Effect of Visual Field Presentation on Action Planning (Estimating Reach) in Children

ERIC Educational Resources Information Center

Gabbard, Carl; Cordova, Alberto

2012-01-01

In this article, the authors examined the effects of target information presented in different visual fields (lower, upper, central) on estimates of reach via use of motor imagery in children (5-11 years old) and young adults. Results indicated an advantage for estimating reach movements for targets placed in lower visual field (LoVF), with all…

[Transient elevation of intraocular pressure in primary open-angle glaucoma patients after automated visual field examination in the winter].

PubMed

Nishino, Kazuaki; Yoshida, Fujiko; Nitta, Akari; Saito, Mieko; Saito, Kazuuchi

2013-12-01

To evaluate retrospectively seasonal fluctuations of transient intraocular pressure (IOP) elevation after automated visual field examination in patients with primary open-angle glaucoma (POAG). We reviewed 53 consecutive patients with POAG who visited Kaimeido Ophthalmic and Dental Clinic from January 2011 to March 2013, 21 men and 32 women aged 67.7 +/- 11.2 years. The patients were divided into 4 groups, spring, summer, autumn, and winter according to the month of automated visual field examination and both eyes of each patient were enrolled. IOP was measured immediately after automated visual field examination (vf IOP) and compared with the average IOP from the previous 3 months (pre IOP) and with the average IOP from the following 3 months (post IOP) in each season. IOP elevation rate was defined as (vf IOP- pre IOP)/pre IOP x 100% and calculated for each season (paired t test). Additionally, the correlation between mean deviation (MD) and IOP elevation rate was evaluated (single regression analysis). Exclusion criteria were patients who received cataract surgery during this study or had a history of any previous glaucoma surgery. The automated visual field test was performed with a Humphrey field analyzer and the Central 30-2 FASTPAC threshold program. The average vf IOP was 14.5 +/- 2.5 mmHg, higher than pre IOP 13.8 +/- 2.4 mmHg (p < 0.0001) and the post IOP 13.8 +/- 2.2 mmHg (p < 0.0001). IOP elevation rate in each season was 4.1 11.6% in spring (n = 22, p = 0.18), 0.1 +/- 9.9% in summer (n = 16, p = 1.0), 5.0 +/- 13.8% in autumn (n = 30. p = 0.11), 10.6 +/- 8.8% in winter (n = 38, p < 0.0001). The MD was not correlated with IOP elevation rate (p = 0.17). Patients with POAG show a transient IOP elevation after automated visual field examination, especially in the winter but not in the summer.

Simulated visual field loss does not alter turning coordination in healthy young adults.

PubMed

Murray, Nicholas G; Ponce de Leon, Marlina; Ambati, V N Pradeep; Saucedo, Fabricio; Kennedy, Evan; Reed-Jones, Rebecca J

2014-01-01

Turning, while walking, is an important component of adaptive locomotion. Current hypotheses regarding the motor control of body segment coordination during turning suggest heavy influence of visual information. The authors aimed to examine whether visual field impairment (central loss or peripheral loss) affects body segment coordination during walking turns in healthy young adults. No significant differences in the onset time of segments or intersegment coordination were observed because of visual field occlusion. These results suggest that healthy young adults can use visual information obtained from central and peripheral visual fields interchangeably, pointing to flexibility of visuomotor control in healthy young adults. Further study in populations with chronic visual impairment and those with turning difficulties are warranted.

Useful visual field in patients with schizophrenia: a choice reaction time study.

PubMed

Matsuda, Yukihisa; Matsui, Mie; Tonoya, Yasuhiro; Ebihara, Naokuni; Kurachi, Masayoshi

2011-04-01

This study examined the size of the useful visual field in patients (9 men, 6 women) with schizophrenia. A choice reaction task was conducted, and performances at 2.5, 5, 7, 10, and 25 degrees in both visual fields were measured. Three key findings were shown. First, patients had slower choice reaction times (choice RTs) than normal controls. Second, patients had slower choice RTs in the right visual field than in the left visual field. Third, patients and normal controls showed the same U-shaped choice RT pattern. The first and second findings were consistent with those of other studies. The third finding was a clear indication of the patients' performance in peripheral vision, and a comparison with normal controls suggested that there was no difference in the size of the useful visual field, at least within

Visualizing vector field topology in fluid flows

NASA Technical Reports Server (NTRS)

Helman, James L.; Hesselink, Lambertus

1991-01-01

Methods of automating the analysis and display of vector field topology in general and flow topology in particular are discussed. Two-dimensional vector field topology is reviewed as the basis for the examination of topology in three-dimensional separated flows. The use of tangent surfaces and clipping in visualizing vector field topology in fluid flows is addressed.

Modulation of visualized electrical field

NASA Astrophysics Data System (ADS)

Chuang, Chin-Jung; Wu, Chi-Chung; Wang, Yi-Ting; Huang, Shiuan-Hau

2015-10-01

Polarization is an important concept of electromagnetism, and polarizers were traditionally applied to demonstrate this concept in a laboratory. We set up a optical system with the optical component "axis finder" to visualize the polarization direction immediately. The light phenomena, such as birefringence, circular polarization, and Brewster's angle, can be examined polarization visually. In addition, the principle of different waveplate and optical axis can be presented in a straightforward approach. By means of image analysis, the great precision of polarizing direction can be measured up to 0.01 degree. Modulated polarized light is applied to a few optical devices, like Liquid-crystal display. It is marvelous to trace the light polarization between the backlight module, polarizer, and panel. As seeing is believing, the visualized electrical field allows educators to teach polarization in a smooth and strikingly manifest manner. Without any polarizer and analyzer, we examine the rotary power of different concentration syrup, presenting the relationship with polarization change. We also demonstrate the wide application of polarization light in modern life, and examine the principle through this visualized electrical field system.

Reclaiming the Periphery: Automated Kinetic Perimetry for Measuring Peripheral Visual Fields in Patients With Glaucoma.

PubMed

Mönter, Vera M; Crabb, David P; Artes, Paul H

2017-02-01

Peripheral vision is important for mobility, balance, and guidance of attention, but standard perimetry examines only <20% of the entire visual field. We report on the relation between central and peripheral visual field damage, and on retest variability, with a simple approach for automated kinetic perimetry (AKP) of the peripheral field. Thirty patients with glaucoma (median age 68, range 59-83 years; median Mean Deviation -8.0, range -16.3-0.1 dB) performed AKP and static automated perimetry (SAP) (German Adaptive Threshold Estimation strategy, 24-2 test). Automated kinetic perimetry consisted of a fully automated measurement of a single isopter (III.1.e). Central and peripheral visual fields were measured twice on the same day. Peripheral and central visual fields were only moderately related (Spearman's ρ, 0.51). Approximately 90% of test-retest differences in mean isopter radius were < ±4 deg. Relative to the range of measurements in this sample, the retest variability of AKP was similar to that of SAP. Patients with similar central visual field loss can have strikingly different peripheral visual fields, and therefore measuring the peripheral visual field may add clinically valuable information.

Lexical Decision with Left, Right and Center Visual Field Presentation: A Comparison between Dyslexic and Regular Readers by Means of Electrophysiological and Behavioral Measures

ERIC Educational Resources Information Center

Shaul, Shelley

2012-01-01

This study examined the differences in processing between regular and dyslexic readers in a lexical decision task in different visual field presentations (left, right, and center). The research utilized behavioral measures that provide information on accuracy and reaction time and electro-physiological measures that permit the examination of brain…

Perceptual asymmetries in greyscales: object-based versus space-based influences.

PubMed

Thomas, Nicole A; Elias, Lorin J

2012-05-01

Neurologically normal individuals exhibit leftward spatial biases, resulting from object- and space-based biases; however their relative contributions to the overall bias remain unknown. Relative position within the display has not often been considered, with similar spatial conditions being collapsed across. Study 1 used the greyscales task to investigate the influence of relative position and object- and space-based contributions. One image in each greyscale pair was shifted towards the left or the right. A leftward object-based bias moderated by a bias to the centre was expected. Results confirmed this as a left object-based bias occurred in the right visual field, where the left side of the greyscale pairs was located in the centre visual field. Further, only lower visual field images exhibited a significant left bias in the left visual field. The left bias was also stronger when images were partially overlapping in the right visual field, demonstrating the importance of examining proximity. The second study examined whether object-based biases were stronger when actual objects, with directional lighting biases, were used. Direction of luminosity was congruent or incongruent with spatial location. A stronger object-based bias emerged overall; however a leftward bias was seen in congruent conditions and a rightward bias was seen in incongruent conditions. In conditions with significant biases, the lower visual field image was chosen most often. Results show that object- and space-based biases both contribute; however stimulus type allows either space- or object-based biases to be stronger. A lower visual field bias also interacts with these biases, leading the left bias to be eliminated under certain conditions. The complex interaction occurring between frame of reference and visual field makes spatial location extremely important in determining the strength of the leftward bias. Copyright © 2010 Elsevier Srl. All rights reserved.

Assessment of the vision-specific quality of life using clustered visual field in glaucoma patients.

PubMed

Sawada, Hideko; Yoshino, Takaiko; Fukuchi, Takeo; Abe, Haruki

2014-02-01

To investigate the significance of vision-specific quality of life (QOL) in glaucoma patients based on the location of visual field defects. We examined 336 eyes of 168 patients. The 25-item National Eye Institute Visual Function Questionnaire was used to evaluate patients' QOL. Visual field testing was performed using the Humphrey Field Analyzer; the visual field was divided into 10 clusters. We defined the eye with better mean deviation as the better eye and the fellow eye as the worse eye. A single linear regression analysis was applied to assess the significance of the relationship between QOL and the clustered visual field. The strongest correlation was observed in the lower paracentral visual field in the better eye. The lower peripheral visual field in the better eye also showed a good correlation. Correlation coefficients in the better eye were generally higher than those in the worse eye. For driving, the upper temporal visual field in the better eye was the most strongly correlated (r=0.509). For role limitation and peripheral vision, the lower peripheral visual field in the better eye had the highest correlation coefficients at 0.459 and 0.425, respectively. Overall, clusters in the lower hemifield in the better eye were more strongly correlated with QOL than those in the worse eye. In particular, the lower paracentral visual field in the better eye was correlated most strongly of all. Driving, however, strongly correlated with the upper hemifield in the better eye.

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

Isolated cortical visual loss with subtle brain MRI abnormalities in a case of hypoxic-ischemic encephalopathy.

PubMed

Margolin, Edward; Gujar, Sachin K; Trobe, Jonathan D

2007-12-01

A 16-year-old boy who was briefly asystolic and hypotensive after a motor vehicle accident complained of abnormal vision after recovering consciousness. Visual acuity was normal, but visual fields were severely constricted without clear hemianopic features. The ophthalmic examination was otherwise normal. Brain MRI performed 11 days after the accident showed no pertinent abnormalities. At 6 months after the event, brain MRI demonstrated brain volume loss in the primary visual cortex and no other abnormalities. One year later, visual fields remained severely constricted; neurologic examination, including formal neuropsychometric testing, was normal. This case emphasizes the fact that hypoxic-ischemic encephalopathy (HIE) may cause enduring damage limited to primary visual cortex and that the MRI abnormalities may be subtle. These phenomena should be recognized in the management of patients with HIE.

Representation of the visual field in the striate cortex: comparison of MR findings with visual field deficits in organic mercury poisoning (Minamata disease).

PubMed

Korogi, Y; Takahashi, M; Hirai, T; Ikushima, I; Kitajima, M; Sugahara, T; Shigematsu, Y; Okajima, T; Mukuno, K

1997-01-01

To compare MR imaging findings of the striate cortex with visual field deficits in patients with Minamata disease and to reestimate the classical Holmes retinotopic map by using the data obtained from comparing visual field abnormalities with degree of visual cortex atrophy. MR imaging was performed in eight patients with Minamata disease who had been given a full neuroophthalmic examination, including Goldmann dynamic perimetry. The atrophic portions of the calcarine area were measured in the sagittal plane next to the midsagittal image and represented as a percentage of atrophy of the total length of the calcarine fissure. MR findings were compared with results of a visual field test. The visual field test revealed moderate to severe concentric constriction of the visual fields, with central vision ranging from 7 degrees to 42 degrees (mean, 19 degrees). The ventral portion of the calcarine sulcus was significantly dilated on MR images in all patients. A logarithmic correlation was found between the visual field defect and the extent of dilatation of the calcarine fissure. The central 10 degrees and 30 degrees of vision seemed to fill about 20% and 50% of the total surface area of the calcarine cortex, respectively. Visual field deficits in patients with Minamata disease correlated well with MR findings of the striate cortex. Our data were consistent with the classical Holmes retinotopic map.

View-Dependent Streamline Deformation and Exploration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tong, Xin; Edwards, John; Chen, Chun-Ming

Occlusion presents a major challenge in visualizing 3D flow and tensor fields using streamlines. Displaying too many streamlines creates a dense visualization filled with occluded structures, but displaying too few streams risks losing important features. We propose a new streamline exploration approach by visually manipulating the cluttered streamlines by pulling visible layers apart and revealing the hidden structures underneath. This paper presents a customized view-dependent deformation algorithm and an interactive visualization tool to minimize visual cluttering for visualizing 3D vector and tensor fields. The algorithm is able to maintain the overall integrity of the fields and expose previously hidden structures.more » Our system supports both mouse and direct-touch interactions to manipulate the viewing perspectives and visualize the streamlines in depth. By using a lens metaphor of different shapes to select the transition zone of the targeted area interactively, the users can move their focus and examine the vector or tensor field freely.« less

'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.

Bilateral Glaucomatous Optic Neuropathy Caused by Eye Rubbing.

PubMed

Savastano, Alfonso; Savastano, Maria Cristina; Carlomusto, Laura; Savastano, Silvio

2015-01-01

In this report, we describe a particular condition of a 52-year-old man who showed advanced bilateral glaucomatous-like optic disc damage, even though the intraocular pressure resulted normal during all examinations performed. Visual field test, steady-state pattern electroretinogram, retinal nerve fiber layer and retinal tomographic evaluations were performed to evaluate the optic disc damage. Over a 4-year observational period, his visual acuity decreased to 12/20 in the right eye and counting fingers in the left eye. Visual fields were severely compromised, and intraocular pressure values were not superior to 14 mm Hg during routine examinations. An accurate anamnesis and the suspicion of this disease represent a crucial aspect to establish the correct diagnosis. In fact, our patient strongly rubbed his eyes for more than 10 h per day. Recurrent and continuous eye rubbing can induce progressive optic neuropathy, causing severe visual field damage similar to the pathology of advanced glaucoma.

Unilateral pigmentary retinopathy--a review of literature and case presentation.

PubMed

Stamate, Alina-Cristina; Burcea, Marian; Zemba, Mihail

2016-01-01

To report a rare case of unilateral pigmentary retinopathy and describe the clinical and visual field characteristics of this particular case. We present the case of a 30-year-old male patient with a gradual loss of the visual field on his left eye (LE) for the past 10 years, with further gradual painless loss of his central visual field in the last year, and no similar symptoms in his right eye. His past medical and ocular history were unremarkable. No family history of acquired or inherited diseases was determined. Based on the history, clinical findings, and visual field examination, the diagnosis of unilateral pigmentary retinopathy was established. Visual acuity and visual field in the left eye (LE) were severely affected, while in the right eye (RE), they were completely normal. In this case, distinct features of pigmentary retinopathy were observed only in one eye, with the fellow eye being unaffected. The diagnosis requires a long follow-up period, visual field and electrophysiological testing to rule out a delayed onset of a bilateral form of pigmentary retinopathy.

38 CFR 4.77 - Visual fields.

Code of Federal Regulations, 2011 CFR

2011-07-01

... who are well adapted to intraocular lens implant or contact lens correction, visual field examinations.... For aphakic individuals not well adapted to contact lens correction or pseudophakic individuals not... meridians 221/2 degrees apart for each eye and indicate the Goldmann equivalent used. See Table III for the...

38 CFR 4.77 - Visual fields.

Code of Federal Regulations, 2010 CFR

2010-07-01

... who are well adapted to intraocular lens implant or contact lens correction, visual field examinations.... For aphakic individuals not well adapted to contact lens correction or pseudophakic individuals not... meridians 221/2 degrees apart for each eye and indicate the Goldmann equivalent used. See Table III for the...

The Effects of Spatial Endogenous Pre-cueing across Eccentricities

PubMed Central

Feng, Jing; Spence, Ian

2017-01-01

Frequently, we use expectations about likely locations of a target to guide the allocation of our attention. Despite the importance of this attentional process in everyday tasks, examination of pre-cueing effects on attention, particularly endogenous pre-cueing effects, has been relatively little explored outside an eccentricity of 20°. Given the visual field has functional subdivisions that attentional processes can differ significantly among the foveal, perifoveal, and more peripheral areas, how endogenous pre-cues that carry spatial information of targets influence our allocation of attention across a large visual field (especially in the more peripheral areas) remains unclear. We present two experiments examining how the expectation of the location of the target shapes the distribution of attention across eccentricities in the visual field. We measured participants’ ability to pick out a target among distractors in the visual field after the presentation of a highly valid cue indicating the size of the area in which the target was likely to occur, or the likely direction of the target (left or right side of the display). Our first experiment showed that participants had a higher target detection rate with faster responses, particularly at eccentricities of 20° and 30°. There was also a marginal advantage of pre-cueing effects when trials of the same size cue were blocked compared to when trials were mixed. Experiment 2 demonstrated a higher target detection rate when the target occurred at the cued direction. This pre-cueing effect was greater at larger eccentricities and with a longer cue-target interval. Our findings on the endogenous pre-cueing effects across a large visual area were summarized using a simple model to assist in conceptualizing the modifications of the distribution of attention over the visual field. We discuss our finding in light of cognitive penetration of perception, and highlight the importance of examining attentional process across a large area of the visual field. PMID:28638353

The Effects of Spatial Endogenous Pre-cueing across Eccentricities.

PubMed

Feng, Jing; Spence, Ian

2017-01-01

Frequently, we use expectations about likely locations of a target to guide the allocation of our attention. Despite the importance of this attentional process in everyday tasks, examination of pre-cueing effects on attention, particularly endogenous pre-cueing effects, has been relatively little explored outside an eccentricity of 20°. Given the visual field has functional subdivisions that attentional processes can differ significantly among the foveal, perifoveal, and more peripheral areas, how endogenous pre-cues that carry spatial information of targets influence our allocation of attention across a large visual field (especially in the more peripheral areas) remains unclear. We present two experiments examining how the expectation of the location of the target shapes the distribution of attention across eccentricities in the visual field. We measured participants' ability to pick out a target among distractors in the visual field after the presentation of a highly valid cue indicating the size of the area in which the target was likely to occur, or the likely direction of the target (left or right side of the display). Our first experiment showed that participants had a higher target detection rate with faster responses, particularly at eccentricities of 20° and 30°. There was also a marginal advantage of pre-cueing effects when trials of the same size cue were blocked compared to when trials were mixed. Experiment 2 demonstrated a higher target detection rate when the target occurred at the cued direction. This pre-cueing effect was greater at larger eccentricities and with a longer cue-target interval. Our findings on the endogenous pre-cueing effects across a large visual area were summarized using a simple model to assist in conceptualizing the modifications of the distribution of attention over the visual field. We discuss our finding in light of cognitive penetration of perception, and highlight the importance of examining attentional process across a large area of the visual field.

Aging and feature search: the effect of search area.

PubMed

Burton-Danner, K; Owsley, C; Jackson, G R

2001-01-01

The preattentive system involves the rapid parallel processing of visual information in the visual scene so that attention can be directed to meaningful objects and locations in the environment. This study used the feature search methodology to examine whether there are aging-related deficits in parallel-processing capabilities when older adults are required to visually search a large area of the visual field. Like young subjects, older subjects displayed flat, near-zero slopes for the Reaction Time x Set Size function when searching over a broad area (30 degrees radius) of the visual field, implying parallel processing of the visual display. These same older subjects exhibited impairment in another task, also dependent on parallel processing, performed over the same broad field area; this task, called the useful field of view test, has more complex task demands. Results imply that aging-related breakdowns of parallel processing over a large visual field area are not likely to emerge when required responses are simple, there is only one task to perform, and there is no limitation on visual inspection time.

Further Evidence of Asymmetrical Processing of Tachistoscopic Inputs in Undergraduates across Sex, Handedness, Field-Side, and Fixation Instructions.

ERIC Educational Resources Information Center

Iaccino, James F.

A study examined laterality effects observed in previous studies in which men as well as right-handers show a right-visual field (RVF) advantage for letter recall and a left-visual field (LVF) advantage for letter position recall, suggesting asymmetrical brain organization for these groups. Subjects, 96 undergraduates equally divided by sex and…

MACULAR COLOBOMA IN A CHILD WITH USHER SYNDROME.

PubMed

Ishaq, Mazhar; Mukhtar, Ahsan; Khan, Saim

2015-01-01

Macular coloboma is a rare entity and its concomitance with Usher syndrome is described here. A 14 years male child was studied in detail along with other family members. He underwent two complete ophthalmologic examinations (4-years follow-up), including visual assessment, orthoptic evaluation, colour vision test, visual fields, corneal topography, Optical coherence tomography, fluorescein angiography, and electroretinography. Detailed ophthalmic examination was also conducted on other asymptomatic members of the same family. Patient had sensorineural deafness, poor visual acuity, and progressive visual field impairment in both eyes, bilaterally presenting macular coloboma and atypical retinitis pigmentosa pattern. The other investigated relatives did not show any specific and/or significant ocular disorder. This concurrence represents no genetic pattern and is observed in sporadic cases.

Neural attractor network for application in visual field data classification.

PubMed

Fink, Wolfgang

2004-07-07

The purpose was to introduce a novel method for computer-based classification of visual field data derived from perimetric examination, that may act as a 'counsellor', providing an independent 'second opinion' to the diagnosing physician. The classification system consists of a Hopfield-type neural attractor network that obtains its input data from perimetric examination results. An iterative relaxation process determines the states of the neurons dynamically. Therefore, even 'noisy' perimetric output, e.g., early stages of a disease, may eventually be classified correctly according to the predefined idealized visual field defect (scotoma) patterns, stored as attractors of the network, that are found with diseases of the eye, optic nerve and the central nervous system. Preliminary tests of the classification system on real visual field data derived from perimetric examinations have shown a classification success of over 80%. Some of the main advantages of the Hopfield-attractor-network-based approach over feed-forward type neural networks are: (1) network architecture is defined by the classification problem; (2) no training is required to determine the neural coupling strengths; (3) assignment of an auto-diagnosis confidence level is possible by means of an overlap parameter and the Hamming distance. In conclusion, the novel method for computer-based classification of visual field data, presented here, furnishes a valuable first overview and an independent 'second opinion' in judging perimetric examination results, pointing towards a final diagnosis by a physician. It should not be considered a substitute for the diagnosing physician. Thanks to the worldwide accessibility of the Internet, the classification system offers a promising perspective towards modern computer-assisted diagnosis in both medicine and tele-medicine, for example and in particular, with respect to non-ophthalmic clinics or in communities where perimetric expertise is not readily available.

Effects of refractive errors on visual evoked magnetic fields.

PubMed

Suzuki, Masaya; Nagae, Mizuki; Nagata, Yuko; Kumagai, Naoya; Inui, Koji; Kakigi, Ryusuke

2015-11-09

The latency and amplitude of visual evoked cortical responses are known to be affected by refractive states, suggesting that they may be used as an objective index of refractive errors. In order to establish an easy and reliable method for this purpose, we herein examined the effects of refractive errors on visual evoked magnetic fields (VEFs). Binocular VEFs following the presentation of a simple grating of 0.16 cd/m(2) in the lower visual field were recorded in 12 healthy volunteers and compared among four refractive states: 0D, +1D, +2D, and +4D, by using plus lenses. The low-luminance visual stimulus evoked a main MEG response at approximately 120 ms (M100) that reversed its polarity between the upper and lower visual field stimulations and originated from the occipital midline area. When refractive errors were induced by plus lenses, the latency of M100 increased, while its amplitude decreased with an increase in power of the lens. Differences from the control condition (+0D) were significant for all three lenses examined. The results of dipole analyses showed that evoked fields for the control (+0D) condition were explainable by one dipole in the primary visual cortex (V1), while other sources, presumably in V3 or V6, slightly contributed to shape M100 for the +2D or +4D condition. The present results showed that the latency and amplitude of M100 are both useful indicators for assessing refractive states. The contribution of neural sources other than V1 to M100 was modest under the 0D and +1D conditions. By considering the nature of the activity of M100 including its high sensitivity to a spatial frequency and lower visual field dominance, a simple low-luminance grating stimulus at an optimal spatial frequency in the lower visual field appears appropriate for obtaining data on high S/N ratios and reducing the load on subjects.

Clinical Phenotypes and Prognostic Full-Field Electroretinographic Findings in Stargardt Disease

PubMed Central

ZAHID, SARWAR; JAYASUNDERA, THIRAN; RHOADES, WILLIAM; BRANHAM, KARI; KHAN, NAHEED; NIZIOL, LESLIE M.; MUSCH, DAVID C.; HECKENLIVELY, JOHN R.

2013-01-01

PURPOSE To investigate the relationships between clinical and full-field electroretinographic (ERG) findings and progressive loss of visual function in Stargardt disease. DESIGN Retrospective cohort study. METHODS We performed a retrospective review of data from 198 patients with Stargardt disease. Measures of visual function over time, including visual acuity, quantified Goldmann visual fields, and full-field ERG data were recorded. Data were analyzed using SAS statistical software. Subgroup analyses were performed on 148 patients with ERG phenotypic data, 46 patients with longitudinal visual field data, and 92 patients with identified ABCA4 mutations (46 with 1 mutation, and 47 with 2 or more mutations). RESULTS Of 46 patients with longitudinal visual field data, 8 patients with faster central scotoma progression rates had significantly worse scotopic B-wave amplitudes at their initial assessment than 20 patients with stable scotomata (P = .014) and were more likely to have atrophy beyond the arcades (P = .047). Overall, 47.3% of patients exhibited abnormal ERG results, with rod–cone dysfunction in 14.2% of patients, cone–rod dysfunction in 17.6% of patients, and isolated cone dysfunction in 15.5% of patients. Abnormal values in certain ERG parameters were associated significantly with (maximum-stimulation A- and B-wave amplitudes) or tended toward (photopic and scotopic B-wave amplitudes) a higher mean rate of central scotoma progression compared with those patients with normal ERG values. Scotoma size and ERG parameters differed significantly between those with a single mutation versus those with multiple mutations. CONCLUSIONS Full-field ERG examination provides clinically relevant information regarding the severity of Stargardt disease, likelihood of central scotoma expansion, and visual acuity deterioration. Patients also may exhibit an isolated cone dystrophy on ERG examination. PMID:23219216

Visual field progression in glaucoma: estimating the overall significance of deterioration with permutation analyses of pointwise linear regression (PoPLR).

PubMed

O'Leary, Neil; Chauhan, Balwantray C; Artes, Paul H

2012-10-01

To establish a method for estimating the overall statistical significance of visual field deterioration from an individual patient's data, and to compare its performance to pointwise linear regression. The Truncated Product Method was used to calculate a statistic S that combines evidence of deterioration from individual test locations in the visual field. The overall statistical significance (P value) of visual field deterioration was inferred by comparing S with its permutation distribution, derived from repeated reordering of the visual field series. Permutation of pointwise linear regression (PoPLR) and pointwise linear regression were evaluated in data from patients with glaucoma (944 eyes, median mean deviation -2.9 dB, interquartile range: -6.3, -1.2 dB) followed for more than 4 years (median 10 examinations over 8 years). False-positive rates were estimated from randomly reordered series of this dataset, and hit rates (proportion of eyes with significant deterioration) were estimated from the original series. The false-positive rates of PoPLR were indistinguishable from the corresponding nominal significance levels and were independent of baseline visual field damage and length of follow-up. At P < 0.05, the hit rates of PoPLR were 12, 29, and 42%, at the fifth, eighth, and final examinations, respectively, and at matching specificities they were consistently higher than those of pointwise linear regression. In contrast to population-based progression analyses, PoPLR provides a continuous estimate of statistical significance for visual field deterioration individualized to a particular patient's data. This allows close control over specificity, essential for monitoring patients in clinical practice and in clinical trials.

View-Dependent Streamline Deformation and Exploration

PubMed Central

Tong, Xin; Edwards, John; Chen, Chun-Ming; Shen, Han-Wei; Johnson, Chris R.; Wong, Pak Chung

2016-01-01

Occlusion presents a major challenge in visualizing 3D flow and tensor fields using streamlines. Displaying too many streamlines creates a dense visualization filled with occluded structures, but displaying too few streams risks losing important features. We propose a new streamline exploration approach by visually manipulating the cluttered streamlines by pulling visible layers apart and revealing the hidden structures underneath. This paper presents a customized view-dependent deformation algorithm and an interactive visualization tool to minimize visual clutter in 3D vector and tensor fields. The algorithm is able to maintain the overall integrity of the fields and expose previously hidden structures. Our system supports both mouse and direct-touch interactions to manipulate the viewing perspectives and visualize the streamlines in depth. By using a lens metaphor of different shapes to select the transition zone of the targeted area interactively, the users can move their focus and examine the vector or tensor field freely. PMID:26600061

View-Dependent Streamline Deformation and Exploration.

PubMed

Tong, Xin; Edwards, John; Chen, Chun-Ming; Shen, Han-Wei; Johnson, Chris R; Wong, Pak Chung

2016-07-01

Occlusion presents a major challenge in visualizing 3D flow and tensor fields using streamlines. Displaying too many streamlines creates a dense visualization filled with occluded structures, but displaying too few streams risks losing important features. We propose a new streamline exploration approach by visually manipulating the cluttered streamlines by pulling visible layers apart and revealing the hidden structures underneath. This paper presents a customized view-dependent deformation algorithm and an interactive visualization tool to minimize visual clutter in 3D vector and tensor fields. The algorithm is able to maintain the overall integrity of the fields and expose previously hidden structures. Our system supports both mouse and direct-touch interactions to manipulate the viewing perspectives and visualize the streamlines in depth. By using a lens metaphor of different shapes to select the transition zone of the targeted area interactively, the users can move their focus and examine the vector or tensor field freely.

Purtscher's retinopathy associated with acute pancreatitis.

PubMed

Hamp, Ania M; Chu, Edward; Slagle, William S; Hamp, Robert C; Joy, Jeffrey T; Morris, Robert W

2014-02-01

Purtscher's retinopathy is a rare condition that is associated with complement-activating systemic diseases such as acute pancreatitis. After pancreatic injury or inflammation, proteases such as trypsin activate the complement system and can potentially cause coagulation and leukoembolization of retinal precapillary arterioles. Specifically, intermediate-sized emboli are sufficiently small enough to pass through larger arteries yet large enough to remain lodged in precapillary arterioles and cause the clinical appearance of Purtscher's retinopathy. This pathology may present with optic nerve edema, impaired visual acuity, visual field loss, as well as retinal findings such as cotton-wool spots, retinal hemorrhage, artery attenuation, venous dilation, and Purtscher flecken. A 57-year-old white man presented with an acute onset of visual field scotomas and decreased visual acuity 1 week after being hospitalized for acute pancreatitis. The retinal examination revealed multiple regions of discrete retinal whitening surrounding the disk, extending through the macula bilaterally, as well as bilateral optic nerve hemorrhages. The patient identified paracentral bilateral visual field defects on Amsler Grid testing, which was confirmed with subsequent Humphrey visual field analysis. Although the patient presented with an atypical underlying etiology, he exhibited classic retinal findings for Purtscher's retinopathy. After 2 months, best corrected visual acuity improved and the retinal whitening was nearly resolved; however, bilateral paracentral visual field defects remained. Purtscher's retinopathy has a distinctive clinical presentation and is typically associated with thoracic trauma but may be a sequela of nontraumatic systemic disease such as acute pancreatitis. Patients diagnosed with acute pancreatitis should have an eye examination to rule out Purtscher's retinopathy. Although visual improvement is possible, patients should be educated that there may be permanent ocular sequelae.

Reading performance after vision rehabilitation of subjects with homonymous visual field defects.

PubMed

Gall, Carolin; Sabel, Bernhard A

2012-12-01

To examine whether increased visual functioning after vision-restoration training (VRT) coincides with improved reading abilities. Prospective noncontrolled open-label trial. Controlled laboratory setting for all diagnostic procedures that were conducted before and after 6 months of home-based VRT with telemedicine support. Eleven subjects who had experienced a posterior-parietal stroke and have homonymous visual field defects. Six months of VRT (1 hour daily repeated light stimulation in the partially damaged visual field). VRT outcome measures were the number of detected light stimuli in eye-tracker controlled high-resolution perimetry and the spared visual field within the affected hemifield up to the relative and absolute defect visual field border (square degrees). Enlargements of spared visual field within the affected hemifield were correlated with changes of reading speed after VRT. After VRT, the number of detected light stimuli increased by 5.02 ± 4.31% (mean ± SD; P = .03). The spared visual field up to the relative defect visual field border increased from 18.09 ± 32.35 square degrees before to 137.40 ± 53.32 after VRT (P = .006), as well as for the absolute defect visual field border from 36.95 ± 33.77 square degrees before VRT to 152.02 ± 49.70 after VRT (P = .005). Reading speed increased from 108.95 ± 33.95 words per minute before VRT to 122.26 ± 30.35 after VRT (P = .017), which significantly correlated with increased spared visual field up to the relative defect visual field border (r = 0.73, P = .016). Measures of eye movement variability did not correlate with VRT outcome. VRT improved visual fields in parafoveal areas, which are most relevant for reading. This finding cannot be explained by changes in eye movement behavior. Because of a significant association between improvements of parafoveal vision and reading speed, we propose that patients with homonymous visual field defects who have reading deficits may benefit from visual stimulation by training. Copyright © 2012 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

Attraction of position preference by spatial attention throughout human visual cortex.

PubMed

Klein, Barrie P; Harvey, Ben M; Dumoulin, Serge O

2014-10-01

Voluntary spatial attention concentrates neural resources at the attended location. Here, we examined the effects of spatial attention on spatial position selectivity in humans. We measured population receptive fields (pRFs) using high-field functional MRI (fMRI) (7T) while subjects performed an attention-demanding task at different locations. We show that spatial attention attracts pRF preferred positions across the entire visual field, not just at the attended location. This global change in pRF preferred positions systematically increases up the visual hierarchy. We model these pRF preferred position changes as an interaction between two components: an attention field and a pRF without the influence of attention. This computational model suggests that increasing effects of attention up the hierarchy result primarily from differences in pRF size and that the attention field is similar across the visual hierarchy. A similar attention field suggests that spatial attention transforms different neural response selectivities throughout the visual hierarchy in a similar manner. Copyright © 2014 Elsevier Inc. All rights reserved.

[Possibilities of magnetotherapy in stabilization of visual function in patients with glaucoma].

PubMed

Bisvas Shutanto Kumar; Listopadova, N A

1996-01-01

Courses of magnetotherapy (MT) using ATOS device with 33 mT magnetic field induction were administered to 31 patients (43 eyes) with primary open-angle glaucoma with compensated intraocular pressure. The operation mode was intermittent, with 1.0 to 1.5 Hz field rotation frequency by 6 radii. The procedure is administered to a patient in a sitting posture with magnetic inductor held before the eye. The duration of a session is 10 min, a course consists of 10 sessions. Untreated eyes (n = 15) of the same patients were examined for control. The patients were examined before and 4 to 5 months after MT course. Vision acuity improved by 0.16 diopters, on an average, in 29 eyes (96.7%) out of 30 with vision acuity below 1.0 before treatment. Visocontrastometry was carried out using Visokontrastometer-DT device with spatial frequency range from 0.4 to 19 cycle/degree (12 frequencies) and 125 x 125 monitor. The orientation of lattices was horizontal and vertical. The contrasts ranged from 0.03 to 0.9 (12 levels). MT brought about an improvement of spatial contrast sensitivity by at least 7 values of 12 levels in 22 (84.6%) out of 26 eyes and was unchanged in 4 eyes. Visual field was examined using Humphry automated analyzer. A 120-point threshold test was used. After a course of MT, visual field deficit decreased by at least 10% in 31 (72%) out of 43 eyes, increased in 3, and was unchanged in 9 eyes; on an average, visual field deficit decreased by 22.4% vs. the initial value. After 4 to 5 months the changes in the vision acuity and visual field deficit were negligible. In controls these parameters did not appreciably change over the entire follow-up period.

Optic neuritis

MedlinePlus

... optic neuritis is unknown. The optic nerve carries visual information from your eye to the brain. The nerve can swell when it becomes suddenly ... may include: Color vision testing MRI of the brain , including special images of the optic nerve Visual acuity testing Visual field testing Examination of the ...

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.

[Atypical optic neuritis in systemic lupus erythematosus (SLE)].

PubMed

Eckstein, A; Kötter, I; Wilhelm, H

1995-11-01

A 67-year-old woman experienced acute unilateral visual loss accompanied by pain with eye movements. There was a marked relative afferent pupillary defect and a nerve fiber bundle defect in the upper half of the visual field. Optic discs were normal. After 4 days vision worsened to motion detection and only a temporal island was left in the visual field. The optic disc margin was blurred. Since thirty years she had been suffering from renal insufficiency. Immunoserologic examination revealed elevated ANA and DS-DNA antibody titers. An optic neuritis in systemic lupus erythematosus was diagnosed, which is called atopic, because of its association to a systemic disease and the old age of the patient. The patient was treated with 100 mg prednisolone/day, slowly tapered. Within 6 weeks visual acuity improved to 0.6 and visual field normalized except for a small nerve fiber bundle defect. Autoimmune optic neuritis often responds to treatment with corticosteroids. Early onset of treatment is important. Immunopathologic examinations are an important diagnostic tool in atopic optic neuritis. Their results may even have consequences for the treatment of the underlying disease.

Effects of attention and laterality on motion and orientation discrimination in deaf signers.

PubMed

Bosworth, Rain G; Petrich, Jennifer A F; Dobkins, Karen R

2013-06-01

Previous studies have asked whether visual sensitivity and attentional processing in deaf signers are enhanced or altered as a result of their different sensory experiences during development, i.e., auditory deprivation and exposure to a visual language. In particular, deaf and hearing signers have been shown to exhibit a right visual field/left hemisphere advantage for motion processing, while hearing nonsigners do not. To examine whether this finding extends to other aspects of visual processing, we compared deaf signers and hearing nonsigners on motion, form, and brightness discrimination tasks. Secondly, to examine whether hemispheric lateralities are affected by attention, we employed a dual-task paradigm to measure form and motion thresholds under "full" vs. "poor" attention conditions. Deaf signers, but not hearing nonsigners, exhibited a right visual field advantage for motion processing. This effect was also seen for form processing and not for the brightness task. Moreover, no group differences were observed in attentional effects, and the motion and form visual field asymmetries were not modulated by attention, suggesting they occur at early levels of sensory processing. In sum, the results show that processing of motion and form, believed to be mediated by dorsal and ventral visual pathways, respectively, are left-hemisphere dominant in deaf signers. Published by Elsevier Inc.

Acquired color vision and visual field defects in patients with ocular hypertension and early glaucoma.

PubMed

Papaconstantinou, Dimitris; Georgalas, Ilias; Kalantzis, George; Karmiris, Efthimios; Koutsandrea, Chrysanthi; Diagourtas, Andreas; Ladas, Ioannis; Georgopoulos, Gerasimos

2009-01-01

To study acquired color vision and visual field defects in patients with ocular hypertension (OH) and early glaucoma. In a prospective study we evaluated 99 eyes of 56 patients with OH without visual field defects and no hereditary color deficiencies, followed up for 4 to 6 years (mean = 4.7 +/- 0.6 years). Color vision defects were studied using a special computer program for Farnsworth-Munsell 100 hue test and visual field tests were performed with Humphrey analyzer using program 30-2. Both tests were repeated every six months. In fifty-six eyes, glaucomatous defects were observed during the follow-up period. There was a statistically significant difference in total error score (TES) between eyes that eventually developed glaucoma (157.89 +/- 31.79) and OH eyes (75.51 +/- 31.57) at the first examination (t value 12.816, p < 0.001). At the same time visual field indices were within normal limits in both groups. In the glaucomatous eyes the earliest statistical significant change in TES was identified at the first year of follow-up and was -20.62 +/- 2.75 (t value 9.08, p < 0.001) while in OH eyes was -2.11 +/- 4.36 (t value 1.1, p = 0.276). Pearson's coefficient was high in all examinations and showed a direct correlation between TES and mean deviation and corrected pattern standard deviation in both groups. Quantitative analysis of color vision defects provides the possibility of follow-up and can prove a useful means for detecting early glaucomatous changes in patients with normal visual fields.

3D Visualization of Global Ocean Circulation

NASA Astrophysics Data System (ADS)

Nelson, V. G.; Sharma, R.; Zhang, E.; Schmittner, A.; Jenny, B.

2015-12-01

Advanced 3D visualization techniques are seldom used to explore the dynamic behavior of ocean circulation. Streamlines are an effective method for visualization of flow, and they can be designed to clearly show the dynamic behavior of a fluidic system. We employ vector field editing and extraction software to examine the topology of velocity vector fields generated by a 3D global circulation model coupled to a one-layer atmosphere model simulating preindustrial and last glacial maximum (LGM) conditions. This results in a streamline-based visualization along multiple density isosurfaces on which we visualize points of vertical exchange and the distribution of properties such as temperature and biogeochemical tracers. Previous work involving this model examined the change in the energetics driving overturning circulation and mixing between simulations of LGM and preindustrial conditions. This visualization elucidates the relationship between locations of vertical exchange and mixing, as well as demonstrates the effects of circulation and mixing on the distribution of tracers such as carbon isotopes.

Intraoperative Subcortical Electrical Mapping of the Optic Tract in Awake Surgery Using a Virtual Reality Headset.

PubMed

Mazerand, Edouard; Le Renard, Marc; Hue, Sophie; Lemée, Jean-Michel; Klinger, Evelyne; Menei, Philippe

2017-01-01

Brain mapping during awake craniotomy is a well-known technique to preserve neurological functions, especially the language. It is still challenging to map the optic radiations due to the difficulty to test the visual field intraoperatively. To assess the visual field during awake craniotomy, we developed the Functions' Explorer based on a virtual reality headset (FEX-VRH). The impaired visual field of 10 patients was tested with automated perimetry (the gold standard examination) and the FEX-VRH. The proof-of-concept test was done during the surgery performed on a patient who was blind in his right eye and presenting with a left parietotemporal glioblastoma. The FEX-VRH was used intraoperatively, simultaneously with direct subcortical electrostimulation, allowing identification and preservation of the optic radiations. The FEX-VRH detected 9 of the 10 visual field defects found by automated perimetry. The patient who underwent an awake craniotomy with intraoperative mapping of the optic tract using the FEX-VRH had no permanent postoperative visual field defect. Intraoperative visual field assessment with the FEX-VRH during direct subcortical electrostimulation is a promising approach to mapping the optical radiations and preventing a permanent visual field defect during awake surgery for epilepsy or tumor. Copyright © 2016 Elsevier Inc. All rights reserved.

Effects of Peripheral Visual Field Loss on Eye Movements During Visual Search

PubMed Central

Wiecek, Emily; Pasquale, Louis R.; Fiser, Jozsef; Dakin, Steven; Bex, Peter J.

2012-01-01

Natural vision involves sequential eye movements that bring the fovea to locations selected by peripheral vision. How peripheral visual field loss (PVFL) affects this process is not well understood. We examine how the location and extent of PVFL affects eye movement behavior in a naturalistic visual search task. Ten patients with PVFL and 13 normally sighted subjects with full visual fields (FVF) completed 30 visual searches monocularly. Subjects located a 4° × 4° target, pseudo-randomly selected within a 26° × 11° natural image. Eye positions were recorded at 50 Hz. Search duration, fixation duration, saccade size, and number of saccades per trial were not significantly different between PVFL and FVF groups (p > 0.1). A χ2 test showed that the distributions of saccade directions for PVFL and FVL subjects were significantly different in 8 out of 10 cases (p < 0.01). Humphrey Visual Field pattern deviations for each subject were compared with the spatial distribution of eye movement directions. There were no significant correlations between saccade directional bias and visual field sensitivity across the 10 patients. Visual search performance was not significantly affected by PVFL. An analysis of eye movement directions revealed patients with PVFL show a biased directional distribution that was not directly related to the locus of vision loss, challenging feed-forward models of eye movement control. Consequently, many patients do not optimally compensate for visual field loss during visual search. PMID:23162511

Visual field defects of the contralateral eye of non-arteritic ischemic anterior optic neuropathy: are they related to sleep apnea?

PubMed

Aptel, Florent; Aryal-Charles, Nischal; Tamisier, Renaud; Pépin, Jean-Louis; Lesoin, Antoine; Chiquet, Christophe

2017-06-01

To evaluate whether obstructive sleep apnea (OSA) is responsible for the visual field defects found in the fellow eyes of patients with non-arteritic ischemic optic neuropathy (NAION). Prospective cross-sectional study. The visual fields of the fellow eyes of NAION subjects with OSA were compared to the visual fields of control OSA patients matched for OSA severity. All patients underwent comprehensive ophthalmological and general examination including Humphrey 24.2 SITA-Standard visual field and polysomnography. Visual field defects were classified according the Ischemic Optic Neuropathy Decompression Trial (IONDT) classification. From a cohort of 78 consecutive subjects with NAION, 34 unaffected fellow eyes were compared to 34 control eyes of subjects matched for OSA severity (apnea-hypopnea index [AHI] 35.5 ± 11.6 vs 35.4 ± 9.4 events per hour, respectively, p = 0.63). After adjustment for age and body mass index, all visual field parameters were significantly different between the NAION fellow eyes and those of the control OSA groups, including mean deviation (-4.5 ± 3.7 vs -1.3 ± 1.8 dB, respectively, p < 0.05), visual field index (91.6 ± 10 vs 97.4 ± 3.5%, respectively, p = 0.002), pattern standard deviation (3.7 ± 2.3 vs 2.5 ± 2 dB, respectively, p = 0.015), and number of subjects with at least one defect on the IONDT classification (20 vs 10, respectively, p < 0.05). OSA alone does not explain the visual field defects frequently found in the fellow eyes of NAION patients.

A self-organizing model of perisaccadic visual receptive field dynamics in primate visual and oculomotor system.

PubMed

Mender, Bedeho M W; Stringer, Simon M

2015-01-01

We propose and examine a model for how perisaccadic visual receptive field dynamics, observed in a range of primate brain areas such as LIP, FEF, SC, V3, V3A, V2, and V1, may develop through a biologically plausible process of unsupervised visually guided learning. These dynamics are associated with remapping, which is the phenomenon where receptive fields anticipate the consequences of saccadic eye movements. We find that a neural network model using a local associative synaptic learning rule, when exposed to visual scenes in conjunction with saccades, can account for a range of associated phenomena. In particular, our model demonstrates predictive and pre-saccadic remapping, responsiveness shifts around the time of saccades, and remapping from multiple directions.

A self-organizing model of perisaccadic visual receptive field dynamics in primate visual and oculomotor system

PubMed Central

Mender, Bedeho M. W.; Stringer, Simon M.

2015-01-01

We propose and examine a model for how perisaccadic visual receptive field dynamics, observed in a range of primate brain areas such as LIP, FEF, SC, V3, V3A, V2, and V1, may develop through a biologically plausible process of unsupervised visually guided learning. These dynamics are associated with remapping, which is the phenomenon where receptive fields anticipate the consequences of saccadic eye movements. We find that a neural network model using a local associative synaptic learning rule, when exposed to visual scenes in conjunction with saccades, can account for a range of associated phenomena. In particular, our model demonstrates predictive and pre-saccadic remapping, responsiveness shifts around the time of saccades, and remapping from multiple directions. PMID:25717301

Algorithm Visualization: The State of the Field

ERIC Educational Resources Information Center

Shaffer, Clifford A.; Cooper, Matthew L.; Alon, Alexander Joel D.; Akbar, Monika; Stewart, Michael; Ponce, Sean; Edwards, Stephen H.

2010-01-01

We present findings regarding the state of the field of Algorithm Visualization (AV) based on our analysis of a collection of over 500 AVs. We examine how AVs are distributed among topics, who created them and when, their overall quality, and how they are disseminated. There does exist a cadre of good AVs and active developers. Unfortunately, we…

Visual-Spatial Orienting in Autism.

ERIC Educational Resources Information Center

Wainwright, J. Ann; Bryson, Susan E.

1996-01-01

Visual-spatial orienting in 10 high-functioning adults with autism was examined. Compared to controls, subjects responded faster to central than to lateral stimuli, and showed a left visual field advantage for stimulus detection only when laterally presented. Abnormalities in attention shifting and coordination of attentional and motor systems are…

Perceptions of Visual Literacy. Selected Readings from the Annual Conference of the International Visual Literacy Association (21st, Scottsdale, Arizona, October 1989).

ERIC Educational Resources Information Center

Braden, Roberts A., Ed.; And Others

These proceedings contain 37 papers from 51 authors noted for their expertise in the field of visual literacy. The collection is divided into three sections: (1) "Examining Visual Literacy" (including, in addition to a 7-year International Visual Literacy Association bibliography covering the period from 1983-1989, papers on the perception of…

Organization of area hV5/MT+ in subjects with homonymous visual field defects.

PubMed

Papanikolaou, Amalia; Keliris, Georgios A; Papageorgiou, T Dorina; Schiefer, Ulrich; Logothetis, Nikos K; Smirnakis, Stelios M

2018-04-06

Damage to the primary visual cortex (V1) leads to a visual field loss (scotoma) in the retinotopically corresponding part of the visual field. Nonetheless, a small amount of residual visual sensitivity persists within the blind field. This residual capacity has been linked to activity observed in the middle temporal area complex (V5/MT+). However, it remains unknown whether the organization of hV5/MT+ changes following early visual cortical lesions. We studied the organization of area hV5/MT+ of five patients with dense homonymous defects in a quadrant of the visual field as a result of partial V1+ or optic radiation lesions. To do so, we developed a new method, which models the boundaries of population receptive fields directly from the BOLD signal of each voxel in the visual cortex. We found responses in hV5/MT+ arising inside the scotoma for all patients and identified two possible sources of activation: 1) responses might originate from partially lesioned parts of area V1 corresponding to the scotoma, and 2) responses can also originate independent of area V1 input suggesting the existence of functional V1-bypassing pathways. Apparently, visually driven activity observed in hV5/MT+ is not sufficient to mediate conscious vision. More surprisingly, visually driven activity in corresponding regions of V1 and early extrastriate areas including hV5/MT+ did not guarantee visual perception in the group of patients with post-geniculate lesions that we examined. This suggests that the fine coordination of visual activity patterns across visual areas may be an important determinant of whether visual perception persists following visual cortical lesions. Copyright © 2018 Elsevier Inc. All rights reserved.

The Tölz Temporal Topography Study: mapping the visual field across the life span. Part II: cognitive factors shaping visual field maps.

PubMed

Poggel, Dorothe A; Treutwein, Bernhard; Calmanti, Claudia; Strasburger, Hans

2012-08-01

Part I described the topography of visual performance over the life span. Performance decline was explained only partly by deterioration of the optical apparatus. Part II therefore examines the influence of higher visual and cognitive functions. Visual field maps for 95 healthy observers of static perimetry, double-pulse resolution (DPR), reaction times, and contrast thresholds, were correlated with measures of visual attention (alertness, divided attention, spatial cueing), visual search, and the size of the attention focus. Correlations with the attentional variables were substantial, particularly for variables of temporal processing. DPR thresholds depended on the size of the attention focus. The extraction of cognitive variables from the correlations between topographical variables and participant age substantially reduced those correlations. There is a systematic top-down influence on the aging of visual functions, particularly of temporal variables, that largely explains performance decline and the change of the topography over the life span.

Ethambutol/Linezolid Toxic Optic Neuropathy.

PubMed

Libershteyn, Yevgeniya

2016-02-01

To report a rare toxic optic neuropathy after long-term use of two medications: ethambutol and linezolid. A 65-year-old man presented to the Miami Veterans Affairs Medical Center in December 2014 for evaluation of progressive vision decrease in both eyes. The patient presented with best-corrected visual acuities of 20/400 in the right eye and counting fingers at 5 feet in the left eye. Color vision was significantly reduced in both eyes. Visual fields revealed a cecocentral defect in both eyes. His fundus and optic nerve examination was unremarkable. Because vision continued to decline after discontinuation of ethambutol, linezolid was also discontinued, after which vision, color vision, and visual fields improved. Because of these findings, the final diagnosis was toxic optic neuropathy. Final visual outcome was 20/30 in the right eye and 20/40 in the left eye. Drug-associated toxic optic neuropathy is a rare but vision-threatening condition. Diagnosis is made based on an extensive case history and careful clinical examination. The examination findings include varying decrease in vision, normal pupils and extraocular muscles, and unremarkable fundoscopy, with the possibility of swollen optic discs in the acute stage of the optic neuropathy. Other important findings descriptive of toxic optic neuropathy include decreased color vision and cecocentral visual field defects. This case illustrates the importance of knowledge of all medications and/or substances a patient consumes that may cause a toxic reaction and discontinuing them immediately if the visual functions are worsening or not improving.

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

PubMed Central

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

2017-01-01

Background Good vision is essential for safe driving and studies have associated visual impairment with an increased crash risk. Currently, there is little information about the medical review of drivers with visual field loss. This study examines the prevalence of visual field loss among drivers referred for medical review in one Australian jurisdiction and investigates factors associated with licence outcome in this group. Methods A random sample of 10,000 (31.25 per cent) medical review cases was extracted for analysis from the Victorian licensing authority. Files were screened for the presence of six visual field-related medical conditions. Data were captured on a range of variables, including referral source, age, gender, health status, crash history and licence outcome. Prevalence analyses were univariate and descriptive. Logistic regression was used to assess factors associated with licence outcomes in the visual field loss group. Results Approximately 1.9 per cent of the 10,000 medical review cases screened had a visual field loss condition identified (n=194). Among the visual field loss group, 57.2 per cent were permitted to continue driving (conditional/unconditional licence). Primary referral sources were the police, self-referrals and general medical practitioners. Key factors associated with licence test outcomes were visual field condition, age group, crash involvement and referral to the Driver Licensing Authority’s Medical Advisors. Those who were younger had a crash involvement triggering referral and those who were referred to the Medical Advisors were more likely to have a positive licensing outcome. Conclusion The evidence base for making licensing decisions is complicated by the variable causes, patterns, progressions and measuring technologies for visual field loss. This study highlighted that the involvement of an expert medical advisory service in Victoria resulted in an increased likelihood that drivers with visual field loss will be allowed to continue driving. Further research is warranted to explore issues relating to severity of field loss and the capacity for compensation. PMID:27530283

Visual Receptive Field Heterogeneity and Functional Connectivity of Adjacent Neurons in Primate Frontoparietal Association Cortices.

PubMed

Viswanathan, Pooja; Nieder, Andreas

2017-09-13

The basic organization principles of the primary visual cortex (V1) are commonly assumed to also hold in the association cortex such that neurons within a cortical column share functional connectivity patterns and represent the same region of the visual field. We mapped the visual receptive fields (RFs) of neurons recorded at the same electrode in the ventral intraparietal area (VIP) and the lateral prefrontal cortex (PFC) of rhesus monkeys. We report that the spatial characteristics of visual RFs between adjacent neurons differed considerably, with increasing heterogeneity from VIP to PFC. In addition to RF incongruences, we found differential functional connectivity between putative inhibitory interneurons and pyramidal cells in PFC and VIP. These findings suggest that local RF topography vanishes with hierarchical distance from visual cortical input and argue for increasingly modified functional microcircuits in noncanonical association cortices that contrast V1. SIGNIFICANCE STATEMENT Our visual field is thought to be represented faithfully by the early visual brain areas; all the information from a certain region of the visual field is conveyed to neurons situated close together within a functionally defined cortical column. We examined this principle in the association areas, PFC, and ventral intraparietal area of rhesus monkeys and found that adjacent neurons represent markedly different areas of the visual field. This is the first demonstration of such noncanonical organization of these brain areas. Copyright © 2017 the authors 0270-6474/17/378919-10$15.00/0.

Mapping the Visual Communication Field.

ERIC Educational Resources Information Center

Moriarty, Sandra E.

This paper discusses visual communication theory. After an examination of the literature, this study built a more extensive bibliography of visual communication in general--theory, research, teaching--as well as a taxonomy that was better grounded. A 95-page bibliography was developed for works from a number of scholarly journals dealing with…

Collision avoidance in persons with homonymous visual field defects under virtual reality conditions.

PubMed

Papageorgiou, Eleni; Hardiess, Gregor; Ackermann, Hermann; Wiethoelter, Horst; Dietz, Klaus; Mallot, Hanspeter A; Schiefer, Ulrich

2012-01-01

The aim of the present study was to examine the effect of homonymous visual field defects (HVFDs) on collision avoidance of dynamic obstacles at an intersection under virtual reality (VR) conditions. Overall performance was quantitatively assessed as the number of collisions at a virtual intersection at two difficulty levels. HVFDs were assessed by binocular semi-automated kinetic perimetry within the 90° visual field, stimulus III4e and the area of sparing within the affected hemifield (A-SPAR in deg(2)) was calculated. The effect of A-SPAR, age, gender, side of brain lesion, time since brain lesion and presence of macular sparing on the number of collisions, as well as performance over time were investigated. Thirty patients (10 female, 20 male, age range: 19-71 years) with HVFDs due to unilateral vascular brain lesions and 30 group-age-matched subjects with normal visual fields were examined. The mean number of collisions was higher for patients and in the more difficult level they experienced more collisions with vehicles approaching from the blind side than the seeing side. Lower A-SPAR and increasing age were associated with decreasing performance. However, in agreement with previous studies, wide variability in performance among patients with identical visual field defects was observed and performance of some patients was similar to that of normal subjects. Both patients and healthy subjects displayed equal improvement of performance over time in the more difficult level. In conclusion, our results suggest that visual-field related parameters per se are inadequate in predicting successful collision avoidance. Individualized approaches which also consider compensatory strategies by means of eye and head movements should be introduced. Copyright © 2011 Elsevier Ltd. All rights reserved.

Acquired color vision and visual field defects in patients with ocular hypertension and early glaucoma

PubMed Central

Papaconstantinou, Dimitris; Georgalas, Ilias; Kalantzis, George; Karmiris, Efthimios; Koutsandrea, Chrysanthi; Diagourtas, Andreas; Ladas, Ioannis; Georgopoulos, Gerasimos

2009-01-01

Purpose: To study acquired color vision and visual field defects in patients with ocular hypertension (OH) and early glaucoma. Methods: In a prospective study we evaluated 99 eyes of 56 patients with OH without visual field defects and no hereditary color deficiencies, followed up for 4 to 6 years (mean = 4.7 ± 0.6 years). Color vision defects were studied using a special computer program for Farnsworth–Munsell 100 hue test and visual field tests were performed with Humphrey analyzer using program 30–2. Both tests were repeated every six months. Results: In fifty-six eyes, glaucomatous defects were observed during the follow-up period. There was a statistically significant difference in total error score (TES) between eyes that eventually developed glaucoma (157.89 ± 31.79) and OH eyes (75.51 ± 31.57) at the first examination (t value 12.816, p < 0.001). At the same time visual field indices were within normal limits in both groups. In the glaucomatous eyes the earliest statistical significant change in TES was identified at the first year of follow-up and was −20.62 ± 2.75 (t value 9.08, p < 0.001) while in OH eyes was −2.11 ± 4.36 (t value 1.1, p = 0.276). Pearson’s coefficient was high in all examinations and showed a direct correlation between TES and mean deviation and corrected pattern standard deviation in both groups. Conclusion: Quantitative analysis of color vision defects provides the possibility of follow-up and can prove a useful means for detecting early glaucomatous changes in patients with normal visual fields. PMID:19668575

Solar retinopathy. A study from Nepal and from Germany.

PubMed

Rai, N; Thuladar, L; Brandt, F; Arden, G B; Berninger, T A

1998-01-01

319 patients with a solar retinopathy were seen in an eye clinic in Nepal within 20 months. All patients had either a positive history of sun-gazing or typical circumscribed scars in the foveal area. In more than 80% of the patients the visual acuity was 6/12 or better and did not deteriorate over time. 126 (40%) patients had a history of gazing at the sun during an eclipse, 33 (10%) were sun worshipers and 4 (1%) were in both categories. Three years later 29 patients were re-examined in a follow-up study. Only 16 had had visual disturbances directly after they had gazed into the sun. No colour vision defects were seen in any of the 44 affected eyes, when tested with Panel D 15, while four patients (6 eyes) had some uncertainty with the tritan plates of the Ishihara test charts. Metamorphopsia were recorded in 11 eyes. Five German patients with solar retinopathy were examined in more detail. Colour contrast sensitivity (CCS) was tested for the central and the peripheral visual field. CCS for tritan axis was raised in all patients for the central visual field, while it was normal for the peripheral visual field.

Exploring the Relationship Between Students' Visual Spatial Abilities and Comprehension in STEM Fields

NASA Astrophysics Data System (ADS)

Cid, Ximena; Lopez, Ramon

2011-10-01

It is well known that student have difficulties with concepts in physics and space science as well as other STEM fields. Some of these difficulties may be rooted in student conceptual errors, whereas other difficulties may arise from issues with visual cognition and spatial intelligence. It has also been suggested that some aspects of high attrition rates from STEM fields can be attributed to students' visual spatial abilities. We will be presenting data collected from introductory courses in the College of Engineering, Department of Physics, Department of Chemistry, and the Department of Mathematics at the University of Texas at Arlington. These data examine the relationship between students' visual spatial abilities and comprehension in the subject matter. Where correlations are found to exist, visual spatial interventions can be implemented to reduce the attrition rates.

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

NASA Astrophysics Data System (ADS)

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

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

Visual word form familiarity and attention in lateral difference during processing Japanese Kana words.

PubMed

Nakagawa, A; Sukigara, M

2000-09-01

The purpose of this study was to examine the relationship between familiarity and laterality in reading Japanese Kana words. In two divided-visual-field experiments, three- or four-character Hiragana or Katakana words were presented in both familiar and unfamiliar scripts, to which subjects performed lexical decisions. Experiment 1, using three stimulus durations (40, 100, 160 ms), suggested that only in the unfamiliar script condition was increased stimulus presentation time differently affected in each visual field. To examine this lateral difference during the processing of unfamiliar scripts as related to attentional laterality, a concurrent auditory shadowing task was added in Experiment 2. The results suggested that processing words in an unfamiliar script requires attention, which could be left-hemisphere lateralized, while orthographically familiar kana words can be processed automatically on the basis of their word-level orthographic representations or visual word form. Copyright 2000 Academic Press.

Expanding Understanding of Emergent Literacy: Empirical Support for a New Framework

ERIC Educational Resources Information Center

Erickson, Karen A.; Hatton, Deborah

2007-01-01

Emergent literacy in young children with visual impairments is examined using a conceptual framework proposed by Senechal, LeFevre, Smith-Chant, and Colton (2001). The utility of this framework for young children with visual impairments is illustrated using data from a field study of preschool classes for children with visual impairments.…

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

PubMed

Rhee, Taek Kwan; Han, Jung Il

2014-02-01

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

Effects of visual familiarity for words on interhemispheric cooperation for lexical processing.

PubMed

Yoshizaki, K

2001-12-01

The purpose of this study was to examine the effects of visual familiarity of words on interhemispheric lexical processing. Words and pseudowords were tachistoscopically presented in a left, a right, or bilateral visual fields. Two types of words, Katakana-familiar-type and Hiragana-familiar-type, were used as the word stimuli. The former refers to the words which are more frequently written with Katakana script, and the latter refers to the words which are written predominantly in Hiragana script. Two conditions for the words were set up in terms of visual familiarity for a word. In visually familiar condition, words were presented in familiar script form and in visually unfamiliar condition, words were presented in less familiar script form. The 32 right-handed Japanese students were asked to make a lexical decision. Results showed that a bilateral gain, which indicated that the performance in the bilateral visual fields was superior to that in the unilateral visual field, was obtained only in the visually familiar condition, not in the visually unfamiliar condition. These results suggested that the visual familiarity for a word had an influence on the interhemispheric lexical processing.

Central corneal thickness and progression of the visual field and optic disc in glaucoma

PubMed Central

Chauhan, B C; Hutchison, D M; LeBlanc, R P; Artes, P H; Nicolela, M T

2005-01-01

Aims: To determine whether central corneal thickness (CCT) is a significant predictor of visual field and optic disc progression in open angle glaucoma. Methods: Data were obtained from a prospective study of glaucoma patients tested with static automated perimetry and confocal scanning laser tomography every 6 months. Progression was determined using a trend based approach called evidence of change (EOC) analysis in which sectoral ordinal scores based on the significance of regression coefficients of visual field pattern deviation and neuroretinal rim area over time are summed. Visual field progression was also determined using the event based glaucoma change probability (GCP) analysis using both total and pattern deviation. Results: The sample contained 101 eyes of 54 patients (mean (SD) age 56.5 (9.8) years) with a mean follow up of 9.2 (0.7) years and 20.7 (2.3) sets of examinations every 6 months. Lower CCT was associated with worse baseline visual fields and lower mean IOP in the follow up. In the longitudinal analysis CCT was not correlated with the EOC scores for visual field or optic disc change. In the GCP analyses, there was a tendency for groups classified as progressing to have lower CCT compared to non-progressing groups. In a multivariate analyses accounting for IOP, the opposite was found, whereby higher CCT was associated with visual field progression. None of the independent factors were predictive of optic disc progression. Conclusions: In this cohort of patients with established glaucoma, CCT was not a useful index in the risk assessment of visual field and optic disc progression. PMID:16024855

Visual field progression in glaucoma: total versus pattern deviation analyses.

PubMed

Artes, Paul H; Nicolela, Marcelo T; LeBlanc, Raymond P; Chauhan, Balwantray C

2005-12-01

To compare visual field progression with total and pattern deviation analyses in a prospective longitudinal study of patients with glaucoma and healthy control subjects. A group of 101 patients with glaucoma (168 eyes) with early to moderately advanced visual field loss at baseline (average mean deviation [MD], -3.9 dB) and no clinical evidence of media opacity were selected from a prospective longitudinal study on visual field progression in glaucoma. Patients were examined with static automated perimetry at 6-month intervals for a median follow-up of 9 years. At each test location, change was established with event and trend analyses of total and pattern deviation. The event analyses compared each follow-up test to a baseline obtained from averaging the first two tests, and visual field progression was defined as deterioration beyond the 5th percentile of test-retest variability at three test locations, observed on three consecutive tests. The trend analyses were based on point-wise linear regression, and visual field progression was defined as statistically significant deterioration (P < 5%) worse than -1 dB/year at three locations, confirmed by independently omitting the last and the penultimate observation. The incidence and the time-to-progression were compared between total and pattern deviation analyses. To estimate the specificity of the progression analyses, identical criteria were applied to visual fields obtained in 102 healthy control subjects, and the rate of visual field improvement was established in the patients with glaucoma and the healthy control subjects. With both event and trend methods, pattern deviation analyses classified approximately 15% fewer eyes as having progressed than did the total deviation analyses. In eyes classified as progressing by both the total and pattern deviation methods, total deviation analyses tended to detect progression earlier than the pattern deviation analyses. A comparison of the changes observed in MD and the visual fields' general height (estimated by the 85th percentile of the total deviation values) confirmed that change in the glaucomatous eyes almost always comprised a diffuse component. Pattern deviation analyses of progression may therefore underestimate the true amount of glaucomatous visual field progression. Pattern deviation analyses of visual field progression may underestimate visual field progression in glaucoma, particularly when there is no clinical evidence of increasing media opacity. Clinicians should have access to both total and pattern deviation analyses to make informed decisions on visual field progression in glaucoma.

