acuity, uncorrected distance visual acuity, binocular stereopsis, patient satisfaction, and patient task performance were assessed. Postoperatively, the mean spherical equivalent was -0.66 D (0.78 SD) for the inlay group and -1.03 D (0.56 SD) for the monovision LASIK group. Monocularly, at uncorrected near distances, 60% of inlay patients and 47% of monovision LASIK patients achieved ≥20/20. Monocularly, at uncorrected far distances, 75% of inlay patients and 40% of monovision LASIK patients achieved ≥20/32 vision. Binocularly, at near distances, 79% of inlay patients and 53% of monovision LASIK patients obtained ≥20/20 vision. All patients achieved ≥20/20 binocularly for distance. On average, inlay patients obtained 98 seconds of arc and monovision LASIK patients obtained 286 seconds of arc for stereopsis. Most (79%) of the inlay patients and 66% of monovision LASIK patients were satisfied with their near vision, while 86% of inlay patients and 67% of monovision LASIK patients were satisfied with their distance vision. Patients receiving corneal inlays demonstrated better near and distance visual acuities, binocular stereopsis, task performance, and satisfaction, when compared to patients treated with monovision LASIK.

Progression of Near Vision Loss and Incidence of Near Vision Impairment in an Adult Chinese Population.

PubMed

Han, Xiaotong; Ellwein, Leon B; Guo, Xinxing; Hu, Yin; Yan, William; He, Mingguang

2017-05-01

To investigate the progression of near vision loss and the cumulative incidence of near vision impairment (NVI) 6 years after initial examination of an urban Chinese cohort. Population-based, prospective cohort study. People aged ≥35 years examined at baseline in the Yuexiu District of Guangzhou, China. Participants examined at baseline were invited for 2-year and 6-year follow-up examinations in 2010 and 2014, respectively. Examinations included noncycloplegic autorefraction and binocular near visual acuity (NVA) with and without current near correction measured at 40 cm using a LogMAR ETDRS near vision tumbling E chart. Those with uncorrected binocular NVA (UCNVA) ≤20/40 underwent subjective refraction to obtain best-corrected binocular NVA (BCNVA). Change in UCNVA between baseline and 2014 follow-up examinations and the 6-year cumulative incidence of vision impairment based on 3 definitions: NVA ≤20/40, ≤20/50, and ≤20/63. Among the 1817 baseline participants, 1595 (87.8%) were reexamined in 2010 and 1427 (78.5%) in 2014. Mean vision loss between baseline and the 2014 follow-up was 1.54 (±1.74) lines of UCNVA. Vision loss was associated with age 80 years or older, less education, and better baseline UCNVA. The 6-year cumulative incidence of uncorrected binocular NVI (UCNVI) across the 3 vision impairment definitions was 55.2% (95% confidence interval [CI], 46.1%-64.3%), 51.3% (95% CI, 44.0%-58.7%), and 42.4% (95% CI, 35.5%-49.3%), respectively. With best-corrected binocular NVI (BCNVI), incidence was 6.89% (95% CI, 4.28%-9.50%), 5.17% (95% CI, 2.89%-7.44%), and 2.62% (95% CI, 1.11%-4.12%), respectively. A higher incidence of UCNVI was associated with worse baseline UCNVA for all 3 impairment definitions. Similarly, incidence of BCNVI was associated with worse baseline BCNVA, but also with older age and education at the primary level or less. Gender was not significant for either UCNVI or BCNVI. Approximately half of those aged 35 years or older develop UCNVI in 6 years, the overwhelming majority of whom can be corrected with spectacles. Cost-effective strategies to provide spectacles to this at-risk population remains an issue requiring further study. Copyright © 2017 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Design of and normative data for a new computer based test of ocular torsion.

PubMed

Vaswani, Reena S; Mudgil, Ananth V

2004-01-01

To evaluate a new clinically practical and dynamic test for quantifying torsional binocular eye alignment changes which may occur in the change from monocular to binocular viewing conditions. The test was developed using a computer with Lotus Freelance Software, binoculars with prisms and colored filters. The subject looks through binoculars at the computer screen two meters away. For monocular vision, six concentric blue circles, a blue horizontal line and a tilted red line were displayed on the screen. For binocular vision, white circles replaced blue circles. The subject was asked to orient the lines parallel to each other. The difference in tilt (degrees) between the subjective parallel and fixed horizontal position is the torsional alignment of the eye. The time to administer the test was approximately two minutes. In 70 Normal subjects, average age 16 years, the mean degree of cyclodeviation tilt in the right eye was 0.6 degrees for monocular viewing conditions and 0.7 degrees for binocular viewing conditions, with a standard deviation of approximately one degree. There was no "statistically significant" difference between monocular and binocular viewing. This computer based test is a simple, computerized, non-invasive test that has a potential for use in the diagnosis of cyclovertical strabismus. Currently, there is no commercially available test for this purpose.

The Relationship Between Fusion, Suppression, and Diplopia in Normal and Amblyopic Vision.

PubMed

Spiegel, Daniel P; Baldwin, Alex S; Hess, Robert F

2016-10-01

Single vision occurs through a combination of fusion and suppression. When neither mechanism takes place, we experience diplopia. Under normal viewing conditions, the perceptual state depends on the spatial scale and interocular disparity. The purpose of this study was to examine the three perceptual states in human participants with normal and amblyopic vision. Participants viewed two dichoptically separated horizontal blurred edges with an opposite tilt (2.35°) and indicated their binocular percept: "one flat edge," "one tilted edge," or "two edges." The edges varied with scale (fine 4 min arc and coarse 32 min arc), disparity, and interocular contrast. We investigated how the binocular interactions vary in amblyopic (visual acuity [VA] > 0.2 logMAR, n = 4) and normal vision (VA ≤ 0 logMAR, n = 4) under interocular variations in stimulus contrast and luminance. In amblyopia, despite the established sensory dominance of the fellow eye, fusion prevails at the coarse scale and small disparities (75%). We also show that increasing the relative contrast to the amblyopic eye enhances the probability of fusion at the fine scale (from 18% to 38%), and leads to a reversal of the sensory dominance at coarse scale. In normal vision we found that interocular luminance imbalances disturbed binocular combination only at the fine scale in a way similar to that seen in amblyopia. Our results build upon the growing evidence that the amblyopic visual system is binocular and further show that the suppressive mechanisms rendering the amblyopic system functionally monocular are scale dependent.

Binocular Vision-Based Position and Pose of Hand Detection and Tracking in Space

NASA Astrophysics Data System (ADS)

Jun, Chen; Wenjun, Hou; Qing, Sheng

After the study of image segmentation, CamShift target tracking algorithm and stereo vision model of space, an improved algorithm based of Frames Difference and a new space point positioning model were proposed, a binocular visual motion tracking system was constructed to verify the improved algorithm and the new model. The problem of the spatial location and pose of the hand detection and tracking have been solved.

The disparate histories of binocular vision and binaural hearing.

PubMed

Wade, Nicholas J

2018-01-01

Vision and hearing are dependent on disparities of spatial patterns received by two eyes and on time and intensity differences to two ears. However, the experiences of a single world have masked attention to these disparities. While eyes and ears are paired, there has not been parity in the attention directed to their functioning. Phenomena involving binocular vision were commented upon since antiquity whereas those about binaural hearing are much more recent. This history is compared with respect to the experimental manipulations of dichoptic and dichotic stimuli and the instruments used to stimulate the paired organs. Binocular color mixing led to studies of binaural hearing and direction and distance in visual localization were analyzed before those for auditory localization. Experimental investigations began in the nineteenth century with the invention of instruments like the stereoscope and pseudoscope, soon to be followed by their binaural equivalents, the stethophone and pseudophone.

Owls see in stereo much like humans do.

PubMed

van der Willigen, Robert F

2011-06-10

While 3D experiences through binocular disparity sensitivity have acquired special status in the understanding of human stereo vision, much remains to be learned about how binocularity is put to use in animals. The owl provides an exceptional model to study stereo vision as it displays one of the highest degrees of binocular specialization throughout the animal kingdom. In a series of six behavioral experiments, equivalent to hallmark human psychophysical studies, I compiled an extensive body of stereo performance data from two trained owls. Computer-generated, binocular random-dot patterns were used to ensure pure stereo performance measurements. In all cases, I found that owls perform much like humans do, viz.: (1) disparity alone can evoke figure-ground segmentation; (2) selective use of "relative" rather than "absolute" disparity; (3) hyperacute sensitivity; (4) disparity processing allows for the avoidance of monocular feature detection prior to object recognition; (5) large binocular disparities are not tolerated; (6) disparity guides the perceptual organization of 2D shape. The robustness and very nature of these binocular disparity-based perceptual phenomena bear out that owls, like humans, exploit the third dimension to facilitate early figure-ground segmentation of tangible objects.

Binocular interactions in random chromatic changes at isoluminance

NASA Astrophysics Data System (ADS)

Medina, José M.

2006-02-01

To examine the type of chromatic interactions at isoluminance in the phenomenon of binocular vision, I have determined simple visual reaction times (VRT) under three observational conditions (monocular left, monocular right, and binocular) for different chromatic stimuli along random color axes at isoluminance (simultaneous L-, M-, and S-cone variations). Upper and lower boundaries of probability summation as well as the binocular capacity coefficient were estimated with observed distributions of reaction times. The results were not consistent with the notion of independent chromatic channels between eyes, suggesting the existence of excitatory and inhibitory binocular interactions at suprathreshold isoluminance conditions.

A method of camera calibration in the measurement process with reference mark for approaching observation space target

NASA Astrophysics Data System (ADS)

Zhang, Hua; Zeng, Luan

2017-11-01

Binocular stereoscopic vision can be used for space-based space targets near observation. In order to solve the problem that the traditional binocular vision system cannot work normally after interference, an online calibration method of binocular stereo measuring camera with self-reference is proposed. The method uses an auxiliary optical imaging device to insert the image of the standard reference object into the edge of the main optical path and image with the target on the same focal plane, which is equivalent to a standard reference in the binocular imaging optical system; When the position of the system and the imaging device parameters are disturbed, the image of the standard reference will change accordingly in the imaging plane, and the position of the standard reference object does not change. The camera's external parameters can be re-calibrated by the visual relationship of the standard reference object. The experimental results show that the maximum mean square error of the same object can be reduced from the original 72.88mm to 1.65mm when the right camera is deflected by 0.4 degrees and the left camera is high and low with 0.2° rotation. This method can realize the online calibration of binocular stereoscopic vision measurement system, which can effectively improve the anti - jamming ability of the system.

The effect of lens-induced anisometropia on accommodation and vergence during human visual development.

PubMed

Bharadwaj, Shrikant R; Candy, T Rowan

2011-06-01

Clear and single binocular vision, a prerequisite for normal human visual development, is achieved through accommodation and vergence. Anisometropia is associated with abnormal visual development, but its impact on accommodation and vergence, and therefore on the individual's visual experience, is not known. This study determined the impact of transiently induced anisometropia on accommodative and vergence performance of the typically developing human visual system. One hundred eighteen subjects (age range, 2.9 months to 41.1 years) watched a cartoon movie that moved between 80 and 33 cm under six different viewing conditions: binocular and monocular, and with ±2 diopters (D) and ±4 D of lens-induced anisometropia. Twenty-one subjects (age range, 3.1 months to 12.1 years) also watched the movie with 11% induced aniseikonia. Accommodation and vergence were recorded in both eyes using a videoretinoscope (25 Hz). The main effect of viewing condition was statistically significant for both accommodation and vergence (both P < 0.001), with monocular accommodative and vergence gains statistically significantly smaller than the binocular and four induced anisometropia conditions (P < 0.001 for both accommodation and vergence). The main effect of age approached significance for accommodation (P = 0.06) and was not significant for vergence (P = 0.32). Accommodative and vergence gains with induced aniseikonia were not statistically significantly different from the binocular condition (both P > 0.5). Accommodative and vergence gains of the typically developing visual system deteriorated marginally (accommodation more than vergence) with transiently induced anisometropia (up to ±4 D) and did not deteriorate significantly with induced aniseikonia of 11%. Some binocular cues remained with ±4 D of induced anisometropia and 11% induced aniseikonia, as indicated by the accommodative and vergence gains being higher than in monocular viewing.

The Effect of Lens-Induced Anisometropia on Accommodation and Vergence during Human Visual Development

PubMed Central

Candy, T. Rowan

2011-01-01

Purpose. Clear and single binocular vision, a prerequisite for normal human visual development, is achieved through accommodation and vergence. Anisometropia is associated with abnormal visual development, but its impact on accommodation and vergence, and therefore on the individual's visual experience, is not known. This study determined the impact of transiently induced anisometropia on accommodative and vergence performance of the typically developing human visual system. Methods. One hundred eighteen subjects (age range, 2.9 months to 41.1 years) watched a cartoon movie that moved between 80 and 33 cm under six different viewing conditions: binocular and monocular, and with ±2 diopters (D) and ±4 D of lens-induced anisometropia. Twenty-one subjects (age range, 3.1 months to 12.1 years) also watched the movie with 11% induced aniseikonia. Accommodation and vergence were recorded in both eyes using a videoretinoscope (25 Hz). Results. The main effect of viewing condition was statistically significant for both accommodation and vergence (both P < 0.001), with monocular accommodative and vergence gains statistically significantly smaller than the binocular and four induced anisometropia conditions (P < 0.001 for both accommodation and vergence). The main effect of age approached significance for accommodation (P = 0.06) and was not significant for vergence (P = 0.32). Accommodative and vergence gains with induced aniseikonia were not statistically significantly different from the binocular condition (both P > 0.5). Conclusions. Accommodative and vergence gains of the typically developing visual system deteriorated marginally (accommodation more than vergence) with transiently induced anisometropia (up to ±4 D) and did not deteriorate significantly with induced aniseikonia of 11%. Some binocular cues remained with ±4 D of induced anisometropia and 11% induced aniseikonia, as indicated by the accommodative and vergence gains being higher than in monocular viewing. PMID:21296822

Contrast masking in strabismic amblyopia: attenuation, noise, interocular suppression and binocular summation.

PubMed

Baker, Daniel H; Meese, Tim S; Hess, Robert F

2008-07-01

To investigate amblyopic contrast vision at threshold and above we performed pedestal-masking (contrast discrimination) experiments with a group of eight strabismic amblyopes using horizontal sinusoidal gratings (mainly 3c/deg) in monocular, binocular and dichoptic configurations balanced across eye (i.e. five conditions). With some exceptions in some observers, the four main results were as follows. (1) For the monocular and dichoptic conditions, sensitivity was less in the amblyopic eye than in the good eye at all mask contrasts. (2) Binocular and monocular dipper functions superimposed in the good eye. (3) Monocular masking functions had a normal dipper shape in the good eye, but facilitation was diminished in the amblyopic eye. (4) A less consistent result was normal facilitation in dichoptic masking when testing the good eye, but a loss of this when testing the amblyopic eye. This pattern of amblyopic results was replicated in a normal observer by placing a neutral density filter in front of one eye. The two-stage model of binocular contrast gain control [Meese, T.S., Georgeson, M.A. & Baker, D.H. (2006). Binocular contrast vision at and above threshold. Journal of Vision 6, 1224-1243.] was 'lesioned' in several ways to assess the form of the amblyopic deficit. The most successful model involves attenuation of signal and an increase in noise in the amblyopic eye, and intact stages of interocular suppression and binocular summation. This implies a behavioural influence from monocular noise in the amblyopic visual system as well as in normal observers with an ND filter over one eye.

An automated miniaturized Haploscope for testing binocular visual function

NASA Technical Reports Server (NTRS)

Decker, T. A.; Williams, R. E.; Kuether, C. L.; Wyman-Cornsweet, D.

1976-01-01

A computer-controlled binocular vision testing device has been developed as one part of a system designed for NASA to test the vision of astronauts during spaceflight. The device, called the Mark III Haploscope, utilizes semi-automated psychophysical test procedures to measure visual acuity, stereopsis, phorias, fixation disparity and accommodation/convergence relationships. All tests are self-administered, yield quantitative data and may be used repeatedly without subject memorization. Future applications of this programmable, compact device include its use as a clinical instrument to perform routine eye examinations or vision screening, and as a research tool to examine the effects of environment or work-cycle upon visual function.

Thalamocortical dynamics of the McCollough effect: boundary-surface alignment through perceptual learning.

PubMed

Grossberg, Stephen; Hwang, Seungwoo; Mingolla, Ennio

2002-05-01

This article further develops the FACADE neural model of 3-D vision and figure-ground perception to quantitatively explain properties of the McCollough effect (ME). The model proposes that many ME data result from visual system mechanisms whose primary function is to adaptively align, through learning, boundary and surface representations that are positionally shifted due to the process of binocular fusion. For example, binocular boundary representations are shifted by binocular fusion relative to monocular surface representations, yet the boundaries must become positionally aligned with the surfaces to control binocular surface capture and filling-in. The model also includes perceptual reset mechanisms that use habituative transmitters in opponent processing circuits. Thus the model shows how ME data may arise from a combination of mechanisms that have a clear functional role in biological vision. Simulation results with a single set of parameters quantitatively fit data from 13 experiments that probe the nature of achromatic/chromatic and monocular/binocular interactions during induction of the ME. The model proposes how perceptual learning, opponent processing, and habituation at both monocular and binocular surface representations are involved, including early thalamocortical sites. In particular, it explains the anomalous ME utilizing these multiple processing sites. Alternative models of the ME are also summarized and compared with the present model.

Environmental Enrichment Promotes Plasticity and Visual Acuity Recovery in Adult Monocular Amblyopic Rats

PubMed Central

Bonaccorsi, Joyce; Cenni, Maria Cristina; Sale, Alessandro; Maffei, Lamberto

2012-01-01

Loss of visual acuity caused by abnormal visual experience during development (amblyopia) is an untreatable pathology in adults. In some occasions, amblyopic patients loose vision in their better eye owing to accidents or illnesses. While this condition is relevant both for its clinical importance and because it represents a case in which binocular interactions in the visual cortex are suppressed, it has scarcely been studied in animal models. We investigated whether exposure to environmental enrichment (EE) is effective in triggering recovery of vision in adult amblyopic rats rendered monocular by optic nerve dissection in their normal eye. By employing both electrophysiological and behavioral assessments, we found a full recovery of visual acuity in enriched rats compared to controls reared in standard conditions. Moreover, we report that EE modulates the expression of GAD67 and BDNF. The non invasive nature of EE renders this paradigm promising for amblyopia therapy in adult monocular people. PMID:22509358

Childhood amblyopia: current management and new trends

PubMed Central

Tailor, Vijay; Bossi, Manuela; Greenwood, John A.; Dahlmann-Noor, Annegret

2016-01-01

Abstract Introduction or background With a prevalence of 2–5%, amblyopia is the most common vision deficit in children in the UK and the second most common cause of functional low vision in children in low-income countries. Sources of data Pubmed, Cochrane library and clinical trial registries (clinicaltrials.gov, ISRCTN, UKCRN portfolio database). Areas of agreement Screening and treatment at the age of 4–5 years are cost efficient and clinically effective. Optical treatment (glasses) alone can improve visual acuity, with residual amblyopia treated by part-time occlusion or pharmacological blurring of the better-seeing eye. Treatment after the end of the conventional ‘critical period’ can improve vision, but in strabismic amblyopia carries a low risk of double vision. Areas of controversy It is not clear whether earlier vision screening would be cost efficient and associated with better outcomes. Optimization of treatment by individualized patching regimes or early start of occlusion, and novel binocular treatment approaches may enhance adherence to treatment, provide better outcomes and shorten treatment duration. Growing points Binocular treatments for amblyopia. Areas timely for developing research Impact of amblyopia on education and quality of life; optimal screening timing and tests; optimal administration of conventional treatments; development of child-friendly, effective and safe binocular treatments. PMID:27543498

Neural architectures for stereo vision.

PubMed

Parker, Andrew J; Smith, Jackson E T; Krug, Kristine

2016-06-19

Stereoscopic vision delivers a sense of depth based on binocular information but additionally acts as a mechanism for achieving correspondence between patterns arriving at the left and right eyes. We analyse quantitatively the cortical architecture for stereoscopic vision in two areas of macaque visual cortex. For primary visual cortex V1, the result is consistent with a module that is isotropic in cortical space with a diameter of at least 3 mm in surface extent. This implies that the module for stereo is larger than the repeat distance between ocular dominance columns in V1. By contrast, in the extrastriate cortical area V5/MT, which has a specialized architecture for stereo depth, the module for representation of stereo is about 1 mm in surface extent, so the representation of stereo in V5/MT is more compressed than V1 in terms of neural wiring of the neocortex. The surface extent estimated for stereo in V5/MT is consistent with measurements of its specialized domains for binocular disparity. Within V1, we suggest that long-range horizontal, anatomical connections form functional modules that serve both binocular and monocular pattern recognition: this common function may explain the distortion and disruption of monocular pattern vision observed in amblyopia.This article is part of the themed issue 'Vision in our three-dimensional world'. © 2016 The Authors.

Childhood amblyopia: current management and new trends.

PubMed

Tailor, Vijay; Bossi, Manuela; Greenwood, John A; Dahlmann-Noor, Annegret

2016-09-01

With a prevalence of 2-5%, amblyopia is the most common vision deficit in children in the UK and the second most common cause of functional low vision in children in low-income countries. Pubmed, Cochrane library and clinical trial registries (clinicaltrials.gov, ISRCTN, UKCRN portfolio database). Screening and treatment at the age of 4-5 years are cost efficient and clinically effective. Optical treatment (glasses) alone can improve visual acuity, with residual amblyopia treated by part-time occlusion or pharmacological blurring of the better-seeing eye. Treatment after the end of the conventional 'critical period' can improve vision, but in strabismic amblyopia carries a low risk of double vision. It is not clear whether earlier vision screening would be cost efficient and associated with better outcomes. Optimization of treatment by individualized patching regimes or early start of occlusion, and novel binocular treatment approaches may enhance adherence to treatment, provide better outcomes and shorten treatment duration. Binocular treatments for amblyopia. Impact of amblyopia on education and quality of life; optimal screening timing and tests; optimal administration of conventional treatments; development of child-friendly, effective and safe binocular treatments. © The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Binocular fusion time in sleep-deprived subjects.

DOT National Transportation Integrated Search

1969-01-01

The attainment of binocular single vision when the distance of gaze is changed is a component of total reaction time and may be critical in flight when the gaze is changed from the instrument panel to the outside or from the outside to the instrument...

Landing performance by low-time private pilots after the sudden loss of binocular vision - Cyclops II

NASA Technical Reports Server (NTRS)

Lewis, C. E., Jr.; Swaroop, R.; Mcmurty, T. C.; Blakeley, W. R.; Masters, R. L.

1973-01-01

Study of low-time general aviation pilots, who, in a series of spot landings, were suddenly deprived of binocular vision by patching either eye on the downwind leg of a standard, closed traffic pattern. Data collected during these landings were compared with control data from landings flown with normal vision during the same flight. The sequence of patching and the mix of control and monocular landings were randomized to minimize the effect of learning. No decrease in performance was observed during landings with vision restricted to one eye, in fact, performance improved. This observation is reported at a high level of confidence (p less than 0.001). These findings confirm the previous work of Lewis and Krier and have important implications with regard to aeromedical certification standards.

Image registration algorithm for high-voltage electric power live line working robot based on binocular vision

NASA Astrophysics Data System (ADS)

Li, Chengqi; Ren, Zhigang; Yang, Bo; An, Qinghao; Yu, Xiangru; Li, Jinping

2017-12-01

In the process of dismounting and assembling the drop switch for the high-voltage electric power live line working (EPL2W) robot, one of the key problems is the precision of positioning for manipulators, gripper and the bolts used to fix drop switch. To solve it, we study the binocular vision system theory of the robot and the characteristic of dismounting and assembling drop switch. We propose a coarse-to-fine image registration algorithm based on image correlation, which can improve the positioning precision of manipulators and bolt significantly. The algorithm performs the following three steps: firstly, the target points are marked respectively in the right and left visions, and then the system judges whether the target point in right vision can satisfy the lowest registration accuracy by using the similarity of target points' backgrounds in right and left visions, this is a typical coarse-to-fine strategy; secondly, the system calculates the epipolar line, and then the regional sequence existing matching points is generated according to neighborhood of epipolar line, the optimal matching image is confirmed by calculating the similarity between template image in left vision and the region in regional sequence according to correlation matching; finally, the precise coordinates of target points in right and left visions are calculated according to the optimal matching image. The experiment results indicate that the positioning accuracy of image coordinate is within 2 pixels, the positioning accuracy in the world coordinate system is within 3 mm, the positioning accuracy of binocular vision satisfies the requirement dismounting and assembling the drop switch.

Optoelectronic stereoscopic device for diagnostics, treatment, and developing of binocular vision

NASA Astrophysics Data System (ADS)

Pautova, Larisa; Elkhov, Victor A.; Ovechkis, Yuri N.

2003-08-01

Operation of the device is based on alternative generation of pictures for left and right eyes on the monitor screen. Controller gives pulses on LCG so that shutter for left or right eye opens synchronously with pictures. The device provides frequency of switching more than 100 Hz, and that is why the flickering is absent. Thus, a separate demonstration of images to the left eye or to the right one in turn is obtained for patients being unaware and creates the conditions of binocular perception clsoe to natural ones without any additional separation of vision fields. LC-cell transfer characteristic coodination with time parameters of monitor screen has enabled to improve stereo image quality. Complicated problem of computer stereo images with LC-glasses is so called 'ghosts' - noise images that come to blocked eye. We reduced its influence by adapting stereo images to phosphor and LC-cells characteristics. The device is intended for diagnostics and treatment of stabismus, amblyopia and other binocular and stereoscopic vision impairments, for cultivating, training and developing of stereoscopic vision, for measurements of horizontal and vertical phoria, phusion reserves, the stereovision acuity and some else, for fixing central scotoma borders, as well as suppression scotoma in strabismus too.

21 CFR 886.1340 - Haploscope.

Code of Federal Regulations, 2011 CFR

2011-04-01

... afterimages. The device is intended to measure strabismus (eye muscle imbalance), to assess binocular vision (use of both eyes to see), and to treat suppression and amblyopia (dimness of vision without any...

21 CFR 886.1340 - Haploscope.

Code of Federal Regulations, 2010 CFR

2010-04-01

... afterimages. The device is intended to measure strabismus (eye muscle imbalance), to assess binocular vision (use of both eyes to see), and to treat suppression and amblyopia (dimness of vision without any...

Aerial LED signage by use of crossed-mirror array

NASA Astrophysics Data System (ADS)

Yamamoto, Hirotsugu; Kujime, Ryousuke; Bando, Hiroki; Suyama, Shiro

2013-03-01

3D representation of digital signage improves its significance and rapid notification of important points. Real 3D display techniques such as volumetric 3D displays are effective for use of 3D for public signs because it provides not only binocular disparity but also motion parallax and other cues, which will give 3D impression even people with abnormal binocular vision. Our goal is to realize aerial 3D LED signs. We have specially designed and fabricated a reflective optical device to form an aerial image of LEDs with a wide field angle. The developed reflective optical device composed of crossed-mirror array (CMA). CMA contains dihedral corner reflectors at each aperture. After double reflection, light rays emitted from an LED will converge into the corresponding image point. The depth between LED lamps is represented in the same depth in the floating 3D image. Floating image of LEDs was formed in wide range of incident angle with a peak reflectance at 35 deg. The image size of focused beam (point spread function) agreed to the apparent aperture size.

Binocular vision anomalies and normative data (BAND) in Tamil Nadu: report 1.

PubMed

Hussaindeen, Jameel Rizwana; Rakshit, Archayeeta; Singh, Neeraj Kumar; Swaminathan, Meenakshi; George, Ronnie; Kapur, Suman; Scheiman, Mitchell; Ramani, Krishna Kumar

2017-05-01

This population-based, cross-sectional study was designed to determine normative data for binocular vision and accommodative testing in rural and urban populations of Tamil Nadu. A sample of 936 was determined, based on a previous pilot study. The epidemiological field work included a comprehensive eye examination and a binocular vision and accommodative assessment carried out in a total of four public schools, two each in the rural and urban arms of Chennai. An overall sample of 3,024 children between seven and 17 years of age was screened in the four schools and 920 children were included in the study. We found significant differences in expected values from the current clinical criteria for near point of convergence (NPC) with penlight, distance and near horizontal phorias, vergence facility, accommodation convergence/accommodation (AC/A) ratio, accommodative amplitudes, monocular and binocular accommodative facility (t-test: p < 0.001). The mean and standard deviation break/recovery values for NPC (in centimetres) with an accommodative target and penlight with red filter was 3 ± 3/4 ± 4 and 7 ± 5/10 ± 7, respectively. The mean accommodative amplitudes for the population could be estimated from the linear regression equation 16 - 0.3 × (age). The vergence facility was 12 ± 4 cycles/minute and 14 ± 4 cycles/minute in the seven to 10 and 11 to 17 age groups, respectively. Monocular accommodative facility was 11 ± 4 cycles/minute and 14 ± 5 cycles/minute and binocular accommodative facility was 10 ± 4 cycles/minute and 14 ± 5 cycles/minute in the seven to 12 and 13 to 17 age groups, respectively. The mean calculated AC/A ratio was 5.4 ± 0.6/1. The normative data for vergence and accommodative parameters for the Indian children between seven and 17 years of age are reported. The developmental trend of accommodation and vergence differences and significant differences in cut-off between the current data and available literature are reported. These differences have clinical implications for the interpretation, diagnosis and management of anomalies of binocular vision. © 2016 Optometry Australia.

An Autonomous Gps-Denied Unmanned Vehicle Platform Based on Binocular Vision for Planetary Exploration

NASA Astrophysics Data System (ADS)

Qin, M.; Wan, X.; Shao, Y. Y.; Li, S. Y.

2018-04-01

Vision-based navigation has become an attractive solution for autonomous navigation for planetary exploration. This paper presents our work of designing and building an autonomous vision-based GPS-denied unmanned vehicle and developing an ARFM (Adaptive Robust Feature Matching) based VO (Visual Odometry) software for its autonomous navigation. The hardware system is mainly composed of binocular stereo camera, a pan-and tilt, a master machine, a tracked chassis. And the ARFM-based VO software system contains four modules: camera calibration, ARFM-based 3D reconstruction, position and attitude calculation, BA (Bundle Adjustment) modules. Two VO experiments were carried out using both outdoor images from open dataset and indoor images captured by our vehicle, the results demonstrate that our vision-based unmanned vehicle is able to achieve autonomous localization and has the potential for future planetary exploration.

Association between reading speed, cycloplegic refractive error, and oculomotor function in reading disabled children versus controls.

PubMed

Quaid, Patrick; Simpson, Trefford

2013-01-01

Approximately one in ten students aged 6 to 16 in Ontario (Canada) school boards have an individual education plan (IEP) in place due to various learning disabilities, many of which are specific to reading difficulties. The relationship between reading (specifically objectively determined reading speed and eye movement data), refractive error, and binocular vision related clinical measurements remain elusive. One hundred patients were examined in this study (50 IEP and 50 controls, age range 6 to 16 years). IEP patients were referred by three local school boards, with controls being recruited from the routine clinic population (non-IEP patients in the same age group). A comprehensive eye examination was performed on all subjects, in addition to a full binocular vision work-up and cycloplegic refraction. In addition to the cycloplegic refractive error, the following binocular vision related data was also acquired: vergence facility, vergence amplitudes, accommodative facility, accommodative amplitudes, near point of convergence, stereopsis, and a standardized symptom scoring scale. Both the IEP and control groups were also examined using the Visagraph III system, which permits recording of the following reading parameters objectively: (i) reading speed, both raw values and values compared to grade normative data, and (ii) the number of eye movements made per 100 words read. Comprehension was assessed via a questionnaire administered at the end of the reading task, with each subject requiring 80% or greater comprehension. The IEP group had significantly greater hyperopia compared to the control group on cycloplegic examination. Vergence facility was significantly correlated to (i) reading speed, (ii) number of eye movements made when reading, and (iii) a standardized symptom scoring system. Vergence facility was also significantly reduced in the IEP group versus controls. Significant differences in several other binocular vision related scores were also found. This research indicates there are significant associations between reading speed, refractive error, and in particular vergence facility. It appears sensible that students being considered for reading specific IEP status should have a full eye examination (including cycloplegia), in addition to a comprehensive binocular vision evaluation.

A verification and errors analysis of the model for object positioning based on binocular stereo vision for airport surface surveillance

NASA Astrophysics Data System (ADS)

Wang, Huan-huan; Wang, Jian; Liu, Feng; Cao, Hai-juan; Wang, Xiang-jun

2014-12-01

A test environment is established to obtain experimental data for verifying the positioning model which was derived previously based on the pinhole imaging model and the theory of binocular stereo vision measurement. The model requires that the optical axes of the two cameras meet at one point which is defined as the origin of the world coordinate system, thus simplifying and optimizing the positioning model. The experimental data are processed and tables and charts are given for comparing the positions of objects measured with DGPS with a measurement accuracy of 10 centimeters as the reference and those measured with the positioning model. Sources of visual measurement model are analyzed, and the effects of the errors of camera and system parameters on the accuracy of positioning model were probed, based on the error transfer and synthesis rules. A conclusion is made that measurement accuracy of surface surveillances based on binocular stereo vision measurement is better than surface movement radars, ADS-B (Automatic Dependent Surveillance-Broadcast) and MLAT (Multilateration).

Preliminary results from the use of the novel Interactive binocular treatment (I-BiT) system, in the treatment of strabismic and anisometropic amblyopia.

PubMed

Waddingham, P E; Butler, T K H; Cobb, S V; Moody, A D R; Comaish, I F; Haworth, S M; Gregson, R M; Ash, I M; Brown, S M; Eastgate, R M; Griffiths, G D

2006-03-01

We have developed a novel application of adapted virtual reality (VR) technology, for the binocular treatment of amblyopia. We describe the use of the system in six children. Subjects consisted of three conventional treatment 'failures' and three conventional treatment 'refusers', with a mean age of 6.25 years (5.42-7.75 years). Treatment consisted of watching video clips and playing interactive games with specifically designed software to allow streamed binocular image presentation. Initial vision in the amblyopic eye ranged from 6/12 to 6/120 and post-treatment 6/7.5 to 6/24-1. Total treatment time was a mean of 4.4 h. Five out of six children have shown an improvement in their vision (average increase of 10 letters), including those who had previously failed to comply with conventional occlusion. Improvements in vision were demonstrable within a short period of time, in some children after 1 h of treatment. This system is an exciting and promising application of VR technology as a new treatment for amblyopia.

Looking above the prairie: localized and upward acute vision in a native grassland bird.

PubMed

Tyrrell, Luke P; Moore, Bret A; Loftis, Christopher; Fernández-Juricic, Esteban

2013-12-02

Visual systems of open habitat vertebrates are predicted to have a band of acute vision across the retina (visual streak) and wide visual coverage to gather information along the horizon. We tested whether the eastern meadowlark (Sturnella magna) had this visual configuration given that it inhabits open grasslands. Contrary to our expectations, the meadowlark retina has a localized spot of acute vision (fovea) and relatively narrow visual coverage. The fovea projects above rather than towards the horizon with the head at rest, and individuals modify their body posture in tall grass to maintain a similar foveal projection. Meadowlarks have relatively large binocular fields and can see their bill tips, which may help with their probe-foraging technique. Overall, meadowlark vision does not fit the profile of vertebrates living in open habitats. The binocular field may control foraging while the fovea may be used for detecting and tracking aerial stimuli (predators, conspecifics).

Evaluation of visual acuity with Gen 3 night vision goggles

NASA Technical Reports Server (NTRS)

Bradley, Arthur; Kaiser, Mary K.

1994-01-01

Using laboratory simulations, visual performance was measured at luminance and night vision imaging system (NVIS) radiance levels typically encountered in the natural nocturnal environment. Comparisons were made between visual performance with unaided vision and that observed with subjects using image intensification. An Amplified Night Vision Imaging System (ANVIS6) binocular image intensifier was used. Light levels available in the experiments (using video display technology and filters) were matched to those of reflecting objects illuminated by representative night-sky conditions (e.g., full moon, starlight). Results show that as expected, the precipitous decline in foveal acuity experienced with decreasing mesopic luminance levels is effectively shifted to much lower light levels by use of an image intensification system. The benefits of intensification are most pronounced foveally, but still observable at 20 deg eccentricity. Binocularity provides a small improvement in visual acuity under both intensified and unintensified conditions.

Effects of cortical damage on binocular depth perception.

PubMed

Bridge, Holly

2016-06-19

Stereoscopic depth perception requires considerable neural computation, including the initial correspondence of the two retinal images, comparison across the local regions of the visual field and integration with other cues to depth. The most common cause for loss of stereoscopic vision is amblyopia, in which one eye has failed to form an adequate input to the visual cortex, usually due to strabismus (deviating eye) or anisometropia. However, the significant cortical processing required to produce the percept of depth means that, even when the retinal input is intact from both eyes, brain damage or dysfunction can interfere with stereoscopic vision. In this review, I examine the evidence for impairment of binocular vision and depth perception that can result from insults to the brain, including both discrete damage, temporal lobectomy and more systemic diseases such as posterior cortical atrophy.This article is part of the themed issue 'Vision in our three-dimensional world'. © 2016 The Authors.

Effects of cortical damage on binocular depth perception

PubMed Central

2016-01-01

Stereoscopic depth perception requires considerable neural computation, including the initial correspondence of the two retinal images, comparison across the local regions of the visual field and integration with other cues to depth. The most common cause for loss of stereoscopic vision is amblyopia, in which one eye has failed to form an adequate input to the visual cortex, usually due to strabismus (deviating eye) or anisometropia. However, the significant cortical processing required to produce the percept of depth means that, even when the retinal input is intact from both eyes, brain damage or dysfunction can interfere with stereoscopic vision. In this review, I examine the evidence for impairment of binocular vision and depth perception that can result from insults to the brain, including both discrete damage, temporal lobectomy and more systemic diseases such as posterior cortical atrophy. This article is part of the themed issue ‘Vision in our three-dimensional world’. PMID:27269597

Modeling the convergence accommodation of stereo vision for binocular endoscopy.

PubMed

Gao, Yuanqian; Li, Jinhua; Li, Jianmin; Wang, Shuxin

2018-02-01

The stereo laparoscope is an important tool for achieving depth perception in robot-assisted minimally invasive surgery (MIS). A dynamic convergence accommodation algorithm is proposed to improve the viewing experience and achieve accurate depth perception. Based on the principle of the human vision system, a positional kinematic model of the binocular view system is established. The imaging plane pair is rectified to ensure that the two rectified virtual optical axes intersect at the fixation target to provide immersive depth perception. Stereo disparity was simulated with the roll and pitch movements of the binocular system. The chessboard test and the endoscopic peg transfer task were performed, and the results demonstrated the improved disparity distribution and robustness of the proposed convergence accommodation method with respect to the position of the fixation target. This method offers a new solution for effective depth perception with the stereo laparoscopes used in robot-assisted MIS. Copyright © 2017 John Wiley & Sons, Ltd.

Effect of ecological viewing conditions on the Ames' distorted room illusion.

PubMed

Gehringer, W L; Engel, E

1986-05-01

Ecological theory asserts that the Ames' distorted room illusion (DRI) occurs as a result of the artificial restriction of information pickup. According to Gibson (1966, 1979), the illusion is eliminated when binocular vision and/or head movement are allowed. In Experiment 1, to measure the DRI, we used a size-matching technique employing discs placed within an Ames' distorted room. One hundred forty-four subjects viewed the distorted room or a control apparatus under four different viewing conditions (i.e., restricted or unrestricted head movement), using monocular and binocular vision. In Experiment 2, subjects viewed binocularly and were instructed to move freely while making judgments. Overall, the main findings of this study were that the DRI decreased with increases in viewing access and that the DRI persisted under all viewing conditions. The persistence of the illusion was felt to contradict Gibson's position.

A binocular approach to treating amblyopia: antisuppression therapy.

PubMed

Hess, Robert F; Mansouri, Behzad; Thompson, Benjamin

2010-09-01

We developed a binocular treatment for amblyopia based on antisuppression therapy. A novel procedure is outlined for measuring the extent to which the fixing eye suppresses the fellow amblyopic eye. We hypothesize that suppression renders a structurally binocular system, functionally monocular. We demonstrate using three strabismic amblyopes that information can be combined normally between their eyes under viewing conditions where suppression is reduced. Also, we show that prolonged periods of viewing (under the artificial conditions of stimuli of different contrast in each eye) during which information from the two eyes is combined leads to a strengthening of binocular vision in such cases and eventual combination of binocular information under natural viewing conditions (stimuli of the same contrast in each eye). Concomitant improvement in monocular acuity of the amblyopic eye occurs with this reduction in suppression and strengthening of binocular fusion. Furthermore, in each of the three cases, stereoscopic function is established. This provides the basis for a new treatment of amblyopia, one that is purely binocular and aimed at reducing suppression as a first step.

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

PubMed

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.

Effects of Brief Daily Periods of Unrestricted Vision during Early Monocular Form Deprivation on Development of Visual Area 2

PubMed Central

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

2011-01-01

Purpose. 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. Methods. 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. Results. 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. Conclusions. 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. PMID:21849427

Comparison of visual outcomes after bilateral implantation of extended range of vision and trifocal intraocular lenses.

PubMed

Ruiz-Mesa, Ramón; Abengózar-Vela, Antonio; Aramburu, Ana; Ruiz-Santos, María

2017-06-26

To compare visual outcomes after cataract surgery with bilateral implantation of 2 intraocular lenses (IOLs): extended range of vision and trifocal. Each group of this prospective study comprised 40 eyes (20 patients). Phacoemulsification followed by bilateral implantation of a FineVision IOL (group 1) or a Symfony IOL (group 2) was performed. The following outcomes were assessed up to 1 year postoperatively: binocular uncorrected distance visual acuity (UDVA), binocular uncorrected intermediate visual acuity (UIVA) at 60 cm, binocular uncorrected near visual acuity (UNVA) at 40 cm, spherical equivalent (SE) refraction, defocus curves, mesopic and photopic contrast sensitivity, halometry, posterior capsule opacification (PCO), and responses to a patient questionnaire. The mean binocular values in group 1 and group 2, respectively, were SE -0.15 ± 0.25 D and -0.19 ± 0.18 D; UDVA 0.01 ± 0.03 logMAR and 0.01 ± 0.02 logMAR; UIVA 0.11 ± 0.08 logMAR and 0.09 ± 0.08 logMAR; UNVA 0.06 ± 0.07 logMAR and 0.17 ± 0.06 logMAR. Difference in UNVA between IOLs (p<0.05) was statistically significant. There were no significant differences in contrast sensitivity, halometry, or PCO between groups. Defocus curves were similar between groups from 0 D to -2 D, but showed significant differences from -2.50 D to -4.00 D (p<0.05). Both IOLs provided excellent distance and intermediate visual outcomes. The FineVision IOL showed better near visual acuity. Predictability of the refractive results and optical performance were excellent; all patients achieved spectacle independence. The 2 IOLs gave similar and good contrast sensitivity in photopic and mesopic conditions and low perception of halos by patients.

The prevalence of specific reading disability in an amblyopic population. A preliminary report.

PubMed

Koklanis, Konstandina; Georgievski, Zoran; Brassington, Kate; Bretherton, Lesley

2006-01-01

To investigate the prevalence of specific reading disability in children with functional amblyopia and to explore the relationship between the two. In this prospective study, 20 consecutive children, aged 6 to 15 years (mean 8 +/-1.99 years), and diagnosed with amblyopia underwent a vision and reading assessment. The orthoptic examination included the assessment of participants' visual acuity, ocular motility and binocular functions. Specific reading disability was diagnosed using the Wide Range Achievement Test (WRAT III Reading Subtest). Intelligence, phonological awareness, rapid automatized naming (RAN), and the ability to read pseudo or nonsense words was also assessed using various psycho-linguistic reading tests. The prevalence of specific reading disability in this small series of amblyopic children was found to be 5% (n=1/20). This was even less than that reported in the local Victoria general population (16%). The type of amblyopia appeared related to phonological awareness (p=0.018) and decoding words (p=0.024), those with anisometropic amblyopia performing significantly better on these tasks than the strabismic amblyopes. The presence of binocular vision functions was also related to decoding words; those with binocular single vision performed better than those with suppression and lacking single binocular vision (p=0.007). Generally, amblyopic children also showed a lower RAN score when compared to phonological awareness score. There was no statistically significant difference for the severity of amblyopia (p=>0.05). In this very small pilot series, reading disorders were relatively rare in children with amblyopia. However, strabismic amblyopia and presence of suppression may have an adverse effect on phonological skills. In addition, amblyopia may be associated with a deficit in RAN. Further research is needed and planned to gain a better understanding about the relationship between amblyopia and reading ability.

Interactions between binocular rivalry and Gestalt formation.

PubMed

de Weert, Charles M M; Snoeren, Peter R; Koning, Arno

2005-09-01

A question raised a long time ago in binocular rivalry research is whether the phenomenon of binocular rivalry is purely determined by local stimulus properties or that global stimulus properties also play a role. More specifically: do coherent features in a stimulus influence rivalrous behavior? After decades of underexposure of the subject, recently this question seemed to be answered in the affirmative. This paper presents additional evidence for an influence of coherent features. In an experiment in which eye movements cannot bias conclusions it is demonstrated that Gestalt formation influences binocular rivalry positively, i.e., stronger Gestalts have longer total dominance times. Gestalt formation appears to intervene in the states of dominance ("what"), not directly in the dominance durations ("how long"). This generates questions about the nature of interactions between binocular rivalry and Gestalt formation. Gestalt formation seems to be fed by signals that are generated after binocular convergence and only leaves its mark on binocular rivalry by feedback to monocular channels, a conclusion which has been drawn before by Alais and Blake [Alais, D., & Blake, R. (1998). Interaction between global motion and local binocular rivalry. Vision research 38, 637-644].

Pilot vision considerations : the effect of age on binocular fusion time.

DOT National Transportation Integrated Search

1966-10-01

The study provides data regarding the relationship between vision performance and age of the individual. It has direct application to pilot visual tasks with respect to instrument panel displays, and to controller visual tasks in association with rad...

The biomechanical significance of pulley on binocular vision.

PubMed

Guo, Hongmei; Gao, Zhipeng; Chen, Weiyi

2016-12-28

Pulleys have been reported as the functional origins of the rectus extraocular muscles (EOMs). However, biomechanical significance of pulleys on binocular vision has not been reported. Three eye movement models, i.e., non-pulley model, passive-pulley model, and active-pulley model, are used to simulate the horizontal movement of the eyes from the primary position to the left direction in the range of 1°-30°. The resultant forces of six EOMs along both orthogonal directions (i.e., the x-axis and y-axis defined in this paper) in the horizontal plane are calculated using the three models. The resultant force along the y-axis of the left eye for non-pulley model are significantly larger than that of the other two pulley models. The difference of the force, between the left eye and the right eye in non-pulley model, is larger than those in the other two pulley models along x-axis and y-axis. The pulley models present more biomechanical advantage on the horizontally binocular vision than the non-pulley model. Combining with the previous imaging evidences of pulleys, the results show that pulley model coincides well with the real physiological conditions.

Symptomatic accommodative and binocular dysfunctions from the use of flat-panel displays

PubMed Central

Porcar, Esteban; Montalt, Juan Carlos; Pons, Álvaro M.; España-Gregori, Enrique

2018-01-01

AIM To determine the presence of symptomatic accommodative and non-strabismic binocular dysfunctions (ANSBD) in a non-presbyopic population of video display unit (VDU) users with flat-panel displays. METHODS One hundred and one VDU users, aged between 20 to 34y, initially participated in the study. This study excluded contact-lens wearers and subjects who had undergone refractive surgery or had any systemic or ocular disease. First, subjects were asked about the type and nature of eye symptoms they experienced during VDU use. Then, a thorough eye examination excluded those subjects with a significant uncorrected refractive error or other problem, such as ocular motility disorders, vertical deviation, strabismus and eye diseases. Finally, the remaining participants underwent an exhaustive assessment of their accommodative and binocular vision status. RESULTS Eighty-nine VDU users (46 females and 43 males) were included in this study. They used flat-panel displays for an average of 5±1.9h a day. Twenty subjects presented ANSBD (22.5%). Convergence excess was the most frequent non-strabismic binocular dysfunction (9 subjects), followed by fusional vergence dysfunction (3 subjects) and convergence insufficiency (2 subjects). Within the accommodative dysfunctions, accommodative excess was the most common (4 subjects), followed by accommodative insufficiency (2 subjects). Moderate to severe eye symptoms were found in 13 subjects with ANSBD. CONCLUSION Significant eye symptoms in VDU users with accommodative and/or non-strabismic binocular dysfunctions often occur and should not be underestimated; therefore, an appropriate evaluation of accommodative and binocular vision status is more important for this population. PMID:29600186

Binocular vision and eye movement disorders in older adults.

PubMed

Leat, Susan J; Chan, Lisa Li-Li; Maharaj, Priya-Devi; Hrynchak, Patricia K; Mittelstaedt, Andrea; Machan, Carolyn M; Irving, Elizabeth L

2013-05-31

To determine the prevalence of binocular vision (BV) and eye movement disorders in a clinic population of older adults. Retrospective clinic data were abstracted from files of 500 older patients seen at the University of Waterloo Optometry Clinic over a 1-year period. Stratified sampling gave equal numbers of patients in the 60 to 69, 70 to 79, and 80+ age groups. Data included age, general and ocular history and symptoms, use of antidepressants, a habit of smoking, refraction, visual acuity, BV and eye movement status for the most recent full oculo-visual assessment, and an assessment 10 years prior. The prevalence of any BV or eye movement abnormal test (AT) result, defined as a test result outside the normal range, was determined. This included strabismus (any) or phoria; incomitancy; poor pursuits; and remote near point of convergence (NPC). The prevalence of significant BV disorders (diagnostic entities, i.e., a clinical condition that may need treatment and may have functional implications) was also determined. The prevalence of any BV or eye movement at was 41%, 44%, and 51% in the 60 to 69, 70 to 79, and 80+ age groups, respectively. These figures were lower for 10 years earlier: 31%, 36%, and 40% for ages 50 to 59, 60 to 69, and 70+, respectively. The prevalence of any BV or eye movement disorder was 27%, 30%, and 38% for the three age groups and 17%, 19%, and 24% for 10 years prior. Age and use of antidepressants most commonly predicted BV or eye movement AT or disorder. BV disorders are common among older adults.

The Active Side of Stereopsis: Fixation Strategy and Adaptation to Natural Environments.

PubMed

Gibaldi, Agostino; Canessa, Andrea; Sabatini, Silvio P

2017-03-20

Depth perception in near viewing strongly relies on the interpretation of binocular retinal disparity to obtain stereopsis. Statistical regularities of retinal disparities have been claimed to greatly impact on the neural mechanisms that underlie binocular vision, both to facilitate perceptual decisions and to reduce computational load. In this paper, we designed a novel and unconventional approach in order to assess the role of fixation strategy in conditioning the statistics of retinal disparity. We integrated accurate realistic three-dimensional models of natural scenes with binocular eye movement recording, to obtain accurate ground-truth statistics of retinal disparity experienced by a subject in near viewing. Our results evidence how the organization of human binocular visual system is finely adapted to the disparity statistics characterizing actual fixations, thus revealing a novel role of the active fixation strategy over the binocular visual functionality. This suggests an ecological explanation for the intrinsic preference of stereopsis for a close central object surrounded by a far background, as an early binocular aspect of the figure-ground segregation process.

Orientation tuning of binocular summation: a comparison of colour to achromatic contrast

PubMed Central

Gheiratmand, Mina; Cherniawsky, Avital S.; Mullen, Kathy T.

2016-01-01

A key function of the primary visual cortex is to combine the input from the two eyes into a unified binocular percept. At low, near threshold, contrasts a process of summation occurs if the visual inputs from the two eyes are similar. Here we measure the orientation tuning of binocular summation for chromatic and equivalent achromatic contrast. We derive estimates of orientation tuning by measuring binocular summation as a function of the orientation difference between two sinusoidal gratings presented dichoptically to different eyes. We then use a model to estimate the orientation bandwidth of the neural detectors underlying the binocular combination. We find that orientation bandwidths are similar for chromatic and achromatic stimuli at both low (0.375 c/deg) and mid (1.5 c/deg) spatial frequencies, with an overall average of 29 ± 3 degs (HWHH, s.e.m). This effect occurs despite the overall greater binocular summation found for the low spatial frequency chromatic stimuli. These results suggest that similar, oriented processes underlie both chromatic and achromatic binocular contrast combination. The non-oriented detection process found in colour vision at low spatial frequencies under monocular viewing is not evident at the binocular combination stage. PMID:27168119

21 CFR 886.1340 - Haploscope.

Code of Federal Regulations, 2014 CFR

2014-04-01

...-powered device that consists of two movable viewing tubes, each containing a slide carrier, a low... afterimages. The device is intended to measure strabismus (eye muscle imbalance), to assess binocular vision (use of both eyes to see), and to treat suppression and amblyopia (dimness of vision without any...

21 CFR 886.1340 - Haploscope.

Code of Federal Regulations, 2013 CFR

2013-04-01

...-powered device that consists of two movable viewing tubes, each containing a slide carrier, a low... afterimages. The device is intended to measure strabismus (eye muscle imbalance), to assess binocular vision (use of both eyes to see), and to treat suppression and amblyopia (dimness of vision without any...

21 CFR 886.1340 - Haploscope.

Code of Federal Regulations, 2012 CFR

2012-04-01

...-powered device that consists of two movable viewing tubes, each containing a slide carrier, a low... afterimages. The device is intended to measure strabismus (eye muscle imbalance), to assess binocular vision (use of both eyes to see), and to treat suppression and amblyopia (dimness of vision without any...

Two-dimensional (2D) displacement measurement of moving objects using a new MEMS binocular vision system

NASA Astrophysics Data System (ADS)

Di, Si; Lin, Hui; Du, Ruxu

2011-05-01

Displacement measurement of moving objects is one of the most important issues in the field of computer vision. This paper introduces a new binocular vision system (BVS) based on micro-electro-mechanical system (MEMS) technology. The eyes of the system are two microlenses fabricated on a substrate by MEMS technology. The imaging results of two microlenses are collected by one complementary metal-oxide-semiconductor (CMOS) array. An algorithm is developed for computing the displacement. Experimental results show that as long as the object is moving in two-dimensional (2D) space, the system can effectively estimate the 2D displacement without camera calibration. It is also shown that the average error of the displacement measurement is about 3.5% at different object distances ranging from 10 cm to 35 cm. Because of its low cost, small size and simple setting, this new method is particularly suitable for 2D displacement measurement applications such as vision-based electronics assembly and biomedical cell culture.

The evaluation of partial binocular overlap on car maneuverability: A pilot study

NASA Technical Reports Server (NTRS)

Tsou, Brian H.; Rogers-Adams, Beth M.; Goodyear, Charles D.

1992-01-01

An engineering approach to enlarge the helmet mounted display (HMD) field of view (FOV) and maintain resolution and weight by partially overlapping the binocular FOV has received renewed interest among human factors scientists. It is evident, based on the brief literature review, that any panoramic display with a binocular overlap, less than a minimum amount, annoys the viewer, degrades performance, and elicits undesirable behavior. The major finding is that across the 60 deg conditions, subjects moved their heads a greater distance (by about 5 degs on each side) than in the 180 deg condition, presumably to compensate for the lack of FOV. It is quite clear that the study, based on simple car maneuverability and two subjects, reveals differences in FOV, but nothing significant between binocular overlap levels and configurations. This tentatively indicates that some tradeoffs of binocular vision for a larger overall display FOV are acceptable.

Rapid Vision Correction by Special Operations Forces.

PubMed

Reynolds, Mark E

This report describes a rapid method of vision correction used by Special Operations Medics in multiple operational engagements. Between 2011 and 2015, Special Operations Medics used an algorithm- driven refraction technique. A standard block of instruction was provided to the medics, along with a packaged kit. The technique was used in multiple operational engagements with host nation military and civilians. Data collected for program evaluation were later analyzed to assess the utility of the technique. Glasses were distributed to 230 patients with complaints of either decreased distance or near (reading). Most patients (84%) with distance complaints achieved corrected binocular vision of 20/40 or better, and 97% of patients with near-vision complaints achieved corrected near-binocular vision of 20/40 or better. There was no statistically significant difference between the percentages of patients achieving 20/40 when medics used the technique under direct supervision versus independent use. A basic refraction technique using a designed kit allows for meaningful improvement in distance and/or near vision at austere locations. Special Operations Medics can leverage this approach after specific training with minimal time commitment. It can serve as a rapid, effective intervention with multiple applications in diverse operational environments. 2017.

Compact and wide-field-of-view head-mounted display

NASA Astrophysics Data System (ADS)

Uchiyama, Shoichi; Kamakura, Hiroshi; Karasawa, Joji; Sakaguchi, Masafumi; Furihata, Takeshi; Itoh, Yoshitaka

1997-05-01

A compact and wide field of view HMD having 1.32-in full color VGA poly-Si TFT LCDs and simple eyepieces much like LEEP optics has been developed. The total field of view is 80 deg with a 40 deg overlap in its central area. Each optical unit which includes an LCD and eyepiece is 46 mm in diameter and 42 mm in length. The total number of pixels is equivalent to (864 times 3) times 480. This HMD realizes its wide field of view and compact size by having a narrower binocular area (overlap area) than that of commercialized HMDs. For this reason, it is expected that the frequency of monocular vision will be more than that of commercialized HMDs and human natural vision. Therefore, we researched the convergent state of eyes while observing the monocular areas of this HMD by employing an EOG and considered the suitability of this HMD to human vision. As a result, it was found that the convergent state of the monocular vision was nearly equal to that of binocular vision. That is, it can be said that this HMD has the possibility of being well suited to human vision in terms of the convergence.

Improved Binocular Outcomes Following Binocular Treatment for Childhood Amblyopia.

PubMed

Kelly, Krista R; Jost, Reed M; Wang, Yi-Zhong; Dao, Lori; Beauchamp, Cynthia L; Leffler, Joel N; Birch, Eileen E

2018-03-01

Childhood amblyopia can be treated with binocular games or movies that rebalance contrast between the eyes, which is thought to reduce depth of interocular suppression so the child can experience binocular vision. While visual acuity gains have been reported following binocular treatment, studies rarely report gains in binocular outcomes (i.e., stereoacuity, suppression) in amblyopic children. Here, we evaluated binocular outcomes in children who had received binocular treatment for childhood amblyopia. Data for amblyopic children enrolled in two ongoing studies were pooled. The sample included 41 amblyopic children (6 strabismic, 21 anisometropic, 14 combined; age 4-10 years; ≤4 prism diopters [PD]) who received binocular treatment (20 game, 21 movies; prescribed 9-10 hours treatment). Amblyopic eye visual acuity and binocular outcomes (Randot Preschool Stereoacuity, extent of suppression, and depth of suppression) were assessed at baseline and at 2 weeks. Mean amblyopic eye visual acuity (P < 0.001) and mean stereoacuity improved (P = 0.045), and mean extent (P = 0.005) and depth of suppression (P = 0.003) were reduced from baseline at the 2-week visit (87% game adherence, 100% movie adherence). Depth of suppression was reduced more in children aged <8 years than in those aged ≥8 years (P = 0.004). Worse baseline depth of suppression was correlated with a larger depth of suppression reduction at 2 weeks (P = 0.001). After 2 weeks, binocular treatment in amblyopic children improved visual acuity and binocular outcomes, reducing the extent and depth of suppression and improving stereoacuity. Binocular treatments that rebalance contrast to overcome suppression are a promising additional option for treating amblyopia.

Identification and location of catenary insulator in complex background based on machine vision

NASA Astrophysics Data System (ADS)

Yao, Xiaotong; Pan, Yingli; Liu, Li; Cheng, Xiao

2018-04-01

It is an important premise to locate insulator precisely for fault detection. Current location algorithms for insulator under catenary checking images are not accurate, a target recognition and localization method based on binocular vision combined with SURF features is proposed. First of all, because of the location of the insulator in complex environment, using SURF features to achieve the coarse positioning of target recognition; then Using binocular vision principle to calculate the 3D coordinates of the object which has been coarsely located, realization of target object recognition and fine location; Finally, Finally, the key is to preserve the 3D coordinate of the object's center of mass, transfer to the inspection robot to control the detection position of the robot. Experimental results demonstrate that the proposed method has better recognition efficiency and accuracy, can successfully identify the target and has a define application value.

Amaurosis fugax

MedlinePlus

... other symptoms with the vision loss, seek medical attention right away. Alternative Names Transient monocular blindness; Transient monocular visual loss; TMLV; Transient monocular visual loss; Transient binocular ...

Cerebral Palsy for the Pediatric Eye Care Team Part III: Diagnosis and Management of Associated Visual and Sensory Disorders.

PubMed

Arnoldi, Kyle A; Pendarvis, Lauren; Jackson, Jorie; Batra, Noopur Nikki Agarwal

2006-01-01

Cerebral palsy (CP) is a term used to describe a spectrum of deficits of muscle tone and posture resulting from damage to the developing nervous system. Though considered a motor disorder, CP can be associated with disorders of the sensory visual pathway. This paper, the final in a series of three articles, will present frequency, diagnosis, and management of the visual and binocular vision deficits associated with CP. Topics for discussion will include the prevalence and etiology of decreased acuity, the effect of CP on sensory and motor fusion, and the response to treatment for these sensory deficits. A retrospective chart review of all cases of cerebral palsy referred to the St. Louis Children's Hospital Eye Center was done. Detailed data on the sensory and motor deficits documented in these children was collected. Also recorded was the management strategy and response to treatment. Of the 131 cases reviewed (mean age 5.2 years at presentation), 46% had decreased vision in at least one eye due to amblyopia (24%), optic nerve abnormality (16%), cortical visual impairment (14%), or a combination. Forty-nine (37%) had significant refractive error. Sixty-four percent of those with significant refractive error responded to spectacle correction. Forty-three percent of those with amblyopia responded to conventional therapies. Of the nonstrabismic patients, 89% demonstrated sensory fusion, 90% had stereopsis, and 91% had motor fusion. No patient lacking fusion or stereopsis prior to strabismus surgery gained these abilities with realignment of the eyes. While children with CP are capable of age-appropriate acuity and binocular vision, they are at increased risk for sensory visual deficits. These deficits are not the direct result of CP itself, but either share a common underlying cause, or occur as sequelae to the strabismus that is prevalent in CP. Most importantly, some sensory deficits may respond to standard treatment methods.

Effects of Pictorial Cues on Reaching Depend on the Distinctiveness of Target Objects

PubMed Central

Himmelbach, Marc

2013-01-01

There is an ongoing debate under what conditions learned object sizes influence visuomotor control under preserved stereovision. Using meaningful objects (matchboxes of locally well-known brands in the UK) a previous study has nicely shown that the recognition of these objects influences action programming by means of reach amplitude and grasp pre-shaping even under binocular vision. Using the same paradigm, we demonstrated that short-term learning of colour-size associations was not sufficient to induce any visuomotor effects under binocular viewing conditions. Now we used the same matchboxes, for which the familiarity effect was shown in the UK, with German participants who have never seen these objects before. We addressed the question whether simply a high degree of distinctness, or whether instead actual prior familiarity of these objects, are required to affect motor computations. We found that under monocular and binocular viewing conditions the learned size and location influenced the amplitude of the reaching component significantly. In contrast, the maximum grip aperture remained unaffected for binocular vision. We conclude that visual distinctness is sufficient to form reliable associations in short-term learning to influence reaching even for preserved stereovision. Grasp pre-shaping instead seems to be less susceptible to such perceptual effects. PMID:23382882

Ecomorphology of orbit orientation and the adaptive significance of binocular vision in primates and other mammals.

PubMed

Heesy, Christopher P

2008-01-01

Primates are characterized by forward-facing, or convergent, orbits and associated binocular field overlap. Hypotheses explaining the adaptive significance of these traits often relate to ecological factors, such as arboreality, nocturnal visual predation, or saltatory locomotion in a complex nocturnal, arboreal environment. This study re-examines the ecological factors that are associated with high orbit convergence in mammals. Orbit orientation data were collected for 321 extant taxa from sixteen orders of metatherian (marsupial) and eutherian mammals. These taxa were coded for activity pattern, degree of faunivory, and substrate preference. Results demonstrate that nocturnal and cathemeral mammals have significantly more convergent orbits than diurnal taxa, both within and across orders. Faunivorous eutherians (both nocturnal and diurnal) have higher mean orbit convergence than opportunistically foraging or non-faunivorous taxa. However, substrate preference is not associated with higher orbit convergence and, by extension, greater binocular visual field overlap. These results are consistent with the hypothesis that mammalian predators evolved higher orbit convergence, binocular vision, and stereopsis to counter camouflage in prey inhabiting a nocturnal environment. Strepsirhine primates have a range of orbit convergence values similar to nocturnal or cathemeral predatory non-primate mammals. These data are entirely consistent with the nocturnal visual predation hypothesis of primate origins. (c) 2007 S. Karger AG, Basel.

