The Effect of "Read-Aloud" as a Test Accommodation for Students with Visual Impairments in South Korea

ERIC Educational Resources Information Center

Kim, Jung Sook

2012-01-01

Arguing the issue of fairness and the additional advantage for test takers with visual impairments, some professionals have expressed negative attitudes toward test accommodation. However, researchers have found that the validity of test accommodations increases when the test scores of students who need a particular accommodation increases, while…

Visual efficiency among teenaged athletes and non-athletes

PubMed Central

Omar, Rokiah; Kuan, Yau Meng; Zuhairi, Nurul Atikah; Manan, Faudziah Abd; Knight, Victor Feizal

2017-01-01

AIM To compare visual efficiency, specifically accom-modation, vergence, and oculomotor functions among athletes and non-athletes. METHODS A cross-sectional study on sports vision screening was used to evaluate the visual skills of 214 elementary students (107 athletes, 107 non-athletes), aged between 13 and 16y. The visual screening assessed visual parameters such as ocular motor alignment, accommodation, and vergence functions. RESULTS Mean visual parameters were compared between age-group matched athletes (mean age 14.82±0.98y) and non-athletes (mean age 15.00±1.04y). The refractive errors of all participants were corrected to maximal attainable best corrected visual acuity of logMAR 0.0. Accommodation function assessment evaluated amplitude of accommodation and accommodation facility. Vergence functions measured the near point of convergence, vergence facility, and distance fusional vergence at break and recovery point. Ocular motor alignment was not statistically significant between both groups. Athletes had a statistically significant amplitude of accommodation for both the right eye (t=2.30, P=0.02) and the left eye (t=1.99, P=0.05). Conversely, non-athletes had better accommodation facility (t=-2.54, P=0.01) and near point of convergence (t=4.39, P<0.001) when compared to athletes. Vergence facility was found to be better among athletes (t=2.47, P=0.01). Nevertheless, non-athletes were significantly better for both distance negative and positive fusional vergence. CONCLUSION Although the findings are still inconclusive as to whether athletes had superior visual skills as compared to non-athletes, it remains important to identify and elucidate the key visual skills needed by athletes in order for them to achieve higher performance in their sports. PMID:28944208

Visual accommodation trainer-tester

NASA Technical Reports Server (NTRS)

Randle, R. J., Jr. (Inventor)

1983-01-01

An apparatus for training of the human visual accommodation system is presented, specifically, useful for training a person to volitionally control his focus to his far point (normaly infinity) from a position of myopia due to functional causes. The functional causes could be due, for example, to a behavioral accommodative spasm or the effects of an empty field. The device may also be used to measure accommodation, the accommodation resting position and the near and far points of vision.

Accommodative intraocular lens versus standard monofocal intraocular lens implantation in cataract surgery.

PubMed

Ong, Hon Shing; Evans, Jennifer R; Allan, Bruce D S

2014-05-01

Following cataract surgery and intraocular lens (IOL) implantation, loss of accommodation or postoperative presbyopia occurs and remains a challenge. Standard monofocal IOLs correct only distance vision; patients require spectacles for near vision. Accommodative IOLs have been designed to overcome loss of accommodation after cataract surgery. To define (a) the extent to which accommodative IOLs improve unaided near visual function, in comparison with monofocal IOLs; (b) the extent of compromise to unaided distance visual acuity; c) whether a higher rate of additional complications is associated the use of accommodative IOLs. We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2013, Issue 9), Ovid MEDLINE, Ovid MEDLINE in-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily Update, Ovid OLDMEDLINE (January 1946 to October 2013), EMBASE (January 1980 to October 2013), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to October 2013), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrial.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 10 October 2013. We include randomised controlled trials (RCTs) which compared implantation of accommodative IOLs to implantation of monofocal IOLs in cataract surgery. Two authors independently screened search results, assessed risk of bias and extracted data. All included trials used the 1CU accommodative IOL (HumanOptics, Erlangen, Germany) for their intervention group. One trial had an additional arm with the AT-45 Crystalens accommodative IOL (Eyeonics Vision). We performed a separate analysis comparing 1CU and AT-45 IOL. We included four RCTs, including 229 participants (256 eyes), conducted in Germany, Italy and the UK. The age range of participants was 21 to 87 years. All studies included people who had bilateral cataracts with no pre-existing ocular pathologies. We judged all studies to be at high risk of performance bias. We graded two studies with high risk of detection bias and one study with high risk of selection bias.Participants who received the accommodative IOLs achieved better distance-corrected near visual acuity (DCNVA) at six months (mean difference (MD) -3.10 Jaeger units; 95% confidence intervals (CI) -3.36 to -2.83, 2 studies, 106 people, 136 eyes, moderate quality evidence). Better DCNVA was seen in the accommodative lens group at 12 to 18 months in the three trials that reported this time point but considerable heterogeneity of effect was seen, ranging from 1.3 (95% CI 0.98 to 1.68; 20 people, 40 eyes) to 6 (95% CI 4.15 to 7.85; 51 people, 51 eyes) Jaeger units and 0.12 (95% CI 0.05 to 0.19; 40 people, binocular) logMAR improvement (low quality evidence). The relative effect of the lenses on corrected distant visual acuity (CDVA) was less certain. At six months there was a standardised mean difference of -0.04 standard deviations (95% CI -0.37 to 0.30, 2 studies, 106 people, 136 eyes, low quality evidence). At long-term follow-up there was heterogeneity of effect with 18-month data in two studies showing that CDVA was better in the monofocal group (MD 0.12 logMAR; 95% CI 0.07 to 0.16, 2 studies, 70 people,100 eyes) and one study which reported data at 12 months finding similar CDVA in the two groups (-0.02 logMAR units, 95% CI -0.06 to 0.02, 51 people) (low quality evidence).The relative effect of the lenses on reading speed and spectacle independence was uncertain, The average reading speed was 11.6 words per minute more in the accommodative lens group but the 95% confidence intervals ranged from 12.2 words less to 35.4 words more (1 study, 40 people, low quality evidence). People with accommodative lenses were more likely to be spectacle-independent but the estimate was very uncertain (risk ratio (RR) 8.18; 95% CI 0.47 to 142.62, 1 study, 40 people, very low quality evidence).More cases of posterior capsule opacification (PCO) were seen in accommodative lenses but the effect of the lenses on PCO was uncertain (Peto odds ratio (OR) 2.12; 95% CI 0.45 to 10.02, 91 people, 2 studies, low quality evidence). People in the accommodative lens group were more likely to require laser capsulotomy (Peto OR 7.96; 95% CI 2.49 to 25.45, 2 studies, 60 people, 80 eyes, low quality evidence). Glare was reported less frequently with accommodative lenses but the relative effect of the lenses on glare was uncertain (RR any glare 0.78; 95% CI 0.32 to 1.90, 1 study, 40 people, and RR moderate/severe glare 0.45; 95% CI 0.04 to 4.60, low quality evidence). There is moderate-quality evidence that study participants who received accommodative IOLs had a small gain in near visual acuity after six months. There is some evidence that distance visual acuity with accommodative lenses may be worse after 12 months but due to low quality of evidence and heterogeneity of effect, the evidence for this is not clear-cut. People receiving accommodative lenses had more PCO which may be associated with poorer distance vision. However, the effect of the lenses on PCO was uncertain.Further research is required to improve the understanding of how accommodative IOLs may affect near visual function, and whether they provide any durable gains. Additional trials, with longer follow-up, comparing different accommodative IOLs, multifocal IOLs and monofocal IOLs, would help map out their relative efficacy, and associated late complications. Research is needed on control over capsular fibrosis postimplantation.Risks of bias, heterogeneity of outcome measures and study designs used, and the dominance of one design of accommodative lens in existing trials (the HumanOptics 1CU) mean that these results should be interpreted with caution. They may not be applicable to other accommodative IOL designs.

Technique and cue selection for graphical presentation of generic hyperdimensional data

NASA Astrophysics Data System (ADS)

Howard, Lee M.; Burton, Robert P.

2013-12-01

Several presentation techniques have been created for visualization of data with more than three variables. Packages have been written, each of which implements a subset of these techniques. However, these packages generally fail to provide all the features needed by the user during the visualization process. Further, packages generally limit support for presentation techniques to a few techniques. A new package called Petrichor accommodates all necessary and useful features together in one system. Any presentation technique may be added easily through an extensible plugin system. Features are supported by a user interface that allows easy interaction with data. Annotations allow users to mark up visualizations and share information with others. By providing a hyperdimensional graphics package that easily accommodates presentation techniques and includes a complete set of features, including those that are rarely or never supported elsewhere, the user is provided with a tool that facilitates improved interaction with multivariate data to extract and disseminate information.

Diurnal rhythms of visual accommodation and blink responses - Implication for flight-deck visual standards

NASA Technical Reports Server (NTRS)

Murphy, M. R.; Randle, R. J.; Williams, B. A.

1977-01-01

Possible 24-h variations in accommodation responses were investigated. A recently developed servo-controlled optometer and focus stimulator were used to obtain monocular accommodation response data on four college-age subjects. No 24-h rhythm in accommodation was shown. Heart rate and blink rate also were measured and periodicity analysis showed a mean 24-h rhythm for both; however, blink rate periodograms were significant for only two of the four subjects. Thus, with the qualifications that college students were tested instead of pilots and that they performed monocular laboratory tasks instead of binocular flight-deck tasks, it is concluded that 24-h rhythms in accommodation responses need not be considered in setting visual standards for flight-deck tasks.

The Effect of Visual-Chunking-Representation Accommodation on Geometry Testing for Students with Math Disabilities

ERIC Educational Resources Information Center

Zhang, Dake; Ding, Yi; Stegall, Joanna; Mo, Lei

2012-01-01

Students who struggle with learning mathematics often have difficulties with geometry problem solving, which requires strong visual imagery skills. These difficulties have been correlated with deficiencies in visual working memory. Cognitive psychology has shown that chunking of visual items accommodates students' working memory deficits. This…

Short-term adaptation of accommodation, accommodative vergence and disparity vergence facility.

PubMed

Maxwell, James; Tong, Jianliang; Schor, Clifton M

2012-06-01

Previous studies have found that subjects can increase the velocity of accommodation using visual exercises such as pencil push ups, flippers, Brock strings and the like and myriad papers have shown improvement in accommodation facility (speed) and sufficiency (amplitude) using subjective tests following vision training but few have objectively measured accommodation before and after training in either normal subjects or in patients diagnosed with accommodative infacility (abnormally slow dynamics). Accommodation is driven either directly by blur or indirectly by way of neural crosslinks from the vergence system. Until now, no study has objectively measured both accommodation and accommodative-vergence before and after vision training and the role vergence might play in modifying the speed of accommodation. In the present study, accommodation and accommodative-vergence were measured with a Purkinje Eye Tracker/optometer before and after normal subjects trained in a flipper-like task in which the stimulus stepped between 0 and 2.5 diopters and back for over 200 cycles. Most subjects increased their speed of accommodation as well as their speed of accommodative vergence. Accommodative vergence led the accommodation response by approximately 77 ms before training and 100 ms after training and the vergence lead was most prominent in subjects with high accommodation and vergence velocities and the vergence leads tended to increase in conjunction with increases in accommodation velocity. We surmise that volitional vergence may help increase accommodation velocity by way of vergence-accommodation cross links. Copyright © 2012 Elsevier Ltd. All rights reserved.

Short-Term Adaptation of Accommodation, Accommodative Vergence and Disparity Vergence Facility

PubMed Central

Maxwell, James; Tong, Jianliang; Schor, Clifton M.

2012-01-01

Previous studies have found that subjects can increase the velocity of accommodation using visual exercises such as pencil push ups, flippers, Brock strings and the like and myriad papers have shown improvement in accommodation facility (speed) and sufficiency (amplitude) using subjective tests following vision training but few have objectively measured accommodation before and after training in either normal subjects or in patients diagnosed with accommodative infacility (abnormally slow dynamics). Accommodation is driven either directly by blur or indirectly by way of neural crosslinks from the vergence system. Until now, no study has objectively measured both accommodation and accommodative-vergence before and after vision training and the role vergence might play in modifying the speed of accommodation. In the present study, accommodation and accommodative-vergence were measured with a Purkinje Eye Tracker/Optometer before and after normal subjects trained in a flipper-like task in which the stimulus stepped between 0 and 2.5 diopters and back for over 200 cycles. Most subjects increased their speed of accommodation as well as their speed of accommodative vergence. Accommodative vergence led the accommodation response by approximately 77 msec before training and 100 msec after training and the vergence lead was most prominent in subjects with high accommodation and vergence velocities and the vergence leads tended to increase in conjunction with increases in accommodation velocity. We surmise that volitional vergence may help increase accommodation velocity by way of vergence-accommodation cross links. PMID:22480879

Yellow filters can improve magnocellular function: motion sensitivity, convergence, accommodation, and reading.

PubMed

Ray, N J; Fowler, S; Stein, J F

2005-04-01

The magnocellular system plays an important role in visual motion processing, controlling vergence eye movements, and in reading. Yellow filters may boost magnocellular activity by eliminating inhibitory blue input to this pathway. It was found that wearing yellow filters increased motion sensitivity, convergence, and accommodation in many children with reading difficulties, both immediately and after three months using the filters. Motion sensitivity was not increased using control neutral density filters. Moreover, reading-impaired children showed significant gains in reading ability after three months wearing the filters compared with those who had used a placebo. It was concluded that yellow filters can improve magnocellular function permanently. Hence, they should be considered as an alternative to corrective lenses, prisms, or exercises for treating poor convergence and accommodation, and also as an aid for children with reading problems.

Clinical evaluation of accommodation and ocular surface stability relavant to visual asthenopia with 3D displays

PubMed Central

2014-01-01

Background To validate the association between accommodation and visual asthenopia by measuring objective accommodative amplitude with the Optical Quality Analysis System (OQAS®, Visiometrics, Terrassa, Spain), and to investigate associations among accommodation, ocular surface instability, and visual asthenopia while viewing 3D displays. Methods Fifteen normal adults without any ocular disease or surgical history watched the same 3D and 2D displays for 30 minutes. Accommodative ability, ocular protection index (OPI), and total ocular symptom scores were evaluated before and after viewing the 3D and 2D displays. Accommodative ability was evaluated by the near point of accommodation (NPA) and OQAS to ensure reliability. The OPI was calculated by dividing the tear breakup time (TBUT) by the interblink interval (IBI). The changes in accommodative ability, OPI, and total ocular symptom scores after viewing 3D and 2D displays were evaluated. Results Accommodative ability evaluated by NPA and OQAS, OPI, and total ocular symptom scores changed significantly after 3D viewing (p = 0.005, 0.003, 0.006, and 0.003, respectively), but yielded no difference after 2D viewing. The objective measurement by OQAS verified the decrease of accommodative ability while viewing 3D displays. The change of NPA, OPI, and total ocular symptom scores after 3D viewing had a significant correlation (p < 0.05), implying direct associations among these factors. Conclusions The decrease of accommodative ability after 3D viewing was validated by both subjective and objective methods in our study. Further, the deterioration of accommodative ability and ocular surface stability may be causative factors of visual asthenopia in individuals viewing 3D displays. PMID:24612686

Effects of visual imagery on the accommodation response

NASA Technical Reports Server (NTRS)

Malmstrom, F. V.; Randle, R. J.

1976-01-01

Twenty-seven naive male subjects were tested to determine whether they could effect appropriate accommodation changes in an empty field by 'thinking near' and 'thinking far'. Evidence indicated that naive subjects could effect significant and appropriate accommodation changes, but only about a steady-state value of 1.0 diopter. Additionally, the data support the hypothesis that the resting state of accommodation is not at the visual far point, but, rather, at about 1.0 diopter.

Ocular Aberrations Across the Visual Field During Accommodation

NASA Astrophysics Data System (ADS)

Liu, Tao

Myopia is classically defined as a mismatch between the optical power of the relaxed eye and its dioptric length. This definition is entirely foveocentric without concern for the contributions of peripheral refractive errors to myopia development. Long periods of steady near-work was considered to cause myopia development due to inadequate accommodation. Consequently, not only the on-axis optical features but also off-axis ones should be probed to gain insight about myopia progression. Moreover, these features need to be understood not only for the relaxed eye, but also for the accommodating eye. To acquire complete data set, a custom-built Indiana Scanning Aberrometer for Wavefront (I SAW) was developed to measure wavefront aberration along 37 line-of-sights at 8 different accommodation states in the central 30 degree visual field. We found that ocular refractive state changed uniformly over the central visual field as the eye accommodates up to 6D, and the accuracy of accommodation across the central visual field is similar to that measured in the fovea. No systematic difference between emmetropic and myopic eyes was evident. Then, a linear vector-summation rule for axial and oblique astigmatism was found to account for their interaction over the central visual field. Using this combination rule, our experimental evidence revealed no systematic effect of accommodation on axial or oblique astigmatism for two adult populations. The axial and oblique astigmatism of the whole eye is less than for the cornea alone, indicating a compensatory role for internal optics at all accommodative states. This compensation mechanism was further validated theoretically with schematic eye model. Lastly, we developed a hybrid method yielding customized eye models that accurately reproduce the empirical measurements and reasonably represent the anatomical structure, thus providing a mechanistic explanation for the changes in the eye's aberration structure that occur over the central visual field during accommodation.

Synthesis of Available Accommodations for Students with Visual Impairments on Standardized Assessments

ERIC Educational Resources Information Center

Smith, Derrick W.; Amato, Sheila

2012-01-01

Because of the mandates found in the Individuals with Disabilities Education Act that specifically focus on assessment, most states have developed a set of policies that focus on the types of accommodations that can be provided to students with disabilities. Students with visual impairments require a unique set of accommodations. Braille and large…

Visual functions in amblyopia as determinants of response to treatment.

PubMed

Singh, Vinita; Agrawal, Siddharth

2013-01-01

To describe the visual functions in amblyopia as determinants of response to treatment. Sixty-nine patients with unilateral and bilateral amblyopia (114 amblyopic eyes) 3 to 15 years old (mean age: 8.80 ± 2.9 years), 40 males (58%) and 29 females (42%), were included in this study. All patients were treated by conventional occlusion 6 hours per day for mild to moderate amblyopia (visual acuity 0.70 or better) and full-time for 4 weeks followed by 6 hours per day for severe amblyopia (visual acuity 0.8 or worse). During occlusion, near activities requiring hand-eye coordination were advised. The follow-up examination was done at 3 and 6 months. Improvement in visual acuity was evaluated on the logMAR chart and correlated with the visual functions. Statistical analysis was done using Wilcoxon rank sum test (Mann-Whitney U test) and Kruskal-Wallis analysis. There was a statistically significant association of poor contrast sensitivity with the grade of amblyopia (P < .001). The grade of amblyopia (P < .01), accommodation (P < .01), stereopsis (P = .01), and mesopic visual acuity (P < .03) were found to have a correlation with response to amblyopia therapy. The grade of amblyopia (initial visual acuity) and accommodation are strong determinants of response to amblyopia therapy, whereas stereopsis and mesopic visual acuity have some value as determinants. Copyright 2013, SLACK Incorporated.

Audible Image Description as an Accommodation in Statewide Assessments for Students with Visual and Print Disabilities

ERIC Educational Resources Information Center

Ferrell, Kay Alicyn; Correa-Torres, Silvia M.; Howell, Jennifer Johnson; Pearson, Robert; Carver, Wendy Morrow; Groll, Amy Spencer; Anthony, Tanni L.; Matthews, Deborah; Gould, Bryan; O'Connell, Trisha; Botsford, Kathryn D,; Dewald, Hong Phangia; Smyth, Catherine A.; Dewald, Aaron John

2017-01-01

Introduction:Although image description has been identified as an accommodation for presentations conducted in the classroom, only a few U.S. states have approved it for use in high-stakes assessments. This study examined the use of audible image description as an assessment accommodation for students with visual and print disabilities by…

Experimental study of visual accommodation

NASA Technical Reports Server (NTRS)

Cornsweet, T. N.; Crane, H. D.

1972-01-01

A summary report of a research effort related to the human visual accommodation system is presented. A theoretical study of the accommodation system was made. Subsequent effort was aimed at the development of specialized instrumentation for experiments designed to lead to understanding the nature of the control system in human accommodation. The necessary instrumentation consisted primarily of: (1) an automatic optometer to measure the state of eye focus, (2) a focus stimulator device to control the apparent optical distance to any target, and (3) a two-dimensional eye tracker. The concepts and designs of the first two instruments have been published in the open literature, but this report contains the first detailed treatment of the Purkinje eye tracker developed under this program. The report also discusses an accommodation lag model to explain the ability of the eye to apparently know the polarity of focus error even though the blur on the retina is to a first-approximation an even function. The interaction of the accommodation and eye movement systems is also discussed, as is the ability to train the visual accommodation system to a surprisingly responsive condition in only a few hours of training.

Accommodative performance for chromatic displays.

PubMed

Lovasik, J V; Kergoat, H

1988-01-01

Over the past few years, video display units (VDUs) have been incorporated into many varieties of workplaces and occupational demands. The success of electro-optical displays in facilitating and improving job performance has spawned interest in extracting further advantage from VDUs by incorporating colour coding into such communication systems. However, concerns have been raised about the effect of chromatic stimuli on the visual comfort and task efficiency, because of the chromatic aberration inherent in the optics of the human eye. In this study, we used a computer aided laser speckle optometer system to measure the accommodative responses to brightness-matched chromatic letters displayed on a high-resolution RGB monitor. Twenty, visually normal, paid volunteers in a 22-35 year age category served as subjects. Stimuli were 14, 21, 28 minutes of arc letters presented in a 'monochromatic' (white, red, green or blue, on a black background) or 'multichromatic' (blue-red, blue-green, red-green, foreground-background combinations) mode at 40 and 80 cm viewing distances. The results demonstrated that while the accommodative responses were strongly influenced by the foreground-background colour combination, the group-averaged dioptric difference across colours was relatively small. Further, accommodative responses were not guided in any systematic fashion by the size of letters presented for fixation. Implications of these findings for display designs are discussed.

Accommodating Elementary Students' Learning Styles.

ERIC Educational Resources Information Center

Wallace, James

1995-01-01

Examines the perceptual learning style preferences of sixth- and seventh-grade students in the Philippines. Finds that the visual modality was the most preferred and the auditory modality was the least preferred. Offers suggestions for accommodating visual, tactile, and kinesthetic preferences. (RS)

Longitudinal changes in oculomotor function in young adults with mild traumatic brain injury in Sweden: an exploratory prospective observational study.

PubMed

Matuseviciene, Giedre; Johansson, Jan; Möller, Marika; Godbolt, Alison K; Pansell, Tony; Deboussard, Catharina Nygren

2018-02-03

To assess (1) whether visual disturbances can be demonstrated with objective measures more often in patients with mild traumatic brain injury (mTBI) than in orthopaedic controls and non-injured controls, (2) whether such objectively demonstrated disturbances change over time and (3) whether self-reported visual symptoms after mTBI correlate with objectively measurable changes in visuomotor performance. A prospective, controlled, observational study, with assessments planned 7-10 and 75-100 days after injury. Emergency department of a general hospital in Sweden. 15 patients with mTBI, 15 patients with minor orthopaedic injury, 15 non-injured controls, aged 18-40 years. Visual examination, including assessment of visual acuity, accommodation, eye alignment, saccades and stereoacuity. Symptom assessment using Convergence Insufficiency Symptoms Survey (CISS) and Rivermead PostConcussion Symptoms Questionnaire. Assessments were performed 4-13 and 81-322 days after injury (extended time frames for logistical reasons). No statistically significant difference was found between the mTBI and control groups regarding saccade performance and stereoacuity at any time point. The accommodative amplitude was significantly lower in the mTBI group compared with non-injured controls at baseline. 6 out of 13 patients with mTBI had accommodative insufficiency at follow-up. Near point of convergence in the mTBI group was receded at baseline and improved statistically significantly at follow-up. At baseline, patients with mTBI had significantly higher CISS score than orthopaedic and non-injured controls. For patients with mTBI, the CISS score correlated with fusional vergence. There were some transient measurable visual changes regarding convergence in patients with mTBI during the subacute period after the injury. Our findings of persistence of accommodative insufficiency in a considerable proportion of patients with mTBI suggest that this visual function should not be overlooked in clinical assessment. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Subjective evaluation of two stereoscopic imaging systems exploiting visual attention to improve 3D quality of experience

NASA Astrophysics Data System (ADS)

Hanhart, Philippe; Ebrahimi, Touradj

2014-03-01

Crosstalk and vergence-accommodation rivalry negatively impact the quality of experience (QoE) provided by stereoscopic displays. However, exploiting visual attention and adapting the 3D rendering process on the fly can reduce these drawbacks. In this paper, we propose and evaluate two different approaches that exploit visual attention to improve 3D QoE on stereoscopic displays: an offline system, which uses a saliency map to predict gaze position, and an online system, which uses a remote eye tracking system to measure real time gaze positions. The gaze points were used in conjunction with the disparity map to extract the disparity of the object-of-interest. Horizontal image translation was performed to bring the fixated object on the screen plane. The user preference between standard 3D mode and the two proposed systems was evaluated through a subjective evaluation. Results show that exploiting visual attention significantly improves image quality and visual comfort, with a slight advantage for real time gaze determination. Depth quality is also improved, but the difference is not significant.

The visual accommodation response during concurrent mental activity

NASA Technical Reports Server (NTRS)

Malmstrom, F. V.; Randle, R. J.; Bendix, J. S.; Weber, R. J.

1980-01-01

The direction and magnitude of the human visual accommodation response during concurrent mental activity are investigated. Subject focusing responses to targets at distances of 0.0 D, 3.0 D and an indeterminate distance were monitored by means of an optometer during the performance of a backwards counting task and a visual imagery task (thinking near and thinking far). In both experiments a shift in accommodation towards the visual far point is observed particularly for the near target, which increases with the duration of the task. The results can be interpreted in terms of both the capacity model of Kahneman (1973) and the autonomic arousal model of Hess and Polt (1964), and are not inconsistent with the possibility of an intermediate resting position.

Circadian rhythms of visual accommodation responses and physiological correlations.

NASA Technical Reports Server (NTRS)

Murphy, M. R.; Randle, R. J.; Williams, B. A.

1972-01-01

Use of a recently developed servocontrolled infrared optometer to continuously record the state of monocular focus while subjects viewed a visual target for which the stimulus to focus was systematically varied. Calculated parameters form recorded data - e.g., speeds of accommodation to approaching and receding targets, magnitude of accommodation to step changes in target distance, and amplitude and phase lag of response to sinusoidally varying stimuli were submitted to periodicity analyses. Ear canal temperature (ECT) and heart rate (HR) rhythms were also recorded for physiological correlation with accommodation rhythms. HR demonstrated a 24-hr rhythm, but ECT data did not.

Visual-Accommodation Trainer/Tester

NASA Technical Reports Server (NTRS)

Randle, Robert J., Jr.

1986-01-01

Ophthalmic instrument tests and helps develop focusing ability. Movable stage on a fixed base permits adjustment of effective target position as perceived by subject. Various apertures used to perform tests and training procedures. Ophthalmic instrument provides four functions: it measures visual near and far points; provides focus stimulus in vision research; measures visual-accommodation resting position; can be used to train for volitional control of person's focus response.

The Dark Focus of Visual Accommodation: Its Existence, Its Measurement, Its Effects

DTIC Science & Technology

1979-11-01

DaVinci Jepicted the lens as a light focusing agent, but went virtually unnoticed as there was no available means to mass-produce his drawings (see...the Bates method of treating myopia in wni2n suggestion and relaxation techniques apparently yielded improved acuity. Working with hypnosis ,. he found...1’ Acute myopes had the greatest improvement during hypnosis . 2) Out ’f 1 49 nypnosis, acuity improvement transferred, but no refractive changes

Trying to see, failing to focus: near visual impairment in Down syndrome

PubMed Central

Doyle, Lesley; Saunders, Kathryn J.; Little, Julie-Anne

2016-01-01

The majority of individuals with Down syndrome (DS) do not exhibit accurate accommodation, with the aetiology of this deficit unknown. This study examines the mechanism underlying hypoaccommodation in DS by simultaneously investigating the ‘near triad’ – accommodation, vergence and pupillary response. An objective photorefraction system measured accommodation, pupil size and gaze position (vergence) under binocular conditions while participants viewed an animated movie at 50, 33, 25 and 20 cm. Participants were aged 6–16 years (DS = 41, controls = 76). Measures were obtained from 59% of participants with DS and 99% of controls. Accommodative response was significantly less in DS (p < 0.001) and greater accommodative deficits were associated with worsening visual acuity (p = 0.02). Vergence responses were as accurate in DS as in controls (p = 0.90). Habitual pupil diameter did not differ between groups (p = 0.24) but reduced significantly with increasing accommodative demand in both participants with and without DS (p < 0.0001). This study is the first to report simultaneous binocular measurement of the near triad in DS demonstrating that hypoaccommodation is linked to poor visual acuity. Vergence responses were accurate indicating that hypoaccommodation cannot be dismissed as a failure to visually engage with near targets, but rather is a consequence of underlying neurological or physiological deficits. PMID:26847360

Temporal Co-Variation between Eye Lens Accommodation and Trapezius Muscle Activity during a Dynamic Near-Far Visual Task

PubMed Central

Zetterberg, Camilla; Richter, Hans O.; Forsman, Mikael

2015-01-01

Near work is associated with increased activity in the neck and shoulder muscles, but the underlying mechanism is still unknown. This study was designed to determine whether a dynamic change in focus, alternating between a nearby and a more distant visual target, produces a direct parallel change in trapezius muscle activity. Fourteen healthy controls and 12 patients with a history of visual and neck/shoulder symptoms performed a Near-Far visual task under three different viewing conditions; one neutral condition with no trial lenses, one condition with negative trial lenses to create increased accommodation, and one condition with positive trial lenses to create decreased accommodation. Eye lens accommodation and trapezius muscle activity were continuously recorded. The trapezius muscle activity was significantly higher during Near than during Far focusing periods for both groups within the neutral viewing condition, and there was a significant co-variation in time between accommodation and trapezius muscle activity within the neutral and positive viewing conditions for the control group. In conclusion, these results reveal a connection between Near focusing and increased muscle activity during dynamic changes in focus between a nearby and a far target. A direct link, from the accommodation/vergence system to the trapezius muscles cannot be ruled out, but the connection may also be explained by an increased need for eye-neck (head) stabilization when focusing on a nearby target as compared to a more distant target. PMID:25961299

Temporal Co-Variation between Eye Lens Accommodation and Trapezius Muscle Activity during a Dynamic Near-Far Visual Task.

PubMed

Zetterberg, Camilla; Richter, Hans O; Forsman, Mikael

2015-01-01

Near work is associated with increased activity in the neck and shoulder muscles, but the underlying mechanism is still unknown. This study was designed to determine whether a dynamic change in focus, alternating between a nearby and a more distant visual target, produces a direct parallel change in trapezius muscle activity. Fourteen healthy controls and 12 patients with a history of visual and neck/shoulder symptoms performed a Near-Far visual task under three different viewing conditions; one neutral condition with no trial lenses, one condition with negative trial lenses to create increased accommodation, and one condition with positive trial lenses to create decreased accommodation. Eye lens accommodation and trapezius muscle activity were continuously recorded. The trapezius muscle activity was significantly higher during Near than during Far focusing periods for both groups within the neutral viewing condition, and there was a significant co-variation in time between accommodation and trapezius muscle activity within the neutral and positive viewing conditions for the control group. In conclusion, these results reveal a connection between Near focusing and increased muscle activity during dynamic changes in focus between a nearby and a far target. A direct link, from the accommodation/vergence system to the trapezius muscles cannot be ruled out, but the connection may also be explained by an increased need for eye-neck (head) stabilization when focusing on a nearby target as compared to a more distant target.

Effects of Age on Dynamic Accommodation

PubMed Central

Lockhart, Thurmon E.; Shi, Wen

2010-01-01

Visual accommodation plays a critical role in one’s visual perception and activities of daily living. Age-related accommodation loss poses an increased risk to older adults’ safety and independence. Although extensive effort has been made towards understanding the effect of age on steady-state accommodation, dynamic aspects of accommodation is still unknown. A study was therefore conducted to investigate age-related dynamic accommodative characteristics utilizing a modified autorefractor. Ten individuals from each of three age groups (i.e., younger group: 20 to 29 years old, middle-aged group: 40 to 49 years old, and older group: 60 to 69 years old) were recruited and their dynamic accommodation responses were examined. The laboratory experiment was designed to assess dynamic accommodation associated with an abrupt change from a constant far target (400 cm, 50 cd/m2) to a near target (70 cm, 100 cd/m2 or 20 cd/m2), which aimed to simulate car dashboard reading behavior while driving. The results of the study indicated that age and target intensity both had a significant impact on dynamic accommodation. These effects were attributed to both the age-related physiological limitation of the eye as well as to central neural processing delay. A method of measuring dynamic accommodation and the implications of the study are discussed. PMID:20582770

Performance Measurement and Accommodation: Students with Visual Impairments on Pennsylvania's Alternate Assessment

ERIC Educational Resources Information Center

Zebehazy, Kim T.; Zigmond, Naomi; Zimmerman, George J.

2012-01-01

Introduction: This study investigated the use of accommodations and the performance of students with visual impairments and severe cognitive disabilities on the Pennsylvania Alternate System of Assessment (PASA)yCoan alternate performance-based assessment. Methods: Differences in test scores on the most basic level (level A) of the PASA of 286…

Effect of visual target blurring on accommodation under distance viewing

NASA Astrophysics Data System (ADS)

Iwata, Yo; Handa, Tomoya; Ishikawa, Hitoshi

2018-04-01

Abstract Purpose To examine the effect of visual target blurring on accommodation. Methods We evaluated the objective refraction values when the visual target (asterisk; 8°) was changed from the state without Gaussian blur (15 s) to the state with Gaussian blur adapted [0(without blur) → 10, 0 → 50, 0 → 100: 15 s each]. Results In Gaussian blur 10, when blurring of the target occurred, refraction value did not change significantly. In Gaussian blur 50 and 100, when blurring of the target occurred, the refraction value became significantly myopic. Conclusion Blurring of the distant visual target results in intervention of accommodation.

Effects of magnification and visual accommodation on aimpoint estimation in simulated landings with real and virtual image displays

NASA Technical Reports Server (NTRS)

Randle, R. J.; Roscoe, S. N.; Petitt, J. C.

1980-01-01

Twenty professional pilots observed a computer-generated airport scene during simulated autopilot-coupled night landing approaches and at two points (20 sec and 10 sec before touchdown) judged whether the airplane would undershoot or overshoot the aimpoint. Visual accommodation was continuously measured using an automatic infrared optometer. Experimental variables included approach slope angle, display magnification, visual focus demand (using ophthalmic lenses), and presentation of the display as either a real (direct view) or a virtual (collimated) image. Aimpoint judgments shifted predictably with actual approach slope and display magnification. Both pilot judgments and measured accommodation interacted with focus demand with real-image displays but not with virtual-image displays. With either type of display, measured accommodation lagged far behind focus demand and was reliably less responsive to the virtual images. Pilot judgments shifted dramatically from an overwhelming perceived-overshoot bias 20 sec before touchdown to a reliable undershoot bias 10 sec later.

Counteracting the effects of mydriatics. Does it benefit the patient?

PubMed

Nelson, M E; Orton, H P

1987-04-01

The effect of 2% pilocarpine nitrate in countering mydriasis, cycloplegia, and change in visual acuity due to 0.5% tropicamide was studied in 23 healthy volunteers. There was no significant difference in the decrease in pupil size or the rate of return of accommodation between the eye that received pilocarpine and the control eye. The effect of tropicamide on visual acuity was slight. In four (17%) of 23 eyes that received pilocarpine, visual acuity was reduced to 6/36 or worse. It is suggested that the use of 2% pilocarpine in the attempted reversal of 0.5% tropicamide to improve a patient's vision is not helpful and may possibly be harmful.

Setting visual pre-placement testing in a technology manufacturing environment.

PubMed

Gowan, Nancy J

2014-01-01

Every day we use our eyes to perform activities of daily living and work. Aging changes as well as health conditions can impact an individual's visual function, making it more difficult to accurately perform work activities. Occupational therapists work closely with optometrists and employers to develop ways to accommodate for these changes so that the employee can continue to perform the work tasks. This manuscript outlines a case study of systematically developing visual demands analyses and pre-placement vision screening assessment protocols for individuals completing quality inspection positions. When the vision screening was completed, it was discovered that over 20% of the employees had visual deficits that were correctable. This screening process yielded improved quality results but also identification of previously undetected visual deficits. Further development of vision screening in the workplace is supported.

Visual accommodation and active pursuit of prey underwater in a plunge-diving bird: the Australasian gannet

PubMed Central

Machovsky-Capuska, Gabriel E.; Howland, Howard C.; Raubenheimer, David; Vaughn-Hirshorn, Robin; Würsig, Bernd; Hauber, Mark E.; Katzir, Gadi

2012-01-01

Australasian gannets (Morus serrator), like many other seabird species, locate pelagic prey from the air and perform rapid plunge dives for their capture. Prey are captured underwater either in the momentum (M) phase of the dive while descending through the water column, or the wing flapping (WF) phase while moving, using the wings for propulsion. Detection of prey from the air is clearly visually guided, but it remains unknown whether plunge diving birds also use vision in the underwater phase of the dive. Here we address the question of whether gannets are capable of visually accommodating in the transition from aerial to aquatic vision, and analyse underwater video footage for evidence that gannets use vision in the aquatic phases of hunting. Photokeratometry and infrared video photorefraction revealed that, immediately upon submergence of the head, gannet eyes accommodate and overcome the loss of greater than 45 D (dioptres) of corneal refractive power which occurs in the transition between air and water. Analyses of underwater video showed the highest prey capture rates during WF phase when gannets actively pursue individual fish, a behaviour that very likely involves visual guidance, following the transition after the plunge dive's M phase. This is to our knowledge the first demonstration of the capacity for visual accommodation underwater in a plunge diving bird while capturing submerged prey detected from the air. PMID:22874749

Do reading additions improve reading in pre-presbyopes with low vision?

PubMed

Alabdulkader, Balsam; Leat, Susan

2012-09-01

This study compared three different methods of determining a reading addition and the possible improvement on reading performance in children and young adults with low vision. Twenty-eight participants with low vision, aged 8 to 32 years, took part in the study. Reading additions were determined with (a) a modified Nott dynamic retinoscopy, (b) a subjective method, and (c) an age-based formula. Reading performance was assessed with MNREAD-style reading charts at 12.5 cm, with and without each reading addition in random order. Outcome measures were reading speed, critical print size, MNREAD threshold, and the area under the reading speed curve. For the whole group, there was no significant improvement in reading performance with any of the additions. When participants with normal accommodation at 12.5 cm were excluded, the area under the reading speed curve was significantly greater with all reading additions compared with no addition (p = 0.031, 0.028, and 0.028, respectively). Also, the reading acuity threshold was significantly better with all reading additions compared with no addition (p = 0.014, 0.030, and 0.036, respectively). Distance and near visual acuity, age, and contrast sensitivity did not predict improvement with a reading addition. All, but one, of the participants who showed a significant improvement in reading with an addition had reduced accommodation. A reading addition may improve reading performance for young people with low vision and should be considered as part of a low vision assessment, particularly when accommodation is reduced.

75 FR 82411 - Sunshine Act Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-30

... will be made available in alternate formats to accommodate visual and hearing impairments. Individuals who have a disability and need an accommodation to attend the meeting may notify Katherine Ward, at...

Visual Accommodation, the Mandelbaum Effect, and Apparent Size.

DTIC Science & Technology

1979-11-01

remarks can lead the designer of visual displays to inappropriate application of some so-called laws of vision. As Ogle (1950) has suggested the objective...SNS control of accommodation, discussing much of tne above literature, and presenting clinical, experimental , and pnarmacological evidence for his view...the mechanisms operates and how to evaluate the relevance of the experimental findings under varying conditions. P1. 7. 7 7 - Cogan (1937) reviewed

[The dependence of the range of fusion on some selected functions of the visual system. Part II: Accommodation and dominance].

PubMed

Adamek, Bogdan; Karczewicz, Danuta

2006-01-01

This present study is the continuation of Part I of the research into the range of fusion in which the difference between both eyeballs as far as convergent fusion is concerned was described. The phenomenon was called "visual unevenness of the range of convergent fusion". This part of the study is devoted to the analysis of the relationship between the unevenness of the fusion, ocular dominance and accommodation. A lower range of convergent fusion was observed in the dominant eye with the higher accommodation, In contrast, a higher range of fusion was observed in the not dominant eye with lower accommodation. The authors think that the phenomenon of ocular unevenness of the range of convergent fusion does not depend on the peripheral part of visual organ. In fact, it does seem to point out to a cortical process. The authors suggest that quantitative tests on amplitude of fusion should be carried out first on the first eye and then on the other. The results obtained from both eyes should be compared with each other.

Trapezius muscle activity increases during near work activity regardless of accommodation/vergence demand level.

PubMed

Richter, H O; Zetterberg, C; Forsman, M

2015-07-01

To investigate if trapezius muscle activity increases over time during visually demanding near work. The vision task consisted of sustained focusing on a contrast-varying black and white Gabor grating. Sixty-six participants with a median age of 38 (range 19-47) fixated the grating from a distance of 65 cm (1.5 D) during four counterbalanced 7-min periods: binocularly through -3.5 D lenses, and monocularly through -3.5 D, 0 D and +3.5 D. Accommodation, heart rate variability and trapezius muscle activity were recorded in parallel. General estimating equation analyses showed that trapezius muscle activity increased significantly over time in all four lens conditions. A concurrent effect of accommodation response on trapezius muscle activity was observed with the minus lenses irrespective of whether incongruence between accommodation and convergence was present or not. Trapezius muscle activity increased significantly over time during the near work task. The increase in muscle activity over time may be caused by an increased need of mental effort and visual attention to maintain performance during the visual tasks to counteract mental fatigue.

Neck pain brought into focus.

PubMed

Richter, Hans O

2014-01-01

A time honored dictum states that the eyes "lead the body", i.e., that the body typically adjusts its position to compensate for an impoverished retinal image (e.g., as due to optical blur, and/or inappropriately sized visual target). But only moderate or low level of evidence exists in support of this view. Inconclusive evidence does not, however, equal negative evidence. The accommodation/vergence system does exhibit signs of overload in contemporary working life, including eye discomfort, transient myopia, altered pattern of eye-lens oscillations, and associated phoria. Accommodation/vergence overload, caused by non-ergonomic near work, may also emerge as quickly as within one regular workday. Long-term musculoskeletal consequences of high accommodation/vergence demands have nevertheless not yet been studied in any detail. A research agenda which aims to provide multi-scientific evidence for eye-neck/shoulder interactions with public health implications and which also, in addition, study the eye-neck/shoulder mechanisms and elucidates the operating characteristics, should consequently be highly warranted. This new knowledge would be useful for physiotherapists, ergonomists and opticians, who in their profession treat patients experiencing vision- and musculoskeletal disorders. If both visual and the musculoskeletal aspects are given full and equal weight in the design and evaluation of work places, it is predicted to lead to an improved quality of life for the individual worker, and an enhanced productivity for the employer.

Effect of elimination of nitrogen and/or hypoxia or restricted visual environment on color vision and range of accommodation

NASA Technical Reports Server (NTRS)

Wolbarsht, M. L.; White, C. W.; Anderson, W. B., Jr.

1973-01-01

The effects upon range of accommodation and color vision of reduced atmospheric pressure, at partial and complete elimination of nitrogen, of hypoxia, and of exposure for varying periods of time to restricted visual environment, have been studied alone or in various combinations. Measurements were made on the electroretinogram, the electrooculogram, and the diameter of the retinal vessels as an indicator of blood flow to the retina at the time of total elimination of nitrogen. An objective method was used to test range of accommodation. In the color vision test the flicker colors of a Benham's top were matched with a colorimeter.

A novel experimental method for measuring vergence and accommodation responses to the main near visual cues in typical and atypical groups.

PubMed

Horwood, Anna M; Riddell, Patricia M

2009-01-01

Binocular disparity, blur, and proximal cues drive convergence and accommodation. Disparity is considered to be the main vergence cue and blur the main accommodation cue. We have developed a remote haploscopic photorefractor to measure simultaneous vergence and accommodation objectively in a wide range of participants of all ages while fixating targets at between 0.3 and 2 m. By separating the three main near cues, we can explore their relative weighting in three-, two-, one-, and zero-cue conditions. Disparity can be manipulated by remote occlusion; blur cues manipulated by using either a Gabor patch or a detailed picture target; looming cues by either scaling or not scaling target size with distance. In normal orthophoric, emmetropic, symptom-free, naive visually mature participants, disparity was by far the most significant cue to both vergence and accommodation. Accommodation responses dropped dramatically if disparity was not available. Blur only had a clinically significant effect when disparity was absent. Proximity had very little effect. There was considerable interparticipant variation. We predict that relative weighting of near cue use is likely to vary between clinical groups and present some individual cases as examples. We are using this naturalistic tool to research strabismus, vergence and accommodation development, and emmetropization.

A Novel Experimental Method for Measuring Vergence and Accommodation Responses to the Main Near Visual Cues in Typical and Atypical Groups

PubMed Central

Horwood, Anna M; Riddell, Patricia M

2015-01-01

Binocular disparity, blur and proximal cues drive convergence and accommodation. Disparity is considered to be the main vergence cue and blur the main accommodation cue. We have developed a remote haploscopic photorefractor to measure simultaneous vergence and accommodation objectively in a wide range of participants of all ages while fixating targets at between 0.3m and 2m. By separating the three main near cues we can explore their relative weighting in three, two, one and zero cue conditions. Disparity can be manipulated by remote occlusion; blur cues manipulated by using either a Gabor patch or a detailed picture target; looming cues by either scaling or not scaling target size with distance. In normal orthophoric, emmetropic, symptom-free, naive visually mature participants, disparity was by far the most significant cue to both vergence and accommodation. Accommodation responses dropped dramatically if disparity was not available. Blur only had a clinically significant effect when disparity was absent. Proximity had very little effect. There was considerable inter-participant variation. We predict that relative weighting of near cue use is likely to vary between clinical groups and present some individual cases as examples. We are using this naturalistic tool to research strabismus, vergence and accommodation development and emmetropisation. PMID:19301186

Data Driven Quality Improvement of Health Professions Education: Design and Development of CLUE - An Interactive Curriculum Data Visualization Tool.

PubMed

Canning, Claire Ann; Loe, Alan; Cockett, Kathryn Jane; Gagnon, Paul; Zary, Nabil

2017-01-01

Curriculum Mapping and dynamic visualization is quickly becoming an integral aspect of quality improvement in support of innovations which drive curriculum quality assurance processes in medical education. CLUE (Curriculum Explorer) a highly interactive, engaging and independent platform was developed to support curriculum transparency, enhance student engagement, and enable granular search and display. Reflecting a design based approach to meet the needs of the school's varied stakeholders, CLUE employs an iterative and reflective approach to drive the evolution of its platform, as it seeks to accommodate the ever-changing needs of our stakeholders in the fast pace world of medicine and medical education today. CLUE exists independent of institutional systems and in this way, is uniquely positioned to deliver a data driven quality improvement resource, easily adaptable for use by any member of our health care professions.

75 FR 32227 - Sunshine Act Meeting of the Board of Directors

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-07

... available in alternate formats to accommodate visual and hearing impairments. Individuals who have a disability and need an accommodation to attend the meeting may notify Katherine Ward at (202) 295-1500 or FR...

Magnitude of visual accommodation to a head-up display

NASA Technical Reports Server (NTRS)

Leitner, E. F.; Haines, R. F.

1981-01-01

The virtual image symbology of head-up displays (HUDs) is presented at optical infinity to the pilot. This design feature is intended to help pilots maintain visual focus distance at optical infinity. However, the accommodation response could be nearer than optical infinity, due to an individual's dark focus response. Accommodation responses were measured of two age groups of airline pilots to: (1) static symbology on a HUD; (2) a landing site background at optical infinity; (3) the combination of the HUD symbology and the landing site background; and (4) complete darkness. Results indicate that magnitude of accommodation to HUD symbology, with and without the background, is not significantly different from an infinity focus response for either age group. The dark focus response is significantly closer than optical infinity for the younger pilots, but not the older pilots, a finding consistent with previous research.

Variation of axial and oblique astigmatism with accommodation across the visual field

PubMed Central

Liu, Tao; Thibos, Larry N.

2017-01-01

In this study we investigated the impact of accommodation on axial and oblique astigmatism along 12 meridians of the central 30° of visual field and explored the compensation of corneal first-surface astigmatism by the remainder of the eye's optical system. Our experimental evidence revealed no systematic effect of accommodation on either axial or oblique astigmatism for two adult populations (myopic and emmetropic eyes). Although a few subjects exhibited systematic changes in axial astigmatism during accommodation, the dioptric value of these changes was much smaller than the amount of accommodation. For most subjects, axial and oblique astigmatism of the whole eye are both less than for the cornea alone, which indicates a compensatory role for internal optics at all accommodative states in both central and peripheral vision. A new method for determining the eye's optical axis based on visual field maps of oblique astigmatism revealed that, on average, the optical axis is 4.8° temporal and 0.39° superior to the foveal line-of-sight in object space, which agrees with previous results obtained by different methodologies and implies that foveal astigmatism includes a small amount of oblique astigmatism (0.06 D on average). Customized optical models of each eye revealed that oblique astigmatism of the corneal first surface is negligible along the pupillary axis for emmetropic and myopic eyes. Individual variation in the eye's optical axis is due in part to misalignment of the corneal and internal components that is consistent with tilting of the crystalline lens relative to the pupillary axis. PMID:28362902

Multifactor Determinants of Visual Accommodation as a Critical Intervening Variable in the Perception of Size and Distance: Phase I Report

DTIC Science & Technology

1997-11-01

Expanded subset of the illustration to clarify the locus of the off-axis end point of retinal stimulation for correct accommodation. 55 Figure...12c. Expanded illustration to clarify the locus of the off -axis end point of retinal stimulation for myopic accommodation. 55 Figure 12d...Expanded illustration to clarify the locus of the off -axis end point of retinal stimulation for hyperopic accommodation. 56 Figure 13. Simplified

Visual accommodation trainer-tester

NASA Technical Reports Server (NTRS)

Randle, Robert J. (Inventor)

1988-01-01

An apparatus for training the human visual accommodation system is described. Specifically, the apparatus is useful for training personnel to volitionally control focus to the far point (normally infinity) from a position of myopia due to functional causes. The functional causes could be due, for example, to a behavioral accommodative spasm or the effects of an empty field. The device may also be used to measure accommodation, the accommodation resting position and the near and far points of vision. The device comprises a number of optical elements arranged on a single optical axis. Several of the elements are arranged in order on a movable stage in fixed relationship to each other: a light source, a lens, a target, an aperture and/or a second lens. On a base and in fixed relationship to each other are eyepiece and third lens. A stage generates an image of the target and the stage is movable with respect to the base by means of a knob. The device is utilized for the various training and test functions by following a series of procedural steps, and interchanging the apertures as necessary for the selected procedure.

Visual Immersion for Cultural Understanding and Multimodal Literacy

ERIC Educational Resources Information Center

Smilan, Cathy

2017-01-01

When considering inclusive art curriculum that accommodates all learners, including English language learners, two distinct yet inseparable issues come to mind. The first is that English language learner students can use visual language and visual literacy skills inherent in visual arts curriculum to scaffold learning in and through the arts.…

Accommodating Technology in the Visual Literacy Classroom.

ERIC Educational Resources Information Center

Lloyd, Carla V.; Barnhurst, Kevin G.

The development of a visual literacy facility, the Creative Visual Lab, at the S. I. Newhouse School of Public Communications at Syracuse University (New York) is described. The facility was designed to provide students with the instruction that would develop their computer proficiency and visual sensitivity without being, in itself, completely…

Advocating for a Population-Specific Health Literacy for People With Visual Impairments.

PubMed

Harrison, Tracie; Lazard, Allison

2015-01-01

Health literacy, the ability to access, process, and understand health information, is enhanced by the visual senses among people who are typically sighted. Emotions, meaning, speed of knowledge transfer, level of attention, and degree of relevance are all manipulated by the visual design of health information when people can see. When consumers of health information are blind or visually impaired, they access, process, and understand their health information in a multitude of methods using a variety of accommodations depending upon their severity and type of impairment. They are taught, or they learn how, to accommodate their differences by using alternative sensory experiences and interpretations. In this article, we argue that due to the unique and powerful aspects of visual learning and due to the differences in knowledge creation when people are not visually oriented, health literacy must be considered a unique construct for people with visual impairment, which requires a distinctive theoretical basis for determining the impact of their mind-constructed representations of health.

75 FR 16188 - Sunshine Act Meetings of the Board of Directors and Five Committees of the Board

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-31

..., meeting notices will be made available in alternate formats to accommodate visual and hearing impairments. Individuals who have a disability and need an accommodation to attend the meeting may notify Katherine Ward...

Morphology and accommodative function of the vitreous zonule in human and monkey eyes.

PubMed

Lütjen-Drecoll, Elke; Kaufman, Paul L; Wasielewski, Rainer; Ting-Li, Lin; Croft, Mary Ann

2010-03-01

To explore the attachments of the posterior zonule and vitreous in relation to accommodation and presbyopia in monkeys and humans. Novel scanning electron microscopy (SEM) and ultrasound biomicroscopy (UBM) techniques were used to visualize the anterior, intermediate, and posterior vitreous zonule and their connections to the ciliary body, vitreous membrane, lens capsule, and ora serrata, and to characterize their age-related changes and correlate them with loss of accommodative forward movement of the ciliary body. alpha-Chymotrypsin was used focally to lyse the vitreous zonule and determine the effect on movement of the accommodative apparatus in monkeys. The vitreous attached to the peripheral lens capsule and the ora serrata directly. The pars plana zonule and the posterior tines of the anterior zonule were separated from the vitreous membrane except for strategically placed attachments, collectively termed the vitreous zonule, that may modulate and smooth the forward and backward movements of the entire system. Age-dependent changes in these relationships correlated significantly with loss of accommodative amplitude. Lysis of the intermediate vitreous zonule partially restored accommodative movement. The vitreous zonule system may help to smoothly translate to the lens the driving forces of accommodation and disaccommodation generated by the ciliary muscle, while maintaining visual focus and protecting the lens capsule and ora serrata from acute tractional forces. Stiffening of the vitreous zonular system may contribute to age-related loss of accommodation and offer a therapeutic target for presbyopia.

Visual function of children with visual and other disabilities in Oman: A case series.

PubMed

Gogri, Urmi; Khandekar, Rajiv; Al Harby, Salah

2016-12-01

We assessed the visual functioning of the children with special needs in Oman between 2009 and 2012. We present the methods of assessing different visual functions, outcomes, and interventions carried out to improve their functioning. Optometrists assessed visual functions of children of "Day care centres" in Oman. Experts further assessed them and provided low vision care. Ocular movements, refractive corrections, near, distance, contrast color, motion, field of vision, and cognitive visual function test results were noted. Feedback to caregivers was given to improve visual functioning of these children. We grouped 321 participants, (196 [61.1%] boys, age range of 3-18 years) into 61; Down syndrome (DS), 72 with intellectual disabilities (IDs), 67; hearing impaired and 121 with other conditions. Refractive error and lag of accommodation were 26 (42.6%) and 14 (22.6%) among children with DS. Contrast sensitivity was impaired in 8 (12.7%) among hearing impaired children. Defective distant and near vision was in 162 (70%) and 104 (42%) of our cohort. Children with ID were most difficult to assess. Children in a group of other disabilities had a higher proportion of impaired visual functioning. They were given low vision aids (telescopes [22], filters [7], and magnifiers [3]) in large numbers compared to those in other groups. Visual functioning of children with other disabilities show great variation and difficult to group. The care, therefore, should be at individual level. All visual functions cannot be assessed at one time.

Convergence and Accommodation Development Is Preprogrammed in Premature Infants.

PubMed

Horwood, Anna M; Toor, Sonia S; Riddell, Patricia M

2015-08-01

This study investigated whether vergence and accommodation development in preterm infants is preprogrammed or is driven by experience. Thirty-two healthy infants, born at mean 34 weeks gestation (range, 31.2-36 weeks), were compared with 45 healthy full-term infants (mean 40.0 weeks) over a 6-month period, starting at 4 to 6 weeks postnatally. Simultaneous accommodation and convergence to a detailed target were measured using a Plusoptix PowerRefII infrared photorefractor as a target moved between 0.33 and 2 m. Stimulus/response gains and responses at 0.33 and 2 m were compared by both corrected (gestational) age and chronological (postnatal) age. When compared by their corrected age, preterm and full-term infants showed few significant differences in vergence and accommodation responses after 6 to 7 weeks of age. However, when compared by chronological age, preterm infants' responses were more variable, with significantly reduced vergence gains, reduced vergence response at 0.33 m, reduced accommodation gain, and increased accommodation at 2 m compared to full-term infants between 8 and 13 weeks after birth. When matched by corrected age, vergence and accommodation in preterm infants show few differences from full-term infants' responses. Maturation appears preprogrammed and is not advanced by visual experience. Longer periods of immature visual responses might leave preterm infants more at risk of development of oculomotor deficits such as strabismus.

A survey of visual function in an Austrian population of school-age children with reading and writing difficulties.

PubMed

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

2010-05-25

To describe and compare visual function measures of two groups of school age children (6-14 years of age) attending a specialist eyecare practice in Austria; one group referred to the practice from educational assessment centres diagnosed with reading and writing difficulties and the other, a clinical age-matched control group. Retrospective clinical data from one group of subjects with reading difficulties (n = 825) and a clinical control group of subjects (n = 328) were examined.Statistical analysis was performed to determine whether any differences existed between visual function measures from each group (refractive error, visual acuity, binocular status, accommodative function and reading speed and accuracy). Statistical analysis using one way ANOVA demonstrated no differences between the two groups in terms of refractive error and the size or direction of heterophoria at distance (p > 0.05). Using predominately one way ANOVA and chi-square analyses, those subjects in the referred group were statistically more likely to have poorer distance visual acuity, an exophoric deviation at near, a lower amplitude of accommodation, reduced accommodative facility, reduced vergence facility, a reduced near point of convergence, a lower AC/A ratio and a slower reading speed than those in the clinical control group (p < 0.05). This study highlights the high proportions of visual function anomalies in a group of children with reading difficulties in an Austrian population. It confirms the importance of a full assessment of binocular visual status in order to detect and remedy these deficits in order to prevent the visual problems continuing to impact upon educational development.