Early detection of glaucoma by means of a novel 3D computer‐automated visual field test

PubMed Central

Nazemi, Paul P; Fink, Wolfgang; Sadun, Alfredo A; Francis, Brian; Minckler, Donald

2007-01-01

Purpose A recently devised 3D computer‐automated threshold Amsler grid test was used to identify early and distinctive defects in people with suspected glaucoma. Further, the location, shape and depth of these field defects were characterised. Finally, the visual fields were compared with those obtained by standard automated perimetry. Patients and methods Glaucoma suspects were defined as those having elevated intraocular pressure (>21 mm Hg) or cup‐to‐disc ratio of >0.5. 33 patients and 66 eyes with risk factors for glaucoma were examined. 15 patients and 23 eyes with no risk factors were tested as controls. The recently developed 3D computer‐automated threshold Amsler grid test was used. The test exhibits a grid on a computer screen at a preselected greyscale and angular resolution, and allows patients to trace those areas on the grid that are missing in their visual field using a touch screen. The 5‐minute test required that the patients repeatedly outline scotomas on a touch screen with varied displays of contrast while maintaining their gaze on a central fixation marker. A 3D depiction of the visual field defects was then obtained that was further characterised by the location, shape and depth of the scotomas. The exam was repeated three times per eye. The results were compared to Humphrey visual field tests (ie, achromatic standard or SITA standard 30‐2 or 24‐2). Results In this pilot study 79% of the eyes tested in the glaucoma‐suspect group repeatedly demonstrated visual field loss with the 3D perimetry. The 3D depictions of visual field loss associated with these risk factors were all characteristic of or compatible with glaucoma. 71% of the eyes demonstrated arcuate defects or a nasal step. Constricted visual fields were shown in 29% of the eyes. No visual field changes were detected in the control group. Conclusions The 3D computer‐automated threshold Amsler grid test may demonstrate visual field abnormalities characteristic of glaucoma in glaucoma suspects with normal achromatic Humphrey visual field testing. This test may be used as a screening tool for the early detection of glaucoma. PMID:17504855

Electrophysiological evidence for the left-lateralized effect of language on preattentive categorical perception of color

PubMed Central

Mo, Lei; Xu, Guiping; Kay, Paul; Tan, Li-Hai

2011-01-01

Previous studies have shown that the effect of language on categorical perception of color is stronger when stimuli are presented in the right visual field than in the left. To examine whether this lateralized effect occurs preattentively at an early stage of processing, we monitored the visual mismatch negativity, which is a component of the event-related potential of the brain to an unfamiliar stimulus among a temporally presented series of stimuli. In the oddball paradigm we used, the deviant stimuli were unrelated to the explicit task. A significant interaction between color-pair type (within-category vs. between-category) and visual field (left vs. right) was found. The amplitude of the visual mismatch negativity component evoked by the within-category deviant was significantly smaller than that evoked by the between-category deviant when displayed in the right visual field, but no such difference was observed for the left visual field. This result constitutes electroencephalographic evidence that the lateralized Whorf effect per se occurs out of awareness and at an early stage of processing. PMID:21844340

A Competition Model of Exogenous Orienting in 3.5-Month-Old Infants.

ERIC Educational Resources Information Center

Dannemiller, James L.

1998-01-01

Four experiments examined exogenous orienting in 3.5-month-olds. Found that sensitivity to a small moving bar was lower when most of the red bars were in the visual field contra-lateral to this probe. The distribution of color within the visual field biased attention, making it either more or less likely that the infant detected a moving stimulus.…

Inhibition of Return in the Visual Field

PubMed Central

Bao, Yan; Lei, Quan; Fang, Yuan; Tong, Yu; Schill, Kerstin; Pöppel, Ernst; Strasburger, Hans

2013-01-01

Inhibition of return (IOR) as an indicator of attentional control is characterized by an eccentricity effect, that is, the more peripheral visual field shows a stronger IOR magnitude relative to the perifoveal visual field. However, it could be argued that this eccentricity effect may not be an attention effect, but due to cortical magnification. To test this possibility, we examined this eccentricity effect in two conditions: the same-size condition in which identical stimuli were used at different eccentricities, and the size-scaling condition in which stimuli were scaled according to the cortical magnification factor (M-scaling), thus stimuli being larger at the more peripheral locations. The results showed that the magnitude of IOR was significantly stronger in the peripheral relative to the perifoveal visual field, and this eccentricity effect was independent of the manipulation of stimulus size (same-size or size-scaling). These results suggest a robust eccentricity effect of IOR which cannot be eliminated by M-scaling. Underlying neural mechanisms of the eccentricity effect of IOR are discussed with respect to both cortical and subcortical structures mediating attentional control in the perifoveal and peripheral visual field. PMID:23820946

Correlation between Macular Thickness and Visual Field in Early Open Angle Glaucoma: A Cross-Sectional Study.

PubMed

Fallahi Motlagh, Behzad; Sadeghi, Ali

2017-01-01

The aim of this study was to correlate macular thickness and visual field parameters in early glaucoma. A total of 104 eyes affected with early glaucoma were examined in a cross-sectional, prospective study. Visual field testing using both standard automated perimetry (SAP) and shortwave automated perimetry (SWAP) was performed. Global visual field parameters, including mean deviation (MD) and pattern standard deviation (PSD), were recorded and correlated with spectral domain optical coherence tomography (SD-OCT)-measured macular thickness and asymmetry. Average macular thickness correlated significantly with all measures of visual field including MD-SWAP (r = 0.42), MD-SAP (r = 0.41), PSD-SWAP (r = -0.23), and PSD-SAP (r = -0.21), with P-values <0.001 for all correlations. The mean MD scores (using both SWAP and SAP) were significantly higher in the eyes with thin than in those with intermediate average macular thickness. Intraeye (superior macula thickness - inferior macula thickness) asymmetries correlated significantly with both PSD-SWAP (r = 0.63, P < 0.001) and PSD-SAP (r = 0.26, P = 0.01) scores. This study revealed a significant correlation between macular thickness and visual field parameters in early glaucoma. The results of this study should make macular thickness measurements even more meaningful to glaucoma specialists.

Role of inter-hemispheric transfer in generating visual evoked potentials in V1-damaged brain hemispheres

PubMed Central

Kavcic, Voyko; Triplett, Regina L.; Das, Anasuya; Martin, Tim; Huxlin, Krystel R.

2015-01-01

Partial cortical blindness is a visual deficit caused by unilateral damage to the primary visual cortex, a condition previously considered beyond hopes of rehabilitation. However, recent data demonstrate that patients may recover both simple and global motion discrimination following intensive training in their blind field. The present experiments characterized motion-induced neural activity of cortically blind (CB) subjects prior to the onset of visual rehabilitation. This was done to provide information about visual processing capabilities available to mediate training-induced visual improvements. Visual Evoked Potentials (VEPs) were recorded from two experimental groups consisting of 9 CB subjects and 9 age-matched, visually-intact controls. VEPs were collected following lateralized stimulus presentation to each of the 4 visual field quadrants. VEP waveforms were examined for both stimulus-onset (SO) and motion-onset (MO) related components in postero-lateral electrodes. While stimulus presentation to intact regions of the visual field elicited normal SO-P1, SO-N1, SO-P2 and MO-N2 amplitudes and latencies in contralateral brain regions of CB subjects, these components were not observed contralateral to stimulus presentation in blind quadrants of the visual field. In damaged brain hemispheres, SO-VEPs were only recorded following stimulus presentation to intact visual field quadrants, via inter-hemispheric transfer. MO-VEPs were only recorded from damaged left brain hemispheres, possibly reflecting a native left/right asymmetry in inter-hemispheric connections. The present findings suggest that damaged brain hemispheres contain areas capable of responding to visual stimulation. However, in the absence of training or rehabilitation, these areas only generate detectable VEPs in response to stimulation of the intact hemifield of vision. PMID:25575450

Is current eye-care-policy focus almost exclusively on cataract adequate to deal with blindness in India?

PubMed

Dandona, L; Dandona, R; Naduvilath, T J; McCarty, C A; Nanda, A; Srinivas, M; Mandal, P; Rao, G N

1998-05-02

India's National Programme for Control of Blindness focuses almost exclusively on cataract, based on a national survey done in the 1980s which reported that cataract caused 80% of the blindness in India. No current population-based data on the causes of blindness in India are available. We assessed the rate and causes of blindness in an urban population in southern India. We selected 2954 participants by stratified, random, cluster, systematic sampling from Hyderabad city. Eligible participants were interviewed and given a detailed ocular assessment, including visual acuity, refraction, slitlamp biomicroscopy, applanation intraocular pressure, gonioscopy, dilatation, grading of cataract, stereoscopic fundus assessment, and automated-threshold visual fields. 2522 participants, including 1399 aged 30 years or more, were assessed. 49 participants (all aged > or =30 years) were blind (presenting distance visual acuity <6/60 or central visual field <200 in the better eye). The rate of blindness among those aged 30 years or more, adjusted for age and sex, was 3.08% ([95% CI 1.95-4.21]). Causes included cataract (29.7%), retinal disease (17.1%), corneal disease (15.4%), refractive error (12.5%), glaucoma (12.1%), and optic atrophy (11.0%). 15.7% of the blindness caused by visual-field constriction would have been missed without visual-field examination. Also without visual-field and detailed dilated-fundus assessments, blindness attributed to cataract would have been overestimated by up to 75.8%. If the use of cataract surgery in this urban population was half that found in this study, which simulates the situation in rural India, cataract would have caused 51.8% (39.4-64.2) of blindness, significantly less than the 80% accepted by current policy. Much of the blindness in this Indian population was due to non-cataract causes. The previous national survey did not include detailed dilated-fundus assessment and visual-field examination which could have led to overestimation of cataract as a cause of blindness in India. Policy-makers in India should encourage well-designed population-based epidemiological studies from which to develop a comprehensive long-term policy on blindness in addition to dealing with cataract.

Neuro-ophthalmologic evaluation, quality of life, and functional disability in patients with MS.

PubMed

Garcia-Martin, Elena; Rodriguez-Mena, Diego; Herrero, Raquel; Almarcegui, Carmen; Dolz, Isabel; Martin, Jesus; Ara, Jose R; Larrosa, Jose M; Polo, Vicente; Fernández, Javier; Pablo, Luis E

2013-07-02

To evaluate correlations between longitudinal changes in neuro-ophthalmologic measures and quality of life (QOL) and disability in patients with multiple sclerosis (MS), using optical coherence tomography (OCT), visual evoked potentials (VEP), and visual field examination. Fifty-four patients with relapsing-remitting MS were enrolled in this study and underwent Multiple Sclerosis Quality of Life questionnaire (54 items) (MSQOL-54) and Expanded Disability Status Scale (EDSS) evaluation, as well as complete neuro-ophthalmologic examination including visual field testing and retinal nerve fiber layer (RNFL) measurements using Cirrus and Spectralis OCT and VEP. All patients were re-evaluated at 12, 24, and 36 months. Logistical regression was performed to analyze which measures, if any, could predict QOL. Overall, RNFL thickness results at the baseline evaluation were significantly different from those at 3 years (p ≤ 0.05), but there were no differences in functional measures (visual acuity, contrast sensitivity, color vision, visual field, and VEP). A reduced MSQOL-54 score was associated with an increase in EDSS score and a decrease in both functional and structural parameters. Patients with longer MS duration presented with a lower MSQOL-54 score (reduction in QOL). Patients with progressive axonal loss as seen in RNFL results had a lower QOL and more functional disability.

Pediatric Perimeter-A Novel Device to Measure Visual Fields in Infants and Patients with Special Needs.

PubMed

Satgunam, PremNandhini; Datta, Sourav; Chillakala, Koteswararao; Bobbili, Karthik R; Joshi, Dhruv

2017-07-01

There are no commercially available devices to measure visual fields in infants. We developed a device, "Pediatric Perimeter," that quantifies visual field extent (VFE) for infants. We describe the construction, validation, and use of this device. A hemispherical dome with light emitting diodes (LEDs) was constructed. The LEDs were controlled using a computer program to measure reaction time (RT) to gross visual fields (GVF) and the VFE. Participants were tested in supine position in a dark room. Eye or head movement towards the stimuli was monitored with an infrared (IR) camera. Validation was done on 10 adults (mean age: 24.4 ± 5 years) with tunnel vision simulator. Perimetry was performed on 19 infants (age: 2.3-12 months), five infants with normal milestones. GVF and VFE were estimated in 17 and 7 infants, respectively. Median RT of infants with developmental delay was 663 ms and 380 ms for healthy infants. Also, 14 children (age: 14 months-6 years) with developmental delay and five patients with cognitive impairment were tested. Visual field isopter and RT can be examined with the Pediatric Perimeter device on infants and patients with special needs. Further testing on infants will need to assess the repeatability. A large-scale study will be needed to compare typically developing infants and infants with delayed milestones with this device. Quantifiable parameters obtained with this device can be used as outcome measures in clinical examination of infants and patients with special needs. This device can be used in pediatric, neurology, and ophthalmology clinics.

Visualizing planetary data by using 3D engines

NASA Astrophysics Data System (ADS)

Elgner, S.; Adeli, S.; Gwinner, K.; Preusker, F.; Kersten, E.; Matz, K.-D.; Roatsch, T.; Jaumann, R.; Oberst, J.

2017-09-01

We examined 3D gaming engines for their usefulness in visualizing large planetary image data sets. These tools allow us to include recent developments in the field of computer graphics in our scientific visualization systems and present data products interactively and in higher quality than before. We started to set up the first applications which will take use of virtual reality (VR) equipment.

The Visual Hemifield Asymmetry in the Spatial Blink during Singleton Search and Feature Search

ERIC Educational Resources Information Center

Burnham, Bryan R.; Rozell, Cassandra A.; Kasper, Alex; Bianco, Nicole E.; Delliturri, Antony

2011-01-01

The present study examined a visual field asymmetry in the contingent capture of attention that was previously observed by Du and Abrams (2010). In our first experiment, color singleton distractors that matched the color of a to-be-detected target produced a stronger capture of attention when they appeared in the left visual hemifield than in the…

Synaptic Mechanisms Generating Orientation Selectivity in the ON Pathway of the Rabbit Retina

PubMed Central

Venkataramani, Sowmya

2016-01-01

Neurons that signal the orientation of edges within the visual field have been widely studied in primary visual cortex. Much less is known about the mechanisms of orientation selectivity that arise earlier in the visual stream. Here we examine the synaptic and morphological properties of a subtype of orientation-selective ganglion cell in the rabbit retina. The receptive field has an excitatory ON center, flanked by excitatory OFF regions, a structure similar to simple cell receptive fields in primary visual cortex. Examination of the light-evoked postsynaptic currents in these ON-type orientation-selective ganglion cells (ON-OSGCs) reveals that synaptic input is mediated almost exclusively through the ON pathway. Orientation selectivity is generated by larger excitation for preferred relative to orthogonal stimuli, and conversely larger inhibition for orthogonal relative to preferred stimuli. Excitatory orientation selectivity arises in part from the morphology of the dendritic arbors. Blocking GABAA receptors reduces orientation selectivity of the inhibitory synaptic inputs and the spiking responses. Negative contrast stimuli in the flanking regions produce orientation-selective excitation in part by disinhibition of a tonic NMDA receptor-mediated input arising from ON bipolar cells. Comparison with earlier studies of OFF-type OSGCs indicates that diverse synaptic circuits have evolved in the retina to detect the orientation of edges in the visual input. SIGNIFICANCE STATEMENT A core goal for visual neuroscientists is to understand how neural circuits at each stage of the visual system extract and encode features from the visual scene. This study documents a novel type of orientation-selective ganglion cell in the retina and shows that the receptive field structure is remarkably similar to that of simple cells in primary visual cortex. However, the data indicate that, unlike in the cortex, orientation selectivity in the retina depends on the activity of inhibitory interneurons. The results further reveal the physiological basis for feature detection in the visual system, elucidate the synaptic mechanisms that generate orientation selectivity at an early stage of visual processing, and illustrate a novel role for NMDA receptors in retinal processing. PMID:26985041

Synaptic Mechanisms Generating Orientation Selectivity in the ON Pathway of the Rabbit Retina.

PubMed

Venkataramani, Sowmya; Taylor, W Rowland

2016-03-16

Neurons that signal the orientation of edges within the visual field have been widely studied in primary visual cortex. Much less is known about the mechanisms of orientation selectivity that arise earlier in the visual stream. Here we examine the synaptic and morphological properties of a subtype of orientation-selective ganglion cell in the rabbit retina. The receptive field has an excitatory ON center, flanked by excitatory OFF regions, a structure similar to simple cell receptive fields in primary visual cortex. Examination of the light-evoked postsynaptic currents in these ON-type orientation-selective ganglion cells (ON-OSGCs) reveals that synaptic input is mediated almost exclusively through the ON pathway. Orientation selectivity is generated by larger excitation for preferred relative to orthogonal stimuli, and conversely larger inhibition for orthogonal relative to preferred stimuli. Excitatory orientation selectivity arises in part from the morphology of the dendritic arbors. Blocking GABAA receptors reduces orientation selectivity of the inhibitory synaptic inputs and the spiking responses. Negative contrast stimuli in the flanking regions produce orientation-selective excitation in part by disinhibition of a tonic NMDA receptor-mediated input arising from ON bipolar cells. Comparison with earlier studies of OFF-type OSGCs indicates that diverse synaptic circuits have evolved in the retina to detect the orientation of edges in the visual input. A core goal for visual neuroscientists is to understand how neural circuits at each stage of the visual system extract and encode features from the visual scene. This study documents a novel type of orientation-selective ganglion cell in the retina and shows that the receptive field structure is remarkably similar to that of simple cells in primary visual cortex. However, the data indicate that, unlike in the cortex, orientation selectivity in the retina depends on the activity of inhibitory interneurons. The results further reveal the physiological basis for feature detection in the visual system, elucidate the synaptic mechanisms that generate orientation selectivity at an early stage of visual processing, and illustrate a novel role for NMDA receptors in retinal processing. Copyright © 2016 the authors 0270-6474/16/363336-14$15.00/0.

Retinitis Pigmentosa Sine Pigmento Mimicking a Chiasm Disease.

PubMed

Pellegrini, Francesco; Prosdocimo, Giovanni; Romano, Francesco; Interlandi, Emanuela

2017-08-01

A 75-year-old woman presented to her ophthalmologist complaining of visual loss for several years. The ophthalmic examination was remarkable for a bitemporal visual field defect. Magnetic resonance imaging (MRI) scan of the brain was normal without evidence of chiasm compression. Neuro-ophthalmic examination was consistent with a retinal rather than a chiasmal disease. Retinal multimodal imaging helped in the correct diagnosis of retinitis pigmentosa, later confirmed by genetic testing.

Inhibition of return in the visual field: the eccentricity effect is independent of cortical magnification.

PubMed

Bao, Yan; Lei, Quan; Fang, Yuan; Tong, Yu; Schill, Kerstin; Pöppel, Ernst; Strasburger, Hans

2013-01-01

Inhibition of return (IOR) as an indicator of attentional control is characterized by an eccentricity effect, that is, the more peripheral visual field shows a stronger IOR magnitude relative to the perifoveal visual field. However, it could be argued that this eccentricity effect may not be an attention effect, but due to cortical magnification. To test this possibility, we examined this eccentricity effect in two conditions: the same-size condition in which identical stimuli were used at different eccentricities, and the size-scaling condition in which stimuli were scaled according to the cortical magnification factor (M-scaling), thus stimuli being larger at the more peripheral locations. The results showed that the magnitude of IOR was significantly stronger in the peripheral relative to the perifoveal visual field, and this eccentricity effect was independent of the manipulation of stimulus size (same-size or size-scaling). These results suggest a robust eccentricity effect of IOR which cannot be eliminated by M-scaling. Underlying neural mechanisms of the eccentricity effect of IOR are discussed with respect to both cortical and subcortical structures mediating attentional control in the perifoveal and peripheral visual field.

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

PubMed

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

2018-02-01

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

A case report of ophthalmic artery emboli secondary to Calcium Hydroxylapatite filler injection for nose augmentation- long-term outcome.

PubMed

Cohen, Eyal; Yatziv, Yossi; Leibovitch, Igal; Kesler, Anat; Cnaan, Ran Ben; Klein, Ainat; Goldenberg, Dafna; Habot-Wilner, Zohar

2016-07-08

Filler injection for face augmentation is a common cosmetic procedure in the last decades, in our case report we describe long-term outcomes of a devastating complication of ophthalmic artery emboli following Calcium Hydroxylapatite filler injection to the nose bridge. A healthy 24-year-old women received a Calcium Hydroxylapatite filler injection to her nose bridge for the correction of nose asymmetry 8 years post rhinoplasty. She developed sudden right eye ocular pain and visual disturbances. Visual acuity was 20/20 in both eyes and visual field in the right eye showed inferior arch with fixation sparing and supero-temporal central scotoma. Examination revealed marked periorbital edema and hematoma, ptosis, ocular movements limitation, an infero-temporal branch retinal artery occlusion and multiple choroidal emboli. Eighteen months post initial presentation ptosis and eye movements returned normal and choroidal emboli absorbed almost completely. However, visual acuity declined to 20/60, visual field showed severe progressive deterioration with a central and supero-nasal field remnant and the optic disc became pallor. Cosmetic injection of calcium hydroxylapatite to the nose bridge can result in arterial emboli to the ophthalmic system with optic nerve, retinal and choroidal involvement causing long term severe visual acuity and visual field impairment.

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

NASA Technical Reports Server (NTRS)

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

1980-01-01

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

Deployment of spatial attention to words in central and peripheral vision.

PubMed

Ducrot, Stéphanie; Grainger, Jonathan

2007-05-01

Four perceptual identification experiments examined the influence of spatial cues on the recognition of words presented in central vision (with fixation on either the first or last letter of the target word) and in peripheral vision (displaced left or right of a central fixation point). Stimulus location had a strong effect on word identification accuracy in both central and peripheral vision, showing a strong right visual field superiority that did not depend on eccentricity. Valid spatial cues improved word identification for peripherally presented targets but were largely ineffective for centrally presented targets. Effects of spatial cuing interacted with visual field effects in Experiment 1, with valid cues reducing the right visual field superiority for peripherally located targets, but this interaction was shown to depend on the type of neutral cue. These results provide further support for the role of attentional factors in visual field asymmetries obtained with targets in peripheral vision but not with centrally presented targets.

Application of virtual reality graphics in assessment of concussion.

PubMed

Slobounov, Semyon; Slobounov, Elena; Newell, Karl

2006-04-01

Abnormal balance in individuals suffering from traumatic brain injury (TBI) has been documented in numerous recent studies. However, specific mechanisms causing balance deficits have not been systematically examined. This paper demonstrated the destabilizing effect of visual field motion, induced by virtual reality graphics in concussed individuals but not in normal controls. Fifty five student-athletes at risk for concussion participated in this study prior to injury and 10 of these subjects who suffered MTBI were tested again on day 3, day 10, and day 30 after the incident. Postural responses to visual field motion were recorded using a virtual reality (VR) environment in conjunction with balance (AMTI force plate) and motion tracking (Flock of Birds) technologies. Two experimental conditions were introduced where subjects passively viewed VR scenes or actively manipulated the visual field motion. Long-lasting destabilizing effects of visual field motion were revealed, although subjects were asymptomatic when standard balance tests were introduced. The findings demonstrate that advanced VR technology may detect residual symptoms of concussion at least 30 days post-injury.

Effect of visual field presentation on action planning (estimating reach) in children.

PubMed

Gabbard, Carl; Cordova, Alberto

2012-01-01

In this article, the authors examined the effects of target information presented in different visual fields (lower, upper, central) on estimates of reach via use of motor imagery in children (5-11 years old) and young adults. Results indicated an advantage for estimating reach movements for targets placed in lower visual field (LoVF), with all groups having greater difficulty in the upper visual field (UpVF) condition, especially 5- and 7-year-olds. Complementing these results was an overall age-related increase in accuracy. Based in part on the equivalence hypothesis suggesting that motor imagery and motor planning and execution are similar, the findings support previous work of executed behaviors showing that there is a LoVF bias for motor skill actions of the hand. Given that previous research hints that the UpVF may be bias for visuospatial (perceptual) qualities, research in that area and its association with visuomotor processing (LoVF) should be considered.

The Tölz Temporal Topography Study: mapping the visual field across the life span. Part I: the topography of light detection and temporal-information processing.

PubMed

Poggel, Dorothe A; Treutwein, Bernhard; Calmanti, Claudia; Strasburger, Hans

2012-08-01

Temporal performance parameters vary across the visual field. Their topographical distributions relative to each other and relative to basic visual performance measures and their relative change over the life span are unknown. Our goal was to characterize the topography and age-related change of temporal performance. We acquired visual field maps in 95 healthy participants (age: 10-90 years): perimetric thresholds, double-pulse resolution (DPR), reaction times (RTs), and letter contrast thresholds. DPR and perimetric thresholds increased with eccentricity and age; the periphery showed a more pronounced age-related increase than the center. RT increased only slightly and uniformly with eccentricity. It remained almost constant up to the age of 60, a marked change occurring only above 80. Overall, age was a poor predictor of functionality. Performance decline could be explained only in part by the aging of the retina and optic media. In Part II, we therefore examine higher visual and cognitive functions.

Cortical connective field estimates from resting state fMRI activity.

PubMed

Gravel, Nicolás; Harvey, Ben; Nordhjem, Barbara; Haak, Koen V; Dumoulin, Serge O; Renken, Remco; Curčić-Blake, Branislava; Cornelissen, Frans W

2014-01-01

One way to study connectivity in visual cortical areas is by examining spontaneous neural activity. In the absence of visual input, such activity remains shaped by the underlying neural architecture and, presumably, may still reflect visuotopic organization. Here, we applied population connective field (CF) modeling to estimate the spatial profile of functional connectivity in the early visual cortex during resting state functional magnetic resonance imaging (RS-fMRI). This model-based analysis estimates the spatial integration between blood-oxygen level dependent (BOLD) signals in distinct cortical visual field maps using fMRI. Just as population receptive field (pRF) mapping predicts the collective neural activity in a voxel as a function of response selectivity to stimulus position in visual space, CF modeling predicts the activity of voxels in one visual area as a function of the aggregate activity in voxels in another visual area. In combination with pRF mapping, CF locations on the cortical surface can be interpreted in visual space, thus enabling reconstruction of visuotopic maps from resting state data. We demonstrate that V1 ➤ V2 and V1 ➤ V3 CF maps estimated from resting state fMRI data show visuotopic organization. Therefore, we conclude that-despite some variability in CF estimates between RS scans-neural properties such as CF maps and CF size can be derived from resting state data.

Resting-State Retinotopic Organization in the Absence of Retinal Input and Visual Experience

PubMed Central

Binda, Paola; Benson, Noah C.; Bridge, Holly; Watkins, Kate E.

2015-01-01

Early visual areas have neuronal receptive fields that form a sampling mosaic of visual space, resulting in a series of retinotopic maps in which the same region of space is represented in multiple visual areas. It is not clear to what extent the development and maintenance of this retinotopic organization in humans depend on retinal waves and/or visual experience. We examined the corticocortical receptive field organization of resting-state BOLD data in normally sighted, early blind, and anophthalmic (in which both eyes fail to develop) individuals and found that resting-state correlations between V1 and V2/V3 were retinotopically organized for all subject groups. These results show that the gross retinotopic pattern of resting-state connectivity across V1-V3 requires neither retinal waves nor visual experience to develop and persist into adulthood. SIGNIFICANCE STATEMENT Evidence from resting-state BOLD data suggests that the connections between early visual areas develop and are maintained even in the absence of retinal waves and visual experience. PMID:26354906

The Effects of Compensatory Scanning Training on Mobility in Patients with Homonymous Visual Field Defects: Further Support, Predictive Variables and Follow-Up

PubMed Central

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

2016-01-01

Introduction People with homonymous visual field defects (HVFD) often report difficulty detecting obstacles in the periphery on their blind side in time when moving around. Recently, a randomized controlled trial showed that the InSight-Hemianopia Compensatory Scanning Training (IH-CST) specifically improved detection of peripheral stimuli and avoiding obstacles when moving around, especially in dual task situations. Method The within-group training effects of the previously reported IH-CST are examined in an extended patient group. Performance of patients with HVFD on a pre-assessment, post-assessment and follow-up assessment and performance of a healthy control group are compared. Furthermore, it is examined whether training effects can be predicted by demographic characteristics, variables related to the visual disorder, and neuropsychological test results. Results Performance on both subjective and objective measures of mobility-related scanning was improved after training, while no evidence was found for improvement in visual functions (including visual fields), reading, visual search and dot counting. Self-reported improvement did not correlate with improvement in objective mobility performance. According to the participants, the positive effects were still present six to ten months after training. No demographic characteristics, variables related to the visual disorder, and neuropsychological test results were found to predict the size of training effect, although some inconclusive evidence was found for more improvement in patients with left-sided HVFD than in patients with right-sided HFVD. Conclusion Further support was found for a positive effect of IH-CST on detection of visual stimuli during mobility-related activities specifically. Based on the reports given by patients, these effects appear to be long-term effects. However, no conclusions can be drawn on the objective long-term training effects. PMID:27935973

[Eccentricity-dependent influence of amodal completion on visual search].

PubMed

Shirama, Aya; Ishiguchi, Akira

2009-06-01

Does amodal completion occur homogeneously across the visual field? Rensink and Enns (1998) found that visual search for efficiently-detected fragments became inefficient when observers perceived the fragments as a partially-occluded version of a distractor due to a rapid completion process. We examined the effect of target eccentricity in Rensink and Enns's tasks and a few additional tasks by magnifying the stimuli in the peripheral visual field to compensate for the loss of spatial resolution (M-scaling; Rovamo & Virsu, 1979). We found that amodal completion disrupted the efficient search for the salient fragments (i.e., target) even when the target was presented at high eccentricity (within 17 deg). In addition, the configuration effect of the fragments, which produced amodal completion, increased with eccentricity while the same target was detected efficiently at the lowest eccentricity. This eccentricity effect is different from a previously-reported eccentricity effect where M-scaling was effective (Carrasco & Frieder, 1997). These findings indicate that the visual system has a basis for rapid completion across the visual field, but the stimulus representations constructed through amodal completion have eccentricity-dependent properties.

Retinitis Pigmentosa Sine Pigmento Mimicking a Chiasm Disease

PubMed Central

Pellegrini, Francesco; Prosdocimo, Giovanni; Romano, Francesco; Interlandi, Emanuela

2017-01-01

ABSTRACT A 75-year-old woman presented to her ophthalmologist complaining of visual loss for several years. The ophthalmic examination was remarkable for a bitemporal visual field defect. Magnetic resonance imaging (MRI) scan of the brain was normal without evidence of chiasm compression. Neuro-ophthalmic examination was consistent with a retinal rather than a chiasmal disease. Retinal multimodal imaging helped in the correct diagnosis of retinitis pigmentosa, later confirmed by genetic testing. PMID:29344059

Pediatric Perimeter—A Novel Device to Measure Visual Fields in Infants and Patients with Special Needs

PubMed Central

Satgunam, PremNandhini; Datta, Sourav; Chillakala, Koteswararao; Bobbili, Karthik R.; Joshi, Dhruv

2017-01-01

Purpose There are no commercially available devices to measure visual fields in infants. We developed a device, “Pediatric Perimeter,” that quantifies visual field extent (VFE) for infants. We describe the construction, validation, and use of this device. Methods A hemispherical dome with light emitting diodes (LEDs) was constructed. The LEDs were controlled using a computer program to measure reaction time (RT) to gross visual fields (GVF) and the VFE. Participants were tested in supine position in a dark room. Eye or head movement towards the stimuli was monitored with an infrared (IR) camera. Validation was done on 10 adults (mean age: 24.4 ± 5 years) with tunnel vision simulator. Results Perimetry was performed on 19 infants (age: 2.3–12 months), five infants with normal milestones. GVF and VFE were estimated in 17 and 7 infants, respectively. Median RT of infants with developmental delay was 663 ms and 380 ms for healthy infants. Also, 14 children (age: 14 months–6 years) with developmental delay and five patients with cognitive impairment were tested. Conclusion Visual field isopter and RT can be examined with the Pediatric Perimeter device on infants and patients with special needs. Further testing on infants will need to assess the repeatability. A large-scale study will be needed to compare typically developing infants and infants with delayed milestones with this device. Translational Relevance Quantifiable parameters obtained with this device can be used as outcome measures in clinical examination of infants and patients with special needs. This device can be used in pediatric, neurology, and ophthalmology clinics. PMID:28685105

Stimulus size and eccentricity in visually induced perception of horizontally translational self-motion.

PubMed

Nakamura, S; Shimojo, S

1998-10-01

The effects of the size and eccentricity of the visual stimulus upon visually induced perception of self-motion (vection) were examined with various sizes of central and peripheral visual stimulation. Analysis indicated the strength of vection increased linearly with the size of the area in which the moving pattern was presented, but there was no difference in vection strength between central and peripheral stimuli when stimulus sizes were the same. Thus, the effect of stimulus size is homogeneous across eccentricities in the visual field.

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

PubMed

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

2017-02-11

Objective: To investigate the rationality of visual field morphological stages of glaucoma, its relationship with visual field index and their diagnostic value. Methods: Retrospective series case study. Two hundred and seventy-four glaucoma patients and 100 normal control received visual field examination by Humphrey perimeter using standard automatic perimetry (SAP) program from March 2014 to September 2014. Glaucoma patients were graded into four stages according to characteristic morphological damage of visual field, distribution of mean defect (MD) and visual field index (VFI) of each stage were plotted and receiver operation characteristic curve (ROC) was used to explore its correlation with MD and VFI. The diagnostic value of MD and VFI was also compared. For the comparison of general data of subjects, categorical variables were compared using χ(2) test, numerical variables were compared using F test. MD and VFI were compared using ANOVA among stages according to visual field, followed by multiple comparisons using LSD method. The correlation between MD and VFI and different stages according to visual field defined their diagnostic value, and compared using area under the curve (AUC) of ROC. Results: No characteristic visual field damage was found in normal control group, and MD and VFI was (-0.06±1.24) dB and (99.15±0.76)%, respectively. Glaucomatous visual field damage was graded into early, medium, late and end stage according to morphological characteristic. MD for each stage were (-2.83±2.00) dB, (-9.70±3.68) dB, (-18.46±2.90) dB, and (-27.96±2.76) dB, respectively. VFI for each stage were (93.84±3.61)%, (75.16±10.85)%, (49.36±11.26)% and (17.65±10.59)%, respectively. MD and VFI of each stage of glaucomatous group and normal control group were all significantly different ( F= 1 165.53 and P <0.01 for MD; F= 1 028.04 and P <0.01 for VFI). AUC of ROC was A(MD)=0.91 and Se(MD)=0.01 (95% confident interval was 0.89-0.94) for MD, and A(VFI)=0.97, Se(VFI)=0.01 (95% confident interval was 0.94-0.10) for VFI. So, AUC(VFI)>AUC(MD) ( P< 0.05). Conclusions: It is feasible and rational of glaucomatous visual field damage to be graded into early, medium, late and end stage using Humphrey perimeter. Distribution of MD and VFI for each stage was relatively concentrative. Both MD and VFI were useful for grading glaucomatous visual field damage with preference for VFI. (Chin J Ophthalmol, 2017, 53: 92-97) .

Ocular fundus manifestation of two patients following long-term chloroquine therapy: a case report

PubMed Central

2010-01-01

This report describes the typical manifestations of chloroquine retinopathy with some advanced new technology. A series of examinations were performed on the patients, including the fundus fluorescein angiography, optical coherence tomography, GDxVCC Nerve Fiber Analyzer, full-field electroretinography, multifocal electroretinography and visual field examinations, to provide a better understanding of chloroquine retinopathy. PMID:20346186

Localized direction selective responses in the dendrites of visual interneurons of the fly

PubMed Central

2010-01-01

Background The various tasks of visual systems, including course control, collision avoidance and the detection of small objects, require at the neuronal level the dendritic integration and subsequent processing of many spatially distributed visual motion inputs. While much is known about the pooled output in these systems, as in the medial superior temporal cortex of monkeys or in the lobula plate of the insect visual system, the motion tuning of the elements that provide the input has yet received little attention. In order to visualize the motion tuning of these inputs we examined the dendritic activation patterns of neurons that are selective for the characteristic patterns of wide-field motion, the lobula-plate tangential cells (LPTCs) of the blowfly. These neurons are known to sample direction-selective motion information from large parts of the visual field and combine these signals into axonal and dendro-dendritic outputs. Results Fluorescence imaging of intracellular calcium concentration allowed us to take a direct look at the local dendritic activity and the resulting local preferred directions in LPTC dendrites during activation by wide-field motion in different directions. These 'calcium response fields' resembled a retinotopic dendritic map of local preferred directions in the receptive field, the layout of which is a distinguishing feature of different LPTCs. Conclusions Our study reveals how neurons acquire selectivity for distinct visual motion patterns by dendritic integration of the local inputs with different preferred directions. With their spatial layout of directional responses, the dendrites of the LPTCs we investigated thus served as matched filters for wide-field motion patterns. PMID:20384983

[Case of brain infarction in the anterior choroidal artery territory with homonymous scotomas].

PubMed

Nakae, Yoshiharu; Higashiyama, Yuichi; Kuroiwa, Yoshiyuki

2009-08-01

We report a case of brain infarction in the anterior choroidal artery territory accompanied homonymous scotomas. A 59-year-old man with diabetes mellitus felt weakness in his left upper and lower extremities. He was admitted to our hospital with mild hemiparesis on his left side. He noticed a small black spot in the left inferior portion of his visual field; however, this disappeared within one minute. He had no visual defects as assessed by a confrontation test, but a Goldmann visual field test revealed that there were homonymous scotomas in the left inferior portion of the visual field. Brain MRI showed hyperintense signals on diffusion-weighted images in the territory of the right anterior choroidal artery. He was diagnosed as having a brain infarction. The anterior choroidal artery penetrates the lateral geniculate nucleus from the front, and branches of the artery usually supply the medial and lateral parts of the lateral geniculate nucleus. Occlusion of these branches causes the loss of the upper and lower homonymous sectors in the visual field. The present case exhibited homonymous scotomas. We assumed that our patient's homonymous scotomas were a variant form of wedge-shaped visual field deficits often seen in anterior choroidal artery syndrome. On the basis the experience gained in this case, we consider that patients with brain infarction in the anterior choroidal artery territory should undergo ophthalmological examination, even when no visual defects are detected by a confrontation test.

Properties of pattern standard deviation in open-angle glaucoma patients with hemi-optic neuropathy and bi-optic neuropathy.

PubMed

Heo, Dong Won; Kim, Kyoung Nam; Lee, Min Woo; Lee, Sung Bok; Kim, Chang-Sik

2017-01-01

To evaluate the properties of pattern standard deviation (PSD) according to localization of the glaucomatous optic neuropathy. We enrolled 242 eyes of 242 patients with primary open-angle glaucoma, with a best-corrected visual acuity ≥ 20/25, and no media opacity. Patients were examined via dilated fundus photography, spectral-domain optical coherence tomography, and Humphrey visual field examination, and divided into those with hemi-optic neuropathy (superior or inferior) and bi-optic neuropathy (both superior and inferior). We assessed the relationship between mean deviation (MD) and PSD. Using broken stick regression analysis, the tipping point was identified, i.e., the point at which MD became significantly associated with a paradoxical reversal of PSD. In 91 patients with hemi-optic neuropathy, PSD showed a strong correlation with MD (r = -0.973, β = -0.965, p < 0.001). The difference between MD and PSD ("-MD-PSD") was constant (mean, -0.32 dB; 95% confidence interval, -2.48~1.84 dB) regardless of visual field defect severity. However, in 151 patients with bi-optic neuropathy, a negative correlation was evident between "-MD-PSD" and MD (r2 = 0.907, p < 0.001). Overall, the MD tipping point was -14.0 dB, which was close to approximately 50% damage of the entire visual field (p < 0.001). Although a false decrease of PSD usually begins at approximately 50% visual field damage, in patients with hemi-optic neuropathy, the PSD shows no paradoxical decrease and shows a linear correlation with MD.

Long-term follow-up of two patients with oligocone trichromacy.

PubMed

Smirnov, Vasily; Drumare, Isabelle; Bouacha, Ikram; Puech, Bernard; Defoort-Dhellemmes, Sabine

2015-10-01

Oligocone trichromacy (OT) is an uncommon cone dysfunction disorder, the mechanism of which remains poorly understood. OT has been thought to be non-progressive, but its long-term visual outcome has been seldom reported in the literature. Our aim was to present two OT patients followed at our institution over 18 years. Complete ocular examination, color vision, visual fields, and full-field electroretinography (ERG) were performed at initial presentation and follow-up. Spectral-domain optical coherence tomography (OCT) was performed during follow-up when available at our institution. Initial ocular examination showed satisfactory visual acuities with normal fundus examination and near-to-normal color vision. However, computerized perimetry demonstrated a ring-shaped scotoma around fixation, and ERG showed a profound cone dysfunction. The discrepancy between preserved color vision and profound cone dysfunction leads to the diagnosis of OT. Subsequent follow-ups over 18 years showed subtle degradation of visual acuities along with progression of the myopia in both patients and slight worsening of color vision in one patient. Initial OCT revealed a focal interruption of the ellipsoid line along with decreased thickness of the perifoveal macula. Subsequent OCT imaging performed 2 years later did not show any macular changes. Although OT is known to be a non-progressive cone dysfunction, our results suggest that subtle degradation of the visual function might happen over time.

The effect of contextual cues on the encoding of motor memories.

PubMed

Howard, Ian S; Wolpert, Daniel M; Franklin, David W

2013-05-01

Several studies have shown that sensory contextual cues can reduce the interference observed during learning of opposing force fields. However, because each study examined a small set of cues, often in a unique paradigm, the relative efficacy of different sensory contextual cues is unclear. In the present study we quantify how seven contextual cues, some investigated previously and some novel, affect the formation and recall of motor memories. Subjects made movements in a velocity-dependent curl field, with direction varying randomly from trial to trial but always associated with a unique contextual cue. Linking field direction to the cursor or background color, or to peripheral visual motion cues, did not reduce interference. In contrast, the orientation of a visual object attached to the hand cursor significantly reduced interference, albeit by a small amount. When the fields were associated with movement in different locations in the workspace, a substantial reduction in interference was observed. We tested whether this reduction in interference was due to the different locations of the visual feedback (targets and cursor) or the movements (proprioceptive). When the fields were associated only with changes in visual display location (movements always made centrally) or only with changes in the movement location (visual feedback always displayed centrally), a substantial reduction in interference was observed. These results show that although some visual cues can lead to the formation and recall of distinct representations in motor memory, changes in spatial visual and proprioceptive states of the movement are far more effective than changes in simple visual contextual cues.

Grammatical number agreement processing using the visual half-field paradigm: an event-related brain potential study.

PubMed

Kemmer, Laura; Coulson, Seana; Kutas, Marta

2014-02-01

Despite indications in the split-brain and lesion literatures that the right hemisphere is capable of some syntactic analysis, few studies have investigated right hemisphere contributions to syntactic processing in people with intact brains. Here we used the visual half-field paradigm in healthy adults to examine each hemisphere's processing of correct and incorrect grammatical number agreement marked either lexically, e.g., antecedent/reflexive pronoun ("The grateful niece asked herself/*themselves…") or morphologically, e.g., subject/verb ("Industrial scientists develop/*develops…"). For reflexives, response times and accuracy of grammaticality decisions suggested similar processing regardless of visual field of presentation. In the subject/verb condition, we observed similar response times and accuracies for central and right visual field (RVF) presentations. For left visual field (LVF) presentation, response times were longer and accuracy rates were reduced relative to RVF presentation. An event-related brain potential (ERP) study using the same materials revealed similar ERP responses to the reflexive pronouns in the two visual fields, but very different ERP effects to the subject/verb violations. For lexically marked violations on reflexives, P600 was elicited by stimuli in both the LVF and RVF; for morphologically marked violations on verbs, P600 was elicited only by RVF stimuli. These data suggest that both hemispheres can process lexically marked pronoun agreement violations, and do so in a similar fashion. Morphologically marked subject/verb agreement errors, however, showed a distinct LH advantage. Copyright © 2013 Elsevier B.V. All rights reserved.

Grammatical number agreement processing using the visual half-field paradigm: An event-related brain potential study

PubMed Central

Kemmer, Laura; Coulson, Seana; Kutas, Marta

2014-01-01

Despite indications in the split-brain and lesion literatures that the right hemisphere is capable of some syntactic analysis, few studies have investigated right hemisphere contributions to syntactic processing in people with intact brains. Here we used the visual half-field paradigm in healthy adults to examine each hemisphere’s processing of correct and incorrect grammatical number agreement marked either lexically, e.g., antecedent/reflexive pronoun (“The grateful niece asked herself/*themselves…”) or morphologically, e.g., subject/verb (“Industrial scientists develop/*develops…”). For reflexives, response times and accuracy of grammaticality decisions suggested similar processing regardless of visual field of presentation. In the subject/verb condition, we observed similar response times and accuracies for central and right visual field (RVF) presentations. For left visual field (LVF) presentation, response times were longer and accuracy rates were reduced relative to RVF presentation. An event-related brain potential (ERP) study using the same materials revealed similar ERP responses to the reflexive pronouns in the two visual fields, but very different ERP effects to the subject/verb violations. For lexically marked violations on reflexives, P600 was elicited by stimuli in both the LVF and RVF; for morphologically marked violations on verbs, P600 was elicited only by RVF stimuli. These data suggest that both hemispheres can process lexically marked pronoun agreement violations, and do so in a similar fashion. Morphologically marked subject/verb agreement errors, however, showed a distinct LH advantage. PMID:24326084

Long Term Results of Visual Field Progression Analysis in Open Angle Glaucoma Patients Under Treatment.

PubMed

Kocatürk, Tolga; Bekmez, Sinan; Katrancı, Merve; Çakmak, Harun; Dayanır, Volkan

2015-01-01

To evaluate visual field progression with trend and event analysis in open angle glaucoma patients under treatment. Fifteen year follow-up results of 408 eyes of 217 glaucoma patients who were followed at Adnan Menderes University, Department of Ophthalmology between 1998 and 2013 were analyzed retrospectively. Visual field data were collected for Mean Deviation (MD), Visual Field Index (VFI), and event occurrence. There were 146 primary open-angle glaucoma (POAG), 123 pseudoexfoliative glaucoma (XFG) and 139 normal tension glaucoma (NTG) eyes. MD showed significant change in all diagnostic groups (p<0.001). The difference of VFI between first and last examinations were significantly different in POAG (p<0.001), and XFG (p<0.003) but not in NTG. VFI progression rates were -0.3, -0.43, and -0.2 % loss/year in treated POAG, XFG, and NTG, respectively. The number of empty triangles were statistically different between POAG-NTG (p=0.001), and XFG-NTG (p=0.002) groups. The number of half-filled (p=0.002), and full-filled (p=0.010) triangles were significantly different between XFG-NTG groups. Functional long-term follow-up of glaucoma patients can be monitored with visual field indices. We herein report our fifteen year follow-up results in open angle glaucoma.

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

PubMed

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

2017-09-01

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

Colored floaters as a manifestation of digoxin toxicity.

PubMed

Shi, Lynn; Sun, Linus D; Odel, Jeffrey G

2018-06-01

Since its report in one patient more than 70 years ago, digitalis-induced colored muscae volitantes have not surfaced again in the literature. We report here a case of digoxin induced colored floaters. An 89-year-old man on 0.25 mg digoxin daily developed visual hallucinations and colored floaters. He had floaters in the past but now they were in various colors including yellow, green, blue and red, though predominantly in yellow. These "weirdly" shaped little particles wiggled around as if in a viscous solution and casted shadows in his vision. He also saw geometric shapes, spirals, and cross hatch patterns of various colors that moved and undulated, especially on wallpaper. Ophthalmic examination revealed reduced visual acuity, poor color vision especially in his left eye, along with central depression on Amsler grid and Humphrey visual field in his left eye. Discontinuation of digoxin resulted in complete resolution of his visual symptoms. On subsequent ophthalmic examination, the patient's visual acuity, field testing and color vision improved and he had normal Amsler grid test results. Colored floaters may occur in patients taking cardiac glycosides but this association has not been explored. Unlike optical illusions and visual hallucinations, floaters are entoptic phenomena casting a physical shadow upon the retina and their coloring likely arise from retinal dysfunction. Colored floaters may be a more common visual phenomenon than realized.

Functional and morphological assessment of ocular structures and follow-up of patients with early-stage Parkinson's disease.

PubMed

Hasanov, Samir; Demirkilinc Biler, Elif; Acarer, Ahmet; Akkın, Cezmi; Colakoglu, Zafer; Uretmen, Onder

2018-05-09

To evaluate and follow-up of functional and morphological changes of the optic nerve and ocular structures prospectively in patients with early-stage Parkinson's disease. Nineteen patients with a diagnosis of early-stage Parkinson's disease and 19 age-matched healthy controls were included in the study. All participants were examined minimum three times at the intervals of at least 6 month following initial examination. Pattern visually evoked potentials (VEP), contrast sensitivity assessments at photopic conditions, color vision tests with Ishihara cards and full-field visual field tests were performed in addition to measurement of retinal nerve fiber layer (RNFL) thickness of four quadrants (top, bottom, nasal, temporal), central and mean macular thickness and macular volumes. Best corrected visual acuity was observed significantly lower in study group within all three examinations. Contrast sensitivity values of the patient group were significantly lower in all spatial frequencies. P100 wave latency of VEP was significantly longer, and amplitude was lower in patient group; however, significant deterioration was not observed during the follow-up. Although average peripapillary RNFL thickness was not significant between groups, RNFL thickness in the upper quadrant was thinner in the patient group. While there was no difference in terms of mean macular thickness and total macular volume values between the groups initially, a significant decrease occurred in the patient group during the follow-up. During the initial and follow-up process, a significant deterioration in visual field was observed in the patient group. Structural and functional disorders shown as electro-physiologically and morphologically exist in different parts of visual pathways in early-stage Parkinson's disease.

Rates of glaucomatous visual field change in a large clinical population.

PubMed

Chauhan, Balwantray C; Malik, Rizwan; Shuba, Lesya M; Rafuse, Paul E; Nicolela, Marcelo T; Artes, Paul H

2014-06-10

To determine the rate of glaucomatous visual field change in routine clinical care. Mean deviation (MD) rate was computed in one randomly selected eye of all glaucoma patients and suspects with ≥5 examinations in a tertiary eye-care center. Proportions of "fast" (MD rate, <-1 to -2 dB/y) and "catastrophic" (<-2 dB/y) progressors were determined. The MD rates were computed in tertile groups by the number of examinations, baseline age, and MD. The MD rates were compared to the Canadian Glaucoma Study (CGS), a prospective study with IOP interventions mandated by visual field progression, by pairwise matching of patients by baseline MD. There were 2324 patients with median (interquartile range) baseline age and MD of 65 (56, 74) years and -2.44 (-5.44, -0.86) dB, and follow-up of 7.1 (4.8, 10.2) years with 8 (6, 11) examinations. The median MD rate was -0.05 (0.13, -0.30) dB/y, while the mean follow-up IOP was 17.1 (15.0, 19.7) mm Hg. The MD rate was progressively worse, with a doubling of fast and catastrophic progressors, with each tertile of increasing age. Worse MD rate was associated with lower follow-up IOP. Neither MD rate nor the number of fast and catastrophic progressors was significantly different in clinical care patients matched to CGS patients. Most patients under routine glaucoma care demonstrate slow rates of visual field progression. The MD rate in the current study was similar to an interventional prospective study, but considerably less negative compared to published studies with similar design. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Anxiety and Lateral Cerebral Function

ERIC Educational Resources Information Center

Tucker, Don M.; And Others

1978-01-01

Examines the effect of stressful and nonstressful experimental situations upon the processing capacity of each cerebral hemisphere, through observing the differential performance tasks presented to right and left visual half-fields (VHFs). Also examines attentional bias and lateral eye movements. (Author/RK)

[Clinical feature of chronic compressive optic neuropathy without optic atrophy].

PubMed

Jiang, Libin; Shi, Jitong; Liu, Wendong; Kang, Jun; Wang, Ningli

2014-12-01

To investigate the clinical feature of the chronic compressive optic neuropathy without optic atrophy. Retrospective cases series study. The clinical data of 25 patients (37 eyes) with chronic compressive optic neuropathy without optic atrophy, treated in Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, from October, 2005 to March, 2014, were collected. Those patients had been showing visual symptoms for 6 months or longer, but missed diagnosed or misdiagnosed as other eye diseases due to their normal or slightly changed fundi. The collected data including visual acuities, visual fields, neuroimaging and/or pathologic diagnosis were analyzed. Among the 25 patients, there were 5 males and 20 females, and their ages range from 9 to 74 years [average (47.5 ± 13.4) years]. All patients suffered progressive impaired vision in single eye or both eyes, without exophthalmos or abnormal eye movements. Except one patient had a headache, other patients did not show systemic symptoms. The corrected visual acuities were between HM to 1.0, and their appearances of optic discs and colors of fundi were normal. After neuroimaging and/or pathological examination, it was proven that 14 patients suffered tuberculum sellae meningiomas, 5 patients with hypophysoma, 3 patient with optic nerve sheath meningioma in orbital apex, 1 patient with cavernous hemangioma, 1 patient with vascular malformation in orbital apex and 1 patient with optic nerve glioma. Among the 19 patients whose suffered occupied lesions of saddle area, 14 patients underwent visual field examinations, and only 4 patients showed classic visual field defects caused by optic chiasmal lesions. Occult progressive visual loss was the most important clinical feature of the disease.

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

PubMed

2002-10-01

To examine the relationships between baseline risk factors and sustained decrease of visual field (SDVF) and sustained decrease of visual acuity (SDVA). Cohort study of participants in the Advanced Glaucoma Intervention Study (AGIS). This multicenter study enrolled patients between 1988 and 1992 and followed them until 2001; 789 eyes of 591 patients with advanced glaucoma were randomly assigned to one of two surgical sequences, argon laser trabeculoplasty (ALT)-trabeculectomy-trabeculectomy (ATT) or trabeculectomy-ALT-trabeculectomy (TAT). This report is based on data from 747 eyes. Eyes were offered the next intervention in the sequence upon failure of the previous intervention. Failure was based on recurrent intraocular pressure elevation, visual field defect, and disk rim criteria. Study visits occurred every 6 months; potential follow-up ranged from 8 to 13 years. For each intervention sequence, Cox multiple regression analyses were used to examine the baseline characteristics for association with two vision outcomes: SDVF and SDVA. The magnitude of the association is measured by the hazard ratio (HR), where HR for binary variables is the relative change in the hazard (or risk) of the outcome in eyes with the factor divided by the hazard in eyes without the factor, and HR for continuous variables is the relative change in the hazard (or risk) of the outcome in eyes with a unit increase in the factor. Characteristics associated with increased SDVF risk in the ATT sequence are: less baseline visual field defect (hazard ratio [HR] = 0.86, P <.001, 95% CI = 0.82-0.90), male gender (HR = 2.23, P <.001, 1.54-3.23), and worse baseline visual acuity (HR = 0.96, P =.001, 0.94-0.98); in the TAT sequence: less baseline visual field defect (HR = 0.93, P =.001, 0.89-0.97) and diabetes (HR = 1.87, P =.007, 1.18-2.97). Characteristics associated with increased SDVA risk in both treatment sequences are better baseline acuity (ATT: HR = 1.05, P <.001, 1.02-1.09; TAT: HR = 1.06, P <.001, 1.03-1.08), older age (ATT: HR = 1.05, P =.001, 1.02-1.08; TAT: HR = 1.04, P =.002, 1.01-1.06), and less formal education (ATT: HR = 1.92, P =.001, 1.29-2.88; TAT: HR = 1.77, P =.002, 1.22-2.54). For SDVF, risk factors were better baseline visual field in both treatment sequences, male gender, and worse baseline visual acuity in the ATT sequence, and diabetes in the TAT sequence. For SDVA, risk factors in both treatment sequences were better baseline visual acuity, older age, and less formal education.

Gaze Patterns of Gross Anatomy Students Change with Classroom Learning

ERIC Educational Resources Information Center

Zumwalt, Ann C.; Iyer, Arjun; Ghebremichael, Abenet; Frustace, Bruno S.; Flannery, Sean

2015-01-01

Numerous studies have documented that experts exhibit more efficient gaze patterns than those of less experienced individuals. In visual search tasks, experts use fewer, longer fixations to fixate for relatively longer on salient regions of the visual field while less experienced observers spend more time examining nonsalient regions. This study…

Hemorrhagic Retinopathy after Spondylosis Surgery and Seizure.

PubMed

Kord Valeshabad, Ali; Francis, Andrew W; Setlur, Vikram; Chang, Peter; Mieler, William F; Shahidi, Mahnaz

2015-08-01

To report bilateral hemorrhagic retinopathy in an adult female subject after lumbar spinal surgery and seizure. A 38-year-old woman presented with bilateral blurry vision and spots in the visual field. The patient had lumbar spondylosis surgery that was complicated by a dural tear with persistent cerebrospinal fluid leak. Visual symptoms started immediately after witnessed seizure-like activity. At presentation, visual acuity was 20/100 and 20/25 in the right and left eye, respectively. Dilated fundus examination demonstrated bilateral hemorrhagic retinopathy with subhyaloid, intraretinal, and subretinal involvement. At 4-month follow-up, visual acuity improved to 20/60 and 20/20 in the right and left eye, respectively. Dilated fundus examination and fundus photography showed resolution of retinal hemorrhages in both eyes. The first case of bilateral hemorrhagic retinopathy after lumbar spondylosis surgery and witnessed seizure in an adult was reported. Ophthalmic examination may be warranted after episodes of seizure in adults.

Effect of a patient training video on visual field test reliability

PubMed Central

Sherafat, H; Spry, P G D; Waldock, A; Sparrow, J M; Diamond, J P

2003-01-01

Aims: To evaluate the effect of a visual field test educational video on the reliability of the first automated visual field test of new patients. Methods: A prospective, randomised, controlled trial of an educational video on visual field test reliability of patients referred to the hospital eye service for suspected glaucoma was undertaken. Patients were randomised to either watch an educational video or a control group with no video. The video group was shown a 4.5 minute audiovisual presentation to familiarise them with the various aspects of visual field examination with particular emphasis on sources of unreliability. Reliability was determined using standard criteria of fixation loss rate less than 20%, false positive responses less than 33%, and false negative responses less than 33%. Results: 244 patients were recruited; 112 in the video group and 132 in the control group with no significant between group difference in age, sex, and density of field defects. A significant improvement in reliability (p=0.015) was observed in the group exposed to the video with 85 (75.9%) patients having reliable results compared to 81 (61.4%) in the control group. The difference was not significant for the right (first tested) eye with 93 (83.0%) of the visual fields reliable in the video group compared to 106 (80.0%) in the control group (p = 0.583), but was significant for the left (second tested) eye with 97 (86.6 %) of the video group reliable versus 97 (73.5%) of the control group (p = 0.011). Conclusions: The use of a brief, audiovisual patient information guide on taking the visual field test produced an improvement in patient reliability for individuals tested for the first time. In this trial the use of the video had most of its impact by reducing the number of unreliable fields from the second tested eye. PMID:12543740

Effect of a patient training video on visual field test reliability.

PubMed

Sherafat, H; Spry, P G D; Waldock, A; Sparrow, J M; Diamond, J P

2003-02-01

To evaluate the effect of a visual field test educational video on the reliability of the first automated visual field test of new patients. A prospective, randomised, controlled trial of an educational video on visual field test reliability of patients referred to the hospital eye service for suspected glaucoma was undertaken. Patients were randomised to either watch an educational video or a control group with no video. The video group was shown a 4.5 minute audiovisual presentation to familiarize them with the various aspects of visual field examination with particular emphasis on sources of unreliability. Reliability was determined using standard criteria of fixation loss rate less than 20%, false positive responses less than 33%, and false negative responses less than 33%. 244 patients were recruited; 112 in the video group and 132 in the control group with no significant between group difference in age, sex, and density of field defects. A significant improvement in reliability (p=0.015) was observed in the group exposed to the video with 85 (75.9%) patients having reliable results compared to 81 (61.4%) in the control group. The difference was not significant for the right (first tested) eye with 93 (83.0%) of the visual fields reliable in the video group compared to 106 (80.0%) in the control group (p = 0.583), but was significant for the left (second tested) eye with 97 (86.6 %) of the video group reliable versus 97 (73.5%) of the control group (p = 0.011). The use of a brief, audiovisual patient information guide on taking the visual field test produced an improvement in patient reliability for individuals tested for the first time. In this trial the use of the video had most of its impact by reducing the number of unreliable fields from the second tested eye.

Longitudinal and Cross-Sectional Analyses of Visual Field Progression in Participants of the Ocular Hypertension Treatment Study (OHTS)

PubMed Central

Chauhan, Balwantray C; Keltner, John L; Cello, Kim E; Johnson, Chris A; Anderson, Douglas R; Gordon, Mae O; Kass, Michael A

2014-01-01

Purpose Visual field progression can be determined by evaluating the visual field by serial examinations (longitudinal analysis), or by a change in classification derived from comparison to age-matched normal data in single examinations (cross-sectional analysis). We determined the agreement between these two approaches in data from the Ocular Hypertension Treatment Study (OHTS). Methods Visual field data from 3088 eyes of 1570 OHTS participants (median follow-up 7 yrs, 15 tests with static automated perimetry) were analysed. Longitudinal analyses were performed with change probability with total and pattern deviation, and cross-sectional analysis with Glaucoma Hemifield Test, Corrected Pattern Standard Deviation, and Mean Deviation. The rates of Mean Deviation and General Height change were compared to estimate the degree of diffuse loss in emerging glaucoma. Results The agreement on progression in longitudinal and cross-sectional analyses ranged from 50% to 61% and remained nearly constant across a wide range of criteria. In contrast, the agreement on absence of progression ranged from 97% to 99.7%, being highest for the stricter criteria. Analyses of pattern deviation were more conservative than total deviation, with a 3 to 5 times lesser incidence of progression. Most participants developing field loss had both diffuse and focal change. Conclusions Despite considerable overall agreement, between 40 to 50% of eyes identified as having progressed with either longitudinal or cross-sectional analyses were identified with only one of the analyses. Because diffuse change is part of early glaucomatous damage, pattern deviation analyses may underestimate progression in patients with ocular hypertension. PMID:21149774

Aircrew laser eye protection: visual consequences and mission performance.

PubMed

Thomas, S R

1994-05-01

Battlefield laser proliferation poses a mounting risk to aircrew and ground personnel. Laser eye protection (LEP) based on current mature, mass-producible technologies absorbs visible light and can impact visual performance and color identification. These visual consequences account for many of the mission incompatibilities associated with LEP. Laboratory experiments and field investigations that examined the effects of LEP on visual performance and mission compatibility are reviewed. Laboratory experiments assessed the ability of subjects to correctly read and identify the color of head-down display symbology and tactical pilotage charts (TPC's) with three prototype LEP visors. Field investigations included Weapons Systems Trainer (WST), ground, and flight tests of the LEP visors. Recommendations for modifying aviation lighting systems to improve LEP compatibility are proposed. Issues concerning flight safety when using LEP during air operation are discussed.

Wind Tunnel Visualization of the Flow Over a Full-Scale F/A-18 Aircraft

NASA Technical Reports Server (NTRS)

Lanser, Wendy R.; Botha, Gavin J.; James, Kevin D.; Crowder, James P.; Schmitz, Fredric H. (Technical Monitor)

1994-01-01

The proposed paper presents flow visualization performed during experiments conducted on a full-scale F/A-18 aircraft in the 80- by 120-Foot Wind-Tunnel at NASA Ames Research Center. This investigation used both surface and off-surface flow visualization techniques to examine the flow field on the forebody, canopy, leading edge extensions (LEXs), and wings. The various techniques used to visualize the flow field were fluorescent tufts, flow cones treated with reflective material, smoke in combination with a laser light sheet, and a video imaging system. The flow visualization experiments were conducted over an angle of attack range from 20deg to 45deg and over a sideslip range from -10deg to 10deg. The results show regions of attached and separated flow on the forebody, canopy, and wings. Additionally, the vortical flow is clearly visible over the leading-edge extensions, canopy, and wings.

The Functional Architecture of the Retina.

ERIC Educational Resources Information Center

Masland, Richard H.

1986-01-01

Examines research related to the retina's coding of visual input with emphasis on the organization of two kinds of ganglion cell receptive fields. Reviews current techniques for examining the shapes and arrangement in the retina of entire populations of nerve cells. (ML)

Effect of visual field locus and oscillation frequencies on posture control in an ecological environment.

PubMed

Piponnier, Jean-Claude; Hanssens, Jean-Marie; Faubert, Jocelyn

2009-01-14

To examine the respective roles of central and peripheral vision in the control of posture, body sway amplitude (BSA) and postural perturbations (given by velocity root mean square or vRMS) were calculated in a group of 19 healthy young adults. The stimulus was a 3D tunnel, either static or moving sinusoidally in the anterior-posterior direction. There were nine visual field conditions: four central conditions (4, 7, 15, and 30 degrees); four peripheral conditions (central occlusions of 4, 7, 15, and 30 degrees); and a full visual field condition (FF). The virtual tunnel respected all the aspects of a real physical tunnel (i.e., stereoscopy and size increase with proximity). The results show that, under static conditions, central and peripheral visual fields appear to have equal importance for the control of stance. In the presence of an optic flow, peripheral vision plays a crucial role in the control of stance, since it is responsible for a compensatory sway, whereas central vision has an accessory role that seems to be related to spatial orientation.

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.

Useful field of view test performance throughout adulthood in subjects without ocular disorders.

PubMed

Woutersen, Karlijn; van den Berg, Albert V; Boonstra, F Nienke; Theelen, Thomas; Goossens, Jeroen

2018-01-01

Previous research has shown an age-related decline in Useful Field of View (UFOV) test performance, which measures the duration required to extract relevant information from a scene in three subtasks. However, these results are mostly based on data that may have been confounded by (age-related) ocular diseases. We examined UFOV performance in subjects aged 19.5 to 70.3 years to investigate how UFOV performance changes throughout adulthood. All subjects underwent a thorough ophthalmological examination to exclude ocular disorders. We also examined some elementary visual functions, i.e., near and far visual acuity, crowding and contrast sensitivity. We investigated whether these functions were related to age and whether they could explain a possible age-related decline in UFOV performance. The subjects (n = 41) performed very well on almost every measure and reached far better UFOV and visual acuity scores than those reported by other studies that relied on self-reported absence of ocular pathology. We did not find significant relationships between age and any of the elementary visual functions or the first two UFOV subtasks (R2UFOV1 = 0.03, p = 0.25; R2UFOV2 = 0.07, p = 0.10). However, we found an age-related decline in performance on the third UFOV subtask (R2UFOV3 = 0.36, p < 0.001), which was unrelated to performance on the elementary visual function tasks. Our results show that performance on the first two UFOV subtasks as well as central elementary visual functions may remain high in the absence of obvious ophthalmological pathology.

[Outcome of cataract surgery in patients with pigmentary retinal degeneration].

PubMed

Grześk, Magdalena; Kałuzny, Józef; Malukiewicz-Wiśniewska, Grazyna

2007-01-01

To evaluate the results of cataract surgery in patients with RP because retinitis pigmentosa is one of the disease entities that belongs to tapeto-retinal degenerations. The occurrence of RP appearance is 1:4000 to 1:3000. Twenty patients with RP (7 women and 13 men, 33 eyes), who underwent cataract surgery were examined retrospectively. Average age in our group was 46.6 years. Visual acuity, intraocular pressure, slip lamp examination, fundus examination, cataract morphology, visual field were taken before surgery and on discharge, on the basis of medical documentation. Control examination was taken, on average, eighty one months after cataract surgery. Nine eyes were operated by phacoemulsification, 24 eyes by means of extracapsular cataract extraction. In the same way control group of 18 patients who underwent cataract surgery without RP (33 eyes) was examined. In RP group in 63.6% patients on discharge from the hospital and in 60.6% patients during the control examination, improvement of visual acuity was revealed. Deterioration was noted in 18.2% of patients on discharge from hospital and in 24.2% of patients during the control examination. In the control group improvement of visual acuity was revealed in 90.9% of patients on discharge and in 97% patients during the control examination, whereas deterioration of visual acuity occurred in 6.1% patients on discharge and in 3% patients during the check examination. In patients with retinitis pigmentosa cataract occurs earlier then in the control group. Cataract surgery for relatively minor opacities is beneficial in patients with RP, and causes improvement of visual acuity in most of eyes undergoing surgery.

Haltere mechanosensory influence on tethered flight behavior in Drosophila.

PubMed

Mureli, Shwetha; Fox, Jessica L

2015-08-01

In flies, mechanosensory information from modified hindwings known as halteres is combined with visual information for wing-steering behavior. Haltere input is necessary for free flight, making it difficult to study the effects of haltere ablation under natural flight conditions. We thus used tethered Drosophila melanogaster flies to examine the relationship between halteres and the visual system, using wide-field motion or moving figures as visual stimuli. Haltere input was altered by surgically decreasing its mass, or by removing it entirely. Haltere removal does not affect the flies' ability to flap or steer their wings, but it does increase the temporal frequency at which they modify their wingbeat amplitude. Reducing the haltere mass decreases the optomotor reflex response to wide-field motion, and removing the haltere entirely does not further decrease the response. Decreasing the mass does not attenuate the response to figure motion, but removing the entire haltere does attenuate the response. When flies are allowed to control a visual stimulus in closed-loop conditions, haltereless flies fixate figures with the same acuity as intact flies, but cannot stabilize a wide-field stimulus as accurately as intact flies can. These manipulations suggest that the haltere mass is influential in wide-field stabilization, but less so in figure tracking. In both figure and wide-field experiments, we observe responses to visual motion with and without halteres, indicating that during tethered flight, intact halteres are not strictly necessary for visually guided wing-steering responses. However, the haltere feedback loop may operate in a context-dependent way to modulate responses to visual motion. © 2015. Published by The Company of Biologists Ltd.

The influence of artificial scotomas on eye movements during visual search.