Predicting Vision-Related Disability in Glaucoma.

PubMed

Abe, Ricardo Y; Diniz-Filho, Alberto; Costa, Vital P; Wu, Zhichao; Medeiros, Felipe A

2018-01-01

To present a new methodology for investigating predictive factors associated with development of vision-related disability in glaucoma. Prospective, observational cohort study. Two hundred thirty-six patients with glaucoma followed up for an average of 4.3±1.5 years. Vision-related disability was assessed by the 25-item National Eye Institute Visual Function Questionnaire (NEI VFQ-25) at baseline and at the end of follow-up. A latent transition analysis model was used to categorize NEI VFQ-25 results and to estimate the probability of developing vision-related disability during follow-up. Patients were tested with standard automated perimetry (SAP) at 6-month intervals, and evaluation of rates of visual field change was performed using mean sensitivity (MS) of the integrated binocular visual field. Baseline disease severity, rate of visual field loss, and duration of follow-up were investigated as predictive factors for development of disability during follow-up. The relationship between baseline and rates of visual field deterioration and the probability of vision-related disability developing during follow-up. At baseline, 67 of 236 (28%) glaucoma patients were classified as disabled based on NEI VFQ-25 results, whereas 169 (72%) were classified as nondisabled. Patients classified as nondisabled at baseline had 14.2% probability of disability developing during follow-up. Rates of visual field loss as estimated by integrated binocular MS were almost 4 times faster for those in whom disability developed versus those in whom it did not (-0.78±1.00 dB/year vs. -0.20±0.47 dB/year, respectively; P < 0.001). In the multivariate model, each 1-dB lower baseline binocular MS was associated with 34% higher odds of disability developing over time (odds ratio [OR], 1.34; 95% confidence interval [CI], 1.06-1.70; P = 0.013). In addition, each 0.5-dB/year faster rate of loss of binocular MS during follow-up was associated with a more than 3.5 times increase in the risk of disability developing (OR, 3.58; 95% CI, 1.56-8.23; P = 0.003). A new methodology for classification and analysis of change in patient-reported quality-of-life outcomes allowed construction of models for predicting vision-related disability in glaucoma. Copyright © 2017 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Visual performance of four simultaneous-image multifocal contact lenses under dim and glare conditions.

PubMed

García-Lázaro, Santiago; Ferrer-Blasco, Teresa; Madrid-Costa, David; Albarrán-Diego, César; Montés-Micó, Robert

2015-01-01

To assess and compare the effects of four simultaneous-image multifocal contact lenses (SIMCLs), and those with distant-vision-only contact lenses on visual performance in early presbyopes, under dim conditions, including the effects of induced glare. In this double-masked crossover study design, 28 presbyopic subjects aged 40 to 46 years were included. All participants were fitted with the four different SIMCLs (Air Optix Aqua Multifocal [AOAM; Alcon], PureVision Multifocal [PM; Bausch & Lomb], Acuvue Oasys for Presbyopia [AOP; Johnson & Johnson Vision], and Biofinity Multifocal [BM; CooperVision]) and with monofocal contact lenses (Air Optix Aqua, Alcon). After 1 month of daily contact lens wearing, each subject's binocular distance visual acuity (BDVA) and binocular distance contrast sensitivity (BDCS) were measured using the Functional Visual Analyzer (Stereo Optical Co., Inc.) under mesopic conditions (3 candela [cd]/m) both with no glare and under the 2 levels of induced glare: 1.0 lux (glare 1) and 28 lux (glare 2). Among the SIMCLs, in terms of BDVA, AOAM and PM outperformed BM and AOP. All contact lenses performed better at level without glare, followed by Glare 1, and with the worst results obtained under glare 2. Binocular distance contrast sensitivity revealed statistically significant differences for 12 cycles per degree (cpd). Among the SIMCLs, post hoc multiple comparison testing revealed that AOAM and PM provided the best BDCS at the three luminance levels. In both cases, BDVA and BDCS at 12 cpd, monofocal contact lenses outperformed all SIMCL ones at all lighting conditions. Air Optix Aqua Multifocal and PM provided better visual performance than BM and AOP for distance vision with low addition and under dim conditions, but they all provide worse performance than monofocal contact lenses.

Improved Binocular Outcomes Following Binocular Treatment for Childhood Amblyopia

PubMed Central

Kelly, Krista R.; Jost, Reed M.; Wang, Yi-Zhong; Dao, Lori; Beauchamp, Cynthia L.; Leffler, Joel N.; Birch, Eileen E.

2018-01-01

Purpose Childhood amblyopia can be treated with binocular games or movies that rebalance contrast between the eyes, which is thought to reduce depth of interocular suppression so the child can experience binocular vision. While visual acuity gains have been reported following binocular treatment, studies rarely report gains in binocular outcomes (i.e., stereoacuity, suppression) in amblyopic children. Here, we evaluated binocular outcomes in children who had received binocular treatment for childhood amblyopia. Methods Data for amblyopic children enrolled in two ongoing studies were pooled. The sample included 41 amblyopic children (6 strabismic, 21 anisometropic, 14 combined; age 4–10 years; ≤4 prism diopters [PD]) who received binocular treatment (20 game, 21 movies; prescribed 9–10 hours treatment). Amblyopic eye visual acuity and binocular outcomes (Randot Preschool Stereoacuity, extent of suppression, and depth of suppression) were assessed at baseline and at 2 weeks. Results Mean amblyopic eye visual acuity (P < 0.001) and mean stereoacuity improved (P = 0.045), and mean extent (P = 0.005) and depth of suppression (P = 0.003) were reduced from baseline at the 2-week visit (87% game adherence, 100% movie adherence). Depth of suppression was reduced more in children aged <8 years than in those aged ≥8 years (P = 0.004). Worse baseline depth of suppression was correlated with a larger depth of suppression reduction at 2 weeks (P = 0.001). Conclusions After 2 weeks, binocular treatment in amblyopic children improved visual acuity and binocular outcomes, reducing the extent and depth of suppression and improving stereoacuity. Binocular treatments that rebalance contrast to overcome suppression are a promising additional option for treating amblyopia. PMID:29625442

VISION AND COLLEGE READING - A REVIEW OF THE LITERATURE AND REPORT OF A SURVEY.

ERIC Educational Resources Information Center

MAXWELL, MARTHA J.

THE AMERICAN OPTICAL (AO) COMPANY'S SIGHT SCREENER, A PORTABLE BINOCULAR INSTRUMENT DESIGNED FOR MASS VISION TESTING, WAS EVALUATED AT THE UNIVERSITY OF MARYLAND READING AND STUDY SKILLS LABORATORY TO DETERMINE ITS CAPACITY TO IDENTIFY STUDENTS NEEDING PROFESSIONAL EYE EXAMINATIONS PRIOR TO READING INSTRUCTION. DATA FROM 106 PROBATIONARY FRESHMEN,…

Stereo vision and strabismus

PubMed Central

Read, J C A

2015-01-01

Binocular stereopsis, or stereo vision, is the ability to derive information about how far away objects are, based solely on the relative positions of the object in the two eyes. It depends on both sensory and motor abilities. In this review, I briefly outline some of the neuronal mechanisms supporting stereo vision, and discuss how these are disrupted in strabismus. I explain, in some detail, current methods of assessing stereo vision and their pros and cons. Finally, I review the evidence supporting the clinical importance of such measurements. PMID:25475234

New insights into amblyopia: binocular therapy and noninvasive brain stimulation.

PubMed

Hess, Robert F; Thompson, Benjamin

2013-02-01

The current approach to the treatment of amblyopia is problematic for a number of reasons. First, it promotes recovery of monocular vision but because it is not designed to promote binocularity, its binocular outcomes often are disappointing. Second, compliance is poor and variable. Third, the effectiveness of the treatment is thought to decrease with increasing age. We discuss 2 new approaches aimed at recovering visual function in adults with amblyopia. The first is a binocular approach to amblyopia treatment that is showing promise in initial clinical studies. The second is still in development and involves the use of well-established noninvasive brain stimulation techniques to temporarily alter the balance of excitation and inhibition in the visual cortex. Copyright © 2013 American Association for Pediatric Ophthalmology and Strabismus. Published by Mosby, Inc. All rights reserved.

Visual Performance of a Quadrifocal (Trifocal) Intraocular Lens Following Removal of the Crystalline Lens.

PubMed

Kohnen, Thomas; Herzog, Michael; Hemkeppler, Eva; Schönbrunn, Sabrina; De Lorenzo, Nina; Petermann, Kerstin; Böhm, Myriam

2017-12-01

To evaluate visual performance after implantation of a quadrifocal intraocular lens (IOL). Setting: Department of Ophthalmology, Goethe University, Frankfurt, Germany. Twenty-seven patients (54 eyes) received bilateral implantation of the PanOptix IOL (AcrySof IQ PanOptixTM; Alcon Research, Fort Worth, Texas, USA) pre-enrollment. Exclusion criteria were previous ocular surgeries, corneal astigmatism of >1.5 diopter (D), ocular pathologies, or corneal abnormalities. Intervention or Observational Procedure(s): Postoperative examination at 3 months including manifest refraction; uncorrected visual acuity (UCVA) and distance-corrected visual acuity (DCVA) in 4 m, 80 cm, 60 cm, and 40 cm slit-lamp examination; defocus testing; contrast sensitivity (CS) under photopic and mesopic conditions; and a questionnaire on subjective quality of vision, optical phenomena, and spectacle independence was performed. At 3 months postoperatively, UCVA and DCVA in 4 m, 80 cm, 60 cm, and 40 cm (logMAR), defocus curves, CS, and quality-of-vision questionnaire results. Mean spherical equivalent was -0.04 ± 0.321 D 3 months postoperatively. Binocular UCVA at distance, intermediate (80 cm, 60 cm), and near was 0.00 ± 0.094 logMAR, 0.09 ± 0.107 logMAR, 0.00 ± 0.111 logMAR, and 0.01 ± 0.087 logMAR, respectively. Binocular defocus curve showed peaks with best visual acuity (VA) at 0.00 D (-0.07 logMAR) and -2.00 D (-0.02 logMAR). Visual performance of the PanOptix IOL showed good VA at all distances; particularly good intermediate VA (logMAR > 0.1), with best VA at 60 cm; and high patient satisfaction and spectacle independence 3 months postoperatively. Copyright © 2017 Elsevier Inc. All rights reserved.

Study on portable optical 3D coordinate measuring system

NASA Astrophysics Data System (ADS)

Ren, Tongqun; Zhu, Jigui; Guo, Yinbiao

2009-05-01

A portable optical 3D coordinate measuring system based on digital Close Range Photogrammetry (CRP) technology and binocular stereo vision theory is researched. Three ultra-red LED with high stability is set on a hand-hold target to provide measuring feature and establish target coordinate system. Ray intersection based field directional calibrating is done for the intersectant binocular measurement system composed of two cameras by a reference ruler. The hand-hold target controlled by Bluetooth wireless communication is free moved to implement contact measurement. The position of ceramic contact ball is pre-calibrated accurately. The coordinates of target feature points are obtained by binocular stereo vision model from the stereo images pair taken by cameras. Combining radius compensation for contact ball and residual error correction, object point can be resolved by transfer of axes using target coordinate system as intermediary. This system is suitable for on-field large-scale measurement because of its excellent portability, high precision, wide measuring volume, great adaptability and satisfying automatization. It is tested that the measuring precision is near to +/-0.1mm/m.

The King-Devick (K-D) test of rapid eye movements: a bedside correlate of disability and quality of life in MS.

PubMed

Moster, Stephen; Wilson, James A; Galetta, Steven L; Balcer, Laura J

2014-08-15

We investigated the King-Devick (K-D) test of rapid number naming as a visual performance measure in a cohort of patients with multiple sclerosis (MS). In this cross-sectional study, 81 patients with MS and 20 disease-free controls from an ongoing study of visual outcomes underwent K-D testing. A test of rapid number naming, K-D requires saccadic eye movements as well as intact vision, attention and concentration. To perform the K-D test, participants are asked to read numbers aloud as quickly as possible from three test cards; the sum of the three test card times in seconds constitutes the summary score. High-contrast visual acuity (VA), low-contrast letter acuity (1.25% and 2.5% levels), retinal nerve fiber layer (RNFL) thickness by optical coherence tomography (OCT), MS Functional Composite (MSFC) and vision-specific quality of life (QOL) measures (25-Item NEI Visual Functioning Questionnaire [NEI-VFQ-25] and 10-Item Neuro-Ophthalmic Supplement) were also assessed. K-D time scores in the MS cohort (total time to read the three test cards) were significantly higher (worse) compared to those for disease-free controls (P=0.003, linear regression, accounting for age). Within the MS cohort, higher K-D scores were associated with worse scores for the NEI-VFQ-25 composite (P<0.001), 10-Item Neuro-Ophthalmic Supplement (P<0.001), binocular low-contrast acuity (2.5%, 1.25%, P<0.001, and high-contrast VA (P=0.003). Monocular low-contrast vision scores (P=0.001-0.009) and RNFL thickness (P=0.001) were also reduced in eyes of patients with worse K-D scores (GEE models accounting for age and within-patient, inter-eye correlations). Patients with a history of optic neuritis (ON) had increased (worse) K-D scores. Patients who classified their work disability status as disabled (receiving disability pension) did worse on K-D testing compared to those working full-time (P=0.001, accounting for age). The K-D test, a <2 minute bedside test of rapid number naming, is associated with visual dysfunction, neurologic impairment, and reduced vision-specific QOL in patients with MS. Scores reflect work disability as well as structural changes as measured by OCT imaging. History of ON and abnormal binocular acuities were associated with worse K-D scores, suggesting that abnormalities detected by K-D may go along with afferent dysfunction in MS patients. A brief test that requires saccadic eye movements, K-D should be considered for future MS trials as a rapid visual performance measure. Copyright © 2014 Elsevier B.V. All rights reserved.

Using the auxiliary camera for system calibration of 3D measurement by digital speckle

NASA Astrophysics Data System (ADS)

Xue, Junpeng; Su, Xianyu; Zhang, Qican

2014-06-01

The study of 3D shape measurement by digital speckle temporal sequence correlation have drawn a lot of attention by its own advantages, however, the measurement mainly for depth z-coordinate, horizontal physical coordinate (x, y) are usually marked as image pixel coordinate. In this paper, a new approach for the system calibration is proposed. With an auxiliary camera, we made up the temporary binocular vision system, which are used for the calibration of horizontal coordinates (mm) while the temporal sequence reference-speckle-sets are calibrated. First, the binocular vision system has been calibrated using the traditional method. Then, the digital speckles are projected on the reference plane, which is moved by equal distance in the direction of depth, temporal sequence speckle images are acquired with camera as reference sets. When the reference plane is in the first position and final position, crossed fringe pattern are projected to the plane respectively. The control points of pixel coordinates are extracted by Fourier analysis from the images, and the physical coordinates are calculated by the binocular vision. The physical coordinates corresponding to each pixel of the images are calculated by interpolation algorithm. Finally, the x and y corresponding to arbitrary depth value z are obtained by the geometric formula. Experiments prove that our method can fast and flexibly measure the 3D shape of an object as point cloud.

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

PubMed

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

2013-05-28

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

Association Between Undetected 10-2 Visual Field Damage and Vision-Related Quality of Life in Patients With Glaucoma.

PubMed

Blumberg, Dana M; De Moraes, Carlos Gustavo; Prager, Alisa J; Yu, Qi; Al-Aswad, Lama; Cioffi, George A; Liebmann, Jeffrey M; Hood, Donald C

2017-07-01

Recent evidence supports the presence of macular damage (within 8° of the central field) to retinal ganglion cells and associated central visual field (VF) defects in glaucoma, even in early stages. Despite this, to our knowledge, the association of 10-2 VF damage with vision-related quality of life (QOL) has not been well studied. To determine the association between QOL and visual function as measured by 24-2 and 10-2 VFs in patients with primary open-angle glaucoma and to test the hypothesis that patients with vision-related QOL disproportionate to their 24-2 VF status may exhibit 10-2 damage overlooked by the 24-2 test. In this cross-sectional analysis of observational cohort study data taken from a tertiary care specialty practice, 113 patients with glaucoma with the entire range of 24-2 VF damage completed the National Eye Institute Visual Function Questionnaire (NEI VFQ-25). Data were collected from May 2014 to January 2015 and were analyzed from March 2016 to May 2016. Standardized binocular 24-2 and 10-2 VF sensitivities were calculated for each patient. Association of binocular 24-2 and 10-2 VF sensitivity with Rasch-calibrated NEI VFQ-25 scores. Detection of outliers was based on Cook distance of the regression of binocular 24-2 and NEI VFQ-25 score. Outlier association with QOL was then assessed using a linear regression model, with binocular 10-2 VF sensitivity as the independent variable. Of the 113 patients, the mean (SD) age was 70.1 (10.9) years, and 51 (45.1%) were male and 71 (62.8%) were white. The composite NEI VFQ-25 score was associated with both binocular 24-2 (β = 1.95; 95% CI, 0.47-3.43; P = .01) and 10-2 (β = 2.57; 95% CI, 1.12-4.01; P = .001) sensitivities, but the 10-2 VF univariable model showed an almost 2-fold better fit to the data (R2 = 9.2% vs 4.9%). However, the binocular 10-2 sensitivities of 24-2 outliers had the strongest association with the composite NEI VFQ-25 scores (β = 2.78; 95% CI, 0.84-4.72; P = .006.) and the best fit to the data (R2 = 18.2%.). The 10-2 VF model showed a stronger association with NEI VFQ-25 score than the 24-2 VF model. Patients with disproportionately low quality of vision relative to patients with 24-2 VF damage may have damage on the central field missed by the 24-2 grid. Future prospective testing, including additional dimensions of quality of life, is indicated.

On-line bolt-loosening detection method of key components of running trains using binocular vision

NASA Astrophysics Data System (ADS)

Xie, Yanxia; Sun, Junhua

2017-11-01

Bolt loosening, as one of hidden faults, affects the running quality of trains and even causes serious safety accidents. However, the developed fault detection approaches based on two-dimensional images cannot detect bolt-loosening due to lack of depth information. Therefore, we propose a novel online bolt-loosening detection method using binocular vision. Firstly, the target detection model based on convolutional neural network (CNN) is used to locate the target regions. And then, stereo matching and three-dimensional reconstruction are performed to detect bolt-loosening faults. The experimental results show that the looseness of multiple bolts can be characterized by the method simultaneously. The measurement repeatability and precision are less than 0.03mm, 0.09mm respectively, and its relative error is controlled within 1.09%.

Attention in dichoptic and binocular vision

NASA Technical Reports Server (NTRS)

Kimchi, Ruth; Rubin, Yifat; Gopher, Daniel; Raij, David

1989-01-01

The ability of human subjected to mobilize attention and cope with task requirements under dichoptic and binocular viewing was investigated in an experiment employing a target search task. Subjects were required to search for a target at either the global level, the local level, or at both levels of a compound stimulus. The tasks were performed in a focused attention condition in which subjects had to attend to the stimulus presented to one eye/field (under dichoptic and binocular viewings, respectively) and to ignore the stimulus presented to the irrelevant eye/field, and in a divided attention condition in which subjects had to attend to the stimuli presented to both eyes/fields. Subjects' performance was affected mainly by attention conditions which interacted with task requirements, rather than by viewing situation. An interesting effect of viewing was found for the local-directed search task in which the cost of dividing attention was higher under binocular than under dichoptic viewing.

Comparing the Impact of Refractive and Non-Refractive Vision Loss on Functioning and Disability: The Salisbury Eye Evaluation

PubMed Central

Zebardast, Nazlee; Swenor, Bonnielin K.; van Landingham, Suzanne W.; Massof, Robert W.; Munoz, Beatriz; West, Sheila K.; Ramulu, Pradeep Y.

2015-01-01

Purpose To compare the effects of uncorrected refractive error (URE) and non-refractive visual impairment (VI) on performance and disability measures. Design Cross-sectional population-based study. Participants 2469 individuals with binocular presenting visual acuity (PVA) of 20/80 or better who participated in the first round of the Salisbury Eye Evaluation study. Methods URE was defined as binocular PVA of 20/30 or worse, improving to better than 20/30 with subjective refraction. VI was defined as post-refraction binocular best corrected visual acuity (BCVA) of 20/30 or worse. The visual acuity decrement attributable to VI was calculated as the difference between BCVA and 20/30 while that due to URE was taken as the difference between PVA and BCVA. Multivariable regression analyses were used to assess the disability impact of 1) vision status (VI, URE, or normal vision) using the group with normal vision as reference, and 2) a one-line decrement in acuity due to VI or URE. Main Outcome Measures Objective measures of visual function were obtained from timed performance of mobility and near vision tasks, self-reported driving cessation, and self-reported visual difficulty measured by the Activities of Daily Vision (ADV) scale. ADV responses were analyzed using Rasch analysis to determine visual ability. Results Compared to individuals with normal vision, subjects with VI (n=191) had significantly poorer objective and subjective visual functioning in all metrics examined (p<0.05) while subjects with URE (n=132) demonstrated slower walking speeds, slower near task performance, more frequent driving cessation and lower ADV scores (p<0.05), but did not demonstrate slower stair climbing or descent speed. For all functional metrics evaluated, the impact of VI was greater than the impact of URE. The impact of a one-line VA decrement due to VI was associated with greater deficits in mobility measures and driving cessation when compared to a one-line VA decrement due to URE. Conclusions VI is associated with greater disability than URE across a wide variety of functional measures, even in analyses adjusting for the severity of vision loss. Refractive and non-refractive vision loss should be distinguished in studies evaluating visual disability, and should be understood to have differing consequences. PMID:25813453

Comparing the Impact of Refractive and Nonrefractive Vision Loss on Functioning and Disability: The Salisbury Eye Evaluation.

PubMed

Zebardast, Nazlee; Swenor, Bonnielin K; van Landingham, Suzanne W; Massof, Robert W; Munoz, Beatriz; West, Sheila K; Ramulu, Pradeep Y

2015-06-01

To compare the effects of uncorrected refractive error (URE) and nonrefractive visual impairment (VI) on performance and disability measures. Cross-sectional, population-based study. A total of 2469 individuals with binocular presenting visual acuity (PVA) of ≥ 20/80 who participated in the first round of the Salisbury Eye Evaluation study. The URE was defined as binocular PVA of ≤ 20/30, improving to >20/30 with subjective refraction. The VI was defined as post-refraction binocular best-corrected visual acuity (BCVA) of ≤ 20/30. The visual acuity decrement due to VI was calculated as the difference between BCVA and 20/30, whereas visual acuity due to URE was taken as the difference between PVA and BCVA. Multivariable regression analyses were used to assess the disability impact of (1) vision status (VI, URE, or normal vision) using the group with normal vision as reference and (2) a 1-line decrement in acuity due to VI or URE. Objective measures of visual function were obtained from timed performance of mobility and near vision tasks, self-reported driving cessation, and self-reported visual difficulty measured by the Activities of Daily Vision (ADV) scale. The ADV responses were analyzed using Rasch analysis to determine visual ability. Compared with individuals with normal vision, subjects with VI (n = 191) had significantly poorer objective and subjective visual functioning in all metrics examined (P < 0.05), whereas subjects with URE (n = 132) demonstrated slower walking speeds, slower near task performance, more frequent driving cessation, and lower ADV scores (P < 0.05), but did not demonstrate slower stair climbing or descent speed. For all functional metrics evaluated, the impact of VI was greater than the impact of URE. The impact of a 1-line VA decrement due to VI was associated with greater deficits in mobility measures and driving cessation when compared with a 1-line VA decrement due to URE. Visual impairment is associated with greater disability than URE across a wide variety of functional measures, even in analyses adjusting for the severity of vision loss. Refractive and nonrefractive vision loss should be distinguished in studies evaluating visual disability and be understood to have differing consequences. Copyright © 2015 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

The minimum test battery to screen for binocular vision anomalies: report 3 of the BAND study.

PubMed

Hussaindeen, Jameel Rizwana; Rakshit, Archayeeta; Singh, Neeraj Kumar; Swaminathan, Meenakshi; George, Ronnie; Kapur, Suman; Scheiman, Mitchell; Ramani, Krishna Kumar

2018-03-01

This study aims to report the minimum test battery needed to screen non-strabismic binocular vision anomalies (NSBVAs) in a community set-up. When large numbers are to be screened we aim to identify the most useful test battery when there is no opportunity for a more comprehensive and time-consuming clinical examination. The prevalence estimates and normative data for binocular vision parameters were estimated from the Binocular Vision Anomalies and Normative Data (BAND) study, following which cut-off estimates and receiver operating characteristic curves to identify the minimum test battery have been plotted. In the receiver operating characteristic phase of the study, children between nine and 17 years of age were screened in two schools in the rural arm using the minimum test battery, and the prevalence estimates with the minimum test battery were found. Receiver operating characteristic analyses revealed that near point of convergence with penlight and red filter (> 7.5 cm), monocular accommodative facility (< 10 cycles per minute), and the difference between near and distance phoria (> 1.25 prism dioptres) were significant factors with cut-off values for best sensitivity and specificity. This minimum test battery was applied to a cohort of 305 children. The mean (standard deviation) age of the subjects was 12.7 (two) years with 121 males and 184 females. Using the minimum battery of tests obtained through the receiver operating characteristic analyses, the prevalence of NSBVAs was found to be 26 per cent. Near point of convergence with penlight and red filter > 10 cm was found to have the highest sensitivity (80 per cent) and specificity (73 per cent) for the diagnosis of convergence insufficiency. For the diagnosis of accommodative infacility, monocular accommodative facility with a cut-off of less than seven cycles per minute was the best predictor for screening (92 per cent sensitivity and 90 per cent specificity). The minimum test battery of near point of convergence with penlight and red filter, difference between distance and near phoria, and monocular accommodative facility yield good sensitivity and specificity for diagnosis of NSBVAs in a community set-up. © 2017 Optometry Australia.

Peripheral Vision Can Influence Eye Growth and Refractive Development in Infant Monkeys

PubMed Central

Smith, Earl L.; Kee, Chea-su; Ramamirtham, Ramkumar; Qiao-Grider, Ying; Hung, Li-Fang

2006-01-01

PURPOSE Given the prominence of central vision in humans, it has been assumed that visual signals from the fovea dominate emmetropization. The purpose of this study was to examine the impact of peripheral vision on emmetropization. METHODS Bilateral, peripheral form deprivation was produced in 12 infant monkeys by rearing them with diffusers that had either 4- or 8-mm apertures centered on the pupils of each eye, to allow 24° or 37° of unrestricted central vision, respectively. At the end of the lens-rearing period, an argon laser was used to ablate the fovea in one eye of each of seven monkeys. Subsequently, all the animals were allowed unrestricted vision. Refractive error and axial dimensions were measured along the pupillary axis by retinoscopy and A-scan ultrasonography, respectively. Control data were obtained from 21 normal monkeys and 3 infants reared with binocular plano lenses. RESULTS Nine of the 12 treated monkeys had refractive errors that fell outside the 10th- and 90th-percentile limits for the age-matched control subjects, and the average refractive error for the treated animals was more variable and significantly less hyperopic/more myopic (+0.03 ± 2.39 D vs. +2.39 ± 0.92 D). The refractive changes were symmetric in the two eyes of a given animal and axial in nature. After lens removal, all the treated monkeys recovered from the induced refractive errors. No interocular differences in the recovery process were observed in the animals with monocular foveal lesions. CONCLUSIONS On the one hand, the peripheral retina can contribute to emmetropizing responses and to ametropias produced by an abnormal visual experience. On the other hand, unrestricted central vision is not sufficient to ensure normal refractive development, and the fovea is not essential for emmetropizing responses. PMID:16249469

Binocular vision in a virtual world: visual deficits following the wearing of a head-mounted display.

PubMed

Mon-Williams, M; Wann, J P; Rushton, S

1993-10-01

The short-term effects on binocular stability of wearing a conventional head-mounted display (HMD) to explore a virtual reality environment were examined. Twenty adult subjects (aged 19-29 years) wore a commercially available HMD for 10 min while cycling around a computer generated 3-D world. The twin screen presentations were set to suit the average interpupillary distance of our subject population, to mimic the conditions of public access virtual reality systems. Subjects were examined before and after exposure to the HMD and there were clear signs of induced binocular stress for a number of the subjects. The implications of introducing such HMDs into the workplace and entertainment environments are discussed.

Discrimination of binocular color mixtures in dichromacy: evaluation of the Maxwell-Cornsweet conjecture

NASA Astrophysics Data System (ADS)

Knoblauch, Kenneth; McMahon, Matthew J.

1995-10-01

We tested the Maxwell-Cornsweet conjecture that differential spectral filtering of the two eyes can increase the dimensionality of a dichromat's color vision. Sex-linked dichromats wore filters that differentially passed long- and middle-wavelength regions of the spectrum to each eye. Monocularly, temporal modulation thresholds (1.5 Hz) for color mixtures from the Rayleigh region of the spectrum were accounted for by a single, univariant mechanism. Binocularly, univariance was rejected because, as in monocular viewing by trichromats, in no color direction could silent substitution of the color mixtures be obtained. Despite the filter-aided increase in dimension, estimated wavelength discrimination was quite poor in this spectral region, suggesting a limit to the effectiveness of this technique. binocular summation.

Comparative visual performance with monofocal and multifocal intraocular lenses

PubMed Central

Gundersen, Kjell Gunnar; Potvin, Richard

2013-01-01

Background To compare near, intermediate, and distance vision, and quality of vision using appropriate subjective questionnaires, when monofocal or apodized diffractive multifocal intraocular lenses (IOLs) are binocularly implanted. Methods Patients with different binocular IOLs implanted were recruited after surgery and had their visual acuity tested, and quality of vision evaluated, at a single diagnostic visit between 3 and 8 months after second-eye surgery. Lenses tested included an aspheric monofocal and two apodized diffractive multifocal IOLs with slightly different design parameters. A total of 94 patients were evaluated. Results Subjects with the ReSTOR® +2.5 D IOL had better near and intermediate vision than those subjects with a monofocal IOL. Intermediate vision was similar to, and near vision slightly lower than, that of subjects with a ReSTOR® +3.0 D IOL implanted. The preferred reading distance was slightly farther out for the +2.5 D relative to the +3.0 D lens, and farthest for the monofocal. Visual acuity at the preferred reading distance was equal with the two multifocal IOLs and significantly worse with the monofocal IOL. Quality of vision measures were highest with the monofocal IOL and similar between the two multifocal IOLs. Conclusion The data indicate that the ReSTOR +2.5 D IOL provided good intermediate and functional near vision for patients who did not want to accept a higher potential for visual disturbances associated with the ReSTOR +3.0 D IOL, but wanted more near vision than a monofocal IOL generally provides. Quality of vision was not significantly different between the multifocal IOLs, but patient self-selection for each lens type may have been a factor. PMID:24143064

Overcoming Presbyopia by Manipulating the Eyes' Optics

NASA Astrophysics Data System (ADS)

Zheleznyak, Leonard A.

Presbyopia, the age-related loss of accommodation, is a visual condition affecting all adults over the age of 45 years. In presbyopia, individuals lose the ability to focus on nearby objects, due to a lifelong growth and stiffening of the eye's crystalline lens. This leads to poor near visual performance and affects patients' quality of life. The objective of this thesis is aimed towards the correction of presbyopia and can be divided into four aims. First, we examined the characteristics and limitations of currently available strategies for the correction of presbyopia. A natural-view wavefront sensor was used to objectively measure the accommodative ability of patients implanted with an accommodative intraocular lens (IOL). Although these patients had little accommodative ability based on changes in power, pupil miosis and higher order aberrations led to an improvement in through-focus retinal image quality in some cases. To quantify the through-focus retinal image quality of accommodative and multifocal IOLs directly, an adaptive optics (AO) IOL metrology system was developed. Using this system, the impact of corneal aberrations in regard to presbyopia-correcting IOLs was assessed, providing an objective measure of through-focus retinal image quality and practical guidelines for patient selection. To improve upon existing multifocal designs, we investigated retinal image quality metrics for the prediction of through-focus visual performance. The preferred metric was based on the fidelity of an image convolved with an aberrated point spread function. Using this metric, we investigated the potential of higher order aberrations and pupil amplitude apodization to increase the depth of focus of the presbyopic eye. Thirdly, we investigated modified monovision, a novel binocular approach to presbyopia correction using a binocular AO vision simulator. In modified monovision, different magnitudes of defocus and spherical aberration are introduced to each eye, thereby taking advantage of the binocular visual system. Several experiments using the binocular AO vision simulator found modified monovision led to significant improvements in through-focus visual performance, binocular summation and stereoacuity, as compared to traditional monovision. Finally, we addressed neural factors, affecting visual performance in modified monovision, such as ocular dominance and neural plasticity. We found that pairing modified monovision with a vision training regimen may further improve visual performance beyond the limits set by optics via neural plasticity. This opens the door to an exciting new avenue of vision correction to accompany optical interventions. The research presented in this thesis offers important guidelines for the clinical and scientific communities. Furthermore, the techniques described herein may be applied to other fields of ophthalmology, such as childhood myopia progression.

Railway clearance intrusion detection method with binocular stereo vision

NASA Astrophysics Data System (ADS)

Zhou, Xingfang; Guo, Baoqing; Wei, Wei

2018-03-01

In the stage of railway construction and operation, objects intruding railway clearance greatly threaten the safety of railway operation. Real-time intrusion detection is of great importance. For the shortcomings of depth insensitive and shadow interference of single image method, an intrusion detection method with binocular stereo vision is proposed to reconstruct the 3D scene for locating the objects and judging clearance intrusion. The binocular cameras are calibrated with Zhang Zhengyou's method. In order to improve the 3D reconstruction speed, a suspicious region is firstly determined by background difference method of a single camera's image sequences. The image rectification, stereo matching and 3D reconstruction process are only executed when there is a suspicious region. A transformation matrix from Camera Coordinate System(CCS) to Track Coordinate System(TCS) is computed with gauge constant and used to transfer the 3D point clouds into the TCS, then the 3D point clouds are used to calculate the object position and intrusion in TCS. The experiments in railway scene show that the position precision is better than 10mm. It is an effective way for clearance intrusion detection and can satisfy the requirement of railway application.

Research and Development of Target Recognition and Location Crawling Platform based on Binocular Vision

NASA Astrophysics Data System (ADS)

Xu, Weidong; Lei, Zhu; Yuan, Zhang; Gao, Zhenqing

2018-03-01

The application of visual recognition technology in industrial robot crawling and placing operation is one of the key tasks in the field of robot research. In order to improve the efficiency and intelligence of the material sorting in the production line, especially to realize the sorting of the scattered items, the robot target recognition and positioning crawling platform based on binocular vision is researched and developed. The images were collected by binocular camera, and the images were pretreated. Harris operator was used to identify the corners of the images. The Canny operator was used to identify the images. Hough-chain code recognition was used to identify the images. The target image in the image, obtain the coordinates of each vertex of the image, calculate the spatial position and posture of the target item, and determine the information needed to capture the movement and transmit it to the robot control crawling operation. Finally, In this paper, we use this method to experiment the wrapping problem in the express sorting process The experimental results show that the platform can effectively solve the problem of sorting of loose parts, so as to achieve the purpose of efficient and intelligent sorting.

Distance vision after bilateral implantation of AcrySof toric intraocular lenses: a randomized, controlled, prospective trial

PubMed Central

Zhang, Jin-Song; Zhao, Jiang-Yue; Sun, Qi; Ma, Li-Wei

2011-01-01

AIM To evaluate the distance vision of Chinese patients with cataracts and corneal astigmatism after implantation of bilateral AcrySof toric intraocular lens (IOL) versus bilateral AcrySof spherical IOL. METHODS This study randomized 60 patients into equal groups to receive toric IOL or spherical IOL. IOL powers targeting emmetropia were selected for 93% of toric IOL patients and for 90% of spherical IOL patients. Assessments included monocular and binocular distance vision, with and without best correction. Patients also completed surveys about their distance vision. RESULTS Preoperatively, the two study groups were similar in age, in distance visual acuity, and in the magnitude of corneal astigmatism. At 6 months postoperative, binocular uncorrected distance vision was 0.06±0.14 logMAR in the AcrySof toric IOL group, significantly better than the 0.14±0.11 logMAR in the spherical IOL group (P<0.05). For eyes with emmetropia as a target, the equivalent of 20/20 uncorrected vision was more likely (P<0.001) in the toric IOL group (36% of eyes) than in the spherical IOL group (4% of eyes). No patients in the emmetropia/toric IOL group used distance glasses, as compared to 52% of patients in the emmetropia/spherical IOL group. All patients were satisfied or highly satisfied. Quality of distance vision was rated higher by toric IOL patients than by spherical IOL patients (P<0.05). CONCLUSION Bilateral AcrySof toric IOL is superior to bilateral spherical IOL in providing uncorrected distance vision to cataract patients with corneal astigmatism. PMID:22553636

Development and matching of binocular orientation preference in mouse V1.

PubMed

Bhaumik, Basabi; Shah, Nishal P

2014-01-01

Eye-specific thalamic inputs converge in the primary visual cortex (V1) and form the basis of binocular vision. For normal binocular perceptions, such as depth and stereopsis, binocularly matched orientation preference between the two eyes is required. A critical period of binocular matching of orientation preference in mice during normal development is reported in literature. Using a reaction diffusion model we present the development of RF and orientation selectivity in mouse V1 and investigate the binocular orientation preference matching during the critical period. At the onset of the critical period the preferred orientations of the modeled cells are mostly mismatched in the two eyes and the mismatch decreases and reaches levels reported in juvenile mouse by the end of the critical period. At the end of critical period 39% of cells in binocular zone in our model cortex is orientation selective. In literature around 40% cortical cells are reported as orientation selective in mouse V1. The starting and the closing time for critical period determine the orientation preference alignment between the two eyes and orientation tuning in cortical cells. The absence of near neighbor interaction among cortical cells during the development of thalamo-cortical wiring causes a salt and pepper organization in the orientation preference map in mice. It also results in much lower % of orientation selective cells in mice as compared to ferrets and cats having organized orientation maps with pinwheels.

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

PubMed

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.

Visual performance after the implantation of a new trifocal intraocular lens

PubMed Central

Vryghem, Jérôme C; Heireman, Steven

2013-01-01

Purpose To evaluate the subjective and objective visual results after the implantation of a new trifocal diffractive intraocular lens. Methods A new trifocal diffractive intraocular lens was designed combining two superimposed diffractive profiles: one with +1.75 diopters (D) addition for intermediate vision and the other with +3.50 D addition for near vision. Fifty eyes of 25 patients that were operated on by one surgeon are included in this study. The uncorrected and best distance-corrected monocular and binocular, near, intermediate, and distance visual acuities, contrast sensitivity, and defocus curves were measured 6 months postoperatively. In addition to the standard clinical follow-up, a questionnaire evaluating individual satisfaction and quality of life was submitted to the patients. Results The mean age of patients at the time of surgery was 70 ± 10 years. The mean uncorrected and corrected monocular distance visual acuity (VA) were LogMAR 0.06 ± 0.10 and LogMAR 0.00 ± 0.08, respectively. The outcomes for the binocular uncorrected distance visual acuity were almost the same (LogMAR −0.04 ± 0.09). LogMAR −010 ± 0.15 and 0.02 ± 0.06 were measured for the binocular uncorrected intermediate and near VA, respectively. The distance-corrected visual acuity was maintained in mesopic conditions. The contrast sensitivity was similar to that obtained after implantation of a bifocal intraocular lens and did not decrease in mesopic conditions. The binocular defocus curve confirms good VA even in the intermediate distance range, with a moderate decrease of less than LogMAR 0.2 at −1.5 D, with respect to the best distance VA at 0 D defocus. Patient satisfaction was high. No discrepancy between the objective and subjective outcomes was evidenced. Conclusion The introduction of a third focus in diffractive multifocal intraocular lenses improves the intermediate vision with minimal visual discomfort for the patient. PMID:24124348

Binocular function to increase visual outcome in patients implanted with a diffractive trifocal intraocular lens.

PubMed

Kretz, Florian T A; Müller, Matthias; Gerl, Matthias; Gerl, Ralf H; Auffarth, Gerd U

2015-08-21

To evaluate binocular visual outcome for near, intermediate and distance compared to monocular visual outcome at the same distances in patients implanted with a diffractive trifocal intraocular lens (IOL). The study comprised of 100 eyes of 50 patients that underwent bilateral refractive lens exchange or cataract surgery with implantation of a multifocal diffractive IOL (AT LISA tri 839MP, Carl Zeiss Meditech, Germany). A complete ophthalmological examination was performed preoperatively and 3 month postoperatively. The main outcome measures were monocular and binocular uncorrected distance (UDVA), corrected distance (CDVA), uncorrected intermediate (UIVA), and uncorrected near visual acuities (UNVA), keratometry, and manifest refraction. The mean age was 59.28 years ± 9.6 [SD] (range 44-79 years), repectively. There was significant improvement in UDVA, UIVA, UNVA and CDVA. Comparing the monocular results to the binocular results there was a statistical significant better binocular outcome in all distances (UDVA p = 0.036; UIVA p < 0.0001; UNVA p = 0.001). The postoperative manifest refraction was in 86 % of patients within ± 0.50 [D]. The trifocal IOL improved near, intermediate, and distance vision compared to preoperatively. In addition a statistical significant increase for binocular visual function in all distances could be found. German Clinical Trials Register (DRKS) DRKS00007837.

Advanced helmet vision system (AHVS) integrated night vision helmet mounted display (HMD)

NASA Astrophysics Data System (ADS)

Ashcraft, Todd W.; Atac, Robert

2012-06-01

Gentex Corporation, under contract to Naval Air Systems Command (AIR 4.0T), designed the Advanced Helmet Vision System to provide aircrew with 24-hour, visor-projected binocular night vision and HMD capability. AHVS integrates numerous key technologies, including high brightness Light Emitting Diode (LED)-based digital light engines, advanced lightweight optical materials and manufacturing processes, and innovations in graphics processing software. This paper reviews the current status of miniaturization and integration with the latest two-part Gentex modular helmet, highlights the lessons learned from previous AHVS phases, and discusses plans for qualification and flight testing.

Analysis on detection accuracy of binocular photoelectric instrument optical axis parallelism digital calibration instrument

NASA Astrophysics Data System (ADS)

Ying, Jia-ju; Yin, Jian-ling; Wu, Dong-sheng; Liu, Jie; Chen, Yu-dan

2017-11-01

Low-light level night vision device and thermal infrared imaging binocular photoelectric instrument are used widely. The maladjustment of binocular instrument ocular axises parallelism will cause the observer the symptom such as dizziness, nausea, when use for a long time. Binocular photoelectric equipment digital calibration instrument is developed for detecting ocular axises parallelism. And the quantitative value of optical axis deviation can be quantitatively measured. As a testing instrument, the precision must be much higher than the standard of test instrument. Analyzes the factors that influence the accuracy of detection. Factors exist in each testing process link which affect the precision of the detecting instrument. They can be divided into two categories, one category is factors which directly affect the position of reticle image, the other category is factors which affect the calculation the center of reticle image. And the Synthesize error is calculated out. And further distribute the errors reasonably to ensure the accuracy of calibration instruments.

Bionic Vision-Based Intelligent Power Line Inspection System

PubMed Central

Ma, Yunpeng; He, Feijia; Xu, Jinxin

2017-01-01

Detecting the threats of the external obstacles to the power lines can ensure the stability of the power system. Inspired by the attention mechanism and binocular vision of human visual system, an intelligent power line inspection system is presented in this paper. Human visual attention mechanism in this intelligent inspection system is used to detect and track power lines in image sequences according to the shape information of power lines, and the binocular visual model is used to calculate the 3D coordinate information of obstacles and power lines. In order to improve the real time and accuracy of the system, we propose a new matching strategy based on the traditional SURF algorithm. The experimental results show that the system is able to accurately locate the position of the obstacles around power lines automatically, and the designed power line inspection system is effective in complex backgrounds, and there are no missing detection instances under different conditions. PMID:28203269

Environmental Recognition and Guidance Control for Autonomous Vehicles using Dual Vision Sensor and Applications

NASA Astrophysics Data System (ADS)

Moriwaki, Katsumi; Koike, Issei; Sano, Tsuyoshi; Fukunaga, Tetsuya; Tanaka, Katsuyuki

We propose a new method of environmental recognition around an autonomous vehicle using dual vision sensor and navigation control based on binocular images. We consider to develop a guide robot that can play the role of a guide dog as the aid to people such as the visually impaired or the aged, as an application of above-mentioned techniques. This paper presents a recognition algorithm, which finds out the line of a series of Braille blocks and the boundary line between a sidewalk and a roadway where a difference in level exists by binocular images obtained from a pair of parallelarrayed CCD cameras. This paper also presents a tracking algorithm, with which the guide robot traces along a series of Braille blocks and avoids obstacles and unsafe areas which exist in the way of a person with the guide robot.

Bubble behavior characteristics based on virtual binocular stereo vision

NASA Astrophysics Data System (ADS)

Xue, Ting; Xu, Ling-shuang; Zhang, Shang-zhen

2018-01-01

The three-dimensional (3D) behavior characteristics of bubble rising in gas-liquid two-phase flow are of great importance to study bubbly flow mechanism and guide engineering practice. Based on the dual-perspective imaging of virtual binocular stereo vision, the 3D behavior characteristics of bubbles in gas-liquid two-phase flow are studied in detail, which effectively increases the projection information of bubbles to acquire more accurate behavior features. In this paper, the variations of bubble equivalent diameter, volume, velocity and trajectory in the rising process are estimated, and the factors affecting bubble behavior characteristics are analyzed. It is shown that the method is real-time and valid, the equivalent diameter of the rising bubble in the stagnant water is periodically changed, and the crests and troughs in the equivalent diameter curve appear alternately. The bubble behavior characteristics as well as the spiral amplitude are affected by the orifice diameter and the gas volume flow.

Development and matching of binocular orientation preference in mouse V1

PubMed Central

Bhaumik, Basabi; Shah, Nishal P.

2014-01-01

Eye-specific thalamic inputs converge in the primary visual cortex (V1) and form the basis of binocular vision. For normal binocular perceptions, such as depth and stereopsis, binocularly matched orientation preference between the two eyes is required. A critical period of binocular matching of orientation preference in mice during normal development is reported in literature. Using a reaction diffusion model we present the development of RF and orientation selectivity in mouse V1 and investigate the binocular orientation preference matching during the critical period. At the onset of the critical period the preferred orientations of the modeled cells are mostly mismatched in the two eyes and the mismatch decreases and reaches levels reported in juvenile mouse by the end of the critical period. At the end of critical period 39% of cells in binocular zone in our model cortex is orientation selective. In literature around 40% cortical cells are reported as orientation selective in mouse V1. The starting and the closing time for critical period determine the orientation preference alignment between the two eyes and orientation tuning in cortical cells. The absence of near neighbor interaction among cortical cells during the development of thalamo-cortical wiring causes a salt and pepper organization in the orientation preference map in mice. It also results in much lower % of orientation selective cells in mice as compared to ferrets and cats having organized orientation maps with pinwheels. PMID:25104927

A novel apparatus for testing binocular function using the 'CyberDome' three-dimensional hemispherical visual display system.

PubMed

Handa, T; Ishikawa, H; Shimizu, K; Kawamura, R; Nakayama, H; Sawada, K

2009-11-01

Virtual reality has recently been highlighted as a promising medium for visual presentation and entertainment. A novel apparatus for testing binocular visual function using a hemispherical visual display system, 'CyberDome', has been developed and tested. Subjects comprised 40 volunteers (mean age, 21.63 years) with corrected visual acuity of -0.08 (LogMAR) or better, and stereoacuity better than 100 s of arc on the Titmus stereo test. Subjects were able to experience visual perception like being surrounded by visual images, a feature of the 'CyberDome' hemispherical visual display system. Visual images to the right and left eyes were projected and superimposed on the dome screen, allowing test images to be seen independently by each eye using polarizing glasses. The hemispherical visual display was 1.4 m in diameter. Three test parameters were evaluated: simultaneous perception (subjective angle of strabismus), motor fusion amplitude (convergence and divergence), and stereopsis (binocular disparity at 1260, 840, and 420 s of arc). Testing was performed in volunteer subjects with normal binocular vision, and results were compared with those using a major amblyoscope. Subjective angle of strabismus and motor fusion amplitude showed a significant correlation between our test and the major amblyoscope. All subjects could perceive the stereoscopic target with a binocular disparity of 480 s of arc. Our novel apparatus using the CyberDome, a hemispherical visual display system, was able to quantitatively evaluate binocular function. This apparatus offers clinical promise in the evaluation of binocular function.

Stereopsis and aging.

PubMed

Norman, J Farley; Norman, Hideko F; Craft, Amy E; Walton, Crystal L; Bartholomew, Ashley N; Burton, Cory L; Wiesemann, Elizabeth Y; Crabtree, Charles E

2008-10-01

Three experiments investigated whether and to what extent increases in age affect the functionality of stereopsis. The observers' ages ranged from 18 to 83 years. The overall goal was to challenge the older stereoscopic visual system by utilizing high magnitudes of binocular disparity, ambiguous binocular disparity [cf., Julesz, B., & Chang, J. (1976). Interaction between pools of binocular disparity detectors tuned to different disparities. Biological Cybernetics, 22, 107-119], and by making binocular matching more difficult. In particular, Experiment 1 evaluated observers' abilities to discriminate ordinal depth differences away from the horopter using standing disparities of 6.5-46 min arc. Experiment 2 assessed observers' abilities to discriminate stereoscopic shape using line-element stereograms. The direction (crossed vs. uncrossed) and magnitude of the binocular disparity (13.7 and 51.5 min arc) were manipulated. Binocular matching was made more difficult by varying the orientations of corresponding line elements across the two eyes' views. The purpose of Experiment 3 was to determine whether the aging stereoscopic system can resolve ambiguous binocular disparities in a manner similar to that of younger observers. The results of all experiments demonstrated that older observers' stereoscopic vision is functionally comparable to that of younger observers in many respects. For example, both age groups exhibited a similar ability to discriminate depth and surface shape. The results also showed, however, that age-related differences in stereopsis do exist, and they become most noticeable when the older stereoscopic system is challenged by multiple simultaneous factors.

An ancient explanation of presbyopia based on binocular vision.

PubMed

Barbero, Sergio

2014-06-01

Presbyopia, understood as the age-related loss of ability to clearly see near objects, was known to ancient Greeks. However, few references to it can be found in ancient manuscripts. A relevant discussion on presbyopia appears in a book called Symposiacs written by Lucius Mestrius Plutarchus around 100 A.C. In this work, Plutarch provided four explanations of presbyopia, associated with different theories of vision. One of the explanations is particularly interesting as it is based on a binocular theory of vision. In this theory, vision is produced when visual rays, emanating from the eyes, form visual cones that impinge on the objects to be seen. Visual rays coming from old people's eyes, it was supposed, are weaker than those from younger people's eyes; so the theory, to be logically coherent, implies that this effect is compensated by the increase in light intensity due to the overlapping, at a certain distance, of the visual cones coming from both eyes. Thus, it benefits the reader to move the reading text further away from the eyes in order to increase the fusion area of both visual cones. The historical hypothesis taking into consideration that the astronomer Hipparchus of Nicaea was the source of Plutarch's explanation of the theory is discussed. © 2013 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

A Normative Data Set for the Clinical Assessment of Achromatic and Chromatic Contrast Sensitivity Using a qCSF Approach.

PubMed

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

2017-07-01

The measurement of achromatic sensitivity has been an important tool for monitoring subtle changes in vision as the result of disease or response to therapy. In this study, we aimed to provide a normative data set for achromatic and chromatic contrast sensitivity functions within a common cone contrast space using an abbreviated measurement approach suitable for clinical practice. In addition, we aimed to provide comparisons of achromatic and chromatic binocular summation across spatial frequency. We estimated monocular cone contrast sensitivity functions (CCSFs) using a quick Contrast Sensitivity Function (qCSF) approach for achromatic as well as isoluminant, L/M cone opponent, and S cone opponent stimuli in a healthy population of 51 subjects. We determined the binocular CCSFs for achromatic and chromatic vision to evaluate the degree of binocular summation across spatial frequency for these three different mechanisms in a subset of 20 subjects. Each data set shows consistent contrast sensitivity across the population. They highlight the extremely high cone contrast sensitivity of L/M cone opponency compared with the S-cone and achromatic responses. We also find that the two chromatic sensitivities are correlated across the healthy population. In addition, binocular summation for all mechanisms depends strongly on stimulus spatial frequency. This study, using an approach well suited to the clinic, is the first to provide a comparative normative data set for the chromatic and achromatic contrast sensitivity functions, yielding quantitative comparisons of achromatic, L/M cone opponent, and S cone opponent chromatic sensitivities as a function of spatial frequency.

An evaluation of clinical treatment of convergence insufficiency for children with reading difficulties.

PubMed

Dusek, Wolfgang A; Pierscionek, Barbara K; McClelland, Julie F

2011-08-11

The present study investigates two different treatment options for convergence insufficiency CI for a group of children with reading difficulties referred by educational institutes to a specialist eye clinic in Vienna. One hundred and thirty four subjects (aged 7-14 years) with reading difficulties were referred from an educational institute in Vienna, Austria for visual assessment. Each child was given either 8Δ base-in reading spectacles (n=51) or computerised home vision therapy (HTS) (n=51). Thirty two participants refused all treatment offered (clinical control group). A full visual assessment including reading speed and accuracy were conducted pre- and post-treatment. Factorial analyses demonstrated statistically significant changes between results obtained for visits 1 and 2 for total reading time, reading error score, amplitude of accommodation and binocular accommodative facility (within subjects effects) (p<0.05). Significant differences were also demonstrated between treatment groups for total reading time, reading error score and binocular accommodative facility (between subjects effects) (p<0.05). Reading difficulties with no apparent intellectual or psychological foundation may be due to a binocular vision anomaly such as convergence insufficiency. Both the HTS and prismatic correction are highly effective treatment options for convergence insufficiency. Prismatic correction can be considered an effective alternative to HTS.

The pursuit of stereopsis.

PubMed

Sharma, Pradeep

2018-02-01

Pediatric ophthalmologists are increasingly expected to promote, preserve, and restore binocular vision. Clinical studies on restoring alignment and stereopsis in the management of amblyopia, esotropia, exotropia, and complex strabismus are reviewed from the perspective of the author's published work and personal experiences. Treatment of amblyopia by means of optical rehabilitation, occlusion, or penalization has been reinforced by medical treatment and perceptual training with monocular or binocular video games. Studies indicate that early management of esotropia and alignment within 8 Δ is required for regaining stereopsis. In the surgical management of intermittent exotropia, distance stereopsis by Frisby Davis Distance stereotest can predict better stereopsis, with patients having preoperative distance stereopsis of <70 arcsec less likely to improve after surgery. The surgeon's armamentarium for correcting alignment and restoring binocular vision include procedures such as adjustable, partial vertical rectus muscle transposition in cases of exotropic Duane syndrome and lateral rectus palsy, periosteal fixation of the globe or of the lateral rectus muscle, and medial transposition of the split lateral rectus muscle. The goal for present-day strabismologists is not merely to correct strabismus but also to achieve alignment of eyes in time to ensure normal development of stereopsis in children and to restore alignment and stereopsis in adults. Copyright © 2017 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.

The consequence of spatial visual processing dysfunction caused by traumatic brain injury (TBI).

PubMed

Padula, William V; Capo-Aponte, Jose E; Padula, William V; Singman, Eric L; Jenness, Jonathan

2017-01-01

A bi-modal visual processing model is supported by research to affect dysfunction following a traumatic brain injury (TBI). TBI causes dysfunction of visual processing affecting binocularity, spatial orientation, posture and balance. Research demonstrates that prescription of prisms influence the plasticity between spatial visual processing and motor-sensory systems improving visual processing and reducing symptoms following a TBI. The rationale demonstrates that visual processing underlies the functional aspects of binocularity, balance and posture. The bi-modal visual process maintains plasticity for efficiency. Compromise causes Post Trauma Vision Syndrome (PTVS) and Visual Midline Shift Syndrome (VMSS). Rehabilitation through use of lenses, prisms and sectoral occlusion has inter-professional implications in rehabilitation affecting the plasticity of the bi-modal visual process, thereby improving binocularity, spatial orientation, posture and balance Main outcomes: This review provides an opportunity to create a new perspective of the consequences of TBI on visual processing and the symptoms that are often caused by trauma. It also serves to provide a perspective of visual processing dysfunction that has potential for developing new approaches of rehabilitation. Understanding vision as a bi-modal process facilitates a new perspective of visual processing and the potentials for rehabilitation following a concussion, brain injury or other neurological events.

Perceptual Visual Distortions in Adult Amblyopia and Their Relationship to Clinical Features

PubMed Central

Piano, Marianne E. F.; Bex, Peter J.; Simmers, Anita J.

2015-01-01

Purpose Develop a paradigm to map binocular perceptual visual distortions in adult amblyopes and visually normal controls, measure their stability over time, and determine the relationship between strength of binocular single vision and distortion magnitude. Methods Perceptual visual distortions were measured in 24 strabismic, anisometropic, or microtropic amblyopes (interocular acuity difference ≥ 0.200 logMAR or history of amblyopia treatment) and 10 controls (mean age 27.13 ± 10.20 years). The task was mouse-based target alignment on a stereoscopic liquid crystal display monitor, measured binocularly five times during viewing dichoptically through active shutter glasses, amblyopic eye viewing cross-hairs, fellow eye viewing single target dots (16 locations within central 5°), and five times nondichoptically, with all stimuli visible to either eye. Measurements were repeated over time (1 week, 1 month) in eight amblyopic subjects, evaluating test–retest reliability. Measurements were also correlated against logMAR visual acuity, horizontal prism motor fusion range, Frisby/Preschool Randot stereoacuity, and heterophoria/heterotropia prism cover test measurement. Results Sixty-seven percent (16/24) of amblyopes had significant perceptual visual distortions under dichoptic viewing conditions compared to nondichoptic viewing conditions and dichoptic control group performance. Distortions correlated with the strength of motor fusion (r = −0.417, P = 0.043) and log stereoacuity (r = 0.492, P = 0.015), as well as near angle of heterotropic/heterophoric deviation (r = 0.740, P < 0.001), and, marginally, amblyopia depth (r = 0.405, P = 0.049). Global distortion index (GDI, mean displacement) remained, overall, consistent over time (median change in GDI between baseline and 1 week = −0.03°, 1 month = −0.08°; x-axis Z = 4.4256, P < 0.001; y-axis Z = 5.0547, P < 0.001). Conclusions Perceptual visual distortions are stable over time and associated with poorer binocular function, greater amblyopia depth, and larger angles of ocular deviation. Assessment of distortions may be relevant for recent perceptual learning paradigms specifically targeting binocular vision. PMID:26284559

Hawk Eyes I: Diurnal Raptors Differ in Visual Fields and Degree of Eye Movement

PubMed Central

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

2010-01-01

Background Different strategies to search and detect prey may place specific demands on sensory modalities. We studied visual field configuration, degree of eye movement, and orbit orientation in three diurnal raptors belonging to the Accipitridae and Falconidae families. Methodology/Principal Findings We used an ophthalmoscopic reflex technique and an integrated 3D digitizer system. We found inter-specific variation in visual field configuration and degree of eye movement, but not in orbit orientation. Red-tailed Hawks have relatively small binocular areas (∼33°) and wide blind areas (∼82°), but intermediate degree of eye movement (∼5°), which underscores the importance of lateral vision rather than binocular vision to scan for distant prey in open areas. Cooper's Hawks' have relatively wide binocular fields (∼36°), small blind areas (∼60°), and high degree of eye movement (∼8°), which may increase visual coverage and enhance prey detection in closed habitats. Additionally, we found that Cooper's Hawks can visually inspect the items held in the tip of the bill, which may facilitate food handling. American Kestrels have intermediate-sized binocular and lateral areas that may be used in prey detection at different distances through stereopsis and motion parallax; whereas the low degree eye movement (∼1°) may help stabilize the image when hovering above prey before an attack. Conclusions We conclude that: (a) there are between-species differences in visual field configuration in these diurnal raptors; (b) these differences are consistent with prey searching strategies and degree of visual obstruction in the environment (e.g., open and closed habitats); (c) variations in the degree of eye movement between species appear associated with foraging strategies; and (d) the size of the binocular and blind areas in hawks can vary substantially due to eye movements. Inter-specific variation in visual fields and eye movements can influence behavioral strategies to visually search for and track prey while perching. PMID:20877645

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

PubMed

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

2010-09-22

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

Accommodative spasm in siblings: A unique finding

PubMed Central

Rutstein, Robert P

2010-01-01

Accommodative spasm is a rare condition occurring in children, adolescents, and young adults. A familial tendency for this binocular vision disorder has not been reported. I describe accommodative spasm occurring in a brother and sister. Both children presented on the same day with complaints of headaches and blurred vision. Treatment included cycloplegia drops and bifocals. Siblings of patients having accommodative spasm should receive a detailed eye exam with emphasis on recognition of accommodative spasm. PMID:20534925

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

PubMed

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

2007-08-15

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

Reading strategies in mild to moderate strabismic amblyopia: an eye movement investigation.

PubMed

Kanonidou, Evgenia; Proudlock, Frank A; Gottlob, Irene

2010-07-01

PURPOSE. To investigate oculomotor strategies in strabismic amblyopia and evaluate abnormalities during monocular and binocular reading. METHODS. Eye movements were recorded with a head-mounted infrared video eye-tracker (250 Hz, <0.01 degrees resolution) in 20 strabismic amblyopes (mean age, 44.9 +/- 10.7 years) and 20 normal control subjects (mean age, 42.8 +/- 10.9 years) while they silently read paragraphs of text. Monocular reading comparisons were made between the amblyopic eye and the nondominant eye of control subjects and the nonamblyopic eye and the dominant eye of the control subjects. Binocular reading between the amblyopic and control subjects was also compared. RESULTS. Mean reading speed, number of progressive and regressive saccades per line, saccadic amplitude (of progressive saccades), and fixation duration were estimated. Inter- and intrasubject statistical comparisons were made. Reading speed was significantly slower in amblyopes than in control subjects during monocular reading with amblyopic (13.094 characters/s vs. 22.188 characters/s; P < 0.0001) and nonamblyopic eyes (16.241 characters/s vs. 22.349 characters/s, P < 0.0001), and binocularly (15.698 characters/s vs. 23.425 characters/s, P < 0.0001). In amblyopes, reading was significantly slower with the amblyopic eye than with the nonamblyopic eye in binocular viewing (P < 0.05). These differences were associated with significantly more regressive saccades and longer fixation durations, but not with changes in saccadic amplitudes. CONCLUSIONS. In strabismic amblyopia, reading is impaired, not only during monocular viewing with the amblyopic eye, but also with the nonamblyopic eye and binocularly, even though normal visual acuity pertains to the latter two conditions. The impaired reading performance is associated with differences in both the saccadic and fixational patterns, most likely as adaptation strategies to abnormal sensory experiences such as crowding and suppression.

A moving observer in a three-dimensional world

PubMed Central

2016-01-01

For many tasks such as retrieving a previously viewed object, an observer must form a representation of the world at one location and use it at another. A world-based three-dimensional reconstruction of the scene built up from visual information would fulfil this requirement, something computer vision now achieves with great speed and accuracy. However, I argue that it is neither easy nor necessary for the brain to do this. I discuss biologically plausible alternatives, including the possibility of avoiding three-dimensional coordinate frames such as ego-centric and world-based representations. For example, the distance, slant and local shape of surfaces dictate the propensity of visual features to move in the image with respect to one another as the observer's perspective changes (through movement or binocular viewing). Such propensities can be stored without the need for three-dimensional reference frames. The problem of representing a stable scene in the face of continual head and eye movements is an appropriate starting place for understanding the goal of three-dimensional vision, more so, I argue, than the case of a static binocular observer. This article is part of the themed issue ‘Vision in our three-dimensional world’. PMID:27269608

Infantile aperiodic alternating nystagmus.