[Physiological mechanisms of the etiology of visual fatigue during work involving visual stress].

PubMed

Korniushina, T A

2000-01-01

Physiological parameters of vision were studied in three professional groups (a total of 1204 subjects): microscope operators, subjects working with magnifying glasses, and computer users. General and specific features of visual system fatigue formation were identified. Because of complete (in microscope operators) or partial (in subjects working with magnifying glasses and display users) "deprivation" of accommodation, these subjects develop early presbyopia (at the age of 30-35 years). In microscope operators long strain of accommodation system leads to professional myopia, while display users develop pseudomyopia. The highest overstrain is observed after 4 years of work in microscope operators, after 5 years in magnifying glass users, and after 6 years in computer users.

Near visual acuity for everyday activities with accommodative and monofocal intraocular lenses.

PubMed

Sanders, Donald R; Sanders, Monica L

2007-10-01

To determine the levels of functional near visual acuity required for everyday social reading activities and to compare the levels to those attained with accommodative and monofocal intraocular lenses (LOLs). Font size equivalencies of an Early Treatment Diabetic Retinopathy Study near chart and a variety of commonly read print objects were determined and correlated to the findings of distance-corrected near vision measurements with 2 accommodative (Tetraflex, 1CU) and 1 monofocal (Acrysof MA30) IOLs. The smallest print objects studied were sweetener packets with type between 20/40 (Jaeger [J] 5) and 20/50 (J6). Type in classified ads, stock quotations, and pocket bibles was 20/50 (J6), type in a telephone directory was 20/63 (J8), and type in standard newspapers, journals, and magazines was 20/80 (J9). Tested monocularly, 88% of Tetraflex, 40% of ICU, and 7% of Acrysof MA30 eyes had distance-corrected near vision sufficient to read newspaper and telephone directory print, and 63% of Tetraflex, 30% of 1CU, and 0% of Acrysof MA30 eyes could read classified ads, stock quotations, and pocket bibles, respectively. Tested binocularly after bilateral implantation, 96% of Tetraflex patients could read telephone directory print and 89% could read ads, stock quotations, and pocket bibles. Functional near visual acuity is not equivalent to the bottom-line objective at 20/20 (J1) near visual acuity. No print size was found at or smaller than 20/40 (J5), indicating that a requirement of nearly perfect near visual acuity, while desirable, may not be necessary for patients' social reading needs for accommodative IOLs.

Prediction of anthropometric accommodation in aircraft cockpits

NASA Astrophysics Data System (ADS)

Zehner, Gregory Franklin

Designing aircraft cockpits to accommodate the wide range of body sizes existing in the U.S. population has always been a difficult problem for Crewstation Engineers. The approach taken in the design of military aircraft has been to restrict the range of body sizes allowed into flight training, and then to develop standards and specifications to ensure that the majority of the pilots are accommodated. Accommodation in this instance is defined as the ability to: (1) Adequately see, reach, and actuate controls; (2) Have external visual fields so that the pilot can see to land, clear for other aircraft, and perform a wide variety of missions (ground support/attack or air to air combat); and (3) Finally, if problems arise, the pilot has to be able to escape safely. Each of these areas is directly affected by the body size of the pilot. Unfortunately, accommodation problems persist and may get worse. Currently the USAF is considering relaxing body size entrance requirements so that smaller and larger people could become pilots. This will make existing accommodation problems much worse. This dissertation describes a methodology for correcting this problem and demonstrates the method by predicting pilot fit and performance in the USAF T-38A aircraft based on anthropometric data. The methods described can be applied to a variety of design applications where fitting the human operator into a system is a major concern. A systematic approach is described which includes: defining the user population, setting functional requirements that operators must be able to perform, testing the ability of the user population to perform the functional requirements, and developing predictive equations for selecting future users of the system. Also described is a process for the development of new anthropometric design criteria and cockpit design methods that assure body size accommodation is improved in the future.

Caffeine intake is associated with pupil dilation and enhanced accommodation

PubMed Central

Abokyi, S; Owusu-Mensah, J; Osei, K A

2017-01-01

Purpose It is purported that caffeine, an autonomic stimulant, affects visual performance. This study sought to assess whether caffeine intake was associated with changes in pupil size and/or amplitude of accommodation. Patients and methods A double-masked, crossover study was conducted in 50 healthy subjects of age range 19 to 25 years. Subjects were randomized to treatments such that subjects consumed either 250 mg caffeine drink or vehicle on separate days. Amplitude of accommodation was measured by the push-up technique, and pupil size using a millimeter ruler fixed to a slit lamp biomicroscope in dim illumination (5 lux). Amplitude of accommodation and pupil size were taken at baseline, and at 30, 60 and 90 min time points post treatment. Repeated measures one-way ANOVA and paired t-test were used in analyzing data. Results Amplitude of accommodation and pupil size after caffeine intake were significantly greater than vehicle (P<0.001) at each time point. Consumption of the caffeine beverage was associated with significant increases in amplitude of accommodation and pupil size with time (P<0.001). Amplitude of accommodation rose from 12.4 (±2.2 D) at baseline to 15.8(±2.6 D) at 90 min. Similarly, pupil size increased from 3.4 (±0.4 mm) at baseline to 4.5 (±0.72 mm) at 90 min. Consumption of vehicle was not associated with increase in amplitude of accommodation or pupil size with time. Conclusion Pupil size and accommodation are affected after ingestion of caffeine. This study suggests caffeine may have some influence on visual functions. PMID:27983733

[Correction of refractive errors in patients with strabismus. Part I. Clinical problems associated with refraction, accommodation and convergence].

PubMed

Tokarz-Sawińska, Ewa

2012-01-01

In Part I the problems associated with refraction, accommodation and convergence and their role in proper eye position/visual alignment of the eyes as well as convergent, divergent and vertical alignment of the eyes have been described.

The dynamic response of visual accommodation over a seven-day period

NASA Technical Reports Server (NTRS)

Randle, R. J.; Murphy, M. R.

1974-01-01

Four college students, ranging in age from 18 to 21 years, were tested on their dynamic, monocular accommodation responses to a square wave stimulus and sine waves of two frequencies. The tests were conducted over a period of seven days in a controlled environment, each subject being tested once every three hours. Latency, magnitude, velocity, gain and phase lag of the responses were measured, and means and standard deviations were computed. The latency of response was stable throughout and agreed fairly well with previous studies. The response magnitude was relatively stable. Three of the subjects had higher velocities on receding targets; one was faster on approaching targets. The group mean velocity increased over the seven days of the study. In keeping with the trend to faster dynamics over the seven days, both gain and phase lag improved.

Convergence and accommodation development is pre-programmed in premature infants

PubMed Central

Horwood, Anna M; Toor, Sonia S; Riddell, Patricia M

2015-01-01

Purpose This study investigated whether vergence and accommodation development in pre-term infants is pre-programmed or is driven by experience. Methods 32 healthy infants, born at mean 34 weeks gestation (range 31.2-36 weeks) were compared with 45 healthy full-term infants (mean 40.0 weeks) over a 6 month period, starting at 4-6 weeks post-natally. Simultaneous accommodation and convergence to a detailed target were measured using a Plusoptix PowerRefII infra-red photorefractor as a target moved between 0.33m and 2m. Stimulus/response gains and responses at 0.33m and 2m were compared by both corrected (gestational) age and chronological (post-natal) age. Results When compared by their corrected age, pre-term and full-term infants showed few significant differences in vergence and accommodation responses after 6-7 weeks of age. However, when compared by chronological age, pre-term infants’ responses were more variable, with significantly reduced vergence gains, reduced vergence response at 0.33m, reduced accommodation gain, and increased accommodation at 2m, compared to full-term infants between 8-13 weeks after birth. Conclusions When matched by corrected age, vergence and accommodation in pre-term infants show few differences from full-term infants’ responses. Maturation appears pre-programmed and is not advanced by visual experience. Longer periods of immature visual responses might leave pre-term infants more at risk of development of oculomotor deficits such as strabismus. PMID:26275135

Colouring the Gaps in Learning Design: Aesthetics and the Visual in Learning

ERIC Educational Resources Information Center

Carroll, Fiona; Kop, Rita

2016-01-01

The visual is a dominant mode of information retrieval and understanding however, the focus on the visual dimension of Technology Enhanced Learning (TEL) is still quite weak in relation to its predominant focus on usability. To accommodate the future needs of the visual learner, designers of e-learning environments should advance the current…

Evaluation of stereoscopic display with visual function and interview

NASA Astrophysics Data System (ADS)

Okuyama, Fumio

1999-05-01

The influence of binocular stereoscopic (3D) television display on the human eye were compared with one of a 2D display, using human visual function testing and interviews. A 40- inch double lenticular display was used for 2D/3D comparison experiments. Subjects observed the display for 30 minutes at a distance 1.0 m, with a combination of 2D material and one of 3D material. The participants were twelve young adults. Main optometric test with visual function measured were visual acuity, refraction, phoria, near vision point, accommodation etc. The interview consisted of 17 questions. Testing procedures were performed just before watching, just after watching, and forty-five minutes after watching. Changes in visual function are characterized as prolongation of near vision point, decrease of accommodation and increase in phoria. 3D viewing interview results show much more visual fatigue in comparison with 2D results. The conclusions are: 1) change in visual function is larger and visual fatigue is more intense when viewing 3D images. 2) The evaluation method with visual function and interview proved to be very satisfactory for analyzing the influence of stereoscopic display on human eye.

Experiences of Visually Impaired Students in Community College Math Courses

NASA Astrophysics Data System (ADS)

Swan, S. Tomeka

Blind and visually impaired students who attend community colleges face challenges in learning mathematics (Forrest, 2010). Scoy, McLaughlin, Walls, and Zuppuhaur (2006) claim these students are at a disadvantage in studying mathematics due to the visual and interactive nature of the subject, and by the way mathematics is taught. In this qualitative study six blind and visually impaired students attended three community colleges in one Mid-Atlantic state. They shared their experiences inside the mathematics classroom. Five of the students were enrolled in developmental level math, and one student was enrolled in college level math. The conceptual framework used to explore how blind and visually impaired students persist and succeed in math courses was Piaget's theory on constructivism. The data from this qualitative study was obtained through personal interviews. Based on the findings of this study, blind and visually impaired students need the following accommodations in order to succeed in community college math courses: Accommodating instructors who help to keep blind and visually impaired students motivated and facilitate their academic progress towards math completion, tutorial support, assistive technology, and a positive and inclusive learning environment.

Ocular dynamics of systemic aqueous extracts of Xylopia aethiopica (African guinea pepper) seeds on visually active volunteers.

PubMed

Igwe, S A; Afonne, J C; Ghasi, S I

2003-06-01

Xylopia aethiopica, African guinea pepper, is an angiosperm belonging to the family Annonecae, and used mainly as spice and in traditional medicine. The ocular dynamics of bolus consumption of 300 mg total dose was undertaken on visually active volunteers with a view to finding its ocular effects or complications. Results showed that the aqueous extract of X. aethiopica was neither a miotic nor a mydriatic, but lowered the intraocular pressure (17.48%), reduced the near point of convergence (31.1%) and increased the amplitude of accommodation (8.98%) which are positively correlated (r=0.95). On the other hand, the systemic extract had no effect on the visual acuity at far and near as well as the phoria status at the appropriate distances. The convergence excess resulted in esophoria and the increased amplitude of accommodation placed greater demand on accommodation mechanism without any discomfort. The nonspecific mechanism of action makes it a safer spice which can be exploited in the management of exophoria and raised intraocular pressure (glaucoma) in instances where the efficacy of the older conventional drugs is insufficient.

The effect of monocular and binocular viewing on the accommodation response to real targets in emmetropia and myopia.

PubMed

Seidel, Dirk; Gray, Lyle S; Heron, Gordon

2005-04-01

Decreased blur-sensitivity found in myopia has been linked with reduced accommodation responses and myopigenesis. Although the mechanism for myopia progression remains unclear, it is commonly known that myopic patients rarely report near visual symptoms and are generally very sensitive to small changes in their distance prescription. This experiment investigated the effect of monocular and binocular viewing on static and dynamic accommodation in emmetropes and myopes for real targets to monitor whether inaccuracies in the myopic accommodation response are maintained when a full set of visual cues, including size and disparity, is available. Monocular and binocular steady-state accommodation responses were measured with a Canon R1 autorefractor for target vergences ranging from 0-5 D in emmetropes (EMM), late-onset myopes (LOM), and early-onset myopes (EOM). Dynamic closed-loop accommodation responses for a stationary target at 0.25 m and step stimuli of two different magnitudes were recorded for both monocular and binocular viewing. All refractive groups showed similar accommodation stimulus response curves consistent with previously published data. Viewing a stationary near target monocularly, LOMs demonstrated slightly larger accommodation microfluctuations compared with EMMs and EOMs; however, this difference was absent under binocular viewing conditions. Dynamic accommodation step responses revealed significantly (p < 0.05) longer response times for the myopic subject groups for a number of step stimuli. No significant difference in either reaction time or the number of correct responses for a given number of step-vergence changes was found between the myopic groups and EMMs. When viewing real targets with size and disparity cues available, no significant differences in the accuracy of static and dynamic accommodation responses were found among EMM, EOM, and LOM. The results suggest that corrected myopes do not experience dioptric blur levels that are substantially different from emmetropes when they view free space targets.

Ophthalmological outcome after resection of tumors based on the pineal gland.

PubMed

Hart, Michael G; Sarkies, Nicholas J; Santarius, Thomas; Kirollos, Ramez W

2013-08-01

Descriptions of visual dysfunction in pineal gland tumors tend to focus on upward gaze palsy alone. The authors aimed to characterize the nature, incidence, and functional significance of ophthalmological dysfunction after resection of tumors based on the pineal gland. Review of a retrospective case series was performed and included consecutive patients who underwent surgery performed by a consultant neurosurgeon between 2002 and 2011. Only tumors specifically based on the pineal gland were included; tumors encroaching on the pineal gland from other regions were excluded. All patients with visual signs and/or symptoms were reviewed by a specialist consultant neuroophthalmologist to accurately characterize the nature of their deficits. Visual disturbance was defined as visual symptoms caused by a disturbance of ocular motility. A total of 20 patients underwent resection of pineal gland tumors. Complete resection was obtained in 85%, and there were no perioperative deaths. Visual disturbance was present in 35% at presentation; of those who had normal ocular motility preoperatively 82% had normal motility postoperatively. In total, 55% of patients had residual visual disturbance postoperatively. Although upward gaze tended to improve, significant functional deficits remained, particularly with regard to complex convergence and accommodation dysfunction. Prisms were used in 25% but were only ever partially effective. Visual outcome was only related to preoperative visual status and tumor volume (multivariate analysis). Long-term visual morbidity after pineal gland tumor resection is common and leads to significant functional impairment. Improvement in deficits rarely occurs spontaneously, and prisms only have limited effectiveness, probably due to the dynamic nature of supranuclear ocular movement coordination.

Op art and visual perception.

PubMed

Wade, N J

1978-01-01

An attempt is made to list the visual phenomena exploited in op art. These include moire frinlude moiré fringes, afterimages, Hermann grid effects, Gestalt grouping principles, blurring and movement due to astigmatic fluctuations in accommodation, scintillation and streaming possibly due to eye movements, and visual persistence. The historical origins of these phenomena are also noted.

Accommodating Scientific Illiteracy: Award-Winning Visualizations on the Covers of "Science"

ERIC Educational Resources Information Center

Gigante, Maria E.

2012-01-01

The International Science and Engineering Visualization Challenge, recently established by the National Science Foundation (NSF), is an alleged attempt at public outreach. The NSF encourages scientists to submit visualizations that would appeal to non-expert audiences by displaying their work in an annual "special feature" in "Science" magazine,…

Teaching Choice Making to Children with Visual Impairments and Multiple Disabilities in Preschool and Kindergarten Classrooms

ERIC Educational Resources Information Center

Clark, Christine; McDonnell, Andrea P.

2008-01-01

This study examined the effectiveness of an intervention package that included visual accommodations, daily preference assessments, and naturalistic instructional strategies on the accuracy of choice-making responses for three participants with visual impairments and multiple disabilities. It also examined the participants' ability to maintain and…

Visual discomfort in stereoscopic displays: a review

NASA Astrophysics Data System (ADS)

Lambooij, Marc T. M.; IJsselsteijn, Wijnand A.; Heynderickx, Ingrid

2007-02-01

Visual discomfort has been the subject of considerable research in relation to stereoscopic and autostereoscopic displays, but remains an ambiguous concept used to denote a variety of subjective symptoms potentially related to different underlying processes. In this paper we clarify the importance of various causes and aspects of visual comfort. Classical causative factors such as excessive binocular parallax and accommodation-convergence conflict appear to be of minor importance when disparity values do not surpass one degree limit of visual angle, which still provides sufficient range to allow for satisfactory depth perception in consumer applications, such as stereoscopic television. Visual discomfort, however, may still occur within this limit and we believe the following factors to be the most pertinent in contributing to this: (1) excessive demand of accommodation-convergence linkage, e.g., by fast motion in depth, viewed at short distances, (2) 3D artefacts resulting from insufficient depth information in the incoming data signal yielding spatial and temporal inconsistencies, and (3) unnatural amounts of blur. In order to adequately characterize and understand visual discomfort, multiple types of measurements, both objective and subjective, are needed.

The effects of a convex rear-view mirror on ocular accommodative responses.

PubMed

Nagata, Tatsuo; Iwasaki, Tsuneto; Kondo, Hiroyuki; Tawara, Akihiko

2013-11-01

Convex mirrors are universally used as rear-view mirrors in automobiles. However, the ocular accommodative responses during the use of these mirrors have not yet been examined. This study investigated the effects of a convex mirror on the ocular accommodative systems. Seven young adults with normal visual functions were ordered to binocularly watch an object in a convex or plane mirror. The accommodative responses were measured with an infrared optometer. The average of the accommodation of all subjects while viewing the object in the convex mirror were significantly nearer than in the plane mirror, although all subjects perceived the position of the object in the convex mirror as being farther away. Moreover, the fluctuations of accommodation were significantly larger for the convex mirror. The convex mirror caused the 'false recognition of distance', which induced the large accommodative fluctuations and blurred vision. Manufactures should consider the ocular accommodative responses as a new indicator for increasing automotive safety. Copyright © 2013 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Nocturnality constrains morphological and functional diversity in the eyes of reef fishes.

PubMed

Schmitz, Lars; Wainwright, Peter C

2011-11-19

Ambient light levels are often considered to drive the evolution of eye form and function. Diel activity pattern is the main mechanism controlling the visual environment of teleost reef fish, with day-active (diurnal) fish active in well-illuminated conditions, whereas night-active (nocturnal) fish cope with dim light. Physiological optics predicts several specific evolutionary responses to dim-light vision that should be reflected in visual performance features of the eye. We analyzed a large comparative dataset on morphological traits of the eyes in 265 species of teleost reef fish in 43 different families. The eye morphology of nocturnal reef teleosts is characterized by a syndrome that indicates better light sensitivity, including large relative eye size, high optical ratio and large, rounded pupils. Improved dim-light image formation comes at the cost of reduced depth of focus and reduction of potential accommodative lens movement. Diurnal teleost reef fish, released from the stringent functional requirements of dim-light vision have much higher morphological and optical diversity than nocturnal species, with large ranges of optical ratio, depth of focus, and lens accommodation. Physical characteristics of the environment are an important factor in the evolution and diversification of the vertebrate eye. Both teleost reef fish and terrestrial amniotes meet the functional requirements of dim-light vision with a similar evolutionary response of morphological and optical modifications. The trade-off between improved dim-light vision and reduced optical diversity may be a key factor in explaining the lower trophic diversity of nocturnal reef teleosts.

The BHVI-EyeMapper: peripheral refraction and aberration profiles.

PubMed

Fedtke, Cathleen; Ehrmann, Klaus; Falk, Darrin; Bakaraju, Ravi C; Holden, Brien A

2014-10-01

The aim of this article was to present the optical design of a new instrument (BHVI-EyeMapper, EM), which is dedicated to rapid peripheral wavefront measurements across the visual field for distance and near, and to compare the peripheral refraction and higher-order aberration profiles obtained in myopic eyes with and without accommodation. Central and peripheral refractive errors (M, J180, and J45) and higher-order aberrations (C[3, 1], C[3, 3], and C[4, 0]) were measured in 26 myopic participants (mean [±SD] age, 20.9 [±2.0] years; mean [±SD] spherical equivalent, -3.00 [±0.90] diopters [D]) corrected for distance. Measurements were performed along the horizontal visual field with (-2.00 to -5.00 D) and without (+1.00 D fogging) accommodation. Changes as a function of accommodation were compared using tilt and curvature coefficients of peripheral refraction and aberration profiles. As accommodation increased, the relative peripheral refraction profiles of M and J180 became significantly (p < 0.05) more negative and the profile of M became significantly (p < 0.05) more asymmetric. No significant differences were found for the J45 profiles (p > 0.05). The peripheral aberration profiles of C[3, 1], C[3, 3], and C[4, 0] became significantly (p < 0.05) less asymmetric as accommodation increased, but no differences were found in the curvature. The current study showed that significant changes in peripheral refraction and higher-order aberration profiles occurred during accommodation in myopic eyes. With its extended measurement capabilities, that is, permitting rapid peripheral refraction and higher-order aberration measurements up to visual field angles of ±50 degrees for distance and near (up to -5.00 D), the EM is a new advanced instrument that may provide additional insights in the ongoing quest to understand and monitor myopia development.

The BHVI-EyeMapper: Peripheral Refraction and Aberration Profiles

PubMed Central

Fedtke, Cathleen; Ehrmann, Klaus; Falk, Darrin; Bakaraju, Ravi C.; Holden, Brien A.

2014-01-01

ABSTRACT Purpose The aim of this article was to present the optical design of a new instrument (BHVI-EyeMapper, EM), which is dedicated to rapid peripheral wavefront measurements across the visual field for distance and near, and to compare the peripheral refraction and higher-order aberration profiles obtained in myopic eyes with and without accommodation. Methods Central and peripheral refractive errors (M, J180, and J45) and higher-order aberrations (C[3, 1], C[3, 3], and C[4, 0]) were measured in 26 myopic participants (mean [±SD] age, 20.9 [±2.0] years; mean [±SD] spherical equivalent, −3.00 [±0.90] diopters [D]) corrected for distance. Measurements were performed along the horizontal visual field with (−2.00 to −5.00 D) and without (+1.00 D fogging) accommodation. Changes as a function of accommodation were compared using tilt and curvature coefficients of peripheral refraction and aberration profiles. Results As accommodation increased, the relative peripheral refraction profiles of M and J180 became significantly (p < 0.05) more negative and the profile of M became significantly (p < 0.05) more asymmetric. No significant differences were found for the J45 profiles (p > 0.05). The peripheral aberration profiles of C[3, 1], C[3, 3], and C[4, 0] became significantly (p < 0.05) less asymmetric as accommodation increased, but no differences were found in the curvature. Conclusions The current study showed that significant changes in peripheral refraction and higher-order aberration profiles occurred during accommodation in myopic eyes. With its extended measurement capabilities, that is, permitting rapid peripheral refraction and higher-order aberration measurements up to visual field angles of ±50 degrees for distance and near (up to −5.00 D), the EM is a new advanced instrument that may provide additional insights in the ongoing quest to understand and monitor myopia development. PMID:25105690

Bigness is in the eye of the beholder. [size and distance perception of pilots in flight

NASA Technical Reports Server (NTRS)

Roscoe, S. N.

1985-01-01

This report reviews an investigation of judgments of size and distance as required of pilots in flight. The experiments covered a broad spectrum of basic psychophysiological issues involving the measurement of visual accommodation and its correlation with various other dependent variables. Psychophysiological issues investigated included the size-distance invariance hypothesis, the projection of afterimages, the moon illusion, night and empty-field myopia, the dark focus and its so-called Mandelbaum effect, the nature and locus of the accommodative stimulus, the relation between accommodation, retinal size, and perceived size, and possible relationships among accommodative responses, autonomic balance, and personality variables.

Fast scanning photoretinoscope for measuring peripheral refraction as a function of accommodation.

PubMed

Tabernero, Juan; Schaeffel, Frank

2009-10-01

A new device was designed to provide fast measurements (4 s) of the peripheral refraction (90 degrees central horizontal field). Almost-continuous traces are obtained with high angular resolution (0.4 degrees) while the subject is fixating a central stimulus. Three-dimensional profiles can also be measured. The peripheral refractions in 10 emmetropic subjects were studied as a function of accommodation (200 cm, 50 cm, and 25 cm viewing distances). Peripheral refraction profiles were largely preserved during accommodation but were different in each individual. Apparently, the accommodating lens changes its focal length evenly over the central 90 degrees of the visual field.

Neck/shoulder discomfort due to visually demanding experimental near work is influenced by previous neck pain, task duration, astigmatism, internal eye discomfort and accommodation

PubMed Central

Forsman, Mikael; Richter, Hans O.

2017-01-01

Visually demanding near work can cause eye discomfort, and eye and neck/shoulder discomfort during, e.g., computer work are associated. To investigate direct effects of experimental near work on eye and neck/shoulder discomfort, 33 individuals with chronic neck pain and 33 healthy control subjects performed a visual task four times using four different trial lenses (referred to as four different viewing conditions), and they rated eye and neck/shoulder discomfort at baseline and after each task. Since symptoms of eye discomfort may differ depending on the underlying cause, two categories were used; internal eye discomfort, such as ache and strain, that may be caused by accommodative or vergence stress; and external eye discomfort, such as burning and smarting, that may be caused by dry-eye disorders. The cumulative performance time (reflected in the temporal order of the tasks), astigmatism, accommodation response and concurrent symptoms of internal eye discomfort all aggravated neck/shoulder discomfort, but there was no significant effect of external eye discomfort. There was also an interaction effect between the temporal order and internal eye discomfort: participants with a greater mean increase in internal eye discomfort also developed more neck/shoulder discomfort with time. Since moderate musculoskeletal symptoms are a risk factor for more severe symptoms, it is important to ensure a good visual environment in occupations involving visually demanding near work. PMID:28832612

Neck/shoulder discomfort due to visually demanding experimental near work is influenced by previous neck pain, task duration, astigmatism, internal eye discomfort and accommodation.

PubMed

Zetterberg, Camilla; Forsman, Mikael; Richter, Hans O

2017-01-01

Visually demanding near work can cause eye discomfort, and eye and neck/shoulder discomfort during, e.g., computer work are associated. To investigate direct effects of experimental near work on eye and neck/shoulder discomfort, 33 individuals with chronic neck pain and 33 healthy control subjects performed a visual task four times using four different trial lenses (referred to as four different viewing conditions), and they rated eye and neck/shoulder discomfort at baseline and after each task. Since symptoms of eye discomfort may differ depending on the underlying cause, two categories were used; internal eye discomfort, such as ache and strain, that may be caused by accommodative or vergence stress; and external eye discomfort, such as burning and smarting, that may be caused by dry-eye disorders. The cumulative performance time (reflected in the temporal order of the tasks), astigmatism, accommodation response and concurrent symptoms of internal eye discomfort all aggravated neck/shoulder discomfort, but there was no significant effect of external eye discomfort. There was also an interaction effect between the temporal order and internal eye discomfort: participants with a greater mean increase in internal eye discomfort also developed more neck/shoulder discomfort with time. Since moderate musculoskeletal symptoms are a risk factor for more severe symptoms, it is important to ensure a good visual environment in occupations involving visually demanding near work.

[Effects on visual functions following several hours' usage of a head mounted display].

PubMed

Hara, N; Ukai, K; Ishikawa, S; Takagi, M; Bando, T; Oyamada, H

1996-07-01

We investigated the effects of viewing video movies with a head-mounted display (HMD) for 4 to 6 hours on visual functions such as refraction, visual acuity, and accommodation-vergence system. Two or three video movies were watched without any breaks by 13 normal volunteers (age: 22 approximately 40). Measurements were made of (1) objective and subjective refraction, (2) corrected visual acuity, (3) tonic level and step response of accommodation with a computer-assisted infrared optometer, and (4) near and far phorias and AC/A ratio. Significant transient myopia was found following 4 hours' viewing, but not following 6 hours' viewing. Scrutinizing individual data, myopia was consistently found in some subjects, and hyperopia in others. We presumed that many subjects might have been influenced by initial instrumental myopia when they adjusted the focus by using the mechanism built in the HMD. No significant change was observed in any other examination. However, there was a tendency for the AC/A ratio to change after a short time, and then to recover to its original value. Based on the results in this study, it appears that some changes in accommodation and vergence systems are caused by viewing video movies with the HMD. Although the amount of changes was within normal physiological variation in this study, the possibility still remains that usage for a longer time may lead to other changes in visual function. Care is also necessary when using the HMD in subjects with subclinical problems.

Intermediate visual acuity of presbyopic individuals with and without distance and bifocal lens corrections.

DOT National Transportation Integrated Search

1977-03-01

Visual acuity was determined at the intermediate range for older individuals with various combinations of ocular refractive error (nine subcategories) and accommodative power (three subcategories). Subjects (N=249) read numerals ranging in size to me...

Uncorrected refractive error and presbyopia among junior high school teachers in Jakarta, Indonesia.

PubMed

Ehrlich, Joshua R; Laoh, Alex; Kourgialis, Nick; Prasetyanti, Widya; Zakiyah, Rima; Faillace, Silvana; Friedman, David S

2013-12-01

To report on the frequency of observed refractive and accommodative errors among junior high school teachers in Jakarta, Indonesia, who participated in a Helen Keller International screening, refraction and spectacle distribution program. A total of 965 teachers from 19 schools were eligible for screening; those with uncorrected distance visual acuity (VA) ≤ 6/12-3 and teachers ≥ 35 years old with uncorrected end-point print size >Jaeger (J) 6 were referred. Autorefraction and subjective refraction were performed for teachers with confirmed decreased VA. Refractive error was considered present if sphere ≤-0.75 diopters (D), sphere ≥+0.25D or cylinder ≤-0.50 D resulted in ≥ 2 lines of improvement in VA. Presbyopia was considered present if an end-point print size >J6 improved by ≥ 1 optotype with the use of a lens ≥+1.00 D. Overall, 866 teachers were screened (89.7% of those eligible) with complete screening data available for 858 (99.0%), among whom 762 failed screening. Distance refraction data were available for 666 of 762 (87.4%) and near refraction data for 520 of 686 (75.8%) teachers who failed screening. Of those screened, 76.2 ± 9.0% of teachers had refractive and/or accommodative error and 57.1 ± 7.6% had uncorrected refractive and/or accommodative error. Overall and uncorrected distance refractive error affected 44.2 ± 3.7% and 36.0 ± 3.6%, respectively; overall and uncorrected presbyopia affected 66.4 ± 8.1% and 41.0 ± 6.6%, respectively. As defined in this program, refractive and accommodative errors were common among teachers in Jakarta.

Accommodative Lag by Autorefraction and Two Dynamic Retinoscopy Methods

PubMed Central

2008-01-01

Purpose To evaluate two clinical procedures, MEM and Nott retinoscopy, for detecting accommodative lags 1.00 diopter (D) or greater in children as identified by an open-field autorefractor. Methods 168 children 8 to <12 years old with low myopia, normal visual acuity, and no strabismus participated as part of an ancillary study within the screening process for a randomized trial. Accommodative response to a 3.00 D demand was first assessed by MEM and Nott retinoscopy, viewing binocularly with spherocylindrical refractive error corrected, with testing order randomized and each performed by a different masked examiner. The response was then determined viewing monocularly with spherical equivalent refractive error corrected, using an open-field autorefractor, which was the gold standard used for eligibility for the clinical trial. Sensitivity and specificity for accommodative lags of 1.00 D or more were calculated for each retinoscopy method compared to the autorefractor. Results 116 (69%) of the 168 children had accommodative lag of 1.00 D or more by autorefraction. MEM identified 66 children identified by autorefraction for a sensitivity of 57% (95% CI = 47% to 66%) and a specificity of 63% (95% CI = 49% to 76%). Nott retinoscopy identified 35 children for a sensitivity of 30% (95% CI = 22% to 39%) and a specificity of 81% (95% CI = 67% to 90%). Analysis of receiver operating characteristic (ROC) curves constructed for MEM and for Nott retinoscopy failed to reveal alternate cut points that would improve the combination of sensitivity and specificity for identifying accommodative lag ≥ 1.00 D as defined by autorefraction. Conclusions Neither MEM nor Nott retinoscopy provided adequate sensitivity and specificity to identify myopic children with accommodative lag ≥ 1.00 D as determined by autorefraction. A variety of methodological differences between the techniques may contribute to the modest to poor agreement. PMID:19214130

Clear lens extraction for the treatment of persistent accommodative spasm after head trauma.

PubMed

McMurray, Catherine J; Burley, Celeste D; Elder, Mark J

2004-12-01

We report the case of a 28-year-old man with decreased visual acuity after closed head trauma sustained in a motor vehicle accident 16 weeks earlier. Several structures thought to be associated with the control of accommodation were injured. The patient had a persistent accommodative spasm causing up to 7.0 diopters of pseudomyopia. We present the patient's progress through the clinic, including manifest and cycloplegic refractions and results of a trial with atropine drops, and successful transition to bilateral pseudophakia 2 years and 9 months after the accident.

Developing Testing Accommodations for English Language Learners: Illustrations as Visual Supports for Item Accessibility

ERIC Educational Resources Information Center

Solano-Flores, Guillermo; Wang, Chao; Kachchaf, Rachel; Soltero-Gonzalez, Lucinda; Nguyen-Le, Khanh

2014-01-01

We address valid testing for English language learners (ELLs)--students in the United States who are schooled in English while they are still acquiring English as a second language. Also, we address the need for procedures for systematically developing ELL testing accommodations--changes in tests intended to support ELLs to gain access to the…

Accommodative and vergence responses to conflicting blur and disparity stimuli during development

PubMed Central

Bharadwaj, Shrikant R.; Candy, T. Rowan

2014-01-01

Accommodative and vergence responses of the typically developing visual system are generated using a combination of cues, including retinal blur and disparity. The developmental importance of blur and disparity cues in generating these motor responses was assessed by placing the two cues in conflict with each other. Cue-conflicts were induced by placing either −2 D lenses or 2 MA base-out prisms before both eyes of 140 subjects (2.0 months to 40.8 years) while they watched a cartoon movie binocularly at 80 cm. The frequency and amplitude of accommodation to lenses and vergence to prisms increased with age (both p < 0.001), with the vergence response (mean ± 1 SEM = 1.38 ± 0.05 MA) being slightly larger than the accommodative response (1.18 ± 0.04 D) at all ages (p = 0.007). The amplitude of these responses decreased with an increase in conflict stimuli (1 to 3 D or MA) (both p < 0.01). The coupled vergence response to −2 D lenses (0.31 ± 0.06 MA) and coupled accommodative response to 2 MA base-out prisms (0.21 ± 0.02 D) were significantly smaller than (both p < 0.001) and poorly correlated with the open-loop vergence (r = 0.12; p = 0.44) and open-loop accommodation (r = −0.08; p = 0.69), respectively. The typically developing visual system compensates for transiently induced conflicts between blur and disparity stimuli, without exhibiting a strong preference for either cue. The accuracy of this compensation decreases with an increase in amplitude of cue-conflict. PMID:20053067

Integrated remote sensing and visualization (IRSV) system for transportation infrastructure operations and management, phase one, volume 1 : summary report.

DOT National Transportation Integrated Search

2009-12-01

The Integrated Remote Sensing and Visualization System (IRSV) is being designed to accommodate the needs of todays Bridge : Engineers at the state and local level from the following aspects: : Better understanding and enforcement of a complex ...

Applied Computational Chemistry for the Blind and Visually Impaired

ERIC Educational Resources Information Center

Wedler, Henry B.; Cohen, Sarah R.; Davis, Rebecca L.; Harrison, Jason G.; Siebert, Matthew R.; Willenbring, Dan; Hamann, Christian S.; Shaw, Jared T.; Tantillo, Dean J.

2012-01-01

We describe accommodations that we have made to our applied computational-theoretical chemistry laboratory to provide access for blind and visually impaired students interested in independent investigation of structure-function relationships. Our approach utilizes tactile drawings, molecular model kits, existing software, Bash and Perl scripts…

STS payload data collection and accommodations analysis study. Volume 3: Accommodations analysis

NASA Technical Reports Server (NTRS)

1978-01-01

Payload requirements were compared to launch site accommodations and flight accommodations for a number of Spacelab payloads. Experiment computer operating system accommodations were also considered. A summary of accommodations in terms of resources available for payload discretionary use and recommendations for Spacelab/STS accommodation improvements are presented.

Nocturnality constrains morphological and functional diversity in the eyes of reef fishes

PubMed Central

2011-01-01

Background Ambient light levels are often considered to drive the evolution of eye form and function. Diel activity pattern is the main mechanism controlling the visual environment of teleost reef fish, with day-active (diurnal) fish active in well-illuminated conditions, whereas night-active (nocturnal) fish cope with dim light. Physiological optics predicts several specific evolutionary responses to dim-light vision that should be reflected in visual performance features of the eye. Results We analyzed a large comparative dataset on morphological traits of the eyes in 265 species of teleost reef fish in 43 different families. The eye morphology of nocturnal reef teleosts is characterized by a syndrome that indicates better light sensitivity, including large relative eye size, high optical ratio and large, rounded pupils. Improved dim-light image formation comes at the cost of reduced depth of focus and reduction of potential accommodative lens movement. Diurnal teleost reef fish, released from the stringent functional requirements of dim-light vision have much higher morphological and optical diversity than nocturnal species, with large ranges of optical ratio, depth of focus, and lens accommodation. Conclusions Physical characteristics of the environment are an important factor in the evolution and diversification of the vertebrate eye. Both teleost reef fish and terrestrial amniotes meet the functional requirements of dim-light vision with a similar evolutionary response of morphological and optical modifications. The trade-off between improved dim-light vision and reduced optical diversity may be a key factor in explaining the lower trophic diversity of nocturnal reef teleosts. PMID:22098687

Changes in dynamics of accommodation after accommodative facility training in myopes and emmetropes.

PubMed

Allen, Peter M; Charman, W Neil; Radhakrishnan, Hema

2010-05-12

This study evaluates the effect of accommodative facility training in myopes and emmetropes. Monocular accommodative facility was measured in nine myopes and nine emmetropes for distance and near. Subjective facility was recorded with automated flippers and objective measurements were simultaneously taken with a PowerRefractor. Accommodative facility training (a sequence of 5 min monocular right eye, 5 min monocular left eye, 5 min binocular) was given on three consecutive days and facility was re-assessed on the fifth day. The results showed that training improved the facility rate in both groups. The improvement in facility rates were linked to the time constants and peak velocity of accommodation. Some changes in amplitude seen in emmetropes indicate an improvement in facility rate at the expense of an accurate accommodation response. Copyright 2010 Elsevier Ltd. All rights reserved.

Optical methods for enabling focus cues in head-mounted displays for virtual and augmented reality

NASA Astrophysics Data System (ADS)

Hua, Hong

2017-05-01

Developing head-mounted displays (HMD) that offer uncompromised optical pathways to both digital and physical worlds without encumbrance and discomfort confronts many grand challenges, both from technological perspectives and human factors. Among the many challenges, minimizing visual discomfort is one of the key obstacles. One of the key contributing factors to visual discomfort is the lack of the ability to render proper focus cues in HMDs to stimulate natural eye accommodation responses, which leads to the well-known accommodation-convergence cue discrepancy problem. In this paper, I will provide a summary on the various optical methods approaches toward enabling focus cues in HMDs for both virtual reality (VR) and augmented reality (AR).

[Binocular fusion method for prevention of myopia].

PubMed

Xu, G D

1989-03-01

When looking at a far object with two eyes, relaxation of convergence and accommodation occurred and accompanied by binocular fusion. Using this phenomenon a method of binocular fusion of targets was designed, that is the distance between two targets are just the same as the distance between two visual lines, while looking at a far object. During the images of the targets are fused, the accommodation and convergence are relaxed concomitantly; thus a result of correction of pseudomyopia and prevention of myopia is achieved. By means of binocular fusion, the eye muscle exercises were conducted and resulted in not only the far point further but also the near point closer. The skiascopic examination carried out at the same time of binocular fusion showed that the degrees of relaxed accommodation was 97.9% that of looking at an object in far distance. The above results indicated that the binocular fusion method had excellent effect on the prevention of myopia. This method is simple and feasible, conforms to the visual physiology, and thus can be widely adopted.

Quasi-Monochromatic Visual Environments and the Resting Point of Accommodation

DTIC Science & Technology

1988-01-01

accommodation. No statistically significant differences were revealed to support the possibility of color mediated differential regression to resting...discussed with respect to the general findings of the total sample as well as the specific behavior of individual participants. The summarized statistics ...remaining ten varied considerably with respect to the averaged trends reported in the above descriptive statistics as well as with respect to precision

Compensation of Corneal Oblique Astigmatism by Internal Optics: a Theoretical Analysis

PubMed Central

Liu, Tao; Thibos, Larry N.

2017-01-01

Purpose Oblique astigmatism is a prominent optical aberration of peripheral vision caused by oblique incidence of rays striking the refracting surfaces of the cornea and crystalline lens. We inquired whether oblique astigmatism from these two sources should be expected, theoretically, to have the same or opposite signs across the visual field at various states of accommodation. Methods Oblique astigmatism was computed across the central visual field for a rotationally-symmetric schematic-eye using optical design software. Accommodative state was varied by altering the apical radius of curvature and separation of the biconvex lens’s two aspheric surfaces in a manner consistent with published biometry. Oblique astigmatism was evaluated separately for the whole eye, the cornea, and the isolated lens over a wide range of surface curvatures and asphericity values associated with the accommodating lens. We also computed internal oblique astigmatism by subtracting corneal oblique astigmatism from whole-eye oblique astigmatism. Results A visual field map of oblique astigmatism for the cornea in the Navarro model follows the classic, textbook description of radially-oriented axes everywhere in the field. Despite large changes in surface properties during accommodation, intrinsic astigmatism of the isolated human lens for collimated light is also radially oriented and nearly independent of accommodation both in theory and in real eyes. However, the magnitude of ocular oblique astigmatism is smaller than that of the cornea alone, indicating partial compensation by the internal optics. This implies internal oblique astigmatism (which includes wavefront propagation from the posterior surface of the cornea to the anterior surface of the lens and intrinsic lens astigmatism) must have tangentially-oriented axes. This non-classical pattern of tangential axes for internal astigmatism was traced to the influence of corneal power on the angles of incidence of rays striking the internal lens. Conclusions Partial compensation of corneal astigmatism by internal optics is due mainly to the highly converging nature of wavefronts incident upon the lens resulting from corneal refraction. The degree of compensation is quadratically dependent on eccentricity but is expected to diminish as the eye accommodates. Neutralising the cornea by index-matching defeats internal compensation, revealing classical, radially-oriented oblique astigmatism in the isolated lens. PMID:28281302

Temporal accommodation response measured by photorefractive accommodation measurement device

NASA Astrophysics Data System (ADS)

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

2017-02-01

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

Symptomatology associated with accommodative and binocular vision anomalies.

PubMed

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

2014-01-01

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

Multifocal planes head-mounted displays.

PubMed

Rolland, J P; Krueger, M W; Goon, A

2000-07-01

Stereoscopic head-mounted displays (HMD's) provide an effective capability to create dynamic virtual environments. For a user of such environments, virtual objects would be displayed ideally at the appropriate distances, and natural concordant accommodation and convergence would be provided. Under such image display conditions, the user perceives these objects as if they were objects in a real environment. Current HMD technology requires convergent eye movements. However, it is currently limited by fixed visual accommodation, which is inconsistent with real-world vision. A prototype multiplanar volumetric projection display based on a stack of laminated planes was built for medical visualization as discussed in a paper presented at a 1999 Advanced Research Projects Agency workshop (Sullivan, Advanced Research Projects Agency, Arlington, Va., 1999). We show how such technology can be engineered to create a set of virtual planes appropriately configured in visual space to suppress conflicts of convergence and accommodation in HMD's. Although some scanning mechanism could be employed to create a set of desirable planes from a two-dimensional conventional display, multiplanar technology accomplishes such function with no moving parts. Based on optical principles and human vision, we present a comprehensive investigation of the engineering specification of multiplanar technology for integration in HMD's. Using selected human visual acuity and stereoacuity criteria, we show that the display requires at most 27 equally spaced planes, which is within the capability of current research and development display devices, located within a maximal 26-mm-wide stack. We further show that the necessary in-plane resolution is of the order of 5 microm.

Driving time modulates accommodative response and intraocular pressure.

PubMed

Vera, Jesús; Diaz-Piedra, Carolina; Jiménez, Raimundo; Morales, José M; Catena, Andrés; Cardenas, David; Di Stasi, Leandro L

2016-10-01

Driving is a task mainly reliant on the visual system. Most of the time, while driving, our eyes are constantly focusing and refocusing between the road and the dashboard or near and far traffic. Thus, prolonged driving time should produce visual fatigue. Here, for the first time, we investigated the effects of driving time, a common inducer of driver fatigue, on two ocular parameters: the accommodative response (AR) and the intraocular pressure (IOP). A pre/post-test design has been used to assess the impact of driving time on both indices. Twelve participants (out of 17 recruited) completed the study (5 women, 24.42±2.84years old). The participants were healthy and active drivers with no visual impairment or pathology. They drove for 2h in a virtual driving environment. We assessed AR and IOP before and after the driving session, and also collected subjective measures of arousal and fatigue. We found that IOP and AR decreased (i.e., the accommodative lag increased) after the driving session (p=0.03 and p<0.001, respectively). Moreover, the nearest distances tested (20cm, 25cm, and 33cm) induced the highest decreases in AR (corrected p-values<0.05). Consistent with these findings, the subjective levels of arousal decreased and levels of fatigue increased after the driving session (all p-values<0.001). These results represent an innovative step towards an objective, valid, and reliable assessment of fatigue-impaired driving based on visual fatigue signs. Copyright © 2016 Elsevier Inc. All rights reserved.

[Monochromatic aberration in accommodation. Dynamic wavefront analysis].

PubMed

Fritzsch, M; Dawczynski, J; Jurkutat, S; Vollandt, R; Strobel, J

2011-06-01

Monochromatic aberrations may influence the visual acuity of the eye. They are not stable and can be affected by different factors. The subject of the following paper is the dynamic investigation of the changes in wavefront aberration with accommodation. Dynamic measurement of higher and lower order aberrations was performed with a WASCA Wavefront Analyzer (Carl-Zeiss-Meditec) and a specially constructed target device for aligning objects in far and near distances on 25 subjects aged from 15 to 27 years old. Wavefront aberrations showed some significant changes in accommodation. In addition to the characteristic sphere reaction accompanying miosis and changes in horizontal prism (Z(1) (1)) in the sense of a convergence movement of the eyeball also occurred. Furthermore defocus rose (Z(2) (0)) and astigmatism (Z(2) (-2)) changed. In higher-order aberrations a decrease in coma-like Zernike polynomials (Z(3) (-1), Z(3) (1)) was found. The most obvious change appeared in spherical aberration (Z(4) (0)) which increased and changed from positive to negative. In addition the secondary astigmatism (Z(4) (-2)) and quadrafoil (Z(4) (4)) rise also increased. The total root mean square (RMS), as well as the higher-order aberrations (RMS-HO) significantly increased in accommodation which is associated with a theoretical reduction of visual acuity. An analysis of the influence of pupil size on aberrations showed significant increases in defocus, spherical aberration, quadrafoil, RMS and RMS HO by increasing pupil diameter. By accommodation-associated miosis, the growing aberrations are partially compensated by focusing on near objects. Temporal analysis of the accommodation process with dynamic wavefront analysis revealed significant delays in pupil response and changing of prism in relation to the sphere reaction. In accommodation to near objects a discrete time ahead of third order aberrations in relation to the sphere response was found. Using dynamic wavefront measurement achieved a sequential analysis of aberrations during accommodation. Significant changes in the lower and higher-order aberrations could be detected. These are additionally varied by the associated pupillary response. Moreover, the synchronicity of wave front reaction in the accommodation process was proven.

The rate of change of vergence-accommodation conflict affects visual discomfort.

PubMed

Kim, Joohwan; Kane, David; Banks, Martin S

2014-12-01

Stereoscopic (S3D) displays create conflicts between the distance to which the eyes must converge and the distance to which the eyes must accommodate. Such conflicts require the viewer to overcome the normal coupling between vergence and accommodation, and this effort appears to cause viewer discomfort. Vergence-accommodation coupling is driven by the phasic components of the underlying control systems, and those components respond to relatively fast changes in vergence and accommodative stimuli. Given the relationship between phasic changes and vergence-accommodation coupling, we examined how the rate of change in the vergence-accommodation conflict affects viewer discomfort. We used a stereoscopic display that allows independent manipulation of the stimuli to vergence and accommodation. We presented stimuli that simulate natural viewing (i.e., vergence and accommodative stimuli changed together) and stimuli that simulate S3D viewing (i.e., vergence stimulus changes but accommodative stimulus remains fixed). The changes occurred at 0.01, 0.05, or 0.25 Hz. The lowest rate is too slow to stimulate the phasic components while the highest rate is well within the phasic range. The results were consistent with our expectation: somewhat greater discomfort was experienced when stimulus distance changed rapidly, particularly in S3D viewing when the vergence stimulus changed but the accommodative stimulus did not. These results may help in the generation of guidelines for the creation and viewing of stereo content with acceptable viewer comfort.

Clinical study of the influence of preoperative wearing time on postoperative effects in children with partially accommodative esotropia.

PubMed

Jiang, Danni; Han, Dong; Zhang, Jiahuan; Pei, Tianxu; Zhao, Qi

2018-05-01

The aim of this study was to evaluate the influence of the preoperative wearing time on the postoperative effect in children with partially accommodative esotropia.Sixty children with partially accommodative esotropia who visited our hospital were placed in full cycloplegic refraction by using 1% Atropine eye gel and then wore full hyperopic correction glasses. Children were divided into groups A and B according to the preoperative wearing time. The visual acuity, eye position, and results of the synoptophore and Titmus stereoacuity tests were recorded before and half a year after the surgery in each group, and appropriate statistical analyses were conducted.Half a year after the operation, 54 cases achieved orthotropia when wearing full hyperopic correction glasses. One case was overcorrected. Five cases were undercorrected. The results of the synoptophore and Titmus stereoacuity test showed that there was no significant difference between postoperative outcomes for patients who wore glasses for half a year and for 1 year before the operation.For children with partially accommodative esotropia, surgery should be used to correct the eye position after wearing full hyperopic correction glasses for half a year to improve the eye position and binocular vision as early as possible. If the operation cannot be completed after the patient wears full hyperopic correction glasses for half a year due to various subjective and objective factors, a good postoperative effect can be obtained if the patients receive surgery after wearing full hyperopic correction glasses for 1 year.

Change in convergence and accommodation after two weeks of eye exercises in typical young adults

PubMed Central

Horwood, Anna M.; Toor, Sonia S.; Riddell, Patricia M.

2014-01-01

Background Although eye exercises appear to help heterophoria, convergence insufficiency, and intermittent strabismus, results can be confounded by placebo, practice, and encouragement effects. This study assessed objective changes in vergence and accommodation responses in naive young adults after a 2-week period of eye exercises under controlled conditions to determine the extent to which treatment effects occur over other factors. Methods Asymptomatic young adults were randomly assigned to one of two no-treatment (control) groups or to one of six eye exercise groups: accommodation, vergence, both, convergence in excess of accommodation, accommodation in excess of convergence, and placebo. Subjects were tested and retested under identical conditions, except for the second control group, who were additionally encouraged. Objective accommodation and vergence were assessed to a range of targets moving in depth containing combinations of blur, disparity, and proximity/looming cues. Results A total of 156 subjects were included. Response gain improved more for less naturalistic targets where more improvement was possible. Convergence exercises improved vergence for near across all targets (P = 0.035). Mean accommodation changed similarly but nonsignificantly. No other treatment group differed significantly from the nonencouraged control group, whereas encouraging effort produced significantly increased vergence (P = 0.004) and accommodation (P = 0.005) gains in the second control group. Conclusions True treatment effects were small, significantly better only after vergence exercises to a nonaccommodative target, and rarely related to the response they were designed to improve. Exercising accommodation without convergence made no difference to accommodation to cues containing detail. Additional effort improved objective responses the most. PMID:24582466

Physics Learning Strategies with Multi-touch Technology

NASA Astrophysics Data System (ADS)

Potter, Mark; Ilie, C.; Schofield, D.

2011-03-01

Advancements in technology have opened doorways to build new teaching and learning methods. Through conjunctive use of these technologies and methods, a classroom can be enriched to stimulate and improve student learning. The purpose of our research is to ascertain whether or not multi-touch technology enhances students' abilities to better comprehend and retain the knowledge taught in physics. At their basis, students learn via visual, aural, reading/writing, and kinesthetic styles. Labs provide for all but the aural style, while lectures lack kinesthetic learning. Pedagogical research indicates that kinesthetic learning is a fundamental, powerful, and ubiquitous learning style. By using multi-touch technology in lecture, not only can we accommodate kinesthetic learners, but we can also enrich the experiences of visual learners. Ushering to this wider array of students will hopefully lead to an increase in meaningful learning.

Crystalens HD intraocular lens analysis using an adaptive optics visual simulator.

PubMed

Pérez-Vives, Cari; Montés-Micó, Robert; López-Gil, Norberto; Ferrer-Blasco, Teresa; García-Lázaro, Santiago

2013-12-01

To compare visual and optical quality of the Crystalens HD intraocular lens (IOL) with that of a monofocal IOL. The wavefront aberration patterns of the monocular Akreos Adapt AO IOL and the single-optic accommodating Crystalens HD IOL were measured in a model eye. The Crystalens IOL was measured in its nonaccommodative state and then, after flexing the haptic to produce 1.4 mm of movement, in its accommodative state. Using an adaptive optics system, subjects' aberrations were removed and replaced with those of pseudophakes viewing with either lens. Monocular distance visual acuity (DVA) at high (100%), medium (50%), and low (10%) contrast and contrast sensitivity (CS) were measured for both IOL optics. Near VA (NVA) and CS were measured for the Crystalens HD IOL in its accommodative state. Depth of focus around the distance and near focus was also evaluated for the Crystalens HD IOL. Modulation transfer function (MTF), point spread function (PSF), and Strehl ratio were also calculated. All measures were taken for 3- and 5-mm pupils. The MTF, PSF, and Strehl ratio showed comparable values between IOLs (p > 0.05). There were no significant differences in DVA and CS between IOLs for all contrasts and pupils (p > 0.05). When spherically focused, mean DVA and NVA with the Crystalens HD IOL were ≥20/20 at 100 and 50% contrasts for both pupils. Monocular DVA, NVA, and CS were slightly better with 3- than 5-mm pupils, but without statistically significant differences. The Crystalens HD IOL showed about 0.75 and 0.50 D of depth of focus in its accommodative state and nonaccommodative state, respectively. The optical and visual quality with the nonaccommodatied Crystalens HD IOL was comparable to that of a monofocal IOL. If this lens can move 1.4 mm in the eye, it will provide high-quality optics for near vision as well.

Comparison of visual function between phakic eyes and pseudophakic eyes with a monofocal intraocular lens.

PubMed

Hayashi, Ken; Yoshida, Motoaki; Manabe, Shin-ichi; Hayashi, Hideyuki

2010-01-01

To compare all-distance visual acuity and contrast visual acuity with and without glare (glare visual acuity) between phakic eyes with a clear lens and pseudophakic eyes with a monofocal intraocular lens. Hayashi Eye Hospital, Fukuoka, Japan. This study comprised phakic), pseudophakic eyes in 4 age groups (40s, 50s, 60s, 70s). Corrected visual acuity from far to near, contrast visual acuity, and glare visual acuity were examined. The mean corrected intermediate and near visual acuities were significantly better in phakic eyes than in pseudophakic eyes in patients in their 40s and 50s (P

Change in the accommodative convergence per unit of accommodation ratio after bilateral laser in situ keratomileusis for myopia in orthotropic patients: prospective evaluation.

PubMed

Prakash, Gaurav; Choudhary, Vandana; Sharma, Namrata; Titiyal, Jeewan S

2007-12-01

To analyze the effect of bilateral laser in situ keratomileusis (LASIK) on the accommodative convergence per unit of accommodation (AC/A) ratio in otherwise normal orthotropic myopic patients. Cornea and refractive services of a tertiary-care ophthalmic center. This prospective clinical trial consisted of 61 myopic patients who had bilateral LASIK. Those with manifest tropia, previous squint surgery, amblyopia, or absent or impaired binocularity or those in whom monovision was planned were excluded. The preoperative examination included visual acuity, cycloplegic refraction, assessment of binocularity, a prism cover test, and evaluation of the stimulus AC/A ratio by the gradient method. All patients had LASIK using the Zyoptix platform (Bausch & Lomb). Postoperative evaluation included uncorrected and best corrected visual acuities, residual refraction, and the AC/A ratio. All patients had a follow-up of 9 months. There was significant decrease in the mean AC/A ratio at the 1-week and 1-month follow-ups. The AC/A progressively recovered to near preoperative values between 3 months and 9 months after surgery (analysis of variance test). There was a significant reduction in the number of symptomatic patients from the first month onward (chi square = 89.23; P<.001). The AC/A ratio varied after LASIK, stabilizing between 3 months and 9 months after surgery. This suggests that the maximum variation in the accommodation-convergence relationship after LASIK occurs in the first 3 months.

Living Independently: Exploring the Experiences of Visually Impaired People Living in Age-Related and Lifetime Housing Through Qualitative Synthesis.