PubMed

Cornelissen, Frans W; Bruin, Klaas J; Kooijman, Aart C

2005-01-01

Fixation durations are normally adapted to the difficulty of the foveal analysis task. We examine to what extent artificial central and peripheral visual field defects interfere with this adaptation process. Subjects performed a visual search task while their eye movements were registered. The latter were used to drive a real-time gaze-dependent display that was used to create artificial central and peripheral visual field defects. Recorded eye movements were used to determine saccadic amplitude, number of fixations, fixation durations, return saccades, and changes in saccade direction. For central defects, although fixation duration increased with the size of the absolute central scotoma, this increase was too small to keep recognition performance optimal, evident from an associated increase in the rate of return saccades. Providing a relatively small amount of visual information in the central scotoma did substantially reduce subjects' search times but not their fixation durations. Surprisingly, reducing the size of the tunnel also prolonged fixation duration for peripheral defects. This manipulation also decreased the rate of return saccades, suggesting that the fixations were prolonged beyond the duration required by the foveal task. Although we find that adaptation of fixation duration to task difficulty clearly occurs in the presence of artificial scotomas, we also find that such field defects may render the adaptation suboptimal for the task at hand. Thus, visual field defects may not only hinder vision by limiting what the subject sees of the environment but also by limiting the visual system's ability to program efficient eye movements. We speculate this is because of how visual field defects bias the balance between saccade generation and fixation stabilization.

Emergence of Orientation Selectivity in the Mammalian Visual Pathway

PubMed Central

Scholl, Benjamin; Tan, Andrew Y. Y.; Corey, Joseph

2013-01-01

Orientation selectivity is a property of mammalian primary visual cortex (V1) neurons, yet its emergence along the visual pathway varies across species. In carnivores and primates, elongated receptive fields first appear in V1, whereas in lagomorphs such receptive fields emerge earlier, in the retina. Here we examine the mouse visual pathway and reveal the existence of orientation selectivity in lateral geniculate nucleus (LGN) relay cells. Cortical inactivation does not reduce this orientation selectivity, indicating that cortical feedback is not its source. Orientation selectivity is similar for LGN relay cells spiking and subthreshold input to V1 neurons, suggesting that cortical orientation selectivity is inherited from the LGN in mouse. In contrast, orientation selectivity of cat LGN relay cells is small relative to subthreshold inputs onto V1 simple cells. Together, these differences show that although orientation selectivity exists in visual neurons of both rodents and carnivores, its emergence along the visual pathway, and thus its underlying neuronal circuitry, is fundamentally different. PMID:23804085

Visual Field Map Clusters in High-Order Visual Processing: Organization of V3A/V3B and a New Cloverleaf Cluster in the Posterior Superior Temporal Sulcus

PubMed Central

Barton, Brian; Brewer, Alyssa A.

2017-01-01

The cortical hierarchy of the human visual system has been shown to be organized around retinal spatial coordinates throughout much of low- and mid-level visual processing. These regions contain visual field maps (VFMs) that each follows the organization of the retina, with neighboring aspects of the visual field processed in neighboring cortical locations. On a larger, macrostructural scale, groups of such sensory cortical field maps (CFMs) in both the visual and auditory systems are organized into roughly circular cloverleaf clusters. CFMs within clusters tend to share properties such as receptive field distribution, cortical magnification, and processing specialization. Here we use fMRI and population receptive field (pRF) modeling to investigate the extent of VFM and cluster organization with an examination of higher-level visual processing in temporal cortex and compare these measurements to mid-level visual processing in dorsal occipital cortex. In human temporal cortex, the posterior superior temporal sulcus (pSTS) has been implicated in various neuroimaging studies as subserving higher-order vision, including face processing, biological motion perception, and multimodal audiovisual integration. In human dorsal occipital cortex, the transverse occipital sulcus (TOS) contains the V3A/B cluster, which comprises two VFMs subserving mid-level motion perception and visuospatial attention. For the first time, we present the organization of VFMs in pSTS in a cloverleaf cluster. This pSTS cluster contains four VFMs bilaterally: pSTS-1:4. We characterize these pSTS VFMs as relatively small at ∼125 mm2 with relatively large pRF sizes of ∼2–8° of visual angle across the central 10° of the visual field. V3A and V3B are ∼230 mm2 in surface area, with pRF sizes here similarly ∼1–8° of visual angle across the same region. In addition, cortical magnification measurements show that a larger extent of the pSTS VFM surface areas are devoted to the peripheral visual field than those in the V3A/B cluster. Reliability measurements of VFMs in pSTS and V3A/B reveal that these cloverleaf clusters are remarkably consistent and functionally differentiable. Our findings add to the growing number of measurements of widespread sensory CFMs organized into cloverleaf clusters, indicating that CFMs and cloverleaf clusters may both be fundamental organizing principles in cortical sensory processing. PMID:28293182

Comparison of optical coherence tomography findings and visual field changes in patients with primary open-angle glaucoma and amyotrophic lateral sclerosis.

PubMed

Liu, Ziyuan; Wang, Hongli; Fan, Dongsheng; Wang, Wei

2018-02-01

Recent studies revealing genetic connection of primary open angle glaucoma (POAG) and amyotrophic lateral sclerosis (ALS) have received particular attention. Exploring the evidence for common pathogenesis of these two progressive neurological disorders may assist in understanding the mechanism and searching for new treatment. Retinal nerve fiber layer (RNFL) defect and corresponding visual field (VF) impairment are well known neuropathy signs in glaucoma. In our study, thickness of certain retinal layer in ALS patients was analyzed to detect ganglion cell's soma and axon, and for first time visual field was examined for ALS. The correlation of retinal involvement and ALS progression were also investigated. The results were compared with those of POAG. The study may provide new knowledge for these two neurodegenerative diseases. Copyright © 2017 Elsevier Ltd. All rights reserved.

[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.

Attentional Focus versus Diffuse Attention: Which is Better in Toddlers?

ERIC Educational Resources Information Center

Rivière, James; Cordonnier, Aurore; Fouasse, Christie

2017-01-01

How toddlers' attention is distributed in the visual field during a magic trick was examined using three expectation conditions. Results showed that 2.5-year-old children assigned to the condition with major task-relevant information (i.e., a verbal cue to attend to one of the visual targets) (i) outperformed those who were assigned to the…

The Vision of Children with Learning Difficulties: The Role of the Teacher and Psychologist.

ERIC Educational Resources Information Center

Willis, Marilyn A.

1981-01-01

The role of optometry in the study of learning difficulties and the problems of interpreting research results in the fields of optometry and ophthalmology are discussed. Limitations of school visual screening are described, and it is suggested that many children with learning difficulties should be referred for a full clinical visual examination.…

Linear utility corridors—a simulated visual field trip

Treesearch

Robert W. Ross Jr.

1979-01-01

With the increase in various utility corridors continuing to find their way across the American landscape, more and more people are becoming concerned about their ecological as well as visual impact. This paper examines "linear utility corridors" in terms of those that transport energy and those that transport fuels, their various components, and the types of...

Functional Dissociations within the Ventral Object Processing Pathway: Cognitive Modules or a Hierarchical Continuum?

ERIC Educational Resources Information Center

Cowell, Rosemary A.; Bussey, Timothy J.; Saksida, Lisa M.

2010-01-01

We examined the organization and function of the ventral object processing pathway. The prevailing theoretical approach in this field holds that the ventral object processing stream has a modular organization, in which visual perception is carried out in posterior regions and visual memory is carried out, independently, in the anterior temporal…

75 FR 72863 - Qualification of Drivers; Exemption Applications; Vision

Federal Register 2010, 2011, 2012, 2013, 2014

2010-11-26

..., has had complete loss of vision in his right eye due to a traumatic injury in 1964. The best corrected..., ``While Eugene has suffered traumatic blindness of his right eye his visual field examination and function... injury to his right eye since 1984. The best corrected visual acuity in his right eye is 20/60 and in his...

Preschool Teaching Staff's Opinions on the Importance of Preschool Curricular Fields of Activities, Art Genres and Visual Arts Fields

ERIC Educational Resources Information Center

Zupancic, Tomaž; Cagran, Branka; Mulej, Matjaž

2015-01-01

This article presents preschool teachers' and assistant teachers' opinions on the importance of selected fields of educational work in kindergartens. The article first highlights the importance of activities expressing artistic creativity within modern curriculums. Then, it presents an empirical study that examines the preschool teachers' and…

Eyelid drooping

MedlinePlus

... around or behind the eye Diabetes Horner syndrome Myasthenia gravis Stroke Swelling in the eyelid, such as with ... performed include: Slit-lamp examination Tension test for myasthenia gravis Visual field testing

45 CFR 233.70 - Blindness.

Code of Federal Regulations, 2010 CFR

2010-10-01

... visual acuity of 20/200 or less in the better eye with correcting glasses or a field defect in which the... diseases of the eye or by an optometrist, whichever the individual so selects. (i) No examination is necessary when both eyes are missing. (ii) Where an initial eye examination or re-examination is necessary...

45 CFR 233.70 - Blindness.

Code of Federal Regulations, 2011 CFR

2011-10-01

... visual acuity of 20/200 or less in the better eye with correcting glasses or a field defect in which the... diseases of the eye or by an optometrist, whichever the individual so selects. (i) No examination is necessary when both eyes are missing. (ii) Where an initial eye examination or re-examination is necessary...

Flow Visualization Techniques in Wind Tunnel Tests of a Full-Scale F/A-18 Aircraft

NASA Technical Reports Server (NTRS)

Lanser, Wendy R.; Botha, Gavin J.; James, Kevin D.; Bennett, Mark; Crowder, James P.; Cooper, Don; Olson, Lawrence (Technical Monitor)

1994-01-01

The proposed paper presents flow visualization performed during experiments conducted on a full-scale F/A-18 aircraft in the 80- by 120-Foot Wind-Tunnel at NASA Ames Research Center. The purpose of the flow-visualization experiments was to document the forebody and leading edge extension (LEX) vortex interaction along with the wing flow patterns at high angles of attack and low speed high Reynolds number conditions. This investigation used surface pressures in addition to both surface and off-surface flow visualization techniques to examine the flow field on the forebody, canopy, LEXS, and wings. The various techniques used to visualize the flow field were fluorescent tufts, flow cones treated with reflective material, smoke in combination with a laser light sheet, and a video imaging system for three-dimension vortex tracking. The flow visualization experiments were conducted over an angle of attack range from 20 deg to 45 deg and over a sideslip range from -10 deg to 10 deg. The various visualization techniques as well as the pressure distributions were used to understand the flow field structure. The results show regions of attached and separated flow on the forebody, canopy, and wings as well as the vortical flow over the leading-edge extensions. This paper will also present flow visualization comparisons with the F-18 HARV flight vehicle and small-scale oil flows on the F-18.

Visual functions of commercial drivers in relation to road accidents in Nigeria

PubMed Central

Oladehinde, M. K.; Adeoye, A. O.; Adegbehingbe, B. O.; Onakoya, A. O.

2007-01-01

Objective: To determine the effects of the visual functions on the occurrence of road traffic accidents (RTA) amongst commercial drivers in Ife central local government area (LGA) of Osun state of Nigeria. Design: A cross-sectional study. Settings: Four major motor parks located at Ife Central LGA. Materials and Methods: Of the estimated 270 commercial drivers in the four major parks of the LGA, 215 consecutive drivers were interviewed and had their eyes examined. Structured questionnaires were administered by an ophthalmologist. Results: The prevalence of visual impairment (visual acuity < 6/18) in the better eye without correction was 3.3% ± 2.4 and there was a significant association between uncorrected visual acuity impairment in the better eye and RTA (P = 0.0152). Refractive error was seen in 8.4% of the drivers, but none of these wear corrective glasses. Visual field defect, abnormal stereopsis and color vision impairment did not have any significant association with RTA. Conclusion: Poor visual acuity is strongly associated with RTA amongst Nigerian commercial drivers as opposed to visual field defect, abnormal color vision and stereopsis. A significant proportion of visual impairment was due to uncorrected refractive errors. PMID:21938219

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

PubMed

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

2018-03-11

Objective: To analyze potentials of frequency-doubling technology perimetry (FDP) for diagnosing open-angle glaucoma (OAG) in perimetrically normal eyes of OAG patients diagnosed with standard automated perimetry (SAP) and relating factors from abnormalities on FDP to visual field loss on SAP. Methods: A prospective cohort study. Sixty-eight eyes of 68 OAG patients visiting the ophthalmic clinic of Peking University Third Hospital during November 2003 and October 2007 [32 primary open-angle glaucoma patients and 36 normal tension glaucoma patients, 32 males and 36 females, with an average age of (59±13) years] with unilateral field loss detected by SAP (Octopus101 tG2 program) were examined with the FDP N-30 threshold program (Humphrey Instruments) at baseline. Two groups, FDP positive group and FDP negative group, were divided based on the FDP results, and visual field examinations were followed by a series of SAP examinations for the perimetrically normal eyes over 8 years. During the follow-up, the difference of the converting rate of SAP tests between the two groups was analyzed. Differences between "convertors" and "non-convertors" of SAP tests in the FDP positive group, such as the cup-to-disk ratio and glaucomatous optic neuropathy rate, were also compared with the independent-sample t test or Wilcoxon two-sample test for continuous variable data and the χ(2) test or Fisher exact test for classified variable data and rates. Results: Forty-eight perimetrically normal eyes of 48 participants had complete data and a qualifying follow-up. Baseline FDP results were positive in 33 eyes and negative in 15 eyes. Of the eyes with positive FDP results, 22 eyes developed abnormal SAP results after 4.0 to 90.0 months (median 14.5 months) , whereas none of the eyes with negative FDP results developed abnormal SAP results. For perimetrically normal eyes in the FDP positive group, "converters" showed a greater cup-to-disk ratio (0.73±0.09 vs . 0.63±0.14, Wilcoxon two-sample test, P= 0.011) and more eyes with glaucomatous optic neuropathy (19/22 vs . 4/11, Fisher exact test, P= 0.006). Conclusions: In perimetrically normal eyes of OAG patients, FDP could detect visual field loss of these eyes and predict to some extent future visual field loss on SAP. Severity of glaucomatous optic neuropathy at baseline is related to converting from abnormalities on FDP to visual field loss on SAP. (Chin J Ophthalmol, 2018, 54: 177-183) .

New approach to estimating variability in visual field data using an image processing technique.

PubMed Central

Crabb, D P; Edgar, D F; Fitzke, F W; McNaught, A I; Wynn, H P

1995-01-01

AIMS--A new framework for evaluating pointwise sensitivity variation in computerised visual field data is demonstrated. METHODS--A measure of local spatial variability (LSV) is generated using an image processing technique. Fifty five eyes from a sample of normal and glaucomatous subjects, examined on the Humphrey field analyser (HFA), were used to illustrate the method. RESULTS--Significant correlation between LSV and conventional estimates--namely, HFA pattern standard deviation and short term fluctuation, were found. CONCLUSION--LSV is not dependent on normals' reference data or repeated threshold determinations, thus potentially reducing test time. Also, the illustrated pointwise maps of LSV could provide a method for identifying areas of fluctuation commonly found in early glaucomatous field loss. PMID:7703196

The Advanced Glaucoma Intervention Study (AGIS): 7. The relationship between control of intraocular pressure and visual field deterioration.The AGIS Investigators.

PubMed

2000-10-01

To investigate the association between control of intraocular pressure after surgical intervention for glaucoma and visual field deterioration. In the Advanced Glaucoma Intervention Study, eyes were randomly assigned to one of two sequences of glaucoma surgery, one beginning with argon laser trabeculoplasty and the other trabeculectomy. In the present article we examine the relationship between intraocular pressure and progression of visual field damage over 6 or more years of follow-up. In the first analysis, designated Predictive Analysis, we categorize 738 eyes into three groups based on intraocular pressure determinations over the first three 6-month follow-up visits. In the second analysis, designated Associative Analysis, we categorize 586 eyes into four groups based on the percent of 6-month visits over the first 6 follow-up years in which eyes presented with intraocular pressure less than 18 mm Hg. The outcome measure in both analyses is change from baseline in follow-up visual field defect score (range, 0 to 20 units). In the Predictive Analysis, eyes with early average intraocular pressure greater than 17.5 mm Hg had an estimated worsening during subsequent follow-up that was 1 unit of visual field defect score greater than eyes with average intraocular pressure less than 14 mm Hg (P =.002). This amount of worsening was greater at 7 years (1.89 units; P <.001) than at 2 years (0.64 units; P =.071). In the Associative Analysis, eyes with 100% of visits with intraocular pressure less than 18 mm Hg over 6 years had mean changes from baseline in visual field defect score close to zero during follow-up, whereas eyes with less than 50% of visits with intraocular pressure less than 18 mm Hg had an estimated worsening over follow-up of 0.63 units of visual field defect score (P =.083). This amount of worsening was greater at 7 years (1.93 units; P <.001) than at 2 years (0.25 units; P =.572). In both analyses low intraocular pressure is associated with reduced progression of visual field defect, supporting evidence from earlier studies of a protective role for low intraocular pressure in visual field deterioration.

The effect of acute sleep deprivation on visual evoked potentials in professional drivers.

PubMed

Jackson, Melinda L; Croft, Rodney J; Owens, Katherine; Pierce, Robert J; Kennedy, Gerard A; Crewther, David; Howard, Mark E

2008-09-01

Previous studies have demonstrated that as little as 18 hours of sleep deprivation can cause deleterious effects on performance. It has also been suggested that sleep deprivation can cause a "tunnel-vision" effect, in which attention is restricted to the center of the visual field. The current study aimed to replicate these behavioral effects and to examine the electrophysiological underpinnings of these changes. Repeated-measures experimental study. University laboratory. Nineteen professional drivers (1 woman; mean age = 45.3 +/- 9.1 years). Two experimental sessions were performed; one following 27 hours of sleep deprivation and the other following a normal night of sleep, with control for circadian effects. A tunnel-vision task (central versus peripheral visual discrimination) and a standard checkerboard-viewing task were performed while 32-channel EEG was recorded. For the tunnel-vision task, sleep deprivation resulted in an overall slowing of reaction times and increased errors of omission for both peripheral and foveal stimuli (P < 0.05). These changes were related to reduced P300 amplitude (indexing cognitive processing) but not measures of early visual processing. No evidence was found for an interaction effect between sleep deprivation and visual-field position, either in terms of behavior or electrophysiological responses. Slower processing of the sustained parvocellular visual pathway was demonstrated. These findings suggest that performance deficits on visual tasks during sleep deprivation are due to higher cognitive processes rather than early visual processing. Sleep deprivation may differentially impair processing of more-detailed visual information. Features of the study design (eg, visual angle, duration of sleep deprivation) may influence whether peripheral visual-field neglect occurs.

Category Membership and Semantic Coding in the Cerebral Hemispheres.

PubMed

Turner, Casey E; Kellogg, Ronald T

2016-01-01

Although a gradient of category membership seems to form the internal structure of semantic categories, it is unclear whether the 2 hemispheres of the brain differ in terms of this gradient. The 2 experiments reported here examined this empirical question and explored alternative theoretical interpretations. Participants viewed category names centrally and determined whether a closely related or distantly related word presented to either the left visual field/right hemisphere (LVF/RH) or the right visual field/left hemisphere (RVF/LH) was a member of the category. Distantly related words were categorized more slowly in the LVF/RH relative to the RVF/LH, with no difference for words close to the prototype. The finding resolved past mixed results showing an unambiguous typicality effect for both visual field presentations. Furthermore, we examined items near the fuzzy border that were sometimes rejected as nonmembers of the category and found both hemispheres use the same category boundary. In Experiment 2, we presented 2 target words to be categorized, with the expectation of augmenting the speed advantage for the RVF/LH if the 2 hemispheres differ structurally. Instead the results showed a weakening of the hemispheric difference, arguing against a structural in favor of a processing explanation.

The effect of response mode on lateralized lexical decision performance.

PubMed

Weems, Scott A; Zaidel, Eran

2005-01-01

We examined the effect of manipulations of response programming, i.e. post-lexical decision making requirements, on lateralized lexical decision. Although response hand manipulations tend to elicit weaker laterality effects than those involving visual field of presentation, the implementation of different lateralized response strategies remains relatively unexplored. Four different response conditions were compared in a between-subjects design: (1) unimanual, (2) bimanual, (3) congruent visual field/response hand, and (4) confounded response hand/target lexicality response. It was observed that hemispheric specialization and interaction effects during the lexical decision task remained unchanged despite the very different response requirements. However, a priori examination of each condition revealed that some manipulations yielded a reduced power to detect laterality effects. The consistent observation of left hemisphere specialization, and both left and right hemisphere lexicality priming effects (interhemispheric transfer), indicate that these effects are relatively robust and unaffected by late occurring processes in the lexical decision task. It appears that the lateralized response mode neither determines nor reflects the laterality of decision processes. In contrast, the target visual half-field is critical for determining the deciding hemisphere and is a sensitive index of hemispheric specialization, as well as of directional interhemispheric transfer.

Automated objective characterization of visual field defects in 3D

NASA Technical Reports Server (NTRS)

Fink, Wolfgang (Inventor)

2006-01-01

A method and apparatus for electronically performing a visual field test for a patient. A visual field test pattern is displayed to the patient on an electronic display device and the patient's responses to the visual field test pattern are recorded. A visual field representation is generated from the patient's responses. The visual field representation is then used as an input into a variety of automated diagnostic processes. In one process, the visual field representation is used to generate a statistical description of the rapidity of change of a patient's visual field at the boundary of a visual field defect. In another process, the area of a visual field defect is calculated using the visual field representation. In another process, the visual field representation is used to generate a statistical description of the volume of a patient's visual field defect.

Rate of progression of total, upper, and lower visual field defects in patients with open-angle glaucoma and high myopia.

PubMed

Yoshino, Takaiko; Fukuchi, Takeo; Togano, Tetsuya; Sakaue, Yuta; Seki, Masaaki; Tanaka, Takayuki; Ueda, Jun

2016-03-01

We evaluated the rate of progression of total, upper, and lower visual field defects in patients with treated primary open-angle glaucoma (POAG) with high myopia (HM). Seventy eyes of 70 POAG patients with HM [≤-8 diopters (D)] were examined. The mean deviation (MD) slope and the upper and lower total deviation (upper TD, lower TD) slopes of the Humphrey Field Analyzer were calculated in patients with high-tension glaucoma (HTG) (>21 mmHg) versus normal-tension glaucoma (NTG) (≤21 mmHg). The mean age of all the patients (29 eyes with HTG and 41 eyes with NTG) was 48.5 ± 9.6 years. The MD slope, and upper and lower TD slopes of the HM group were compared to those of the non-HM group (NHM) (>-8 D) selected from 544 eyes in 325 age-matched POAG patients. In all, 70 eyes with HM and NHM were examined. The mean MD slope was -0.33 ± 0.33 dB/year in the HM, and -0.38 ± 0.49 dB/year in the NHM. There were no statistical differences between the HM and NHM (p = 0.9565). In the comparison of HTG versus NTG patients in both groups, the MD slope, and upper and lower TD slopes were similar. The rate of progression of total, upper, and lower visual field defects was similar among patients with HM and NHM. Although HM is a risk factor for the onset of glaucoma, HM may not be a risk factor for progression of visual field defects as assessed by the progression rate under treatment.

Diagnosing cerebral visual impairment in children with good visual acuity.

PubMed

van Genderen, Maria; Dekker, Marjoke; Pilon, Florine; Bals, Irmgard

2012-06-01

To identify elements that could facilitate the diagnosis of cerebral visual impairment (CVI) in children with good visual acuity in the general ophthalmic clinic. We retrospectively investigated the clinical characteristics of 30 children with good visual acuity and CVI and compared them with those of 23 children who were referred with a suspicion of CVI, but proved to have a different diagnosis. Clinical characteristics included medical history, MRI findings, visual acuity, crowding ratio (CR), visual field assessment, and the results of ophthalmologic and orthoptic examination. We also evaluated the additional value of a short CVI questionnaire. Eighty-three percent of the children with an abnormal medical history (mainly prematurity and perinatal hypoxia) had CVI, in contrast with none of the children with a normal medical history. Cerebral palsy, visual field defects, and partial optic atrophy only occurred in the CVI group. 41% of the children with CVI had a CR ≥2.0, which may be related to dorsal stream dysfunction. All children with CVI, but also 91% of the children without CVI gave ≥3 affirmative answers on the CVI questionnaire. An abnormal pre- or perinatal medical history is the most important risk factor for CVI in children, and therefore in deciding which children should be referred for further multidisciplinary assessment. Additional symptoms of cerebral damage, i.e., cerebral palsy, visual field defects, partial optic atrophy, and a CR ≥2 may support the diagnosis. CVI questionnaires should not be used for screening purposes as they yield too many false positives.

Lack of Multisensory Integration in Hemianopia: No Influence of Visual Stimuli on Aurally Guided Saccades to the Blind Hemifield

PubMed Central

Ten Brink, Antonia F.; Nijboer, Tanja C. W.; Bergsma, Douwe P.; Barton, Jason J. S.; Van der Stigchel, Stefan

2015-01-01

In patients with visual hemifield defects residual visual functions may be present, a phenomenon called blindsight. The superior colliculus (SC) is part of the spared pathway that is considered to be responsible for this phenomenon. Given that the SC processes input from different modalities and is involved in the programming of saccadic eye movements, the aim of the present study was to examine whether multimodal integration can modulate oculomotor competition in the damaged hemifield. We conducted two experiments with eight patients who had visual field defects due to lesions that affected the retinogeniculate pathway but spared the retinotectal direct SC pathway. They had to make saccades to an auditory target that was presented alone or in combination with a visual stimulus. The visual stimulus could either be spatially coincident with the auditory target (possibly enhancing the auditory target signal), or spatially disparate to the auditory target (possibly competing with the auditory tar-get signal). For each patient we compared the saccade endpoint deviation in these two bi-modal conditions with the endpoint deviation in the unimodal condition (auditory target alone). In all seven hemianopic patients, saccade accuracy was affected only by visual stimuli in the intact, but not in the blind visual field. In one patient with a more limited quadrantano-pia, a facilitation effect of the spatially coincident visual stimulus was observed. We conclude that our results show that multisensory integration is infrequent in the blind field of patients with hemianopia. PMID:25835952

Scene and human face recognition in the central vision of patients with glaucoma

PubMed Central

Aptel, Florent; Attye, Arnaud; Guyader, Nathalie; Boucart, Muriel; Chiquet, Christophe; Peyrin, Carole

2018-01-01

Primary open-angle glaucoma (POAG) firstly mainly affects peripheral vision. Current behavioral studies support the idea that visual defects of patients with POAG extend into parts of the central visual field classified as normal by static automated perimetry analysis. This is particularly true for visual tasks involving processes of a higher level than mere detection. The purpose of this study was to assess visual abilities of POAG patients in central vision. Patients were assigned to two groups following a visual field examination (Humphrey 24–2 SITA-Standard test). Patients with both peripheral and central defects and patients with peripheral but no central defect, as well as age-matched controls, participated in the experiment. All participants had to perform two visual tasks where low-contrast stimuli were presented in the central 6° of the visual field. A categorization task of scene images and human face images assessed high-level visual recognition abilities. In contrast, a detection task using the same stimuli assessed low-level visual function. The difference in performance between detection and categorization revealed the cost of high-level visual processing. Compared to controls, patients with a central visual defect showed a deficit in both detection and categorization of all low-contrast images. This is consistent with the abnormal retinal sensitivity as assessed by perimetry. However, the deficit was greater for categorization than detection. Patients without a central defect showed similar performances to the controls concerning the detection and categorization of faces. However, while the detection of scene images was well-maintained, these patients showed a deficit in their categorization. This suggests that the simple loss of peripheral vision could be detrimental to scene recognition, even when the information is displayed in central vision. This study revealed subtle defects in the central visual field of POAG patients that cannot be predicted by static automated perimetry assessment using Humphrey 24–2 SITA-Standard test. PMID:29481572

Visual field defects after temporal lobe resection for epilepsy.

PubMed

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

2018-01-01

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

The Nigerian national blindness and visual impairment survey: Rationale, objectives and detailed methodology

PubMed Central

Dineen, Brendan; Gilbert, Clare E; Rabiu, Mansur; Kyari, Fatima; Mahdi, Abdull M; Abubakar, Tafida; Ezelum, Christian C; Gabriel, Entekume; Elhassan , Elizabeth; Abiose, Adenike; Faal, Hannah; Jiya, Jonathan Y; Ozemela, Chinenyem P; Lee, Pak Sang; Gudlavalleti, Murthy VS

2008-01-01

Background Despite having the largest population in Africa, Nigeria has no accurate population based data to plan and evaluate eye care services. A national survey was undertaken to estimate the prevalence and determine the major causes of blindness and low vision. This paper presents the detailed methodology used during the survey. Methods A nationally representative sample of persons aged 40 years and above was selected. Children aged 10–15 years and individuals aged <10 or 16–39 years with visual impairment were also included if they lived in households with an eligible adult. All participants had their height, weight, and blood pressure measured followed by assessment of presenting visual acuity, refractokeratomery, A-scan ultrasonography, visual fields and best corrected visual acuity. Anterior and posterior segments of each eye were examined with a torch and direct ophthalmoscope. Participants with visual acuity of < = 6/12 in one or both eyes underwent detailed examination including applanation tonometry, dilated slit lamp biomicroscopy, lens grading and fundus photography. All those who had undergone cataract surgery were refracted and best corrected vision recorded. Causes of visual impairment by eye and for the individual were determined using a clinical algorithm recommended by the World Health Organization. In addition, 1 in 7 adults also underwent a complete work up as described for those with vision < = 6/12 for constructing a normative data base for Nigerians. Discussion The field work for the study was completed in 30 months over the period 2005–2007 and covered 305 clusters across the entire country. Concurrently persons 40+ years were examined to form a normative data base. Analysis of the data is currently underway. Conclusion The methodology used was robust and adequate to provide estimates on the prevalence and causes of blindness in Nigeria. The survey would also provide information on barriers to accessing services, quality of life of visually impaired individuals and also provide normative data for Nigerian eyes. PMID:18808712

The Impact of Feedback on Self-Rated Driving Ability and Driving Self-Regulation among Older Adults

ERIC Educational Resources Information Center

Ackerman, Michelle L.; Crowe, Michael; Vance, David E.; Wadley, Virginia G.; Owsley, Cynthia; Ball, Karlene K.

2011-01-01

In 129 community-dwelling older adults, feedback regarding qualification for an insurance discount (based on a visual speed of processing test; Useful Field of View) was examined as a prospective predictor of change in self-reported driving ability, driving avoidance, and driving exposure over 3 months, along with physical, visual, health, and…

Caffeine Improves Left Hemisphere Processing of Positive Words

PubMed Central

Kuchinke, Lars; Lux, Vanessa

2012-01-01

A positivity advantage is known in emotional word recognition in that positive words are consistently processed faster and with fewer errors compared to emotionally neutral words. A similar advantage is not evident for negative words. Results of divided visual field studies, where stimuli are presented in either the left or right visual field and are initially processed by the contra-lateral brain hemisphere, point to a specificity of the language-dominant left hemisphere. The present study examined this effect by showing that the intake of caffeine further enhanced the recognition performance of positive, but not negative or neutral stimuli compared to a placebo control group. Because this effect was only present in the right visual field/left hemisphere condition, and based on the close link between caffeine intake and dopaminergic transmission, this result points to a dopaminergic explanation of the positivity advantage in emotional word recognition. PMID:23144893

Examining Lateralized Semantic Access Using Pictures

ERIC Educational Resources Information Center

Lovseth, Kyle; Atchley, Ruth Ann

2010-01-01

A divided visual field (DVF) experiment examined the semantic processing strategies employed by the cerebral hemispheres to determine if strategies observed with written word stimuli generalize to other media for communicating semantic information. We employed picture stimuli and vary the degree of semantic relatedness between the picture pairs.…

Phenotypes in defined genotypes including siblings with Usher syndrome.

PubMed

Malm, Eva; Ponjavic, Vesna; Möller, Claes; Kimberling, William J; Andréasson, Sten

2011-06-01

To characterize visual function in defined genotypes including siblings with Usher syndrome. Thirteen patients with phenotypically different subtypes of Usher syndrome, including 3 families with affected siblings, were selected. Genetic analysis and ophthalmological examinations including visual fields, full-field electroretinography (ERG), multifocal electroretinography (mf ERG), and optical coherence tomography (OCT) were assessed. The patients' degree of visual handicap was evaluated by a questionnaire (ADL). Twelve of thirteen patients were genotyped as Usher 1B, 1D, 1F, 2A, 2C or 3A. In 12 of 13 patients examined with ERG the 30 Hz flickering light response revealed remaining cone function. In 3 of the patients with Usher type 1 mf ERG demonstrated a specific pattern, with a sharp distinction between the area with reduced function and the central area with remaining macular function and normal peak time. OCT demonstrated loss of foveal depression with distortion of the foveal architecture in the macula in all patients. The foveal thickness ranged from 159 to 384 µm and was not correlated to retinal function. Three siblings shared the same mutation for Usher 2C but in contrast to previous reports regarding this genotype, 1 of them diverged in phenotype with substantially normal visual fields, almost normal OCT and mf ERG findings, and only moderately reduced rod and cone function according to ERG. Evaluation of visual function comprising both the severity of the rod cone degeneration and the function in the macular region confirm phenotypical heterogeneity within siblings and between different genotypes of Usher syndrome.

Colour vision and light sensitivity in tunnel workers previously exposed to acrylamide and N-methylolacrylamide containing grouting agents.

PubMed

Goffeng, Lars Ole; Kjuus, Helge; Heier, Mona Skard; Alvestrand, Monica; Ulvestad, Bente; Skaug, Vidar

2008-01-01

The aim of the study was to examine possible persisting visual system effects in tunnel workers previously exposed to acrylamide and N-methylolacrylamide during grouting work. Visual field light sensitivity threshold and colour vision has been examined among 44 tunnel workers 2-10 years after exposure to acrylamide and N-methylolacrylamide containing grouting agents. Forty-four tunnel workers not involved in grouting operations served as control group. Information on exposure and background variables was obtained for all participants from a questionnaire. Visual light sensitivity threshold was measured using Humphrey Visual Field Static Perimeter 740, program 30-2 Fastpack, with red stimuli on white background, and colour vision, using Lanthony D-15 Desaturated Color test. Based on D-15d test results, colour confusion index (CCI), and a severity index (C-index) was calculated. The exposed group had a significantly higher threshold for detecting single stimuli in all parts of the inner 30 degrees of the visual field compared to the control group. The foveal threshold group difference was 1.4 dB (p=0.002) (mean value, both eyes). On the Lanthony 15 Hue Desaturated test, the exposed subjects made more errors in sorting blue colours, and a statistically significant increase in C-index was observed. Surrogate measures for duration and intensity of exposure gave no further improvement of the model. The results indicate slightly reduced light sensitivity and reduced colour discrimination among the exposed subjects compared to the controls. The findings may be due to previous exposure to acrylamide containing grouts among the tunnel workers.

Investigating accidents involving aircraft manufactured from polymer composite materials

NASA Astrophysics Data System (ADS)

Dunn, Leigh

This study looks into the examination of polymer composite wreckage from the perspective of the aircraft accident investigator. It develops an understanding of the process of wreckage examination as well as identifying the potential for visual and macroscopic interpretation of polymer composite aircraft wreckage. The in-field examination of aircraft wreckage, and subsequent interpretations of material failures, can be a significant part of an aircraft accident investigation. As the use of composite materials in aircraft construction increases, the understanding of how macroscopic failure characteristics of composite materials may aid the field investigator is becoming of increasing importance.. The first phase of this research project was to explore how investigation practitioners conduct wreckage examinations. Four accident investigation case studies were examined. The analysis of the case studies provided a framework of the wreckage examination process. Subsequently, a literature survey was conducted to establish the current level of knowledge on the visual and macroscopic interpretation of polymer composite failures. Relevant literature was identified and a compendium of visual and macroscopic characteristics was created. Two full-scale polymer composite wing structures were loaded statically, in an upward bending direction, until each wing structure fractured and separated. The wing structures were subsequently examined for the existence of failure characteristics. The examination revealed that whilst characteristics were present, the fragmentation of the structure destroyed valuable evidence. A hypothetical accident scenario utilising the fractured wing structures was developed, which UK government accident investigators subsequently investigated. This provided refinement to the investigative framework and suggested further guidance on the interpretation of polymer composite failures by accident investigators..

Blur adaptation: contrast sensitivity changes and stimulus extent.

PubMed

Venkataraman, Abinaya Priya; Winter, Simon; Unsbo, Peter; Lundström, Linda

2015-05-01

A prolonged exposure to foveal defocus is well known to affect the visual functions in the fovea. However, the effects of peripheral blur adaptation on foveal vision, or vice versa, are still unclear. In this study, we therefore examined the changes in contrast sensitivity function from baseline, following blur adaptation to small as well as laterally extended stimuli in four subjects. The small field stimulus (7.5° visual field) was a 30min video of forest scenery projected on a screen and the large field stimulus consisted of 7-tiles of the 7.5° stimulus stacked horizontally. Both stimuli were used for adaptation with optical blur (+2.00D trial lens) as well as for clear control conditions. After small field blur adaptation foveal contrast sensitivity improved in the mid spatial frequency region. However, these changes neither spread to the periphery nor occurred for the large field blur adaptation. To conclude, visual performance after adaptation is dependent on the lateral extent of the adaptation stimulus. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Ocular findings in MELAS syndrome – a case report.

PubMed

Modrzejewska, Monika; Chrzanowska, Martyna; Modrzejewska, Anna; Romanowska, Hanna; Ostrowska, Iwona; Giżewska, Maria

We present a case of a child with MELAS syndrome (mitochondrial encephalo-myopathy with lactic acidosis and stroke-like episodes), discussing clinical manifestation, ocular findings and diagnostic challenges. Predominant ocular symptom was a transient complete visual loss, while the predominant ocular sign was a visual field defect. The diagnosia was based on clinical manifestation, laboratory tests, brain scans and genetic testing which confirmed the pathognomonic mutation in the MTTL1 gene encoding the mitochondrial tRNA for leucine 3243> G. Ocular examination demonstrated decreased visual acuity (with bilateral best corrected visual acuity of .1). Periodical, transient visual loss and visual field defects were clinically predominant. Specialist investigations were carried out, which demonstrated homonymous hemianopia (kinetic perimetry), bilateral partial optic nerve atrophy (RetCam). Funduscopy and electrophysiology mfERG study did not confirm features of retinitis pigmentosa. The brain scans revealed numerous small cortical ischemic lesions within the frontal, parietal and temporal lobes, post-stroke focal areas within the occipital lobes and diffuse calcifications of the basal ganglia. During several years of follow-up, visual field defects showed progressive concentric narrowing. The patient received a long-term treatment with arginine, coenzyme Q and vitamin D, both oral and intravenous, but no beneficial effect for the improvement of ophthalmic condition was observed. As it is the case in severe MELAS syndrome, the course of disease was fatal and the patientdied at the age of 14.

Visual Outcomes in Japanese Patients with Retinitis Pigmentosa and Usher Syndrome Caused by USH2A Mutations.

PubMed

Nagase, Yasunori; Kurata, Kentaro; Hosono, Katsuhiro; Suto, Kimiko; Hikoya, Akiko; Nakanishi, Hiroshi; Mizuta, Kunihiro; Mineta, Hiroyuki; Minoshima, Shinsei; Hotta, Yoshihiro

2017-07-05

EYS and USH2A are the most common causative genes for retinitis pigmentosa (RP) in Japan. We determined the clinical outcomes for USH2A-related non-syndromic RP or Usher syndrome type II (USH2). Two non-syndromic RP and 11 USH2 patients with previously identified USH2A mutations were included. Their complete history and medical records were collected using standard procedures. Visual fields and acuity were compared with those of patients with EYS mutations. Clinical analyses were based on ophthalmic and otolaryngologic examinations. In all patients, the fundus displayed changes typical of RP. Most patients showed relatively well-preserved visual acuity in their thirties or forties, with rapid deterioration in their fifties. Concentric constriction started in the twenties or thirties, and no effective residual visual field was observed after the fifties. The visual outcome for non-syndromic RP or USH2 patients with USH2A mutations is consistent with that for RP patients with EYS mutations.

The retest distribution of the visual field summary index mean deviation is close to normal.

PubMed

Anderson, Andrew J; Cheng, Allan C Y; Lau, Samantha; Le-Pham, Anne; Liu, Victor; Rahman, Farahnaz

2016-09-01

When modelling optimum strategies for how best to determine visual field progression in glaucoma, it is commonly assumed that the summary index mean deviation (MD) is normally distributed on repeated testing. Here we tested whether this assumption is correct. We obtained 42 reliable 24-2 Humphrey Field Analyzer SITA standard visual fields from one eye of each of five healthy young observers, with the first two fields excluded from analysis. Previous work has shown that although MD variability is higher in glaucoma, the shape of the MD distribution is similar to that found in normal visual fields. A Shapiro-Wilks test determined any deviation from normality. Kurtosis values for the distributions were also calculated. Data from each observer passed the Shapiro-Wilks normality test. Bootstrapped 95% confidence intervals for kurtosis encompassed the value for a normal distribution in four of five observers. When examined with quantile-quantile plots, distributions were close to normal and showed no consistent deviations across observers. The retest distribution of MD is not significantly different from normal in healthy observers, and so is likely also normally distributed - or nearly so - in those with glaucoma. Our results increase our confidence in the results of influential modelling studies where a normal distribution for MD was assumed. © 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.

Visual field progression with frequency-doubling matrix perimetry and standard automated perimetry in patients with glaucoma and in healthy controls.

PubMed

Redmond, Tony; O'Leary, Neil; Hutchison, Donna M; Nicolela, Marcelo T; Artes, Paul H; Chauhan, Balwantray C

2013-12-01

A new analysis method called permutation of pointwise linear regression measures the significance of deterioration over time at each visual field location, combines the significance values into an overall statistic, and then determines the likelihood of change in the visual field. Because the outcome is a single P value, individualized to that specific visual field and independent of the scale of the original measurement, the method is well suited for comparing techniques with different stimuli and scales. To test the hypothesis that frequency-doubling matrix perimetry (FDT2) is more sensitive than standard automated perimetry (SAP) in identifying visual field progression in glaucoma. Patients with open-angle glaucoma and healthy controls were examined by FDT2 and SAP, both with the 24-2 test pattern, on the same day at 6-month intervals in a longitudinal prospective study conducted in a hospital-based setting. Only participants with at least 5 examinations were included. Data were analyzed with permutation of pointwise linear regression. Permutation of pointwise linear regression is individualized to each participant, in contrast to current analyses in which the statistical significance is inferred from population-based approaches. Analyses were performed with both total deviation and pattern deviation. Sixty-four patients and 36 controls were included in the study. The median age, SAP mean deviation, and follow-up period were 65 years, -2.6 dB, and 5.4 years, respectively, in patients and 62 years, +0.4 dB, and 5.2 years, respectively, in controls. Using total deviation analyses, statistically significant deterioration was identified in 17% of patients with FDT2, in 34% of patients with SAP, and in 14% of patients with both techniques; in controls these percentages were 8% with FDT2, 31% with SAP, and 8% with both. Using pattern deviation analyses, statistically significant deterioration was identified in 16% of patients with FDT2, in 17% of patients with SAP, and in 3% of patients with both techniques; in controls these values were 3% with FDT2 and none with SAP. No evidence was found that FDT2 is more sensitive than SAP in identifying visual field deterioration. In about one-third of healthy controls, age-related deterioration with SAP reached statistical significance.

Association of visual sensory function and higher order visual processing skills with incident driving cessation

PubMed Central

Huisingh, Carrie; McGwin, Gerald; Owsley, Cynthia

2017-01-01

Background Many studies on vision and driving cessation have relied on measures of sensory function, which are insensitive to the higher order cognitive aspects of visual processing. The purpose of this study was to examine the association between traditional measures of visual sensory function and higher order visual processing skills with incident driving cessation in a population-based sample of older drivers. Methods Two thousand licensed drivers aged ≥70 were enrolled and followed-up for three years. Tests for central vision and visual processing were administered at baseline and included visual acuity, contrast sensitivity, sensitivity in the driving visual field, visual processing speed (Useful Field of View (UFOV) Subtest 2 and Trails B), and spatial ability measured by the Visual Closure Subtest of the Motor-free Visual Perception Test. Participants self-reported the month and year of driving cessation and provided a reason for cessation. Cox proportional hazards models were used to generate crude and adjusted hazard ratios with 95% confidence intervals between visual functioning characteristics and risk of driving cessation over a three-year period. Results During the study period, 164 participants stopped driving which corresponds to a cumulative incidence of 8.5%. Impaired contrast sensitivity, visual fields, visual processing speed (UFOVand Trails B), and spatial ability were significant risk factors for subsequent driving cessation after adjusting for age, gender, marital status, number of medical conditions, and miles driven. Visual acuity impairment was not associated with driving cessation. Medical problems (63%), specifically musculoskeletal and neurological problems, as well as vision problems (17%) were cited most frequently as the reason for driving cessation. Conclusion Assessment of cognitive and visual functioning can provide useful information about subsequent risk of driving cessation among older drivers. In addition, a variety of factors, not just vision, influenced the decision to stop driving and may be amenable to intervention. PMID:27353969

Binasal hemianopia.

PubMed

Salinas-Garcia, R F; Smith, J L

1978-09-01

The visual fields of 100 patients referred for neuro-ophthalmologic examination were reviewed; eight cases had binasal visual field defects. Most clinicians have suspected an intracranial cause for such field defects since the classic report of Cushing and Walker in 1912. However, in this study, the cause for the binasal hemianopia was found to be ischemic optic neuropathy in two patients, and one case each of optic nerve drusen, glaucoma, congenital optic nerve pits, and retinitis pigmentosa sine pigmento. Thus 75% of the cases had an intraocular cause for the binasal hemianopia. Two patients had congenital hydrocephalus, and an intracranial basis was thus noted in 25% of these cases. The neurosurgeon should realize that the patient with binasal field defects is much more likely to have an ocular cause than an intracranial one for his problem.

Canonical Visual Size for Real-World Objects

PubMed Central

Konkle, Talia; Oliva, Aude

2012-01-01

Real-world objects can be viewed at a range of distances and thus can be experienced at a range of visual angles within the visual field. Given the large amount of visual size variation possible when observing objects, we examined how internal object representations represent visual size information. In a series of experiments which required observers to access existing object knowledge, we observed that real-world objects have a consistent visual size at which they are drawn, imagined, and preferentially viewed. Importantly, this visual size is proportional to the logarithm of the assumed size of the object in the world, and is best characterized not as a fixed visual angle, but by the ratio of the object and the frame of space around it. Akin to the previous literature on canonical perspective, we term this consistent visual size information the canonical visual size. PMID:20822298

Retinal nerve fiber layer thickness measured with optical coherence tomography is related to visual function in glaucomatous eyes.

PubMed

El Beltagi, Tarek A; Bowd, Christopher; Boden, Catherine; Amini, Payam; Sample, Pamela A; Zangwill, Linda M; Weinreb, Robert N

2003-11-01

To determine the relationship between areas of glaucomatous retinal nerve fiber layer thinning identified by optical coherence tomography and areas of decreased visual field sensitivity identified by standard automated perimetry in glaucomatous eyes. Retrospective observational case series. Forty-three patients with glaucomatous optic neuropathy identified by optic disc stereo photographs and standard automated perimetry mean deviations >-8 dB were included. Participants were imaged with optical coherence tomography within 6 months of reliable standard automated perimetry testing. The location and number of optical coherence tomography clock hour retinal nerve fiber layer thickness measures outside normal limits were compared with the location and number of standard automated perimetry visual field zones outside normal limits. Further, the relationship between the deviation from normal optical coherence tomography-measured retinal nerve fiber layer thickness at each clock hour and the average pattern deviation in each visual field zone was examined by using linear regression (R(2)). The retinal nerve fiber layer areas most frequently outside normal limits were the inferior and inferior temporal regions. The least sensitive visual field zones were in the superior hemifield. Linear regression results (R(2)) showed that deviation from the normal retinal nerve fiber layer thickness at optical coherence tomography clock hour positions 6 o'clock, 7 o'clock, and 8 o'clock (inferior and inferior temporal) was best correlated with standard automated perimetry pattern deviation in visual field zones corresponding to the superior arcuate and nasal step regions (R(2) range, 0.34-0.57). These associations were much stronger than those between clock hour position 6 o'clock and the visual field zone corresponding to the inferior nasal step region (R(2) = 0.01). Localized retinal nerve fiber layer thinning, measured by optical coherence tomography, is topographically related to decreased localized standard automated perimetry sensitivity in glaucoma patients.

Visual search for features and conjunctions following declines in the useful field of view.

PubMed

Cosman, Joshua D; Lees, Monica N; Lee, John D; Rizzo, Matthew; Vecera, Shaun P

2012-01-01

BACKGROUND/STUDY CONTEXT: Typical measures for assessing the useful field (UFOV) of view involve many components of attention. The objective of the current experiment was to examine differences in visual search efficiency for older individuals with and without UFOV impairment. The authors used a computerized screening instrument to assess the useful field of view and to characterize participants as having an impaired or normal UFOV. Participants also performed two visual search tasks, a feature search (e.g., search for a green target among red distractors) or a conjunction search (e.g., a green target with a gap on its left or right side among red distractors with gaps on the left or right and green distractors with gaps on the top or bottom). Visual search performance did not differ between UFOV impaired and unimpaired individuals when searching for a basic feature. However, search efficiency was lower for impaired individuals than unimpaired individuals when searching for a conjunction of features. The results suggest that UFOV decline in normal aging is associated with conjunction search. This finding suggests that the underlying cause of UFOV decline may arise from an overall decline in attentional efficiency. Because the useful field of view is a reliable predictor of driving safety, the results suggest that decline in the everyday visual behavior of older adults might arise from attentional declines.

Evaluation of Hydroxychloroquine Retinopathy With Multifocal Electroretinography

PubMed Central

So, Scott C.; Hedges, Thomas R.; Schuman, Joel S.; Quireza, Maria Luz Amaro

2007-01-01

BACKGROUND AND OBJECTIVE To describe the changes revealed by multifocal electroretinography (ERG) in patients taking hydroxychloroquine. PATIENTS AND METHODS Six patients being treated for various inflammatory conditions with hydroxychloroquine for periods ranging from 8 months to 7 years were consecutively evaluated. Each examination included measurement of Snellen visual acuities, Amsler grid assessment, and automated visual field testing. In some cases, funduscopic examinations were complimented by photography and fluorescein angiography. Multifocal ERG was performed for all patients. RESULTS Three patients (six eyes) were found to have distinctive abnormalities on multifocal ERG consisting of pericentral depression of ERG signals. The abnormalities on multifocal ERG corresponded with the patients’ subjective descriptions and the visual field depiction of their pericentral scotomas. All affected patients had been taking hydroxychloroquine for at least 7 years. One patient with generalized depression on multifocal ERG had possible hydroxychloroquine retinopathy. Two patients (three eyes) had relatively normal results on multifocal ERG. CONCLUSION Multifocal ERG objectively demonstrates depression of signals in the perifoveal region in visually symptomatic patients with long-term hydroxychloroquine use. Even patients with normal visual acuity and no fundus abnormalities can have abnormal results. Although we have not yet identified patients with abnormalities on multifocal ERG before the onset of symptoms, multifocal ERG may be useful in monitoring patients at risk and may provide an earlier opportunity to identify maculopathy. PMID:12757106

Anatomical Analysis of the Retinal Specializations to a Crypto-Benthic, Micro-Predatory Lifestyle in the Mediterranean Triplefin Blenny Tripterygion delaisi

PubMed Central

Fritsch, Roland; Collin, Shaun P.; Michiels, Nico K.

2017-01-01

The environment and lifestyle of a species are known to exert selective pressure on the visual system, often demonstrating a tight link between visual morphology and ecology. Many studies have predicted the visual requirements of a species by examining the anatomical features of the eye. However, among the vast number of studies on visual specializations in aquatic animals, only a few have focused on small benthic fishes that occupy a heterogeneous and spatially complex visual environment. This study investigates the general retinal anatomy including the topography of both the photoreceptor and ganglion cell populations and estimates the spatial resolving power (SRP) of the eye of the Mediterranean triplefin Tripterygion delaisi. Retinal wholemounts were prepared to systematically and quantitatively analyze photoreceptor and retinal ganglion cell (RGC) densities using design-based stereology. To further examine the retinal structure, we also used magnetic resonance imaging (MRI) and histological examination of retinal cross sections. Observations of the triplefin’s eyes revealed them to be highly mobile, allowing them to view the surroundings without body movements. A rostral aphakic gap and the elliptical shape of the eye extend its visual field rostrally and allow for a rostro-caudal accommodatory axis, enabling this species to focus on prey at close range. Single and twin cones dominate the retina and are consistently arranged in one of two regular patterns, which may enhance motion detection and color vision. The retina features a prominent, dorso-temporal, convexiclivate fovea with an average density of 104,400 double and 30,800 single cones per mm2, and 81,000 RGCs per mm2. Based on photoreceptor spacing, SRP was calculated to be between 6.7 and 9.0 cycles per degree. Location and resolving power of the fovea would benefit the detection and identification of small prey in the lower frontal region of the visual field. PMID:29311852

Anatomical Analysis of the Retinal Specializations to a Crypto-Benthic, Micro-Predatory Lifestyle in the Mediterranean Triplefin Blenny Tripterygion delaisi.

PubMed

Fritsch, Roland; Collin, Shaun P; Michiels, Nico K

2017-01-01

The environment and lifestyle of a species are known to exert selective pressure on the visual system, often demonstrating a tight link between visual morphology and ecology. Many studies have predicted the visual requirements of a species by examining the anatomical features of the eye. However, among the vast number of studies on visual specializations in aquatic animals, only a few have focused on small benthic fishes that occupy a heterogeneous and spatially complex visual environment. This study investigates the general retinal anatomy including the topography of both the photoreceptor and ganglion cell populations and estimates the spatial resolving power (SRP) of the eye of the Mediterranean triplefin Tripterygion delaisi . Retinal wholemounts were prepared to systematically and quantitatively analyze photoreceptor and retinal ganglion cell (RGC) densities using design-based stereology. To further examine the retinal structure, we also used magnetic resonance imaging (MRI) and histological examination of retinal cross sections. Observations of the triplefin's eyes revealed them to be highly mobile, allowing them to view the surroundings without body movements. A rostral aphakic gap and the elliptical shape of the eye extend its visual field rostrally and allow for a rostro-caudal accommodatory axis, enabling this species to focus on prey at close range. Single and twin cones dominate the retina and are consistently arranged in one of two regular patterns, which may enhance motion detection and color vision. The retina features a prominent, dorso-temporal, convexiclivate fovea with an average density of 104,400 double and 30,800 single cones per mm 2 , and 81,000 RGCs per mm 2 . Based on photoreceptor spacing, SRP was calculated to be between 6.7 and 9.0 cycles per degree. Location and resolving power of the fovea would benefit the detection and identification of small prey in the lower frontal region of the visual field.

TMS over the right precuneus reduces the bilateral field advantage in visual short term memory capacity.

PubMed

Kraft, Antje; Dyrholm, Mads; Kehrer, Stefanie; Kaufmann, Christian; Bruening, Jovita; Kathmann, Norbert; Bundesen, Claus; Irlbacher, Kerstin; Brandt, Stephan A

2015-01-01

Several studies have demonstrated a bilateral field advantage (BFA) in early visual attentional processing, that is, enhanced visual processing when stimuli are spread across both visual hemifields. The results are reminiscent of a hemispheric resource model of parallel visual attentional processing, suggesting more attentional resources on an early level of visual processing for bilateral displays [e.g. Sereno AB, Kosslyn SM. Discrimination within and between hemifields: a new constraint on theories of attention. Neuropsychologia 1991;29(7):659-75.]. Several studies have shown that the BFA extends beyond early stages of visual attentional processing, demonstrating that visual short term memory (VSTM) capacity is higher when stimuli are distributed bilaterally rather than unilaterally. Here we examine whether hemisphere-specific resources are also evident on later stages of visual attentional processing. Based on the Theory of Visual Attention (TVA) [Bundesen C. A theory of visual attention. Psychol Rev 1990;97(4):523-47.] we used a whole report paradigm that allows investigating visual attention capacity variability in unilateral and bilateral displays during navigated repetitive transcranial magnetic stimulation (rTMS) of the precuneus region. A robust BFA in VSTM storage capacity was apparent after rTMS over the left precuneus and in the control condition without rTMS. In contrast, the BFA diminished with rTMS over the right precuneus. This finding indicates that the right precuneus plays a causal role in VSTM capacity, particularly in bilateral visual displays. Copyright © 2015 Elsevier Inc. All rights reserved.

Retinal vessel caliber among people with acquired immunodeficiency syndrome: relationships with visual function.

PubMed

Kalyani, Partho S; Fawzi, Amani A; Gangaputra, Sapna; van Natta, Mark L; Hubbard, Larry D; Danis, Ronald P; Thorne, Jennifer E; Holland, Gary N

2012-03-01

To evaluate relationships between retinal vessel caliber and tests of visual function among people with AIDS. Longitudinal, observational cohort study. We evaluated data for participants without ocular opportunistic infections at initial examination (baseline) in the Longitudinal Studies of the Ocular Complications of AIDS (1998-2008). Visual function was evaluated with best-corrected visual acuity, Goldmann perimetry, automated perimetry (Humphrey Field Analyzer), and contrast sensitivity (CS) testing. Semi-automated grading of fundus photographs (1 eye/participant) determined central retinal artery equivalent (CRAE), central retinal vein equivalent (CRVE), and arteriole-to-venule ratio (AVR) at baseline. Multiple linear regression models, using forward selection, sought independent relationships between indices and visual function variables. Included were 1250 participants. Smaller AVR was associated with reduced visual field by Goldmann perimetry (P = .003) and worse mean deviation (P = .02) on automated perimetry and possibly with worse pattern standard deviation (PSD) on automated perimetry (P = .06). There was a weak association between smaller AVR and worse CS (P = .07). Relationships were independent of antiretroviral therapy and level of immunodeficiency (CD4+ T lymphocyte count, human immunodeficiency virus [HIV] RNA blood level). On longitudinal analysis, retinal vascular indices at baseline did not predict changes in visual function. Variation in retinal vascular indices is associated with abnormal visual function in people with AIDS, manifested by visual field loss and possibly by reduced CS. Relationships are consistent with the hypothesis that HIV-related retinal vasculopathy is a contributing factor to vision dysfunction among HIV-infected individuals. Longitudinal studies are needed to determine whether changes in indices predict change in visual function. Copyright © 2012 Elsevier Inc. All rights reserved.

Threshold and variability properties of matrix frequency-doubling technology and standard automated perimetry in glaucoma.

PubMed

Artes, Paul H; Hutchison, Donna M; Nicolela, Marcelo T; LeBlanc, Raymond P; Chauhan, Balwantray C

2005-07-01

To compare test results from second-generation Frequency-Doubling Technology perimetry (FDT2, Humphrey Matrix; Carl-Zeiss Meditec, Dublin, CA) and standard automated perimetry (SAP) in patients with glaucoma. Specifically, to examine the relationship between visual field sensitivity and test-retest variability and to compare total and pattern deviation probability maps between both techniques. Fifteen patients with glaucoma who had early to moderately advanced visual field loss with SAP (mean MD, -4.0 dB; range, +0.2 to -16.1) were enrolled in the study. Patients attended three sessions. During each session, one eye was examined twice with FDT2 (24-2 threshold test) and twice with SAP (Swedish Interactive Threshold Algorithm [SITA] Standard 24-2 test), in random order. We compared threshold values between FDT2 and SAP at test locations with similar visual field coordinates. Test-retest variability, established in terms of test-retest intervals and standard deviations (SDs), was investigated as a function of visual field sensitivity (estimated by baseline threshold and mean threshold, respectively). The magnitude of visual field defects apparent in total and pattern deviation probability maps were compared between both techniques by ordinal scoring. The global visual field indices mean deviation (MD) and pattern standard deviation (PSD) of FDT2 and SAP correlated highly (r > 0.8; P < 0.001). At test locations with high sensitivity (>25 dB with SAP), threshold estimates from FDT2 and SAP exhibited a close, linear relationship, with a slope of approximately 2.0. However, at test locations with lower sensitivity, the relationship was much weaker and ceased to be linear. In comparison with FDT2, SAP showed a slightly larger proportion of test locations with absolute defects (3.0% vs. 2.2% with SAP and FDT2, respectively, P < 0.001). Whereas SAP showed a significant increase in test-retest variability at test locations with lower sensitivity (P < 0.001), there was no relationship between variability and sensitivity with FDT2 (P = 0.46). In comparison with SAP, FDT2 exhibited narrower test-retest intervals at test locations with lower sensitivity (SAP thresholds <25 dB). A comparison of the total and pattern deviation maps between both techniques showed that the total deviation analyses of FDT2 may slightly underestimate the visual field loss apparent with SAP. However, the pattern-deviation maps of both instruments agreed well with each other. The test-retest variability of FDT2 is uniform over the measurement range of the instrument. These properties may provide advantages for the monitoring of patients with glaucoma that should be investigated in longitudinal studies.

Severity of Visual Field Loss and Health Related Quality of Life

PubMed Central

McKean-Cowdin, Roberta; Varma, Rohit; Wu, Joanne; Hays, Ron D.; Azen, Stanley P.

2009-01-01

Purpose To examine the association between severity of visual field loss (VFL) and self-reported health-related quality of life (HRQOL) in a population-based sample. Design Population-based cross-sectional study. Methods Participants in the Los Angeles Latino Eye Study underwent a comprehensive ophthalmic examination including visual field testing using the Humphrey Automated Field Analyzer II (SITA Standard 24-2). Mean Deviation (MD) scores were used to determine severity of VFL both as a continuous variable and stratified by severity: no VFL (MD≥ − 2 decibels [dB]), mild VFL (6dB

Repeatability of automated perimetry: a comparison between standard automated perimetry with stimulus size III and V, matrix, and motion perimetry.

PubMed

Wall, Michael; Woodward, Kimberly R; Doyle, Carrie K; Artes, Paul H

2009-02-01

Standard automated perimetry (SAP) shows a marked increase in variability in damaged areas of the visual field. This study was conducted to test the hypothesis that larger stimuli are associated with more uniform variability, by investigating the retest variability of four perimetry tests: standard automated perimetry size III (SAP III), with the SITA standard strategy; SAP size V (SAP V), with the full-threshold strategy; Matrix (FDT II), and Motion perimetry. One eye each of 120 patients with glaucoma was examined on the same day with these four perimetric tests and retested 1 to 8 weeks later. The decibel scales were adjusted to make the test's scales numerically similar. Retest variability was examined by establishing the distributions of retest threshold estimates, for each threshold level observed at the first test. The 5th and 95th percentiles of the retest distribution were used as point-wise limits of retest variability. Regression analyses were performed to quantify the relationship between visual field sensitivity and variability. With SAP III, the retest variability increased substantially with reducing sensitivity. Corresponding increases with SAP V, Matrix, and Motion perimetry were considerably smaller or absent. With SAP III, sensitivity explained 22% of the retest variability (r(2)), whereas corresponding data for SAP V, Matrix, and Motion perimetry were 12%, 2%, and 2%, respectively. Variability of Matrix and Motion perimetry does not increase as substantially as that of SAP III in damaged areas of the visual field. Increased sampling with the larger stimuli of these techniques is the likely explanation for this finding. These properties may make these stimuli excellent candidates for early detection of visual field progression.

Effects of the AMPA Antagonist ZK 200775 on Visual Function: A Randomized Controlled Trial

PubMed Central

Bergholz, Richard; Staks, Thomas; Rüther, Klaus

2010-01-01

Background ZK 200775 is an antagonist at the α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptor and had earned attention as a possible neuroprotective agent in cerebral ischemia. Probands receiving the agent within phase I trials reported on an alteration of visual perception. In this trial, the effects of ZK 200775 on the visual system were analyzed in detail. Methodology In a randomised controlled trial we examined eyes and vision before and after the intravenous administration of two different doses of ZK 200775 and placebo. There were 3 groups of 6 probands each: Group 1 recieved 0.03 mg/kg/h, group 2 0.75 mg/kg/h of ZK 200775, the control group received 0.9% sodium chloride solution. Probands were healthy males aged between 57 and 69 years. The following methods were applied: clinical examination, visual acuity, ophthalmoscopy, colour vision, rod absolute threshold, central visual field, pattern-reversal visual evoked potentials (pVEP), ON-OFF and full-field electroretinogram (ERG). Principal Findings No effect of ZK 200775 was seen on eye position or motility, stereopsis, pupillary function or central visual field testing. Visual acuity and dark vision deteriorated significantly in both treated groups. Color vision was most remarkably impaired. The dark-adapted ERG revealed a reduction of oscillatory potentials (OP) and partly of the a- and b-wave, furthermore an alteration of b-wave morphology and an insignificantly elevated b/a-ratio. Cone-ERG modalities showed decreased amplitudes and delayed implicit times. In the ON-OFF ERG the ON-answer amplitudes increased whereas the peak times of the OFF-answer were reduced. The pattern VEP exhibited lower amplitudes and prolonged peak times. Conclusions The AMPA receptor blockade led to a strong impairment of typical OFF-pathway functions like color vision and the cone ERG. On the other hand the ON-pathway as measured by dark vision and the scotopic ERG was affected as well. This further elucidates the interdependence of both pathways. Trial Registration ClinicalTrials.gov NCT00999284 PMID:20711429

[Clinico-statistical study on availability of Esterman disability score for assessment of mobility difficulty in patients with visual field loss].

PubMed

Yamagata, Yoshitaka; Terada, Yuko; Suzuki, Atsushi; Mimura, Osamu

2010-01-01

The visual efficiency scale currently adopted to determine the legal grade of visual disability associated with visual field loss in Japan is not appropriate for the evaluation of disability regarding daily living activities. We investigated whether Esterman disability score (EDS) is suitable for the assessment of mobility difficulty in patients with visual field loss. The correlation between the EDS calculated from Goldmann's kinetic visual field and the degree of subjective mobility difficulty determined by a questionnaire was investigated in 164 patients with visual field loss. The correlation between the EDS determined using a program built into the Humphrey field analyzer and that calculated from Goldmann's kinetic visual field was also investigated. The EDS based on the kinetic visual field was correlated well with the degree of subjective mobility difficulty, and the EDS measured using the Humphrey field analyzer could be estimated from the kinetic visual field-based EDS. Instead of the currently adopted visual efficiency scale, EDS should be employed for the assessment of mobility difficulty in patients with visual field loss, also to establish new judgment criteria concerning the visual field.

What Do Patients With Glaucoma See? Visual Symptoms Reported by Patients With Glaucoma

PubMed Central

Hu, Cindy X.; Zangalli, Camila; Hsieh, Michael; Gupta, Lalita; Williams, Alice L.; Richman, Jesse

2014-01-01

Abstract: Background: Vision loss from glaucoma has traditionally been described as loss of “peripheral vision.” In this prospective study, we aimed to improve our clinical understanding of the visual symptoms caused by glaucoma by asking patients specific detailed questions about how they see. Methods: Patients who were clinically diagnosed with various types and stages of glaucoma were included. All had a comprehensive ocular examination, including Octopus visual field testing. Patients were excluded if they had other ocular conditions that affected their vision, including cornea, lens or retina pathologies. Patients responded to an oral questionnaire about their visual symptoms. We investigated the visual symptoms described by patients with glaucoma and correlated the severity of visual field loss with visual symptoms reported. Results: Ninety-nine patients completed the questionnaire. Most patients (76%) were diagnosed with primary open-angle glaucoma. The most common symptoms reported by all patients, including patients with early or moderate glaucoma, were needing more light and blurry vision. Patients with a greater amount of field loss (Octopus mean defect >+9.4 dB) were more likely to report difficulty seeing objects to one or both sides, as if looking through dirty glasses and trouble differentiating boundaries and colors. Conclusions: Vision loss in patients with glaucoma is not as simple as the traditional view of loss of peripheral vision. Needing more light and blurry vision were the most common symptoms reported by patients with glaucoma. PMID:24992392

Visualization of hydrodynamic pilot-wave dynamics

NASA Astrophysics Data System (ADS)

Prost, Victor; Quintela, Julio; Harris, Daniel; Brun, Pierre-Thomas; Bush, John

2015-11-01

We present a low-cost device for examining the dynamics of droplets bouncing on a vibrating fluid bath, suitable for educational purposes. Dual control of vibrational and strobing frequency from a cell phone application allowed us to reduce the total cost to 60 dollars. Illumination with inhomogeneous colored light allows for striking visualization of the droplet dynamics and accompanying wave field via still photography or high-speed videography. Thanks to the NSF.

Do the Eyes Have It? Using Eye Tracking to Assess Students Cognitive Dimensions

ERIC Educational Resources Information Center

Nisiforou, Efi A.; Laghos, Andrew

2013-01-01

Field dependence/independence (FD/FI) is a significant dimension of cognitive styles. The paper presents results of a study that seeks to identify individuals' level of field independence during visual stimulus tasks processing. Specifically, it examined the relationship between the Hidden Figure Test (HFT) scores and the eye tracking metrics.…

Impact of Different Visual Field Testing Paradigms on Sample Size Requirements for Glaucoma Clinical Trials.