PubMed

Hertle, Richard W; Reznick, Leah; Yang, Dongsheng

2009-01-01

This study identifies the clinical and ocular motility characteristics of the periodic and aperiodic forms of infantile alternating nystagmus (IAPAN) and establishes the range of electrophysiological and clinical characteristics while providing clues to its presence and pathophysiology. Seventy-eight patients with ocular oscillations consistent with IAPAN were reported. Outcome variables were: age, follow-up in months, vision, strabismus, other eye and systemic abnormalities, head position, periodicity, cycle and null period duration, foveation time, waveforms, and cycle symmetry. Age range was 1 to 67 years, 50% had pure periodic and aperiodic forms, 46% had albinism, 26% had binocular acuity of 20/40 or greater, 72% had strabismus, 35% had amblyopia, 31% had other eye disease, 14% had systemic disease, 87% had an anomalous head posture, and 65% had binocular directional asymmetry. The periodic cycle averaged 224 seconds and the aperiodic cycle ranged from 2 to more than 300 seconds. One in three patients with strabismus and nystagmus periodicity had a static head posture. Fifteen percent of the infantile nystagmus syndrome population had either the periodic or aperiodic form. A changing null period is often clinically missed because of long or irregular cycles, decreased acuity, associated strabismus, and either a nonexistent or inconsistent head posture. The changing null period is easier to recognize using eye movement recordings or if the non-preferred eye is occluded and the preferred eye is examined with the head straight and gaze in primary position for at least 5 to 7 minutes. The recognition of this variant has profound treatment implications.

Visually induced self-motion sensation adapts rapidly to left-right reversal of vision

NASA Technical Reports Server (NTRS)

Oman, C. M.; Bock, O. L.

1981-01-01

Three experiments were conducted using 15 adult volunteers with no overt oculomotor or vestibular disorders. In all experiments, left-right vision reversal was achieved using prism goggles, which permitted a binocular field of vision subtending approximately 45 deg horizontally and 28 deg vertically. In all experiments, circularvection (CV) was tested before and immediately after a period of exposure to reversed vision. After one to three hours of active movement while wearing vision-reversing goggles, 10 of 15 (stationary) human subjects viewing a moving stripe display experienced a self-rotation illusion in the same direction as seen stripe motion, rather than in the opposite (normal) direction, demonstrating that the central neural pathways that process visual self-rotation cues can undergo rapid adaptive modification.

Uniocular and binocular fields of rotation measures: Octopus versus Goldmann.

PubMed

Rowe, Fiona J; Hanif, Sahira

2011-06-01

To compare the range of ocular rotations measured by Octopus versus Goldmann perimetry. Forty subjects (20 controls and 20 patients with impaired ocular movements) were prospectively recruited, age range 21-83 years. Range of uniocular rotations was measured in six vectors corresponding to extraocular muscle actions: 0°, 67°, 141°, 180°, 216°, 293°. Fields of binocular single vision were assessed at 30° intervals. Vector measurements were utilised to calculate an area score for the field of uniocular rotations or binocular field of single vision. Two test speeds were used for Octopus testing: 3°/ and 10°/second. Test duration was two thirds quicker for Octopus 10°/second than for 3°/second stimulus speed, and slightly quicker for Goldmann. Mean area for control subjects for uniocular field was 7910.45 degrees(2) for Goldmann, 7032.14 for Octopus 3°/second and 7840.66 for Octopus 10°/second. Mean area for patient subjects of right uniocular field was 8567.21 degrees(2) for Goldmann, 5906.72 for Octopus 3°/second and 8806.44 for Octopus 10°/second. Mean area for left uniocular field was 8137.49 degrees(2) for Goldmann, 8127.9 for Octopus 3°/second and 8950.54 for Octopus 10°/second. Range of measured rotation was significantly larger for Octopus 10°/second speed. Our results suggest that the Octopus perimeter is an acceptable alternative method of assessment for uniocular ductions and binocular field of single vision. Speed of stimulus significantly alters test duration for Octopus perimetry. Comparisons of results from both perimeters show that quantitative measurements differ, although qualitatively the results are similar. Differences per mean vectors were less than 5° (within clinically accepted variances) for both controls and patients when comparing Goldmann to Octopus 10°/second speed. However, differences were almost 10° for the patient group when comparing Goldmann to Octopus 3°/second speed. Thus, speed of stimulus must be considered if wishing to use these perimeters interchangeably.

Ocular morbidity on headache ruled out of systemic causes—A prevalence study carried out at a community based hospital in Nepal

PubMed Central

Marasini, Sanjay; Khadka, Jyoti; Sthapit, Purnima Raj Karnikar; Sharma, Ranjana; Nepal, Bhagvat Prasad

2012-01-01

Purpose The association between ophthalmic anomalies and headache still needs to be investigated largely. We aimed to look for it in the context of a rural community hospital of Nepal. Methods Hundred patients with headache were investigated for ophthalmic anomalies after the probable systemic association was ruled out. All the patients were first examined by general physician, otorhinolaryngologist and psychiatrist. Ocular evaluation consisted of detailed refractive, binocularity assessment and anterior and posterior segment examination. Data were analyzed using t-test, chi-square test, multiple logistic regression, odds ratio as well as frequency and percentages. Results Female above the age of 17 suffered more (p < 0.05). Frontal headache was more common than occipital (p > 0.05). In students and housewives frontal headache was more common (OR 3.467, 0.848–14.174; 95% CI and 1.167, 0.303–4.499; 95% CI). Refractive error was associated with frontal headache (OR, 1.429, 1.130–0.806, 95% CI). On presentation, 88% had visual acuity 6/9 or better. Forty-four percent had refractive error among whom astigmatism was more frequent (63.63%) followed by hyperopia (27.27%) and myopia (9.09%). Known eye problems were significantly associated with refractive error and binocular vision anomalies (p < 0.001). Convergence insufficiency (16.25%) and fusional vergence (11.25%) deficiencies were common among unstable binocularity. Conclusion Ocular anomalies co-exist with headache complains very frequently. Refractive and binocular vision anomalies need to be largely investigated in all headache patients. It is important to get a good headache history so that patients can be referred to the appropriate specialist.

Screening for childhood strabismus by primary care physicians.

PubMed Central

Weinstock, V. M.; Weinstock, D. J.; Kraft, S. P.

1998-01-01

OBJECTIVE: To review the clinical classification of strabismus, to describe the timing and method of strabismus screening examinations, and to discuss the principles of treatment. QUALITY OF EVIDENCE: Current literature (1983 to 1995) was searched via MEDLINE using the MeSH headings strabismus, ocular motility disorders, and amblyopia. Articles were selected based on their date of publication, clinical relevance, and availability. Preference was given to more recent articles, articles with large numbers of subjects, and well-designed cohort studies. Official recommendations from academic groups were analyzed. Descriptions of clinical tests and their illustrations are based on classic texts. MAIN FINDINGS: Primary care physicians should screen all low-risk children. High-risk children (low birth weight, family history of strabismus, congenital ocular abnormality, or systemic conditions with vision-threatening ocular manifestations) should be referred to an ophthalmologist for screening. Screening should be performed in the neonatal period, at 6 months, and at 3 years (Grade A recommendation), as well as at 5 to 6 years (Grade B recommendation). Screening examination includes inspection, examining visual acuity, determining pupillary reactions, checking ocular alignment, testing eye movements, and ophthalmoscopy. CONCLUSIONS: Primary care physicians are essential to early detection of strabismus and amblyopia. Early detection can help minimize visual dysfunction, allow for normal development of binocular vision and depth perception, and prevent psychosocial dysfunction. PMID:9512837

Capture of visual direction in dynamic vergence is reduced with flashed monocular lines.

PubMed

Jaschinski, Wolfgang; Jainta, Stephanie; Schürer, Michael

2006-08-01

The visual direction of a continuously presented monocular object is captured by the visual direction of a closely adjacent binocular object, which questions the reliability of nonius lines for measuring vergence. This was shown by Erkelens, C. J., and van Ee, R. (1997a,b) [Capture of the visual direction: An unexpected phenomenon in binocular vision. Vision Research, 37, 1193-1196; Capture of the visual direction of monocular objects by adjacent binocular objects. Vision Research, 37, 1735-1745] stimulating dynamic vergence by a counter phase oscillation of two square random-dot patterns (one to each eye) that contained a smaller central dot-free gap (of variable width) with a vertical monocular line oscillating in phase with the random-dot pattern of the respective eye; subjects adjusted the motion-amplitude of the line until it was perceived as (nearly) stationary. With a continuously presented monocular line, we replicated capture of visual direction provided the dot-free gap was narrow: the adjusted motion-amplitude of the line was similar as the motion-amplitude of the random-dot pattern, although large vergence errors occurred. However, when we flashed the line for 67 ms at the moments of maximal and minimal disparity of the vergence stimulus, we found that the adjusted motion-amplitude of the line was smaller; thus, the capture effect appeared to be reduced with flashed nonius lines. Accordingly, we found that the objectively measured vergence gain was significantly correlated (r=0.8) with the motion-amplitude of the flashed monocular line when the separation between the line and the fusion contour was at least 32 min arc. In conclusion, if one wishes to estimate the dynamic vergence response with psychophysical methods, effects of capture of visual direction can be reduced by using flashed nonius lines.

Use of botulinum toxin in small-angle heterotropia and decompensating heterophoria: a review of the literature.

PubMed

Ripley, L; Rowe, F J

2007-01-01

Botulinum toxin has been used extensively in strabismus management. However, less is published regarding its use in small-angled manifest deviations or decompensating heterophorias, where an alternative to surgery is required. The aim of this review is to look at the use and effectiveness of botulinum toxin in managing small-angled manifest deviations, both constant and intermittent, and decompensating heterophorias. These types of strabismus can prove difficult to manage, as the angle present is often too small for surgery to be advised, but it may still cause a cosmetic or symptom-producing problem. A search of the English speaking literature was undertaken using Medline facilities as well as a limited manual search of non-Medline journals and transactions. A brief overview is provided for mechanisms of action, complications and dose effects, and diagnostic and therapeutic uses of botulinum toxin. The main reported complications are those of ptosis, induced vertical deviation and subconjunctival haemorrhage. The higher the dose, the greater the risk of complications. In small-angle strabismus, botulinum toxin is reported as particularly useful in cases of acquired and acute-onset esotropia in aiding maintenance of binocular vision. It is useful for additional management of surgically under- or over-corrected esotropia, particularly for those with potential for binocular vision. Less effect is reported in primary exotropia versus primary esotropia. It is the management of choice for consecutive exotropia, particularly when patients have had previous multiple surgery and where there is a risk for postoperative diplopia. Botulinum toxin has a specific role in decompensated heterophoria, allowing the visual axes a chance to 'lock on' and subsequently maintain binocular vision. Successful outcomes are reported after 1-2 injections only but the results are best in cases of heterophoria with little near-distance angle disparity.

Relationship between binocular vision, visual acuity, and fine motor skills.

PubMed

O'Connor, Anna R; Birch, Eileen E; Anderson, Susan; Draper, Hayley

2010-12-01

The aims of this study were to analyze the relationship between the performance on fine motor skills tasks and peripheral and bifoveal sensory fusion, phasic and tonic motor fusion, the level of visual acuity (VA) in the poorer seeing eye, and the interocular VA difference. Subjects aged 12 to 28 years with a range of levels of binocular vision and VA performed three tasks: Purdue pegboard (number of pegs placed in 30 s), bead threading task (with two sizes of bead to increase the difficulty, time taken to thread a fixed number of beads), and a water pouring task (accuracy and time to pour a fixed quantity into five glass cylinders). Ophthalmic measures included peripheral (Worth 4 dot) and bifoveal (4 prism diopter) sensory fusion, phasic (prism bar) and tonic (Risley rotary prism) motor fusion ranges, and monocular VA. One hundred twenty-one subjects with a mean age of 18.8 years were tested; 18.2% had a manifest strabismus. Performance on fine motor skills tasks was significantly better in subjects with sensory and motor fusion compared with those without for most tasks, with significant differences between those with and without all measures of fusion on the pegboard and bead task. Both the acuity in the poorer seeing eye (highest r value of all motor tasks = 0.43) and the interocular acuity difference were statistically significantly related to performance on the motor skill tasks. Both sensory and motor fusion and good VA in both eyes are of benefit in the performance of fine motor skills tasks, with the presence of some binocular vision being beneficial compared with no fusion on certain sensorimotor tasks. This evidence supports the need to maximize fusion and VA outcomes.

Contrast normalization in colour vision: the effect of luminance contrast on colour contrast detection

PubMed Central

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

2014-01-01

While contrast normalization is well known to occur in luminance vision between overlaid achromatic contrasts, and in colour vision between overlaid colour contrasts, it is unknown whether it transfers between colour and luminance contrast. Here we investigate whether contrast detection in colour vision can be normalized by achromatic contrast, or whether this is a selective process driven only by colour contrast. We use a method of cross-orientation masking, in which colour detection is masked by cross-oriented achromatic contrast, over a range of spatio-temporal frequencies (0.375–1.5 cpd, 2–8 Hz). We find that there is virtually no cross-masking of colour by achromatic contrast under monocular or binocular conditions for any of the spatio-temporal frequencies tested, although we find significant facilitation at low spatio-temporal conditions (0.375 cpd, 2 Hz). These results indicate that the process of contrast nornalization is colour selective and independent of achromatic contrast, and imply segregated chromatic signals in early visual processing. Under dichoptic conditions, however, we find a strikingly different result with significant masking of colour by achromatic contrast. This indicates that the dichoptic site of suppression is unselective, responding similarly to colour and luminance contrast, and suggests that dichoptic suppression has a different origin from monocular or binocular suppression. PMID:25491564

21 CFR 886.1870 - Stereoscope.

Code of Federal Regulations, 2011 CFR

2011-04-01

...-dimensional appearance of solidity and relief. It is intended to measure the angle of strabismus (eye muscle deviation), evaluate binocular vision (usage of both eyes to see), and guide a patient's corrective exercises of eye muscles. (b) Classification. Class I (general controls). The AC-powered device and the...

21 CFR 886.1870 - Stereoscope.

Code of Federal Regulations, 2010 CFR

2010-04-01

...-dimensional appearance of solidity and relief. It is intended to measure the angle of strabismus (eye muscle deviation), evaluate binocular vision (usage of both eyes to see), and guide a patient's corrective exercises of eye muscles. (b) Classification. Class I (general controls). The AC-powered device and the...

Incidence of vertical phoria on postural control during binocular vision: what perspective for prevention to nonspecific chronic pain management?

PubMed

Matheron, Eric; Kapoula, Zoï

2015-01-01

Vertical heterophoria (VH) is the latent vertical misalignment of the eyes when the retinal images are dissociated, vertical orthophoria (VO) when there is no misalignment. Studies on postural control, during binocular vision in upright stance, reported that healthy subjects with small VH vs. VO are less stable, but the experimental cancellation of VH with an appropriate prism improves postural stability. The same behavior was recorded in nonspecific chronic back pain subjects, all with VH. It was hypothesized that, without refraction problems, VH indicates a perturbation of the somaesthetic cues required in the sensorimotor loops involved in postural control and the capacity of the CNS to optimally integrate these cues, suggesting prevention possibilities. Sensorimotor conflict can induce pain and modify sensory perception in some healthy subjects; some nonspecific pain or chronic pain could result from such prolonged conflict in which VH could be a sign, with new theoretical and clinical implications.

Composition of a Vision Screen for Servicemembers With Traumatic Brain Injury: Consensus Using a Modified Nominal Group Technique

PubMed Central

Finkelstein, Marsha; Llanos, Imelda; Scheiman, Mitchell; Wagener, Sharon Gowdy

2014-01-01

Vision impairment is common in the first year after traumatic brain injury (TBI), including among service members whose brain injuries occurred during deployment in Iraq and Afghanistan. Occupational therapy practitioners provide routine vision screening to inform treatment planning and referral to vision specialists, but existing methods are lacking because many tests were developed for children and do not screen for vision dysfunction typical of TBI. An expert panel was charged with specifying the composition of a vision screening protocol for servicemembers with TBI. A modified nominal group technique fostered discussion and objective determinations of consensus. After considering 29 vision tests, the panel recommended a nine-test vision screening that examines functional performance, self-reported problems, far–near acuity, reading, accommodation, convergence, eye alignment and binocular vision, saccades, pursuits, and visual fields. Research is needed to develop reliable, valid, and clinically feasible vision screening protocols to identify TBI-related vision disorders in adults. PMID:25005505

Visual function in anterior ischemic optic neuropathy: effect of Vision Restoration Therapy--a pilot study.

PubMed

Jung, Cecilia S; Bruce, Beau; Newman, Nancy J; Biousse, Valérie

2008-05-15

To evaluate the effects of Vision Restoration Therapy (VRT) on the visual function of patients with anterior ischemic optic neuropathy. Randomized controlled double-blind pilot trial. 10 patients with stable anterior ischemic optic neuropathy (AION). All patients were evaluated before VRT and after 3 and 6 months of treatment by Early Treatment Diabetic Retinopathy Study (ETDRS) visual acuity, contrast sensitivity, reading speed, 24-2 SITA-standard Humphrey visual field (HVF), High Resolution Perimetry (HRP) (perimetry obtained during VRT), and vision-based quality of life questionnaire. Patients were randomized between two VRT strategies (5 in each group): I) VRT in which stimulation was performed in the seeing VF of the affected eye ("seeing field-VRT"); II) VRT in which stimulation was performed along the area of central fixation and in the ARV (areas of residual vision) of the affected eye ("ARV-VRT"). The results of the HRP, HVF, and clinical assessment of visual function were compared for each patient and between the two groups at each evaluation. Visual acuity qualitatively improved in the ARV-VRT group, however the change was not statistically significant (p=0.28). Binocular reading speed significantly improved in the ARV-VRT group (p=0.03). HVF foveal sensitivity increased mildly in both groups (p=0.059). HRP analysis showed a similar increase in stimulus accuracy in both groups (mean improvement of about 15%). All patients reported functional improvement after VRT. Despite a small sample, the study showed a trend toward improvement of visual function in the ARV-VRT group. Improvement of HRP in both groups may reflect diffusely increased visual attention (neuronal activation), or improvement of an underlying sub-clinical abnormality in the "seeing" visual field of patients with optic neuropathies.

[Dichoptic training for amblyopia].

PubMed

Bach, M

2016-04-01

Dichoptic training is a promising new therapeutic approach to amblyopia, which employs simultaneous and separate stimulation of both eyes (thus dichoptic). The contrast for the good eye is reduced thus aiming at a balance with the amblyopic eye. In contrast to monocular patching, binocular vision is trained by video game tasks that can only be solved binocularly. To date the average gain in visual acuity achieved in currently available studies is only 0.20 ± 0.07 logMAR and is not significantly better than competing treatment options. This article explains the basic approach of dichoptic training, summarizes pertinent studies, names unsolved problems and closes with a personal critical assessment.

Counter sniper: a localization system based on dual thermal imager

NASA Astrophysics Data System (ADS)

He, Yuqing; Liu, Feihu; Wu, Zheng; Jin, Weiqi; Du, Benfang

2010-11-01

Sniper tactics is widely used in modern warfare, which puts forward the urgent requirement of counter sniper detection devices. This paper proposed the anti-sniper detection system based on a dual-thermal imaging system. Combining the infrared characteristics of the muzzle flash and bullet trajectory of binocular infrared images obtained by the dual-infrared imaging system, the exact location of the sniper was analyzed and calculated. This paper mainly focuses on the system design method, which includes the structure and parameter selection. It also analyzes the exact location calculation method based on the binocular stereo vision and image analysis, and give the fusion result as the sniper's position.

The effect of Bangerter filters on binocular function in observers with amblyopia.

PubMed

Chen, Zidong; Li, Jinrong; Thompson, Benjamin; Deng, Daming; Yuan, Junpeng; Chan, Lily; Hess, Robert F; Yu, Minbin

2014-10-28

We assessed whether partial occlusion of the nonamblyopic eye with Bangerter filters can immediately reduce suppression and promote binocular summation of contrast in observers with amblyopia. In Experiment 1, suppression was measured for 22 observers (mean age, 20 years; range, 14-32 years; 10 females) with strabismic or anisometropic amblyopia and 10 controls using our previously established "balance point" protocol. Measurements were made at baseline and with 0.6-, 0.4-, and 0.2-strength Bangerter filters placed over the nonamblyopic/dominant eye. In Experiment 2, psychophysical measurements of contrast sensitivity were made under binocular and monocular viewing conditions for 25 observers with anisometropic amblyopia (mean age, 17 years; range, 11-28 years; 14 females) and 22 controls (mean age, 24 years; range, 22-27; 12 female). Measurements were made at baseline, and with 0.4- and 0.2-strength Bangerter filters placed over the nonamblyopic/dominant eye. Binocular summation ratios (BSRs) were calculated at baseline and with Bangerter filters in place. Experiment 1: Bangerter filters reduced suppression in observers with amblyopia and induced suppression in controls (P = 0.025). The 0.2-strength filter eliminated suppression in observers with amblyopia and this was not a visual acuity effect. Experiment 2: Bangerter filters were able to induce normal levels of binocular contrast summation in the group of observers with anisometropic amblyopia for a stimulus with a spatial frequency of 3 cycles per degree (cpd, P = 0.006). The filters reduced binocular summation in controls. Bangerter filters can immediately reduce suppression and promote binocular summation for mid/low spatial frequencies in observers with amblyopia. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

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

PubMed Central

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

2007-01-01

Amblyopia is a developmental visual disorder associated with loss of monocular acuity and sensitivity as well as profound alterations in binocular integration. Abnormal connections in visual cortex are known to underlie this loss, but the extent to which these abnormalities are regionally or retinotopically specific has not been fully determined. This functional magnetic resonance imaging (fMRI) study compared the retinotopic maps in visual cortex produced by each individual eye in 19 adults (7 esotropic strabismics, 6 anisometropes and 6 controls). In our standard viewing condition, the non-tested eye viewed a dichoptic homogeneous mid-level grey stimulus, thereby permitting some degree of binocular interaction. Regions-of-interest analysis was performed for extrafoveal V1, extrafoveal V2 and the foveal representation at the occipital pole. In general, the blood oxygenation level-dependent (BOLD) signal was reduced for the amblyopic eye. At the occipital pole, population receptive fields were shifted to represent more parafoveal locations for the amblyopic eye, compared with the fellow eye, in some subjects. Interestingly, occluding the fellow eye caused an expanded foveal representation for the amblyopic eye in one early–onset strabismic subject with binocular suppression, indicating real-time cortical remapping. In addition, a few subjects actually showed increased activity in parietal and temporal cortex when viewing with the amblyopic eye. We conclude that, even in a heterogeneous population, abnormal early visual experience commonly leads to regionally specific cortical adaptations. PMID:17627994

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

PubMed

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

2013-01-01

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

Sparse Coding Can Predict Primary Visual Cortex Receptive Field Changes Induced by Abnormal Visual Input

PubMed Central

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

2013-01-01

Receptive fields acquired through unsupervised learning of sparse representations of natural scenes have similar properties to primary visual cortex (V1) simple cell receptive fields. However, what drives in vivo development of receptive fields remains controversial. The strongest evidence for the importance of sensory experience in visual development comes from receptive field changes in animals reared with abnormal visual input. However, most sparse coding accounts have considered only normal visual input and the development of monocular receptive fields. Here, we applied three sparse coding models to binocular receptive field development across six abnormal rearing conditions. In every condition, the changes in receptive field properties previously observed experimentally were matched to a similar and highly faithful degree by all the models, suggesting that early sensory development can indeed be understood in terms of an impetus towards sparsity. As previously predicted in the literature, we found that asymmetries in inter-ocular correlation across orientations lead to orientation-specific binocular receptive fields. Finally we used our models to design a novel stimulus that, if present during rearing, is predicted by the sparsity principle to lead robustly to radically abnormal receptive fields. PMID:23675290

Perceptual Learning as a potential treatment for amblyopia: a mini-review

PubMed Central

Levi, Dennis M.; Li, Roger W.

2009-01-01

Amblyopia is a developmental abnormality that results from physiological alterations in the visual cortex and impairs form vision. It is a consequence of abnormal binocular visual experience during the “sensitive period” early in life. While amblyopia can often be reversed when treated early, conventional treatment is generally not undertaken in older children and adults. A number of studies over the last twelve years or so suggest that Perceptual Learning (PL) may provide an important new method for treating amblyopia. The aim of this mini-review is to provide a critical review and “meta-analysis” of perceptual learning in adults and children with amblyopia, with a view to extracting principles that might make PL more effective and efficient. Specifically we evaluate: What factors influence the outcome of perceptual learning?Specificity and generalization – two sides of the coin.Do the improvements last?How does PL improve visual function?Should PL be part of the treatment armamentarium? A review of the extant studies makes it clear that practicing a visual task results in a long-lasting improvement in performance in an amblyopic eye. The improvement is generally strongest for the trained eye, task, stimulus and orientation, but appears to have a broader spatial frequency bandwidth than in normal vision. Importantly, practicing on a variety of different tasks and stimuli seems to transfer to improved visual acuity. Perceptual learning operates via a reduction of internal neural noise and/or through more efficient use of the stimulus information by retuning the weighting of the information. The success of PL raises the question of whether it should become a standard part of the armamentarium for the clinical treatment of amblyopia, and suggests several important principles for effective perceptual learning in amblyopia. PMID:19250947

An evaluation of the lag of accommodation using photorefraction.

PubMed

Seidemann, Anne; Schaeffel, Frank

2003-02-01

The lag of accommodation which occurs in most human subjects during reading has been proposed to explain the association between reading and myopia. However, the measured lags are variable among different published studies and current knowledge on its magnitude rests largely on measurements with the Canon R-1 autorefractor. Therefore, we have measured it with another technique, eccentric infrared photorefraction (the PowerRefractor), and studied how it can be modified. Particular care was taken to ensure correct calibration of the instrument. Ten young adult subjects were refracted both in the fixation axis of the right eye and from the midline between both eyes, while they read text both monocularly and binocularly at 1.5, 2, 3, 4 and 5 D distance ("group 1"). A second group of 10 subjects ("group 2"), measured from the midline between both eyes, was studied to analyze the effects of binocular vs monocular vision, addition of +1 or +2 D lenses, and of letter size. Spherical equivalents (SE) were analyzed in all cases. The lag of accommodation was variable among subjects (standard deviations among groups and viewing distances ranging from 0.18 to 1.07 D) but was significant when the measurements were done in the fixation axis (0.35 D at 3 D target distance to 0.60 D at 5 D with binocular vision; p<0.01 or better all cases). Refracting from the midline between both eyes tended to underestimate the lag of accommodation although this was significant only at 5 D (ANOVA: p<0.0001, post hoc t-test: p<0.05). There was a small improvement in accommodation precision with binocular compared to monocular viewing but significance was reached only for the 5 D reading target (group 1--lags for a 3/4/5 D target: 0.35 vs 0.41 D/0.48 vs 0.47 D/0.60 vs 0.66 D, ANOVA: p<0.0001, post hoc t-test: p<0.05; group 2--0.29 vs 0.12 D, 0.33 vs 0.16 D, 0.23 vs -0.31 D, ANOVA: p<0.0001, post hoc t-test: p<0.05). Adjusting the letter height for constant angular subtense (0.2 deg) induced scarcely more accommodation than keeping letter size constantly at 3.5 mm (ANOVA: p<0.0001, post hoc t-test: n.s.). Positive trial lenses reduced the lag of accommodation under monocular viewing conditions and even reversed it with binocular vision. After consideration of possible sources of measurement error, the lag of accommodation measured with photorefraction at 3 D (0.41 D SE monocular and 0.35 D SE binocular) was in the range of published values from the Canon R-1 autorefractor. With the measured lag, simulations of the retinal images for a diffraction limited eye suggest surprisingly poor letter contrast on the retina.

Obstacles encountered in the development of the low vision enhancement system.

PubMed

Massof, R W; Rickman, D L

1992-01-01

The Johns Hopkins Wilmer Eye Institute and the NASA Stennis Space Center are collaborating on the development of a new high technology low vision aid called the Low Vision Enhancement System (LVES). The LVES consists of a binocular head-mounted video display system, video cameras mounted on the head-mounted display, and real-time video image processing in a system package that is battery powered and portable. Through a phased development approach, several generations of the LVES can be made available to the patient in a timely fashion. This paper describes the LVES project with major emphasis on technical problems encountered or anticipated during the development process.

Binocular contrast-gain control for natural scenes: Image structure and phase alignment.

PubMed

Huang, Pi-Chun; Dai, Yu-Ming

2018-05-01

In the context of natural scenes, we applied the pattern-masking paradigm to investigate how image structure and phase alignment affect contrast-gain control in binocular vision. We measured the discrimination thresholds of bandpass-filtered natural-scene images (targets) under various types of pedestals. Our first experiment had four pedestal types: bandpass-filtered pedestals, unfiltered pedestals, notch-filtered pedestals (which enabled removal of the spatial frequency), and misaligned pedestals (which involved rotation of unfiltered pedestals). Our second experiment featured six types of pedestals: bandpass-filtered, unfiltered, and notch-filtered pedestals, and the corresponding phase-scrambled pedestals. The thresholds were compared for monocular, binocular, and dichoptic viewing configurations. The bandpass-filtered pedestal and unfiltered pedestals showed classic dipper shapes; the dipper shapes of the notch-filtered, misaligned, and phase-scrambled pedestals were weak. We adopted a two-stage binocular contrast-gain control model to describe our results. We deduced that the phase-alignment information influenced the contrast-gain control mechanism before the binocular summation stage and that the phase-alignment information and structural misalignment information caused relatively strong divisive inhibition in the monocular and interocular suppression stages. When the pedestals were phase-scrambled, the elimination of the interocular suppression processing was the most convincing explanation of the results. Thus, our results indicated that both phase-alignment information and similar image structures cause strong interocular suppression. Copyright © 2018 Elsevier Ltd. All rights reserved.

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

PubMed Central

Martin, Graham R.

2014-01-01

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

Object Rotation Effects on the Timing of a Hitting Action

ERIC Educational Resources Information Center

Scott, Mark A.; van der Kamp, John; Savelsbergh, Geert J. P.; Oudejans, Raoul R. D.; Davids, Keith

2004-01-01

In this article, the authors investigated how perturbing optical information affects the guidance of an unfolding hitting action. Using monocular and binocular vision, six participants were required to hit a rectangular foam object, released from two different heights, under four different approach conditions, two with object rotation (to perturb…

Sensory Sensitivities and Discriminations and their Roles in Aviation

DTIC Science & Technology

1991-10-31

asymmetry. Neurology, in press. 5. Zihl JD, Von Cramon D & Mai N (1983) Selective disturbance of movement vision after bilateral brain damage. Brain...1970) Electrophysiological correlate of binocular depth perception in man. Nature 255, 92-4. 1971 16. Regan D & Sperling HG (1971) A method of evoking

Precise positioning method for multi-process connecting based on binocular vision

NASA Astrophysics Data System (ADS)

Liu, Wei; Ding, Lichao; Zhao, Kai; Li, Xiao; Wang, Ling; Jia, Zhenyuan

2016-01-01

With the rapid development of aviation and aerospace, the demand for metal coating parts such as antenna reflector, eddy-current sensor and signal transmitter, etc. is more and more urgent. Such parts with varied feature dimensions, complex three-dimensional structures, and high geometric accuracy are generally fabricated by the combination of different manufacturing technology. However, it is difficult to ensure the machining precision because of the connection error between different processing methods. Therefore, a precise positioning method is proposed based on binocular micro stereo vision in this paper. Firstly, a novel and efficient camera calibration method for stereoscopic microscope is presented to solve the problems of narrow view field, small depth of focus and too many nonlinear distortions. Secondly, the extraction algorithms for law curve and free curve are given, and the spatial position relationship between the micro vision system and the machining system is determined accurately. Thirdly, a precise positioning system based on micro stereovision is set up and then embedded in a CNC machining experiment platform. Finally, the verification experiment of the positioning accuracy is conducted and the experimental results indicated that the average errors of the proposed method in the X and Y directions are 2.250 μm and 1.777 μm, respectively.

Binocular Therapy for Childhood Amblyopia Improves Vision Without Breaking Interocular Suppression.

PubMed

Bossi, Manuela; Tailor, Vijay K; Anderson, Elaine J; Bex, Peter J; Greenwood, John A; Dahlmann-Noor, Annegret; Dakin, Steven C

2017-06-01

Amblyopia is a common developmental visual impairment characterized by a substantial difference in acuity between the two eyes. Current monocular treatments, which promote use of the affected eye by occluding or blurring the fellow eye, improve acuity, but are hindered by poor compliance. Recently developed binocular treatments can produce rapid gains in visual function, thought to be as a result of reduced interocular suppression. We set out to develop an effective home-based binocular treatment system for amblyopia that would engage high levels of compliance but that would also allow us to assess the role of suppression in children's response to binocular treatment. Balanced binocular viewing therapy (BBV) involves daily viewing of dichoptic movies (with "visibility" matched across the two eyes) and gameplay (to monitor compliance and suppression). Twenty-two children (3-11 years) with anisometropic (n = 7; group 1) and strabismic or combined mechanism amblyopia (group 2; n = 6 and 9, respectively) completed the study. Groups 1 and 2 were treated for a maximum of 8 or 24 weeks, respectively. The treatment elicited high levels of compliance (on average, 89.4% ± 24.2% of daily dose in 68.23% ± 12.2% of days on treatment) and led to a mean improvement in acuity of 0.27 logMAR (SD 0.22) for the amblyopic eye. Importantly, acuity gains were not correlated with a reduction in suppression. BBV is a binocular treatment for amblyopia that can be self-administered at home (with remote monitoring), producing rapid and substantial benefits that cannot be solely mediated by a reduction in interocular suppression.

Fine Motor Skills of Children With Amblyopia Improve Following Binocular Treatment.

PubMed

Webber, Ann L; Wood, Joanne M; Thompson, Benjamin

2016-09-01

The purpose of this study was to determine whether reduced fine motor skills in children with amblyopia improve after binocular treatment and whether improvements are sustained once treatment has ceased. Fine motor skills (FMS [Bruininks-Oseretsky Test of Motor Proficiency]), visual acuity (VA [Early Treatment of Diabetic Retinopathy Study chart]) and level of binocular function (BF [Randot preschool stereoacuity and Worth 4 Dot]) were measured in children with amblyopia (n = 20; age: 8.5 ± 1.3 years; 11 anisometropic; 5 strabismic; 4 mixed) and in a group of visually normal children (n = 10; age: 9.63 ± 1.6 years). Eighteen children with amblyopia subsequently completed 5 weeks of binocular treatment provided by home-based dichoptic iPod game play. FMS, VA, and BF were retested at the end of treatment and 12 weeks after treatment cessation. All visually normal children also completed FMS measurements at baseline and 5 weeks later to assess test-retest variability of the FMS scores. Prior to treatment, FMS scores in children with amblyopia were poorer than those in children with normal vision (P < 0.05). In the children with amblyopia, binocular treatment significantly improved FMS scores (P < 0.05). Better baseline amblyopic eye VA and BF were associated with greater improvements in FMS score. Improvements were still evident at 12 weeks post treatment. In the visually normal children, FMS scores remained stable across the two test sessions. Binocular treatment provided by dichoptic iPod game play improved FMS performance in children with amblyopia, particularly in those with less severe amblyopia. Improvements were maintained at 3 months following cessation of treatment.

Vector disparity sensor with vergence control for active vision systems.

PubMed

Barranco, Francisco; Diaz, Javier; Gibaldi, Agostino; Sabatini, Silvio P; Ros, Eduardo

2012-01-01

This paper presents an architecture for computing vector disparity for active vision systems as used on robotics applications. The control of the vergence angle of a binocular system allows us to efficiently explore dynamic environments, but requires a generalization of the disparity computation with respect to a static camera setup, where the disparity is strictly 1-D after the image rectification. The interaction between vision and motor control allows us to develop an active sensor that achieves high accuracy of the disparity computation around the fixation point, and fast reaction time for the vergence control. In this contribution, we address the development of a real-time architecture for vector disparity computation using an FPGA device. We implement the disparity unit and the control module for vergence, version, and tilt to determine the fixation point. In addition, two on-chip different alternatives for the vector disparity engines are discussed based on the luminance (gradient-based) and phase information of the binocular images. The multiscale versions of these engines are able to estimate the vector disparity up to 32 fps on VGA resolution images with very good accuracy as shown using benchmark sequences with known ground-truth. The performances in terms of frame-rate, resource utilization, and accuracy of the presented approaches are discussed. On the basis of these results, our study indicates that the gradient-based approach leads to the best trade-off choice for the integration with the active vision system.

Vector Disparity Sensor with Vergence Control for Active Vision Systems

PubMed Central

Barranco, Francisco; Diaz, Javier; Gibaldi, Agostino; Sabatini, Silvio P.; Ros, Eduardo

2012-01-01

This paper presents an architecture for computing vector disparity for active vision systems as used on robotics applications. The control of the vergence angle of a binocular system allows us to efficiently explore dynamic environments, but requires a generalization of the disparity computation with respect to a static camera setup, where the disparity is strictly 1-D after the image rectification. The interaction between vision and motor control allows us to develop an active sensor that achieves high accuracy of the disparity computation around the fixation point, and fast reaction time for the vergence control. In this contribution, we address the development of a real-time architecture for vector disparity computation using an FPGA device. We implement the disparity unit and the control module for vergence, version, and tilt to determine the fixation point. In addition, two on-chip different alternatives for the vector disparity engines are discussed based on the luminance (gradient-based) and phase information of the binocular images. The multiscale versions of these engines are able to estimate the vector disparity up to 32 fps on VGA resolution images with very good accuracy as shown using benchmark sequences with known ground-truth. The performances in terms of frame-rate, resource utilization, and accuracy of the presented approaches are discussed. On the basis of these results, our study indicates that the gradient-based approach leads to the best trade-off choice for the integration with the active vision system. PMID:22438737

A methodology for coupling a visual enhancement device to human visual attention

NASA Astrophysics Data System (ADS)

Todorovic, Aleksandar; Black, John A., Jr.; Panchanathan, Sethuraman

2009-02-01

The Human Variation Model views disability as simply "an extension of the natural physical, social, and cultural variability of mankind." Given this human variation, it can be difficult to distinguish between a prosthetic device such as a pair of glasses (which extends limited visual abilities into the "normal" range) and a visual enhancement device such as a pair of binoculars (which extends visual abilities beyond the "normal" range). Indeed, there is no inherent reason why the design of visual prosthetic devices should be limited to just providing "normal" vision. One obvious enhancement to human vision would be the ability to visually "zoom" in on objects that are of particular interest to the viewer. Indeed, it could be argued that humans already have a limited zoom capability, which is provided by their highresolution foveal vision. However, humans still find additional zooming useful, as evidenced by their purchases of binoculars equipped with mechanized zoom features. The fact that these zoom features are manually controlled raises two questions: (1) Could a visual enhancement device be developed to monitor attention and control visual zoom automatically? (2) If such a device were developed, would its use be experienced by users as a simple extension of their natural vision? This paper details the results of work with two research platforms called the Remote Visual Explorer (ReVEx) and the Interactive Visual Explorer (InVEx) that were developed specifically to answer these two questions.

Age- and Stereovision-Dependent Eye–Hand Coordination Deficits in Children With Amblyopia and Abnormal Binocularity

PubMed Central

Grant, Simon; Suttle, Catherine; Melmoth, Dean R.; Conway, Miriam L.; Sloper, John J.

2014-01-01

Purpose. To examine factors contributing to eye–hand coordination deficits in children with amblyopia and impaired stereovision. Methods. Participants were 55 anisometropic or strabismic children aged 5.0 to 9.25 years with different degrees of amblyopia and abnormal binocularity, along with 28 age-matched visually-normal controls. Pilot data were obtained from four additional patients studied longitudinally at different treatment stages. Movements of the preferred hand were recorded using a 3D motion-capture system while subjects reached-to-precision grasp objects (two sizes, three locations) under binocular, dominant eye, and amblyopic/nonsighting eye conditions. Kinematic and “error” performance measures were quantified and compared by viewing condition and subject group using ANOVA, stepwise regression, and correlation analyses. Results. Movements of the younger amblyopes (age 5–6 years; n = 30) were much slower, particularly in the final approach to the objects, and contained more spatial errors in reaching (∼×1.25–1.75) and grasping (∼×1.75–2.25) under all three views (P < 0.05) than their age-matched controls (n = 13). Amblyopia severity was the main contributor to their slower movements with absent stereovision a secondary factor and the unique determinant of their increased error-rates. Older amblyopes (age 7–9 years; n = 25) spent longer contacting the objects before lifting them (P = 0.015) compared with their matched controls (n = 15), with absence of stereovision still solely related to increases in reach and grasp errors, although these occurred less frequently than in younger patients. Pilot prospective data supported these findings by showing positive treatment-related associations between improved stereovision and reach-to-grasp performance. Conclusions. Strategies that children with amblyopia and abnormal binocularity use for reach-to-precision grasping change with age, from emphasis on visual feedback during the “in-flight” approach at ages 5 to 6 years to more reliance on tactile/kinesthetic feedback from object contact at ages 7 to 9 years. However, recovery of binocularity confers increasing benefits for eye–hand coordination speed and accuracy with age, and is a better predictor of these fundamental performance measures than the degree of visual acuity loss. PMID:25097239

What Drives Bird Vision? Bill Control and Predator Detection Overshadow Flight.

PubMed

Martin, Graham R

2017-01-01

Although flight is regarded as a key behavior of birds this review argues that the perceptual demands for its control are met within constraints set by the perceptual demands of two other key tasks: the control of bill (or feet) position, and the detection of food items/predators. Control of bill position, or of the feet when used in foraging, and timing of their arrival at a target, are based upon information derived from the optic flow-field in the binocular region that encompasses the bill. Flow-fields use information extracted from close to the bird using vision of relatively low spatial resolution. The detection of food items and predators is based upon information detected at a greater distance and depends upon regions in the retina with relatively high spatial resolution. The tasks of detecting predators and of placing the bill (or feet) accurately, make contradictory demands upon vision and these have resulted in trade-offs in the form of visual fields and in the topography of retinal regions in which spatial resolution is enhanced, indicated by foveas, areas, and high ganglion cell densities. The informational function of binocular vision in birds does not lie in binocularity per se (i.e., two eyes receiving slightly different information simultaneously about the same objects) but in the contralateral projection of the visual field of each eye. This ensures that each eye receives information from a symmetrically expanding optic flow-field centered close to the direction of the bill, and from this the crucial information of direction of travel and time-to-contact can be extracted, almost instantaneously. Interspecific comparisons of visual fields between closely related species have shown that small differences in foraging techniques can give rise to different perceptual challenges and these have resulted in differences in visual fields even within the same genus. This suggests that vision is subject to continuing and relatively rapid natural selection based upon individual differences in the structure of the optical system, retinal topography, and eye position in the skull. From a sensory ecology perspective a bird is best characterized as "a bill guided by an eye" and that control of flight is achieved within constraints on visual capacity dictated primarily by the demands of foraging and bill control.

What Drives Bird Vision? Bill Control and Predator Detection Overshadow Flight

PubMed Central

Martin, Graham R.

2017-01-01

Although flight is regarded as a key behavior of birds this review argues that the perceptual demands for its control are met within constraints set by the perceptual demands of two other key tasks: the control of bill (or feet) position, and the detection of food items/predators. Control of bill position, or of the feet when used in foraging, and timing of their arrival at a target, are based upon information derived from the optic flow-field in the binocular region that encompasses the bill. Flow-fields use information extracted from close to the bird using vision of relatively low spatial resolution. The detection of food items and predators is based upon information detected at a greater distance and depends upon regions in the retina with relatively high spatial resolution. The tasks of detecting predators and of placing the bill (or feet) accurately, make contradictory demands upon vision and these have resulted in trade-offs in the form of visual fields and in the topography of retinal regions in which spatial resolution is enhanced, indicated by foveas, areas, and high ganglion cell densities. The informational function of binocular vision in birds does not lie in binocularity per se (i.e., two eyes receiving slightly different information simultaneously about the same objects) but in the contralateral projection of the visual field of each eye. This ensures that each eye receives information from a symmetrically expanding optic flow-field centered close to the direction of the bill, and from this the crucial information of direction of travel and time-to-contact can be extracted, almost instantaneously. Interspecific comparisons of visual fields between closely related species have shown that small differences in foraging techniques can give rise to different perceptual challenges and these have resulted in differences in visual fields even within the same genus. This suggests that vision is subject to continuing and relatively rapid natural selection based upon individual differences in the structure of the optical system, retinal topography, and eye position in the skull. From a sensory ecology perspective a bird is best characterized as “a bill guided by an eye” and that control of flight is achieved within constraints on visual capacity dictated primarily by the demands of foraging and bill control. PMID:29163020

Peripheral Prism Glasses: Effects of Dominance, Suppression and Background

PubMed Central

Ross, Nicole C.; Bowers, Alex R.; Optom, M.C.; Peli, Eli

2012-01-01

Purpose Unilateral peripheral prisms for homonymous hemianopia (HH) place different images on corresponding peripheral retinal points, a rivalrous situation in which local suppression of the prism image could occur and thus limit device functionality. Detection with peripheral prisms has primarily been evaluated using conventional perimetry where binocular rivalry is unlikely to occur. We quantified detection over more visually complex backgrounds and examined the effects of ocular dominance. Methods Detection rates of 8 participants with HH or quadranopia and normal binocularity wearing unilateral peripheral prism glasses were determined for static perimetry targets briefly presented in the prism expansion area (in the blind hemifield) and the seeing hemifield, under monocular and binocular viewing, over uniform gray and more complex patterned backgrounds. Results Participants with normal binocularity had mixed sensory ocular dominance, demonstrated no difference in detection rates when prisms were fitted on the side of the HH or the opposite side (p>0.2), and had detection rates in the expansion area that were not different for monocular and binocular viewing over both backgrounds (p>0.4). However, two participants with abnormal binocularity and strong ocular dominance demonstrated reduced detection in the expansion area when prisms were fitted in front of the non-dominant eye. Conclusions We found little evidence of local suppression of the peripheral prism image for HH patients with normal binocularity. However, in cases of strong ocular dominance, consideration should be given to fitting prisms before the dominant eye. Although these results are promising, further testing in more realistic conditions including image motion is needed. PMID:22885783

A comparison of the sensitivity of EQ-5D, SF-6D and TTO utility values to changes in vision and perceived visual function in patients with primary open-angle glaucoma

PubMed Central

2012-01-01

Background Economic viability of treatments for primary open-angle glaucoma (POAG) should be assessed objectively to prioritise health care interventions. This study aims to identify the methods for eliciting utility values (UVs) most sensitive to differences in visual field and visual functioning in patients with POAG. As a secondary objective, the dimensions of generic health-related and vision-related quality of life most affected by progressive vision loss will be identified. Methods A total of 132 POAG patients were recruited. Three sets of utility values (EuroQoL EQ-5D, Short Form SF-6D, Time Trade Off) and a measure of perceived visual functioning from the National Eye Institute Visual Function Questionnaire (VFQ-25) were elicited during face-to-face interviews. The sensitivity of UVs to differences in the binocular visual field, visual acuity and visual functioning measures was analysed using non-parametric statistical methods. Results Median utilities were similar across Integrated Visual Field score quartiles for EQ-5D (P = 0.08) whereas SF-6D and Time-Trade-Off UVs significantly decreased (p = 0.01 and p = 0.001, respectively). The VFQ-25 score varied across Integrated Visual Field and binocular visual acuity groups and was associated with all three UVs (P ≤ 0.001); most of its vision-specific sub-scales were associated with the vision markers. The most affected dimension was driving. A relationship with vision markers was found for the physical component of SF-36 and not for any dimension of EQ-5D. Conclusions The Time-Trade-Off was more sensitive than EQ-5D and SF-6D to changes in vision and visual functioning associated with glaucoma progression but could not measure quality of life changes in the mildest disease stages. PMID:22909264

Early Monocular Defocus Disrupts the Normal Development of Receptive-Field Structure in V2 Neurons of Macaque Monkeys

PubMed Central

Tao, Xiaofeng; Zhang, Bin; Shen, Guofu; Wensveen, Janice; Smith, Earl L.; Nishimoto, Shinji; Ohzawa, Izumi

2014-01-01

Experiencing different quality images in the two eyes soon after birth can cause amblyopia, a developmental vision disorder. Amblyopic humans show the reduced capacity for judging the relative position of a visual target in reference to nearby stimulus elements (position uncertainty) and often experience visual image distortion. Although abnormal pooling of local stimulus information by neurons beyond striate cortex (V1) is often suggested as a neural basis of these deficits, extrastriate neurons in the amblyopic brain have rarely been studied using microelectrode recording methods. The receptive field (RF) of neurons in visual area V2 in normal monkeys is made up of multiple subfields that are thought to reflect V1 inputs and are capable of encoding the spatial relationship between local stimulus features. We created primate models of anisometropic amblyopia and analyzed the RF subfield maps for multiple nearby V2 neurons of anesthetized monkeys by using dynamic two-dimensional noise stimuli and reverse correlation methods. Unlike in normal monkeys, the subfield maps of V2 neurons in amblyopic monkeys were severely disorganized: subfield maps showed higher heterogeneity within each neuron as well as across nearby neurons. Amblyopic V2 neurons exhibited robust binocular suppression and the strength of the suppression was positively correlated with the degree of hereogeneity and the severity of amblyopia in individual monkeys. Our results suggest that the disorganized subfield maps and robust binocular suppression of amblyopic V2 neurons are likely to adversely affect the higher stages of cortical processing resulting in position uncertainty and image distortion. PMID:25297110

Measurement of the geometric parameters of power contact wire based on binocular stereovision

NASA Astrophysics Data System (ADS)

Pan, Xue-Tao; Zhang, Ya-feng; Meng, Fei

2010-10-01

In the electrified railway power supply system, electric locomotive obtains power from the catenary's wire through the pantograph. Under the action of the pantograph, combined with various factors such as vibration, touch current, relative sliding speed, load, etc, the contact wire will produce mechanical wear and electrical wear. Thus, in electrified railway construction and daily operations, the geometric parameters such as line height, pull value, the width of wear surface must be under real-timely and non-contact detection. On the one hand, the safe operation of electric railways will be guaranteed; on the other hand, the wire endurance will be extended, and operating costs reduced. Based on the characteristics of the worn wires' image signal, the binocular stereo vision technology was applied for measurement of contact wire geometry parameters, a mathematical model of measurement of geometric parameters was derived, and the boundaries of the wound wire abrasion-point value were extracted by means of sub-pixel edge detection method based on the LOG operator with the least-squares fitting, thus measurements of the wire geometry parameters were realized. Principles were demonstrated through simulation experiments, and the experimental results show that the detection methods presented in this paper for measuring the accuracy, efficiency and convenience, etc. are close to or superior to the traditional measurements, which has laid a good foundation for the measurement system of geometric parameters for the contact wire of the development of binocular vision.

Tunnel Vision Prismatic Field Expansion: Challenges and Requirements

PubMed Central

Apfelbaum, Henry; Peli, Eli

2015-01-01

Purpose No prismatic solution for peripheral field loss (PFL) has gained widespread acceptance. Field extended by prisms has a corresponding optical scotoma at the prism apices. True expansion can be achieved when each eye is given a different view (through visual confusion). We analyze the effects of apical scotomas and binocular visual confusion in different designs to identify constraints on any solution that is likely to meet acceptance. Methods Calculated perimetry diagrams were compared to perimetry with PFL patients wearing InWave channel prisms and Trifield spectacles. Percept diagrams illustrate the binocular visual confusion. Results Channel prisms provide no benefit at primary gaze. Inconsequential extension was provided by InWave prisms, although accessible with moderate gaze shifts. Higher-power prisms provide greater extension, with greater paracentral scotoma loss, but require uncomfortable gaze shifts. Head turns, not eye scans, are needed to see regions lost to the apical scotomas. Trifield prisms provide field expansion at all gaze positions, but acceptance was limited by disturbing effects of central binocular visual confusion. Conclusions Field expansion when at primary gaze (where most time is spent) is needed while still providing unobstructed central vision. Paracentral multiplexing prisms we are developing that superimpose shifted and see-through views may accomplish that. Translational Relevance Use of the analyses and diagramming techniques presented here will be of value when considering prismatic aids for PFL, and could have prevented many unsuccessful designs and the improbable reports we cited from the literature. New designs must likely address the challenges identified here. PMID:26740910

Tunnel Vision Prismatic Field Expansion: Challenges and Requirements.

PubMed

Apfelbaum, Henry; Peli, Eli

2015-12-01

No prismatic solution for peripheral field loss (PFL) has gained widespread acceptance. Field extended by prisms has a corresponding optical scotoma at the prism apices. True expansion can be achieved when each eye is given a different view (through visual confusion). We analyze the effects of apical scotomas and binocular visual confusion in different designs to identify constraints on any solution that is likely to meet acceptance. Calculated perimetry diagrams were compared to perimetry with PFL patients wearing InWave channel prisms and Trifield spectacles. Percept diagrams illustrate the binocular visual confusion. Channel prisms provide no benefit at primary gaze. Inconsequential extension was provided by InWave prisms, although accessible with moderate gaze shifts. Higher-power prisms provide greater extension, with greater paracentral scotoma loss, but require uncomfortable gaze shifts. Head turns, not eye scans, are needed to see regions lost to the apical scotomas. Trifield prisms provide field expansion at all gaze positions, but acceptance was limited by disturbing effects of central binocular visual confusion. Field expansion when at primary gaze (where most time is spent) is needed while still providing unobstructed central vision. Paracentral multiplexing prisms we are developing that superimpose shifted and see-through views may accomplish that. Use of the analyses and diagramming techniques presented here will be of value when considering prismatic aids for PFL, and could have prevented many unsuccessful designs and the improbable reports we cited from the literature. New designs must likely address the challenges identified here.

Modification of visual function by early visual experience.

PubMed

Blakemore, C

1976-07-01

Physiological experiments, involving recording from the visual cortex in young kittens and monkeys, have given new insight into human developmental disorders. In the visual cortex of normal cats and monkeys most neurones are selectively sensitive to the orientation of moving edges and they receive very similar signals from both eyes. Even in very young kittens without visual experience, most neurones are binocularly driven and a small proportion of them are genuinely orientation selective. There is no passive maturation of the system in the absence of visual experience, but even very brief exposure to patterned images produces rapid emergence of the adult organization. These results are compared to observations on humans who have "recovered" from early blindness. Covering one eye in a kitten or a monkey, during a sensitive period early in life, produces a virtually complete loss of input from that eye in the cortex. These results can be correlated with the production of "stimulus deprivation amblyopia" in infants who have had one eye patched. Induction of a strabismus causes a loss of binocularity in the visual cortex, and in humans it leads to a loss of stereoscopic vision and binocular fusion. Exposing kittens to lines of one orientation modifies the preferred orientations of cortical cells and there is an analogous "meridional amblyopia" in astigmatic humans. The existence of a sensitive period in human vision is discussed, as well as the possibility of designing remedial and preventive treatments for human developmental disorders.

Prism-based single-camera system for stereo display

NASA Astrophysics Data System (ADS)

Zhao, Yue; Cui, Xiaoyu; Wang, Zhiguo; Chen, Hongsheng; Fan, Heyu; Wu, Teresa

2016-06-01

This paper combines the prism and single camera and puts forward a method of stereo imaging with low cost. First of all, according to the principle of geometrical optics, we can deduce the relationship between the prism single-camera system and dual-camera system, and according to the principle of binocular vision we can deduce the relationship between binoculars and dual camera. Thus we can establish the relationship between the prism single-camera system and binoculars and get the positional relation of prism, camera, and object with the best effect of stereo display. Finally, using the active shutter stereo glasses of NVIDIA Company, we can realize the three-dimensional (3-D) display of the object. The experimental results show that the proposed approach can make use of the prism single-camera system to simulate the various observation manners of eyes. The stereo imaging system, which is designed by the method proposed by this paper, can restore the 3-D shape of the object being photographed factually.

On Alternative Approaches to 3D Image Perception: Monoscopic 3D Techniques

NASA Astrophysics Data System (ADS)

Blundell, Barry G.

2015-06-01

In the eighteenth century, techniques that enabled a strong sense of 3D perception to be experienced without recourse to binocular disparities (arising from the spatial separation of the eyes) underpinned the first significant commercial sales of 3D viewing devices and associated content. However following the advent of stereoscopic techniques in the nineteenth century, 3D image depiction has become inextricably linked to binocular parallax and outside the vision science and arts communities relatively little attention has been directed towards earlier approaches. Here we introduce relevant concepts and terminology and consider a number of techniques and optical devices that enable 3D perception to be experienced on the basis of planar images rendered from a single vantage point. Subsequently we allude to possible mechanisms for non-binocular parallax based 3D perception. Particular attention is given to reviewing areas likely to be thought-provoking to those involved in 3D display development, spatial visualization, HCI, and other related areas of interdisciplinary research.

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

PubMed

Moro, Stefania S; Steeves, Jennifer K E

2018-04-13

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

AI And Early Vision - Part II

NASA Astrophysics Data System (ADS)

Julesz, Bela

1989-08-01

A quarter of a century ago I introduced two paradigms into psychology which in the intervening years have had a direct impact on the psychobiology of early vision and an indirect one on artificial intelligence (AI or machine vision). The first, the computer-generated random-dot stereogram (RDS) paradigm (Julesz, 1960) at its very inception posed a strategic question both for AI and neurophysiology. The finding that stereoscopic depth perception (stereopsis) is possible without the many enigmatic cues of monocular form recognition - as assumed previously - demonstrated that stereopsis with its basic problem of finding matches between corresponding random aggregates of dots in the left and right visual fields became ripe for modeling. Indeed, the binocular matching problem of stereopsis opened up an entire field of study, eventually leading to the computational models of David Marr (1982) and his coworkers. The fusion of RDS had an even greater impact on neurophysiologists - including Hubel and Wiesel (1962) - who realized that stereopsis must occur at an early stage, and can be studied easier than form perception. This insight recently culminated in the studies by Gian Poggio (1984) who found binocular-disparity - tuned neurons in the input stage to the visual cortex (layer IVB in V1) in the monkey that were selectively triggered by dynamic RDS. Thus the first paradigm led to a strategic insight: that with stereoscopic vision there is no camouflage, and as such was advantageous for our primate ancestors to evolve the cortical machinery of stereoscopic vision to capture camouflaged prey (insects) at a standstill. Amazingly, although stereopsis evolved relatively late in primates, it captured the very input stages of the visual cortex. (For a detailed review, see Julesz, 1986a)

Visual impairment and road traffic accidents among drivers in Jimma Town, Southwest Ethiopia.

PubMed

Biza, Mohamed; Mossie, Andualem; Woldemichael, Kifle; Gelaw, Yeshigeta

2013-04-01

Vision play a vital role in driving where good and efficient visual functioning of the driver is essential. Any significant loss of visual function will diminish a driver's ability to operate a motor vehicle safely and will thus contribute to road traffic injury. However, there is little evidence indicating that defects of vision alone cause road traffic accidents. To determine the impact of visual impairment and other factors on road traffic accident among vehicle drivers. A cross-sectional descriptive study was conducted on 249 sampled drivers in Southwest Ethiopia. A pretested interviewer led questionnaire was used for interview and vision tests were done using Snellen's acuity chart and Ishihara pseudo-isochromatic plates. Statistical analyses were performed using SPSS version 16.0. The mean age of drivers was 33.6 years (SD +/- 10.3). The relative frequency of self reported road traffic accident was 15.3%. The prevalence of uncorrected binocular visual impairment was 1.6% and there was a significant association between visual impairment and road traffic accident (P < 0.05). Uncorrected refractive error was seen in 7.6% and 8.8% of drivers in the right and left eyes respectively, and 3.2% of them had vision less than what is required to obtain driving license (visual acuity of 6/12). None of the drivers with refractive errors were wearing appropriate corrections. Color vision impairment was seen in 1.6% of the drivers. A significant proportion (9.6%) of the drivers did not have eye exam for their driving license. Uncorrected binocular visual impairment was strongly associated with road traffic accident. There is need for consistent inspection and screening, strict rules and regulations of licensing and health education for drivers to minimize road traffic accident.

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

ERIC Educational Resources Information Center

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…

Visual and Ocular Control Anomalies in Relation to Reading Difficulty.

ERIC Educational Resources Information Center

Bedwell, C. H.; And Others

1980-01-01

The visual behavior under both static and dynamic viewing conditions was examined in a group of 13-year-old successful readers, compared with a group of the same age retarded in reading. Research supports the notion that problems of dynamic binocular vision and control while reading are important. (Author/KC)

Limits of Precision for Human Eye Motor Control

DTIC Science & Technology

1989-11-01

APE (Watt & Andrews, 1981) or a staircase method similar to PEST (Taylor & Creelman , 1967) were used. The results from these different methods of...Freeman StCyr, G.J. & Fender, D.H. (1969) The interplay of drifts and flicks in binocular fixation. Vision Res. 9, 245-265 Taylor, M.M. & Creelman , C.D

Contextual cueing impairment in patients with age-related macular degeneration.

PubMed

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

2013-09-12

Visual attention can be guided by past experience of regularities in our visual environment. In the contextual cueing paradigm, incidental learning of repeated distractor configurations speeds up search times compared to random search arrays. Concomitantly, fewer fixations and more direct scan paths indicate more efficient visual exploration in repeated search arrays. In previous work, we found that simulating a central scotoma in healthy observers eliminated this search facilitation. Here, we investigated contextual cueing in patients with age-related macular degeneration (AMD) who suffer from impaired foveal vision. AMD patients performed visual search using only their more severely impaired eye (n = 13) as well as under binocular viewing (n = 16). Normal-sighted controls developed a significant contextual cueing effect. In comparison, patients showed only a small nonsignificant advantage for repeated displays when searching with their worse eye. When searching binocularly, they profited from contextual cues, but still less than controls. Number of fixations and scan pattern ratios showed a comparable pattern as search times. Moreover, contextual cueing was significantly correlated with acuity in monocular search. Thus, foveal vision loss may lead to impaired guidance of attention by contextual memory cues.

High-performance object tracking and fixation with an online neural estimator.

PubMed

Kumarawadu, Sisil; Watanabe, Keigo; Lee, Tsu-Tian

2007-02-01

Vision-based target tracking and fixation to keep objects that move in three dimensions in view is important for many tasks in several fields including intelligent transportation systems and robotics. Much of the visual control literature has focused on the kinematics of visual control and ignored a number of significant dynamic control issues that limit performance. In line with this, this paper presents a neural network (NN)-based binocular tracking scheme for high-performance target tracking and fixation with minimum sensory information. The procedure allows the designer to take into account the physical (Lagrangian dynamics) properties of the vision system in the control law. The design objective is to synthesize a binocular tracking controller that explicitly takes the systems dynamics into account, yet needs no knowledge of dynamic nonlinearities and joint velocity sensory information. The combined neurocontroller-observer scheme can guarantee the uniform ultimate bounds of the tracking, observer, and NN weight estimation errors under fairly general conditions on the controller-observer gains. The controller is tested and verified via simulation tests in the presence of severe target motion changes.

Stereo-motion cooperation and the use of motion disparity in the visual perception of 3-D structure.

PubMed

Cornilleau-Pérès, V; Droulez, J

1993-08-01

When an observer views a moving scene binocularly, both motion parallax and binocular disparity provide depth information. In Experiments 1A-1C, we measured sensitivity to surface curvature when these depth cues were available either individually or simultaneously. When the depth cues yielded comparable sensitivity to surface curvature, we found that curvature detection was easier with the cues present simultaneously, rather than individually. For 2 of the 6 subjects, this effect was stronger when the component of frontal translation of the surface was vertical, rather than horizontal. No such anisotropy was found for the 4 other subjects. If a moving object is observed binocularly, the patterns of optic flow are different on the left and right retinae. We have suggested elsewhere (Cornilleau-Pérès & Droulez, in press) that this motion disparity might be used as a visual cue for the perception of a 3-D structure. Our model consisted in deriving binocular disparity from the left and right distributions of vertical velocities, rather than from luminous intensities, as has been done in classical studies on stereoscopic vision. The model led to some predictions concerning the detection of surface curvature from motion disparity in the presence or absence of intensity-based disparity (classically termed binocular disparity). In a second set of experiments, we attempted to test these predictions, and we failed to validate our theoretical scheme from a physiological point of view.