PubMed

Rooney, Clíona; Hadjri, Karim; Faith, Verity; Rooney, Máirin; McAllister, Keith; Craig, Cathy

2017-01-01

The aim of this study is to gain a deeper understanding of the experiences of visually impaired older people living independently at home. As populations are aging globally, there is now an increase in the prevalence of visual impairment. That means for ongoing and future aging-in-place strategies that seek to enable older people to remain independent for longer, more attention needs to be given to the needs of those with visual impairment. As people develop visual impairment, they use adaptive strategies including modifying long-term homes or relocating to more suitable accommodation. In the United Kingdom, aging-in-place strategies include employing statutory lifetime home standards (LTHS) in the home or relocating to sheltered housing to live independently with support available if required. To get a better understanding of the needs of the visually impaired in the home, 12 interviews with six visually impaired occupants of LTHS homes and six from sheltered accommodation were analyzed separately using interpretative phenomenological analysis. Secondly, qualitative synthesis was used to further analyze themes generated from both samples before interview results were conceptualized in two superordinate concepts, namely, "negotiating priorities" and "understanding visual impairment." Participants from both groups had similar needs and were willing to compromise by living with some negative features. Those who coped well with moving utilized various resources. These findings will shed more understanding on providing good quality housing for those with visual impairment wanting to live either independently or within healthcare home environments.

Extralenticular and lenticular aspects of accommodation and presbyopia in human versus monkey eyes.

PubMed

Croft, Mary Ann; McDonald, Jared P; Katz, Alexander; Lin, Ting-Li; Lütjen-Drecoll, Elke; Kaufman, Paul L

2013-07-26

To determine if the accommodative forward movements of the vitreous zonule and lens equator occur in the human eye, as they do in the rhesus monkey eye; to investigate the connection between the vitreous zonule posterior insertion zone and the posterior lens equator; and to determine which components-muscle apex width, lens thickness, lens equator position, vitreous zonule, circumlental space, and/or other intraocular dimensions, including those stated in the objectives above-are most important in predicting accommodative amplitude and presbyopia. Accommodation was induced pharmacologically in 12 visually normal human subjects (ages 19-65 years) and by midbrain electrical stimulation in 11 rhesus monkeys (ages 6-27 years). Ultrasound biomicroscopy imaged the entire ciliary body, anterior and posterior lens surfaces, and the zonule. Relevant distances were measured in the resting and accommodated eyes. Stepwise regression analysis determined which variables were the most important predictors. The human vitreous zonule and lens equator move forward (anteriorly) during accommodation, and their movements decline with age, as in the monkey. Over all ages studied, age could explain accommodative amplitude, but not as well as accommodative lens thickening and resting muscle apex thickness did together. Accommodative change in distances between the vitreous zonule insertion zone and the posterior lens equator or muscle apex were important for predicting accommodative lens thickening. Our findings quantify the movements of the zonule and ciliary muscle during accommodation, and identify their age-related changes that could impact the optical change that occurs during accommodation and IOL function.

[Analysis and evaluation of the visual effort in remote-control public traffic operators working with computer-based equipments].

PubMed

Gullà, F; Zambelli, P; Bergamaschi, A; Piccoli, B

2007-01-01

The aim of this study is the objective evaluation of the visual effort in 6 public traffic controllers (4 male, 2 female, mean age 29,6), by means of electronic equipment. The electronic equipment quantify the observation distance and the observation time for each controller's occupational visual field. The quantification of these parameters is obtained by the emission of ultrasound at 40 KHz from an emission sensor (placed by the VDT screen) and the ultrasound reception by means of a receiving sensor (placed on the operator's head). The travelling time of the ultrasound (US), as the air speed is known and costant (about 340 m/s), it is used to calculate the distance between the emitting and the receiving sensor. The results show that the visual acuity required is of average level, while accommodation's and convergence's effort vary from average to intense (depending on the visual characteristics of the operator considered), ranging from 26,41 and 43,92% of accommodation and convergence available in each operator. The time actually spent in "near observation within the c.v.p." (Tscr) was maintained in a range from 2h 54' and 4h 05'.

[Impairment of safety in navigation caused by alcohol: impact on visual function].

PubMed

Grütters, G; Reichelt, J A; Ritz-Timme, S; Thome, M; Kaatsch, H J

2003-05-01

So far in Germany, no legally binding standards for blood alcohol concentration exist that prove an impairment of navigability. The aim of our interdisciplinary project was to obtain data in order to identify critical blood alcohol limits. In this context the visual system seems to be of decisive importance. 21 professional skippers underwent realistic navigational demands soberly and alcoholized in a sea traffic simulator. The following parameters were considered: visual acuity, stereopsis, color vision, and accommodation. Under the influence of alcohol (average blood alcohol concentration: 1.08 per thousand ) each skipper considered himself to be completely capable of navigating. While simulations were running, all of the skippers made nautical mistakes or underestimated dangerous situations. Severe impairment in visual acuity or binocular function were not observed. Accommodation decreased by an average of 18% ( p=0.0001). In the test of color vision skippers made more mistakes ( p=0.017) and the time needed for this test was prolonged ( p=0.004). Changes in visual function as well as vegetative and psychological reactions could be the cause of mistakes and alcohol should therefore be regarded as a severe risk factor for security in sea navigation.

Accommodation and convergence in 10-year-old prematurely born and full-term children: a population-based study.

PubMed

Larsson, Eva; Rydberg, Agneta; Holmström, Gerd

2012-09-01

To examine the accommodative amplitude and convergence in 10-year-old prematurely born children previously screened for retinopathy of prematurity (ROP) and to compare with full-term controls of the same age. Two-hundred and thirteen prematurely born and 217 children born at term were included. Accommodative amplitude and near-point convergence were assessed, together with best-corrected visual acuity (VA). A questionnaire was answered regarding possible problems at school. Binocular accommodation (P = 0.03) and convergence (P = 0.003) were significantly poorer in prematurely born children. Accommodation was correlated to neurological findings in the preterm group, but not to the degree of prematurity or stage of ROP. Regarding convergence there were no correlations to neurology, stage of ROP, or degree of prematurity. For neither accommodation nor convergence were any correlations with distance and near VA found. Preterm children had a higher prevalence of school problems, and there was an association with poor accommodation. Prematurely born children had poorer accommodation and convergence than full-term children, but no association with near VA was found. The reduction of accommodative amplitude and convergence was small and was probably of little clinical significance. However, it may have additional effects on other ophthalmological problems and school problems in the preterm group.

Chromatic aberration, accommodation, and color preference in asthenopia.

PubMed

Drew, Stefanie A; Borsting, Eric; Stark, Lawrence R; Chase, Chris

2012-07-01

Asthenopia is a common problem associated with near work and reports suggest that colored lenses or overlays may be applied to reduce symptoms. In this study, we examine the relationship between eyestrain, color preferences, and function of the accommodation and vergence system. Specifically, we examine whether symptomatic observers select colors that reduce accommodative demand based on longitudinal chromatic aberration (LCA). Forty-seven undergraduate students participated in this study. Visual discomfort symptoms were assessed using the Conlon survey. A Mark 2 Intuitive Colorimeter was used to obtain optimal colored light preferences. LCA was modeled using the Chromatic Eye and spectral power density data. A comprehensive evaluation of accommodation and vergence was performed following standard procedures. A significant negative correlation (r = -0.51) was found between eyestrain symptoms and the International Commission on Illumination (CIE) v' axis of colors preferences. Additionally, a significant negative correlation (r = -0.31) was found between eyestrain symptoms and LCA accommodation. Two thirds of the participants in the high discomfort group chose colors that decreased accommodative demand. Accommodative amplitude and vergence facility also correlated with LCA, accounting for 25% of the variance. The color preferences of individuals are systematically influenced by the functioning of their accommodation and vergence systems with increased symptomatology resulting in color selections that reduce LCA accommodative stimulus demand.

Locomotion Enhances Neural Encoding of Visual Stimuli in Mouse V1

PubMed Central

2017-01-01

Neurons in mouse primary visual cortex (V1) are selective for particular properties of visual stimuli. Locomotion causes a change in cortical state that leaves their selectivity unchanged but strengthens their responses. Both locomotion and the change in cortical state are thought to be initiated by projections from the mesencephalic locomotor region, the latter through a disinhibitory circuit in V1. By recording simultaneously from a large number of single neurons in alert mice viewing moving gratings, we investigated the relationship between locomotion and the information contained within the neural population. We found that locomotion improved encoding of visual stimuli in V1 by two mechanisms. First, locomotion-induced increases in firing rates enhanced the mutual information between visual stimuli and single neuron responses over a fixed window of time. Second, stimulus discriminability was improved, even for fixed population firing rates, because of a decrease in noise correlations across the population. These two mechanisms contributed differently to improvements in discriminability across cortical layers, with changes in firing rates most important in the upper layers and changes in noise correlations most important in layer V. Together, these changes resulted in a threefold to fivefold reduction in the time needed to precisely encode grating direction and orientation. These results support the hypothesis that cortical state shifts during locomotion to accommodate an increased load on the visual system when mice are moving. SIGNIFICANCE STATEMENT This paper contains three novel findings about the representation of information in neurons within the primary visual cortex of the mouse. First, we show that locomotion reduces by at least a factor of 3 the time needed for information to accumulate in the visual cortex that allows the distinction of different visual stimuli. Second, we show that the effect of locomotion is to increase information in cells of all layers of the visual cortex. Third, we show that the means by which information is enhanced by locomotion differs between the upper layers, where the major effect is the increasing of firing rates, and in layer V, where the major effect is the reduction in noise correlations. PMID:28264980

Change in peripheral refraction and curvature of field of the human eye with accommodation

NASA Astrophysics Data System (ADS)

Ho, Arthur; Zimmermann, Frederik; Whatham, Andrew; Martinez, Aldo; Delgado, Stephanie; Lazon de la Jara, Percy; Sankaridurg, Padmaja

2009-02-01

Recent research showed that the peripheral refractive state is a sufficient stimulus for myopia progression. This finding led to the suggestion that devices that control peripheral refraction may be efficacious in controlling myopia progression. This study aims to understand whether the optical effect of such devices may be affected by near focus. In particular, we seek to understand the influence of accommodation on peripheral refraction and curvature of field of the eye. Refraction was measured in twenty young subjects using an autorefractor at 0° (i.e. along visual axis), and 20°, 30° and 40° field angles both nasal and temporal to the visual axis. All measurements were conducted at 2.5 m, 40 cm and 30 cm viewing distances. Refractive errors were corrected using a soft contact lens during all measurements. As field angle increased, refraction became less hyperopic. Peripheral refraction also became less hyperopic at nearer viewing distances (i.e. with increasing accommodation). Astigmatism (J180) increased with field angle as well as with accommodation. Adopting a third-order aberration theory approach, the position of the Petzval surface relative to the retinal surface was estimated by considering the relative peripheral refractive error (RPRE) and J180 terms of peripheral refraction. Results for the estimated dioptric position of the Petzval surface relative to the retina showed substantial asymmetry. While temporal field tended to agree with theoretical predictions, nasal response departed dramatically from the model eye predictions. With increasing accommodation, peripheral refraction becomes less hyperopic while the Petzval surface showed asymmetry in its change in position. The change in the optical components (i.e. cornea and/or lens as opposed to retinal shape or position) is implicated as at least one of the contributors of this shift in peripheral refraction during accommodation.

Visualizing Sound with an Electro-Optical Eardrum

NASA Astrophysics Data System (ADS)

Truncale, Nicholas P.; Graham, Michelle T.

2014-02-01

As science educators, one of our important responsibilities is ensuring students possess the proper tools and accommodations to examine phenomena in a laboratory setting. It is our job to innovate methods enabling students with disabilities to participate in all aspects of investigations. This article describes an experimental accommodation allowing a deaf student to determine and plot the sensitivity of an electro-optical eardrum in the sound range of 10-150 Hz.

Optical systems in ergophthalmology

NASA Astrophysics Data System (ADS)

Kovalenko, Valentina; Besedovskaya, Valentina; Paloob, Tamara

1994-02-01

The important part of ergophthalmology is the problem of diagnosing and treatment of refraction errors, accommodation and visual disorders by means of the special optical systems. The using of our diagnostical approach helps to choose the right treatment strategy. Our therapeutical approach permits to normalize the muscle tonus and working capacity of eye accommodation apparatus and gives the possibility to obtain the stable positive results in treatment of the refraction amblyopia as well.

Integrated remote sensing and visualization (IRSV) system for transportation infrastructure operations and management, phase two, volume 1 : outreach and commercialization of IRSV prototype.

DOT National Transportation Integrated Search

2012-03-01

The Integrated Remote Sensing and Visualization System (IRSV) was developed in Phase One of this project in order to : accommodate the needs of todays Bridge Engineers at the state and local level. Overall goals of this project are: : Better u...

Integrated remote sensing and visualization (IRSV) system for transportation infrastructure operations and management, phase one, volume 2 : knowledge modeling and database development.

DOT National Transportation Integrated Search

2009-12-01

The Integrated Remote Sensing and Visualization System (IRSV) is being designed to accommodate the needs of todays Bridge Engineers at the : state and local level from several aspects that were documented in Volume One, Summary Report. The followi...

Intraocular Lenses for the Treatment of Age-Related Cataracts

PubMed Central

2009-01-01

Executive Summary Objective The objective of the report is to examine the comparative effectiveness and cost-effectiveness of various intraocular lenses (IOLs) for the treatment of age-related cataracts. Clinical Need: Target Population and Condition A cataract is a hardening and clouding of the normally transparent crystalline lens that may result in a progressive loss of vision depending on its size, location and density. The condition is typically bilateral, seriously compromises visual acuity and contrast sensitivity and increases glare. Cataracts can also affect people at any age, however, they usually occur as a part of the natural aging process. The occurrence of cataracts increases with age from about 12% at age 50 years, to 60% at age 70. In general, approximately 50% of people 65 year of age or older have cataracts. Mild cataracts can be treated with a change in prescription glasses, while more serious symptoms are treated by surgical removal of the cataract and implantation of an IOL. In Ontario, the estimated prevalence of cataracts increased from 697,000 in 1992 to 947,000 in 2004 (35.9% increase, 2.4% annual increase). The number of cataract surgeries per 1,000 individuals at risk of cataract increased from 64.6 in 1992 to 140.4 in 1997 (61.9% increase, 10.1% annual increase) and continued to steadily increase to 115.7 in 2004 (10.7% increase, 5.2% increase per year). Description of Technology/Therapy IOLs are classified either as monofocal, multifocal, or accommodative. Traditionally, monofocal (i.e.. fixed focusing power) IOLs are available as replacement lenses but their implantation can cause a loss of the eye’s accommodative capability (which allows variable focusing). Patients thus usually require eyeglasses after surgery for reading and near vision tasks. Multifocal IOLs aim to improve near and distant vision and obviate the need for glasses. Potential disadvantages include reduced contrast sensitivity, halos around lights and glare. Accommodating IOLs are designed to move with ciliary body contraction during accommodation and, therefore, offer a continuous range of vision (i.e. near, intermediate and distant vision) without the need for glasses. Purported advantages over multifocal IOLs include the avoidance of haloes and no reduction in contrast sensitivity. Polymethyl methacrylate (PMMA) was the first material used in the fabrication of IOLs and has inherent ultraviolet blocking abilities. PMMA IOLs are inflexible, however, and require a larger incision for implantation compared with newer foldable silicone (hydrophobic) and acrylic (hydrophobic or hydrophilic) lenses. IOLs can be further sub-classified as being either aspheric or spheric, blue/violet filtered or non-filtered or 1- or 3-piece. Methods of Evidence-Based Analysis A literature search was conducted from January 2003 to January 2009 that included OVID MEDLINE, MEDLINE In-Process and Other Non-Indexed Citations, EMBASE, the Cumulative Index to Nursing & Allied Health Literature (CINAHL), The Cochrane Library, and the International Agency for Health Technology Assessment/Centre for Review and Dissemination. Inclusion Criteria Exclusion Criteria adult patients with age-related cataractssystematic reviews, randomized controlled trials (RCTs)primary outcomes: distance visual acuity (best corrected distance visual acuity), near visual acuity (best distance corrected near visual acuity)secondary outcomes: contrast sensitivity, depth of field, glare, quality of life, visual function, spectacle dependence, posterior capsule opacification. studies with fewer than 20 eyesIOLs for non-age related cataractsIOLs for presbyopiastudies with a mean follow-up <6monthsstudies reporting insufficient data for analysis Comparisons of Interest The primary comparison of interest was accommodative vs. multifocal vs. monofocal lenses. Secondary comparisons of interest included: tinted vs. non-tinted lenses aspheric vs. spheric lenses multipiece vs. single piece lenses biomaterial A (e.g. acrylic) vs. biomaterial B (e.g. silicone) lenses sharp vs. round edged lenses The quality of the studies was examined according to the GRADE Working Group criteria for grading quality of evidence for interventional procedures. Summary of Findings The conclusions of the systematic review of IOLs for age-related cataracts are summarized in Executive Summary Table 1. Considerations for the Ontario Health System Procedures for crystalline lens removal and IOL insertion are insured and listed in the Ontario Schedule of Benefits. If a particular lens is determined to be medically necessary for a patient, the cost of the lens is covered by the hospital budget. If the patient chooses a lens that has enhanced features, then the hospital may choose to charge an additional amount above the cost of the usual lens offered. An IOL manufacturer stated that monofocal lenses comprise approximately 95% of IOL sales in Ontario and premium lenses (e.g., multifocal/accomodative) consist of about 5% of IOL sales. A medical consultant stated that all types of lenses are currently being used in Ontario (e.g., multifocal, monofocal, accommodative, tinted, nontinted, spheric, and aspheric). Nonfoldable lenses, rarely used in routine cases, are primarily used for complicated cataract implantation situations. ES Table 1: Conclusions for the Systematic Review of IOLs for Age-Related Cataracts Comparison Conclusion GRADE Quality Multifocal vs. monofocal Objective OutcomesSignificant improvement in BDCUNVANo significant difference in BCDVAInconclusive evidence for contrast sensitivityInconclusive evidence for glareSubjective OutcomesInconclusive evidence for visual satisfactionSignificant increase in glare/halosSignificant increase in freedom from spectacles moderatemoderatelowvery lowlowlow/moderatelow/moderate Accommodative vs. multifocal/monofocal Inconclusive due to Insufficient limited evidence for any effectiveness outcome very low Hydrophilic acrylic vs. other materials (hydrophobic acrylic, silicone) Significant increase in PCO score Low Sharp edged compared to round edged Significant reduction in PCO score Low One piece compared to three piece No significant difference in PCO score low Hydrophobic acrylic compared to silicone No significant difference in PCO score moderate Aspherical modified prolate anterior surface compared to spherical No significant difference in VASignificant reduction in contrast sensitivity very lowvery low Blue light filtering compared to non blue-light filtering No significant difference in BCDVANo significant difference in contrast sensitivityNo significant difference in HRQL lowlowhigh/moderate BCDVA refers to best corrected distance visual acuity; BDCUNVA, best distance corrected unaided near visual acuity; HRQL, health related quality of life; PCO, posterior capsule opacification; VA, visual acuity. PMID:23074519

Characteristics of visual fatigue under the effect of 3D animation.

PubMed

Chang, Yu-Shuo; Hsueh, Ya-Hsin; Tung, Kwong-Chung; Jhou, Fong-Yi; Lin, David Pei-Cheng

2015-01-01

Visual fatigue is commonly encountered in modern life. Clinical visual fatigue characteristics caused by 2-D and 3-D animations may be different, but have not been characterized in detail. This study tried to distinguish the differential effects on visual fatigue caused by 2-D and 3-D animations. A total of 23 volunteers were subjected to accommodation and vergence assessments, followed by a 40-min video game program designed to aggravate their asthenopic symptoms. The volunteers were then assessed for accommodation and vergence parameters again and directed to watch a 5-min 3-D video program, and then assessed again for the parameters. The results support that the 3-D animations caused similar characteristics in vision fatigue parameters in some specific aspects as compared to that caused by 2-D animations. Furthermore, 3-D animations may lead to more exhaustion in both ciliary and extra-ocular muscles, and such differential effects were more evident in the high demand of near vision work. The current results indicated that an arbitrary set of indexes may be promoted in the design of 3-D display or equipments.

Change in convergence and accommodation after two weeks of eye exercises in typical young adults.

PubMed

Horwood, Anna M; Toor, Sonia S; Riddell, Patricia M

2014-04-01

Although eye exercises appear to help heterophoria, convergence insufficiency, and intermittent strabismus, results can be confounded by placebo, practice, and encouragement effects. This study assessed objective changes in vergence and accommodation responses in naive young adults after a 2-week period of eye exercises under controlled conditions to determine the extent to which treatment effects occur over other factors. Asymptomatic young adults were randomly assigned to one of two no-treatment (control) groups or to one of six eye exercise groups: accommodation, vergence, both, convergence in excess of accommodation, accommodation in excess of convergence, and placebo. Subjects were tested and retested under identical conditions, except for the second control group, who were additionally encouraged. Objective accommodation and vergence were assessed to a range of targets moving in depth containing combinations of blur, disparity, and proximity/looming cues. A total of 156 subjects were included. Response gain improved more for less naturalistic targets where more improvement was possible. Convergence exercises improved vergence for near across all targets (P = 0.035). Mean accommodation changed similarly but nonsignificantly. No other treatment group differed significantly from the nonencouraged control group, whereas encouraging effort produced significantly increased vergence (P = 0.004) and accommodation (P = 0.005) gains in the second control group. True treatment effects were small, significantly better only after vergence exercises to a nonaccommodative target, and rarely related to the response they were designed to improve. Exercising accommodation without convergence made no difference to accommodation to cues containing detail. Additional effort improved objective responses the most. Copyright © 2014 American Association for Pediatric Ophthalmology and Strabismus. Published by Mosby, Inc. All rights reserved.

Accommodative spasm with bilateral vision loss due to untreated intermittent exotropia in an adult.

PubMed

Shanker, V; Ganesh, S; Sethi, S

2012-01-01

Intermittent exotropia (IXT) is an exodeviation intermittently controlled by fusional mechanisms. Patients with IXT may present with asthenopic symptoms, blurred vision, headaches, diplopia or visual confusion and reading difficulties; especially after prolonged periods of near work. To report the presentation and management of a young adult with intractable accommodative spasm secondary to long standing intermittent exotropia. The patient was found to have bilateral accommodative spasm with high pseudomyopia and severe impairment of vision. There was a tendency for recurrence with discontinuation of cycloplegics. A total relief of symptoms was noticed after strabismus surgery was undertaken for the exotropia. A detailed orthoptic evaluation with emphasis on recognizing accommodative spasm as an unusual presentation of IXT, could aid in appropriate diagnosis and treatment of such cases. © NEPjOPH.

The Rate of Change of Vergence-Accommodation Conflict Affects Visual Discomfort

PubMed Central

Kane, David; Banks, Martin S.

2014-01-01

Stereoscopic (S3D) displays create conflicts between the distance to which the eyes must converge and the distance to which the eyes must accommodate. Such conflicts require the viewer to overcome the normal coupling between vergence and accommodation, and this effort appears to cause viewer discomfort. Vergence-accommodation coupling is driven by the phasic components of the underlying control systems, and those components respond to relatively fast changes in vergence and accommodative stimuli. Given the relationship between phasic changes and vergence-accommodation coupling, we examined how the rate of change in the vergence-accommodation conflict affects viewer discomfort. We used a stereoscopic display that allows independent manipulation of the stimuli to vergence and accommodation. We presented stimuli that simulate natural viewing (i.e., vergence and accommodative stimuli changed together) and stimuli that simulate S3D viewing (i.e., vergence stimulus changes but accommodative stimulus remains fixed). The changes occurred at 0.01, 0.05, or 0.25Hz. The lowest rate is too slow to stimulate the phasic components while the highest rate is well within the phasic range. The results were consistent with our expectation: somewhat greater discomfort was experienced when stimulus distance changed rapidly, particularly in S3D viewing when the vergence stimulus changed but the accommodative stimulus did not. These results may help in the generation of guidelines for the creation and viewing of stereo content with acceptable viewer comfort. PMID:25448713

The moon illusion revisited.

PubMed

Iavecchia, J H; Iavecchia, H P; Roscoe, S N

1983-01-01

In two experiments, the apparent size of a simulated horizon moon was measured as a function of the location of visible texture in the natural vistas against which it appeared. Size was found to increase as the visible scene extended farther into the distance and to decrease as the moon rose above the vista of surface texture. In the second experiment, the observers' eye accommodation distances to various scenes were also measured with a laser optometer, and after appropriate transformations, size judgments were found to correlate 0.89 with measured accommodation values, thereby suggesting the hypothesis that the fabled moon illusion is mediated by the oculomotor adjustments of visual accommodation.

Visual training improves underwater vision in children.

PubMed

Gislén, Anna; Warrant, Eric J; Dacke, Marie; Kröger, Ronald H H

2006-10-01

Children in a tribe of sea-gypsies from South-East Asia have been found to have superior underwater vision compared to European children. In this study, we show that the improved underwater vision of these Moken children is not due to better contrast sensitivity in general. We also show that European children can achieve the same underwater acuity as the Moken children. After 1 month of underwater training (11 sessions) followed by 4 months with no underwater activities, European children showed improved underwater vision and distinct bursts of pupil constriction. When tested 8 months after the last training session in an outdoor pool in bright sunlight-comparable to light environments in South-East Asia-the children had attained the same underwater acuity as the sea-gypsy children. The achieved performance can be explained by the combined effect of pupil constriction and strong accommodation.

Visual skills involved in decision making by expert referees.

PubMed

Ghasemi, Abdollah; Momeni, Maryam; Jafarzadehpur, Ebrahim; Rezaee, Meysam; Taheri, Hamid

2011-02-01

Previous studies have compared visual skills of expert and novice athletes; referees' performance has not been addressed. Visual skills of two groups of expert referees, successful and unsuccessful in decision making, were compared. Using video clips of soccer matches to assess decision-making success of 41 national and international referees from 31 to 42 years of age, 10 top referees were selected as the Successful group and 10 as the Unsuccessful group. Visual tests included visual memory, visual reaction time, peripheral vision, recognition speed, saccadic eye movement, and facility of accommodation. The Successful group had better visual skills than the Unsuccessful group. Such visual skills enhance soccer referees' performance and may be recommended for young referees.

Long-term follow-up of acute isolated accommodation insufficiency.

PubMed

Lee, Jung Jin; Baek, Seung-Hee; Kim, Ungsoo Samuel

2013-04-01

To define the long-term results of accommodation insufficiency and to investigate the correlation between accommodation insufficiency and other factors including near point of convergence (NPC), age, and refractive errors. From January 2008 to December 2009, 11 patients with acute near vision disturbance and remote near point of accommodation (NPA) were evaluated. Full ophthalmologic examinations, including best corrected visual acuity, manifest refraction and prism cover tests were performed. Accommodation ability was measured by NPA using the push-up method. We compared accommodation insufficiency and factors including age, refractive errors and NPC. We also investigated the recovery from loss of accommodation in patients. Mean age of patients was 20 years (range, 9 to 34 years). Five of the 11 patients were female. Mean refractive error was -0.6 diopters (range, -3.5 to +0.25 diopters) and 8 of 11 patients (73%) had emmetropia (+0.50 to -0.50 diopters). No abnormalities were found in brain imaging tests. Refractive errors were not correlated with NPA or NPC (rho = 0.148, p = 0.511; rho = 0.319, p = 0.339; respectively). The correlation between age and NPA was not significant (rho = -395, p = 0.069). However, the correlation between age and NPC was negative (rho = -0.508, p = 0.016). Three of 11 patients were lost to follow-up, and 6 of 8 patients had permanent insufficiency of accommodation. Accommodation insufficiency is most common in emmetropia, however, refractive errors and age are not correlated with accommodation insufficiency. Dysfunction of accommodation can be permanent in the isolated accommodation insufficiency.

Long-term Follow-up of Acute Isolated Accommodation Insufficiency

PubMed Central

Lee, Jung Jin; Baek, Seung-Hee

2013-01-01

Purpose To define the long-term results of accommodation insufficiency and to investigate the correlation between accommodation insufficiency and other factors including near point of convergence (NPC), age, and refractive errors. Methods From January 2008 to December 2009, 11 patients with acute near vision disturbance and remote near point of accommodation (NPA) were evaluated. Full ophthalmologic examinations, including best corrected visual acuity, manifest refraction and prism cover tests were performed. Accommodation ability was measured by NPA using the push-up method. We compared accommodation insufficiency and factors including age, refractive errors and NPC. We also investigated the recovery from loss of accommodation in patients. Results Mean age of patients was 20 years (range, 9 to 34 years). Five of the 11 patients were female. Mean refractive error was -0.6 diopters (range, -3.5 to +0.25 diopters) and 8 of 11 patients (73%) had emmetropia (+0.50 to -0.50 diopters). No abnormalities were found in brain imaging tests. Refractive errors were not correlated with NPA or NPC (rho = 0.148, p = 0.511; rho = 0.319, p = 0.339; respectively). The correlation between age and NPA was not significant (rho = -395, p = 0.069). However, the correlation between age and NPC was negative (rho = -0.508, p = 0.016). Three of 11 patients were lost to follow-up, and 6 of 8 patients had permanent insufficiency of accommodation. Conclusions Accommodation insufficiency is most common in emmetropia, however, refractive errors and age are not correlated with accommodation insufficiency. Dysfunction of accommodation can be permanent in the isolated accommodation insufficiency. PMID:23543051

Extralenticular and Lenticular Aspects of Accommodation and Presbyopia in Human Versus Monkey Eyes

PubMed Central

Croft, Mary Ann; McDonald, Jared P.; Katz, Alexander; Lin, Ting-Li; Lütjen-Drecoll, Elke; Kaufman, Paul L.

2013-01-01

Purpose. To determine if the accommodative forward movements of the vitreous zonule and lens equator occur in the human eye, as they do in the rhesus monkey eye; to investigate the connection between the vitreous zonule posterior insertion zone and the posterior lens equator; and to determine which components—muscle apex width, lens thickness, lens equator position, vitreous zonule, circumlental space, and/or other intraocular dimensions, including those stated in the objectives above—are most important in predicting accommodative amplitude and presbyopia. Methods. Accommodation was induced pharmacologically in 12 visually normal human subjects (ages 19–65 years) and by midbrain electrical stimulation in 11 rhesus monkeys (ages 6–27 years). Ultrasound biomicroscopy imaged the entire ciliary body, anterior and posterior lens surfaces, and the zonule. Relevant distances were measured in the resting and accommodated eyes. Stepwise regression analysis determined which variables were the most important predictors. Results. The human vitreous zonule and lens equator move forward (anteriorly) during accommodation, and their movements decline with age, as in the monkey. Over all ages studied, age could explain accommodative amplitude, but not as well as accommodative lens thickening and resting muscle apex thickness did together. Accommodative change in distances between the vitreous zonule insertion zone and the posterior lens equator or muscle apex were important for predicting accommodative lens thickening. Conclusions. Our findings quantify the movements of the zonule and ciliary muscle during accommodation, and identify their age-related changes that could impact the optical change that occurs during accommodation and IOL function. PMID:23745002

A Review of Worksite Lactation Accommodations.

PubMed

Hilliard, Elizabeth Dianne

2017-01-01

The purpose of this review was to examine workplace lactation accommodations, and their association with breastfeeding duration, and identify strategies occupational health professionals can use to promote lactation improvements. This study included literature published from 1985 through 2015 and listed in PubMed and CINAHL. Using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), 11 articles were identified for review. Presence of a corporate lactation program, on-site child care, and return to work/telephone lactation consultation were consistently associated with breastfeeding at 6 months. Other breastfeeding accommodations (i.e., lactation spaces, lactation breaks, worksite lactation policies, and supervisor/coworker support) were not consistently associated with breastfeeding duration. Occupational health professionals can play key roles in improving the effectiveness of lactation accommodations. Assuring adequate implementation of accommodations, increasing communication and marketing of accommodations, and promoting supervisor and coworker support are areas that occupational health professionals should explore for improving lactation duration.

A neuroergonomic quasi-experiment: Predictors of situation awareness and display usability while performing complex tasks

NASA Astrophysics Data System (ADS)

Harbour, Steven D.; Christensen, James C.

2015-05-01

Situation awareness (SA) is the ability and capacity to perceive information and act on it acceptably. Head Up Display (HUD) versus Head Down Display (HDD) manipulation induced variation in task difficulty. HUD and HDD cockpit displays or display designs promoted or impaired SA. The quantitative research presented in this paper examines basic neurocognitive factors in order to identify their specific contributions to the formation of SA, while studying display usability and the effects on SA. Visual attentiveness (Va), perceptiveness (Vp), and spatial working memory (Vswm) were assessed as predictors of SA under varying task difficulty. The study participants were 19 tactical airlift pilots, selected from the Ohio Air National Guard. Neurocognitive tests were administered to the participants prior to flight. In-flight SA was objectively and subjectively assessed for 24 flights. At the completion of this field experiment, the data were analyzed and the tests were statistically significant for the three predictor visual abilities Vp, Va, and Vswm as task difficulty was varied, F(3,11) = 8.125, p = .008. In addition, multiple regression analyses revealed that the visual abilities together predicted a majority of the variance in SA, R2 = 0.753, p = .008. As validated and verified by ECG and EEG data, the HUD yielded a full ability and capacity to anticipate and accommodate trends were as the HDD yielded a saturated ability to anticipate and accommodate trends. Post-hoc tests revealed a Cohen's f2 = 3.05 yielding statistical power to be 0.98. This work results in a significant contribution to the field by providing an improved understanding of SA and path to safer travel for society worldwide. PA 88ABW-2015-1282.

Cues for the control of ocular accommodation and vergence during postnatal human development.

PubMed

Bharadwaj, Shrikant R; Candy, T Rowan

2008-12-22

Accommodation and vergence help maintain single and focused visual experience while an object moves in depth. The relative importance of retinal blur and disparity, the primary sensory cues to accommodation and vergence, is largely unknown during development; a period when growth of the eye and head necessitate continual recalibration of egocentric space. Here we measured the developmental importance of retinal disparity in 192 typically developing subjects (1.9 months to 46 years). Subjects viewed high-contrast cartoon targets with naturalistic spatial frequency spectra while their accommodation and vergence responses were measured from both eyes using a PowerRefractor. Accommodative gain was reduced during monocular viewing relative to full binocular viewing, even though the fixating eye generated comparable tracking eye movements in the two conditions. This result was consistent across three forms of monocular occlusion. The accommodative gain was lowest in infants and only reached adult levels by 7 to 10 years of age. As expected, the gain of vergence was also reduced in monocular conditions. When 4- to 6-year-old children read 20/40-sized letters, their monocular accommodative gain reached adult-like levels. In summary, binocular viewing appears necessary under naturalistic viewing conditions to generate full accommodation and vergence responses in typically developing humans.

Cues for the control of ocular accommodation and vergence during postnatal human development

PubMed Central

Bharadwaj, Shrikant R.; Candy, T. Rowan

2009-01-01

Accommodation and vergence help maintain single and focused visual experience while an object moves in depth. The relative importance of retinal blur and disparity, the primary sensory cues to accommodation and vergence, is largely unknown during development; a period when growth of the eye and head necessitate continual recalibration of egocentric space. Here we measured the developmental importance of retinal disparity in 192 typically developing subjects (1.9 months to 46 years). Subjects viewed high-contrast cartoon targets with naturalistic spatial frequency spectra while their accommodation and vergence responses were measured from both eyes using a PowerRefractor. Accommodative gain was reduced during monocular viewing relative to full binocular viewing, even though the fixating eye generated comparable tracking eye movements in the two conditions. This result was consistent across three forms of monocular occlusion. The accommodative gain was lowest in infants and only reached adult levels by 7 to 10 years of age. As expected, the gain of vergence was also reduced in monocular conditions. When 4- to 6-year-old children read 20/40-sized letters, their monocular accommodative gain reached adult-like levels. In summary, binocular viewing appears necessary under naturalistic viewing conditions to generate full accommodation and vergence responses in typically developing humans. PMID:19146280

Comparison of tests of accommodation for computer users.

PubMed

Kolker, David; Hutchinson, Robert; Nilsen, Erik

2002-04-01

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

Classroom Technology: How to Use AV Equipment for Visual Learners. PEPNet Tipsheet

ERIC Educational Resources Information Center

Johnstone, Chas

1999-01-01

Students who are deaf and hard of hearing have special needs that must be accommodated before they can fully benefit from various types of classroom presentation technology. An optimal classroom situation for learners who must depend primarily on visual input includes careful consideration of factors such as room set up, legibility of the media,…

Using Art Criticism To Examine Meaning in Today's Visual Imagery.

ERIC Educational Resources Information Center

Smith, Mary Ruth

A method of pedagogical art criticism can be used to examine meaning in one of today's most pervasive forms of visual imagery: the advertising image. It was necessary for the art critical method to accommodate the following components of advertising imagery: (1) history; (2) purpose in a capitalist society; (3) function in society; (4) effects on…

Teacher-Made Tactile Science Materials with Critical and Creative Thinking Activities for Learners Including Those with Visual Impairments

ERIC Educational Resources Information Center

Teske, Jolene K.; Gray, Phyllis; Kuhn, Mason A.; Clausen, Courtney K.; Smith, Latisha L.; Alsubia, Sukainah A.; Ghayoorad, Maryam; Rule, Audrey C.; Schneider, Jean Suchsland

2014-01-01

Gifted students with visual impairments are twice exceptional learners and may not evidence their advanced science aptitudes without appropriate accommodations for learning science. However, effective tactile science teaching materials may be easily made. Recent research has shown that when tactile materials are used with "all" students…

Model-Driven Study of Visual Memory

DTIC Science & Technology

2004-12-01

dimensional stimuli (synthetic human faces ) afford important insights into episodic recognition memory. The results were well accommodated by a summed...the unusual properties of the z-transformed ROCS. 15. SUBJECT TERMS Memory, visual memory, computational model, human memory, faces , identity 16...3 Accomplishments/New Findings 3 Work on Objective One: Recognition Memory for Synthetic Faces . 3 Experim ent 1

Incorporating Assistive Technology for Students with Visual Impairments into the Music Classroom

ERIC Educational Resources Information Center

Rush, Toby W.

2015-01-01

Although recent advances make it easier than ever before for students with severe visual impairments to be fully accommodated in the music classroom, one of the most significant current challenges in this area is most music educators' unfamiliarity with current assistive technology. Fortunately, many of these tools are readily available and even…

Making the Familiar Strange: Thinking Visually in a Study Abroad Course in Professional Communication

ERIC Educational Resources Information Center

Andrews, Deborah C.

2016-01-01

Business and professional communicators increasingly rely on visual thinking and design strategies to create effective messages. The workplace need for such thinking, however, is not readily accommodated in current pedagogy. A long-running study abroad short course for American students taught in London provides a model for meeting this need.…

ToxPi Graphical User Interface 2.0: Dynamic exploration, visualization, and sharing of integrated data models.

PubMed

Marvel, Skylar W; To, Kimberly; Grimm, Fabian A; Wright, Fred A; Rusyn, Ivan; Reif, David M

2018-03-05

Drawing integrated conclusions from diverse source data requires synthesis across multiple types of information. The ToxPi (Toxicological Prioritization Index) is an analytical framework that was developed to enable integration of multiple sources of evidence by transforming data into integrated, visual profiles. Methodological improvements have advanced ToxPi and expanded its applicability, necessitating a new, consolidated software platform to provide functionality, while preserving flexibility for future updates. We detail the implementation of a new graphical user interface for ToxPi (Toxicological Prioritization Index) that provides interactive visualization, analysis, reporting, and portability. The interface is deployed as a stand-alone, platform-independent Java application, with a modular design to accommodate inclusion of future analytics. The new ToxPi interface introduces several features, from flexible data import formats (including legacy formats that permit backward compatibility) to similarity-based clustering to options for high-resolution graphical output. We present the new ToxPi interface for dynamic exploration, visualization, and sharing of integrated data models. The ToxPi interface is freely-available as a single compressed download that includes the main Java executable, all libraries, example data files, and a complete user manual from http://toxpi.org .

Computer vision syndrome: a review.

PubMed

Blehm, Clayton; Vishnu, Seema; Khattak, Ashbala; Mitra, Shrabanee; Yee, Richard W

2005-01-01

As computers become part of our everyday life, more and more people are experiencing a variety of ocular symptoms related to computer use. These include eyestrain, tired eyes, irritation, redness, blurred vision, and double vision, collectively referred to as computer vision syndrome. This article describes both the characteristics and treatment modalities that are available at this time. Computer vision syndrome symptoms may be the cause of ocular (ocular-surface abnormalities or accommodative spasms) and/or extraocular (ergonomic) etiologies. However, the major contributor to computer vision syndrome symptoms by far appears to be dry eye. The visual effects of various display characteristics such as lighting, glare, display quality, refresh rates, and radiation are also discussed. Treatment requires a multidirectional approach combining ocular therapy with adjustment of the workstation. Proper lighting, anti-glare filters, ergonomic positioning of computer monitor and regular work breaks may help improve visual comfort. Lubricating eye drops and special computer glasses help relieve ocular surface-related symptoms. More work needs to be done to specifically define the processes that cause computer vision syndrome and to develop and improve effective treatments that successfully address these causes.

Influence of different types of astigmatism on visual acuity.

PubMed

Remón, Laura; Monsoriu, Juan A; Furlan, Walter D

To investigate the change in visual acuity (VA) produced by different types of astigmatism (on the basis of the refractive power and position of the principal meridians) on normal accommodating eyes. The lens induced method was employed to simulate a set of 28 astigmatic blur conditions on different healthy emmetropic eyes. Additionally, 24 values of spherical defocus were also simulated on the same eyes for comparison. VA was measured in each case and the results, expressed in logMAR units, were represented against of the modulus of the dioptric power vector (blur strength). LogMAR VA varies in a linear fashion with increasing astigmatic blur, being the slope of the line dependent on the accommodative demand in each type of astigmatism. However, in each case, we found no statistically significant differences between the three axes investigated (0°, 45°, 90°). Non-statistically significant differences were found either for the VA achieved with spherical myopic defocus (MD) and mixed astigmatism (MA). VA with simple hyperopic astigmatism (SHA) was higher than with simple myopic astigmatism (SMA), however, in this case non conclusive results were obtained in terms of statistical significance. The VA achieved with imposed compound hyperopic astigmatism (CHA) was highly influenced by the eye's accommodative response. VA is correlated with the blur strength in a different way for each type of astigmatism, depending on the accommodative demand. VA is better when one of the focal lines lie on the retina irrespective of the axis orientation; accommodation favors this situation. Copyright © 2016 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.

Thomas Young's contribution to visual optics: the Bakerian Lecture "on the mechanism of the eye".

PubMed

Atchison, David A; Charman, W Neil

2010-10-15

Thomas Young (1773-1829) carried out major pioneering work in many different subjects. In 1800 he gave the Bakerian Lecture of the Royal Society on the topic of the "mechanism of the eye": this was published in the following year (T. Young, 1801). Young used his own design of optometer to measure refraction and accommodation, and discovered his own astigmatism. He considered the different possible origins of accommodation and confirmed that it was due to change in shape of the lens rather than to change in shape of the cornea or an increase in axial length. However, the paper also dealt with many other aspects of visual and ophthalmic optics, such as biometric parameters, peripheral refraction, longitudinal chromatic aberration, depth-of-focus and instrument myopia. These aspects of the paper have previously received little attention. We now give detailed consideration to these and other less-familiar features of Young's work and conclude that his studies remain relevant to many of the topics which currently engage visual scientists.

6-Hydroxy dopamine does not affect lens-induced refractive errors but suppresses deprivation myopia.

PubMed

Schaeffel, F; Hagel, G; Bartmann, M; Kohler, K; Zrenner, E

1994-01-01

Degradation of the retinal image by translucent occluders during postnatal development induces axial myopia in chickens, tree shrews and monkeys. Local visual deprivation produces myopia even in local regions of the eye and neither accommodation nor intact connection between the eye and the brain are necessary. Therefore, it is an important question whether a similar local-retinal pathway translating visual information into growth or stretch signals to the underlying sclera is acting to emmetropize the growing eye. It is not known until now whether occluder deprivation triggers similar eye growth (or scleral stretch) mechanisms that are also responsible for visual guidance of normal refractive development. We here report that, in chickens, 6-hydroxy dopamine suppresses deprivation-induced myopia but has no effect on the magnitude of changes in axial eye elongation that are induced by spectacle lenses. The result suggests that, in chickens with normal accommodation, two pharmacologically different feedback loops may be responsible for deprivation myopia and lens-induced refractive errors.

Compensation of corneal oblique astigmatism by internal optics: a theoretical analysis.

PubMed

Liu, Tao; Thibos, Larry N

2017-05-01

Oblique astigmatism is a prominent optical aberration of peripheral vision caused by oblique incidence of rays striking the refracting surfaces of the cornea and crystalline lens. We inquired whether oblique astigmatism from these two sources should be expected, theoretically, to have the same or opposite signs across the visual field at various states of accommodation. Oblique astigmatism was computed across the central visual field for a rotationally-symmetric schematic-eye using optical design software. Accommodative state was varied by altering the apical radius of curvature and separation of the biconvex lens's two aspheric surfaces in a manner consistent with published biometry. Oblique astigmatism was evaluated separately for the whole eye, the cornea, and the isolated lens over a wide range of surface curvatures and asphericity values associated with the accommodating lens. We also computed internal oblique astigmatism by subtracting corneal oblique astigmatism from whole-eye oblique astigmatism. A visual field map of oblique astigmatism for the cornea in the Navarro model follows the classic, textbook description of radially-oriented axes everywhere in the field. Despite large changes in surface properties during accommodation, intrinsic astigmatism of the isolated human lens for collimated light is also radially oriented and nearly independent of accommodation both in theory and in real eyes. However, the magnitude of ocular oblique astigmatism is smaller than that of the cornea alone, indicating partial compensation by the internal optics. This implies internal oblique astigmatism (which includes wavefront propagation from the posterior surface of the cornea to the anterior surface of the lens and intrinsic lens astigmatism) must have tangentially-oriented axes. This non-classical pattern of tangential axes for internal astigmatism was traced to the influence of corneal power on the angles of incidence of rays striking the internal lens. Partial compensation of corneal astigmatism by internal optics is due mainly to the highly converging nature of wavefronts incident upon the lens resulting from corneal refraction. The degree of compensation is quadratically dependent on eccentricity but is expected to diminish as the eye accommodates. Neutralising the cornea by index-matching defeats internal compensation, revealing classical, radially-oriented oblique astigmatism in the isolated lens. © 2017 The Authors Ophthalmic & Physiological Optics © 2017 The College of Optometrists.

Reduction of deviation angle during occlusion therapy: in partially accommodative esotropia with moderate amblyopia.

PubMed

Chun, Bo Young; Kwon, Soon Jae; Chae, Sun Hwa; Kwon, Jung Yoon

2007-09-01

To evaluate changes in ocular alignment in partially accommodative esotropic children age ranged from 3 to 8 years during occlusion therapy for amblyopia. Angle measurements of twenty-two partially accommodative esotropic patients with moderate amblyopia were evaluated before and at 2 years after occlusion therapy. Mean deviation angle with glasses at the start of occlusion treatment was 19.45+/-5.97 PD and decreased to 12.14+/-12.96 PD at 2 years after occlusion therapy (p<0.01). After occlusion therapy, 9 (41%) cases were indications of surgery for residual deviation but if we had planned surgery before occlusion treatment, 18 (82%) of patients would have had surgery. There was a statistical relationship between increase of visual acuity ratio and decrease of deviation angle (r=-0.479, p=0.024). There was a significant reduction of deviation angle of partially accommodative esotropic patients at 2 years after occlusion therapy. Our results suggest that occlusion therapy has an influence on ocular alignment in partially accommodative esotropic patients with amblyopia.

Improving Accommodations Outcomes: Monitoring Instructional and Assessment Accommodations for Students with Disabilities

ERIC Educational Resources Information Center

Christensen, Laurene L.; Thurlow, Martha L.; Wang, Ting

2009-01-01

This document presents a five-step process for schools, districts, and states to use in monitoring accommodations for instruction and assessment. This document was designed to be a companion to the "Council of Chief State School Officers' Accommodations Manual: How to Select, Administer, and Evaluate Use of Accommodations for Instruction and…

Synchronized gastric electrical stimulation improves vagotomy-induced impairment in gastric accommodation via the nitrergic pathway in dogs

PubMed Central

Chen, Jie; Koothan, Thillai; Chen, Jiande D. Z.

2009-01-01

Impaired gastric accommodation and gastric dysrhythmia are common in gastroparesis and functional dyspepsia. Recent studies have shown that synchronized gastric electrical stimulation (SGES) accelerates gastric emptying and enhances antral contractions in dogs. The aim of this study was to investigate the effects and mechanism of SGES on gastric accommodation and slow waves impaired by vagotomy in dogs. Gastric tone, compliance, and accommodation as well as slow waves with and without SGES were assessed in seven female regular dogs and seven dogs with bilateral truncal vagotomy, chronically implanted with gastric serosal electrodes and a gastric cannula. We found that 1) vagotomy impaired gastric accommodation that was normalized by SGES. The postprandial increase in gastric volume was 283.5 ± 50.6 ml in the controlled dogs, 155.2 ± 49.2 ml in the vagotomized dogs, and 304.0 ± 57.8 ml in the vagotomized dogs with SGES. The ameliorating effect of SGES was no longer observed after application of Nω-nitro-l-arginine (l-NNA); 2) vagotomy did not alter gastric compliance whereas SGES improved gastric compliance in the vagotomized dogs, and the improvement was also blocked by l-NNA; and 3) vagotomy impaired antral slow wave rhythmicity in both fasting and fed states. SGES at the proximal stomach enhanced the postprandial rhythmicity and amplitude (dominant power) of the gastric slow waves in the antrum. In conclusion, SGES with appropriate parameters restores gastric accommodation and improves gastric slow waves impaired by vagotomy. The improvement in gastric accommodation with SGES is mediated via the nitrergic pathway. Combined with previously reported findings (enhanced antral contractions and accelerated gastric emptying) and findings in this study (improved gastric accommodation and slow waves), SGES may be a viable therapy for gastroparesis. PMID:19023028

Christoph Scheiner and the optics of the eye. (German Title: Christoph Scheiner und die Optik des Auges)

NASA Astrophysics Data System (ADS)

Daxecker, Franz

Some of Scheiner's discoveries and experiments are taken from the books «Oculus», (Innsbruck 1619) and «Rosa Ursina sive Sol» (Rome 1626-1630): determination of the radius of curvature of the cornea, discovery of the nasal exit of the visual nerve, increase in the curvature of the lens in case of accommodation, anatomy of the eye, light reaction of the pupil, contraction of the pupil during accommodation, Scheiner's test (double images caused by ametropia), stenopeic effect, crossing rays in the eye, aperture, description of the cataract treatment, refractive indices of various parts of the eye, eye model, visual pivot angle of the eye, proof of crossing rays on the retina, comparison of the camera obscura and the optics of the eye.

Prediction of accommodative optical response in prepresbyopic patients using ultrasound biomicroscopy

PubMed Central

Ramasubramanian, Viswanathan; Glasser, Adrian

2015-01-01

PURPOSE To determine whether relatively low-resolution ultrasound biomicroscopy (UBM) can predict the accommodative optical response in prepresbyopic eyes as well as in a previous study of young phakic subjects, despite lower accommodative amplitudes. SETTING College of Optometry, University of Houston, Houston, USA. DESIGN Observational cross-sectional study. METHODS Static accommodative optical response was measured with infrared photorefraction and an autorefractor (WR-5100K) in subjects aged 36 to 46 years. A 35 MHz UBM device (Vumax, Sonomed Escalon) was used to image the left eye, while the right eye viewed accommodative stimuli. Custom-developed Matlab image-analysis software was used to perform automated analysis of UBM images to measure the ocular biometry parameters. The accommodative optical response was predicted from biometry parameters using linear regression, 95% confidence intervals (CIs), and 95% prediction intervals. RESULTS The study evaluated 25 subjects. Per-diopter (D) accommodative changes in anterior chamber depth (ACD), lens thickness, anterior and posterior lens radii of curvature, and anterior segment length were similar to previous values from young subjects. The standard deviations (SDs) of accommodative optical response predicted from linear regressions for UBM-measured biometry parameters were ACD, 0.15 D; lens thickness, 0.25 D; anterior lens radii of curvature, 0.09 D; posterior lens radii of curvature, 0.37 D; and anterior segment length, 0.42 D. CONCLUSIONS Ultrasound biomicroscopy parameters can, on average, predict accommodative optical response with SDs of less than 0.55 D using linear regressions and 95% CIs. Ultrasound biomicroscopy can be used to visualize and quantify accommodative biometric changes and predict accommodative optical response in prepresbyopic eyes. PMID:26049831

Software-based stacking techniques to enhance depth of field and dynamic range in digital photomicrography.

PubMed

Piper, Jörg

2010-01-01

Several software solutions are powerful tools to enhance the depth of field and improve focus in digital photomicrography. By these means, the focal depth can be fundamentally optimized so that three-dimensional structures within specimens can be documented with superior quality. Thus, images can be created in light microscopy which will be comparable with scanning electron micrographs. The remaining sharpness will no longer be dependent on the specimen's vertical dimension or its range in regional thickness. Moreover, any potential lack of definition associated with loss of planarity and unsteadiness in the visual accommodation can be mitigated or eliminated so that the contour sharpness and resolution can be strongly enhanced.Through the use of complementary software, ultrahigh ranges in brightness and contrast (the so-called high-dynamic range) can be corrected so that the final images will also be free from locally over- or underexposed zones. Furthermore, fine detail in low natural contrast can be visualized in much higher clarity. Fundamental enhancements of the global visual information will result from both techniques.

Patient DF's visual brain in action: Visual feedforward control in visual form agnosia.

PubMed

Whitwell, Robert L; Milner, A David; Cavina-Pratesi, Cristiana; Barat, Masihullah; Goodale, Melvyn A

2015-05-01

Patient DF, who developed visual form agnosia following ventral-stream damage, is unable to discriminate the width of objects, performing at chance, for example, when asked to open her thumb and forefinger a matching amount. Remarkably, however, DF adjusts her hand aperture to accommodate the width of objects when reaching out to pick them up (grip scaling). While this spared ability to grasp objects is presumed to be mediated by visuomotor modules in her relatively intact dorsal stream, it is possible that it may rely abnormally on online visual or haptic feedback. We report here that DF's grip scaling remained intact when her vision was completely suppressed during grasp movements, and it still dissociated sharply from her poor perceptual estimates of target size. We then tested whether providing trial-by-trial haptic feedback after making such perceptual estimates might improve DF's performance, but found that they remained significantly impaired. In a final experiment, we re-examined whether DF's grip scaling depends on receiving veridical haptic feedback during grasping. In one condition, the haptic feedback was identical to the visual targets. In a second condition, the haptic feedback was of a constant intermediate width while the visual target varied trial by trial. Despite this incongruent feedback, DF still scaled her grip aperture to the visual widths of the target blocks, showing only normal adaptation to the false haptically-experienced width. Taken together, these results strengthen the view that DF's spared grasping relies on a normal mode of dorsal-stream functioning, based chiefly on visual feedforward processing. Copyright © 2014 Elsevier B.V. All rights reserved.

[Effects of visual optical stimuli for accommodation-convergence system on asthenopia].

PubMed

Iwasaki, Tsuneto; Tawara, Akihiko; Miyake, Nobuyuki

2006-01-01

We investigated the effect on eyestrain of optical stimuli that we designed for accommodation and convergence systems. Eight female students were given optical stimuli for accommodation and convergence systems for 1.5 min immediately after 20 min of a sustained task on a 3-D display. Before and after the trial, their ocular functions were measured and their symptoms were assessed. The optical stimuli were applied by moving targets of scenery images far and near around the far point position of both eyes on a horizonal place, which induced divergence in the direction of the eye position of rest. In a control group, subjects rested with closed eyes for 1.5 min instead of applying the optical stimuli. There were significant changes in the accommodative contraction time (from far to near) and the accommodative relaxation time (from near to far) and the lag of accommodation at near target, from 1.26 s to 1.62 s and from 1.49 s to 1.63 s and from 0.5 D to 0.65 D, respectively, and in the symptoms in the control group after the duration of closed-eye rest. In the stimulus group, however, the changes of those functions were smaller than in the control group. From these results, we suggest that our designed optical stimuli for accommodation and convergence systems are effective on asthenopia following accommodative dysfunction.

Maximum human objectively measured pharmacologically stimulated accommodative amplitude.

PubMed

Grzybowski, Andrzej; Schachar, Ronald A; Gaca-Wysocka, Magdalena; Schachar, Ira H; Pierscionek, Barbara K

2018-01-01

To measure the maximum, objectively measured, accommodative amplitude, produced by pharmacologic stimulation. Thirty-seven healthy subjects were enrolled, with a mean age of 20.2±1.1 years, corrected visual acuity of 20/20, and mean spherical equivalent refraction (SER) =-0.83±1.60 diopters. For each subject, the right pupil was dilated with phenylephrine 10%. After 30 minutes, the pupil was measured, the left eye was patched, and the right eye was autorefracted. Pilocarpine 4% was then instilled in the right eye, followed by phenylephrine. At 45 minutes after the pilocarpine, autorefraction and pupil size were again measured. Mean pupil size pre- and postpilocarpine was 8.0±0.8 mm and 4.4±1.9 mm, respectively. Pre- and postpilocarpine, the mean SER was -0.83±1.60 and -10.55±4.26 diopters, respectively. The mean pilocarpine-induced accommodative amplitude was 9.73±3.64 diopters. Five subjects had accommodative amplitudes ≥14.00 diopters. Accommodative amplitude was not significantly related to baseline SER ( p -value =0.24), pre- or postpilocarpine pupil size ( p -values =0.13 and 0.74), or change in pupil size ( p -value =0.37). Iris color did not statistically significantly affect accommodative amplitude ( p -value =0.83). Following topically applied pilocarpine, the induced objectively measured accommodation in the young eye is greater than or equal to the reported subjectively measured voluntary maximum accommodative amplitude.

Attention-deficit/hyperactivity disorder children exhibit an impaired accommodative response.

PubMed

Redondo, Beatriz; Vera, Jesús; Molina, Rubén; García, José Antonio; Ouadi, Miriam; Muñoz-Hoyos, Antonio; Jiménez, Raimundo

2018-05-01

Attention-deficit/hyperactivity disorder (ADHD) is one of the most common paediatric neurobehavioural disorders causing multiple functional impairments in children. Based on the relationship between the neural system that controls attention and ocular dynamics, the present study compares the magnitude and variability of accommodation between a group of non-medicated ADHD children and an age-matched control group. The magnitude and variability of the accommodative response were objectively measured in 36 children using the WAM-5500 autorefractometer for 90 consecutive seconds at three static viewing distances (500, 40, and 20 cm). Participants were divided into ADHD (n = 18) or control (n = 18) groups based on clinically validated criteria. Children with ADHD exhibited higher lags of accommodation (p = 0.024), increasing at closer viewing distances, in comparison to the control group. Marginal statistical differences were found for the variability of accommodation (p = 0.066), with the ADHD group showing a trend towards higher variability. Our analysis showed that the magnitude and variability of accommodation did not vary over time between groups (p > 0.05). Our data suggest that children with ADHD have a less accurate accommodative response. These results provide a new ocular index that could help to clarify the relationship between accommodative response and attentional deficits, which could have a direct impact on the academic, cognitive, and visual performance of ADHD children.