PubMed

Wu, Zhichao; Medeiros, Felipe A

2018-03-20

Visual field testing is an important endpoint in glaucoma clinical trials, and the testing paradigm used can have a significant impact on the sample size requirements. To investigate this, this study included 353 eyes of 247 glaucoma patients seen over a 3-year period to extract real-world visual field rates of change and variability estimates to provide sample size estimates from computer simulations. The clinical trial scenario assumed that a new treatment was added to one of two groups that were both under routine clinical care, with various treatment effects examined. Three different visual field testing paradigms were evaluated: a) evenly spaced testing, b) United Kingdom Glaucoma Treatment Study (UKGTS) follow-up scheme, which adds clustered tests at the beginning and end of follow-up in addition to evenly spaced testing, and c) clustered testing paradigm, with clusters of tests at the beginning and end of the trial period and two intermediary visits. The sample size requirements were reduced by 17-19% and 39-40% using the UKGTS and clustered testing paradigms, respectively, when compared to the evenly spaced approach. These findings highlight how the clustered testing paradigm can substantially reduce sample size requirements and improve the feasibility of future glaucoma clinical trials.

Information Visualization Techniques for Effective Cross-Discipline Communication

NASA Astrophysics Data System (ADS)

Fisher, Ward

2013-04-01

Collaboration between research groups in different fields is a common occurrence, but it can often be frustrating due to the absence of a common vocabulary. This lack of a shared context can make expressing important concepts and discussing results difficult. This problem may be further exacerbated when communicating to an audience of laypeople. Without a clear frame of reference, simple concepts are often rendered difficult-to-understand at best, and unintelligible at worst. An easy way to alleviate this confusion is with the use of clear, well-designed visualizations to illustrate an idea, process or conclusion. There exist a number of well-described machine-learning and statistical techniques which can be used to illuminate the information present within complex high-dimensional datasets. Once the information has been separated from the data, clear communication becomes a matter of selecting an appropriate visualization. Ideally, the visualization is information-rich but data-scarce. Anything from a simple bar chart, to a line chart with confidence intervals, to an animated set of 3D point-clouds can be used to render a complex idea as an easily understood image. Several case studies will be presented in this work. In the first study, we will examine how a complex statistical analysis was applied to a high-dimensional dataset, and how the results were succinctly communicated to an audience of microbiologists and chemical engineers. Next, we will examine a technique used to illustrate the concept of the singular value decomposition, as used in the field of computer vision, to a lay audience of undergraduate students from mixed majors. We will then examine a case where a simple animated line plot was used to communicate an approach to signal decomposition, and will finish with a discussion of the tools available to create these visualizations.

Clinical results from low-level laser therapy in patients with autosomal dominant cone-rod dystrophy

NASA Astrophysics Data System (ADS)

Koev, K.; Avramov, L.; Borissova, E.

2018-03-01

The objective of this study is to examine long-term effects of low-level laser therapy (LLLT) in patients with autosomal dominant cone-rod dystrophy (CRDs). A He-Ne Laser with continuous emission at 633 nm (01 mW/cm2) was used on five patients with autosomal dominant pedigree of Romani origin with non-syndromic CRDs. The laser radiation was applied transpupillary to the macula six times for three minutes every other day. The experiment was conducted for a period of three years. The clinical evaluation included best corrected visual acuity determination, funduscopy, Humphrey perimetry, Farnsworth Hue-28 color testing, fluorescein angiography, and full-field electroretinogram (ERG). All affected individuals presented reduced visual acuity (0.01 – 0.4) and photophobia. The funduscopic examination and fluorescein angiography revealed advanced changes including bone spicule-like pigment deposits in the midperiphery and the macular area, along with retinal atrophy, narrowing of the vessels, and waxy optic discs. The visual fields demonstrated central scotoma. The electrophysiologic examination of the patients detected an abnormal cone-rod ERG (20 – 30 μV) with photopic amplitudes more markedly reduced than the scotopic. Flicker responses were missing and Farnsworth Hue-28 test found protanopia. There was a statistically significant increase in the visual acuity (p<0.001, end of study versus baseline) for CRDs patients for the period of three years after the treatment with LLLT. Following the LLLT, the central absolute scotoma in CRDs was reduced, as was the prevalence of metamorphopsia in CRDs. This study shows that LLLT may prove be a novel long-lasting therapeutic option for both forms of CRDs. It is a highly effective treatment resulting in a long-term improvement of the visual acuity.

Change in Visual Field Progression Following Treatment Escalation in Primary Open-angle Glaucoma.

PubMed

Aptel, Florent; Bron, Alain M; Lachkar, Yves; Schweitzer, Cédric

2017-10-01

To evaluate the effect of treatment escalation on the rate of visual field progression in patients with primary open-angle glaucoma (POAG). Multicenter database study. We reviewed the electronic records of 171 patients with POAG under medical hypotensive treatment who underwent 5 consecutive visits 6 months apart before and after medical treatment escalation or additive laser trabeculoplasty. We calculated the rate of visual field progression (mean deviation change per year) before and after treatment escalation. The mean duration of follow-up was 5.1±0.5 years and the mean number of visual field examinations was 10.2±0.2. In 139 eyes with medical treatment escalation, the rate of progression was significantly reduced [from -0.57 to -0.29 dB/y; P=0.022; intraocular pressure (IOP) reduction 11.1%]. In detail, the rate of progression was significantly reduced after escalation from mono to dual therapy, dual to triple therapy, and from mono to triple therapy (-0.35 to -0.24 dB/y, P=0.018; -1.01 to -0.48 dB/y, P=0.038; -1.04 to -0.35 dB/y, P=0.020, respectively). In 32 eyes with additive laser trabeculoplasty, the rate of progression was significantly reduced (-0.60 to -0.24 dB/y; P=0.014; IOP reduction 9.4%). Medical treatment escalation or additive laser trabeculoplasty significantly reduced the rate of visual field progression in POAG. Larger IOP reduction has a greater probability of reducing glaucoma progression.

On-Road Driving Performance by Persons with Hemianopia and Quadrantanopia

PubMed Central

Wood, Joanne M.; McGwin, Gerald; Elgin, Jennifer; Vaphiades, Michael S.; Braswell, Ronald A.; DeCarlo, Dawn K.; Kline, Lanning B.; Meek, G. Christine; Searcey, Karen; Owsley, Cynthia

2009-01-01

Purpose This study was designed to examine the on-road driving performance of drivers with hemianopia and quadrantanopia compared with age-matched controls. Methods Participants included persons with hemianopia or quadrantanopia and those with normal visual fields. Visual and cognitive function tests were administered, including confirmation of hemianopia and quadrantanopia through visual field testing. Driving performance was assessed using a dual-brake vehicle and monitored by a certified driving rehabilitation specialist. The route was 14.1 miles of city and interstate driving. Two “back-seat” evaluators masked to drivers’ clinical characteristics independently assessed driving performance using a standard scoring system. Results Participants were 22 persons with hemianopia and 8 with quadrantanopia (mean age, 53 ± 20 years) and 30 participants with normal fields (mean age, 52 ± 19 years). Inter-rater agreement for back-seat evaluators was 96%. All drivers with normal fields were rated as safe to drive, while 73% (16/22) of hemianopic and 88% (7/8) of quadrantanopic drivers received safe ratings. Drivers with hemianopia or quadrantanopia who displayed on-road performance problems tended to have difficulty with lane position, steering steadiness, and gap judgment compared to controls. Clinical characteristics associated with unsafe driving were slowed visual processing speed, reduced contrast sensitivity and visual field sensitivity. Conclusions Some drivers with hemianopia or quadrantanopia are fit to drive compared with age-matched control drivers. Results call into question the fairness of governmental policies that categorically deny licensure to persons with hemianopia or quadrantanopia without the opportunity for on-road evaluation. PMID:18936138

Corticosteroid therapy in patients with non-arteritic anterior ischemic optic neuropathy.

PubMed

Vidović, Tomislav; Cerovski, Branimir; Perić, Sanja; Kordić, Rajko; Mrazovac, Danijela

2015-03-01

Non-arteritic anterior ischemic optic neuropathy is one of the most common conditions affecting the optic nerve in the elderly. It may lead to severe visual loss. Typical symptoms are painless impairment of visual function accompanied by relative afferent pupillary defect, edema of the optic disc and visual field defects. Aim is to present 38 patients with nonarteritic anterior ischemic optic neuropathy who were treated with corticosteroid therapy. This prospective study involved 38 patients, 20 men and 18 women aged 60-75 years who were treated with corticosteroid therapy. The study included patients with visual acuity in the affected eye from 0.1 to 0.8 according to Snellen. Every patient underwent clinical examination, the Octopus 900 perimetry in G program, laboratory testing, while the compressive optic neuropathy was rule out with MSCT of the brain and orbits. The most common forms of visual field defect are altitudinal defect and diffuse depression. Corticosteroid therapy led to recovery in 65% of patient, in 30% of patients did not change, while the deterioration occurred in 5% of patients.

Linking crowding, visual span, and reading.

PubMed

He, Yingchen; Legge, Gordon E

2017-09-01

The visual span is hypothesized to be a sensory bottleneck on reading speed with crowding thought to be the major sensory factor limiting the size of the visual span. This proposed linkage between crowding, visual span, and reading speed is challenged by the finding that training to read crowded letters reduced crowding but did not improve reading speed (Chung, 2007). Here, we examined two properties of letter-recognition training that may influence the transfer to improved reading: the spatial arrangement of training stimuli and the presence of flankers. Three groups of nine young adults were trained with different configurations of letter stimuli at 10° in the lower visual field: a flanked-local group (flanked letters localized at one position), a flanked-distributed group (flanked letters distributed across different horizontal locations), and an isolated-distributed group (isolated and distributed letters). We found that distributed training, but not the presence of flankers, appears to be necessary for the training benefit to transfer to increased reading speed. Localized training may have biased attention to one specific, small area in the visual field, thereby failing to improve reading. We conclude that the visual span represents a sensory bottleneck on reading, but there may also be an attentional bottleneck. Reducing the impact of crowding can enlarge the visual span and can potentially facilitate reading, but not when adverse attentional bias is present. Our results clarify the association between crowding, visual span, and reading.

Linking crowding, visual span, and reading

PubMed Central

He, Yingchen; Legge, Gordon E.

2017-01-01

The visual span is hypothesized to be a sensory bottleneck on reading speed with crowding thought to be the major sensory factor limiting the size of the visual span. This proposed linkage between crowding, visual span, and reading speed is challenged by the finding that training to read crowded letters reduced crowding but did not improve reading speed (Chung, 2007). Here, we examined two properties of letter-recognition training that may influence the transfer to improved reading: the spatial arrangement of training stimuli and the presence of flankers. Three groups of nine young adults were trained with different configurations of letter stimuli at 10° in the lower visual field: a flanked-local group (flanked letters localized at one position), a flanked-distributed group (flanked letters distributed across different horizontal locations), and an isolated-distributed group (isolated and distributed letters). We found that distributed training, but not the presence of flankers, appears to be necessary for the training benefit to transfer to increased reading speed. Localized training may have biased attention to one specific, small area in the visual field, thereby failing to improve reading. We conclude that the visual span represents a sensory bottleneck on reading, but there may also be an attentional bottleneck. Reducing the impact of crowding can enlarge the visual span and can potentially facilitate reading, but not when adverse attentional bias is present. Our results clarify the association between crowding, visual span, and reading. PMID:28973564

The Effect of Acute Sleep Deprivation on Visual Evoked Potentials in Professional Drivers

PubMed Central

Jackson, Melinda L.; Croft, Rodney J.; Owens, Katherine; Pierce, Robert J.; Kennedy, Gerard A.; Crewther, David; Howard, Mark E.

2008-01-01

Study Objectives: Previous studies have demonstrated that as little as 18 hours of sleep deprivation can cause deleterious effects on performance. It has also been suggested that sleep deprivation can cause a “tunnel-vision” effect, in which attention is restricted to the center of the visual field. The current study aimed to replicate these behavioral effects and to examine the electrophysiological underpinnings of these changes. Design: Repeated-measures experimental study. Setting: University laboratory. Patients or Participants: Nineteen professional drivers (1 woman; mean age = 45.3 ± 9.1 years). Interventions: Two experimental sessions were performed; one following 27 hours of sleep deprivation and the other following a normal night of sleep, with control for circadian effects. Measurements & Results: A tunnel-vision task (central versus peripheral visual discrimination) and a standard checkerboard-viewing task were performed while 32-channel EEG was recorded. For the tunnel-vision task, sleep deprivation resulted in an overall slowing of reaction times and increased errors of omission for both peripheral and foveal stimuli (P < 0.05). These changes were related to reduced P300 amplitude (indexing cognitive processing) but not measures of early visual processing. No evidence was found for an interaction effect between sleep deprivation and visual-field position, either in terms of behavior or electrophysiological responses. Slower processing of the sustained parvocellular visual pathway was demonstrated. Conclusions: These findings suggest that performance deficits on visual tasks during sleep deprivation are due to higher cognitive processes rather than early visual processing. Sleep deprivation may differentially impair processing of more-detailed visual information. Features of the study design (eg, visual angle, duration of sleep deprivation) may influence whether peripheral visual-field neglect occurs. Citation: Jackson ML; Croft RJ; Owens K; Pierce RJ; Kennedy GA; Crewther D; Howard ME. The effect of acute sleep deprivation on visual evoked potentials in professional drivers. SLEEP 2008;31(9):1261-1269. PMID:18788651

A prospective profile of visual field loss following stroke: prevalence, type, rehabilitation, and outcome.

PubMed

Rowe, Fiona J; Wright, David; Brand, Darren; Jackson, Carole; Harrison, Shirley; Maan, Tallat; Scott, Claire; Vogwell, Linda; Peel, Sarah; Akerman, Nicola; Dodridge, Caroline; Howard, Claire; Shipman, Tracey; Sperring, Una; Macdiarmid, Sonia; Freeman, Cicely

2013-01-01

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

Using the Biodatamation(TM) strategy to learn introductory college biology: Value-added effects on selected students' conceptual understanding and conceptual integration of the processes of photosynthesis and cellular respiration

NASA Astrophysics Data System (ADS)

Reuter, Jewel Jurovich

The purpose of this exploratory research was to study how students learn photosynthesis and cellular respiration and to determine the value added to the student's learning by each of the three technology-scaffolded learning strategy components (animated concept presentations and WebQuest-style activities, data collection, and student-constructed animations) of the BioDatamation(TM) (BDM) Program. BDM learning strategies utilized the Theory of Interacting Visual Fields(TM) (TIVF) (Reuter & Wandersee, 2002a, 2002b; 2003a, 2003b) which holds that meaningful knowledge is hierarchically constructed using the past, present, and future visual fields, with visual metacognitive components that are derived from the principles of Visual Behavior (Jones, 1995), Human Constructivist Theory (Mintzes & Wandersee, 1998a), and Visual Information Design Theory (Tufte, 1990, 1997, 2001). Student alternative conceptions of photosynthesis and cellular respiration were determined by the item analysis of 263,267 Biology Advanced Placement Examinations and were used to develop the BDM instructional strategy and interview questions. The subjects were 24 undergraduate students of high and low biology prior knowledge enrolled in an introductory-level General Biology course at a major research university in the Deep South. Fifteen participants received BDM instruction which included original and innovative learning materials and laboratories in 6 phases; 8 of the 15 participants were the subject of in depth, extended individual analysis. The other 9 participants received traditional, non-BDM instruction. Interviews which included participants' creation of concept maps and visual field diagrams were conducted after each phase. Various content analyses, including Chi's Verbal Analysis and quantitizing/qualitizing were used for data analysis. The total value added to integrative knowledge during BDM instruction with the three visual fields was an average increase of 56% for cellular respiration and 62% increase for photosynthesis knowledge, improved long-term memory of concepts, and enhanced biological literacy to the multidimensional level, as determined by the BSCS literacy model. WebQuest-style activities and data collection provided for animated prior knowledge in the past visual field, and detailed content knowledge construction in the present visual field. During student construction of animated presentations, layering required participants to think by rearranging words and images for improved hierarchical organization of knowledge with real-life applications.

Developing a Side Bias for Conspecific Faces during Childhood

ERIC Educational Resources Information Center

Balas, Benjamin; Moulson, Margaret C.

2011-01-01

Adults preferentially use information from the left side of face images to judge gender, emotion, and identity. In this study, we examined the development of this visual-field bias over middle childhood (5-10 years). Our goal was to both characterize the developmental trajectory of the left-side bias (should one exist) and examine the selectivity…

The sensory components of high-capacity iconic memory and visual working memory.

PubMed

Bradley, Claire; Pearson, Joel

2012-01-01

EARLY VISUAL MEMORY CAN BE SPLIT INTO TWO PRIMARY COMPONENTS: a high-capacity, short-lived iconic memory followed by a limited-capacity visual working memory that can last many seconds. Whereas a large number of studies have investigated visual working memory for low-level sensory features, much research on iconic memory has used more "high-level" alphanumeric stimuli such as letters or numbers. These two forms of memory are typically examined separately, despite an intrinsic overlap in their characteristics. Here, we used a purely sensory paradigm to examine visual short-term memory for 10 homogeneous items of three different visual features (color, orientation and motion) across a range of durations from 0 to 6 s. We found that the amount of information stored in iconic memory is smaller for motion than for color or orientation. Performance declined exponentially with longer storage durations and reached chance levels after ∼2 s. Further experiments showed that performance for the 10 items at 1 s was contingent on unperturbed attentional resources. In addition, for orientation stimuli, performance was contingent on the location of stimuli in the visual field, especially for short cue delays. Overall, our results suggest a smooth transition between an automatic, high-capacity, feature-specific sensory-iconic memory, and an effortful "lower-capacity" visual working memory.

The influence of an immersive virtual environment on the segmental organization of postural stabilizing responses.

PubMed

Keshner, E A; Kenyon, R V

2000-01-01

We examined the effect of a 3-dimensional stereoscopic scene on segmental stabilization. Eight subjects participated in static sway and locomotion experiments with a visual scene that moved sinusoidally or at constant velocity about the pitch or roll axes. Segmental displacements, Fast Fourier Transforms, and Root Mean Square values were calculated. In both pitch and roll, subjects exhibited greater magnitudes of motion in head and trunk than ankle. Smaller amplitudes and frequent phase reversals suggested control of the ankle by segmental proprioceptive inputs and ground reaction forces rather than by the visual-vestibular signals. Postural controllers may set limits of motion at each body segment rather than be governed solely by a perception of the visual vertical. Two locomotor strategies were also exhibited, implying that some subjects could override the effect of the roll axis optic flow field. Our results demonstrate task dependent differences that argue against using static postural responses to moving visual fields when assessing more dynamic tasks.

The frontal eye fields limit the capacity of visual short-term memory in rhesus monkeys.

PubMed

Lee, Kyoung-Min; Ahn, Kyung-Ha

2013-01-01

The frontal eye fields (FEF) in rhesus monkeys have been implicated in visual short-term memory (VSTM) as well as control of visual attention. Here we examined the importance of the area in the VSTM capacity and the relationship between VSTM and attention, using the chemical inactivation technique and multi-target saccade tasks with or without the need of target-location memory. During FEF inactivation, serial saccades to targets defined by color contrast were unaffected, but saccades relying on short-term memory were impaired when the target count was at the capacity limit of VSTM. The memory impairment was specific to the FEF-coded retinotopic locations, and subject to competition among targets distributed across visual fields. These results together suggest that the FEF plays a crucial role during the entry of information into VSTM, by enabling attention deployment on targets to be remembered. In this view, the memory capacity results from the limited availability of attentional resources provided by FEF: The FEF can concurrently maintain only a limited number of activations to register the targets into memory. When lesions render part of the area unavailable for activation, the number would decrease, further reducing the capacity of VSTM.

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

PubMed

Yahata, Izumi; Kawase, Tetsuaki; Kanno, Akitake; Hidaka, Hiroshi; Sakamoto, Shuichi; Nakasato, Nobukazu; Kawashima, Ryuta; Katori, Yukio

2017-01-01

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

Visual indices of motor vehicle drivers in relation to road safety in Nigeria.

PubMed

Emerole, C G; Nneli, R O

2013-06-30

This study assessed the visual profile of motor vehicle drivers in Owerri, Nigeria and to analyse the relationship between the various aspects of visual function in relation to road safety. A cross-sectional descriptive study of 150 commercial vehicles drivers and 130 private vehicles drivers was conducted between November 2005 and February 2006. Data were obtained using structured interviewer administered questionnaires and clinical examination was done. Standards procedures were used to determine visual indices. Data from the better eye (eye with a better visual acuity according to international and national standards) were reported, except in the analysis of near vision of the respondents. Twenty percent of the study group had normal visual acuity of ≥6/6 compared with 46.2% in the control group. The tonometric value in 88.0% and 93.1% of study and control groups respectively was less than 24mmHg. Both groups (96.8%) had normal confrontation visual field while 95.3% of study group and 97.7% of control group had normal colour vision. The most prevailing eye conditions that may reduce visual acuity were pterygium (51.3% in study group and 13.8% in the control group), retinopathy (16.7% of study group and 6.2% of control group) and glaucoma (12.0% and 6.9% of study and control groups respectively). Nineteen percent of the study group had regular eye examination compared with 38.5% in the control group. Alcohol consumption was 64.7% in the study group and 32.3% in the control group. Most of the commercial motor drivers in Owerri, Nigeria did not meet the Federal Road Safety Commission visual acuity standard for commercial motor drivers. Visual impairments and poor visibility are strongly associated with RTA among Nigerian motor vehicle drivers. Visual acuity and visual health care were poor among commercial motor drivers. There is need for renewed efforts to enforce a compulsory periodic visual examination for drivers, and to ensure that visual requirements for driving are met.

SU5. Investigation of the Visual Steady-State Response in Schizophrenia, Schizoaffective, Psychotic, and Nonpsychotic Bipolar Disorders

PubMed Central

Schneider, Zoe; Parker, David; Kittle, Frances; McDowell, Jennifer; Buckley, Peter; Keedy, Sarah; Gershon, Elliot; Sweeney, John; Keshavan, Matcheri; Pearlson, Godfrey; Tamminga, Carol; Clementz, Brett

2017-01-01

Abstract Background: Electroencephalographic (EEG) studies of the visual steady-state response (ssVEP) probe the oscillatory capacity and synchronization in the primary visual cortex. Previous ssVEP studies have demonstrated early visual processing deficits in schizophrenia (SZ). However, few studies have examined the ssVEP across diagnostic categories and included the full spectrum of psychotic subgroups (schizophrenia: SZ, schizoaffective disorder: SAD, bipolar disorder with psychosis: BDP, and bipolar disorder without psychosis: BD-NP). This is a critical step in order to investigate its potential as a biomarker and to examine specific neural deficits that are unique to each disorder. In this study visual steady-state stimuli in the central, bilateral, left, and right hemisphere were administered to a large sample of well characterized participants diagnosed with SZ, SAD, BDP, or BD-NP. Methods: Four hundred and seven individuals (HC = 153, SZ = 64, SAD = 79, BDP = 65, BD-NP = 46) completed the ssVEP EEG task at the 5 BSNIP sites. A black and white square oscillating at 18.75 Hz was placed in the subject’s central, bilateral, left, and right visual field for 2000 ms. Inter-trial phase coherence (ITC) was calculated for each subject, sensor, and task. The resulting time-frequency values ranged from 4 to 53 Hz and −500 to 2000 ms poststimulus. The 7 peak sensors from the grand average for each task were selected and used to average over the 0–2000 ms ssVEP period for each subject. One-way ANOVA’s and Welch’s t tests were conducted to determine group differences for each task. Results: SAD had significantly reduced ITC in comparison to HC during the bilateral ssVEP task. SZ and SAD both had significantly reduced ITC in comparison to HC and BD-NP during the center visual field trials. There were no significant group differences in either left or right visual field trials for any of the groups. BDP and BD-NP did not differ from HC in any of the conditions. Conclusion: There are 2 main conclusions that can be drawn from this study. (1) Both SZ and SAD had a reduced response to the central stimuli. This is suggestive of a core deficit at the beginning of the visual processing pathway. (2) SAD had a reduction in response the bilateral stimuli. This suggests that SAD has a unique deficit in interhemispheric visual response that is not found in any of the other psychotic or bipolar disorders. Examining differences in the ssVEP between proband groups offers unique insight into how neural synchronization relates to the etiology of SZ and SAD. This provides novel information about core visual processing deficits that could potentially be used as a translational biomarker.

Small-spot laser-exposure effects on visual function

NASA Astrophysics Data System (ADS)

Zwick, Harry; Robbins, David O.; Stuck, Bruce E.; Lund, David J.; Reynolds, Scottie B.; Nawim, Maqsood; Schuschereba, Steven T.

1990-07-01

Laser field exposure effects on visual function involve produc tJon of minimal spot irradiation on or near the huntan fovea. Functional effects of such exposure may involve transient or perinanent change in visual function depending upon exposure dose. While Maximun Permissible Exposure (MPE) lirrtits define exposure in terins of threshold retinal niorphological change such limits are not applicable with regard to transient changes in visual function below MPE limits induced by alteration in retinal physiological processes. Mechanisms of transient and permanent functional change reported in these exper iments point out the need to examine laser safety limits in terms of both the functional as well as the morphological disturbance induced in retinal tissue. L

Interactive displays in medical art

NASA Technical Reports Server (NTRS)

Mcconathy, Deirdre Alla; Doyle, Michael

1989-01-01

Medical illustration is a field of visual communication with a long history. Traditional medical illustrations are static, 2-D, printed images; highly realistic depictions of the gross morphology of anatomical structures. Today medicine requires the visualization of structures and processes that have never before been seen. Complex 3-D spatial relationships require interpretation from 2-D diagnostic imagery. Pictures that move in real time have become clinical and research tools for physicians. Medical illustrators are involved with the development of interactive visual displays for three different, but not discrete, functions: as educational materials, as clinical and research tools, and as data bases of standard imagery used to produce visuals. The production of interactive displays in the medical arts is examined.

Development of cortical orientation selectivity in the absence of visual experience with contour

PubMed Central

Hussain, Shaista; Weliky, Michael

2011-01-01

Visual cortical neurons are selective for the orientation of lines, and the full development of this selectivity requires natural visual experience after eye opening. Here we examined whether this selectivity develops without seeing lines and contours. Juvenile ferrets were reared in a dark room and visually trained by being shown a movie of flickering, sparse spots. We found that despite the lack of contour visual experience, the cortical neurons of these ferrets developed strong orientation selectivity and exhibited simple-cell receptive fields. This finding suggests that overt contour visual experience is unnecessary for the maturation of orientation selectivity and is inconsistent with the computational models that crucially require the visual inputs of lines and contours for the development of orientation selectivity. We propose that a correlation-based model supplemented with a constraint on synaptic strength dynamics is able to account for our experimental result. PMID:21753023

Continuous visual field motion impacts the postural responses of older and younger women during and after support surface tilt

PubMed Central

Lauer, Richard T.; Keshner, Emily A.

2011-01-01

The effect of continuous visual flow on the ability to regain and maintain postural orientation was examined. Fourteen young (20–39 years old) and 14 older women (60–79 years old) stood quietly during 3° (30°/s) dorsiflexion tilt of the support surface combined with 30° and 45°/s upward or downward pitch rotations of the visual field. The support surface was held tilted for 30 s and then returned to neutral over a 30-s period while the visual field continued to rotate. Segmental displacement and bilateral tibialis anterior and gastrocnemius muscle EMG responses were recorded. Continuous wavelet transforms were calculated for each muscle EMG response. An instantaneous mean frequency curve (IMNF) of muscle activity, center of mass (COM), center of pressure (COP), and angular excursion at the hip and ankle were used in a functional principal component analysis (fPCA). Functional component weights were calculated and compared with mixed model repeated measures ANOVAs. The fPCA revealed greatest mathematical differences in COM and COP responses between groups or conditions during the period that the platform transitioned from the sustained tilt to a return to neutral position. Muscle EMG responses differed most in the period following support surface tilt indicating that muscle activity increased to support stabilization against the visual flow. Older women exhibited significantly larger COM and COP responses in the direction of visual field motion and less muscle modulation when the platform returned to neutral than younger women. Results on a Rod and Frame test indicated that older women were significantly more visually dependent than the younger women. We concluded that a stiffer body combined with heightened visual sensitivity in older women critically interferes with their ability to counteract posturally destabilizing environments. PMID:21479659

Not one extrastriate body area: Using anatomical landmarks, hMT+, and visual field maps to parcellate limb-selective activations in human lateral occipitotemporal cortex

PubMed Central

Weiner, Kevin S.; Grill-Spector, Kalanit

2011-01-01

The prevailing view of human lateral occipitotemporal cortex (LOTC) organization suggests a single area selective for images of the human body (extrastriate body area, EBA) that highly overlaps with the human motion-selective complex (hMT+). Using functional magnetic resonance imaging with higher resolution (1.5mm voxels) than past studies (3–4mm voxels), we examined the fine-scale spatial organization of these activations relative to each other, as well as to visual field maps in LOTC. Rather than one contiguous EBA highly overlapping hMT+, results indicate three limb-selective activations organized in a crescent surrounding hMT+: (1) an activation posterior to hMT+ on the lateral occipital sulcus/middle occipital gyrus (LOS/MOG) overlapping the lower vertical meridian shared between visual field maps LO-2 and TO-1, (2) an activation anterior to hMT+ on the middle temporal gyrus (MTG) consistently overlapping the lower vertical meridian of TO-2 and extending outside presently defined visual field maps, and (3) an activation inferior to hMT+ on the inferotemporal gyrus (ITG) overlapping the parafoveal representation of the TO cluster. This crescent organization of limb-selective activations surrounding hMT+ is reproducible over a span of three years and is consistent across different image types used for localization. Further, these regions exhibit differential position properties: preference for contralateral image presentation decreases and preference for foveal presentation increases from the limb-selective LOS to the MTG. Finally, the relationship between limb-selective activations and visual field maps extends to the dorsal stream where a posterior IPS activation overlaps V7. Overall, our measurements demonstrate a series of LOTC limb-selective activations that 1) have separate anatomical and functional boundaries, 2) overlap distinct visual field maps, and 3) illustrate differential position properties. These findings indicate that category selectivity alone is an insufficient organization principle for defining brain areas. Instead, multiple properties are necessary in order to parcellate and understand the functional organization of high-level visual cortex. PMID:21439386

Concurrent Vision Dysfunctions in Convergence Insufficiency with Traumatic Brain Injury

PubMed Central

Alvarez, Tara L.; Kim, Eun H.; Vicci, Vincent R.; Dhar, Sunil K.; Biswal, Bharat B.; Barrett, A. M.

2012-01-01

Purpose This study assessed the prevalence of convergence insufficiency (CI) with and without simultaneous vision dysfunctions within the traumatic brain injury (TBI) sample population because although CI is commonly reported with TBI, the prevalence of concurrent visual dysfunctions with CI in TBI is unknown. Methods A retrospective analysis of 557 medical records from TBI civilian patients was conducted. Patients were all evaluated by a single optometrist. Visual acuity, oculomotor, binocular vision function, accommodation, visual fields, ocular health and vestibular function were assessed. Statistical comparisons between the CI and non-CI, as well as in-patient and out-patient subgroups, were conducted using chi-squared and Z-tests. Results Approximately 9% of the TBI sample had CI without the following simultaneous diagnoses: saccade or pursuit dysfunction; 3rd, 4th, or 6th nerve palsy; visual field deficit; visual spatial inattention/neglect; vestibular dysfunction or nystagmus. Photophobia with CI was observed in 16.3% (N=21/130) and vestibular dysfunction with CI was observed in 18.5% (N=24/130) of the CI subgroup. CI and cranial nerve palsies were common and yielded prevalence rates of 23.3% (N=130/557) and 26.9% (N=150/557), respectively, within the TBI sample. Accommodative dysfunction was common within the non-presbyopic TBI sample with a prevalence of 24.4% (N=76/314). Visual field deficits or unilateral visual spatial inattention/neglect were observed within 29.6% (N=80/270) of the TBI in-patient subgroup and were significantly more prevalent compared to the out-patient subgroup (p<0.001). Most TBI patients had visual acuities of 20/60 or better in the TBI sample (85%;N=473/557). Conclusions CI without simultaneous visual or vestibular dysfunctions was observed in about 9% of the visually symptomatic TBI civilian population studied. A thorough visual and vestibular examination is recommended for all TBI patients. PMID:23190716

[Analysis of clinical phenotype and mode of inheritance in retinitis pigmentosa patients with consanguineous marriage].

PubMed

Rong, Wei-ning; Sheng, Xun-lun; Liu, Ya-ni

2012-10-01

To analyse the mode of inheritance and clinical characteristics of retinitis pigmentosa (RP) patients with consanguineous marriage. RP patients were recruited for this study in Ningxia Eye Hospital from September 2009 to July 2011. All patients received complete ophthalmic examination. The mode of inheritance were determined based on family history and marriage history. Clinical features were characterized by complete ophthalmic examinations including visual acuity, macular OCT, visual field and electroretinogram (ERG). A total of 143 individuals with RP (33 families) were recruited. Based on analysis of family history and marriage history, 20 RP families (23 patients) had consanguineous marriage history accounted for 60.6% RP families (16.1% RP patients). There were 4 patients (from 4 families) diagnosed as Usher syndrome. In 20 RP families with consanguineous marriage history, 7 families (35.0%) were Hui ethnicity and 13 families (65%) were Han ethnicity. The marriages of 15 families were between first cousins and 3 families were between second cousins, only 2 families were between half cousins matrimony. Of 23 RP patients, 12 were males and 11 were females. The average age of onset was 11.4 ± 6.8 years and the average age of recruitment was (32.0 ± 13.5) years. The best-corrected visual acuity was less than 0.6 in 78.2% patients. According to the features of the fundus, 13 patients were classical retinitis pigmentosa and 10 patients were retinitis pigmentosa sine pigmento. Visual field examination showed that all patients had varying degrees of peripheral visual field defect. Retinal neuroepithelial layer of macular and peripheral retina became thinner and retinal photoreceptors were disappeared. The average thickness of macular fovea was (186.1 ± 78.7) µm on right eyes and (187.4 ± 76.3) µm on left eyes. The incidence of RP with consanguineous marriages was high in Ningxia Region. The mode of inheritance of RP patients with consanguinity is autosomal recessive. The common marriage pattern of consanguinity is between first cousins. The age of onset is early and the ocular fundus changes of some patients are atypical, this should be paid attention clinically.

The multiple sclerosis visual pathway cohort: understanding neurodegeneration in MS.

PubMed

Martínez-Lapiscina, Elena H; Fraga-Pumar, Elena; Gabilondo, Iñigo; Martínez-Heras, Eloy; Torres-Torres, Ruben; Ortiz-Pérez, Santiago; Llufriu, Sara; Tercero, Ana; Andorra, Magi; Roca, Marc Figueras; Lampert, Erika; Zubizarreta, Irati; Saiz, Albert; Sanchez-Dalmau, Bernardo; Villoslada, Pablo

2014-12-15

Multiple Sclerosis (MS) is an immune-mediated disease of the Central Nervous System with two major underlying etiopathogenic processes: inflammation and neurodegeneration. The latter determines the prognosis of this disease. MS is the main cause of non-traumatic disability in middle-aged populations. The MS-VisualPath Cohort was set up to study the neurodegenerative component of MS using advanced imaging techniques by focusing on analysis of the visual pathway in a middle-aged MS population in Barcelona, Spain. We started the recruitment of patients in the early phase of MS in 2010 and it remains permanently open. All patients undergo a complete neurological and ophthalmological examination including measurements of physical and disability (Expanded Disability Status Scale; Multiple Sclerosis Functional Composite and neuropsychological tests), disease activity (relapses) and visual function testing (visual acuity, color vision and visual field). The MS-VisualPath protocol also assesses the presence of anxiety and depressive symptoms (Hospital Anxiety and Depression Scale), general quality of life (SF-36) and visual quality of life (25-Item National Eye Institute Visual Function Questionnaire with the 10-Item Neuro-Ophthalmic Supplement). In addition, the imaging protocol includes both retinal (Optical Coherence Tomography and Wide-Field Fundus Imaging) and brain imaging (Magnetic Resonance Imaging). Finally, multifocal Visual Evoked Potentials are used to perform neurophysiological assessment of the visual pathway. The analysis of the visual pathway with advance imaging and electrophysilogical tools in parallel with clinical information will provide significant and new knowledge regarding neurodegeneration in MS and provide new clinical and imaging biomarkers to help monitor disease progression in these patients.

Visual Sensory and Visual-Cognitive Function and Rate of Crash and Near-Crash Involvement Among Older Drivers Using Naturalistic Driving Data

PubMed Central

Huisingh, Carrie; Levitan, Emily B.; Irvin, Marguerite R.; MacLennan, Paul; Wadley, Virginia; Owsley, Cynthia

2017-01-01

Purpose An innovative methodology using naturalistic driving data was used to examine the association between visual sensory and visual-cognitive function and rates of future crash or near-crash involvement among older drivers. Methods The Strategic Highway Research Program (SHRP2) Naturalistic Driving Study was used for this prospective analysis. The sample consisted of N = 659 drivers aged ≥70 years and study participation lasted 1 or 2 years for most participants. Distance and near visual acuity, contrast sensitivity, peripheral vision, visual processing speed, and visuospatial skills were assessed at baseline. Crash and near-crash involvement were based on video recordings and vehicle sensors. Poisson regression models were used to generate crude and adjusted rate ratios (RRs) and 95% confidence intervals, while accounting for person-miles of travel. Results After adjustment, severe impairment of the useful field of view (RR = 1.33) was associated with an increased rate of near-crash involvement. Crash, severe crash, and at-fault crash involvement were associated with impaired contrast sensitivity in the worse eye (RRs = 1.38, 1.54, and 1.44, respectively) and far peripheral field loss in both eyes (RRs = 1.74, 2.32, and 1.73, respectively). Conclusions Naturalistic driving data suggest that contrast sensitivity in the worse eye and far peripheral field loss in both eyes elevate the rates of crash involvement, and impaired visual processing speed elevates rates of near-crash involvement among older drivers. Naturalistic driving data may ultimately be critical for understanding the relationship between vision and driving safety. PMID:28605807

A field intervention examining the impact of an office ergonomics training and a highly adjustable chair on visual symptoms in a public sector organization

PubMed Central

Amick, Benjamin C.; Menéndez, Cammie Chaumont; Bazzani, Lianna; Robertson, Michelle; DeRango, Kelly; Rooney, Ted; Moore, Anne

2016-01-01

Objective Examine the effect of a multi-component office ergonomics intervention on visual symptom reductions. Methods Office workers were assigned to either a group receiving a highly adjustable chair with office ergonomics training (CWT), a training-only group (TO) or a control group (C). A work environment and health questionnaire was administered 2 and 1 month(s) pre-intervention and 3, 6, and 12 months post-intervention. Multi-level statistical models tested hypotheses. Results The CWT intervention lowered daily visual symptoms (p < 0.01) post-intervention. The TO group did not significantly differ from the control group. The CWT group differed significantly from the TO group (p = 0.01) post-intervention. Conclusion Workers who received a highly adjustable chair and office ergonomics training had reduced visual symptoms and the effect was maintained through twelve months post-intervention. The lack of a training-only group effect supports implementing training in conjunction with the highly adjustable chair to reduce visual symptoms. PMID:21963250

A field intervention examining the impact of an office ergonomics training and a highly adjustable chair on visual symptoms in a public sector organization.

PubMed

Amick, Benjamin C; Menéndez, Cammie Chaumont; Bazzani, Lianna; Robertson, Michelle; DeRango, Kelly; Rooney, Ted; Moore, Anne

2012-05-01

Examine the effect of a multi-component office ergonomics intervention on visual symptom reductions. Office workers were assigned to either a group receiving a highly adjustable chair with office ergonomics training (CWT), a training-only group (TO) or a control group (C). A work environment and health questionnaire was administered 2 and 1 month(s) pre-intervention and 3, 6, and 12 months post-intervention. Multi-level statistical models tested hypotheses. The CWT intervention lowered daily visual symptoms (p < 0.01) post-intervention. The TO group did not significantly differ from the control group. The CWT group differed significantly from the TO group (p = 0.01) post-intervention. Workers who received a highly adjustable chair and office ergonomics training had reduced visual symptoms and the effect was maintained through twelve months post-intervention. The lack of a training-only group effect supports implementing training in conjunction with the highly adjustable chair to reduce visual symptoms. Copyright © 2011 Elsevier Ltd and The Ergonomics Society. All rights reserved.

[Solar retinopathy].

PubMed

Kawa, P; Mańkowska, A; Mackiewicz, J; Zagórski, Z

1998-01-01

The purpose of this study is the present clinical evaluation of 21 patients (number of affected eyes--33), who watched eclipse of the sun on 12 October 1996. All patients had general ophthalmic examination with emphasis on visual acuity, visual field, Amsler test, fluorescein angiography and fundus appearance. Eleven out of 21 patients had at least one follow up examination (number of affected eyes--17). None of the patient received any treatment. All patients revealed tiny, central scotomata--positive Amsler test and decreased visual acuity on the first visit; reading Snellen chart could be improved in all patients by adequate head tilt or eye movement (improvement up to 3 Snellen chart lines). No signs of retinopathy were observed in two eyes with uncorrected refractive error and one amblyopic eye. After 7-8 weeks the visual acuity was decreased to 5/30 in two eyes and to 5/10 in ten eyes. In all those eyes persisted a tiny, central scotoma. Looking at the eclipse of the sun in spite of using primitive eye protection may cause irreversible retinal damage. Return of visual acuity to 5/5 does not always imply complete recovery because of persistent central scotoma.

Bilateral Neuroretinitis in Cat Scratch Disease with Exudative, Obliterative Vasculitis in the Optic Disc.

PubMed

Tagawa, Yoshiaki; Suzuki, Yasuo; Sakaguchi, Takatoshi; Endoh, Hiroki; Yokoi, Masahiko; Kase, Manabu

2014-01-01

A 29-year-old fisherman exhibited optic disc oedema and peripapillary retinal detachment in the right eye, whereas in the left eye, optic atrophy and intraretinal exudates were already observed on first examination. About 6 months earlier, he noticed blurred vision of the left eye but took no medication. Visual acuity was 0.4 OD and 0.01 OS. Perimetry showed a large lower-half field defect with sparing 10° central field in the right eye and a large central scotoma in the left eye. Fluorescein angiography showed existence of arteriole or capillary nonperfusion and hyperpermeability of surrounding capillaries. Since serological examinations showed positive Bartonella immunoglobulin G (IgG) and other causes of neuroretinitis (NR) were excluded, NR in the present case was caused by cat scratch disease (CSD). Optic atrophy appeared 2 weeks after onset. Optical coherence tomography 13 weeks after onset revealed severe loss of retinal nerve fibre layer (RNFL) superior and nasal to the optic disc in both eyes and temporal in the left eye. Visual acuity of the right eye improved to 1.2 by the treatment, whereas visual field defects were persistent. CSD-NR in the present case developed abrupt appearance of optic atrophy with severe RNFL loss in the right eye, which was elicited by exudative, obliterative vasculitis in the superficial layer of the optic disc.

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

PubMed

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

2004-06-01

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

The Chinese American Eye Study: Design and Methods

PubMed Central

Varma, Rohit; Hsu, Chunyi; Wang, Dandan; Torres, Mina; Azen, Stanley P.

2016-01-01

Purpose To summarize the study design, operational strategies and procedures of the Chinese American Eye Study (CHES), a population-based assessment of the prevalence of visual impairment, ocular disease, and visual functioning in Chinese Americans. Methods This population-based, cross-sectional study, included 4,570 Chinese, 50 years and older, residing in the city of Monterey Park, California. Each eligible participant completed a detailed interview and eye examination. The interview included an assessment of demographic, behavioral, and ocular risk factors and health-related and vision-related quality of life. The eye examination included measurements of visual acuity, intraocular pressure, visual fields, fundus and optic disc photography, a detailed anterior and posterior segment examination, and measurements of blood pressure, glycosylated hemoglobin levels, and blood glucose levels. Results The objectives of the CHES are to obtain prevalence estimates of visual impairment, refractive error, diabetic retinopathy, open-angle and angle-closure glaucoma, lens opacities, and age-related macular degeneration in Chinese-Americans. In addition, outcomes include effect estimates for risk factors associated with eye diseases. Lastly, CHES will investigate the genetic determinates of myopia and glaucoma. Conclusion The CHES will provide information about the prevalence and risk factors of ocular diseases in one of the fastest growing minority groups in the United States. PMID:24044409

Spatial attention improves reliability of fMRI retinotopic mapping signals in occipital and parietal cortex

PubMed Central

Bressler, David W.; Silver, Michael A.

2010-01-01

Spatial attention improves visual perception and increases the amplitude of neural responses in visual cortex. In addition, spatial attention tasks and fMRI have been used to discover topographic visual field representations in regions outside visual cortex. We therefore hypothesized that requiring subjects to attend to a retinotopic mapping stimulus would facilitate the characterization of visual field representations in a number of cortical areas. In our study, subjects attended either a central fixation point or a wedge-shaped stimulus that rotated about the fixation point. Response reliability was assessed by computing coherence between the fMRI time series and a sinusoid with the same frequency as the rotating wedge stimulus. When subjects attended to the rotating wedge instead of ignoring it, the reliability of retinotopic mapping signals increased by approximately 50% in early visual cortical areas (V1, V2, V3, V3A/B, V4) and ventral occipital cortex (VO1) and by approximately 75% in lateral occipital (LO1, LO2) and posterior parietal (IPS0, IPS1 and IPS2) cortical areas. Additionally, one 5-minute run of retinotopic mapping in the attention-to-wedge condition produced responses as reliable as the average of three to five (early visual cortex) or more than five (lateral occipital, ventral occipital, and posterior parietal cortex) attention-to-fixation runs. These results demonstrate that allocating attention to the retinotopic mapping stimulus substantially reduces the amount of scanning time needed to determine the visual field representations in occipital and parietal topographic cortical areas. Attention significantly increased response reliability in every cortical area we examined and may therefore be a general mechanism for improving the fidelity of neural representations of sensory stimuli at multiple levels of the cortical processing hierarchy. PMID:20600961

Visual disability rates in a ten-year cohort of patients with anterior visual pathway meningiomas.

PubMed

Bor-Shavit, Elite; Hammel, Naama; Nahum, Yoav; Rappaport, Zvi Harry; Stiebel-Kalish, Hadas

2015-01-01

To examine the visual outcome of anterior visual pathway meningioma (AVPM) patients followed for at least one year. Data were collected on demographics, clinical course and management. Visual disability was classified at the first and last examination as follows: I--no visual disability; II--mild visual defect in one eye; III--mild visual defect in both eyes; IV--loss of driver's license; V--legally blind. Eight-one AVPM patients had their tumor originate in the clinoid process in 23 (28%), sphenoid-wing area in 18 (22%), cavernous sinus in 15 (19%), tuberculum sellae in 8 (10%), and mixed in 17 (21%). On last examination, 46 patients (57%) had good visual acuity in one or both eyes (Class I or II) and 17 (21%) were mildly affected in both eyes. The rate of Class IV disability was 16%, and Class V disability was 6%. Attention needs to be addressed to the considerable proportion of patients with AVPM (22% in this study) who may lose their driver's license or become legally blind. Occupational therapists should play an important role in the multidisciplinary management of those patients to help them adapt to their new physical and social situation. Anterior visual pathway meningiomas (AVPMs) are commonly not life-threatening but they can lead to profound visual disability, especially when the tumor originates in the tuberculum sellae and cavernous sinus. Particular attention should be paid to visual acuity and visual field deficits, as these can profoundly affect the patient's quality of life including ability to drive and activities of daily living. The interdisciplinary management of patients with AVPM should include the neurosurgeon, neuro-ophthalmologist and occupational therapist. Also, early intervention by the occupational therapist can help patients adapt to their current physical and social situation and return to everyday tasks more rapidly.

The second visual area in the marmoset monkey: visuotopic organisation, magnification factors, architectonical boundaries, and modularity.

PubMed

Rosa, M G; Fritsches, K A; Elston, G N

1997-11-03

The organisation of the second visual area (V2) in marmoset monkeys was studied by means of extracellular recordings of responses to visual stimulation and examination of myelin- and cytochrome oxidase-stained sections. Area V2 forms a continuous cortical belt of variable width (1-2 mm adjacent to the foveal representation of V1, and 3-3.5 mm near the midline and on the tentorial surface) bordering V1 on the lateral, dorsal, medial, and tentorial surfaces of the occipital lobe. The total surface area of V2 is approximately 100 mm2, or about 50% of the surface area of V1 in the same individuals. In each hemisphere, the receptive fields of V2 neurones cover the entire contralateral visual hemifield, forming an ordered visuotopic representation. As in other simians, the dorsal and ventral halves of V2 represent the lower and upper contralateral quadrants, respectively, with little invasion of the ipsilateral hemifield. The representation of the vertical meridian forms the caudal border of V2, with V1, whereas a field discontinuity approximately coincident with the horizontal meridian forms the rostral border of V2, with other visually responsive areas. The bridge of cortex connecting dorsal and ventral V2 contains neurones with receptive fields centred within 1 degree of the centre of the fovea. The visuotopy, size, shape and location of V2 show little variation among individuals. Analysis of cortical magnification factor (CMF) revealed that the V2 map of the visual field is highly anisotropic: for any given eccentricity, the CMF is approximately twice as large in the dimension parallel to the V1/V2 border as it is perpendicular to this border. Moreover, comparison of V2 and V1 in the same individuals demonstrated that the representation of the central visual field is emphasised in V2, relative to V1. Approximately half of the surface area of V2 is dedicated to the representation of the central 5 degrees of the visual field. Calculations based on the CMF, receptive field scatter, and receptive field size revealed that the point-image size measured parallel to the V1/V2 border (2-3 mm) equals the width of a full cycle of cytochrome oxidase stripes in V2, suggesting a close correspondence between physiological and anatomical estimates of the dimensions of modular components in this area.

Impact of Visual Field Loss on Health-Related Quality of Life in Glaucoma

PubMed Central

McKean-Cowdin, Roberta; Wang, Ying; Wu, Joanne; Azen, Stanley P.; Varma, Rohit

2016-01-01

Purpose To examine the association between health-related quality of life (HRQOL) and visual field (VF) loss in participants with open-angle glaucoma (OAG) in the Los Angeles Latino Eye Study (LALES). Design Population-based cross-sectional study. Participants Two hundred thirteen participants with OAG and 2821 participants without glaucoma or VF loss. Methods Participants in the LALES—a population-based prevalence study of eye disease in Latinos 40 years and older, residing in Los Angeles, California—underwent a detailed eye examination including an assessment of their VF using the Humphrey Automated Field Analyzer (Swedish interactive thresholding algorithm Standard 24-2). Open-angle glaucoma was determined by clinical examination. Mean deviation scores were used to assess severity of VF loss. Health-related QOL was assessed by the Medical Outcomes Study 12-item Short-Form Health Survey (SF-12) and 25-item National Eye Institute Visual Function Questionnaire (NEI-VFQ-25). Linear regression and analysis of covariance were used to assess the relationship between HRQOL scores and VF loss after adjusting for sociodemographic variables and visual acuity. Main Outcome Measures The 25-item NEI-VFQ and SF-12 scores. Results A trend of worse NEI-VFQ-25 scores for most subscales was observed with worse VF loss (using both monocular and calculated binocular data). Open-angle glaucoma participants with VF loss had lower scores than participants with no VF loss. This association was also present in participants who were previously undiagnosed and untreated for OAG (N = 160). Participants with any central VF loss had lower NEI-VFQ-25 scores than those with unilateral or bilateral peripheral VF loss. There was no significant impact of severity or location of VF loss on SF-12 scores. Conclusion Greater severity of VF loss in persons with OAG impacts vision-related QOL. This impact was present in persons who were previously unaware that they had glaucoma. Prevention of VF loss in persons with glaucoma is likely to reduce loss of vision-related QOL. PMID:17997485

Effect of Ginkgo biloba on visual field and contrast sensitivity in Chinese patients with normal tension glaucoma: a randomized, crossover clinical trial.

PubMed

Guo, Xinxing; Kong, Xiangbin; Huang, Rui; Jin, Ling; Ding, Xiaohu; He, Mingguang; Liu, Xing; Patel, Mehul Chimanlal; Congdon, Nathan G

2014-01-07

We evaluated the effect of ginkgo biloba extract on visual field defect and contrast sensitivity in a Chinese cohort with normal tension glaucoma. In this prospective, randomized, placebo-controlled crossover study, patients newly diagnosed with normal tension glaucoma, either in a tertiary glaucoma clinic (n = 5) or in a cohort undergoing routine general physical examinations in a primary care clinic (n = 30), underwent two 4-week phases of treatment, separated by a washout period of 8 weeks. Randomization determined whether ginkgo biloba extract (40 mg, 3 times per day) or placebo (identical-appearing tablets) was received first. Primary outcomes were change in contrast sensitivity and mean deviation on 24-2 SITA standard visual field testing, while secondary outcomes included IOP and self-reported adverse events. A total of 35 patients with mean age 63.7 (6.5) years were randomized to the ginkgo biloba extract-placebo (n = 18) or the placebo-ginkgo biloba extract (n = 17) sequence. A total of 28 patients (80.0%, 14 in each group) who completed testing did not differ at baseline in age, sex, visual field mean deviation, contrast sensitivity, IOP, or blood pressure. Changes in visual field and contrast sensitivity did not differ by treatment received or sequence (P > 0.2 for all). Power to have detected a difference in mean defect as large as previously reported was 80%. In contrast to some previous reports, ginkgo biloba extract treatment had no effect on mean defect or contrast sensitivity in this group of normal tension glaucoma patients. (http://www.chictr.org number, ChiCTR-TRC-08000724).

Visual field defects and retinal nerve fiber imaging in patients with obstructive sleep apnea syndrome and in healthy controls.

PubMed

Casas, Paula; Ascaso, Francisco J; Vicente, Eugenio; Tejero-Garcés, Gloria; Adiego, María I; Cristóbal, José A

2018-03-02

To assess the retinal sensitivity in obstructive sleep apnea hypopnea syndrome (OSAHS) patients evaluated with standard automated perimetry (SAP). And to correlate the functional SAP results with structural parameters obtained with optical coherence tomography (OCT). This prospective, observational, case-control study consisted of 63 eyes of 63 OSAHS patients (mean age 51.7 ± 12.7 years, best corrected visual acuity ≥20/25, refractive error less than three spherical or two cylindrical diopters, and intraocular pressure < 21 mmHg) who were enrolled and compared with 38 eyes of 38 age-matched controls. Peripapillary retinal nerve fiber layer (RNFL) thickness was measured by Stratus OCT and SAP sensitivities and indices were explored with Humphrey Field Analyzer perimeter. Correlations between functional and structural parameters were calculated, as well as the relationship between ophthalmologic and systemic indices in OSAHS patients. OSAHS patients showed a significant reduction of the sensitivity for superior visual field division (p = 0.034, t-student test). When dividing the OSAHS group in accordance with the severity of the disease, nasal peripapillary RNFL thickness was significantly lower in severe OSAHS than that in controls and mild-moderate cases (p = 0.031 and p = 0.016 respectively, Mann-Whitney U test). There were no differences between groups for SAP parameters. We found no correlation between structural and functional variables. The central visual field sensitivity of the SAP revealed a poor Pearson correlation with the apnea-hipopnea index (0.284, p = 0.024). Retinal sensitivity show minor differences between healthy subjects and OSAHS. Functional deterioration in OSAHS patients is not easy to demonstrate with visual field examination.

Different Roles for Honey Bee Mushroom Bodies and Central Complex in Visual Learning of Colored Lights in an Aversive Conditioning Assay

PubMed Central

Plath, Jenny A.; Entler, Brian V.; Kirkerud, Nicholas H.; Schlegel, Ulrike; Galizia, C. Giovanni; Barron, Andrew B.

2017-01-01

The honey bee is an excellent visual learner, but we know little about how and why it performs so well, or how visual information is learned by the bee brain. Here we examined the different roles of two key integrative regions of the brain in visual learning: the mushroom bodies and the central complex. We tested bees' learning performance in a new assay of color learning that used electric shock as punishment. In this assay a light field was paired with electric shock. The other half of the conditioning chamber was illuminated with light of a different wavelength and not paired with shocks. The unrestrained bee could run away from the light stimulus and thereby associate one wavelength with punishment, and the other with safety. We compared learning performance of bees in which either the central complex or mushroom bodies had been transiently inactivated by microinjection of the reversible anesthetic procaine. Control bees learned to escape the shock-paired light field and to spend more time in the safe light field after a few trials. When ventral lobe neurons of the mushroom bodies were silenced, bees were no longer able to associate one light field with shock. By contrast, silencing of one collar region of the mushroom body calyx did not alter behavior in the learning assay in comparison to control treatment. Bees with silenced central complex neurons did not leave the shock-paired light field in the middle trials of training, even after a few seconds of being shocked. We discussed how mushroom bodies and the central complex both contribute to aversive visual learning with an operant component. PMID:28611605

Visual experience sculpts whole-cortex spontaneous infraslow activity patterns through an Arc-dependent mechanism

PubMed Central

Kraft, Andrew W.; Mitra, Anish; Bauer, Adam Q.; Raichle, Marcus E.; Culver, Joseph P.; Lee, Jin-Moo

2017-01-01

Decades of work in experimental animals has established the importance of visual experience during critical periods for the development of normal sensory-evoked responses in the visual cortex. However, much less is known concerning the impact of early visual experience on the systems-level organization of spontaneous activity. Human resting-state fMRI has revealed that infraslow fluctuations in spontaneous activity are organized into stereotyped spatiotemporal patterns across the entire brain. Furthermore, the organization of spontaneous infraslow activity (ISA) is plastic in that it can be modulated by learning and experience, suggesting heightened sensitivity to change during critical periods. Here we used wide-field optical intrinsic signal imaging in mice to examine whole-cortex spontaneous ISA patterns. Using monocular or binocular visual deprivation, we examined the effects of critical period visual experience on the development of ISA correlation and latency patterns within and across cortical resting-state networks. Visual modification with monocular lid suturing reduced correlation between left and right cortices (homotopic correlation) within the visual network, but had little effect on internetwork correlation. In contrast, visual deprivation with binocular lid suturing resulted in increased visual homotopic correlation and increased anti-correlation between the visual network and several extravisual networks, suggesting cross-modal plasticity. These network-level changes were markedly attenuated in mice with genetic deletion of Arc, a gene known to be critical for activity-dependent synaptic plasticity. Taken together, our results suggest that critical period visual experience induces global changes in spontaneous ISA relationships, both within the visual network and across networks, through an Arc-dependent mechanism. PMID:29087327

The language of arithmetic across the hemispheres: An event-related potential investigation.

PubMed

Dickson, Danielle S; Federmeier, Kara D

2017-05-01

Arithmetic expressions, like verbal sentences, incrementally lead readers to anticipate potential appropriate completions. Existing work in the language domain has helped us understand how the two hemispheres differently participate in and contribute to the cognitive process of sentence reading, but comparatively little work has been done with mathematical equation processing. In this study, we address this gap by examining the ERP response to provided answers to simple multiplication problems, which varied both in levels of correctness (given an equation context) and in visual field of presentation (joint attention in central presentation, or biased processing to the left or right hemisphere through contralateral visual field presentation). When answers were presented to any of the visual fields (hemispheres), there was an effect of correctness prior to the traditional N400 timewindow, which we interpret as a P300 in response to a detected target item (the correct answer). In addition to this response, equation answers also elicited a late positive complex (LPC) for incorrect answers. Notably, this LPC effect was most prominent in the left visual field (right hemisphere), and it was also sensitive to the confusability of the wrong answer - incorrect answers that were closely related to the correct answer elicited a smaller LPC. This suggests a special, prolonged role for the right hemisphere during answer evaluation. Copyright © 2017 Elsevier B.V. All rights reserved.

Comparison of Matrix Frequency-Doubling Technology (FDT) Perimetry with the SWEDISH Interactive Thresholding Algorithm (SITA) Standard Automated Perimetry (SAP) in Mild Glaucoma.

PubMed

Doozandeh, Azadeh; Irandoost, Farnoosh; Mirzajani, Ali; Yazdani, Shahin; Pakravan, Mohammad; Esfandiari, Hamed

2017-01-01

This study aimed to compare second-generation frequency-doubling technology (FDT) perimetry with standard automated perimetry (SAP) in mild glaucoma. Forty-seven eyes of 47 participants who had mild visual field defect by SAP were included in this study. All participants were examined using SITA 24-2 (SITA-SAP) and matrix 24-2 (Matrix-FDT). The correlations of global indices and the number of defects on pattern deviation (PD) plots were determined. Agreement between two sets regarding the stage of visual field damage was assessed. Pearson's correlation, intra-cluster comparison, paired t-test, and 95% limit of agreement were calculated. Although there was no significant difference between global indices, the agreement between the two devices regarding the global indices was weak (the limit of agreement for mean deviation was -6.08 to 6.08 and that for pattern standard deviation was -4.42 to 3.42). The agreement between SITA-SAP and Matrix-FDT regarding the Glaucoma Hemifield Test (GHT) and the number of defective points in each quadrant and staging of the visual field damage was also weak. Because the correlation between SITA-SAP and Matrix-FDT regarding global indices, GHT, number of defective points, and stage of the visual field damage in mild glaucoma is weak, Matrix-FDT cannot be used interchangeably with SITA-SAP in the early stages of glaucoma.

Car driving in schizophrenia: can visual memory and organization make a difference?

PubMed

Lipskaya-Velikovsky, Lena; Kotler, Moshe; Weiss, Penina; Kaspi, Maya; Gamzo, Shimrit; Ratzon, Navah

2013-09-01

Driving is a meaningful occupation which is ascribed to functional independence in schizophrenia. Although it is estimated that individuals with schizophrenia have two times more traffic accidents, little research has been done in this field. Present research explores differences in mental status, visual working memory and visual organization between drivers and non-drivers with schizophrenia in comparison to healthy drivers. There were three groups in the study: 20 drivers with schizophrenia, 20 non-driving individuals with schizophrenia and 20 drivers without schizophrenia (DWS). Visual perception was measured with Rey-Osterrieth Complex Figure test and a general cognitive status with Mini-Mental State Examination. The general cognitive status predicted actual driving situation in people with schizophrenia. No statistically significant differences were found between driving and non-driving persons with schizophrenia on any of the visual parameters tested, although these abilities were significantly lower than those of DWS. The research demonstrates that impairment of visual abilities does not prevent people with schizophrenia from driving and emphasizes the importance of general cognitive status for complex and multidimensional everyday tasks. The findings support the need for further investigation in the field of car driving for this population - a move that will considerably contribute to the participation and well-being. Implication for Rehabilitation Unique approach for driving evaluation in schizophrenia should be designed since direct applications of knowledge and practice acquired from other populations are not reliable. This research demonstrates that visual perception deficits in schizophrenia do not prevent clients from driving, and general cognitive status appeared to be a valid determinant for actual driving. We recommended usage of a general test of cognition such as Mini-Mental State Examination, or conjunction number of cognitive factors such as executive functions (e.g., Trail Making Test) and attention (e.g., Continuous Performance Test) in addition to spatial-visual ability tests (e.g., Rey-Osterrieth Complex Figure test) for considering driving status in schizophrenia.

Re-examining overlap between tactile and visual motion responses within hMT+ and STS

PubMed Central

Jiang, Fang; Beauchamp, Michael S.; Fine, Ione

2015-01-01

Here we examine overlap between tactile and visual motion BOLD responses within the human MT+ complex. Although several studies have reported tactile responses overlapping with hMT+, many used group average analyses, leaving it unclear whether these responses were restricted to sub-regions of hMT+. Moreover, previous studies either employed a tactile task or passive stimulation, leaving it unclear whether or not tactile responses in hMT+ are simply the consequence of visual imagery. Here we carried out a replication of one of the classic papers finding tactile responses in hMT+ (Hagen et al. 2002). We mapped MT and MST in individual subjects using visual field localizers. We then examined responses to tactile motion on the arm, either presented passively or in the presence of a visual task performed at fixation designed to minimize visualization of the concurrent tactile stimulation. To our surprise, without a visual task, we found only weak tactile motion responses in MT (6% of voxels showing tactile responses) and MST (2% of voxels). With an unrelated visual task designed to withdraw attention from the tactile modality, responses in MST reduced to almost nothing (<1% regions). Consistent with previous results, we did observe tactile responses in STS regions superior and anterior to hMT+. Despite the lack of individual overlap, group averaged responses produced strong spurious overlap between tactile and visual motion responses within hMT+ that resembled those observed in previous studies. The weak nature of tactile responses in hMT+ (and their abolition by withdrawal of attention) suggests that hMT+ may not serve as a supramodal motion processing module. PMID:26123373

Unilateral retinitis pigmentosa. A case report.

PubMed

Nazar, C; Feldman, M; González, R; Espinoza, R

2017-06-01

A 27-year-old woman with a history of nyctalopia and constriction of visual field of the right eye. The ophthalmological examination showed a visual field and electroretinogram that were compatible with unilateral retinitis pigmentosa (RP). After a one year follow-up, the unilateral condition remained. Unilateral retinitis pigmentosa is a rare condition, with a frequency between 0.2%-5% of the RP. It mainly affects women and older age groups than bilateral RP. For a definitive diagnosis, it is necessary to have a funduscopy and electroretinogram (ERG) altered unilaterally, and exclude infectious, inflammatory, and vascular causes. Copyright © 2016 Sociedad Española de Oftalmología. Publicado por Elsevier España, S.L.U. All rights reserved.

Reaching nearby sources: comparison between real and virtual sound and visual targets

PubMed Central

Parseihian, Gaëtan; Jouffrais, Christophe; Katz, Brian F. G.

2014-01-01

Sound localization studies over the past century have predominantly been concerned with directional accuracy for far-field sources. Few studies have examined the condition of near-field sources and distance perception. The current study concerns localization and pointing accuracy by examining source positions in the peripersonal space, specifically those associated with a typical tabletop surface. Accuracy is studied with respect to the reporting hand (dominant or secondary) for auditory sources. Results show no effect on the reporting hand with azimuthal errors increasing equally for the most extreme source positions. Distance errors show a consistent compression toward the center of the reporting area. A second evaluation is carried out comparing auditory and visual stimuli to examine any bias in reporting protocol or biomechanical difficulties. No common bias error was observed between auditory and visual stimuli indicating that reporting errors were not due to biomechanical limitations in the pointing task. A final evaluation compares real auditory sources and anechoic condition virtual sources created using binaural rendering. Results showed increased azimuthal errors, with virtual source positions being consistently overestimated to more lateral positions, while no significant distance perception was observed, indicating a deficiency in the binaural rendering condition relative to the real stimuli situation. Various potential reasons for this discrepancy are discussed with several proposals for improving distance perception in peripersonal virtual environments. PMID:25228855

Visual orientation by the crown-of-thorns starfish ( Acanthaster planci)

NASA Astrophysics Data System (ADS)

Petie, Ronald; Hall, Michael R.; Hyldahl, Mia; Garm, Anders

2016-12-01

Photoreception in echinoderms has been known for over 200 years, but their visual capabilities remain poorly understood. As has been reported for some asteroids, the crown-of-thorns starfish ( Acanthaster planci) possess a seemingly advanced eye at the tip of each of its 7-23 arms. With such an array of eyes, the starfish can integrate a wide field of view of its surroundings. We hypothesise that, at close range, orientation and directional movements of the crown-of-thorns starfish are visually guided. In this study, the eyes and vision of A. planci were examined by means of light microscopy, electron microscopy, underwater goniometry, electroretinograms and behavioural experiments in the animals' natural habitat. We found that only animals with intact vision could orient to a nearby coral reef, whereas blinded animals, with olfaction intact, walked in random directions. The eye had peak sensitivity in the blue part (470 nm) of the visual spectrum and a narrow, horizontal visual field of approximately 100° wide and 30° high. With approximately 250 ommatidia in each adult compound eye and average interommatidial angles of 8°, crown-of-thorns starfish have the highest spatial resolution of any starfish studied to date. In addition, they have the slowest vision of all animals examined thus far, with a flicker fusion frequency of only 0.6-0.7 Hz. This may be adaptive as fast vision is not required for the detection of stationary objects such as reefs. In short, the eyes seem optimised for detecting large, dark, stationary objects contrasted against an ocean blue background. Our results show that the visual sense of the crown-of-thorns starfish is much more elaborate than has been thus far appreciated and is essential for orientation and localisation of suitable habitats.

Characterizing head motion in three planes during combined visual and base of support disturbances in healthy and visually sensitive subjects.