The design of visible system for improving the measurement accuracy of imaging points

NASA Astrophysics Data System (ADS)

Shan, Qiu-sha; Li, Gang; Zeng, Luan; Liu, Kai; Yan, Pei-pei; Duan, Jing; Jiang, Kai

2018-02-01

It has a widely applications in robot vision and 3D measurement for binocular stereoscopic measurement technology. And the measure precision is an very important factor, especially in 3D coordination measurement, high measurement accuracy is more stringent to the distortion of the optical system. In order to improving the measurement accuracy of imaging points, to reducing the distortion of the imaging points, the optical system must be satisfied the requirement of extra low distortion value less than 0.1#65285;, a transmission visible optical lens was design, which has characteristic of telecentric beam path in image space, adopted the imaging model of binocular stereo vision, and imaged the drone at the finity distance. The optical system was adopted complex double Gauss structure, and put the pupil stop on the focal plane of the latter groups, maked the system exit pupil on the infinity distance, and realized telecentric beam path in image space. The system mainly optical parameter as follows: the system spectrum rangement is visible light wave band, the optical effective length is f '=30mm, the relative aperture is 1/3, and the fields of view is 21°. The final design results show that the RMS value of the spread spots of the optical lens in the maximum fields of view is 2.3μm, which is less than one pixel(3.45μm) the distortion value is less than 0.1%, the system has the advantage of extra low distortion value and avoids the latter image distortion correction; the proposed modulation transfer function of the optical lens is 0.58(@145 lp/mm), the imaging quality of the system is closed to the diffraction limited; the system has simply structure, and can satisfies the requirements of the optical indexes. Ultimately, based on the imaging model of binocular stereo vision was achieved to measuring the drone at the finity distance.

Modified Monovision With Spherical Aberration to Improve Presbyopic Through-Focus Visual Performance

PubMed Central

Zheleznyak, Len; Sabesan, Ramkumar; Oh, Je-Sun; MacRae, Scott; Yoon, Geunyoung

2013-01-01

Purpose. To investigate the impact on visual performance of modifying monovision with monocularly induced spherical aberration (SA) to increase depth of focus (DoF), thereby enhancing binocular through-focus visual performance. Methods. A binocular adaptive optics (AO) vision simulator was used to correct both eyes' native aberrations and induce traditional (TMV) and modified (MMV) monovision corrections. TMV was simulated with 1.5 diopters (D) of anisometropia (dominant eye at distance, nondominant eye at near). Zernike primary SA was induced in the nondominant eye in MMV. A total of four MMV conditions were tested with various amounts of SA (±0.2 and ±0.4 μm) and fixed anisometropia (1.5 D). Monocular and binocular visual acuity (VA) and contrast sensitivity (CS) at 10 cyc/deg and binocular summation were measured through-focus in three cyclopledged subjects with 4-mm pupils. Results. MMV with positive SA had a larger benefit for intermediate distances (1.5 lines at 1.0 D) than with negative SA, compared with TMV. Negative SA had a stronger benefit in VA at near. DoF of all MMV conditions was 3.5 ± 0.5 D (mean) as compared with TMV (2.7 ± 0.3 D). Through-focus CS at 10 cyc/deg was significantly reduced with MMV as compared to TMV only at intermediate object distances, however was unaffected at distance. Binocular summation was absent at all object distances except 0.5 D, where it improved in MMV by 19% over TMV. Conclusions. Modified monovision with SA improves through-focus VA and DoF as compared with traditional monovision. Binocular summation also increased as interocular similarity of image quality increased due to extended monocular DoF. PMID:23557742

[Refractive Surgery in Children with Myopic Anisometropia and Amblyopia in Comparison with Conventional Treatment by Contact Lenses].

PubMed

Autrata, R; Krejčířová, I; Griščíková, L; Doležel, Z

2016-01-01

Our study evaluated the visual and refractive results of LASEK and anterior chamber phakic intraocular lens (pIOL) implantation performed for high myopic anisometropia with amblyopia and contact lens intolerance in children compared with conventional treatment by contact lenses.Fourty-three patients (Group A) aged 3 to 7 years (mean, 5,6 years) with high myopic anisometropia and amblyopia had performed multizonal LASEK (27 eyes) or pIOL Verisyse implantation (16 eyes) on the more myopic eye in general anesthesia. Surgery was followed by patching of the dominant eye. Postoperative visual and refractive outcomes were analyzed and all children had minimally two years follow-up after procedure. Refractive surgical data were reported in standard format to describe safety, efficacy, predictability and stability of the procedure. This Group A of 43 children was compared with control Group B of 37 children (mean age 5,4 years), in whom myopic anisometropia and amblyopia were treated conventionally by contact lenses (CL) and patching of the dominant eye. Visual acuity (VA) and binocular vision (BV) outcome were analyzed and compared in both groups.The mean preoperative spherical equivalent (SE) cycloplegic refraction in Group A was - 9,45 ± 2,47 diopters (D) (range -6.0 to -18.25 D) and the mean postoperative SE -1,48 ± 1,13 D (range + 0,75 to - 2,25 D). The mean preop. decimal uncorrected visual acuity (UCVA) 0,023 ± 0,017 increased to 0,46 ± 0,18. The mean preop.decimal best-corrected visual acuity (BCVA) in Group A was 0,28 ± 0.22 and changed to 0,78± 0,19 by 2 years after surgery. The mean BCVA in Group B was 0,23 ± 0,19, at start of CL correction and amblyopia therapy, and improved to 0,42 ± 0,15 after two years. The mean BCVA at final examination was significantly better in Group A (P < 0,05). Binocular vision improvement expressed by the proportions of subjects gained fusion and stereopsis, was overall better in Group A (81 %) than in Group B (33 %), (P < 0,05). There were no complications after surgery.Refractive surgery in children, multizonal LASEK and pIOL Verisyse implantation, are effective and safe methods for correction of high myopic anisometropia, and has an important role in the treatment of amblyopia in children when contact lens intolerance. Visual acuity and binocular vision outcomes were better in children who received permanent surgical correction of anisometropia, than in children conventionally treated by contact lenses. myopic anisometropia, amblyopia, children, laser subepithelial keratomileusis (LASEK), anterior chamber phakic intraocular lenses (AC pIOL), binocular vision.

[Binocular functions in amblyopia and strabismus].

PubMed

Awaya, S; Sato, M; Tsuzuki, K; Takara, T; Hiraiwa, S; Ota, K; Arai, M; Yoshida, M; Miyake, Y; Terasaki, H; Horiguchi, M; Hirano, K; Hirose, H; Uno, Y; Suzuki, Y; Iwata, M; Takai, Y; Maeda, M; Hisano, S; Kawakita, T; Omura, T; Ota, Y; Kondo, N; Takashi, A; Kawakami, O

1997-12-01

Regarding the changing trends in the concept, definition, etiological classification, and criteria for diagnosis of amblyopia, we reviewed a total of 4,693 cases of amblyopia seen during the past 37 years. The amblyopia was divided into four types: strabismic, anisometropic, ametropic, and form vision deprivative. There was a definite trend for the incidence to decrease and for the diagnosis to be made during earlier age in recent years. Although favorable recovery of visual acuity is obtained after treatment of amblyopia and strabismus, there are difficulties in obtaining good binocular functions in early-onset amblyopia and strabismus. This feature was evaluated in regard to motion perception asymmetry (MPA) and binocular depth from motion (DFM). Many cases of early-onset amblyopia and strabismus showed no disparity stereopsis, or position stereopsis, in spite of the presence of DFM. The MPA appeared to be closely related to early-onset esotropia regardless of age, while it disappeared and motion perception became symmetric 4 to 5 months after birth in normal infants. The DFM seemed to play an important role in maintaining good motor alignment for several years after surgery. I developed a checkerboard pattern stimulator in 1978. This method proved to be useful in developing binocular functions and motor alignment by applying simultaneous bifoveolar stimulation and anti-suppression. Extensive exposure to the stimulation was essential for therapeutic success.

Selective binocular vision loss in two subterranean caviomorph rodents: Spalacopus cyanus and Ctenomys talarum

PubMed Central

Vega-Zuniga, T.; Medina, F. S.; Marín, G.; Letelier, J. C.; Palacios, A. G.; Němec, P.; Schleich, C. E.; Mpodozis, J.

2017-01-01

To what extent can the mammalian visual system be shaped by visual behavior? Here we analyze the shape of the visual fields, the densities and distribution of cells in the retinal ganglion-cell layer and the organization of the visual projections in two species of facultative non-strictly subterranean rodents, Spalacopus cyanus and Ctenomys talarum, aiming to compare these traits with those of phylogenetically closely related species possessing contrasting diurnal/nocturnal visual habits. S. cyanus shows a definite zone of frontal binocular overlap and a corresponding area centralis, but a highly reduced amount of ipsilateral retinal projections. The situation in C. talarum is more extreme as it lacks of a fronto-ventral area of binocular superposition, has no recognizable area centralis and shows no ipsilateral retinal projections except to the suprachiasmatic nucleus. In both species, the extension of the monocular visual field and of the dorsal region of binocular overlap as well as the whole set of contralateral visual projections, appear well-developed. We conclude that these subterranean rodents exhibit, paradoxically, diurnal instead of nocturnal visual specializations, but at the same time suffer a specific regression of the anatomical substrate for stereopsis. We discuss these findings in light of the visual ecology of subterranean lifestyles. PMID:28150809

Recovering stereo vision by squashing virtual bugs in a virtual reality environment.

PubMed

Vedamurthy, Indu; Knill, David C; Huang, Samuel J; Yung, Amanda; Ding, Jian; Kwon, Oh-Sang; Bavelier, Daphne; Levi, Dennis M

2016-06-19

Stereopsis is the rich impression of three-dimensionality, based on binocular disparity-the differences between the two retinal images of the same world. However, a substantial proportion of the population is stereo-deficient, and relies mostly on monocular cues to judge the relative depth or distance of objects in the environment. Here we trained adults who were stereo blind or stereo-deficient owing to strabismus and/or amblyopia in a natural visuomotor task-a 'bug squashing' game-in a virtual reality environment. The subjects' task was to squash a virtual dichoptic bug on a slanted surface, by hitting it with a physical cylinder they held in their hand. The perceived surface slant was determined by monocular texture and stereoscopic cues, with these cues being either consistent or in conflict, allowing us to track the relative weighting of monocular versus stereoscopic cues as training in the task progressed. Following training most participants showed greater reliance on stereoscopic cues, reduced suppression and improved stereoacuity. Importantly, the training-induced changes in relative stereo weights were significant predictors of the improvements in stereoacuity. We conclude that some adults deprived of normal binocular vision and insensitive to the disparity information can, with appropriate experience, recover access to more reliable stereoscopic information.This article is part of the themed issue 'Vision in our three-dimensional world'. © 2016 The Author(s).

Recovering stereo vision by squashing virtual bugs in a virtual reality environment

PubMed Central

Vedamurthy, Indu; Knill, David C.; Huang, Samuel J.; Yung, Amanda; Ding, Jian; Kwon, Oh-Sang; Bavelier, Daphne

2016-01-01

Stereopsis is the rich impression of three-dimensionality, based on binocular disparity—the differences between the two retinal images of the same world. However, a substantial proportion of the population is stereo-deficient, and relies mostly on monocular cues to judge the relative depth or distance of objects in the environment. Here we trained adults who were stereo blind or stereo-deficient owing to strabismus and/or amblyopia in a natural visuomotor task—a ‘bug squashing’ game—in a virtual reality environment. The subjects' task was to squash a virtual dichoptic bug on a slanted surface, by hitting it with a physical cylinder they held in their hand. The perceived surface slant was determined by monocular texture and stereoscopic cues, with these cues being either consistent or in conflict, allowing us to track the relative weighting of monocular versus stereoscopic cues as training in the task progressed. Following training most participants showed greater reliance on stereoscopic cues, reduced suppression and improved stereoacuity. Importantly, the training-induced changes in relative stereo weights were significant predictors of the improvements in stereoacuity. We conclude that some adults deprived of normal binocular vision and insensitive to the disparity information can, with appropriate experience, recover access to more reliable stereoscopic information. This article is part of the themed issue ‘Vision in our three-dimensional world’. PMID:27269607

Enhancement of vision by monocular deprivation in adult mice.

PubMed

Prusky, Glen T; Alam, Nazia M; Douglas, Robert M

2006-11-08

Plasticity of vision mediated through binocular interactions has been reported in mammals only during a "critical" period in juvenile life, wherein monocular deprivation (MD) causes an enduring loss of visual acuity (amblyopia) selectively through the deprived eye. Here, we report a different form of interocular plasticity of vision in adult mice in which MD leads to an enhancement of the optokinetic response (OKR) selectively through the nondeprived eye. Over 5 d of MD, the spatial frequency sensitivity of the OKR increased gradually, reaching a plateau of approximately 36% above pre-deprivation baseline. Eye opening initiated a gradual decline, but sensitivity was maintained above pre-deprivation baseline for 5-6 d. Enhanced function was restricted to the monocular visual field, notwithstanding the dependence of the plasticity on binocular interactions. Activity in visual cortex ipsilateral to the deprived eye was necessary for the characteristic induction of the enhancement, and activity in visual cortex contralateral to the deprived eye was necessary for its maintenance after MD. The plasticity also displayed distinct learning-like properties: Active testing experience was required to attain maximal enhancement and for enhancement to persist after MD, and the duration of enhanced sensitivity after MD was extended by increasing the length of MD, and by repeating MD. These data show that the adult mouse visual system maintains a form of experience-dependent plasticity in which the visual cortex can modulate the normal function of subcortical visual pathways.

Evaluation Field Building in South Asia: Insights from the Rear View Mirror

ERIC Educational Resources Information Center

Grob, George F.

2010-01-01

The author enjoyed reading Katharine Hay's ambitious and humbling visions for evaluation field building in South Asia. She has successfully positioned herself on a high mountain with a wonderful set of binoculars that enable her to see the entire evaluation landscape of South Asia. She magically sees and describes significant historical forces and…

Binocular iPad Game vs Patching for Treatment of Amblyopia in Children: A Randomized Clinical Trial.

PubMed

Kelly, Krista R; Jost, Reed M; Dao, Lori; Beauchamp, Cynthia L; Leffler, Joel N; Birch, Eileen E

2016-12-01

Fellow eye patching has long been the standard treatment for amblyopia, but it does not always restore 20/20 vision or teach the eyes to work together. Amblyopia can be treated with binocular games that rebalance contrast between the eyes so that a child may overcome suppression. However, it is unclear whether binocular treatment is comparable to patching in treating amblyopia. To assess the effectiveness of a binocular iPad (Apple Inc) adventure game as amblyopia treatment and compare this binocular treatment with patching, the current standard of care. This investigation was a randomized clinical trial with a crossover design at a nonprofit eye research institute. Between February 20, 2015, and January 4, 2016, a total of 28 patients were enrolled in the study, with 14 randomized to binocular game treatment and 14 to patching treatment. Binocular game and patching as amblyopia treatments. The primary outcome was change in amblyopic eye best-corrected visual acuity (BCVA) at the 2-week visit. Secondary outcomes were change in stereoacuity and suppression at the 2-week visit and change in BCVA at the 4-week visit. Among 28 children, the mean (SD) age at baseline was 6.7 (1.4) years (age range, 4.6-9.5 years), and 7 (25%) were female. At baseline, the mean (SD) amblyopic eye BCVA was 0.48 (0.14) logMAR (approximately 20/63; range, 0.3-0.8 logMAR [20/40 to 20/125]), with 14 children randomized to the binocular game and 14 to patching for 2 weeks. At the 2-week visit, improvement in amblyopic eye BCVA was greater with the binocular game compared with patching, with a mean (SD) improvement of 0.15 (0.08) logMAR (mean [SD], 1.5 [0.8] lines) vs 0.07 (0.08) logMAR (mean [SD], 0.7 [0.8] line; P = .02) after 2 weeks of treatment. These improvements from baseline were significant for the binocular game (mean [SD] improvement, 1.5 [0.8] lines; P < .001) and for patching (mean [SD] improvement, 0.7 [0.8] line; P = .006). Depth of suppression improved from baseline at the 2-week visit for the binocular game (mean [SD], 4.82 [2.82] vs 3.24 [2.87]; P = .03) and for patching (mean [SD], 4.77 [3.10] vs 2.57 [1.67]; P = .004). Patching children crossed over to binocular game treatment, and all 28 children played the game for another 2 weeks. At the 4-week visit, no group difference was found in BCVA change, with children who crossed over to the binocular games catching up with children treated with binocular games, for a mean (SD) improvement of 0.17 (0.10) logMAR (mean [SD], 1.7 [1.0] lines) for the binocular game vs a mean (SD) improvement of 0.16 (0.12) logMAR (mean [SD], 1.6 [1.2] lines) for the patching crossover (P = .73). A binocular iPad game was effective in treating childhood amblyopia and was more efficacious than patching at the 2-week visit. Binocular games that rebalance contrast to overcome suppression are a promising additional option for treating amblyopia. clinicaltrials.gov Identifier: NCT02365090.

Covert spatial attention is functionally intact in amblyopic human adults.

PubMed

Roberts, Mariel; Cymerman, Rachel; Smith, R Theodore; Kiorpes, Lynne; Carrasco, Marisa

2016-12-01

Certain abnormalities in behavioral performance and neural signaling have been attributed to a deficit of visual attention in amblyopia, a neurodevelopmental disorder characterized by a diverse array of visual deficits following abnormal binocular childhood experience. Critically, most have inferred attention's role in their task without explicitly manipulating and measuring its effects against a baseline condition. Here, we directly investigate whether human amblyopic adults benefit from covert spatial attention-the selective processing of visual information in the absence of eye movements-to the same degree as neurotypical observers. We manipulated both involuntary (Experiment 1) and voluntary (Experiment 2) attention during an orientation discrimination task for which the effects of covert spatial attention have been well established in neurotypical and special populations. In both experiments, attention significantly improved accuracy and decreased reaction times to a similar extent (a) between the eyes of the amblyopic adults and (b) between the amblyopes and their age- and gender-matched controls. Moreover, deployment of voluntary attention away from the target location significantly impaired task performance (Experiment 2). The magnitudes of the involuntary and voluntary attention benefits did not correlate with amblyopic depth or severity. Both groups of observers showed canonical performance fields (better performance along the horizontal than vertical meridian and at the lower than upper vertical meridian) and similar effects of attention across locations. Despite their characteristic low-level vision impairments, covert spatial attention remains functionally intact in human amblyopic adults.

Tract-based spatial statistics analysis of white matter changes in children with anisometropic amblyopia.

PubMed

Li, Qian; Zhai, Liying; Jiang, Qinying; Qin, Wen; Li, Qingji; Yin, Xiaohui; Guo, Mingxia

2015-06-15

Amblyopia is a neurological disorder of vision that follows abnormal binocular interaction or visual deprivation during early life. Previous studies have reported multiple functional or structural cortical alterations. Although white matter was also studied, it still cannot be clarified clearly which fasciculus was affected by amblyopia. In the present study, tract-based spatial statistics analysis was applied to diffusion tensor imaging (DTI) to investigate potential diffusion changes of neural tracts in anisometropic amblyopia. Fractional anisotropy (FA) value was calculated and compared between 20 amblyopic children and 18 healthy age-matched controls. In contrast to the controls, significant decreases in FA values were found in right optic radiation (OR), left inferior longitudinal fasciculus/inferior fronto-occipital fasciculus (ILF/IFO) and right superior longitudinal fasciculus (SLF) in the amblyopia. Furthermore, FA values of these identified tracts showed positive correlation with visual acuity. It can be inferred that abnormal visual input not only hinders OR from well developed, but also impairs fasciculi associated with dorsal and ventral visual pathways, which may be responsible for the amblyopic deficiency in object discrimination and stereopsis. Increased FA was detected in right posterior part of corpus callosum (CC) with a medium effect size, which may be due to compensation effect. DTI with subsequent measurement of FA is a useful tool for investigating neuronal tract involvement in amblyopia. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Natural images dominate in binocular rivalry

PubMed Central

Baker, Daniel H.; Graf, Erich W.

2009-01-01

Ecological approaches to perception have demonstrated that information encoding by the visual system is informed by the natural environment, both in terms of simple image attributes like luminance and contrast, and more complex relationships corresponding to Gestalt principles of perceptual organization. Here, we ask if this optimization biases perception of visual inputs that are perceptually bistable. Using the binocular rivalry paradigm, we designed stimuli that varied in either their spatiotemporal amplitude spectra or their phase spectra. We found that noise stimuli with “natural” amplitude spectra (i.e., amplitude content proportional to 1/f, where f is spatial or temporal frequency) dominate over those with any other systematic spectral slope, along both spatial and temporal dimensions. This could not be explained by perceived contrast measurements, and occurred even though all stimuli had equal energy. Calculating the effective contrast following attenuation by a model contrast sensitivity function suggested that the strong contrast dependency of rivalry provides the mechanism by which binocular vision is optimized for viewing natural images. We also compared rivalry between natural and phase-scrambled images and found a strong preference for natural phase spectra that could not be accounted for by observer biases in a control task. We propose that this phase specificity relates to contour information, and arises either from the activity of V1 complex cells, or from later visual areas, consistent with recent neuroimaging and single-cell work. Our findings demonstrate that human vision integrates information across space, time, and phase to select the input most likely to hold behavioral relevance. PMID:19289828

Early Binocular Input Is Critical for Development of Audiovisual but Not Visuotactile Simultaneity Perception.

PubMed

Chen, Yi-Chuan; Lewis, Terri L; Shore, David I; Maurer, Daphne

2017-02-20

Temporal simultaneity provides an essential cue for integrating multisensory signals into a unified perception. Early visual deprivation, in both animals and humans, leads to abnormal neural responses to audiovisual signals in subcortical and cortical areas [1-5]. Behavioral deficits in integrating complex audiovisual stimuli in humans are also observed [6, 7]. It remains unclear whether early visual deprivation affects visuotactile perception similarly to audiovisual perception and whether the consequences for either pairing differ after monocular versus binocular deprivation [8-11]. Here, we evaluated the impact of early visual deprivation on the perception of simultaneity for audiovisual and visuotactile stimuli in humans. We tested patients born with dense cataracts in one or both eyes that blocked all patterned visual input until the cataractous lenses were removed and the affected eyes fitted with compensatory contact lenses (mean duration of deprivation = 4.4 months; range = 0.3-28.8 months). Both monocularly and binocularly deprived patients demonstrated lower precision in judging audiovisual simultaneity. However, qualitatively different outcomes were observed for the two patient groups: the performance of monocularly deprived patients matched that of young children at immature stages, whereas that of binocularly deprived patients did not match any stage in typical development. Surprisingly, patients performed normally in judging visuotactile simultaneity after either monocular or binocular deprivation. Therefore, early binocular input is necessary to develop normal neural substrates for simultaneity perception of visual and auditory events but not visual and tactile events. Copyright © 2017 Elsevier Ltd. All rights reserved.

Infantile Nystagmus and Abnormalities of Conjugate Eye Movements in Down Syndrome.

PubMed

Weiss, Avery H; Kelly, John P; Phillips, James O

2016-03-01

Subjects with Down syndrome (DS) have an anatomical defect within the cerebellum that may impact downstream oculomotor areas. This study characterized gaze holding and gains for smooth pursuit, saccades, and optokinetic nystagmus (OKN) in DS children with infantile nystagmus (IN). Clinical data of 18 DS children with IN were reviewed retrospectively. Subjects with constant strabismus were excluded to remove any contribution of latent nystagmus. Gaze-holding, horizontal and vertical saccades to target steps, horizontal smooth pursuit of drifting targets, OKN in response to vertically or horizontally-oriented square wave gratings drifted at 15°/s, 30°/s, and 45°/s were recorded using binocular video-oculography. Seven subjects had additional optical coherence tomography imaging. Infantile nystagmus was associated with one or more gaze-holding instabilities (GHI) in each subject. The majority of subjects had a combination of conjugate horizontal jerk with constant or exponential slow-phase velocity, asymmetric or symmetric, and either monocular or binocular pendular nystagmus. Six of seven subjects had mild (Grade 0-1) persistence of retinal layers overlying the fovea, similar to that reported in DS children without nystagmus. All subjects had abnormal gains across one or more stimulus conditions (horizontal smooth pursuit, saccades, or OKN). Saccade velocities followed the main sequence. Down syndrome subjects with IN show a wide range of GHI and abnormalities of conjugate eye movements. We propose that these ocular motor abnormalities result from functional abnormalities of the cerebellum and/or downstream oculomotor circuits, perhaps due to extensive miswiring.

Objective and automated measurement of dynamic vision functions

NASA Technical Reports Server (NTRS)

Flom, M. C.; Adams, A. J.

1976-01-01

A phoria stimulus array and electro-oculographic (EOG) arrangements for measuring motor and sensory responses of subjects subjected to stress or drug conditions are described, along with experimental procedures. Heterophoria (as oculomotor function) and glare recovery time (time required for photochemical and neural recovery after exposure to a flash stimulus) are measured, in research aimed at developing automated objective measurement of dynamic vision functions. Onset of involuntary optokinetic nystagmus in subjects attempting to track moving stripes (while viewing through head-mounted binocular eyepieces) after exposure to glare serves as an objective measure of glare recovery time.

Device for diagnosis and treatment of impairments on binocular vision and stereopsis

NASA Astrophysics Data System (ADS)

Bahn, Jieun; Choi, Yong-Jin; Son, Jung-Young; Kodratiev, N. V.; Elkhov, Victor A.; Ovechkis, Yuri N.; Chung, Chan-sup

2001-06-01

Strabismus and amblyopia are two main impairments of our visual system, which are responsible for the loss of stereovision. A device is developed for diagnosis and treatment of strabismus and amblyopia, and for training and developing stereopsis. This device is composed of a liquid crystal glasses (LCG), electronics for driving LCG and synchronizing with an IBM PC, and a special software. The software contains specially designed patterns and graphics for enabling to train and develop stereopsis, and do objective measurement of some stereoscopic vision parameters such as horizontal and vertical phoria, fusion, fixation disparity, and stereoscopic visual threshold.

Early monocular defocus disrupts the normal development of receptive-field structure in V2 neurons of macaque monkeys.

PubMed

Tao, Xiaofeng; Zhang, Bin; Shen, Guofu; Wensveen, Janice; Smith, Earl L; Nishimoto, Shinji; Ohzawa, Izumi; Chino, Yuzo M

2014-10-08

Experiencing different quality images in the two eyes soon after birth can cause amblyopia, a developmental vision disorder. Amblyopic humans show the reduced capacity for judging the relative position of a visual target in reference to nearby stimulus elements (position uncertainty) and often experience visual image distortion. Although abnormal pooling of local stimulus information by neurons beyond striate cortex (V1) is often suggested as a neural basis of these deficits, extrastriate neurons in the amblyopic brain have rarely been studied using microelectrode recording methods. The receptive field (RF) of neurons in visual area V2 in normal monkeys is made up of multiple subfields that are thought to reflect V1 inputs and are capable of encoding the spatial relationship between local stimulus features. We created primate models of anisometropic amblyopia and analyzed the RF subfield maps for multiple nearby V2 neurons of anesthetized monkeys by using dynamic two-dimensional noise stimuli and reverse correlation methods. Unlike in normal monkeys, the subfield maps of V2 neurons in amblyopic monkeys were severely disorganized: subfield maps showed higher heterogeneity within each neuron as well as across nearby neurons. Amblyopic V2 neurons exhibited robust binocular suppression and the strength of the suppression was positively correlated with the degree of hereogeneity and the severity of amblyopia in individual monkeys. Our results suggest that the disorganized subfield maps and robust binocular suppression of amblyopic V2 neurons are likely to adversely affect the higher stages of cortical processing resulting in position uncertainty and image distortion. Copyright © 2014 the authors 0270-6474/14/3413840-15$15.00/0.

More superimposition for contrast-modulated than luminance-modulated stimuli during binocular rivalry.

PubMed

Skerswetat, Jan; Formankiewicz, Monika A; Waugh, Sarah J

2018-01-01

Luminance-modulated noise (LM) and contrast-modulated noise (CM) gratings were presented with interocularly correlated, uncorrelated and anti-correlated binary noise to investigate their contributions to mixed percepts, specifically piecemeal and superimposition, during binocular rivalry. Stimuli were sine-wave gratings of 2 c/deg presented within 2 deg circular apertures. The LM stimulus contrast was 0.1 and the CM stimulus modulation depth was 1.0, equating to approximately 5 and 7 times detection threshold, respectively. Twelve 45 s trials, per noise configuration, were carried out. Fifteen participants with normal vision indicated via button presses whether an exclusive, piecemeal or superimposed percept was seen. For all noise conditions LM stimuli generated more exclusive visibility, and lower proportions of superimposition. CM stimuli led to greater proportions and longer periods of superimposition. For both stimulus types, correlated interocular noise generated more superimposition than did anti- or uncorrelated interocular noise. No significant effect of stimulus type (LM vs CM) or noise configuration (correlated, uncorrelated, anti-correlated) on piecemeal perception was found. Exclusive visibility was greater in proportion, and perceptual changes more numerous, during binocular rivalry for CM stimuli when interocular noise was not correlated. This suggests that mutual inhibition, initiated by non-correlated noise CM gratings, occurs between neurons processing luminance noise (first-order component), as well as those processing gratings (second-order component). Therefore, first- and second-order components can contribute to overall binocular rivalry responses. We suggest the addition of a new well to the current energy landscape model for binocular rivalry that takes superimposition into account. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dynamics of the near response under natural viewing conditions with an open-view sensor

PubMed Central

Chirre, Emmanuel; Prieto, Pedro; Artal, Pablo

2015-01-01

We have studied the temporal dynamics of the near response (accommodation, convergence and pupil constriction) in healthy subjects when accommodation was performed under natural binocular and monocular viewing conditions. A binocular open-view multi-sensor based on an invisible infrared Hartmann-Shack sensor was used for non-invasive measurements of both eyes simultaneously in real time at 25Hz. Response times for each process under different conditions were measured. The accommodative responses for binocular vision were faster than for monocular conditions. When one eye was blocked, accommodation and convergence were triggered simultaneously and synchronized, despite the fact that no retinal disparity was available. We found that upon the onset of the near target, the unblocked eye rapidly changes its line of sight to fix it on the stimulus while the blocked eye moves in the same direction, producing the equivalent to a saccade, but then converges to the (blocked) target in synchrony with accommodation. This open-view instrument could be further used for additional experiments with other tasks and conditions. PMID:26504666

Linear and nonlinear transparencies in binocular vision.

PubMed Central

Langley, K; Fleet, D J; Hibbard, P B

1998-01-01

When the product of a vertical square-wave grating (contrast envelope) and a horizontal sinusoidal grating (carrier) are viewed binocularly with different disparity cues they can be perceived transparently at different depths. We found, however, that the transparency was asymmetric; it only occurred when the envelope was perceived to be the overlaying surface. When the same two signals were added, the percept of transparency was symmetrical; either signal could be seen in front of or behind the other at different depths. Differences between these multiplicative and additive signal combinations were examined in two experiments. In one, we measured disparity thresholds for transparency as a function of the spatial frequency of the envelope. In the other, we measured disparity discrimination thresholds. In both experiments the thresholds for the multiplicative condition, unlike the additive condition, showed distinct minima at low envelope frequencies. The different sensitivity curves found for multiplicative and additive signal combinations suggest that different processes mediated the disparity signal. The data are consistent with a two-channel model of binocular matching, with multiple depth cues represented at single retinal locations. PMID:9802240

Retinal detachment in hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome: Color vision abnormality as the first and predominant manifestation.

PubMed

Morisawa, Hiroyuki; Makino, Shinji; Takahashi, Hironori; Sorita, Mari; Matsubara, Shigeki

2015-11-01

Serous retinal detachment is sometimes caused by hypertensive disorders in pregnancy and its associated conditions, in which the predominant eye symptoms are blurred vision, distorted vision, and reduced visual acuity. To our best knowledge, this is the first report of a puerperal woman with hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome in whom color vision abnormality was the first and predominant manifestation of serous retinal detachment. At 32 weeks of gestation, the 34-year-old Japanese woman underwent cesarean section due to HELLP syndrome. She complained of color vision abnormality on day 1 post-partum and ophthalmological examination revealed serous retinal detachment of both eyes. The visual acuity was preserved. With supportive therapy, her color vision abnormality gradually ameliorated and retinal detachment completely resolved on day 34 post-partum without any sequelae. Obstetricians should be aware that color vision abnormality can be the first and predominant symptom of HELLP-related serous retinal detachment. © 2015 Japan Society of Obstetrics and Gynecology.

An Active System for Visually-Guided Reaching in 3D across Binocular Fixations

PubMed Central

2014-01-01

Based on the importance of relative disparity between objects for accurate hand-eye coordination, this paper presents a biological approach inspired by the cortical neural architecture. So, the motor information is coded in egocentric coordinates obtained from the allocentric representation of the space (in terms of disparity) generated from the egocentric representation of the visual information (image coordinates). In that way, the different aspects of the visuomotor coordination are integrated: an active vision system, composed of two vergent cameras; a module for the 2D binocular disparity estimation based on a local estimation of phase differences performed through a bank of Gabor filters; and a robotic actuator to perform the corresponding tasks (visually-guided reaching). The approach's performance is evaluated through experiments on both simulated and real data. PMID:24672295

[Use of liquid crystal eyeglasses for examination and recovery of binocular vision].

PubMed

Grigorian, A Iu; Avetisov, E S; Kashchenko, T P; Iachmeneva, E I

1999-01-01

A new method for diploptic treatment of strabismus is proposed, based on phase division of visual fields using liquid crystal eyeglasses --computer complex. The method is based on stereovision training (allowing stereothreshold measurements up to 150 ang. sec.). The method was tried in examinations of two groups of children: 10 controls and 74 patients with strabismus. Examinations of normal controls gave new criteria for measuring fusion reserves and stereovisual acuity by the proposed method. The therapeutic method was tried in 2 groups of patients. Time course of visual function improvement was followed up by several criteria: changes in binocular status by the color test and improvement of in-depth and stereoscopic visual acuity. The method is recommended for practice. The authors discuss the problem of small angle strabismus.

Wernicke-Korsakoff syndrome

MedlinePlus

... cause leg tremor Vision changes such as abnormal eye movements (back and forth movements called nystagmus), double vision , ... may show damage to many nerve systems: Abnormal eye movement Decreased or abnormal reflexes Fast pulse (heart rate) ...

Clinically Normal Stereopsis Does Not Ensure a Performance Benefit from Stereoscopic 3D Depth Cues

NASA Astrophysics Data System (ADS)

McIntire, John P.; Havig, Paul R.; Harrington, Lawrence K.; Wright, Steve T.; Watamaniuk, Scott N. J.; Heft, Eric L.

2014-09-01

To investigate the effect of manipulating disparity on task performance and viewing comfort, twelve participants were tested on a virtual object precision placement task while viewing a stereoscopic 3D (S3D) display. All participants had normal or corrected-to-normal visual acuity, passed the Titmus stereovision clinical test, and demonstrated normal binocular function, including phorias and binocular fusion ranges. Each participant completed six experimental sessions with different maximum binocular disparity limits. The results for ten of the twelve participants were generally as expected, demonstrating a large performance advantage when S3D cues were provided. The sessions with the larger disparity limits typically resulted in the best performance, and the sessions with no S3D cues the poorest performance. However, one participant demonstrated poorer performance in sessions with smaller disparity limits but improved performance in sessions with the larger disparity limits. Another participant's performance declined whenever any S3D cues were provided. Follow-up testing suggested that the phenomenon of pseudo-stereoanomaly may account for one viewer's atypical performance, while the phenomenon of stereoanomaly might account for the other. Overall, the results demonstrate that a subset of viewers with clinically normal binocular and stereoscopic vision may have difficulty performing depth-related tasks on S3D displays. The possibility of the vergence-accommodation conflict contributing to individual performance differences is also discussed.

Resultant vertical prism in toric soft contact lenses.

PubMed

Sulley, Anna; Hawke, Ryan; Lorenz, Kathrine Osborn; Toubouti, Youssef; Olivares, Giovanna

2015-08-01

Rotational stability of toric soft contact lenses (TSCLs) is achieved using a range of designs. Designs utilising prism or peripheral ballast may result in residual prism in the optic zone. This study quantifies the vertical prism in the central 6mm present in TSCLs with various stabilisation methods. Vertical prism was computed using published refractive index and vertical thickness changes in the central optic zone on a full lens thickness map. Thickness maps were measured using scanning transmission microscopy. Designs tested were reusable, silicone hydrogel and hydrogel TSCLs: SofLens(®) Toric, PureVision(®)2 for Astigmatism, PureVision(®) Toric, Biofinity(®) Toric, Avaira(®) Toric, clariti(®) toric, AIR OPTIX(®) for ASTIGMATISM and ACUVUE OASYS(®) for ASTIGMATISM; with eight parameter combinations for each lens (-6.00DS to +3.00DS, -1.25DC, 90° and 180° axes). All TSCL designs evaluated had vertical prism in the optic zone except one which had virtually none (0.01Δ). Mean prism ranged from 0.52Δ to 1.15Δ, with three designs having prism that varied with sphere power. Vertical prism in ACUVUE OASYS(®) for ASTIGMATISM was significantly lower than all other TSCLs tested. TSCL designs utilising prism-ballast and peri-ballast for stabilisation have vertical prism in the central optic zone. In monocular astigmats fitted with a TSCL or those wearing a mix of toric designs, vertical prism imbalance could create or exacerbate disturbances in binocular vision function. Practitioners should be aware of this potential effect when selecting which TSCL designs to prescribe, particularly for monocular astigmats with pre-existing binocular vision anomalies, and when managing complaints of asthenopia in monocular astigmats. Copyright © 2015 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Safety and efficacy of a hydrogel inlay with laser in situ keratomileusis to improve vision in myopic presbyopic patients: one-year results.

PubMed

Garza, Enrique Barragan; Chayet, Arturo

2015-02-01

To study the safety and efficacy of implanting a hydrogel corneal inlay (Raindrop Near Vision Inlay) concurrently with performing laser in situ keratomileusis (LASIK) to treat myopic presbyopia and to compare the results with results of the same treatment in emmetropic and hyperopic patients. Two private clinics, Tijuana and Monterrey, Mexico. Prospective nonrandomized clinical trial. Bilateral myopic LASIK was performed and a corneal inlay was concurrently implanted in the nondominant eye under a flap created using a femtosecond laser. Primary safety outcomes were the retention of corrected distance (CDVA) and near (CNVA) visual acuities. Efficacy was evaluated on the basis of uncorrected near (UNVA), intermediate (UIVA), and distance (UDVA) visual acuities. A patient questionnaire was used to assess the preoperative and postoperative incidence of visual symptoms, the ability to perform common tasks with no correction, and patient satisfaction with vision. Thirty eyes were enrolled. At each postoperative visit, the mean CDVA and CNVA were within one half line of preoperative measurements and no eye lost 2 or more lines of CDVA. The mean binocular UDVA, UIVA, and UNVA were better than 20/25 Snellen at all postoperative visits. By 6 months, 93% of patients had a binocular Snellen acuity of 20/25 or better across all visual ranges. According to patient questionnaires, 1 year after surgery, visual symptoms were at preoperative levels, 98% of all visual tasks could be easily performed without correction, and 90% of patients were satisfied or very satisfied with their overall vision. A hydrogel corneal inlay with concurrent LASIK was safe and effective for treating myopic presbyopia. Drs. Garza and Chayet are consultants to and investigators for Revision Optics, Inc. Copyright © 2015. Published by Elsevier Inc.

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

PubMed Central

Nys, Julie; Scheyltjens, Isabelle; Arckens, Lutgarde

2015-01-01

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

Pattern of optometry practice and range of services in India.

PubMed

Thite, Nilesh; Jaggernath, Jyoti; Chinanayi, Farai; Bharadwaj, Shrikant; Kunjeer, Gauri

2015-05-01

This study was conducted to evaluate the range of services provided by optometrists in various modes of optometric practice in India. An online questionnaire was administered to 1674 optometrists to collect information on the range of optometric services offered. Data were analyzed based on variables including sex, educational qualification, and modes of practice. Two-sample Wilcoxon rank sum tests, χ tests, and Fisher exact text were used to conduct inferential statistics. A total of 563 valid and completed survey questionnaires were received from graduates of 41 optometry institutes working across 23 states of India. Of these, 225 (40.0%) were female, 288 (51.2%) had completed postgraduate education, and 340 (60.5%) were involved in more than one mode of practice. The top three modes of practice were hospital-based practice (44.8%), academia (42.8%), and optical retail (33.0%). Of the 441, out of 563 (78.3%) respondents involved in patient care, the majority (98.4%) performed refraction and routine eye examination, 70.3% dispensed contact lenses, and 66.9% practiced optical dispensing. Lower involvement was seen in providing binocular-vision (45.1%) and low-vision services (30.2%). Higher education was associated with advanced level of practice (p < 0.05) except clinical investigative procedures. There was a significant association between postgraduate studies and involvement in academics and research (p < 0.01). Most optometrists are engaged in multiple modes of practice, with optical practice, hospital-based practice, and academia being the leading modes. Optometrists need to be more involved in providing the core optometric services of binocular vision and low vision. Higher education has an impact on the level of optometric practice.

Nonhuman Primate Studies to Advance Vision Science and Prevent Blindness.

PubMed

Mustari, Michael J

2017-12-01

Most primate behavior is dependent on high acuity vision. Optimal visual performance in primates depends heavily upon frontally placed eyes, retinal specializations, and binocular vision. To see an object clearly its image must be placed on or near the fovea of each eye. The oculomotor system is responsible for maintaining precise eye alignment during fixation and generating eye movements to track moving targets. The visual system of nonhuman primates has a similar anatomical organization and functional capability to that of humans. This allows results obtained in nonhuman primates to be applied to humans. The visual and oculomotor systems of primates are immature at birth and sensitive to the quality of binocular visual and eye movement experience during the first months of life. Disruption of postnatal experience can lead to problems in eye alignment (strabismus), amblyopia, unsteady gaze (nystagmus), and defective eye movements. Recent studies in nonhuman primates have begun to discover the neural mechanisms associated with these conditions. In addition, genetic defects that target the retina can lead to blindness. A variety of approaches including gene therapy, stem cell treatment, neuroprosthetics, and optogenetics are currently being used to restore function associated with retinal diseases. Nonhuman primates often provide the best animal model for advancing fundamental knowledge and developing new treatments and cures for blinding diseases. © The Author(s) 2017. Published by Oxford University Press on behalf of the National Academy of Sciences. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Abnormal Transient Pupillary Light Reflex in Individuals with Autism Spectrum Disorders

ERIC Educational Resources Information Center

Fan, Xiaofei; Miles, Judith H.; Takahashi, Nicole; Yao, Gang

2009-01-01

Computerized binocular infrared pupillography was used to measure the transient pupillary light reflex (PLR) in both children with autism spectrum disorders (ASDs) and children with typical development. We found that participants with ASDs showed significantly longer PLR latency, smaller constriction amplitude and lower constriction velocity than…

Refractive error and presbyopia among adults in Fiji.

PubMed

Brian, Garry; Pearce, Matthew G; Ramke, Jacqueline

2011-04-01

To characterize refractive error, presbyopia and their correction among adults aged ≥ 40 years in Fiji, and contribute to a regional overview of these conditions. A population-based cross-sectional survey using multistage cluster random sampling. Presenting distance and near vision were measured and dilated slitlamp examination performed. The survey achieved 73.0% participation (n=1381). Presenting binocular distance vision ≥ 6/18 was achieved by 1223 participants. Another 79 had vision impaired by refractive error. Three of these were blind. At threshold 6/18, 204 participants had refractive error. Among these, 125 had spectacle-corrected presenting vision ≥ 6/18 ("met refractive error need"); 79 presented wearing no (n=74) or under-correcting (n=5) distance spectacles ("unmet refractive error need"). Presenting binocular near vision ≥ N8 was achieved by 833 participants. At threshold N8, 811 participants had presbyopia. Among these, 336 attained N8 with presenting near spectacles ("met presbyopia need"); 475 presented with no (n=402) or under-correcting (n=73) near spectacles ("unmet presbyopia need"). Rural residence was predictive of unmet refractive error (p=0.040) and presbyopia (p=0.016) need. Gender and household income source were not. Ethnicity-gender-age-domicile-adjusted to the Fiji population aged ≥ 40 years, "met refractive error need" was 10.3% (95% confidence interval [CI] 8.7-11.9%), "unmet refractive error need" was 4.8% (95%CI 3.6-5.9%), "refractive error correction coverage" was 68.3% (95%CI 54.4-82.2%),"met presbyopia need" was 24.6% (95%CI 22.4-26.9%), "unmet presbyopia need" was 33.8% (95%CI 31.3-36.3%), and "presbyopia correction coverage" was 42.2% (95%CI 37.6-46.8%). Fiji refraction and dispensing services should encourage uptake by rural dwellers and promote presbyopia correction. Lack of comparable data from neighbouring countries prevents a regional overview.

Vision Examination Protocol for Archery Athletes Along With an Introduction to Sports Vision

PubMed Central

Mohammadi, Seyed Farzad; Aghazade Amiri, Mohammad; Naderifar, Homa; Rakhshi, Elham; Vakilian, Banafsheh; Ashrafi, Elham; Behesht-Nejad, Amir-Houshang

2016-01-01

Introduction: Visual skills are one of the main pillars of intangible faculties of athletes that can influence their performance. Great number of vision tests used to assess the visual skills and it will be irrational to perform all vision tests for every sport. Objectives: The purpose of this protocol article is to present a relatively comprehensive battery of tests and assessments on static and dynamic aspects of sight which seems relevant to sports vision and introduce the most useful ones for archery. Materials and Methods: Through extensive review of the literature, visual skills and respective tests were listed; such as ‘visual acuity, ‘contrast sensitivity’, ‘stereo-acuity’, ‘ocular alignment’, and ‘eye dominance’. Athletes were defined as “elite” and “non-elite” category based on their past performance. Dominance was considered for eye and hand; binocular or monocular aiming was planned to be recorded. Illumination condition was defined as to simulate the real archery condition to the extent possible. The full cycle of examinations and their order for each athlete was sketched (and estimated to take 40 minutes). Protocol was piloted in an eye hospital. Female and male archers aged 18 - 38 years who practiced compound and recurve archery with a history of more than 6 months were included. Conclusions: We managed to select and design a customized examination protocol for archery (a sight-intensive and aiming type of sports), serving skill assessment and research purposes. Our definition for elite and non-elite athletes can help to define sports talent and devise skill development methods as we compare the performance of these two groups. In our pilot, we identified 8 “archery figures” (by hand dominance, eye dominance and binocularity) and highlighted the concept “congruence” (dominant hand and eye in the same side) in archery performance. PMID:27217923

Design and control of active vision based mechanisms for intelligent robots

NASA Technical Reports Server (NTRS)

Wu, Liwei; Marefat, Michael M.

1994-01-01

In this paper, we propose a design of an active vision system for intelligent robot application purposes. The system has the degrees of freedom of pan, tilt, vergence, camera height adjustment, and baseline adjustment with a hierarchical control system structure. Based on this vision system, we discuss two problems involved in the binocular gaze stabilization process: fixation point selection and vergence disparity extraction. A hierarchical approach to determining point of fixation from potential gaze targets using evaluation function representing human visual behavior to outside stimuli is suggested. We also characterize different visual tasks in two cameras for vergence control purposes, and a phase-based method based on binarized images to extract vergence disparity for vergence control is presented. A control algorithm for vergence control is discussed.

Perceived Visual Distortions in Juvenile Amblyopes During/Following Routine Amblyopia Treatment.

PubMed

Piano, Marianne E F; Bex, Peter J; Simmers, Anita J

2016-08-01

To establish the point prevalence of perceived visual distortions (PVDs) in amblyopic children; the association between severity of PVDs and clinical parameters of amblyopia; and the relationship between PVDs and amblyopia treatment outcomes. Perceived visual distortions were measured using a 16-point dichoptic alignment paradigm in 148 visually normal children (aged, 9.18 ± 2.51 years), and 82 amblyopic children (aged, 6.33 ± 1.48 years) receiving or following amblyopia treatment. Global distortion (GD; vector sum of mean-centered individual alignment error between physical and perceived target location) and Global uncertainty (GU; SD of GD over two experiment runs) were compared to age-matched control data, and correlated against clinical parameters of amblyopia (type, monocular visual acuity, pretreatment interocular acuity difference, refractive error, age at diagnosis, motor fusion, stereopsis, near angle of deviation) and amblyopia treatment outcomes (refractive adaption duration, treatment duration, occlusion dosage, posttreatment interocular acuity difference, number of lines improvement). Point prevalence of PVDs in amblyopes was 56.1%. Strabismic amblyopes experienced more severe distortions than anisometropic or microtropic amblyopes (GD Kruskal Wallis H = 16.89, P < 0.001; GU Kruskal Wallis H = 15.31, P < 0.001). Perceived visual distortions severity moderately correlated with the strength of binocular function, (e.g., log stereoacuity [GD rho = 0.419, P < 0.001; GU rho = 0.384, P < 0.001)], and strongly with near angle of deviation (GD rho = 0.578, P < 0.001; GU rho = 0.384, P < 0.001). There was no relationship between severity of PVDs and amblyopia treatment outcomes, or the amblyopic visual acuity deficit. Perceived visual distortions persisted in more than one-half of treated amblyopic cases whose treatment was deemed successful. Perceived visual distortions are common symptoms of amblyopia and are correlated with binocular (stereoacuity, angle of deviation), but not monocular (visual acuity) clinical outcomes. This adds to evidence demonstrating the role of decorrelated binocular single vision in many aspects of amblyopia, and emphasizes the importance of restoring and improving binocular single vision in amblyopic individuals.

Use of a Binocular Optical Coherence Tomography System to Evaluate Strabismus in Primary Position.

PubMed

Chopra, Reena; Mulholland, Pádraig J; Tailor, Vijay K; Anderson, Roger S; Keane, Pearse A

2018-05-31

Current clinical methods for assessing strabismus can be prone to error. Binocular optical coherence tomography (OCT) has the potential to assess and quantify strabismus objectively and in an automated manner. To evaluate the use of a binocular OCT prototype to assess the presence and size of strabismus. Fifteen participants with strabismus were recruited in 2016 as part of the EASE study from Moorfields Eye Hospital National Health Service Foundation Trust, London, England, and 15 healthy volunteers underwent automated anterior segment imaging using the binocular OCT prototype. All participants had an orthoptic assessment, including alternating prism cover test (APCT), before undergoing imaging. Simultaneously acquired pairs of OCT images, captured with 1 eye fixating, were analyzed using ImageJ (National Institutes of Health) to assess the presence and angle of strabismus. The direction and size of strabismus measured using binocular OCT was compared with that found using APCT. The median age for participants with strabismus was 55 years (interquartile range [IQR], 33-66.5 years) and for the healthy group, 50 years (IQR, 41-59 years); 15 participants (50%) were women, and 25 participants (83.3%) were white. The median magnitude of horizontal deviation was 20∆ (IQR, 13-35∆) and for vertical deviation, 3∆ (IQR, 0-5∆). Binocular OCT imaging correctly revealed the type and direction of the deviation in all 15 participants with strabismus, including horizontal and vertical deviations. The APCT and OCT measurements were strongly correlated for the horizontal (Pearson r = 0.85; 95% CI, 0.60-0.95; P < .001) and vertical (r = 0.89; 95% CI, 0.69-0.96; P < .001) deviations. In the healthy cohort, 9 of 15 participants (60%) had a latent horizontal deviation on APCT results (median magnitude 2∆, range 2-4∆). Six (40%) had orthophoria. Horizontal deviations were observed on OCT imaging results in 12 of the 15 participants (80%), and a vertical deviation was visible in 1 participant (6.7%). These findings suggest that binocular anterior segment OCT imaging can provide clinicians with a precise measurement of strabismus. The prototype can potentially incorporate several binocular vision tests that will provide quantitative data for the assessment, diagnosis, and monitoring of ocular misalignments.

Binocular combination of luminance profiles

PubMed Central

Ding, Jian; Levi, Dennis M.

2017-01-01

We develop and test a new two-dimensional model for binocular combination of the two eyes' luminance profiles. For first-order stimuli, the model assumes that one eye's luminance profile first goes through a luminance compressor, receives gain-control and gain-enhancement from the other eye, and then linearly combines the other eye's output profile. For second-order stimuli, rectification is added in the signal path of the model before the binocular combination site. Both the total contrast and luminance energies, weighted sums over both the space and spatial-frequency domains, were used in the interocular gain-control, while only the total contrast energy was used in the interocular gain-enhancement. To challenge the model, we performed a binocular brightness matching experiment over a large range of background and target luminances. The target stimulus was a dichoptic disc with a sharp edge that has an increment or decrement luminance from its background. The disk's interocular luminance ratio varied from trial to trial. To refine the model we tested three luminance compressors, five nested binocular combination models (including the Ding–Sperling and the DSKL models), and examined the presence or absence of total luminance energy in the model. We found that (1) installing a luminance compressor, either a logarithmic luminance function or luminance gain-control, (2) including both contrast and luminance energies, and (3) adding interocular gain-enhancement (the DSKL model) to a combined model significantly improved its performance. The combined model provides a systematic account of binocular luminance summation over a large range of luminance input levels. It gives a unified explanation of Fechner's paradox observed on a dark background, and a winner-take-all phenomenon observed on a light background. To further test the model, we conducted two additional experiments: luminance summation of discs with asymmetric contour information (Experiment 2), similar to Levelt (1965) and binocular combination of second-order contrast-modulated gratings (Experiment 3). We used the model obtained in Experiment 1 to predict the results of Experiments 2 and 3 and the results of our previous studies. Model simulations further refined the contrast space weight and contrast sensitivity functions that are installed in the model, and provide a reasonable account for rebalancing of imbalanced binocular vision by reducing the mean luminance in the dominant eye. PMID:29098293

Innovative Inspection Techniques

DTIC Science & Technology

1993-01-01

beam and holding the binoculars at the same time. Night-vision glasses with magnification were mentioned but no inspectors we met had direct...angles for an actual lightbulb , the mean spherical candlepower is used as a measure of light output. The MSCP is measured using an integrating...needs special glasses to separate the alternating images, one image for the right and one for the left eye. StereoGraphics Corporation has developed a

Topography from shading and stereo

NASA Technical Reports Server (NTRS)

Horn, Berthold K. P.

1994-01-01

Methods exploiting photometric information in images that have been developed in machine vision can be applied to planetary imagery. Integrating shape from shading, binocular stereo, and photometric stereo yields a robust system for recovering detailed surface shape and surface reflectance information. Such a system is useful in producing quantitative information from the vast volume of imagery being received, as well as in helping visualize the underlying surface.

University NanoSat Program: AggieSat3

DTIC Science & Technology

2009-06-01

commercially available product for stereo machine vision developed by Point Grey Research. The current binocular BumbleBee2® system incorporates two...and Fellow of the American Society of Mechanical Engineers (ASME) in 1997. She was awarded the 2007 J. Leland "Lee" Atwood Award from the ASEE...AggieSat2 satellite programs. Additional experience gained in the area of drawing standards, machining capabilities, solid modeling, safety

How the venetian blind percept emerges from the laminar cortical dynamics of 3D vision

PubMed Central

Cao, Yongqiang; Grossberg, Stephen

2014-01-01

The 3D LAMINART model of 3D vision and figure-ground perception is used to explain and simulate a key example of the Venetian blind effect and to show how it is related to other well-known perceptual phenomena such as Panum's limiting case. The model proposes how lateral geniculate nucleus (LGN) and hierarchically organized laminar circuits in cortical areas V1, V2, and V4 interact to control processes of 3D boundary formation and surface filling-in that simulate many properties of 3D vision percepts, notably consciously seen surface percepts, which are predicted to arise when filled-in surface representations are integrated into surface-shroud resonances between visual and parietal cortex. Interactions between layers 4, 3B, and 2/3 in V1 and V2 carry out stereopsis and 3D boundary formation. Both binocular and monocular information combine to form 3D boundary and surface representations. Surface contour surface-to-boundary feedback from V2 thin stripes to V2 pale stripes combines computationally complementary boundary and surface formation properties, leading to a single consistent percept, while also eliminating redundant 3D boundaries, and triggering figure-ground perception. False binocular boundary matches are eliminated by Gestalt grouping properties during boundary formation. In particular, a disparity filter, which helps to solve the Correspondence Problem by eliminating false matches, is predicted to be realized as part of the boundary grouping process in layer 2/3 of cortical area V2. The model has been used to simulate the consciously seen 3D surface percepts in 18 psychophysical experiments. These percepts include the Venetian blind effect, Panum's limiting case, contrast variations of dichoptic masking and the correspondence problem, the effect of interocular contrast differences on stereoacuity, stereopsis with polarity-reversed stereograms, da Vinci stereopsis, and perceptual closure. These model mechanisms have also simulated properties of 3D neon color spreading, binocular rivalry, 3D Necker cube, and many examples of 3D figure-ground separation. PMID:25309467

How the venetian blind percept emerges from the laminar cortical dynamics of 3D vision.

PubMed

Cao, Yongqiang; Grossberg, Stephen

2014-01-01

The 3D LAMINART model of 3D vision and figure-ground perception is used to explain and simulate a key example of the Venetian blind effect and to show how it is related to other well-known perceptual phenomena such as Panum's limiting case. The model proposes how lateral geniculate nucleus (LGN) and hierarchically organized laminar circuits in cortical areas V1, V2, and V4 interact to control processes of 3D boundary formation and surface filling-in that simulate many properties of 3D vision percepts, notably consciously seen surface percepts, which are predicted to arise when filled-in surface representations are integrated into surface-shroud resonances between visual and parietal cortex. Interactions between layers 4, 3B, and 2/3 in V1 and V2 carry out stereopsis and 3D boundary formation. Both binocular and monocular information combine to form 3D boundary and surface representations. Surface contour surface-to-boundary feedback from V2 thin stripes to V2 pale stripes combines computationally complementary boundary and surface formation properties, leading to a single consistent percept, while also eliminating redundant 3D boundaries, and triggering figure-ground perception. False binocular boundary matches are eliminated by Gestalt grouping properties during boundary formation. In particular, a disparity filter, which helps to solve the Correspondence Problem by eliminating false matches, is predicted to be realized as part of the boundary grouping process in layer 2/3 of cortical area V2. The model has been used to simulate the consciously seen 3D surface percepts in 18 psychophysical experiments. These percepts include the Venetian blind effect, Panum's limiting case, contrast variations of dichoptic masking and the correspondence problem, the effect of interocular contrast differences on stereoacuity, stereopsis with polarity-reversed stereograms, da Vinci stereopsis, and perceptual closure. These model mechanisms have also simulated properties of 3D neon color spreading, binocular rivalry, 3D Necker cube, and many examples of 3D figure-ground separation.

A Method of Three-Dimensional Recording of Mandibular Movement Based on Two-Dimensional Image Feature Extraction

PubMed Central

Li, Zhongke; Yang, Huifang; Lü, Peijun; Wang, Yong; Sun, Yuchun

2015-01-01

Background and Objective To develop a real-time recording system based on computer binocular vision and two-dimensional image feature extraction to accurately record mandibular movement in three dimensions. Methods A computer-based binocular vision device with two digital cameras was used in conjunction with a fixed head retention bracket to track occlusal movement. Software was developed for extracting target spatial coordinates in real time based on two-dimensional image feature recognition. A plaster model of a subject’s upper and lower dentition were made using conventional methods. A mandibular occlusal splint was made on the plaster model, and then the occlusal surface was removed. Temporal denture base resin was used to make a 3-cm handle extending outside the mouth connecting the anterior labial surface of the occlusal splint with a detection target with intersecting lines designed for spatial coordinate extraction. The subject's head was firmly fixed in place, and the occlusal splint was fully seated on the mandibular dentition. The subject was then asked to make various mouth movements while the mandibular movement target locus point set was recorded. Comparisons between the coordinate values and the actual values of the 30 intersections on the detection target were then analyzed using paired t-tests. Results The three-dimensional trajectory curve shapes of the mandibular movements were consistent with the respective subject movements. Mean XYZ coordinate values and paired t-test results were as follows: X axis: -0.0037 ± 0.02953, P = 0.502; Y axis: 0.0037 ± 0.05242, P = 0.704; and Z axis: 0.0007 ± 0.06040, P = 0.952. The t-test result showed that the coordinate values of the 30 cross points were considered statistically no significant. (P<0.05) Conclusions Use of a real-time recording system of three-dimensional mandibular movement based on computer binocular vision and two-dimensional image feature recognition technology produced a recording accuracy of approximately ± 0.1 mm, and is therefore suitable for clinical application. Certainly, further research is necessary to confirm the clinical applications of the method. PMID:26375800

The Mark 3 Haploscope

NASA Technical Reports Server (NTRS)

Decker, T. A.; Williams, R. E.; Kuether, C. L.; Logar, N. D.; Wyman-Cornsweet, D.

1975-01-01

A computer-operated binocular vision testing device was developed as one part of a system designed for NASA to evaluate the visual function of astronauts during spaceflight. This particular device, called the Mark 3 Haploscope, employs semi-automated psychophysical test procedures to measure visual acuity, stereopsis, phoria, fixation disparity, refractive state and accommodation/convergence relationships. Test procedures are self-administered and can be used repeatedly without subject memorization. The Haploscope was designed as one module of the complete NASA Vision Testing System. However, it is capable of stand-alone operation. Moreover, the compactness and portability of the Haploscope make possible its use in a broad variety of testing environments.

Covert spatial attention is functionally intact in amblyopic human adults

PubMed Central

Roberts, Mariel; Cymerman, Rachel; Smith, R. Theodore; Kiorpes, Lynne; Carrasco, Marisa

2016-01-01

Certain abnormalities in behavioral performance and neural signaling have been attributed to a deficit of visual attention in amblyopia, a neurodevelopmental disorder characterized by a diverse array of visual deficits following abnormal binocular childhood experience. Critically, most have inferred attention's role in their task without explicitly manipulating and measuring its effects against a baseline condition. Here, we directly investigate whether human amblyopic adults benefit from covert spatial attention—the selective processing of visual information in the absence of eye movements—to the same degree as neurotypical observers. We manipulated both involuntary (Experiment 1) and voluntary (Experiment 2) attention during an orientation discrimination task for which the effects of covert spatial attention have been well established in neurotypical and special populations. In both experiments, attention significantly improved accuracy and decreased reaction times to a similar extent (a) between the eyes of the amblyopic adults and (b) between the amblyopes and their age- and gender-matched controls. Moreover, deployment of voluntary attention away from the target location significantly impaired task performance (Experiment 2). The magnitudes of the involuntary and voluntary attention benefits did not correlate with amblyopic depth or severity. Both groups of observers showed canonical performance fields (better performance along the horizontal than vertical meridian and at the lower than upper vertical meridian) and similar effects of attention across locations. Despite their characteristic low-level vision impairments, covert spatial attention remains functionally intact in human amblyopic adults. PMID:28033433

Infant Face Preferences after Binocular Visual Deprivation

ERIC Educational Resources Information Center

Mondloch, Catherine J.; Lewis, Terri L.; Levin, Alex V.; Maurer, Daphne

2013-01-01

Early visual deprivation impairs some, but not all, aspects of face perception. We investigated the possible developmental roots of later abnormalities by using a face detection task to test infants treated for bilateral congenital cataract within 1 hour of their first focused visual input. The seven patients were between 5 and 12 weeks old…

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

PubMed

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

2016-12-06

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.

The role of sensory ocular dominance on through-focus visual performance in monovision presbyopia corrections

PubMed Central

Zheleznyak, Len; Alarcon, Aixa; Dieter, Kevin C.; Tadin, Duje; Yoon, Geunyoung

2015-01-01

Monovision presbyopia interventions exploit the binocular nature of the visual system by independently manipulating the optical properties of the two eyes. It is unclear, however, how individual variations in ocular dominance affect visual function in monovision corrections. Here, we examined the impact of sensory ocular dominance on visual performance in both traditional and modified monovision presbyopic corrections. We recently developed a binocular adaptive optics vision simulator to correct subjects' native aberrations and induce either modified monovision (1.5 D anisometropia, spherical aberration of +0.1 and −0.4 μm in distance and near eyes, respectively, over 4 mm pupils) or traditional monovision (1.5 D anisometropia). To quantify both the sign and the degree of ocular dominance, we utilized binocular rivalry to estimate stimulus contrast ratios that yield balanced dominance durations for the two eyes. Through-focus visual acuity and contrast sensitivity were measured under two conditions: (a) assigning dominant and nondominant eye to distance and near, respectively, and (b) vice versa. The results revealed that through-focus visual acuity was unaffected by ocular dominance. Contrast sensitivity, however, was significantly improved when the dominant eye coincided with superior optical quality. We hypothesize that a potential mechanism behind this observation is an interaction between ocular dominance and binocular contrast summation, and thus, assignment of the dominant eye to distance or near may be an important factor to optimize contrast threshold performance at different object distances in both modified and traditional monovision. PMID:26024464

Are visual peripheries forever young?