Objective measurement of accommodative biometric changes using ultrasound biomicroscopy

PubMed Central

Ramasubramanian, Viswanathan; Glasser, Adrian

2015-01-01

PURPOSE To demonstrate that ultrasound biomicroscopy (UBM) can be used for objective quantitative measurements of anterior segment accommodative changes. SETTING College of Optometry, University of Houston, Houston, Texas, USA. DESIGN Prospective cross-sectional study. METHODS Anterior segment biometric changes in response to 0 to 6.0 diopters (D) of accommodative stimuli in 1.0 D steps were measured in eyes of human subjects aged 21 to 36 years. Imaging was performed in the left eye using a 35 MHz UBM (Vumax) and an A-scan ultrasound (A-5500) while the right eye viewed the accommodative stimuli. An automated Matlab image-analysis program was developed to measure the biometry parameters from the UBM images. RESULTS The UBM-measured accommodative changes in anterior chamber depth (ACD), lens thickness, anterior lens radius of curvature, posterior lens radius of curvature, and anterior segment length were statistically significantly (P < .0001) linearly correlated with accommodative stimulus amplitudes. Standard deviations of the UBM-measured parameters were independent of the accommodative stimulus demands (ACD 0.0176 mm, lens thickness 0.0294 mm, anterior lens radius of curvature 0.3350 mm, posterior lens radius of curvature 0.1580 mm, and anterior segment length 0.0340 mm). The mean difference between the A-scan and UBM measurements was −0.070 mm for ACD and 0.166 mm for lens thickness. CONCLUSIONS Accommodating phakic eyes imaged using UBM allowed visualization of the accommodative response, and automated image analysis of the UBM images allowed reliable, objective, quantitative measurements of the accommodative intraocular biometric changes. PMID:25804579

Long-term repetitive sodium lauryl sulfate-induced irritation of the skin: an in vivo study.

PubMed

Branco, Nara; Lee, Ivy; Zhai, Hongbo; Maibach, Howard I

2005-11-01

Skin may adapt to topical irritants through accommodation. This study focuses on long-term exposure to irritants and attempts to demonstrate accommodation. Sodium lauryl sulfate (SLS) induced irritant contact dermatitis at 3 concentrations (0.025% to 0.075%). Distilled water, acetone and an empty chamber served as controls. Experimental compounds were applied to forearms of 7 healthy volunteers for 24 hr before replacing by a fresh chamber for 6 non-consecutive weeks over 103 days. Possible accommodation was quantified by visual scoring (erythema and dryness) and by bioengineering parameters: transepidermal water loss (TEWL), capacitance, chromametry and laser Doppler flowmetry (LDF). Significant erythema, dryness, elevated TEWL, skin colour reflectance and LDF values occurred during the exposure periods. Upon repeat exposure, an immediate and augmented response in erythema, TEWL, skin colour reflectance and LDF developed. However, irritant skin changes were not sustained. Irritation parameters return to baseline after cessation of exposure. There was no evidence of sustained irritation or accommodation after the last exposure. Study findings do not document sustained accommodation or adaptive hyposensitivity after long-term repetitive irritant exposure under these test conditions. Alternative models should be developed to prove or disprove the accommodation hypothesis.

Vergence-accommodation conflicts hinder visual performance and cause visual fatigue.

PubMed

Hoffman, David M; Girshick, Ahna R; Akeley, Kurt; Banks, Martin S

2008-03-28

Three-dimensional (3D) displays have become important for many applications including vision research, operation of remote devices, medical imaging, surgical training, scientific visualization, virtual prototyping, and more. In many of these applications, it is important for the graphic image to create a faithful impression of the 3D structure of the portrayed object or scene. Unfortunately, 3D displays often yield distortions in perceived 3D structure compared with the percepts of the real scenes the displays depict. A likely cause of such distortions is the fact that computer displays present images on one surface. Thus, focus cues-accommodation and blur in the retinal image-specify the depth of the display rather than the depths in the depicted scene. Additionally, the uncoupling of vergence and accommodation required by 3D displays frequently reduces one's ability to fuse the binocular stimulus and causes discomfort and fatigue for the viewer. We have developed a novel 3D display that presents focus cues that are correct or nearly correct for the depicted scene. We used this display to evaluate the influence of focus cues on perceptual distortions, fusion failures, and fatigue. We show that when focus cues are correct or nearly correct, (1) the time required to identify a stereoscopic stimulus is reduced, (2) stereoacuity in a time-limited task is increased, (3) distortions in perceived depth are reduced, and (4) viewer fatigue and discomfort are reduced. We discuss the implications of this work for vision research and the design and use of displays.

Agreement between clinical and laboratory methods assessing tonic and cross-link components of accommodation and vergence.

PubMed

Neveu, Pascaline; Priot, Anne-Emmanuelle; Philippe, Matthieu; Fuchs, Philippe; Roumes, Corinne

2015-09-01

Several tests are available to optometrists for investigating accommodation and vergence. This study sought to investigate the agreement between clinical and laboratory methods and to clarify which components are actually measured when tonic and cross-link of accommodation and vergence are assessed. Tonic vergence, tonic accommodation, accommodative vergence (AC/A) and vergence accommodation (CA/C) were measured using several tests. Clinical tests were compared to the laboratory assessment, the latter being regarded as an absolute reference. The repeatability of each test and the degree of agreement between the tests were quantified using Bland-Altman analysis. The values obtained for each test were found to be stable across repetitions; however, in most cases, significant differences were observed between tests supposed to measure the same oculomotor component. Tonic and cross-link components cannot be easily assessed because proximal and instrumental responses interfere with the assessment. Other components interfere with oculomotor assessment. Specifically, accommodative divergence interferes with tonic vergence estimation and the type of accommodation considered in the AC/A ratio affects its magnitude. Results on clinical tonic accommodation and clinical CA/C show that further investigation is needed to clarify the limitations associated with the use of difference of Gaussian as visual targets to open the accommodative loop. Although different optometric tests of accommodation and vergence rely on the same basic principles, the results of this study indicate that clinical and laboratory methods actually involve distinct components. These differences, which are induced by methodological choices, must be taken into account, when comparing studies or when selecting a test to investigate a particular oculomotor component. © 2015 The Authors. Clinical and Experimental Optometry © 2015 Optometry Australia.

A Comparison of Intranasal and Oral Scopolamine for Motion Sickness Prevention in Military Personnel

DTIC Science & Technology

2008-08-18

Cornum, Caldwell & Cornum, 1997; Cowings et al., 1996; Golding & Stott, 1997; Marcus & Furman, 2006; Putcha, 1999; Wood & Graybiel, 1968). The most...performance effects (Lewandowski, Dietz, & Reeves, 1997; Elsmore, Reeves & Reeves, 2007; Kane , Roebuck-Spenser, Short, Kabat & Wilken, 2007; Wilken...Sullivan, Lewandowski & Kane , 2007). Visual acuity assessment An RAF rule (Neely, 1956) was used to measure visual accommodation (near-focus

The plastic ear and perceptual relearning in auditory spatial perception

PubMed Central

Carlile, Simon

2014-01-01

The auditory system of adult listeners has been shown to accommodate to altered spectral cues to sound location which presumably provides the basis for recalibration to changes in the shape of the ear over a life time. Here we review the role of auditory and non-auditory inputs to the perception of sound location and consider a range of recent experiments looking at the role of non-auditory inputs in the process of accommodation to these altered spectral cues. A number of studies have used small ear molds to modify the spectral cues that result in significant degradation in localization performance. Following chronic exposure (10–60 days) performance recovers to some extent and recent work has demonstrated that this occurs for both audio-visual and audio-only regions of space. This begs the questions as to the teacher signal for this remarkable functional plasticity in the adult nervous system. Following a brief review of influence of the motor state in auditory localization, we consider the potential role of auditory-motor learning in the perceptual recalibration of the spectral cues. Several recent studies have considered how multi-modal and sensory-motor feedback might influence accommodation to altered spectral cues produced by ear molds or through virtual auditory space stimulation using non-individualized spectral cues. The work with ear molds demonstrates that a relatively short period of training involving audio-motor feedback (5–10 days) significantly improved both the rate and extent of accommodation to altered spectral cues. This has significant implications not only for the mechanisms by which this complex sensory information is encoded to provide spatial cues but also for adaptive training to altered auditory inputs. The review concludes by considering the implications for rehabilitative training with hearing aids and cochlear prosthesis. PMID:25147497

Ciliary muscle contraction force and trapezius muscle activity during manual tracking of a moving visual target.

PubMed

Domkin, Dmitry; Forsman, Mikael; Richter, Hans O

2016-06-01

Previous studies have shown an association of visual demands during near work and increased activity of the trapezius muscle. Those studies were conducted under stationary postural conditions with fixed gaze and artificial visual load. The present study investigated the relationship between ciliary muscle contraction force and trapezius muscle activity across individuals during performance of a natural dynamic motor task under free gaze conditions. Participants (N=11) tracked a moving visual target with a digital pen on a computer screen. Tracking performance, eye refraction and trapezius muscle activity were continuously measured. Ciliary muscle contraction force was computed from eye accommodative response. There was a significant Pearson correlation between ciliary muscle contraction force and trapezius muscle activity on the tracking side (0.78, p<0.01) and passive side (0.64, p<0.05). The study supports the hypothesis that high visual demands, leading to an increased ciliary muscle contraction during continuous eye-hand coordination, may increase trapezius muscle tension and thus contribute to the development of musculoskeletal complaints in the neck-shoulder area. Further experimental studies are required to clarify whether the relationship is valid within each individual or may represent a general personal trait, when individuals with higher eye accommodative response tend to have higher trapezius muscle activity. Copyright © 2015 Elsevier Ltd. All rights reserved.

Reduction of Deviation Angle During Occlusion Therapy: In Partially Accommodative Esotropia with Moderate Amblyopia

PubMed Central

Chun, Bo Young; Kwon, Soon Jae; Chae, Sun Hwa

2007-01-01

Purpose To evaluate changes in ocular alignment in partially accommodative esotropic children age ranged from 3 to 8 years during occlusion therapy for amblyopia. Methods Angle measurements of twenty-two partially accommodative esotropic patients with moderate amblyopia were evaluated before and at 2 years after occlusion therapy. Results Mean deviation angle with glasses at the start of occlusion treatment was 19.45±5.97 PD and decreased to 12.14±12.96 PD at 2 years after occlusion therapy (p<0.01). After occlusion therapy, 9 (41%) cases were indications of surgery for residual deviation but if we had planned surgery before occlusion treatment, 18 (82%) of patients would have had surgery. There was a statistical relationship between increase of visual acuity ratio and decrease of deviation angle (r=-0.479, p=0.024). Conclusions There was a significant reduction of deviation angle of partially accommodative esotropic patients at 2 years after occlusion therapy. Our results suggest that occlusion therapy has an influence on ocular alignment in partially accommodative esotropic patients with amblyopia. PMID:17804922

Effect of third-order aberrations on dynamic accommodation.

PubMed

López-Gil, Norberto; Rucker, Frances J; Stark, Lawrence R; Badar, Mustanser; Borgovan, Theodore; Burke, Sean; Kruger, Philip B

2007-03-01

We investigate the potential for the third-order aberrations coma and trefoil to provide a signed cue to accommodation. It is first demonstrated theoretically (with some assumptions) that the point spread function is insensitive to the sign of spherical defocus in the presence of odd-order aberrations. In an experimental investigation, the accommodation response to a sinusoidal change in vergence (1-3D, 0.2Hz) of a monochromatic stimulus was obtained with a dynamic infrared optometer. Measurements were obtained in 10 young visually normal individuals with and without custom contact lenses that induced low and high values of r.m.s. trefoil (0.25, 1.03 microm) and coma (0.34, 0.94 microm). Despite variation between subjects, we did not find any statistically significant increase or decrease in the accommodative gain for low levels of trefoil and coma, although effects approached or reached significance for the high levels of trefoil and coma. Theoretical and experimental results indicate that the presence of Zernike third-order aberrations on the eye does not seem to play a crucial role in the dynamics of the accommodation response.

Dynamic accommodative response to different visual stimuli (2D vs 3D) while watching television and while playing Nintendo 3DS console.

PubMed

Oliveira, Sílvia; Jorge, Jorge; González-Méijome, José M

2012-09-01

The aim of the present study was to compare the accommodative response to the same visual content presented in two dimensions (2D) and stereoscopically in three dimensions (3D) while participants were either watching a television (TV) or Nintendo 3DS console. Twenty-two university students, with a mean age of 20.3 ± 2.0 years (mean ± S.D.), were recruited to participate in the TV experiment and fifteen, with a mean age of 20.1 ± 1.5 years took part in the Nintendo 3DS console study. The accommodative response was measured using a Grand Seiko WAM 5500 autorefractor. In the TV experiment, three conditions were used initially: the film was viewed in 2D mode (TV2D without glasses), the same sequence was watched in 2D whilst shutter-glasses were worn (TV2D with glasses) and the sequence was viewed in 3D mode (TV3D). Measurements were taken for 5 min in each condition, and these sections were sub-divided into ten 30-s segments to examine changes within the film. In addition, the accommodative response to three points of different disparity of one 3D frame was assessed for 30 s. In the Nintendo experiment, two conditions were employed - 2D viewing and stereoscopic 3D viewing. In the TV experiment no statistically significant differences were found between the accommodative response with TV2D without glasses (-0.38 ± 0.32D, mean ± S.D.) and TV3D (-0.37 ± 0.34D). Also, no differences were found between the various segments of the film, or between the accommodative response to different points of one frame (p > 0.05). A significant difference (p = 0.015) was found, however, between the TV2D with (-0.32 ± 0.32D) and without glasses (-0.38 ± 0.32D). In the Nintendo experiment the accommodative responses obtained in modes 2D (-2.57 ± 0.30D) and 3D (-2.49 ± 0.28D) were significantly different (paired t-test p = 0.03). The need to use shutter-glasses may affect the accommodative response during the viewing of displays, and the accommodative response when playing Nintendo 3DS in 3D mode is lower than when it is viewed in 2D. © 2012 The College of Optometrists.

ACCOMMODATIVE MOVEMENTS OF THE LENS/CAPSULE AND THE STRAND THAT EXTENDS BETWEEN THE POSTERIOR VITREOUS ZONULE INSERTION ZONE & THE LENS EQUATOR, IN RELATION TO THE VITREOUS FACE AND AGING

PubMed Central

CROFT, MARY ANN; HEATLEY, GREGG; MCDONALD, JARED P.; KATZ, ALEXANDER; KAUFMAN, PAUL L.

2016-01-01

Purpose To elucidate the dynamic accommodative movements of the lens capsule, posterior lens and the strand that attaches to the posterior vitreous zonule insertion zone and posterior lens equator (PVZ INS-LE), and their age-related changes. Methods Twelve human subjects (ages 19–65 years) and twelve rhesus monkeys (ages 6–27 years) were studied. Accommodation was induced pharmacologically (humans) or by central electrical stimulation (monkeys). Ultrasound biomicroscopy was used to image intraocular structures in both species. Surgical procedures and contrast agents were utilized in the monkey eyes to elucidate function and allow visualization of the intraocular accommodative structures. Results Human: The posterior pole of the lens moves posteriorly during accommodation in proportion to accommodative amplitude and ciliary muscle movement. Monkey: Similar accommodative movements of the posterior lens pole were seen in the monkey eyes. Following extracapsular lens extraction (ECLE), the central capsule bows backward during accommodation in proportion to accommodative amplitude and ciliary muscle movement, while the peripheral capsule moves forward. During accommodation the ciliary muscle moved forward by ~1.0 mm, pulling forward the vitreous zonule and the PVZ INS-LE structure. During the accommodative response the PVZ INS-LE structure moved forward when the lens was intact and when the lens substance and capsule were removed. In both the monkey and the human eyes these movements declined with age. Conclusions The accommodative shape change of the central capsule may be due to the elastic properties of the capsule itself. For these capsule/lens accommodative posterior movements to occur, the vitreous face must either allow for it or facilitate it. The PVZ INS-LE structure may act as a “strut” to the posterior lens equator (pushing the lens equator forward) and thereby facilitate accommodative forward lens equator movement and lens thickening. The age-related posterior restriction of the ciliary muscle, vitreous zonule and the PVZ-INS LE structure dampens the accommodative lens shape change. Future descriptions of the accommodative mechanism, and approaches to presbyopia therapy, may need to incorporate these findings. PMID:26769326

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

Human dynamic closed-loop accommodation augmented by sympathetic inhibition.

PubMed

Culhane, H M; Winn, B; Gilmartin, B

1999-05-01

A ciliary alpha-adrenoceptor accommodative effect has been proposed, caused by a small population of alpha1-inhibitory receptors in excised human ciliary muscle. This study was intended to investigate the effect on the closed-loop dynamic accommodative process of modulating alpha1-adrenoceptor activity by topical instillation of the alpha1-adrenergic agonist, phenylephrine hydrochloride. A group of 10 visually normal subjects viewed a photopic (30 candela/m2) high-contrast Maltese cross, which was modulated sinusoidally (0.05-0.6Hz) and stepwise over a 2-D range (2-4 D). Monocular temporal accommodation responses were measured using a continuously recording dynamic tracking infrared optometer under two trial conditions: after instillation of saline control solution and 50 minutes subsequent to the instillation of 0.27 microl 0.4% benoxinate hydrochloride and 0.27 microl 2.5% phenylephrine hydrochloride. Pupil size and accommodative amplitude were measured at 90-second intervals for 50 minutes after drug instillation. All accommodative measurements were recorded through a fixed 4-mm pupil. A significant reduction in accommodative amplitude (11%; P < 0.05) was recorded, whereas pupil size showed a significant increase (33%; P < 0.05). No significant change in step-response dynamics was observed. However, phenylephrine hydrochloride caused a significant increase in accommodative gain in the low and midtemporal frequency ranges compared with the effect of a saline control treatment. No significant variation in phase lag was observed. For the first time in humans, this study shows that augmentation of the alpha1-inhibitory sympathetic contribution results in increased accommodative gain at low and midtemporal frequencies, which is consistent with findings in animal studies.

Developing an Inclusive Learning Environment for Students with Visual Impairment in Higher Education: Progressive Mutual Accommodation and Learner Experiences in the United Kingdom

ERIC Educational Resources Information Center

Hewett, Rachel; Douglas, Graeme; McLinden, Michael; Keil, Sue

2017-01-01

Drawing on the findings of a unique longitudinal qualitative study, this article investigates the experiences of 32 young people with visual impairment (VI) in higher education (HE) in the United Kingdom (UK) to explore how well they were able to participate on their courses. We propose and apply a Bioecological Model of Inclusive HE to interpret…

Effect of Yogic Breathing on Accommodate Braille Version of Six-letter Cancellation Test in Students with Visual Impairment.

PubMed

Pradhan, Balaram; Mohanty, Soubhagyalaxmi; Hankey, Alex

2018-01-01

Attentional processes tend to be less well developed in the visually impaired, who require special training to develop them fully. Yogic breathing which alters the patterns of respiration has been shown to enhance attention skills. Letter cancellation tests are well-established tools to measure attention and attention span. Here, a modified Braille version of the six-letter cancellation test (SLCT) was used for students with visual impairment (VI). This study aimed to assess the immediate effects of Bhramari Pranayama (BhPr) and breath awareness (BA) on students with VI. This study was a self-as-control study held on 2 consecutive days, on 19 participants (8 males, 11 females), with a mean age of 15.89 ± 1.59 years, randomized into two groups. On the 1 st day, Group 1 performed 10 min breath awareness and Group 2 performed Bhramari ; on the 2 nd day, practices were reversed. Assessments used a SLCT specially adapted for the visually impaired before and after each session. The Braille letter cancellation test was successfully taken by 19 students. Scores significantly improved after both techniques for each student following practices on both days ( P < 0.001). BhPr may have more effect on attention performance than BA as wrong scores significantly increased following BA ( P < 0.05), but the increase in the score after Bhramari was not significant. Despite the small sample size improvement in attentional processes by both yoga breathing techniques was robust. Attentional skills were definitely enhanced. Long-term practice should be studied.

Effect of Yogic Breathing on Accommodate Braille Version of Six-letter Cancellation Test in Students with Visual Impairment

PubMed Central

Pradhan, Balaram; Mohanty, Soubhagyalaxmi; Hankey, Alex

2018-01-01

Context: Attentional processes tend to be less well developed in the visually impaired, who require special training to develop them fully. Yogic breathing which alters the patterns of respiration has been shown to enhance attention skills. Letter cancellation tests are well-established tools to measure attention and attention span. Here, a modified Braille version of the six-letter cancellation test (SLCT) was used for students with visual impairment (VI). Aim: This study aimed to assess the immediate effects of Bhramari Pranayama (BhPr) and breath awareness (BA) on students with VI. Methods: This study was a self-as-control study held on 2 consecutive days, on 19 participants (8 males, 11 females), with a mean age of 15.89 ± 1.59 years, randomized into two groups. On the 1st day, Group 1 performed 10 min breath awareness and Group 2 performed Bhramari; on the 2nd day, practices were reversed. Assessments used a SLCT specially adapted for the visually impaired before and after each session. Results: The Braille letter cancellation test was successfully taken by 19 students. Scores significantly improved after both techniques for each student following practices on both days (P < 0.001). BhPr may have more effect on attention performance than BA as wrong scores significantly increased following BA (P < 0.05), but the increase in the score after Bhramari was not significant. Conclusions: Despite the small sample size improvement in attentional processes by both yoga breathing techniques was robust. Attentional skills were definitely enhanced. Long-term practice should be studied. PMID:29755219

Multiaccommodative stimuli in VR systems: problems & solutions.

PubMed

Marran, L; Schor, C

1997-09-01

Virtual reality environments can introduce multiple and sometimes conflicting accommodative stimuli. For instance, with the high-powered lenses commonly used in head-mounted displays, small discrepancies in screen lens placement, caused by manufacturer error or user adjustment focus error, can change the focal depths of the image by a couple of diopters. This can introduce a binocular accommodative stimulus or, if the displacement between the two screens is unequal, an unequal (anisometropic) accommodative stimulus for the two eyes. Systems that allow simultaneous viewing of virtual and real images can also introduce a conflict in accommodative stimuli: When real and virtual images are at different focal planes, both cannot be in focus at the same time, though they may appear to be in similar locations in space. In this paper four unique designs are described that minimize the range of accommodative stimuli and maximize the visual system's ability to cope efficiently with the focus conflicts that remain: pinhole optics, monocular lens addition combined with aniso-accommodation, chromatic bifocal, and bifocal lens system. The advantages and disadvantages of each design are described and recommendation for design choice is given after consideration of the end use of the virtual reality system (e.g., low or high end, entertainment, technical, or medical use). The appropriate design modifications should allow greater user comfort and better performance.

Vergence–accommodation conflicts hinder visual performance and cause visual fatigue

PubMed Central

Hoffman, David M.; Girshick, Ahna R.; Akeley, Kurt; Banks, Martin S.

2010-01-01

Three-dimensional (3D) displays have become important for many applications including vision research, operation of remote devices, medical imaging, surgical training, scientific visualization, virtual prototyping, and more. In many of these applications, it is important for the graphic image to create a faithful impression of the 3D structure of the portrayed object or scene. Unfortunately, 3D displays often yield distortions in perceived 3D structure compared with the percepts of the real scenes the displays depict. A likely cause of such distortions is the fact that computer displays present images on one surface. Thus, focus cues—accommodation and blur in the retinal image—specify the depth of the display rather than the depths in the depicted scene. Additionally, the uncoupling of vergence and accommodation required by 3D displays frequently reduces one’s ability to fuse the binocular stimulus and causes discomfort and fatigue for the viewer. We have developed a novel 3D display that presents focus cues that are correct or nearly correct for the depicted scene. We used this display to evaluate the influence of focus cues on perceptual distortions, fusion failures, and fatigue. We show that when focus cues are correct or nearly correct, (1) the time required to identify a stereoscopic stimulus is reduced, (2) stereoacuity in a time-limited task is increased, (3) distortions in perceived depth are reduced, and (4) viewer fatigue and discomfort are reduced. We discuss the implications of this work for vision research and the design and use of displays. PMID:18484839

Near Point of Accommodation and Convergence after Photorefractive Keratectomy (PRK) for Myopia.

PubMed

Hashemi, Hassancourtney; Samet, Behnaz; Mirzajani, Ali; Khabazkhoob, Mehdi; Rezvan, Bijan; Jafarzadehpur, Ebrahim

2013-01-01

Near point of convergence (NPC) and near point of accommodation (NPA) were evaluated before and after photorefractive keratectomy (PRK) in normal myopic eyes. In this prospective cross sectional study, NPC and NPA were measured in 120 myopic eyes (60 patients) before and 3 months after PRK. Excluding criteria were manifest tropia, previous eye surgery, amblyopia, and any other ocular pathology. All subjects were younger than35 years old. Fifty-one females (85%) and nine males (15%) participated in the study. The average age of the participants was 25.75 years. Before the operation, the average NPC and NPA were 4.35 cm and 6.9 cm (14.5 D), respectively. NPC and NPA increased significantly 5.63 (p = 0.025) and (p 0.05) to 7.983 cm (12.5 D) (p 0.001), respectively, after 3 months. NPC and NPA may increase significantly after PRK. Convergence and accommodation problems may affect near visual performance. Therefore, for any PRK candidate, accommodation and convergence should be evaluated.

The Measures Contribution Researches on Renewable Energy Accommodation Based on Production Simulation

NASA Astrophysics Data System (ADS)

Zhe, MI; Jinfang, Zhang; Jun, Liu

2018-06-01

This paper presents the impacts of load, source and grid factors on renewable energy accommodation in the northern region of China. Renewable energy curtailment reasons and key measures to improve accommodations are also discussed. The production simulation method is utilized to analysis renewable energy accommodation and the Shapely value method is introduced to calculate the accommodation contribution rate of different factors. The result shows that the amount of renewable energy accommodation is 389 TWh in northern region of China by the year 2020. The contribution rate of load, source and grid factors to renewable energy accommodation are 39%, 35.8% and 25.1%, respectively.

Functional spasm of accommodation: Changes on scheimpflug imaging

PubMed Central

Sukhija, Jaspreet; Dogra, Mangat R.; Zadeng, Thara; Ram, Jagat

2014-01-01

Spasm of accommodation is a rare condition characterized by a sudden increase in myopia. It can occur in emmetropes, hypermetropes and myopes. All the physiological changes that occur in normal accommodation are exaggerated. Mostly the cause is functional disorder and the condition gradually improves. We hereby present the changes occurring in spasm of accommodation as seen on Scheimpflug imaging. PMID:25378883

Taking the Leap

ERIC Educational Resources Information Center

Tretter, Thomas

2012-01-01

Teachers strive to engage students in rich and varied experiences involving exploration. These experiences should be accessible to all types of learners (e.g., visual, kinesthetic, mathematically inclined), offering multiple pathways for engagement at different levels of sophistication and accommodating both conceptual and computational…

A survey of anthropometry and physical accommodation in ergonomics curricula.

PubMed

Garneau, Christopher J; Parkinson, Matthew B

2016-01-01

The size and shape of users are an important consideration for many products and environments. Designers and engineers in many disciplines must often accommodate these attributes to meet objectives such as fit and safety. When practitioners have academic training in addressing these issues, it is typically through courses in Human Factors/Ergonomics (HF/E). This paper investigates education related to physical accommodation and offers suggestions for improvement. A survey was conducted wherein 21 instructors at 18 universities in the United States provided syllabi for 29 courses, which were analysed to determine topics related to anthropometry and resources used for the courses. The results show that within the U.S., anthropometry is covered in the majority of courses discussing physical ergonomics, but important related concepts were often omitted (e.g., digital human modelling, multivariate accommodation and variability across global populations). Curricula could be improved by incorporating more accurate anthropometry, multivariate problems and interactive online tools. This paper describes a study investigating collegiate ergonomics courses within the U.S. in the area of physical accommodation. Course schedules and texts were studied for their treatment of several topics related to accommodating the spatial requirements (anthropometry) of users. Recommendations are made for improving course curricula.

Impact of Adaptive Materials on Teachers and their Students with Visual Impairments in Secondary Science and Mathematics Classes

NASA Astrophysics Data System (ADS)

Rule, Audrey C.; Stefanich, Greg P.; Boody, Robert M.; Peiffer, Belinda

2011-04-01

Science, technology, engineering, and mathematics (STEM) fields, important in today's world, are underrepresented by students with disabilities. Students with visual impairments, although cognitively similar to sighted peers, face challenges as STEM subjects are often taught using visuals. They need alternative forms of access such as enlarged or audio-converted text, tactile graphics, and involvement in hands-on science. This project focused on increasing teacher awareness of and providing funds for the purchase of supplemental adaptive resources, supplies, and equipment. We examined attitude and instructional changes across the year of the programme in 15 science and mathematics teachers educating students with visual impairments. Positive changes were noted from pretest to posttest in student and teacher perspectives, and in teacher attitudes towards students with disabilities in STEM classes. Teachers also provided insights into their challenges and successes through a reflective narrative. Several adolescent students resisted accommodations to avoid appearing conspicuous to peers. Teachers implemented three strategies to address this: providing the adaptations to all students in the class; convincing the student of the need for adaptation; and involving the class in understanding and accepting the student's impairment. A variety of teacher-created adaptations for various science and mathematics labs are reported. Another finding was many adaptations provided for the student with visual impairment benefitted the entire class. This study supports the claim that given knowledgeable, supportive teachers, and with appropriate accommodations such as tactile or auditory materials, students with visual impairments can be as successful and engaged as other students in science and mathematics.

Patient-centered and visual quality outcomes of premium cataract surgery: a systematic review.

PubMed

Wang, Sophia Y; Stem, Maxwell S; Oren, Gale; Shtein, Roni; Lichter, Paul R

2017-06-26

Over 8 million cataract surgeries are performed in the United States and the European Union annually, with many patients choosing to pay out of pocket for premium options including premium intraocular lens implants (IOLs) or laser-assisted cataract surgery (LACS). This report provides a systematic review evaluating patient-centered and visual quality outcomes comparing standard monofocal IOLs to premium cataract surgery options. PubMed and EMBASE were searched for publications published between January 1, 1980, and September 18, 2016, on multifocal, accommodative, and toric IOLs, monovision, and LACS, which reported on 1) dysphotopsias, 2) contrast sensitivity, 3) spectacle independence, 4) vision-related quality of life or patient satisfaction, and 5) IOL exchange. Multifocal lenses achieved higher rates of spectacle independence compared to monofocal lenses but also had higher reported frequency of dysphotopsia and worse contrast sensitivity, especially with low light or glare. Accommodative lenses were not associated with reduced contrast sensitivity or more dysphotopsia but had only modest improvements in spectacle independence compared to monofocal lenses. Studies of monovision did not target a sufficiently myopic outcome in the near-vision eye to achieve the full potential for spectacle independence. Patients reported high levels of overall satisfaction regardless of implanted IOL. No studies correlated patient-reported outcomes with patient expectations. Studies are needed to thoroughly compare patient-reported outcomes with concomitant patient expectations. In light of the substantial patient costs for premium options, patients and their surgeons will benefit from a better understanding of which surgical options best meet patients' expectations and how those expectations can be impacted by premium versus monofocal-including monovision-options.

Ameliorating effect of transcutaneous electroacupuncture on impaired gastric accommodation induced by cold meal in healthy subjects.

PubMed

Huang, Zhihui; Zhang, Nina; Xu, Feng; Yin, Jieyun; Dai, Ning; Chen, Jiande D Z

2016-03-01

Impaired gastric accommodation is recognized as one of major pathophysiologies in functional dyspepsia and gastroparesis. Electroacupuncture has been shown to improve gastric accommodation in laboratory settings. It is, however, unknown whether it exerts similar ameliorating effect in humans and whether needleless transcutaneous electroacupuncture (TEA) is also effective in improving gastric accommodation. The aim was to investigate the effects of TEA on gastric accommodation, gastric slow waves, and dyspeptic related symptoms. Thirteen healthy volunteers were studied in four randomized sessions: control, cold nutrient liquid, cold nutrient liquid + sham-TEA, and cold nutrient liquid + TEA. The subjects were requested to drink Ensure until reaching maximum satiety. The electrogastrogram (EGG) and electrocardiogram (ECG) were recorded to assess the gastric and autonomic functions respectively. 1) Gastric accommodation was reduced with the cold drink in comparison with the warm drink (P = 0.023). TEA improved the impaired gastric accommodation from 539.2 ± 133.8 ml to 731.0 ± 185.7 ml (P = 0.005). 2) The percentage of normal gastric slow waves in six subjects was significantly decreased in the cold session (P = 0.002) and improved in the TEA session (P = 0.009 vs sham; P < 0.001 vs cold). 3) TEA showed significant improvement in the bloating (80.8 ± 5.7 vs 61.2 ± 26.2, P = 0.011), postprandial fullness (48.1 ± 12.0 vs 34.2 ± 21.2, P = 0.042), and nausea (29.6 ± 10.9 vs 19.2 ± 11.2, P = 0.026) in comparison with sham-TEA session. 4) Neither cold drink nor TEA altered vagal activities (P > 0.05). TEA improves impaired gastric accommodation and slow waves induced by cold drink and the effect does not seem to be mediated via the vagal mechanisms. © 2016 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.

3DScapeCS: application of three dimensional, parallel, dynamic network visualization in Cytoscape

PubMed Central

2013-01-01

Background The exponential growth of gigantic biological data from various sources, such as protein-protein interaction (PPI), genome sequences scaffolding, Mass spectrometry (MS) molecular networking and metabolic flux, demands an efficient way for better visualization and interpretation beyond the conventional, two-dimensional visualization tools. Results We developed a 3D Cytoscape Client/Server (3DScapeCS) plugin, which adopted Cytoscape in interpreting different types of data, and UbiGraph for three-dimensional visualization. The extra dimension is useful in accommodating, visualizing, and distinguishing large-scale networks with multiple crossed connections in five case studies. Conclusions Evaluation on several experimental data using 3DScapeCS and its special features, including multilevel graph layout, time-course data animation, and parallel visualization has proven its usefulness in visualizing complex data and help to make insightful conclusions. PMID:24225050

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

PubMed

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

2011-08-11

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

Magnetic resonance imaging of aging, accommodating, phakic, and pseudophakic ciliary muscle diameters

PubMed Central

Strenk, Susan A.; Strenk, Lawrence M.; Guo, Suqin

2012-01-01

PURPOSE To quantify in vivo accommodative changes in the aging human ciliary muscle diameter in phakic and pseudophakic eyes. SETTING Department of Surgery/Bioengineering, UMDNJ–Robert Wood Johnson Medical School, Piscataway, and the Institute of Ophthalmology and Visual Science UMDNJ–New Jersey Medical School, Newark, New Jersey, USA. METHODS Images were acquired from 48 eyes of 40 people between the ages of 22 and 91 years, 1 eye of 32 phakic volunteers and both eyes of 8 patients who had monocular implantation of a single-piece AcrySof intraocular lens (IOL) (Alcon Laboratories). Images were acquired during physiological accommodation and with accommodation at rest, and the diameter of the ciliary muscle ring was measured. RESULTS Results show the ciliary muscle remains active throughout life. The accommodative change in its diameter (mean 0.64 mm) (P<.00001) was undiminished by age or IOL implantation. Preliminary data showed that the accommodative decrease in muscle diameter in phakic and pseudophakic eyes was statistically identical. The phakic eyes had a marked decrease in ciliary muscle diameter with advancing age for both accommodative states (P<.000001 and P<.000001), which did not appear to be altered by IOL implantation. The lens equator was constant with age in the unaccommodated human eye, resulting in decreased circumlental space with advancing age in the phakic eyes. CONCLUSION Although the undiminished ability of the ciliary muscle to decrease its diameter with accommodation can be relied on in strategies for presbyopia correction, even in advanced presbyopia, the decreasing circumlental space and its potential effects on zonular tension must also be considered. PMID:17081859

Accommodation-Amplitudes following an Accommodative Lens Refilling Procedure — an in vivo Update

PubMed Central

Nishi, Okihiro; Nishi, Yutaro; Chang, S.; Nishi, Kayo

2014-01-01

Purpose To investigate whether a newly developed lens refilling procedure can provide some accommodation in monkey eyes and to evaluate the difference in accommodation with different degrees of capsular bag refilling. Setting Jinshikai Medical Foundation, Nishi Eye Hospital, Osaka, Japan. Design Experimental monkey study. Methods Following a central 3–4 mm continuous curvilinear capsulorhexis, phacoemulsification was performed in the usual manner. A novel accommodative membrane intraocular lens for sealing capsular opening was implanted into the capsular bag. Silicone polymers were injected beneath the intraocular lens into the capsular bag through the delivery hole. In three study groups, each with six monkey eyes, the lens capsule was refilled with 0.08 ml corresponding to 65% bag volume, 0.1 ml corresponding to 80% bag volume, and 0.125 ml of silicone polymers corresponding to 100% bag volume, respectively. To calculate the accommodation-amplitudes achieved, automated refractometry was performed before and 1 hour after the topical 4% pilocarpine application before and four weeks after surgery. Results The refilling technique was successful in all monkeys without polymer leakage. Accommodation-amplitudes attained were 2.56 ± 0.74 dioptries (D), 2.42 ± 1.00D, and 2.71 ± 0.63D, respectively, 4 weeks after surgery in the three study groups. Conclusions Using the technique, some accommodation could be obtained in the young monkey eyes. Leakage of the injectable silicone polymer and anterior capsular opacification at least in the visual axis could be avoided. The results suggest that this lens refilling procedure warrants further studies for a possible clinical application. PMID:24461501

Age-Related Changes in Centripetal Ciliary Body Movement Relative to Centripetal Lens Movement in Monkeys

PubMed Central

Croft, Mary Ann; McDonald, Jared P.; Nadkarni, Nivedita V.; Lin, Ting-Li; Kaufman, Paul L.

2009-01-01

The goal was to determine the age-related changes in accommodative movements of the lens and ciliary body in rhesus monkeys. Varying levels of accommodation were stimulated via the Edinger-Westphal (E-W) nucleus in 26 rhesus monkeys, aged 6-27 years, and the refractive changes were measured by coincidence refractometry. Centripetal ciliary process (CP) and lens movements were measured by computerized image analysis of goniovideographic images. Ultrasound biomicroscopy (UBM) at 50 MHz was used to visualize and measure accommodative forward movements of the ciliary body in relation to age, accommodative amplitude, and centripetal CP and lens movements. At ∼3 diopters of accommodation, the amount of centripetal lens movement required did not significantly change with age (p=0.10; n=18 monkeys); however, the amount of centripetal CP movement required significantly increased with age (p=0.01; n=18 monkeys), while the amount of forward ciliary body movement significantly decreased with age (p=0.007; n=11 monkeys). In the middle-aged animals (12-16.5 years), a greater amount of centripetal CP movement was required to induce a given level of lens movement and thereby a given level of accommodation (p=0.01), compared to the young animals (6-10 yrs). Collectively, the data suggests that, with age, the accommodative system may be attempting to compensate for the loss of forward ciliary body movement by increasing the amount of centripetal CP movement. This, in turn, would allow enough zonular relaxation to achieve the magnitude of centripetal lens movement necessary for a given amplitude of accommodation. PMID:19635475

Visual Function of Moderately Hyperopic 4- and 5-Year-Old Children in the Vision In Preschoolers - Hyperopia In Preschoolers Study

PubMed Central

Ciner, Elise B.; Kulp, Marjean Taylor; Maguire, Maureen; Pistilli, Maxwell; Candy, T. Rowan; Moore, Bruce; Ying, Gui-shuang; Quinn, Graham; Orlansky, Gale; Cyert, Lynn

2016-01-01

Purpose To compare visual performance between emmetropic and uncorrected moderately hyperopic preschool age children without strabismus or amblyopia. Design Cross-sectional study. Methods Setting Multicenter, institutional. Patient or Study Population Children aged 4 or 5 years. Intervention or Observation Procedures Visual functions were classified as normal or reduced for each child based on the 95% confidence interval for emmetropes. Hyperopic (≥3.0 diopters [D] to ≤6.0D in the most hyperopic meridian; astigmatism≤1.50D; anisometropia≤1.0D) and emmetropic status were determined by cycloplegic autorefraction. Main Outcome Measures Uncorrected monocular distance and binocular near visual acuity (VA); accommodative response; and near random dot stereoacuity. Results Mean (±SD) LogMAR distance VA among 248 emmetropes was better than among 244 hyperopes for the better (0.05±0.10 vs. 0.14±0.11, p<.001) and worse eyes (0.10±0.11 vs. 0.19±0.10, p<.001). Mean binocular LogMAR near VA was better in emmetropes than hyperopes (0.13±0.11 vs. 0.21±0.11, p<.001). Mean accommodative response for emmetropes was lower than for hyperopes for both Monocular Estimation Method (1.03±0.51D vs. 2.03±1.03D, p<0.001) and Grand Seiko (0.46±0.45D vs. 0.99±1.0D, p<0.001). Median near stereoacuity was better in emmetropes than hyperopes (40 sec arc vs.120 sec arc, p<0.001). The average number of reduced visual functions was lower in emmetropic than in hyperopic children (.19 vs.1.0 p<0.001). Conclusions VA, accommodative response, and stereoacuity were significantly reduced in moderate uncorrected hyperopic preschool children compared to emmetropes. Higher hyperopes (≥4 to ≤6D) were at greatest risk, although more than half of children with lower magnitudes (≥3 to <4D) demonstrated one or more reductions in function. PMID:27477769

The accommodative ciliary muscle function is preserved in older humans

NASA Astrophysics Data System (ADS)

Tabernero, Juan; Chirre, Emmanuel; Hervella, Lucia; Prieto, Pedro; Artal, Pablo

2016-05-01

Presbyopia, the loss of the eye’s accommodation capability, affects all humans aged above 45-50 years old. The two main reasons for this to happen are a hardening of the crystalline lens and a reduction of the ciliary muscle functionality with age. While there seems to be at least some partial accommodating functionality of the ciliary muscle at early presbyopic ages, it is not yet clear whether the muscle is still active at more advanced ages. Previous techniques used to visualize the accommodation mechanism of the ciliary muscle are complicated to apply in the older subjects, as they typically require fixation stability during long measurement times and/or to have an ultrasound probe directly in contact with the eye. Instead, we used our own developed method based on high-speed recording of lens wobbling to study the ciliary muscle activity in a small group of pseudophakic subjects (around 80 years old). There was a significant activity of the muscle, clearly able to contract under binocular stimulation of accommodation. This supports a purely lenticular-based theory of presbyopia and it might stimulate the search for new solutions to presbyopia by making use of the remaining contraction force still presented in the aging eye.

Visual optics: Accommodation in a splash.

PubMed

Cronin, Thomas W

2012-10-23

Gannets are large seabirds that hunt fish from the air, making a plunge dive followed by active swimming pursuit of prey. A recent study shows that they convert from aerial to aquatic vision nearly instantly. Copyright © 2012 Elsevier Ltd. All rights reserved.

41 CFR Appendix A to Part 60 - 741-Guidelines on a Contractor's Duty To Provide Reasonable Accommodation

Code of Federal Regulations, 2011 CFR

2011-07-01

... visual aids, braille devices, talking calculators, magnifiers, audio recordings and brailled or large... vision or hearing impaired, e.g., by making an announcement available in braille, in large print, or on...

Astronomy for Everyone: Harvard's Move Toward an All-Inclusive Astronomy Lab and Telescope

NASA Astrophysics Data System (ADS)

Bieryla, Allyson

2016-01-01

Harvard University has a growing astronomy program that offers various courses to the undergraduate concentrators, secondaries and non-majors. Many of the courses involve labs that use the 16-inch DFM Clay Telescope for night-time observations and the heliostat for observing the Sun. The goal is to proactively adapt the lab and telescope facilities to accommodate all students with disabilities. The current focus is converting the labs to accommodate visually impaired students. Using tactile images and sound, the intention is to create an experience equivalent to that of a student with full sight.

[Spasm of accommodation].

PubMed

Lindberg, Laura

2014-01-01

Spasm of accommodation refers to prolonged contraction of the ciliary muscle, most commonly causing pseudomyopia to varying degrees in both eyes by keeping the lens in a state of short sightedness. It may also be manifested as inability to allow the adaptation spasticity prevailing in the ciliary muscle relax without measurable myopia. As a rule, this is a functional ailment triggered by prolonged near work and stress. The most common symptoms include blurring of distance vision, varying visual acuity as well as pains in the orbital region and the head, progressing into a chronic state. Cycloplegic eye drops are used as the treatment.

Dark focus of accommodation as dependent and independent variables in visual display technology

NASA Technical Reports Server (NTRS)

Jones, Sherrie; Kennedy, Robert; Harm, Deborah

1992-01-01

When independent stimuli are available for accommodation, as in the dark or under low contrast conditions, the lens seeks its resting position. Individual differences in resting positions are reliable, under autonomic control, and can change with visual task demands. We hypothesized that motion sickness in a flight simulator might result in dark focus changes. Method: Subjects received training flights in three different Navy flight simulators. Two were helicopter simulators entailed CRT presentation using infinity optics, one involved a dome presentation of a computer graphic visual projection system. Results: In all three experiments there were significant differences between dark focus activity before and after simulator exposure when comparisons were made between sick and not-sick pilot subjects. In two of these experiments, the average shift in dark focus for the sick subjects was toward increased myopia when each subject was compared to his own baseline. In the third experiment, the group showed an average shift outward of small amount and the subjects who were sick showed significantly less outward movement than those who were symptom free. Conclusions: Although the relationship is not a simple one, dark focus changes in simulator sickness imply parasympathetic activity. Because changes can occur in relation to endogenous and exogenous events, such measurement may have useful applications as dependent measures in studies of visually coupled systems, virtual reality systems, and space adaptation syndrome.

28 CFR 36.303 - Auxiliary aids and services.

Code of Federal Regulations, 2011 CFR

2011-07-01

...; videotext displays; accessible electronic and information technology; or other effective methods of making... electronic and information technology; or other effective methods of making visually delivered materials... circumstances. (4) A public accommodation shall not rely on a minor child to interpret or facilitate...

28 CFR 36.303 - Auxiliary aids and services.

Code of Federal Regulations, 2013 CFR

2013-07-01

...; videotext displays; accessible electronic and information technology; or other effective methods of making... electronic and information technology; or other effective methods of making visually delivered materials... circumstances. (4) A public accommodation shall not rely on a minor child to interpret or facilitate...

28 CFR 36.303 - Auxiliary aids and services.

Code of Federal Regulations, 2014 CFR

2014-07-01

...; videotext displays; accessible electronic and information technology; or other effective methods of making... electronic and information technology; or other effective methods of making visually delivered materials... circumstances. (4) A public accommodation shall not rely on a minor child to interpret or facilitate...

28 CFR 36.303 - Auxiliary aids and services.

Code of Federal Regulations, 2012 CFR

2012-07-01

...; videotext displays; accessible electronic and information technology; or other effective methods of making... electronic and information technology; or other effective methods of making visually delivered materials... circumstances. (4) A public accommodation shall not rely on a minor child to interpret or facilitate...

Accommodation and vergence latencies in human infants

PubMed Central

Tondel, Grazyna M.; Candy, T. Rowan

2008-01-01

Purpose Achieving simultaneous single and clear visual experience during postnatal development depends on the temporal relationship between accommodation and vergence, in addition to their accuracies. This study was designed to examine one component of the dynamic relationship, the latencies of the responses. Methods Infants and adults were tested in three conditions i) Binocular viewing of a target moving in depth at 5cm/s (closed loop) ii) monocular viewing of the same target (vergence open loop) iii) binocular viewing of a low spatial frequency Difference of Gaussian target during a prism induced step change in retinal disparity (accommodation open loop). Results There was a significant correlation between accommodation and vergence latencies in binocular conditions for infants from 7 to 23 weeks of age. Some of the infants, as young as 7 or 8 weeks, generated adult-like latencies of less than 0.5 s. Latencies in the vergence open loop and accommodation open loop conditions tended to be shorter for the stimulated system than the open loop system in both cases, and all latencies were typically less than 2 seconds across the infant age range. Conclusions Many infants between 7 and 23 weeks of age were able to generate accommodation and vergence responses with latencies of less than a second in full binocular closed loop conditions. The correlation between the latencies in the two systems suggests that they are limited by related factors from the earliest ages tested. PMID:18199466

Accommodation and vergence latencies in human infants.

PubMed

Tondel, Grazyna M; Candy, T Rowan

2008-02-01

Achieving simultaneous single and clear visual experience during postnatal development depends on the temporal relationship between accommodation and vergence, in addition to their accuracies. This study was designed to examine one component of the dynamic relationship, the latencies of the responses. Infants and adults were tested in three conditions (i) binocular viewing of a target moving in depth at 5 cm/s (closed loop) (ii) monocular viewing of the same target (vergence open loop) (iii) binocular viewing of a low spatial frequency Difference of Gaussian target during a prism induced step change in retinal disparity (accommodation open loop). There was a significant correlation between accommodation and vergence latencies in binocular conditions for infants from 7 to 23 weeks of age. Some of the infants, as young as 7 or 8 weeks, generated adult-like latencies of less than 0.5 s. Latencies in the vergence open loop and accommodation open loop conditions tended to be shorter for the stimulated system than the open loop system in both cases, and all latencies were typically less than 2 s across the infant age range. Many infants between 7 and 23 weeks of age were able to generate accommodation and vergence responses with latencies of less than a second in full binocular closed loop conditions. The correlation between the latencies in the two systems suggests that they are limited by related factors from the earliest ages tested.

Accommodation and pupil responses to random-dot stereograms

PubMed Central

Suryakumar, Rajaraman; Allison, Robert

2015-01-01

We investigated the dynamics of accommodative and pupillary responses to random-dot stereograms presented in crossed and uncrossed disparity in six visually normal young adult subjects (mean age = 25.8 ± 3.1 years). Accommodation and pupil measures were monitored monocularly with a custom built photorefraction system while subjects fixated at the center of a random-dot stereogram. On each trial, the stereogram initially depicted a flat plane and then changed to depict a sinusoidal corrugation in depth while fixation remained constant. Increase in disparity specified depth resulted in pupil constriction during both crossed and uncrossed disparity presentations. The change in pupil size between crossed and uncrossed disparity conditions was not significantly different (p > 0.05). The change in pupil size was also accompanied by a small concomitant increase in accommodation. In addition, the dynamic properties of pupil responses varied as a function of their initial (starting) diameter. The finding that accommodation and pupil responses increased with disparity regardless of the sign of retinal disparity suggests that these responses were driven by apparent depth rather than shifts in mean simulated distance of the stimulus. Presumably the need for the increased depth of focus when viewing stimuli extended in depth results in pupil constriction which also results in a concomitant change in accommodation. Starting position effects in pupil response confirm the non-linearity in the operating range of the pupil. PMID:25891121

Improving Meaningful Use of Accommodations by Multilingual Learners

ERIC Educational Resources Information Center

Shafer Willner, Lynn; Mokhtari, Kouider

2018-01-01

For more than two decades, accommodations have served as the primary strategy for ensuring the valid participation of multilingual learners (MLLs) in high-stakes summative assessments. Using historical analyses of the evolution of testing accommodation guidelines and related instructional practices, the authors explain how the application of…

Evaluating the effectiveness of using electroencephalogram power indices to measure visual fatigue.

PubMed

Hsu, Bin-Wei; Wang, Mao-Jiun J

2013-02-01

Electroencephalography (EEG) is widely used in cognitive and behavioral research. This study evaluates the effectiveness of using the EEG power index to measure visual fatigue. Three common visual fatigue measures, critical-flicker fusion (CFF), near-point accommodation (NPA), and subjective eye-fatigue rating, were used for comparison. The study participants were 20 men with a mean age of 20.4 yr. (SD = 1.5). The experimental task was a car-racing video game. Results indicated that the EEG power indices were valid as a visual fatigue measure and the sensitivity of the objective measures (CFF and EEG power index) was higher than the subjective measure. The EEG beta and EEG alpha were effective for measuring visual fatigue in short- and long-duration tasks, respectively. EEG beta/alpha were the most effective power indexes for the visual fatigue measure.

Good expert knowledge, small scope.

PubMed

Mayer, Horst

2014-01-01

During many years of occupational stress research, mostly within the German governmental program for "Humanization of Work Life'', remarkable deficits concerning visual work were seen, the most striking being the lack of cooperation between the different experts. With regard to this article hard arguments and ideas for solutions had to be found. A pilot study in 21 enterprises was realized (1602 employees with different visual work tasks). A test set of screening parameters (visual acuity, refraction, phoria, binocular cooperation and efficiency, accommodation range and color vision) were measured. The glasses and/or contact lenses worn were registered and the visual tasks analyzed. In work at visual display units (VDU) the eye movements were recorded and standardized questionnaires were given (health, stress, visual work situation). Because of the heterogeneity of the sample only simple statistics were applied: in groups of different visual work the complaints, symptoms, hassles and uplifts were clustered (SAS software) and correlated with the results of the visual tests. Later a special project in 8 companies (676 employees) was carried out. The results were published in [14]. Discomfort and asthenopic symptoms could be seen as an interaction of the combination of tasks and working conditions with the clusters of individual functionalisms, frequently originating in postural compromises. Mainly three causes for stress could be identified: 1. demands inadequate with regard to intensity, resolution, amount and/or time structure; 2. prevention of elementary perceptive needs; 3. entire use of partial capacities of the visual organ. Symptoms also were correlated with heteronomy. Other findings: influence of adaptation/accommodation ratio, the distracting role of attractors, especially in multitasking jobs; influence of high luminance differences. Dry eyes were very common, they could be attributed to a high screen position, low light, monotonous tasks and office climate. For some parameters a diurnal rhythm could be identified. Nowhere special programs for ageing employees were found: the right glasses; retinal problems and signs of destabilization of vision. In all enterprises, the ergophthalmological and visual ergonomic knowledge of the occupational physicians was poor, visual ergonomists were not available and there was only very poor cooperation with ophthalmologists and optometrists, the first of whom additionally had not much knowledge of modern work.

Spontaneous in-flight accommodation of hand orientation to unseen grasp targets: A case of action blindsight.

PubMed

Prentiss, Emily K; Schneider, Colleen L; Williams, Zoë R; Sahin, Bogachan; Mahon, Bradford Z

2018-03-15

The division of labour between the dorsal and ventral visual pathways is well established. The ventral stream supports object identification, while the dorsal stream supports online processing of visual information in the service of visually guided actions. Here, we report a case of an individual with a right inferior quadrantanopia who exhibited accurate spontaneous rotation of his wrist when grasping a target object in his blind visual field. His accurate wrist orientation was observed despite the fact that he exhibited no sensitivity to the orientation of the handle in a perceptual matching task. These findings indicate that non-geniculostriate visual pathways process basic volumetric information relevant to grasping, and reinforce the observation that phenomenal awareness is not necessary for an object's volumetric properties to influence visuomotor performance.

Partner Accommodation Moderates Treatment Outcomes for Couple Therapy for Posttraumatic Stress Disorder

PubMed Central

Fredman, Steffany J.; Pukay-Martin, Nicole D.; Macdonald, Alexandra; Wagner, Anne C.; Vorstenbosch, Valerie; Monson, Candice M.

2015-01-01

Objective Partner accommodation of posttraumatic stress disorder (PTSD) symptoms (i.e., altering one’s own behaviors to minimize patient distress and/or relationship conflict due to patients’ PTSD symptoms) has been shown to be positively associated with patient and partner psychopathology and negatively associated with patient and partner relationship satisfaction cross-sectionally. However, the prognostic value of partner accommodation in treatment outcomes is unknown. The goals of the present study were to determine if partner accommodation decreases as a function of couple therapy for PTSD and if pretreatment partner accommodation moderates the efficacy of couple therapy for PTSD. Method Thirty-nine patients with PTSD and their intimate partners (n = 39) were enrolled in a randomized controlled trial of cognitive-behavioral conjoint therapy (CBCT) for PTSD (Monson & Fredman, 2012) and received CBCT for PTSD immediately or after three months of waiting. Blinded assessors determined clinician-rated PTSD symptoms and patient-rated PTSD and depressive symptoms and relationship satisfaction at baseline, mid-treatment/4 weeks of waiting, and posttreatment/12 weeks of waiting. Results Contrary to expectation, partner accommodation levels did not change over time for either treatment condition. However, baseline partner accommodation significantly moderated treatment outcomes. Higher levels of partner accommodation were associated with greater improvements in PTSD, depressive symptoms, and relationship satisfaction among patients receiving CBCT for PTSD compared with waiting list. At lower levels of partner accommodation, patients in both groups improved or remained at low levels of these outcomes. Conclusions Individuals with PTSD who have more accommodating partners may be particularly well-suited for couple therapy for PTSD. PMID:26501498

14 CFR 382.43 - Must information and reservation services of carriers be accessible to individuals with visual...

Code of Federal Regulations, 2014 CFR

2014-01-01

... aircraft having a designed seating capacity of more than 60 passengers and owns or controls a primary Web... and ground or cruise accommodations), or tour component (e.g., a hotel stay) that must be purchased...

Uncovering the drivers of host-associated microbiota with joint species distribution modelling.

PubMed

Björk, Johannes R; Hui, Francis K C; O'Hara, Robert B; Montoya, Jose M

2018-06-01

In addition to the processes structuring free-living communities, host-associated microbiota are directly or indirectly shaped by the host. Therefore, microbiota data have a hierarchical structure where samples are nested under one or several variables representing host-specific factors, often spanning multiple levels of biological organization. Current statistical methods do not accommodate this hierarchical data structure and therefore cannot explicitly account for the effect of the host in structuring the microbiota. We introduce a novel extension of joint species distribution models (JSDMs) which can straightforwardly accommodate and discern between effects such as host phylogeny and traits, recorded covariates such as diet and collection site, among other ecological processes. Our proposed methodology includes powerful yet familiar outputs seen in community ecology overall, including (a) model-based ordination to visualize and quantify the main patterns in the data; (b) variance partitioning to assess how influential the included host-specific factors are in structuring the microbiota; and (c) co-occurrence networks to visualize microbe-to-microbe associations. © 2018 John Wiley & Sons Ltd.