PubMed

Keshner, E A; Dhaher, Y

2008-07-01

Multiplanar environmental motion could generate head instability, particularly if the visual surround moves in planes orthogonal to a physical disturbance. We combined sagittal plane surface translations with visual field disturbances in 12 healthy (29-31 years) and 3 visually sensitive (27-57 years) adults. Center of pressure (COP), peak head angles, and RMS values of head motion were calculated and a three-dimensional model of joint motion was developed to examine gross head motion in three planes. We found that subjects standing quietly in front of a visual scene translating in the sagittal plane produced significantly greater (p<0.003) head motion in yaw than when on a translating platform. However, when the platform was translated in the dark or with a visual scene rotating in roll, head motion orthogonal to the plane of platform motion significantly increased (p<0.02). Visually sensitive subjects having no history of vestibular disorder produced large, delayed compensatory head motion. Orthogonal head motions were significantly greater in visually sensitive than in healthy subjects in the dark (p<0.05) and with a stationary scene (p<0.01). We concluded that motion of the visual field could modify compensatory response kinematics of a freely moving head in planes orthogonal to the direction of a physical perturbation. These results suggest that the mechanisms controlling head orientation in space are distinct from those that control trunk orientation in space. These behaviors would have been missed if only COP data were considered. Data suggest that rehabilitation training can be enhanced by combining visual and mechanical perturbation paradigms.

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

PubMed Central

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

1991-01-01

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

Intercomparison of Registration Techniques and Interactive 3D Visualization of Differential LiDAR from the 2010 El Mayor-Cucapah Earthquake

NASA Astrophysics Data System (ADS)

Banesh, D.; Oskin, M. E.; Mu, A.; Vu, C.; Westerteiger, R.; Krishnan, A.; Hamann, B.; Glennie, C. L.; Hinojosa, A.; Borsa, A. A.

2013-12-01

Differential LiDAR provides unprecedented images of the near-field ground deformation and fault slip due to earthquakes. Here we examine the performance of the Iterative Closest Point (ICP) technique for data registration between pre- and post-earthquake LiDAR point clouds of varying density. We use the 2010 El Mayor-Cucapah data set as our region of interest since this earthquake produced different types of surface ruptures, yielding a variety of deformation styles for analysis. We also test a more simplistic, Chi-Squared minimization approach and find that it produces good results when compared to ICP. We present different techniques for visualizing large vector fields, and show how each method highlights a unique feature in the data set. Dense vector fields are useful when analyzing smaller deformations in the surface. A sparse, averaged vector field analyzes the bigger, overall shifts without interference caused by small details. Flow-based visualizations like Line Integral Convolution (LIC) graphs, provide insight into particular artifacts of data collection, such as distortions due to uncorrected pitch and yaw of the aircraft during the survey. Animations of the vector field establish the direction of movement in the landscape, quickly highlighting areas of interest.

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

PubMed Central

Yahata, Izumi; Kanno, Akitake; Hidaka, Hiroshi; Sakamoto, Shuichi; Nakasato, Nobukazu; Kawashima, Ryuta; Katori, Yukio

2017-01-01

The effects of visual speech (the moving image of the speaker’s face uttering speech sound) on early auditory evoked fields (AEFs) were examined using a helmet-shaped magnetoencephalography system in 12 healthy volunteers (9 males, mean age 35.5 years). AEFs (N100m) in response to the monosyllabic sound /be/ were recorded and analyzed under three different visual stimulus conditions, the moving image of the same speaker’s face uttering /be/ (congruent visual stimuli) or uttering /ge/ (incongruent visual stimuli), and visual noise (still image processed from speaker’s face using a strong Gaussian filter: control condition). On average, latency of N100m was significantly shortened in the bilateral hemispheres for both congruent and incongruent auditory/visual (A/V) stimuli, compared to the control A/V condition. However, the degree of N100m shortening was not significantly different between the congruent and incongruent A/V conditions, despite the significant differences in psychophysical responses between these two A/V conditions. Moreover, analysis of the magnitudes of these visual effects on AEFs in individuals showed that the lip-reading effects on AEFs tended to be well correlated between the two different audio-visual conditions (congruent vs. incongruent visual stimuli) in the bilateral hemispheres but were not significantly correlated between right and left hemisphere. On the other hand, no significant correlation was observed between the magnitudes of visual speech effects and psychophysical responses. These results may indicate that the auditory-visual interaction observed on the N100m is a fundamental process which does not depend on the congruency of the visual information. PMID:28141836

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

PubMed

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

2016-11-09

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

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

PubMed

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

2017-07-01

The aim of this study is to relate areas of the visual field to functional difficulties to inform the development of a binocular visual field assessment that can reflect the functional consequences of visual field loss. Fifty-two participants with peripheral visual field loss undertook binocular assessment of visual fields using the 30-2 and 60-4 SITA Fast programs on the Humphrey Field Analyser, and mean thresholds were derived. Binocular visual acuity, contrast sensitivity and near reading performance were also determined. Self-reported overall and mobility function were assessed using the Dutch ICF Activity Inventory. Greater visual field loss (0-60°) was associated with worse self-reported function both overall (R 2 = 0.50; p < 0.0001), and for mobility (R 2 = 0.64; p < 0.0001). Central (0-30°) and peripheral (30-60°) visual field areas were similarly related to mobility function (R 2 = 0.61, p < 0.0001 and R 2 = 0.63, p < 0.0001 respectively), although the peripheral (30-60°) visual field was the best predictor of mobility self-reported function in multiple regression analyses. Superior and inferior visual field areas related similarly to mobility function (R 2 = 0.56, p < 0.0001 and R 2 = 0.67, p < 0.0001 respectively). The inferior field was found to be the best predictor of mobility function in multiple regression analysis. Mean threshold of the binocular visual field to 60° eccentricity is a good predictor of self-reported function overall, and particularly of mobility function. Both the central (0-30°) and peripheral (30-60°) mean threshold are good predictors of self-reported function, but the peripheral (30-0°) field is a slightly better predictor of mobility function, and should not be ignored when considering functional consequences of field loss. The inferior visual field is a slightly stronger predictor of perceived overall and mobility function than the superior field. © 2017 The Authors Ophthalmic & Physiological Optics © 2017 The College of Optometrists.

Visualizing Simulated Electrical Fields from Electroencephalography and Transcranial Electric Brain Stimulation: A Comparative Evaluation

PubMed Central

Eichelbaum, Sebastian; Dannhauer, Moritz; Hlawitschka, Mario; Brooks, Dana; Knösche, Thomas R.; Scheuermann, Gerik

2014-01-01

Electrical activity of neuronal populations is a crucial aspect of brain activity. This activity is not measured directly but recorded as electrical potential changes using head surface electrodes (electroencephalogram - EEG). Head surface electrodes can also be deployed to inject electrical currents in order to modulate brain activity (transcranial electric stimulation techniques) for therapeutic and neuroscientific purposes. In electroencephalography and noninvasive electric brain stimulation, electrical fields mediate between electrical signal sources and regions of interest (ROI). These fields can be very complicated in structure, and are influenced in a complex way by the conductivity profile of the human head. Visualization techniques play a central role to grasp the nature of those fields because such techniques allow for an effective conveyance of complex data and enable quick qualitative and quantitative assessments. The examination of volume conduction effects of particular head model parameterizations (e.g., skull thickness and layering), of brain anomalies (e.g., holes in the skull, tumors), location and extent of active brain areas (e.g., high concentrations of current densities) and around current injecting electrodes can be investigated using visualization. Here, we evaluate a number of widely used visualization techniques, based on either the potential distribution or on the current-flow. In particular, we focus on the extractability of quantitative and qualitative information from the obtained images, their effective integration of anatomical context information, and their interaction. We present illustrative examples from clinically and neuroscientifically relevant cases and discuss the pros and cons of the various visualization techniques. PMID:24821532

Evaluation of two methods for quantifying passeriform lice

PubMed Central

Koop, Jennifer A. H.; Clayton, Dale H.

2013-01-01

Two methods commonly used to quantify ectoparasites on live birds are visual examination and dust-ruffling. Visual examination provides an estimate of ectoparasite abundance based on an observer’s timed inspection of various body regions on a bird. Dust-ruffling involves application of insecticidal powder to feathers that are then ruffled to dislodge ectoparasites onto a collection surface where they can then be counted. Despite the common use of these methods in the field, the proportion of actual ectoparasites they account for has only been tested with Rock Pigeons (Columba livia), a relatively large-bodied species (238–302 g) with dense plumage. We tested the accuracy of the two methods using European Starlings (Sturnus vulgaris; ~75 g). We first quantified the number of lice (Brueelia nebulosa) on starlings using visual examination, followed immediately by dust-ruffling. Birds were then euthanized and the proportion of lice accounted for by each method was compared to the total number of lice on each bird as determined with a body-washing method. Visual examination and dust-ruffling each accounted for a relatively small proportion of total lice (14% and 16%, respectively), but both were still significant predictors of abundance. The number of lice observed by visual examination accounted for 68% of the variation in total abundance. Similarly, the number of lice recovered by dust-ruffling accounted for 72% of the variation in total abundance. Our results show that both methods can be used to reliably quantify the abundance of lice on European Starlings and other similar-sized passerines. PMID:24039328

Developing Matlab scripts for image analysis and quality assessment

NASA Astrophysics Data System (ADS)

Vaiopoulos, A. D.

2011-11-01

Image processing is a very helpful tool in many fields of modern sciences that involve digital imaging examination and interpretation. Processed images however, often need to be correlated with the original image, in order to ensure that the resulting image fulfills its purpose. Aside from the visual examination, which is mandatory, image quality indices (such as correlation coefficient, entropy and others) are very useful, when deciding which processed image is the most satisfactory. For this reason, a single program (script) was written in Matlab language, which automatically calculates eight indices by utilizing eight respective functions (independent function scripts). The program was tested in both fused hyperspectral (Hyperion-ALI) and multispectral (ALI, Landsat) imagery and proved to be efficient. Indices were found to be in agreement with visual examination and statistical observations.

Evolution and ecology of retinal photoreception in early vertebrates.

PubMed

Collin, Shaun P

2010-01-01

Visual ecology or the relationship between the visual system of an animal and its environment has proven to be a crucial research field for establishing general concepts of adaptation, specialization and evolution. The visual neuroscientist is indeed confronted with a plethora of different visual characteristics, each seemingly optimised for each species' ecological niche, but often without a clear understanding of the evolutionary constraints at play. However, before we are able to fully understand the influence(s) of ecology and phylogeny on visual system design in vertebrates, it is first necessary to understand the basic bauplan of key representatives of each taxa. This review examines photoreception in hagfishes, lampreys, cartilaginous fishes and lungfishes with an eye to their ecology using a range of neurobiological methods including anatomy, microspectrophotometry and molecular genetics. These early vertebrates represent critical stages in evolution and surprisingly possess a level of visual complexity that is almost unrivalled in other vertebrates. 2010 S. Karger AG, Basel.

The Sensory Components of High-Capacity Iconic Memory and Visual Working Memory

PubMed Central

Bradley, Claire; Pearson, Joel

2012-01-01

Early visual memory can be split into two primary components: a high-capacity, short-lived iconic memory followed by a limited-capacity visual working memory that can last many seconds. Whereas a large number of studies have investigated visual working memory for low-level sensory features, much research on iconic memory has used more “high-level” alphanumeric stimuli such as letters or numbers. These two forms of memory are typically examined separately, despite an intrinsic overlap in their characteristics. Here, we used a purely sensory paradigm to examine visual short-term memory for 10 homogeneous items of three different visual features (color, orientation and motion) across a range of durations from 0 to 6 s. We found that the amount of information stored in iconic memory is smaller for motion than for color or orientation. Performance declined exponentially with longer storage durations and reached chance levels after ∼2 s. Further experiments showed that performance for the 10 items at 1 s was contingent on unperturbed attentional resources. In addition, for orientation stimuli, performance was contingent on the location of stimuli in the visual field, especially for short cue delays. Overall, our results suggest a smooth transition between an automatic, high-capacity, feature-specific sensory-iconic memory, and an effortful “lower-capacity” visual working memory. PMID:23055993

Change of temporal-order judgment of sounds during long-lasting exposure to large-field visual motion.

PubMed

Teramoto, Wataru; Watanabe, Hiroshi; Umemura, Hiroyuki

2008-01-01

The perceived temporal order of external successive events does not always follow their physical temporal order. We examined the contribution of self-motion mechanisms in the perception of temporal order in the auditory modality. We measured perceptual biases in the judgment of the temporal order of two short sounds presented successively, while participants experienced visually induced self-motion (yaw-axis circular vection) elicited by viewing long-lasting large-field visual motion. In experiment 1, a pair of white-noise patterns was presented to participants at various stimulus-onset asynchronies through headphones, while they experienced visually induced self-motion. Perceived temporal order of auditory events was modulated by the direction of the visual motion (or self-motion). Specifically, the sound presented to the ear in the direction opposite to the visual motion (ie heading direction) was perceived prior to the sound presented to the ear in the same direction. Experiments 2A and 2B were designed to reduce the contributions of decisional and/or response processes. In experiment 2A, the directional cueing of the background (left or right) and the response dimension (high pitch or low pitch) were not spatially associated. In experiment 2B, participants were additionally asked to report which of the two sounds was perceived 'second'. Almost the same results as in experiment 1 were observed, suggesting that the change in temporal order of auditory events during large-field visual motion reflects a change in perceptual processing. Experiment 3 showed that the biases in the temporal-order judgments of auditory events were caused by concurrent actual self-motion with a rotatory chair. In experiment 4, using a small display, we showed that 'pure' long exposure to visual motion without the sensation of self-motion was not responsible for this phenomenon. These results are consistent with previous studies reporting a change in the perceived temporal order of visual or tactile events depending on the direction of self-motion. Hence, large-field induced (ie optic flow) self-motion can affect the temporal order of successive external events across various modalities.

The SCHEIE Visual Field Grading System

PubMed Central

Sankar, Prithvi S.; O’Keefe, Laura; Choi, Daniel; Salowe, Rebecca; Miller-Ellis, Eydie; Lehman, Amanda; Addis, Victoria; Ramakrishnan, Meera; Natesh, Vikas; Whitehead, Gideon; Khachatryan, Naira; O’Brien, Joan

2017-01-01

Objective No method of grading visual field (VF) defects has been widely accepted throughout the glaucoma community. The SCHEIE (Systematic Classification of Humphrey visual fields-Easy Interpretation and Evaluation) grading system for glaucomatous visual fields was created to convey qualitative and quantitative information regarding visual field defects in an objective, reproducible, and easily applicable manner for research purposes. Methods The SCHEIE grading system is composed of a qualitative and quantitative score. The qualitative score consists of designation in one or more of the following categories: normal, central scotoma, paracentral scotoma, paracentral crescent, temporal quadrant, nasal quadrant, peripheral arcuate defect, expansive arcuate, or altitudinal defect. The quantitative component incorporates the Humphrey visual field index (VFI), location of visual defects for superior and inferior hemifields, and blind spot involvement. Accuracy and speed at grading using the qualitative and quantitative components was calculated for non-physician graders. Results Graders had a median accuracy of 96.67% for their qualitative scores and a median accuracy of 98.75% for their quantitative scores. Graders took a mean of 56 seconds per visual field to assign a qualitative score and 20 seconds per visual field to assign a quantitative score. Conclusion The SCHEIE grading system is a reproducible tool that combines qualitative and quantitative measurements to grade glaucomatous visual field defects. The system aims to standardize clinical staging and to make specific visual field defects more easily identifiable. Specific patterns of visual field loss may also be associated with genetic variants in future genetic analysis. PMID:28932621

[Describe and convince: visual rhetoric of cinematography in medicine].

PubMed

Panese, Francesco

2009-01-01

The tools of visualisation occupy a central place in medicine. Far from being simple accessories of glance, they literally constitute objects of medicine. Such empirical acknowledgement and epistemological position open a vast field of investigation: visual technologies of medical knowledge. This article studies the development and transformation of medical objects which have permitted to assess the role of temporality in the epistemology of medicine. It firstly examines the general problem of the relationships between cinema, animated image and medicine and secondly, the contribution of the German doctor Martin Weiser to medical cinematography as a method. Finally, a typology is sketched out organising the variety of the visual technology of movement under the perspective of the development of specific visual techniques in medicine.

Assessment of Central Visual Function in Patients with Retinitis Pigmentosa.

PubMed

Fujiwara, Kohta; Ikeda, Yasuhiro; Murakami, Yusuke; Tachibana, Takashi; Funatsu, Jun; Koyanagi, Yoshito; Nakatake, Shunji; Yoshida, Noriko; Nakao, Shintaro; Hisatomi, Toshio; Yoshida, Shigeo; Yoshitomi, Takeshi; Ishibashi, Tatsuro; Sonoda, Koh-Hei

2018-05-23

In order to clarify the disease progression in retinitis pigmentosa (RP) and its related factors, reliable data on the changes in central visual function in RP are needed. In this longitudinal study, we examined 118 patients who were diagnosed with typical RP. Visual acuity (VA), visual field using a Humphrey Field Analyzer with the central 10-2 SITA-Standard program, and optical coherence tomography measurements were obtained. The slopes, which were derived from serial values of mean deviation (MD), macular sensitivity (MS), or foveal sensitivity (FS) obtained for each eye by a linear mixed model, were used for analysis. MS and FS were calculated as the average retinal sensitivity of 12 and 4 central points respectively. There were statistically significant interactions of times with levels of the central subfield thickness (CST) on the slopes of MS and FS. Compared to the eyes without macular complications, the eyes with macular complications had steeper MD, MS and FS slopes, and this interaction was no significant, but marginal trend for the MS or FS slope (P = 0.10, 0.05, respectively). The central retinal sensitivity (i.e., MS and FS) slopes calculated were effective indices of the progression of central visual function in RP.

Branch retinal arterial occlusion.

PubMed

Subedi, S; Shrestha, C

2010-01-01

Retinal arterial occlusion is an ocular emergency in which visual prognosis is poor mostly due to late presentation of the patient and macular involvement. The casee described, in this report is ane incidence of Branch Retinal Arterial Occlusion in a 22 year old female with grade II Mitral Regurgitation. The patiente presented witha complaint of painless, diminution of vision in the right eyn. She also presented with perception of black shadow in the superior visual fiel n of the same eye5 for five days. There was no significant systemic ord personal history. Her visual acuity at presentation was 6/60 and 6/6 in the right and left eyes,y which did not improve with glasses or pin-hole. Anterior segment including papillary reaction was normal in both eyes while Fundus examination of the right eye revealed retinal whitening inside the inferotemporal vascular arcade that was encroaching foveolar avascular zone. Visual field defect was detected at superonasally inside arhade but Fundus Fluorescence Angiography was normal. An echoycardiograph revealed grade II Mitral Regurgitation. The patient was kept on observation and after two2 days of follow-up, vision in the right eye was improved to 6/6 unaided but visual field defect was remained same.

Scoring nuclear pleomorphism using a visual BoF modulated by a graph structure

NASA Astrophysics Data System (ADS)

Moncayo-Martínez, Ricardo; Romo-Bucheli, David; Arias, Viviana; Romero, Eduardo

2017-11-01

Nuclear pleomorphism has been recognized as a key histological criterium in breast cancer grading systems (such as Bloom Richardson and Nothingham grading systems). However, the nuclear pleomorphism assessment is subjective and presents high inter-reader variability. Automatic algorithms might facilitate quantitative estimation of nuclear variations in shape and size. Nevertheless, the automatic segmentation of the nuclei is difficult and still and open research problem. This paper presents a method using a bag of multi-scale visual features, modulated by a graph structure, to grade nuclei in breast cancer microscopical fields. This strategy constructs hematoxylin-eosin image patches, each containing a nucleus that is represented by a set of visual words in the BoF. The contribution of each visual word is computed by examining the visual words in an associated graph built when projecting the multi-dimensional BoF to a bi-dimensional plane where local relationships are conserved. The methodology was evaluated using 14 breast cancer cases of the Cancer Genome Atlas database. From these cases, a set of 134 microscopical fields was extracted, and under a leave-one-out validation scheme, an average F-score of 0.68 was obtained.

Optic Disc Drusen in Children

PubMed Central

Chang, Melinda Y.; Pineles, Stacy L.

2016-01-01

Optic disc drusen occur in 0.4% of children and consist of acellular intracellular and extracellular deposits that often become calcified over time. They are typically buried early in life and generally become superficial, and therefore visible, later in childhood, at the average age of 12 years. Their main clinical significance lies in the ability of optic disc drusen, particularly when buried, to simulate true optic disc edema. Misdiagnosing drusen as true disc edema may lead to an invasive and unnecessary workup for elevated intracranial pressure. Ancillary testing, including ultrasonography, fluorescein angiography, fundus autofluorescence, and optical coherence tomography, may aid in the correct diagnosis of optic disc drusen. Complications of optic disc drusen in children include visual field defects, hemorrhages, choroidal neovascular membrane, non-arteritic anterior ischemic optic neuropathy, and retinal vascular occlusions. Treatment options for these complications include ocular hypotensive agents for visual field defects and intravitreal anti-vascular endothelial growth factor (anti-VEGF) agents for choroidal neovascular membranes. In most cases, however, children with optic disc drusen can be managed by observation with serial examinations and visual field testing, once true optic disc edema has been excluded. PMID:27033945

Prevention of Blindness: Chronic Glaucoma

ERIC Educational Resources Information Center

Richardson, Kenneth T.

1970-01-01

An evaluation of present screening procedures for chronic open-angle glaucoma includes suggestions for improvement: greater distribution of screening and education, conversion from monophasic to multiphasic screen, and examination of visual fields, optic nerve, and medical history in addition to the tonometry currently done. (KW)

SPECTRAL DOMAIN VERSUS SWEPT SOURCE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY OF THE RETINAL CAPILLARY PLEXUSES IN SICKLE CELL MACULOPATHY.

PubMed

Jung, Jesse J; Chen, Michael H; Frambach, Caroline R; Rofagha, Soraya; Lee, Scott S

2018-01-01

To compare the spectral domain and swept source optical coherence tomography angiography findings in two cases of sickle cell maculopathy. A 53-year-old man and a 24-year-old man both with sickle cell disease (hemoglobin SS) presented with no visual complaints; Humphrey visual field testing demonstrated asymptomatic paracentral scotomas that extended nasally in the involved eyes. Clinical examination and multimodal imaging including spectral domain and swept source optical coherence tomography, and spectral domain optical coherence tomography angiography and swept source optical coherence tomography angiography (Carl Zeiss Meditec Inc, Dublin, CA) were performed. Fundus examination of both patients revealed subtle thinning of the macula. En-face swept source optical coherence tomography confirmed the extent of the thinning correlating with the functional paracentral scotomas on Humphrey visual field. Swept source optical coherence tomography B-scan revealed multiple confluent areas of inner nuclear thinning and significant temporal retinal atrophy. En-face 6 × 6-mm spectral domain optical coherence tomography angiography of the macula demonstrated greater loss of the deep capillary plexus compared with the superficial capillary plexus. Swept source optical coherence tomography angiography 12 × 12-mm imaging captured the same macular findings and loss of both plexuses temporally outside the macula. In these two cases of sickle cell maculopathy, deep capillary plexus ischemia is more extensive within the macula, whereas both the superficial capillary plexus and deep capillary plexus are involved outside the macula likely due to the greater oxygen demands and watershed nature of these areas. Swept source optical coherence tomography angiography clearly demonstrates the angiographic extent of the disease correlating with the Humphrey visual field scotomas and confluent areas of inner nuclear atrophy.

Concentric retinitis pigmentosa: clinicopathologic correlations.

PubMed

Milam, A H; De Castro, E B; Smith, J E; Tang, W X; John, S K; Gorin, M B; Stone, E M; Aguirre, G D; Jacobson, S G

2001-10-01

Progressive concentric (centripetal) loss of vision is one pattern of visual field loss in retinitis pigmentosa. This study provides the first clinicopathologic correlations for this form of retinitis pigmentosa. A family with autosomal dominant concentric retinitis pigmentosa was examined clinically and with visual function tests. A post-mortem eye of an affected 94 year old family member was processed for histopathology and immunocytochemistry with retinal cell specific antibodies. Unrelated simplex/multiplex patients with concentric retinitis pigmentosa were also examined. Affected family members of the eye donor and patients from the other families had prominent peripheral pigmentary retinopathy with more normal appearing central retina, good visual acuity, concentric field loss, normal or near normal rod and cone sensitivity within the preserved visual field, and reduced rod and cone electroretinograms. The eye donor, at age 90, had good acuity and function in a central island. Grossly, the central region of the donor retina appeared thinned but otherwise normal, while the far periphery contained heavy bone spicule pigment. Microscopically the central retina showed photoreceptor outer segment shortening and some photoreceptor cell loss. The mid periphery had a sharp line of demarcation where more central photoreceptors were near normal except for very short outer segments and peripheral photoreceptors were absent. Rods and cones showed abrupt loss of outer segments and cell death at this interface. It is concluded that concentric retinitis pigmentosa is a rare but recognizable phenotype with slowly progressive photoreceptor death from the far periphery toward the central retina. The disease is retina-wide but shows regional variation in severity of degeneration; photoreceptor death is severe in the peripheral retina with an abrupt edge between viable and degenerate photoreceptors. Peripheral to central gradients of unknown retinal molecule(s) may be defective or modify photoreceptor degeneration in concentric retinitis pigmentosa.

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

PubMed

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

2007-06-01

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

Stages of functional processing and the bihemispheric recognition of Japanese Kana script.

PubMed

Yoshizaki, K

2000-04-01

Two experiments were carried out in order to examine the effects of functional steps on the benefits of interhemispheric integration. The purpose of Experiment 1 was to investigate the validity of the Banich (1995a) model, where the benefits of interhemispheric processing increase as the task involves more functional steps. The 16 right-handed subjects were given two types of Hiragana-Katakana script matching tasks. One was the Name Identity (NI) task, and the other was the vowel matching (VM) task, which involved more functional steps compared to the NI task. The VM task required subjects to make a decision whether or not a pair of Katakana-Hiragana scripts had a common vowel. In both tasks, a pair of Kana scripts (Katakana-Hiragana scripts) was tachistoscopically presented in the unilateral visual fields or the bilateral visual fields, where each letter was presented in each visual field. A bilateral visual fields advantage (BFA) was found in both tasks, and the size of this did not differ between the tasks, suggesting that these findings did not support the Banich model. The purpose of Experiment 2 was to examine the effects of imbalanced processing load between the hemispheres on the benefits of interhemispheric integration. In order to manipulate the balance of processing load across the hemispheres, the revised vowel matching (r-VM) task was developed by amending the VM task. The r-VM task was the same as the VM task in Experiment 1, except that a script that has only vowel sound was presented as a counterpart of a pair of Kana scripts. The 24 right-handed subjects were given the r-VM and NI tasks. The results showed that although a BFA showed up in the NI task, it did not in the r-VM task. These results suggested that the balance of processing load between hemispheres would have an influence on the bilateral hemispheric processing.

Fixating at far distance shortens reaction time to peripheral visual stimuli at specific locations.

PubMed

Kokubu, Masahiro; Ando, Soichi; Oda, Shingo

2018-01-18

The purpose of the present study was to examine whether the fixation distance in real three-dimensional space affects manual reaction time to peripheral visual stimuli. Light-emitting diodes were used for presenting a fixation point and four peripheral visual stimuli. The visual stimuli were located at a distance of 45cm and at 25° in the left, right, upper, and lower directions from the sagittal axis including the fixation point. Near (30cm), Middle (45cm), Far (90cm), and Very Far (300cm) fixation distance conditions were used. When one of the four visual stimuli was randomly illuminated, the participants released a button as quickly as possible. Results showed that overall peripheral reaction time decreased as the fixation distance increased. The significant interaction between fixation distance and stimulus location indicated that the effect of fixation distance on reaction time was observed at the left, right, and upper locations but not at the lower location. These results suggest that fixating at far distance would contribute to faster reaction and that the effect is specific to locations in the peripheral visual field. The present findings are discussed in terms of viewer-centered representation, the focus of attention in depth, and visual field asymmetry related to neurological and psychological aspects. Copyright © 2017 Elsevier B.V. All rights reserved.

Directional asymmetries in human smooth pursuit eye movements.

PubMed

Ke, Sally R; Lam, Jessica; Pai, Dinesh K; Spering, Miriam

2013-06-27

Humans make smooth pursuit eye movements to bring the image of a moving object onto the fovea. Although pursuit accuracy is critical to prevent motion blur, the eye often falls behind the target. Previous studies suggest that pursuit accuracy differs between motion directions. Here, we systematically assess asymmetries in smooth pursuit. In experiment 1, binocular eye movements were recorded while observers (n = 20) tracked a small spot of light moving along one of four cardinal or diagonal axes across a featureless background. We analyzed pursuit latency, acceleration, peak velocity, gain, and catch-up saccade latency, number, and amplitude. In experiment 2 (n = 22), we examined the effects of spatial location and constrained stimulus motion within the upper or lower visual field. Pursuit was significantly faster (higher acceleration, peak velocity, and gain) and smoother (fewer and later catch-up saccades) in response to downward versus upward motion in both the upper and the lower visual fields. Pursuit was also more accurate and smoother in response to horizontal versus vertical motion. CONCLUSIONS. Our study is the first to report a consistent up-down asymmetry in human adults, regardless of visual field. Our findings suggest that pursuit asymmetries are adaptive responses to the requirements of the visual context: preferred motion directions (horizontal and downward) are more critical to our survival than nonpreferred ones.

Bohm's Quantum Potential and the Visualization of Molecular Structure

NASA Technical Reports Server (NTRS)

Levit, Creon; Chancellor, Marisa K. (Technical Monitor)

1997-01-01

David Bohm's ontological interpretation of quantum theory can shed light on otherwise counter-intuitive quantum mechanical phenomena including chemical bonding. In the field of quantum chemistry, Richard Bader has shown that the topology of the Laplacian of the electronic charge density characterizes many features of molecular structure and reactivity. Visual and computational examination suggests that the Laplacian of Bader and the quantum potential of Bohm are morphologically equivalent. It appears that Bohmian mechanics and the quantum potential can make chemistry as clear as they makes physics.

The forensic validity of visual analytics

NASA Astrophysics Data System (ADS)

Erbacher, Robert F.

2008-01-01

The wider use of visualization and visual analytics in wide ranging fields has led to the need for visual analytics capabilities to be legally admissible, especially when applied to digital forensics. This brings the need to consider legal implications when performing visual analytics, an issue not traditionally examined in visualization and visual analytics techniques and research. While digital data is generally admissible under the Federal Rules of Evidence [10][21], a comprehensive validation of the digital evidence is considered prudent. A comprehensive validation requires validation of the digital data under rules for authentication, hearsay, best evidence rule, and privilege. Additional issues with digital data arise when exploring digital data related to admissibility and the validity of what information was examined, to what extent, and whether the analysis process was sufficiently covered by a search warrant. For instance, a search warrant generally covers very narrow requirements as to what law enforcement is allowed to examine and acquire during an investigation. When searching a hard drive for child pornography, how admissible is evidence of an unrelated crime, i.e. drug dealing. This is further complicated by the concept of "in plain view". When performing an analysis of a hard drive what would be considered "in plain view" when analyzing a hard drive. The purpose of this paper is to discuss the issues of digital forensics and the related issues as they apply to visual analytics and identify how visual analytics techniques fit into the digital forensics analysis process, how visual analytics techniques can improve the legal admissibility of digital data, and identify what research is needed to further improve this process. The goal of this paper is to open up consideration of legal ramifications among the visualization community; the author is not a lawyer and the discussions are not meant to be inclusive of all differences in laws between states and countries.

Ultra-Widefield Fluorescein Angiography in Intermediate Uveitis.

PubMed

Laovirojjanakul, Wipada; Acharya, Nisha; Gonzales, John A

2017-10-17

To examine associations between pattern of vascular leakage on ultrawide-field fluorescein angiography (UWFFA) and visual acuity, cystoid macular edema (CME), and inflammatory activity in intermediate uveitis. Single center cross-sectional, retrospective review of medical records, spectral domain optical coherence tomography (SD-OCT) and angiographic images of intermediate uveitis patients who underwent UWFFA over a 12-month period. Forty-one eyes from 24 patients were included. Twelve eyes (29%) exhibited peripheral leakage, 26 eyes (64%) had diffuse leakage and three eyes (7%) had no leakage. Diffuse leakage was associated with 0.2 logMAR worse visual acuity than peripheral leakage (p = 0.02). There was no statistically significant difference in the odds of having CME when diffuse leakage was compared to peripheral leakage. UWFFA identifies retinal vascular pathology in intermediate uveitis not present on clinical examination. Diffuse retinal vascular leakage was associated with worse visual acuity when compared to peripheral and no leakage patterns.

Employees' satisfaction as influenced by acoustic and visual privacy in the open office environment

NASA Astrophysics Data System (ADS)

Soules, Maureen Jeanette

The purpose of this study was to examine the relationship between employees' acoustic and visual privacy issues and their perceived satisfaction in their open office work environments while in focus work mode. The study examined the Science Teaching Student Services Building at the University of Minnesota Minneapolis. The building houses instructional classrooms and administrative offices that service UMN students. The Sustainable Post-Occupancy Evaluation Survey was used to collect data on overall privacy conditions, acoustic and visual privacy conditions, and employees' perceived privacy conditions while in their primary workplace. Paired T-tests were used to analyze the relationships between privacy conditions and employees' perceptions of privacy. All hypotheses are supported indicating that the privacy variables are correlated to the employees' perception of satisfaction within the primary workplace. The findings are important because they can be used to inform business leaders, designers, educators and future research in the field of office design.

Thinking in z-space: flatness and spatial narrativity

NASA Astrophysics Data System (ADS)

Zone, Ray

2012-03-01

Now that digital technology has accessed the Z-space in cinema, narrative artistry is at a loss. Motion picture professionals no longer can readily resort to familiar tools. A new language and new linguistics for Z-axis storytelling are necessary. After first examining the roots of monocular thinking in painting, prior modes of visual narrative in twodimensional cinema obviating true binocular stereopsis can be explored, particularly montage, camera motion and depth of field, with historic examples. Special attention is paid to the manner in which monocular cues for depth have been exploited to infer depth on a planar screen. Both the artistic potential and visual limitations of actual stereoscopic depth as a filmmaking language are interrogated. After an examination of the historic basis of monocular thinking in visual culture, a context for artistic exploration of the use of the z-axis as a heightened means of creating dramatic and emotional impact upon the viewer is illustrated.

Orbital complications:diagnosis of different rhinological causes.

PubMed

Matsuba, Yumiko; Strassen, Ulrich; Hofauer, Benedikt; Bas, Murat; Knopf, Andreas

2015-09-01

To evaluate the clinical course of orbital complication using a standardised diagnostic pathway. Seventy-three patients with orbital complications underwent a multimodal diagnostic pathway comprising ENT examination, leucocytes/CRP, CT-/MRI-scanning and disease-related data. Twenty-nine patients suffered from rhinosinusitis, 28 from mucoceles, 13 patients from neoplasms and three patients from rheumatic disorders. Clinical examination diagnosed 60 patients with eyelid swelling, 55 patients with ocular pain, 14 patients with diplopia, 4 patients with exophthalmus, 29 patients with visual field defect and 4 patients with visual loss. The diagnostic pathway identified acute rhinosinusitis with a sensitivity/specificity of 90 %/90 %, mucoceles with 79 %/100 %, neoplasms with 100 %/96 % and granulomatosis with polyangiitis with 100 %/100 %, respectively. All patients left the hospital in good general condition and with regular ocular motility; two patients suffered persistent visual loss. The standardised application of a widely accepted diagnostic pathway reliably distinguishes different causes of orbital complication.

Visual perspective in autobiographical memories: reliability, consistency, and relationship to objective memory performance.

PubMed

Siedlecki, Karen L

2015-01-01

Visual perspective in autobiographical memories was examined in terms of reliability, consistency, and relationship to objective memory performance in a sample of 99 individuals. Autobiographical memories may be recalled from two visual perspectives--a field perspective in which individuals experience the memory through their own eyes, or an observer perspective in which individuals experience the memory from the viewpoint of an observer in which they can see themselves. Participants recalled nine word-cued memories that differed in emotional valence (positive, negative and neutral) and rated their memories on 18 scales. Results indicate that visual perspective was the most reliable memory characteristic overall and is consistently related to emotional intensity at the time of recall and amount of emotion experienced during the memory. Visual perspective is unrelated to memory for words, stories, abstract line drawings or faces.

Structural and Functional Correlates of Visual Field Asymmetry in the Human Brain by Diffusion Kurtosis MRI and Functional MRI

PubMed Central

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

2016-01-01

Human visual performance has been observed to exhibit superiority in localized regions of the visual field across many classes of stimuli. However, the underlying neural mechanisms remain unclear. This study aims to determine if the visual information processing in the human brain is dependent on the location of stimuli in the visual field and the corresponding neuroarchitecture using blood-oxygenation-level-dependent functional MRI (fMRI) and diffusion kurtosis MRI (DKI), respectively in 15 healthy individuals at 3 Tesla. In fMRI, visual stimulation to the lower hemifield showed stronger brain responses and larger brain activation volumes than the upper hemifield, indicative of the differential sensitivity of the human brain across the visual field. In DKI, the brain regions mapping to the lower visual field exhibited higher mean kurtosis but not fractional anisotropy or mean diffusivity when compared to the upper visual field. These results suggested the different distributions of microstructural organization across visual field brain representations. There was also a strong positive relationship between diffusion kurtosis and fMRI responses in the lower field brain representations. In summary, this study suggested the structural and functional brain involvements in the asymmetry of visual field responses in humans, and is important to the neurophysiological and psychological understanding of human visual information processing. PMID:27631541

Cocaine, Appetitive Memory and Neural Connectivity

PubMed Central

Ray, Suchismita

2013-01-01

This review examines existing cognitive experimental and brain imaging research related to cocaine addiction. In section 1, previous studies that have examined cognitive processes, such as implicit and explicit memory processes in cocaine users are reported. Next, in section 2, brain imaging studies are reported that have used chronic users of cocaine as study participants. In section 3, several conclusions are drawn. They are: (a) in cognitive experimental literature, no study has examined both implicit and explicit memory processes involving cocaine related visual information in the same cocaine user, (b) neural mechanisms underlying implicit and explicit memory processes for cocaine-related visual cues have not been directly investigated in cocaine users in the imaging literature, and (c) none of the previous imaging studies has examined connectivity between the memory system and craving system in the brain of chronic users of cocaine. Finally, future directions in the field of cocaine addiction are suggested. PMID:25009766

Considering Apical Scotomas, Confusion, and Diplopia When Prescribing Prisms for Homonymous Hemianopia

PubMed Central

Apfelbaum, Henry L.; Ross, Nicole C.; Bowers, Alex R.; Peli, Eli

2013-01-01

Purpose: While prisms are commonly prescribed for homonymous hemianopia to extend or expand the visual field, they cause potentially troubling visual side effects, including nonveridical location of perceived images, diplopia, and visual confusion. In addition, the field behind a prism at its apex is lost to an apical scotoma equal in magnitude to the amount of prism shift. The perceptual consequences of apical scotomas and the other effects of various designs were examined to consider parameters and designs that can mitigate the impact of these effects. Methods: Various configurations of sector and peripheral prisms were analyzed, in various directions of gaze, and their visual effects were illustrated using simulated perimetry. A novel “percept” diagram was developed that yielded insights into the patient's view through the prisms. The predictions were verified perimetrically with patients. Results: The diagrams distinguish between potentially beneficial field expansion via visual confusion and the pericentrally disturbing and useless effect of diplopia, and their relationship to prism power and gaze direction. They also illustrate the nonexpanding substitution of field segments of some popular prism designs. Conclusions: Yoked sector prisms have no effect at primary gaze or when gaze is directed toward the seeing hemifield, and they introduce pericentral field loss when gaze is shifted into them. When fitted unilaterally, sector prisms also have an effect only when the gaze is directed into the prism and may cause a pericentral scotoma and/or central diplopia. Peripheral prisms are effective at essentially all gaze angles. Since gaze is not directed into them, they avoid problematic pericentral effects. We derive useful recommendations for prism power and position parameters, including novel ways of fitting prisms asymmetrically. Translational Relevance: Clinicians will find these novel diagrams, diagramming techniques, and analyses valuable when prescribing prismatic aids for hemianopia and when designing new prism devices for patients with various types of field loss. PMID:24049719

Visual acuity and visual field impairment in Usher syndrome.

PubMed

Edwards, A; Fishman, G A; Anderson, R J; Grover, S; Derlacki, D J

1998-02-01

To determine the extent of visual acuity and visual field impairment in patients with types 1 and 2 Usher syndrome. The records of 53 patients with type 1 and 120 patients with type 2 Usher syndrome were reviewed for visual acuity and visual field area at their most recent visit. Visual field areas were determined by planimetry of the II4e and V4e isopters obtained with a Goldmann perimeter. Both ordinary and logistic regression models were used to evaluate differences in visual acuity and visual field impairment between patients with type 1 and type 2 Usher syndrome. The difference in visual acuity of the better eye between patients with type 1 and type 2 varied by patient age (P=.01, based on a multiple regression model). The maximum difference in visual acuity between the 2 groups occurred during the third and fourth decades of life (with the type 1 patients being more impaired), while more similar acuities were seen in both younger and older patients. Fifty-one percent (n=27) of the type 1 patients had a visual acuity of 20/40 or better in at least 1 eye compared with 72% (n=87) of the type 2 patients (age-adjusted odds ratio, 3.9). Visual field area to both the II4e (P=.001) and V4e (P<.001) targets was more impaired in the better eye of type 1 patients than type 2 patients. A concentric central visual field greater than 20 degrees in at least 1 eye was present in 20 (59%) of the available 34 visual fields of type 1 patients compared with 70 (67%) of the available 104 visual fields of type 2 patients (age-adjusted odds ratio, 2.9) with the V4e target and in 6 (21%) of the available 29 visual fields of type 1 patients compared with 36 (38%) of the available 94 visual fields of type 2 patients (age-adjusted odds ratio, 4.9) with the II4e target. The fraction of patients who had a visual acuity of 20/40 or better and a concentric central visual field greater than 20 degrees to the II4e target in at least 1 eye was 17% (n=5) in the type 1 patients and 35% (n=33) in the type 2 patients (age-adjusted odds ratio, 3.9). Visual acuity and visual field area were more impaired in patients with type 1 than type 2 Usher syndrome. Of note, 27 of 53 type 1 (51%) and 87 of 120 type 2 (72%) patients had a visual acuity of 20/40 or better in at least 1 eye. These data are useful for overall counseling of patients with Usher syndrome.

Optic Neuropathy Secondary to Polyarteritis Nodosa, Case Report, and Diagnostic Challenges.

PubMed

Vazquez-Romo, Kristian A; Rodriguez-Hernandez, Adrian; Paczka, Jose A; Nuño-Suarez, Moises A; Rocha-Muñoz, Alberto D; Zavala-Cerna, Maria G

2017-01-01

To describe a case of optic neuropathy as a primary manifestation of polyarteritis nodosa (PAN) and discuss diagnostic challenges. Case report. A 41-year-old Hispanic man presented with a 2-day history of reduced visual acuity in his left eye. Physical examination revealed a complete visual field loss in the affected eye. Best-corrected visual acuity (BCVA) in the left eye was hand motion, and fundus examination revealed a hyperemic optic disk with blurred margins, swelling, retinal folds, dilated veins, and normal size arteries. BCVA in the right eye was 20/20; no anomalies were seen during examination of the fundus. The patient was started on oral corticosteroids and once the diagnosis of PAN was made, cyclophosphamide was added to the treatment regimen. Six months later, the patient recovered his BCVA to 20/20 in his left eye. Rarely does optic neuropathy present as a primary manifestation of PAN; nevertheless, it represents an ophthalmologic emergency that requires expeditious anti-inflammatory and immunosuppressive treatment to decrease the probability of permanent visual damage. Unfortunately, diagnosing PAN is challenging as it necessitates a high index of suspicion. In young male patients who present for the first time with diminished visual acuity, ophthalmologists become cornerstones in the suspicion of this diagnosis and should be responsible for continuing the study until a diagnosis is reached to ensure rapid commencement of immunosuppressive treatment.

Binocular Summation and Other Forms of Non-Dominant Eye Contribution in Individuals with Strabismic Amblyopia during Habitual Viewing

PubMed Central

Barrett, Brendan T.; Panesar, Gurvinder K.; Scally, Andrew J.; Pacey, Ian E.

2013-01-01

Background Adults with amblyopia (‘lazy eye’), long-standing strabismus (ocular misalignment) or both typically do not experience visual symptoms because the signal from weaker eye is given less weight than the signal from its fellow. Here we examine the contribution of the weaker eye of individuals with strabismus and amblyopia with both eyes open and with the deviating eye in its anomalous motor position. Methodology/Results The task consisted of a blue-on-yellow detection task along a horizontal line across the central 50 degrees of the visual field. We compare the results obtained in ten individuals with strabismic amblyopia with ten visual normals. At each field location in each participant, we examined how the sensitivity exhibited under binocular conditions compared with sensitivity from four predictions, (i) a model of binocular summation, (ii) the average of the monocular sensitivities, (iii) dominant-eye sensitivity or (iv) non-dominant-eye sensitivity. The proportion of field locations for which the binocular summation model provided the best description of binocular sensitivity was similar in normals (50.6%) and amblyopes (48.2%). Average monocular sensitivity matched binocular sensitivity in 14.1% of amblyopes’ field locations compared to 8.8% of normals’. Dominant-eye sensitivity explained sensitivity at 27.1% of field locations in amblyopes but 21.2% in normals. Non-dominant-eye sensitivity explained sensitivity at 10.6% of field locations in amblyopes but 19.4% in normals. Binocular summation provided the best description of the sensitivity profile in 6/10 amblyopes compared to 7/10 of normals. In three amblyopes, dominant-eye sensitivity most closely reflected binocular sensitivity (compared to two normals) and in the remaining amblyope, binocular sensitivity approximated to an average of the monocular sensitivities. Conclusions Our results suggest a strong positive contribution in habitual viewing from the non-dominant eye in strabismic amblyopes. This is consistent with evidence from other sources that binocular mechanisms are frequently intact in strabismic and amblyopic individuals. PMID:24205005

Characterizing Head Motion in 3 Planes during Combined Visual and Base of Support Disturbances in Healthy and Visually Sensitive Subjects

PubMed Central

Keshner, E.A.; Dhaher, Y.

2008-01-01

Multiplanar environmental motion could generate head instability, particularly if the visual surround moves in planes orthogonal to a physical disturbance. We combined sagittal plane surface translations with visual field disturbances in 12 healthy (29–31 years) and 3 visually sensitive (27–57 years) adults. Center of pressure (COP), peak head angles, and RMS values of head motion were calculated and a 3-dimensional model of joint motion11 was developed to examine gross head motion in 3 planes. We found that subjects standing quietly in front of a visual scene translating in the sagittal plane produced significantly greater (p<0.003) head motion in yaw than when on a translating platform. However, when the platform was translated in the dark or with a visual scene rotating in roll, head motion orthogonal to the plane of platform motion significantly increased (p<0.02). Visually sensitive subjects having no history of vestibular disorder produced large, delayed compensatory head motion. Orthogonal head motions were significantly greater in visually sensitive than in healthy subjects in the dark (p<0.05) and with a stationary scene (p<0.01). We concluded that motion of the visual field can modify compensatory response kinematics of a freely moving head in planes orthogonal to the direction of a physical perturbation. These results suggest that the mechanisms controlling head orientation in space are distinct from those that control trunk orientation in space. These behaviors would have been missed if only COP data were considered. Data suggest that rehabilitation training can be enhanced by combining visual and mechanical perturbation paradigms. PMID:18162402

Perceived change in orientation from optic flow in the central visual field

NASA Technical Reports Server (NTRS)

Dyre, Brian P.; Andersen, George J.

1988-01-01

The effects of internal depth within a simulation display on perceived changes in orientation have been studied. Subjects monocularly viewed displays simulating observer motion within a volume of randomly positioned points through a window which limited the field of view to 15 deg. Changes in perceived spatial orientation were measured by changes in posture. The extent of internal depth within the display, the presence or absence of visual information specifying change in orientation, and the frequency of motion supplied by the display were examined. It was found that increased sway occurred at frequencies equal to or below 0.375 Hz when motion at these frequencies was displayed. The extent of internal depth had no effect on the perception of changing orientation.

Pigmentary glaucoma accompanied by Usher syndrome.

PubMed

Koucheki, Behrooz; Jalali, Kamran Hodjat

2012-08-01

To report a case of pigmentary glaucoma (PG) accompanied by Usher syndrome. Case report. The results were presented after standard ocular examination, visual field test, anterior segment and fundus photography, electroretinography, and otolaryngology consultation were conducted. Typical retinitis pigmentosa, flat electroretinography, congenital sensorineural hearing loss, high intraocular pressure, Krukenberg spindle, iris concavity, radial iris transillumination defect, severe pigment deposition on the trabecular meshwork, and glaucomatous optic nerve damage were indicative of PG accompanied by Usher syndrome. In some rare cases, PG may coexist with Usher syndrome. Common findings of Usher syndrome, including night blindness, impaired vision, visual field defects, and retinal changes may distract the clinician from considering the diagnosis of glaucoma. Such association should be borne in mind to make a timely diagnosis and treatment possible.

Geometric quantification of features in large flow fields.

PubMed

Kendall, Wesley; Huang, Jian; Peterka, Tom

2012-01-01

Interactive exploration of flow features in large-scale 3D unsteady-flow data is one of the most challenging visualization problems today. To comprehensively explore the complex feature spaces in these datasets, a proposed system employs a scalable framework for investigating a multitude of characteristics from traced field lines. This capability supports the examination of various neighborhood-based geometric attributes in concert with other scalar quantities. Such an analysis wasn't previously possible because of the large computational overhead and I/O requirements. The system integrates visual analytics methods by letting users procedurally and interactively describe and extract high-level flow features. An exploration of various phenomena in a large global ocean-modeling simulation demonstrates the approach's generality and expressiveness as well as its efficacy.

Acquired pit of the optic nerve: a risk factor for progression of glaucoma.

PubMed

Ugurlu, S; Weitzman, M; Nduaguba, C; Caprioli, J

1998-04-01

To examine acquired pit of the optic nerve as a risk factor for progression of glaucoma. In a retrospective longitudinal study, 25 open-angle glaucoma patients with acquired pit of the optic nerve were compared with a group of 24 open-angle glaucoma patients without acquired pit of the optic nerve. The patients were matched for age, mean intraocular pressure, baseline ratio of neuroretinal rim area to disk area, visual field damage, and duration of follow-up. Serial optic disk photographs and visual fields of both groups were evaluated by three independent observers for glaucomatous progression. Of 46 acquired pits of the optic nerve in 37 eyes of 25 patients, 36 pits were located inferiorly (76%) and 11 superiorly (24%; P < .001). Progression of optic disk damage occurred in 16 patients (64%) in the group with acquired pit and in three patients (12.5%) in the group without acquired pit (P < .001). Progression of visual field loss occurred in 14 patients (56%) in the group with acquired pit and in six (25%) in the group without pit (P=.04). Bilateral acquired pit of the optic nerve was present in 12 patients (48%). Disk hemorrhages were observed more frequently in the group with acquired pit (10 eyes, 40%) compared with the group without pit (two eyes, 8%; P=.02). Among patients with glaucoma, patients with acquired pit of the optic nerve represent a subgroup who are at increased risk for progressive optic disk damage and visual field loss.

Identification of a novel mutation in the PTCH gene in a patient with Gorlin-Goltz syndrome with unusual ocular disorders.

PubMed

Romano, Mary; Iacovello, Daniela; Cascone, Nikhil C; Contestabile, Maria Teresa

2011-01-01

To document the clinical, functional, and in vivo microanatomic characteristics of a patient with Gorlin-Goltz syndrome with a novel nonsense mutation in PTCH (patched). Optical coherence tomography (OCT), fluorescein angiography, electrophysiologic testing, visual field, magnetic resonance imaging, and mutation screening of PTCH gene. Visual acuity was 20/20 in the right eye and 20/25 in the left. Fundus examination revealed myelinated nerve fibers in the left eye and bilateral epiretinal membranes with lamellar macular hole also documented with macular OCT. A reduction of the retinal nerve fiber layers in both eyes was found with fiber nervous OCT. Fluorescein angiography showed bilaterally foveal hyperfluorescence and the visual field revealed inferior hemianopia in the right eye. Pattern visual evoked potentials registered a reduction of amplitude in both eyes and latency was delayed in the left eye. Pattern electroretinogram showed a reduction in P50 and N95 peak time and a delay in P50 peak time in the left eye. Flash electroretinogram was reduced in rod response, maximal response, and oscillatory potentials in both eyes. Cone response was normal and 30-Hz flicker was slightly reduced in both eyes. Mutation screening identified a novel nonsense mutation in PTCH. A novel nonsense mutation in the PTCH gene was found. We report the occurrence of epiretinal membranes and the persistence of myelinated nerve fibers. Electrophysiologic and visual field alterations, supporting a neuroretinal dysfunction, were also documented.

Enhancement and suppression in the visual field under perceptual load.

PubMed

Parks, Nathan A; Beck, Diane M; Kramer, Arthur F

2013-01-01

The perceptual load theory of attention proposes that the degree to which visual distractors are processed is a function of the attentional demands of a task-greater demands increase filtering of irrelevant distractors. The spatial configuration of such filtering is unknown. Here, we used steady-state visual evoked potentials (SSVEPs) in conjunction with time-domain event-related potentials (ERPs) to investigate the distribution of load-induced distractor suppression and task-relevant enhancement in the visual field. Electroencephalogram (EEG) was recorded while subjects performed a foveal go/no-go task that varied in perceptual load. Load-dependent distractor suppression was assessed by presenting a contrast reversing ring at one of three eccentricities (2, 6, or 11°) during performance of the go/no-go task. Rings contrast reversed at 8.3 Hz, allowing load-dependent changes in distractor processing to be tracked in the frequency-domain. ERPs were calculated to the onset of stimuli in the load task to examine load-dependent modulation of task-relevant processing. Results showed that the amplitude of the distractor SSVEP (8.3 Hz) was attenuated under high perceptual load (relative to low load) at the most proximal (2°) eccentricity but not at more eccentric locations (6 or 11°). Task-relevant ERPs revealed a significant increase in N1 amplitude under high load. These results are consistent with a center-surround configuration of load-induced enhancement and suppression in the visual field.

Visual field defects may not affect safe driving.

PubMed

Dow, Jamie

2011-10-01

In Quebec a driver whose acquired visual field defect renders them ineligible for a driver's permit renewal may request an exemption from the visual field standard by demonstrating safe driving despite the defect. For safety reasons it was decided to attempt to identify predictors of failure on the road test in order to avoid placing driving evaluators in potentially dangerous situations when evaluating drivers with visual field defects. During a 4-month period in 2009 all requests for exemptions from the visual field standard were collected and analyzed. All available medical and visual field data were collated for 103 individuals, of whom 91 successfully completed the evaluation process and obtained a waiver. The collated data included age, sex, type of visual field defect, visual field characteristics, and concomitant medical problems. No single factor, or combination of factors, could predict failure of the road test. All 5 failures of the road test had cognitive problems but 6 of the successful drivers also had known cognitive problems. Thus, cognitive problems influence the risk of failure but do not predict certain failure. Most of the applicants for an exemption were able to complete the evaluation process successfully, thereby demonstrating safe driving despite their handicap. Consequently, jurisdictions that have visual field standards for their driving permit should implement procedures to evaluate drivers with visual field defects that render them unable to meet the standard but who wish to continue driving.

From Disabled Students to Disabled Brains: The Medicalizing Power of Rhetorical Images in the Israeli Learning Disabilities Field.

PubMed

Katchergin, Ofer

2017-09-01

The neurocentric worldview that identifies the essence of the human being with the material brain has become a central paradigm in current academic discourse. Israeli researchers also seek to understand educational principles and processes via neuroscientific models. On this background, the article uncovers the central role that visual brain images play in the learning-disabilities field in Israel. It examines the place brain images have in the professional imagination of didactic-diagnosticians as well as their influence on the diagnosticians' clinical attitudes. It relies on two theoretical fields: sociology and anthropology of the body and sociology of neuromedical knowledge. The research consists of three methodologies: ethnographic observations, in-depth interviews, and rhetorical analysis of visual and verbal texts. It uncovers the various rhetorical and ideological functions of brain images in the field. It also charts the repertoire of rhetorical devices which are utilized to strengthen the neuroreducionist messages contained in the images.

[Clinical findings in members of a Czech family with retinitis pigmentosa caused by the c.2426_2427delAG mutation in RPGR].

PubMed

Kousal, B; Skalická, P; Diblík, P; Kuthan, P; Langrová, H; Lišková, P

2013-03-01

To describe the phenotype of members of the first Czech retinitis pigmentosa family with an identified molecular genetic cause (c.2426_2427delAG in RPGR), followed for more than 13 years. Medical records were reviewed and a detailed ophthalmic examination including spectral-domain optical coherence tomography and full-field and multifocal electroretinography (ERG) was performed in two affected males, three female carriers and one unaffected female. A 22-year-old male who denied suffering from nyctalopia had a best corrected visual acuity (BCVA) of 0.63 in both eyes. Moderate myopia and myopic astigmatism were present bilaterally. Color vision and contrast sensitivity were normal. There was an eccentric constriction of the visual fields that spared the central 20 degrees in both eyes. Fundus examination revealed bilateral pigmentary changes in the mid-periphery. Full-field ERG documented a 10% rod and 20% cone response. The phenotype of his cousin, also aged 22 years, was more severe. He complained of nyctalopia since 12 years of age. His BCVA was 0.3 in the right eye and 0.5 in the left eye. Myopia and astigmatism were present bilaterally. Contrast sensitivity and color vision were severely impaired. Full field ERG was extinct, but some activity on multifocal ERG was still detectable. The constriction of the visual fields reached 5 degrees in both eyes. Fundus examination showed the typical retinitis pigmentosa appearance. All carriers denied that they suffered from nyctalopia, but two of them had decreased BCVA in at least one eye. None exhibited typical bone spicules or a tapetal-like reflex. Significant refractive errors were present in all eyes of the carriers. The finding of moderate or high myopia and astigmatism in males with retinitis pigmentosa as well as refractive errors in female relatives indicates possible X-linked inheritance, which may be especially important in pedigrees where the transmission pattern can not be clearly established. Our study highlights the inter-individual variability in phenotype observed in similar aged patients with identical ORF15 RPGR mutations.

21 CFR 886.1360 - Visual field laser instrument.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Visual field laser instrument. 886.1360 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1360 Visual field laser instrument. (a) Identification. A visual field laser instrument is an AC-powered device intended to provide...

21 CFR 886.1360 - Visual field laser instrument.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Visual field laser instrument. 886.1360 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1360 Visual field laser instrument. (a) Identification. A visual field laser instrument is an AC-powered device intended to provide...

21 CFR 886.1360 - Visual field laser instrument.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Visual field laser instrument. 886.1360 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1360 Visual field laser instrument. (a) Identification. A visual field laser instrument is an AC-powered device intended to provide...

21 CFR 886.1360 - Visual field laser instrument.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Visual field laser instrument. 886.1360 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1360 Visual field laser instrument. (a) Identification. A visual field laser instrument is an AC-powered device intended to provide...

A comparison of some effects of three antimotion sickness drugs on nystagmic responses to angular accelerations and to optokinetic stimuli.

DOT National Transportation Integrated Search

1981-08-01

This study examined the influence of three established antimotion sickness drugs on nystagmic eye movement responses to angular acceleration (whole-body movement) with vision either permitted or denied, and to optokinetic stimulation (visual field mo...

Understanding Metaphors: Is the Right Hemisphere Uniquely Involved?

ERIC Educational Resources Information Center

Kacinik, Natalie A.; Chiarello, Christine

2007-01-01

Two divided visual field priming experiments examined cerebral asymmetries for understanding metaphors varying in sentence constraint. Experiment 1 investigated ambiguous words (e.g., SWEET and BRIGHT) with literal and metaphoric meanings in ambiguous and unambiguous sentence contexts, while Experiment 2 involved standard metaphors (e.g., "The…

[A rare cause of optic neuropathy: Cassava].

PubMed

Zeboulon, P; Vignal-Clermont, C; Baudouin, C; Labbé, A

2016-06-01

Cassava root is a staple food for almost 500 million people worldwide. Excessive consumption of it is a rare cause of optic neuropathy. Ten patients diagnosed with cassava root related optic neuropathy were included in this retrospective study. Diagnostic criteria were a bilateral optic neuropathy preceded by significant cassava root consumption. Differential diagnoses were excluded through a neuro-ophthalmic examination, blood tests and a brain MRI. All patients had visual field examination and OCT retinal nerve fiber layer (RNFL) analysis as well as an evaluation of their cassava consumption. All patients had a bilateral optic nerve head atrophy or pallor predominantly located into the temporal sector. Visual field defects consisted of a central or cecocentral scotoma for all patients. RNFL showed lower values only in the temporal sector. Mean duration of cassava consumption prior to the appearance of visual symptoms was 22.7±11.2 years with a mean of 2.57±0.53 cassava-based meals per week. Cassava related optic neuropathy is possibly due to its high cyanide content and enabled by a specific amino-acid deficiency. Cassava root chronic consumption is a rare, underappreciated cause of optic neuropathy and its exact mechanism is still uncertain. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Optic nerve dysfunction during gravity inversion. Visual field abnormalities.

PubMed

Sanborn, G E; Friberg, T R; Allen, R

1987-06-01

Inversion in a head-down position (gravity inversion) results in an intraocular pressure of 35 to 40 mm Hg in normal subjects. We used computerized static perimetry to measure the visual fields of normal subjects during gravity inversion. There were no visual field changes in the central 6 degrees of the visual field compared with the baseline (preinversion) values. However, when the central 30 degrees of the visual field was tested, reversible visual field defects were found in 11 of 19 eyes. We believe that the substantial elevation of intraocular pressure during gravity inversion may pose potential risks to the eyes, and we recommend that inversion for extended periods of time be avoided.

Multifield-graphs: an approach to visualizing correlations in multifield scalar data.

PubMed

Sauber, Natascha; Theisel, Holger; Seidel, Hans-Peter

2006-01-01

We present an approach to visualizing correlations in 3D multifield scalar data. The core of our approach is the computation of correlation fields, which are scalar fields containing the local correlations of subsets of the multiple fields. While the visualization of the correlation fields can be done using standard 3D volume visualization techniques, their huge number makes selection and handling a challenge. We introduce the Multifield-Graph to give an overview of which multiple fields correlate and to show the strength of their correlation. This information guides the selection of informative correlation fields for visualization. We use our approach to visually analyze a number of real and synthetic multifield datasets.

Combining computational analyses and interactive visualization for document exploration and sensemaking in jigsaw.

PubMed

Görg, Carsten; Liu, Zhicheng; Kihm, Jaeyeon; Choo, Jaegul; Park, Haesun; Stasko, John

2013-10-01

Investigators across many disciplines and organizations must sift through large collections of text documents to understand and piece together information. Whether they are fighting crime, curing diseases, deciding what car to buy, or researching a new field, inevitably investigators will encounter text documents. Taking a visual analytics approach, we integrate multiple text analysis algorithms with a suite of interactive visualizations to provide a flexible and powerful environment that allows analysts to explore collections of documents while sensemaking. Our particular focus is on the process of integrating automated analyses with interactive visualizations in a smooth and fluid manner. We illustrate this integration through two example scenarios: an academic researcher examining InfoVis and VAST conference papers and a consumer exploring car reviews while pondering a purchase decision. Finally, we provide lessons learned toward the design and implementation of visual analytics systems for document exploration and understanding.

Theta coupling between V4 and prefrontal cortex predicts visual short-term memory performance.

PubMed

Liebe, Stefanie; Hoerzer, Gregor M; Logothetis, Nikos K; Rainer, Gregor

2012-01-29

Short-term memory requires communication between multiple brain regions that collectively mediate the encoding and maintenance of sensory information. It has been suggested that oscillatory synchronization underlies intercortical communication. Yet, whether and how distant cortical areas cooperate during visual memory remains elusive. We examined neural interactions between visual area V4 and the lateral prefrontal cortex using simultaneous local field potential (LFP) recordings and single-unit activity (SUA) in monkeys performing a visual short-term memory task. During the memory period, we observed enhanced between-area phase synchronization in theta frequencies (3-9 Hz) of LFPs together with elevated phase locking of SUA to theta oscillations across regions. In addition, we found that the strength of intercortical locking was predictive of the animals' behavioral performance. This suggests that theta-band synchronization coordinates action potential communication between V4 and prefrontal cortex that may contribute to the maintenance of visual short-term memories.

Task set induces dynamic reallocation of resources in visual short-term memory.

PubMed

Sheremata, Summer L; Shomstein, Sarah

2017-08-01

Successful interaction with the environment requires the ability to flexibly allocate resources to different locations in the visual field. Recent evidence suggests that visual short-term memory (VSTM) resources are distributed asymmetrically across the visual field based upon task demands. Here, we propose that context, rather than the stimulus itself, determines asymmetrical distribution of VSTM resources. To test whether context modulates the reallocation of resources to the right visual field, task set, defined by memory-load, was manipulated to influence visual short-term memory performance. Performance was measured for single-feature objects embedded within predominantly single- or two-feature memory blocks. Therefore, context was varied to determine whether task set directly predicts changes in visual field biases. In accord with the dynamic reallocation of resources hypothesis, task set, rather than aspects of the physical stimulus, drove improvements in performance in the right- visual field. Our results show, for the first time, that preparation for upcoming memory demands directly determines how resources are allocated across the visual field.

Slow Reading in Glaucoma: Is it due to the Shrinking Visual Span in Central Vision?

PubMed Central

Liu, Rong; Patel, Bhavika N.; Girkin, Christopher

2017-01-01

Purpose Glaucoma is a leading cause of blindness worldwide, characterized by progressive loss of retinal ganglion cells. Patients with bilateral glaucoma read slower than normal cohorts. Here we examined the factors that may underlie slow reading in glaucoma and determined the best predictor of reading speed in glaucoma. Methods A total of 38 subjects participated in this study: 17 patients with primary open-angle glaucoma (mean age = 64.71 years) and 21 age-similar normal controls (58.24 years). For each subject, we measured binocular visual acuity (BVA); binocular contrast sensitivity (BCS); stereoacuity; visual field mean deviation (MD); and the visual span (i.e., the number of letters recognizable at one glance) known to limit reading speed. The visual span was measured with a trigram letter-recognition task in which subjects identify trigrams flashed at varying letter positions left and right of the fixation. Oral reading speed was measured with short blocks of text. Results Even after controlling for age, glaucoma patients showed significantly slower reading speed (by 19%, P < 0.05) and smaller visual span (by 11 bits, P < 0.001) compared to normal controls. While their BVA was relatively normal (20/20 Snellen equivalent), their BCS (P < 0.001); stereoacuity (P < 0.001); and visual field MD (P < 0.001) showed pronounced deficits. Multiple regression analysis further revealed that reading speed in glaucoma was best predicted by the visual span. Conclusions Our results showed that slower reading speed in glaucoma was closely related to the shrinkage of the visual span. Our findings further support the view that the visual span plays a limiting role in reading speed. PMID:29131903

Slow Reading in Glaucoma: Is it due to the Shrinking Visual Span in Central Vision?

PubMed

Kwon, MiYoung; Liu, Rong; Patel, Bhavika N; Girkin, Christopher

2017-11-01

Glaucoma is a leading cause of blindness worldwide, characterized by progressive loss of retinal ganglion cells. Patients with bilateral glaucoma read slower than normal cohorts. Here we examined the factors that may underlie slow reading in glaucoma and determined the best predictor of reading speed in glaucoma. A total of 38 subjects participated in this study: 17 patients with primary open-angle glaucoma (mean age = 64.71 years) and 21 age-similar normal controls (58.24 years). For each subject, we measured binocular visual acuity (BVA); binocular contrast sensitivity (BCS); stereoacuity; visual field mean deviation (MD); and the visual span (i.e., the number of letters recognizable at one glance) known to limit reading speed. The visual span was measured with a trigram letter-recognition task in which subjects identify trigrams flashed at varying letter positions left and right of the fixation. Oral reading speed was measured with short blocks of text. Even after controlling for age, glaucoma patients showed significantly slower reading speed (by 19%, P < 0.05) and smaller visual span (by 11 bits, P < 0.001) compared to normal controls. While their BVA was relatively normal (20/20 Snellen equivalent), their BCS (P < 0.001); stereoacuity (P < 0.001); and visual field MD (P < 0.001) showed pronounced deficits. Multiple regression analysis further revealed that reading speed in glaucoma was best predicted by the visual span. Our results showed that slower reading speed in glaucoma was closely related to the shrinkage of the visual span. Our findings further support the view that the visual span plays a limiting role in reading speed.

The visual properties of proximal and remote distractors differentially influence reaching planning times: evidence from pro- and antipointing tasks.