PubMed

Burnat, Kalina

2015-01-01

The paper presents a concept of lifelong plasticity of peripheral vision. Central vision processing is accepted as critical and irreplaceable for normal perception in humans. While peripheral processing chiefly carries information about motion stimuli features and redirects foveal attention to new objects, it can also take over functions typical for central vision. Here I review the data showing the plasticity of peripheral vision found in functional, developmental, and comparative studies. Even though it is well established that afferent projections from central and peripheral retinal regions are not established simultaneously during early postnatal life, central vision is commonly used as a general model of development of the visual system. Based on clinical studies and visually deprived animal models, I describe how central and peripheral visual field representations separately rely on early visual experience. Peripheral visual processing (motion) is more affected by binocular visual deprivation than central visual processing (spatial resolution). In addition, our own experimental findings show the possible recruitment of coarse peripheral vision for fine spatial analysis. Accordingly, I hypothesize that the balance between central and peripheral visual processing, established in the course of development, is susceptible to plastic adaptations during the entire life span, with peripheral vision capable of taking over central processing.

Vision development over an extended follow-up period in babies after successful vitrectomy for stage 4b retinopathy of prematurity.

PubMed

Gadkari, Salil; Kamdar, Rushita; Kulkarni, Sucheta; Deshpande, Madan; Taras, Sudhir

2015-05-01

To demonstrate improvement in the vision of babies after successful vitrectomy for stage 4b retinopathy of prematurity (ROP) over an extended period of time. This was an observational prospective case series. Eight babies who had undergone successful vitrectomy in either their only seeing eye (or both eyes) with stage 4b ROP were followed up post-operatively for a period of 80 weeks or more. Vision with Teller acuity chart, refraction, binocular indirect ophthalmoscopy, and documentation with RetCam was done at each visit. Vision of the (only/better) seeing operated eye with corrective glasses was graded for the purpose of statistical evaluation. Paired t test was performed to compare the vision prior to 30 weeks and at or after 80 weeks. Statistically significant improvement in vision was noted at or after 80 weeks as compared to the vision recorded before 30 weeks (p = 0.0062). Unlike in adult intraocular surgeries where stable visual acuity is reached well before 30 weeks, continuing improvement at 80 weeks and beyond is noted. Gradual restoration of the retinal architecture and plasticity of the infant's developing brain are thought to be responsible.

Visual Impairment Screening at the Geriatric Frailty Clinic for Assessment of Frailty and Prevention of Disability at the Gérontopôle.

PubMed

Soler, V; Sourdet, S; Balardy, L; Abellan van Kan, G; Brechemier, D; Rougé-Bugat, M E; Tavassoli, N; Cassagne, M; Malecaze, F; Nourhashémi, F; Vellas, B

2016-01-01

To evaluate visual performance and factors associated with abnormal vision in patients screened for frailty at the Geriatric Frailty Clinic (GFC) for Assessment of Frailty and Prevention of Disability at Toulouse University Hospital. Retrospective, observational cross-sectional, single-centre study. Institutional practice. Patients were screened for frailty during a single-day hospital stay between October 2011 and October 2014 (n = 1648). Collected medical records included sociodemographic data (including living environment and educational level), anthropometric data, and clinical data. The general evaluation included the patient's functional status using the Activities of Daily Living (ADL) scale and the Instrumental Activity of Daily Living (IADL) scale, the Mini-Mental State Examination (MMSE) for cognition testing, and the Short Physical Performance Battery (SPPB) for physical performance. We also examined Body Mass Index (BMI), the Mini-Nutritional Assessment (MNA), and the Hearing Handicap Inventory for the Elderly Screening (HHIE-S) tool. The ophthalmologic evaluation included assessing visual acuity using the Snellen decimal chart for distant vision, and the Parinaud chart for near vision. Patients were divided into groups based on normal distant/near vision (NDV and NNV groups) and abnormal distant/near vision (ADV and ANV groups). Abnormal distant or near vision was defined as visual acuity inferior to 20/40 or superior to a Parinaud score of 2, in at least one eye. Associations with frailty-associated factors were evaluated in both groups. The mean age of the population was 82.6 ± 6.2 years. The gender distribution was 1,061 females (64.4%) and 587 males (35.6%). According to the Fried criteria, 619 patients (41.1%) were pre-frail and 771 (51.1%) were frail. Distant and near vision data were available for 1425 and 1426 patients, respectively. Distant vision was abnormal for 437 patients (30.7%). Near vision was abnormal for 199 patients (14%). Multiple regression analysis showed that abnormal distant vision as well as abnormal near vision were independently associated with greater age (P < 0.01), lower educational level (P < 0.05), lower performance on the MMSE (P < 0.001), and lower autonomy (P < 0.02), after controlling for age, gender, educational level, Fried criteria, and MMSE score. The high prevalence of visual disorders observed in the study population and their association with lower autonomy and cognitive impairment emphasises the need for systematic screening of visual impairments in the elderly. Frailty was not found to be independently associated with abnormal vision.

Accuracy aspects of stereo side-looking radar. [analysis of its visual perception and binocular vision

NASA Technical Reports Server (NTRS)

Leberl, F. W.

1979-01-01

The geometry of the radar stereo model and factors affecting visual radar stereo perception are reviewed. Limits to the vertical exaggeration factor of stereo radar are defined. Radar stereo model accuracies are analyzed with respect to coordinate errors caused by errors of radar sensor position and of range, and with respect to errors of coordinate differences, i.e., cross-track distances and height differences.

Rapid Nonconjugate Adaptation of Vertical Voluntary Pursuit Eye Movements

DTIC Science & Technology

1991-01-01

experiment, phoria adaptation was differentially 8 stimulated at two discrete gaze positions. In a series of experimental sessions, stimulus disparity...P (Ed.), Wenner-Gren Center International Symposium Series , Pergamon: Oxford Vol 24: pages 47-61 Ogle KN (1950), Researches in Binocular Vision, WB...data were saved to an individual file for later off-line analysis. Saccades were stimulated every four to five seconds. The data trial series ended

Animal Preparations to Assess Neurophysiological Effects of Bio-Dynamic Environments.

DTIC Science & Technology

1980-07-17

deprivation in preventing the acquisition of visually-guided behaviors. The next study examined acquisition of visually-guided behaviors in six animals...Maffei, L. and Bisti, S. Binocular interaction in strabismic kittens deprived of vision. Science, 191, 579-580, 1976. Matin, L. A possible hybrid...function in cat visual cortex following prolonged deprivation . Exp. Brain Res., 25 (1976) 139-156. Hein, A. Visually controlled components of movement

The Presentation of Different Visual Information to Each Eye

DTIC Science & Technology

1979-07-12

RETICLE 500 MS 100 MS 50 MS 0 MS SIMULT. TARGET EYE L R L. R L R L R L R L R TREATMENT* 1 2 3 4 5 6 7 8 9 10 111 12 SUBJECT 1 (10 TRIALS/TR EAT MENT...Researches in binocular vision. New York: Hafner, 1963. 7. Panum, P. L., Untersuchungen Uber das sehen mit zwei augen. Kiel, 1858. Cited in Ogle (1963), page

Advances in stereomicroscopy

NASA Astrophysics Data System (ADS)

Schnitzler, H.; Zimmer, Klaus-Peter

2008-09-01

Similar to human's binocular vision, stereomicroscopes are comprised of two optical paths under a convergence angle providing a full perspective insight into the world's microstructure. The numerical aperture of stereomicroscopes has continuously increased over the years, reaching the point where the lenses of left and right perspective paths touched each other. This constraint appeared as an upper limit for the resolution of stereomicroscopes, as the resolution of a stereomicroscope was deduced from the numerical apertures of the two equally sized perspective channels. We present the optical design and advances in resolution of the world's first asymmetrical stereomicroscope, which is a technological breakthrough in many aspects of stereomicroscopes. This unique approach uses a large numerical aperture and thus an, so far, unachievable high lateral resolution in the one path, and a small aperture in the other path, which provides a high depth of field ("Fusion Optics"). This new concept is a technical challenge for the optical design of the zoom system as well as for the common main objectives. Furthermore, the new concept makes use of the particular way in which perspective information by binocular vision is formed in the human's brain. In conjunction with a research project at the University of Zurich, Leica Microsystems consolidated the functionality of this concept in to a new generation of stereomicroscopes.

Dimensional coordinate measurements: application in characterizing cervical spine motion

NASA Astrophysics Data System (ADS)

Zheng, Weilong; Li, Linan; Wang, Shibin; Wang, Zhiyong; Shi, Nianke; Xue, Yuan

2014-06-01

Cervical spine as a complicated part in the human body, the form of its movement is diverse. The movements of the segments of vertebrae are three-dimensional, and it is reflected in the changes of the angle between two joint and the displacement in different directions. Under normal conditions, cervical can flex, extend, lateral flex and rotate. For there is no relative motion between measuring marks fixed on one segment of cervical vertebra, the cervical vertebrae with three marked points can be seen as a body. Body's motion in space can be decomposed into translational movement and rotational movement around a base point .This study concerns the calculation of dimensional coordinate of the marked points pasted to the human body's cervical spine by an optical method. Afterward, these measures will allow the calculation of motion parameters for every spine segment. For this study, we choose a three-dimensional measurement method based on binocular stereo vision. The object with marked points is placed in front of the CCD camera. Through each shot, we will get there two parallax images taken from different cameras. According to the principle of binocular vision we can be realized three-dimensional measurements. Cameras are erected parallelly. This paper describes the layout of experimental system and a mathematical model to get the coordinates.

Pediatric vision screening using binocular retinal birefringencr scanning

NASA Astrophysics Data System (ADS)

Nassif, Deborah S.; Gramatikov, Boris; Guyton, David L.; Hunter, David G.

2003-07-01

Amblyopia, a leading cause of vision loss in childhood, is responsive to treatment if detected early in life. Risk factors for amblyopia, such as refractive error and strabismus, may be difficult to identify clinically in young children. Our laboratory has developed retinal birefringence scanning (RBS), in which a small spot of polarized light is scanned in a circle on the retina, and the returning light is measured for changes in polarization caused by the pattern of birefringent fibers that comprise the fovea. Binocular RBS (BRBS) detects the fixation of both eyes simultaneously and thus screens for strabismus, one of the risk factors of amblyopia. We have also developed a technique to automatically detect when the eye is in focus without measuring refractive error. This focus detection system utilizes a bull's eye photodetector optically conjugate to a point fixation source. Reflected light is focused back to the point source by the optical system of the eye, and if the subject focuses on the fixation source, the returning light will be focused on the detector. We have constructed a hand-held prototype combining BRBS and focus detection measurements in one quick (< 0.5 second) and accurate (theoretically detecting +/-1 of misalignment) measurement. This approach has the potential to reliably identify children at risk for amblyopia.

The research on calibration methods of dual-CCD laser three-dimensional human face scanning system

NASA Astrophysics Data System (ADS)

Wang, Jinjiang; Chang, Tianyu; Ge, Baozhen; Tian, Qingguo; Yang, Fengting; Shi, Shendong

2013-09-01

In this paper, on the basis of considering the performance advantages of two-step method, we combines the stereo matching of binocular stereo vision with active laser scanning to calibrate the system. Above all, we select a reference camera coordinate system as the world coordinate system and unity the coordinates of two CCD cameras. And then obtain the new perspective projection matrix (PPM) of each camera after the epipolar rectification. By those, the corresponding epipolar equation of two cameras can be defined. So by utilizing the trigonometric parallax method, we can measure the space point position after distortion correction and achieve stereo matching calibration between two image points. Experiments verify that this method can improve accuracy and system stability is guaranteed. The stereo matching calibration has a simple process with low-cost, and simplifies regular maintenance work. It can acquire 3D coordinates only by planar checkerboard calibration without the need of designing specific standard target or using electronic theodolite. It is found that during the experiment two-step calibration error and lens distortion lead to the stratification of point cloud data. The proposed calibration method which combining active line laser scanning and binocular stereo vision has the both advantages of them. It has more flexible applicability. Theory analysis and experiment shows the method is reasonable.

Photogrammetry research for FAST eleven-meter reflector panel surface shape measurement

NASA Astrophysics Data System (ADS)

Zhou, Rongwei; Zhu, Lichun; Li, Weimin; Hu, Jingwen; Zhai, Xuebing

2010-10-01

In order to design and manufacture the Five-hundred-meter Aperture Spherical Radio Telescope (FAST) active reflector measuring equipment, measurement on each reflector panel surface shape was presented, static measurement of the whole neutral spherical network of nodes was performed, real-time dynamic measurement at the cable network dynamic deformation was undertaken. In the implementation process of the FAST, reflector panel surface shape detection was completed before eleven-meter reflector panel installation. Binocular vision system was constructed based on the method of binocular stereo vision in machine vision, eleven-meter reflector panel surface shape was measured with photogrammetry method. Cameras were calibrated with the feature points. Under the linearity camera model, the lighting spot array was used as calibration standard pattern, and the intrinsic and extrinsic parameters were acquired. The images were collected for digital image processing and analyzing with two cameras, feature points were extracted with the detection algorithm of characteristic points, and those characteristic points were matched based on epipolar constraint method. Three-dimensional reconstruction coordinates of feature points were analyzed and reflective panel surface shape structure was established by curve and surface fitting method. The error of reflector panel surface shape was calculated to realize automatic measurement on reflector panel surface shape. The results show that unit reflector panel surface inspection accuracy was 2.30mm, within the standard deviation error of 5.00mm. Compared with the requirement of reflector panel machining precision, photogrammetry has fine precision and operation feasibility on eleven-meter reflector panel surface shape measurement for FAST.

Eye muscle prosthesis.

PubMed

Scott, A B; Miller, J M; Collins, C C

1992-01-01

We inserted a silicone rubber elastic band along the course of a paralyzed lateral rectus and of a paralyzed superior oblique to restore alignment and to provide a spring against which the antagonist could pull. The lateral rectus band has been in place for 7 years. It provides alignment and a field of single binocular vision of 20 degrees. The superior oblique band has been in place for 17 months. It provides alignment and single vision over 30 degrees from the primary position except for a restriction in upgaze-adduction to 25 degrees (Brown syndrome) and in downgaze-adduction to 20 degrees. Such engineered elastic bands are a useful addition to current surgical techniques for management of cases of paralysis and restriction.

Laser projection positioning of spatial contour curves via a galvanometric scanner

NASA Astrophysics Data System (ADS)

Tu, Junchao; Zhang, Liyan

2018-04-01

The technology of laser projection positioning is widely applied in advanced manufacturing fields (e.g. composite plying, parts location and installation). In order to use it better, a laser projection positioning (LPP) system is designed and implemented. Firstly, the LPP system is built by a laser galvanometric scanning (LGS) system and a binocular vision system. Applying Single-hidden Layer Feed-forward Neural Network (SLFN), the system model is constructed next. Secondly, the LGS system and the binocular system, which are respectively independent, are integrated through a datadriven calibration method based on extreme learning machine (ELM) algorithm. Finally, a projection positioning method is proposed within the framework of the calibrated SLFN system model. A well-designed experiment is conducted to verify the viability and effectiveness of the proposed system. In addition, the accuracy of projection positioning are evaluated to show that the LPP system can achieves the good localization effect.

Interocular suppression in normal and amblyopic vision: spatio-temporal properties.

PubMed

Huang, Pi-Chun; Baker, Daniel H; Hess, Robert F

2012-10-31

We measured the properties of interocular suppression in strabismic amblyopes and compared these to dichoptic masking in binocularly normal observers. We used a dichoptic version of the well-established probed-sinewave paradigm that measured sensitivity to a brief target stimulus (one of four letters to be discriminated) in the amblyopic eye at different times relative to a suppression-inducing mask in the fixing eye. This was done using both sinusoidal steady state and transient approaches. The suppression-inducing masks were either modulations of luminance or contrast (full field, just overlaying the target, or just surrounding the target). Our results were interpreted using a descriptive model that included contrast gain control and spatio-temporal filtering prior to excitatory binocular combination. The suppression we measured, other than in magnitude, was not fundamentally different from normal dichoptic masking: lowpass spatio-temporal properties with similar contributions from both surround and overlay suppression.

Effects of Form Perception and Meaning on the Visual Evoked Potential with Author’s Update

DTIC Science & Technology

2009-09-01

2001. Controlling binocular rivalry. Vision Research. 41: 2943-2950. Freud , S. 1995. The Basic Writings of Sigmund Freud (Psychopathology of... Freud , S. 1990. The Ego and the Id (The Standard Edition of the Complete Psychological Works of Sigmund Freud ). P. Gay, Introduction. New York...1935), and psychoanalytic talk therapies associated with S. Freud (1995, 1990), gave results that were less accessible to scientific method. In short

Convergence Insufficiency Symptom Survey Scores for Reading Versus Other Near Visual Activities in School-Age Children.

PubMed

Clark, Tiana Y; Clark, Robert A

2015-11-01

To measure the difference in Convergence Insufficiency Symptom Survey scores for reading vs favorite near visual activities. Comparative validity analysis of diagnostic tools. At a single clinical private practice, 100 children aged 9-18 with normal binocular vision were recruited to receive either the original survey emphasizing reading or a modified survey replacing "reading" with their favorite near activity. Average survey scores and subscores for questions emphasizing fatigue, discomfort, impaired vision, and cognitive performance were compared using t tests, while responses to individual questions were compared using Mann-Whitney U tests. The average reading survey score was significantly greater than the favorite near activity survey score (14.1 ± 11.5 vs 6.7 ± 5.8, P = .0001). The largest difference resulted from questions emphasizing cognitive performance (subscore 5.8 ± 4.3 vs 2.0 ± 2.1, P = .0000002), although significant differences were also found for fatigue (5.4 ± 3.8 vs 3.0 ± 2.7, P = .0003), discomfort (3.9 ± 4.6 vs 1.8 ± 2.2, P = .004), and impaired vision (3.2 ± 3.9 vs 1.8 ± 2.2, P = .02). Significant differences were found for 7 survey questions, with higher symptom scores for the reading survey in every case. Using survey scores ≥16 to diagnose convergence insufficiency, significantly more children taking the reading survey would have been diagnosed with convergence insufficiency than children taking the favorite near activity survey (19 of 50 [38%] vs 5 of 50 [10%], P = .001). By emphasizing reading, the Convergence Insufficiency Symptom Survey score significantly overestimates near visual symptoms in children with normal binocular vision compared with symptoms caused by preferred near activities that require similar amplitudes of accommodation and convergence. Copyright © 2015 Elsevier Inc. All rights reserved.

Age-related prevalence and met need for correctable and uncorrectable near vision impairment in a multi-country study.

PubMed

He, Mingguang; Abdou, Amza; Ellwein, Leon B; Naidoo, Kovin S; Sapkota, Yuddha D; Thulasiraj, R D; Varma, Rohit; Zhao, Jialiang; Kocur, Ivo; Congdon, Nathan G

2014-01-01

To estimate the prevalence, potential determinants, and proportion of met need for near vision impairment (NVI) correctable with refraction approximately 2 years after initial examination of a multi-country cohort. Population-based, prospective cohort study. People aged ≥35 years examined at baseline in semi-rural (Shunyi) and urban (Guangzhou) sites in China; rural sites in Nepal (Kaski), India (Madurai), and Niger (Dosso); a semi-urban site (Durban) in South Africa; and an urban site (Los Angeles) in the United States. Near visual acuity (NVA) with and without current near correction was measured at 40 cm using a logarithm of the minimum angle of resolution near vision tumbling E chart. Participants with uncorrected binocular NVA ≤20/40 were tested with plus sphere lenses to obtain best-corrected binocular NVA. Prevalence of total NVI (defined as uncorrected NVA ≤20/40) and NVI correctable and uncorrectable to >20/40, and current spectacle wearing among those with bilateral NVA ≤20/63 improving to >20/40 with near correction (met need). Among 13 671 baseline participants, 10 533 (77.2%) attended the follow-up examination. The prevalence of correctable NVI increased with age from 35 to 50-60 years and then decreased at all sites. Multiple logistic regression modeling suggested that correctable NVI was not associated with gender at any site, whereas more educated persons aged >54 years were associated with a higher prevalence of correctable NVI in Nepal and India. Although near vision spectacles were provided free at baseline, wear among those who could benefit was <40% at all but 2 centers (Guangzhou and Los Angeles). Prevalence of correctable NVI is greatest among persons of working age, and rates of correction are low in many settings, suggesting that strategies targeting the workplace may be needed. Copyright © 2014 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Use of subjective and objective criteria to categorise visual disability.

PubMed

Kajla, Garima; Rohatgi, Jolly; Dhaliwal, Upreet

2014-04-01

Visual disability is categorised using objective criteria. Subjective measures are not considered. To use subjective criteria along with objective ones to categorise visual disability. Ophthalmology out-patient department; teaching hospital; observational study. Consecutive persons aged >25 years, with vision <20/20 (in one or both eyes) due to chronic conditions, like cataract and refractive errors, were categorized into 11 groups of increasing disability; group-zero: normal range of vision, to group-X: no perception of light, bilaterally. Snellen's vision; binocular contrast sensitivity (Pelli-Robson chart); automated binocular visual field (Humphrey; Esterman test); and vision-related quality of life (Indian Visual Function Questionnaire-33; IND-VFQ33) were recorded. SPSS version-17; Kruskal-wallis test was used to compare contrast sensitivity and visual fields across groups, and Mann-Whitney U test for pair-wise comparison (Bonferroni adjustment; P < 0.01). One-way ANOVA compared quality of life data across groups; for pairwise significance, Dunnett T3 test was applied. In 226 patients, contrast sensitivity and visual fields were comparable for differing disability grades except when disability was severe (P < 0.001), or moderately severe (P < 0.01). Individual scales of IND-VFQ33 were also mostly comparable; however, global scores showed a distinct pattern, being different for some disability grades but comparable for groups III (78.51 ± 6.86) and IV (82.64 ± 5.80), and groups IV and V (77.23 ± 3.22); these were merged to generate group 345; similarly, global scores were comparable for adjacent groups V and VI (72.53 ± 6.77), VI and VII (74.46 ± 4.32), and VII and VIII (69.12 ± 5.97); these were merged to generate group 5678; thereafter, contrast sensitivity and global and individual IND-VFQ33 scores could differentiate between different grades of disability in the five new groups. Subjective criteria made it possible to objectively reclassify visual disability. Visual disability grades could be redefined to accommodate all from zero-100%.

A 3D terrain reconstruction method of stereo vision based quadruped robot navigation system

NASA Astrophysics Data System (ADS)

Ge, Zhuo; Zhu, Ying; Liang, Guanhao

2017-01-01

To provide 3D environment information for the quadruped robot autonomous navigation system during walking through rough terrain, based on the stereo vision, a novel 3D terrain reconstruction method is presented. In order to solve the problem that images collected by stereo sensors have large regions with similar grayscale and the problem that image matching is poor at real-time performance, watershed algorithm and fuzzy c-means clustering algorithm are combined for contour extraction. Aiming at the problem of error matching, duel constraint with region matching and pixel matching is established for matching optimization. Using the stereo matching edge pixel pairs, the 3D coordinate algorithm is estimated according to the binocular stereo vision imaging model. Experimental results show that the proposed method can yield high stereo matching ratio and reconstruct 3D scene quickly and efficiently.

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

PubMed

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

2013-04-01

Cataract surgery improves vision and visual functioning; the effect on general health is not established. We investigated if vision, visual functioning, and general health follow the same trajectory of change the year after cataract surgery and if changes in vision explain changes in visual disability and general health. One-hundred forty-eight persons, with a mean (SD) age of 78.9 (5.0) years (70% bilateral surgery), were assessed before and 6 weeks and 12 months after surgery. Visual disability and general health were assessed by the CatQuest-9SF and the Short Formular-36. Corrected binocular visual acuity, visual field, stereo acuity, and contrast vision improved (P < 0.001) from before to 6 weeks after surgery, with further improvements of visual acuity evident up to 12 months (P = 0.034). Cataract surgery had an effect on visual disability 1 year later (P < 0.001). Physical and mental health improved after surgery (P < 0.01) but had returned to presurgery level after 12 months. Vision changes did not explain visual disability and general health 6 weeks after surgery. Vision improved and visual disability decreased in the year after surgery, whereas changes in general health and visual functioning were short-term effects. Lack of associations between changes in vision and self-reported disability and general health suggests that the degree of vision changes and self-reported health do not have a linear relationship.

Fresnel prisms and their effects on visual acuity and binocularity.

PubMed Central

Véronneau-Troutman, S

1978-01-01

1. The visual acuity with the Fresnel membrane prism is significantly less than that with the conventional prism of the same power for all prism powers from 12 delta through 30 delata at distance and from 15 delta through 30 delta at near. 2. The difference in the visual acuity between base up and base down, and between base in and base out, is not significantly different for either the Fresnel membrane prism or for the conventional prism. 3. For both Fresnel membrane prism and the conventional prism, the visual acuity when looking straight ahead. 4. Using Fresnel membrane prisms of the same power from different lots, the visual acuity varied significantly. The 30 delta prism caused the widest range in visual acuity. 5. When normal subjects are fitted with the higher powers of the Fresnel membrane prism, fusion and stereopsis are disrupted to such an extent that the use of this device to restore or to improve binocular vision in cases with large-angle deviations is seriously questioned. 6. Moreover, the disruption of fusion and stereopsis is abrupt and severe and does not parallel the decrease in visual acuity. The severely reduced ability to maintain fusion may be related to the optical aberrations, which, in turn, may be due to the molding process and the polyvinyl chloride molding material. 7. Through the flexibility of the membrane prism is a definite advantage, because of its proclivity to reduce visual acuity and increase aberrations its prescription for adults often must be limited to only one eye. 8. For the same reasons in the young child with binocular vision problems, the membrane prism presently available should be prescribed over both eyes only in powers less than 20 delta. When the membrane prism is to be used as a partial occluder (over one eye only), any power can be used. 9. The new Fresnel "hard" prism reduces visual acuity minimally and rarely disrupts binocularity, thus increasing the potential for prismotherapy to establish binocularity. This prism is currently available only for use as a trial set. Since the cosmetic appearance of the Fresnel "hard" prism is similar to that of the Fresnel membrane prism and it is easier to maintain, it would be the prism of choice (over all other types) for bilateral prescriptions in the young patient with emmetropia. The manufacturer is urged to make these prisms available to fit a special round adjustable frame, such as that developed in Europe for use with the wafer prism. Images FIGURE 14 A FIGURE 14 B FIGURE 2 A FIGURE 2 B FIGURE 12 PMID:754384

Mapping number to space in the two hemispheres of the avian brain.

PubMed

Rugani, Rosa; Vallortigara, Giorgio; Regolin, Lucia

2016-09-01

Pre-verbal infants and non-human animals associate small numbers with the left space and large numbers with the right space. Birds and primates, trained to identify a given position in a sagittal series of identical positions, whenever required to respond on a left/right oriented series, referred the given position starting from the left end. Here, we extended this evidence by selectively investigating the role of either cerebral hemisphere, using the temporary monocular occlusion technique. In birds, lacking the corpus callosum, visual input is fed mainly to the contralateral hemisphere. We trained 4-day-old chicks to identify the 4th element in a sagittal series of 10 identical elements. At test, the series was identical but left/right oriented. Test was conducted in right monocular, left monocular or binocular condition of vision. Right monocular chicks pecked at the 4th right element; left monocular and binocular chicks pecked at the 4th left element. Data on monocular chicks demonstrate that both hemispheres deal with an ordinal (sequential) task. Data on binocular chicks indicate that the left bias is linked to a right hemisphere dominance, that allocates the attention toward the left hemispace. This constitutes a first step towards understanding the neural basis of number space mapping. Copyright © 2016 Elsevier Inc. All rights reserved.

Improvement of Vergence Movements by Vision Therapy Decreases K-ARS Scores of Symptomatic ADHD Children.

PubMed

Lee, Sun Haeng; Moon, Byeong-Yeon; Cho, Hyun Gug

2014-02-01

[Purpose] To determine whether the improvement of vergence movements by vision therapy can decrease the K-ARS scores of symptomatic ADHD children. [Methods] Eighty-one out of 1,123 children surveyed using the K-ARS, a parents'-reported questionnaire, led to 16 of these 81 children being showed scores of ≥19, and measurement of binocular function diagnosed as having convergence insufficiency. The 16 children were divided equally into a control group and a vision therapy group. [Results] After vision therapy for 12 weeks, near point convergence (4.38±0.69 cm) significantly neared compared to the near point convergence before vision therapy (11.50±2.28 cm), and both the break point (32.38±2.53 Δ) and recovery point (19.75±2.11 Δ) of near positive fusional vergence significantly improved compared to their values before vision therapy (15.88±2.64 Δ, 6.38±6.70 Δ, respectively). Near exophoria after vision therapy (7.81±2.00 Δ BI) significantly decreased compared to its value before vision therapy (12.00±1.16 Δ BI). The K-ARS scores referring to symptomatic ADHD significantly decreased after vision therapy (17.13±2.84) compared to before vision therapy (23.25±1.49). [Conclusions] Convergence insufficiency symptoms are closely related to symptoms screened for ADHD, and vision therapy to improve vergence movements is an effective method of decreasing the K-ARS scores.

Visual and Refractive Outcomes following Bilateral Implantation of Extended Range of Vision Intraocular Lens with Micromonovision

PubMed Central

Ganesh, Sri; Relekar, Kirti J.

2018-01-01

Purpose To evaluate the outcomes following bilateral ERV intraocular lens implantation with micromonovision. Methods 25 subjects underwent bilateral Tecnis Symfony IOL implantation with micromonovision. The dominant eye was targeted for emmetropia and the nondominant eye for myopia of −0.75 D. Uncorrected and corrected distance (UDVA, CDVA), intermediate (UIVA, CIVA), and near visual acuity (UNVA, DCNVA); reading performance; defocus curve; and contrast sensitivity were studied. Follow-ups were conducted at 1 week and 1 and 6 months postoperatively. Results At 6 months postoperatively, the mean binocular UDVA, CDVA, UNVA, and DCNVA were −0.036 ± 0.09, −0.108 ± 0.07, 0.152 ± 0.11, and 0.216 ± 0.10 logMAR, respectively. Binocular UIVA and DCIVA were 0.048 ± 0.09 and 0.104 ± 0.08 logMAR, respectively, at 60 cm and −0.044 ± 0.09 and 0.012 ± 0.09 logMAR, respectively, at 80 cm. All patients had ≥0.2 logMAR UDVA and UNVA. Reading acuity and reading speeds showed improvement over time. Between defocus range of −2.50 and +1.00 D, the visual acuity remained ≥0.2 logMAR. Contrast sensitivity scores were within the normal range. 4 patients used reading glasses for very fine print. Conclusion Bilateral ERV IOL implantation leads to excellent outcomes for far and intermediate vision, satisfactory outcomes for near vision, and good tolerance to micromonovision at the end of the 6 months. This trial is registered with CTRI/2015/10/006246. PMID:29545954

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

DTIC Science & Technology

2011-08-01

Intelligence (AGI). For example, it promises to unlock vast sets of training data , such as Google Images, which have previously been inaccessible to...development of this skill holds great promise for e orts, like Emer, that aim to create an Artifcial General Intelligence (AGI). For example, it promises to...instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send

Visual defects in Nepalese children with Down syndrome.

PubMed

Paudel, Nabin; Leat, Susan J; Adhikari, Prakash; Woodhouse, J Margaret; Shrestha, Jyoti Baba

2010-03-01

Down syndrome (DS) is a common chromosomal anomaly. People with this syndrome have recognisable physical characteristics and limited intellectual abilities. The aim of this study was to determine visual defects, especially refractive error and binocular anomalies, in a sample of Nepalese children with DS. Thirty-six children with DS (19 boys and 17 girls) from the Kathmandu valley, aged from four months to 18 years, underwent detailed optometric examination. Cycloplegic refraction was performed on all subjects. Vision on presentation of all the children was assessed with preferential looking cards, the Kay picture cards, the Bailey-Lovie logMAR chart or the Snellen chart. Binocular function was assessed with cover test, Hirschberg or Bruckner test. Cycloplegic refraction of the children revealed that 80 per cent of the children had significant refractive error. Most of them had hyperopia (55 per cent), followed by astigmatism (44 per cent), myopia (25 per cent) and anisometropia (19 per cent). Only two (5.6 per cent) children were strabismic and both of them were alternating esotropes. Nystagmus was present in 10 (28 per cent). Other ocular findings were upward slanting palpebral fissures, blepharitis, congenital nasolacrimal duct obstruction, blepharoconjunctivitis, chalazion and lenticular opacities. Nepalese children with DS have a high prevalence of refractive error and nystagmus. Regular eye examinations are indicated for these children to enable early diagnosis and appropriate management of ocular disorders to improve their vision and quality of life.

The Advanced Human Eye Model (AHEM): a personal binocular eye modeling system inclusive of refraction, diffraction, and scatter.

PubMed

Donnelly, William

2008-11-01

To present a commercially available software tool for creating eye models to assist the development of ophthalmic optics and instrumentation, simulate ailments or surgery-induced changes, explore vision research questions, and provide assistance to clinicians in planning treatment or analyzing clinical outcomes. A commercially available eye modeling system was developed, the Advanced Human Eye Model (AHEM). Two mainstream optical software engines, ZEMAX (ZEMAX Development Corp) and ASAP (Breault Research Organization), were used to construct a similar software eye model and compared. The method of using the AHEM is described and various eye modeling scenarios are created. These scenarios consist of retinal imaging of targets and sources; optimization capability; spectacles, contact lens, and intraocular lens insertion and correction; Zernike surface deformation on the cornea; cataract simulation and scattering; a gradient index lens; a binocular mode; a retinal implant; system import/export; and ray path exploration. Similarity of the two different optical software engines showed validity to the mechanism of the AHEM. Metrics and graphical data are generated from the various modeling scenarios particular to their input specifications. The AHEM is a user-friendly commercially available software tool from Breault Research Organization, which can assist the design of ophthalmic optics and instrumentation, simulate ailments or refractive surgery-induced changes, answer vision research questions, or assist clinicians in planning treatment or analyzing clinical outcomes.

Comparison between bilateral implantation of a trifocal intraocular lens and blended implantation of two bifocal intraocular lenses

PubMed Central

Vilar, César; Hida, Wilson Takashi; de Medeiros, André Lins; Magalhães, Klayny Rafaella Pereira; de Moraes Tzelikis, Patrick Frensel; Chaves, Mario Augusto Pereira Dias; Motta, Antônio Francisco Pimenta; Carricondo, Pedro Carlos; Alves, Milton Ruiz; Nosé, Walton

2017-01-01

Purpose To compare visual outcomes and performance between bilateral implantation of a diffractive trifocal intraocular lens (IOL) Acrysof®PanOptix® TFNT00 and blended implantation of two different near add power bifocal IOLs: Acrysof® Restor® SV25T0 in dominant eye and Acrysof® Restor® SN6AD1 in the nondominant eye. Methods This prospective, nonrandomized, consecutive and comparative study assessed 20 patients (40 eyes) who had bilateral cataract surgery performed using the IOLs described. Patients were divided into groups, bilateral trifocal implant and blended implant. Evaluation included measurement of binocular uncorrected and corrected distance visual acuity at 4 m (UDVA, CDVA) and uncorrected intermediate (60 cm) and near (at 40 cm) visual acuity; contrast sensitivity (CS) and visual defocus curve. Results Postoperative CDVA comparison showed no statistical significance between groups. UDVA was significantly better in the trifocal groups. Under photopic conditions, the trifocal group had better CS in higher frequencies with and without glare. The binocular defocus curve demonstrated a trifocal behavior in both groups, with the bilateral trifocal group exhibiting better performance for intermediate vision. Conclusion Both lens combinations were able to provide good near, intermediate and distance vision, with the trifocal group showing significantly better performance at intermediate distances and better CS under photopic conditions. PMID:28814826

The implementation of depth measurement and related algorithms based on binocular vision in embedded AM5728

NASA Astrophysics Data System (ADS)

Deng, Zhiwei; Li, Xicai; Shi, Junsheng; Huang, Xiaoqiao; Li, Feiyan

2018-01-01

Depth measurement is the most basic measurement in various machine vision, such as automatic driving, unmanned aerial vehicle (UAV), robot and so on. And it has a wide range of use. With the development of image processing technology and the improvement of hardware miniaturization and processing speed, real-time depth measurement using dual cameras has become a reality. In this paper, an embedded AM5728 and the ordinary low-cost dual camera is used as the hardware platform. The related algorithms of dual camera calibration, image matching and depth calculation have been studied and implemented on the hardware platform, and hardware design and the rationality of the related algorithms of the system are tested. The experimental results show that the system can realize simultaneous acquisition of binocular images, switching of left and right video sources, display of depth image and depth range. For images with a resolution of 640 × 480, the processing speed of the system can be up to 25 fps. The experimental results show that the optimal measurement range of the system is from 0.5 to 1.5 meter, and the relative error of the distance measurement is less than 5%. Compared with the PC, ARM11 and DMCU hardware platforms, the embedded AM5728 hardware is good at meeting real-time depth measurement requirements in ensuring the image resolution.

Adaptation to Laterally Displacing Prisms in Anisometropic Amblyopia.

PubMed

Sklar, Jaime C; Goltz, Herbert C; Gane, Luke; Wong, Agnes M F

2015-06-01

Using visual feedback to modify sensorimotor output in response to changes in the external environment is essential for daily function. Prism adaptation is a well-established experimental paradigm to quantify sensorimotor adaptation; that is, how the sensorimotor system adapts to an optically-altered visuospatial environment. Amblyopia is a neurodevelopmental disorder characterized by spatiotemporal deficits in vision that impacts manual and oculomotor function. This study explored the effects of anisometropic amblyopia on prism adaptation. Eight participants with anisometropic amblyopia and 11 visually-normal adults, all right-handed, were tested. Participants pointed to visual targets and were presented with feedback of hand position near the terminus of limb movement in three blocks: baseline, adaptation, and deadaptation. Adaptation was induced by viewing with binocular 11.4° (20 prism diopter [PD]) left-shifting prisms. All tasks were performed during binocular viewing. Participants with anisometropic amblyopia required significantly more trials (i.e., increased time constant) to adapt to prismatic optical displacement than visually-normal controls. During the rapid error correction phase of adaptation, people with anisometropic amblyopia also exhibited greater variance in motor output than visually-normal controls. Amblyopia impacts on the ability to adapt the sensorimotor system to an optically-displaced visual environment. The increased time constant and greater variance in motor output during the rapid error correction phase of adaptation may indicate deficits in processing of visual information as a result of degraded spatiotemporal vision in amblyopia.

The measurement and treatment of suppression in amblyopia.

PubMed

Black, Joanna M; Hess, Robert F; Cooperstock, Jeremy R; To, Long; Thompson, Benjamin

2012-12-14

Amblyopia, a developmental disorder of the visual cortex, is one of the leading causes of visual dysfunction in the working age population. Current estimates put the prevalence of amblyopia at approximately 1-3%(1-3), the majority of cases being monocular(2). Amblyopia is most frequently caused by ocular misalignment (strabismus), blur induced by unequal refractive error (anisometropia), and in some cases by form deprivation. Although amblyopia is initially caused by abnormal visual input in infancy, once established, the visual deficit often remains when normal visual input has been restored using surgery and/or refractive correction. This is because amblyopia is the result of abnormal visual cortex development rather than a problem with the amblyopic eye itself(4,5) . Amblyopia is characterized by both monocular and binocular deficits(6,7) which include impaired visual acuity and poor or absent stereopsis respectively. The visual dysfunction in amblyopia is often associated with a strong suppression of the inputs from the amblyopic eye under binocular viewing conditions(8). Recent work has indicated that suppression may play a central role in both the monocular and binocular deficits associated with amblyopia(9,10) . Current clinical tests for suppression tend to verify the presence or absence of suppression rather than giving a quantitative measurement of the degree of suppression. Here we describe a technique for measuring amblyopic suppression with a compact, portable device(11,12) . The device consists of a laptop computer connected to a pair of virtual reality goggles. The novelty of the technique lies in the way we present visual stimuli to measure suppression. Stimuli are shown to the amblyopic eye at high contrast while the contrast of the stimuli shown to the non-amblyopic eye are varied. Patients perform a simple signal/noise task that allows for a precise measurement of the strength of excitatory binocular interactions. The contrast offset at which neither eye has a performance advantage is a measure of the "balance point" and is a direct measure of suppression. This technique has been validated psychophysically both in control(13,14) and patient(6,9,11) populations. In addition to measuring suppression this technique also forms the basis of a novel form of treatment to decrease suppression over time and improve binocular and often monocular function in adult patients with amblyopia(12,15,16) . This new treatment approach can be deployed either on the goggle system described above or on a specially modified iPod touch device(15).

Is vision function related to physical functional ability in older adults?

PubMed

West, Catherine G; Gildengorin, Ginny; Haegerstrom-Portnoy, Gunilla; Schneck, Marilyn E; Lott, Lori; Brabyn, John A

2002-01-01

To assess the relationship between a broad range of vision functions and measures of physical performance in older adults. Cross-sectional study. Population-based cohort of community-dwelling older adults, subset of an on-going longitudinal study. Seven hundred eighty-two adults aged 55 and older (65% of living eligible subjects) had subjective health measures and objective physical performance evaluated in 1989/91 and again in 1993/95 and a battery of vision functions tested in 1993/95. Comprehensive battery of vision tests (visual acuity, contrast sensitivity, effects of illumination level, contrast and glare on acuity, visual fields with and without attentional load, color vision, temporal sensitivity, and the impact of dimming light on walking ability) and physical function measures (self-reported mobility limitations and observed measures of walking, rising from a chair and tandem balance). The failure rate for all vision functions and physical performance measures increased exponentially with age. Standard high-contrast visual acuity and standard visual fields showed the lowest failure rates. Nonstandard vision tests showed much higher failure rates. Poor performance on many individual vision functions was significantly associated with particular individual measures of physical performance. Using constructed combination vision variables, significant associations were found between spatial vision, field integrity, binocularity and/or adaptation, and each of the functional outcomes. Vision functions other than standard visual acuity may affect day-to-day functioning of older adults. Additional studies of these other aspects of vision and how they can be treated or rehabilitated are needed to determine whether these aspects play a role in strategies for reducing disability in older adults.

Development of 3D online contact measurement system for intelligent manufacturing based on stereo vision

NASA Astrophysics Data System (ADS)

Li, Peng; Chong, Wenyan; Ma, Yongjun

2017-10-01

In order to avoid shortcomings of low efficiency and restricted measuring range exsited in traditional 3D on-line contact measurement method for workpiece size, the development of a novel 3D contact measurement system is introduced, which is designed for intelligent manufacturing based on stereo vision. The developed contact measurement system is characterized with an intergarted use of a handy probe, a binocular stereo vision system, and advanced measurement software.The handy probe consists of six track markers, a touch probe and the associated elcetronics. In the process of contact measurement, the hand probe can be located by the use of the stereo vision system and track markers, and 3D coordinates of a space point on the workpiece can be mearsured by calculating the tip position of a touch probe. With the flexibility of the hand probe, the orientation, range, density of the 3D contact measurenent can be adptable to different needs. Applications of the developed contact measurement system to high-precision measurement and rapid surface digitization are experimentally demonstrated.

Binocular treatment of amblyopia using videogames (BRAVO): study protocol for a randomised controlled trial.

PubMed

Guo, Cindy X; Babu, Raiju J; Black, Joanna M; Bobier, William R; Lam, Carly S Y; Dai, Shuan; Gao, Tina Y; Hess, Robert F; Jenkins, Michelle; Jiang, Yannan; Kowal, Lionel; Parag, Varsha; South, Jayshree; Staffieri, Sandra Elfride; Walker, Natalie; Wadham, Angela; Thompson, Benjamin

2016-10-18

Amblyopia is a common neurodevelopmental disorder of vision that is characterised by visual impairment in one eye and compromised binocular visual function. Existing evidence-based treatments for children include patching the nonamblyopic eye to encourage use of the amblyopic eye. Currently there are no widely accepted treatments available for adults with amblyopia. The aim of this trial is to assess the efficacy of a new binocular, videogame-based treatment for amblyopia in older children and adults. We hypothesise that binocular treatment will significantly improve amblyopic eye visual acuity relative to placebo treatment. The BRAVO study is a double-blind, randomised, placebo-controlled multicentre trial to assess the effectiveness of a novel videogame-based binocular treatment for amblyopia. One hundred and eight participants aged 7 years or older with anisometropic and/or strabismic amblyopia (defined as ≥0.2 LogMAR interocular visual acuity difference, ≥0.3 LogMAR amblyopic eye visual acuity and no ocular disease) will be recruited via ophthalmologists, optometrists, clinical record searches and public advertisements at five sites in New Zealand, Canada, Hong Kong and Australia. Eligible participants will be randomised by computer in a 1:1 ratio, with stratification by age group: 7-12, 13-17 and 18 years and older. Participants will be randomised to receive 6 weeks of active or placebo home-based binocular treatment. Treatment will be in the form of a modified interactive falling-blocks game, implemented on a 5th generation iPod touch device viewed through red/green anaglyphic glasses. Participants and those assessing outcomes will be blinded to group assignment. The primary outcome is the change in best-corrected distance visual acuity in the amblyopic eye from baseline to 6 weeks post randomisation. Secondary outcomes include distance and near visual acuity, stereopsis, interocular suppression, angle of strabismus (where applicable) measured at baseline, 3, 6, 12 and 24 weeks post randomisation. Treatment compliance and acceptability will also be assessed along with quality of life for adult participants. The BRAVO study is the first randomised controlled trial of a home-based videogame treatment for older children and adults with amblyopia. The results will indicate whether a binocular approach to amblyopia treatment conducted at home is effective for patients aged 7 years or older. This trial was registered in Australia and New Zealand Clinical Trials Registry ( ACTRN12613001004752 ) on 10 September 2013.

Real-Time Gaze Holding in Binocular Robot Vision

DTIC Science & Technology

1992-06-01

could have strong implications for visual perception for locomotion. Some results [Bandopadhay, 1986; Aloimonos et al., 1988; Raviv and Herman, 1991...34 In SPIE v. 119, Applications of Digital Image Processing, pages 197-205, San Diego, 1977. [ Raviv and Herman, 1991] Daniel Raviv and Martin Herman...ohlps ft~eshv dqaehg rqec cw te, utte erodcý- d s ii.vc t fle iach ,. oth rio tal van eric lIN (b)IsOw am Imgoaflr pidcalm JOwfile Ths mag iI otlr

Assessment and Development of Oculomotor Flying Skills by the Application of the Channel Theory of Vision.

DTIC Science & Technology

1982-03-26

IT NUMBERSCentre for Research in Sensory Psychology and Medical Physics, Dalhousie University, Halifax, Nova. Scotia, Canada B3J IB6 JA...34Background" above has been developed 38 more extensively in an article for Psychological Review, and the implications for skilled eye-limb coordination are...Press. 4. Barlow , H., Blakemore, C.B. and Pettigrew, J.D. (1967) The neural mechanism of binocular depth discrimination. J. Physiol., Lond. 193, 327-342

Three-dimensional vision enhances task performance independently of the surgical method.

PubMed

Wagner, O J; Hagen, M; Kurmann, A; Horgan, S; Candinas, D; Vorburger, S A

2012-10-01

Within the next few years, the medical industry will launch increasingly affordable three-dimensional (3D) vision systems for the operating room (OR). This study aimed to evaluate the effect of two-dimensional (2D) and 3D visualization on surgical skills and task performance. In this study, 34 individuals with varying laparoscopic experience (18 inexperienced individuals) performed three tasks to test spatial relationships, grasping and positioning, dexterity, precision, and hand-eye and hand-hand coordination. Each task was performed in 3D using binocular vision for open performance, the Viking 3Di Vision System for laparoscopic performance, and the DaVinci robotic system. The same tasks were repeated in 2D using an eye patch for monocular vision, conventional laparoscopy, and the DaVinci robotic system. Loss of 3D vision significantly increased the perceived difficulty of a task and the time required to perform it, independently of the approach (P < 0.0001-0.02). Simple tasks took 25 % to 30 % longer to complete and more complex tasks took 75 % longer with 2D than with 3D vision. Only the difficult task was performed faster with the robot than with laparoscopy (P = 0.005). In every case, 3D robotic performance was superior to conventional laparoscopy (2D) (P < 0.001-0.015). The more complex the task, the more 3D vision accelerates task completion compared with 2D vision. The gain in task performance is independent of the surgical method.

Transcranial direct current stimulation enhances recovery of stereopsis in adults with amblyopia.

PubMed

Spiegel, Daniel P; Li, Jinrong; Hess, Robert F; Byblow, Winston D; Deng, Daming; Yu, Minbin; Thompson, Benjamin

2013-10-01

Amblyopia is a neurodevelopmental disorder of vision caused by abnormal visual experience during early childhood that is often considered to be untreatable in adulthood. Recently, it has been shown that a novel dichoptic videogame-based treatment for amblyopia can improve visual function in adult patients, at least in part, by reducing inhibition of inputs from the amblyopic eye to the visual cortex. Non-invasive anodal transcranial direct current stimulation has been shown to reduce the activity of inhibitory cortical interneurons when applied to the primary motor or visual cortex. In this double-blind, sham-controlled cross-over study we tested the hypothesis that anodal transcranial direct current stimulation of the visual cortex would enhance the therapeutic effects of dichoptic videogame-based treatment. A homogeneous group of 16 young adults (mean age 22.1 ± 1.1 years) with amblyopia were studied to compare the effect of dichoptic treatment alone and dichoptic treatment combined with visual cortex direct current stimulation on measures of binocular (stereopsis) and monocular (visual acuity) visual function. The combined treatment led to greater improvements in stereoacuity than dichoptic treatment alone, indicating that direct current stimulation of the visual cortex boosts the efficacy of dichoptic videogame-based treatment. This intervention warrants further evaluation as a novel therapeutic approach for adults with amblyopia.

Accuracy of accommodation in heterophoric patients: testing an interaction model in a large clinical sample.

PubMed

Hasebe, Satoshi; Nonaka, Fumitaka; Ohtsuki, Hiroshi

2005-11-01

A model of the cross-link interactions between accommodation and convergence predicted that heterophoria can induce large accommodation errors (Schor, Ophthalmic Physiol. Opt. 1999;19:134-150). In 99 consecutive patients with intermittent tropia or decompensated phoria, we tested these interactions by comparing their accommodative responses to a 2.50-D target under binocular fused conditions (BFC) and monocular occluded conditions (MOC). The accommodative response in BFC frequently differed from that in MOC. The magnitude of the accommodative errors in BFC, ranging from an accommodative lag of 1.80 D (in an esophoric patient) to an accommodative lead of 1.56 D (in an exophoric patient), was correlated with distance heterophoria and uncorrected refractive errors. These results indicate that heterophoria affects the accuracy of accommodation to various degrees, as the model predicted, and that an accommodative error larger than the depth of focus of the eye occurs in exchange for binocular single vision in some heterophoric patients.

Clinical vision characteristics of the congenital achromatopsias. I. Visual acuity, refractive error, and binocular status.

PubMed

Haegerstrom-Portnoy, G; Schneck, M E; Verdon, W A; Hewlett, S E

1996-07-01

Visual acuity, refractive error, and binocular status were determined in 43 autosomal recessive (AR) and 15 X-linked (XL) congenital achromats. The achromats were classified by color matching and spectral sensitivity data. Large interindividual variation in refractive error and visual acuity was present within each achromat group (complete AR, incomplete AR, and XL). However, the number of individuals with significant interocular acuity differences is very small. Most XLs are myopic; ARs show a wide range of refractive error from high myopia to high hyperopia. Acuity of the AR and XL groups was very similar. With-the-rule astigmatism of large amount is very common in achromats, particularly ARs. There is a close association between strabismus and interocular acuity differences in the ARs, with the fixating eye having better than average acuity. The large overlap of acuity and refractive error of XL and AR achromats suggests that these measures are less useful for differential diagnosis than generally indicated by the clinical literature.

Application of integral imaging autostereoscopic display to medical training equipment

NASA Astrophysics Data System (ADS)

Nagatani, Hiroyuki

2010-02-01

We applied an autostereoscopic display based on the integral imaging method (II method) to training equipment for medical treatment in an attempt to recover the binocular vision performance of strabismus or amblyopia (lazy eye) patients. This report summarizes the application method and results. The point of the training is to recognize the parallax using both eyes. The strabismus or amblyopia patients have to recognize the information on both eyes equally when they gaze at the display with parallax and perceive the stereo depth of the content. Participants in this interactive training engage actively with the image. As a result, they are able to revive their binocular visual function while playing a game. Through the training, the observers became able to recognize the amount of parallax correctly. In addition, the training level can be changed according to the eyesight difference between a right eye and a left eye. As a result, we ascertained that practical application of the II method for strabismus or amblyopia patients would be possible.

[See the strabismus and amblyopia research development trend from the twelfth World Congress of strabismus].

PubMed

Zhao, Kanxing; Kang, Xiaoli; Liu, Hu; Wei, Yan

2015-06-01

The International strabismus association conference has a history of fifty years until now. It's the most influential academic communication forum for the worldwide doctors and related scientists or technical carers in strabismus and amblyopia area. The conference gathered the top-level experts. The latest clinical/research achievements of strabismus, amblyopia in the field of binocular vision and ocular motility have been showed. The breakthroughs in the etiology study of incomitant strabismus have been and are being transformed into new therapeutic concepts and techniques. Re-adjust the competition between dominant and amblyopic eye using binocular stimulation methods may overcome the existing defects of monocular occlusion therapy, expand new interventional methods to treat amblyopia, and represent the future trends of amblyopia therapy. In this paper, we will introduce the main contents of the XII ISA meeting and spread knowledge of strabismus/amblyopia promoting directions in order to provide reference ideas for the clinicians and research colleagues in this field.

A simple infrared-augmented digital photography technique for detection of pupillary abnormalities.

PubMed

Shazly, Tarek A; Bonhomme, G R

2015-03-01

The purpose of the study was to describe a simple infrared photography technique to aid in the diagnosis and documentation of pupillary abnormalities. An unmodified 12-megapixel "point and shoot" digital camera was used to obtain binocular still photos and videos under different light conditions with near-infrared illuminating frames. The near-infrared light of 850 nm allows the capture of clear pupil images in both dim and bright light conditions. It also allows easy visualization of the pupil despite pigmented irides by augmenting the contrast between the iris and the pupil. The photos and videos obtained illustrated a variety of pupillary abnormalities using the aforementioned technique. This infrared-augmented photography technique supplements medical education, and aids in the more rapid detection, diagnosis, and documentation of a wide spectrum of pupillary abnormalities. Its portability and ease of use with minimal training complements the education of trainees and facilitates the establishment of difficult diagnoses.

Color vision abnormality as an initial presentation of the complete type of congenital stationary night blindness.

PubMed

Tan, Xue; Aoki, Aya; Yanagi, Yasuo

2013-01-01

Patients with the complete form of congenital stationary night blindness (CSNB) often have reduced visual acuity, myopia, impaired night vision, and sometimes nystagmus and strabismus, however, they seldom complain of color vision abnormality. A 17-year-old male who was at technical school showed abnormalities in the color perception test for employment, and was referred to our hospital for a detailed examination. He had no family history of color vision deficiency and no other symptoms. During the initial examination, his best-corrected visual acuity was 1.2 in both eyes. His fundus showed no abnormalities except for somewhat yellowish reflex in the fovea of both eyes. Electroretinogram (ERG) showed a good response in cone ERG and 30 Hz flicker ERG, however, the bright flash, mixed rod and cone ERG showed a negative type with a reduced b-wave (positive deflection). There was no response in the rod ERG, either. From the findings of the typical ERG, the patient was diagnosed with complete congenital stationary night blindness. This case underscores the importance of ERG in order to diagnose the cause of a color vision anomaly.

Obstacle Detection using Binocular Stereo Vision in Trajectory Planning for Quadcopter Navigation

NASA Astrophysics Data System (ADS)

Bugayong, Albert; Ramos, Manuel, Jr.

2018-02-01

Quadcopters are one of the most versatile unmanned aerial vehicles due to its vertical take-off and landing as well as hovering capabilities. This research uses the Sum of Absolute Differences (SAD) block matching algorithm for stereo vision. A complementary filter was used in sensor fusion to combine obtained quadcopter orientation data from the accelerometer and the gyroscope. PID control was implemented for the motor control and VFH+ algorithm was implemented for trajectory planning. Results show that the quadcopter was able to consistently actuate itself in the roll, yaw and z-axis during obstacle avoidance but was however found to be inconsistent in the pitch axis during forward and backward maneuvers due to the significant noise present in the pitch axis angle outputs compared to the roll and yaw axes.

Periorbital hemangiomas.

PubMed

Goldberg, N S; Rosanova, M A

1992-10-01

1. Any hemangioma that involves the upper or lower lid and leads to partial closure in infancy may interfere with or prevent development of normal binocular vision in a matter of days to weeks. 2. Hemangiomas least likely to interfere with vision are lower lid lesions occupying one third of the lid margin or less, not extending beyond the eyelid region, and resolving early. 3. Hemangiomas associated with deprivation amblyopia (with or without anisometropia) are lesions occupying more than one half of the lid margin, extending beyond the eyelid region, resolving late, and obstructing the visual axis. 4. Hemangiomas associated with isolated anisometropic amblyopia are local but bulky lesions that are usually but not always restricted to the upper lid, closing the eye partly and resolving late. 5. The treatment of choice for periorbital hemangiomas is corticosteroids, either systemic or intralesional.

The risk of pedestrian collisions with peripheral visual field loss.

PubMed

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

2016-12-01

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

Improved stereo matching applied to digitization of greenhouse plants

NASA Astrophysics Data System (ADS)

Zhang, Peng; Xu, Lihong; Li, Dawei; Gu, Xiaomeng

2015-03-01

The digitization of greenhouse plants is an important aspect of digital agriculture. Its ultimate aim is to reconstruct a visible and interoperable virtual plant model on the computer by using state-of-the-art image process and computer graphics technologies. The most prominent difficulties of the digitization of greenhouse plants include how to acquire the three-dimensional shape data of greenhouse plants and how to carry out its realistic stereo reconstruction. Concerning these issues an effective method for the digitization of greenhouse plants is proposed by using a binocular stereo vision system in this paper. Stereo vision is a technique aiming at inferring depth information from two or more cameras; it consists of four parts: calibration of the cameras, stereo rectification, search of stereo correspondence and triangulation. Through the final triangulation procedure, the 3D point cloud of the plant can be achieved. The proposed stereo vision system can facilitate further segmentation of plant organs such as stems and leaves; moreover, it can provide reliable digital samples for the visualization of greenhouse tomato plants.

Disparity channels in early vision

PubMed Central

Roe, AW; Parker, AJ; Born, RT; DeAngelis, GC

2008-01-01

The last decade has seen a dramatic increase in our knowledge of the neural basis of stereopsis. New cortical areas have been found to represent binocular disparities, new representations of disparity information (e.g., relative disparity signals) have been uncovered, the first topographic maps of disparity have been measured, and the first causal links between neural activity and depth perception have been established. Equally exciting is the finding that training and experience affects how signals are channeled through different brain areas, a flexibility that may be crucial for learning, plasticity, and recovery of function. The collective efforts of several laboratories have established stereo vision as one of the most productive model systems for elucidating the neural basis of perception. Much remains to be learned about how the disparity signals that are initially encoded in primary visual cortex are routed to and processed by extrastriate areas to mediate the diverse capacities of 3D vision that enhance our daily experience of the world. PMID:17978018

Effects of Anisometropic Amblyopia on Visuomotor Behavior, Part 2: Visually Guided Reaching

PubMed Central

Niechwiej-Szwedo, Ewa; Goltz, Herbert C.; Chandrakumar, Manokaraananthan; Hirji, Zahra; Crawford, J. Douglas; Wong, Agnes M. F.

2016-01-01

Purpose The effects of impaired spatiotemporal vision in amblyopia on visuomotor skills have rarely been explored in detail. The goal of this study was to examine the influences of amblyopia on visually guided reaching. Methods Fourteen patients with anisometropic amblyopia and 14 control subjects were recruited. Participants executed reach-to-touch movements toward targets presented randomly 5° or 10° to the left or right of central fixation in three viewing conditions: binocular, monocular amblyopic eye, and monocular fellow eye viewing (left and right monocular viewing for control subjects). Visual feedback of the target was removed on 50% of the trials at the initiation of reaching. Results Reaching accuracy was comparable between patients and control subjects during all three viewing conditions. Patients’ reaching responses were slightly less precise during amblyopic eye viewing, but their precision was normal during binocular or fellow eye viewing. Reaching reaction time was not affected by amblyopia. The duration of the acceleration phase was longer in patients than in control subjects under all viewing conditions, whereas the duration of the deceleration phase was unaffected. Peak acceleration and peak velocity were also reduced in patients. Conclusions Amblyopia affects both the programming and the execution of visually guided reaching. The increased duration of the acceleration phase, as well as the reduced peak acceleration and peak velocity, might reflect a strategy or adaptation of feedforward/feedback control of the visuomotor system to compensate for degraded spatiotemporal vision in amblyopia, allowing patients to optimize their reaching performance. PMID:21051723

Unexplained head tilt following surgical treatment of congenital esotropia: a postural manifestation of dissociated vertical divergence

PubMed Central

Brodsky, M C; Jenkins, R; Nucci, P

2004-01-01

Background: Strabismus surgery for congenital esotropia can be complicated by the development of a postoperative head tilt. Purpose: To determine the pathophysiology of acquired head tilting following horizontal realignment of the eyes in children with congenital esotropia. Materials and methods: Retrospective analysis of nine children with congenital esotropia who developed unexplained head tilts following horizontal realignment of the eyes. Results: Shortly after strabismus surgery, each child developed a head tilt in association with asymmetrical dissociated vertical divergence (DVD). Five children maintained a head tilt toward the side of the fixing eye (group 1), which did not serve to control the DVD. Four children maintained a head tilt toward the side of the hyperdeviating eye, which served to control the DVD (group 2). Children in group 2 had earlier horizontal muscle surgery and developed better stereopsis than those in group 1, suggesting that the higher degree of single binocular vision and stereopsis in these children may have led to a compensatory torticollis to control an asymmetrical DVD. Conclusions: The onset of an unexpected head tilt after congenital esotropia surgery is usually a postural manifestation of asymmetrical DVD. In this setting, a head tilt toward the side of the fixing eye corresponds with a postural manifestation of the underlying central vestibular imbalance that produces DVD, while a head tilt toward the side of the hyperdeviating eye serves to counteract the hyperdeviation and stabilise binocular vision. PMID:14736789

A systematic comparison between visual cues for boundary detection.

PubMed

Mély, David A; Kim, Junkyung; McGill, Mason; Guo, Yuliang; Serre, Thomas

2016-03-01

The detection of object boundaries is a critical first step for many visual processing tasks. Multiple cues (we consider luminance, color, motion and binocular disparity) available in the early visual system may signal object boundaries but little is known about their relative diagnosticity and how to optimally combine them for boundary detection. This study thus aims at understanding how early visual processes inform boundary detection in natural scenes. We collected color binocular video sequences of natural scenes to construct a video database. Each scene was annotated with two full sets of ground-truth contours (one set limited to object boundaries and another set which included all edges). We implemented an integrated computational model of early vision that spans all considered cues, and then assessed their diagnosticity by training machine learning classifiers on individual channels. Color and luminance were found to be most diagnostic while stereo and motion were least. Combining all cues yielded a significant improvement in accuracy beyond that of any cue in isolation. Furthermore, the accuracy of individual cues was found to be a poor predictor of their unique contribution for the combination. This result suggested a complex interaction between cues, which we further quantified using regularization techniques. Our systematic assessment of the accuracy of early vision models for boundary detection together with the resulting annotated video dataset should provide a useful benchmark towards the development of higher-level models of visual processing. Copyright © 2016 Elsevier Ltd. All rights reserved.

Endotracheal Intubation With and Without Night Vision Goggles in a Helicopter and Emergency Room Setting: A Manikin Study.

PubMed

Gellerfors, Mikael; Svensén, Christer; Linde, Joacim; Lossius, Hans Morten; Gryth, Dan

2015-09-01

Securing the airway by endotracheal intubation (ETI) is a key issue in prehospital critical care. Night vision goggles (NVG) are used by personnel operating in low-light environments. We examined the feasibility of an anesthesiologist performed ETI using NVG in a helicopter setting. Twelve anesthesiologists performed ETI on a manikin in an emergency room (ER) setting and two helicopter settings, with randomization to either rotary wing daylight (RW-D) or rotary wing in total darkness using binocular NVG (RW-NVG). Primary endpoint was intubation time. Secondary endpoints included success rate, Cormack-Lehane (CL) score, and subjective difficulty according to the Visual Analoge Scale (VAS). The median intubation time was shorter for the RW-D compared to the RW-NVG setting (16.5 seconds vs. 30.0 seconds; p = 0,03). We found no difference in median intubation time for the ER and RW-D settings (16.8 seconds vs. 16.5 seconds; p = 0.91). For all scenarios, success rate was 100%. CL and VAS varied between the ER setting (CL 1.8, VAS 2.8), RW-D setting (CL 2.0, VAS 3.0), and RW-NVG setting (CL 3.0, VAS 6.5). This study suggests that anesthesiologists successfully and quickly can perform ETI in a helicopter setting both in daylight and in darkness using binocular NVG, but with shorter intubation times in daylight. Reprint & Copyright © 2015 Association of Military Surgeons of the U.S.