[Evaluation of Motion Sickness Induced by 3D Video Clips].

PubMed

Matsuura, Yasuyuki; Takada, Hiroki

2016-01-01

The use of stereoscopic images has been spreading rapidly. Nowadays, stereoscopic movies are nothing new to people. Stereoscopic systems date back to 280 A.D. when Euclid first recognized the concept of depth perception by humans. Despite the increase in the production of three-dimensional (3D) display products and many studies on stereoscopic vision, the effect of stereoscopic vision on the human body has been insufficiently understood. However, symptoms such as eye fatigue and 3D sickness have been the concerns when viewing 3D films for a prolonged period of time; therefore, it is important to consider the safety of viewing virtual 3D contents as a contribution to society. It is generally explained to the public that accommodation and convergence are mismatched during stereoscopic vision and that this is the main reason for the visual fatigue and visually induced motion sickness (VIMS) during 3D viewing. We have devised a method to simultaneously measure lens accommodation and convergence. We used this simultaneous measurement device to characterize 3D vision. Fixation distance was compared between accommodation and convergence during the viewing of 3D films with repeated measurements. Time courses of these fixation distances and their distributions were compared in subjects who viewed 2D and 3D video clips. The results indicated that after 90 s of continuously viewing 3D images, the accommodative power does not correspond to the distance of convergence. In this paper, remarks on methods to measure the severity of motion sickness induced by viewing 3D films are also given. From the epidemiological viewpoint, it is useful to obtain novel knowledge for reduction and/or prevention of VIMS. We should accumulate empirical data on motion sickness, which may contribute to the development of relevant fields in science and technology.

Cerebral visual impairment in children: Causes and associated ophthalmological problems.

PubMed

Pehere, Niranjan; Chougule, Pratik; Dutton, Gordon N

2018-06-01

The aim of this study is to identify common causes, associated ophthalmological abnormalities, and systemic comorbidities in children in Andhra Pradesh, India, with cerebral visual impairment (CVI). A retrospective review of case records of all children aged <16 years with diagnosis of CVI seen between January 2016 and December 2016 was carried out. Data were collected for their age, gender, cause of CVI, refraction, accommodation, anterior and posterior segment examination findings, and systemic problems. A total of 124 patients were identified and studied (80 boys and 44 girls, mean age 5.23 years, 44.8% aged <2 years). The most common causes of CVI were hypoxic-ischemic encephalopathy (HIE) (34.4%), undetermined etiology (32.8%), neonatal seizures, and infantile spasms (16% each). The most common presenting complaints were poor vision (76%) and squint (11.2%). Profound visual impairment was seen in 88.8%, and 11.2% had high functioning CVI. Fifty-eight (46.4%) patients had significant refractive errors, 40 (32.25%) had strabismus, 4 (3.2%) had visually significant cataract, and 40 (32%) had optic atrophy. Motor delay was observed in 39.5%, speech delay was evident in 22.4%, and cognitive delay in 16%. HIE is the most common cause (one-third) of CVI in our population, and the majority of them presented at age <2 years (44.8%) with profound visual impairment (88.8%). A significant number of them have treatable ophthalmic conditions such as refractive errors (46.4%), accommodative insufficiency (12.1%), and cataract (3.2%), and more than one-third of them also have delay in other areas of development.

Professional Development to Improve Accommodations Decisions--A Review of the Literature. Synthesis Report 84

ERIC Educational Resources Information Center

Hodgson, Jennifer R.; Lazarus, Sheryl S.; Thurlow, Martha L.

2011-01-01

Teachers play an important role in making decisions about students' accommodations for instruction and assessment. Although teachers are a significant part of the decision-making process, "gaps" in teachers' accommodations knowledge are well documented. Some of these gaps may be due to challenges in providing teacher professional…

The Effects of Color to the Eye and its Importance for Heliport Lighting

DTIC Science & Technology

1996-08-01

beginning around middle age . The hardening of the lens makes it difficult for the ciliary muscles to squeeze the lens to accommodate near objects. This...deficiencies of the visual system is important when designing a new approach lighting system so that these effects are not worsened. The effects of aging ...older, our ability to perceive color at the extremes of the visual spectrum decreases due primarily to the aging effects of the eye’s components. Current

Ergonomic evaluation of interior design of Shoka vehicle and proposing recommendations for improvement.

PubMed

Mazloumi, Adel; Mohammadreze, Fallah

2012-01-01

One of the applications of ergonomics disciplinary is designing driver workstation compatible to users' characteristics. The aim of this study was evaluation of interior design of Shoka vehicle with respect to the accommodation for Iranian population and proposing suggestions for customizing design of this vehicle. This study was a descriptive-analytical study conducted among thirty men from Iranian drivers population in 5, 50, 95 percentiles of the stature variable. Objective variables related to the occupant packaging and vehicle visual aspects including anthropometric variables, frontal, lateral, and side view and so on were investigated first. Then, subjective variables related to the driver mental workload and body comfort discomfort were studied using BMDMW and comfort questionnaires during 2-hour driving trial sessions. Occupant packaging variables and hand-arm angle showed the least accommodation percent (%53). Seating angles showed low accommodation as well (%73). Among three percentile groups there were no significant differences between the mean values of mental workload during two hours driving task. And, the mean value related to the comfort discomfort was 3.9 during driving sessions. Considering the findings in this study, it can be conclude that seating angles need correction and optimization. Taking mental workload results into account, it can be concluded that the interior design of the studied car had no influence on drivers' mental workload. From the aspect of comfort discomfort, Shoka vehicle showed neutral state among drivers. Optimizing seating angles, decreasing vibration, correcting stiffness of seating pan are suggested for customization of the ergonomics aspect of this vehicle.

A flight by periscope and where it landed.

PubMed

Roscoe, Stanley N; Acosta, Hector M

2008-06-01

This study defines display design factors linking visual accommodation and the perceived size of distant objects. In 1947, in anticipation of augmented contact and sensor-relayed contact displays, a periscope was installed in an airplane to serve as a sensor-based contact display simulator. To achieve normal landing performance, however, the unity image had to be magnified. This successful intervention, first published in 1966 in Human Factors, implicated oculomotor mechanisms and higher perceptual functions and became the observational basis for a series of investigative hypotheses. Observers registered the perceived size of the collimated image of a "moon" by adjusting a disk of light while alternatively providing optometric measurements of accommodative distance. Various investigators found high correlations between focal distances and perceived moon sizes. The simulated moon provided a superior vehicle for revealing the relationship between focal distance and perceived size and the factors affecting both. The operational display design implications and the possibility of a partial explanation for the moon illusion provided the motivation for an important doctoral research project involving eight factors that affect both focal distance and perceived size. The investigation reaffirmed that virtual images, as found in head-up and head-mounted displays (HUDs and HMDs, respectively), do not consistently draw focus to optical infinity and that a variety of factors necessarily manipulated by display designers and present in many operational systems can affect visual performance partially through the mediation of accommodation.

The Use of Test Accommodations as a Gaming Strategy: A State-Level Exploration of Potential Gaming Tendencies in the 2007-2009 Period and Implications for Re-Directing Research on Gaming through Test Accommodations

ERIC Educational Resources Information Center

Saatcioglu, Argun; Skrtic, Thomas M.; DeLuca, Thomas A.

2016-01-01

The overuse of test accommodations (e.g., test readers, extra time, and calculators) for students with disabilities is a potential means of gaming the accountability system because it can inflate proficiency gains. However, no direct evidence on this problem exists, and findings on whether or not test accommodations improve test scores are…

Myopes show increased susceptibility to nearwork aftereffects.

PubMed

Ciuffreda, K J; Wallis, D M

1998-09-01

Some aspects of accommodation may be slightly abnormal (or different) in myopes, compared with accommodation in emmetropes and hyperopes. For example, the initial magnitude of accommodative adaptation in the dark after nearwork is greatest in myopes. However, the critical test is to assess this initial accommodative aftereffect and its subsequent decay in the light under more natural viewing conditions with blur-related visual feedback present, if a possible link between this phenomenon and clinical myopia is to be considered. Subjects consisted of adult late- (n = 11) and early-onset (n = 13) myopes, emmetropes (n = 11), and hyperopes (n = 9). The distance-refractive state was assessed objectively using an autorefractor immediately before and after a 10-minute binocular near task at 20 cm (5 diopters [D]). Group results showed that myopes were most susceptible to the nearwork aftereffect. It averaged 0.35 D in initial magnitude, with considerably faster posttask decay to baseline in the early-onset (35 seconds) versus late-onset (63 seconds) myopes. There was no myopic aftereffect in the remaining two refractive groups. The myopes showed particularly striking accommodatively related nearwork aftereffect susceptibility. As has been speculated and found by many others, transient pseudomyopia may cause or be a precursor to permanent myopia or myopic progression. Time-integrated increased retinal defocus causing axial elongation is proposed as a possible mechanism.

Distributed visualization of gridded geophysical data: the Carbon Data Explorer, version 0.2.3

NASA Astrophysics Data System (ADS)

Endsley, K. A.; Billmire, M. G.

2016-01-01

Due to the proliferation of geophysical models, particularly climate models, the increasing resolution of their spatiotemporal estimates of Earth system processes, and the desire to easily share results with collaborators, there is a genuine need for tools to manage, aggregate, visualize, and share data sets. We present a new, web-based software tool - the Carbon Data Explorer - that provides these capabilities for gridded geophysical data sets. While originally developed for visualizing carbon flux, this tool can accommodate any time-varying, spatially explicit scientific data set, particularly NASA Earth system science level III products. In addition, the tool's open-source licensing and web presence facilitate distributed scientific visualization, comparison with other data sets and uncertainty estimates, and data publishing and distribution.

An automated miniaturized Haploscope for testing binocular visual function

NASA Technical Reports Server (NTRS)

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

1976-01-01

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

Visualizing Sound with an Electro-Optical Eardrum

ERIC Educational Resources Information Center

Truncale, Nicholas P.; Graham, Michelle T.

2014-01-01

As science educators, one of our important responsibilities is ensuring students possess the proper tools and accommodations to examine phenomena in a laboratory setting. It is our job to innovate methods enabling students with disabilities to participate in all aspects of investigations. This article describes an experimental accommodation…

Building a Culture of Inclusion: Disability as Opportunity for Organizational Growth and Improving Patient Care.

PubMed

Ailey, Sarah H; Brown, Paula; Friese, Tanya R; Dugan, Shelia

2016-01-01

Administrators at Rush University Medical Center have made a commitment to diversity, including accommodating disabilities in the workplace and for students. This article explains extensive multilevel accommodations instituted by Rush University Medical Center that promote organizational growth and a healthier work environment and improve patient care.

The effects of cognitive-behavioral therapy for youth anxiety on sleep problems.

PubMed

Peterman, Jeremy S; Carper, Matthew M; Elkins, R Meredith; Comer, Jonathan S; Pincus, Donna B; Kendall, Philip C

2016-01-01

The present study examined (a) whether sleep related problems (SRPs) improved following cognitive-behavioral therapy (CBT) for youth with anxiety disorders, (b) whether variables that may link anxiety and SRPs (e.g., pre-sleep arousal, family accommodation, sleep hygiene) changed during treatment, and (c) whether such changes predicted SRPs at posttreatment. Youth were diagnosed with anxiety at pretreatment and received weekly CBT that targeted their principal anxiety diagnosis at one of two specialty clinics (N=69 completers, Mage=10.86). Results indicated that parent-reported SRPs improved from pre- to post-treatment and that treatment responders with regard to anxiety yielded greater SRP improvements than nonresponders. Parent report of bedtime resistance and sleep anxiety showed significant improvements. Youth reported lower rates of SRPs compared to their parents and did not demonstrate pre- to post-treatment changes in SRPs. Pre-sleep arousal and family accommodation decreased over treatment but did not predict lower SRPs at posttreatment. Higher accommodation was correlated with greater SRPs. Sleep hygiene evidenced no change and did not mediate links between accommodation and posttreatment SRPs. Copyright © 2015 Elsevier Ltd. All rights reserved.

User-Centered Evaluation of Visual Analytics

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

Scholtz, Jean C.

Visual analytics systems are becoming very popular. More domains now use interactive visualizations to analyze the ever-increasing amount and heterogeneity of data. More novel visualizations are being developed for more tasks and users. We need to ensure that these systems can be evaluated to determine that they are both useful and usable. A user-centered evaluation for visual analytics needs to be developed for these systems. While many of the typical human-computer interaction (HCI) evaluation methodologies can be applied as is, others will need modification. Additionally, new functionality in visual analytics systems needs new evaluation methodologies. There is a difference betweenmore » usability evaluations and user-centered evaluations. Usability looks at the efficiency, effectiveness, and user satisfaction of users carrying out tasks with software applications. User-centered evaluation looks more specifically at the utility provided to the users by the software. This is reflected in the evaluations done and in the metrics used. In the visual analytics domain this is very challenging as users are most likely experts in a particular domain, the tasks they do are often not well defined, the software they use needs to support large amounts of different kinds of data, and often the tasks last for months. These difficulties are discussed more in the section on User-centered Evaluation. Our goal is to provide a discussion of user-centered evaluation practices for visual analytics, including existing practices that can be carried out and new methodologies and metrics that need to be developed and agreed upon by the visual analytics community. The material provided here should be of use for both researchers and practitioners in the field of visual analytics. Researchers and practitioners in HCI and interested in visual analytics will find this information useful as well as a discussion on changes that need to be made to current HCI practices to make them more suitable to visual analytics. A history of analysis and analysis techniques and problems is provided as well as an introduction to user-centered evaluation and various evaluation techniques for readers from different disciplines. The understanding of these techniques is imperative if we wish to support analysis in the visual analytics software we develop. Currently the evaluations that are conducted and published for visual analytics software are very informal and consist mainly of comments from users or potential users. Our goal is to help researchers in visual analytics to conduct more formal user-centered evaluations. While these are time-consuming and expensive to carryout, the outcomes of these studies will have a defining impact on the field of visual analytics and help point the direction for future features and visualizations to incorporate. While many researchers view work in user-centered evaluation as a less-than-exciting area to work, the opposite is true. First of all, the goal is user-centered evaluation is to help visual analytics software developers, researchers, and designers improve their solutions and discover creative ways to better accommodate their users. Working with the users is extremely rewarding as well. While we use the term “users” in almost all situations there are a wide variety of users that all need to be accommodated. Moreover, the domains that use visual analytics are varied and expanding. Just understanding the complexities of a number of these domains is exciting. Researchers are trying out different visualizations and interactions as well. And of course, the size and variety of data are expanding rapidly. User-centered evaluation in this context is rapidly changing. There are no standard processes and metrics and thus those of us working on user-centered evaluation must be creative in our work with both the users and with the researchers and developers.« less

The Effectiveness of Academic Accommodations for School-Age Students with Traumatic Brain Injury. EBP Briefs. Volume 10, Issue 4

ERIC Educational Resources Information Center

Bush, Erin J.; Burge, Emily A.

2016-01-01

Clinical Question: What are the evidence-based classroom accommodations for school-age students with traumatic brain injury who are struggling academically, and do they improve academic performance as compared to no classroom accommodations? Method: Literature Review. Study Sources: Google Scholar, ASHA, PubMed, Academic Search Premier. Search…

Interference with olfactory memory by visual and verbal tasks.

PubMed

Annett, J M; Cook, N M; Leslie, J C

1995-06-01

It has been claimed that olfactory memory is distinct from memory in other modalities. This study investigated the effectiveness of visual and verbal tasks in interfering with olfactory memory and included methodological changes from other recent studies. Subjects were allocated to one of four experimental conditions involving interference tasks [no interference task; visual task; verbal task; visual-plus-verbal task] and presented 15 target odours. Either recognition of the odours or free recall of the odour names was tested on one occasion, either within 15 minutes of presentation or one week later. Recognition and recall performance both showed effects of interference of visual and verbal tasks but there was no effect for time of testing. While the results may be accommodated within a dual coding framework, further work is indicated to resolve theoretical issues relating to task complexity.

Electronic Media, Videodisc Technology, and the Visual Arts.

ERIC Educational Resources Information Center

Anderson, Frances E.

1985-01-01

The potential of electronic media for art education is examined. Discussed are computers, video recorders, interactive video discs, and two-way cable television. Emphasis is on laser videodisc technology. What changes must occur in the educational system to accommodate technology and discipline-based art education are also discussed. (Author/RM)

46 CFR 62.50-30 - Additional requirements for periodically unattended machinery plants.

Code of Federal Regulations, 2013 CFR

2013-10-01

... automatically and continuously charged. (e) Assistance-needed alarm. The engineer's assistance-needed alarm (see... period of time necessary for an engineer to respond at the ECC from the machinery spaces or engineers... engineers' accommodations. Other than fire or flooding alarms, this may be accomplished by summarized visual...

46 CFR 62.50-30 - Additional requirements for periodically unattended machinery plants.

Code of Federal Regulations, 2011 CFR

2011-10-01

... automatically and continuously charged. (e) Assistance-needed alarm. The engineer's assistance-needed alarm (see... period of time necessary for an engineer to respond at the ECC from the machinery spaces or engineers... engineers' accommodations. Other than fire or flooding alarms, this may be accomplished by summarized visual...

46 CFR 62.50-30 - Additional requirements for periodically unattended machinery plants.

Code of Federal Regulations, 2012 CFR

2012-10-01

... automatically and continuously charged. (e) Assistance-needed alarm. The engineer's assistance-needed alarm (see... period of time necessary for an engineer to respond at the ECC from the machinery spaces or engineers... engineers' accommodations. Other than fire or flooding alarms, this may be accomplished by summarized visual...

46 CFR 62.50-30 - Additional requirements for periodically unattended machinery plants.

Code of Federal Regulations, 2010 CFR

2010-10-01

... automatically and continuously charged. (e) Assistance-needed alarm. The engineer's assistance-needed alarm (see... period of time necessary for an engineer to respond at the ECC from the machinery spaces or engineers... engineers' accommodations. Other than fire or flooding alarms, this may be accomplished by summarized visual...

Visual Elements and Container Metaphors for Multi-Media.

ERIC Educational Resources Information Center

Howarth, Mike

1997-01-01

An interactive version of an educational radio program can be developed quickly and easily with a main menu interface that takes into account physical classroom conditions; interactive learning interfaces that accommodate eye and vision requirements of children; and a story interface design informed by the "container" metaphor and the 2-D…

Technology Resources: Mathematics Accessibility for All Not Accommodation for Some

ERIC Educational Resources Information Center

Duranczyk, Irene M.

2009-01-01

When faculty and learning assistance staff create teaching documents and web pages envisioning the widest range of users they can save time while achieving access for all. There are tools and techniques available to make mathematics visual, orally, and dynamically more accessible through multimodal presentation forms. Resources from Design…

78 FR 54363 - Agency Information Collection Activities: Proposed Request and Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-03

... substantial gainful activity because of their impairments, and we consider title XVI children eligible for payment if they have marked and severe functional limitations because of their impairments. SSA also uses... accommodation based on their blindness, or other visual impairment. SSA collects this information electronically...

Using Computers To Accommodate Learning Disabled Students in Mathematics Classes.

ERIC Educational Resources Information Center

Rapp, Rhonda H.; Gittinger, Dennis J.

A person with a learning disability usually has average or above average intelligence, but has difficulty taking in, remembering, or expressing information. Learning disabilities can involve visual processing speed, short-term memory processing, fluid reasoning, and long-term memory retrieval. These disorders are intrinsic to the individual and…

Assessment of Cognitive Style to Examine Students' Use of Hypermedia within Historic Costume.

ERIC Educational Resources Information Center

Frey, Diane; Simonson, Michael

1993-01-01

Cognitive style of 70 students in fashion merchandising or education was compared to their choice of media in a hypermedia lesson on costume using HyperCard. Students used hypermedia effectively to accommodate preferred style; 56% chose visual, 30% text, and 14% auditory. (SK)

Overcoming the momentum of anachronism: American geologic mapping in a twenty-first-century world

USGS Publications Warehouse

House, P. Kyle; Clark, Ryan; Kopera, Joe

2013-01-01

The practice of geologic mapping is undergoing conceptual and methodological transformation. Profound changes in digital technology in the past 10 yr have potential to impact all aspects of geologic mapping. The future of geologic mapping as a relevant scientific enterprise depends on widespread adoption of new technology and ideas about the collection, meaning, and utility of geologic map data. It is critical that the geologic community redefine the primary elements of the traditional paper geologic map and improve the integration of the practice of making maps in the field and office with the new ways to record, manage, share, and visualize their underlying data. A modern digital geologic mapping model will enhance scientific discovery, meet elevated expectations of modern geologic map users, and accommodate inevitable future changes in technology.

[Importance of occlusion therapy for amblyopia in partial unilateral congenital cataracts that are discovered late].

PubMed

Denion, E; Dedes, V; Bonne, M; Labalette, P; Berger, C; Guilbert, F; Bouckehove, S; Rouland, J-F

2004-11-01

The aim of this study is to investigate the importance of occlusion therapy for amblyopia in patients with partial unilateral congenital cataracts that were discovered after 24 months of age. A retrospective study was conducted on 11 patients, each of whom underwent a clinical examination including a cycloplegic refraction with atropine. The average age when the cataract was diagnosed was 35 months. The average distance visual acuity was 6/78 and the average near visual acuity was 35/175. Occlusion therapy using adhesive patches was started after refractive error correction. In two cases, observance was mediocre. Ametropia was found in every patient, with anisometropia in nine patients (alpha < 0.02). This anisometropia included an astigmatism that was always greater on the side with the cataract (alpha < 0.001), averaging 2.7 diopters. After occlusion therapy for amblyopia, the average visual acuity significantly improved to 6/22 in distance vision (alpha < 0.02) and 35/45 in near vision (alpha < 0.01). The average follow-up period was 28 months (5-60 months). Amblyopia is related to lens opacities as well as frequently associated anisometropia. Functional improvement is greater in near vision than in distance vision. With occlusion therapy for amblyopia, accommodation is preserved. This factor is of utmost importance as near vision is preferential in young children. This study provides an opportunity to recall the importance of refraction and occlusion therapy for amblyopia, which must be systematically attempted in cases of partial unilateral congenital cataracts before considering a surgical procedure.

Accommodation and Phoria in Children Wearing Multifocal Contact Lenses

PubMed Central

Gong, Celia R; Troilo, David; Richdale, Kathryn

2017-01-01

Purpose To determine the effect of multifocal contact lenses on accommodation and phoria in children. Methods This was a prospective, non-dispensing, randomized, crossover, single visit study. Myopic children with normal accommodation and binocularity and no history of myopia control treatment were enrolled and fitted with Coopervision Biofinity single vision (SV) and multifocal (MF, +2.50D center distance add) contact lenses. Accommodative responses (photorefraction) and phorias (Modified Thorington) were measured at 4 distances (>3m, 100cm, 40cm, 25cm). Secondary measures included high and low contrast logMAR acuity, accommodative amplitude and facility. Differences between contact lens designs were analyzed using repeated measures regression and paired t-tests. Results A total of 16 subjects, aged 10-15 years, completed the study. There was a small decrease in high (SV: -0.08, MF: +0.01) and low illumination (SV:-0.03, MF: +0.08) (both p<0.01) visual acuity, and contrast sensitivity (SV: 2.0, MF: 1.9 log units, p=0.015) with multifocals. Subjects were more exophoric at 40 cm (SV: -0.41, MF: -2.06 Δ) and 25cm (SV: -0.83, MF: -4.30 Δ) (both p<0.01). With multifocals, subjects had decreased accommodative responses at distance (SV: -0.04; MF: -0.37 D, p=0.02), 100 cm (SV: +0.37; MF: -0.35 D, p<0.01), 40 cm (SV: +1.82; MF: +0.62 D, p<0.01), and 25 cm (SV: +3.38; MF: +1.75 D, p<0.01). There were no significant differences in accommodative amplitude (p=0.66) or facility (p=0.54). Conclusions Children wearing multifocal contact lenses exhibited reduced accommodative responses and more exophoria at increasingly higher accommodative demands than with single vision contact lenses. This suggests that children may be relaxing their accommodation and using the positive addition or increased depth of focus from added spherical aberration of the multifocals. Further studies are needed to evaluate other lens designs, different amounts of positive addition and aberrations, and long-term adaptation to lenses. PMID:28027276

Design of an off-axis visual display based on a free-form projection screen to realize stereo vision

NASA Astrophysics Data System (ADS)

Zhao, Yuanming; Cui, Qingfeng; Piao, Mingxu; Zhao, Lidong

2017-10-01

A free-form projection screen is designed for an off-axis visual display, which shows great potential in applications such as flight training for providing both accommodation and convergence cues for pilots. The method based on point cloud is proposed for the design of the free-form surface, and the design of the point cloud is controlled by a program written in the macro-language. In the visual display based on the free-form projection screen, when the error of the screen along Z-axis is 1 mm, the error of visual distance at each filed is less than 1%. And the resolution of the design for full field is better than 1‧, which meet the requirement of resolution for human eyes.

Visual fatigue modeling for stereoscopic video shot based on camera motion

NASA Astrophysics Data System (ADS)

Shi, Guozhong; Sang, Xinzhu; Yu, Xunbo; Liu, Yangdong; Liu, Jing

2014-11-01

As three-dimensional television (3-DTV) and 3-D movie become popular, the discomfort of visual feeling limits further applications of 3D display technology. The cause of visual discomfort from stereoscopic video conflicts between accommodation and convergence, excessive binocular parallax, fast motion of objects and so on. Here, a novel method for evaluating visual fatigue is demonstrated. Influence factors including spatial structure, motion scale and comfortable zone are analyzed. According to the human visual system (HVS), people only need to converge their eyes to the specific objects for static cameras and background. Relative motion should be considered for different camera conditions determining different factor coefficients and weights. Compared with the traditional visual fatigue prediction model, a novel visual fatigue predicting model is presented. Visual fatigue degree is predicted using multiple linear regression method combining with the subjective evaluation. Consequently, each factor can reflect the characteristics of the scene, and the total visual fatigue score can be indicated according to the proposed algorithm. Compared with conventional algorithms which ignored the status of the camera, our approach exhibits reliable performance in terms of correlation with subjective test results.

Accommodating Remedial Readers in the General Education Setting: Is Listening-while-Reading Sufficient to Improve Factual and Inferential Comprehension?

ERIC Educational Resources Information Center

Schmitt, Ara J.; Hale, Andrea D.; McCallum, Elizabeth; Mauck, Brittany

2011-01-01

Word reading accommodations are commonly applied in the general education setting in an attempt to improve student comprehension and learning of curriculum content. This study examined the effects of listening-while-reading (LWR) and silent reading (SR) using text-to-speech assistive technology on the comprehension of 25 middle-school remedial…

Effect of vergence adaptation on convergence-accommodation: model simulations.

PubMed

Sreenivasan, Vidhyapriya; Bobier, William R; Irving, Elizabeth L; Lakshminarayanan, Vasudevan

2009-10-01

Several theoretical control models depict the adaptation effects observed in the accommodation and vergence mechanisms of the human visual system. Two current quantitative models differ in their approach of defining adaptation and in identifying the effect of controller adaptation on their respective cross-links between the vergence and accommodative systems. Here, we compare the simulation results of these adaptation models with empirical data obtained from emmetropic adults when they performed sustained near task through + 2D lens addition. The results of our experimental study showed an initial increase in exophoria (a divergent open-loop vergence position) and convergence-accommodation (CA) when viewing through +2D lenses. Prolonged fixation through the near addition lenses initiated vergence adaptation, which reduced the lens-induced exophoria and resulted in a concurrent reduction of CA. Both models showed good agreement with empirical measures of vergence adaptation. However, only one model predicted the experimental time course of reduction in CA. The pattern of our empirical results seem to be best described by the adaptation model that indicates the total vergence response to be a sum of two controllers, phasic and tonic, with the output of phasic controller providing input to the cross-link interactions.

Lot quality assurance sampling to monitor supplemental immunization activity quality: an essential tool for improving performance in polio endemic countries.

PubMed

Brown, Alexandra E; Okayasu, Hiromasa; Nzioki, Michael M; Wadood, Mufti Z; Chabot-Couture, Guillaume; Quddus, Arshad; Walker, George; Sutter, Roland W

2014-11-01

Monitoring the quality of supplementary immunization activities (SIAs) is a key tool for polio eradication. Regular monitoring data, however, are often unreliable, showing high coverage levels in virtually all areas, including those with ongoing virus circulation. To address this challenge, lot quality assurance sampling (LQAS) was introduced in 2009 as an additional tool to monitor SIA quality. Now used in 8 countries, LQAS provides a number of programmatic benefits: identifying areas of weak coverage quality with statistical reliability, differentiating areas of varying coverage with greater precision, and allowing for trend analysis of campaign quality. LQAS also accommodates changes to survey format, interpretation thresholds, evaluations of sample size, and data collection through mobile phones to improve timeliness of reporting and allow for visualization of campaign quality. LQAS becomes increasingly important to address remaining gaps in SIA quality and help focus resources on high-risk areas to prevent the continued transmission of wild poliovirus. © Crown copyright 2014.

[Effects of orthokeratology lenses on the magnitude of accommodative lag and accommodativeconvergence/accommodation].

PubMed

Ren, Qiujin; Yue, Hui; Zhou, Qing

2016-02-01

To evaluate the change in accommodative lag and accommodation convergence/accommodation (AC/A) after patients with myopia wear orthokeratology lenses. 
 A total of 48 myopic subjects (a test group), who wore orthokeratology lenses regularly, and 48 myopic subjects (a control group), who wore spectacles regularly, were enrolled for this study from January 2011 to January 2013 in Optometric Center, the Forth Hospital of Changsha. Accommodative lag was measured by fused cross cylinder method, where the patients should gaze at the front optotypes 40 cm away. Gradient of the AC/A ratio was measured by Von Grafe method to check closer distance heterophoria. Accommodative lag and AC/A ratio were analyzed by statistics.
 After 1-year follow-up, accommodative lag and AC/A rate in patients with low or moderate myopia in the test group was decreased in 1, 3, 6 months or 1 year compared with that in the control group (P<0.05). 
 Compared with spectacles, orthokeratology lenses are able to decrease accommodative lag and high AC/A rate in patients with low or moderate myopia. The relationship between accommodation and convergence is improved by orthokeratology lenses. Orthokeratology is an effective way to control myopia.

Performance of Students with Visual Impairments on High-Stakes Tests: A Pennsylvania Report Card

ERIC Educational Resources Information Center

Fox, Lynn A.

2012-01-01

Students with disabilities participate in high-stakes assessments to meet NCLB's newer proficiency standards. This study explored performance in reading and math on the Pennsylvania System of School Assessment (PSSA), Pennsylvania's grade-level assessment, to provide a foundational baseline on performance and accommodations used by students with…

Overview on Deaf-Blindness

ERIC Educational Resources Information Center

Miles, Barbara

2008-01-01

It may seem that deaf-blindness refers to a total inability to see or hear. However, in reality deaf-blindness is a condition in which the combination of hearing and visual losses in children cause "such severe communication and other develop mental and educational needs that they cannot be accommodated in special education programs solely for…

41 CFR Appendix A to Part 60 - 300-Guidelines on a Contractor's Duty To Provide Reasonable Accommodation

Code of Federal Regulations, 2011 CFR

2011-07-01

... include providing adaptive hardware and software for computers, electronic visual aids, braille devices, talking calculators, magnifiers, audio recordings and braille or large-print materials. For persons with... vision or hearing impaired, e.g., by making an announcement available in braille, in large print, or on...

Effect of heterophoria measurement technique on the clinical accommodative convergence to accommodation ratio.

PubMed

Escalante, Jaime Bernal; Rosenfield, Mark

2006-05-01

Measurement of the stimulus accommodative convergence to accommodation (AC/A) ratio is a standard procedure in clinical optometric practice. Typically, heterophoria is assessed at several accommodative stimulus levels, and the gradient of the vergence to accommodation function computed. A number of procedures are available for the subjective measurement of heterophoria, but it is unclear whether the use of different vergence measurement techniques will alter the obtained AC/A value. Accordingly, the current study compared AC/A ratios measured using 3 clinical subjective heterophoria tests, namely the von Graefe (VG), Maddox Rod (MR), and Modified Thorington (MT) procedures. The AC/A ratio was measured in 60 visually normal subjects between 20 and 25 years of age using each of the 3 procedures listed above. The accommodative stimulus was varied by the introduction of +/-1.00 diopter (D) spherical lenses over the distance refractive correction while subjects viewed a target at a viewing distance of 40 cm. To examine the repeatability of each procedure, the AC/A ratio was measured on 2 separate occasions for each measurement technique, with the 2 sessions being separated by at least 24 hours. Mean values of stimulus AC/A ratio measured using the VG, MR, and MT procedures were 3.47, 2.99, and 2.46Delta/D, respectively. These differences were significant (p=0.0001). In addition, the coefficient of repeatability for the 3 techniques was 2.22, 1.99, and 1.20 Delta/D, respectively. Ratios obtained using the Modified Thorington technique with +/-1.00 D lenses showed the best repeatability, whereas the poorest repeatability was found with the von Graefe technique when only +1.00 D lenses were used to vary the accommodative stimulus. Accordingly, we recommend that that Modified Thorington procedure with +/-1.00 D lenses be used to quantify heterophoria during clinical measurement of the stimulus AC/A ratio.

Changes in the dark focus of accommodation associated with simulator sickness

NASA Technical Reports Server (NTRS)

Fowlkes, Jennifer E.; Kennedy, Robert S.; Hettinger, Lawrence J.; Harm, Deborah L.

1993-01-01

The relationship between the dark focus of accommodation and simulator sickness, a form of motion sickness, was examined in three experiments. In Experiment 1, dark focus was measured in 18 college students in a laboratory setting before and after they viewed a projected motion scene depicting low altitude helicopter flight. In Experiments 2 and 3, dark focus was measured in pilots (N = 16 and 23, respectively) before and after they 'flew' in moving-base helicopter flight simulators with optical infinity CRT visual systems. The results showed that individuals who experienced simulator sickness had either an inward (myopic) change in dark focus (Experiments 1 and 3) or attenuated outward shifts in dark focus (Experiment 2) relative to participants who did not get sick. These results are consonant with the hypothesis that parasympathetic activity, which may be associated with simulator sickness, should result in changes in dark focus that are in a myopic direction. Night vision goggles, virtual environments, extended periods in microgravity, and heads-up displays all produce related visual symptomatology. Changes in dark focus may occur in these conditions, as well, and should be measured.

Accommodative Esotropia Treatment Plan Utilizing Simultaneous Strabismus Surgery and Photorefractive Keratectomy.

PubMed

Eustis, H Sprague; Shah, Pulin

2018-03-01

Accommodative esotropia is a common cause of acquired esotropia. Pathogenesis varies among patients but usually includes excessive hyperopia and a high accommodative convergence/accommodation ratio or tight medial recti. The present study reviews an individualized treatment plan combining photorefractive keratectomy (PRK) and strabismus surgery to correct these problems. This study is a retrospective, interventional case series. Records for 15 patients who were treated for accommodative esotropia were reviewed. Patient ages ranged from 11 to 19 years. PRK and strabismus surgery were performed on 11 patients, and PRK only on 4 patients. The goal was to create a physiologic refractive error, good visual acuity (VA), and straight eyes without correction. All patients were spectacle free at 6-month follow-up. Twenty-four of 30 eyes had VA equal to preoperative VA without correction. Three eyes had a 1-line reduction and 2-line reduction in VA. The alignment results were ±10 prism diopters in 13 of 15 patients. Spherical refractive outcomes were 18 of 30 eyes within 1 diopter (D) of target and 12 of 30 eyes within 2 D of target. Astigmatism refractive outcomes were 21 of 30 eyes <1 D, 7 eyes 1-2 D, and 2 eyes >2 D. Two patients complained of halos at night, and 1 patient had peripheral corneal haze. Simultaneous PRK and strabismus surgery is safe and effective in treating accommodative esotropia. An individualized treatment plan can result in a physiologic refractive error, good VA, and a spectacle-free existence. Copyright © 2018 Elsevier Inc. All rights reserved.

Three-dimensional magnetic resonance imaging of the phakic crystalline lens during accommodation.

PubMed

Sheppard, Amy L; Evans, C John; Singh, Krish D; Wolffsohn, James S; Dunne, Mark C M; Davies, Leon N

2011-06-01

To quantify changes in crystalline lens curvature, thickness, equatorial diameter, surface area, and volume during accommodation using a novel two-dimensional magnetic resonance imaging (MRI) paradigm to generate a complete three-dimensional crystalline lens surface model. Nineteen volunteers, aged 19 to 30 years, were recruited. T(2)-weighted MRIs, optimized to show fluid-filled chambers of the eye, were acquired using an eight-channel radio frequency head coil. Twenty-four oblique-axial slices of 0.8 mm thickness, with no interslice gaps, were acquired to visualize the crystalline lens. Three Maltese cross-type accommodative stimuli (at 0.17, 4.0, and 8.0 D) were presented randomly to the subjects in the MRI to examine lenticular changes with accommodation. MRIs were analyzed to generate a three-dimensional surface model. During accommodation, mean crystalline lens thickness increased (F = 33.39, P < 0.001), whereas lens equatorial diameter (F = 24.00, P < 0.001) and surface radii both decreased (anterior surface, F = 21.78, P < 0.001; posterior surface, F = 13.81, P < 0.001). Over the same stimulus range, mean crystalline lens surface area decreased (F = 7.04, P < 0.005) with a corresponding increase in lens volume (F = 6.06, P = 0.005). These biometric changes represent a 1.82% decrease and 2.30% increase in crystalline lens surface area and volume, respectively. CONCLUSIONS; The results indicate that the capsular bag undergoes elastic deformation during accommodation, causing reduced surface area, and the observed volumetric changes oppose the theory that the lens is incompressible.

7 CFR 1744.20 - General.

Code of Federal Regulations, 2010 CFR

2010-01-01

... of outstanding Government debt may be improved as a result of providing such telecommunications..., RUS is willing to consider accommodating the Government's lien on telecommunications borrowers' systems or accommodating or subordinating the Government's lien on after-acquired property of...

Employer benefits from making workplace accommodations.

PubMed

Solovieva, Tatiana I; Dowler, Denetta L; Walls, Richard T

2011-01-01

This study explored workplace disability accommodations and their benefits. The participants were employers and human resource professionals who had not used the services of the Job Accommodation Network (JAN). The companies included large businesses (more than 499 employees) and small businesses (fewer than 500 employees). The intent of this investigation was to assess the disability accommodations and benefits for the employers. The study used responses to online survey from194 employers to discuss disability-related accommodations for an employee or potential employee. The survey included 128 employers who reported having had a person with a disability who requested an accommodation. As reported by the employers, the most frequently mentioned direct benefits from implementing workplace accommodations were (a) retained a qualified employee, (b) increased worker productivity, and (c) eliminated the cost of training a new employee. The most frequently mentioned indirect benefits from accommodations were (a) improved interactions with coworkers, (b) increased overall company morale, and (c) increased overall company productivity. The most frequently reported types of implemented accommodations were buying equipment and changing work schedules. Most of the respondents estimated the direct benefits of having made an accommodation at more than $1000. The findings heighten awareness of benefits associated with making accommodations for people with disabilities in the workplace. These benefits signify value for business, coworkers, and individuals with disabilities for whom accommodations are critical for successful employment. Published by Elsevier Inc.

An improved Michelson interferometer: smoothing out the rough spots for a more effective teaching tool

NASA Astrophysics Data System (ADS)

Eastman, Clarke K.

2017-08-01

The Michelson interferometer is a classic tool for demonstrating the wave nature of light, and it is a cornerstone of the optics curriculum. But many students' experiences with this device are higher in frustration than they are in learning. That situation motivated an effort to make aligning the tool less a test of a visual acuity and patience, and more of an introduction to optics phenomena and optical engineering. Key improvements included an added beam-splitter to accommodate multiple observers, a modified telescope to quickly and reliably obtain parallel mirrors, and a series of increasing spectral-width light sources to obtain equal path lengths. This greatly improved students' chances of success, as defined by achieving "white light fringes". When presenting these new features to the students, high importance is placed on understanding why alignment was so difficult with the original design, and why the changes made alignment easier. By exposing the rationale behind the improvements, students can observe the process of problem-solving in an optical engineering scenario. Equally important is the demonstration that solutions can be devised or adapted based on the parts at hand, and that implementations only achieve a highly "polished' state after several design iterations.

Virtual workstations and telepresence interfaces: Design accommodations and prototypes for Space Station Freedom evolution

NASA Technical Reports Server (NTRS)

Mcgreevy, Michael W.

1990-01-01

An advanced human-system interface is being developed for evolutionary Space Station Freedom as part of the NASA Office of Space Station (OSS) Advanced Development Program. The human-system interface is based on body-pointed display and control devices. The project will identify and document the design accommodations ('hooks and scars') required to support virtual workstations and telepresence interfaces, and prototype interface systems will be built, evaluated, and refined. The project is a joint enterprise of Marquette University, Astronautics Corporation of America (ACA), and NASA's ARC. The project team is working with NASA's JSC and McDonnell Douglas Astronautics Company (the Work Package contractor) to ensure that the project is consistent with space station user requirements and program constraints. Documentation describing design accommodations and tradeoffs will be provided to OSS, JSC, and McDonnell Douglas, and prototype interface devices will be delivered to ARC and JSC. ACA intends to commercialize derivatives of the interface for use with computer systems developed for scientific visualization and system simulation.

Orthoptic status before and immediately after heroin detoxification

PubMed Central

Firth, A Y; Pulling, S; Carr, M P; Beaini, A Y

2004-01-01

Aim: To determine whether changes in orthoptic status take place during withdrawal from heroin and/or methadone. Method: A prospective study of patients, using a repeated measures design, attending a 5 day naltrexone compressed opiate detoxification programme. Results: 83 patients were seen before detoxification (mean age 27.1 (SD 4.6) years) and 69 after detoxification. The horizontal angle of deviation became less exo/more eso at distance (p<0.001) but no significant change was found at near (p = 0.069). Stereoacuity, visual acuity, and convergence were found to be reduced in the immediate post-detoxification period. Prism fusion range, refractive error, subjective accommodation, and objective accommodation at 33 cm did not reduce but a small decrease was found in objective accommodation at 20 cm. Conclusions: The eso trend found in these patients may be responsible for the development of acute concomitant esotropia in some patients undergoing heroin detoxification. However, the mechanism for this trend does not appear to be caused by divergence insufficiency or sixth nerve palsy. PMID:15317713

Music and words in the visual cortex: The impact of musical expertise.

PubMed

Mongelli, Valeria; Dehaene, Stanislas; Vinckier, Fabien; Peretz, Isabelle; Bartolomeo, Paolo; Cohen, Laurent

2017-01-01

How does the human visual system accommodate expertise for two simultaneously acquired symbolic systems? We used fMRI to compare activations induced in the visual cortex by musical notation, written words and other classes of objects, in professional musicians and in musically naïve controls. First, irrespective of expertise, selective activations for music were posterior and lateral to activations for words in the left occipitotemporal cortex. This indicates that symbols characterized by different visual features engage distinct cortical areas. Second, musical expertise increased the volume of activations for music and led to an anterolateral displacement of word-related activations. In musicians, there was also a dramatic increase of the brain-scale networks connected to the music-selective visual areas. Those findings reveal that acquiring a double visual expertise involves an expansion of category-selective areas, the development of novel long-distance functional connectivity, and possibly some competition between categories for the colonization of cortical space. Copyright © 2016 Elsevier Ltd. All rights reserved.

Convergence Insufficiency, Accommodative Insufficiency, Visual Symptoms, and Astigmatism in Tohono O'odham Students

PubMed Central

Twelker, J. Daniel; Miller, Joseph M.; Campus, Irene

2016-01-01

Purpose. To determine rate of convergence insufficiency (CI) and accommodative insufficiency (AI) and assess the relation between CI, AI, visual symptoms, and astigmatism in school-age children. Methods. 3rd–8th-grade students completed the Convergence Insufficiency Symptom Survey (CISS) and binocular vision testing with correction if prescribed. Students were categorized by astigmatism magnitude (no/low: <1.00 D, moderate: 1.00 D to <3.00 D, and high: ≥3.00 D), presence/absence of clinical signs of CI and AI, and presence of symptoms. Analyses determine rate of clinical CI and AI and symptomatic CI and AI and assessed the relation between CI, AI, visual symptoms, and astigmatism. Results. In the sample of 484 students (11.67 ± 1.81 years of age), rate of symptomatic CI was 6.2% and symptomatic AI 18.2%. AI was more common in students with CI than without CI. Students with AI only (p = 0.02) and with CI and AI (p = 0.001) had higher symptom scores than students with neither CI nor AI. Moderate and high astigmats were not at increased risk for CI or AI. Conclusions. With-the-rule astigmats are not at increased risk for CI or AI. High comorbidity rates of CI and AI and higher symptoms scores with AI suggest that research is needed to determine symptomatology specific to CI. PMID:27525112

Reducing Visual Discomfort with HMDs Using Dynamic Depth of Field.

PubMed

Carnegie, Kieran; Rhee, Taehyun

2015-01-01

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

The provision of workplace accommodations following cancer: survivor, provider, and employer perspectives.

PubMed

Stergiou-Kita, Mary; Pritlove, Cheryl; van Eerd, Dwayne; Holness, Linn D; Kirsh, Bonnie; Duncan, Andrea; Jones, Jennifer

2016-06-01

With improvements in screening, diagnosis, and treatment, the number of persons surviving cancer and staying at or returning to work is increasing. While workplace accommodations optimize workers' abilities to participate in the workforce, there has been little in-depth investigation of the types of accommodations reported to have been provided to cancer survivors and the processes relevant to ensuring their successful implementation. We employed an exploratory qualitative method and conducted 40 semi-structured interviews with three groups: (i) cancers survivors (n = 16), (ii) health/vocational service providers (n = 16), and (iii) employer representatives (n = 8) to explore return to work and accommodation processes, successes, and challenges. An inductive thematic analysis approach was used to analyze the data. Four types of accommodations were recommended: (1) graduated return to work plans and flexible scheduling, (2) modification of work duties and performance expectations, (3) retraining and supports at the workplace, and (4) modification of the physical work environment and/or the provision of adaptive aids/technologies. Processes relevant to ensuring effective accommodations included: (1) developing knowledge about accommodations, (2) employer's ability to accommodate, (3) negotiating reasonable accommodations, (4) customizing accommodations, and (5) implementing and monitoring accommodation plans. Accommodation challenges included: (1) survivors' fears requesting accommodations, (2) developing clear and specific accommodations, (3) difficult to accommodate jobs, and (4) workplace challenges, including strained pre-cancer workplace relationships, insufficient/inflexible workplace policies, employer concerns regarding productivity and precedent setting, and limited modified duties. Accommodations need to be customized and clearly linked to survivors' specific job demands, work context, and available workplace supports. Survivors need to feel comfortable disclosing the need for accommodations. Ongoing communication and monitoring are required to ensure accommodations are implemented and changes made to the return to work plan as required. The provision of appropriate workplace accommodations can enhance survivors' abilities to stay or return to work.

SURVEY AND SUMMARY: The morph server: a standardized system for analyzing and visualizing macromolecular motions in a database framework

PubMed Central

Krebs, Werner G.; Gerstein, Mark

2000-01-01

The number of solved structures of macromolecules that have the same fold and thus exhibit some degree of conformational variability is rapidly increasing. It is consequently advantageous to develop a standardized terminology for describing this variability and automated systems for processing protein structures in different conformations. We have developed such a system as a ‘front-end’ server to our database of macromolecular motions. Our system attempts to describe a protein motion as a rigid-body rotation of a small ‘core’ relative to a larger one, using a set of hinges. The motion is placed in a standardized coordinate system so that all statistics between any two motions are directly comparable. We find that while this model can accommodate most protein motions, it cannot accommodate all; the degree to which a motion can be accommodated provides an aid in classifying it. Furthermore, we perform an adiabatic mapping (a restrained interpolation) between every two conformations. This gives some indication of the extent of the energetic barriers that need to be surmounted in the motion, and as a by-product results in a ‘morph movie’. We make these movies available over the Web to aid in visualization. Many instances of conformational variability occur between proteins with somewhat different sequences. We can accommodate these differences in a rough fashion, generating an ‘evolutionary morph’. Users have already submitted hundreds of examples of protein motions to our server, producing a comprehensive set of statistics. So far the statistics show that the median submitted motion has a rotation of ~10° and a maximum Cα displacement of 17 Å. Almost all involve at least one large torsion angle change of >140°. The server is accessible at http://bioinfo.mbb.yale.edu/MolMovDB PMID:10734184

Family accommodation mediates the association between anxiety symptoms in mothers and children.

PubMed

Jones, Johnna D; Lebowitz, Eli R; Marin, Carla E; Stark, Kevin D

2015-01-01

The link between child anxiety and maternal anxiety has been well established but the factors underlying this association are not well understood. One potential factor is family accommodation, which describes ways in which parents change their behaviour to help a child avoid or alleviate anxiety. Family accommodation has been associated with greater symptom severity, more impairment and poorer treatment outcomes in the child. The aim of this study was to investigate whether maternal accommodation mediates the relation between parent and child anxiety. Mothers of children (N = 85) aged 7-17 years (M = 11.79) completed measures of their own anxiety (State-Trait Anxiety Inventory (STAI)), their child's anxiety (Screen for Child Anxiety Related Disorders (SCARED)), and family accommodation (Family Accommodation Scale Anxiety (FASA)). Structural equation modelling (SEM) was used to test the mediational role of accommodation linking parent and child anxiety. Family accommodation was found to significantly mediate the link between maternal anxiety and child anxiety. These results inform theory and imply that the development of interventions designed to target family accommodation may improve the prognosis of those diagnosed with paediatric anxiety disorders and youth with subclinical anxiety symptoms by reducing both parent and child anxiety.

Surface flow visualization using indicators

NASA Technical Reports Server (NTRS)

Crowder, J. P.

1982-01-01

Surface flow visualization using indicators in the cryogenic wind tunnel which requires a fresh look at materials and procedures to accommodate the new test conditions is described. Potential liquid and gaseous indicators are identified. The particular materials illustrate the various requirements an indicator must fulfill. The indicator must respond properly to the flow phenomenon of interest and must be observable. Boundary layer transition is the most important phenomenon for which flow visualization indicators may be employed. The visibility of a particular indicator depends on utilizing various optical or chemical reactions. Gaseous indicators are more difficult to utilize, but because of their diversity may present unusual and useful opportunities. Factors to be considered in selecting an indicator include handling safety, toxicity, potential for contamination of the tunnel, and cost.

Reading in Two Writing Systems: Accommodation and Assimilation of the Brain's Reading Network

ERIC Educational Resources Information Center

Perfetti, Charles A.; Liu, Ying; Fiez, Julie; Nelson, Jessica; Bolger, Donald J.; Tan, Li-Hai

2007-01-01

Bilingual reading can require more than knowing two languages. Learners must acquire also the writing conventions of their second language, which can differ in its deep mapping principles (writing system) and its visual configurations (script). We review ERP (event-related potential) and fMRI studies of both Chinese-English bilingualism and…

The Influence of a Response Format Test Accommodation for College Students with and without Disabilities

ERIC Educational Resources Information Center

Potter, Kyle; Lewandowski, Lawrence; Spenceley, Laura

2016-01-01

Standardised and other multiple-choice examinations often require the use of an answer sheet with fill-in bubbles (i.e. "bubble" or Scantron sheet). Students with disabilities causing impairments in attention, learning and/or visual-motor skill may have difficulties with multiple-choice examinations that employ such a response style.…

Using Computational Simulations to Confront Students' Mental Models

ERIC Educational Resources Information Center

Rodrigues, R.; Carvalho, P. Simeão

2014-01-01

In this paper we show an example of how to use a computational simulation to obtain visual feedback for students' mental models, and compare their predictions with the simulated system's behaviour. Additionally, we use the computational simulation to incrementally modify the students' mental models in order to accommodate new data,…

A Visual Information Tool for User Participation during the Lifecycle of School Building Design: BIM

ERIC Educational Resources Information Center

Koutamanis, Alexander; Heuer, Jos; Könings, Karen D.

2017-01-01

User participation is a key element in decision processes concerning the accommodation of dynamic organisations such as schools. This article addresses the discrepancy between the perspectives of the architects and engineers, as the makers of school buildings, and school management, teachers and students, as the users of the buildings, and…

Learning Outcomes of Factual Knowledge: A Comparison of Module and No Module Conditions

ERIC Educational Resources Information Center

IRIS Center, 2017

2017-01-01

During the 2004-2005 academic year, a study of the learning outcomes associated with the use of an IRIS Module was conducted at a large urban campus with a diverse student body. The module's content pertained to instructional accommodations for students with visual disabilities. In an introductory class aimed primarily at general and special…

Linking the Nature of Secondary School Students Who Are Highly Artistic with Curriculum Needs and Instructional Practice

ERIC Educational Resources Information Center

Visconti, Victoria

2012-01-01

This exploratory qualitative investigation examined the nature of 7 secondary school students who are highly artistic to link visual arts programs that best accommodate their learning needs. Instrumentation for data collection included 1 questionnaire, 3 in-depth semistructured one-on-one interviews, artwork documents, observations, and field…

BactoGeNIE: A large-scale comparative genome visualization for big displays

DOE PAGES

Aurisano, Jillian; Reda, Khairi; Johnson, Andrew; ...

2015-08-13

The volume of complete bacterial genome sequence data available to comparative genomics researchers is rapidly increasing. However, visualizations in comparative genomics--which aim to enable analysis tasks across collections of genomes--suffer from visual scalability issues. While large, multi-tiled and high-resolution displays have the potential to address scalability issues, new approaches are needed to take advantage of such environments, in order to enable the effective visual analysis of large genomics datasets. In this paper, we present Bacterial Gene Neighborhood Investigation Environment, or BactoGeNIE, a novel and visually scalable design for comparative gene neighborhood analysis on large display environments. We evaluate BactoGeNIE throughmore » a case study on close to 700 draft Escherichia coli genomes, and present lessons learned from our design process. In conclusion, BactoGeNIE accommodates comparative tasks over substantially larger collections of neighborhoods than existing tools and explicitly addresses visual scalability. Given current trends in data generation, scalable designs of this type may inform visualization design for large-scale comparative research problems in genomics.« less

BactoGeNIE: a large-scale comparative genome visualization for big displays

PubMed Central

2015-01-01

Background The volume of complete bacterial genome sequence data available to comparative genomics researchers is rapidly increasing. However, visualizations in comparative genomics--which aim to enable analysis tasks across collections of genomes--suffer from visual scalability issues. While large, multi-tiled and high-resolution displays have the potential to address scalability issues, new approaches are needed to take advantage of such environments, in order to enable the effective visual analysis of large genomics datasets. Results In this paper, we present Bacterial Gene Neighborhood Investigation Environment, or BactoGeNIE, a novel and visually scalable design for comparative gene neighborhood analysis on large display environments. We evaluate BactoGeNIE through a case study on close to 700 draft Escherichia coli genomes, and present lessons learned from our design process. Conclusions BactoGeNIE accommodates comparative tasks over substantially larger collections of neighborhoods than existing tools and explicitly addresses visual scalability. Given current trends in data generation, scalable designs of this type may inform visualization design for large-scale comparative research problems in genomics. PMID:26329021

BactoGeNIE: A large-scale comparative genome visualization for big displays

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

Aurisano, Jillian; Reda, Khairi; Johnson, Andrew

The volume of complete bacterial genome sequence data available to comparative genomics researchers is rapidly increasing. However, visualizations in comparative genomics--which aim to enable analysis tasks across collections of genomes--suffer from visual scalability issues. While large, multi-tiled and high-resolution displays have the potential to address scalability issues, new approaches are needed to take advantage of such environments, in order to enable the effective visual analysis of large genomics datasets. In this paper, we present Bacterial Gene Neighborhood Investigation Environment, or BactoGeNIE, a novel and visually scalable design for comparative gene neighborhood analysis on large display environments. We evaluate BactoGeNIE throughmore » a case study on close to 700 draft Escherichia coli genomes, and present lessons learned from our design process. In conclusion, BactoGeNIE accommodates comparative tasks over substantially larger collections of neighborhoods than existing tools and explicitly addresses visual scalability. Given current trends in data generation, scalable designs of this type may inform visualization design for large-scale comparative research problems in genomics.« less

Deformable Surface Accommodating Intraocular Lens: Second Generation Prototype Design Methodology and Testing.

PubMed

McCafferty, Sean J; Schwiegerling, Jim T

2015-04-01

Present an analysis methodology for developing and evaluating accommodating intraocular lenses incorporating a deformable interface. The next generation design of extruded gel interface intraocular lens is presented. A prototype based upon similar previously in vivo proven design was tested with measurements of actuation force, lens power, interface contour, optical transfer function, and visual Strehl ratio. Prototype verified mathematical models were used to optimize optical and mechanical design parameters to maximize the image quality and minimize the required force to accommodate. The prototype lens produced adequate image quality with the available physiologic accommodating force. The iterative mathematical modeling based upon the prototype yielded maximized optical and mechanical performance through maximum allowable gel thickness to extrusion diameter ratio, maximum feasible refractive index change at the interface, and minimum gel material properties in Poisson's ratio and Young's modulus. The design prototype performed well. It operated within the physiologic constraints of the human eye including the force available for full accommodative amplitude using the eye's natural focusing feedback, while maintaining image quality in the space available. The parameters that optimized optical and mechanical performance were delineated as those, which minimize both asphericity and actuation pressure. The design parameters outlined herein can be used as a template to maximize the performance of a deformable interface intraocular lens. The article combines a multidisciplinary basic science approach from biomechanics, optical science, and ophthalmology to optimize an intraocular lens design suitable for preliminary animal trials.

Short exposure to telestereoscope affects the oculomotor system.