PubMed

Heath, Matthew; DeSimone, Jesse C

2016-11-01

The saccade literature has consistently reported that the presentation of a distractor remote to a target increases reaction time (i.e., the remote distractor effect: RDE). As well, some studies have shown that a proximal distractor facilitates saccade reaction time. The lateral inhibition hypothesis attributes the aforementioned findings to the inhibition/facilitation of target selection mechanisms operating in the intermediate layers of the superior colliculus (SC). Although the impact of remote and proximal distractors has been extensively examined in the saccade literature, a paucity of work has examined whether such findings generalize to reaching responses, and to our knowledge, no work has directly contrasted reaching RTs for remote and proximal distractors. To that end, the present investigation had participants complete reaches in target only trials (i.e., TO) and when distractors were presented at "remote" (i.e., the opposite visual field) and "proximal" (i.e., the same visual field) locations along the same horizontal meridian as the target. As well, participants reached to the target's veridical (i.e., propointing) and mirror-symmetrical (i.e., antipointing) location. The basis for contrasting pro- and antipointing was to determine whether the distractor's visual- or motor-related activity influence reaching RTs. Results demonstrated that remote and proximal distractors, respectively, increased and decreased reaching RTs and the effect was consistent for pro- and antipointing. Accordingly, results evince that the RDE and the facilitatory effects of a proximal distractor are effector independent and provide behavioral support for the contention that the SC serves as a general target selection mechanism. As well, the comparable distractor-related effects for pro- and antipointing trials indicate that the visual properties of remote and proximal distractors respectively inhibit and facilitate target selection.

Effects of weak electromagnetic fields on Escherichia coli and Staphylococcus aureus

NASA Astrophysics Data System (ADS)

Smith, Derek A.

Previous studies of electromagnetic field effects on bacteria are examined, and new experimental procedures and their results are discussed. Experimental samples of Escherichia coli and Staphylococcus aureus were prepared in different conditions, and measurements of optical density were used to track growth rates after removing the samples from their associated experimental environments. Experimental environments varied in magnetic field intensities and frequencies, including a control environment of minimal field intensity. Plots of experimental data sets and their associated averages are used to visualize the experimental outcomes, and differences in growth patterns are evaluated. Results are then used to hypothesize the mechanisms and consequences of the potentially observed field effects.

[Effects of the verbal loading on laterality difference in visual field (author's transl)].

PubMed

Kawai, M

1980-02-01

In connection with the Kinsbourne's attention-model, the relation between the level of hemisphere sharing of loading task and the visual-laterality difference was examined under verbal loading conditions. The subjects were 13 (8 male and 5 female) right-handed college students. The loading tasks in Exp. I were the "same-different" judgment of Japanese hiragana alphabets and of triliteral hiragana words, and "true-false" judgment of short statements. In Exp. II, a procedure to eliminate configurational matching of the letters was followed. The results of the two experiments suggest that the visual-laterality effect occurs only when the level of hemisphere sharing of the loading task exceeds a certain lower bound.

Assessment of the reliability of standard automated perimetry in regions of glaucomatous damage.

PubMed

Gardiner, Stuart K; Swanson, William H; Goren, Deborah; Mansberger, Steven L; Demirel, Shaban

2014-07-01

Visual field testing uses high-contrast stimuli in areas of severe visual field loss. However, retinal ganglion cells saturate with high-contrast stimuli, suggesting that the probability of detecting perimetric stimuli may not increase indefinitely as contrast increases. Driven by this concept, this study examines the lower limit of perimetric sensitivity for reliable testing by standard automated perimetry. Evaluation of a diagnostic test. A total of 34 participants with moderate to severe glaucoma; mean deviation at their last clinic visit averaged -10.90 dB (range, -20.94 to -3.38 dB). A total of 75 of the 136 locations tested had a perimetric sensitivity of ≤ 19 dB. Frequency-of-seeing curves were constructed at 4 nonadjacent visual field locations by the Method of Constant Stimuli (MOCS), using 35 stimulus presentations at each of 7 contrasts. Locations were chosen a priori and included at least 2 with glaucomatous damage but a sensitivity of ≥ 6 dB. Cumulative Gaussian curves were fit to the data, first assuming a 5% false-negative rate and subsequently allowing the asymptotic maximum response probability to be a free parameter. The strength of the relation (R(2)) between perimetric sensitivity (mean of last 2 clinic visits) and MOCS sensitivity (from the experiment) for all locations with perimetric sensitivity within ± 4 dB of each selected value, at 0.5 dB intervals. Bins centered at sensitivities ≥ 19 dB always had R(2) >0.1. All bins centered at sensitivities ≤ 15 dB had R(2) <0.1, an indication that sensitivities are unreliable. No consistent conclusions could be drawn between 15 and 19 dB. At 57 of the 81 locations with perimetric sensitivity <19 dB, including 49 of the 63 locations ≤ 15 dB, the fitted asymptotic maximum response probability was <80%, consistent with the hypothesis of response saturation. At 29 of these locations the asymptotic maximum was <50%, and so contrast sensitivity (50% response rate) is undefined. Clinical visual field testing may be unreliable when visual field locations have sensitivity below approximately 15 to 19 dB because of a reduction in the asymptotic maximum response probability. Researchers and clinicians may have difficulty detecting worsening sensitivity in these visual field locations, and this difficulty may occur commonly in patients with glaucoma with moderate to severe glaucomatous visual field loss. Copyright © 2014 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Visual development in primates: Neural mechanisms and critical periods

PubMed Central

Kiorpes, Lynne

2015-01-01

Despite many decades of research into the development of visual cortex, it remains unclear what neural processes set limitations on the development of visual function and define its vulnerability to abnormal visual experience. This selected review examines the development of visual function and its neural correlates, and highlights the fact that in most cases receptive field properties of infant neurons are substantially more mature than infant visual function. One exception is temporal resolution, which can be accounted for by resolution of neurons at the level of the LGN. In terms of spatial vision, properties of single neurons alone are not sufficient to account for visual development. Different visual functions develop over different time courses. Their onset may be limited by the existence of neural response properties that support a given perceptual ability, but the subsequent time course of maturation to adult levels remains unexplained. Several examples are offered suggesting that taking account of weak signaling by infant neurons, correlated firing, and pooled responses of populations of neurons brings us closer to an understanding of the relationship between neural and behavioral development. PMID:25649764

Using Interactive Data Visualizations for Exploratory Analysis in Undergraduate Genomics Coursework: Field Study Findings and Guidelines

NASA Astrophysics Data System (ADS)

Mirel, Barbara; Kumar, Anuj; Nong, Paige; Su, Gang; Meng, Fan

2016-02-01

Life scientists increasingly use visual analytics to explore large data sets and generate hypotheses. Undergraduate biology majors should be learning these same methods. Yet visual analytics is one of the most underdeveloped areas of undergraduate biology education. This study sought to determine the feasibility of undergraduate biology majors conducting exploratory analysis using the same interactive data visualizations as practicing scientists. We examined 22 upper level undergraduates in a genomics course as they engaged in a case-based inquiry with an interactive heat map. We qualitatively and quantitatively analyzed students' visual analytic behaviors, reasoning and outcomes to identify student performance patterns, commonly shared efficiencies and task completion. We analyzed students' successes and difficulties in applying knowledge and skills relevant to the visual analytics case and related gaps in knowledge and skill to associated tool designs. Findings show that undergraduate engagement in visual analytics is feasible and could be further strengthened through tool usability improvements. We identify these improvements. We speculate, as well, on instructional considerations that our findings suggested may also enhance visual analytics in case-based modules.

Using Interactive Data Visualizations for Exploratory Analysis in Undergraduate Genomics Coursework: Field Study Findings and Guidelines

PubMed Central

Kumar, Anuj; Nong, Paige; Su, Gang; Meng, Fan

2016-01-01

Life scientists increasingly use visual analytics to explore large data sets and generate hypotheses. Undergraduate biology majors should be learning these same methods. Yet visual analytics is one of the most underdeveloped areas of undergraduate biology education. This study sought to determine the feasibility of undergraduate biology majors conducting exploratory analysis using the same interactive data visualizations as practicing scientists. We examined 22 upper level undergraduates in a genomics course as they engaged in a case-based inquiry with an interactive heat map. We qualitatively and quantitatively analyzed students’ visual analytic behaviors, reasoning and outcomes to identify student performance patterns, commonly shared efficiencies and task completion. We analyzed students’ successes and difficulties in applying knowledge and skills relevant to the visual analytics case and related gaps in knowledge and skill to associated tool designs. Findings show that undergraduate engagement in visual analytics is feasible and could be further strengthened through tool usability improvements. We identify these improvements. We speculate, as well, on instructional considerations that our findings suggested may also enhance visual analytics in case-based modules. PMID:26877625

Effect of double air injection on performance characteristics of centrifugal compressor

NASA Astrophysics Data System (ADS)

Hirano, Toshiyuki; Ogawa, Tatsuya; Yasui, Ryutaro; Tsujita, Hoshio

2017-02-01

In the operation of a centrifugal compressor of turbocharger, instability phenomena such as rotating stall and surge are induced at a lower flow rate close to the maximum pressure ratio. In this study, the compressed air at the exit of centrifugal compressor was re-circulated and injected to the impeller inlet by using two injection nozzles in order to suppress the surge phenomenon. The most effective circumferential position was examined to reduce the flow rate at the surge inception. Moreover, the influences of the injection on the fluctuating property of the flow field before and after the surge inception were investigated by examining the frequency of static pressure fluctuation on the wall surface and visualizing the compressor wall surface by oil-film visualization technique.

The Montrachet Study: study design, methodology and analysis of visual acuity and refractive errors in an elderly population.

PubMed

Creuzot-Garcher, Catherine; Binquet, Christine; Daniel, Sandrine; Bretillon, Lionel; Acar, Nyiazi; de Lazzer, Aurélie; Arnould, Laurent; Tzourio, Christophe; Bron, Alain M; Delcourt, Cécile

2016-03-01

To describe the design of the Montrachet Study (Maculopathy Optic Nerve nuTRition neurovAsCular and HEarT diseases) and to report visual acuity and refractive errors in this elderly population. Participants were recruited in Dijon (France), from the ongoing population-based 3C Study. In 2009-2011, 1153 participants from the 3 Cities Study, aged 75 years or more, had an initial eye examination and were scheduled for eye examinations. The eye examination comprised visual acuity, refraction, visual field, ocular surface assessment, photographs and OCT of the macula and the optic disc, measurement of intra-ocular pressure, central corneal thickness and macular pigment assessment. Information on cardiovascular and neurologic diseases and a large comprehensive database (blood samples, genetic testing, cognitive tests, MRI) were available from the 3C Study. Presenting visual acuity <20/60 in the better eye was found in 2.3% (95% CI 1.5-3.2) of the participants with no gender differences. Visual impairment increased with age from 1.5% (95% CI 0.3-2.7) for those aged 75-79 years to 5.6% (95% CI 2.9-8.4) for patients 85 years and older (p = 0.0003). Spherical equivalent did not differ between men and women (p = 0.8) and decreased with age whatever the lens status. Despite the high prevalence of self-reported eye diseases in this elderly population, visual impairment was low and increased with age. The Montrachet Study may help to better estimate the prevalence of eye diseases in people over 75 years of age and to seek associations with cardiovascular and neurologic diseases and their potential risk factors. © 2015 The Authors. Acta Ophthalmologica published by John Wiley & Sons Ltd on behalf of Acta Ophthalmologica Scandinavica Foundation.

Relationship between progression of visual field defect and intraocular pressure in primary open-angle glaucoma.

PubMed

Naito, Tomoko; Yoshikawa, Keiji; Mizoue, Shiro; Nanno, Mami; Kimura, Tairo; Suzumura, Hirotaka; Shiraga, Fumio

2015-01-01

To analyze the relationship between intraocular pressure (IOP) and the progression of visual field defects in Japanese primary open-angle glaucoma (POAG) and normal-tension glaucoma (NTG) patients. The subjects of the study were patients undergoing treatment for POAG or NTG who had performed visual field tests at least ten times with a Humphrey field analyzer (Swedish interactive thresholding algorithm standard, C30-2 program). The progression of visual field defects was defined by a significantly negative value of the mean deviation slope at the final visual field test during the follow-up period. The relationships between the progression of visual field defects and IOP, as well as other clinical factors, were retrospectively analyzed. A total of 156 eyes of 156 patients were included in the analysis. Significant progression of visual field defects was observed in 70 eyes of 70 patients (44.9%), while no significant progression was evident in 86 eyes of 86 patients (55.1%). The eyes with visual field defect progression had significantly lower baseline IOP (P<0.05), as well as significantly lower IOP reduction rate (P<0.01). The standard deviation of IOP values during follow-up was significantly greater in the eyes with visual field defect progression than in eyes without (P<0.05). Reducing IOP is thought to be useful for Japanese POAG or NTG patients to suppress the progression of visual field defects. In NTG, IOP management should take into account not only achieving the target IOP, but also minimizing the fluctuation of IOP during follow-up period.

3D Flow Visualization Using Texture Advection

NASA Technical Reports Server (NTRS)

Kao, David; Zhang, Bing; Kim, Kwansik; Pang, Alex; Moran, Pat (Technical Monitor)

2001-01-01

Texture advection is an effective tool for animating and investigating 2D flows. In this paper, we discuss how this technique can be extended to 3D flows. In particular, we examine the use of 3D and 4D textures on 3D synthetic and computational fluid dynamics flow fields.

Hemispheric Differences in the Recruitment of Semantic Processing Mechanisms

ERIC Educational Resources Information Center

Kandhadai, Padmapriya; Federmeier, Kara D.

2010-01-01

This study examined how the two cerebral hemispheres recruit semantic processing mechanisms by combining event-related potential measures and visual half-field methods in a word priming paradigm in which semantic strength and predictability were manipulated using lexically associated word pairs. Activation patterns on the late positive complex…

Transposed-Letter and Laterality Effects in Lexical Decision

ERIC Educational Resources Information Center

Perea, Manuel; Fraga, Isabel

2006-01-01

Two divided visual field lexical decision experiments were conducted to examine the role of the cerebral hemispheres in transposed-letter similarity effects. In Experiment 1, we created two types of nonwords: nonadjacent transposed-letter nonwords ("TRADEGIA"; the base word was "TRAGEDIA," the Spanish for "TRAGEDY") and two-letter different…

Is the Cerebellum Involved in Motor and Perceptual Timing: A Case Study.

DTIC Science & Technology

1985-05-15

return to regular employment as a typist. *The visual fields and cranial nerves were intact. The extraocular movements wererfull and there was no nystagmus ...Her saccades were hypermetric, especially on gaze to the left. Examination of motor function in the upper extremities revealed normal strength

Anosognosia for obvious visual field defects in stroke patients.

PubMed

Baier, Bernhard; Geber, Christian; Müller-Forell, Wiebke; Müller, Notger; Dieterich, Marianne; Karnath, Hans-Otto

2015-01-01

Patients with anosognosia for visual field defect (AVFD) fail to recognize consciously their visual field defect. There is still unclarity whether specific neural correlates are associated with AVFD. We studied AVFD in 54 patients with acute stroke and a visual field defect. Nineteen percent of this unselected sample showed AVFD. By using modern voxelwise lesion-behaviour mapping techniques we found an association between AVFD and parts of the lingual gyrus, the cuneus as well as the posterior cingulate and corpus callosum. Damage to these regions appears to induce unawareness of visual field defects and thus may play a significant role for conscious visual perception.

A Cross-sectional Study of Prevalence and Etiology of Childhood Visual Impairment in Auckland, New Zealand.

PubMed

Chong, Chee Foong; McGhee, Charles N J; Dai, Shuan

2014-01-01

Childhood visual impairment has significant individual and socioeconomic costs with global differences in etiology and prevalence. This study aimed to determine prevalence, etiology, and avoidable causes of childhood visual impairment in New Zealand. Retrospective data analysis from a national referral center, the Blind and Low Vision Education Network New Zealand, Auckland. The World Health Organization Program for Prevention of Blindness eye examination records for visually impaired children, 16 years or younger, registered with the Auckland Visual Resource Centre, were included. Data analyzed included demographics, etiology, visual acuity, visual fields, educational setting, and rehabilitation plan. Charts of 340 children were examined, of which 267 children (144 blind, 123 low vision) were included in the analysis, whereas the remaining 73 charts of children with no visual impairment were excluded. The calculated prevalence of blindness and low vision was 0.05% and 0.04%, respectively, in the Auckland region. Principal causes of blindness affecting 91 children (63.9%) were cerebral visual impairment in 61 children (42.4%), optic nerve atrophy in 18 children (12.5%), and retinal dystrophy in 13 children (9.0%). The main potentially avoidable causes of blindness in 27 children (19%) were neonatal trauma, asphyxia in 9 children (33%), and nonaccidental injury 6 children (22%). This first report of prevalence for childhood blindness and low vision in New Zealand is similar to data from Established Market Economy countries. The leading causes of blindness are also comparable to other high-income countries; however, proportions of avoidable causes differ significantly.

Research on integration of visual and motion cues for flight simulation and ride quality investigation

NASA Technical Reports Server (NTRS)

Young, L. R.; Oman, C. M.; Curry, R. E.

1977-01-01

Vestibular perception and integration of several sensory inputs in simulation were studied. The relationship between tilt sensation induced by moving fields and those produced by actual body tilt is discussed. Linearvection studies were included and the application of the vestibular model for perception of orientation based on motion cues is presented. Other areas of examination includes visual cues in approach to landing, and a comparison of linear and nonlinear wash out filters using a model of the human vestibular system is given.

Visual bioethics.

PubMed

Lauritzen, Paul

2008-12-01

Although images are pervasive in public policy debates in bioethics, few who work in the field attend carefully to the way that images function rhetorically. If the use of images is discussed at all, it is usually to dismiss appeals to images as a form of manipulation. Yet it is possible to speak meaningfully of visual arguments. Examining the appeal to images of the embryo and fetus in debates about abortion and stem cell research, I suggest that bioethicists would be well served by attending much more carefully to how images function in public policy debates.

Visualizing second order tensor fields with hyperstreamlines

NASA Technical Reports Server (NTRS)

Delmarcelle, Thierry; Hesselink, Lambertus

1993-01-01

Hyperstreamlines are a generalization to second order tensor fields of the conventional streamlines used in vector field visualization. As opposed to point icons commonly used in visualizing tensor fields, hyperstreamlines form a continuous representation of the complete tensor information along a three-dimensional path. This technique is useful in visulaizing both symmetric and unsymmetric three-dimensional tensor data. Several examples of tensor field visualization in solid materials and fluid flows are provided.

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

PubMed Central

Rowe, Fiona J.; Rowlands, Alison

2014-01-01

Purpose. To determine diagnostic accuracy of kinetic visual field assessment by Octopus 900 perimetry compared with Goldmann perimetry. Methods. Prospective cross section evaluation of 40 control subjects with full visual fields and 50 patients with known visual field loss. Comparison of test duration and area measurement of isopters for Octopus 3, 5, and 10°/sec stimulus speeds. Comparison of test duration and type of visual field classification for Octopus versus Goldmann perimetry. Results were independently graded for presence/absence of field defect and for type and location of defect. Statistical evaluation comprised of ANOVA and paired t test for evaluation of parametric data with Bonferroni adjustment. Bland Altman and Kappa tests were used for measurement of agreement between data. Results. Octopus 5°/sec perimetry had comparable test duration to Goldmann perimetry. Octopus perimetry reliably detected type and location of visual field loss with visual fields matched to Goldmann results in 88.8% of results (K = 0.775). Conclusions. Kinetic perimetry requires individual tailoring to ensure accuracy. Octopus perimetry was reproducible for presence/absence of visual field defect. Our screening protocol when using Octopus perimetry is 5°/sec for determining boundaries of peripheral isopters and 3°/sec for blind spot mapping with further evaluation of area of field loss for defect depth and size. PMID:24587983

Transient Retinal Dysfunctions after Acute Cannabis Use.

PubMed

Schwitzer, Thomas; Robert, Matthieu P; Giersch, Anne; Angioi-Duprez, Karine; Ingster-Moati, Isabelle; Pon-Monnier, Amandine; Schwan, Raymund; Laprevote, Vincent

2016-01-01

Although cannabis is very widespread worldwide, the impact of cannabis on visual function remains poorly understood. This is partly due to numerous difficulties met in developing clinical studies in cannabis users. Here, we report the first documented case of neuroretinal dysfunction after acute cannabis smoking. This observation was favored by the need of an annual ophthalmic evaluation in the context of a chloroquine intake for a systemic lupus erythematosus in a 47-year-old heavy cannabis user. A complete ophthalmic evaluation including visual acuity tests, intraocular pressure, fundoscopic examination, automated 10° central visual field, full-field electroretinogram (ERG) and multifocal ERG was performed twice - 30 min and 5 h after cannabis smoking. A strong decrease (up to 48%) in the a-wave amplitude of the full-field ERG was measured 30 min after cannabis smoking for all scotopic responses compared with the responses 5 h after smoking. Other tests showed reproducible results between the 2 series of measurements. This clinical case suggests that acute inhalation of cannabis affects the photoreceptors functioning. This rare situation suggests further investigations are required on the impact of cannabis on retinal processing, especially since cannabis has been incriminated in car injuries. © 2016 S. Karger AG, Basel.

Epidemiology, clinical presentation and diagnosis of non-functioning pituitary adenomas.

PubMed

Ntali, Georgia; Wass, John A

2018-04-01

Non-functioning pituitary adenomas (NFPAs) are benign pituitary neoplasms that do not cause a hormonal hypersecretory syndrome. An improved understanding of their epidemiology, clinical presentation and diagnosis is needed. A literature review was performed using Pubmed to identify research reports and clinical case series on NFPAs. They account for 14-54% of pituitary adenomas and have a prevalence of 7-41.3/100,000 population. Their standardized incidence rate is 0.65-2.34/100,000 and the peak occurence is from the fourth to the eighth decade. The clinical spectrum of NFPAs varies from being completely asymptomatic to causing significant hypothalamic/pituitary dysfunction and visual field compromise due to their large size. Most patients present with symptoms of mass effect, such as headaches, visual field defects, ophthalmoplegias, and hypopituitarism but also hyperprolactinaemia due to pituitary stalk deviation and less frequently pituitary apoplexy. Non-functioning pituitary incidentalomas are found on brain imaging performed for an unrelated reason. Diagnostic approach includes magnetic resonance imaging of the sellar region, laboratory evaluations, screening for hormone hypersecretion and for hypopituitarism, and a visual field examination if the lesion abuts the optic nerves or chiasm. This article reviews the epidemiology, clinical behaviour and diagnostic approach of non-functioning pituitary adenomas.

Visual risk factors for falls in older people.

PubMed

Lord, Stephen R

2006-09-01

Poor vision reduces postural stability and significantly increases the risk of falls and fractures in older people. Most studies have found that poor visual acuity increases the risk of falls. However, studies that have included multiple visual measures have found that reduced contrast sensitivity and depth perception are the most important visual risk factors for falls. Multifocal glasses may add to this risk because their near-vision lenses impair distance contrast sensitivity and depth perception in the lower visual field. This reduces the ability of an older person to detect environmental hazards. There is now evidence that maximising vision through cataract surgery is an effective strategy for preventing falls. Further randomised controlled trials are required to determine whether individual strategies (such as restriction of use of multifocal glasses) or multi-strategy visual improvement interventions can significantly reduce falls in older people. Public health initiatives are required to raise awareness in older people and their carers of the importance of regular eye examinations and use of appropriate prescription glasses.

Visual brain plasticity induced by central and peripheral visual field loss.

PubMed

Sanda, Nicolae; Cerliani, Leonardo; Authié, Colas N; Sabbah, Norman; Sahel, José-Alain; Habas, Christophe; Safran, Avinoam B; Thiebaut de Schotten, Michel

2018-06-23

Disorders that specifically affect central and peripheral vision constitute invaluable models to study how the human brain adapts to visual deafferentation. We explored cortical changes after the loss of central or peripheral vision. Cortical thickness (CoTks) and resting-state cortical entropy (rs-CoEn), as a surrogate for neural and synaptic complexity, were extracted in 12 Stargardt macular dystrophy, 12 retinitis pigmentosa (tunnel vision stage), and 14 normally sighted subjects. When compared to controls, both groups with visual loss exhibited decreased CoTks in dorsal area V3d. Peripheral visual field loss also showed a specific CoTks decrease in early visual cortex and ventral area V4, while central visual field loss in dorsal area V3A. Only central visual field loss exhibited increased CoEn in LO-2 area and FG1. Current results revealed biomarkers of brain plasticity within the dorsal and the ventral visual streams following central and peripheral visual field defects.

A novel field generator for magnetic stimulation in cell culture experiments.

PubMed

Vogt, G; Schrefl, A; Mitteregger, R; Falkenhagen, D

1997-06-01

A novel field generator specially designed to examine the influence of low frequency magnetic fields on specific cell material was constructed and characterized. The exposure unit described in this paper consists of a controller unit and three sets of coils. The field generator permits a precious definition of the revelant signal parameters and allows the superposition of alternating current (AC) and direct current (DC) magnetic fields. Critical system parameters were monitored continuously. The three sets of coils, each arranged in the Helmholtz Configuration were characterized. After data processing and visualization the results showed a constant and homogeneous field within the experimental area. The special coil design also allows their use in an incubator.

Towards Determination of Visual Requirements for Augmented Reality Displays and Virtual Environments for the Airport Tower

NASA Technical Reports Server (NTRS)

Ellis, Stephen R.

2006-01-01

The visual requirements for augmented reality or virtual environments displays that might be used in real or virtual towers are reviewed with respect to similar displays already used in aircraft. As an example of the type of human performance studies needed to determine the useful specifications of augmented reality displays, an optical see-through display was used in an ATC Tower simulation. Three different binocular fields of view (14deg, 28deg, and 47deg) were examined to determine their effect on subjects ability to detect aircraft maneuvering and landing. The results suggest that binocular fields of view much greater than 47deg are unlikely to dramatically improve search performance and that partial binocular overlap is a feasible display technique for augmented reality Tower applications.

Proprioception Is Robust under External Forces

PubMed Central

Kuling, Irene A.; Brenner, Eli; Smeets, Jeroen B. J.

2013-01-01

Information from cutaneous, muscle and joint receptors is combined with efferent information to create a reliable percept of the configuration of our body (proprioception). We exposed the hand to several horizontal force fields to examine whether external forces influence this percept. In an end-point task subjects reached visually presented positions with their unseen hand. In a vector reproduction task, subjects had to judge a distance and direction visually and reproduce the corresponding vector by moving the unseen hand. We found systematic individual errors in the reproduction of the end-points and vectors, but these errors did not vary systematically with the force fields. This suggests that human proprioception accounts for external forces applied to the hand when sensing the position of the hand in the horizontal plane. PMID:24019959

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

PubMed

Gangeddula, Viswa; Ranchet, Maud; Akinwuntan, Abiodun E; Bollinger, Kathryn; Devos, Hannes

2017-01-01

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

Sunglasses with thick temples and frame constrict temporal visual field.

PubMed

Denion, Eric; Dugué, Audrey Emmanuelle; Augy, Sylvain; Coffin-Pichonnet, Sophie; Mouriaux, Frédéric

2013-12-01

Our aim was to compare the impact of two types of sunglasses on visual field and glare: one ("thick sunglasses") with a thick plastic frame and wide temples and one ("thin sunglasses") with a thin metal frame and thin temples. Using the Goldmann perimeter, visual field surface areas (cm²) were calculated as projections on a 30-cm virtual cupola. A V4 test object was used, from seen to unseen, in 15 healthy volunteers in the primary position of gaze ("base visual field"), then allowing eye motion ("eye motion visual field") without glasses, then with "thin sunglasses," followed by "thick sunglasses." Visual field surface area differences greater than the 14% reproducibility error of the method and having a p < 0.05 were considered significant. A glare test was done using a surgical lighting system pointed at the eye(s) at different incidence angles. No significant "base visual field" or "eye motion visual field" surface area variations were noted when comparing tests done without glasses and with the "thin sunglasses." In contrast, a 22% "eye motion visual field" surface area decrease (p < 0.001) was noted when comparing tests done without glasses and with "thick sunglasses." This decrease was most severe in the temporal quadrant (-33%; p < 0.001). All subjects reported less lateral glare with the "thick sunglasses" than with the "thin sunglasses" (p < 0.001). The better protection from lateral glare offered by "thick sunglasses" is offset by the much poorer ability to use lateral space exploration; this results in a loss of most, if not all, of the additional visual field gained through eye motion.

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

PubMed

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

2012-06-01

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

Visual Half-Field Experiments Are a Good Measure of Cerebral Language Dominance if Used Properly: Evidence from fMRI

ERIC Educational Resources Information Center

Hunter, Zoe R.; Brysbaert, Marc

2008-01-01

Traditional neuropsychology employs visual half-field (VHF) experiments to assess cerebral language dominance. This approach is based on the assumption that left cerebral dominance for language leads to faster and more accurate recognition of words in the right visual half-field (RVF) than in the left visual half-field (LVF) during tachistoscopic…

Ophthalmological assessment of cannabis-induced persisting perception disorder: is there a direct retinal effect?

PubMed

Zobor, Ditta; Strasser, Torsten; Zobor, Gergely; Schober, Franziska; Messias, Andre; Strauss, Olaf; Batra, Anil; Zrenner, Eberhart

2015-04-01

Cannabis is a psychotomimetic agent that induces impairment of sensory perception. We present detailed clinical and electrophysiological data of patients with hallucinogen persisting perception disorder (HPPD) after marijuana consumption. A HPPD patient and four heavy cannabis smokers with no visual disturbances (controls) underwent complete ophthalmological examination including psychophysical tests (visual acuity, color vision, visual field, and dark adaptation) and detailed electrophysiological examinations, including extended Ganzfeld ERG, multifocal ERG, and electrooculography (EOG). Furthermore, electrically evoked phosphene thresholds (EPTs) were measured to further evaluate retinal function. Ophthalmological and most electrophysiological examinations were within normal limits for the HPPD patient and for all control subjects. Interestingly, EOG results of the HPPD patient showed a slightly reduced fast oscillation ratio, diminished standing potentials of the slow oscillations, and a light peak within normal range resulting in higher Arden ratios. The EPTs of the patient were reduced, in particular for pulses with long durations (50 ms) causing visual sensations even at lowest possible currents of the neurostimulator. The control subjects did not reveal such alterations. Our findings suggest a direct effect of cannabinoids on the retina and retinal pigment epithelium function, which may be involved in disturbances of the visual function experienced after drug consumption. The observations presented here may contribute to the elucidation of the detailed mechanism. Furthermore, EOG and EPT measurements may be useful tools to demonstrate long-term retinal alterations in cannabis-induced HPPD in patients.

Experimental Analyses of Flow Field Structures around Clustered Linear Aerospike Nozzles

NASA Astrophysics Data System (ADS)

Taniguchi, Mashio; Mori, Hideo; Nishihira, Ryutaro; Niimi, Tomohide

2005-05-01

An aerospike nozzle has been expected as a candidate for an engine of a reusable space shuttle to respond to growing demand for rocket-launching and its cost reduction. In this study, the flow field structures in any cross sections around clustered linear aerospike nozzles are visualized and analyzed, using laser induced fluorescence (LIF) of NO seeded in the carrier gas N2. Since flow field structures are affected mainly by pressure ratio (Ps/Pa, Ps: the source pressure in a reservoir, Pa: the ambient pressure in the vacuum chamber), the clustered linear aerospike nozzle is set inside a vacuum chamber to carry out the experiments in the wide range of pressure ratios from 75 to 200. Flow fields are visualized in several cross-sections, demonstrating the complicated three-dimensional flow field structures. Pressure sensitive paint (PSP) of PtTFPP bound by poly-IBM-co-TFEM is also applied to measurement of the complicated pressure distribution on the spike surface, and to verification of contribution of a truncation plane to the thrust. Finally, to examine the effect of the sidewalls attached to the aerospike nozzle, the flow fields around the nozzle with the sidewalls are compared with those without sidewalls.

How do patients with neglect see a horizontal line? Analysis of performances in coloured line bisection task.

PubMed

Misonou, Kaori; Ishiai, Sumio; Seki, Keiko; Koyama, Yasumasa; Nakano, Naomi

2004-06-01

Twelve patients with left unilateral spatial neglect were examined with a newly devised "coloured line bisection task". They were presented with a horizontal line printed in blue on one side and in red on the other side; the proportions of the blue and red segments were varied. Immediately after placement of the subjective midpoint, the line was concealed and the patients were asked to name the colours of the right and left ends. Five patients who identified the left-end colour almost correctly had no visual field defect, while the other seven whose colour naming was impaired on the left side had left visual field defect. The rightward bisection errors were similarly distributed in the fair and poor colour-naming patients except for two patients from the latter group. The lesions of the fair colour-naming patients spared the lingual and fusiform gyri, which are known to be engaged in colour processing. Patients with neglect whose visual field is preserved may neglect the leftward extension of a line but not the colour in the neglected space. The poor colour-naming patients frequently failed to name the left-end colour that appeared to the left of their subjective midpoint, which indicates that they hardly searched leftward beyond that point. In such trials, they reported that the left end had the same colour as the right end. The results suggest that in patients with neglect and left visual field defect, both the leftward extent and the colour of a line may be represented on the basis of the information from the attended right segment.

Correlation of Retinal Nerve Fiber Layer Thickness and Visual Fields in Glaucoma: A broken stick model

PubMed Central

Alasil, Tarek; Wang, Kaidi; Yu, Fei; Field, Matthew G.; Lee, Hang; Baniasadi, Neda; de Boer, Johannes F.; Coleman, Anne L.; Chen, Teresa C.

2015-01-01

Purpose To determine the retinal nerve fiber layer (RNFL) thickness at which visual field (VF) damage becomes detectable and associated with structural loss. Design Retrospective cross-sectional study. Methods Eighty seven healthy and 108 glaucoma subjects (one eye per subject) were recruited from an academic institution. All patients had VF examinations (Swedish Interactive Threshold Algorithm 24-2 test of the Humphrey visual field analyzer 750i; Carl Zeiss Meditec, Dublin, CA) and spectral domain optical coherence tomography RNFL scans (Spectralis, Heidelberg Engineering, Heidelberg, Germany). Comparison of RNFL thicknesses values with VF threshold values showed a plateau of VF threshold values at high RNFL thickness values and then a sharp decrease at lower RNFL thickness values. A broken stick statistical analysis was utilized to estimate the tipping point at which RNFL thickness values are associated with VF defects. The slope for the association between structure and function was computed for data above and below the tipping point. Results The mean RNFL thickness value that was associated with initial VF loss was 89 μm. The superior RNFL thickness value that was associated with initial corresponding inferior VF loss was 100 μm. The inferior RNFL thickness value that was associated with initial corresponding superior VF loss was 73 μm. The differences between all the slopes above and below the aforementioned tipping points were statistically significant (p<0.001). Conclusions In open angle glaucoma, substantial RNFL thinning or structural loss appears to be necessary before functional visual field defects become detectable. PMID:24487047

Visual field protective effect of Erigeron breviscapus (vant.) Hand. Mazz. extract on glaucoma with controlled intraocular pressure: a randomized, double-blind, clinical trial.

PubMed

Zhong, Yisheng; Xiang, Minhong; Ye, Wen; Cheng, Yu; Jiang, Youqin

2010-01-01

To evaluate the visual field protective effect of Erigeron breviscapus (vant.) Hand. Mazz. (EBHM) extract on glaucoma with controlled intraocular pressure (IOP). Forty patients (40 eyes) with primary open-angle glaucoma, visual field defects and a postsurgical IOP of <18 mmHg were enrolled. The EBHM and placebo tablets were given orally according to the randomized and double-blind principle. Two tablets (of either EBHM or placebo) were taken three times a day for a period of 6 months. Patients were examined every 2 months after treatment commenced. At the end of the study, the results were given to the drug manufacturer. All patients completed the prospective, randomized, double-blind, clinical trial. No obvious adverse effects were found in patients during the treatment period. In the placebo group, no significant difference was found in mean defect (MD) or mean sensitivity (MS) between the values at pre-treatment and after 2, 4, and 6 months of treatment. After 6 months of EBHM treatment, the MD was significantly decreased and the MS was significantly increased compared with pre-treatment (p < 0.05). In the patients with moderate and late glaucoma, the MD was significantly decreased and the MS was significantly increased after 2, 4, and 6 months of EBHM treatment compared with pre-treatment. EBHM extract may have a partial protective effect on the visual field of glaucoma patients with controlled IOP. Further studies are needed to determine the safety and effectiveness of long-term EBHM treatment.

Correlation of macular structure and function in a boy with primary foveomacular retinitis and sequence of changes over 5 years.

PubMed

Badhani, Anurag; Padhi, Tapas Ranjan; Panda, Gopal Krishna; Mukherjee, Sujoy; Das, Taraprasad; Jalali, Subhadra

2017-08-01

To describe the clinical characteristics, macular structure and function, and to document sequential changes over 5 years in a 10-year-old boy with bilateral primary foveomacular retinitis. A 10-year-old boy presented with sudden onset scotoma in both eyes, experienced after getting up from bed on a non-eclipse day. He persistently denied direct sun-gazing. He neither had any significant systemic illness, nor was using any medications. In addition to a detailed examination at presentation that included fundus fluorescein angiogram (FFA), electroretinogram (ERG), pattern ERG and electrooculogram (EOG), he was examined periodically for 5 years with Humphrey visual field (HVF), spectral domain optical coherence tomogram (SDOCT), Amsler grid charting and multifocal ERG. The macular structure and functions were analyzed over the years and correlated with the symptoms. All findings were bilaterally symmetrical at each visit. At presentation, his corrected visual acuity was 20/25 with subfoveal yellow dot similar to solar retinopathy, central scotoma with reduced foveal threshold in HVF 24-2, micropsia in Amsler grid, missing of two plates on Ishihara color vision chart, transfoveal full thickness hyper-reflective band on SD OCT, unremarkable FFA and normal foveal peak in mfERG. The flash ERG and EOG were unremarkable. A month later, his VA improved to 20/20, he had relative scotoma in Amsler grid, no scotoma in HVF (10-2), restoration of the inner segment of the photoreceptors with sharp defect involving ellipsoid and photoreceptor interdigitation zone in SDOCT and blunting of foveal peaks in mfERG. Three months later, his corrected VA was 20/20 with relative scotoma in Amsler grid, normal color vision, no scotoma in HVF 10-2 and unchanged SDOCT findings. In subsequent examinations at 6, 9, 14, 29, 39 and 60 months, he was symptomless with VA 20/20, unremarkable fundus, normal Amsler grid and HVF (normal foveal threshold), unchanged SDOCT findings and the reduced foveal peaks on mfERG in both eyes got normalized only at 60 months. Presented here is a case of bilaterally symmetrical idiopathic foveomacular retinitis that had a clinical appearance similar to solar retinopathy. The fundus changes persisted for 4 weeks, the symptoms and changes in Amsler grid lasted for 3 months, and the foveal threshold in visual fields normalized within 3 months. Maximum change in the SDOCT defect occurred within a month, and the extrafoveal defect in the ellipsoid and photoreceptor interdigitation line persisted despite resolution of symptoms and resolution of the visual field defect and normal distance vision. Probably, the foveal lesion detected on SDOCT was too small to cause a reduction in the distance visual acuity or show up in the visual field and mfERG later.

Mechanisms Underlying Development of Visual Maps and Receptive Fields

PubMed Central

Huberman, Andrew D.; Feller, Marla B.; Chapman, Barbara

2008-01-01

Patterns of synaptic connections in the visual system are remarkably precise. These connections dictate the receptive field properties of individual visual neurons and ultimately determine the quality of visual perception. Spontaneous neural activity is necessary for the development of various receptive field properties and visual feature maps. In recent years, attention has shifted to understanding the mechanisms by which spontaneous activity in the developing retina, lateral geniculate nucleus, and visual cortex instruct the axonal and dendritic refinements that give rise to orderly connections in the visual system. Axon guidance cues and a growing list of other molecules, including immune system factors, have also recently been implicated in visual circuit wiring. A major goal now is to determine how these molecules cooperate with spontaneous and visually evoked activity to give rise to the circuits underlying precise receptive field tuning and orderly visual maps. PMID:18558864

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

PubMed

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

2010-03-05

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

Gamma-Aminobutyric Acid Concentration is Reduced in Visual Cortex in Schizophrenia and Correlates with Orientation-Specific Surround Suppression

PubMed Central

Yoon, Jong H.; Maddock, Richard J.; Rokem, Ariel; Silver, Michael A.; Minzenberg, Michael J.; Ragland, J. Daniel; Carter, Cameron S.

2010-01-01

The neural mechanisms underlying cognitive deficits in schizophrenia remain largely unknown. The gamma-aminobutyric acid (GABA) hypothesis proposes that reduced neuronal GABA concentration and neurotransmission results in cognitive impairments in schizophrenia. However, few in vivo studies have directly examined this hypothesis. We employed magnetic resonance spectroscopy (MRS) at high field to measure visual cortical GABA levels in 13 subjects with schizophrenia and 13 demographically matched healthy control subjects. We found that the schizophrenia group had an approximately 10% reduction in GABA concentration. We further tested the GABA hypothesis by examining the relationship between visual cortical GABA levels and orientation-specific surround suppression (OSSS), a behavioral measure of visual inhibition thought to be dependent on GABAergic synaptic transmission. Previous work has shown that subjects with schizophrenia exhibit reduced OSSS of contrast discrimination (Yoon et al., 2009). For subjects with both MRS and OSSS data (n=16), we found a highly significant positive correlation (r=0.76) between these variables. GABA concentration was not correlated with overall contrast discrimination performance for stimuli without a surround (r=-0.10). These results suggest that a neocortical GABA deficit in subjects with schizophrenia leads to impaired cortical inhibition and that GABAergic synaptic transmission in visual cortex plays a critical role in OSSS. PMID:20220012

GABA concentration is reduced in visual cortex in schizophrenia and correlates with orientation-specific surround suppression.

PubMed

Yoon, Jong H; Maddock, Richard J; Rokem, Ariel; Silver, Michael A; Minzenberg, Michael J; Ragland, J Daniel; Carter, Cameron S

2010-03-10

The neural mechanisms underlying cognitive deficits in schizophrenia remain essentially unknown. The GABA hypothesis proposes that reduced neuronal GABA concentration and neurotransmission results in cognitive impairments in schizophrenia. However, few in vivo studies have directly examined this hypothesis. We used magnetic resonance spectroscopy (MRS) at high field to measure visual cortical GABA levels in 13 subjects with schizophrenia and 13 demographically matched healthy control subjects. We found that the schizophrenia group had an approximately 10% reduction in GABA concentration. We further tested the GABA hypothesis by examining the relationship between visual cortical GABA levels and orientation-specific surround suppression (OSSS), a behavioral measure of visual inhibition thought to be dependent on GABAergic synaptic transmission. Previous work has shown that subjects with schizophrenia exhibit reduced OSSS of contrast discrimination (Yoon et al., 2009). For subjects with both MRS and OSSS data (n = 16), we found a highly significant positive correlation (r = 0.76) between these variables. GABA concentration was not correlated with overall contrast discrimination performance for stimuli without a surround (r = -0.10). These results suggest that a neocortical GABA deficit in subjects with schizophrenia leads to impaired cortical inhibition and that GABAergic synaptic transmission in visual cortex plays a critical role in OSSS.

The mapping of the visual field onto the dorso-lateral tectum of the pigeon (Columba livia) and its relations with retinal specializations.

PubMed

Letelier, Juan-Carlos; Marin, Gonzalo; Sentis, Elisa; Tenreiro, Andrea; Fredes, Felipe; Mpodozis, Jorge

2004-01-30

Most of the physiological studies of the pigeon retino-tectal visual pathway have investigated the accessible tectum, a small dorso-lateral tectal section that can be easily accessed by a simple craniotomy. However, at present we lack a detailed study of the topographical arrangement between the visual field, the retina and the accessible tectum. In particular, it is not known which section of the visual field is mapped onto the accessible tectum, and which of the specialized retinal areas mediates this projection. Here we determined, using local field potential (LFP) recordings and reverse retinoscopy, the shape, size and position in the visual space of the portion of the visual field mapped onto the accessible tectum (called here the accessible visual field, or AVF). Using this data and the mapping of Nalbach et al. [Vis. Res. 30 (4) (1990) 529], the retinal area corresponding to the AVF was determined. Such retinal area was also directly delimited by means of retrograde transport of DiI. The results indicate that the AVF is a triangular perifoveal zone encompassing only 15% of total visual field. The retinal region corresponding to the AVF has the shape of an elongated triangle that runs parallel to the visual equator and contains the fovea, the tip of the pecten, a perifoveal region of the yellow field and a small crescent of the red field. In agreement with this anatomical heterogeneity, visual evoked potentials measured in different parts of the accessible tectum present steep variations in shape and size. These results are helpful to better design and interpret anatomical and physiological experiments involving the pigeon's visual system.

The use of Bruch's membrane opening-based optical coherence tomography of the optic nerve head for glaucoma detection in microdiscs.

PubMed

Enders, Philip; Schaub, Friederike; Adler, Werner; Nikoluk, Roman; Hermann, Manuel M; Heindl, Ludwig M

2017-04-01

To assess the performance of Bruch's membrane opening (BMO)-based spectral domain optical coherence tomography (SD-OCT) of the optic nerve head for glaucoma detection in microdiscs in comparison with confocal scanning laser tomography (CSLT). Retrospective cohort study. 82 eyes of 82 patients with disc size <1.63 mm 2 underwent SD-OCT and CSLT measurements, visual field testing and clinical examination. BMO-based minimal rim width (BMO-MRW), retinal nerve fibre layer thickness (RNFLT) in SD-OCT and rim area measured in CSLT were compared and correlated with visual field defects. 51 patients with glaucoma, 11 patients with ocular hypertension (OHT) and 20 healthy controls had a mean disc area of 1.36±0.19 mm 2 in CSLT, and BMO area was 1.45±0.22 mm 2 (r=0.17; p=0.12). In patients with glaucoma, visual field mean defect was -7.5±6.7 dB. Global BMO-MRW correlated better with visual field function (Spearman's r=0.65; p<0.001) than RNFLT (r=0.58; p≤0.001) and CSLT rim area (r=0.47; p=0.004). BMO-MRW significantly deteriorated with progressive visual field loss (p<0.001). In receiver operating characteristic analysis, sensitivity of BMO-MRW was 68.6% at 95% specificity (area under curve (AUC)=0.87), similar to sensitivity of RNFLT (66.4%; AUC=0.81). Performance of CSLT rim area was significantly worse (AUC=0.70, p=0.008). In healthy controls, mean BMO-MRW was 344.3±64.1 µm, mean RNFLT 78.0±11.3 µm and CSLT mean rim area 1.07±0.18 mm 2 . In small optic discs, BMO-MRW and peripapillary RNFLT (OCT) have similar sensitivity to discriminate patients with glaucoma from normal controls; both exceed CSLT rim area in diagnostic power. In glaucomatous patients, BMO-MRW correlates strongest with visual field function. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Visual field impairment captures disease burden in multiple sclerosis.

PubMed

Ortiz-Perez, Santiago; Andorra, Magí; Sanchez-Dalmau, Bernardo; Torres-Torres, Rubén; Calbet, David; Lampert, Erika J; Alba-Arbalat, Salut; Guerrero-Zamora, Ana M; Zubizarreta, Irati; Sola-Valls, Nuria; Llufriu, Sara; Sepúlveda, María; Saiz, Albert; Villoslada, Pablo; Martinez-Lapiscina, Elena H

2016-04-01

Monitoring disease burden is an unmeet need in multiple sclerosis (MS). Identifying patients at high risk of disability progression will be useful for improving clinical-therapeutic decisions in clinical routine. To evaluate the role of visual field testing in non-optic neuritis eyes (non-ON eyes) as a biomarker of disability progression in MS. In 109 patients of the MS-VisualPath cohort, we evaluated the association between visual field abnormalities and global and cognitive disability markers and brain and retinal imaging markers of neuroaxonal injury using linear regression models adjusted for sex, age, disease duration and use of disease-modifying therapies. We evaluated the risk of disability progression associated to have baseline impaired visual field after 3 years of follow-up. Sixty-two percent of patients showed visual field defects in non-ON eyes. Visual field mean deviation was statistically associated with global disability; brain (normalized brain parenchymal, gray matter volume and lesion load) and retinal (peripapillary retinal nerve fiber layer thickness and macular ganglion cell complex thickness) markers of neuroaxonal damage. Patients with impaired visual field had statistically significative greater disability, lower normalized brain parenchymal volume and higher lesion volume than patients with normal visual field testing. MS patients with baseline impaired VF tripled the risk of disability progression during follow-up [OR = 3.35; 95 % CI (1.10-10.19); p = 0.033]. The association of visual field impairment with greater disability and neuroaxonal injury and higher risk of disability progression suggest that VF could be used to monitor MS disease burden.

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

PubMed Central

Gangeddula, Viswa; Ranchet, Maud; Akinwuntan, Abiodun E.; Bollinger, Kathryn; Devos, Hannes

2017-01-01

Purpose: To investigate the effect of cognitive demand on functional visual field performance in drivers with glaucoma. Method: This study included 20 drivers with open-angle glaucoma and 13 age- and sex-matched controls. Visual field performance was evaluated under different degrees of cognitive demand: a static visual field condition (C1), dynamic visual field condition (C2), and dynamic visual field condition with active driving (C3) using an interactive, desktop driving simulator. The number of correct responses (accuracy) and response times on the visual field task were compared between groups and between conditions using Kruskal–Wallis tests. General linear models were employed to compare cognitive workload, recorded in real-time through pupillometry, between groups and conditions. Results: Adding cognitive demand (C2 and C3) to the static visual field test (C1) adversely affected accuracy and response times, in both groups (p < 0.05). However, drivers with glaucoma performed worse than did control drivers when the static condition changed to a dynamic condition [C2 vs. C1 accuracy; glaucoma: median difference (Q1–Q3) 3 (2–6.50) vs. controls: 2 (0.50–2.50); p = 0.05] and to a dynamic condition with active driving [C3 vs. C1 accuracy; glaucoma: 2 (2–6) vs. controls: 1 (0.50–2); p = 0.02]. Overall, drivers with glaucoma exhibited greater cognitive workload than controls (p = 0.02). Conclusion: Cognitive demand disproportionately affects functional visual field performance in drivers with glaucoma. Our results may inform the development of a performance-based visual field test for drivers with glaucoma. PMID:28912712

Salience Is Only Briefly Represented: Evidence from Probe-Detection Performance

ERIC Educational Resources Information Center

Donk, Mieke; Soesman, Leroy

2010-01-01

Salient objects in the visual field tend to capture attention. The present study aimed to examine the time-course of salience effects using a probe-detection task. Eight experiments investigated how the salience of different orientation singletons affected probe reaction time as a function of stimulus onset asynchrony (SOA) between the…

Learner Perspectives on Task Design for Oral-Visual eTandem Language Learning

ERIC Educational Resources Information Center

El-Hariri, Yasmin

2016-01-01

Constituting a more specific form of online collaboration, eTandem Language Learning (eTLL) shows great potential for non-formal, self-directed language learning. Research in this field, particularly regarding task design, is still scarce. Focusing on their beliefs and attitudes, this article examines what learners think about how…

Personal Lineages and the Development of Community Psychology: 1965 to 2005

ERIC Educational Resources Information Center

Fowler, Patrick J.; Toro, Paul A.

2008-01-01

The purpose of this study was twofold: (a) to examine and document the role of personal influence in the history of community psychology, and (b) to measure the field's inclusion of traditionally marginalized populations. In addition to presenting visually the genealogy of community psychology, results suggest that people have mattered in the…

Hemispheric Differences in Bilingual Word and Language Recognition.

ERIC Educational Resources Information Center

Roberts, William T.; And Others

The linguistic role of the right hemisphere in bilingual language processing was examined. Ten right-handed Spanish-English bilinguals were tachistoscopically presented with mixed lists of Spanish and English words to either the right or left visual field and asked to identify the language and the word presented. Five of the subjects identified…

Investigating Student Ideas about Cosmology I: Distances and Structure

ERIC Educational Resources Information Center

Coble, Kim; Camarillo, Carmen T.; Nickerson, Melissa D.; Trouille, Laura E.; Bailey, Janelle M.; Cochran, Geraldine L.; Cominsky, Lynn R.

2013-01-01

Recently, powerful new observations and advances in computation and visualization have led to a revolution in our understanding of the structure of the Universe. As the field of cosmology advances, it is of interest to study how student ideas relate to scientific understanding. In this paper, we examine in-depth undergraduate students' ideas on…

Exploratory survey for the emerald ash borer, Agrilus planipennis (Coleoptera: Buprestidae), and its natural enemies in China.

Treesearch

Houping Liu; Leah S. Bauer; Ruitong Gao; Tonghai Zhao; Toby R. Petrice; Robert A. Haack

2003-01-01

An exploratory survey for the emerald ash borer, Agrilus planipennis, and its natural enemies was conducted in China during October and November 2003. We examined 29 field plots in six provinces. We visually inspected living Fraxinus chinensis, F. mandshurica, F. pennsylvanica, F. rhynchophylla, and F. velutina...

Converging Recommendations for Culturally Responsive Literacy Practices: Students with Learning Disabilities, English Language Learners, and Socioculturally Diverse Learners

ERIC Educational Resources Information Center

Piazza, Susan V.; Rao, Shaila; Protacio, Maria Selena

2015-01-01

This study examines culturally responsive pedagogy across the fields of special education, multicultural literacy education, and teaching English language learners. A systematic review of recommendations identified culturally responsive practices in five key areas: dialogue, collaboration, visual representation, explicit instruction, and inquiry.…

Driving and Low Vision: Validity of Assessments for Predicting Performance of Drivers

ERIC Educational Resources Information Center

Strong, J. Graham; Jutai, Jeffrey W.; Russell-Minda, Elizabeth; Evans, Mal

2008-01-01

The authors conducted a systematic review to examine whether vision-related assessments can predict the driving performance of individuals who have low vision. The results indicate that measures of visual field, contrast sensitivity, cognitive and attention-based tests, and driver screening tools have variable utility for predicting real-world…

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

PubMed

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

2014-01-01

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

Optical cylinder designs to increase the field of vision in the osteo-odonto-keratoprosthesis.

PubMed

Hull, C C; Liu, C S; Sciscio, A; Eleftheriadis, H; Herold, J

2000-12-01

The single optical cylinders used in the osteo-odonto-keratoprosthesis (OOKP) are known to produce very small visual fields. Values of 40 degrees are typically quoted. The purpose of this paper is to present designs for new optical cylinders that significantly increase the field of view and therefore improve the visual rehabilitation of patients having an OOKP. Computer ray-tracing techniques were used to design and analyse improved one- and two-piece optical cylinders made from polymethyl methacrylate. All designs were required to have a potential visual acuity of 6/6 before consideration was given to the visual field and optimising off-axis image quality. Aspheric surfaces were used where this significantly improved off-axis image quality. Single optical cylinders, with increased posterior cylinder (intraocular) diameters, gave an increase in the theoretical visual field of 18% (from 76 degrees to 90 degrees) over current designs. Two-piece designs based on an inverted telephoto principle gave theoretical field angles over 120 degrees. Aspheric surfaces were shown to improve the off-axis image quality while maintaining a potential visual acuity of at least 6/6. This may well increase the measured visual field by improving the retinal illuminance off-axis. Results demonstrate that it is possible to significantly increase the theoretical maximum visual field through OOKP optical cylinders. Such designs will improve the visual rehabilitation of patients undergoing this procedure.

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

NASA Astrophysics Data System (ADS)

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

1995-01-01

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

Fundus white spots and acquired night blindness due to vitamin A deficiency.

PubMed

Genead, Mohamed A; Fishman, Gerald A; Lindeman, Martin

2009-12-01

To report a successfully treated case of acquired night blindness associated with fundus white spots secondary to vitamin A deficiency. An ocular examination, electrophysiologic testing, as well as visual field and OCT examinations were obtained on a 61-year-old man with vitamin A deficiency who had previously undergone gastric bypass surgery. The patient had a re-evaluation after treatment with high doses of oral vitamin A. The patient was observed to have numerous white spots in the retina of each eye. Best-corrected visual acuity was initially 20/80 in each eye, which improved to 20/40-1 OU after oral vitamin A therapy for 2 months. Full field electroretinogram (ERG) testing, showed non-detectable rod function and a 34 and 41% reduction for 32-Hz flicker and single flash cone responses, respectively, below the lower limits of normal. Both rod and cone functions markedly improved after initiation of vitamin A therapy. Vitamin A deficiency needs to be considered in a patient with white spots of the retina in the presence of poor night vision.

Driving with Binocular Visual Field Loss? A Study on a Supervised On-Road Parcours with Simultaneous Eye and Head Tracking

PubMed Central

Aehling, Kathrin; Heister, Martin; Rosenstiel, Wolfgang; Schiefer, Ulrich; Papageorgiou, Elena

2014-01-01

Post-chiasmal visual pathway lesions and glaucomatous optic neuropathy cause binocular visual field defects (VFDs) that may critically interfere with quality of life and driving licensure. The aims of this study were (i) to assess the on-road driving performance of patients suffering from binocular visual field loss using a dual-brake vehicle, and (ii) to investigate the related compensatory mechanisms. A driving instructor, blinded to the participants' diagnosis, rated the driving performance (passed/failed) of ten patients with homonymous visual field defects (HP), including four patients with right (HR) and six patients with left homonymous visual field defects (HL), ten glaucoma patients (GP), and twenty age and gender-related ophthalmologically healthy control subjects (C) during a 40-minute driving task on a pre-specified public on-road parcours. In order to investigate the subjects' visual exploration ability, eye movements were recorded by means of a mobile eye tracker. Two additional cameras were used to monitor the driving scene and record head and shoulder movements. Thus this study is novel as a quantitative assessment of eye movements and an additional evaluation of head and shoulder was performed. Six out of ten HP and four out of ten GP were rated as fit to drive by the driving instructor, despite their binocular visual field loss. Three out of 20 control subjects failed the on-road assessment. The extent of the visual field defect was of minor importance with regard to the driving performance. The site of the homonymous visual field defect (HVFD) critically interfered with the driving ability: all failed HP subjects suffered from left homonymous visual field loss (HL) due to right hemispheric lesions. Patients who failed the driving assessment had mainly difficulties with lane keeping and gap judgment ability. Patients who passed the test displayed different exploration patterns than those who failed. Patients who passed focused longer on the central area of the visual field than patients who failed the test. In addition, patients who passed the test performed more glances towards the area of their visual field defect. In conclusion, our findings support the hypothesis that the extent of visual field per se cannot predict driving fitness, because some patients with HVFDs and advanced glaucoma can compensate for their deficit by effective visual scanning. Head movements appeared to be superior to eye and shoulder movements in predicting the outcome of the driving test under the present study scenario. PMID:24523869

Differences in Visual-Spatial Input May Underlie Different Compression Properties of Firing Fields for Grid Cell Modules in Medial Entorhinal Cortex

PubMed Central

Raudies, Florian; Hasselmo, Michael E.

2015-01-01

Firing fields of grid cells in medial entorhinal cortex show compression or expansion after manipulations of the location of environmental barriers. This compression or expansion could be selective for individual grid cell modules with particular properties of spatial scaling. We present a model for differences in the response of modules to barrier location that arise from different mechanisms for the influence of visual features on the computation of location that drives grid cell firing patterns. These differences could arise from differences in the position of visual features within the visual field. When location was computed from the movement of visual features on the ground plane (optic flow) in the ventral visual field, this resulted in grid cell spatial firing that was not sensitive to barrier location in modules modeled with small spacing between grid cell firing fields. In contrast, when location was computed from static visual features on walls of barriers, i.e. in the more dorsal visual field, this resulted in grid cell spatial firing that compressed or expanded based on the barrier locations in modules modeled with large spacing between grid cell firing fields. This indicates that different grid cell modules might have differential properties for computing location based on visual cues, or the spatial radius of sensitivity to visual cues might differ between modules. PMID:26584432

A conditioned visual orientation requires the ellipsoid body in Drosophila

PubMed Central

Guo, Chao; Du, Yifei; Yuan, Deliang; Li, Meixia; Gong, Haiyun; Gong, Zhefeng

2015-01-01

Orientation, the spatial organization of animal behavior, is an essential faculty of animals. Bacteria and lower animals such as insects exhibit taxis, innate orientation behavior, directly toward or away from a directional cue. Organisms can also orient themselves at a specific angle relative to the cues. In this study, using Drosophila as a model system, we established a visual orientation conditioning paradigm based on a flight simulator in which a stationary flying fly could control the rotation of a visual object. By coupling aversive heat shocks to a fly's orientation toward one side of the visual object, we found that the fly could be conditioned to orientate toward the left or right side of the frontal visual object and retain this conditioned visual orientation. The lower and upper visual fields have different roles in conditioned visual orientation. Transfer experiments showed that conditioned visual orientation could generalize between visual targets of different sizes, compactness, or vertical positions, but not of contour orientation. Rut—Type I adenylyl cyclase and Dnc—phosphodiesterase were dispensable for visual orientation conditioning. Normal activity and scb signaling in R3/R4d neurons of the ellipsoid body were required for visual orientation conditioning. Our studies established a visual orientation conditioning paradigm and examined the behavioral properties and neural circuitry of visual orientation, an important component of the insect's spatial navigation. PMID:25512578

MR findings of Minamata disease--organic mercury poisoning.

PubMed

Korogi, Y; Takahashi, M; Okajima, T; Eto, K

1998-01-01

We describe MR findings in patients with Minamata disease who have been followed for a long time. All patients examined were affected after daily eating of a large quantity of methylmercury-contaminated seafood, from 1955 to 1958, and showed typical neurological findings. On MR images, the visual cortex, the cerebellar vermis and hemispheres, and the postcentral cortex are significantly atrophic in Minamata disease. The visual cortex is slightly hypointense on T1-weighted images and hyperintense on T2-weighted images, probably representing the pathologic changes of status spongiosus. MRI can demonstrate the lesions located in the calcarine area, cerebellum, and postcentral gyri, which are probably related to three of the characteristic manifestations of this disease: the constriction of the visual fields, ataxia, and sensory disturbance, respectively.

Evaluation of afferent pain pathways in adrenomyeloneuropathic patients.

PubMed

Yagüe, Sara; Veciana, Misericordia; Casasnovas, Carlos; Ruiz, Montserrat; Pedro, Jordi; Valls-Solé, Josep; Pujol, Aurora

2018-03-01

Patients with adrenomyeloneuropathy may have dysfunctions of visual, auditory, motor and somatosensory pathways. We thought on examining the nociceptive pathways by means of laser evoked potentials (LEPs), to obtain additional information on the pathophysiology of this condition. In 13 adrenomyeloneuropathic patients we examined LEPs to leg, arm and face stimulation. Normative data were obtained from 10 healthy subjects examined in the same experimental conditions. We also examined brainstem auditory evoked potentials (BAEPs), pattern reversal full-field visual evoked potentials (VEPs), motor evoked potentials (MEPs) and somatosensory evoked potentials (SEPs). Upper and lower limb MEPs and SEPs, as well as BAEPs, were abnormal in all patients, while VEPs were abnormal in 3 of them (23.1%). LEPs revealed abnormalities to stimulation of the face in 4 patients (30.7%), the forearm in 4 patients (30.7%) and the leg in 10 patients (76.9%). The pathologic process of adrenomyeloneuropathy is characterized by a preferential involvement of auditory, motor and somatosensory tracts and less severely of the visual and nociceptive pathways. This non-inflammatory distal axonopathy preferably damages large myelinated spinal tracts but there is also partial involvement of small myelinated fibres. LEPs studies can provide relevant information about afferent pain pathways involvement in adrenomyeloneuropathic patients. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Usher's syndrome--case report.

PubMed

Kwiecień, Sława; Sulak, Robert; Szaflik, Jerzy

2008-01-01

The aim of this study is to present a case of coincidence of sensorineural hearing loss with chronic recurrent bilateral cystoid macular oedema in a 32-year-old woman, who was admitted to the clinic for deterioration of visual acuity of four months' duration. The patient gave a history of hearing loss for 29 years. Visual field examination disclosed peripheral ring scotoma. Electrophysiological examination was performed: pattern visual evoked response was within normal limits and electroretinogram displayed diminished both photopic and scotopic response. As ophthalmoscopy demonstrated no pigment in the fundus of the eye, the findings were consisted with diagnosis of retinitis pigmentosis sine pigmento. The presence of loss of hearing indicated the necessity of performing the genetic examination for Usher's syndrome. In order to establish a final diagnosis of Usher's syndrome genetic examination must be performed, but family history is relevant. Early investigation for Usher's syndrome in children with sensorineural hearing impairment is of a great significance. The patient may develop symptoms of retinitis pigmentosa in second or even third decade of his life. The necessity of thorough investigation for detecting other systemic abnormalities should be emphasized. There is no effective treatment of this syndrome. A child with Usher's syndrome requires a comprehensive care of different medical specialties. Psychological, educational and sociological attitude is also of a great importance in the child development.

Visual analytics in healthcare education: exploring novel ways to analyze and represent big data in undergraduate medical education

PubMed Central

Nilsson, Gunnar; Zary, Nabil

2014-01-01

Introduction. The big data present in the medical curriculum that informs undergraduate medical education is beyond human abilities to perceive and analyze. The medical curriculum is the main tool used by teachers and directors to plan, design, and deliver teaching and assessment activities and student evaluations in medical education in a continuous effort to improve it. Big data remains largely unexploited for medical education improvement purposes. The emerging research field of visual analytics has the advantage of combining data analysis and manipulation techniques, information and knowledge representation, and human cognitive strength to perceive and recognize visual patterns. Nevertheless, there is a lack of research on the use and benefits of visual analytics in medical education. Methods. The present study is based on analyzing the data in the medical curriculum of an undergraduate medical program as it concerns teaching activities, assessment methods and learning outcomes in order to explore visual analytics as a tool for finding ways of representing big data from undergraduate medical education for improvement purposes. Cytoscape software was employed to build networks of the identified aspects and visualize them. Results. After the analysis of the curriculum data, eleven aspects were identified. Further analysis and visualization of the identified aspects with Cytoscape resulted in building an abstract model of the examined data that presented three different approaches; (i) learning outcomes and teaching methods, (ii) examination and learning outcomes, and (iii) teaching methods, learning outcomes, examination results, and gap analysis. Discussion. This study identified aspects of medical curriculum that play an important role in how medical education is conducted. The implementation of visual analytics revealed three novel ways of representing big data in the undergraduate medical education context. It appears to be a useful tool to explore such data with possible future implications on healthcare education. It also opens a new direction in medical education informatics research. PMID:25469323

Visual analytics in healthcare education: exploring novel ways to analyze and represent big data in undergraduate medical education.

PubMed

Vaitsis, Christos; Nilsson, Gunnar; Zary, Nabil

2014-01-01

Introduction. The big data present in the medical curriculum that informs undergraduate medical education is beyond human abilities to perceive and analyze. The medical curriculum is the main tool used by teachers and directors to plan, design, and deliver teaching and assessment activities and student evaluations in medical education in a continuous effort to improve it. Big data remains largely unexploited for medical education improvement purposes. The emerging research field of visual analytics has the advantage of combining data analysis and manipulation techniques, information and knowledge representation, and human cognitive strength to perceive and recognize visual patterns. Nevertheless, there is a lack of research on the use and benefits of visual analytics in medical education. Methods. The present study is based on analyzing the data in the medical curriculum of an undergraduate medical program as it concerns teaching activities, assessment methods and learning outcomes in order to explore visual analytics as a tool for finding ways of representing big data from undergraduate medical education for improvement purposes. Cytoscape software was employed to build networks of the identified aspects and visualize them. Results. After the analysis of the curriculum data, eleven aspects were identified. Further analysis and visualization of the identified aspects with Cytoscape resulted in building an abstract model of the examined data that presented three different approaches; (i) learning outcomes and teaching methods, (ii) examination and learning outcomes, and (iii) teaching methods, learning outcomes, examination results, and gap analysis. Discussion. This study identified aspects of medical curriculum that play an important role in how medical education is conducted. The implementation of visual analytics revealed three novel ways of representing big data in the undergraduate medical education context. It appears to be a useful tool to explore such data with possible future implications on healthcare education. It also opens a new direction in medical education informatics research.

Maintaining perceptual constancy while remaining vigilant: left hemisphere change blindness and right hemisphere vigilance.

PubMed

Vos, Leia; Whitman, Douglas

2014-01-01

A considerable literature suggests that the right hemisphere is dominant in vigilance for novel and survival-related stimuli, such as predators, across a wide range of species. In contrast to vigilance for change, change blindness is a failure to detect obvious changes in a visual scene when they are obscured by a disruption in scene presentation. We studied lateralised change detection using a series of scenes with salient changes in either the left or right visual fields. In Study 1 left visual field changes were detected more rapidly than right visual field changes, confirming a right hemisphere advantage for change detection. Increasing stimulus difficulty resulted in greater right visual field detections and left hemisphere detection was more likely when change occurred in the right visual field on a prior trial. In Study 2 an intervening distractor task disrupted the influence of prior trials. Again, faster detection speeds were observed for the left visual field changes with a shift to a right visual field advantage with increasing time-to-detection. This suggests that a right hemisphere role for vigilance, or catching attention, and a left hemisphere role for target evaluation, or maintaining attention, is present at the earliest stage of change detection.