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

PubMed

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

2018-01-01

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

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

PubMed Central

Farragher, Tracey M; Shickle, Darren

2018-01-01

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

Maximal subtotal extirpation of the horizontal rectus extraocular muscles for the treatment of nystagmus with no null point. A report of four successful human cases.

PubMed

Sinskey, Robert M; Eshete, Almaz

2002-01-01

To evaluate the visual and restoration of normal appearance results of maximal excision of the horizontal rectus muscles in nystagmus patients. Menelik II Hospital, Addis Ababa, Ethiopia and the Sinskey Eye Institute, Santa Monica, California. The medial and lateral rectus muscles were extirpated as far back as possible with an enucleation snare in four patients with horizontal nystagmus. A complete eye examination was performed pre- and postoperatively. Using a camcorder, ocular movements were recorded before surgery, and at postop; days 1 and 40, and months 1, 3 and 10. All four patients had a marked reduction in both abnormal and normal horizontal eye movement, and improvement in objective visual acuity. Postoperative residual intermittent fine horizontal movement was recorded in the left eye in a 6 year old and in both eyes of a 41 year old patient. A residual rotary component was recorded in a 15 year-old patient. The 6 and 9 year-old patients each developed a moderate exotropia. The 15 and 41 year-old patients maintained binocular fusion with some residual ability to converge. Vision increased subjectively in all cases. Subtotal myectomy of the horizontal muscles in horizontal nystagmus with no null point was very effective in improving and/or eliminating horizontal eye movement. Restoration of normal or near normal appearance and improvement in visual acuity occurred in all cases. None of the patients complained of their loss of horizontal gaze and eye movement. More complete myectomy of the muscles should produce total elimination of both normal and abnormal horizontal eye movement including nystagmus.

Visual impairment evaluation in 119 children with congenital Zika syndrome.

PubMed

Ventura, Liana O; Ventura, Camila V; Dias, Natália de C; Vilar, Isabelle G; Gois, Adriana L; Arantes, Tiago E; Fernandes, Luciene C; Chiang, Michael F; Miller, Marilyn T; Lawrence, Linda

2018-06-01

To assess visual impairment in a large sample of infants with congenital Zika syndrome (CZS) and to compare with a control group using the same assessment protocol. The study group was composed of infants with confirmed diagnosis of CZS. Controls were healthy infants matched for age, sex, and socioeconomic status. All infants underwent comprehensive ophthalmologic evaluation including visual acuity, visual function assessment, and visual developmental milestones. The CZS group included 119 infants; the control group, 85 infants. At examination, the mean age of the CZS group was 8.5 ± 1.2 months (range, 6-13 months); of the controls, 8.4 ± 1.8 months (range, 5-12 months; P = 0.598). Binocular Teller Acuity Card (TAC) testing was abnormal in 107 CZS infants and in 4 controls (89.9% versus 5% [P < 0.001]). In the study group, abnormal monocular TAC results were more frequent in eyes with funduscopic alterations (P = 0.008); however, 104 of 123 structurally normal eyes (84.6%) also presented abnormal TAC results. Binocular contrast sensitivity was reduced in 87 of 107 CZS infants and in 8 of 80 controls (81.3% versus 10% [P < 0.001]). The visual development milestones were less achieved by infants with CZS compared to controls (P < 0.001). Infants with CZS present with severe visual impairment. A protocol for assessment of the ocular findings, visual acuity, and visual developmental milestones tested against age-matched controls is suggested. Copyright © 2018 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.

Dense range map reconstruction from a versatile robotic sensor system with an active trinocular vision and a passive binocular vision.

PubMed

Kim, Min Young; Lee, Hyunkee; Cho, Hyungsuck

2008-04-10

One major research issue associated with 3D perception by robotic systems is the creation of efficient sensor systems that can generate dense range maps reliably. A visual sensor system for robotic applications is developed that is inherently equipped with two types of sensor, an active trinocular vision and a passive stereo vision. Unlike in conventional active vision systems that use a large number of images with variations of projected patterns for dense range map acquisition or from conventional passive vision systems that work well on specific environments with sufficient feature information, a cooperative bidirectional sensor fusion method for this visual sensor system enables us to acquire a reliable dense range map using active and passive information simultaneously. The fusion algorithms are composed of two parts, one in which the passive stereo vision helps active vision and the other in which the active trinocular vision helps the passive one. The first part matches the laser patterns in stereo laser images with the help of intensity images; the second part utilizes an information fusion technique using the dynamic programming method in which image regions between laser patterns are matched pixel-by-pixel with help of the fusion results obtained in the first part. To determine how the proposed sensor system and fusion algorithms can work in real applications, the sensor system is implemented on a robotic system, and the proposed algorithms are applied. A series of experimental tests is performed for a variety of configurations of robot and environments. The performance of the sensor system is discussed in detail.

PixonVision real-time video processor

NASA Astrophysics Data System (ADS)

Puetter, R. C.; Hier, R. G.

2007-09-01

PixonImaging LLC and DigiVision, Inc. have developed a real-time video processor, the PixonVision PV-200, based on the patented Pixon method for image deblurring and denoising, and DigiVision's spatially adaptive contrast enhancement processor, the DV1000. The PV-200 can process NTSC and PAL video in real time with a latency of 1 field (1/60 th of a second), remove the effects of aerosol scattering from haze, mist, smoke, and dust, improve spatial resolution by up to 2x, decrease noise by up to 6x, and increase local contrast by up to 8x. A newer version of the processor, the PV-300, is now in prototype form and can handle high definition video. Both the PV-200 and PV-300 are FPGA-based processors, which could be spun into ASICs if desired. Obvious applications of these processors include applications in the DOD (tanks, aircraft, and ships), homeland security, intelligence, surveillance, and law enforcement. If developed into an ASIC, these processors will be suitable for a variety of portable applications, including gun sights, night vision goggles, binoculars, and guided munitions. This paper presents a variety of examples of PV-200 processing, including examples appropriate to border security, battlefield applications, port security, and surveillance from unmanned aerial vehicles.

Rapid assessment of visual impairment (RAVI) in marine fishing communities in South India - study protocol and main findings

PubMed Central

2011-01-01

Background Reliable data are a pre-requisite for planning eye care services. Though conventional cross sectional studies provide reliable information, they are resource intensive. A novel rapid assessment method was used to investigate the prevalence and causes of visual impairment and presbyopia in subjects aged 40 years and older. This paper describes the detailed methodology and study procedures of Rapid Assessment of Visual Impairment (RAVI) project. Methods A population-based cross-sectional study was conducted using cluster random sampling in the coastal region of Prakasam district of Andhra Pradesh in India, predominantly inhabited by fishing communities. Unaided, aided and pinhole visual acuity (VA) was assessed using a Snellen chart at a distance of 6 meters. The VA was re-assessed using a pinhole, if VA was < 6/12 in either eye. Near vision was assessed using N notation chart binocularly. Visual impairment was defined as presenting VA < 6/18 in the better eye. Presbyopia is defined as binocular near vision worse than N8 in subjects with binocular distance VA of 6/18 or better. Results The data collection was completed in <12 weeks using two teams each consisting of one paramedical ophthalmic personnel and two community eye health workers. The prevalence of visual impairment was 30% (95% CI, 27.6-32.2). This included 111 (7.1%; 95% CI, 5.8-8.4) individuals with blindness. Cataract was the leading cause of visual impairment followed by uncorrected refractive errors. The prevalence of blindness according to WHO definition (presenting VA < 3/60 in the better eye) was 2.7% (95% CI, 1.9-3.5). Conclusion There is a high prevalence of visual impairment in marine fishing communities in Prakasam district in India. The data from this rapid assessment survey can now be used as a baseline to start eye care services in this region. The rapid assessment methodology (RAVI) reported in this paper is robust, quick and has the potential to be replicated in other areas. PMID:21929802

Interocular suppression

NASA Astrophysics Data System (ADS)

Tuna, Ana Rita; Almeida Neves Carrega, Filipa; Nunes, Amélia Fernandes

2017-08-01

The objective of this work is to quantify the suppressive imbalance, based on the manipulation of ocular luminance, between a group of subjects with normal binocular vision and a group of subjects with amblyopia. The result reveals that there are statistically significant differences in interocular dominance between two groups, evidencing a greater suppressive imbalance in amblyopic subjects. The technique used, proved to be a simple, easy to apply and economic method, for quantified ocular dominance. It is presented as a technique with the potential to accompany subjects with a marked dominance in one of the eyes that makes fusion difficult.

Diplopia after Strabismus Surgery.

PubMed

Sharma, Medha; Hunter, David G

2018-01-01

Diplopia is a disappointing and, at times, unanticipated consequence of what might otherwise be considered anatomically successful strabismus surgery. In this study, we review the existing literature regarding diplopia after strabismus surgery in the context of the senior author's experience. We divide postoperative diplopia types into cases that occur in the setting of normal binocular vision (or "normal" suppression) vs. cases that are the consequence of rare or anomalous sensorial adaptations. We then discuss how to identify patients at greatest risk based on history and preoperative testing, and we offer strategies for managing these sometimes-challenging cases.

[The evaluation of color vision and its diagnostic value in predicting the risk of diabetic retinopathy in patients with glucose metabolism disorders].

PubMed

Jończyk-Skórka, Katarzyna; Kowalski, Jan

2017-07-21

The aim of the study was to evaluate color vision and its diagnostic value in predicting the risk of diabetic retinopathy in patients with glucose metabolism disorders. The study involved 197 people, 92 women and 105 men aged 63.21 ± 8.74 years. In order to assess glucose metabolism disorders, patients were divided into three groups. The first group (DM) consisted of 60 people (16 women and 44 men aged 61.92 ± 8.46 years). These were people with type 2 diabetes. Second group (IFG IGT) consisted of 67 people (35 women and 32 men aged 65 ± 8.5 years). These were people who were diagnosed with impaired fasting glucose or impaired glucose tolerance. The third group, the control one (K) consisted of 70 people (41 women and 29 men aged 62.6 ± 9.06 years). They were healthy individuals. In order to assess diabetic retinopathy study population was divided into two groups. The first group (BZ) consisted of 177 patients (84 women and 93 men aged 62.9 ± 8.78 years) without diabetic retinopathy. The second group (NPDR) consisted of 20 patients (8 women and 12 men aged 65.95 ± 8.17 years) with diabetic retinopathy. Glucose metabolism disorders were diagnosed with glucose tolerance test (OGTT). Evaluation of retinopathy was based on eye examination. All patients underwent binocular Farnsworth-Munsell 100 Hue color vision test (test result is a Total Error Score - TES). In the healthy control group (K) there were less patients with diabetic retinopathy (p = 0,0101), and less patients with abnormal color vision test (p = 0,0001) than in other groups. Majority of patients in K group had generalized abnormalities of color vision while other groups demonstrated tritanomalią (p = 0,0018). It was discovered that sTES value adequately distinguishes group K from group IFG, IGT, DM (AUC = 0,673), group K from group DM (AUC = 0,701), and group K from group IFG IGT (AUC = 0,648) sTES does not differentiate groups IGT, IFG and DM (AUC = 0,563). It was shown that in IGT, IFG group sTES was an independent risk factor that increased the risk of prediabetes almost six times (OR 5,924, 95% CI [1,169- 30,036], p = 0,032). In DM group sTES was an independent risk factor, which increased the risk of diabetes more than thirteen times (OR 13,408, 95% CI [2,324-77,345], p = 0,004). Higher values of sTES occurred in patients with retinopathy (NPDR) (p <0,001) and multivariate analyzes demonstrated that sTES ≥1.04 was an independent risk factor that increased the risk of retinopathy over twenty times (OR 21,380, 95% CI [1,101 -89,241], p <0,001). sTES is an independent risk factor for glucose metabolism disorders that increases the risk of prediabetes almost six times and the risk of diabetes more than thirteen times. sTES ≥1,04 is an independent risk factor for diabetic retinopathy. sTES ≥1,04 increases the risk of diabetic retinopathy over twenty times. The color vision 100 Hue test can be useful in detecting glucose metabolism disorders even before the ophthalmoscopic manifestation of retinopathy. Early detection rises the possibility to prevent or delay the development of diabetes through lifestyle changes and implementation of healthy behaviors.

International Practice in Care Provision for Post-stroke Visual Impairment.

PubMed

Rowe, Fiona J

2017-09-01

This study sought to explore the practice of orthoptists internationally in care provision for poststroke visual impairment. Survey questions were developed and piloted with clinicians, academics, and users. Questions addressed types of visual problems, how these were identified, treated, and followed up, care pathways in use, links with other professions, and referral options. The survey was approved by the institutional ethical committee. The survey was accessed via a web link that was circulated through the International Orthoptic Association member professional organisations to orthoptists. Completed electronic surveys were obtained from 299 individuals. About one-third (35.5%) of orthoptists saw patients within 2 weeks of stroke onset and over half (55.5%) by 1 month post stroke. Stroke survivors were routinely assessed by 87%; over three-quarters in eye clinics. Screening tools were used by 11%. Validated tests were used for assessment of visual acuity (76.5%), visual field (68.2%), eye movement (80.9%), binocular vision (77.9%), and visual function (55.8%). Visual problems suspected by family or professionals were high (86.6%). Typical overall follow-up period of vision care was less than 3 months. Designated care pathways for stroke survivors with visual problems were used by 56.9% of orthoptists. Information on visual impairment was provided by 85.9% of orthoptists. In international orthoptic practice, there is general agreement on assessment and management of visual impairment in stroke populations. More than half of orthoptists reported seeing stroke survivors within 1 month of the stroke onset, typically in eye clinics. There was a high use of validated tests of visual acuity, visual fields, ocular motility, and binocular vision. Similarly there was high use of established treatment options including prisms, occlusion, compensatory strategies, and oculomotor training, appropriately targeted at specific types of visual conditions/symptoms. This information can be used to inform choice of core outcome orthoptic measures in stroke practice.

Color vision defects in adrenomyeloneuropathy.

PubMed Central

Sack, G H; Raven, M B; Moser, H W

1989-01-01

The relationship between abnormal color vision and adrenomyeloneuropathy (AMN) was investigated in 27 AMN patients and 31 age-matched controls by using the Farnsworth-Munsell 100 Hue test. Twelve (44%) of 27 patients showed test scores significantly above normal. The axes of bipolarity determined by the testing differed widely between the patients with abnormal scores, compatible with the notion that different alterations in visual pigment genes occur in different AMN kindreds. These observations confirm our earlier impression that the frequency of abnormal color vision is increased in these kindreds, and it supports our contentions that (1) AMN (and its companion, adrenoleukodystrophy) are very closely linked to the visual pigment loci at Xq28 and (2) this proximity might provide the opportunity to observe contiguous gene defects. PMID:2729274

Development of an immersive virtual reality head-mounted display with high performance.

PubMed

Wang, Yunqi; Liu, Weiqi; Meng, Xiangxiang; Fu, Hanyi; Zhang, Daliang; Kang, Yusi; Feng, Rui; Wei, Zhonglun; Zhu, Xiuqing; Jiang, Guohua

2016-09-01

To resolve the contradiction between large field of view and high resolution in immersive virtual reality (VR) head-mounted displays (HMDs), an HMD monocular optical system with a large field of view and high resolution was designed. The system was fabricated by adopting aspheric technology with CNC grinding and a high-resolution LCD as the image source. With this monocular optical system, an HMD binocular optical system with a wide-range continuously adjustable interpupillary distance was achieved in the form of partially overlapping fields of view (FOV) combined with a screw adjustment mechanism. A fast image processor-centered LCD driver circuit and an image preprocessing system were also built to address binocular vision inconsistency in the partially overlapping FOV binocular optical system. The distortions of the HMD optical system with a large field of view were measured. Meanwhile, the optical distortions in the display and the trapezoidal distortions introduced during image processing were corrected by a calibration model for reverse rotations and translations. A high-performance not-fully-transparent VR HMD device with high resolution (1920×1080) and large FOV [141.6°(H)×73.08°(V)] was developed. The full field-of-view average value of angular resolution is 18.6  pixels/degree. With the device, high-quality VR simulations can be completed under various scenarios, and the device can be utilized for simulated trainings in aeronautics, astronautics, and other fields with corresponding platforms. The developed device has positive practical significance.

Short exposure to telestereoscope affects the oculomotor system.

PubMed

Neveu, Pascaline; Priot, Anne-Emmanuelle; Plantier, Justin; Roumes, Corinne

2010-11-01

Under natural viewing conditions, the accommodation and vergence systems adjust the focus and the binocular alignment of the eyes in response to changes in viewing distance. The two responses are linked via cross-coupling and proceed almost simultaneously. Some optical devices, such as virtual reality or helmet mounted displays, create an oculomotor conflict by modifying demands on both vergence and accommodation. Previous studies extensively investigated the effect of such a conflict on the cross-coupling between vergence and accommodation, but little is known about the plasticity of the whole oculomotor system. In the present study, an oculomotor conflict was induced by a telestereoscope which magnified the standard inter-pupillary separation threefold and thus increased the convergence demand while accommodation remained almost unchanged. The effect of a 10 min exposure was assessed via a series of optometric parameters selected on the basis of existing oculomotor models. Associated with subject's visual complaints, most of the oculomotor parameters tested were modified: there was (1) deterioration of stereoscopic threshold; (2) increase in AC/A ratio; (3) increase in near and far phorias; and (4) shift of the zone of clear and single binocular vision towards convergence. These results showed a change in gain of accommodative vergence and a shift of vergence reserves towards convergence in response to telestereoscopic viewing. The subject's binocular behaviour tended towards esophoria with convergence excess as confirmed by Sheard's and Percival's criteria. Such changes in oculomotor parameters support adaptive behaviour linked with telestereoscopic viewing. © 2010 IRBA.

Temporal accommodation response measured by photorefractive accommodation measurement device

NASA Astrophysics Data System (ADS)

Song, Byoungsub; Leportier, Thibault; Park, Min-Chul

2017-02-01

Although accommodation response plays an important role in the human vision system for perception of distance, some three-dimensional (3D) displays offer depth stimuli regardless of the accommodation response. The consequence is that most observers watching 3D displays have complained about visual fatigue. The measurement of the accommodation response is therefore necessary to develop human-friendly 3D displays. However, only few studies about accommodation measurement have been reported. Most of the investigations have been focused on the measurement and analysis of monocular accommodation responses only because the accommodation response works individually in each eye. Moreover, a main eye perceives dominantly the object distance. However, the binocular accommodation response should be examined because both eyes are used to watch the 3D display in natural conditions. The ophthalmic instrument that we developed enabled to measure changes in the accommodation response of the two eyes simultaneously. Two cameras acquired separately the infrared images reflected from each eyes after the reflected beams passed through a cylindrical lens. The changes in the accommodation response could then be estimated from the changes in the astigmatism ratio of the infrared images that were acquired in real time. In this paper, we compared the accommodation responses of main eye between the monocular and the binocular conditions. The two eyes were measured one by one, with only one eye opened, during measurement for monocular condition. Then the two eyes were examined simultaneously for binocular condition. The results showed similar tendencies for main eye accommodation response in both cases.

Retinal image quality and visual stimuli processing by simulation of partial eye cataract

NASA Astrophysics Data System (ADS)

Ozolinsh, Maris; Danilenko, Olga; Zavjalova, Varvara

2016-10-01

Visual stimuli were demonstrated on a 4.3'' mobile phone screen inside a "Virtual Reality" adapter that allowed separation of the left and right eye visual fields. Contrast of the retina image thus can be controlled by the image on the phone screen and parallel to that at appropriate geometry by the AC voltage applied to scattering PDLC cell inside the adapter. Such optical pathway separation allows to demonstrate to both eyes spatially variant images, that after visual binocular fusion acquire their characteristic indications. As visual stimuli we used grey and different color (two opponent components to vision - red-green in L*a*b* color space) spatially periodical stimuli for left and right eyes; and with spatial content that by addition or subtraction resulted as clockwise or counter clockwise slanted Gabor gratings. We performed computer modeling with numerical addition or subtraction of signals similar to processing in brain via stimuli input decomposition in luminance and color opponency components. It revealed the dependence of the perception psychophysical equilibrium point between clockwise or counter clockwise perception of summation on one eye image contrast and color saturation, and on the strength of the retinal aftereffects. Existence of a psychophysical equilibrium point in perception of summation is only in the presence of a prior adaptation to a slanted periodical grating and at the appropriate slant orientation of adaptation grating and/or at appropriate spatial grating pattern phase according to grating nods. Actual observer perception experiments when one eye images were deteriorated by simulated cataract approved the shift of mentioned psychophysical equilibrium point on the degree of artificial cataract. We analyzed also the mobile devices stimuli emission spectra paying attention to areas sensitive to macula pigments absorption spectral maxima and blue areas where the intense irradiation can cause in abnormalities in periodic melatonin regeneration and deviations in regular circadian rhythms. Therefore participants in vision studies using "Virtual Reality" appliances with fixed vision fields and emitting a spike liked spectral bands (on basis of OLED and AMOLED diodes) different from spectra of ambient illuminators should be accordingly warned about potential health risks.

Resource Letter CCV-1: Color and Color Vision.

ERIC Educational Resources Information Center

Stuewer, Roger H., Ed.; Pease, Paul L.

1980-01-01

Listed are selected resource materials on color vision and the measurement and specification of the stimulus for vision, photometry, and colorimetry. The author's purpose is to equip teachers and students with an understanding of normal and abnormal color vision. References are categorized relative to content level. (Author/DS)

The handicap of abnormal colour vision.

PubMed

Cole, Barry L

2004-07-01

All people with abnormal colour vision, except for a few mildly affected deuteranomals, report that they experience problems with colour in everyday life and at work. Contemporary society presents them with increasing problems because colour is now so widely used in printed materials and in computer displays. Equal opportunity law gives them protection against unfair discrimination in employment, so a decision to exclude a person from employment on the grounds of abnormal colour vision must now be well supported by good evidence and sound argument. This paper reviews the investigations that have contributed to understanding the nature and consequences of the problems they have. All those with abnormal colour vision are at a disadvantage with comparative colour tasks that involve precise matching of colours or discrimination of fine colour differences either because of their loss of colour discrimination or anomalous perception of metamers. The majority have problems when colour is used to code information, in man-made colour codes and in naturally occurring colour codes that signal ripeness of fruit, freshness of meat or illness. They can be denied the benefit of colour to mark out objects and organise complex visual displays. They may be unreliable when a colour name is used as an identifier. They are slower and less successful in search when colour is an attribute of the target object or is used to organise the visual display. Because those with the more severe forms of abnormal colour vision perceive a very limited gamut of colours, they are at a disadvantage in the pursuit and appreciation of those forms of art that use colour.

From optics to attention: visual perception in barn owls.

PubMed

Harmening, Wolf M; Wagner, Hermann

2011-11-01

Barn owls are nocturnal predators which have evolved specific sensory and morphological adaptations to a life in dim light. Here, some of the most fundamental properties of spatial vision in barn owls are reviewed. The eye with its tubular shape is rigidly integrated in the skull so that eye movements are very much restricted. The eyes are oriented frontally, allowing for a large binocular overlap. Accommodation, but not pupil dilation, is coupled between the two eyes. The retina is rod dominated and lacks a visible fovea. Retinal ganglion cells form a marked region of highest density that extends to a horizontally oriented visual streak. Behavioural visual acuity and contrast sensitivity are poor, although the optical quality of the ocular media is excellent. A low f-number allows high image quality at low light levels. Vernier acuity was found to be a hyperacute percept. Owls have global stereopsis with hyperacute stereo acuity thresholds. Neurons of the visual Wulst are sensitive to binocular disparities. Orientation based saliency was demonstrated in a visual-search experiment, and higher cognitive abilities were shown when the owl's were able to use illusory contours for object discrimination.

Spatial contrast sensitivity at twilight: luminance, monocularity, and oxygenation.

PubMed

Connolly, Desmond M

2010-05-01

Visual performance in dim light is compromised by lack of oxygen (hypoxia). The possible influence of altered oxygenation on foveal contrast sensitivity under mesopic (twilight) viewing conditions is relevant to aircrew flying at night, including when using night vision devices, but is poorly documented. Foveal contrast sensitivity was measured binocularly and monocularly in 12 subjects at 7 spatial frequencies, ranging from 0.5 to approximately 16 cycles per degree, using sinusoidal Gabor patch gratings. Hypoxic performance breathing 14.1% oxygen, equivalent to altitude exposure at 3048 m (10,000 ft), was compared with breathing air at sea level (normoxia) at low photopic (28 cd x m(-2)), borderline upper mesopic (approximately 2.1 cd x m(-2)) and midmesopic (approximately 0.26 cd x m(-2)) luminance. Mesopic performance was also assessed breathing 100% oxygen (hyperoxia). Typical 'inverted U' log/log plots of the contrast sensitivity function were obtained, with elevated thresholds (reduced sensitivity) at lower luminance. Binocular viewing enhanced sensitivity by a factor approximating square root of 2 for most conditions, supporting neural summation of the contrast signal, but had greater influence at the lowest light level and highest spatial frequencies (8.26 and 16.51 cpd). Respiratory challenges had no effect. Contrast sensitivity is poorer when viewing monocularly and especially at midmesopic luminance, with relevance to night flying. The foveal contrast sensitivity function is unaffected by respiratory disturbance when twilight conditions favor cone vision, despite known effects on retinal illumination (pupil size). The resilience of the contrast sensitivity function belies the vulnerability of foveal low contrast acuity to mild hypoxia at mesopic luminance.

The impact of prism adaptation test on surgical outcomes in patients with primary exotropia.

PubMed

Kiyak Yilmaz, Ayse; Kose, Suheyla; Guven Yilmaz, Suzan; Uretmen, Onder

2015-05-01

We aimed to determine the impact of the preoperative prism adaptation test (PAT) on surgical outcomes in patients with primary exotropia. Thirty-eight consecutive patients with primary exotropia were enrolled. Pre-operative PAT was performed in 18 randomly selected patients (Group 1). Surgery was based on the angle of deviation at distance measured after PAT. The remaining 20 patients in whom PAT was not performed comprised Group 2. Surgery was based on the angle of deviation at distance in these patients. Surgical success was defined as ocular alignment within eight prism dioptres (PD) of orthophoria. Satisfactory motor alignment (± 8 PD) was achieved in 16 Group 1 patients (88.9 per cent) and 16 Group 2 patients (80 per cent) one year after surgery (p = 0.6; chi-square test). There were no statistically significant differences in demographic parameters, pre-operative and post-operative angle of deviation between the two groups (p > 0.05; Mann-Whitney U and chi-square tests). Nine patients in Group 1 (50 per cent) and two patients in Group 2 (10 per cent) had increased binocular vision one year post-operatively. A statistically significant difference was determined in terms of change in binocular single vision between the two groups (p = 0.01; chi-square test). Although the prism adaptation test did not lead to a significant increment in motor success, it may be helpful in achieving a more favourable functional surgical outcome in patients with primary exotropia. © 2014 The Authors. Clinical and Experimental Optometry © 2014 Optometrists Association Australia.

Assessment of Grating Acuity in Infants and Toddlers Using an Electronic Acuity Card: The Dobson Card.

PubMed

Mohan, Kathleen M; Miller, Joseph M; Harvey, Erin M; Gerhart, Kimberly D; Apple, Howard P; Apple, Deborah; Smith, Jordana M; Davis, Amy L; Leonard-Green, Tina; Campus, Irene; Dennis, Leslie K

2016-01-01

To determine if testing binocular visual acuity in infants and toddlers using the Acuity Card Procedure (ACP) with electronic grating stimuli yields clinically useful data. Participants were infants and toddlers ages 5 to 36.7 months referred by pediatricians due to failed automated vision screening. The ACP was used to test binocular grating acuity. Stimuli were presented on the Dobson Card. The Dobson Card consists of a handheld matte-black plexiglass frame with two flush-mounted tablet computers and is similar in size and form to commercially available printed grating acuity testing stimuli (Teller Acuity Cards II [TACII]; Stereo Optical, Inc., Chicago, IL). On each trial, one tablet displayed a square-wave grating and the other displayed a luminance-matched uniform gray patch. Stimuli were roughly equivalent to the stimuli available in the printed TACII stimuli. After acuity testing, each child received a cycloplegic eye examination. Based on cycloplegic retinoscopy, patients were categorized as having high or low refractive error per American Association for Pediatric Ophthalmology and Strabismus vision screening referral criteria. Mean acuities for high and low refractive error groups were compared using analysis of covariance, controlling for age. Mean visual acuity was significantly poorer in children with high refractive error than in those with low refractive error (P = .015). Electronic stimuli presented using the ACP can yield clinically useful measurements of grating acuity in infants and toddlers. Further research is needed to determine the optimal conditions and procedures for obtaining accurate and clinically useful automated measurements of visual acuity in infants and toddlers. Copyright 2016, SLACK Incorporated.

Uncorrected refractive errors, presbyopia and spectacle coverage: results from a rapid assessment of refractive error survey.

PubMed

Marmamula, Srinivas; Keeffe, Jill E; Rao, Gullapalli N

2009-01-01

To investigate the prevalence of uncorrected refractive errors, presbyopia and spectacle coverage in subjects aged 15-50 years using rapid assessment methodology in the Mahabubnagar district of Andhra Pradesh, India. A population-based cross sectional study was conducted using cluster random sampling to enumerate 3,300 subjects from 55 clusters. Unaided, aided and pinhole visual acuity was assessed using a LogMAR chart at a distance of 4 meters. Near vision was assessed using N notation chart. Uncorrected refractive error was defined as presenting visual acuity worse than 6/12 but improving to at least 6/12 or better on using a pinhole. Presbyopia is defined as binocular near vision worse than N8 in subjects aged more than 35 years with binocular distance visual acuity of 6/12 or better. Of the 3,300 subjects enumerated from 55 clusters, 3,203 (97%) subjects were available for examination. Of these, 1,496 (46.7%) were females and 930 (29%) were > or = 40 years. Age and gender adjusted prevalence of uncorrected refractive errors causing visual impairment in the better eye was 2.7% (95% CI, 2.1-3.2%). Presbyopia was present in 690 (63.7%, 95% CI, 60.8-66.6%) subjects aged over 35 years. Spectacle coverage for refractive error was 29% and for presbyopia it was 19%. There is a large unmet need for refractive correction in this area in India. Rapid assessment methods are an effective means of assessing the need for services and the impact of models of care.

Reliability of Snellen charts for testing visual acuity for driving: prospective study and postal questionnaire

PubMed Central

Currie, Zanna; Bhan, Archana; Pepper, Irene

2000-01-01

Objectives To assess the ability of patients with binocular 6/9 or 6/12 vision on the Snellen chart (Snellen acuity) to read a number plate at 20.5 m (the required standard for driving) and to determine how health professionals advise such patients about driving. Design Prospective study of patients and postal questionnaire to healthcare professionals. Subjects 50 patients with 6/9 vision and 50 with 6/12 vision and 100 general practitioners, 100 optometrists or opticians, and 100 ophthalmologists. Setting Ophthalmology outpatient clinics in Sheffield. Main outcome measures Ability to read a number plate at 20.5 m and health professionals' advice about driving on the basis of visual acuity. Results 26% of patients with 6/9 vision failed the number plate test, and 34% with 6/12 vision passed it. Of the general practitioners advising patients with 6/9 vision, 76% said the patients could drive, 13% said they should not drive, and 11% were unsure. Of the general practitioners advising patients with 6/12 vision, 21% said the patients could drive, 54% said they should not drive, and 25% were unsure. The level of acuity at which optometrists, opticians, and ophthalmologists would advise drivers against driving ranged from 6/9−2 (ability to read all except two letters on the 6/9 line of the Snellen chart) to less than 6/18. Conclusions Snellen acuity is a poor predictor of an individual's ability to meet the required visual standard for driving. Patients with 6/9 vision or less should be warned that they may fail to meet this standard, but those with 6/12 vision should not be assumed to be below the standard. PMID:11039964

The iPod binocular home-based treatment for amblyopia in adults: efficacy and compliance.

PubMed

Hess, Robert F; Babu, Raiju Jacob; Clavagnier, Simon; Black, Joanna; Bobier, William; Thompson, Benjamin

2014-09-01

Occlusion therapy for amblyopia is predicated on the idea that amblyopia is primarily a disorder of monocular vision; however, there is growing evidence that patients with amblyopia have a structurally intact binocular visual system that is rendered functionally monocular due to suppression. Furthermore, we have found that a dichoptic treatment intervention designed to directly target suppression can result in clinically significant improvement in both binocular and monocular visual function in adult patients with amblyopia. The fact that monocular improvement occurs in the absence of any fellow eye occlusion suggests that amblyopia is, in part, due to chronic suppression. Previously the treatment has been administered as a psychophysical task and more recently as a video game that can be played on video goggles or an iPod device equipped with a lenticular screen. The aim of this case-series study of 14 amblyopes (six strabismics, six anisometropes and two mixed) ages 13 to 50 years was to investigate: 1. whether the portable video game treatment is suitable for at-home use and 2. whether an anaglyphic version of the iPod-based video game, which is more convenient for at-home use, has comparable effects to the lenticular version. The dichoptic video game treatment was conducted at home and visual functions assessed before and after treatment. We found that at-home use for 10 to 30 hours restored simultaneous binocular perception in 13 of 14 cases along with significant improvements in acuity (0.11 ± 0.08 logMAR) and stereopsis (0.6 ± 0.5 log units). Furthermore, the anaglyph and lenticular platforms were equally effective. In addition, the iPod devices were able to record a complete and accurate picture of treatment compliance. The home-based dichoptic iPod approach represents a viable treatment for adults with amblyopia. © 2014 The Authors. Clinical and Experimental Optometry © 2014 Optometrists Association Australia.

'I didn't see that coming': simulated visual fields and driving hazard perception test performance.

PubMed

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

2016-09-01

Evidence is limited regarding specific types of visual field loss associated with unsafe driving. We use novel gaze-contingent software to examine the effect of simulated visual field loss on computer-based driving hazard detection with the specific aim of testing the impact of scotomata located to the right and left of fixation. The 'hazard perception test' is a component of the UK driving licence examination, which measures speed of detecting 15 different hazards in a series of real-life driving films. We have developed a novel eye-tracking and computer set up capable of generating a realistic gaze-contingent scotoma simulation (GazeSS) overlaid on film content. Thirty drivers with healthy vision completed three versions of the hazard perception test in a repeated measures experiment. In two versions, GazeSS simulated a scotoma in the binocular field of view to the left or right of fixation. A third version was unmodified to establish baseline performance. Participants' mean baseline hazard perception test score was 51 ± 7 (out of 75). This reduced to 46 ± 9 and 46 ± 11 when completing the task with a binocular visual field defect located to the left and right of fixation, respectively. While the main effect of simulated visual field loss on performance was statistically significant (p = 0.007), there were no average differences in the experimental conditions where a scotoma was located in the binocular visual field to the right or left of fixation. Simulated visual field loss impairs driving hazard detection on a computer-based test. There was no statistically significant difference in average performance when the simulated scotoma was located to the right or left of fixation of the binocular visual field, but certain types of hazard caused more difficulties than others. © 2016 Optometry Australia.

Comparison of tests of accommodation for computer users.

PubMed

Kolker, David; Hutchinson, Robert; Nilsen, Erik

2002-04-01

With the increased use of computers in the workplace and at home, optometrists are finding more patients presenting with symptoms of Computer Vision Syndrome. Among these symptomatic individuals, research supports that accommodative disorders are the most common vision finding. A prepresbyopic group (N= 30) and a presbyopic group (N = 30) were selected from a private practice. Assignment to a group was determined by age, accommodative amplitude, and near visual acuity with their distance prescription. Each subject was given a thorough vision and ocular health examination, then administered several nearpoint tests of accommodation at a computer working distance. All the tests produced similar results in the presbyopic group. For the prepresbyopic group, the tests yielded very different results. To effectively treat symptomatic VDT users, optometrists must assess the accommodative system along with the binocular and refractive status. For presbyopic patients, all nearpoint tests studied will yield virtually the same result. However, the method of testing accommodation, as well as the test stimulus presented, will yield significantly different responses for prepresbyopic patients. Previous research indicates that a majority of patients prefer the higher plus prescription yielded by the Gaussian image test.

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

NASA Astrophysics Data System (ADS)

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

2018-01-01

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

The effects of absence of stereopsis on performance of a simulated surgical task in two-dimensional and three-dimensional viewing conditions

PubMed Central

Bloch, Edward; Uddin, Nabil; Gannon, Laura; Rantell, Khadija; Jain, Saurabh

2015-01-01

Background Stereopsis is believed to be advantageous for surgical tasks that require precise hand-eye coordination. We investigated the effects of short-term and long-term absence of stereopsis on motor task performance in three-dimensional (3D) and two-dimensional (2D) viewing conditions. Methods 30 participants with normal stereopsis and 15 participants with absent stereopsis performed a simulated surgical task both in free space under direct vision (3D) and via a monitor (2D), with both eyes open and one eye covered in each condition. Results The stereo-normal group scored higher, on average, than the stereo-absent group with both eyes open under direct vision (p<0.001). Both groups performed comparably in monocular and binocular monitor viewing conditions (p=0.579). Conclusions High-grade stereopsis confers an advantage when performing a fine motor task under direct vision. However, stereopsis does not appear advantageous to task performance under 2D viewing conditions, such as in video-assisted surgery. PMID:25185439

GPU-based real-time trinocular stereo vision

NASA Astrophysics Data System (ADS)

Yao, Yuanbin; Linton, R. J.; Padir, Taskin

2013-01-01

Most stereovision applications are binocular which uses information from a 2-camera array to perform stereo matching and compute the depth image. Trinocular stereovision with a 3-camera array has been proved to provide higher accuracy in stereo matching which could benefit applications like distance finding, object recognition, and detection. This paper presents a real-time stereovision algorithm implemented on a GPGPU (General-purpose graphics processing unit) using a trinocular stereovision camera array. Algorithm employs a winner-take-all method applied to perform fusion of disparities in different directions following various image processing techniques to obtain the depth information. The goal of the algorithm is to achieve real-time processing speed with the help of a GPGPU involving the use of Open Source Computer Vision Library (OpenCV) in C++ and NVidia CUDA GPGPU Solution. The results are compared in accuracy and speed to verify the improvement.

Vision-Based Real-Time Traversable Region Detection for Mobile Robot in the Outdoors.

PubMed

Deng, Fucheng; Zhu, Xiaorui; He, Chao

2017-09-13

Environment perception is essential for autonomous mobile robots in human-robot coexisting outdoor environments. One of the important tasks for such intelligent robots is to autonomously detect the traversable region in an unstructured 3D real world. The main drawback of most existing methods is that of high computational complexity. Hence, this paper proposes a binocular vision-based, real-time solution for detecting traversable region in the outdoors. In the proposed method, an appearance model based on multivariate Gaussian is quickly constructed from a sample region in the left image adaptively determined by the vanishing point and dominant borders. Then, a fast, self-supervised segmentation scheme is proposed to classify the traversable and non-traversable regions. The proposed method is evaluated on public datasets as well as a real mobile robot. Implementation on the mobile robot has shown its ability in the real-time navigation applications.

Mobility performance in glaucoma.

PubMed

Turano, K A; Rubin, G S; Quigley, H A

1999-11-01

To determine whether glaucoma affects mobility performance and whether there is a relationship between mobility performance and stage of disease as estimated from vision-function measures. The mobility performance of 47 glaucoma subjects was compared with that of 47 normal-vision subjects who were of similar age. Mobility performance was assessed by the time required to complete an established travel path and the number of mobility incidents. The subjective assessment of falling and fear of falling were also compared. Vision function was assessed by measures of visual acuity, contrast sensitivity, monocular automated threshold perimetry, and suprathreshold; binocular visual fields were assessed with the Esterman test. The glaucoma subjects walked on average 10% more slowly than did the normal-vision subjects. The number of people who experienced bumps, stumbles, or orientation problems was almost twice as high in the glaucoma group than the normal-vision group, but the difference did not reach statistical significance. The difference between groups also was not significant with respect to the number of people who reported falling in the past year (38% for the glaucoma group and 30% for the normal-vision group) or a fear of falling (28% for the glaucoma group and 23% for the normal-vision group). The visual fields assessed with a Humphrey 24-2 test were more highly correlated with walking speed in glaucoma than the visual fields scored by the Esterman scale or than visual acuity or contrast sensitivity. Glaucoma is associated with a modest decrease in mobility performance. Walking speed decreases with severity of the disease as estimated by threshold perimetry.

Visual performance after bilateral implantation of 2 new presbyopia-correcting intraocular lenses: Trifocal versus extended range of vision.

PubMed

Monaco, Gaspare; Gari, Mariangela; Di Censo, Fabio; Poscia, Andrea; Ruggi, Giada; Scialdone, Antonio

2017-06-01

To compare the visual outcomes and quality of vision of 2 new diffractive multifocal intraocular lenses (IOLs) with those of a monofocal IOL. Fatebenefratelli e Oftalmico Hospital, Milan, Italy. Prospective case series. Patients had bilateral cataract surgery with implantation of a trifocal IOL (Panoptix), an extended-range-of-vision IOL (Symfony), or a monofocal IOL (SN60WF). Postoperative examinations included assessing distance, intermediate, and near visual acuity; binocular defocus; intraocular and total aberrations; point-spread function (PSF); modulation transfer function (MTF); retinal straylight; and quality-of-vision (QoV) and spectacle-dependence questionnaires. Seventy-six patients (152 eyes) were assessed for study eligibility. Twenty patients (40 eyes) in each arm of the study (60 patients, 120 eyes) completed the outcome assessment. At the 4-month follow-up, the trifocal group had significantly better near visual acuity than the extended-range-of-vision group (P = .005). The defocus curve showed the trifocal IOL had better intermediate/near performance than the extended-range-of-vision IOL and both multifocal IOLs performed better than the monofocal IOL. Intragroup comparison of the total higher-order aberrations, PSF, MTF, and retinal straylight were not statistically different. The QoV questionnaire results showed no differences in dysphotopsia between the multifocal IOL groups; however, the results were significantly higher than in the monofocal IOL group. Both multifocal IOLs seemed to be good options for patients with intermediate-vision requirements, whereas the trifocal IOL might be better for patients with near-vision requirements. The significant perception of visual side effects indicates that patients still must be counseled about these effects before a multifocal IOL is implanted. Copyright © 2017 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Correlation Between Near-Vision Acuity and the Incidence of Peritoneal Dialysis-Related Infections.

PubMed

Kojima, Shigeki; Sakurada, Tsutomu; Koitabashi, Kenichiro; Kojima, Kaori; Watanabe, Shiika; Uchida, Daisuke; Kaneshiro, Nagayuki; Konno, Yusuke; Shibagaki, Yugo

Peritoneal dialysis (PD)-related infections (PDIs) such as peritonitis, exit-site infection, and tunnel infection are serious complications affecting patients on PD. Because patients with diabetes (DM) and of older age have increased in number in Japan, the number of patients with visual impairment is estimated also to have increased. Near vision is necessary for performing proper PD daily care. However, no studies have reported whether visual impairment is likely to increase the risk of PDIs.Our study included 31 PD patients (16 men, 15 women; mean age: 61.5 ± 11.8 years; mean PD duration: 27.3 ± 20.3 months; 38.7% with DM; 54.8% wearing glasses) who performed their own PD care. At our facility and related facilities, we used a standard near-vision test chart, which classifies vision into 12 grades, from 0.1 (poor) to 1.5 (clear), to assess near-vision binocular visual acuity in those patients between March 2015 and September 2015. In addition, we retrospectively examined the medical records of the patients to determine their history of PDIs. We then evaluated the correlation between near-vision acuity and the incidence of PDIs.Mean measured near-vision acuity was 0.61 ± 0.29, and we observed no significant difference in the visual acuity of patients with and without DM (0.55 ± 0.31 vs. 0.63 ± 0.26 respectively, p = 0.477). In addition, we observed no significant difference in the incidence of PDIs between patients with and without DM (1.298 ± 1.609 per year vs. 1.164 ± 0.908 per year respectively, p = 0.804). We did not find a correlation between near-vision acuity and the incidence of PDIs (r = -0.071, p = 0.795).

Optical devices in highly myopic eyes with low vision: a prospective study.

PubMed

Scassa, C; Cupo, G; Bruno, M; Iervolino, R; Capozzi, S; Tempesta, C; Giusti, C

2012-01-01

To compare, in relation to the cause of visual impairment, the possibility of rehabilitation, the corrective systems already in use and the finally prescribed optical devices in highly myopic patients with low vision. Some considerations about the rehabilitation of these subjects, especially in relation to their different pathologies, have also been made. 25 highly myopic subjects were enrolled. We evaluated both visual acuity and retinal sensitivity by Scanning Laser Ophthalmoscope (SLO) microperimetry. 20 patients (80%) were rehabilitated by means of monocular optical devices while five patients (20%) were rehabilitated binocularly. We found a good correlation between visual acuity and retinal sensitivity only when the macular pathology did not induce large areas of chorioretinal atrophy that cause lack of stabilization of the preferential retinal locus. In fact, the best results in reading and performing daily visual tasks were obtained by maximizing the residual vision in patients with retinal sensitivity greater than 10 dB. A well circumscribed area of absolute scotoma with a defined new retinal fixation locus could be considered as a positive predictive factor for the final rehabilitation process. A more careful evaluation of visual acuity, retinal sensitivity and preferential fixation locus is necessary in order to prescribe the best optical devices to patients with low vision, thus reducing the impact of the disability on their daily life.

Using virtual reality to test the regularity priors used by the human visual system

NASA Astrophysics Data System (ADS)

Palmer, Eric; Kwon, TaeKyu; Pizlo, Zygmunt

2017-09-01

Virtual reality applications provide an opportunity to test human vision in well-controlled scenarios that would be difficult to generate in real physical spaces. This paper presents a study intended to evaluate the importance of the regularity priors used by the human visual system. Using a CAVE simulation, subjects viewed virtual objects in a variety of experimental manipulations. In the first experiment, the subject was asked to count the objects in a scene that was viewed either right-side-up or upside-down for 4 seconds. The subject counted more accurately in the right-side-up condition regardless of the presence of binocular disparity or color. In the second experiment, the subject was asked to reconstruct the scene from a different viewpoint. Reconstructions were accurate, but the position and orientation error was twice as high when the scene was rotated by 45°, compared to 22.5°. Similarly to the first experiment, there was little difference between monocular and binocular viewing. In the third experiment, the subject was asked to adjust the position of one object to match the depth extent to the frontal extent among three objects. Performance was best with symmetrical objects and became poorer with asymmetrical objects and poorest with only small circular markers on the floor. Finally, in the fourth experiment, we demonstrated reliable performance in monocular and binocular recovery of 3D shapes of objects standing naturally on the simulated horizontal floor. Based on these results, we conclude that gravity, horizontal ground, and symmetry priors play an important role in veridical perception of scenes.

Perceptual Learning Improves Stereoacuity in Amblyopia

PubMed Central

Xi, Jie; Jia, Wu-Li; Feng, Li-Xia; Lu, Zhong-Lin; Huang, Chang-Bing

2014-01-01

Purpose. Amblyopia is a developmental disorder that results in both monocular and binocular deficits. Although traditional treatment in clinical practice (i.e., refractive correction, or occlusion by patching and penalization of the fellow eye) is effective in restoring monocular visual acuity, there is little information on how binocular function, especially stereopsis, responds to traditional amblyopia treatment. We aim to evaluate the effects of perceptual learning on stereopsis in observers with amblyopia in the current study. Methods. Eleven observers (21.1 ± 5.1 years, six females) with anisometropic or ametropic amblyopia were trained to judge depth in 10 to 13 sessions. Red–green glasses were used to present three different texture anaglyphs with different disparities but a fixed exposure duration. Stereoacuity was assessed with the Fly Stereo Acuity Test and visual acuity was assessed with the Chinese Tumbling E Chart before and after training. Results. Averaged across observers, training significantly reduced disparity threshold from 776.7″ to 490.4″ (P < 0.01) and improved stereoacuity from 200.3″ to 81.6″ (P < 0.01). Interestingly, visual acuity also significantly improved from 0.44 to 0.35 logMAR (approximately 0.9 lines, P < 0.05) in the amblyopic eye after training. Moreover, the learning effects in two of the three retested observers were largely retained over a 5-month period. Conclusions. Perceptual learning is effective in improving stereo vision in observers with amblyopia. These results, together with previous evidence, suggest that structured monocular and binocular training might be necessary to fully recover degraded visual functions in amblyopia. Chinese Abstract PMID:24508791

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

PubMed

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

2013-09-09

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

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

PubMed

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

1982-11-04

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

Perceptual learning improves stereoacuity in amblyopia.

PubMed

Xi, Jie; Jia, Wu-Li; Feng, Li-Xia; Lu, Zhong-Lin; Huang, Chang-Bing

2014-04-15

Amblyopia is a developmental disorder that results in both monocular and binocular deficits. Although traditional treatment in clinical practice (i.e., refractive correction, or occlusion by patching and penalization of the fellow eye) is effective in restoring monocular visual acuity, there is little information on how binocular function, especially stereopsis, responds to traditional amblyopia treatment. We aim to evaluate the effects of perceptual learning on stereopsis in observers with amblyopia in the current study. Eleven observers (21.1 ± 5.1 years, six females) with anisometropic or ametropic amblyopia were trained to judge depth in 10 to 13 sessions. Red-green glasses were used to present three different texture anaglyphs with different disparities but a fixed exposure duration. Stereoacuity was assessed with the Fly Stereo Acuity Test and visual acuity was assessed with the Chinese Tumbling E Chart before and after training. Averaged across observers, training significantly reduced disparity threshold from 776.7″ to 490.4″ (P < 0.01) and improved stereoacuity from 200.3″ to 81.6″ (P < 0.01). Interestingly, visual acuity also significantly improved from 0.44 to 0.35 logMAR (approximately 0.9 lines, P < 0.05) in the amblyopic eye after training. Moreover, the learning effects in two of the three retested observers were largely retained over a 5-month period. Perceptual learning is effective in improving stereo vision in observers with amblyopia. These results, together with previous evidence, suggest that structured monocular and binocular training might be necessary to fully recover degraded visual functions in amblyopia. Chinese Abstract.

Is Male Migraine Associated With Color Vision Deficiency? Findings Among Israeli Adolescents Between 2007 and 2013.

PubMed

Berger, Assaf; Findler, Michael; Korach, Tzfanya; Yativ, Oshrat Fono; Gronovich, Yoav; Hassidim, Ayal

2016-04-01

Accumulating clinical and experimental evidence has shown that migraine patients tend to suffer from color vision abnormalities. The aim of this study was to examine whether color vision deficiency is associated with male migraine in a large population of adolescents. The study population included all Israeli male adolescents who underwent medical and cognitive examinations as part of their recruiting process between the years 2007 and 2013. Migraine prevalence among patients with color vision deficiency was compared to that of males without substantial color vision abnormalities. The study population included 305 964 male adolescents at the age of 17 ± 0.6, of whom 7584 (2.5%) had color vision deficiency, as determined by the Farnsworth Panel D-15 color blindness test. Males with color vision deficiency had a 32% increased prevalence of migraine as compared with the control group (odds ratio 1.32, 95% confidence interval 1.18-1.48, P < .001), after adjusting for multiple variables. The authors found an association between color vision deficiency and migraine in male adolescents. The study results lay the basis for further research into male migraine, as well as the visual aspects of migraine. © The Author(s) 2015.

Function of transected or avulsed rectus muscles following recovery using an anterior orbitotomy approach.

PubMed

Pineles, Stacy L; Laursen, Jessica; Goldberg, Robert A; Demer, Joseph L; Velez, Federico G

2012-08-01

To assess the function of muscles retrieved from a retrobulbar location using an anterior orbitotomy approach and to identify the prognostic factors favoring a good outcome. The records of all patients undergoing anterior orbitotomy for the retrieval of a transected or avulsed muscle in a retrobulbar location were reviewed. Ocular motility, before and after retrieval (with ductions scaled from -4 to +4), was evaluated. Record review identified 11 patients who had suffered trauma to 12 muscles (5 inferior, 6 medial, and 1 lateral rectus muscle). Ductions improved from -4 ± 0.4 preoperatively to -2.7 ± 0.9 postoperatively (P = 0.002); mean primary position deviation improved from 34(Δ) ± 14(Δ)-15(Δ) ± 9(Δ) (P < 0.001), and mean deviation in the field of action improved from 47(Δ) ± 20(Δ)-20(Δ) ± 22(Δ) (P = 0.02). Ductions improved by at least two units in three patients, all of whom had medial rectus trauma. Single binocular vision in primary gaze was achieved in 6 patients. Patients with medial rectus muscle injury and patients injured by sinus surgery had the lowest likelihood of recovering single binocular vision. Our results are similar to historical series in which muscles were not retrieved and transpositions performed; however, muscle retrieval avoids risks associated with transposition surgeries such as anterior segment ischemia. Muscle recovery via the anterior orbitotomy approach may be reasonable to consider in those cases with a reasonable possibility of having active force generation postoperatively. Copyright © 2012 American Association for Pediatric Ophthalmology and Strabismus. Published by Mosby, Inc. All rights reserved.

Evaluation and development of a novel binocular treatment (I-BiT™) system using video clips and interactive games to improve vision in children with amblyopia ('lazy eye'): study protocol for a randomised controlled trial.

PubMed

Foss, Alexander J; Gregson, Richard M; MacKeith, Daisy; Herbison, Nicola; Ash, Isabel M; Cobb, Sue V; Eastgate, Richard M; Hepburn, Trish; Vivian, Anthony; Moore, Diane; Haworth, Stephen M

2013-05-20

Amblyopia (lazy eye) affects the vision of approximately 2% of all children. Traditional treatment consists of wearing a patch over their 'good' eye for a number of hours daily, over several months. This treatment is unpopular and compliance is often low. Therefore results can be poor. A novel binocular treatment which uses 3D technology to present specially developed computer games and video footage (I-BiT™) has been studied in a small group of patients and has shown positive results over a short period of time. The system is therefore now being examined in a randomised clinical trial. Seventy-five patients aged between 4 and 8 years with a diagnosis of amblyopia will be randomised to one of three treatments with a ratio of 1:1:1 - I-BiT™ game, non-I-BiT™ game, and I-BiT™ DVD. They will be treated for 30 minutes once weekly for 6 weeks. Their visual acuity will be assessed independently at baseline, mid-treatment (week 3), at the end of treatment (week 6) and 4 weeks after completing treatment (week 10). The primary endpoint will be the change in visual acuity from baseline to the end of treatment. Secondary endpoints will be additional visual acuity measures, patient acceptability, compliance and the incidence of adverse events. This is the first randomised controlled trial using the I-BiT™ system. The results will determine if the I-BiT™ system is effective in the treatment of amblyopia and will also determine the optimal treatment for future development. ClinicalTrials.gov identifier: NCT01702727.

Evaluating the effect of three-dimensional visualization on force application and performance time during robotics-assisted mitral valve repair.

PubMed

Currie, Maria E; Trejos, Ana Luisa; Rayman, Reiza; Chu, Michael W A; Patel, Rajni; Peters, Terry; Kiaii, Bob B

2013-01-01

The purpose of this study was to determine the effect of three-dimensional (3D) binocular, stereoscopic, and two-dimensional (2D) monocular visualization on robotics-assisted mitral valve annuloplasty versus conventional techniques in an ex vivo animal model. In addition, we sought to determine whether these effects were consistent between novices and experts in robotics-assisted cardiac surgery. A cardiac surgery test-bed was constructed to measure forces applied during mitral valve annuloplasty. Sutures were passed through the porcine mitral valve annulus by the participants with different levels of experience in robotics-assisted surgery and tied in place using both robotics-assisted and conventional surgery techniques. The mean time for both the experts and the novices using 3D visualization was significantly less than that required using 2D vision (P < 0.001). However, there was no significant difference in the maximum force applied by the novices to the mitral valve during suturing (P = 0.7) and suture tying (P = 0.6) using either 2D or 3D visualization. The mean time required and forces applied by both the experts and the novices were significantly less using the conventional surgical technique than when using the robotic system with either 2D or 3D vision (P < 0.001). Despite high-quality binocular images, both the experts and the novices applied significantly more force to the cardiac tissue during 3D robotics-assisted mitral valve annuloplasty than during conventional open mitral valve annuloplasty. This finding suggests that 3D visualization does not fully compensate for the absence of haptic feedback in robotics-assisted cardiac surgery.

Prevalence of uncorrected refractive errors, presbyopia and spectacle coverage in marine fishing communities in South India: Rapid Assessment of Visual Impairment (RAVI) project.

PubMed

Marmamula, Srinivas; Madala, Sreenivas R; Rao, Gullapalli N

2012-03-01

To investigate the prevalence of uncorrected refractive errors, presbyopia and spectacle coverage in subjects aged 40 years or more using a novel Rapid Assessment of Visual Impairment (RAVI) methodology. A population-based cross-sectional study was conducted using cluster random sampling to enumerate 1700 subjects from 34 clusters predominantly inhabited by marine fishing communities in the Prakasam district of Andhra Pradesh, India. Unaided, aided and pinhole visual acuity (VA) was assessed using a Snellen chart at a distance of 6 m. Near vision was assessed using an N notation chart. Uncorrected refractive error was defined as presenting VA < 6/18 and improving to ≥6/18 with pinhole. Uncorrected presbyopia was defined as binocular near vision worse than N8 in subjects with binocular distance VA ≥ 6/18. 1560 subjects (response rate - 92%) were available for examination. Of these, 54.6% were female and 10.1% were ≥70 years of age. Refractive error was present in 250 individuals. It was uncorrected in 179 (unmet need) and corrected in 71 (met need) individuals. Among 1094 individuals with no distance visual impairment, presbyopia was present in 494 individuals. It was uncorrected in 439 (unmet need) and corrected in 55 individuals (met need). Spectacle coverage was 28.4% for refractive errors and 11.1% for presbyopia. There is a high unmet need for uncorrected refractive errors and presbyopia among marine fishing communities in the Prakasam district of South India. The data from this study can now be used as a baseline prior to the commencement of eye care services in this region. Ophthalmic & Physiological Optics © 2012 The College of Optometrists.

Lack of early pattern stimulation prevents normal development of the alpha (Y) retinal ganglion cell population in the cat.

PubMed

Burnat, Kalina; Van Der Gucht, Estelle; Waleszczyk, Wioletta J; Kossut, Malgorzata; Arckens, Lutgarde

2012-08-01

Binocular deprivation of pattern vision (BD) early in life permanently impairs global motion perception. With the SMI-32 antibody against neurofilament protein (NFP) as a marker of the motion-sensitive Y-cell pathway (Van der Gucht et al. [2001] Cereb. Cortex 17:2805-2819), we analyzed the impact of early BD on the retinal circuitry in adult, perceptually characterized cats (Burnat et al. [2005] Neuroreport 16:751-754). In controls, large retinal ganglion cells exhibited a strong NFP signal in the soma and in the proximal parts of the dendritic arbors. The NFP-immunoreactive dendrites typically branched into sublamina a of the inner plexiform layer (IPL), i.e., the OFF inner plexiform sublamina. In the retina of adult BD cats, however, most of the NFP-immunoreactive ganglion cell dendrites branched throughout the entire IPL. The NFP-immunoreactive cell bodies were less regularly distributed, often appeared in pairs, and had a significantly larger diameter compared with NFP-expressing cells in control retinas. These remarkable differences in the immunoreactivity pattern were typically observed in temporal retina. In conclusion, we show that the anatomical organization typical of premature Y-type retinal ganglion cells persists into adulthood even if normal visual experience follows for years upon an initial 6-month period of BD. Binocular pattern deprivation possibly induces a lifelong OFF functional domination, normally apparent only during development, putting early high-quality vision forward as a premise for proper ON-OFF pathway segregation. These new observations for pattern-deprived animals provide an anatomical basis for the well-described motion perception deficits in congenital cataract patients. Copyright © 2012 Wiley Periodicals, Inc.

The effect of abnormal colour vision on the ability to identify and outline coloured clinical signs and to count stained bacilli in sputum.

PubMed

Campbell, John L; Griffin, Lewis; Spalding, J Anthony B; Mir, Fraz A

2005-11-01

To determine if medical practitioners with congenital colour vision deficiencies (CCVD) are less able to identify and delineate the extent of coloured abnormal signs than those with normal colour vision. Twenty-two medical practitioners with CCVD and 17 with normal colour vision, matched for age and gender, were shown 10 photographs. They were asked to identify and outline the extent of the clinical sign in eight that were of vomit or stool (six of these showing fresh blood), one of a skin rash and for one to mark the position of bacilli in sputum stained by the Ziehl-Neelsen method. There were statistically significant differences between the CCVD practitioners and those with normal colour vision in their ability to outline abnormalities in five of the six photographs that showed fresh blood, in the photograph of a rash and in marking the position of bacilli in the photograph of a stained slide. Medical practitioners with CCVD are handicapped in their evaluation of the presence and extent of coloured clinical signs. Medical schools should ensure that students with CCVD are aware of their deficiency and know its severity, so they can take special care in clinical practice.

Demographic and clinical characteristics of a paediatric low vision population in a low vision clinic in China.

PubMed

Gao, Guohong; Yu, Manrong; Dai, Jinhui; Xue, Feng; Wang, Xiaoying; Zou, Leilei; Chen, Minjie; Ma, Fei

2016-05-01

The aim was to describe the characteristics of the paediatric population attending the low vision clinic of the Eye and ENT Hospital, located in Shanghai, China. The clinical records of all the children attending the low vision clinic of Eye and ENT Hospital affiliated to Fudan University between January 1, 2009 and May 31, 2014 were retrospectively reviewed. The main data analysed were age, gender, education, visual demand, diagnosis, visual acuity and prescription of low vision aids. Of the 162 patients, 104 (64.20 per cent) were male. The age range of the study population was three to 20 years, with a mean of 10.73 ± 5.08 years. There were 43.21 per cent with moderate visual impairment, 26.54 per cent had severe visual impairment and 19.75 per cent were blind. The leading causes of visual impairment were congenital cataract (21.61 per cent), optic atrophy (14.20 per cent), macular dystrophy (11.73 per cent), nystagmus (9.88 per cent) and congenital glaucoma (9.26 per cent). The most frequently prescribed low vision devices for distant and near vision were binocular telescopes (23.57 per cent) and stand magnifiers (22.93 per cent), respectively. Young age (up to six years, 37.93 per cent), high cost (24.14 per cent), cosmetic reasons (17.24 per cent) and inconvenience (13.79 per cent) were the main reasons that children or parents refused to accept useful low vision aids. Congenital and hereditary diseases constituted the major causes of low vision in the study population. Strategies that make good-quality rehabilitation services available, affordable and accessible, especially in developing countries, will have the greatest impact on visual impairment. In China, both urban and rural, the coverage of low vision services should be strengthened. © 2016 The Authors. Clinical and Experimental Optometry © 2016 Optometry Australia.

Your Child's Vision

MedlinePlus

... 3½, kids should have eye health screenings and visual acuity tests (tests that measure sharpness of vision) ... eye rubbing extreme light sensitivity poor focusing poor visual tracking (following an object) abnormal alignment or movement ...

Human factors involved in perception and action in a natural stereoscopic world: an up-to-date review with guidelines for stereoscopic displays and stereoscopic virtual reality (VR)

NASA Astrophysics Data System (ADS)

Perez-Bayas, Luis

2001-06-01

In stereoscopic perception of a three-dimensional world, binocular disparity might be thought of as the most important cue to 3D depth perception. Nevertheless, in reality there are many other factors involved before the 'final' conscious and subconscious stereoscopic perception, such as luminance, contrast, orientation, color, motion, and figure-ground extraction (pop-out phenomenon). In addition, more complex perceptual factors exist, such as attention and its duration (an equivalent of 'brain zooming') in relation to physiological central vision, In opposition to attention to peripheral vision and the brain 'top-down' information in relation to psychological factors like memory of previous experiences and present emotions. The brain's internal mapping of a pure perceptual world might be different from the internal mapping of a visual-motor space, which represents an 'action-directed perceptual world.' In addition, psychological factors (emotions and fine adjustments) are much more involved in a stereoscopic world than in a flat 2D-world, as well as in a world using peripheral vision (like VR, using a curved perspective representation, and displays, as natural vision does) as opposed to presenting only central vision (bi-macular stereoscopic vision) as in the majority of typical stereoscopic displays. Here is presented the most recent and precise information available about the psycho-neuro- physiological factors involved in the perception of stereoscopic three-dimensional world, with an attempt to give practical, functional, and pertinent guidelines for building more 'natural' stereoscopic displays.