PubMed

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

2010-11-01

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

Coupled Solid Rocket Motor Ballistics and Trajectory Modeling for Higher Fidelity Launch Vehicle Design

NASA Technical Reports Server (NTRS)

Ables, Brett

2014-01-01

Multi-stage launch vehicles with solid rocket motors (SRMs) face design optimization challenges, especially when the mission scope changes frequently. Significant performance benefits can be realized if the solid rocket motors are optimized to the changing requirements. While SRMs represent a fixed performance at launch, rapid design iterations enable flexibility at design time, yielding significant performance gains. The streamlining and integration of SRM design and analysis can be achieved with improved analysis tools. While powerful and versatile, the Solid Performance Program (SPP) is not conducive to rapid design iteration. Performing a design iteration with SPP and a trajectory solver is a labor intensive process. To enable a better workflow, SPP, the Program to Optimize Simulated Trajectories (POST), and the interfaces between them have been improved and automated, and a graphical user interface (GUI) has been developed. The GUI enables real-time visual feedback of grain and nozzle design inputs, enforces parameter dependencies, removes redundancies, and simplifies manipulation of SPP and POST's numerous options. Automating the analysis also simplifies batch analyses and trade studies. Finally, the GUI provides post-processing, visualization, and comparison of results. Wrapping legacy high-fidelity analysis codes with modern software provides the improved interface necessary to enable rapid coupled SRM ballistics and vehicle trajectory analysis. Low cost trade studies demonstrate the sensitivities of flight performance metrics to propulsion characteristics. Incorporating high fidelity analysis from SPP into vehicle design reduces performance margins and improves reliability. By flying an SRM designed with the same assumptions as the rest of the vehicle, accurate comparisons can be made between competing architectures. In summary, this flexible workflow is a critical component to designing a versatile launch vehicle model that can accommodate a volatile mission scope.

Design Optimization of Innovative High-Level Waste Pipeline Unplugging Technologies - 13341

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

Pribanic, T.; Awwad, A.; Varona, J.

2013-07-01

Florida International University (FIU) is currently working on the development and optimization of two innovative pipeline unplugging methods: the asynchronous pulsing system (APS) and the peristaltic crawler system (PCS). Experiments were conducted on the APS to determine how air in the pipeline influences the system's performance as well as determine the effectiveness of air mitigation techniques in a pipeline. The results obtained during the experimental phase of the project, including data from pipeline pressure pulse tests along with air bubble compression tests are presented. Single-cycle pulse amplification caused by a fast-acting cylinder piston pump in 21.8, 30.5, and 43.6 mmore » pipelines were evaluated. Experiments were conducted on fully flooded pipelines as well as pipelines that contained various amounts of air to evaluate the system's performance when air is present in the pipeline. Also presented are details of the improvements implemented to the third generation crawler system (PCS). The improvements include the redesign of the rims of the unit to accommodate a camera system that provides visual feedback of the conditions inside the pipeline. Visual feedback allows the crawler to be used as a pipeline unplugging and inspection tool. Tests conducted previously demonstrated a significant reduction of the crawler speed with increasing length of tether. Current improvements include the positioning of a pneumatic valve manifold system that is located in close proximity to the crawler, rendering tether length independent of crawler speed. Additional improvements to increase the crawler's speed were also investigated and presented. Descriptions of the test beds, which were designed to emulate possible scenarios present on the Department of Energy (DOE) pipelines, are presented. Finally, conclusions and recommendations for the systems are provided. (authors)« less

Tonic accommodation predicts closed-loop accommodation responses.

PubMed

Liu, Chunming; Drew, Stefanie A; Borsting, Eric; Escobar, Amy; Stark, Lawrence; Chase, Christopher

2016-12-01

The purpose of this study is to examine the potential relationship between tonic accommodation (TA), near work induced TA-adaptation and the steady state closed-loop accommodation response (AR). Forty-two graduate students participated in the study. Various aspects of their accommodation system were objectively measured using an open-field infrared auto-refractor (Grand Seiko WAM-5500). Tonic accommodation was assessed in a completely dark environment. The association between TA and closed-loop AR was assessed using linear regression correlations and t-test comparisons. Initial mean baseline TA was 1.84diopter (D) (SD±1.29D) with a wide distribution range (-0.43D to 5.14D). For monocular visual tasks, baseline TA was significantly correlated with the closed-loop AR. The slope of the best fit line indicated that closed-loop AR varied by approximately 0.3D for every 1D change in TA. This ratio was consistent across a variety of viewing distances and different near work tasks, including both static targets and continuous reading. Binocular reading conditions weakened the correlation between baseline TA and AR, although results remained statistically significant. The 10min near reading task with a 3D demand did not reveal significant near work induced TA-adaptation for either monocular or binocular conditions. Consistently, the TA-adaptation did not show any correlation with AR during reading. This study found a strong association between open-loop TA and closed-loop AR across a variety of viewing distances and different near work tasks. Difference between the correlations under monocular and binocular reading condition suggests a potential role for vergence compensation during binocular closed-loop AR. Copyright © 2016 Elsevier Ltd. All rights reserved.

Developmental changes in the balance of disparity, blur and looming/proximity cues to drive ocular alignment and focus

PubMed Central

Horwood, Anna M; Riddell, Patricia M

2015-01-01

Accurate co-ordination of accommodation and convergence is necessary to view near objects and develop fine motor co-ordination. We used a remote haploscopic videorefraction paradigm to measure longitudinal changes in simultaneous ocular accommodation and vergence to targets at different depths, and to all combinations of blur, binocular disparity, and change-in-size (“proximity”) cues. Infants were followed longitudinally and compared to older children and young adults, with the prediction that sensitivity to different cues would change during development. Mean infant responses to the most naturalistic condition were similar to those of adults from 6-7 weeks (accommodation) and 8-9 weeks (vergence). Proximity cues influenced responses most in infants less than 14 weeks of age, but sensitivity declined thereafter. Between 12-28 weeks of age infants were equally responsive to all three cues, while in older children and adults manipulation of disparity resulted in the greatest changes in response. Despite rapid development of visual acuity (thus increasing availability of blur cues), responses to blur were stable throughout development. Our results suggest that during much of infancy, vergence and accommodation responses are not dependent on the development of specific depth cues, but make use of any cues available to drive appropriate changes in response. PMID:24344547

Finite element modelling of radial lentotomy cuts to improve the accommodation performance of the human lens.

PubMed

Burd, H J; Wilde, G S

2016-04-01

The use of a femtosecond laser to form planes of cavitation bubbles within the ocular lens has been proposed as a potential treatment for presbyopia. The intended purpose of these planes of cavitation bubbles (referred to in this paper as 'cutting planes') is to increase the compliance of the lens, with a consequential increase in the amplitude of accommodation. The current paper describes a computational modelling study, based on three-dimensional finite element analysis, to investigate the relationship between the geometric arrangement of the cutting planes and the resulting improvement in lens accommodation performance. The study is limited to radial cutting planes. The effectiveness of a variety of cutting plane geometries was investigated by means of modelling studies conducted on a 45-year human lens. The results obtained from the analyses depend on the particular modelling procedures that are employed. When the lens substance is modelled as an incompressible material, radial cutting planes are found to be ineffective. However, when a poroelastic model is employed for the lens substance, radial cuts are shown to cause an increase in the computed accommodation performance of the lens. In this case, radial cuts made in the peripheral regions of the lens have a relatively small influence on the accommodation performance of the lens; the lentotomy process is seen to be more effective when cuts are made near to the polar axis. When the lens substance is modelled as a poroelastic material, the computational results suggest that useful improvements in lens accommodation performance can be achieved, provided that the radial cuts are extended to the polar axis. Radial cuts are ineffective when the lens substance is modelled as an incompressible material. Significant challenges remain in developing a safe and effective surgical procedure based on this lentotomy technique.

TransFit: Finite element analysis data fitting software

NASA Technical Reports Server (NTRS)

Freeman, Mark

1993-01-01

The Advanced X-Ray Astrophysics Facility (AXAF) mission support team has made extensive use of geometric ray tracing to analyze the performance of AXAF developmental and flight optics. One important aspect of this performance modeling is the incorporation of finite element analysis (FEA) data into the surface deformations of the optical elements. TransFit is software designed for the fitting of FEA data of Wolter I optical surface distortions with a continuous surface description which can then be used by SAO's analytic ray tracing software, currently OSAC (Optical Surface Analysis Code). The improved capabilities of Transfit over previous methods include bicubic spline fitting of FEA data to accommodate higher spatial frequency distortions, fitted data visualization for assessing the quality of fit, the ability to accommodate input data from three FEA codes plus other standard formats, and options for alignment of the model coordinate system with the ray trace coordinate system. TransFit uses the AnswerGarden graphical user interface (GUI) to edit input parameters and then access routines written in PV-WAVE, C, and FORTRAN to allow the user to interactively create, evaluate, and modify the fit. The topics covered include an introduction to TransFit: requirements, designs philosophy, and implementation; design specifics: modules, parameters, fitting algorithms, and data displays; a procedural example; verification of performance; future work; and appendices on online help and ray trace results of the verification section.

[Functional amblyopia].

PubMed

Avram, Elena; Stănilă, Adriana

2013-01-01

Amblyopia is a disorder of the visual system that represents unilateral or bi-lateral reduction of visual acuity in which an organic cause cannot be detected. The illness represents a syndrome of visual deficits, not only a deterioration of visual acuity. This syndrome includes: presence of crowding phenomena, contrast sensitivity deterioration, deficits in accommodation, deterioration of spatial orientation and ocular motility dysfunction. Depending on its etiology, amblyopia is classified into four main types: strabismic amblyopia, anisometropic amblyopia, isoametropic amblyopia and stimulus deprivation amblyopia. To successfully treat the "lazy eye" it is essential to remove the amblyopic factor with techniques addressing each disturbing factor. Techniques used for treating amblyopia include: occlusion, optical penalty or pharmacological, therapy with Levodopa and computer vision therapy. Amblyopia treatment is lengthy and it is very important to counsel not only the child but the whole family and to establish a relationship of trust between doctor and patient in order to get high treatment compliance and high child motivation.

Clinical test responses to different orthoptic exercise regimes in typical young adults

PubMed Central

Horwood, Anna; Toor, Sonia

2014-01-01

Purpose The relative efficiency of different eye exercise regimes is unclear, and in particular the influences of practice, placebo and the amount of effort required are rarely considered. This study measured conventional clinical measures following different regimes in typical young adults. Methods A total of 156 asymptomatic young adults were directed to carry out eye exercises three times daily for 2 weeks. Exercises were directed at improving blur responses (accommodation), disparity responses (convergence), both in a naturalistic relationship, convergence in excess of accommodation, accommodation in excess of convergence, and a placebo regime. They were compared to two control groups, neither of which were given exercises, but the second of which were asked to make maximum effort during the second testing. Results Instruction set and participant effort were more effective than many exercises. Convergence exercises independent of accommodation were the most effective treatment, followed by accommodation exercises, and both regimes resulted in changes in both vergence and accommodation test responses. Exercises targeting convergence and accommodation working together were less effective than those where they were separated. Accommodation measures were prone to large instruction/effort effects and monocular accommodation facility was subject to large practice effects. Conclusions Separating convergence and accommodation exercises seemed more effective than exercising both systems concurrently and suggests that stimulation of accommodation and convergence may act in an additive fashion to aid responses. Instruction/effort effects are large and should be carefully controlled if claims for the efficacy of any exercise regime are to be made. PMID:24471739

Effect of Phenylephrine on the Accommodative System

PubMed Central

Del Águila-Carrasco, Antonio J.; Bernal-Molina, Paula; Ferrer-Blasco, Teresa; López-Gil, Norberto; Montés-Micó, Robert

2016-01-01

Accommodation is controlled by the action of the ciliary muscle and mediated primarily by parasympathetic input through postganglionic fibers that originate from neurons in the ciliary and pterygopalatine ganglia. During accommodation the pupil constricts to increase the depth of focus of the eye and improve retinal image quality. Researchers have traditionally faced the challenge of measuring the accommodative properties of the eye through a small pupil and thus have relied on pharmacological agents to dilate the pupil. Achieving pupil dilation (mydriasis) without affecting the accommodative ability of the eye (cycloplegia) could be useful in many clinical and research contexts. Phenylephrine hydrochloride (PHCl) is a sympathomimetic agent that is used clinically to dilate the pupil. Nevertheless, first investigations suggested some loss of functional accommodation in the human eye after PHCl instillation. Subsequent studies, based on different measurement procedures, obtained contradictory conclusions, causing therefore an unexpected controversy that has been spread almost to the present days. This manuscript reviews and summarizes the main research studies that have been performed to analyze the effect of PHCl on the accommodative system and provides clear conclusions that could help clinicians know the real effects of PHCl on the accommodative system of the human eye. PMID:28053778

Phenomenological model of visual acuity

NASA Astrophysics Data System (ADS)

Gómez-Pedrero, José A.; Alonso, José

2016-12-01

We propose in this work a model for describing visual acuity (V) as a function of defocus and pupil diameter. Although the model is mainly based on geometrical optics, it also incorporates nongeometrical effects phenomenologically. Compared to similar visual acuity models, the proposed one considers the effect of astigmatism and the variability of best corrected V among individuals; it also takes into account the accommodation and the "tolerance to defocus," the latter through a phenomenological parameter. We have fitted the model to the V data provided in the works of Holladay et al. and Peters, showing the ability of this model to accurately describe the variation of V against blur and pupil diameter. We have also performed a comparison between the proposed model and others previously published in the literature. The model is mainly intended for use in the design of ophthalmic compensations, but it can also be useful in other fields such as visual ergonomics, design of visual tests, and optical instrumentation.

Early screening of an infant's visual system

NASA Astrophysics Data System (ADS)

Costa, Manuel F. M.; Jorge, Jorge M.

1999-06-01

It is of utmost importance to the development of the child's visual system that she perceives clear focused retinal images. Furthermore if the refractive problems are not corrected in due time amblyopia may occur--myopia and hyperopia can only cause important problems in the future when they are significantly large, however for the astigmatism (rather frequent in infants) and anisometropia the problems tend to be more stringent. The early evaluation of the visual status of human infants is thus of critical importance. Photorefraction is a convenient technique for this kind of subjects. Essentially a light beam is delivered into the eyes. It is refracted by the ocular media, strikes the retina, focusing or not, reflects off and is collected by a camera. The photorefraction setup we established using new technological breakthroughs on the fields of imaging devices, digital image processing and fiber optics, allows a fast noninvasive evaluation of children visual status (refractive errors, accommodation, strabismus, ...). Results of the visual screening of a group of risk' child descents of blinds or amblyopes will be presented.

Stereoscopic 3D entertainment and its effect on viewing comfort: comparison of children and adults.

PubMed

Pölönen, Monika; Järvenpää, Toni; Bilcu, Beatrice

2013-01-01

Children's and adults' viewing comfort during stereoscopic three-dimensional film viewing and computer game playing was studied. Certain mild changes in visual function, heterophoria and near point of accommodation values, as well as eyestrain and visually induced motion sickness levels were found when single setups were compared. The viewing system had an influence on viewing comfort, in particular for eyestrain levels, but no clear difference between two- and three-dimensional systems was found. Additionally, certain mild changes in visual functions and visually induced motion sickness levels between adults and children were found. In general, all of the system-task combinations caused mild eyestrain and possible changes in visual functions, but these changes in magnitude were small. According to subjective opinions that further support these measurements, using a stereoscopic three-dimensional system for up to 2 h was acceptable for most of the users regardless of their age. Copyright © 2012 Elsevier Ltd and The Ergonomics Society. All rights reserved.

A reference web architecture and patterns for real-time visual analytics on large streaming data

NASA Astrophysics Data System (ADS)

Kandogan, Eser; Soroker, Danny; Rohall, Steven; Bak, Peter; van Ham, Frank; Lu, Jie; Ship, Harold-Jeffrey; Wang, Chun-Fu; Lai, Jennifer

2013-12-01

Monitoring and analysis of streaming data, such as social media, sensors, and news feeds, has become increasingly important for business and government. The volume and velocity of incoming data are key challenges. To effectively support monitoring and analysis, statistical and visual analytics techniques need to be seamlessly integrated; analytic techniques for a variety of data types (e.g., text, numerical) and scope (e.g., incremental, rolling-window, global) must be properly accommodated; interaction, collaboration, and coordination among several visualizations must be supported in an efficient manner; and the system should support the use of different analytics techniques in a pluggable manner. Especially in web-based environments, these requirements pose restrictions on the basic visual analytics architecture for streaming data. In this paper we report on our experience of building a reference web architecture for real-time visual analytics of streaming data, identify and discuss architectural patterns that address these challenges, and report on applying the reference architecture for real-time Twitter monitoring and analysis.

Clinical predictors of the optimal spectacle correction for comfort performing desktop tasks.

PubMed

Leffler, Christopher T; Davenport, Byrd; Rentz, Jodi; Miller, Amy; Benson, William

2008-11-01

The best strategy for spectacle correction of presbyopia for near tasks has not been determined. Thirty volunteers over the age of 40 years were tested for subjective accommodative amplitude, pupillary size, fusional vergence, interpupillary distance, arm length, preferred working distance, near and far visual acuity and preferred reading correction in the phoropter and trial frames. Subjects performed near tasks (reading, writing and counting change) using various spectacle correction strengths. Predictors of the correction maximising near task comfort were determined by multivariable linear regression. The mean age was 54.9 years (range 43 to 71) and 40 per cent had diabetes. Significant predictors of the most comfortable addition in univariate analyses were age (p<0.001), interpupillary distance (p=0.02), fusional vergence amplitude (p=0.02), distance visual acuity in the worse eye (p=0.01), vision at 40 cm in the worse eye with distance correction (p=0.01), duration of diabetes (p=0.01), and the preferred correction to read at 40 cm with the phoropter (p=0.002) or trial frames (p<0.001). Target distance selected wearing trial frames (in dioptres), arm length, and accommodative amplitude were not significant predictors (p>0.15). The preferred addition wearing trial frames holding a reading target at a distance selected by the patient was the only independent predictor. Excluding this variable, distance visual acuity was predictive independent of age or near vision wearing distance correction. The distance selected for task performance was predicted by vision wearing distance correction at near and at distance. Multivariable linear regression can be used to generate tables based on distance visual acuity and age or near vision wearing distance correction to determine tentative near spectacle addition. Final spectacle correction for desktop tasks can be estimated by subjective refraction with trial frames.

Direct manipulation of virtual objects

NASA Astrophysics Data System (ADS)

Nguyen, Long K.

Interacting with a Virtual Environment (VE) generally requires the user to correctly perceive the relative position and orientation of virtual objects. For applications requiring interaction in personal space, the user may also need to accurately judge the position of the virtual object relative to that of a real object, for example, a virtual button and the user's real hand. This is difficult since VEs generally only provide a subset of the cues experienced in the real world. Complicating matters further, VEs presented by currently available visual displays may be inaccurate or distorted due to technological limitations. Fundamental physiological and psychological aspects of vision as they pertain to the task of object manipulation were thoroughly reviewed. Other sensory modalities -- proprioception, haptics, and audition -- and their cross-interactions with each other and with vision are briefly discussed. Visual display technologies, the primary component of any VE, were canvassed and compared. Current applications and research were gathered and categorized by different VE types and object interaction techniques. While object interaction research abounds in the literature, pockets of research gaps remain. Direct, dexterous, manual interaction with virtual objects in Mixed Reality (MR), where the real, seen hand accurately and effectively interacts with virtual objects, has not yet been fully quantified. An experimental test bed was designed to provide the highest accuracy attainable for salient visual cues in personal space. Optical alignment and user calibration were carefully performed. The test bed accommodated the full continuum of VE types and sensory modalities for comprehensive comparison studies. Experimental designs included two sets, each measuring depth perception and object interaction. The first set addressed the extreme end points of the Reality-Virtuality (R-V) continuum -- Immersive Virtual Environment (IVE) and Reality Environment (RE). This validated, linked, and extended several previous research findings, using one common test bed and participant pool. The results provided a proven method and solid reference points for further research. The second set of experiments leveraged the first to explore the full R-V spectrum and included additional, relevant sensory modalities. It consisted of two full-factorial experiments providing for rich data and key insights into the effect of each type of environment and each modality on accuracy and timeliness of virtual object interaction. The empirical results clearly showed that mean depth perception error in personal space was less than four millimeters whether the stimuli presented were real, virtual, or mixed. Likewise, mean error for the simple task of pushing a button was less than four millimeters whether the button was real or virtual. Mean task completion time was less than one second. Key to the high accuracy and quick task performance time observed was the correct presentation of the visual cues, including occlusion, stereoscopy, accommodation, and convergence. With performance results already near optimal level with accurate visual cues presented, adding proprioception, audio, and haptic cues did not significantly improve performance. Recommendations for future research include enhancement of the visual display and further experiments with more complex tasks and additional control variables.

New trends in intraocular lens imaging

NASA Astrophysics Data System (ADS)

Millán, María S.; Alba-Bueno, Francisco; Vega, Fidel

2011-08-01

As a result of modern technological advances, cataract surgery can be seen as not only a rehabilitative operation, but a customized procedure to compensate for important sources of image degradation in the visual system of a patient, such as defocus and some aberrations. With the development of new materials, instruments and surgical techniques in ophthalmology, great progress has been achieved in the imaging capability of a pseudophakic eye implanted with an intraocular lens (IOL). From the very beginning, optical design has played an essential role in this progress. New IOL designs need, on the one hand, theoretical eye models able to predict optical imaging performance and on the other hand, testing methods, verification through in vitro and in vivo measurements, and clinical validation. The implant of an IOL requires a precise biometry of the eye, a prior calculation from physiological data, and an accurate position inside the eye. Otherwise, the effects of IOL calculation errors or misplacements degrade the image very quickly. The incorporation of wavefront aberrometry into clinical ophthalmology practice has motivated new designs of IOLs to compensate for high order aberrations in some extent. Thus, for instance, IOLs with an aspheric design have the potential to improve optical performance and contrast sensitivity by reducing the positive spherical aberration of human cornea. Monofocal IOLs cause a complete loss of accommodation that requires further correction for either distance or near vision. Multifocal IOLs address this limitation using the principle of simultaneous vision. Some multifocal IOLs include a diffractive zone that covers the aperture in part or totally. Reduced image contrast and undesired visual phenomena, such as halos and glare, have been associated to the performance of multifocal IOLs. Based on a different principle, accommodating IOLs rely on the effort of the ciliary body to increase the effective power of the optical system of the eye in near vision. Finally, we present a theoretical approach that considers the modification of less conventional ocular parameters to compensate for possible refractive errors after the IOL implant.

Change in human lens dimensions, lens refractive index distribution and ciliary body ring diameter with accommodation.

PubMed

Khan, Adnan; Pope, James M; Verkicharla, Pavan K; Suheimat, Marwan; Atchison, David A

2018-03-01

We investigated changes in ciliary body ring diameter, lens dimensions and lens refractive index distributions with accommodation in young adults. A 3T clinical magnetic resonance imaging scanner imaged right eyes of 38 18-29 year old participants using a multiple spin echo sequence to determine accommodation-induced changes along lens axial and equatorial directions. Accommodation stimuli were approximately 1 D and 5 D. With accommodation, ciliary body ring diameter, and equatorial lens diameter decreased (-0.43 ± 0.31 mm and -0.30 ± 0.23 mm, respectively), and axial lens thickness increased ( + 0.34 ± 0.16 mm). Lens shape changes cause redistribution of the lens internal structure, leading to change in refractive index distribution profiles. With accommodation, in the axial direction refractive index profiles became flatter in the center and steeper near the periphery of the lens, while in the equatorial direction they became steeper in the center and flatter in the periphery. The results suggest that the anatomical accuracy of lens optical models can be improved by accounting for changes in the refractive index profile during accommodation.

Modified Ball and Socket Coupling

DOEpatents

Conley, Jr, W. R.; Pitman, R. W.

1961-05-23

A ball and socket coupling arrangement is given in which the male and female members may be engaged or disengaged without visual aid. The female member has an internal spherical seat through which slots are provided to accommodate appropriately arranged and shaped ribs in the male ball member. After engagement of the members, one or both are rotated to lock them together to prevent accidental disengagement.

MODIFIED BALL AND SOCKET COUPLING

DOEpatents

Kalen, D.D.

1961-05-23

A ball and socket coupling arrangement is described in which the male and female members may be engaged or disengaged without visual aid. The female member has an internal spherical seat through which slots are provided to accommodate appropriately arranged and shaped ribs in the ball member. After engagement of the members, one or both are rotated to lock them together to prevent accidental disengagement. (AEC)

The Effects of Pilot Age, Lighting, and Head-Down Time on Visual Accommodation

DTIC Science & Technology

1979-02-06

technique for determining the extent of ametropia (nearsighted- ness, farsightedness, astigmatism) and as an aid in the fitting (8.1)of eyeglasses. Knoll... Ametropia with a Gas LASER", "Amerinan 1onu~nl nf Onpw’rp"r-_ Vol. 43, No. 7: 415-418, 1966. 4. Oliver, G. M. "Sparkling Spots and Random Diffractions

The zone of comfort: Predicting visual discomfort with stereo displays

PubMed Central

Shibata, Takashi; Kim, Joohwan; Hoffman, David M.; Banks, Martin S.

2012-01-01

Recent increased usage of stereo displays has been accompanied by public concern about potential adverse effects associated with prolonged viewing of stereo imagery. There are numerous potential sources of adverse effects, but we focused on how vergence–accommodation conflicts in stereo displays affect visual discomfort and fatigue. In one experiment, we examined the effect of viewing distance on discomfort and fatigue. We found that conflicts of a given dioptric value were slightly less comfortable at far than at near distance. In a second experiment, we examined the effect of the sign of the vergence–accommodation conflict on discomfort and fatigue. We found that negative conflicts (stereo content behind the screen) are less comfortable at far distances and that positive conflicts (content in front of screen) are less comfortable at near distances. In a third experiment, we measured phoria and the zone of clear single binocular vision, which are clinical measurements commonly associated with correcting refractive error. Those measurements predicted susceptibility to discomfort in the first two experiments. We discuss the relevance of these findings for a wide variety of situations including the viewing of mobile devices, desktop displays, television, and cinema. PMID:21778252

Passive method of eliminating accommodation/convergence disparity in stereoscopic head-mounted displays

NASA Astrophysics Data System (ADS)

Eichenlaub, Jesse B.

2005-03-01

The difference in accommodation and convergence distance experienced when viewing stereoscopic displays has long been recognized as a source of visual discomfort. It is especially problematic in head mounted virtual reality and enhanced reality displays, where images must often be displayed across a large depth range or superimposed on real objects. DTI has demonstrated a novel method of creating stereoscopic images in which the focus and fixation distances are closely matched for all parts of the scene from close distances to infinity. The method is passive in the sense that it does not rely on eye tracking, moving parts, variable focus optics, vibrating optics, or feedback loops. The method uses a rapidly changing illumination pattern in combination with a high speed microdisplay to create cones of light that converge at different distances to form the voxels of a high resolution space filling image. A bench model display was built and a series of visual tests were performed in order to demonstrate the concept and investigate both its capabilities and limitations. Results proved conclusively that real optical images were being formed and that observers had to change their focus to read text or see objects at different distances

The zone of comfort: Predicting visual discomfort with stereo displays.

PubMed

Shibata, Takashi; Kim, Joohwan; Hoffman, David M; Banks, Martin S

2011-07-21

Recent increased usage of stereo displays has been accompanied by public concern about potential adverse effects associated with prolonged viewing of stereo imagery. There are numerous potential sources of adverse effects, but we focused on how vergence-accommodation conflicts in stereo displays affect visual discomfort and fatigue. In one experiment, we examined the effect of viewing distance on discomfort and fatigue. We found that conflicts of a given dioptric value were slightly less comfortable at far than at near distance. In a second experiment, we examined the effect of the sign of the vergence-accommodation conflict on discomfort and fatigue. We found that negative conflicts (stereo content behind the screen) are less comfortable at far distances and that positive conflicts (content in front of screen) are less comfortable at near distances. In a third experiment, we measured phoria and the zone of clear single binocular vision, which are clinical measurements commonly associated with correcting refractive error. Those measurements predicted susceptibility to discomfort in the first two experiments. We discuss the relevance of these findings for a wide variety of situations including the viewing of mobile devices, desktop displays, television, and cinema.

Increasing Student Involvement in IEPs

ERIC Educational Resources Information Center

Nolan-Spohn, Hannah

2016-01-01

In this article, the author proposes that students who led their Individual Education Program (IEP) meetings were better informed about their own disabilities, rights, and accommodations, and that the act of leading the meeting resulted in improved self-advocacy and self-confidence. Also, in understanding their list of accommodations and…

The role of interactions between accommodation and vergence in human visual development

NASA Astrophysics Data System (ADS)

Teel, Danielle F. W.

Even in early infancy accommodation and vergence interact through neural coupling such that accommodation drives vergence (AC/A ratio) and vergence drives accommodation (CA/C ratio), to assist coordination and development of clear and single binocular vision. Infants have narrow inter-pupillary distances (IPD) requiring less vergence in angular units (degrees or prism diopters), and are typically hyperopic, requiring larger accommodative responses (diopters) than adults. The relative demands also change with emmetropization (decreasing hyperopia) and head growth (increasing IPD) over time. Therefore, adult-like couplings may not be optimal during development and the couplings may play a role in abnormality such as esotropia. A range of cues can drive accommodation and vergence. In addition to blur and disparity, proximity in the form of looming, size and perceived distance has been shown to influence the interactions between accommodation and vergence in adults. The role of this cue in measures of coupling is also poorly understood and may impact key clinical AC/A estimates in young children. Utilizing principles of eccentric photorefraction and Purkinje image eye tracking, this research examines the AC/A and CA/C ratios in infants, preschoolers and adults as a function of age, refractive error and interpupillary distance, plus the role proximity, specifically looming and size cues, plays in estimating the AC/A ratio in three year olds and adults. The AC/A (PD/D) was significantly higher in adults than three-year-olds or infants but similar across age groups in MA/D units. The CA/C was higher in infants than adults or three-year-olds (D/MA and D/PD). Although, not fully reciprocally related, a significant negative relationship was found between the response AC/A and CA/C. Similarly, higher AC/As (PD/D) and lower CA/Cs (D/PD) were associated with larger IPDs and less hyperopia. Although, not statistically significant the absence of proximity resulted in a trend toward a lower AC/A than in it's presence for children. These results provide insight into methods of measuring the AC/A ratio in children and determining whether the couplings are optimized to prevent over-convergence or under-accommodation during development and growth.

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

Van de Velde, Joris, E-mail: joris.vandevelde@ugent.be; Department of Radiotherapy, Ghent University, Ghent; Audenaert, Emmanuel

Purpose: To develop contouring guidelines for the brachial plexus (BP) using anatomically validated cadaver datasets. Magnetic resonance imaging (MRI) and computed tomography (CT) were used to obtain detailed visualizations of the BP region, with the goal of achieving maximal inclusion of the actual BP in a small contoured volume while also accommodating for anatomic variations. Methods and Materials: CT and MRI were obtained for 8 cadavers positioned for intensity modulated radiation therapy. 3-dimensional reconstructions of soft tissue (from MRI) and bone (from CT) were combined to create 8 separate enhanced CT project files. Dissection of the corresponding cadavers anatomically validatedmore » the reconstructions created. Seven enhanced CT project files were then automatically fitted, separately in different regions, to obtain a single dataset of superimposed BP regions that incorporated anatomic variations. From this dataset, improved BP contouring guidelines were developed. These guidelines were then applied to the 7 original CT project files and also to 1 additional file, left out from the superimposing procedure. The percentage of BP inclusion was compared with the published guidelines. Results: The anatomic validation procedure showed a high level of conformity for the BP regions examined between the 3-dimensional reconstructions generated and the dissected counterparts. Accurate and detailed BP contouring guidelines were developed, which provided corresponding guidance for each level in a clinical dataset. An average margin of 4.7 mm around the anatomically validated BP contour is sufficient to accommodate for anatomic variations. Using the new guidelines, 100% inclusion of the BP was achieved, compared with a mean inclusion of 37.75% when published guidelines were applied. Conclusion: Improved guidelines for BP delineation were developed using combined MRI and CT imaging with validation by anatomic dissection.« less

Aging well with smart technology.

PubMed

Cheek, Penny; Nikpour, Linda; Nowlin, Heather D

2005-01-01

As baby-boomers age, the need for long-term nursing care services increases. In the future, there will simply not be enough long-term care facilities to accommodate all of these patients. In addition, many people prefer to grow old at home, a concept known as aging-in-place. Smart home technology facilities aging-in-place by assisting patients with emergency assistance, fall prevention/detection, reminder systems, medication administration and assistance for those with hearing, visual or cognitive impairments. Benefits include making aging-in-place a reality, continuous monitoring, and improved psychosocial effects. Concerns of this technology include cost, availability of technology, retrofitting complications, and potential inappropriate use of the technology. Overall, the concept of smart homes is gaining in popularity and will expand the role of the nurse in the future. It is important for all nurses to understand how their practices will be transformed as smart homes become a reality for the aging population.

Fiber Optic Rate Sensors For High-G Environment Applications

NASA Astrophysics Data System (ADS)

Moore, Emery L.; Hertzberg, Alex

1990-02-01

Advances in modern warfare require the development of artillery munitions that travel beyond the visual horizon. It is not unusual, particularly in undulating terrain, for the direct line of sight from the forward edge of the battle area (FEBA) to the attacking forces to be limited to 2,000 meters. In addition to terrain, influences of clouds, fog, rain and smoke combine to limit the direct line of sight. Mobile targets also decrease probability of kill. What is called for and what has been developed are "smart munitions" that allow the artilleryman to "fire and forget." The technique which accommodates this fire and forget philosophy utilizes a projectile having a radiation detector (or seeker) to sense the target and inertial rate sensors supported by a computer or processor. However, even though we have smart shells today room for improvement exists in weight, power, shelf life, environmental ruggedness and cost.

Optimizing MR imaging-guided navigation for focused ultrasound interventions in the brain

NASA Astrophysics Data System (ADS)

Werner, B.; Martin, E.; Bauer, R.; O'Gorman, R.

2017-03-01

MR imaging during transcranial MR imaging-guided Focused Ultrasound surgery (tcMRIgFUS) is challenging due to the complex ultrasound transducer setup and the water bolus used for acoustic coupling. Achievable image quality in the tcMRIgFUS setup using the standard body coil is significantly inferior to current neuroradiologic standards. As a consequence, MR image guidance for precise navigation in functional neurosurgical interventions using tcMRIgFUS is basically limited to the acquisition of MR coordinates of salient landmarks such as the anterior and posterior commissure for aligning a stereotactic atlas. Here, we show how improved MR image quality provided by a custom built MR coil and optimized MR imaging sequences can support imaging-guided navigation for functional tcMRIgFUS neurosurgery by visualizing anatomical landmarks that can be integrated into the navigation process to accommodate for patient specific anatomy.

Supervisors' perceptions of organizational policies are associated with their likelihood to accommodate back-injured workers.

PubMed

McGuire, Connor; Kristman, Vicki L; Shaw, William S; Loisel, Patrick; Reguly, Paula; Williams-Whitt, Kelly; Soklaridis, Sophie

2017-02-01

Background Low back pain (LBP) is a major concern among North American workplaces and little is known regarding a supervisor's decision to support job accommodation for workers with LBP. The extent to which supervisors are included in a company's effort to institute disability management policies and practices and workplace safety climate are two factors that may influence a supervisor's decision to accommodate workers with LBP. Objective Determine the association between supervisors' perceptions of disability management policies, corporate safety culture and their likelihood of supporting job accommodations for workers with LBP. Methods We conducted a cross-sectional study of supervisors (N=796) recruited from a non-random, convenience sample of 19 Canadian and US employers. The outcome was supervisors' likeliness to support job accommodation and the exposure was global work safety culture and disability management policies and practices. A multivariable generalized linear modelling strategy was used and final models for each exposure were obtained after assessing potential effect modifiers and confounders. Results In the study, 796 eligible supervisors from 19 employers participated. Disability management policies and practices were positively associated with supervisors' likeliness to accommodate (β=0.19; 95% CI: 0.13; 0.24) while no significant association was found between corporate safety culture (β= -0.084; 95% CI: -0.19; 0.027) and supervisors' likeliness to accommodate. Conclusions Employers should ensure that proactive disability management policies and practices are clearly communicated to supervisors in order to improve job modification and return to work efforts. Implications for Rehabilitation Low back pain (LBP) is a major workplace concern and little is known regarding what factors are associated with a supervisor's likelihood to support job accommodation for workers with LBP. The objective of this article was to determine the association between supervisors' perceptions of disability management policies and practices, corporate safety culture and their likelihood of support job accommodations for workers with LBP. Results suggest that disability management policies and practices are positively associated with supervisors' likelihood to accommodate while corporate safety culture is not. These results are important for employers as it suggests that employers should ensure that their disability management policies and practices are clearly communicated to supervisors in order to improve job accommodation and return to work efforts.

A Rare Presentation of Cyclitis Induced Myopia.

PubMed

Ijaz, Umar; Habib, Asad; Rathore, Hassan Sajjad

2018-03-01

Unilateral cyclitis leading to myopia is a rare and clinical relevant entity. In clinical settings, pseudomyopia is generally encountered in the form of accommodative spasm, which is always bilateral. Cyclitis due to inflammation, on the other hand, can cause pseudomyopia unilaterally and it is a very rare presentation. A young male with acute anterior uveitis, presented with acute episode of unilateral myopia. When patient was examined on first visit, there were no cells in anterior chamber; so he was started on cycloplegic eye drops, but his condition didn't improve. Examination on subsequent visit revealed cellular reaction in anterior chamber and narrowing of anterior chamber angles on anterior segment optical coherence tomography (OCT). Treatment for uveitis was started and patient's visual acuity and refractive error improved. Pseudomyopia is a known complication of several drugs and certain medical conditions. The possible mechanism is supraciliary exudation causing relaxation of zonular fibers and increased convexity of the crystalline lens. Myopia in the setting of a mild cellular reaction can easily be missed and has not been reported yet to the best of authors' literature search.

Current Management of Presbyopia

PubMed Central

Papadopoulos, Pandelis A.; Papadopoulos, Alexandros P.

2014-01-01

Presbyopia is a physiologic inevitability that causes gradual loss of accommodation during the fifth decade of life. The correction of presbyopia and the restoration of accommodation are considered the final frontier of refractive surgery. Different approaches on the cornea, the crystalline lens and the sclera are being pursued to achieve surgical correction of this disability. There are however, a number of limitations and considerations that have prevented widespread acceptance of surgical correction for presbyopia. The quality of vision, optical and visual distortions, regression of effect, complications such as corneal ectasia and haze, anisometropia after monovision correction, impaired distance vision and the invasive nature of the currently techniques have limited the utilization of presbyopia surgery. The purpose of this paper is to provide an update of current procedures available for presbyopia correction and their limitations. PMID:24669140

The Mark 3 Haploscope

NASA Technical Reports Server (NTRS)

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

1975-01-01

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

Usage of CISS and Conlon surveys in eye accommodation studies

NASA Astrophysics Data System (ADS)

Panke, Karola; Svede, Aiga; Jaschinski, Wolfgang; Krumina, Gunta

2017-08-01

To date, there is no assessment of more than one survey used for a clinical research study that address subjects with and without symptoms related to accommodative or binocular vision disorders. Thus, the purpose of this study was to investigate two different surveys - CISS and Conlon for the same subject group and analyse also critical visual function parameters. Monocular and binocular accommodative response for 20 subjects was measured for dominant eye with openfield infrared autorefractometer (Shin-Nippon SRW-5000) at three distances (24 cm, 30 cm and 40 cm). Subjects were divided into symptomatic and asymptomatic group using cut off score 21 for CISS and 20 for Conlon survey. We found positive exponential growth relationship between CISS and Conlon scores (R² = 0.7), but separation between symptomatic and asymptomatic group differed significantly depending on which survey was used. We found positive correlation between Conlon score and exophoria at 30 cm (r=0.41, p=0.01) and 24 cm (r=0.27, p=0.03). Relationship between subjective symptoms and following clinical parameters - accommodation lag (r < 0.2, p < 0.05), positive relative accommodation (r < 0.15, p < 0.05) and convergence near point (r = 0.26, p < 0.05) were not significant. Our results confirmed that using different subjective symptom surveys can provide different results within the same subject group, therefore we recommend to use surveys as a part of case history and tool to measure patient satisfaction and results of treatment effectiveness instead of using them for clinical trials as a criteria to divide symptomatic and asymptomatic group.

Effect of the accommodation-vergence conflict on vergence eye movements.

PubMed

Vienne, Cyril; Sorin, Laurent; Blondé, Laurent; Huynh-Thu, Quan; Mamassian, Pascal

2014-07-01

With the broader use of stereoscopic displays, a flurry of research activity about the accommodation-vergence conflict has emerged to highlight the implications for the human visual system. In stereoscopic displays, the introduction of binocular disparities requires the eyes to make vergence movements. In this study, we examined vergence dynamics with regard to the conflict between the stimulus-to-accommodation and the stimulus-to-vergence. In a first experiment, we evaluated the immediate effect of the conflict on vergence responses by presenting stimuli with conflicting disparity and focus on a stereoscopic display (i.e. increasing the stereoscopic demand) or by presenting stimuli with matched disparity and focus using an arrangement of displays and a beam splitter (i.e. focus and disparity specifying the same locations). We found that the dynamics of vergence responses were slower overall in the first case due to the conflict between accommodation and vergence. In a second experiment, we examined the effect of a prolonged exposure to the accommodation-vergence conflict on vergence responses, in which participants judged whether an oscillating depth pattern was in front or behind the fixation plane. An increase in peak velocity was observed, thereby suggesting that the vergence system has adapted to the stereoscopic demand. A slight increase in vergence latency was also observed, thus indicating a small decline of vergence performance. These findings offer a better understanding and document how the vergence system behaves in stereoscopic displays. We describe what stimuli in stereo-movies might produce these oculomotor effects, and discuss potential applications perspectives. Copyright © 2014 Elsevier B.V. All rights reserved.

Clinical test responses to different orthoptic exercise regimes in typical young adults.

PubMed

Horwood, Anna; Toor, Sonia

2014-03-01

The relative efficiency of different eye exercise regimes is unclear, and in particular the influences of practice, placebo and the amount of effort required are rarely considered. This study measured conventional clinical measures following different regimes in typical young adults. A total of 156 asymptomatic young adults were directed to carry out eye exercises three times daily for 2 weeks. Exercises were directed at improving blur responses (accommodation), disparity responses (convergence), both in a naturalistic relationship, convergence in excess of accommodation, accommodation in excess of convergence, and a placebo regime. They were compared to two control groups, neither of which were given exercises, but the second of which were asked to make maximum effort during the second testing. Instruction set and participant effort were more effective than many exercises. Convergence exercises independent of accommodation were the most effective treatment, followed by accommodation exercises, and both regimes resulted in changes in both vergence and accommodation test responses. Exercises targeting convergence and accommodation working together were less effective than those where they were separated. Accommodation measures were prone to large instruction/effort effects and monocular accommodation facility was subject to large practice effects. Separating convergence and accommodation exercises seemed more effective than exercising both systems concurrently and suggests that stimulation of accommodation and convergence may act in an additive fashion to aid responses. Instruction/effort effects are large and should be carefully controlled if claims for the efficacy of any exercise regime are to be made. © 2014 The Authors Ophthalmic & Physiological Optics published by John Wiley & Sons Ltd on behalf of The College of Optometrists.

Supervisor and organizational factors associated with supervisor support of job accommodations for low back injured workers

PubMed Central

Kristman, Vicki L; Shaw, William S.; Reguly, Paula; Williams-Whitt, Kelly; Soklaridis, Sophie; Loisel, Patrick

2016-01-01

PURPOSE Temporary job accommodations contribute to the prevention of chronic work disability due to low back pain (LBP) through the facilitation of early return to work; yet, workplace dimensions of job accommodation are poorly understood. The objective of this study was to determine supervisor and organizational factors associated with supervisors’ support for temporary job accommodations for LBP injured workers. METHODS Supervisors were recruited from 19 workplaces in the USA and Canada and completed an online survey regarding job accommodation practices and potential associated factors with respect to a case vignette of a worker with LBP. Multivariable linear regression was used to identify the most parsimonious set of factors associated with supervisors’ support for accommodations. RESULTS A total of 804 supervisors participated with 796 eligible for inclusion in the analysis. The final set of factors explained 21% of the variance in supervisors’ support for temporary job accommodations. Considerate leadership style (β = .261; 95 % CI: .212, .310), workplace disability management policies and practices (β = .243; 95 % CI: .188, .298), and supervisor autonomy for designing and providing workplace accommodations (β = .156; 95 % CI: .071, .241) had the largest effect on supervisor support for accommodations. CONCLUSION Factors predicting supervisors’ likelihood to accommodate LBP injured workers include use of considerate leadership style, workplace disability management policies and practices, and supervisor autonomy. Workplace interventions targeting these factors should be developed and evaluated for their ability to improve work disability prevention outcomes. PMID:27032398

[Comparative evaluation of the effectiveness of various treatment modalities for accommodation disorders and acquired progressive myopia].

PubMed

Tarutta, E P; Tarasova, N A

2015-01-01

To evaluate the effectiveness of non-surgical treatment of accommodation disorders and progressive myopia in children. A total of 190 patients (380 eyes) with myopia aged from 6 to 18 years (10.79±0.18 years on average) were enrolled and divided into 9 groups depending on the treatment prescribed. Comparative evaluation of different hardware-based treatment modalities for progressive myopia allowed to work out their optimal combination: "Visotronic", "MACDEL 09", and magnetophoresis of Taufon 4%. Such courses, provided twice a year, were associated with optimization of accommodative response and 1.9-2.8 times reduction of the rate of myopia progression. On the contrary, pleoptic therapy showed a negative effect on accommodative tonus and the rate of progression of acquired myopia. Comparative evaluation of different hardware-based treatment modalities for progressive myopia and accommodation disorders allowed to work out their optimal combination: "Visotronic", "MACDEL 09" and magnetophoresis of Taufon 4%. This treatment, provided twice a year, allows to increase accommodative reserves and volume, improve objective accommodative response, and reduce accommodative hypertonus as well as the rate of myopia progression (1.9-2.8 times over a 1.5-year period). Under pleoptic therapy (specialized software, near field speckles, color pulse therapy, Ambliokor device), both accommodative tonus and the rate of myopia progression increased (1.3-1.5 and 1.6 times correspondingly).

Subjective and objective evaluation of visual fatigue on viewing 3D display continuously

NASA Astrophysics Data System (ADS)

Wang, Danli; Xie, Yaohua; Yang, Xinpan; Lu, Yang; Guo, Anxiang

2015-03-01

In recent years, three-dimensional (3D) displays become more and more popular in many fields. Although they can provide better viewing experience, they cause extra problems, e.g., visual fatigue. Subjective or objective methods are usually used in discrete viewing processes to evaluate visual fatigue. However, little research combines subjective indicators and objective ones in an entirely continuous viewing process. In this paper, we propose a method to evaluate real-time visual fatigue both subjectively and objectively. Subjects watch stereo contents on a polarized 3D display continuously. Visual Reaction Time (VRT), Critical Flicker Frequency (CFF), Punctum Maximum Accommodation (PMA) and subjective scores of visual fatigue are collected before and after viewing. During the viewing process, the subjects rate the visual fatigue whenever it changes, without breaking the viewing process. At the same time, the blink frequency (BF) and percentage of eye closure (PERCLOS) of each subject is recorded for comparison to a previous research. The results show that the subjective visual fatigue and PERCLOS increase with time and they are greater in a continuous process than a discrete one. The BF increased with time during the continuous viewing process. Besides, the visual fatigue also induced significant changes of VRT, CFF and PMA.

Vision in semi-aquatic snakes: Intraocular morphology, accommodation, and eye: Body allometry

NASA Astrophysics Data System (ADS)

Plylar, Helen Bond

Vision in vertebrates generally relies on the refractive power of the cornea and crystalline lens to facilitate vision. Light from the environment enters the eye and is refracted by the cornea and lens onto the retina for production of an image. When an animal with a system designed for air submerges underwater, the refractive power of the cornea is lost. Semi-aquatic animals (e.g., water snakes, turtles, aquatic mammals) must overcome this loss of corneal refractive power through visual accommodation. Accommodation relies on change of the position or shape of the lens to change the focal length of the optical system. Intraocular muscles and fibers facilitate lenticular displacement and deformation. Snakes, in general, are largely unstudied in terms of visual acuity and intraocular morphology. I used light microscopy and scanning electron microscopy to examine differences in eye anatomy between five sympatric colubrid snake species (Nerodia cyclopion, N. fasciata, N. rhombifer, Pantherophis obsoletus, and Thamnophis proximus) from Southeast Louisiana. I discovered previously undescribed structures associated with the lens in semi-aquatic species. Photorefractive methods were used to assess refractive error. While all species overcame the expected hyperopia imposed by submergence, there was interspecific variation in refractive error. To assess scaling of eye size with body size, I measure of eye size, head size, and body size in Nerodia cyclopion and N. fasciata from the SLU Vertebrate Museum. In both species, body size increases at a significantly faster rate than head size and eye size (negative allometry). Small snakes have large eyes relative to body size, and large snakes have relatively small eyes. There were interspecific differences in scaling of eye size with body size, where N. fasciata had larger eye diameter, but N. cyclopion had longer eyes (axial length).

The capacity of the US food system to accommodate improved diet quality: Projections to 2030

USDA-ARS?s Scientific Manuscript database

Objective: To estimate the capacity of the US agricultural system to produce enough food, in the right amounts, to accommodate a population shift toward healthier diet patterns. This analysis has immediate and long-term implications for the nutritional quality of the food supply, as well as for envi...

The Contribution of University Accommodation to International Student Security

ERIC Educational Resources Information Center

Paltridge, Toby; Mayson, Susan; Schapper, Jan

2010-01-01

In this paper we argue that living in university accommodation is a possible means of improving the security of international students. Our argument is supported by a qualitative case study of a single Hall of Residence on Monash University's Clayton campus. Data were collected primarily from interviews with three groups of participants--six…

Change in human lens dimensions, lens refractive index distribution and ciliary body ring diameter with accommodation

PubMed Central

Khan, Adnan; Pope, James M.; Verkicharla, Pavan K.; Suheimat, Marwan; Atchison, David A.

2018-01-01

We investigated changes in ciliary body ring diameter, lens dimensions and lens refractive index distributions with accommodation in young adults. A 3T clinical magnetic resonance imaging scanner imaged right eyes of 38 18-29 year old participants using a multiple spin echo sequence to determine accommodation-induced changes along lens axial and equatorial directions. Accommodation stimuli were approximately 1 D and 5 D. With accommodation, ciliary body ring diameter, and equatorial lens diameter decreased (–0.43 ± 0.31 mm and –0.30 ± 0.23 mm, respectively), and axial lens thickness increased ( + 0.34 ± 0.16 mm). Lens shape changes cause redistribution of the lens internal structure, leading to change in refractive index distribution profiles. With accommodation, in the axial direction refractive index profiles became flatter in the center and steeper near the periphery of the lens, while in the equatorial direction they became steeper in the center and flatter in the periphery. The results suggest that the anatomical accuracy of lens optical models can be improved by accounting for changes in the refractive index profile during accommodation. PMID:29541520

Eyesight quality and Computer Vision Syndrome.

PubMed

Bogdănici, Camelia Margareta; Săndulache, Diana Elena; Nechita, Corina Andreea

2017-01-01

The aim of the study was to analyze the effects that gadgets have on eyesight quality. A prospective observational study was conducted from January to July 2016, on 60 people who were divided into two groups: Group 1 - 30 middle school pupils with a mean age of 11.9 ± 1.86 and Group 2 - 30 patients evaluated in the Ophthalmology Clinic, "Sf. Spiridon" Hospital, Iași, with a mean age of 21.36 ± 7.16 years. The clinical parameters observed were the following: visual acuity (VA), objective refraction, binocular vision (BV), fusional amplitude (FA), Schirmer's test. A questionnaire was also distributed, which contained 8 questions that highlighted the gadget's impact on the eyesight. The use of different gadgets, such as computer, laptops, mobile phones or other displays become part of our everyday life and people experience a variety of ocular symptoms or vision problems related to these. Computer Vision Syndrome (CVS) represents a group of visual and extraocular symptoms associated with sustained use of visual display terminals. Headache, blurred vision, and ocular congestion are the most frequent manifestations determined by the long time use of gadgets. Mobile phones and laptops are the most frequently used gadgets. People who use gadgets for a long time have a sustained effort for accommodation. A small amount of refractive errors (especially myopic shift) was objectively recorded by various studies on near work. Dry eye syndrome could also be identified, and an improvement of visual comfort could be observed after the instillation of artificial tears drops. Computer Vision Syndrome is still under-diagnosed, and people should be made aware of the bad effects the prolonged use of gadgets has on eyesight.

Eyesight quality and Computer Vision Syndrome

PubMed Central

Bogdănici, Camelia Margareta; Săndulache, Diana Elena; Nechita, Corina Andreea

2017-01-01

The aim of the study was to analyze the effects that gadgets have on eyesight quality. A prospective observational study was conducted from January to July 2016, on 60 people who were divided into two groups: Group 1 – 30 middle school pupils with a mean age of 11.9 ± 1.86 and Group 2 – 30 patients evaluated in the Ophthalmology Clinic, “Sf. Spiridon” Hospital, Iași, with a mean age of 21.36 ± 7.16 years. The clinical parameters observed were the following: visual acuity (VA), objective refraction, binocular vision (BV), fusional amplitude (FA), Schirmer’s test. A questionnaire was also distributed, which contained 8 questions that highlighted the gadget’s impact on the eyesight. The use of different gadgets, such as computer, laptops, mobile phones or other displays become part of our everyday life and people experience a variety of ocular symptoms or vision problems related to these. Computer Vision Syndrome (CVS) represents a group of visual and extraocular symptoms associated with sustained use of visual display terminals. Headache, blurred vision, and ocular congestion are the most frequent manifestations determined by the long time use of gadgets. Mobile phones and laptops are the most frequently used gadgets. People who use gadgets for a long time have a sustained effort for accommodation. A small amount of refractive errors (especially myopic shift) was objectively recorded by various studies on near work. Dry eye syndrome could also be identified, and an improvement of visual comfort could be observed after the instillation of artificial tears drops. Computer Vision Syndrome is still under-diagnosed, and people should be made aware of the bad effects the prolonged use of gadgets has on eyesight. PMID:29450383

Cost of workplace accommodations for individuals with disabilities: with or without personal assistance services.

PubMed

Solovieva, Tatiana I; Walls, Richard T; Hendricks, Deborah J; Dowler, Denetta L

2009-10-01

This study compared the expense associated with use of personal assistance services (PAS) for individuals with disabilities to the expense incurred by individuals with disabilities who did not use PAS. The intent of this investigation was to assess the disability accommodation costs and benefits of PAS and non-PAS cases. The study uses 1,182 follow-up telephone surveys and 24 telephone interviews of employers who had previously contacted the Job Accommodation Network (JAN) to discuss disability-related accommodations for an employee or potential employee that were conducted from January 2004 through December 2006. The survey included 69 employers who had considered PAS. The surveys were conducted by the University of Iowa's Law, Health Policy, and Disability Center, which contacted employers who had previously contacted JAN for consultation on workplace accommodations. The interviews were conducted by the International Center for Disability Information at West Virginia University. Key findings point to the costs associated with PAS cases and with cases not involving PAS accommodations. As reported by the employers, the median "one-time cost" of accommodations (not $0) for non-PAS cases was $500. The median "one-time cost" of accommodations (not $0) for PAS cases was $1,850. When $0 cost of accommodations on PAS cases was factored in with "one-time cost" of accommodations for PAS cases, the median cost was $0. For non-PAS cases of accommodations, when $0 cost of accommodations was considered, the outcome was a median cost of $0. The annual cost for PAS accommodations was a median cost of $8,000 in comparison to $2,000 for non-PAS. The median dollar amount estimates of direct benefits were $1,600 for PAS accommodations, similar to $1,500 for non-PAS. The most frequently mentioned benefits from PAS accommodations were (a) increased productivity, (b) increased diversity, (c) retention of a valued employee, (d) improved interactions with co-workers, (e) increased overall company morale, and (f) increased overall company productivity. The findings heighten awareness of the cost and benefits aspects associated with PAS for people with disabilities. Many non-PAS accommodations cost nothing to the employer (e.g., changing the work schedule, moving the individual to another location). When dollar cost was involved, the costs for PAS accommodations were more than three times greater than non-PAS accommodations.

Constructive and Unproductive Processing of Traumatic Experiences in Trauma-Focused Cognitive-Behavioral Therapy for Youth.

PubMed

Hayes, Adele M; Yasinski, Carly; Grasso, Damion; Ready, C Beth; Alpert, Elizabeth; McCauley, Thomas; Webb, Charles; Deblinger, Esther

2017-03-01

Although there is substantial evidence to support the efficacy of cognitive-behavioral treatments (CBT) for posttraumatic stress disorder (PTSD), there is some debate about how these treatments have their effects. Modern learning theory and cognitive and emotional processing theories highlight the importance of reducing avoidance, facilitating the constructive processing of feared experiences, and strengthening new inhibitory learning. We examined variables thought to be associated with unproductive and constructive processing of traumatic experiences in a sample of 81 youth with elevated PTSD symptoms, who received Trauma-Focused Cognitive Behavioral Therapy (TF-CBT) for abuse or traumatic interpersonal loss. Sessions during the trauma narrative phase of TF-CBT were coded for indicators of unproductive processing (overgeneralization, rumination, avoidance) and constructive processing (decentering, accommodation of corrective information), as well as levels of negative emotion. In previous analyses of this trial (Ready et al., 2015), more overgeneralization during the narrative phase predicted less improvement in internalizing symptoms at posttreatment and a worsening of externalizing symptoms over the 12-month follow-up. In contrast, more accommodation predicted improvement in internalizing symptoms and also moderated the negative effects of overgeneralization on internalizing and externalizing symptoms. The current study examined correlates of overgeneralization and accommodation. Overgeneralization was associated with more rumination, less decentering, and more negative emotion, suggesting immersion in trauma-related material. Accommodation was associated with less avoidance and more decentering, suggesting a healthy distance from trauma-related material that might allow for processing and cognitive change. Decentering also predicted improvement in externalizing symptoms at posttreatment. Rumination and avoidance showed important associations with overgeneralization and accommodation, respectively, but did not predict treatment outcomes. This study identifies correlates of overgeneralization and accommodation that might shed light on how these variables relate to unproductive and constructive processing of traumatic experiences. Copyright © 2016. Published by Elsevier Ltd.