Relevance of wide-field autofluorescence imaging in Birdshot retinochoroidopathy: descriptive analysis of 76 eyes.

PubMed

Piffer, Anne-Laure Le; Boissonnot, Michèle; Gobert, Frédéric; Zenger, Anita; Wolf, Sebastian; Wolf, Ute; Korobelnik, Jean-François; Rougier, Marie-Bénédicte

2014-09-01

To study and classify retinal lesions in patients with birdshot disease using wide-field autofluorescence imaging and correlate them according to patients' visual status. A multicentre study was carried out on 76 eyes of 39 patients with birdshot disease, analysing colour images and under autofluorescence using the wide-field Optomap(®) imaging system. This was combined with a complete clinical exam and analysis of the macula with OCT. In over 80% of the eyes, a chorioretinal lesion has been observed under autofluorescence with a direct correlation between the extent of the lesion and visual status. The presence of macular hypo-autofluorescence was correlated with a decreased visual acuity, due to the presence of a macular oedema, active clinical inflammation or an epiretinal membrane. The hypo-autofluorescence observed correlated with the duration of the disease and the degree of inflammation in the affected eye, indicating a secondary lesion in the pigment epithelium in relation to the choroid. The pigment epithelium was affected in a diffuse manner, as in almost 50% of the eyes the wider peripheral retina was affected. Wide-field autofluorescence imaging could appear to be a useful examination when monitoring patients, to look for areas of macular hypo-autofluorescence responsible for an irreversible loss of vision. © 2013 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

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

Code of Federal Regulations, 2010 CFR

2010-07-01

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

Physiological and morphological characterization of ganglion cells in the salamander retina

PubMed Central

Wang, Jing; Jacoby, Roy; Wu, Samuel M.

2016-01-01

Retinal ganglion cells (RGCs) integrate visual information from the retina and transmit collective signals to the brain. A systematic investigation of functional and morphological characteristics of various types of RGCs is important to comprehensively understand how the visual system encodes and transmits information via various RGC pathways. This study evaluated both physiological and morphological properties of 67 RGCs in dark-adapted flat-mounted salamander retina by examining light-evoked cation and chloride current responses via voltage-clamp recordings and visualizing morphology by Lucifer yellow fluorescence with a confocal microscope. Six groups of RGCs were described: asymmetrical ON–OFF RGCs, symmetrical ON RGCs, OFF RGCs, and narrow-, medium- and wide-field ON–OFF RGCs. Dendritic field diameters of RGCs ranged 102–490 µm: narrow field (<200 µm, 31% of RGCs), medium field (200–300 µm, 45%) and wide field (>300 µm, 24%). Dendritic ramification patterns of RGCs agree with the sub-lamina A/B rule. 34% of RGCs were monostratified, 24% bistratified and 42% diffusely stratified. 70% of ON RGCs and OFF RGCs were monostratified. Wide-field RGCs were diffusely stratified. 82% of RGCs generated light-evoked ON–OFF responses, while 11% generated ON responses and 7% OFF responses. Response sensitivity analysis suggested that some RGCs obtained separated rod/cone bipolar cell inputs whereas others obtained mixed bipolar cell inputs. 25% of neurons in the RGC layer were displaced amacrine cells. Although more types may be defined by more refined classification criteria, this report is to incorporate more physiological properties into RGC classification. PMID:26731645

A longitudinal study of visual function in carriers of X-linked recessive retinitis pigmentosa.

PubMed

Grover, S; Fishman, G A; Anderson, R J; Lindeman, M

2000-02-01

This study was carried out to evaluate the progression of visual function impairment in carriers of X-linked recessive retinitis pigmentosa. We also assessed the relationship between the retinal findings at presentation and the extent of deterioration. Observational, retrospective, case series. Twenty-seven carriers of X-linked recessive retinitis pigmentosa. Each carrier was clinically categorized into one of four grades (grades 0 through 3) depending on the presence or absence of a tapetal-like retinal reflex and the extent of peripheral pigmentary degeneration. A complete ophthalmologic examination was performed and data for visual acuity, visual field area, and electroretinographic measurements were collected on the most recent visit in both eyes. These were then compared with similar data obtained on their initial visits. A comparison of visual function was carried out between the initial visit and the most recent visit on each carrier. The visual acuity was measured with Snellen's acuity charts. The visual fields to targets V-4-e and II-4-e were planimeterized and used for the analysis. The electroretinographic (ERG) measures used were light-adapted single-flash b-wave amplitudes and 30-Hz red flicker for cone function, dark-adapted maximal b-wave amplitudes, and response to a low intensity blue-flash for rod function. None of the 11 carriers with a tapetal-like reflex only (grade 1) showed any significant change in visual acuity or fields as compared with 3 of 7 (43%) carriers with diffuse peripheral pigmentary findings (grade 3) who showed significant deterioration in visual acuity in at least one eye, and 6 of 7 (86%) who showed a significant decrease in visual field area with at least one target size in at least one eye. By comparison, only 1 of 10 carriers with a grade 1 fundus finding demonstrated a significant decrease in maximal dark-adapted ERG function as compared with 5 of 6 (83%) carriers with grade 3 in response to a single-flash stimulus and with 4 of 5 (80%) carriers in response to a single-flash blue stimulus. For the single-flash photopic response, none of the 10 carriers with grade 1 showed any significant deterioration, whereas 2 of 4 (50%) with grade 3 did show such deterioration. The ERG responses for carriers with grade 2 were in between the extent of decrease in ERG amplitudes of those in carriers with grades 1 and 3. In our cohort of X-linked retinitis pigmentosa carriers, those with only a tapetal-like retinal reflex at presentation had a better prognosis to retain visual function than those with peripheral retinal pigmentation. These data are useful in counseling such carriers as to their visual prognosis.

[Radial optic neurotomy for severe central retinal vein occlusion: preliminary results].

PubMed

Le Rouic, J-F; Becquet, F; Zanlonghi, X; Péronnet, P; Pousset-Decré, C; Hermouet-Leclair, E; Ducournau, D

2003-06-01

To describe the results of radial optic neurotomy for the treatment of severe central retinal vein occlusion. Prospective noncomparative single-center study. Analysis of ten eyes of ten consecutive patients whose visual acuity was 0.1 or less. They underwent fluorescein angiography, visual field testing by automated perimetry, and macular thickness analysis by optical coherence tomography preoperatively at 3 months and at 6 months postoperatively. Mean visual acuity on an ETDRS chart increased from 30+/-12 points preoperatively to 42+/-15 points at the 3-month visit, (p=0.03), and mean macular thickness decreased from 580+/-150 micro m to 361+/-52 micro m (p=0.04). All patients had clinical improvement as determined by fundus examination and fluorescein angiography. An improvement in the central visual field was observed in all eyes. Mean visual acuity of the five patients followed-up for 6 months was 52.8+/-20 points. No visual loss was observed. None of the patients underwent laser photocoagulation or has presented with neovascularization so far. Optociliary veins developed in three eyes and a retinochoroidal anastomosis within the disk incision was observed in two eyes. These preliminary results are encouraging when compared to the reported natural progression of severe central retinal vein occlusion. A bypass of the site of occlusion is a possible mechanism for radial optic neurotomy. A randomized study should be conducted to assess the efficacy of radial optic neurotomy and determine the best candidates for surgery.

Visual motion perception predicts driving hazard perception ability.

PubMed

Lacherez, Philippe; Au, Sandra; Wood, Joanne M

2014-02-01

To examine the basis of previous findings of an association between indices of driving safety and visual motion sensitivity and to examine whether this association could be explained by low-level changes in visual function. A total of 36 visually normal participants (aged 19-80 years) completed a battery of standard vision tests including visual acuity, contrast sensitivity and automated visual fields and two tests of motion perception including sensitivity for movement of a drifting Gabor stimulus and sensitivity for displacement in a random dot kinematogram (Dmin ). Participants also completed a hazard perception test (HPT), which measured participants' response times to hazards embedded in video recordings of real-world driving, which has been shown to be linked to crash risk. Dmin for the random dot stimulus ranged from -0.88 to -0.12 log minutes of arc, and the minimum drift rate for the Gabor stimulus ranged from 0.01 to 0.35 cycles per second. Both measures of motion sensitivity significantly predicted response times on the HPT. In addition, while the relationship involving the HPT and motion sensitivity for the random dot kinematogram was partially explained by the other visual function measures, the relationship with sensitivity for detection of the drifting Gabor stimulus remained significant even after controlling for these variables. These findings suggest that motion perception plays an important role in the visual perception of driving-relevant hazards independent of other areas of visual function and should be further explored as a predictive test of driving safety. Future research should explore the causes of reduced motion perception to develop better interventions to improve road safety. © 2012 The Authors. Acta Ophthalmologica © 2012 Acta Ophthalmologica Scandinavica Foundation.

Stereo depth and the control of locomotive heading

NASA Astrophysics Data System (ADS)

Rushton, Simon K.; Harris, Julie M.

1998-04-01

Does the addition of stereoscopic depth aid steering--the perceptual control of locomotor heading--around an environment? This is a critical question when designing a tele-operation or Virtual Environment system, with implications for computational resources and visual comfort. We examined the role of stereoscopic depth in the perceptual control of heading by employing an active steering task. Three conditions were tested: stereoscopic depth; incorrect stereoscopic depth and no stereoscopic depth. Results suggest that stereoscopic depth does not improve performance in a visual control task. A further set of experiments examined the importance of a ground plane. As a ground plane is a common feature of all natural environments and provides a pictorial depth cue, it has been suggested that the visual system may be especially attuned to exploit its presence. Thus it would be predicted that a ground plane would aid judgments of locomotor heading. Results suggest that the presence of rich motion information in the lower visual field produces significant performance advantages and that provision of such information may prove a better target for system resources than stereoscopic depth. These findings have practical consequences for a system designer and also challenge previous theoretical and psychophysical perceptual research.

Sampling methods, dispersion patterns, and fixed precision sequential sampling plans for western flower thrips (Thysanoptera: Thripidae) and cotton fleahoppers (Hemiptera: Miridae) in cotton.

PubMed

Parajulee, M N; Shrestha, R B; Leser, J F

2006-04-01

A 2-yr field study was conducted to examine the effectiveness of two sampling methods (visual and plant washing techniques) for western flower thrips, Frankliniella occidentalis (Pergande), and five sampling methods (visual, beat bucket, drop cloth, sweep net, and vacuum) for cotton fleahopper, Pseudatomoscelis seriatus (Reuter), in Texas cotton, Gossypium hirsutum (L.), and to develop sequential sampling plans for each pest. The plant washing technique gave similar results to the visual method in detecting adult thrips, but the washing technique detected significantly higher number of thrips larvae compared with the visual sampling. Visual sampling detected the highest number of fleahoppers followed by beat bucket, drop cloth, vacuum, and sweep net sampling, with no significant difference in catch efficiency between vacuum and sweep net methods. However, based on fixed precision cost reliability, the sweep net sampling was the most cost-effective method followed by vacuum, beat bucket, drop cloth, and visual sampling. Taylor's Power Law analysis revealed that the field dispersion patterns of both thrips and fleahoppers were aggregated throughout the crop growing season. For thrips management decision based on visual sampling (0.25 precision), 15 plants were estimated to be the minimum sample size when the estimated population density was one thrips per plant, whereas the minimum sample size was nine plants when thrips density approached 10 thrips per plant. The minimum visual sample size for cotton fleahoppers was 16 plants when the density was one fleahopper per plant, but the sample size decreased rapidly with an increase in fleahopper density, requiring only four plants to be sampled when the density was 10 fleahoppers per plant. Sequential sampling plans were developed and validated with independent data for both thrips and cotton fleahoppers.

Predictors of visual outcome in patients operated for craniopharyngioma - a Danish national study.

PubMed

Jacobsen, Mads Forslund; Thomsen, Ann Sofia Skou; Bach-Holm, Daniella; Doroudian, Ghazaleh; Nissen, Kamilla Rothe; Fugleholm, Kåre; Poulsgaard, Lars; Siersma, Volkert; Heegaard, Steffen

2018-02-01

Craniopharyngioma often causes visual loss due to the close relation to the anterior visual pathways. This study investigates the incidence and predictors of visual outcomes in patients with craniopharyngioma. Data from sixty-six patients who underwent surgery for craniopharyngioma from 2009 to 2013 in Denmark were reviewed. Primary outcomes were visual acuity (VA) and visual field (VF) defects from pre-and postoperative visits. Secondary outcomes were optic nerve atrophy (OA) and papilledema. Fifty-eight patients were included. The VA of the patients 1-year after surgery improved by -0.16 log(MAR) (95%CI: -0.30 to -0.02; p = 0.0266). Visual field (VF) defects worsened in 17 eyes (30%), remained stable in 21 eyes (37%) and improved in 19 eyes (33%). The presence of papilledema and the absence of OA were significantly correlated with an improvement in VA postoperatively (p = 0.011 and p = 0.011, respectively). Patients undergoing surgery within a week or less after their first ophthalmological examination had a significant improvement in VA (-0.36; 95%CI: -0.62 to -0.09; p = 0.0099). Patients undergoing surgery using a subfrontal approach also showed improvement in VA (p = 0.048). Tumour recurrence had a significantly worse VA outcome (p = 0.0074). Patients show a slight improvement in VA 1-year after operation for craniopharyngioma. The presence of papilledema and early surgical intervention is associated with a significant improvement in VA. Early involvement of a dedicated ophthalmologist is recommended to secure an early detection of a visual decline and potential tumour recurrence. © 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Perceived reachability in single- and multiple-degree-of-freedom workspaces.

PubMed

Gabbard, Carl; Ammar, Diala; Lee, Sunghan

2006-11-01

In comparisons of perceived (imagined) and actual reaches, investigators consistently find a tendency to overestimate. A primary explanation for that phenomenon is that individuals reach as a "whole-body engagement" involving multiple degrees of freedom (m-df). The authors examined right-handers (N = 28) in 1-df and m-df workspaces by having them judge the reachability of targets at midline, right, and left visual fields. Response profiles were similar for total error. Both conditions reflected an overestimation bias, although the bias was significantly greater in the m-df condition. Midline responses differed (greater overestimation) from those of right and left visual fields, which were similar. Although the authors would have predicted better performance in the m-df condition, it seems plausible that if individuals think in terms of m-df, they may feel more confident in that condition and thereby exhibit greater overestimation. Furthermore, the authors speculate that the reduced bias at the side fields may be attributed to a more conservative strategy based in part on perceived reach constraints.

Laser-based volumetric flow visualization by digital color imaging of a spectrally coded volume.

PubMed

McGregor, T J; Spence, D J; Coutts, D W

2008-01-01

We present the framework for volumetric laser-based flow visualization instrumentation using a spectrally coded volume to achieve three-component three-dimensional particle velocimetry. By delivering light from a frequency doubled Nd:YAG laser with an optical fiber, we exploit stimulated Raman scattering within the fiber to generate a continuum spanning the visible spectrum from 500 to 850 nm. We shape and disperse the continuum light to illuminate a measurement volume of 20 x 10 x 4 mm(3), in which light sheets of differing spectral properties overlap to form an unambiguous color variation along the depth direction. Using a digital color camera we obtain images of particle fields in this volume. We extract the full spatial distribution of particles with depth inferred from particle color. This paper provides a proof of principle of this instrument, examining the spatial distribution of a static field and a spray field of water droplets ejected by the nozzle of an airbrush.

Vision-related fitness to drive mobility scooters: A practical driving test.

PubMed

Cordes, Christina; Heutink, Joost; Tucha, Oliver M; Brookhuis, Karel A; Brouwer, Wiebo H; Melis-Dankers, Bart J M

2017-03-06

To investigate practical fitness to drive mobility scooters, comparing visually impaired participants with healthy controls. Between-subjects design. Forty-six visually impaired (13 with very low visual acuity, 10 with low visual acuity, 11 with peripheral field defects, 12 with multiple visual impairment) and 35 normal-sighted controls. Participants completed a practical mobility scooter test-drive, which was recorded on video. Two independent occupational therapists specialized in orientation and mobility evaluated the videos systematically. Approximately 90% of the visually impaired participants passed the driving test. On average, participants with visual impairments performed worse than normal-sighted controls, but were judged sufficiently safe. In particular, difficulties were observed in participants with peripheral visual field defects and those with a combination of low visual acuity and visual field defects. People with visual impairment are, in practice, fit to drive mobility scooters; thus visual impairment on its own should not be viewed as a determinant of safety to drive mobility scooters. However, special attention should be paid to individuals with visual field defects with or without a combined low visual acuity. The use of an individual practical fitness-to-drive test is advised.

Electropysiologic evaluation of the visual pathway in patients with multiple sclerosis.

PubMed

Rodriguez-Mena, Diego; Almarcegui, Carmen; Dolz, Isabel; Herrero, Raquel; Bambo, Maria P; Fernandez, Javier; Pablo, Luis E; Garcia-Martin, Elena

2013-08-01

To evaluate the ability of visual evoked potentials and pattern electroretinograms (PERG) to detect subclinical axonal damage in patients during the early diagnostic stage of multiple sclerosis (MS). The authors also compared the ability of optical coherence tomography (OCT), PERG, and visual evoked potentials to detect axonal loss in MS patients and correlated the functional and structural properties of the retinal nerve fiber layer. Two hundred twenty-eight eyes of 114 subjects (57 MS patients and 57 age- and sex-matched healthy controls) were included. The visual pathway was evaluated based on functional and structural assessments. All patients underwent a complete ophthalmic examination that included assessment of visual acuity, ocular motility, intraocular pressure, visual field, papillary morphology, OCT, visual evoked potentials, and PERG. Visual evoked potentials (P100 latency and amplitude), PERG (N95 amplitude and N95/P50 ratio), and OCT parameters differed significantly between MS patients and healthy subjects. Moderate significant correlations were found between visual evoked potentials or PERG parameters and OCT measurements. Axonal damage in ganglion cells of the visual pathway can be detected based on structural measures provided by OCT in MS patients and by the N95 component and N95/P50 index of PERG, thus providing good correlation between function and structure.

A quantitative comparison of the hemispheric, areal, and laminar origins of sensory and motor cortical projections to the superior colliculus of the cat.

PubMed

Butler, Blake E; Chabot, Nicole; Lomber, Stephen G

2016-09-01

The superior colliculus (SC) is a midbrain structure central to orienting behaviors. The organization of descending projections from sensory cortices to the SC has garnered much attention; however, rarely have projections from multiple modalities been quantified and contrasted, allowing for meaningful conclusions within a single species. Here, we examine corticotectal projections from visual, auditory, somatosensory, motor, and limbic cortices via retrograde pathway tracers injected throughout the superficial and deep layers of the cat SC. As anticipated, the majority of cortical inputs to the SC originate in the visual cortex. In fact, each field implicated in visual orienting behavior makes a substantial projection. Conversely, only one area of the auditory orienting system, the auditory field of the anterior ectosylvian sulcus (fAES), and no area involved in somatosensory orienting, shows significant corticotectal inputs. Although small relative to visual inputs, the projection from the fAES is of particular interest, as it represents the only bilateral cortical input to the SC. This detailed, quantitative study allows for comparison across modalities in an animal that serves as a useful model for both auditory and visual perception. Moreover, the differences in patterns of corticotectal projections between modalities inform the ways in which orienting systems are modulated by cortical feedback. J. Comp. Neurol. 524:2623-2642, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Improved Visual Cognition through Stroboscopic Training

PubMed Central

Appelbaum, L. Gregory; Schroeder, Julia E.; Cain, Matthew S.; Mitroff, Stephen R.

2011-01-01

Humans have a remarkable capacity to learn and adapt, but surprisingly little research has demonstrated generalized learning in which new skills and strategies can be used flexibly across a range of tasks and contexts. In the present work we examined whether generalized learning could result from visual–motor training under stroboscopic visual conditions. Individuals were assigned to either an experimental condition that trained with stroboscopic eyewear or to a control condition that underwent identical training with non-stroboscopic eyewear. The training consisted of multiple sessions of athletic activities during which participants performed simple drills such as throwing and catching. To determine if training led to generalized benefits, we used computerized measures to assess perceptual and cognitive abilities on a variety of tasks before and after training. Computer-based assessments included measures of visual sensitivity (central and peripheral motion coherence thresholds), transient spatial attention (a useful field of view – dual task paradigm), and sustained attention (multiple-object tracking). Results revealed that stroboscopic training led to significantly greater re-test improvement in central visual field motion sensitivity and transient attention abilities. No training benefits were observed for peripheral motion sensitivity or peripheral transient attention abilities, nor were benefits seen for sustained attention during multiple-object tracking. These findings suggest that stroboscopic training can effectively improve some, but not all aspects of visual perception and attention. PMID:22059078

Right away: A late, right-lateralized category effect complements an early, left-lateralized category effect in visual search.

PubMed

Constable, Merryn D; Becker, Stefanie I

2017-10-01

According to the Sapir-Whorf hypothesis, learned semantic categories can influence early perceptual processes. A central finding in support of this view is the lateralized category effect-namely, the finding that categorically different colors (e.g., blue and green hues) can be discriminated faster than colors within the same color category (e.g., different hues of green), especially when they are presented in the right visual field. Because the right visual field projects to the left hemisphere, this finding has been popularly couched in terms of the left-lateralization of language. However, other studies have reported bilateral category effects, which has led some researchers to question the linguistic origins of the effect. Here we examined the time course of lateralized and bilateral category effects in the classical visual search paradigm by means of eyetracking and RT distribution analyses. Our results show a bilateral category effect in the manual responses, which is combined of an early, left-lateralized category effect and a later, right-lateralized category effect. The newly discovered late, right-lateralized category effect occurred only when observers had difficulty locating the target, indicating a specialization of the right hemisphere to find categorically different targets after an initial error. The finding that early and late stages of visual search show different lateralized category effects can explain a wide range of previously discrepant findings.

Visual perception and appraisal of persons with impairments: a randomised controlled field experiment using photo elicitation.

PubMed

Reinhardt, Jan Dietrich; Ballert, Carolina Saskia; Fellinghauer, Bernd; Lötscher, Alexander; Gradinger, Felix; Hilfiker, Roger; Graf, Sibylle; Stucki, Gerold

2011-01-01

Visual cues from persons with impairments may trigger stereotypical generalisations that lead to prejudice and discrimination. The main objective of this pilot study is to examine whether visual stimuli of impairment activate latent prejudice against disability and whether this connection can be counteracted with priming strategies. In a field experiment, participants were asked to rate photographs showing models with mental impairments, wheelchair users with paraplegia, and persons without any visible impairment. Participants should appraise the models with regard to several features (e.g. communicativeness, intelligence). One hundred participants rated 12 photo models yielding a total of 1183 observations. One group of participants was primed with a cover story introducing visual perception of impairment as the study's gist, while controls received neutral information. Photo models with mental impairments were rated lowest and models without visible impairment highest. In participants who did not have prior contacts with persons with impairments, priming led to a levelling of scores of models with and without impairment. Prior contacts with persons with impairments created similar effects as the priming. Unexpectedly, a pattern of converse double discrimination to the disadvantage of men with mental impairments was revealed. Signs of stereotypical processing of visual cues of impairment have been found in participants of the Swiss general population. Personal contact with persons with impairments as well as priming participants seems to reduce stereotyping.

Grating test of contrast sensitivity in patients with Minamata disease.

PubMed Central

Mukuno, K; Ishikawa, S; Okamura, R

1981-01-01

Thirty cases of Minamata disease caused by methyl mercury poisoning with the lesion mainly at the occipital cortex were selected and their spatial contrast sensitivity of vision was examined by the Arden grating chart. At the same time their visual acuity, visual field, and visual evoked cortical potential (VECP) were also investigated. In all cases the results of the Arden test indicated abnormality. Poor results were obtained at higher frequencies of the gratings. VECP elicited by grating pattern reversal stimulus was undertaken in 12 cases out of the 30. The results revealed abnormality almost equal to that shown by the Arden test. Seven out of the 12 cases showed no VECP response. The other 5, giving a response, showed abnormality: when the size of the grating became smaller at higher frequencies, the VECP paused or was not recorded, whereas at low frequencies it was recorded. This finding was in good agreement or was not recorded, whereas at low frequencies it was recorded. This finding was in good agreement with the results of the Arden test. Visual acuity and visual field tests were less sensitive in detecting abnormality. The Arden chart is a sensitive clinical tool for patients with lesions at the cerebral cortex. Furthermore, the test can be used for screening patients who may have come in contrast with organic mercury. PMID:7236573

Optical Coherence Tomography Angiography of Retinal Cavernous Hemangioma.

PubMed

Pierro, Luisa; Marchese, Alessandro; Gagliardi, Marco; Bandello, Francesco

2017-08-01

Retinal cavernous hemangioma is a rare, benign, retinal tumor characterized by angiomatous proliferation of vessels within the inner retina or the optic disc.1 Here we report a case of retinal cavernous hemangioma on the margin of the optic disc in the right eye of a 61-year-old asymptomatic female. The lesion was studied with multimodal imaging which included structural optical coherence tomography, fluorescein angiography, blue fundus auto-fluorescence, optical coherence tomography angiography (OCTA) (DRI OCT Triton; Topcon, Tokyo, Japan) and visual field examination. Blood circulation inside retinal cavernous hemangioma lesion is typically low-stagnant.2 However, OCTA demonstrated blood flow inside the lesion, illustrating its vascular circulation.3 Visual field was within the normal limits, except from a slight enlargement of the blind spot. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:684-685.]. Copyright 2017, SLACK Incorporated.

Towards Determination of Visual Requirements for Augmented Reality Displays and Virtual Environments for the Airport Tower

NASA Technical Reports Server (NTRS)

Ellis, Stephen R.

2006-01-01

The visual requirements for augmented reality or virtual environments displays that might be used in real or virtual towers are reviewed wi th respect to similar displays already used in aircraft. As an example of the type of human performance studies needed to determine the use ful specifications of augmented reality displays, an optical see-thro ugh display was used in an ATC Tower simulation. Three different binocular fields of view (14 deg, 28 deg, and 47 deg) were examined to det ermine their effect on subjects# ability to detect aircraft maneuveri ng and landing. The results suggest that binocular fields of view much greater than 47 deg are unlikely to dramatically improve search perf ormance and that partial binocular overlap is a feasible display tech nique for augmented reality Tower applications.

Contralateral eye comparison on changes in visual field following laser in situ keratomileusis vs photorefractive keratectomy for myopia: a randomized clinical trial.

PubMed

Mostafaei, A; Sedgipour, M R; Sadeghi-Bazargani, H

2009-12-01

Study purpose was to compare the changes of Visual Field (VF) during laser in situ Keratomileusis (LASIK) VS photorefractive keratectomy (PRK). This randomized, double blind, study involved 54 eyes of 27 Myopia patients who underwent LASIK or PRK procedures for contralateral eyes in each patient. Using Humphrey 30-2 SITA standard, the Mean Defect (MD) and Pattern Standard Deviation (PSD) were evaluated preoperatively and three months after surgery. At the same examination optical zone size, papillary and corneal diameters were also evaluated. There was no clinically significant difference in PSD and MD measurements between treated eyes with LASIK or PRK in any zone pre and postoperatively. VF may not be affected by corneal changes induced by LASIK or PRK three months after surgery.

Differential color brightness as a body orientation cue

NASA Technical Reports Server (NTRS)

Barbour, Christopher G.; Coss, Richard G.

1988-01-01

Ninety male and female college students reclining on their backs in the dark were disoriented when positioned on a rotating platform under a slowly rotating disk that filled their entire visual field. Half of the disk was painted with a brighter value (about 69 percent higher luminance level) of the color on the other half. The effects of red, blue, and yellow were examined. Subjects wearing frosted goggles viewed the illuminated disk for three rotations. The disk was stopped when the subjects felt that they were right side up. A significant proportion of subjects selected the disk position in which the brighter side of each of the three colors filled their upper visual field. These results suggest that color brightness as well as lighting variation could provide Space Station crew members with body orientation cues as they move around.

Finding an emotional face in a crowd: emotional and perceptual stimulus factors influence visual search efficiency.

PubMed

Lundqvist, Daniel; Bruce, Neil; Öhman, Arne

2015-01-01

In this article, we examine how emotional and perceptual stimulus factors influence visual search efficiency. In an initial task, we run a visual search task, using a large number of target/distractor emotion combinations. In two subsequent tasks, we then assess measures of perceptual (rated and computational distances) and emotional (rated valence, arousal and potency) stimulus properties. In a series of regression analyses, we then explore the degree to which target salience (the size of target/distractor dissimilarities) on these emotional and perceptual measures predict the outcome on search efficiency measures (response times and accuracy) from the visual search task. The results show that both emotional and perceptual stimulus salience contribute to visual search efficiency. The results show that among the emotional measures, salience on arousal measures was more influential than valence salience. The importance of the arousal factor may be a contributing factor to contradictory history of results within this field.

Technical Note: MR-visualization of interventional devices using transient field alterations and balanced steady-state free precession imaging.

PubMed

Eibofner, Frank; Martirosian, Petros; Würslin, Christian; Graf, Hansjörg; Syha, Roland; Clasen, Stephan

2015-11-01

In interventional magnetic resonance imaging, instruments can be equipped with conducting wires for visualization by current application. The potential of sequence triggered application of transient direct currents in balanced steady-state free precession (bSSFP) imaging is demonstrated. A conductor and a modified catheter were examined in water phantoms and in an ex vivo porcine liver. The current was switched by a trigger pulse in the bSSFP sequence in an interval between radiofrequency pulse and signal acquisition. Magnitude and phase images were recorded. Regions with transient field alterations were evaluated by a postprocessing algorithm. A phase mask was computed and overlaid with the magnitude image. Transient field alterations caused continuous phase shifts, which were separated by the postprocessing algorithm from phase jumps due to persistent field alterations. The overlaid images revealed the position of the conductor. The modified catheter generated visible phase offset in all orientations toward the static magnetic field and could be unambiguously localized in the ex vivo porcine liver. The application of a sequence triggered, direct current in combination with phase imaging allows conspicuous localization of interventional devices with a bSSFP sequence.

Visual Disturbance as the first Symptom of Chronic Myeloid Leukemia

PubMed Central

Huang, Philemon K.; Sanjay, Srinivasan

2011-01-01

Chronic myeloid leukemia (CML) is a well-studied entity and advances made in diagnosis and treatment have improved the disease outcome. Patients with ophthalmic manifestation of CML have been reported to have lower 5-year survival rates. Hence, recognizing the early fundus changes may improve outcome by allowing earlier diagnosis and treatment. We report a case of a previously healthy 30-year-old Myanmarese male, who presented with a minor visual disturbance, complaining of seeing a ‘black dot’ in his left visual field for the past 1 week. Fundoscopic examination revealed bilateral retinal blot hemorrhages, white-centered hemorrhage, and preretinal hemorrhage over the left fovea. The full blood count and peripheral blood film were abnormal, and bone marrow biopsy confirmed the diagnosis of CML. Cytoreduction therapy was promptly commenced and his symptoms resolved, with improvement in visual acuity. No complications were recorded at 1-year follow-up. PMID:22224030

Visual Disturbance as the first Symptom of Chronic Myeloid Leukemia.

PubMed

Huang, Philemon K; Sanjay, Srinivasan

2011-10-01

Chronic myeloid leukemia (CML) is a well-studied entity and advances made in diagnosis and treatment have improved the disease outcome. Patients with ophthalmic manifestation of CML have been reported to have lower 5-year survival rates. Hence, recognizing the early fundus changes may improve outcome by allowing earlier diagnosis and treatment. We report a case of a previously healthy 30-year-old Myanmarese male, who presented with a minor visual disturbance, complaining of seeing a 'black dot' in his left visual field for the past 1 week. Fundoscopic examination revealed bilateral retinal blot hemorrhages, white-centered hemorrhage, and preretinal hemorrhage over the left fovea. The full blood count and peripheral blood film were abnormal, and bone marrow biopsy confirmed the diagnosis of CML. Cytoreduction therapy was promptly commenced and his symptoms resolved, with improvement in visual acuity. No complications were recorded at 1-year follow-up.

Visual motion integration for perception and pursuit

NASA Technical Reports Server (NTRS)

Stone, L. S.; Beutter, B. R.; Lorenceau, J.

2000-01-01

To examine the relationship between visual motion processing for perception and pursuit, we measured the pursuit eye-movement and perceptual responses to the same complex-motion stimuli. We show that humans can both perceive and pursue the motion of line-figure objects, even when partial occlusion makes the resulting image motion vastly different from the underlying object motion. Our results show that both perception and pursuit can perform largely accurate motion integration, i.e. the selective combination of local motion signals across the visual field to derive global object motion. Furthermore, because we manipulated perceived motion while keeping image motion identical, the observed parallel changes in perception and pursuit show that the motion signals driving steady-state pursuit and perception are linked. These findings disprove current pursuit models whose control strategy is to minimize retinal image motion, and suggest a new framework for the interplay between visual cortex and cerebellum in visuomotor control.

Feasibility and safety of a novel magnetic-assisted capsule endoscope system in a preliminary examination for upper gastrointestinal tract.

PubMed

Lien, Gi-Shih; Wu, Ming-Shun; Chen, Chun-Nan; Liu, Chih-Wen; Suk, Fat-Moon

2018-04-01

Current capsule endoscopy procedures are ineffective for upper gastrointestinal (GI) tract examination because they do not allow for operator-controlled navigation of the capsule. External controllability of a capsule endoscope with an applied magnetic field is a possible solution to this problem. We developed a novel magnetic-assisted capsule endoscope (MACE) system to visualize the entire upper GI tract. The present study evaluated the safety and feasibility of the MACE system for the examination of the upper GI tract, including the esophagus, stomach, and duodenum. The present open clinical study enrolled ten healthy volunteers. All participants swallowed a MACE, and an external magnetic field navigator was used for magnetic capsule manipulation in the upper GI tract. We assessed the maneuverability of the magnetic capsule and completeness of the MACE examination as well as the safety and tolerability of the procedure. The present study enrolled ten healthy volunteers with a mean age and body mass index of 47.7 years and 25.6 kg/m 2 , respectively. One volunteer withdrew because of difficulty in swallowing the capsule. In total, nine volunteers underwent the MACE examination. The average examination time was 27.1 min. The maneuverability of the capsule was assessed as good and fair in 55.6 and 44.4% of the participants, respectively. The overall completeness of the examination in the esophagus, stomach, and duodenum was 100, 85.2, and 86.1%, respectively. No severe adverse events occurred during this study. All participants exhibited satisfactory tolerance of the MACE examination. The MACE system has satisfactory maneuverability and visualization completeness with excellent acceptance and tolerance.

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

Comparison of visual field training for hemianopia with active versus sham transcranial direct cortical stimulation.

PubMed

Plow, Ela B; Obretenova, Souzana N; Fregni, Felipe; Pascual-Leone, Alvaro; Merabet, Lotfi B

2012-01-01

Vision Restoration Therapy (VRT) aims to improve visual field function by systematically training regions of residual vision associated with the activity of suboptimal firing neurons within the occipital cortex. Transcranial direct current stimulation (tDCS) has been shown to modulate cortical excitability. Assess the possible efficacy of tDCS combined with VRT. The authors conducted a randomized, double-blind, demonstration-of-concept pilot study where participants were assigned to either VRT and tDCS or VRT and sham. The anode was placed over the occipital pole to target both affected and unaffected lobes. One hour training sessions were carried out 3 times per week for 3 months in a laboratory. Outcome measures included objective and subjective changes in visual field, recording of visual fixation performance, and vision-related activities of daily living (ADLs) and quality of life (QOL). Although 12 participants were enrolled, only 8 could be analyzed. The VRT and tDCS group demonstrated significantly greater expansion in visual field and improvement on ADLs compared with the VRT and sham group. Contrary to expectations, subjective perception of visual field change was greater in the VRT and sham group. QOL did not change for either group. The observed changes in visual field were unrelated to compensatory eye movements, as shown with fixation monitoring. The combination of occipital cortical tDCS with visual field rehabilitation appears to enhance visual functional outcomes compared with visual rehabilitation alone. TDCS may enhance inherent mechanisms of plasticity associated with training.

An optimized content-aware image retargeting method: toward expanding the perceived visual field of the high-density retinal prosthesis recipients

NASA Astrophysics Data System (ADS)

Li, Heng; Zeng, Yajie; Lu, Zhuofan; Cao, Xiaofei; Su, Xiaofan; Sui, Xiaohong; Wang, Jing; Chai, Xinyu

2018-04-01

Objective. Retinal prosthesis devices have shown great value in restoring some sight for individuals with profoundly impaired vision, but the visual acuity and visual field provided by prostheses greatly limit recipients’ visual experience. In this paper, we employ computer vision approaches to seek to expand the perceptible visual field in patients implanted potentially with a high-density retinal prosthesis while maintaining visual acuity as much as possible. Approach. We propose an optimized content-aware image retargeting method, by introducing salient object detection based on color and intensity-difference contrast, aiming to remap important information of a scene into a small visual field and preserve their original scale as much as possible. It may improve prosthetic recipients’ perceived visual field and aid in performing some visual tasks (e.g. object detection and object recognition). To verify our method, psychophysical experiments, detecting object number and recognizing objects, are conducted under simulated prosthetic vision. As control, we use three other image retargeting techniques, including Cropping, Scaling, and seam-assisted shrinkability. Main results. Results show that our method outperforms in preserving more key features and has significantly higher recognition accuracy in comparison with other three image retargeting methods under the condition of small visual field and low-resolution. Significance. The proposed method is beneficial to expand the perceived visual field of prosthesis recipients and improve their object detection and recognition performance. It suggests that our method may provide an effective option for image processing module in future high-density retinal implants.

[Glaucoma and optic nerve drusen: Limitations of optic nerve head OCT].

PubMed

Poli, M; Colange, J; Goutagny, B; Sellem, E

2017-09-01

Optic nerve head drusen are congenital calcium deposits located in the prelaminar section of the optic nerve head. Their association with visual field defects has been classically described, but the diagnosis of glaucoma is not easy in these cases of altered optic nerve head anatomy. We describe the case of a 67-year-old man with optic nerve head drusen complicated by glaucoma, which was confirmed by visual field and OCT examination of the peripapillary retinal nerve fiber layer (RNFL), but the measurement of the minimum distance between the Bruch membrane opening and the internal limiting membrane (minimum rim width, BMO-MRW) by OCT was normal. OCT of the BMO-MRW is a new diagnostic tool for glaucoma. Superficial optic nerve head drusen, which are found between the internal limiting membrane and the Bruch's membrane opening, overestimate the value of this parameter. BMO-MRW measurement is not adapted to cases of optic nerve head drusen and can cause false-negative results for this parameter, and the diagnosis of glaucoma in this case should be based on other parameters such as the presence of a fascicular defect in the retinal nerve fibers, RNFL or macular ganglion cell complex thinning, as well as visual field data. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Neural correlates of the eye dominance effect in human face perception: the left-visual-field superiority for faces revisited.

PubMed

Jung, Wookyoung; Kang, Joong-Gu; Jeon, Hyeonjin; Shim, Miseon; Sun Kim, Ji; Leem, Hyun-Sung; Lee, Seung-Hwan

2017-08-01

Faces are processed best when they are presented in the left visual field (LVF), a phenomenon known as LVF superiority. Although one eye contributes more when perceiving faces, it is unclear how the dominant eye (DE), the eye we unconsciously use when performing a monocular task, affects face processing. Here, we examined the influence of the DE on the LVF superiority for faces using event-related potentials. Twenty left-eye-dominant (LDE group) and 23 right-eye-dominant (RDE group) participants performed the experiments. Face stimuli were randomly presented in the LVF or right visual field (RVF). The RDE group exhibited significantly larger N170 amplitudes compared with the LDE group. Faces presented in the LVF elicited N170 amplitudes that were significantly more negative in the RDE group than they were in the LDE group, whereas the amplitudes elicited by stimuli presented in the RVF were equivalent between the groups. The LVF superiority was maintained in the RDE group but not in the LDE group. Our results provide the first neural evidence of the DE's effects on the LVF superiority for faces. We propose that the RDE may be more biologically specialized for face processing. © The Author (2017). Published by Oxford University Press.

Neural correlates of the eye dominance effect in human face perception: the left-visual-field superiority for faces revisited

PubMed Central

Jung, Wookyoung; Kang, Joong-Gu; Jeon, Hyeonjin; Shim, Miseon; Sun Kim, Ji; Leem, Hyun-Sung

2017-01-01

Abstract Faces are processed best when they are presented in the left visual field (LVF), a phenomenon known as LVF superiority. Although one eye contributes more when perceiving faces, it is unclear how the dominant eye (DE), the eye we unconsciously use when performing a monocular task, affects face processing. Here, we examined the influence of the DE on the LVF superiority for faces using event-related potentials. Twenty left-eye-dominant (LDE group) and 23 right-eye-dominant (RDE group) participants performed the experiments. Face stimuli were randomly presented in the LVF or right visual field (RVF). The RDE group exhibited significantly larger N170 amplitudes compared with the LDE group. Faces presented in the LVF elicited N170 amplitudes that were significantly more negative in the RDE group than they were in the LDE group, whereas the amplitudes elicited by stimuli presented in the RVF were equivalent between the groups. The LVF superiority was maintained in the RDE group but not in the LDE group. Our results provide the first neural evidence of the DE’s effects on the LVF superiority for faces. We propose that the RDE may be more biologically specialized for face processing. PMID:28379584

Foveal and peripheral fields of vision influences perceptual skill in anticipating opponents' attacking position in volleyball.

PubMed

Schorer, Jörg; Rienhoff, Rebecca; Fischer, Lennart; Baker, Joseph

2013-09-01

The importance of perceptual-cognitive expertise in sport has been repeatedly demonstrated. In this study we examined the role of different sources of visual information (i.e., foveal versus peripheral) in anticipating volleyball attack positions. Expert (n = 11), advanced (n = 13) and novice (n = 16) players completed an anticipation task that involved predicting the location of volleyball attacks. Video clips of volleyball attacks (n = 72) were spatially and temporally occluded to provide varying amounts of information to the participant. In addition, participants viewed the attacks under three visual conditions: full vision, foveal vision only, and peripheral vision only. Analysis of variance revealed significant between group differences in prediction accuracy with higher skilled players performing better than lower skilled players. Additionally, we found significant differences between temporal and spatial occlusion conditions. Both of those factors interacted separately, but not combined with expertise. Importantly, for experts the sum of both fields of vision was superior to either source in isolation. Our results suggest different sources of visual information work collectively to facilitate expert anticipation in time-constrained sports and reinforce the complexity of expert perception.

Evaluation of visual field parameters in patients with chronic obstructive pulmonary disease.

PubMed

Demir, Helin Deniz; Inönü, Handan; Kurt, Semiha; Doruk, Sibel; Aydın, Erdinc; Etikan, Ilker

2012-08-01

To evaluate the effects of chronic obstructive pulmonary disease (COPD) on retina and optic nerve. Thirty-eight patients with COPD and 29 healthy controls, totally 67 subjects, were included in the study. Visual evoked potentials (VEP) and visual field assessment (both standard achromatic perimetry (SAP) and short-wavelength automated perimetry (SWAP)) were performed on each subject after ophthalmological, neurological and pulmonary examinations. Mean deviation (MD), pattern standard deviation (PSD) and corrected pattern standard deviation (CPSD) were significantly different between patient and control groups as for both SAP and SWAP measurements (p = 0.001, 0.019, 0.009 and p = 0.004,0.019, 0.031, respectively). Short-term fluctuation (SF) was not statistically different between the study and the control groups (p = 0.874 and 0.694, respectively). VEP P100 latencies were significantly different between patients with COPD and the controls (p = 0.019). Chronic obstructive pulmonary disease is a systemic disease, and hypoxia in COPD seems to affect the retina and the optic nerve. © 2012 The Authors. Acta Ophthalmologica © 2012 Acta Ophthalmologica Scandinavica Foundation.

Effect of ocular transverse chromatic aberration on detection acuity for peripheral vision.

PubMed

Cheney, Frank; Thibos, Larry; Bradley, Arthur

2015-01-01

We examined the effect of transverse chromatic aberration (TCA) on detection acuity for white-light interference fringes seen in Maxwellian view at various orientations and locations in the visual field. A circular patch (3.5° diameter, 3.2 log Trolands) of nominally high-contrast fringes was produced on the retina by a commercial instrument (the Lotmar Visometer, Haag Streit) mounted on a gimbal for controlled positioning of the stimulus in the visual field from 0° to 35° eccentricity. Detection acuity for white light fringes for all meridians and eccentricities ≥15° was maximum when fringes were oriented parallel to the visual meridian line. This meridional effect disappeared when a narrow-band filter was used to eliminate TCA. The meridional effect also disappeared when the interferometric stimulator was displaced laterally to align the instrument with the eye's local achromatic axis. Modelling confirmed that TCA is the major factor responsible for white-light meridional bias, with minor contribution arising from higher-order monochromatic aberrations and neural factors. © 2014 The Authors Ophthalmic & Physiological Optics © 2014 The College of Optometrists.

Extent of resection in temporal lobectomy for epilepsy. II. Memory changes and neurologic complications.

PubMed

Katz, A; Awad, I A; Kong, A K; Chelune, G J; Naugle, R I; Wyllie, E; Beauchamp, G; Lüders, H

1989-01-01

We present correlations of extent of temporal lobectomy for intractable epilepsy with postoperative memory changes (20 cases) and abnormalities of visual field and neurologic examination (45 cases). Postoperative magnetic resonance imaging (MRI) in the coronal plane was used to quantify anteroposterior extent of resection of various quadrants of the temporal lobe, using a 20-compartment model of that structure. The Wechsler Memory Scale-Revised (WMS-R) was administered preoperatively and postoperatively. Postoperative decrease in percentage of retention of verbal material correlated with extent of medial resection of left temporal lobe, whereas decrease in percentage of retention of visual material correlated with extent of medial resection of right temporal lobe. These correlations approached but did not reach statistical significance. Extent of resection correlated significantly with the presence of visual field defect on perimetry testing but not with severity, denseness, or congruity of the defect. There was no correlation between postoperative dysphasia and extent of resection in any quadrant. Assessment of extent of resection after temporal lobectomy allows a rational interpretation of postoperative neurologic deficits in light of functional anatomy of the temporal lobe.

Optimal viewing position in vertically and horizontally presented Japanese words.

PubMed

Kajii, N; Osaka, N

2000-11-01

In the present study, the optimal viewing position (OVP) phenomenon in Japanese Hiragana was investigated, with special reference to a comparison between the vertical and the horizontal meridians in the visual field. In the first experiment, word recognition scores were determined while the eyes were fixating predetermined locations in vertically and horizontally displayed words. Similar to what has been reported for Roman scripts, OVP curves, which were asymmetric with respect to the beginning of words, were observed in both conditions. However, this asymmetry was less pronounced for vertically than for horizontally displayed words. In the second experiment, the visibility of individual characters within strings was examined for the vertical and horizontal meridians. As for Roman characters, letter identification scores were better in the right than in the left visual field. However, identification scores did not differ between the upper and the lower sides of fixation along the vertical meridian. The results showed that the model proposed by Nazir, O'Regan, and Jacobs (1991) cannot entirely account for the OVP phenomenon. A model in which visual and lexical factors are combined is proposed instead.

Effects of visual attention on chromatic and achromatic detection sensitivities.

PubMed

Uchikawa, Keiji; Sato, Masayuki; Kuwamura, Keiko

2014-05-01

Visual attention has a significant effect on various visual functions, such as response time, detection and discrimination sensitivity, and color appearance. It has been suggested that visual attention may affect visual functions in the early visual pathways. In this study we examined selective effects of visual attention on sensitivities of the chromatic and achromatic pathways to clarify whether visual attention modifies responses in the early visual system. We used a dual task paradigm in which the observer detected a peripheral test stimulus presented at 4 deg eccentricities while the observer concurrently carried out an attention task in the central visual field. In experiment 1, it was confirmed that peripheral spectral sensitivities were reduced more for short and long wavelengths than for middle wavelengths with the central attention task so that the spectral sensitivity function changed its shape by visual attention. This indicated that visual attention affected the chromatic response more strongly than the achromatic response. In experiment 2 it was obtained that the detection thresholds increased in greater degrees in the red-green and yellow-blue chromatic directions than in the white-black achromatic direction in the dual task condition. In experiment 3 we showed that the peripheral threshold elevations depended on the combination of color-directions of the central and peripheral stimuli. Since the chromatic and achromatic responses were separately processed in the early visual pathways, the present results provided additional evidence that visual attention affects responses in the early visual pathways.

Eccentric correction for off-axis vision in central visual field loss.

PubMed

Gustafsson, Jörgen; Unsbo, Peter

2003-07-01

Subjects with absolute central visual field loss use eccentric fixation and magnifying devices to utilize their residual vision. This preliminary study investigated the importance of an accurate eccentric correction of off-axis refractive errors to optimize the residual visual function for these subjects. Photorefraction using the PowerRefractor instrument was used to evaluate the ametropia in eccentric fixation angles. Methods were adapted for measuring visual acuity outside the macula using filtered optotypes from high-pass resolution perimetry. Optical corrections were implemented, and the visual function of subjects with central visual field loss was measured with and without eccentric correction. Of the seven cases reported, five experienced an improvement in visual function in their preferred retinal locus with eccentric refraction. The main result was that optical correction for better image quality on the peripheral retina is important for the vision of subjects with central visual field loss, objectively as well as subjectively.

Retinitis pigmentosa.

PubMed

Hamel, Christian

2006-10-11

Retinitis pigmentosa (RP) is an inherited retinal dystrophy caused by the loss of photoreceptors and characterized by retinal pigment deposits visible on fundus examination. Prevalence of non syndromic RP is approximately 1/4,000. The most common form of RP is a rod-cone dystrophy, in which the first symptom is night blindness, followed by the progressive loss in the peripheral visual field in daylight, and eventually leading to blindness after several decades. Some extreme cases may have a rapid evolution over two decades or a slow progression that never leads to blindness. In some cases, the clinical presentation is a cone-rod dystrophy, in which the decrease in visual acuity predominates over the visual field loss. RP is usually non syndromic but there are also many syndromic forms, the most frequent being Usher syndrome. To date, 45 causative genes/loci have been identified in non syndromic RP (for the autosomal dominant, autosomal recessive, X-linked, and digenic forms). Clinical diagnosis is based on the presence of night blindness and peripheral visual field defects, lesions in the fundus, hypovolted electroretinogram traces, and progressive worsening of these signs. Molecular diagnosis can be made for some genes, but is not usually performed due to the tremendous genetic heterogeneity of the disease. Genetic counseling is always advised. Currently, there is no therapy that stops the evolution of the disease or restores the vision, so the visual prognosis is poor. The therapeutic approach is restricted to slowing down the degenerative process by sunlight protection and vitaminotherapy, treating the complications (cataract and macular edema), and helping patients to cope with the social and psychological impact of blindness. However, new therapeutic strategies are emerging from intensive research (gene therapy, neuroprotection, retinal prosthesis).

Retinitis pigmentosa

PubMed Central

Hamel, Christian

2006-01-01

Retinitis pigmentosa (RP) is an inherited retinal dystrophy caused by the loss of photoreceptors and characterized by retinal pigment deposits visible on fundus examination. Prevalence of non syndromic RP is approximately 1/4,000. The most common form of RP is a rod-cone dystrophy, in which the first symptom is night blindness, followed by the progressive loss in the peripheral visual field in daylight, and eventually leading to blindness after several decades. Some extreme cases may have a rapid evolution over two decades or a slow progression that never leads to blindness. In some cases, the clinical presentation is a cone-rod dystrophy, in which the decrease in visual acuity predominates over the visual field loss. RP is usually non syndromic but there are also many syndromic forms, the most frequent being Usher syndrome. To date, 45 causative genes/loci have been identified in non syndromic RP (for the autosomal dominant, autosomal recessive, X-linked, and digenic forms). Clinical diagnosis is based on the presence of night blindness and peripheral visual field defects, lesions in the fundus, hypovolted electroretinogram traces, and progressive worsening of these signs. Molecular diagnosis can be made for some genes, but is not usually performed due to the tremendous genetic heterogeneity of the disease. Genetic counseling is always advised. Currently, there is no therapy that stops the evolution of the disease or restores the vision, so the visual prognosis is poor. The therapeutic approach is restricted to slowing down the degenerative process by sunlight protection and vitaminotherapy, treating the complications (cataract and macular edema), and helping patients to cope with the social and psychological impact of blindness. However, new therapeutic strategies are emerging from intensive research (gene therapy, neuroprotection, retinal prosthesis). PMID:17032466

High-resolution imaging of retinal nerve fiber bundles in glaucoma using adaptive optics scanning laser ophthalmoscopy.

PubMed

Takayama, Kohei; Ooto, Sotaro; Hangai, Masanori; Ueda-Arakawa, Naoko; Yoshida, Sachiko; Akagi, Tadamichi; Ikeda, Hanako Ohashi; Nonaka, Atsushi; Hanebuchi, Masaaki; Inoue, Takashi; Yoshimura, Nagahisa

2013-05-01

To detect pathologic changes in retinal nerve fiber bundles in glaucomatous eyes seen on images obtained by adaptive optics (AO) scanning laser ophthalmoscopy (AO SLO). Prospective cross-sectional study. Twenty-eight eyes of 28 patients with open-angle glaucoma and 21 normal eyes of 21 volunteer subjects underwent a full ophthalmologic examination, visual field testing using a Humphrey Field Analyzer, fundus photography, red-free SLO imaging, spectral-domain optical coherence tomography, and imaging with an original prototype AO SLO system. The AO SLO images showed many hyperreflective bundles suggesting nerve fiber bundles. In glaucomatous eyes, the nerve fiber bundles were narrower than in normal eyes, and the nerve fiber layer thickness was correlated with the nerve fiber bundle widths on AO SLO (P < .001). In the nerve fiber layer defect area on fundus photography, the nerve fiber bundles on AO SLO were narrower compared with those in normal eyes (P < .001). At 60 degrees on the inferior temporal side of the optic disc, the nerve fiber bundle width was significantly lower, even in areas without nerve fiber layer defect, in eyes with glaucomatous eyes compared with normal eyes (P = .026). The mean deviations of each cluster in visual field testing were correlated with the corresponding nerve fiber bundle widths (P = .017). AO SLO images showed reduced nerve fiber bundle widths both in clinically normal and abnormal areas of glaucomatous eyes, and these abnormalities were associated with visual field defects, suggesting that AO SLO may be useful for detecting early nerve fiber bundle abnormalities associated with loss of visual function. Copyright © 2013 Elsevier Inc. All rights reserved.

Left and Right Memory Revisited: Electrophysiological Investigations of Hemispheric Asymmetries at Retrieval

ERIC Educational Resources Information Center

Evans, Karen M.; Federmeier, Kara D.

2009-01-01

Hemispheric differences in the use of memory retrieval cues were examined in a continuous recognition design, using visual half-field presentation to bias the processing of test words. A speeded recognition task revealed general accuracy and response time advantages for items whose test presentation was biased to the left hemisphere. A second…

Cerebral Asymmetries in the Processing of Tachistoscopic Information as a Function of Sex, Handedness, and Instructions.

ERIC Educational Resources Information Center

Iaccino, James F.; Sowa, Stephen J.

A study examined the effects of sex, handedness, and instructions in the processing of verbal and spatial information presented tachistoscopically. Subjects, 48 volunteers from Illinois Benedictine College, were evenly distributed in terms of sex and handedness, and were further divided into two subgroups based on whether visual field attendance…

Lexical Competition is Enhanced in the Left Hemisphere: Evidence from Different Types of Orthographic Neighbors

ERIC Educational Resources Information Center

Perea, Manuel; Acha, Joana; Fraga, Isabel

2008-01-01

Two divided visual field lexical decision experiments were conducted to examine the role of the cerebral hemispheres in orthographic neighborhood effects. In Experiment 1, we employed two types of words: words with many substitution neighbors (high-"N") and words with few substitution neighbors (low-"N"). Results showed a facilitative effect of…

Research Review: Implications of Metaphorical Thinking for Teaching Artists

ERIC Educational Resources Information Center

Baxter, Kristin

2009-01-01

This review presents a rare blend of a scholar's insight into research and a teaching artist's insight into what the implications of that research can and should be for all teaching artists, regardless of their field. The author thoroughly examines Daniel Serig's 2006 research "A Conceptual Structure of Visual Metaphor" (Studies in Art Education,…

Hemispheric Asymmetries in Processing L1 and L2 Idioms: Effects of Salience and Context

ERIC Educational Resources Information Center

Cieslicka, Anna B.; Heredia, Roberto R.

2011-01-01

This study investigates the contribution of the left and right hemispheres to the comprehension of bilingual figurative language and the joint effects of salience and context on the differential cerebral involvement in idiom processing. The divided visual field and the lexical decision priming paradigms were employed to examine the activation of…

Cognitive Style Factors and Learning from Micro-Computer Based and Programmed Instructional Materials: A Preliminary Analysis.

ERIC Educational Resources Information Center

Canelos, James; And Others

This study examined the effects of two cognitive styles--field dependents-independents and reflectivity-impulsivity--on learning from microcomputer-based instruction. In the first of three experimental designs, a programmed instruction text on the human heart was used which contained both visual and verbal information in an instructional display,…

Hemispheric Processing of Idioms and Irony in Adults with and without Pervasive Developmental Disorder

ERIC Educational Resources Information Center

Saban-Bezalel, Ronit; Mashal, Nira

2015-01-01

Previous studies on individuals with pervasive developmental disorders (PDD) have pointed to difficulties in comprehension of figurative language. Using the divided visual field paradigm, the present study examined hemispheric processing of idioms and irony in 23 adults with PDD and in 24 typically developing (TD) adults. The results show that…

Gender Differences in Solving Mathematics Problems among Two-Year College Students in a Developmental Algebra Class and Related Factors.

ERIC Educational Resources Information Center

Schonberger, Ann K.

A study was conducted at the University of Maine at Orono (UMO) to examine gender differences with respect to mathematical problem-solving ability, visual spatial ability, abstract reasoning ability, field independence/dependence, independent learning style, and developmental problem-solving ability (i.e., formal reasoning ability). Subjects…

Rehabilitation of Reading and Visual Exploration in Visual Field Disorders: Transfer or Specificity?

ERIC Educational Resources Information Center

Schuett, Susanne; Heywood, Charles A.; Kentridge, Robert W.; Dauner, Ruth; Zihl, Josef

2012-01-01

Reading and visual exploration impairments in unilateral homonymous visual field disorders are frequent and disabling consequences of acquired brain injury. Compensatory therapies have been developed, which allow patients to regain sufficient reading and visual exploration performance through systematic oculomotor training. However, it is still…

Learning to Read Vertical Text in Peripheral Vision

PubMed Central

Subramanian, Ahalya; Legge, Gordon E.; Wagoner, Gunther Harrison; Yu, Deyue

2014-01-01

Purpose English–language text is almost always written horizontally. Text can be formatted to run vertically, but this is seldom used. Several studies have found that horizontal text can be read faster than vertical text in the central visual field. No studies have investigated the peripheral visual field. Studies have also concluded that training can improve reading speed in the peripheral visual field for horizontal text. We aimed to establish whether the horizontal vertical differences are maintained and if training can improve vertical reading in the peripheral visual field. Methods Eight normally sighted young adults participated in the first study. Rapid Serial Visual Presentation (RSVP) reading speed was measured for horizontal and vertical text in the central visual field and at 10° eccentricity in the upper or lower (horizontal text), and right or left (vertical text) visual fields. Twenty-one normally sighted young adults split equally between 2 training and 1 control group participated in the second study. Training consisted of RSVP reading either using vertical text in the left visual field or horizontal text in the inferior visual field. Subjects trained daily over 4 days. Pre and post horizontal and vertical RSVP reading speeds were carried out for all groups. For the training groups these measurements were repeated 1 week and 1 month post training. Results Prior to training, RSVP reading speeds were faster for horizontal text in the central and peripheral visual fields when compared to vertical text. Training vertical reading improved vertical reading speeds by an average factor of 2.8. There was partial transfer of training to the opposite (right) hemifield. The training effects were retained for up to a month. Conclusions RSVP training can improve RSVP vertical text reading in peripheral vision. These findings may have implications for patients with macular degeneration or hemianopic field loss. PMID:25062130

Proceedings of the Symposium of Medical (Ophthalmic) Surveillance of Personnel Potentially Exposed to Laser Radiation Held on 8-9 September 1982.

DTIC Science & Technology

1982-01-01

Hardy, Rand, and Rittler (HRR) pseudoisochromatic plates and the Farnsworth D15 color panel; these tests were normal. However, in an anomaloscopic...measures (e.g., slit-lamp and ophthalmoscopic examinations ) rather than quantitative visual function tests (e.g., Snellen acuity, contrast transfer, color...arose from eye examination programs ii ..’ 1C- following field tests at Fort Hunter Liggett, California and at Yuma Proving Ground, Arizona. Most, if

Modulation of Neuronal Responses by Exogenous Attention in Macaque Primary Visual Cortex.

PubMed

Wang, Feng; Chen, Minggui; Yan, Yin; Zhaoping, Li; Li, Wu

2015-09-30

Visual perception is influenced by attention deployed voluntarily or triggered involuntarily by salient stimuli. Modulation of visual cortical processing by voluntary or endogenous attention has been extensively studied, but much less is known about how involuntary or exogenous attention affects responses of visual cortical neurons. Using implanted microelectrode arrays, we examined the effects of exogenous attention on neuronal responses in the primary visual cortex (V1) of awake monkeys. A bright annular cue was flashed either around the receptive fields of recorded neurons or in the opposite visual field to capture attention. A subsequent grating stimulus probed the cue-induced effects. In a fixation task, when the cue-to-probe stimulus onset asynchrony (SOA) was <240 ms, the cue induced a transient increase of neuronal responses to the probe at the cued location during 40-100 ms after the onset of neuronal responses to the probe. This facilitation diminished and disappeared after repeated presentations of the same cue but recurred for a new cue of a different color. In another task to detect the probe, relative shortening of monkey's reaction times for the validly cued probe depended on the SOA in a way similar to the cue-induced V1 facilitation, and the behavioral and physiological cueing effects remained after repeated practice. Flashing two cues simultaneously in the two opposite visual fields weakened or diminished both the physiological and behavioral cueing effects. Our findings indicate that exogenous attention significantly modulates V1 responses and that the modulation strength depends on both novelty and task relevance of the stimulus. Significance statement: Visual attention can be involuntarily captured by a sudden appearance of a conspicuous object, allowing rapid reactions to unexpected events of significance. The current study discovered a correlate of this effect in monkey primary visual cortex. An abrupt, salient, flash enhanced neuronal responses, and shortened the animal's reaction time, to a subsequent visual probe stimulus at the same location. However, the enhancement of the neural responses diminished after repeated exposures to this flash if the animal was not required to react to the probe. Moreover, a second, simultaneous, flash at another location weakened the neuronal and behavioral effects of the first one. These findings revealed, beyond the observations reported so far, the effects of exogenous attention in the brain. Copyright © 2015 the authors 0270-6474/15/3513419-11$15.00/0.

Visual function, driving safety, and the elderly.

PubMed

Keltner, J L; Johnson, C A

1987-09-01

The authors have conducted a survey of the Departments of Motor Vehicles in all 50 states, the District of Columbia, and Puerto Rico requesting information about the visual standards, accidents, and conviction rates for different age groups. In addition, we have reviewed the literature on visual function and traffic safety. Elderly drivers have a greater number of vision problems that affect visual acuity and/or peripheral visual fields. Although the elderly are responsible for a small percentage of the total number of traffic accidents, the types of accidents they are involved in (e.g., failure to yield the right-of-way, intersection collisions, left turns onto crossing streets) may be related to peripheral and central visual field problems. Because age-related changes in performance occur at different rates for various individuals, licensing of the elderly driver should be based on functional abilities rather than age. Based on information currently available, we can make the following recommendations: (1) periodic evaluations of visual acuity and visual fields should be performed every 1 to 2 years in the population over age 65; (2) drivers of any age with multiple accidents or moving violations should have visual acuity and visual fields evaluated; and (3) a system should be developed for physicians to report patients with potentially unsafe visual function. The authors believe that these recommendations may help to reduce the number of traffic accidents that result from peripheral visual field deficits.

Sudden visual loss after cardiac resynchronization therapy device implantation.

PubMed

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

2017-03-10

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

Is the size of the useful field of view affected by postural demands associated with standing and stepping?

PubMed

Reed-Jones, James G; Reed-Jones, Rebecca J; Hollands, Mark A

2014-04-30

The useful field of view (UFOV) is the visual area from which information is obtained at a brief glance. While studies have examined the effects of increased cognitive load on the visual field, no one has specifically looked at the effects of postural control or locomotor activity on the UFOV. The current study aimed to examine the effects of postural demand and locomotor activity on UFOV performance in healthy young adults. Eleven participants were tested on three modified UFOV tasks (central processing, peripheral processing, and divided-attention) while seated, standing, and stepping in place. Across all postural conditions, participants showed no difference in their central or peripheral processing. However, in the divided-attention task (reporting the letter in central vision and target location in peripheral vision amongst distracter items) a main effect of posture condition on peripheral target accuracy was found for targets at 57° of eccentricity (p=.037). The mean accuracy reduced from 80.5% (standing) to 74% (seated) to 56.3% (stepping). These findings show that postural demands do affect UFOV divided-attention performance. In particular, the size of the useful field of view significantly decreases when stepping. This finding has important implications for how the results of a UFOV test are used to evaluate the general size of the UFOV during varying activities, as the traditional seated test procedure may overestimate the size of the UFOV during locomotor activities. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Vision restoration therapy does not benefit from costimulation: A pilot study.

PubMed

Kasten, Erich; Bunzenthal, Ulrike; Müller-Oehring, Eva M; Mueller, Iris; Sabel, Bernhard A

2007-08-01

Visual field deficits in patients have long been considered to be nontreatable, but in previous studies we have found an enlargement of the intact visual field following vision restoration therapy (VRT). In the present pilot study, we wished to determine whether a double-stimulation approach would facilitate visual field enlargements beyond those achieved by the single-stimulus paradigm used in standard VRT. This was motivated by the findings that following visual cortex injury in animals, the size of receptive fields could be enlarged by systematic costimulation, where two stimuli were used to excite visual cortex neurons (Eysel, Eyding, & Schweigart, 1998). Patients (n = 23) with stable homonymous field deficits after trauma, cerebral ischemia, or hemorrhage (lesion age > 6 months) carried out either (a) standard VRT with a single stimulation (n = 9), or vision therapy with (b) a parallel costimulation (n = 7) or (c) a moving costimulation paradigm (n = 7). Training was carried out twice daily for 30 min over a 3-month period. Before and after therapy, visual fields were tested with 30 degrees and 90 degrees Tübinger automatic perimetry (TAP) and with high-resolution perimetry (HRP). Eye movements were recorded with an eye tracking system. When data of all three types of visual field training were pooled, we found significant improvements of stimulus detection in HRP (4.2%) and fewer misses within the central 30 degrees perimetrically (-3.7% right eye, OD, or -4.4% left eye, OS). However, the type of training did not make any difference such that the three training groups profited equally. A more detailed analysis of trained versus untrained visual field areas in 16 patients revealed a superiority of the trained area of only 1.1% in HRP and between 3.5% (OS) and 4.4% (OD) in TAP. Spatial attention and alertness improved significantly in all three groups and correlated significantly with visual field enlargements. While vision training had no influence on the patient's testimonials concerning their visual abilities, the patients significantly improved in a practical paper-and-pencil number tracking task (Zahlen-Verbindungs Test; ZVT). Visual field enlargement does not benefit from a double-stimulation paradigm, but visual attention seems to play an important role in vision restoration. The improvements in trained as well as in untrained areas are explained by top-down attentional control mechanisms interacting with local visual cortex plasticity.

Slow changing postural cues cancel visual field dependence on self-tilt detection.

PubMed

Scotto Di Cesare, C; Macaluso, T; Mestre, D R; Bringoux, L

2015-01-01

Interindividual differences influence the multisensory integration process involved in spatial perception. Here, we assessed the effect of visual field dependence on self-tilt detection relative to upright, as a function of static vs. slow changing visual or postural cues. To that aim, we manipulated slow rotations (i.e., 0.05° s(-1)) of the body and/or the visual scene in pitch. Participants had to indicate whether they felt being tilted forward at successive angles. Results show that thresholds for self-tilt detection substantially differed between visual field dependent/independent subjects, when only the visual scene was rotated. This difference was no longer present when the body was actually rotated, whatever the visual scene condition (i.e., absent, static or rotated relative to the observer). These results suggest that the cancellation of visual field dependence by dynamic postural cues may rely on a multisensory reweighting process, where slow changing vestibular/somatosensory inputs may prevail over visual inputs. Copyright © 2014 Elsevier B.V. All rights reserved.

Altered prefrontal function with aging: insights into age-associated performance decline.