Does functional vision behave differently in low-vision patients with diabetic retinopathy?--A case-matched study.

PubMed

Ahmadian, Lohrasb; Massof, Robert

2008-09-01

A retrospective case-matched study designed to compare patients with diabetic retinopathy (DR) and other ocular diseases, managed in a low-vision clinic, in four different types of functional vision. Reading, mobility, visual motor, and visual information processing were measured in the patients (n = 114) and compared with those in patients with other ocular diseases (n = 114) matched in sex, visual acuity (VA), general health status, and age, using the Activity Inventory as a Rasch-scaled measurement tool. Binocular distance visual acuity was categorized as normal (20/12.5-20/25), near normal (20/32-20/63), moderate (20/80-20/160), severe (20/200-20/400), profound (20/500-20/1000), and total blindness (20/1250 to no light perception). Both Wilcoxon matched pairs signed rank test and the sign test of matched pairs were used to compare estimated functional vision measures between DR cases and controls. Cases ranged in age from 19 to 90 years (mean age, 67.5), and 59% were women. The mean visual acuity (logMar scale) was 0.7. Based on the Wilcoxon signed rank test analyses and after adjusting the probability for multiple comparisons, there was no statistically significant difference (P > 0.05) between patients with DR and control subjects in any of four functional visions. Furthermore, diabetic retinopathy patients did not differ (P > 0.05) from their matched counterparts in goal-level vision-related functional ability and total visual ability. Visual impairment in patients with DR appears to be a generic and non-disease-specific outcome that can be explained mainly by the end impact of the disease in the patients' daily lives and not by the unique disease process that results in the visual impairment.

Binocular depth processing in the ventral visual pathway

PubMed Central

Vogels, Rufin

2016-01-01

One of the most powerful forms of depth perception capitalizes on the small relative displacements, or binocular disparities, in the images projected onto each eye. The brain employs these disparities to facilitate various computations, including sensori-motor transformations (reaching, grasping), scene segmentation and object recognition. In accordance with these different functions, disparity activates a large number of regions in the brain of both humans and monkeys. Here, we review how disparity processing evolves along different regions of the ventral visual pathway of macaques, emphasizing research based on both correlational and causal techniques. We will discuss the progression in the ventral pathway from a basic absolute disparity representation to a more complex three-dimensional shape code. We will show that, in the course of this evolution, the underlying neuronal activity becomes progressively more bound to the global perceptual experience. We argue that these observations most probably extend beyond disparity processing per se, and pertain to object processing in the ventral pathway in general. We conclude by posing some important unresolved questions whose answers may significantly advance the field, and broaden its scope. This article is part of the themed issue ‘Vision in our three-dimensional world’. PMID:27269602

Eye structure and amphibious foraging in albatrosses

PubMed Central

Martin, G. R.

1998-01-01

Anterior eye structure and retinal visual fields were determined in grey-headed and black-browed albatrosses, Diomedea melanophris and D. chrysostoma (Procellariiformes, Diomedeidae), using keratometry and an ophthalmoscopic reflex technique. Results for the two species were very similar and indicate that the eyes are of an amphibious optical design suggesting that albatross vision is well suited to the visual pursuit of active prey both on and below the ocean surface. The corneas are relatively flat (radius ca. 14.5 mm) and hence of low absolute refractive power (ca. 23 dioptres). In air the binocular fields are relatively long (vertical extent ca. 70 degrees) and narrow (maximum width in the plane of the optic axes 26–32 degrees), a topography found in a range of bird species that employ visual guidance of bill position when foraging. The cyclopean fields measure approximately 270 degrees in the horizontal plane, but there is a 60 degrees blind sector above the head owing to the positioning of the eyes below the protruding supraorbital ridges. Upon immersion the monocular fields decrease in width such that the binocular fields are abolished. Anterior eye structure, and visual field topography in both air and water, show marked similarity with those of the Humboldt penguin.

Neuronal responses in visual area V2 (V2) of macaque monkeys with strabismic amblyopia.

PubMed

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

2011-09-01

Amblyopia, a developmental disorder of spatial vision, is thought to result from a cascade of cortical deficits over several processing stages beginning at the primary visual cortex (V1). However, beyond V1, little is known about how cortical development limits the visual performance of amblyopic primates. We quantitatively analyzed the monocular and binocular responses of V1 and V2 neurons in a group of strabismic monkeys exhibiting varying depths of amblyopia. Unlike in V1, the relative effectiveness of the affected eye to drive V2 neurons was drastically reduced in the amblyopic monkeys. The spatial resolution and the orientation bias of V2, but not V1, neurons were subnormal for the affected eyes. Binocular suppression was robust in both cortical areas, and the magnitude of suppression in individual monkeys was correlated with the depth of their amblyopia. These results suggest that the reduced functional connections beyond V1 and the subnormal spatial filter properties of V2 neurons might have substantially limited the sensitivity of the amblyopic eyes and that interocular suppression was likely to have played a key role in the observed alterations of V2 responses and the emergence of amblyopia.

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

PubMed Central

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

2011-01-01

Amblyopia, a developmental disorder of spatial vision, is thought to result from a cascade of cortical deficits over several processing stages beginning at the primary visual cortex (V1). However, beyond V1, little is known about how cortical development limits the visual performance of amblyopic primates. We quantitatively analyzed the monocular and binocular responses of V1 and V2 neurons in a group of strabismic monkeys exhibiting varying depths of amblyopia. Unlike in V1, the relative effectiveness of the affected eye to drive V2 neurons was drastically reduced in the amblyopic monkeys. The spatial resolution and the orientation bias of V2, but not V1, neurons were subnormal for the affected eyes. Binocular suppression was robust in both cortical areas, and the magnitude of suppression in individual monkeys was correlated with the depth of their amblyopia. These results suggest that the reduced functional connections beyond V1 and the subnormal spatial filter properties of V2 neurons might have substantially limited the sensitivity of the amblyopic eyes and that interocular suppression was likely to have played a key role in the observed alterations of V2 responses and the emergence of amblyopia. PMID:21263036

Binocular depth processing in the ventral visual pathway.

PubMed

Verhoef, Bram-Ernst; Vogels, Rufin; Janssen, Peter

2016-06-19

One of the most powerful forms of depth perception capitalizes on the small relative displacements, or binocular disparities, in the images projected onto each eye. The brain employs these disparities to facilitate various computations, including sensori-motor transformations (reaching, grasping), scene segmentation and object recognition. In accordance with these different functions, disparity activates a large number of regions in the brain of both humans and monkeys. Here, we review how disparity processing evolves along different regions of the ventral visual pathway of macaques, emphasizing research based on both correlational and causal techniques. We will discuss the progression in the ventral pathway from a basic absolute disparity representation to a more complex three-dimensional shape code. We will show that, in the course of this evolution, the underlying neuronal activity becomes progressively more bound to the global perceptual experience. We argue that these observations most probably extend beyond disparity processing per se, and pertain to object processing in the ventral pathway in general. We conclude by posing some important unresolved questions whose answers may significantly advance the field, and broaden its scope.This article is part of the themed issue 'Vision in our three-dimensional world'. © 2016 The Author(s).

Patient-reported outcomes 5 years after laser in situ keratomileusis.

PubMed

Schallhorn, Steven C; Venter, Jan A; Teenan, David; Hannan, Stephen J; Hettinger, Keith A; Pelouskova, Martina; Schallhorn, Julie M

2016-06-01

To assess vision-related, quality-of-life outcomes 5 years after laser in situ keratomileusis (LASIK) and determine factors predictive of patient satisfaction. Optical Express, Glasgow, Scotland. Retrospective case series. Data from patients who had attended a clinical examination 5 years after LASIK were analyzed. All treatments were performed using the Visx Star S4 IR excimer laser. Patient-reported satisfaction, the effect of eyesight on various activities, visual phenomena, and ocular discomfort were evaluated 5 years postoperatively. Multivariate regression analysis was performed to determine factors affecting patient satisfaction. The study comprised 2530 patients (4937 eyes) who had LASIK. The mean age at the time of surgery was 42.4 years ± 12.5 (SD), and the preoperative manifest spherical equivalent ranged from -11.0 diopters (D) to +4.88 D. Five years postoperatively, 79.3% of eyes were within ±0.50 D of emmetropia and 77.7% of eyes achieved monocular uncorrected distance visual acuity (UDVA) and 90.6% of eyes achieved binocular UDVA of 20/20 or better. Of the patients, 91.0% said they were satisfied with their vision and 94.9% did not wear distance correction. Less than 2.0% of patients noticed visual phenomena, even with spectacle correction. Major predictors of patient satisfaction 5 years postoperatively were postoperative binocular UDVA (37.6% variance explained by regression model), visual phenomena (relative contribution of 15.0%), preoperative and postoperative sphere and their interactions (11.6%), and eyesight-related difficulties with various activities such as night driving, outdoor activities, and reading (10.2%). Patient-reported quality-of-life and satisfaction rates remained high 5 years after LASIK. Uncorrected vision was the strongest predictor of satisfaction. Dr. S.C. Schallhorn is a consultant to Abbott Medical Optics, Inc., Zeiss Meditec AG, and Autofocus Inc. and a global medical director for Optical Express. No other author has a financial or proprietary interest in any material or method mentioned. Copyright © 2016 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Texton Theory Of Two-Dimensional And Three-Dimensional Vision

NASA Astrophysics Data System (ADS)

Julesz, Bela

1983-04-01

Recently, after two decades of research in visual texture discrimination and in the discrimination of briefly presented patterns, a new structure of human vision has emerged. Accordingly, human vision is mediated by two separate visual systems: a preattentive and an attentive one. The parallel preattentive visual system cannot process complex forms, yet can, almost instantaneously, without effort or scrutiny, detect differences in a few local conspicuous features, regardless of the number of elements or where they occur. These "textons" (Julesz, 1981) are elongated blobs (e.g. rectangles, ellipses, or line segments) of specific color, angular orientation, width, length, binocular and movement disparity, and flicker rate. For line segments, their terminators (ends-of-lines) and crossings often behave as textons. The preattentive system can count only the number of textons and detect their locale, but cannot perceive the positional relations between them (Julesz, 1981, 1981a). However, the preattentive system can direct focal attention to the areas where differences in texton density occur in about 50 msec steps (four times faster than eye-movements). Only in this narrow aperture of focal attention (which can be as small as a few minutes of arc) can positional differences be perceived, permitting the prodigious feats of form recognition (Bergen and Julesz, 1981). Since disparity differences in random-dot stereograms can be perceived in a 50 msec presentation (followed by masking) provided the binocular disparity is beyond a critical limit, disparity is also a texton. It can be shown (for review, see Julesz and Schumer, 1981) that the largest disparity that can yield stereopsis in random-dot stereograms is a monotonic function of the cyclopean target area. Furthermore, the cyclopean modulation function (for corrugated sinusoidal depth gratings) is very "myopic" with a cit-off around 3 c/deg. Since stereopsis is important in quality inspection, an objective determination of stereoscopic abilities using evoked potential techniques to dynamic random-dot correlograms and stereograms is also discussed (Julesz, Kropfl and Petrig, 1980; Julesz and Kropfl, 1982). These techniques also permit the early diagnosis of stereo-blindness that afflicts 2% of the human population and might lead to its prevention.

Strabismus surgery before versus after completion of amblyopia therapy in children

PubMed Central

Korah, Sanita; Philip, Swetha; Jasper, Smitha; Antonio-Santos, Aileen; Braganza, Andrew

2015-01-01

Background Normal visual development occurs when the brain is able to integrate the visual input from each of the two eyes to form a single three-dimensional image. The process of development of complete three-dimensional vision begins at birth and is almost complete by 24 months of age. The development of this binocular vision is hindered by any abnormality that prevents the brain from receiving a clear, similar image from each eye, due to decreased vision (e.g. amblyopia), or due to misalignment of the two eyes (strabismus or squint) in infancy and early childhood. Currently, practice patterns for management of a child with both strabismus and amblyopia are not standardized. Objectives To study the functional and anatomic (ocular alignment) outcomes of strabismus surgery before completion of amblyopia therapy as compared with surgery after completion of amblyopia therapy in children under seven years of age. Search methods We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2014, Issue 6), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to July 2014), EMBASE (January 1980 to July 2014), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to July 2014), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 24 July 2014. A manual search for articles from a review of the references of the selected publications and conference abstracts was completed to identify any additional relevant studies. Selection criteria We searched for randomized controlled trials (RCTs) that provided data on strabismus surgery in children less than seven years of age, performed after initiation of, but before completion of amblyopia therapy, as compared with strabismus surgery after completion of amblyopia therapy. Data collection and analysis Two authors independently assessed studies identified from the electronic and manual searches. Main results There were no RCTs that fit our inclusion criteria and so no analysis was possible. Authors’ conclusions As there are no RCTs currently available and the best existing evidence is only from non-randomized studies, there is a need for prospective RCTs to investigate strabismus surgery in the presence of strabismic amblyopia. The optimal timing of when to perform strabismus surgery in children with amblyopia is unknown. PMID:25315969

Color blindness among multiple sclerosis patients in Isfahan.

PubMed

Shaygannejad, Vahid; Golabchi, Khodayar; Dehghani, Alireza; Ashtari, Fereshteh; Haghighi, Sepehr; Mirzendehdel, Mahsa; Ghasemi, Majid

2012-03-01

Multiple sclerosis (MS) is a disease of young and middle aged individuals with a demyelinative axonal damage nature in central nervous system that causes various signs and symptoms. As color vision needs normal function of optic nerve and macula, it is proposed that MS can alter it via influencing optic nerve. In this survey, we evaluated color vision abnormalities and its relationship with history of optic neuritis and abnormal visual evoked potentials (VEPs) among MS patients. The case group was included of clinically definitive MS patients and the same number of normal population was enrolled as the control group. Color vision of all the participants was evaluated by Ishihara test and then visual evoked potential (VEPs) and history of optic neuritis (ON) was assessed among them. Then, frequency of color blindness was compared between the case and the control group. Finally, color blinded patients were compared to those with the history of ON and abnormal VEPs. 63 MS patients and the same number of normal populations were enrolled in this study. 12 patients had color blindness based on the Ishihara test; only 3 of them were among the control group, which showed a significant different between the two groups (P = 0.013). There was a significant relationship between the color blindness and abnormal VEP (R = 0.53, P = 0.023) but not for the color blindness and ON (P = 0.67). This study demonstrates a significant correlation between color blindness and multiple sclerosis including ones with abnormal prolonged VEP latencies. Therefore, in individuals with acquired color vision impairment, an evaluation for potentially serious underlying diseases like MS is essential.

Genetics Home Reference: renal coloboma syndrome

MedlinePlus

... the back of the eye ( the retina ). The vision problems caused by these abnormalities can vary depending ... visual problems, while others may have severely impaired vision. Less common features of renal coloboma syndrome include ...

Vision rehabilitation for visual-vestibular dysfunction: the role of the neuro-optometrist.

PubMed

Cohen, Allen H

2013-01-01

This article discusses, in a clinically relevant format, the importance of including a neuro-optometrist as a member of the management team for patients with balance disorders. To review the importance of vision and visual processing for maintaining a sense of balance and equilibrium and the role of the neuro-optometrist in the overall rehabilitation of patients with balance disorders Dizziness, balance problems and the sensation that the space world is moving (vertigo) are one of the most commonly reported problems in general medical practice. Persons with a central nervous system injury or other idiopathic causes of visual processing problems or who have functional vision problems that are not adequately managed, often experience extreme difficulty with balance and movement, as well as with their perception of space. Consequently, the patient often experiences difficulty functioning in an environment with excessive visual stimulation such as a grocery store or shopping mall. Symptoms of disequilibrium, vestibular and balance problems are commonly a result of VOR disturbance secondary to an inner ear problem and an unstable binocularity. The combination of neuro-optomertic rehabilitative therapy and balance therapy will result in a is an effective treatment for reducing or resolving these symptoms.

The use of contact lens telescopic systems in low vision rehabilitation.

PubMed

Vincent, Stephen J

2017-06-01

Refracting telescopes are afocal compound optical systems consisting of two lenses that produce an apparent magnification of the retinal image. They are routinely used in visual rehabilitation in the form of monocular or binocular hand held low vision aids, and head or spectacle-mounted devices to improve distance visual acuity, and with slight modifications, to enhance acuity for near and intermediate tasks. Since the advent of ground glass haptic lenses in the 1930's, contact lenses have been employed as a useful refracting element of telescopic systems; primarily as a mobile ocular lens (the eyepiece), that moves with the eye. Telescopes which incorporate a contact lens eyepiece significantly improve the weight, comesis, and field of view compared to traditional spectacle-mounted telescopes, in addition to potential related psycho-social benefits. This review summarises the underlying optics and use of contact lenses to provide telescopic magnification from the era of Descartes, to Dallos, and the present day. The limitations and clinical challenges associated with such devices are discussed, along with the potential future use of reflecting telescopes incorporated within scleral lenses and tactile contact lens systems in low vision rehabilitation. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Feedforward control strategies of subjects with transradial amputation in planar reaching.

PubMed

Metzger, Anthony J; Dromerick, Alexander W; Schabowsky, Christopher N; Holley, Rahsaan J; Monroe, Brian; Lum, Peter S

2010-01-01

The rate of upper-limb amputations is increasing, and the rejection rate of prosthetic devices remains high. People with upper-limb amputation do not fully incorporate prosthetic devices into their activities of daily living. By understanding the reaching behaviors of prosthesis users, researchers can alter prosthetic devices and develop training protocols to improve the acceptance of prosthetic limbs. By observing the reaching characteristics of the nondisabled arms of people with amputation, we can begin to understand how the brain alters its motor commands after amputation. We asked subjects to perform rapid reaching movements to two targets with and without visual feedback. Subjects performed the tasks with both their prosthetic and nondisabled arms. We calculated endpoint error, trajectory error, and variability and compared them with those of nondisabled control subjects. We found no significant abnormalities in the prosthetic limb. However, we found an abnormal leftward trajectory error (in right arms) in the nondisabled arm of prosthetic users in the vision condition. In the no-vision condition, the nondisabled arm displayed abnormal leftward endpoint errors and abnormally higher endpoint variability. In the vision condition, peak velocity was lower and movement duration was longer in both arms of subjects with amputation. These abnormalities may reflect the cortical reorganization associated with limb loss.

Stereo imaging with spaceborne radars

NASA Technical Reports Server (NTRS)

Leberl, F.; Kobrick, M.

1983-01-01

Stereo viewing is a valuable tool in photointerpretation and is used for the quantitative reconstruction of the three dimensional shape of a topographical surface. Stereo viewing refers to a visual perception of space by presenting an overlapping image pair to an observer so that a three dimensional model is formed in the brain. Some of the observer's function is performed by machine correlation of the overlapping images - so called automated stereo correlation. The direct perception of space with two eyes is often called natural binocular vision; techniques of generating three dimensional models of the surface from two sets of monocular image measurements is the topic of stereology.

Optimal Audiovisual Integration in the Ventriloquism Effect But Pervasive Deficits in Unisensory Spatial Localization in Amblyopia.

PubMed

Richards, Michael D; Goltz, Herbert C; Wong, Agnes M F

2018-01-01

Classically understood as a deficit in spatial vision, amblyopia is increasingly recognized to also impair audiovisual multisensory processing. Studies to date, however, have not determined whether the audiovisual abnormalities reflect a failure of multisensory integration, or an optimal strategy in the face of unisensory impairment. We use the ventriloquism effect and the maximum-likelihood estimation (MLE) model of optimal integration to investigate integration of audiovisual spatial information in amblyopia. Participants with unilateral amblyopia (n = 14; mean age 28.8 years; 7 anisometropic, 3 strabismic, 4 mixed mechanism) and visually normal controls (n = 16, mean age 29.2 years) localized brief unimodal auditory, unimodal visual, and bimodal (audiovisual) stimuli during binocular viewing using a location discrimination task. A subset of bimodal trials involved the ventriloquism effect, an illusion in which auditory and visual stimuli originating from different locations are perceived as originating from a single location. Localization precision and bias were determined by psychometric curve fitting, and the observed parameters were compared with predictions from the MLE model. Spatial localization precision was significantly reduced in the amblyopia group compared with the control group for unimodal visual, unimodal auditory, and bimodal stimuli. Analyses of localization precision and bias for bimodal stimuli showed no significant deviations from the MLE model in either the amblyopia group or the control group. Despite pervasive deficits in localization precision for visual, auditory, and audiovisual stimuli, audiovisual integration remains intact and optimal in unilateral amblyopia.

Degraded attentional modulation of cortical neural populations in strabismic amblyopia

PubMed Central

Hou, Chuan; Kim, Yee-Joon; Lai, Xin Jie; Verghese, Preeti

2016-01-01

Behavioral studies have reported reduced spatial attention in amblyopia, a developmental disorder of spatial vision. However, the neural populations in the visual cortex linked with these behavioral spatial attention deficits have not been identified. Here, we use functional MRI–informed electroencephalography source imaging to measure the effect of attention on neural population activity in the visual cortex of human adult strabismic amblyopes who were stereoblind. We show that compared with controls, the modulatory effects of selective visual attention on the input from the amblyopic eye are substantially reduced in the primary visual cortex (V1) as well as in extrastriate visual areas hV4 and hMT+. Degraded attentional modulation is also found in the normal-acuity fellow eye in areas hV4 and hMT+ but not in V1. These results provide electrophysiological evidence that abnormal binocular input during a developmental critical period may impact cortical connections between the visual cortex and higher level cortices beyond the known amblyopic losses in V1 and V2, suggesting that a deficit of attentional modulation in the visual cortex is an important component of the functional impairment in amblyopia. Furthermore, we find that degraded attentional modulation in V1 is correlated with the magnitude of interocular suppression and the depth of amblyopia. These results support the view that the visual suppression often seen in strabismic amblyopia might be a form of attentional neglect of the visual input to the amblyopic eye. PMID:26885628

Degraded attentional modulation of cortical neural populations in strabismic amblyopia.

PubMed

Hou, Chuan; Kim, Yee-Joon; Lai, Xin Jie; Verghese, Preeti

2016-01-01

Behavioral studies have reported reduced spatial attention in amblyopia, a developmental disorder of spatial vision. However, the neural populations in the visual cortex linked with these behavioral spatial attention deficits have not been identified. Here, we use functional MRI-informed electroencephalography source imaging to measure the effect of attention on neural population activity in the visual cortex of human adult strabismic amblyopes who were stereoblind. We show that compared with controls, the modulatory effects of selective visual attention on the input from the amblyopic eye are substantially reduced in the primary visual cortex (V1) as well as in extrastriate visual areas hV4 and hMT+. Degraded attentional modulation is also found in the normal-acuity fellow eye in areas hV4 and hMT+ but not in V1. These results provide electrophysiological evidence that abnormal binocular input during a developmental critical period may impact cortical connections between the visual cortex and higher level cortices beyond the known amblyopic losses in V1 and V2, suggesting that a deficit of attentional modulation in the visual cortex is an important component of the functional impairment in amblyopia. Furthermore, we find that degraded attentional modulation in V1 is correlated with the magnitude of interocular suppression and the depth of amblyopia. These results support the view that the visual suppression often seen in strabismic amblyopia might be a form of attentional neglect of the visual input to the amblyopic eye.

[Treatment of amblyopia].

PubMed

von Noorden, G K

1990-01-01

Animal experiments have explored the structural and functional alterations of the afferent visual pathways in amblyopia and have emphasized the extraordinary sensitivity of the immature visual system to abnormal visual stimulation. The practical consequences of these experiments are obvious: early diagnosis of amblyopia and energetic occlusion therapy as early in life as possible. At the same time, measures must be taken to prevent visual deprivation amblyopia in the occluded eye. After successful treatment, alternating penalization with two pairs of spectacles is recommended. Pleoptics involves an enormous commitment in terms of time, personnel and costs. In view of the fact that the superiority of this treatment over occlusion therapy has yet to be proven, the current value of pleoptics appears dubious. Moreover, overtreated patients may end up with intractable diplopia. Diverging opinions exist with regard to the use of penalization as a primary treatment of amblyopia. We employ it only in special cases as an alternative to occlusion therapy. Visual deprivation in infancy caused by opacities of the ocular media, especially when they occur unilaterally, must be eliminated, and deprivation amblyopia must be treated without delay to regain useful vision. Brief periods of bilateral occlusion are recommended to avoid the highly amblyopiogenic imbalance between binocular afferent visual input. Future developments will hopefully include new objective methods to diagnose amblyopia in preverbal children and infants. The application of positron emission tomography is perhaps the first step in the direction of searching for new approaches to this problem.(ABSTRACT TRUNCATED AT 250 WORDS)

Developing a Very Low Vision Orientation and Mobility Test Battery (O&M-VLV).

PubMed

Finger, Robert P; Ayton, Lauren N; Deverell, Lil; O'Hare, Fleur; McSweeney, Shane C; Luu, Chi D; Fenwick, Eva K; Keeffe, Jill E; Guymer, Robyn H; Bentley, Sharon A

2016-09-01

This study aimed to determine the feasibility of an assessment of vision-related orientation and mobility (O&M) tasks in persons with severe vision loss. These tasks may be used for future low vision rehabilitation clinical assessments or as outcome measures in vision restoration trials. Forty legally blind persons (mean visual acuity logMAR 2.3, or hand movements) with advanced retinitis pigmentosa participated in the Orientation & Mobility-Very Low Vision (O&M-VLV) subtests from the Low Vision Assessment of Daily Activities (LoVADA) protocol. Four categories of tasks were evaluated: route travel in three indoor hospital environments, a room orientation task (the "cafe"), a visual exploration task (the "gallery"), and a modified version of the Timed Up and Go (TUG) test, which assesses re-orientation and route travel. Spatial cognition was assessed using the Stuart Tactile Maps test. Visual acuity and visual fields were measured. A generalized linear regression model showed that a number of measures in the O&M-VLV tasks were related to residual visual function. The percentage of preferred walking speed without an aid on three travel routes was associated with visual field (p < 0.01 for all routes) whereas the number of contacts with obstacles during route travel was associated with acuity (p = 0.001). TUG-LV task time was associated with acuity (p = 0.003), as was the cafe time and distance traveled (p = 0.006 and p < 0.001, respectively). The gallery score was the only measure that was significantly associated with both residual acuity and fields (p < 0.001 and p = 0.001, respectively). The O&M-VLV was designed to capture key elements of O&M performance in persons with severe vision loss, which is a population not often studied previously. Performance on these tasks was associated with both binocular visual acuity and visual field. This new protocol includes assessments of orientation, which may be of benefit in vision restoration clinical trials.

Extraocular muscle function testing

MedlinePlus

... may result in double vision or rapid, uncontrolled eye movements . Normal Results Normal movement of the eyes in all directions. What Abnormal Results Mean Eye movement disorders may be due to abnormalities of the ...

Binocular fusion and invariant category learning due to predictive remapping during scanning of a depthful scene with eye movements

PubMed Central

Grossberg, Stephen; Srinivasan, Karthik; Yazdanbakhsh, Arash

2015-01-01

How does the brain maintain stable fusion of 3D scenes when the eyes move? Every eye movement causes each retinal position to process a different set of scenic features, and thus the brain needs to binocularly fuse new combinations of features at each position after an eye movement. Despite these breaks in retinotopic fusion due to each movement, previously fused representations of a scene in depth often appear stable. The 3D ARTSCAN neural model proposes how the brain does this by unifying concepts about how multiple cortical areas in the What and Where cortical streams interact to coordinate processes of 3D boundary and surface perception, spatial attention, invariant object category learning, predictive remapping, eye movement control, and learned coordinate transformations. The model explains data from single neuron and psychophysical studies of covert visual attention shifts prior to eye movements. The model further clarifies how perceptual, attentional, and cognitive interactions among multiple brain regions (LGN, V1, V2, V3A, V4, MT, MST, PPC, LIP, ITp, ITa, SC) may accomplish predictive remapping as part of the process whereby view-invariant object categories are learned. These results build upon earlier neural models of 3D vision and figure-ground separation and the learning of invariant object categories as the eyes freely scan a scene. A key process concerns how an object's surface representation generates a form-fitting distribution of spatial attention, or attentional shroud, in parietal cortex that helps maintain the stability of multiple perceptual and cognitive processes. Predictive eye movement signals maintain the stability of the shroud, as well as of binocularly fused perceptual boundaries and surface representations. PMID:25642198

The application of diffraction grating in the design of virtual reality (VR) system

NASA Astrophysics Data System (ADS)

Chen, Jiekang; Huang, Qitai; Guan, Min

2017-10-01

Virtual Reality (VR) products serve for human eyes ultimately, and the optical properties of VR optical systems must be consistent with the characteristic of human eyes. The monocular coaxial VR optical system is simulated in ZEMAX. A diffraction grating is added to the optical surface next to the eye, and the lights emitted from the diffraction grating are deflected, which can forming an asymmetrical field of view(FOV). Then the lateral chromatic aberration caused by the diffraction grating was corrected by the chromatic dispersion of the prism. Finally, the aspheric surface was added to further optimum design. During the optical design of the system, how to balance the dispersion of the diffraction grating and the prism is the main problem. The balance was achieved by adjusting the parameters of the grating and the prism constantly, and then using aspheric surfaces finally. In order to make the asymmetric FOV of the system consistent with the angle of the visual axis, and to ensure the stereo vision area clear, the smaller half FOV of monocular system is required to reach 30°. Eventually, a system with asymmetrical FOV of 30°+40° was designed. In addition, the aberration curve of the system was analyzed by ZEMAX, and the binocular FOV was calculated according to the principle of binocular overlap. The results show that the asymmetry of FOV of VR monocular optical system can fit to human eyes and the imaging quality match for the human visual characteristics. At the same time, the diffraction grating increases binocular FOV, which decreases the requirement for the design FOV of monocular system.

Comparing the fixational and functional preferred retinal location in a pointing task

PubMed Central

Sullivan, Brian; Walker, Laura

2016-01-01

Patients with central vision loss (CVL) typically adopt eccentric viewing strategies using a preferred retinal locus (PRL) in peripheral retina. Clinically, the PRL is defined monocularly as the area of peripheral retina used to fixate small stimuli. It is not clear if this fixational PRL describes the same portion of peripheral retina used during dynamic binocular eye-hand coordination tasks. We studied this question with four participants each with a unique CVL history. Using a scanning laser ophthalmoscope, we measured participants’ monocular visual fields and the location and stability of their fixational PRLs. Participants’ monocular and binocular visual fields were also evaluated using a computer monitor and eye tracker. Lastly, eye-hand coordination was tested over several trials where participants pointed to and touched a small target on a touchscreen monitor. Trials were blocked and carried out monocularly and binocularly, with a target appearing at 5° or 15° from screen center, in one of 8 locations. During pointing, our participants often exhibited long movement durations, an increased number of eye movements and impaired accuracy, especially in monocular conditions. However, these compensatory changes in behavior did not consistently worsen when loci beyond the fixational PRL were used. While fixational PRL size, location and fixation stability provide a necessary description of behavior, they are not sufficient to capture the pointing PRL used in this task. Generally, patients use a larger portion of peripheral retina than one might expect from measures of the fixational PRL alone, when pointing to a salient target without time constraints. While the fixational and pointing PRLs often overlap, the fixational PRL does not predict the large area of peripheral retina that can be used. PMID:26440864

[Binocular status of dyslexics--are there differences to a healthy comparison group?].

PubMed

Riebeling, P; Brunner, E; Grossjohann, R; Clemens, S

2009-10-01

Despite numerous studies dealing with the question of a possible relation of visual problems and dyslexia, which is negated by most ophthalmologists, some opticians still favour the treatment of dyslexia by correction of the "Winkelfehlsichtigkeit" following MCH. Our aim was by also including the Pola test to check the usefulness of this treatment. In a 2-year prospective study we examined the 4th grade elementary school students in our city who had dyslexia as an assured diagnosis (n = 21). The results were compared to those of an age-matched group without pathological findings regarding their reading and spelling ability (n = 21). Examinations included visual acuity, eye position by cover test, Maddox cylinder and Pola test for near distance, binocular vision (Bagolini and Worth test, Lang test I and II, Titmus test, amplitude of fusion), amplitude of accommodation, refraction in cycloplegia and organic status. A significant difference was found between the two groups regarding the amplitude of divergence in near (p = 0.009) and far distance (p = 0.019) which were both smaller for the dyslexia group, as well as the binocular near visual acuity (p = 0.04). Using the SAS procedure STEPDISC we discriminated the normal and dyslexia group by amplitude of divergence, near visual acuity and alternating near prism cover test with a sensitivity of 81 % and a specifity of 75 %. The results of the Pola test did not show any significant difference between the groups. No differences were found between the groups regarding the eye position. Therefore a treatment of dyslexia using prisms does not appear reasonable. However because of the group sizes the significance of the results is limited. Georg Thieme Verlag KG Stuttgart.New York.

Binocular fusion and invariant category learning due to predictive remapping during scanning of a depthful scene with eye movements.

PubMed

Grossberg, Stephen; Srinivasan, Karthik; Yazdanbakhsh, Arash

2014-01-01

How does the brain maintain stable fusion of 3D scenes when the eyes move? Every eye movement causes each retinal position to process a different set of scenic features, and thus the brain needs to binocularly fuse new combinations of features at each position after an eye movement. Despite these breaks in retinotopic fusion due to each movement, previously fused representations of a scene in depth often appear stable. The 3D ARTSCAN neural model proposes how the brain does this by unifying concepts about how multiple cortical areas in the What and Where cortical streams interact to coordinate processes of 3D boundary and surface perception, spatial attention, invariant object category learning, predictive remapping, eye movement control, and learned coordinate transformations. The model explains data from single neuron and psychophysical studies of covert visual attention shifts prior to eye movements. The model further clarifies how perceptual, attentional, and cognitive interactions among multiple brain regions (LGN, V1, V2, V3A, V4, MT, MST, PPC, LIP, ITp, ITa, SC) may accomplish predictive remapping as part of the process whereby view-invariant object categories are learned. These results build upon earlier neural models of 3D vision and figure-ground separation and the learning of invariant object categories as the eyes freely scan a scene. A key process concerns how an object's surface representation generates a form-fitting distribution of spatial attention, or attentional shroud, in parietal cortex that helps maintain the stability of multiple perceptual and cognitive processes. Predictive eye movement signals maintain the stability of the shroud, as well as of binocularly fused perceptual boundaries and surface representations.

Binocular Neurons in Parastriate Cortex: Interocular ‘Matching’ of Receptive Field Properties, Eye Dominance and Strength of Silent Suppression

PubMed Central

Wang, Chun; Dreher, Bogdan

2014-01-01

Spike-responses of single binocular neurons were recorded from a distinct part of primary visual cortex, the parastriate cortex (cytoarchitectonic area 18) of anaesthetized and immobilized domestic cats. Functional identification of neurons was based on the ratios of phase-variant (F1) component to the mean firing rate (F0) of their spike-responses to optimized (orientation, direction, spatial and temporal frequencies and size) sine-wave-luminance-modulated drifting grating patches presented separately via each eye. In over 95% of neurons, the interocular differences in the phase-sensitivities (differences in F1/F0 spike-response ratios) were small (≤0.3) and in over 80% of neurons, the interocular differences in preferred orientations were ≤10°. The interocular correlations of the direction selectivity indices and optimal spatial frequencies, like those of the phase sensitivies and optimal orientations, were also strong (coefficients of correlation r ≥0.7005). By contrast, the interocular correlations of the optimal temporal frequencies, the diameters of summation areas of the excitatory responses and suppression indices were weak (coefficients of correlation r ≤0.4585). In cells with high eye dominance indices (HEDI cells), the mean magnitudes of suppressions evoked by stimulation of silent, extra-classical receptive fields via the non-dominant eyes, were significantly greater than those when the stimuli were presented via the dominant eyes. We argue that the well documented ‘eye-origin specific’ segregation of the lateral geniculate inputs underpinning distinct eye dominance columns in primary visual cortices of mammals with frontally positioned eyes (distinct eye dominance columns), combined with significant interocular differences in the strength of silent suppressive fields, putatively contribute to binocular stereoscopic vision. PMID:24927276

Vision Function in HIV-infected Individuals without Retinitis; Report of the Studies of Ocular Complications of AIDS Research Group

PubMed Central

Freeman, William R.; Van Natta, Mark L.; Jabs, Douglas; Sample, Pamela A.; Sadun, Alfredo A.; Thorne, Jennifer; Shah, Kayur H.; Holland, Gary N.

2008-01-01

Purpose To evaluate the prevalence and risk factors for vision loss in patients with clinical or immunologic AIDS without infectious retinitis. Design A prospective multicentered cohort study of patients with AIDS. Methods 1,351 patients (2,671 eyes) at 19 clinical trials centers diagnosed with AIDS but without major ocular complications of HIV. Standardized measurements of visual acuity, automated perimetry, and contrast sensitivity were analyzed and correlated with measurements of patients’ health and medical data relating to HIV infection. We evaluated correlations between vision function testing and HIV-related risk factors and medical testing. Results There were significant (p<0.05) associations between measures of decreasing vision function and indices of increasing disease severity including Karnofsky score and hemoglobin. A significant relationship was seen between low contrast sensitivity and decreasing levels of CD4+ T-cell count. Three percent of eyes had a visual acuity worse than 20/40 Snellen equivalents, which was significantly associated with a history of opportunistic infections and low Karnofsky score. When compared to external groups with normal vision, 39% of eyes had abnormal mean deviation on automated perimetry, 33% had abnormal pattern standard deviation, and 12% of eyes had low contrast sensitivity. Conclusions This study confirms that visual dysfunction is common in patients with AIDS but without retinitis. The most prevalent visual dysfunction is loss of visual field; nearly 40% of patients have some abnormal visual field. There is an association between general disease severity and less access to care and vision loss. The pathophysiology of this vision loss is unknown but is consistent with retinovascular disease or optic nerve disease. PMID:18191094

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

PubMed

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

2016-02-01

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

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

PubMed Central

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

2016-01-01

Perceptual learning in contrast detection improves monocular visual function in adults with anisometropic amblyopia; however, its effect on binocular combination remains unknown. Given that the amblyopic visual system suffers from pronounced binocular functional loss, it is important to address how the amblyopic visual system responds to such training strategies under binocular viewing conditions. Anisometropic amblyopes (n = 13) were asked to complete two psychophysical supra-threshold binocular summation tasks: (1) binocular phase combination and (2) dichoptic global motion coherence before and after monocular training to investigate this question. We showed that these participants benefited from monocular training in terms of binocular combination. More importantly, the improvements observed with the area under log CSF (AULCSF) were found to be correlated with the improvements in binocular phase combination. PMID:26829898

Factors influencing hand/eye synchronicity in the computer age.

PubMed

Grant, A H

1992-09-01

In using a computer, the relation of vision to hand/finger actuated keyboard usage in performing fine motor-coordinated functions is influenced by the physical location, size, and collective placement of the keys. Traditional nonprehensile flat/rectangular keyboard applications usually require a high and nearly constant level of visual attention. Biometrically shaped keyboards would allow for prehensile hand-posturing, thus affording better tactile familiarity with the keys, requiring less intense and less constant level of visual attention to the task, and providing a greater measure of freedom from having to visualize the key(s). Workpace and related physiological changes, aging, onset of monocularization (intermittent lapsing of binocularity for near vision) that accompanies presbyopia, tool colors, and background contrast are factors affecting constancy of visual attention to task performance. Capitas extension, excessive excyclotorsion, and repetitive strain injuries (such as carpal tunnel syndrome) are common and debilitating concomitants to computer usage. These problems can be remedied by improved keyboard design. The salutary role of mnemonics in minimizing visual dependency is discussed.

Combination of blood oxygen level–dependent functional magnetic resonance imaging and visual evoked potential recordings for abnormal visual cortex in two types of amblyopia

PubMed Central

Wang, Xinmei; Cui, Dongmei; Zheng, Ling; Yang, Xiao; Yang, Hui

2012-01-01

Purpose To elucidate the different neuromechanisms of subjects with strabismic and anisometropic amblyopia compared with normal vision subjects using blood oxygen level–dependent functional magnetic resonance imaging (BOLD-fMRI) and pattern-reversal visual evoked potential (PR-VEP). Methods Fifty-three subjects, age range seven to 12 years, diagnosed with strabismic amblyopia (17 cases), anisometropic amblyopia (20 cases), and normal vision (16 cases), were examined using the BOLD-fMRI and PR-VEP of UTAS-E3000 techniques. Cortical activation by binocular viewing of reversal checkerboard patterns was examined in terms of the calcarine region of interest (ROI)-based and spatial frequency–dependent analysis. The correlation of cortical activation in fMRI and the P100 amplitude in VEP were analyzed using the SPSS 12.0 software package. Results In the BOLD-fMRI procedure, reduced areas and decreased activation levels were found in Brodmann area (BA) 17 and other extrastriate areas in subjects with amblyopia compared with the normal vision group. In general, the reduced areas mainly resided in the striate visual cortex in subjects with anisometropic amblyopia. In subjects with strabismic amblyopia, a more significant cortical impairment was found in bilateral BA 18 and BA 19 than that in subjects with anisometropic amblyopia. The activation by high-spatial-frequency stimuli was reduced in bilateral BA 18 and 19 as well as BA 17 in subjects with anisometropic amblyopia, whereas the activation was mainly reduced in BA 18 and BA 19 in subjects with strabismic amblyopia. These findings were further confirmed by the ROI-based analysis of BA 17. During spatial frequency–dependent VEP detection, subjects with anisometropic amblyopia had reduced sensitivity for high spatial frequency compared to subjects with strabismic amblyopia. The cortical activation in fMRI with the calcarine ROI-based analysis of BA 17 was significantly correlated with the P100 amplitude in VEP recording. Conclusions This study suggested that different types of amblyopia had different cortical responses and combinations of spatial frequency–dependent BOLD-fMRI with PR-VEP could differentiate among various kinds of amblyopia according to the different cortical responses. This study can supply new methods for amblyopia neurology study. PMID:22539870

Color blindness among multiple sclerosis patients in Isfahan

PubMed Central

Shaygannejad, Vahid; Golabchi, Khodayar; Dehghani, Alireza; Ashtari, Fereshteh; Haghighi, Sepehr; Mirzendehdel, Mahsa; Ghasemi, Majid

2012-01-01

Background: Multiple sclerosis (MS) is a disease of young and middle aged individuals with a demyelinative axonal damage nature in central nervous system that causes various signs and symptoms. As color vision needs normal function of optic nerve and macula, it is proposed that MS can alter it via influencing optic nerve. In this survey, we evaluated color vision abnormalities and its relationship with history of optic neuritis and abnormal visual evoked potentials (VEPs) among MS patients. Materials and Methods: The case group was included of clinically definitive MS patients and the same number of normal population was enrolled as the control group. Color vision of all the participants was evaluated by Ishihara test and then visual evoked potential (VEPs) and history of optic neuritis (ON) was assessed among them. Then, frequency of color blindness was compared between the case and the control group. Finally, color blinded patients were compared to those with the history of ON and abnormal VEPs. Results: 63 MS patients and the same number of normal populations were enrolled in this study. 12 patients had color blindness based on the Ishihara test; only 3 of them were among the control group, which showed a significant different between the two groups (P = 0.013). There was a significant relationship between the color blindness and abnormal VEP (R = 0.53, P = 0.023) but not for the color blindness and ON (P = 0.67). Conclusions: This study demonstrates a significant correlation between color blindness and multiple sclerosis including ones with abnormal prolonged VEP latencies. Therefore, in individuals with acquired color vision impairment, an evaluation for potentially serious underlying diseases like MS is essential. PMID:23267377

SOURCES OF BINOCULAR SUPRATHRESHOLD VISUAL FIELD LOSS IN A COHORT OF OLDER WOMEN BEING FOLLOWED FOR RISK OF FALLS (AN AMERICAN OPHTHALMOLOGICAL SOCIETY THESIS)

PubMed Central

Coleman, Anne Louise

2007-01-01

Purpose To determine the sources of binocular visual field loss most strongly associated with falls in a cohort of older women. Methods In the Study of Osteoporotic Fractures, women with severe binocular visual field loss had an increased risk of two or more falls during the 12 months following the eye examination. The lens and fundus photographs of the 422 women with severe binocular visual field loss, plus a random sample of 141 white women with no, mild, or moderate binocular visual field loss—47 white women with no binocular visual field loss, 46 white women with mild binocular visual field loss, and 48 white women with moderate binocular visual field loss —were evaluated for lens opacities, glaucomatous optic nerve damage, age-related macular degeneration, and diabetic retinopathy. Results Eighty-four percent of the women with severe binocular visual field loss had ocular disease in one or both eyes. Bilateral cataracts and glaucomatous optic nerve damage were the most common sources of this severe binocular visual field loss. Approximately 15.2% of women had no evidence of lens opacities, glaucomatous optic nerve damage, age-related macular degeneration, or diabetic retinopathy. Conclusion Severe binocular visual field loss due primarily to cataracts, glaucoma, and age-related macular degeneration explains 33.3% of the falls among women who fell frequently. Because binocular visual field loss may be treatable and/or preventable, screening programs for binocular visual field loss and subsequent referral for intervention and treatment are recommended as a strategy for preventing falls among the elderly. PMID:18427619

The perception of depth from binocular disparity.

DOT National Transportation Integrated Search

1963-05-01

This study was concerned with the factors involved in the perception of depth from a binocular disparity. A binocularly observed configuration of constant convergences, constant visual size, and having constant binocular disparities was made to appea...

[Strabismus surgery in Grave's disease--dose-effect relationships and functional results].

PubMed

Schittkowski, M; Fichter, N; Guthoff, R

2004-11-01

Strabismus in thyroid ophthalmopathy is based on a loss of the contractility and distensibility of the external ocular muscles. Different therapeutic approaches are available, such as recession after pre-. or intraoperative measurement, adjustable sutures, antagonist resection, or contralateral synergist faden-operation. 26 patients with strabismus in thyroid ophthalmopathy were operated between 2000 and 2003. All patients were examined preoperatively, then 1 day and 3 - 6 months (maximum 36 months) postoperatively. Before proceeding with surgery, we waited at least 6 months after stabilization of ocular alignment and normalization of thyroid chemistry. Preoperative vertical deviation was 10-44 PD (mean 22), 3 months postoperatively it was 2-10 PD (mean 1.5). Recession of the fibrotic muscle leads to reproducible results: 3.98 +/- 0.52 PD vertical deviation/mm for the inferior rectus. In the case of a large preoperative deviation a correction should be expected, which might not be sufficient in the first few days or weeks; a second operation should not be carried out before 3 months. 7 patients were operated twice, 1 patient need three operations. 4 patients (preop. 0) achieved no double vision at all; 15 patients (preop. 1) had no double vision in the primary and reading positions; 3 patients (preop. 0) had no double vision with a maximum of 5 PD; 1 patient (preop. 7) had double vision in the primary or reading position even with prisms; and 2 patients (preop. 17) had double vision in every position. We advocate that recession of the restricted inferior or internal rectus muscle is precise, safe and effective in patients with thyroid ophthalmopathy. The recessed muscle should be fixed directly at the sclera to avoid late over-correction through a slipped muscle. The success rate in terms of binocular single vision was 76 % and 88 % with prisms added.

Eyesight quality and Computer Vision Syndrome.

PubMed

Bogdănici, Camelia Margareta; Săndulache, Diana Elena; Nechita, Corina Andreea

2017-01-01

The aim of the study was to analyze the effects that gadgets have on eyesight quality. A prospective observational study was conducted from January to July 2016, on 60 people who were divided into two groups: Group 1 - 30 middle school pupils with a mean age of 11.9 ± 1.86 and Group 2 - 30 patients evaluated in the Ophthalmology Clinic, "Sf. Spiridon" Hospital, Iași, with a mean age of 21.36 ± 7.16 years. The clinical parameters observed were the following: visual acuity (VA), objective refraction, binocular vision (BV), fusional amplitude (FA), Schirmer's test. A questionnaire was also distributed, which contained 8 questions that highlighted the gadget's impact on the eyesight. The use of different gadgets, such as computer, laptops, mobile phones or other displays become part of our everyday life and people experience a variety of ocular symptoms or vision problems related to these. Computer Vision Syndrome (CVS) represents a group of visual and extraocular symptoms associated with sustained use of visual display terminals. Headache, blurred vision, and ocular congestion are the most frequent manifestations determined by the long time use of gadgets. Mobile phones and laptops are the most frequently used gadgets. People who use gadgets for a long time have a sustained effort for accommodation. A small amount of refractive errors (especially myopic shift) was objectively recorded by various studies on near work. Dry eye syndrome could also be identified, and an improvement of visual comfort could be observed after the instillation of artificial tears drops. Computer Vision Syndrome is still under-diagnosed, and people should be made aware of the bad effects the prolonged use of gadgets has on eyesight.

Eyesight quality and Computer Vision Syndrome

PubMed Central

Bogdănici, Camelia Margareta; Săndulache, Diana Elena; Nechita, Corina Andreea

2017-01-01

The aim of the study was to analyze the effects that gadgets have on eyesight quality. A prospective observational study was conducted from January to July 2016, on 60 people who were divided into two groups: Group 1 – 30 middle school pupils with a mean age of 11.9 ± 1.86 and Group 2 – 30 patients evaluated in the Ophthalmology Clinic, “Sf. Spiridon” Hospital, Iași, with a mean age of 21.36 ± 7.16 years. The clinical parameters observed were the following: visual acuity (VA), objective refraction, binocular vision (BV), fusional amplitude (FA), Schirmer’s test. A questionnaire was also distributed, which contained 8 questions that highlighted the gadget’s impact on the eyesight. The use of different gadgets, such as computer, laptops, mobile phones or other displays become part of our everyday life and people experience a variety of ocular symptoms or vision problems related to these. Computer Vision Syndrome (CVS) represents a group of visual and extraocular symptoms associated with sustained use of visual display terminals. Headache, blurred vision, and ocular congestion are the most frequent manifestations determined by the long time use of gadgets. Mobile phones and laptops are the most frequently used gadgets. People who use gadgets for a long time have a sustained effort for accommodation. A small amount of refractive errors (especially myopic shift) was objectively recorded by various studies on near work. Dry eye syndrome could also be identified, and an improvement of visual comfort could be observed after the instillation of artificial tears drops. Computer Vision Syndrome is still under-diagnosed, and people should be made aware of the bad effects the prolonged use of gadgets has on eyesight. PMID:29450383

A Visual Profile of Queensland Indigenous Children.

PubMed

Hopkins, Shelley; Sampson, Geoff P; Hendicott, Peter L; Wood, Joanne M

2016-03-01

Little is known about the prevalence of refractive error, binocular vision, and other visual conditions in Australian Indigenous children. This is important given the association of these visual conditions with reduced reading performance in the wider population, which may also contribute to the suboptimal reading performance reported in this population. The aim of this study was to develop a visual profile of Queensland Indigenous children. Vision testing was performed on 595 primary schoolchildren in Queensland, Australia. Vision parameters measured included visual acuity, refractive error, color vision, nearpoint of convergence, horizontal heterophoria, fusional vergence range, accommodative facility, AC/A ratio, visual motor integration, and rapid automatized naming. Near heterophoria, nearpoint of convergence, and near fusional vergence range were used to classify convergence insufficiency (CI). Although refractive error (Indigenous, 10%; non-Indigenous, 16%; p = 0.04) and strabismus (Indigenous, 0%; non-Indigenous, 3%; p = 0.03) were significantly less common in Indigenous children, CI was twice as prevalent (Indigenous, 10%; non-Indigenous, 5%; p = 0.04). Reduced visual information processing skills were more common in Indigenous children (reduced visual motor integration [Indigenous, 28%; non-Indigenous, 16%; p < 0.01] and slower rapid automatized naming [Indigenous, 67%; non-Indigenous, 59%; p = 0.04]). The prevalence of visual impairment (reduced visual acuity) and color vision deficiency was similar between groups. Indigenous children have less refractive error and strabismus than their non-Indigenous peers. However, CI and reduced visual information processing skills were more common in this group. Given that vision screenings primarily target visual acuity assessment and strabismus detection, this is an important finding as many Indigenous children with CI and reduced visual information processing may be missed. Emphasis should be placed on identifying children with CI and reduced visual information processing given the potential effect of these conditions on school performance.

Adaptability of the Immature Ocular Motor Control System: Unilateral IGF-1 Medial Rectus Treatment.

PubMed

Willoughby, Christy L; Fleuriet, Jérome; Walton, Mark M; Mustari, Michael J; McLoon, Linda K

2015-06-01

Unilateral treatment with sustained release IGF-1 to one medial rectus muscle in infant monkeys was performed to test the hypothesis that strabismus would develop as a result of changes in extraocular muscles during the critical period of development of binocularity. Sustained release IGF-1 pellets were implanted unilaterally on one medial rectus muscle in normal infant monkeys during the first 2 weeks of life. Eye position was monitored using standard photographic methods. After 3 months of treatment, myofiber and neuromuscular size, myosin composition, and innervation density were quantified in all rectus muscles and compared to those in age-matched controls. Sustained unilateral IGF-1 treatments resulted in strabismus for all treated subjects; 3 of the 4 subjects had a clinically significant strabismus of more than 10°. Both the treated medial rectus and the untreated ipsilateral antagonist lateral rectus muscles had significantly larger myofibers. No adaptation in myofiber size occurred in the contralateral functionally yoked lateral rectus or in myosin composition, neuromuscular junction size, or nerve density. Sustained unilateral IGF-1 treatment to extraocular muscles during the sensitive period of development of orthotropic eye alignment and binocularity was sufficient to disturb ocular motor development, resulting in strabismus in infant monkeys. This could be due to altering fusion of gaze during the early sensitive period. Serial measurements of eye alignment suggested the IGF-1-treated infants received insufficient coordinated binocular experience, preventing the establishment of normal eye alignment. Our results uniquely suggest that abnormal signaling by the extraocular muscles may be a cause of strabismus.

Adaptability of the Immature Ocular Motor Control System: Unilateral IGF-1 Medial Rectus Treatment

PubMed Central

Willoughby, Christy L.; Fleuriet, Jérome; Walton, Mark M.; Mustari, Michael J.; McLoon, Linda K.

2015-01-01

Purpose. Unilateral treatment with sustained release IGF-1 to one medial rectus muscle in infant monkeys was performed to test the hypothesis that strabismus would develop as a result of changes in extraocular muscles during the critical period of development of binocularity. Methods. Sustained release IGF-1 pellets were implanted unilaterally on one medial rectus muscle in normal infant monkeys during the first 2 weeks of life. Eye position was monitored using standard photographic methods. After 3 months of treatment, myofiber and neuromuscular size, myosin composition, and innervation density were quantified in all rectus muscles and compared to those in age-matched controls. Results. Sustained unilateral IGF-1 treatments resulted in strabismus for all treated subjects; 3 of the 4 subjects had a clinically significant strabismus of more than 10°. Both the treated medial rectus and the untreated ipsilateral antagonist lateral rectus muscles had significantly larger myofibers. No adaptation in myofiber size occurred in the contralateral functionally yoked lateral rectus or in myosin composition, neuromuscular junction size, or nerve density. Conclusions. Sustained unilateral IGF-1 treatment to extraocular muscles during the sensitive period of development of orthotropic eye alignment and binocularity was sufficient to disturb ocular motor development, resulting in strabismus in infant monkeys. This could be due to altering fusion of gaze during the early sensitive period. Serial measurements of eye alignment suggested the IGF-1-treated infants received insufficient coordinated binocular experience, preventing the establishment of normal eye alignment. Our results uniquely suggest that abnormal signaling by the extraocular muscles may be a cause of strabismus. PMID:26030103

Temporal Binding Window of the Sound-Induced Flash Illusion in Amblyopia.

PubMed

Narinesingh, Cindy; Goltz, Herbert C; Wong, Agnes M F

2017-03-01

Amblyopia is a neurodevelopmental visual disorder caused by abnormal visual experience in childhood. In addition to known visual deficits, there is evidence for changes in audiovisual integration in amblyopia using explicit tasks. We examined audiovisual integration in amblyopia using an implicit task that is more relevant in a real-world context. A total of 11 participants with amblyopia and 16 controls were tested binocularly and monocularly on the sound-induced flash illusion, in which flashes and beeps are presented concurrently and the perceived number of flashes is influenced by the number of beeps. The task used 1 to 2 rapid peripheral flashes presented with 0 to 2 beeps, at 5 stimulus onset asynchronies, that is, beep (-200 milliseconds, -100 milliseconds) or flash leading (100 milliseconds, 200 milliseconds) or simultaneous (0 milliseconds). Participants reported the number of perceived flashes. Susceptibility was indicated by a "2 flashes" response to "fission" (1 flash, 2 beeps) or "1 flash" to "fusion" (2 flashes, 1 beep). For fission with the beep leading during binocular viewing, controls showed an expected decrease in illusion strength as stimulus onset asynchronies increased, whereas the illusion strength remained constant in participants with amblyopia, indicating a wider temporal binding window in amblyopia (P = 0.007). For fusion, participants with amblyopia showed reduced illusion strength during amblyopic eye viewing (P = 0.044) with the flash leading. Amblyopia is associated with the widening of the temporal binding window, specifically for fission when viewing binocularly with the beep leading. This suggests a developmental adaptation to delayed amblyopic eye visual processing to optimize audiovisual integration.

Visual outcomes of patients bilaterally implanted with the extended range of vision intraocular lens: A prospective study

PubMed Central

Sachdev, Gitansha Shreyas; Ramamurthy, Shreyas; Sharma, Umesh; Dandapani, Ramamurthy

2018-01-01

Purpose: The aim of this study was to analyze the objective and subjective visual outcomes of patients bilaterally implanted with the extended range of vision intraocular lens (EROV IOL), the Tecnis Symfony. Methods: This was a prospective interventional case series conducted at a tertiary eye care hospital in South India. The study included patients with bilateral implantation of EROV IOLs. The uncorrected and corrected visual acuity for distance, intermediate, and near vision was recorded at 6 weeks and 6 months’ postoperative visit. A subjective questionnaire was administered to assess spectacle independence, photic phenomenon, and overall satisfaction. All data were recorded using Microsoft Excel worksheet. The analyses were performed using SPSS for windows software. Results: Our study included fifty patients with bilateral implantation of EROV IOLs. The mean age was 59.84 ± 11.68 years. The mean uncorrected binocular distance, intermediate, and near visual acuity (in standard decimal equivalent) was 0.89,0.99 and 0.99 respectively, at 6 months’ postoperative visit. Ninety-six percent of the patients did not require spectacles for distance and 98% of the patients were free from spectacles for intermediate and near vision. 94% of our patients perceived no or minimal photic phenomena such as glare and halos. The mean subjective patient satisfaction score (out of 10) for distance, intermediate, and near was 9, 10, and 9, respectively. Conclusion: The EROV IOLs demonstrated high levels of spectacle independence for distance, intermediate, and near vision. The incidence of photic phenomena observed was minimal with a high level of patient satisfaction. PMID:29480252

Reproducibility of retinal nerve fiber layer thickness measures using eye tracking in children with nonglaucomatous optic neuropathy.

PubMed

Rajjoub, Raneem D; Trimboli-Heidler, Carmelina; Packer, Roger J; Avery, Robert A

2015-01-01

To determine the intra- and intervisit reproducibility of circumpapillary retinal nerve fiber layer (RNFL) thickness measures using eye tracking-assisted spectral-domain optical coherence tomography (SD OCT) in children with nonglaucomatous optic neuropathy. Prospective longitudinal study. Circumpapillary RNFL thickness measures were acquired with SD OCT using the eye-tracking feature at 2 separate study visits. Children with normal and abnormal vision (visual acuity ≥ 0.2 logMAR above normal and/or visual field loss) who demonstrated clinical and radiographic stability were enrolled. Intra- and intervisit reproducibility was calculated for the global average and 9 anatomic sectors by calculating the coefficient of variation and intraclass correlation coefficient. Forty-two subjects (median age 8.6 years, range 3.9-18.2 years) met inclusion criteria and contributed 62 study eyes. Both the abnormal and normal vision cohort demonstrated the lowest intravisit coefficient of variation for the global RNFL thickness. Intervisit reproducibility remained good for those with normal and abnormal vision, although small but statistically significant increases in the coefficient of variation were observed for multiple anatomic sectors in both cohorts. The magnitude of visual acuity loss was significantly associated with the global (ß = 0.026, P < .01) and temporal sector coefficient of variation (ß = 0.099, P < .01). SD OCT with eye tracking demonstrates highly reproducible RNFL thickness measures. Subjects with vision loss demonstrate greater intra- and intervisit variability than those with normal vision. Copyright © 2015 Elsevier Inc. All rights reserved.

The visual impact of gossip.

PubMed

Anderson, Eric; Siegel, Erika H; Bliss-Moreau, Eliza; Barrett, Lisa Feldman

2011-06-17

Gossip is a form of affective information about who is friend and who is foe. We show that gossip does not influence only how a face is evaluated--it affects whether a face is seen in the first place. In two experiments, neutral faces were paired with negative, positive, or neutral gossip and were then presented alone in a binocular rivalry paradigm (faces were presented to one eye, houses to the other). In both studies, faces previously paired with negative (but not positive or neutral) gossip dominated longer in visual consciousness. These findings demonstrate that gossip, as a potent form of social affective learning, can influence vision in a completely top-down manner, independent of the basic structural features of a face.

Dichoptic training improves contrast sensitivity in adults with amblyopia.

PubMed

Li, Jinrong; Spiegel, Daniel P; Hess, Robert F; Chen, Zidong; Chan, Lily Y L; Deng, Daming; Yu, Minbin; Thompson, Benjamin

2015-09-01

Dichoptic training is designed to promote binocular vision in patients with amblyopia. Initial studies have found that the training effects transfer to both binocular (stereopsis) and monocular (recognition acuity) visual functions. The aim of this study was to assess whether dichoptic training effects also transfer to contrast sensitivity (CS) in adults with amblyopia. We analyzed CS data from 30 adults who had taken part in one of two previous dichoptic training studies and assessed whether the changes in CS exceeded the 95% confidence intervals for change based on test-retest data from a separate group of observers with amblyopia. CS was measured using Gabor patches (0.5, 3 and 10cpd) before and after 10days of dichoptic training. Training was delivered using a dichoptic video game viewed through video goggles (n=15) or on an iPod touch equipped with a lenticular overlay screen (n=15). In the iPod touch study, training was combined with anodal transcranial direct current stimulation of the visual cortex. We found that dichoptic training significantly improved CS across all spatial frequencies tested for both groups. These results suggest that dichoptic training modifies the sensitivity of the neural systems that underpin monocular CS. Copyright © 2015 Elsevier Ltd. All rights reserved.

Slow and fast visual motion channels have independent binocular-rivalry stages.

PubMed Central

van de Grind, W. A.; van Hof, P.; van der Smagt, M. J.; Verstraten, F. A.

2001-01-01

We have previously reported a transparent motion after-effect indicating that the human visual system comprises separate slow and fast motion channels. Here, we report that the presentation of a fast motion in one eye and a slow motion in the other eye does not result in binocular rivalry but in a clear percept of transparent motion. We call this new visual phenomenon 'dichoptic motion transparency' (DMT). So far only the DMT phenomenon and the two motion after-effects (the 'classical' motion after-effect, seen after motion adaptation on a static test pattern, and the dynamic motion after-effect, seen on a dynamic-noise test pattern) appear to isolate the channels completely. The speed ranges of the slow and fast channels overlap strongly and are observer dependent. A model is presented that links after-effect durations of an observer to the probability of rivalry or DMT as a function of dichoptic velocity combinations. Model results support the assumption of two highly independent channels showing only within-channel rivalry, and no rivalry or after-effect interactions between the channels. The finding of two independent motion vision channels, each with a separate rivalry stage and a private line to conscious perception, might be helpful in visualizing or analysing pathways to consciousness. PMID:11270442

Optometric measurements predict performance but not comfort on a virtual object placement task with a stereoscopic three-dimensional display

NASA Astrophysics Data System (ADS)

McIntire, John P.; Wright, Steve T.; Harrington, Lawrence K.; Havig, Paul R.; Watamaniuk, Scott N. J.; Heft, Eric L.