Supporting the Transition into Employment: A Study of Canadian Young Adults Living with Disabilities.

PubMed

Jetha, Arif; Bowring, Julie; Furrie, Adele; Smith, Frank; Breslin, Curtis

2018-04-25

Objective To examine the job accommodation and benefit needs of young adults with disabilities as they transition into employment, and their perceived barriers to meeting support needs. Methods An online survey was conducted of 155 Canadian young adults with disabilities (mean age = 25.8 years). Respondents were either employed or seeking employment, and were asked about their need for health benefits, and soft (e.g., flexible scheduling) and hard accommodations (e.g., ergonomic interventions), and perceived accommodation barriers. Disability characteristics (e.g., disability type), demographic details and work context information were collected. Multivariable logistic analyses were conducted to examine the factors associated with a greater need for health benefits and hard and soft accommodations. Result Participants reported having a physical (79%), psychological (79%) or cognitive/learning disability (77%); 68% had > 1 disability. Over half (55%) were employed. Health benefits and soft accommodations were most needed by participants. Also, an average of six perceived accommodation barriers were indicated; difficulty with disability disclosure was most frequently reported. More perceived accommodation barriers were associated with a greater need for health benefits (OR 1.17, 95% CI 1.04-1.31) and soft accommodations (OR 1.13, 95% CI 1.01-1.27). A psychological disability was a associated with a greater need for health benefits (OR 2.91, 95% CI 1.09-7.43) and soft accommodations (OR 3.83, 95% CI 1.41-10.42). Discussion Employers can support the employment of young adults with disabilities through provision of extended health benefits and soft accommodations. Addressing accommodation barriers could minimize unmet workplace need, and improve employment outcomes for young adults with disabilities as they begin their career and across the life course.

Objective Evaluation of Visual Fatigue Using Binocular Fusion Maintenance.

PubMed

Hirota, Masakazu; Morimoto, Takeshi; Kanda, Hiroyuki; Endo, Takao; Miyoshi, Tomomitsu; Miyagawa, Suguru; Hirohara, Yoko; Yamaguchi, Tatsuo; Saika, Makoto; Fujikado, Takashi

2018-03-01

In this study, we investigated whether an individual's visual fatigue can be evaluated objectively and quantitatively from their ability to maintain binocular fusion. Binocular fusion maintenance (BFM) was measured using a custom-made binocular open-view Shack-Hartmann wavefront aberrometer equipped with liquid crystal shutters, wherein eye movements and wavefront aberrations were measured simultaneously. Transmittance in the liquid crystal shutter in front of the subject's nondominant eye was reduced linearly, and BFM was determined from the transmittance at the point when binocular fusion was broken and vergence eye movement was induced. In total, 40 healthy subjects underwent the BFM test and completed a questionnaire regarding subjective symptoms before and after a visual task lasting 30 minutes. BFM was significantly reduced after the visual task ( P < 0.001) and was negatively correlated with the total subjective eye symptom score (adjusted R 2 = 0.752, P < 0.001). Furthermore, the diagnostic accuracy for visual fatigue was significantly higher in BFM than in the conventional test results (aggregated fusional vergence range, near point of convergence, and the high-frequency component of accommodative microfluctuations; P = 0.007). These results suggest that BFM can be used as an indicator for evaluating visual fatigue. BFM can be used to evaluate the visual fatigue caused by the new visual devices, such as head-mount display, objectively.

Supervisor and Organizational Factors Associated with Supervisor Support of Job Accommodations for Low Back Injured Workers.

PubMed

Kristman, Vicki L; Shaw, William S; Reguly, Paula; Williams-Whitt, Kelly; Soklaridis, Sophie; Loisel, Patrick

2017-03-01

Purpose Temporary job accommodations contribute to the prevention of chronic work disability due to low back pain (LBP) through the facilitation of early return to work; yet, workplace dimensions of job accommodation are poorly understood. The objective of this study was to determine supervisor and organizational factors associated with supervisors' support for temporary job accommodations for LBP injured workers. Methods Supervisors were recruited from 19 workplaces in the USA and Canada and completed an online survey regarding job accommodation practices and potential associated factors with respect to a case vignette of a worker with LBP. Multivariable linear regression was used to identify the most parsimonious set of factors associated with supervisors' support for accommodations. Results A total of 804 supervisors participated with 796 eligible for inclusion in the analysis. The final set of factors explained 21 % of the variance in supervisors' support for temporary job accommodations. Considerate leadership style (β = 0.261; 95 % CI 0.212, 0.310), workplace disability management policies and practices (β = 0.243; 95 % CI 0.188, 0.298), and supervisor autonomy for designing and providing workplace accommodations (β = 0.156; 95 % CI 0.071, 0.241) had the largest effect on supervisor support for accommodations. Conclusion Factors predicting supervisors' likelihood to accommodate LBP injured workers include use of considerate leadership style, workplace disability management policies and practices, and supervisor autonomy. Workplace interventions targeting these factors should be developed and evaluated for their ability to improve work disability prevention outcomes.

From optics to attention: visual perception in barn owls.

PubMed

Harmening, Wolf M; Wagner, Hermann

2011-11-01

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

Visualizing inequality

NASA Astrophysics Data System (ADS)

Eliazar, Iddo

2016-07-01

The study of socioeconomic inequality is of substantial importance, scientific and general alike. The graphic visualization of inequality is commonly conveyed by Lorenz curves. While Lorenz curves are a highly effective statistical tool for quantifying the distribution of wealth in human societies, they are less effective a tool for the visual depiction of socioeconomic inequality. This paper introduces an alternative to Lorenz curves-the hill curves. On the one hand, the hill curves are a potent scientific tool: they provide detailed scans of the rich-poor gaps in human societies under consideration, and are capable of accommodating infinitely many degrees of freedom. On the other hand, the hill curves are a powerful infographic tool: they visualize inequality in a most vivid and tangible way, with no quantitative skills that are required in order to grasp the visualization. The application of hill curves extends far beyond socioeconomic inequality. Indeed, the hill curves are highly effective 'hyperspectral' measures of statistical variability that are applicable in the context of size distributions at large. This paper establishes the notion of hill curves, analyzes them, and describes their application in the context of general size distributions.

Differences between naïve and expert observers’ vergence and accommodative responses to a range of targets

PubMed Central

Horwood, Anna M; Riddell, Patricia M

2015-01-01

Purpose Vergence and accommodation studies often use adult participants with experience of vision science. Reports of infant and clinical responses are generally more variable and of lower gain, with the implication that differences lie in immaturity or sub-optimal clinical characteristics but expert /naïve differences are rarely considered or quantified. Methods Sixteen undergraduates, naïve to vision science were individually matched by age, visual acuity, refractive error, heterophoria, stereoacuity and near point of accommodation to 2nd & 3rd year orthoptics and optometry undergraduates (“experts”). Accommodation and vergence responses were assessed to targets moving between 33cm, 50 cm, 1m and 2m using a haploscopic device incorporating a PlusoptiX SO4 autorefractor. Disparity, blur and looming cues were separately available or minimised in all combinations. Instruction set was minimal. Results In all cases, vergence and accommodation response slopes (gain) were steeper and closer to 1.0 in the expert group (p=0.001), with the largest expert /naïve differences for both vergence and accommodation being for near targets (p=0.012). For vergence, the differences between expert and naïve response slopes increased with increasingly open-loop targets (linear trend p=0.025). Although we predicted that proximal cues would drive additional response in the experts, the proximity-only cue was the only condition that showed no statistical effect of experience. Conclusions Expert observers provide more accurate responses to near target demand than closely matched naïve observers. We suggest that attention, practice, voluntary and proprioceptive effects may enhance responses in experienced participants when compared to a more typical general population. Differences between adult reports and the developmental and clinical literature may partially reflect expert / naïve effects, as well as developmental change. If developmental and clinical studies are to be compared to adult normative data, uninstructed naïve adult data should be used. PMID:20444119

Accommodative insufficiency in a student population in Iran.

PubMed

Hashemi, Hassan; Khabazkhoob, Mehdi; Nabovati, Payam; Shahraki, Fatemeh Azad; Ostadimoghaddam, Hadi; Faghihi, Mohammad; Aghamirsalim, Mohamadreza; Doostdar, Asgar; Yekta, Abbasali

2018-05-22

To determine the prevalence of accommodative insufficiency (AI) and its relation with age, gender, and refractive errors in a college-age student population in Iran. The present study was conducted cross-sectionally in 2017. All students had optometric tests including measurement of visual acuity, objective and subjective refraction, as well as binocular vision and accommodative examinations. Amplitude of accommodation was measured with the Donders' push-up method using the Royal Air Force (RAF) rule. Monocular accommodative facility was measured with ±2.00diopter flipper lenses. The accommodative response was tested using dynamic retinoscopy with the monocular estimation method (MEM). The prevalence of AI in the studied population was 4.07% (95% CI: 2.61-5.52). The rate was 6.04% (95% CI: 3.58-8.50) in females and 2.01% (95% CI: 0.53-3.48) in males, and logistic regression showed a significantly higher odds of AI in females (OR=3.14, 95% CI: 1.33-7.45, p-value=0.009). The prevalence of AI was 2.59% (95% CI: 0.55-7.56) in the 18-19-year-old age group and 4.08% (95% CI: 0.09-8.07) in the 24-25-year-old group (p-value=0.848). The prevalence of AI among emmetropic, myopic, and hyperopic individuals was 3.74% (95% CI: 1.88-5.61), 4.44% (95% CI: 2.07-6.81), and 5.26% (95% CI: 4.79-16.32), respectively (p-value=0.869). In the multiple regression model, only gender showed significant relationship with AI (Odds ratio=3.14, 95% CI: 1.33-7.45; p-values=0.009). The prevalence of AI in the present study is lower than the most prevalence rates reported in previous studies. In the present study, gender and AI showed a strong association, such that AI prevalence was significantly higher in females than males. Copyright © 2018 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.

Chick eyes under cycloplegia compensate for spectacle lenses despite six-hydroxy dopamine treatment.

PubMed

Schwahn, H N; Schaeffel, F

1994-08-01

To test whether eye growth changes produced by spectacle lens wear are mediated by changes in ciliary muscle tonus in chicks. Because there is evidence that deprivation myopia is based on a local-retinal mechanism in the eye that probably remains functional after cycloplegia as well as after ciliary ganglion or Edinger-Westphal lesions, none of these treatments provides insight into whether accommodation tonus is also important in the control of axial eye growth. Because 6-hydroxy dopamine (6-OHDA) suppresses deprivation myopia, to isolate growth changes mediated by accommodation the authors injected 6-OHDA and paralyzed accommodation in addition (by corneal application of vecuroniumbromide). To quantify the state of cycloplegia, the abnormal pecking responses of cyclopleged chickens were studied. The authors found that cycloplegia could be maintained for 3 hours daily by corneal application of vecuroniumbromide. To ensure that visual exposure was restricted to the time period of cycloplegia, chickens were transferred to a 3-hour light/21-hour dark cycle. Control experiments showed that emmetropization was still functional under the changed light cycle. Strikingly, even with suppressed local-retinal growth control mechanisms (as indicated by the lack of deprivation myopia in a 6-OHDA injected group of chickens with occluders) and paralysis of accommodation, the eyes compensated for the defocus imposed by spectacles by changing their axial growth rates to be similar to those of eyes with functional accommodation. The findings show that the ciliary muscle and the activity of the iris sphincter muscle are not involved in emmetropization in chicks. If accommodation mediates the growth effects with lenses, it must happen via another pathway. Based on previous results, the authors propose that either the choroidal nerves from the ciliary ganglion to the choroid are important or that another yet unknown pathway from the Edinger Westphal nucleus to the eye transmits the necessary information.

Accommodation and the Visual Regulation of Refractive State in Marmosets

PubMed Central

Troilo, David; Totonelly, Kristen; Harb, Elise

2009-01-01

Purpose To determine the effects of imposed anisometropic retinal defocus on accommodation, ocular growth, and refractive state changes in marmosets. Methods Marmosets were raised with extended-wear soft contact lenses for an average duration of 10 wks beginning at an average age of 76 d. Experimental animals wore either a positive or negative contact lens over one eye and a plano lens or no lens over the other. Another group wore binocular lenses of equal magnitude but opposite sign. Untreated marmosets served as controls and three wore plano lenses monocularly. Cycloplegic refractive state, corneal curvature, and vitreous chamber depth were measured before, during, and after the period of lens wear. To investigate the accommodative response, the effective refractive state was measured through each anisometropic condition at varying accommodative stimuli positions using an infrared refractometer. Results Eye growth and refractive state are significantly correlated with the sign and power of the contact lens worn. The eyes of marmosets reared with monocular negative power lenses had longer vitreous chambers and were myopic relative to contralateral control eyes (p<0.01). Monocular positive power lenses produced a significant reduction in vitreous chamber depth and hyperopia relative to the contralateral control eyes (p<0.05). In marmosets reared binocularly with lenses of opposite sign, we found larger interocular differences in vitreous chamber depths and refractive state (p<0.001). Accommodation influences the defocus experienced through the lenses, however, the mean effective refractive state was still hyperopia in the negative-lens-treated eyes and myopia in the positive-lens-treated eyes. Conclusions Imposed anisometropia effectively alters marmoset eye growth and refractive state to compensate for the imposed defocus. The response to imposed hyperopia is larger and faster than the response to imposed myopia. The pattern of accommodation under imposed anisometropia produces effective refractive states that are consistent with the changes in eye growth and refractive state observed. PMID:19104464

Improving Quality of Life Outcomes in Supported Accommodation for People with Intellectual Disability: What Makes a Difference?

ERIC Educational Resources Information Center

Bigby, Christine; Beadle-Brown, Julie

2018-01-01

Background: The quality of life (QOL) of people with intellectual disability living in supported accommodation services is variable, influenced by many possible factors. Various frameworks have attempted to identify these factors without assigning value, direction of influence or relative impact on outcomes. Methods: A realist review of the…

Culture Change from Tobacco Accommodation to Intolerance: Time to Connect the Dots

ERIC Educational Resources Information Center

Livingood, William C., Jr.; Allegrante, John P.; Green, Lawrence W.

2016-01-01

Broad changes in normative health behavior are critical to overcoming many of the contemporary challenges to public health. Reduction in tobacco use during the last third of the 20th century--one of the greatest improvements in public health--illustrates such change. The culture change from accommodation to intolerance of smoking is irrefutable.…

Identifying and individuating cognitive systems: a task-based distributed cognition alternative to agent-based extended cognition.

PubMed

Davies, Jim; Michaelian, Kourken

2016-08-01

This article argues for a task-based approach to identifying and individuating cognitive systems. The agent-based extended cognition approach faces a problem of cognitive bloat and has difficulty accommodating both sub-individual cognitive systems ("scaling down") and some supra-individual cognitive systems ("scaling up"). The standard distributed cognition approach can accommodate a wider variety of supra-individual systems but likewise has difficulties with sub-individual systems and faces the problem of cognitive bloat. We develop a task-based variant of distributed cognition designed to scale up and down smoothly while providing a principled means of avoiding cognitive bloat. The advantages of the task-based approach are illustrated by means of two parallel case studies: re-representation in the human visual system and in a biomedical engineering laboratory.

A Review of Research Related to Unmanned Aircraft System Visual Observers

DTIC Science & Technology

2014-10-01

accommodation. Poor Contrast Contrast refers to the difference in luminance between an object and its background. The larger the difference in luminance , the...to camouflage potential targets. Complex Backgrounds When the background behind an object contains a variety of luminance levels and contours it...itself contained a variety of luminance levels and contours. It is likely that this complex background effect would be seen more often between air

The ageing lens and cataract: a model of normal and pathological ageing

PubMed Central

Michael, R.; Bron, A. J.

2011-01-01

Cataract is a visible opacity in the lens substance, which, when located on the visual axis, leads to visual loss. Age-related cataract is a cause of blindness on a global scale involving genetic and environmental influences. With ageing, lens proteins undergo non-enzymatic, post-translational modification and the accumulation of fluorescent chromophores, increasing susceptibility to oxidation and cross-linking and increased light-scatter. Because the human lens grows throughout life, the lens core is exposed for a longer period to such influences and the risk of oxidative damage increases in the fourth decade when a barrier to the transport of glutathione forms around the lens nucleus. Consequently, as the lens ages, its transparency falls and the nucleus becomes more rigid, resisting the change in shape necessary for accommodation. This is the basis of presbyopia. In some individuals, the steady accumulation of chromophores and complex, insoluble crystallin aggregates in the lens nucleus leads to the formation of a brown nuclear cataract. The process is homogeneous and the affected lens fibres retain their gross morphology. Cortical opacities are due to changes in membrane permeability and enzyme function and shear-stress damage to lens fibres with continued accommodative effort. Unlike nuclear cataract, progression is intermittent, stepwise and non-uniform. PMID:21402586

The dual function of barred plumage in birds: camouflage and communication.

PubMed

Gluckman, T L; Cardoso, G C

2010-11-01

A commonly held principle in visual ecology is that communication compromises camouflage: while visual signals are often conspicuous, camouflage provides concealment. However, some traits may have evolved for communication and camouflage simultaneously, thereby overcoming this functional compromise. Visual patterns generally provide camouflage, but it was suggested that a particular type of visual pattern – avian barred plumage – could also be a signal of individual quality. Here, we test if the evolution of sexual dimorphism in barred plumage, as well as differences between juvenile and adult plumage, indicate camouflage and/or signalling functions across the class Aves. We found a higher frequency of female- rather than male-biased sexual dimorphism in barred plumage, indicating that camouflage is its most common function. But we also found that, compared to other pigmentation patterns, barred plumage is more frequently biased towards males and its expression more frequently restricted to adulthood, suggesting that barred plumage often evolves or is maintained as a sexual communication signal. This illustrates how visual traits can accommodate the apparently incompatible functions of camouflage and communication, which has implications for our understanding of avian visual ecology and sexual ornamentation.

Visual symptomatology and referral patterns for Operation Iraqi Freedom and Operation Enduring Freedom veterans with traumatic brain injury.

PubMed

Bulson, Ryan; Jun, Weon; Hayes, John

2012-01-01

Advances in protective armor technology and changes in the "patterns of war" have created a population of Operation Iraqi Freedom/Operation Enduring Freedom (OIF/OEF) veterans with traumatic brain injury (TBI) that provide a unique challenge to Department of Veterans Affairs (VA) healthcare practitioners. The purpose of the study was to determine the frequency of symptomatic ocular and visual sequelae of TBI in OIF/OEF veterans at the Portland VA Medical Center, a Polytrauma Support Clinic Team site. A retrospective analysis of 100 OIF/OEF veterans with TBI was conducted to determine the prevalence of ocular and visual complaints. Referral patterns were also investigated. Visual symptoms were reported in approximately 50% of veterans with TBI. Loss of consciousness, but not number of deployments or number of blast exposures, was found to have a statistically significant association with severity of reported visual symptoms. The most commonly reported symptoms included blurred vision (67%), photosensitivity (50%), and accommodative problems (40%). Visual symptoms of OIF/OEF veterans at the Portland VA Medical Center are reported at slightly lower rates than similar studies conducted at the Palo Alto and Edward Hines Jr VA facilities.

Advanced detection, isolation, and accommodation of sensor failures in turbofan engines: Real-time microcomputer implementation

NASA Technical Reports Server (NTRS)

Delaat, John C.; Merrill, Walter C.

1990-01-01

The objective of the Advanced Detection, Isolation, and Accommodation Program is to improve the overall demonstrated reliability of digital electronic control systems for turbine engines. For this purpose, an algorithm was developed which detects, isolates, and accommodates sensor failures by using analytical redundancy. The performance of this algorithm was evaluated on a real time engine simulation and was demonstrated on a full scale F100 turbofan engine. The real time implementation of the algorithm is described. The implementation used state-of-the-art microprocessor hardware and software, including parallel processing and high order language programming.

Binocular Vision in Chronic Fatigue Syndrome.

PubMed

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

2016-01-01

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

Reading from electronic devices versus hardcopy text.

PubMed

Hue, Jennifer E; Rosenfield, Mark; Saá, Gianinna

2014-01-01

The use of electronic reading devices has increased dramatically. However, some individuals report increased visual symptoms when reading from electronic screens. This investigation compared reading from two electronic devices (Amazon Kindle or Apple Ipod) versus hardcopy text in two groups of 20 subjects. Subjects performed a 20 min reading task for each condition. Both the accommodative response and reading rate were monitored during the trial. Immediately post-task, subjects completed a questionnaire concerning the ocular symptoms experienced during the task. In comparing the Kindle with hardcopy, no significant difference in the total symptom score was observed, although the mean score for the symptoms of tired eyes and eye discomfort was significantly higher with the Kindle. No significant differences in reading rate were found. When comparing the Ipod with hardcopy, no significant differences in symptom scores were found. The mean reading rate with the Ipod was significantly slower than for hardcopy while the mean lag of accommodation was significantly larger for the Ipod. Given the significant increase in symptoms with the Kindle, and larger lag of accommodation and reduced reading rate with the Ipod, one may conclude that reading from electronic devices is not equivalent to hardcopy.

Correlation between ocular parameters and amplitude of accommodation

PubMed Central

Abraham, Lekha Mary; Kuriakose, Thomas; Sivanandam, Viswanathan; Venkatesan, Nithya; Thomas, Ravi; Muliyil, Jayaprakash

2010-01-01

Aim: To study the relationship between ocular parameters and amplitude of accommodation (AA) in the peri-presbyopic age group (35–50 years). Materials and Methods: Three hundred and sixteen right eyes of consecutive patients in the age group 35–50 years, who attended our outpatient clinic, were studied. Emmetropes, hypermetropes and myopes with best-corrected visual acuity of 20/20, J1 in both eyes were included. The AA was calculated by measuring the near point of accommodation. The axial length (AL), central anterior chamber depth (CACD) and lens thickness (LT) were also measured. Results: There was moderate correlation (Pearson’s correlation coefficient r = 0.56) between AL and AA as well as between CACD and AA (r = 0.53) in myopes in the age group 35–39 years. In the other age groups and the groups taken as a whole, there was no correlation. In hypermetropes and emmetropes, there was no correlation between AA and the above ocular parameters. No significant correlation existed between LT and AA across different age groups and refractive errors. Conclusion: There was no significant correlation between AA and ocular parameters like anterior chamber depth, AL and LT. PMID:20952831

Modeling the convergence accommodation of stereo vision for binocular endoscopy.

PubMed

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

2018-02-01

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

Phylo-VISTA: Interactive visualization of multiple DNA sequence alignments

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

Shah, Nameeta; Couronne, Olivier; Pennacchio, Len A.

The power of multi-sequence comparison for biological discovery is well established. The need for new capabilities to visualize and compare cross-species alignment data is intensified by the growing number of genomic sequence datasets being generated for an ever-increasing number of organisms. To be efficient these visualization algorithms must support the ability to accommodate consistently a wide range of evolutionary distances in a comparison framework based upon phylogenetic relationships. Results: We have developed Phylo-VISTA, an interactive tool for analyzing multiple alignments by visualizing a similarity measure for multiple DNA sequences. The complexity of visual presentation is effectively organized using a frameworkmore » based upon interspecies phylogenetic relationships. The phylogenetic organization supports rapid, user-guided interspecies comparison. To aid in navigation through large sequence datasets, Phylo-VISTA leverages concepts from VISTA that provide a user with the ability to select and view data at varying resolutions. The combination of multiresolution data visualization and analysis, combined with the phylogenetic framework for interspecies comparison, produces a highly flexible and powerful tool for visual data analysis of multiple sequence alignments. Availability: Phylo-VISTA is available at http://www-gsd.lbl. gov/phylovista. It requires an Internet browser with Java Plugin 1.4.2 and it is integrated into the global alignment program LAGAN at http://lagan.stanford.edu« less

Maximising Occupancy. Accommodation Management Module. Operational Management Programme.

ERIC Educational Resources Information Center

Holland, Julia

This module on maximizing occupancy is intended to cover the basic framework for analysis of occupancy in accommodations and for identification of ways to improve it on both a long-term and day-to-day basis. The material is presented in a self-instructional format in seven sections. At the beginning of each section is a statement of the objectives…

Higher Education and Disability: Improved Federal Enforcement Needed to Better Protect Students' Rights to Testing Accommodations. Report to Congressional Requesters. GAO-12-40

ERIC Educational Resources Information Center

Scott, George A.

2011-01-01

Standardized tests are often required to gain admission into postsecondary schools or to obtain professional certifications. Federal disability laws, such as the Americans with Disabilities Act (ADA) require entities that administer these tests to provide accommodations, such as extended time or changes in test format, to students with…

Improved data illustration in complex multi-ligament knee reconstruction surgery: using the historical principles of Florence Nightingale and John Venn.

PubMed

Meyers, Paul D; McNicholas, Mike J

2008-04-01

The collection of multi-ligament knee reconstruction procedure data generates long tabulated lists of featureless abbreviations, which are often difficult to interpret and present. As demonstrated with the launch of the Scandinavian anterior cruciate ligament registries, such data are under increasing scrutiny. When developing a visual tool to improve the interpretation, presentation, and ongoing collection of data within this field, much can be learnt from the historical teachings of Florence Nightingale and John Venn. Unknown to many, Florence Nightingale was a pioneer of graphic data illustration, becoming a Fellow of the Royal Statistical Society in 1858. Further advances in the visualization of complex data relations were made by John Venn, who introduced the Venn diagram in 1880. With this background in mind, the present work has been based upon the senior author's case series of 70 patients undergoing complex knee-ligament reconstruction at Warrington Hospital, from 2001 to the present time. Although obviously not negating the need for tabulated data, the graphic representation put forward here successfully supplements featureless tabulated lists of abbreviations and can be updated easily and regularly. Providing a clear, bright illustration that is free from patient identifiers, it can be used in presentations and publications, and freely accessed by a multidisciplinary team. It assists in the identification of injury patterns, can accommodate illustration of associated factors such as meniscal injury, and clearly demonstrates each hospital's multi-ligament knee reconstruction experience. This facilitates comparison and collaboration between hospitals and promotes research.

A domains-based taxonomy of supported accommodation for people with severe and persistent mental illness.

PubMed

Siskind, Dan; Harris, Meredith; Pirkis, Jane; Whiteford, Harvey

2013-06-01

A lack of definitional clarity in supported accommodation and the absence of a widely accepted system for classifying supported accommodation models creates barriers to service planning and evaluation. We undertook a systematic review of existing supported accommodation classification systems. Using a structured system for qualitative data analysis, we reviewed the stratification features in these classification systems, identified the key elements of supported accommodation and arranged them into domains and dimensions to create a new taxonomy. The existing classification systems were mapped onto the new taxonomy to verify the domains and dimensions. Existing classification systems used either a service-level characteristic or programmatic approach. We proposed a taxonomy based around four domains: duration of tenure; patient characteristics; housing characteristics; and service characteristics. All of the domains in the taxonomy were drawn from the existing classification structures; however, none of the existing classification structures covered all of the domains in the taxonomy. Existing classification systems are regionally based, limited in scope and lack flexibility. A domains-based taxonomy can allow more accurate description of supported accommodation services, aid in identifying the service elements likely to improve outcomes for specific patient populations, and assist in service planning.

Primary care for adults on the autism spectrum.

PubMed

Nicolaidis, Christina; Kripke, Clarissa Calliope; Raymaker, Dora

2014-09-01

Autism spectrum disorder (ASD) is defined by differences in social communication and restricted, repetitive patterns of behavior, interests, or activities. Skills and challenges can change depending on environmental stimuli, supports, and stressors. Quality of life can be improved by the use of accommodations, assistive technologies, therapies to improve adaptive function or communication, caregiver training, acceptance, access, and inclusion. This article focuses on the identification of ASD in adults, referrals for services, the recognition of associated conditions, strategies and accommodations to facilitate effective primary care services, and ethical issues related to caring for autistic adults. Copyright © 2014 Elsevier Inc. All rights reserved.

The Perspective Structure of Visual Space

PubMed Central

2015-01-01

Luneburg’s model has been the reference for experimental studies of visual space for almost seventy years. His claim for a curved visual space has been a source of inspiration for visual scientists as well as philosophers. The conclusion of many experimental studies has been that Luneburg’s model does not describe visual space in various tasks and conditions. Remarkably, no alternative model has been suggested. The current study explores perspective transformations of Euclidean space as a model for visual space. Computations show that the geometry of perspective spaces is considerably different from that of Euclidean space. Collinearity but not parallelism is preserved in perspective space and angles are not invariant under translation and rotation. Similar relationships have shown to be properties of visual space. Alley experiments performed early in the nineteenth century have been instrumental in hypothesizing curved visual spaces. Alleys were computed in perspective space and compared with reconstructed alleys of Blumenfeld. Parallel alleys were accurately described by perspective geometry. Accurate distance alleys were derived from parallel alleys by adjusting the interstimulus distances according to the size-distance invariance hypothesis. Agreement between computed and experimental alleys and accommodation of experimental results that rejected Luneburg’s model show that perspective space is an appropriate model for how we perceive orientations and angles. The model is also appropriate for perceived distance ratios between stimuli but fails to predict perceived distances. PMID:27648222

Stereoscopic visual fatigue assessment and modeling

NASA Astrophysics Data System (ADS)

Wang, Danli; Wang, Tingting; Gong, Yue

2014-03-01

Evaluation of stereoscopic visual fatigue is one of the focuses in the user experience research. It is measured in either subjective or objective methods. Objective measures are more preferred for their capability to quantify the degree of human visual fatigue without being affected by individual variation. However, little research has been conducted on the integration of objective indicators, or the sensibility of each objective indicator in reflecting subjective fatigue. The paper proposes a simply effective method to evaluate visual fatigue more objectively. The stereoscopic viewing process is divided into series of sessions, after each of which viewers rate their visual fatigue with subjective scores (SS) according to a five-grading scale, followed by tests of the punctum maximum accommodation (PMA) and visual reaction time (VRT). Throughout the entire viewing process, their eye movements are recorded by an infrared camera. The pupil size (PS) and percentage of eyelid closure over the pupil over time (PERCLOS) are extracted from the videos processed by the algorithm. Based on the method, an experiment with 14 subjects was conducted to assess visual fatigue induced by 3D images on polarized 3D display. The experiment consisted of 10 sessions (5min per session), each containing the same 75 images displayed randomly. The results show that PMA, VRT and PERCLOS are the most efficient indicators of subjective visual fatigue and finally a predictive model is derived from the stepwise multiple regressions.

Objective Evaluation of Visual Fatigue Using Binocular Fusion Maintenance

PubMed Central

Hirota, Masakazu; Morimoto, Takeshi; Kanda, Hiroyuki; Endo, Takao; Miyoshi, Tomomitsu; Miyagawa, Suguru; Hirohara, Yoko; Yamaguchi, Tatsuo; Saika, Makoto

2018-01-01

Purpose In this study, we investigated whether an individual's visual fatigue can be evaluated objectively and quantitatively from their ability to maintain binocular fusion. Methods Binocular fusion maintenance (BFM) was measured using a custom-made binocular open-view Shack–Hartmann wavefront aberrometer equipped with liquid crystal shutters, wherein eye movements and wavefront aberrations were measured simultaneously. Transmittance in the liquid crystal shutter in front of the subject's nondominant eye was reduced linearly, and BFM was determined from the transmittance at the point when binocular fusion was broken and vergence eye movement was induced. In total, 40 healthy subjects underwent the BFM test and completed a questionnaire regarding subjective symptoms before and after a visual task lasting 30 minutes. Results BFM was significantly reduced after the visual task (P < 0.001) and was negatively correlated with the total subjective eye symptom score (adjusted R2 = 0.752, P < 0.001). Furthermore, the diagnostic accuracy for visual fatigue was significantly higher in BFM than in the conventional test results (aggregated fusional vergence range, near point of convergence, and the high-frequency component of accommodative microfluctuations; P = 0.007). Conclusions These results suggest that BFM can be used as an indicator for evaluating visual fatigue. Translational Relevance BFM can be used to evaluate the visual fatigue caused by the new visual devices, such as head-mount display, objectively. PMID:29600117

Localization of Virtual Objects in the Near Visual Field (Operator Interaction with Simple Virtual Objects)

NASA Technical Reports Server (NTRS)

Ellis, Stephen R.; Menges, Brian M.

1998-01-01

Errors in the localization of nearby virtual objects presented via see-through, helmet mounted displays are examined as a function of viewing conditions and scene content in four experiments using a total of 38 subjects. Monocular, biocular or stereoscopic presentation of the virtual objects, accommodation (required focus), subjects' age, and the position of physical surfaces are examined. Nearby physical surfaces are found to introduce localization errors that differ depending upon the other experimental factors. These errors apparently arise from the occlusion of the physical background by the optically superimposed virtual objects. But they are modified by subjects' accommodative competence and specific viewing conditions. The apparent physical size and transparency of the virtual objects and physical surfaces respectively are influenced by their relative position when superimposed. The design implications of the findings are discussed in a concluding section.

Toying with the moon illusion.

PubMed

Lockhead, G R; Wolbarsht, M L

1991-08-20

We propose that the correct interpretation of the moon illusion is that the zenith moon appears small, not that the horizon moon appears large. This illusion is caused by the visual gap between the observer and the overhead moon. Because of the gap, the observer has no or little optical information about the distance of the moon. This results in empty field myopia where the moon is neurally, although not necessarily cognitively, processed as being at about arm's length. When the moon is seen on the horizon, there usually is optical information about distance. That results in reduced accommodation, and so the moon is processed as at a greater distance. Consistent with the size-distance-invariance hypothesis, the moon is then judged as large. This is a specific example of the more general fact that all distant objects appear small in the absence of a stimulus for accommodation to be distant. This outcome produces the toy illusion.

Enabling Disabled Persons to Gain Access to Digital Media

NASA Technical Reports Server (NTRS)

Beach, Glenn; OGrady, Ryan

2011-01-01

A report describes the first phase in an effort to enhance the NaviGaze software to enable profoundly disabled persons to operate computers. (Running on a Windows-based computer equipped with a video camera aimed at the user s head, the original NaviGaze software processes the user's head movements and eye blinks into cursor movements and mouse clicks to enable hands-free control of the computer.) To accommodate large variations in movement capabilities among disabled individuals, one of the enhancements was the addition of a graphical user interface for selection of parameters that affect the way the software interacts with the computer and tracks the user s movements. Tracking algorithms were improved to reduce sensitivity to rotations and reduce the likelihood of tracking the wrong features. Visual feedback to the user was improved to provide an indication of the state of the computer system. It was found that users can quickly learn to use the enhanced software, performing single clicks, double clicks, and drags within minutes of first use. Available programs that could increase the usability of NaviGaze were identified. One of these enables entry of text by using NaviGaze as a mouse to select keys on a virtual keyboard.

The Charles F. Prentice Award Lecture 2005: optics of the human eye: progress and problems.

PubMed

Charman, W Neil

2006-06-01

The history of measurements of ocular aberration is briefly reviewed and recent work using much-improved aberrometers and large samples of eyes is summarized. When on-axis, higher-order, monochromatic aberrations are averaged, undercorrected, positive, fourth-order spherical aberration dominates; other Zernike wavefront aberration coefficients have average values near zero. Individually, however, many eyes show substantial amounts of third-order and other fourth-order aberrations; the value of these varies idiosyncratically about zero. Most normal eyes show only small amounts of axial monochromatic aberration for photopic pupils up to around 3 mm; the limits to retinal image quality are then usually set by diffraction, uncorrected or imperfectly corrected spherocylindrical refractive error, accommodation error, and chromatic aberration. Longitudinal chromatic aberration varies very little across the population. With larger mesopic and scotopic pupils, monochromatic aberration plays a more important optical role, but overall visual performance is increasingly dominated by neural factors. Some remaining problems in measuring and modeling the eye's optical performance are discussed.

agriGO v2.0: a GO analysis toolkit for the agricultural community, 2017 update

PubMed Central

Tian, Tian; Liu, Yue; Yan, Hengyu; You, Qi; Yi, Xin; Du, Zhou

2017-01-01

Abstract The agriGO platform, which has been serving the scientific community for >10 years, specifically focuses on gene ontology (GO) enrichment analyses of plant and agricultural species. We continuously maintain and update the databases and accommodate the various requests of our global users. Here, we present our updated agriGO that has a largely expanded number of supporting species (394) and datatypes (865). In addition, a larger number of species have been classified into groups covering crops, vegetables, fish, birds and insects closely related to the agricultural community. We further improved the computational efficiency, including the batch analysis and P-value distribution (PVD), and the user-friendliness of the web pages. More visualization features were added to the platform, including SEACOMPARE (cross comparison of singular enrichment analysis), direct acyclic graph (DAG) and Scatter Plots, which can be merged by choosing any significant GO term. The updated platform agriGO v2.0 is now publicly accessible at http://systemsbiology.cau.edu.cn/agriGOv2/. PMID:28472432

Management of digital eye strain.

PubMed

Coles-Brennan, Chantal; Sulley, Anna; Young, Graeme

2018-05-23

Digital eye strain, an emerging public health issue, is a condition characterised by visual disturbance and/or ocular discomfort related to the use of digital devices and resulting from a range of stresses on the ocular environment. This review aims to provide an overview of the extensive literature on digital eye strain research with particular reference to the clinical management of symptoms. As many as 90 per cent of digital device users experience symptoms of digital eye strain. Many studies suggest that the following factors are associated with digital eye strain: uncorrected refractive error (including presbyopia), accommodative and vergence anomalies, altered blinking pattern (reduced rate and incomplete blinking), excessive exposure to intense light, closer working distance, and smaller font size. Since a symptom may be caused by one or more factors, a holistic approach should be adopted. The following management strategies have been suggested: (i) appropriate correction of refractive error, including astigmatism and presbyopia; (ii) management of vergence anomalies, with the aim of inducing or leaving a small amount of heterophoria (~1.5 Δ Exo); (iii) blinking exercise/training to maintain normal blinking pattern; (iv) use of lubricating eye drops (artificial tears) to help alleviate dry eye-related symptoms; (v) contact lenses with enhanced comfort, particularly at end-of-day and in challenging environments; (vi) prescription of colour filters in all vision correction options, especially blue light-absorbing filters; and (vii) management of accommodative anomalies. Prevention is the main strategy for management of digital eye strain, which involves: (i) ensuring an ergonomic work environment and practice (through patient education and the implementation of ergonomic workplace policies); and (ii) visual examination and eye care to treat visual disorders. Special consideration is needed for people at a high risk of digital eye strain, such as computer workers and contact lens wearers. © 2018 Optometry Australia.

Visual information processing; Proceedings of the Meeting, Orlando, FL, Apr. 20-22, 1992

NASA Technical Reports Server (NTRS)

Huck, Friedrich O. (Editor); Juday, Richard D. (Editor)

1992-01-01

Topics discussed in these proceedings include nonlinear processing and communications; feature extraction and recognition; image gathering, interpolation, and restoration; image coding; and wavelet transform. Papers are presented on noise reduction for signals from nonlinear systems; driving nonlinear systems with chaotic signals; edge detection and image segmentation of space scenes using fractal analyses; a vision system for telerobotic operation; a fidelity analysis of image gathering, interpolation, and restoration; restoration of images degraded by motion; and information, entropy, and fidelity in visual communication. Attention is also given to image coding methods and their assessment, hybrid JPEG/recursive block coding of images, modified wavelets that accommodate causality, modified wavelet transform for unbiased frequency representation, and continuous wavelet transform of one-dimensional signals by Fourier filtering.

A Visual Profile of Queensland Indigenous Children.

PubMed

Hopkins, Shelley; Sampson, Geoff P; Hendicott, Peter L; Wood, Joanne M

2016-03-01

Little is known about the prevalence of refractive error, binocular vision, and other visual conditions in Australian Indigenous children. This is important given the association of these visual conditions with reduced reading performance in the wider population, which may also contribute to the suboptimal reading performance reported in this population. The aim of this study was to develop a visual profile of Queensland Indigenous children. Vision testing was performed on 595 primary schoolchildren in Queensland, Australia. Vision parameters measured included visual acuity, refractive error, color vision, nearpoint of convergence, horizontal heterophoria, fusional vergence range, accommodative facility, AC/A ratio, visual motor integration, and rapid automatized naming. Near heterophoria, nearpoint of convergence, and near fusional vergence range were used to classify convergence insufficiency (CI). Although refractive error (Indigenous, 10%; non-Indigenous, 16%; p = 0.04) and strabismus (Indigenous, 0%; non-Indigenous, 3%; p = 0.03) were significantly less common in Indigenous children, CI was twice as prevalent (Indigenous, 10%; non-Indigenous, 5%; p = 0.04). Reduced visual information processing skills were more common in Indigenous children (reduced visual motor integration [Indigenous, 28%; non-Indigenous, 16%; p < 0.01] and slower rapid automatized naming [Indigenous, 67%; non-Indigenous, 59%; p = 0.04]). The prevalence of visual impairment (reduced visual acuity) and color vision deficiency was similar between groups. Indigenous children have less refractive error and strabismus than their non-Indigenous peers. However, CI and reduced visual information processing skills were more common in this group. Given that vision screenings primarily target visual acuity assessment and strabismus detection, this is an important finding as many Indigenous children with CI and reduced visual information processing may be missed. Emphasis should be placed on identifying children with CI and reduced visual information processing given the potential effect of these conditions on school performance.

Effect of Multiple Dietary Supplement Containing Lutein, 
Astaxanthin, Cyanidin-3-Glucoside, and DHA on Accommodative Ability

PubMed Central

Kono, Keiko; Shimizu, Yoshiki; Takahashi, Satomi; Matsuoka, Sayuri; Yui, Kei

2014-01-01

Objective The study aimed to verify that ingestion of multiple dietary supplement containing lutein, astaxanthin, cyanidin-3-glucoside and docosahexaenoic acid (DHA) would improve accommodative ability of aged and older subjects who were aware of eye strain on a daily basis. Methods A randomized double-blind placebo-controlled parallel group comparison study was conducted for 48 participants aged 45 to 64 years who complained of eye strain. The subjects took multiple dietary supplement containing 10 mg of lutein, 20 mg of bilberry extract and 26.5 mg of black soybean hull extract (a total of 2.3 mg of cyanidin-3-glucoside in both extracts), 4 mg of astaxanthin, and 50 mg of DHA (test supplement) or placebo for four consecutive weeks. Near-point accommodation (NPA) and subjective symptoms were evaluated both before and after four weeks’ intake. Results The variation of the NPA of both eyes from baseline to 4 weeks’ post-intake in the test supplement group was significantly higher than in the placebo group (1.321±0.394 diopter (D) in the test supplement group and 0.108±0.336 D in the placebo group, p=0.023). The multiple dietary supplement group showed improvement in the NPA. Regarding subjective symptoms, significant improvement of “stiff shoulders or neck” and “blurred vision” was also found in the test supplement group compared to the placebo group (p<0.05). There were no safety concerns in this study. Conclusion This study shows that multiple dietary supplement containing lutein, astaxanthin, cyanidin-3-glucoside, and DHA has effect to improve accommodative ability and subjective symptoms related to eye fatigue.

The Significance of Emotions and Professional Relations for Accommodating a Web-Based Ulcer Record and Improving Home-Based Care

PubMed Central

Ekeland, Anne G.

2015-01-01

Evidence of technological performance, medical improvements and economic effectiveness is generally considered sufficient for judging advances in healthcare. In this paper, I aim to add knowledge about the ways human emotions and professional relations play roles in the processes of accommodating new technologies for quality improvements. A newly-implemented, web-based ulcer record service for patients with chronic skin ulcers constitutes the case. After one year, only a few home care nurses were using the service, interacting with a specialist team. The result was disappointing, but the few users were enthusiastic. An explorative, qualitative study was initiated to understand the users, the processes that accounted for use and how improvements were enacted. In the paper, I expose the emotional aspects of the record accommodation by analyzing the ways emotions were translated in the process and how they influenced the improvements. I contend that use came about through a heterogeneous assemblage of ethical engagement and compassionate emotions stemming from frustration, combined with technological affordances and relations between different professionals. Certain aspects of the improvements are exposed. These are discussed as: (1) reconciliations between the medical facts and rational judgments, on one side, and the emotional and subjective values for judging quality, on the other; and (2) mediation between standardized and personalized care. The healing of ulcers was combined with a sense of purpose and wellbeing to validate improvements. Emotions were strongly involved, and the power of evaluative emotions and professional relations should be further explored to add to the understanding of innovation processes and to validate quality improvements. PMID:27417745

The Significance of Emotions and Professional Relations for Accommodating a Web-Based Ulcer Record and Improving Home-Based Care.

PubMed

Ekeland, Anne G

2015-01-22

Evidence of technological performance, medical improvements and economic effectiveness is generally considered sufficient for judging advances in healthcare. In this paper, I aim to add knowledge about the ways human emotions and professional relations play roles in the processes of accommodating new technologies for quality improvements. A newly-implemented, web-based ulcer record service for patients with chronic skin ulcers constitutes the case. After one year, only a few home care nurses were using the service, interacting with a specialist team. The result was disappointing, but the few users were enthusiastic. An explorative, qualitative study was initiated to understand the users, the processes that accounted for use and how improvements were enacted. In the paper, I expose the emotional aspects of the record accommodation by analyzing the ways emotions were translated in the process and how they influenced the improvements. I contend that use came about through a heterogeneous assemblage of ethical engagement and compassionate emotions stemming from frustration, combined with technological affordances and relations between different professionals. Certain aspects of the improvements are exposed. These are discussed as: (1) reconciliations between the medical facts and rational judgments, on one side, and the emotional and subjective values for judging quality, on the other; and (2) mediation between standardized and personalized care. The healing of ulcers was combined with a sense of purpose and wellbeing to validate improvements. Emotions were strongly involved, and the power of evaluative emotions and professional relations should be further explored to add to the understanding of innovation processes and to validate quality improvements.

COMPARATIVE EFFECTIVENESS OF AN ADJUSTABLE TRANSFEMORAL PROSTHETIC INTERFACE ACCOMMODATING VOLUME FLUCTUATION: CASE STUDY

PubMed Central

Kahle, Jason T.; Klenow, Tyler D.; Highsmith, M. Jason

2016-01-01

The socket-limb interface is vital for functionality and provides stability and mobility for the amputee. Volume fluctuation can lead to compromised fit and function. Current socket technology does not accommodate for volume fluctuation. An adjustable interface may improve function and comfort by filling this technology gap. The purpose of this study was to compare the effectiveness of the standard of care (SOC) ischial ramus containment to an adjustable transfemoral prosthetic interface socket in the accommodation of volume fluctuation. A prospective experimental case study using repeated measures of subjective and performance outcome measures between socket conditions was employed. In the baseline volume condition, the adjustable socket improved subjective and performance measures 19% to 37% over SOC, whereas the two-minute walk test demonstrated equivalence. In the volume loss condition, the adjustable socket improved all subjective and performance measures 22% to 93%. All aggregated data improved 16% to 50% compared with the SOC. In simulated volume gain, the SOC socket failed, while the subject was able to complete the protocol using the adjustable socket. In this case study, the SOC socket was inferior to the comparative adjustable transfemoral amputation interface in subjective and performance outcomes. There is a lack of clinical trials and evidence comparing socket functional outcomes related to volume fluctuation. PMID:28066526

Optimization of neural retinal visual motor strategies in recovery of visual acuity following acute laser-induced macula injury

NASA Astrophysics Data System (ADS)

Zwick, Harry; Ness, James W.; Loveday, J.; Molchany, Jerome W.; Stuck, Bruce E.

1997-05-01

Laser induced damage to the retina may produce immediate and serious loss in visual acuity as well as subsequent recovery of visual acuity over a 1 to 6 month post exposure period. While acuity may recover, full utilization of the foveal region may not return. In one patient, a superior/temporal preferred retinal location (PRL) was apparent, while a second patient demonstrated significant foveal involvement and contrast sensitivity more reflective of foveal than parafoveal involvement. These conditions of injury wee simulated by using an artificial scotoma technique which optically stabilized a 5 degree opacity in the center of the visual field. The transmission of spatially degraded target information in the scotoma was 0 percent, 5 percent and 95 percent. Contrast sensitivity for the 0 percent and 5 percent transmission scotoma showed broad spatial frequency suppression as opposed to a bipartite contrast sensitivity function with a narrow sensitivity loss at 3 cycles/degree for the 95 percent transmission scotoma. A PRL shift to superior temporal retina with a concomitant change in accommodation was noted as target resolution became more demanding. These findings suggest that restoration of visual acuity in human laser accidents may depend upon the functionality of complex retinal and cortical adaptive mechanisms.

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

PubMed

Moro, Stefania S; Steeves, Jennifer K E

2018-04-13

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

A guide to performing basic manifest refractometry.

PubMed

Garber, N

2000-01-01

Refractometry provides the ophthalmologist with the prescription that has the most plus power with the best vision. This eliminates the need for the patient accommodating to achieve clear vision at distance. Flowcharts, of the refractometry process, help the refractionist use standard procedures to accurately arrive at the correct baseline prescription for the patient's refractive state. By using the patient's history of subjective complaints, past refractive corrections, and present visual needs, the ophthalmologist then can prescribe the final prescription.

[The clinical efficacy and safety study of Esculin and Digitalis glycosides Eye Drops in treating ametropic asthenopia].

PubMed

Jiang, Zhen-ying; Qu, Xiao-mei; Li, Xiao-xin; Liu, Yu-ling; Shen, Nian-ci; Zhang, Lin; Ke, Bi-lian; Zhao, Pei-quan; Jiang, Jun; Yao, Ke; Zeng, Jin; Yang, Xiao; Chu, Ren-yuan

2010-12-01

To study the clinical efficacy and safety of the Esculin and Digitalis glycosides Eye Drops used in the patients of ametropic asthenopia. Multicenter clinical trial. Asthenopia patients were chosen from eleven hospitals cross China from July, 2008 to January, 2009. The experiment was conducted asthenopia patients who used the Esculin and Digitalis glycosides Eye Drops for 4 weeks continuously. Symptoms of asthenopia, UCVA (uncorrected vision acuity), refraction, amplitude of accommodation, accommodative lag, accommodative sensitivity and positive/negative relative accommodation were measured at different time points, such as treated before, 1 week and 4 week in treated after. After the 4-week's use of Esculin and Digitalis glycosides Eye Drops, each subjective symptom of the patients was decreased significantly (F=353.30, P<0.05). In addition, most of the objective exams of accommodation ability were significantly improved, such as UCVA (left eye: F=23.39, P<0.05; right eye: F=15.62, P<0.05), refraction (left eye: F=10.34, P<0.05; right eye: F=17.13, P<0.05), amplitude of accommodation (left eye: F=14.46, P<0.05; right eye: F=8.29, P<0.05; eyes: F=13.86, P<0.05), accommodative lag (F=14.89, P<0.05) and accommodative sensitivity (left eye: F=62.67, P<0.05; right eye: F=68.77, P<0.05; eyes: F=82.74, P<0.05). And no patient appeared any adverse reaction in whole experiment. Esculin and Digitalis glycosides Eye Drops is effective and safety for use in the patients of ametropia asthenopia.

OPTICAL PRINCIPLES, BIOMECHANICS, AND INITIAL CLINICAL PERFORMANCE OF A DUAL-OPTIC ACCOMMODATING INTRAOCULAR LENS (AN AMERICAN OPHTHALMOLOGICAL SOCIETY THESIS)

PubMed Central

McLeod, Stephen D.

2006-01-01

Purpose To design and develop an accommodating intraocular lens (IOL) for endocapsular fixation with extended accommodative range that can be adapted to current standard extracapsular phacoemulsification technique. Methods Ray tracing analysis and lens design; finite element modeling of biomechanical properties; cadaver eye implantation; initial clinical evaluation. Results Ray tracing analysis indicated that a dual-optic design with a high plus-power front optic coupled to an optically compensatory minus posterior optic produced greater change in conjugation power of the eye compared to that produced by axial movement of a single-optic IOL, and that magnification effects were unlikely to account for improved near vision. Finite element modeling indicated that the two optics can be linked by spring-loaded haptics that allow anterior and posterior axial displacement of the front optic in response to changes in ciliary body tone and capsular tension. A dual-optic single-piece foldable silicone lens was constructed based on these principles. Subsequent initial clinical evaluation in 24 human eyes after phacoemulsification for cataract indicated mean 3.22 diopters of accommodation (range, 1 to 5 D) based on defocus curve measurement. Accommodative amplitude evaluation at 1- and 6-month follow-up in all eyes indicated that the accommodative range was maintained and that the lens was well tolerated. Conclusions A dual-optic design increases the accommodative effect of axial optic displacement, with minimal magnification effect. Initial clinical trials suggest that IOLs designed on this principle might provide true pseudophakic accommodation following cataract extraction and lens implantation. PMID:17471355

Employing WebGL to develop interactive stereoscopic 3D content for use in biomedical visualization

NASA Astrophysics Data System (ADS)

Johnston, Semay; Renambot, Luc; Sauter, Daniel

2013-03-01

Web Graphics Library (WebGL), the forthcoming web standard for rendering native 3D graphics in a browser, represents an important addition to the biomedical visualization toolset. It is projected to become a mainstream method of delivering 3D online content due to shrinking support for third-party plug-ins. Additionally, it provides a virtual reality (VR) experience to web users accommodated by the growing availability of stereoscopic displays (3D TV, desktop, and mobile). WebGL's value in biomedical visualization has been demonstrated by applications for interactive anatomical models, chemical and molecular visualization, and web-based volume rendering. However, a lack of instructional literature specific to the field prevents many from utilizing this technology. This project defines a WebGL design methodology for a target audience of biomedical artists with a basic understanding of web languages and 3D graphics. The methodology was informed by the development of an interactive web application depicting the anatomy and various pathologies of the human eye. The application supports several modes of stereoscopic displays for a better understanding of 3D anatomical structures.

The effect of fractal contact lenses on peripheral refraction in myopic model eyes.

PubMed

Rodriguez-Vallejo, Manuel; Benlloch, Josefa; Pons, Amparo; Monsoriu, Juan A; Furlan, Walter D

2014-12-01

To test multizone contact lenses in model eyes: Fractal Contact Lenses (FCLs), designed to induce myopic peripheral refractive error (PRE). Zemax ray-tracing software was employed to simulate myopic and accommodation-dependent model eyes fitted with FCLs. PRE, defined in terms of mean sphere M and 90°-180° astigmatism J180, was computed at different peripheral positions, ranging from 0 to 35° in steps of 5°, and for different pupil diameters (PDs). Simulated visual performance and changes in the PRE were also analyzed for contact lens decentration and model eye accommodation. For comparison purposes, the same simulations were performed with another commercially available contact lens designed for the same intended use: the Dual Focus (DF). PRE was greater with FCL than with DF when both designs were tested for a 3.5 mm PD, and with and without decentration of the lenses. However, PRE depended on PD with both multizone lenses, with a remarkable reduction of the myopic relative effect for a PD of 5.5 mm. The myopic PRE with contact lenses decreased as the myopic refractive error increased, but this could be compensated by increasing the power of treatment zones. A peripheral myopic shift was also induced by the FCLs in the accommodated model eye. In regard to visual performance, a myopia under-correction with reference to the circle of least confusion was obtained in all cases for a 5.5 mm PD. The ghost images, generated by treatment zones of FCL, were dimmer than the ones produced with DF lens of the same power. FCLs produce a peripheral myopic defocus without compromising central vision in photopic conditions. FCLs have several design parameters that can be varied to obtain optimum results: lens diameter, number of zones, addition and asphericity; resulting in a very promising customized lens for the treatment of myopia progression.

Analysis of patients with good uncorrected distance and near vision after monofocal intraocular lens implantation.

PubMed

Nanavaty, Mayank A; Vasavada, Abhay R; Patel, Anil S; Raj, Shetal M; Desai, Tejas H

2006-07-01

To analyze factors contributing to uncorrected visual acuity of at least 6/12 for distance and at least J4 for near (pseudoaccommodation) after monofocal intraocular lens (IOL) implantation. Iladevi Cataract and IOL Research Center, Ahmedabad, India. In a case-controlled study of 30 eyes (30 patients) that had phacoemulsification, those with pseudoaccommodation were assigned to cases and 30 eyes (30 patients) without pseudoaccommodation were designated as controls. Controls were matched by identical best corrected visual acuity, age, and postoperative duration. Subjective refraction was done with retinoscopy. Factors analyzed included corneal astigmatism, pupil size, axial IOL movement, amplitude of accommodation, axial length (AL), and age. Corneal astigmatism was noted on topography and interpreted as against the rule (ATR) (180 +/- 15 degrees), with the rule (WTR) (90 +/- 15 degrees), and oblique (OB) (45/135 +/- 30 degrees). Pupil size was noted on topographic display and AL and anterior chamber depth (ACD) on immersion A-scan. The axial IOL movement was calculated as the difference in ACD after instillation of cyclopentolate 1% (Cyclopent) and subsequently pilocarpine nitrate 2% (Carpinol) at separate visits, and amplitude of accommodation was measured with static and dynamic retinoscopy. Multivariate logistic regression and odds ratio with 95% confidence intervals were determined. Mean spherical equivalent was -0.45 +/- 0.63 diopter (D) in cases and -0.35 +/- 0.83 D (P = .61) in controls. Multivariate logistic regression in cases versus controls: corneal astigmatism (ATR versus WTR and OB collectively): 10.19 [1.8,57.44], P = .009; pupil size: 0.45 [0.07,2.71], P = .38; axial IOL movement: 1.39 [0.51,0.77], P = .514; amplitude of accommodation: 2.95 [0.93,9.3], P = .065; AL: 0.55 [0.29,1.02], P = .058; and age: 0.98 [0.5,1.95], P = .963. The study suggests a significant role of ATR corneal astigmatism in good uncorrected distance and near vision after monofocal IOL implantation.

The standpoint of persons with hearing loss on work disparities and workplace accommodations.