PubMed

Solbakk, Anne-Kristin; Fuhrmann Alpert, Galit; Furst, Ansgar J; Hale, Laura A; Oga, Tatsuhide; Chetty, Sundari; Pickard, Natasha; Knight, Robert T

2008-09-26

We examined the effects of aging on visuo-spatial attention. Participants performed a bi-field visual selective attention task consisting of infrequent target and task-irrelevant novel stimuli randomly embedded among repeated standards in either attended or unattended visual fields. Blood oxygenation level dependent (BOLD) responses to the different classes of stimuli were measured using functional magnetic resonance imaging. The older group had slower reaction times to targets, and committed more false alarms but had comparable detection accuracy to young controls. Attended target and novel stimuli activated comparable widely distributed attention networks, including anterior and posterior association cortex, in both groups. The older group had reduced spatial extent of activation in several regions, including prefrontal, basal ganglia, and visual processing areas. In particular, the anterior cingulate and superior frontal gyrus showed more restricted activation in older compared with young adults across all attentional conditions and stimulus categories. The spatial extent of activations correlated with task performance in both age groups, but the regional pattern of association between hemodynamic responses and behavior differed between the groups. Whereas the young subjects relied on posterior regions, the older subjects engaged frontal areas. The results indicate that aging alters the functioning of neural networks subserving visual attention, and that these changes are related to cognitive performance.

How vision and movement combine in the hippocampal place code.

PubMed

Chen, Guifen; King, John A; Burgess, Neil; O'Keefe, John

2013-01-02

How do external environmental and internal movement-related information combine to tell us where we are? We examined the neural representation of environmental location provided by hippocampal place cells while mice navigated a virtual reality environment in which both types of information could be manipulated. Extracellular recordings were made from region CA1 of head-fixed mice navigating a virtual linear track and running in a similar real environment. Despite the absence of vestibular motion signals, normal place cell firing and theta rhythmicity were found. Visual information alone was sufficient for localized firing in 25% of place cells and to maintain a local field potential theta rhythm (but with significantly reduced power). Additional movement-related information was required for normally localized firing by the remaining 75% of place cells. Trials in which movement and visual information were put into conflict showed that they combined nonlinearly to control firing location, and that the relative influence of movement versus visual information varied widely across place cells. However, within this heterogeneity, the behavior of fully half of the place cells conformed to a model of path integration in which the presence of visual cues at the start of each run together with subsequent movement-related updating of position was sufficient to maintain normal fields.

Noticing spiders on the left: Evidence on attentional bias and spider fear in the inattentional blindness paradigm.

PubMed

Brailsford, Richard; Catherwood, Di; Tyson, Philip J; Edgar, Graham

2014-01-01

Attentional biases in anxiety disorders have been assessed primarily using three types of experiment: the emotional Stroop task, the probe-detection task, and variations of the visual search task. It is proposed that the inattentional blindness procedure has the ability to overcome limitations of these paradigms in regard to identifying the components of attentional bias. Three experiments examined attentional responding to spider images in individuals with low and moderate to high spider fear. The results demonstrate that spider fear causes a bias in the engage component of visual attention and this is specific to stimuli presented in the left visual field (i.e., to the right hemisphere). The implications of the results are discussed and recommendations for future research are made.

MR findings in seven patients with organic mercury poisoning (Minamata disease).

PubMed

Korogi, Y; Takahashi, M; Shinzato, J; Okajima, T

1994-09-01

To study the long-term MR findings in seven patients with Minamata disease. All patients examined were affected after eating daily considerable amounts of the methylmercury-contaminated seafoods from 1955 through 1958 and showed typical neurologic findings. T1- and T2-weighted images were obtained in axial, coronal, and sagittal sections. The visual cortex, the cerebellar vermis and hemispheres, and the postcentral cortex were significantly atrophic. The visual cortex was slightly hypointense on T1-weighted images and hyperintense on T2-weighted images, probably representing the pathologic changes of status spongiosus. MR demonstrated the lesions, located in the calcarine area, cerebellum, and postcentral gyri, which are probably related to three of the characteristic manifestations of this disease: the constriction of the visual fields, ataxia, and sensory disturbance, respectively.

[Retinotopic mapping of the human visual cortex with functional magnetic resonance imaging - basic principles, current developments and ophthalmological perspectives].

PubMed

Hoffmann, M B; Kaule, F; Grzeschik, R; Behrens-Baumann, W; Wolynski, B

2011-07-01

Since its initial introduction in the mid-1990 s, retinotopic mapping of the human visual cortex, based on functional magnetic resonance imaging (fMRI), has contributed greatly to our understanding of the human visual system. Multiple cortical visual field representations have been demonstrated and thus numerous visual areas identified. The organisation of specific areas has been detailed and the impact of pathophysiologies of the visual system on the cortical organisation uncovered. These results are based on investigations at a magnetic field strength of 3 Tesla or less. In a field-strength comparison between 3 and 7 Tesla, it was demonstrated that retinotopic mapping benefits from a magnetic field strength of 7 Tesla. Specifically, the visual areas can be mapped with high spatial resolution for a detailed analysis of the visual field maps. Applications of fMRI-based retinotopic mapping in ophthalmological research hold promise to further our understanding of plasticity in the human visual cortex. This is highlighted by pioneering studies in patients with macular dysfunction or misrouted optic nerves. © Georg Thieme Verlag KG Stuttgart · New York.

The effects of retinal abnormalities on the multifocal visual evoked potential.

PubMed

Chen, John Y; Hood, Donald C; Odel, Jeffrey G; Behrens, Myles M

2006-10-01

To examine the effects on the amplitude and latency of the multifocal visual evoked potential (mfVEP) in retinal diseases associated with depressed multifocal electroretinograms (mfERG). Static automated perimetry (SAP), mfERGs, and mfVEPs were obtained from 15 individuals seen by neuro-ophthalmologists and diagnosed with retinal disease based on funduscopic examination, visual field, and mfERG. Optic neuropathy was ruled out in all cases. Diagnoses included autoimmune retinopathy (n = 3), branch retinal arterial occlusion (n = 3), branch retinal vein occlusion (n = 1), vitamin A deficiency (n = 1), digoxin/age-related macular degeneration (n = 1), multiple evanescent white dot syndrome (n = 1), and nonspecific retinal disease (n = 5). Patients were selected from a larger group based on abnormal mfERG amplitudes covering a diameter of 20 degrees or greater. Fourteen (93%) of 15 patients showed significant mfVEP delays, as determined by either mean latency or the probability of a cluster of delayed local responses. Thirteen of 15 patients had normal mfVEP amplitudes in regions corresponding to markedly reduced or nonrecordable mfERG responses. These findings can be mimicked in normal individuals by viewing the display through a neutral-density filter. Retinal diseases can result in mfVEPs of relatively normal amplitudes, often with delays, in regions showing decreased mfERG responses and visual field sensitivity loss. Consequently, a retinal problem can be missed, or dismissed as functional, if a diagnosis is based on an mfVEP of normal or near-normal amplitude. Further, in patients with marked mfVEP delays, a retinal problem could be confused with optic neuritis, especially in a patient with a normal appearing fundus.

Progression of visual field in patients with primary open-angle glaucoma - ProgF study 1.

PubMed

Aptel, Florent; Aryal-Charles, Nishal; Giraud, Jean-Marie; El Chehab, Hussam; Delbarre, Maxime; Chiquet, Christophe; Romanet, Jean-Paul; Renard, Jean-Paul

2015-12-01

To evaluate the visual field rate of progression of patients with treated ocular hypertension (OHT) and primary open-angle glaucoma (POAG) in clinical practice, using the mean deviation (MD) and the visual field index (VFI). Non-interventional cohort study. From a large multicentre database representative of the French population, 441 eyes of 228 patients with treated OHT or POAG followed up at least 6 years with Humphrey 24.2 Sita-Standard visual field examination at least twice a year were identified. From initial data, eyes were classified in five groups: 121 with OHT, 188 with early glaucoma (MD greater than -6 dB), 45 with moderate glaucoma (MD -6 to -12 dB), 41 with advanced glaucoma (MD -12 to -18 dB) and 46 with severe glaucoma (MD less than -18 dB). Rate of progression during the follow-up period was calculated using the trend analysis of the Guided Progression Analysis software. The mean duration of follow-up was 8.4 ± 2.7 years and the mean number of visual field, 18.4 ± 3.5. In eyes with OHT, rate of progression was -0.09 dB/year (-0.17%VFI/year). In eyes with POAG, rate of progression was -0.32 dB/year (-0.83%VFI/year) in eyes with early glaucoma, -0.52 dB/year (-1.81%VFI/year) in moderate glaucoma, -0.54 dB/year (-2.35%VFI/year) in advanced glaucoma and -0.45 dB/year (-1.97%VFI/year) in severe glaucoma. In eyes with POAG, a significant progression (p < 0.05) was detected in 159 of 320 eyes (49.7%) with trend analysis and 117 of 320 eyes (36.6%, likely progression) or 183 of 320 eyes (57.2%, possible and likely progression) with event analysis. Primary open-angle glaucoma is a progressive disease in the majority of patients despite cautioned treatment and follow-up. The rate of progression varies greatly among subjects. © 2015 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

A rare type of Usher's syndrome.

PubMed

Antunica, Antonela Gverović; Kastelan, Snjezana; Bućan, Kajo; Ivanković, Mira; Radman, Maja; Karaman, Ksenija

2013-12-01

A case is presented of a very rare type of Usher's syndrome detected in a 30-year-old woman in her 28th week of pregnancy. She reported left eye visual impairment with a one-month history. She underwent standard ophthalmologic examination with additional procedures scheduled after childbirth, including fluorescein angiography, visual field (Goldman and Octopus) and electroretinography. Fundus examination revealed pallor of the optic disk, diffuse retinal blood vessel narrowing, no retinal pigmentation, left macular edema, vitreous liquefaction, and posterior vitreous detachment. Goldman perimetry showed narrowing of all isopters to 10 degrees, and Octopus perimetry showed peripheral decrease of retinal sensitivity. Electroretinography confirmed the diagnosis of retinitis pigmentosa sine pigmento. Upon collecting case history records, hearing disorders originating from childhood were discovered. To our knowledge, this type of retinitis in Usher's syndrome has been reported only once in the available literature.

Driving with visual field loss : an exploratory simulation study

DOT National Transportation Integrated Search

2009-01-01

The goal of this study was to identify the influence of peripheral visual field loss (VFL) on driving performance in a motion-based driving simulator. Sixteen drivers (6 with VFL and 10 with normal visual fields) completed a 14 km simulated drive. Th...

Collaborative volume visualization with applications to underwater acoustic signal processing

NASA Astrophysics Data System (ADS)

Jarvis, Susan; Shane, Richard T.

2000-08-01

Distributed collaborative visualization systems represent a technology whose time has come. Researchers at the Fraunhofer Center for Research in Computer Graphics have been working in the areas of collaborative environments and high-end visualization systems for several years. The medical application. TeleInVivo, is an example of a system which marries visualization and collaboration. With TeleInvivo, users can exchange and collaboratively interact with volumetric data sets in geographically distributed locations. Since examination of many physical phenomena produce data that are naturally volumetric, the visualization frameworks used by TeleInVivo have been extended for non-medical applications. The system can now be made compatible with almost any dataset that can be expressed in terms of magnitudes within a 3D grid. Coupled with advances in telecommunications, telecollaborative visualization is now possible virtually anywhere. Expert data quality assurance and analysis can occur remotely and interactively without having to send all the experts into the field. Building upon this point-to-point concept of collaborative visualization, one can envision a larger pooling of resources to form a large overview of a region of interest from contributions of numerous distributed members.

How does visual manipulation affect obstacle avoidance strategies used by athletes?

PubMed

Bijman, M P; Fisher, J J; Vallis, L A

2016-01-01

Research examining our ability to avoid obstacles in our path has stressed the importance of visual input. The aim of this study was to determine if athletes playing varsity-level field sports, who rely on visual input to guide motor behaviour, are more able to guide their foot over obstacles compared to recreational individuals. While wearing kinematic markers, eight varsity athletes and eight age-matched controls (aged 18-25) walked along a walkway and stepped over stationary obstacles (180° motion arc). Visual input was manipulated using PLATO visual goggles three or two steps pre-obstacle crossing and compared to trials where vision was given throughout. A main effect between groups for peak trail toe elevation was shown with greater values generated by the controls for all crossing conditions during full vision trials only. This may be interpreted as athletes not perceiving this obstacle as an increased threat to their postural stability. Collectively, findings suggest the athletic group is able to transfer their abilities to non-specific conditions during full vision trials; however, varsity-level athletes were equally reliant on visual cues for these visually guided stepping tasks as their performance was similar to the controls when vision is removed.

Random Wiring, Ganglion Cell Mosaics, and the Functional Architecture of the Visual Cortex

PubMed Central

Coppola, David; White, Leonard E.; Wolf, Fred

2015-01-01

The architecture of iso-orientation domains in the primary visual cortex (V1) of placental carnivores and primates apparently follows species invariant quantitative laws. Dynamical optimization models assuming that neurons coordinate their stimulus preferences throughout cortical circuits linking millions of cells specifically predict these invariants. This might indicate that V1’s intrinsic connectome and its functional architecture adhere to a single optimization principle with high precision and robustness. To validate this hypothesis, it is critical to closely examine the quantitative predictions of alternative candidate theories. Random feedforward wiring within the retino-cortical pathway represents a conceptually appealing alternative to dynamical circuit optimization because random dimension-expanding projections are believed to generically exhibit computationally favorable properties for stimulus representations. Here, we ask whether the quantitative invariants of V1 architecture can be explained as a generic emergent property of random wiring. We generalize and examine the stochastic wiring model proposed by Ringach and coworkers, in which iso-orientation domains in the visual cortex arise through random feedforward connections between semi-regular mosaics of retinal ganglion cells (RGCs) and visual cortical neurons. We derive closed-form expressions for cortical receptive fields and domain layouts predicted by the model for perfectly hexagonal RGC mosaics. Including spatial disorder in the RGC positions considerably changes the domain layout properties as a function of disorder parameters such as position scatter and its correlations across the retina. However, independent of parameter choice, we find that the model predictions substantially deviate from the layout laws of iso-orientation domains observed experimentally. Considering random wiring with the currently most realistic model of RGC mosaic layouts, a pairwise interacting point process, the predicted layouts remain distinct from experimental observations and resemble Gaussian random fields. We conclude that V1 layout invariants are specific quantitative signatures of visual cortical optimization, which cannot be explained by generic random feedforward-wiring models. PMID:26575467

Computer systems and methods for the query and visualization of multidimensional databases

DOEpatents

Stolte, Chris; Tang, Diane L.; Hanrahan, Patrick

2015-11-10

A computer displays a graphical user interface on its display. The graphical user interface includes a schema information region and a data visualization region. The schema information region includes a plurality of fields of a multi-dimensional database that includes at least one data hierarchy. The data visualization region includes a columns shelf and a rows shelf. The computer detects user actions to associate one or more first fields with the columns shelf and to associate one or more second fields with the rows shelf. The computer generates a visual table in the data visualization region in accordance with the user actions. The visual table includes one or more panes. Each pane has an x-axis defined based on data for the one or more first fields, and each pane has a y-axis defined based on data for the one or more second fields.

Comparison of 30-2 Standard and Fast programs of Swedish Interactive Threshold Algorithm of Humphrey Field Analyzer for perimetry in patients with intracranial tumors.

PubMed

Singh, Manav Deep; Jain, Kanika

2017-11-01

To find out whether 30-2 Swedish Interactive Threshold Algorithm (SITA) Fast is comparable to 30-2 SITA Standard as a tool for perimetry among the patients with intracranial tumors. This was a prospective cross-sectional study involving 80 patients aged ≥18 years with imaging proven intracranial tumors and visual acuity better than 20/60. The patients underwent multiple visual field examinations using the two algorithms till consistent and repeatable results were obtained. A total of 140 eyes of 80 patients were analyzed. Almost 60% of patients undergoing perimetry with SITA Standard required two or more sessions to obtain consistent results, whereas the same could be obtained in 81.42% with SITA Fast in the first session itself. Of 140 eyes, 70 eyes had recordable field defects and the rest had no defects as detected by either of the two algorithms. Mean deviation (MD) (P = 0.56), pattern standard deviation (PSD) (P = 0.22), visual field index (P = 0.83) and number of depressed points at P < 5%, 2%, 1%, and 0.5% on MD and PSD probability plots showed no statistically significant difference between two algorithms. Bland-Altman test showed that considerable variability existed between two algorithms. Perimetry performed by SITA Standard and SITA Fast algorithm of Humphrey Field Analyzer gives comparable results among the patients of intracranial tumors. Being more time efficient and with a shorter learning curve, SITA Fast my be recommended as a standard test for the purpose of perimetry among these patients.

Adolescent fluoxetine exposure produces enduring, sex-specific alterations of visual discrimination and attention in rats.

PubMed

LaRoche, Ronee B; Morgan, Russell E

2007-01-01

Over the past two decades the use of selective serotonin reuptake inhibitors (SSRIs) to treat behavioral disorders in children has grown rapidly, despite little evidence regarding the safety and efficacy of these drugs for use in children. Utilizing a rat model, this study investigated whether post-weaning exposure to a prototype SSRI, fluoxetine (FLX), influenced performance on visual tasks designed to measure discrimination learning, sustained attention, inhibitory control, and reaction time. Additionally, sex differences in response to varying doses of fluoxetine were examined. In Experiment 1, female rats were administered (P.O.) fluoxetine (10 mg/kg ) or vehicle (apple juice) from PND 25 thru PND 49. After a 14 day washout period, subjects were trained to perform a simultaneous visual discrimination task. Subjects were then tested for 20 sessions on a visual attention task that consisted of varied stimulus delays (0, 3, 6, or 9 s) and cue durations (200, 400, or 700 ms). In Experiment 2, both male and female Long-Evans rats (24 F, 24 M) were administered fluoxetine (0, 5, 10, or 15 mg/kg) then tested in the same visual tasks used in Experiment 1, with the addition of open-field and elevated plus-maze testing. Few FLX-related differences were seen in the visual discrimination, open field, or plus-maze tasks. However, results from the visual attention task indicated a dose-dependent reduction in the performance of fluoxetine-treated males, whereas fluoxetine-treated females tended to improve over baseline. These findings indicate that enduring, behaviorally-relevant alterations of the CNS can occur following pharmacological manipulation of the serotonin system during postnatal development.

The Impact of a Sports Vision Training Program in Youth Field Hockey Players

PubMed Central

Schwab, Sebastian; Memmert, Daniel

2012-01-01

The aim of this study was to investigate whether a sports vision training program improves the visual performance of youth male field hockey players, ages 12 to 16 years, after an intervention of six weeks compared to a control group with no specific sports vision training. The choice reaction time task at the D2 board (Learning Task I), the functional field of view task (Learning Task II) and the multiple object tracking (MOT) task (Transfer Task) were assessed before and after the intervention and again six weeks after the second test. Analyzes showed significant differences between the two groups for the choice reaction time task at the D2 board and the functional field of view task, with significant improvements for the intervention group and none for the control group. For the transfer task, we could not find statistically significant improvements for either group. The results of this study are discussed in terms of theoretical and practical implications. Key pointsPerceptual training with youth field hockey playersCan a sports vision training program improve the visual performance of youth male field hockey players, ages 12 to 16 years, after an intervention of six weeks compared to a control group with no specific sports vision training?The intervention was performed in the “VisuLab” as DynamicEye® SportsVision Training at the German Sport University Cologne.We ran a series of 3 two-factor univariate analysis of variance (ANOVA) with repeated measures on both within subject independent variables (group; measuring point) to examine the effects on central perception, peripheral perception and choice reaction time.The present study shows an improvement of certain visual abilities with the help of the sports vision training program. PMID:24150071

Smartphone-based colorimetric ELISA implementation for determination of women's reproductive steroid hormone profiles.

PubMed

Ogirala, Tejaswi; Eapen, Ashley; Salvante, Katrina G; Rapaport, Tomas; Nepomnaschy, Pablo A; Parameswaran, Ash M

2017-10-01

Biologists frequently collect and analyze biospecimens in naturalistic (i.e., field) conditions to ascertain information regarding the physiological status of their study participants. Generally, field-collected biospecimens need to be stored frozen in the field and then transported frozen to laboratory facilities where traditional biomarker assays, such as enzyme-linked immunosorbent assays (ELISAs), are conducted. As proper storage and transport of frozen specimens is often logistically difficult and expensive, particularly in nonurban field settings, methods that reduce the need for specimen storage and transport would benefit field-research dependent disciplines such as biology, ecology and epidemiology. One limiting factor to running assays in the field is the use of large and expensive equipment to visualize and quantify the assays, such as microplate readers. Here, we describe an implementation of colorimetric ELISA visualization and quantification using two novel and portable imaging instrumentation systems and data processing techniques for the determination of women's reproductive steroid hormone profiles. Using the light absorbance and transmittance properties of the chemical compounds that make up the hormone assay, we were able to estimate unknown hormone concentrations using a smartphone system and a webcam system. These estimates were comparable to those from a standard laboratory multiple reader (smartphone: accuracy = 82.20%, R 2  > 0.910; webcam: accuracy = 87.59%, R 2  > 0.942). This line of applied research, in the long run, is expected to provide necessary information for examining the extent to which reproductive function varies within and between populations and how it is influenced by psychosocial, energetic and environmental challenges. Our validation of these novel, portable visualization and quantification systems allows for the eventual development of a compact and economical closed system which can be used to quantify biomarker concentrations in remote areas.

Effect of disease stage on progression of hydroxychloroquine retinopathy.

PubMed

Marmor, Michael F; Hu, Julia

2014-09-01

Hydroxychloroquine sulfate retinopathy can progress after the drug is stopped. It is not clear how this relates to the stage of retinopathy or whether early screening with modern imaging technology can prevent progression and visual loss. To determine the relationship between progression of retinopathy and the severity of disease using objective data from optical coherence tomography and assess the value of early screening for the toxic effects of hydroxychloroquine. Clinical findings in patients with hydroxychloroquine retinopathy were monitored with repeated anatomical and functional examinations for 13 to 40 months after the drug was stopped in a referral practice in a university medical center. Eleven patients participated, with the severity of toxic effects categorized as early (patchy parafoveal damage shown on field or objective testing), moderate (a 50%-100% parafoveal ring of optical coherence tomography thinning but intact retinal pigment epithelium), and severe (visible bull's-eye damage). Visual acuity, white 10-2 visual field pattern density plots, fundus autofluorescence, spectral-density optical coherence tomography cross sections, thickness (from cube diagrams), and ellipsoid zone length. Visual acuity and visual fields showed no consistent change. Fundus autofluorescence showed little or no change except in severe cases in which the bull's-eye damage expanded progressively. Optical coherence tomography cross sections showed little visible change in early and moderate cases but progressive foveal thinning (approximately 7 μm/y) and loss of ellipsoid zone (in the range of 100 μm/y) in severe cases, which was confirmed by quantitative measurements. The measurements also showed some foveal thinning (approximately 4 μm/y) and deepening of parafoveal loss in moderate cases, but the breadth of the ellipsoid zone remained constant in both early and moderate cases. A few cases showed a suggestion of ellipsoid zone improvement. Patients with hydroxychloroquine retinopathy involving the retinal pigment epithelium demonstrated progressive damage on optical coherence tomography for at least 3 years after the drug was discontinued, including loss of foveal thickness and cone structure. Cases recognized before retinal pigment epithelium damage retained foveal architecture with little retinal thinning. Early recognition of hydroxychloroquine toxic effects before any fundus changes are visible, using visual fields and optical coherence tomography (along with fundus autofluorescence and multifocal electroretinography as indicated), will greatly minimize late progression and the risk of visual loss.

Barriers to accessing eye care services among visually impaired populations in rural Andhra Pradesh, South India

PubMed Central

Krishnaiah, Sannapaneni; Shamanna, Bindiganavale Ramaswamy; Thomas, Ravi; Rao, Gullapalli N

2007-01-01

Purpose: To understand the reasons why people in rural south India with visual impairment arising from various ocular diseases do not seek eye care. Materials and Methods: A total of 5,573 persons above the age of 15 were interviewed and examined in the South Indian state of Andhra Pradesh covering the districts of Adilabad, West Godavari and Mahaboobnagar. A pre-tested structured questionnaire on barriers to eye care was administered by trained field investigators. Results: Of the eligible subjects, 1234 (22.1%, N=5573)) presented with distant visual acuity < 20/60 or equivalent visual field loss in the better eye. Of these, 898 (72.7%, N=1234) subjects had not sought treatment despite noticing a decrease in vision citing personal, economic and social reasons. The analysis also showed that the odds of seeking treatment was significantly higher for literates [odds ratio (OR) 1.91, 95% confidence interval (CI) 1.38 to 2.65], for those who would be defined as blind by visual acuity category (OR 1.35, 95% CI 0.96 to 1.90) and for those with cataract and other causes of visual impairment (OR 1.50, 95% CI 1.11 to 2.03). Barriers to seeking treatment among those who had not sought treatment despite noticing a decrease in vision over the past five years were personal in 52% of the respondents, economic in 37% and social in 21%. Conclusion: Routine planning for eye care services in rural areas of India must address the barriers to eye care perceived by communities to increase the utilization of services. PMID:17699946

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berres, Anne Sabine

This slide presentation describes basic topological concepts, including topological spaces, homeomorphisms, homotopy, betti numbers. Scalar field topology explores finding topological features and scalar field visualization, and vector field topology explores finding topological features and vector field visualization.

NEUROSARCOIDOSIS MASQUERADING AS A CENTRAL NERVOUS SYSTEM TUMOR.

PubMed

Elia, Maxwell; Kombo, Ninani; Huang, John

2017-01-01

To report a case of neurosarcoidosis with an isolated brain lesion mimicking a low-grade glioma. A 38-year-old woman presented with 2 weeks of blurry vision in the left eye. Ophthalmic examination, visual field testing, fluorescein angiography, laboratory testing, and MRI of the brain were performed. Ophthalmic examination revealed left-sided optic nerve infiltration, and MRI of the brain demonstrated a solitary lesion in the brain. The visual symptoms and ophthalmic examination improved significantly with initiation of high-dose oral prednisone. Because the MRI appearance was concerning for malignancy, a brain biopsy was performed. Pathology demonstrated gliosis consistent with a low-grade central nervous system (CNS) glioma. One year later, after initial loss to ophthalmic follow-up, the right optic nerve became involved, and the patient was again treated successfully for presumed ocular sarcoidosis. At this time, serial neuroimaging demonstrated enlargement of the CNS lesion, prompting rebiopsy. Rebiopsy demonstrated a noncaseating granuloma, confirming the diagnosis of neurosarcoidosis. The patient was treated with 20 mg of methotrexate weekly and a prednisone taper with improvement in visual and neurologic symptoms. The authors present an unusual case of neurosarcoidosis masquerading as a CNS glioma. In cases of solitary CNS granulomas, radiographically differentiating neurosarcoidosis from a glioma can be challenging. In this case, serial ophthalmic examination identifying sequential involvement of both optic nerves helped to identify the underlying cause of the CNS disease as sarcoidosis.

Could Buerger's disease cause nonarteritic anterior ischemic optic neuropathy?: a rare case report.

PubMed

Korkmaz, Anil; Karti, Omer; Top Karti, Dilek; Yüksel, Bora; Zengin, Mehmet Ozgur; Kusbeci, Tuncay

2018-04-05

We present an interesting case with nonarteritic anterior ischemic optic neuropathy (NAION) accompanied by Buerger's disease. A 43-year-old man was referred to our neuro-ophthalmology clinic with a complaint of visual deterioration in the left eye that started 5 days ago. He suffered from Buerger's disease, and he had acute pain in the right lower limb below the knee. His best corrected visual acuity was 10/10 in the right eye and 2/10 in the left eye by Snellen chart. There was a relative afferent pupil defect in the left eye. The right optic disc was normal on fundus examination, and blurring, hemorrhagic swelling was found at the left optic disc. Inferior altitudinal visual field defect was observed in the left eye. Neurological examination was normal. Computed tomography angiography scan revealed occlusion in the right posterior tibial artery. Brain imaging and laboratory tests such as blood analyses, genetic screening, coagulation, and lipid panels were unremarkable. NAION may occur in patients with Buerger's disease, but it is extremely rare. Therefore, clinicians should be aware of this rare association.

The Field of View is More Useful in Golfers than Regular Exercisers

PubMed Central

Murphy, Karen

2017-01-01

Superior visual attention skills are vital for excellent sports performance. This study used a cognitive skills approach to examine expert and novice differences in a visual spatial attention task. Thirty-two males aged 18 to 42 years completed this study in return for course credit or monetary incentive. Participants were expert golfers (N = 18) or exercise controls (N = 14). Spatial attention was assessed using the useful field of view task which required participants to locate a target shown 10°, 20°, and 30° of eccentricity from centre in very brief presentations. At each degree of eccentricity, golfers were more accurate at locating the target than the exercise controls. These results provide support for the broad transfer hypothesis by demonstrating a link between golf expertise and better performance on an objective measure of spatial attention skills. Therefore, it appears that sports expertise can transfer to expertise in non-sport related tasks. PMID:28450973

The eccentricity effect of inhibition of return is resistant to practice.

PubMed

Bao, Yan; Sander, Tilmann; Trahms, Lutz; Pöppel, Ernst; Lei, Quan; Zhou, Bin

2011-08-01

Inhibition of return (IOR) refers to a delayed responding to targets appeared at previously cued location relative to an uncued novel location. In a recent study, Bao and Pöppel reported a functional dissociation of inhibitory processing in the visual field with much stronger IOR magnitude in the far periphery relative to the perifoveal visual field up to 15° eccentricity. The present study aimed to examine whether this effect is sensitive to participant experience or practice. Consistent with previous findings, our data demonstrated a larger IOR magnitude at 21° relative to 7° stimulus eccentricity. More importantly, no practice-related IOR magnitude changes were observed for both perifoveal and peripheral stimuli, although response times did decrease significantly with practice. These results suggest that the eccentricity effect of IOR is a robust phenomenon which is resistant to practice. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Unilateral retinitis pigmentosa occurring in an individual with a mutation in the CLRN1 gene.

PubMed

Sim, Peng Yong; Jeganathan, V Swetha E; Wright, Alan F; Cackett, Peter

2018-03-15

This case report depicts the clinical course of a female patient with unilateral retinitis pigmentosa, who first presented at the age of 12 years. Fundus photography at the time revealed unilateral pigmentary retinopathy, which was associated with extinguished electroretinogram (ERG) signal. At 35 years of age, fundus examination revealed deterioration of pre-existing unilateral pigmentary retinopathy with progressive visual field defect detected on Goldmann visual field testing. ERG findings remained unchanged and multifocal ERG showed unilateral decrease in amplitude in the affected eye. The patient was referred for genetic counselling. Next-generation sequencing identified a deleterious heterozygous c.118T>G (p.Cys40Gly) mutation in the CLRN1 gene. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Motivation, affect, and hemispheric asymmetry: power versus affiliation.

PubMed

Kuhl, Julius; Kazén, Miguel

2008-08-01

In 4 experiments, the authors examined to what extent information related to different social needs (i.e., power vs. affiliation) is associated with hemispheric laterality. Response latencies to a lateralized dot-probe task following lateralized pictures or verbal labels that were associated with positive or negative episodes related to power, affiliation, or achievement revealed clear-cut laterality effects. These effects were a function of need content rather than of valence: Power-related stimuli were associated with right visual field (left hemisphere) superiority, whereas affiliation-related stimuli were associated with left visual field (right hemisphere) superiority. Additional results demonstrated that in contrast to power, affiliation primes were associated with better discrimination between coherent word triads (e.g., goat, pass, and green, all related to mountain) and noncoherent triads, a remote associate task known to activate areas of the right hemisphere. (c) 2008 APA, all rights reserved

Development of a Bayesian Estimator for Audio-Visual Integration: A Neurocomputational Study

PubMed Central

Ursino, Mauro; Crisafulli, Andrea; di Pellegrino, Giuseppe; Magosso, Elisa; Cuppini, Cristiano

2017-01-01

The brain integrates information from different sensory modalities to generate a coherent and accurate percept of external events. Several experimental studies suggest that this integration follows the principle of Bayesian estimate. However, the neural mechanisms responsible for this behavior, and its development in a multisensory environment, are still insufficiently understood. We recently presented a neural network model of audio-visual integration (Neural Computation, 2017) to investigate how a Bayesian estimator can spontaneously develop from the statistics of external stimuli. Model assumes the presence of two unimodal areas (auditory and visual) topologically organized. Neurons in each area receive an input from the external environment, computed as the inner product of the sensory-specific stimulus and the receptive field synapses, and a cross-modal input from neurons of the other modality. Based on sensory experience, synapses were trained via Hebbian potentiation and a decay term. Aim of this work is to improve the previous model, including a more realistic distribution of visual stimuli: visual stimuli have a higher spatial accuracy at the central azimuthal coordinate and a lower accuracy at the periphery. Moreover, their prior probability is higher at the center, and decreases toward the periphery. Simulations show that, after training, the receptive fields of visual and auditory neurons shrink to reproduce the accuracy of the input (both at the center and at the periphery in the visual case), thus realizing the likelihood estimate of unimodal spatial position. Moreover, the preferred positions of visual neurons contract toward the center, thus encoding the prior probability of the visual input. Finally, a prior probability of the co-occurrence of audio-visual stimuli is encoded in the cross-modal synapses. The model is able to simulate the main properties of a Bayesian estimator and to reproduce behavioral data in all conditions examined. In particular, in unisensory conditions the visual estimates exhibit a bias toward the fovea, which increases with the level of noise. In cross modal conditions, the SD of the estimates decreases when using congruent audio-visual stimuli, and a ventriloquism effect becomes evident in case of spatially disparate stimuli. Moreover, the ventriloquism decreases with the eccentricity. PMID:29046631

Vision problems

MedlinePlus

... shade or curtain hanging across part of your visual field. Optic neuritis : inflammation of the optic nerve ... to ask your doctor Images Crossed eyes Eye Visual acuity test Slit-lamp exam Visual field test ...

Useful field of view in simulated driving: Reaction times and eye movements of drivers

PubMed Central

Seya, Yasuhiro; Nakayasu, Hidetoshi; Yagi, Tadasu

2013-01-01

To examine the spatial distribution of a useful field of view (UFOV) in driving, reaction times (RTs) and eye movements were measured in simulated driving. In the experiment, a normal or mirror-reversed letter “E” was presented on driving images with different eccentricities and directions from the current gaze position. The results showed significantly slower RTs in the upper and upper left directions than in the other directions. The RTs were significantly slower in the left directions than in the right directions. These results suggest that the UFOV in driving may be asymmetrical among the meridians in the visual field. PMID:24349688

Magnetosphere-Ionosphere Coupling in the Auroral Zone

NASA Technical Reports Server (NTRS)

Schriver, David

2004-01-01

The visual light display at high latitudes referred to as the aurora fascinates casual observers and researchers alike. The natural question is what causes the aurora? We know that energized electrons streaming along the Earth's ambient magnetic field and colliding with atmospheric particles produce aurora. We do not know for certain, however, how these electrons are accelerated to high energies primarily in the field-aligned direction toward the Earth, or what the drivers of this acceleration are. As such, the goal of this Guest Investigator research project was to examine the physical processes that can cause field-aligned acceleration of plasma particles in the auroral region.

21 CFR 886.1360 - Visual field laser instrument.

Code of Federal Regulations, 2010 CFR

2010-04-01

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

Accelerated damage visualization using binary search with fixed pitch-catch distance laser ultrasonic scanning

NASA Astrophysics Data System (ADS)

Park, Byeongjin; Sohn, Hoon

2017-07-01

Laser ultrasonic scanning, especially full-field wave propagation imaging, is attractive for damage visualization thanks to its noncontact nature, sensitivity to local damage, and high spatial resolution. However, its practicality is limited because scanning at a high spatial resolution demands a prohibitively long scanning time. Inspired by binary search, an accelerated damage visualization technique is developed to visualize damage with a reduced scanning time. The pitch-catch distance between the excitation point and the sensing point is also fixed during scanning to maintain a high signal-to-noise ratio (SNR) of measured ultrasonic responses. The approximate damage boundary is identified by examining the interactions between ultrasonic waves and damage observed at the scanning points that are sparsely selected by a binary search algorithm. Here, a time-domain laser ultrasonic response is transformed into a spatial ultrasonic domain response using a basis pursuit approach so that the interactions between ultrasonic waves and damage, such as reflections and transmissions, can be better identified in the spatial ultrasonic domain. Then, the area inside the identified damage boundary is visualized as damage. The performance of the proposed damage visualization technique is validated excusing a numerical simulation performed on an aluminum plate with a notch and experiments performed on an aluminum plate with a crack and a wind turbine blade with delamination. The proposed damage visualization technique accelerates the damage visualization process in three aspects: (1) the number of measurements that is necessary for damage visualization is dramatically reduced by a binary search algorithm; (2) the number of averaging that is necessary to achieve a high SNR is reduced by maintaining the wave propagation distance short; and (3) with the proposed technique, the same damage can be identified with a lower spatial resolution than the spatial resolution required by full-field wave propagation imaging.

Dioptric defocus maps across the visual field for different indoor environments.

PubMed

García, Miguel García; Ohlendorf, Arne; Schaeffel, Frank; Wahl, Siegfried

2018-01-01

One of the factors proposed to regulate the eye growth is the error signal derived from the defocus in the retina and actually, this might arise from defocus not only in the fovea but the whole visual field. Therefore, myopia could be better predicted by spatio-temporally mapping the 'environmental defocus' over the visual field. At present, no devices are available that could provide this information. A 'Kinect sensor v1' camera (Microsoft Corp.) and a portable eye tracker were used for developing a system for quantifying 'indoor defocus error signals' across the central 58° of the visual field. Dioptric differences relative to the fovea (assumed to be in focus) were recorded over the visual field and 'defocus maps' were generated for various scenes and tasks.

Word learning and the cerebral hemispheres: from serial to parallel processing of written words

PubMed Central

Ellis, Andrew W.; Ferreira, Roberto; Cathles-Hagan, Polly; Holt, Kathryn; Jarvis, Lisa; Barca, Laura

2009-01-01

Reading familiar words differs from reading unfamiliar non-words in two ways. First, word reading is faster and more accurate than reading of unfamiliar non-words. Second, effects of letter length are reduced for words, particularly when they are presented in the right visual field in familiar formats. Two experiments are reported in which right-handed participants read aloud non-words presented briefly in their left and right visual fields before and after training on those items. The non-words were interleaved with familiar words in the naming tests. Before training, naming was slow and error prone, with marked effects of length in both visual fields. After training, fewer errors were made, naming was faster, and the effect of length was much reduced in the right visual field compared with the left. We propose that word learning creates orthographic word forms in the mid-fusiform gyrus of the left cerebral hemisphere. Those word forms allow words to access their phonological and semantic representations on a lexical basis. But orthographic word forms also interact with more posterior letter recognition systems in the middle/inferior occipital gyri, inducing more parallel processing of right visual field words than is possible for any left visual field stimulus, or for unfamiliar non-words presented in the right visual field. PMID:19933140

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

PubMed

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

2017-06-01

The aim of this study was to demonstrate and explore the ability of novel game-based perimetry to establish normal visual field thresholds in children. One hundred and eighteen children (aged 8.0 ± 2.8 years old) with no history of visual field loss or significant medical history were recruited. Each child had one eye tested using a game-based visual field test 'Caspar's Castle' at four retinal locations 12.7° (N = 118) from fixation. Thresholds were established repeatedly using up/down staircase algorithms with stimuli of varying diameter (luminance 20 cd/m 2 , duration 200 ms, background luminance 10 cd/m 2 ). Relationships between threshold and age were determined along with measures of intra- and intersubject variability. The Game-based visual field test was able to establish threshold estimates in the full range of children tested. Threshold size reduced with increasing age in children. Intrasubject variability and intersubject variability were inversely related to age in children. Normal visual field thresholds were established for specific locations in children using a novel game-based visual field test. These could be used as a foundation for developing a game-based perimetry screening test for children.

Nasendoscopy: an analysis of measurement uncertainties.

PubMed

Gilleard, Onur; Sommerlad, Brian; Sell, Debbie; Ghanem, Ali; Birch, Malcolm

2013-05-01

Objective : The purpose of this study was to analyze the optical characteristics of two different nasendoscopes used to assess velopharyngeal insufficiency and to quantify the measurement uncertainties that will occur in a typical set of clinical data. Design : The magnification and barrel distortion associated with nasendoscopy was estimated by using computer software to analyze the apparent dimensions of a spatially calibrated test object at varying object-lens distances. In addition, a method of semiquantitative analysis of velopharyngeal closure using nasendoscopy and computer software is described. To calculate the reliability of this method, 10 nasendoscopy examinations were analyzed two times by three separate operators. The measure of intraoperator and interoperator agreement was evaluated using Pearson's r correlation coefficient. Results : Over an object lens distance of 9 mm, magnification caused the visualized dimensions of the test object to increase by 80%. In addition, dimensions of objects visualized in the far-peripheral field of the nasendoscopic examinations appeared approximately 40% smaller than those visualized in the central field. Using computer software to analyze velopharyngeal closure, the mean correlation coefficient for intrarater reliability was .94 and for interrater reliability was .90. Conclusion : Using a custom-designed apparatus, the effect object-lens distance has on the magnification of nasendoscopic images has been quantified. Barrel distortion has also been quantified and was found to be independent of object-lens distance. Using computer software to analyze clinical images, the intraoperator and interoperator correlation appears to show that ratio-metric measurements are reliable.

Functional decor in the International Space Station: Body orientation cues and picture perception

NASA Technical Reports Server (NTRS)

Coss, Richard G.; Clearwater, Yvonne A.; Barbour, Christopher G.; Towers, Steven R.

1989-01-01

Subjective reports of American astronauts and their Soviet counterparts suggest that homogeneous, often symmetrical, spacecraft interiors can contribute to motion sickness during the earliest phase of a mission and can also engender boredom. Two studies investigated the functional aspects of Space Station interior aesthetics. One experiment examined differential color brightnesses as body orientation cues; the other involved a large survey of photographs and paintings that might enhance the interior aesthetics of the proposed International Space Station. Ninety male and female college students reclining on their backs in the dark were disoriented by a rotating platform and inserted under a slowly rotating disk that filled their entire visual field. The entire disk was painted the same color but one half had a brightness value that was about 69 percent higher than the other. The effects of red, blue, and yellow were examined. Subjects wearing frosted goggles opened their eyes to view the rotating, illuminated disk, which was stopped when they felt that they were right-side up. For all three colors, significant numbers of subjects said they felt right-side up when the brighter side of the disk filled their upper visual field. These results suggest that color brightness could provide Space Station crew members with body orientation cues as they move about. It was found that subjects preferred photographs and paintings with the greatest depths of field, irrespective of picture topic.

Tablets at the bedside - iPad-based visual field test used in the diagnosis of Intrasellar Haemangiopericytoma: a case report.

PubMed

Nesaratnam, Nisha; Thomas, Peter B M; Kirollos, Ramez; Vingrys, Algis J; Kong, George Y X; Martin, Keith R

2017-04-24

In the assessment of a pituitary mass, objective visual field testing represents a valuable means of evaluating mass effect, and thus in deciding whether surgical management is warranted. In this vignette, we describe a 73 year-old lady who presented with a three-week history of frontal headache, and 'blurriness' in the left side of her vision, due to a WHO grade III anaplastic haemangiopericytoma compressing the optic chiasm. We report how timely investigations, including an iPad-based visual field test (Melbourne Rapid Field, (MRF)) conducted at the bedside aided swift and appropriate management of the patient. We envisage such a test having a role in assessing bed-bound patients in hospital where access to formal visual field testing is difficult, or indeed in rapid testing of visual fields at the bedside to screen for post-operative complications, such as haematoma.

Cerebral specialization for spatial processing in adults with Down syndrome.

PubMed

Elliott, D; Pollock, B J; Chua, R; Weeks, D J

1995-05-01

Cerebral specialization for spatial processing in adults with Down syndrome was examined. In the first experiment, both control and right-handed subjects with Down syndrome exhibited no lateral advantage in a dihaptic shape-matching task, whereas left-handed subjects with Down syndrome displayed an expected left-hand advantage. In a visual field dot enumeration task in the second experiment, all groups exhibited left-field superiority. Thus, atypical cerebral organization of function in adults with Down syndrome appears to be confined to speech perception (Elliott & Weeks, 1993).

Coherent Doppler lidar for measurements of wind fields

NASA Technical Reports Server (NTRS)

Menzies, Robert T.; Hardesty, R. Michael

1989-01-01

The signal-processing techniques for obtaining the velocity estimates and the fundamental factors that influence coherent lidar performance are considered. The similarities and distinctions between Doppler lidar and Doppler radars are discussed. The capability of coherent Doppler lidars for mapping wind fields over selected regions in the lower atmosphere and greatly enhancing the capability to visualize flow patterns in real time is discussed, and examples are given. Salient features of a concept for an earth-orbiting Doppler lidar to be launched in the late 1990s are examined.

Incidence and rates of visual field progression after longitudinally measured optic disc change in glaucoma.

PubMed

Chauhan, Balwantray C; Nicolela, Marcelo T; Artes, Paul H

2009-11-01

To determine whether glaucoma patients with progressive optic disc change have subsequent visual field progression earlier and at a faster rate compared with those without disc change. Prospective, longitudinal, cohort study. Eighty-one patients with open-angle glaucoma. Patients underwent confocal scanning laser tomography and standard automated perimetry every 6 months. The complete follow-up was divided into initial and subsequent periods. Two initial periods-first 3 years (Protocol A) and first half of the total follow-up (Protocol B)-were used, with the respective remainder being the subsequent follow-up. Disc change during the initial follow-up was determined with liberal, moderate, or conservative criteria of the Topographic Change Analysis. Subsequent field progression was determined with significant pattern deviation change in >or=3 locations (criterion used in the Early Manifest Glaucoma Trial). As a control analysis, field change during the initial follow-up was determined with significant pattern deviation change in >or=1, >or=2, or >or=3 locations. Survival time to subsequent field progression, rates of mean deviation (MD) change, and positive and negative likelihood ratios. The median (interquartile range) total follow-up was 11.0 (8.0-12.0) years with 22 (18-24) examinations. More patients had disc changes during the initial follow-up compared with field changes. The mean time to field progression was consistently shorter (protocol A, 0.8-1.7 years; protocol B, 0.3-0.7 years) in patients with prior disc change. In the control analysis, patients with prior field change had statistically earlier subsequent field progression (protocol A, 2.9-3.0 years; protocol B, 0.7-0.9). Similarly, patients with either prior disc or field change always had worse mean rates of subsequent MD change, although the distributions overlapped widely. Patients with subsequent field progression were up to 3 times more likely to have prior disc change compared with those without, and up to 5 times more likely to have prior field change compared with those without. Longitudinally measured optic disc change is predictive of subsequent visual field progression and may be an efficacious end point for functional outcomes in clinical studies and trials in glaucoma.

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

PubMed

Fledelius, Hans C

2009-11-01

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

Face, Body, and Center of Gravity Mediate Person Detection in Natural Scenes

ERIC Educational Resources Information Center

Bindemann, Markus; Scheepers, Christoph; Ferguson, Heather J.; Burton, A. Mike

2010-01-01

Person detection is an important prerequisite of social interaction, but is not well understood. Following suggestions that people in the visual field can capture a viewer's attention, this study examines the role of the face and the body for person detection in natural scenes. We observed that viewers tend first to look at the center of a scene,…

Hemispheric Differences in the Time-Course of Semantic Priming Processes: Evidence from Event-Related Potentials (ERPs)

ERIC Educational Resources Information Center

Bouaffre, Sarah; Faita-Ainseba, Frederique

2007-01-01

To investigate hemispheric differences in the timing of word priming, the modulation of event-related potentials by semantic word relationships was examined in each cerebral hemisphere. Primes and targets, either categorically (silk-wool) or associatively (needle-sewing) related, were presented to the left or right visual field in a go/no-go…

New Applications for the Testing and Visualization of Wireless Networks

NASA Technical Reports Server (NTRS)

Griffin, Robert I.; Cauley, Michael A.; Pleva, Michael A.; Seibert, Marc A.; Lopez, Isaac

2005-01-01

Traditional techniques for examining wireless networks use physical link characteristics such as Signal-to-Noise (SNR) ratios to assess the performance of wireless networks. Such measurements may not be reliable indicators of available bandwidth. This work describes two new software applications developed at NASA Glenn Research Center for the investigation of wireless networks. GPSIPerf combines measurements of Transmission Control Protocol (TCP) throughput with Global Positioning System (GPS) coordinates to give users a map of wireless bandwidth for outdoor environments where a wireless infrastructure has been deployed. GPSIPerfView combines the data provided by GPSIPerf with high-resolution digital elevation maps (DEM) to help users visualize and assess the impact of elevation features on wireless networks in a given sample area. These applications were used to examine TCP throughput in several wireless network configurations at desert field sites near Hanksville, Utah during May of 2004. Use of GPSIPerf and GPSIPerfView provides a geographically referenced picture of the extent and deterioration of TCP throughput in tested wireless network configurations. GPSIPerf results from field-testing in Utah suggest that it can be useful in assessing other wireless network architectures, and may be useful to future human-robotic exploration missions.

Coats-like retinitis pigmentosa: Reports of three cases

PubMed Central

Kan, Emrah; Yilmaz, Turgut; Aydemir, Orhan; Güler, Mete; Kurt, Jülide

2007-01-01

Purpose: Describing the ophthalmic findings of an exudative vasculopathy called as Coats-like retinitis pigmentosa on three patients. The etiology of the Coats-like retinitis pigmentosa is obscure. The principal theories have been discussed in this article. Methods: Three observational case series have been discussed. Complete ophthalmic examinations and color fundus photos, visual field, and fluorescein angiography have been performed. Results: We have identified 3 patients who have some typical clinical features of Coats-like retinitis pigmentosa; peripheral serous retinal detachment, telangiectasia, prominent lipid deposition, pigmentary changes in peripheral retina, and loss of vision. None of the three patients had positive family history. All of the patients have had symptoms of nyctalopia, decreased central vision, and two of them have had constriction of visual field. All of the patients have had cataracts and two of them underwent cataract surgery. Fundus examination and fluorescein angiography of patients revealed typical retinitis pigmentosa with Coats-type changes in bilateral inferiotemporal quadrants. Conclusion: A better understanding of clinical features and genetic etiology of Coats-type retinitis pigmentosa will aid diagnosis and development of new therapies. If sufficient conditions arise, genetic factors that influence the expression of CRB1 mutations in Coats-like retinitis pigmentosa should be detected. PMID:19668510

Coats-like retinitis pigmentosa: Reports of three cases.

PubMed

Kan, Emrah; Yilmaz, Turgut; Aydemir, Orhan; Güler, Mete; Kurt, Jülide

2007-06-01

Describing the ophthalmic findings of an exudative vasculopathy called as Coats-like retinitis pigmentosa on three patients. The etiology of the Coats-like retinitis pigmentosa is obscure. The principal theories have been discussed in this article. Three observational case series have been discussed. Complete ophthalmic examinations and color fundus photos, visual field, and fluorescein angiography have been performed. We have identified 3 patients who have some typical clinical features of Coats-like retinitis pigmentosa; peripheral serous retinal detachment, telangiectasia, prominent lipid deposition, pigmentary changes in peripheral retina, and loss of vision. None of the three patients had positive family history. All of the patients have had symptoms of nyctalopia, decreased central vision, and two of them have had constriction of visual field. All of the patients have had cataracts and two of them underwent cataract surgery. Fundus examination and fluorescein angiography of patients revealed typical retinitis pigmentosa with Coats-type changes in bilateral inferiotemporal quadrants. A better understanding of clinical features and genetic etiology of Coats-type retinitis pigmentosa will aid diagnosis and development of new therapies. If sufficient conditions arise, genetic factors that influence the expression of CRB1 mutations in Coats-like retinitis pigmentosa should be detected.

Clinical characteristics of occult macular dystrophy in family with mutation of RP1l1 gene.

PubMed

Tsunoda, Kazushige; Usui, Tomoaki; Hatase, Tetsuhisa; Yamai, Satoshi; Fujinami, Kaoru; Hanazono, Gen; Shinoda, Kei; Ohde, Hisao; Akahori, Masakazu; Iwata, Takeshi; Miyake, Yozo

2012-06-01

To report the clinical characteristics of occult macular dystrophy (OMD) in members of one family with a mutation of the RP1L1 gene. Fourteen members with a p.Arg45Trp mutation in the RP1L1 gene were examined. The visual acuity, visual fields, fundus photographs, fluorescein angiograms, full-field electroretinograms, multifocal electroretinograms, and optical coherence tomographic images were examined. The clinical symptoms and signs and course of the disease were documented. All the members with the RP1L1 mutation except one woman had ocular symptoms and signs of OMD. The fundus was normal in all the patients during the entire follow-up period except in one patient with diabetic retinopathy. Optical coherence tomography detected the early morphologic abnormalities both in the photoreceptor inner/outer segment line and cone outer segment tip line. However, the multifocal electroretinograms were more reliable in detecting minimal macular dysfunction at an early stage of OMD. The abnormalities in the multifocal electroretinograms and optical coherence tomography observed in the OMD patients of different durations strongly support the contribution of RP1L1 mutation to the presence of this disease.

Flashes and floaters - a practical approach to assessment and management.

PubMed

Kahawita, Shyalle; Simon, Sumu; Gilhotra, Jolly

2014-04-01

Flashes and floaters are common ophthalmic issues for which patients may initially present to their general practitioner. It may be a sign of benign, 
age-related changes of the vitreous or more serious retinal detachment. This article provides a guide to the assessment and management of a patient presenting with flashes and floaters. Although most patients presenting with flashes and floaters have benign 
age-related changes, they must be referred to an ophthalmologist to rule out sight-threatening conditions. Key examination features include the nature of the flashes and floaters, whether one or both eyes are affected and changes in visual acuity or visual field.

A Sticky Situation.

PubMed

Weng, Christina Y; Khimani, Karima S; Foroozan, Rod; Gospe, Sidney M; Bhatti, M Tariq

2018-04-26

An 81-year-old man with bilateral progressively blurry vision and optic disc swelling was referred for evaluation. Examination and ancillary testing confirmed a diagnosis of bilateral vitreopapillary traction (VPT) accompanied by unilateral tractional retinoschisis in the right eye. Pars plana vitrectomy was performed to release the traction in both eyes. Visual acuity improved in the right eye and stabilized in the left eye. Retinoschisis in the right eye resolved. The visual field improved in both eyes, although the left eye demonstrated a persistent hemifield defect likely attributable to a prior optic neuropathy. Distinguishing VPT optic neuropathy (VPTON) from nonarteritic anterior ischemic optic neuropathy (NAION) is discussed. Copyright © 2018 Elsevier Inc. All rights reserved.

Discussion on the 3D visualizing of 1:200 000 geological map

NASA Astrophysics Data System (ADS)

Wang, Xiaopeng

2018-01-01

Using United States National Aeronautics and Space Administration Shuttle Radar Topography Mission (SRTM) terrain data as digital elevation model (DEM), overlap scanned 1:200 000 scale geological map, program using Direct 3D of Microsoft with C# computer language, the author realized the three-dimensional visualization of the standard division geological map. User can inspect the regional geology content with arbitrary angle, rotating, roaming, and can examining the strata synthetical histogram, map section and legend at any moment. This will provide an intuitionistic analyzing tool for the geological practitioner to do structural analysis with the assistant of landform, dispose field exploration route etc.

Visual discrimination training improves Humphrey perimetry in chronic cortically induced blindness.

PubMed

Cavanaugh, Matthew R; Huxlin, Krystel R

2017-05-09

To assess if visual discrimination training improves performance on visual perimetry tests in chronic stroke patients with visual cortex involvement. 24-2 and 10-2 Humphrey visual fields were analyzed for 17 chronic cortically blind stroke patients prior to and following visual discrimination training, as well as in 5 untrained, cortically blind controls. Trained patients practiced direction discrimination, orientation discrimination, or both, at nonoverlapping, blind field locations. All pretraining and posttraining discrimination performance and Humphrey fields were collected with online eye tracking, ensuring gaze-contingent stimulus presentation. Trained patients recovered ∼108 degrees 2 of vision on average, while untrained patients spontaneously improved over an area of ∼16 degrees 2 . Improvement was not affected by patient age, time since lesion, size of initial deficit, or training type, but was proportional to the amount of training performed. Untrained patients counterbalanced their improvements with worsening of sensitivity over ∼9 degrees 2 of their visual field. Worsening was minimal in trained patients. Finally, although discrimination performance improved at all trained locations, changes in Humphrey sensitivity occurred both within trained regions and beyond, extending over a larger area along the blind field border. In adults with chronic cortical visual impairment, the blind field border appears to have enhanced plastic potential, which can be recruited by gaze-controlled visual discrimination training to expand the visible field. Our findings underscore a critical need for future studies to measure the effects of vision restoration approaches on perimetry in larger cohorts of patients. Copyright © 2017 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.

Open angle glaucoma effects on preattentive visual search efficiency for flicker, motion displacement and orientation pop-out tasks.

PubMed

Loughman, James; Davison, Peter; Flitcroft, Ian

2007-11-01

Preattentive visual search (PAVS) describes rapid and efficient retinal and neural processing capable of immediate target detection in the visual field. Damage to the nerve fibre layer or visual pathway might reduce the efficiency with which the visual system performs such analysis. The purpose of this study was to test the hypothesis that patients with glaucoma are impaired on parallel search tasks, and that this would serve to distinguish glaucoma in early cases. Three groups of observers (glaucoma patients, suspect and normal individuals) were examined, using computer-generated flicker, orientation, and vertical motion displacement targets to assess PAVS efficiency. The task required rapid and accurate localisation of a singularity embedded in a field of 119 homogeneous distractors on either the left or right-hand side of a computer monitor. All subjects also completed a choice reaction time (CRT) task. Independent sample T tests revealed PAVS efficiency to be significantly impaired in the glaucoma group compared with both normal and suspect individuals. Performance was impaired in all types of glaucoma tested. Analysis between normal and suspect individuals revealed a significant difference only for motion displacement response times. Similar analysis using a PAVS/CRT index confirmed the glaucoma findings but also showed statistically significant differences between suspect and normal individuals across all target types. A test of PAVS efficiency appears capable of differentiating early glaucoma from both normal and suspect cases. Analysis incorporating a PAVS/CRT index enhances the diagnostic capacity to differentiate normal from suspect cases.

Cortical metabolic activity matches the pattern of visual suppression in strabismus.

PubMed

Adams, Daniel L; Economides, John R; Sincich, Lawrence C; Horton, Jonathan C

2013-02-27

When an eye becomes deviated in early childhood, a person does not experience double vision, although the globes are aimed at different targets. The extra image is prevented from reaching perception in subjects with alternating exotropia by suppression of each eye's peripheral temporal retina. To test the impact of visual suppression on neuronal activity in primary (striate) visual cortex, the pattern of cytochrome oxidase (CO) staining was examined in four macaques raised with exotropia by disinserting the medial rectus muscles shortly following birth. No ocular dominance columns were visible in opercular cortex, where the central visual field is represented, indicating that signals coming from the central retina in each eye were perceived. However, the border strips at the edges of ocular dominance columns appeared pale, reflecting a loss of activity in binocular cells from disruption of fusion. In calcarine cortex, where the peripheral visual field is represented, there were alternating pale and dark bands resembling ocular dominance columns. To interpret the CO staining pattern, [(3)H]proline was injected into the right eye in two monkeys. In the right calcarine cortex, the pale CO columns matched the labeled proline columns of the right eye. In the left calcarine cortex, the pale CO columns overlapped the unlabeled columns of the left eye in the autoradiograph. Therefore, metabolic activity was reduced in the ipsilateral eye's ocular dominance columns which serve peripheral temporal retina, in a fashion consistent with the topographic organization of suppression scotomas in humans with exotropia.

Stage II Chronic Maxillary Atelectasis Associated with Subclinical Visual Field Defect.

PubMed

Mangussi-Gomes, João; Nakanishi, Márcio; Chalita, Maria Regina; Damasco, Fabiana; De Oliveira, Carlos Augusto Costa Pires

2013-10-01

Introduction Chronic maxillary atelectasis (CMA) is characterized by a persistent decrease in the maxillary sinus volume due to inward bowing of its walls. According to its severity, it may be classified into three clinical-radiological stages. Objective To report a case of stage II CMA associated with subclinical visual field defect. Case Report A 34-year-old woman presented with a 15-year history of recurrent episodes of sinusitis and intermittent right facial discomfort for the past 5 years. She denied visual complaints, and no facial deformities were observed on physical examination. Paranasal sinus computed tomography (CT) demonstrated a completely opacified right maxillary sinus with inward bowing of its walls, suggesting the diagnosis of stage II CMA. A computerized campimetry (CC) disclosed a scotoma adjacent to the blind spot of the right eye, indicating a possible damage to the optic nerve. The patient was submitted to functional endoscopic sinus surgery, with drainage of a thick mucous fluid from the sinus. She did well after surgery and has been asymptomatic since then. Postoperative CT was satisfactory and CC was normal. Discussion CMA occurs because of a persistent ostiomeatal obstruction, which creates negative pressure inside the sinus. It is associated with nasosinusal symptoms but had never been described in association with any visual field defect. It can be divided into stage I (membranous deformity), stage II (bony deformity), and stage III (clinical deformity). The silent sinus syndrome is a special form of CMA. This term should only be used to describe those cases with spontaneous enophthalmos, hypoglobus, and/or midfacial deformity in the absence of nasosinusal symptoms.

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

PubMed Central

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

2015-01-01

Abstract Visual field assessment is an important clinical evaluation for eye disease and neurological injury. We evaluated Octopus semi-automated kinetic peripheral perimetry (SKP) and Humphrey static automated central perimetry for detection of neurological visual field loss in patients with pituitary disease. We carried out a prospective cross-sectional diagnostic accuracy study comparing Humphrey central 30-2 SITA threshold programme with a screening protocol for SKP on Octopus perimetry. Humphrey 24-2 data were extracted from 30-2 results. Results were independently graded for presence/absence of field defect plus severity of defect. Fifty patients (100 eyes) were recruited (25 males and 25 females), with mean age of 52.4 years (SD = 15.7). Order of perimeter assessment (Humphrey/Octopus first) and order of eye tested (right/left first) were randomised. The 30-2 programme detected visual field loss in 85%, the 24-2 programme in 80%, and the Octopus combined kinetic/static strategy in 100% of eyes. Peripheral visual field loss was missed by central threshold assessment. Qualitative comparison of type of visual field defect demonstrated a match between Humphrey and Octopus results in 58%, with a match for severity of defect in 50%. Tests duration was 9.34 minutes (SD = 2.02) for Humphrey 30-2 versus 10.79 minutes (SD = 4.06) for Octopus perimetry. Octopus semi-automated kinetic perimetry was found to be superior to central static testing for detection of pituitary disease-related visual field loss. Where reliant on Humphrey central static perimetry, the 30-2 programme is recommended over the 24-2 programme. Where kinetic perimetry is available, this is preferable to central static programmes for increased detection of peripheral visual field loss. PMID:27928344

Cosmography and Data Visualization

NASA Astrophysics Data System (ADS)

Pomarède, Daniel; Courtois, Hélène M.; Hoffman, Yehuda; Tully, R. Brent

2017-05-01

Cosmography, the study and making of maps of the universe or cosmos, is a field where visual representation benefits from modern three-dimensional visualization techniques and media. At the extragalactic distance scales, visualization is contributing to our understanding of the complex structure of the local universe in terms of spatial distribution and flows of galaxies and dark matter. In this paper, we report advances in the field of extragalactic cosmography obtained using the SDvision visualization software in the context of the Cosmicflows Project. Here, multiple visualization techniques are applied to a variety of data products: catalogs of galaxy positions and galaxy peculiar velocities, reconstructed velocity field, density field, gravitational potential field, velocity shear tensor viewed in terms of its eigenvalues and eigenvectors, envelope surfaces enclosing basins of attraction. These visualizations, implemented as high-resolution images, videos, and interactive viewers, have contributed to a number of studies: the cosmography of the local part of the universe, the nature of the Great Attractor, the discovery of the boundaries of our home supercluster of galaxies Laniakea, the mapping of the cosmic web, and the study of attractors and repellers.

Supporting Geographic Investigations and Visualizations and Engaging Students as Citizen Scientists

NASA Astrophysics Data System (ADS)

Takaki, E.

2011-12-01

Historically, citizen science projects have had to provide their own technical infrastructure to handle the data they collect. National Geographic Education Programs (funded by the National Science Foundation) has developed a free (or low cost for large projects) online data visualization and analysis tool called FieldScope, which is available to any person or group doing studies that involve geographically dispersed data. FieldScope can house and scaffold the analysis of authentic environmental data as well as augment it with other helpful layers such as precipitation, population density, water quality parameters, etc. During the session, participants will come to understand the basics of GIS, the history of FieldScope, and its unique educational features. We will spend the majority of the time exploring specific tools for analyzing authentic data, the different types of layers that make FieldScope powerful in its educational and research capacities, and examining various questions that can be addressed in a classroom or citizen science setting. We'll conclude the hands-on portion by sharing what was learned and how they were able to make meaning from the myriad of ways that data can be displayed.

Interventions for visual field defects in patients with stroke.

PubMed

Pollock, Alex; Hazelton, Christine; Henderson, Clair A; Angilley, Jayne; Dhillon, Baljean; Langhorne, Peter; Livingstone, Katrina; Munro, Frank A; Orr, Heather; Rowe, Fiona J; Shahani, Uma

2011-10-05

Visual field defects are estimated to affect 20% to 57% of people who have had a stroke. Visual field defects can affect functional ability in activities of daily living (commonly affecting mobility, reading and driving), quality of life, ability to participate in rehabilitation, and depression, anxiety and social isolation following stroke. There are many interventions for visual field defects, which are proposed to work by restoring the visual field (restitution); compensating for the visual field defect by changing behaviour or activity (compensation); substituting for the visual field defect by using a device or extraneous modification (substitution); or ensuring appropriate diagnosis, referral and treatment prescription through standardised assessment or screening, or both. To determine the effects of interventions for people with visual field defects after stroke. We searched the Cochrane Stroke Group Trials Register (February 2011), the Cochrane Eyes and Vision Group Trials Register (December 2009) and nine electronic bibliographic databases including CENTRAL (The Cochrane Library 2009, Issue 4), MEDLINE (1950 to December 2009), EMBASE (1980 to December 2009), CINAHL (1982 to December 2009), AMED (1985 to December 2009), and PsycINFO (1967 to December 2009). We also searched reference lists and trials registers, handsearched journals and conference proceedings and contacted experts. Randomised trials in adults after stroke, where the intervention was specifically targeted at improving the visual field defect or improving the ability of the participant to cope with the visual field loss. The primary outcome was functional ability in activities of daily living and secondary outcomes included functional ability in extended activities of daily living, reading ability, visual field measures, balance, falls, depression and anxiety, discharge destination or residence after stroke, quality of life and social isolation, visual scanning, adverse events and death. Two review authors independently screened abstracts, extracted data and appraised trials. We undertook an assessment of methodological quality for allocation concealment, blinding of outcome assessors, method of dealing with missing data, and other potential sources of bias. Thirteen studies (344 randomised participants, 285 of whom were participants with stroke) met the inclusion criteria for this review. However, only six of these studies compared the effect of an intervention with a placebo, control or no treatment group and were included in comparisons within this review. Four studies compared the effect of scanning (compensatory) training with a control or placebo intervention. Meta-analysis demonstrated that scanning training is more effective than control or placebo at improving reading ability (three studies, 129 participants; mean difference (MD) 3.24, 95% confidence interval (CI) 0.84 to 5.59) and visual scanning (three studies, 129 participants; MD 18.84, 95% CI 12.01 to 25.66) but that scanning may not improve visual field outcomes (two studies, 110 participants; MD -0.70, 95% CI -2.28 to 0.88). There were insufficient data to enable generalised conclusions to be made about the effectiveness of scanning training relative to control or placebo for the primary outcome of activities of daily living (one study, 33 participants). Only one study (19 participants) compared the effect of a restitutive intervention with a control or placebo intervention and only one study (39 participants) compared the effect of a substitutive intervention with a control or placebo intervention. There is limited evidence which supports the use of compensatory scanning training for patients with visual field defects (and possibly co-existing visual neglect) to improve scanning and reading outcomes. There is insufficient evidence to reach a conclusion about the impact of compensatory scanning training on functional activities of daily living. There is insufficient evidence to reach generalised conclusions about the benefits of visual restitution training (VRT) (restitutive intervention) or prisms (substitutive intervention) for patients with visual field defects after stroke.

Multidimensional structured data visualization method and apparatus, text visualization method and apparatus, method and apparatus for visualizing and graphically navigating the world wide web, method and apparatus for visualizing hierarchies

DOEpatents

Risch, John S [Kennewick, WA; Dowson, Scott T [West Richland, WA; Hart, Michelle L [Richland, WA; Hatley, Wes L [Kennewick, WA

2008-05-13

A method of displaying correlations among information objects comprises receiving a query against a database; obtaining a query result set; and generating a visualization representing the components of the result set, the visualization including one of a plane and line to represent a data field, nodes representing data values, and links showing correlations among fields and values. Other visualization methods and apparatus are disclosed.