2014-06-01

Twelve participants were tested on a simple virtual object precision placement task while viewing a stereoscopic three-dimensional (S3-D) display. Inclusion criteria included uncorrected or best corrected vision of 20/20 or better in each eye and stereopsis of at least 40 arc sec using the Titmus stereotest. Additionally, binocular function was assessed, including measurements of distant and near phoria (horizontal and vertical) and distant and near horizontal fusion ranges using standard optometric clinical techniques. Before each of six 30 min experimental sessions, measurements of phoria and fusion ranges were repeated using a Keystone View Telebinocular and an S3-D display, respectively. All participants completed experimental sessions in which the task required the precision placement of a virtual object in depth at the same location as a target object. Subjective discomfort was assessed using the simulator sickness questionnaire. Individual placement accuracy in S3-D trials was significantly correlated with several of the binocular screening outcomes: viewers with larger convergent fusion ranges (measured at near distance), larger total fusion ranges (convergent plus divergent ranges, measured at near distance), and/or lower (better) stereoscopic acuity thresholds were more accurate on the placement task. No screening measures were predictive of subjective discomfort, perhaps due to the low levels of discomfort induced.

The red-green visual pigment gene region in adrenoleukodystrophy.

PubMed Central

Aubourg, P; Feil, R; Guidoux, S; Kaplan, J C; Moser, H; Kahn, A; Mandel, J L

1990-01-01

Although recent data established that a specific very-long-chain fatty acyl-CoA synthetase is defective in X-linked adrenoleukodystrophy (ALD), the ALD gene is still unidentified. The ALD locus has been mapped to Xq28, like the red and green color pigment genes. Abnormal color vision has been observed in 12 of 27 patients with adrenomyeloneuropathy (AMN), a milder form of ALD. Furthermore, rearrangements of the color vision gene cluster were found in four of eight ALD kindreds. This led us to propose that a single DNA rearrangement could underlie both ALD and abnormal color vision in these patients. Study of 34 French ALD patients failed to reveal a higher than expected frequency of green/red visual pigment rearrangements 3' to the red/green color vision gene complex. The previous report of such rearrangements was based on small numbers and lack of knowledge that the frequency of "abnormal" color vision arrays on molecular analysis was twice as high as expected on the basis of the frequency of phenotypic color vision defects. The red/green color pigment (R/GCP) region was studied by pulsed-field gel electrophoresis in 14 of these patients, and we did not find any fragment size difference between the patients and normal individuals who have the same number of pigment genes. The R/GCP region was also analyzed in 29 French and seven North American ALD patients by using six genomic DNA probes, isolated from a cosmid walk, that flank the color vision genes. No deletions were found with probes that lie 3' of the green pigment genes. One of the eight previously reported ALD individuals has a long deletion 5' of the red pigment gene, a deletion causing blue cone monochromacy. This finding and the previous findings of a 45% frequency of phenotypic color vision defects in patients with AMN may suggest that the ALD/AMN gene lies 5' to the red pigment gene and that the frequent phenotypic color vision anomalies owe their origin to deleted DNA that includes regulatory genes for color vision. It is possible, however, that phenotypic color vision anomalies in AMN may be phenocopies secondary to retinal or neural involvement by the disease. The single case of blue cone monochromacy may therefore be a fortuitous coincidence of two diseases. Images p[466]-a Figure 3 Figure 4 Figure 5 Figure 7 Figure 8 PMID:2309698

Association Between Retinal Nerve Fiber Layer Thickness and Abnormalities of Vision in People With Human Immunodeficiency Virus Infection

PubMed Central

Kalyani, Partho S.; Holland, Gary N.; Fawzi, Amani A.; Arantes, Tiago E.F.; Yu, Fei; Sadun, Alfredo A.

2014-01-01

Purpose To investigate relationships between contrast sensitivity (CS), color vision, and retinal nerve fiber layer (RNFL) among people with human immunodeficiency virus (HIV) infection; to evaluate the effect of time since diagnosis of HIV infection on RNFL thickness. Design Noninterventional cross-sectional study. Methods We evaluated 102 eyes of 57 HIV-infected individuals without ocular opportunistic infections. Peripapillary RNFL thickness was determined with spectraldomain optical coherence tomography in 4 quadrants. CS was measured with the Pelli-Robson technique (expressed as logCS); color vision was measured with the Lanthony desaturated 15-hue technique (expressed as color confusion index [C-index], with higher scores indicating worse color vision). Correlations between values were assessed using Spearman correlation coefficients. Results Median RNFL thickness (average of 4 quadrants) was 102.9 μm (range, 75.0–134.7 μm). Median logCS was 1.90 (range, 1.25–1.95). Median C-index was 1.58 (range, 0.96–4.07). Temporal RNFL thickness was correlated with logCS (r = 0.295, P = .003) and C-index (r = −0.338, P = .0005). Time since diagnosis of HIV infection was shorter for those with thick average RNFL than for those with thin average RNFL (P = .18). Conclusions Both worse CS and worse color vision are correlated with thinning of the temporal RNFL, with possible threshold effects. Increased prevalences of abnormal CS and abnormal color vision in this population are therefore likely attributable to neuroretinal compromise. This pattern of structural and functional losses may reflect preferential damage to small-caliber axons in the maculopapillary bundle, possibly associated with mitochondrial dysfunction, providing a potential disease mechanism for HIV-associated “neuroretinal disorder.” PMID:22245459

Wavefront-Guided Versus Wavefront-Optimized Photorefractive Keratectomy: Visual and Military Task Performance.

PubMed

Ryan, Denise S; Sia, Rose K; Stutzman, Richard D; Pasternak, Joseph F; Howard, Robin S; Howell, Christopher L; Maurer, Tana; Torres, Mark F; Bower, Kraig S

2017-01-01

To compare visual performance, marksmanship performance, and threshold target identification following wavefront-guided (WFG) versus wavefront-optimized (WFO) photorefractive keratectomy (PRK). In this prospective, randomized clinical trial, active duty U.S. military Soldiers, age 21 or over, electing to undergo PRK were randomized to undergo WFG (n = 27) or WFO (n = 27) PRK for myopia or myopic astigmatism. Binocular visual performance was assessed preoperatively and 1, 3, and 6 months postoperatively: Super Vision Test high contrast, Super Vision Test contrast sensitivity (CS), and 25% contrast acuity with night vision goggle filter. CS function was generated testing at five spatial frequencies. Marksmanship performance in low light conditions was evaluated in a firing tunnel. Target detection and identification performance was tested for probability of identification of varying target sets and probability of detection of humans in cluttered environments. Visual performance, CS function, marksmanship, and threshold target identification demonstrated no statistically significant differences over time between the two treatments. Exploratory regression analysis of firing range tasks at 6 months showed no significant differences or correlations between procedures. Regression analysis of vehicle and handheld probability of identification showed a significant association with pretreatment performance. Both WFG and WFO PRK results translate to excellent and comparable visual and military performance. Reprint & Copyright © 2017 Association of Military Surgeons of the U.S.

DLP™-based dichoptic vision test system

NASA Astrophysics Data System (ADS)

Woods, Russell L.; Apfelbaum, Henry L.; Peli, Eli

2010-01-01

It can be useful to present a different image to each of the two eyes while they cooperatively view the world. Such dichoptic presentation can occur in investigations of stereoscopic and binocular vision (e.g., strabismus, amblyopia) and vision rehabilitation in clinical and research settings. Various techniques have been used to construct dichoptic displays. The most common and most flexible modern technique uses liquid-crystal (LC) shutters. When used in combination with cathode ray tube (CRT) displays, there is often leakage of light from the image intended for one eye into the view of the other eye. Such interocular crosstalk is 14% even in our state of the art CRT-based dichoptic system. While such crosstalk may have minimal impact on stereo movie or video game experiences, it can defeat clinical and research investigations. We use micromirror digital light processing (DLP™) technology to create a novel dichoptic visual display system with substantially lower interocular crosstalk (0.3% remaining crosstalk comes from the LC shutters). The DLP system normally uses a color wheel to display color images. Our approach is to disable the color wheel, synchronize the display directly to the computer's sync signal, allocate each of the three (former) color presentations to one or both eyes, and open and close the LC shutters in synchrony with those color events.

Visual fields and eye morphology support color vision in a color-changing crab-spider.

PubMed

Insausti, Teresita C; Defrize, Jérémy; Lazzari, Claudio R; Casas, Jérôme

2012-03-01

Vision plays a major role in many spiders, being involved in prey hunting, orientation or substrate choice, among others. In Misumena vatia, which experiences morphological color changes, vision has been reported to be involved in substrate color matching. Electrophysiological evidence reveals that at least two types of photoreceptors are present in this species, but these data are not backed up by morphological evidence. This work analyzes the functional structure of the eyes of this spider and relates it to its color-changing abilities. A broad superposition of the visual field of the different eyes was observed, even between binocular regions of principal and secondary eyes. The frontal space is simultaneously analyzed by four eyes. This superposition supports the integration of the visual information provided by the different eye types. The mobile retina of the principal eyes of this spider is organized in three layers of three different types of rhabdoms. The third and deepest layer is composed by just one large rhabdom surrounded by dark screening pigments that limit the light entry. The three pairs of secondary eyes have all a single layer of rhabdoms. Our findings provide strong support for an involvement of the visual system in color matching in this spider. Copyright © 2011 Elsevier Ltd. All rights reserved.

Binocular eye movement control and motion perception: what is being tracked?

PubMed

van der Steen, Johannes; Dits, Joyce

2012-10-19

We investigated under what conditions humans can make independent slow phase eye movements. The ability to make independent movements of the two eyes generally is attributed to few specialized lateral eyed animal species, for example chameleons. In our study, we showed that humans also can move the eyes in different directions. To maintain binocular retinal correspondence independent slow phase movements of each eye are produced. We used the scleral search coil method to measure binocular eye movements in response to dichoptically viewed visual stimuli oscillating in orthogonal direction. Correlated stimuli led to orthogonal slow eye movements, while the binocularly perceived motion was the vector sum of the motion presented to each eye. The importance of binocular fusion on independency of the movements of the two eyes was investigated with anti-correlated stimuli. The perceived global motion pattern of anti-correlated dichoptic stimuli was perceived as an oblique oscillatory motion, as well as resulted in a conjugate oblique motion of the eyes. We propose that the ability to make independent slow phase eye movements in humans is used to maintain binocular retinal correspondence. Eye-of-origin and binocular information are used during the processing of binocular visual information, and it is decided at an early stage whether binocular or monocular motion information and independent slow phase eye movements of each eye are produced during binocular tracking.

Binocular Eye Movement Control and Motion Perception: What Is Being Tracked?

PubMed Central

van der Steen, Johannes; Dits, Joyce

2012-01-01

Purpose. We investigated under what conditions humans can make independent slow phase eye movements. The ability to make independent movements of the two eyes generally is attributed to few specialized lateral eyed animal species, for example chameleons. In our study, we showed that humans also can move the eyes in different directions. To maintain binocular retinal correspondence independent slow phase movements of each eye are produced. Methods. We used the scleral search coil method to measure binocular eye movements in response to dichoptically viewed visual stimuli oscillating in orthogonal direction. Results. Correlated stimuli led to orthogonal slow eye movements, while the binocularly perceived motion was the vector sum of the motion presented to each eye. The importance of binocular fusion on independency of the movements of the two eyes was investigated with anti-correlated stimuli. The perceived global motion pattern of anti-correlated dichoptic stimuli was perceived as an oblique oscillatory motion, as well as resulted in a conjugate oblique motion of the eyes. Conclusions. We propose that the ability to make independent slow phase eye movements in humans is used to maintain binocular retinal correspondence. Eye-of-origin and binocular information are used during the processing of binocular visual information, and it is decided at an early stage whether binocular or monocular motion information and independent slow phase eye movements of each eye are produced during binocular tracking. PMID:22997286

Normative values for a tablet computer-based application to assess chromatic contrast sensitivity.

PubMed

Bodduluri, Lakshmi; Boon, Mei Ying; Ryan, Malcolm; Dain, Stephen J

2018-04-01

Tablet computer displays are amenable for the development of vision tests in a portable form. Assessing color vision using an easily accessible and portable test may help in the self-monitoring of vision-related changes in ocular/systemic conditions and assist in the early detection of disease processes. Tablet computer-based games were developed with different levels of gamification as a more portable option to assess chromatic contrast sensitivity. Game 1 was designed as a clinical version with no gaming elements. Game 2 was a gamified version of game 1 (added fun elements: feedback, scores, and sounds) and game 3 was a complete game with vision task nested within. The current study aimed to determine the normative values and evaluate repeatability of the tablet computer-based games in comparison with an established test, the Cambridge Colour Test (CCT) Trivector test. Normally sighted individuals [N = 100, median (range) age 19.0 years (18-56 years)] had their chromatic contrast sensitivity evaluated binocularly using the three games and the CCT. Games 1 and 2 and the CCT showed similar absolute thresholds and tolerance intervals, and game 3 had significantly lower values than games 1, 2, and the CCT, due to visual task differences. With the exception of game 3 for blue-yellow, the CCT and tablet computer-based games showed similar repeatability with comparable 95% limits of agreement. The custom-designed games are portable, rapid, and may find application in routine clinical practice, especially for testing younger populations.

Vision therapy in adults with convergence insufficiency: clinical and functional magnetic resonance imaging measures.

PubMed

Alvarez, Tara L; Vicci, Vincent R; Alkan, Yelda; Kim, Eun H; Gohel, Suril; Barrett, Anna M; Chiaravalloti, Nancy; Biswal, Bharat B

2010-12-01

This research quantified clinical measurements and functional neural changes associated with vision therapy in subjects with convergence insufficiency (CI). Convergence and divergence 4° step responses were compared between 13 control adult subjects with normal binocular vision and four CI adult subjects. All CI subjects participated in 18 h of vision therapy. Clinical parameters quantified throughout the therapy included: nearpoint of convergence, recovery point of convergence, positive fusional vergence at near, near dissociated phoria, and eye movements that were quantified using peak velocity. Neural correlates of the CI subjects were quantified with functional magnetic resonance imaging scans comparing random vs. predictable vergence movements using a block design before and after vision therapy. Images were quantified by measuring the spatial extent of activation and the average correlation within five regions of interests (ROI). The ROIs were the dorsolateral prefrontal cortex, a portion of the frontal lobe, part of the parietal lobe, the cerebellum, and the brain stem. All measurements were repeated 4 months to 1 year post-therapy in three of the CI subjects. Convergence average peak velocities to step stimuli were significantly slower (p = 0.016) in CI subjects compared with controls; however, significant differences in average peak velocities were not observed for divergence step responses (p = 0.30). The investigation of CI subjects participating in vision therapy showed that the nearpoint of convergence, recovery point of convergence, and near dissociated phoria significantly decreased. Furthermore, the positive fusional vergence, average peak velocity from 4° convergence steps, and the amount of functional activity within the frontal areas, cerebellum, and brain stem significantly increased. Several clinical and cortical parameters were significantly correlated. Convergence peak velocity was significantly slower in CI subjects compared with controls, which may result in asthenopic complaints reported by the CI subjects. Vision therapy was associated with and may have evoked clinical and cortical activity changes.

Vision Therapy in Adults with Convergence Insufficiency: Clinical and Functional Magnetic Resonance Imaging Measures

PubMed Central

Alvarez, Tara L.; Vicci, Vincent R.; Alkan, Yelda; Kim, Eun H.; Gohel, Suril; Barrett, Anna M.; Chiaravalloti, Nancy; Biswal, Bharat B.

2011-01-01

Purpose This research quantified clinical measurements and functional neural changes associated with vision therapy in subjects with convergence insufficiency (CI). Methods Convergence and divergence 4° step responses were compared between 13 control adult subjects with normal binocular vision and four CI adult subjects. All CI subjects participated in 18 h of vision therapy. Clinical parameters quantified throughout the therapy included: nearpoint of convergence, recovery point of convergence, positive fusional vergence at near, near dissociated phoria, and eye movements that were quantified using peak velocity. Neural correlates of the CI subjects were quantified with functional magnetic resonance imaging scans comparing random vs. predictable vergence movements using a block design before and after vision therapy. Images were quantified by measuring the spatial extent of activation and the average correlation within five regions of interests (ROI). The ROIs were the dorsolateral prefrontal cortex, a portion of the frontal lobe, part of the parietal lobe, the cerebellum, and the brain stem. All measurements were repeated 4 months to 1 year post-therapy in three of the CI subjects. Results Convergence average peak velocities to step stimuli were significantly slower (p = 0.016) in CI subjects compared with controls; however, significant differences in average peak velocities were not observed for divergence step responses (p = 0.30). The investigation of CI subjects participating in vision therapy showed that the nearpoint of convergence, recovery point of convergence, and near dissociated phoria significantly decreased. Furthermore, the positive fusional vergence, average peak velocity from 4° convergence steps, and the amount of functional activity within the frontal areas, cerebellum, and brain stem significantly increased. Several clinical and cortical parameters were significantly correlated. Conclusions Convergence peak velocity was significantly slower in CI subjects compared with controls, which may result in asthenopic complaints reported by the CI subjects. Vision therapy was associated with and may have evoked clinical and cortical activity changes. PMID:21057347

Acute Blindness.

PubMed

Meekins, Jessica M

2015-09-01

Sudden loss of vision is an ophthalmic emergency with numerous possible causes. Abnormalities may occur at any point within the complex vision pathway, from retina to optic nerve to the visual center in the occipital lobe. This article reviews specific prechiasm (retina and optic nerve) and cerebral cortical diseases that lead to acute blindness. Information regarding specific etiologies, pathophysiology, diagnosis, treatment, and prognosis for vision is discussed. Copyright © 2015 Elsevier Inc. All rights reserved.

21 CFR 886.5120 - Low-power binocular loupe.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Low-power binocular loupe. 886.5120 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5120 Low-power binocular loupe. (a) Identification. A low-power binocular loupe is a device that consists of two eyepieces, each with a lens or lens...

Binocular Combination of Second-Order Stimuli

PubMed Central

Zhou, Jiawei; Liu, Rong; Zhou, Yifeng; Hess, Robert F.

2014-01-01

Phase information is a fundamental aspect of visual stimuli. However, the nature of the binocular combination of stimuli defined by modulations in contrast, so-called second-order stimuli, is presently not clear. To address this issue, we measured binocular combination for first- (luminance modulated) and second-order (contrast modulated) stimuli using a binocular phase combination paradigm in seven normal adults. We found that the binocular perceived phase of second-order gratings depends on the interocular signal ratio as has been previously shown for their first order counterparts; the interocular signal ratios when the two eyes were balanced was close to 1 in both first- and second-order phase combinations. However, second-order combination is more linear than previously found for first-order combination. Furthermore, binocular combination of second-order stimuli was similar regardless of whether the carriers in the two eyes were correlated, anti-correlated, or uncorrelated. This suggests that, in normal adults, the binocular phase combination of second-order stimuli occurs after the monocular extracting of the second-order modulations. The sensory balance associated with this second-order combination can be obtained from binocular phase combination measurements. PMID:24404180

A complete investigation of monocular and binocular functions in clinically treated amblyopia.

PubMed

Zhao, Wuxiao; Jia, Wu-Li; Chen, Ge; Luo, Yan; Lin, Borong; He, Qing; Lu, Zhong-Lin; Li, Min; Huang, Chang-Bing

2017-09-06

The gold standard of a successful amblyopia treatment is full recovery of visual acuity (VA) in the amblyopic eye, but there has been no systematic study on both monocular and binocular visual functions. In this research, we aimed to quantify visual qualities with a variety of perceptual tasks in subjects with treated amblyopia. We found near stereoacuity and pAE dominance in binocular rivalry in "treated" amblyopia were largely comparable to those of normal subjects. CSF of the pAE remained deficient in high spatial frequencies. The binocular contrast summation ratio is significantly lower than normal standard. The interocular balance point is 34%, indicating that contrast in pAE is much less effective as the same contrast in pFE in binocular phase combination. Although VA, stereoacuity and binocular rivalry at low spatial frequency in treated amblyopes were normal or nearly normal, the pAE remained "lazy" in high frequency domain, binocular contrast summation, and interocular phase combination. Our results suggest that structured monocular and binocular training are necessary to fully recover deficient functions in amblyopia.

Surgical planning and innervation in pontine gaze palsy with ipsilateral esotropia.

PubMed

Somer, Deniz; Cinar, Fatma Gul; Kaderli, Ahmet; Ornek, Firdevs

2016-10-01

To discuss surgical intervention strategies among patients with horizontal gaze palsy with concurrent esotropia. Five consecutive patients with dorsal pontine lesions are presented. Each patient had horizontal gaze palsy with symptomatic diplopia as a consequence of esotropia in primary gaze and an anomalous head turn to attain single binocular vision. Clinical findings in the first 2 patients led us to presume there was complete loss of rectus muscle function from rectus muscle palsy. Based on this assumption, medial rectus recessions with simultaneous partial vertical muscle transposition (VRT) on the ipsilateral eye of the gaze palsy and recession-resection surgery on the contralateral eye were performed, resulting in significant motility limitation. Sequential recession-resection surgery without simultaneous VRT on the 3rd patient created an unexpected motility improvement to the side of gaze palsy, an observation differentiating rectus muscle palsy from paresis. Recession combined with VRT approach in the esotropic eye was abandoned on subsequent patients. Simultaneous recession-resection surgery without VRT in the next 2 patients resulted in alleviation of head postures, resolution of esotropia, and also substantial motility improvements to the ipsilateral hemifield of gaze palsy without limitations in adduction and vertical deviations. Ocular misalignment and abnormal head posture as a result of conjugate gaze palsy can be successfully treated by basic recession-resection surgery, with the advantage of increasing versions to the ipsilateral side of the gaze palsy. Improved motility after surgery presumably represents paresis, not "paralysis," with residual innervation in rectus muscles. Copyright © 2016 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.

Vision in two cyprinid fish: implications for collective behavior

PubMed Central

Moore, Bret A.; Tyrrell, Luke P.; Fernández-Juricic, Esteban

2015-01-01

Many species of fish rely on their visual systems to interact with conspecifics and these interactions can lead to collective behavior. Individual-based models have been used to predict collective interactions; however, these models generally make simplistic assumptions about the sensory systems that are applied without proper empirical testing to different species. This could limit our ability to predict (and test empirically) collective behavior in species with very different sensory requirements. In this study, we characterized components of the visual system in two species of cyprinid fish known to engage in visually dependent collective interactions (zebrafish Danio rerio and golden shiner Notemigonus crysoleucas) and derived quantitative predictions about the positioning of individuals within schools. We found that both species had relatively narrow binocular and blind fields and wide visual coverage. However, golden shiners had more visual coverage in the vertical plane (binocular field extending behind the head) and higher visual acuity than zebrafish. The centers of acute vision (areae) of both species projected in the fronto-dorsal region of the visual field, but those of the zebrafish projected more dorsally than those of the golden shiner. Based on this visual sensory information, we predicted that: (a) predator detection time could be increased by >1,000% in zebrafish and >100% in golden shiners with an increase in nearest neighbor distance, (b) zebrafish schools would have a higher roughness value (surface area/volume ratio) than those of golden shiners, (c) and that nearest neighbor distance would vary from 8 to 20 cm to visually resolve conspecific striping patterns in both species. Overall, considering between-species differences in the sensory system of species exhibiting collective behavior could change the predictions about the positioning of individuals in the group as well as the shape of the school, which can have implications for group cohesion. We suggest that more effort should be invested in assessing the role of the sensory system in shaping local interactions driving collective behavior. PMID:26290783

Potential hazards of viewing 3-D stereoscopic television, cinema and computer games: a review.

PubMed

Howarth, Peter A

2011-03-01

The visual stimulus provided by a 3-D stereoscopic display differs from that of the real world because the image provided to each eye is produced on a flat surface. The distance from the screen to the eye remains fixed, providing a single focal distance, but the introduction of disparity between the images allows objects to be located geometrically in front of, or behind, the screen. Unlike in the real world, the stimulus to accommodation and the stimulus to convergence do not match. Although this mismatch is used positively in some forms of Orthoptic treatment, a number of authors have suggested that it could negatively lead to the development of asthenopic symptoms. From knowledge of the zone of clear, comfortable, single binocular vision one can predict that, for people with normal binocular vision, adverse symptoms will not be present if the discrepancy is small, but are likely if it is large, and that what constitutes 'large' and 'small' are idiosyncratic to the individual. The accommodation-convergence mismatch is not, however, the only difference between the natural and the artificial stimuli. In the former case, an object located in front of, or behind, a fixated object will not only be perceived as double if the images fall outside Panum's fusional areas, but it will also be defocused and blurred. In the latter case, however, it is usual for the producers of cinema, TV or computer game content to provide an image that is in focus over the whole of the display, and as a consequence diplopic images will be sharply in focus. The size of Panum's fusional area is spatial frequency-dependent, and because of this the high spatial frequencies present in the diplopic 3-D image will provide a different stimulus to the fusion system from that found naturally. © 2011 The College of Optometrists.

Do older drivers with bilateral cataract self-regulate their driving while waiting for first eye cataract surgery?

PubMed Central

Agramunt, Seraina; Meuleners, Lynn B; Fraser, Michelle L; Chow, Kyle C; Ng, Jonathon Q; Raja, Vignesh; Morlet, Nigel

2017-01-01

Objectives To analyze the association between visual impairment and driver self-regulation among a cohort of older drivers waiting for first eye cataract surgery. Methods Ninety-six drivers with bilateral cataract aged 55+ years were assessed before first eye cataract surgery. Data collection consisted of a researcher-administered questionnaire, objective visual measures (visual acuity, contrast sensitivity and stereopsis), a visual attention test (the useful field of view test) and a cognitive test (the Mini-Mental State Examination). Driver self-regulation practices were collected using the Driving Habits Questionnaire and were also measured with an in-vehicle monitoring device. Characteristics of self-regulators and non-self-regulators were compared and a logistic regression model was used to examine the association between 3 objective visual measures and driver self-regulation status. Results After controlling for potential confounding factors, only binocular contrast sensitivity (p=0.01), age (p=0.03) and gender (p=0.03) were significantly associated with driver self-regulation status. The odds of participants with better contrast sensitivity scores (better vision) self-regulating their driving in at least 1 driving situation decreased (odds ratio [OR]: 0.01, 95% CI: 0.00–0.28) while those of increasing age reported an increased odds of self-regulating their driving (OR: 1.08, 95% CI: 1.01–1.15). The odds of males self-regulating their driving was decreased compared with females (OR: 0.28, 95% CI: 0.09–0.86). Conclusions Worse binocular contrast sensitivity scores, increasing age and being female were significantly associated with driver self-regulation. The study highlighted that while self-regulation was common among cataract patients, a proportion of those with poor vision did not self-regulate. Further research should determine how cataract patients could benefit from self-regulation strategies while waiting for cataract surgery. PMID:29184397

Duane's retraction syndrome: a retrospective review from Kathmandu, Nepal.

PubMed

Shrestha, Gauri Shankar; Sharma, Ananda Kumar

2012-01-01

  The aim was to study the clinical characteristics of Duane's retraction syndrome (DRS) in Nepalese patients.   Medical records from 52 cases of DRS from May 2003 to April 2010 were retrospectively reviewed for age, gender, laterality and clinical characteristics. Forty-one case records (78.8 per cent) that had complete clinical findings were considered for further evaluation. Examination included visual acuity by Snellen chart, refraction, associated horizontal and vertical strabismus in primary gaze, upshoot and downshoot on attempted adduction, binocular vision assessed with the Worth four-dot test on adopted gaze and stereopsis examined with the Titmus stereo test.   DRS type I was the most common type observed in 73.2 per cent of cases, followed by DRS type II (14.6 per cent) and DRS type III (12.2 per cent). It was more common in female patients (58.5 per cent) than male patients (χ(2) = 4.6, df = 1, p = 0.03). DRS was more common in the left eye (68.3 per cent) than the right eye and unilaterally present in 95.1 per cent of subjects. In primary gaze, orthotropia (41.5 per cent) was more common than exotropia (34.1 per cent) and esotropia (24.4 per cent) and vertical strabismus was present in 24.4 per cent of subjects. Upshoot and downshoot on attempted adduction was seen in 14.6 and 9.8 per cent, respectively. Binocular single vision was present in 68.3 per cent of subjects by Worth four-dot test at near. Stereopsis of 3,000 seconds of arc was present in 9.8 per cent, 100 to 200 seconds of arc in 14.6 per cent and 40 to 60 seconds of arc in 43.9 per cent with the Titmus stereo test.   DRS is more common in female patients and the left eye. DRS type I is the most common type. © 2011 The Authors. Clinical and Experimental Optometry © 2011 Optometrists Association Australia.

Sweep visually evoked potentials and visual findings in children with West syndrome.

PubMed

de Freitas Dotto, Patrícia; Cavascan, Nívea Nunes; Berezovsky, Adriana; Sacai, Paula Yuri; Rocha, Daniel Martins; Pereira, Josenilson Martins; Salomão, Solange Rios

2014-03-01

West syndrome (WS) is a type of early childhood epilepsy characterized by progressive neurological development deterioration that includes vision. To demonstrate the clinical importance of grating visual acuity thresholds (GVA) measurement by sweep visually evoked potentials technique (sweep-VEP) as a reliable tool for evaluation of the visual cortex status in WS children. This is a retrospective study of the best-corrected binocular GVA and ophthalmological features of WS children referred for the Laboratory of Clinical Electrophysiology of Vision of UNIFESP from 1998 to 2012 (Committee on Ethics in Research of UNIFESP n° 0349/08). The GVA deficit was calculated by subtracting binocular GVA score (logMAR units) of each patient from the median values of age norms from our own lab and classified as mild (0.1-0.39 logMAR), moderate (0.40-0.80 logMAR) or severe (>0.81 logMAR). Associated ophthalmological features were also described. Data from 30 WS children (age from 6 to 108 months, median = 14.5 months, mean ± SD = 22.0 ± 22.1 months; 19 male) were analyzed. The majority presented severe GVA deficit (0.15-1.44 logMAR; mean ± SD = 0.82 ± 0.32 logMAR; median = 0.82 logMAR), poor visual behavior, high prevalence of strabismus and great variability in ocular positioning. The GVA deficit did not vary according to gender (P = .8022), WS type (P = .908), birth age (P = .2881), perinatal oxygenation (P = .7692), visual behavior (P = .8789), ocular motility (P = .1821), nystagmus (P = .2868), risk of drug-induced retinopathy (P = .4632) and participation in early visual stimulation therapy (P = .9010). The sweep-VEP technique is a reliable tool to classify visual system impairment in WS children, in agreement with the poor visual behavior exhibited by them. Copyright © 2013 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.

Comparison of visual status of Iranian military and commercial drivers.

PubMed

Ghasemi, Mohammad; Hoseini Yazdi, Seyed Hosein; Heravian, Javad; Jafarzadehpur, Ebrahim; Rezaee, Maryam

2015-04-01

There is no legal requirement for Iranian military truck drivers to undergo regular visual checkups as compared to commercial truck drivers. This study aimed to evaluate the impact of drivers' visual checkups by comparing the visual function of Iranian military and commercial truck drivers. In this comparative cross-sectional study, two hundred military and 200 commercial truck drivers were recruited and their Visual Acuity (VA), Visual Field (VF), color vision and Contrast Sensitivity (CS) were assessed and compared using the Snellen chart, confrontation screening method, D15 test and Pelli-Robson letter chart, respectively. A questionnaire regarding driving exposure and history of motor-vehicle crashes (MVCs) was also filled by drivers. Results were analyzed using an independent samples t-test, one-way ANOVA (assessing difference in number of MVCs across different age groups), chi-square test and Pearson correlation at statistical significance level of P < 0.05. Mean age was 41.6 ± 9.2 for the military truck drivers and 43.4 ± 10.9 for commercial truck drivers (P > 0.05). No significant difference between military and commercial drivers was found in terms of driving experience, number of MVCs, binocular VA, frequency of color vision defects and CS scores. In contrast, the last ocular examination was significantly earlier in military drivers than commercial drivers (P < 0.001). In addition, 4% of military drivers did not meet the national standards to drive as opposed to 2% of commercial drivers. There was a significant but weak correlation between binocular VA and age (r = 0.175, P < 0.001). However, CS showed a significantly moderate correlation with age (r = -0.488, P < 0.001). The absence of legal requirement for regular eye examination in military drivers caused the incompetent drivers to be missed in contrast to commercial drivers. The need for scientific revision of VA standard for Iranian drivers is also discussed. The CS measurement in visual checkups of older drivers deserves to be investigated more thoroughly.

Reliability and validity of abbreviated surveys derived from the National Eye Institute Visual Function Questionnaire: The Study of Osteoporotic Fractures

PubMed Central

Gergana, Kodjebacheva; Coleman, Anne L.; Ensrud, Kristine E.; Cauley, Jane A.; Yu, Fei; Stone, Katie L.; Pedula, Kathryn L.; Hochberg, Marc C.; Mangione, Carol M.

2010-01-01

Purpose To test the reliability and validity of questionnaires shortened from the National Eye Institute 25-item Vision Function Questionnaire (NEI VFQ-9 and NEI VFQ-8). Design A cross-sectional multi-center cohort study. Methods Reliability was assessed by Cronbach alpha coefficients. Validity was evaluated by studying the association of vision-targeted quality-of-life composite scores with objective visual function measurements. Study population: A total of 5,482 women between the ages of 65 and 100 years participated in the Year-10 clinic visit in the Study of Osteoporotic Fractures (SOF). A total of 3,631 women with complete data were included in the visual acuity (VA) and visual field (VF) analysis of the NEI VFQ-9, which is defined for those who care to drive. and 5,311 in the analysis of the NEI VFQ-8. To assess differences in prevalent eye diseases, which were ascertained for a random sample of SOF participants, 853 and 1,237 women were included in the NEI VFQ-9 and the NEI VFQ-8 analyses, respectively. Results Cronbach alpha coefficient for the NEI VFQ-9 scale was 0.83 and that of the NEI VFQ-8 was 0.84. Using both questionnaires, women with VA worse than 20/40 had lower composite scores compared to those with VA 20/40 or better (p<0.001). Participants with mild, moderate, and severe binocular VF loss had lower composite scores compared to those with no binocular VF loss (p<0.001).Compared to women without chronic eye diseases in both eyes, women with at least one chronic eye disease in at least one eye had lower composite scores. Conclusions Both questionnaires showed high reliability across items and validity with respect to clinical markers of eye disease Future research should compare the properties of these shortened surveys to those of the NEI VFQ-25. PMID:20103058

Perceptual full-reference quality assessment of stereoscopic images by considering binocular visual characteristics.

PubMed

Shao, Feng; Lin, Weisi; Gu, Shanbo; Jiang, Gangyi; Srikanthan, Thambipillai

2013-05-01

Perceptual quality assessment is a challenging issue in 3D signal processing research. It is important to study 3D signal directly instead of studying simple extension of the 2D metrics directly to the 3D case as in some previous studies. In this paper, we propose a new perceptual full-reference quality assessment metric of stereoscopic images by considering the binocular visual characteristics. The major technical contribution of this paper is that the binocular perception and combination properties are considered in quality assessment. To be more specific, we first perform left-right consistency checks and compare matching error between the corresponding pixels in binocular disparity calculation, and classify the stereoscopic images into non-corresponding, binocular fusion, and binocular suppression regions. Also, local phase and local amplitude maps are extracted from the original and distorted stereoscopic images as features in quality assessment. Then, each region is evaluated independently by considering its binocular perception property, and all evaluation results are integrated into an overall score. Besides, a binocular just noticeable difference model is used to reflect the visual sensitivity for the binocular fusion and suppression regions. Experimental results show that compared with the relevant existing metrics, the proposed metric can achieve higher consistency with subjective assessment of stereoscopic images.

Differences in quality-of-life dimensions of Adult Strabismus Quality of Life and Amblyopia & Strabismus Questionnaires.

PubMed

van de Graaf, Elizabeth S; Borsboom, Gerard J J M; van der Sterre, Geertje W; Felius, Joost; Simonsz, Huibert J; Kelderman, Henk

2017-09-01

The Adult Strabismus Quality of Life Questionnaire (AS-20) and the Amblyopia & Strabismus Questionnaire (A&SQ) both measure health-related quality of life in strabismus patients. We evaluated to what extent these instruments cover similar domains by identifying the underlying quality-of-life factors of the combined questionnaires. Participants were adults from a historic cohort with available orthoptic childhood data documenting strabismus and/or amblyopia. They had previously completed the A&SQ and were now asked to complete the AS-20. Factor analysis was performed on the correlation-matrix of the combined AS-20 and A&SQ data to identify common underlying factors. The identified factors were correlated with the clinical variables of angle of strabismus, degree of binocular vision, and visual acuity of the worse eye. One hundred ten patients completed both questionnaires (mean age, 44 years; range, 38-51 years). Six factors were found that together explained 78% of the total variance. The factor structure was dominated by the first four factors. One factor contained psychosocial and social-contact items, and another factor depth-perception items from both questionnaires. A third factor contained seven items-only from the AS-20-on eye strain, stress, and difficulties with reading and with concentrating. A fourth factor contained seven items-only from the A&SQ-on fear of losing the better eye and visual disorientation, specific for amblyopia. Current visual acuity of the worse eye correlated with depth-perception items and vision-related items, whereas current binocular vision correlated with psychosocial and social-contact items, in 93 patients. Factor analysis suggests that the AS-20 and A&SQ measure a similar psychosocial quality-of-life domain. However, functional problems like avoidance of reading, difficulty in concentrating, eye stress, reading problems, inability to enjoy hobbies, and need for frequent breaks when reading are represented only in the AS-20. During the development of the A&SQ, asthenopia items were considered insufficiently specific for strabismus and were excluded a priori. The patients who generated the items for the AS-20 had, in majority, adulthood-onset strabismus and diplopia and were, hence, more likely to develop such complaints than our adult patients with childhood-onset strabismus and/or amblyopia.

Contrast sensitivity of wildtype mice wearing diffusers or spectacle lenses, and the effect of atropine.

PubMed

Schmucker, Christine; Schaeffel, Frank

2006-03-01

To find out how spatial vision in mice is affected by wearing of spectacle lenses or diffusers, and by atropine eye drops. This information is necessary to determine which treatments could effectively induce refractive errors in young mice. Whole-body optomotor responses were recorded by automated video analysis in freely ranging mice in a large rotating drum that was covered inside with vertical square-wave gratings with spatial frequencies of 0.03, 0.10 and 0.30 cyc/deg, both at "dim light" (0.10 cd/m(2)), and under photopic conditions (30 cd/m(2)). Contrast thresholds were determined by varying the contrasts of the gratings. Mice wore either no lenses, or binocular plano lenses, or lenses with powers ranging from +25 D to -25 D, or diffusers. In another experiment, contrast thresholds were determined 30 min after binocular installation of one drop of 1% atropine solution which is known to suppress myopia development in other animal models. The range of spatial frequencies, at which the mice still responded to stripes with less than the maximal grating contrast, was rather small. At 0.03 cyc/deg, the mice responded to stripes with low contrast down to 24%. At 0.10 cyc/deg, the minimal contrast was 45%, but at 0.30 cyc/deg, only the maximum contrast elicited a significant response. In dim light, spatial vision was severely impaired and only the lowest spatial frequencies, presented at the highest contrast (91%), were detected. The whole-body optomotor response was largest with spectacle lens powers of plano diopters and +7D lenses. The magnitude of the response decreased symmetrically with increasing lens powers for both signs, providing information on the behavioral depth of field (a second-order fit through the data placed the extreme limits of a response at around +25 D and -25 D lens powers). Finally, atropine improved contrast sensitivity, at least at the lowest spatial frequency tested, a result that was previously obtained also in the chicken and could help to explain the inhibitory effect of atropine on myopia. The study shows that mice have sufficient spatial vision to respond to treatment with powerful spectacle lenses or diffusers. Accordingly, these devices should be effective in inducing refractive errors in this animal model, although primarily under photopic conditions.

Visual Sensor Based Abnormal Event Detection with Moving Shadow Removal in Home Healthcare Applications

PubMed Central

Lee, Young-Sook; Chung, Wan-Young

2012-01-01

Vision-based abnormal event detection for home healthcare systems can be greatly improved using visual sensor-based techniques able to detect, track and recognize objects in the scene. However, in moving object detection and tracking processes, moving cast shadows can be misclassified as part of objects or moving objects. Shadow removal is an essential step for developing video surveillance systems. The goal of the primary is to design novel computer vision techniques that can extract objects more accurately and discriminate between abnormal and normal activities. To improve the accuracy of object detection and tracking, our proposed shadow removal algorithm is employed. Abnormal event detection based on visual sensor by using shape features variation and 3-D trajectory is presented to overcome the low fall detection rate. The experimental results showed that the success rate of detecting abnormal events was 97% with a false positive rate of 2%. Our proposed algorithm can allow distinguishing diverse fall activities such as forward falls, backward falls, and falling asides from normal activities. PMID:22368486

Functional vision loss: a diagnosis of exclusion.

PubMed

Villegas, Rex B; Ilsen, Pauline F

2007-10-01

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

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

PubMed

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.

Visual function among commercial vehicle drivers in the central region of Ghana

PubMed Central

Boadi-Kusi, Samuel Bert; Kyei, Samuel; Asare, Frederick Afum; Owusu-Ansah, Andrew; Awuah, Agnes; Darko-Takyi, Charles

2015-01-01

Aim To determine the relationship between some visual functions: colour vision defects, abnormal stereopsis, visual acuity and the occurrence of road traffic accident (RTAs) among commercial vehicle drivers in the central region of Ghana, and to assess their knowledge of these anomalies. Method A descriptive cross-sectional study employing a multi-stage random sampling approach was conducted in the major commercial towns within the central region of Ghana. Participants were taken through a comprehensive eye examination after the administration of a structured questionnaire. Results 520 male commercial vehicle drivers were enrolled for this study with a mean age of 39.23 years ±10.96 years and mean visual acuity of 0.02 ± 0.08 logMAR. Protans were more likely to be involved in RTAs (χ2 = 6.194, p = 0.034). However, there was no statistically significant association between abnormal stereopsis (OR = 0.89 95% CI: 0.44–1.80, p = 0.56), poor vision due to refractive error (χ2 = 3.090, p = 0.388) and the occurrence of RTAs. While 86.9% were aware of abnormal stereopsis, only 45% were aware of colour vision defects. There was a statistically significant association between stereopsis anomaly and colour vision defect (r = 0.371, p < 0.005). Conclusion The study found an association between protanopia and RTAs but none between stereopsis anomalies, refractive errors and the occurrence of RTAs. Drivers were less knowledgeable on colour vision defects as compared to stereopsis anomalies. PMID:26364760

Visual function among commercial vehicle drivers in the central region of Ghana.

PubMed

Boadi-Kusi, Samuel Bert; Kyei, Samuel; Asare, Frederick Afum; Owusu-Ansah, Andrew; Awuah, Agnes; Darko-Takyi, Charles

2016-01-01

To determine the relationship between some visual functions: colour vision defects, abnormal stereopsis, visual acuity and the occurrence of road traffic accident (RTAs) among commercial vehicle drivers in the central region of Ghana, and to assess their knowledge of these anomalies. A descriptive cross-sectional study employing a multi-stage random sampling approach was conducted in the major commercial towns within the central region of Ghana. Participants were taken through a comprehensive eye examination after the administration of a structured questionnaire. 520 male commercial vehicle drivers were enrolled for this study with a mean age of 39.23 years ±10.96 years and mean visual acuity of 0.02±0.08 logMAR. Protans were more likely to be involved in RTAs (χ(2)=6.194, p=0.034). However, there was no statistically significant association between abnormal stereopsis (OR=0.89 95% CI: 0.44-1.80, p=0.56), poor vision due to refractive error (χ(2)=3.090, p=0.388) and the occurrence of RTAs. While 86.9% were aware of abnormal stereopsis, only 45% were aware of colour vision defects. There was a statistically significant association between stereopsis anomaly and colour vision defect (r=0.371, p<0.005). The study found an association between protanopia and RTAs but none between stereopsis anomalies, refractive errors and the occurrence of RTAs. Drivers were less knowledgeable on colour vision defects as compared to stereopsis anomalies. Copyright © 2015 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

Design and realization of photoelectric instrument binocular optical axis parallelism calibration system

NASA Astrophysics Data System (ADS)

Ying, Jia-ju; Chen, Yu-dan; Liu, Jie; Wu, Dong-sheng; Lu, Jun

2016-10-01

The maladjustment of photoelectric instrument binocular optical axis parallelism will affect the observe effect directly. A binocular optical axis parallelism digital calibration system is designed. On the basis of the principle of optical axis binocular photoelectric instrument calibration, the scheme of system is designed, and the binocular optical axis parallelism digital calibration system is realized, which include four modules: multiband parallel light tube, optical axis translation, image acquisition system and software system. According to the different characteristics of thermal infrared imager and low-light-level night viewer, different algorithms is used to localize the center of the cross reticle. And the binocular optical axis parallelism calibration is realized for calibrating low-light-level night viewer and thermal infrared imager.

A dataset of stereoscopic images and ground-truth disparity mimicking human fixations in peripersonal space

PubMed Central

Canessa, Andrea; Gibaldi, Agostino; Chessa, Manuela; Fato, Marco; Solari, Fabio; Sabatini, Silvio P.

2017-01-01

Binocular stereopsis is the ability of a visual system, belonging to a live being or a machine, to interpret the different visual information deriving from two eyes/cameras for depth perception. From this perspective, the ground-truth information about three-dimensional visual space, which is hardly available, is an ideal tool both for evaluating human performance and for benchmarking machine vision algorithms. In the present work, we implemented a rendering methodology in which the camera pose mimics realistic eye pose for a fixating observer, thus including convergent eye geometry and cyclotorsion. The virtual environment we developed relies on highly accurate 3D virtual models, and its full controllability allows us to obtain the stereoscopic pairs together with the ground-truth depth and camera pose information. We thus created a stereoscopic dataset: GENUA PESTO—GENoa hUman Active fixation database: PEripersonal space STereoscopic images and grOund truth disparity. The dataset aims to provide a unified framework useful for a number of problems relevant to human and computer vision, from scene exploration and eye movement studies to 3D scene reconstruction. PMID:28350382

Visual function and fitness to drive.

PubMed

Kotecha, Aachal; Spratt, Alexander; Viswanathan, Ananth

2008-01-01

Driving is recognized to be a visually intensive task and accordingly there is a legal minimum standard of vision required for all motorists. The purpose of this paper is to review the current United Kingdom (UK) visual requirements for driving and discuss the evidence base behind these legal rules. The role of newer, alternative tests of visual function that may be better indicators of driving safety will also be considered. Finally, the implications of ageing on driving ability are discussed. A search of Medline and PubMed databases was performed using the following keywords: driving, vision, visual function, fitness to drive and ageing. In addition, papers from the Department of Transport website and UK Royal College of Ophthalmologists guidelines were studied. Current UK visual standards for driving are based upon historical concepts, but recent advances in technology have brought about more sophisticated methods for assessing the status of the binocular visual field and examining visual attention. These tests appear to be better predictors of driving performance. Further work is required to establish whether these newer tests should be incorporated in the current UK visual standards when examining an individual's fitness to drive.

Stereoacuity versus fixation disparity as indicators for vergence accuracy under prismatic stress.

PubMed

Kromeier, Miriam; Schmitt, Christina; Bach, Michael; Kommerell, Guntram

2003-01-01

Fixation disparity has been widely used as an indicator for vergence accuracy under prismatic stress. However, the targets used for measuring fixation disparity contain artificial features in that the fusional contours are thinned out. We considered that stereoacuity might be a preferable indicator of vergence accuracy, as stereo targets represent natural viewing conditions. We measured fixation disparity with a computer adaptation of Ogle's test and stereoacuity with the automatic Freiburg Stereoacuity Test. Eight subjects were examined under increasing base-in and base-out prisms. The response of fixation disparity to prismatic stress revealed the curve types described by Ogle and Crone. All eight subjects reached a stereoscopic threshold below 10 arcsec. In seven subjects the stereoscopic threshold increased before double vision occurred. Our data suggest that stereoacuity is suitable to assess the range of binocular vision under prismatic stress. As stereoacuity bears the advantage over fixation disparity in that it can be measured without introducing artificial viewing conditions, we suggest exploring whether stereoacuity under prismatic stress would be more meaningful in the work-up of asthenopic patients than is fixation disparity.

Home use of binocular dichoptic video content device for treatment of amblyopia: a pilot study.

PubMed

Mezad-Koursh, Daphna; Rosenblatt, Amir; Newman, Hadas; Stolovitch, Chaim

2018-04-01

To evaluate the efficacy of the BinoVision home system as measured by improvement of visual acuity in the patient's amblyopic eye. An open-label prospective pilot-trial of the system was conducted with amblyopic children aged 4-8 years at the pediatric ophthalmology unit, Tel-Aviv Medical Center, January 2014 to October 2015. Participants were assigned to the study or sham group for treatment with BinoVision for 8 or 12 weeks. Patients were instructed to watch animated television shows and videos at home using the BinoVision device for 60 minutes, 6 days a week. The BinoVision program incorporates elements at different contrast and brightness levels for both eyes, weak eye tracking training by superimposed screen images, and weak eye flicker stimuli with alerting sound manipulations. Patients were examined at 4, 8, 12, 24, and 36 weeks. A total of 27 children were recruited (14 boys), with 19 in the treatment group. Median age was 5 years (range, 4-8 years). Mean visual acuity improved by 0.26 logMAR lines in the treatment group from baseline to 12 weeks. Visual acuity was improved compared to baseline during all study and follow-up appointments (P < 0.01), with stabilization of visual acuity after cessation of treatment. The sham group completed 4 weeks of sham protocol with no change in visual acuity (P = 0.285). The average compliance rate was 88% ± 16% (50% to 100%) in treatment group. This pilot trial of 12 weeks of amblyopia treatment with the BinoVision home system demonstrated significant improvement in patients' visual acuity. Copyright © 2018 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.

Helicopter flights with night-vision goggles: Human factors aspects

NASA Technical Reports Server (NTRS)

Brickner, Michael S.

1989-01-01

Night-vision goggles (NVGs) and, in particular, the advanced, helmet-mounted Aviators Night-Vision-Imaging System (ANVIS) allows helicopter pilots to perform low-level flight at night. It consists of light intensifier tubes which amplify low-intensity ambient illumination (star and moon light) and an optical system which together produce a bright image of the scene. However, these NVGs do not turn night into day, and, while they may often provide significant advantages over unaided night flight, they may also result in visual fatigue, high workload, and safety hazards. These problems reflect both system limitations and human-factors issues. A brief description of the technical characteristics of NVGs and of human night-vision capabilities is followed by a description and analysis of specific perceptual problems which occur with the use of NVGs in flight. Some of the issues addressed include: limitations imposed by a restricted field of view; problems related to binocular rivalry; the consequences of inappropriate focusing of the eye; the effects of ambient illumination levels and of various types of terrain on image quality; difficulties in distance and slope estimation; effects of dazzling; and visual fatigue and superimposed symbology. These issues are described and analyzed in terms of their possible consequences on helicopter pilot performance. The additional influence of individual differences among pilots is emphasized. Thermal imaging systems (forward looking infrared (FLIR)) are described briefly and compared to light intensifier systems (NVGs). Many of the phenomena which are described are not readily understood. More research is required to better understand the human-factors problems created by the use of NVGs and other night-vision aids, to enhance system design, and to improve training methods and simulation techniques.

Impact of cataract surgery on vision-related life performances: the usefulness of Real-Life Vision Test for cataract surgery outcomes evaluation

PubMed Central

Ni, W; Li, X; Hou, Z; Zhang, H; Qiu, W; Wang, W

2015-01-01

Purpose Real-Life Vision Test (RLVT) is a newly developed performance-based measures of functional vision. This present study is designed to determine whether it could be a meaningful assessment for cataract surgery outcomes evaluation. Patients and methods Age-related cataract patients (56) who scheduled for bilateral cataract surgery and 44 age-matched controls were evaluated by four types of measurements: (1) demographic, medical, cognitive and depressive evaluation, and the reaction time testing; (2) clinical measures (visual acuity, contrast sensitivity, stereopsis, and color perception); (3) the 25-item National Eye Institute's Visual Functioning Questionnaire (NEI-VFQ); (4) the RLVT. Spearman's coefficients and multiple regression analysis were conducted to investigate the relationship among RLVT, clinical measures, and self-report assessment of visual function. Results The results of RLVT, clinical measures, and NEI-VFQ total scores were improved significantly after cataract surgery. There were no differences between control subjects and post-surgery patients with respect to NEI-VFQ-25 total scores, self-rating depression scale scores and three tasks of RLVT. Change of RLVT was significantly associated with the change of clinical measures in the cataract group. Multiple regression analysis demonstrated that change of distance, intermediate, and near visual acuity, and binocular contrast sensitivity were significant predictors of improvements of RLVT. Conclusions Cataract surgery could improve real-world visual ability effectively for cataract patients. Our study highlights the potential usefulness of RLVT as an adjunct to the current outcomes evaluation system for cataract surgery. The use of RLVT combined with clinical and self-survey methods may be the comprehensive strategy to manifest the impact of cataract surgery on patients' overall vision-related quality of life. PMID:26272444

Long term outcomes of bilateral congenital and developmental cataracts operated in Maharashtra, India. Miraj pediatric cataract study III.

PubMed

Gogate, Parikshit M; Sahasrabudhe, Mohini; Shah, Mitali; Patil, Shailbala; Kulkarni, Anil N; Trivedi, Rupal; Bhasa, Divya; Tamboli, Rahin; Mane, Rekha

2014-02-01

To study long term outcome of bilateral congenital and developmental cataract surgery. 258 pediatric cataract operated eyes of 129 children. Children who underwent pediatric cataract surgery in 2004-8 were traced and examined prospectively in 2010-11. Demographic and clinical factors were noted from retrospective chart readings. All children underwent visual acuity estimation and comprehensive ocular examination in a standardized manner. L. V. Prasad Child Vision Function scores (LVP-CVF) were noted for before and after surgery. Statistical analysis was done with SPSS version 16 including multi-variate analysis. Children aged 9.1 years (std dev 4.6, range 7 weeks-15 years) at the time of surgery. 74/129 (57.4%) were boys. The average duration of follow-up was 4.4 years (stddev 1.6, range 3-8 years). 177 (68.6%) eyes had vision <3/60 before surgery, while 109 (42.2%) had best corrected visual acuity (BCVA) >6/18 and 157 (60.9%) had BCVA >6/60 3-8 years after surgery. 48 (37.2%) had binocular stereoacuity <480 sec of arc by TNO test. Visual outcome depended on type of cataract (P = 0.004), type of cataract surgery (P < 0.001), type of intra-ocular lens (P = 0.05), age at surgery (P = 0.004), absence of post-operative uveitis (P = 0.01) and pre-operative vision (P < 0.001), but did not depend on delay (0.612) between diagnosis and surgery. There was a statistically significant improvement for all the 20 questions of the LVP-CVF scale (P < 0.001). Pediatric cataract surgery improved the children's visual acuity, stereo acuity and vision function. Developmental cataract, use of phacoemulsification, older children and those with better pre-operative vision had betterlong-termoutcomes.

Differences in vision between clinic and home and the effect of lighting in older adults with and without glaucoma

PubMed Central

Bhorade, Anjali M.; Perlmutter, Monica S.; Wilson, Brad; Kambarian, Jamie; Chang, Sidney; Pekmezci, Melike; Gordon, Mae

2015-01-01

Importance Patients often report greater visual difficulties at home than expected from vision testing in the clinic. Such discordance may be due to worse vision in the home than measured in clinic. Objective To compare vision measured between clinic and home and evaluate factors, including lighting, associated with these differences. Design Cross-sectional, between years 2005–2009. Setting Participants recruited from the Glaucoma and Comprehensive Eye Clinics at Washington University, St. Louis, MO underwent a clinic and home visit. Participants 126 glaucoma and 49 non-glaucoma patients, ages 55–90 years, consecutively recruited and met inclusion criteria for this report; 166 eligible patients refused participation. Exposure Participants underwent a clinic and home visit randomized to order of completion. At each visit, masked and certified examiners measured binocular distance visual acuity (DVA) with a non-backlit chart, near visual acuity (NVA), contrast sensitivity (CS), CS with glare, and lighting. Main Outcome Measure Differences in vision between clinic and home. Results Mean scores for all vision tests were significantly better in the clinic than home for glaucoma and non-glaucoma patients (p<0.05, matched pair t-tests). For DVA, 29% of glaucoma participants read ≥2 lines better in clinic than home and 39% with advanced glaucoma read ≥3 lines better. For the entire sample, 21% of participants read ≥2 lines better in clinic than home for NVA and 49% read ≥2 triplets better in clinic for CS with glare. Lighting was the most significant factor associated with differences in vision between clinic and home for DVA, NVA, and CS with glare testing (p<0.05 multiple regression model). Median home lighting was 4.3 times and 2.8 times lower than clinic lighting in areas tested for DVA and NVA, respectively. Home lighting was below that recommended in ≥ 85% of participants. Conclusions and Relevance Vision measured in the clinic is generally better than vision measured at home, with differences mainly due to poor home lighting. Knowledge that vision discrepancies between patient report and clinical testing may be due to home lighting may initiate clinician-patient discussions to increase home lighting and improve vision of older adults in their homes. PMID:24263699

Peripheral prism glasses: effects of moving and stationary backgrounds.

PubMed

Shen, Jieming; Peli, Eli; Bowers, Alex R

2015-04-01

Unilateral peripheral prisms for homonymous hemianopia (HH) expand the visual field through peripheral binocular visual confusion, a stimulus for binocular rivalry that could lead to reduced predominance and partial suppression of the prism image, thereby limiting device functionality. Using natural-scene images and motion videos, we evaluated whether detection was reduced in binocular compared with monocular viewing. Detection rates of nine participants with HH or quadranopia and normal binocularity wearing peripheral prisms were determined for static checkerboard perimetry targets briefly presented in the prism expansion area and the seeing hemifield. Perimetry was conducted under monocular and binocular viewing with targets presented over videos of real-world driving scenes and still frame images derived from those videos. With unilateral prisms, detection rates in the prism expansion area were significantly lower in binocular than in monocular (prism eye) viewing on the motion background (medians, 13 and 58%, respectively, p = 0.008) but not the still frame background (medians, 63 and 68%, p = 0.123). When the stimulus for binocular rivalry was reduced by fitting prisms bilaterally in one HH and one normally sighted subject with simulated HH, prism-area detection rates on the motion background were not significantly different (p > 0.6) in binocular and monocular viewing. Conflicting binocular motion appears to be a stimulus for reduced predominance of the prism image in binocular viewing when using unilateral peripheral prisms. However, the effect was only found for relatively small targets. Further testing is needed to determine the extent to which this phenomenon might affect the functionality of unilateral peripheral prisms in more real-world situations.

Peripheral Prism Glasses: Effects of Moving and Stationary Backgrounds

PubMed Central

Shen, Jieming; Peli, Eli; Bowers, Alex R.

2015-01-01

Purpose Unilateral peripheral prisms for homonymous hemianopia (HH) expand the visual field through peripheral binocular visual confusion, a stimulus for binocular rivalry that could lead to reduced predominance (partial local suppression) of the prism image and limit device functionality. Using natural-scene images and motion videos, we evaluated whether detection was reduced in binocular compared to monocular viewing. Methods Detection rates of nine participants with HH or quadranopia and normal binocularity wearing peripheral prisms were determined for static checkerboard perimetry targets briefly presented in the prism expansion area and the seeing hemifield. Perimetry was conducted under monocular and binocular viewing with targets presented over videos of real-world driving scenes and still frame images derived from those videos. Results With unilateral prisms, detection rates in the prism expansion area were significantly lower in binocular than monocular (prism eye) viewing on the motion background (medians 13% and 58%, respectively, p = 0.008), but not the still frame background (63% and 68%, p = 0.123). When the stimulus for binocular rivalry was reduced by fitting prisms bilaterally in 1 HH and 1 normally-sighted subject with simulated HH, prism-area detection rates on the motion background were not significantly different (p > 0.6) in binocular and monocular viewing. Conclusions Conflicting binocular motion appears to be a stimulus for reduced predominance of the prism image in binocular viewing when using unilateral peripheral prisms. However, the effect was only found for relatively small targets. Further testing is needed to determine the extent to which this phenomenon might affect the functionality of unilateral peripheral prisms in more real-world situations. PMID:25785533

Underwater binocular imaging of aerial objects versus the position of eyes relative to the flat water surface.

PubMed

Barta, András; Horváth, Gábor

2003-12-01

The apparent position, size, and shape of aerial objects viewed binocularly from water change as a result of the refraction of light at the water surface. Earlier studies of the refraction-distorted structure of the aerial binocular visual field of underwater observers were restricted to either vertically or horizontally oriented eyes. Here we calculate the position of the binocular image point of an aerial object point viewed by two arbitrarily positioned underwater eyes when the water surface is flat. Assuming that binocular image fusion is performed by appropriate vergent eye movements to bring the object's image onto the foveae, the structure of the aerial binocular visual field is computed and visualized as a function of the relative positions of the eyes. We also analyze two erroneous representations of the underwater imaging of aerial objects that have occurred in the literature. It is demonstrated that the structure of the aerial binocular visual field of underwater observers distorted by refraction is more complex than has been thought previously.

Measurement of suprathreshold binocular interactions in amblyopia.

PubMed

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

2008-12-01

It has been established that in amblyopia, information from the amblyopic eye (AME) is not combined with that from the fellow fixing eye (FFE) under conditions of binocular viewing. However, recent evidence suggests that mechanisms that combine information between the eyes are intact in amblyopia. The lack of binocular function is most likely due to the imbalanced inputs from the two eyes under binocular conditions [Baker, D. H., Meese, T. S., Mansouri, B., & Hess, R. F. (2007b). Binocular summation of contrast remains intact in strabismic amblyopia. Investigative Ophthalmology & Visual Science, 48(11), 5332-5338]. We have measured the extent to which the information presented to each eye needs to differ for binocular combination to occur and in doing so we quantify the influence of interocular suppression. We quantify these suppressive effects for suprathreshold processing of global stimuli for both motion and spatial tasks. The results confirm the general importance of these suppressive effects in rendering the structurally binocular visual system of a strabismic amblyope, functionally monocular.

The role of binocular viewing in a spacing illusion arising in a darkened surround.

PubMed

Suzuki, K

1998-01-01

A study is reported of the binocular-oculomotor hypothesis of the moon illusion. In a dark hall, a pair of light points was presented straight ahead horizontally, and another pair was presented at the same distance but 50 degrees upward. Twenty subjects compared the spacings of these two pairs. Half of the subjects viewed the stimuli first monocularly and then binocularly, and the other half viewed them in the reverse order. Eye position was also systematically varied, either level or elevated. A spacing illusion was consistently obtained during binocular viewing (with the upper spacing seen as smaller), but no illusion arose during monocular viewing unless it was preceded by binocular viewing. Furthermore, an enhancement of the illusion due to eye elevation was found only during binocular viewing. These findings replicate the report of Taylor and Boring (1942 American Journal of Psychology 55 189-201), in which the moon was used as the stimulus, and support the binocular-oculomotor hypothesis as a partial explanation for the moon illusion.

Aerobic Exercise Effects on Ocular Dominance Plasticity with a Phase Combination Task in Human Adults

PubMed Central

Reynaud, Alexandre; Hess, Robert F.

2017-01-01

Several studies have shown that short-term monocular patching can induce ocular dominance plasticity in normal adults, in which the patched eye becomes stronger in binocular viewing. There is a recent study showing that exercise enhances this plasticity effect when assessed with binocular rivalry. We address one question, is this enhancement from exercise a general effect such that it is seen for measures of binocular processing other than that revealed using binocular rivalry? Using a binocular phase combination task in which we directly measure each eye's contribution to the binocularly fused percept, we show no additional effect of exercise after short-term monocular occlusion and argue that the enhancement of ocular dominance plasticity from exercise could not be demonstrated with our approach. PMID:28357142

The Visual Impact of Gossip

PubMed Central

Anderson, Eric; Siegel, Erika H.; Bliss-Moreau, Eliza; Barrett, Lisa Feldman

2011-01-01

Gossip is a form of affective information about who is friend and who is foe. We show that gossip does not impact only how a face is evaluated—it affects whether a face is seen in the first place. In two experiments, neutral faces were paired with negative, positive, or neutral gossip and were then presented alone in a binocular rivalry paradigm (faces were presented to one eye, houses to the other). In both studies, faces previously paired with negative (but not positive or neutral) gossip dominated longer in visual consciousness. These findings demonstrate that gossip, as a potent form of social affective learning, can influence vision in a completely top-down manner, independent of the basic structural features of a face. PMID:21596956