PubMed

Shaw, Lynn; Tetlaff, Britta; Jennings, Mary Beth; Southall, Kenneth E

2013-01-01

The perspectives of persons who live and work with hearing loss were sought to examine workplace accommodation challenges and strategies. A convenience sample of seven older adults with hearing loss participated in in-depth interviews. A systematic grounded theory approach informed the study design and analysis. Categories of facilitators and challenges in the data were identified through axial coding and clustering. Core categories of social processes emerged through constant comparison and theoretical sampling of the data to reveal the actions and interactions used to negotiate or implement adaptations or workplace accommodations. Persons with hearing loss use a realm of strategies to live and work with a hearing loss. Social processes used to navigate the challenges to working with hearing loss and to manage optimal work performance included: self-accommodation, self-advocacy, self-management of hearing loss, and lobbying. Success in overcoming work disparities for persons with hearing loss requires individuals to take control of identifying their needs within the workplace and at home, and to negotiate for specific accommodations. These strategies and processes draw attention to the need for a repository on contextualized workplace accommodation strategies for improving communication and hearing in the workplace. Further to this a best practice guide for use by workers, employers, and work rehabilitation and health care workers is indicated.

Development and implementation of a radiation therapy incident learning system compatible with local workflow and a national taxonomy.

PubMed

Montgomery, Logan; Fava, Palma; Freeman, Carolyn R; Hijal, Tarek; Maietta, Ciro; Parker, William; Kildea, John

2018-01-01

Collaborative incident learning initiatives in radiation therapy promise to improve and standardize the quality of care provided by participating institutions. However, the software interfaces provided with such initiatives must accommodate all participants and thus are not optimized for the workflows of individual radiation therapy centers. This article describes the development and implementation of a radiation therapy incident learning system that is optimized for a clinical workflow and uses the taxonomy of the Canadian National System for Incident Reporting - Radiation Treatment (NSIR-RT). The described incident learning system is a novel version of an open-source software called the Safety and Incident Learning System (SaILS). A needs assessment was conducted prior to development to ensure SaILS (a) was intuitive and efficient (b) met changing staff needs and (c) accommodated revisions to NSIR-RT. The core functionality of SaILS includes incident reporting, investigations, tracking, and data visualization. Postlaunch modifications of SaILS were informed by discussion and a survey of radiation therapy staff. There were 240 incidents detected and reported using SaILS in 2016 and the number of incidents per month tended to increase throughout the year. An increase in incident reporting occurred after switching to fully online incident reporting from an initial hybrid paper-electronic system. Incident templating functionality and a connection with our center's oncology information system were incorporated into the investigation interface to minimize repetitive data entry. A taskable actions feature was also incorporated to document outcomes of incident reports and has since been utilized for 36% of reported incidents. Use of SaILS and the NSIR-RT taxonomy has improved the structure of, and staff engagement with, incident learning in our center. Software and workflow modifications informed by staff feedback improved the utility of SaILS and yielded an efficient and transparent solution to categorize incidents with the NSIR-RT taxonomy. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

The concave iris in pigment dispersion syndrome.

PubMed

Liu, Lance; Ong, Ee Lin; Crowston, Jonathan

2011-01-01

To visualize the changes of the iris contour in patients with pigment dispersion syndrome after blinking, accommodation, and pharmacologic miosis using anterior segment optical coherence tomography. Observational case series. A total of 33 eyes of 20 patients with pigment dispersion syndrome. Each eye was imaged along the horizontal 0- to 180-degree meridian using the Visante Anterior Segment Imaging System (Carl Zeiss Meditec, Dublin, CA). Scans were performed at baseline and after focusing on an internal fixation target for 5 minutes, forced blinking, accommodation, and pharmacologic miosis with pilocarpine 2%. Quantitative analysis of the changes in the iris configuration. After 5 minutes of continual fixation, the iris became planar with the mean ± standard deviation curvature decreasing from 214 ± 74 μm to 67 ± 76 μm (P < 0.05). The iris remained planar in all patients with pigment dispersion syndrome after forced blinking, but the iris concavity recovered to 227 ± 113 μm (P = 0.34) and 238 ± 119 μm (P = 0.19) with the -3.0 and -6.0 diopter lenses, respectively. Pilocarpine-induced miosis caused the iris to assume a planar configuration in all subjects. This study shows that the iris in pigment dispersion syndrome assumes a planar configuration when fixating and that the concavity of the iris surface is not restored by blinking. Accommodation restored the iris concavity, suggesting that the posterior curvature of the iris in pigment dispersion syndrome is induced and probably maintained, at least in part, by accommodation. Copyright © 2011 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Comparison of vision disorders between children in mainstream and special education classes in government primary schools in Malaysia.

PubMed

Abu Bakar, Nurul Farhana; Chen, Ai-Hong; Md Noor, Abdul Rahim; Goh, Pik-Pin

2012-08-01

The visual status of children with learning disabilities has not been extensively studied. This study aimed to compare vision disorders between children in mainstream classes and those with learning disabilities attending special education classes in government primary schools in Malaysia. In this cross-sectional comparative study, 60 school children (30 from mainstream classes and 30 from special education classes) who were matched in age (6-12 years old) and ethnicity (Malay, Chinese and Indian) were examined. The subjects were recruited using non-probability convenience sampling. A complete eye examination was performed to detect three major vision disorders, namely refractive error, lag of accommodation and convergence insufficiency. The overall prevalence of refractive error, lag of accommodation and convergence insufficiency was found to be 65.0%, 43.3% and 35.2%, respectively. Convergence insufficiency (χ² = 24.073, p < 0.001) was found to be associated with children in special education classes. No association was found between refractive error and lag of accommodation (p > 0.05) with the type of classes. Children in special education classes are more likely to have convergence insufficiency compared to children in mainstream classes. Thus, vision screening programmes for children in special education classes may need to be modified.

Combined laser-ray tracing and OCT system for biometry of the crystalline lens (Conference Presentation)

NASA Astrophysics Data System (ADS)

Ruggeri, Marco; Maceo Heilman, Bianca M.; Yao, Yue; Chang, Yu-Cherng; Gonzalez, Alex; Rowaan, Cornelis; Mohamed, Ashik; Williams, Siobhan; Durkee, Heather A.; Silgado, Juan; Bernal, Andres; Arrieta-Quintero, Esdras; Ho, Arthur; Parel, Jean-Marie A.; Manns, Fabrice

2017-02-01

Age-related changes in the crystalline lens shape and refractive index gradient produce changes in dioptric power and high-order aberrations that influence the optics of the whole eye and contribute to a decrease in overall visual quality. Despite their key role, the changes in lens shape and refractive index gradient with age and accommodation and their effects on high-order aberrations are still not well understood. The goal of this project was to develop a combined laser ray tracing (LRT) and optical coherence tomography (OCT) system to measure high-order aberrations, shape and refractive index gradient in non-human primate and human lenses. A miniature motorized lens stretching system was built to enable imaging and aberrometry of the lens during simulated accommodation. A positioning system was also built to enable on- and off-axis OCT imaging and aberrometry for characterization of the peripheral defocus of the lens. We demonstrated the capability of the LRT-OCT system to produce OCT images and aberration measurements of crystalline lens with age and accommodation in vitro. In future work, the information acquired with the LRT-OCT system will be used to develop an accurate age-dependent lens model to predict the role of the lens in the development of refractive error and aberrations of the whole eye.

Feature and Region Selection for Visual Learning.

PubMed

Zhao, Ji; Wang, Liantao; Cabral, Ricardo; De la Torre, Fernando

2016-03-01

Visual learning problems, such as object classification and action recognition, are typically approached using extensions of the popular bag-of-words (BoWs) model. Despite its great success, it is unclear what visual features the BoW model is learning. Which regions in the image or video are used to discriminate among classes? Which are the most discriminative visual words? Answering these questions is fundamental for understanding existing BoW models and inspiring better models for visual recognition. To answer these questions, this paper presents a method for feature selection and region selection in the visual BoW model. This allows for an intermediate visualization of the features and regions that are important for visual learning. The main idea is to assign latent weights to the features or regions, and jointly optimize these latent variables with the parameters of a classifier (e.g., support vector machine). There are four main benefits of our approach: 1) our approach accommodates non-linear additive kernels, such as the popular χ(2) and intersection kernel; 2) our approach is able to handle both regions in images and spatio-temporal regions in videos in a unified way; 3) the feature selection problem is convex, and both problems can be solved using a scalable reduced gradient method; and 4) we point out strong connections with multiple kernel learning and multiple instance learning approaches. Experimental results in the PASCAL VOC 2007, MSR Action Dataset II and YouTube illustrate the benefits of our approach.

[The relationship between accommodative accuracy at different near-work distances and early-onset myopia].

PubMed

Yu, Q W; Zhang, P; Zhou, S B; Hu, Y; Ji, M X; Luo, Y C; You, H L; Yao, Z X

2016-07-01

To observe the accommodative accuracy of children with early-onset myopia at different near-work distances, and discuss the relationship between accommodative accuracy and early-onset myopia. This was a case-control study. Thirty-seven emmetropic children, 41 early-onset myopic children without correction, and 39 early-onset myopic children with spectacles, aged 7 to 13 years, were included. Measures of refractive errors and accommodative accuracy at four near-work distances, including 50 cm, 40 cm, 30 cm, and 20 cm, were made using the binocular fusion cross cylinder (FCC) of an automatic phoropter. Most candidates showed accommodative lags, including the children with emmetropia. The ratio of lags in all candidates at different near-work distances was 75.21% (50 cm), 87.18% (40 cm), 92.31% (30 cm), and 98.29% (20 cm), respectively. All accommodative accuracies became worse, and the accommodative lag ratio and values of FCC increased, along with the shortening of the distance. The difference in accommodative accuracy among groups was statistically significant at 30 cm (χ(2)=7.852, P= 0.020) and 20 cm (χ(2)=6.480, P=0.039). The values of FCC among groups were significantly different at 30 cm (F=3.626, P=0.030) and 20 cm (F=3.703, P=0.028), but not at 50 cm and 40 cm (P>0.05). In addition, the FCC values of 30 cm and 20 cm had a statistically significant difference between myopic children without correction [(1.25±0.44) D and (1.76±0.43) D] and emmetropic children [(0.95±0.52) D and (1.41±0.58) D] (P=0.012, 0.008). The correlation between diopters of myopia and accommodative accuracy at different nearwork distances was not statistically significant (P>0.05). However, the correlation between diopters of myopia and the accommodative lag value (FCC) at 20 cm was statistically significant (r=0.246, P=0.028). The closer the near-work distance is, the worse the accommodative accuracy is. This is more significant in early-onset myopia, especially myopia without correction, than emmetropia. Wearing spectacles may improve the threshold and sensitivity of accommodations, and the accommodative accuracy at near-work distances (<30 cm) to some extent. The poor accommodative accuracy at near-work distances may be not related to early-onset myopia, but the value of FCC (20 cm) is related to early-onset myopia. The higher the FCC value is, the higher the diopter is. (Chin J Ophthalmol, 2016, 52: 520-524).

The Effects of Fatigue on Position Determination and Cognitive Workload Using a Visual and 3-Dimensional Auditory Display

DTIC Science & Technology

2004-06-01

in first third of the night. REM sleep is associated with an extremely active brain that is frequently dreaming with bursts of rapid eye movement...these areas. 3. Human Sleep and Fatigue Sleep is nature’s process of resting the body although brain activity continues throughout the rest...midday roughly between 1500 and 1700 (LeClair, 2001). Disruption of one’s circadian rhythm to accommodate adjustments in unconventional working hours

Sparsening Filter Design for Iterative Soft-Input Soft-Output Detectors

DTIC Science & Technology

2012-02-29

filter/detector structure. Since the BP detector itself is unaltered from [1], it can accommodate a system employing channel codes such as LDPC encoding...considered in [1], or can readily be extended to the MIMO case with, for example, space-time coding as in [2,8]. Since our focus is on the design of...simplex method of [15], since it was already available in Matlab , via the “fminsearch” function. 6 Cost surfaces To visualize the cost surfaces, consider

The Lens Capsule

PubMed Central

Danysh, Brian P.; Duncan, Melinda K.

2009-01-01

The lens capsule is a modified basement membrane that completely surrounds the ocular lens. It is known that this extracellular matrix is important for both the structure and biomechanics of the lens in addition to providing informational cues to maintain lens cell phenotype. This review covers the development and structure of the lens capsule, lens diseases associated with mutations in extracellular matrix genes and the role of the capsule in lens function including those proposed for visual accommodation, selective permeability to infectious agents, and cell signaling. PMID:18773892

Comparison of Objective and Subjective Changes Induced by Multiple-Pinhole Glasses and Single-Pinhole Glasses

PubMed Central

2017-01-01

Multiple-pinhole (MPH) glasses are currently sold in many countries with unproven advertisements; however, their objective and subjective effects have not been investigated. Therefore, to investigate the effects of MPH glasses excluding the single-pinhole (SPH) effect, we compared the visual functional changes, reading speed, and ocular discomfort after reading caused by MPH and SPH glasses. Healthy 36 participants with a mean age of 33.1 years underwent examinations of pupil size, visual acuity (VA), depth of focus (DOF), and near point accommodation (NPA); tests for visual field (VF), contrast sensitivity (CS), stereopsis, and reading speed; and a survey of ocular discomfort after reading. Both types of pinhole glasses enlarged pupil diameter and improved VA, DOF, and NPA. However, CS, stereopsis, and VF parameters deteriorated. In comparison with SPH glasses, MPH glasses induced smaller pupil dilation (5.3 and 5.9 mm, P < 0.001) and showed better VF parameters with preserved peripheral VF. However, no significant difference was observed for VA, DOF, NPA, stereopsis, and CS. Reading speed using pinhole glasses was significantly slower than baseline; SPH glasses showed the slowest reading speed. Both types of glasses caused significant ocular discomfort after reading compared with baseline, and symptoms were worst with MPH glasses. In conclusion, both types of pinhole glasses had positive effects due to the pinhole effect; however, they had negative effects on VF, CS, stereopsis, reading speed, and ocular discomfort. In spite of the increased luminance and preserved peripheral VF with MPHs, these glasses caused more severe ocular discomfort than SPH glasses. This clinical trial was registered at www.ClinicalTrials.gov (Identifier: NCT02572544). PMID:28378561

Juvenile myopia progression, risk factors and interventions.

PubMed

Myrowitz, Elliott H

2012-07-01

The development and progression of early onset myopia is actively being investigated. While myopia is often considered a benign condition it should be considered a public health problem for its visual, quality of life, and economic consequences. Nearly half of the visually impaired population in the world has uncorrected refractive errors, with myopia a high percent of that group. Uncorrected visual acuity should be screened for and treated in order to improve academic performance, career opportunities and socio-economic status. Genetic and environmental factors contribute to the onset and progression of myopia. Twin studies have supported genetic factors and research continues to identify myopia genetic loci. While multiple myopia genetic loci have been identified establishing myopia as a common complex disorder, there is not yet a genetic model explaining myopia progression in populations. Environmental factors include near work, education levels, urban compared to rural location, and time spent outdoors. In this field of study where there continues to be etiology controversies, there is recent agreement that children who spend more time outdoors are less likely to become myopic. Worldwide population studies, some completed and some in progress, with a common protocol are gathering both genetic and environmental cohort data of great value. There have been rapid population changes in prevalence rates supporting an environmental influence. Interventions to prevent juvenile myopia progression include pharmacologic agents, glasses and contact lenses. Pharmacological interventions over 1-2 year trials have shown benefits. Peripheral vision defocus has been found to affect the emmetropization process and may be affected by wearing glasses or contacts. Accommodation accuracy also has been implicated in myopia progression. Further research will aim to assess both the role and interaction of environmental influences and genetic factors.

An examination of the impact of care giving styles (accommodation and skilful communication and support) on the one year outcome of adolescent anorexia nervosa: Testing the assumptions of the cognitive interpersonal model in anorexia nervosa.

PubMed

Salerno, Laura; Rhind, Charlotte; Hibbs, Rebecca; Micali, Nadia; Schmidt, Ulrike; Gowers, Simon; Macdonald, Pamela; Goddard, Elizabeth; Todd, Gillian; Lo Coco, Gianluca; Treasure, Janet

2016-02-01

The cognitive interpersonal model predicts that parental caregiving style will impact on the rate of improvement of anorexia nervosa symptoms. The study aims to examine whether the absolute levels and the relative congruence between mothers' and fathers' care giving styles influenced the rate of change of their children's symptoms of anorexia nervosa over 12 months. Triads (n=54) consisting of patients with anorexia nervosa and both of their parents were included in the study. Caregivers completed the Caregiver Skills scale and the Accommodation and Enabling Scale at intake. Patients completed the Short Evaluation of Eating Disorders at intake and at monthly intervals for one year. Polynomial Hierarchical Linear Modeling was used for the analysis. There is a person/dose dependant relationship between accommodation and patients' outcome, i.e. when both mother and father are highly accommodating outcome is poor, if either is highly accommodating outcome is intermediate and if both parents are low on accommodation outcome is good. Outcome is also good if both parents or mother alone have high levels of carer skills and poor if both have low levels of skills. Including only a sub-sample of an adolescent clinical population; not considering time spent care giving, and reporting patient's self-reported outcome data limits the generalisability of the current findings. Accommodating and enabling behaviours by family members can serve to maintain eating disorder behaviours. However, skilful behaviours particularly by mothers, can aid recovery. Clinical interventions to optimise care giving skills and to reduce accommodation by both parents may be an important addition to treatment for anorexia nervosa. Copyright © 2015 Elsevier B.V. All rights reserved.

The design of 3D scaffold for tissue engineering using automated scaffold design algorithm.

PubMed

Mahmoud, Shahenda; Eldeib, Ayman; Samy, Sherif

2015-06-01

Several progresses have been introduced in the field of bone regenerative medicine. A new term tissue engineering (TE) was created. In TE, a highly porous artificial extracellular matrix or scaffold is required to accommodate cells and guide their growth in three dimensions. The design of scaffolds with desirable internal and external structure represents a challenge for TE. In this paper, we introduce a new method known as automated scaffold design (ASD) for designing a 3D scaffold with a minimum mismatches for its geometrical parameters. The method makes use of k-means clustering algorithm to separate the different tissues and hence decodes the defected bone portions. The segmented portions of different slices are registered to construct the 3D volume for the data. It also uses an isosurface rendering technique for 3D visualization of the scaffold and bones. It provides the ability to visualize the transplanted as well as the normal bone portions. The proposed system proves good performance in both the segmentation results and visualizations aspects.

Neuronal integration in visual cortex elevates face category tuning to conscious face perception

PubMed Central

Fahrenfort, Johannes J.; Snijders, Tineke M.; Heinen, Klaartje; van Gaal, Simon; Scholte, H. Steven; Lamme, Victor A. F.

2012-01-01

The human brain has the extraordinary capability to transform cluttered sensory input into distinct object representations. For example, it is able to rapidly and seemingly without effort detect object categories in complex natural scenes. Surprisingly, category tuning is not sufficient to achieve conscious recognition of objects. What neural process beyond category extraction might elevate neural representations to the level where objects are consciously perceived? Here we show that visible and invisible faces produce similar category-selective responses in the ventral visual cortex. The pattern of neural activity evoked by visible faces could be used to decode the presence of invisible faces and vice versa. However, only visible faces caused extensive response enhancements and changes in neural oscillatory synchronization, as well as increased functional connectivity between higher and lower visual areas. We conclude that conscious face perception is more tightly linked to neural processes of sustained information integration and binding than to processes accommodating face category tuning. PMID:23236162

Measuring visual discomfort associated with 3D displays

NASA Astrophysics Data System (ADS)

Lambooij, M.; Fortuin, M.; Ijsselsteijn, W. A.; Heynderickx, I.

2009-02-01

Some people report visual discomfort when watching 3D displays. For both the objective measurement of visual fatigue and the subjective measurement of visual discomfort, we would like to arrive at general indicators that are easy to apply in perception experiments. Previous research yielded contradictory results concerning such indicators. We hypothesize two potential causes for this: 1) not all clinical tests are equally appropriate to evaluate the effect of stereoscopic viewing on visual fatigue, and 2) there is a natural variation in susceptibility to visual fatigue amongst people with normal vision. To verify these hypotheses, we designed an experiment, consisting of two parts. Firstly, an optometric screening was used to differentiate participants in susceptibility to visual fatigue. Secondly, in a 2×2 within-subjects design (2D vs 3D and two-view vs nine-view display), a questionnaire and eight optometric tests (i.e. binocular acuity, fixation disparity with and without fusion lock, heterophoria, convergent and divergent fusion, vergence facility and accommodation response) were administered before and immediately after a reading task. Results revealed that participants found to be more susceptible to visual fatigue during screening showed a clinically meaningful increase in fusion amplitude after having viewed 3D stimuli. Two questionnaire items (i.e., pain and irritation) were significantly affected by the participants' susceptibility, while two other items (i.e., double vision and sharpness) were scored differently between 2D and 3D for all participants. Our results suggest that a combination of fusion range measurements and self-report is appropriate for evaluating visual fatigue related to 3D displays.

A framework for improved safety and accessibility through pedestrian guidance and navigation.

DOT National Transportation Integrated Search

2015-07-01

With the changes in America's demographics comes a need to provide improved accommodation of individuals : with reduced capabilities. To date, our research has focused upon assistive pedestrian signal technologies for : pedestrians with impaired visi...

A cognitive task analysis of a visual analytic workflow: Exploring molecular interaction networks in systems biology.

PubMed

Mirel, Barbara; Eichinger, Felix; Keller, Benjamin J; Kretzler, Matthias

2011-03-21

Bioinformatics visualization tools are often not robust enough to support biomedical specialists’ complex exploratory analyses. Tools need to accommodate the workflows that scientists actually perform for specific translational research questions. To understand and model one of these workflows, we conducted a case-based, cognitive task analysis of a biomedical specialist’s exploratory workflow for the question: What functional interactions among gene products of high throughput expression data suggest previously unknown mechanisms of a disease? From our cognitive task analysis four complementary representations of the targeted workflow were developed. They include: usage scenarios, flow diagrams, a cognitive task taxonomy, and a mapping between cognitive tasks and user-centered visualization requirements. The representations capture the flows of cognitive tasks that led a biomedical specialist to inferences critical to hypothesizing. We created representations at levels of detail that could strategically guide visualization development, and we confirmed this by making a trial prototype based on user requirements for a small portion of the workflow. Our results imply that visualizations should make available to scientific users “bundles of features” consonant with the compositional cognitive tasks purposefully enacted at specific points in the workflow. We also highlight certain aspects of visualizations that: (a) need more built-in flexibility; (b) are critical for negotiating meaning; and (c) are necessary for essential metacognitive support.

A Software Developer’s Guide to Informal Evaluation of Visual Analytics Environments Using VAST Challenge Information

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

Cook, Kristin A.; Scholtz, Jean; Whiting, Mark A.

The VAST Challenge has been a popular venue for academic and industry participants for over ten years. Many participants comment that the majority of their time in preparing VAST Challenge entries is discovering elements in their software environments that need to be redesigned in order to solve the given task. Fortunately, there is no need to wait until the VAST Challenge is announced to test out software systems. The Visual Analytics Benchmark Repository contains all past VAST Challenge tasks, data, solutions and submissions. This paper details the various types of evaluations that may be conducted using the Repository information. Inmore » this paper we describe how developers can do informal evaluations of various aspects of their visual analytics environments using VAST Challenge information. Aspects that can be evaluated include the appropriateness of the software for various tasks, the various data types and formats that can be accommodated, the effectiveness and efficiency of the process supported by the software, and the intuitiveness of the visualizations and interactions. Researchers can compare their visualizations and interactions to those submitted to determine novelty. In addition, the paper provides pointers to various guidelines that software teams can use to evaluate the usability of their software. While these evaluations are not a replacement for formal evaluation methods, this information can be extremely useful during the development of visual analytics environments.« less

The Edge-Disjoint Path Problem on Random Graphs by Message-Passing.

PubMed

Altarelli, Fabrizio; Braunstein, Alfredo; Dall'Asta, Luca; De Bacco, Caterina; Franz, Silvio

2015-01-01

We present a message-passing algorithm to solve a series of edge-disjoint path problems on graphs based on the zero-temperature cavity equations. Edge-disjoint paths problems are important in the general context of routing, that can be defined by incorporating under a unique framework both traffic optimization and total path length minimization. The computation of the cavity equations can be performed efficiently by exploiting a mapping of a generalized edge-disjoint path problem on a star graph onto a weighted maximum matching problem. We perform extensive numerical simulations on random graphs of various types to test the performance both in terms of path length minimization and maximization of the number of accommodated paths. In addition, we test the performance on benchmark instances on various graphs by comparison with state-of-the-art algorithms and results found in the literature. Our message-passing algorithm always outperforms the others in terms of the number of accommodated paths when considering non trivial instances (otherwise it gives the same trivial results). Remarkably, the largest improvement in performance with respect to the other methods employed is found in the case of benchmarks with meshes, where the validity hypothesis behind message-passing is expected to worsen. In these cases, even though the exact message-passing equations do not converge, by introducing a reinforcement parameter to force convergence towards a sub optimal solution, we were able to always outperform the other algorithms with a peak of 27% performance improvement in terms of accommodated paths. On random graphs, we numerically observe two separated regimes: one in which all paths can be accommodated and one in which this is not possible. We also investigate the behavior of both the number of paths to be accommodated and their minimum total length.

The Edge-Disjoint Path Problem on Random Graphs by Message-Passing

PubMed Central

2015-01-01

We present a message-passing algorithm to solve a series of edge-disjoint path problems on graphs based on the zero-temperature cavity equations. Edge-disjoint paths problems are important in the general context of routing, that can be defined by incorporating under a unique framework both traffic optimization and total path length minimization. The computation of the cavity equations can be performed efficiently by exploiting a mapping of a generalized edge-disjoint path problem on a star graph onto a weighted maximum matching problem. We perform extensive numerical simulations on random graphs of various types to test the performance both in terms of path length minimization and maximization of the number of accommodated paths. In addition, we test the performance on benchmark instances on various graphs by comparison with state-of-the-art algorithms and results found in the literature. Our message-passing algorithm always outperforms the others in terms of the number of accommodated paths when considering non trivial instances (otherwise it gives the same trivial results). Remarkably, the largest improvement in performance with respect to the other methods employed is found in the case of benchmarks with meshes, where the validity hypothesis behind message-passing is expected to worsen. In these cases, even though the exact message-passing equations do not converge, by introducing a reinforcement parameter to force convergence towards a sub optimal solution, we were able to always outperform the other algorithms with a peak of 27% performance improvement in terms of accommodated paths. On random graphs, we numerically observe two separated regimes: one in which all paths can be accommodated and one in which this is not possible. We also investigate the behavior of both the number of paths to be accommodated and their minimum total length. PMID:26710102

Postactivation Potentation Effects From Accommodating Resistance Combined With Heavy Back Squats on Short Sprint Performance.

PubMed

Wyland, Timothy P; Van Dorin, Joshua D; Reyes, G Francis Cisco

2015-11-01

Applying accommodating resistance combined with isoinertial resistance has been demonstrated to be effective in improving neuromuscular attributes important for sport performance. The main purpose of this study was to determine whether short sprints can be acutely enhanced after several sets of back squats with or without accommodating resistance. Twenty recreationally resistance-trained males (age: 23.3 ± 4.4 years; height: 178.9 ± 6.5 cm; weight: 88.3 ± 10.8 kg) performed pre-post testing on 9.1-m sprint time. Three different interventions were implemented in randomized order between pre-post 9.1-m sprints. On 3 separate days, subjects either sat for 5 minutes (CTRL), performed 5 sets of 3 repetitions at 85% of their 1 repetition maximum (1RM) with isoinertial load (STND), or performed 5 sets of 3 repetitions at 85% of their 1RM, with 30% of the total resistance coming from elastic band tension (BAND) between pre-post 9.1-m sprint testing. Posttesting for 9.1-m sprint time occurred immediately after the last set of squats (Post-Immediate) and on every minute for 4 minutes after the last set of squats (Post-1min, Post-2min, Post-3min, and Post-4min). Repeated-measures analysis of variance statistical analyses revealed no significant changes in sprint time across posttesting times during the CTRL and STND condition. During the BAND condition, sprint time significantly decreased from Post-Immediate to Post-4min (p = 0.002). The uniqueness of accommodating resistance could create an optimal postactivation potentiation effect to increase neuromuscular performance. Coaches and athletes can implement heavy accommodating resistance exercises to their warm-up when improving acute sprint time is desired.

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

Cook, Kris A.; Scholtz, Jean; Whiting, Mark A.

The VAST Challenge has been a popular venue for academic and industry participants for over ten years. Many participants comment that the majority of their time in preparing VAST Challenge entries is discovering elements in their software environments that need to be redesigned in order to solve the given task. Fortunately, there is no need to wait until the VAST Challenge is announced to test out software systems. The Visual Analytics Benchmark Repository contains all past VAST Challenge tasks, data, solutions and submissions. This paper details the various types of evaluations that may be conducted using the Repository information. Inmore » this paper we describe how developers can do informal evaluations of various aspects of their visual analytics environments using VAST Challenge information. Aspects that can be evaluated include the appropriateness of the software for various tasks, the various data types and formats that can be accommodated, the effectiveness and efficiency of the process supported by the software, and the intuitiveness of the visualizations and interactions. Researchers can compare their visualizations and interactions to those submitted to determine novelty. In addition, the paper provides pointers to various guidelines that software teams can use to evaluate the usability of their software. While these evaluations are not a replacement for formal evaluation methods, this information can be extremely useful during the development of visual analytics environments.« less

Unconscious Imagination and the Mental Imagery Debate

PubMed Central

Brogaard, Berit; Gatzia, Dimitria Electra

2017-01-01

Traditionally, philosophers have appealed to the phenomenological similarity between visual experience and visual imagery to support the hypothesis that there is significant overlap between the perceptual and imaginative domains. The current evidence, however, is inconclusive: while evidence from transcranial brain stimulation seems to support this conclusion, neurophysiological evidence from brain lesion studies (e.g., from patients with brain lesions resulting in a loss of mental imagery but not a corresponding loss of perception and vice versa) indicates that there are functional and anatomical dissociations between mental imagery and perception. Assuming that the mental imagery and perception do not overlap, at least, to the extent traditionally assumed, then the question arises as to what exactly mental imagery is and whether it parallels perception by proceeding via several functionally distinct mechanisms. In this review, we argue that even though there may not be a shared mechanism underlying vision for perception and conscious imagery, there is an overlap between the mechanisms underlying vision for action and unconscious visual imagery. On the basis of these findings, we propose a modification of Kosslyn’s model of imagery that accommodates unconscious imagination and explore possible explanations of the quasi-pictorial phenomenology of conscious visual imagery in light of the fact that its underlying neural substrates and mechanisms typically are distinct from those of visual experience. PMID:28588527

Visual flow scene effects on the somatogravic illusion in non-pilots.

PubMed

Eriksson, Lars; von Hofsten, Claes; Tribukait, Arne; Eiken, Ola; Andersson, Peter; Hedström, Johan

2008-09-01

The somatogravic illusion (SGI) is easily broken when the pilot looks out the aircraft window during daylight flight, but it has proven difficult to break or even reduce the SGI in non-pilots in simulators using synthetic visual scenes. Could visual-flow scenes that accommodate compensatory head movement reduce the SGI in naive subjects? We investigated the effects of visual cues on the SGI induced by a human centrifuge. The subject was equipped with a head-tracked, head-mounted display (HMD) and was seated in a fixed gondola facing the center of rotation. The angular velocity of the centrifuge increased from near zero until a 0.57-G centripetal acceleration was attained, resulting in a tilt of the gravitoinertial force vector, corresponding to a pitch-up of 30 degrees. The subject indicated perceived horizontal continuously by means of a manual adjustable-plate system. We performed two experiments with within-subjects designs. In Experiment 1, the subjects (N = 13) viewed a darkened HMD and a presentation of simple visual flow beneath a horizon. In Experiment 2, the subjects (N = 12) viewed a darkened HMD, a scene including symbology superimposed on simple visual flow and horizon, and this scene without visual flow (static). In Experiment 1, visual flow reduced the SGI from 12.4 +/- 1.4 degrees (mean +/- SE) to 8.7 +/- 1.5 degrees. In Experiment 2, the SGI was smaller in the visual flow condition (9.3 +/- 1.8 degrees) than with the static scene (13.3 +/- 1.7 degrees) and without HMD presentation (14.5 +/- 2.3 degrees), respectively. It is possible to reduce the SGI in non-pilots by means of a synthetic horizon and simple visual flow conveyed by a head-tracked HMD. This may reflect the power of a more intuitive display for reducing the SGI.

Reduced vergence adaptation is associated with a prolonged output of convergence accommodation in convergence insufficiency.

PubMed

Sreenivasan, Vidhyapriya; Bobier, William R

2014-07-01

Convergence insufficiency (CI) is a developmental visual anomaly defined clinically by a reduced near point of convergence, a reduced capacity to view through base-out prisms (fusional convergence); coupled with asthenopic symptoms typically blur and diplopia. Experimental studies show reduced vergence parameters and tonic adaptation. Based upon current models of accommodation and vergence, we hypothesize that the reduced vergence adaptation in CI leads to excessive amounts of convergence accommodation (CA). Eleven CI participants (mean age=17.4±2.3 years) were recruited with reduced capacity to view through increasing magnitudes of base out (BO) prisms (mean fusional convergence at 40 cm=12±0.9Δ). Testing followed our previous experimental design for (n=11) binocularly normal adults. Binocular fixation of a difference of Gaussian (DoG) target (0.2 cpd) elicited CA responses during vergence adaptation to a 12Δ BO. Vergence and CA responses were obtained at 3 min intervals over a 15 min period and time course were quantified using exponential decay functions. Results were compared to previously published data on eleven binocular normals. Eight participants completed the study. CI's showed significantly reduced magnitude of vergence adaptation (CI: 2.9Δ vs. normals: 6.6Δ; p=0.01) and CA reduction (CI=0.21 D, Normals=0.55 D; p=0.03). However, the decay time constants for adaptation and CA responses were not significantly different. CA changes were not confounded by changes in tonic accommodation (Change in TA=0.01±0.2D; p=0.8). The reduced magnitude of vergence adaptation found in CI patients resulting in higher levels of CA may potentially explain their clinical findings of reduced positive fusional vergence (PFV) and the common symptom of blur. Copyright © 2014 Elsevier B.V. All rights reserved.

Effectiveness of Placebo Therapy for Maintaining Masking in a Clinical Trial of Vergence/Accommodative Therapy

PubMed Central

Kulp, Marjean; Mitchell, G. Lynn; Borsting, Eric; Scheiman, Mitchell; Cotter, Susan; Rouse, Michael; Tamkins, Susanna; Mohney, Brian G.; Toole, Andrew; Reuter, Kathleen

2009-01-01

Purpose To evaluate the effectiveness of the Convergence Insufficiency Treatment Trial (CITT) placebo therapy program in maintaining masking of patients randomized to the office-based treatment arms, determine whether demographic variables affect masking, and determine whether perception of assigned treatment group was associated with treatment outcome or adherence to treatment. Methods Patients (n = 221, ages, 9–17 years) were randomized to one of four treatment groups, two of which were office-based and masked to treatment (n = 114). The placebo therapy program was designed to appear to be real vergence/accommodative therapy, without stimulating vergence, accommodation, or fine saccades (beyond levels of daily visual activities). After treatment, patients in the office-based groups were asked whether they thought they had received real or placebo therapy and how confident they were in their answers. Results Ninety-three percent of patients assigned to real therapy and 85% assigned to placebo therapy thought they were in the real therapy group (P = 0.17). No significant differences were found between the two groups in adherence to the therapy (P ≥ 0.22 for all comparisons). The percentage of patients who thought they were assigned to real therapy did not differ by age, sex, race, or ethnicity (P > 0.30 for all comparisons). No association was found between patients' perception of group assignment and symptoms or signs at outcome (P ≥ 0.38 for all comparisons). Conclusions The CITT placebo therapy program was effective in maintaining patient masking in this study and therefore may have potential for use in future clinical trials using vergence/accommodative therapy. Masking was not affected by demographic variables. Perception of group assignment was not related to symptoms or signs at outcome (ClinicalTrials.gov number, NCT00338611). PMID:19151384

Cretaceous to present kinematics of the Indian, African and Seychelles plates

NASA Astrophysics Data System (ADS)

Eagles, Graeme; Hoang, Ha H.

2014-01-01

An iterative inverse model of seafloor spreading data from the Mascarene and Madagascar basins and the flanks of the Carlsberg Ridge describes a continuous history of Indian-African Plate divergence since 84 Ma. Visual-fit modelling of conjugate magnetic anomaly data from near the Seychelles platform and Laxmi Ridge documents rapid rotation of a Seychelles Plate about a nearby Euler pole in Palaeocene times. As the Euler pole migrated during this rotation, the Amirante Trench on the western side of the plate accommodated first convergence and later divergence with the African Plate. The unusual present-day morphology of the Amirante Trench and neighbouring Amirante Banks can be related to crustal thickening by thrusting and folding during the convergent phase and the subsequent development of a spreading centre with a median valley during the divergent phase. The model fits FZ trends in the north Arabian and east Somali basins, suggesting that they formed in India-Africa Plate divergence. Seafloor fabric in and between the basins shows that they initially hosted a segmented spreading ridge that accommodated slow plate divergence until 71-69 Ma, and that upon arrival of the Deccan-Réunion plume and an increase to faster plate divergence rates in the period 69-65 Ma, segments of the ridge lengthened and propagated. Ridge propagation into the Indian continental margin led first to the formation of the Laxmi Basin, which accompanied extensive volcanism onshore at the Deccan Traps and offshore at the Saurashtra High and Somnath Ridge. A second propagation episode initiated the ancestral Carlsberg Ridge at which Seychelles-India and India-Africa Plate motions were accommodated. With the completion of this propagation, the plate boundaries in the Mascarene Basin were abandoned. Seafloor spreading between this time and the present has been accommodated solely at the Carlsberg Ridge.

Recent improvements to Binding MOAD: a resource for protein–ligand binding affinities and structures

PubMed Central

Ahmed, Aqeel; Smith, Richard D.; Clark, Jordan J.; Dunbar, James B.; Carlson, Heather A.

2015-01-01

For over 10 years, Binding MOAD (Mother of All Databases; http://www.BindingMOAD.org) has been one of the largest resources for high-quality protein–ligand complexes and associated binding affinity data. Binding MOAD has grown at the rate of 1994 complexes per year, on average. Currently, it contains 23 269 complexes and 8156 binding affinities. Our annual updates curate the data using a semi-automated literature search of the references cited within the PDB file, and we have recently upgraded our website and added new features and functionalities to better serve Binding MOAD users. In order to eliminate the legacy application server of the old platform and to accommodate new changes, the website has been completely rewritten in the LAMP (Linux, Apache, MySQL and PHP) environment. The improved user interface incorporates current third-party plugins for better visualization of protein and ligand molecules, and it provides features like sorting, filtering and filtered downloads. In addition to the field-based searching, Binding MOAD now can be searched by structural queries based on the ligand. In order to remove redundancy, Binding MOAD records are clustered in different families based on 90% sequence identity. The new Binding MOAD, with the upgraded platform, features and functionalities, is now equipped to better serve its users. PMID:25378330

SimGraph: A Flight Simulation Data Visualization Workstation

NASA Technical Reports Server (NTRS)

Kaplan, Joseph A.; Kenney, Patrick S.

1997-01-01

Today's modern flight simulation research produces vast amounts of time sensitive data, making a qualitative analysis of the data difficult while it remains in a numerical representation. Therefore, a method of merging related data together and presenting it to the user in a more comprehensible format is necessary. Simulation Graphics (SimGraph) is an object-oriented data visualization software package that presents simulation data in animated graphical displays for easy interpretation. Data produced from a flight simulation is presented by SimGraph in several different formats, including: 3-Dimensional Views, Cockpit Control Views, Heads-Up Displays, Strip Charts, and Status Indicators. SimGraph can accommodate the addition of new graphical displays to allow the software to be customized to each user s particular environment. A new display can be developed and added to SimGraph without having to design a new application, allowing the graphics programmer to focus on the development of the graphical display. The SimGraph framework can be reused for a wide variety of visualization tasks. Although it was created for the flight simulation facilities at NASA Langley Research Center, SimGraph can be reconfigured to almost any data visualization environment. This paper describes the capabilities and operations of SimGraph.

Visual function in patients followed at a Veterans Affairs polytrauma network site: an electronic medical record review.

PubMed

Stelmack, Joan A; Frith, Theresa; Van Koevering, Denise; Rinne, Stephen; Stelmack, Thomas R

2009-08-01

This observational study describes the "Polytrauma System of Care" used by the Veterans Health Administration to guide medical care and rehabilitation of injured military personnel serving in Operation Enduring Freedom (OEF) and Operation Iraqi Freedom (OIF) and reports the visual function of patients with polytrauma and/or traumatic brain injury (TBI) at the Hines, Illinois, Polytrauma Network Site (PNS). A retrospective medical record review was performed for 103 patients with polytrauma seen at the Hines PNS from October 2005 through March 2008 and 88 patients with TBI seen in the Hines TBI Clinic from December 2007 through March 2008. Visual symptoms were self-reported by 76% of patients with polytrauma and 75% of the patients with TBI. Problems with reading (polytrauma 60% and TBI 50%) and accommodation (polytrauma 30% and TBI 47%) were frequently found on eye examinations. Spectacles were the treatment most frequently prescribed (polytrauma 62% and TBI 78%). It is important for optometrists to be aware of the high rates of self-reported symptoms and visual problems in military personnel returning from deployment to the wars in Iraq and Afghanistan. Post-traumatic stress disorder and depression may complicate optometric evaluation and management.

Advanced detection, isolation and accommodation of sensor failures: Real-time evaluation

NASA Technical Reports Server (NTRS)

Merrill, Walter C.; Delaat, John C.; Bruton, William M.

1987-01-01

The objective of the Advanced Detection, Isolation, and Accommodation (ADIA) Program is to improve the overall demonstrated reliability of digital electronic control systems for turbine engines by using analytical redundacy to detect sensor failures. The results of a real time hybrid computer evaluation of the ADIA algorithm are presented. Minimum detectable levels of sensor failures for an F100 engine control system are determined. Also included are details about the microprocessor implementation of the algorithm as well as a description of the algorithm itself.

A real-time simulation evaluation of an advanced detection. Isolation and accommodation algorithm for sensor failures in turbine engines

NASA Technical Reports Server (NTRS)

Merrill, W. C.; Delaat, J. C.

1986-01-01

An advanced sensor failure detection, isolation, and accommodation (ADIA) algorithm has been developed for use with an aircraft turbofan engine control system. In a previous paper the authors described the ADIA algorithm and its real-time implementation. Subsequent improvements made to the algorithm and implementation are discussed, and the results of an evaluation presented. The evaluation used a real-time, hybrid computer simulation of an F100 turbofan engine.

Understanding and preventing computer vision syndrome.

PubMed

Loh, Ky; Redd, Sc

2008-01-01

The invention of computer and advancement in information technology has revolutionized and benefited the society but at the same time has caused symptoms related to its usage such as ocular sprain, irritation, redness, dryness, blurred vision and double vision. This cluster of symptoms is known as computer vision syndrome which is characterized by the visual symptoms which result from interaction with computer display or its environment. Three major mechanisms that lead to computer vision syndrome are extraocular mechanism, accommodative mechanism and ocular surface mechanism. The visual effects of the computer such as brightness, resolution, glare and quality all are known factors that contribute to computer vision syndrome. Prevention is the most important strategy in managing computer vision syndrome. Modification in the ergonomics of the working environment, patient education and proper eye care are crucial in managing computer vision syndrome.

GiPSi:a framework for open source/open architecture software development for organ-level surgical simulation.

PubMed

Cavuşoğlu, M Cenk; Göktekin, Tolga G; Tendick, Frank

2006-04-01

This paper presents the architectural details of an evolving open source/open architecture software framework for developing organ-level surgical simulations. Our goal is to facilitate shared development of reusable models, to accommodate heterogeneous models of computation, and to provide a framework for interfacing multiple heterogeneous models. The framework provides an application programming interface for interfacing dynamic models defined over spatial domains. It is specifically designed to be independent of the specifics of the modeling methods used, and therefore facilitates seamless integration of heterogeneous models and processes. Furthermore, each model has separate geometries for visualization, simulation, and interfacing, allowing the model developer to choose the most natural geometric representation for each case. Input/output interfaces for visualization and haptics for real-time interactive applications have also been provided.

Refined Synthesis and Characterization of Controlled Diameter, Narrow Size Distribution Microparticles for Aerospace Research Applications

NASA Technical Reports Server (NTRS)

Tiemsin, Pacita I.; Wohl, Christopher J.

2012-01-01

Flow visualization using polystyrene microspheres (PSL)s has enabled researchers to learn a tremendous amount of information via particle based diagnostic techniques. To better accommodate wind tunnel researchers needs, PSL synthesis via dispersion polymerization has been carried out at NASA Langley Research Center since the late 1980s. When utilizing seed material for flow visualization, size and size distribution are of paramount importance. Therefore, the work described here focused on further refinement of PSL synthesis and characterization. Through controlled variation of synthetic conditions (chemical concentrations, solution stirring speed, temperature, etc.) a robust, controllable procedure was developed. The relationship between particle size and salt concentration, MgSO4, was identified enabling the determination of PSL diameters a priori. Suggestions of future topics related to PSL synthesis, stability, and size variation are also described.

Localization from Visual Landmarks on a Free-Flying Robot

NASA Technical Reports Server (NTRS)

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

2016-01-01

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

Old and new news about single-photon sensitivity in human vision

NASA Astrophysics Data System (ADS)

Nelson, Philip

It is sometimes said that ``our eyes can see single photons,'' when in fact the faintest flash of light that can reliably be reported by human subjects is closer to 100 photons. Nevertheless, there is a sense in which the familiar claim is true. Experiments conducted long after the seminal work of Hecht, Shlaer, and Pirenne in two distinct realms, those of human psychophysics and single-cell physiology, now admit a more precisem conclusion to be drawn about our visual apparatus. Finding a single framework that accommodates both kinds of result is a nontrivial challenge, and one that sets severe quantitative constraints on any model of dim-light visual processing. I will present one such model and compare it to a recent experiment. Partially supported by the NSF under Grants EF-0928048 and DMR-0832802.

Chirality-dependent flutter of Typha blades in wind

PubMed Central

Zhao, Zi-Long; Liu, Zong-Yuan; Feng, Xi-Qiao

2016-01-01

Cattail or Typha, an emergent aquatic macrophyte widely distributed in lakes and other shallow water areas, has slender blades with a chiral morphology. The wind-resilient Typha blades can produce distinct hydraulic resistance for ecosystem functions. However, their stem may rupture and dislodge in excessive wind drag. In this paper, we combine fluid dynamics simulations and experimental measurements to investigate the aeroelastic behavior of Typha blades in wind. It is found that the chirality-dependent flutter, including wind-induced rotation and torsion, is a crucial strategy for Typha blades to accommodate wind forces. Flow visualization demonstrates that the twisting morphology of blades provides advantages over the flat one in the context of two integrated functions: improving wind resistance and mitigating vortex-induced vibration. The unusual dynamic responses and superior mechanical properties of Typha blades are closely related to their biological/ecosystem functions and macro/micro structures. This work decodes the physical mechanisms of chirality-dependent flutter in Typha blades and holds potential applications in vortex-induced vibration suppression and the design of, e.g., bioinspired flight vehicles. PMID:27432079

Chirality-dependent flutter of Typha blades in wind.

PubMed

Zhao, Zi-Long; Liu, Zong-Yuan; Feng, Xi-Qiao

2016-07-19

Cattail or Typha, an emergent aquatic macrophyte widely distributed in lakes and other shallow water areas, has slender blades with a chiral morphology. The wind-resilient Typha blades can produce distinct hydraulic resistance for ecosystem functions. However, their stem may rupture and dislodge in excessive wind drag. In this paper, we combine fluid dynamics simulations and experimental measurements to investigate the aeroelastic behavior of Typha blades in wind. It is found that the chirality-dependent flutter, including wind-induced rotation and torsion, is a crucial strategy for Typha blades to accommodate wind forces. Flow visualization demonstrates that the twisting morphology of blades provides advantages over the flat one in the context of two integrated functions: improving wind resistance and mitigating vortex-induced vibration. The unusual dynamic responses and superior mechanical properties of Typha blades are closely related to their biological/ecosystem functions and macro/micro structures. This work decodes the physical mechanisms of chirality-dependent flutter in Typha blades and holds potential applications in vortex-induced vibration suppression and the design of, e.g., bioinspired flight vehicles.

agriGO v2.0: a GO analysis toolkit for the agricultural community, 2017 update.

PubMed

Tian, Tian; Liu, Yue; Yan, Hengyu; You, Qi; Yi, Xin; Du, Zhou; Xu, Wenying; Su, Zhen

2017-07-03

The agriGO platform, which has been serving the scientific community for >10 years, specifically focuses on gene ontology (GO) enrichment analyses of plant and agricultural species. We continuously maintain and update the databases and accommodate the various requests of our global users. Here, we present our updated agriGO that has a largely expanded number of supporting species (394) and datatypes (865). In addition, a larger number of species have been classified into groups covering crops, vegetables, fish, birds and insects closely related to the agricultural community. We further improved the computational efficiency, including the batch analysis and P-value distribution (PVD), and the user-friendliness of the web pages. More visualization features were added to the platform, including SEACOMPARE (cross comparison of singular enrichment analysis), direct acyclic graph (DAG) and Scatter Plots, which can be merged by choosing any significant GO term. The updated platform agriGO v2.0 is now publicly accessible at http://systemsbiology.cau.edu.cn/agriGOv2/. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

Technology and needs for tomorrow's treatment of cataract

NASA Astrophysics Data System (ADS)

Tassignon, Marie-José

2007-02-01

Cataract surgery is considered to be the most successful surgery worldwide. However, new developments are ongoing either to improve the surgical stress or to improve the surgical outcome. While restoration of the transparency and optical parameters of the eye were initially the first goals, the need to improve the quality of sight (QOS) and to restore accommodation became evident during the last decades. By introducing the bag-in-the-lens (BIL) intraocular lens (IOL) and technique of implantation (US Patent 6,027,531) in 2000, PCO was no longer a matter of concern. Clinical studies conducted between 2000 and 2004 proved the efficacy of this new IOL with respect to PCO control, but showed additional advantages like surgeon-controlled centration and rotational stability. Surgeon-controlled IOL centration based on the alignment of the first and third Purkinje reflexes is one method to promote IOL centration but future tracking devices will probably enhance the precision by which IOL centration along the line of sight can be achieved. Optimal alignment is a major issue if toric correction and compensation of the spherical aberrations is intended to be incorporated into the IOL optic. IOL optics with toric correction to compensate for regular astigmatism are in development now, but toric correction for irregular astigmatism remains extremely challenging for the manufacturers. Improving the quality of the image by compensating for the spherical aberrations is the next step on our research programme. The BIL offers some opportunities to optimize postoperative accommodation by introducing the capsular accommodation ring.

A variable-collimation display system

NASA Astrophysics Data System (ADS)

Batchko, Robert; Robinson, Sam; Schmidt, Jack; Graniela, Benito

2014-03-01

Two important human depth cues are accommodation and vergence. Normally, the eyes accommodate and converge or diverge in tandem; changes in viewing distance cause the eyes to simultaneously adjust both focus and orientation. However, ambiguity between accommodation and vergence cues is a well-known limitation in many stereoscopic display technologies. This limitation also arises in state-of-the-art full-flight simulator displays. In current full-flight simulators, the out-the-window (OTW) display (i.e., the front cockpit window display) employs a fixed collimated display technology which allows the pilot and copilot to perceive the OTW training scene without angular errors or distortions; however, accommodation and vergence cues are limited to fixed ranges (e.g., ~ 20 m). While this approach works well for long-range, the ambiguity of depth cues at shorter range hinders the pilot's ability to gauge distances in critical maneuvers such as vertical take-off and landing (VTOL). This is the first in a series of papers on a novel, variable-collimation display (VCD) technology that is being developed under NAVY SBIR Topic N121-041 funding. The proposed VCD will integrate with rotary-wing and vertical take-off and landing simulators and provide accurate accommodation and vergence cues for distances ranging from approximately 3 m outside the chin window to ~ 20 m. A display that offers dynamic accommodation and vergence could improve pilot safety and training, and impact other applications presently limited by lack of these depth cues.

Shadow image on the retina of a defocused eye

NASA Astrophysics Data System (ADS)

Lenskii, A. V.

1994-04-01

Some visual conditions for transparent objects positioned within and beyond the accommodation limits on the path of the light traveling from a remote source of a small angular size are theoretically considered for the naked eye with a strong ametropia. The resolving power and admissible angular size of the light source are evaluated. The predicted possibility of seeing sufficiently extended transparent gratings at such distances has found that the density of ruling of the grating-object is higher than the ultimate angular resolution of the normal eye.

Cross-sectional study of object permanence in domestic puppies (Canis familiaris).

PubMed

Gagnon, S; Doré, F Y

1994-09-01

Visual accommodation and object permanence tests were administered to 70 puppies (Canis familiaris), aged 4 weeks to 9 months. The results showed that understanding of visible displacement problems emerged at the 5th weeks and developed rapidly until the 8th week. Although the search behaviors of older puppies were more flexible, no further significant development was observed between 8 weeks and 9 months. The results on invisible displacement tests suggest that understanding of invisible displacement problems appears around the 1st year in dogs' development.

Old and new results about single-photon sensitivity in human vision

NASA Astrophysics Data System (ADS)

Nelson, Philip C.

2016-04-01

It is sometimes said that ‘our eyes can see single photons’. This article begins by finding a more precise version of that claim and reviewing evidence gathered for it up to around 1985 in two distinct realms, those of human psychophysics and single-cell physiology. Finding a single framework that accommodates both kinds of result is then a nontrivial challenge, and one that sets severe quantitative constraints on any model of dim-light visual processing. This article presents one such model and compares it to a recent experiment.

Family-based treatment for transition age youth: parental self-efficacy and caregiver accommodation.

PubMed

Dimitropoulos, Gina; Landers, Ashley L; Freeman, Victoria E; Novick, Jason; Cullen, Olivia; Engelberg, Marla; Steinegger, Cathleen; Le Grange, Daniel

2018-01-01

Family-Based Treatment (FBT) is the first line of care in paediatric treatment while adult programs focus on individualized models of care. Transition age youth (TAY) with Anorexia Nervosa (AN) are in a unique life stage and between systems of care. As such, they and their caregivers may benefit from specialized, developmentally tailored models of treatment. The primary purpose of this study was to assess if parental self-efficacy and caregiver accommodation changed in caregivers during the course of FBT-TAY for AN. The secondary aim was to determine if changes in parental self-efficacy and caregiver accommodation contributed to improvements in eating disorder behaviour and weight restoration in the transition age youth with AN. Twenty-six participants (ages 16-22) and 39 caregivers were recruited. Caregivers completed the Parents versus Anorexia Scale and Accommodation and Enabling Scale for Eating Disorders at baseline, end-of-treatment (EOT), and 3 months follow-up. Unbalanced repeated measures designs for parental self-efficacy and caregiver accommodation towards illness behaviours were conducted using generalized estimation equations. Parental self-efficacy increased from baseline to EOT, although not significantly ( p =  .398). Parental self-efficacy significantly increased from baseline to 3 months post-treatment ( p  = .002). Caregiver accommodation towards the illness significantly decreased from baseline to EOT ( p  = 0.0001), but not from baseline to 3 months post-treatment ( p  = 1.000). Stepwise ordinary least squares regression estimates of eating disorder behaviour and weight restoration did not show that changes in parental-self efficacy and caregiver accommodation predict eating disorder behaviour or weight restoration at EOT or 3 months post-treatment. Our findings demonstrate, albeit preliminary at this stage, that FBT-TAY promotes positive increases in parental self-efficacy and assists caregivers in decreasing their accommodation to illness behaviours for transition age youth with AN. However, changes in the parental factors did not influence changes in eating and weight in the transition age youth.

Adaptation of the Quality Indicator for Rehabilitative Care (QuIRC) for use in mental health supported accommodation services (QuIRC-SA).

PubMed

Killaspy, Helen; White, Sarah; Dowling, Sarah; Krotofil, Joanna; McPherson, Peter; Sandhu, Sima; Arbuthnott, Maurice; Curtis, Sarah; Leavey, Gerard; Priebe, Stefan; Shepherd, Geoff; King, Michael

2016-04-14

No standardised tools for assessing the quality of specialist mental health supported accommodation services exist. To address this, we adapted the Quality Indicator for Rehabilitative care-QuIRC-that was originally developed to assess the quality of longer term inpatient and community based mental health facilities. The QuIRC, which is completed by the service manager and gives ratings of seven domains of care, has good psychometric properties. Focus groups with staff of the three main types of supported accommodation in the UK (residential care, supported housing and floating outreach services) were carried out to identify potential amendments to the QuIRC. Additional advice was gained from consultation with three expert panels, two of which comprised service users with lived experience of mental health and supported accommodation services. The amended QuIRC (QuIRC-SA) was piloted with a manager of each of the three service types. Item response variance, inter-rater reliability and internal consistency were assessed in a random sample of 52 services. Factorial structure and discriminant validity were assessed in a larger random sample of 87 services. The QuIRC-SA comprised 143 items of which only 18 items showed a narrow range of response and five items had poor inter-rater reliability. The tool showed good discriminant validity, with supported housing services generally scoring higher than the other two types of supported accommodation on most domains. Exploratory factor analysis showed that the QuIRC-SA items loaded onto the domains to which they had been allocated. The QuIRC-SA is the first standardised tool for quality assessment of specialist mental health supported accommodation services. Its psychometric properties mean that it has potential for use in research as well as audit and quality improvement programmes. A web based application is being developed to make it more accessible which will produce a printable report for the service manager about the performance of their service, comparison data for similar services and suggestions on how to improve service quality.

How EF-Tu can contribute to efficient proofreading of aa-tRNA by the ribosome

PubMed Central

Noel, Jeffrey K.; Whitford, Paul C.

2016-01-01

It has long been recognized that the thermodynamics of mRNA–tRNA base pairing is insufficient to explain the high fidelity and efficiency of aminoacyl-tRNA (aa-tRNA) selection by the ribosome. To rationalize this apparent inconsistency, Hopfield proposed that the ribosome may improve accuracy by utilizing a multi-step kinetic proofreading mechanism. While biochemical, structural and single-molecule studies have provided a detailed characterization of aa-tRNA selection, there is a limited understanding of how the physical–chemical properties of the ribosome enable proofreading. To this end, we probe the role of EF-Tu during aa-tRNA accommodation (the proofreading step) through the use of energy landscape principles, molecular dynamics simulations and kinetic models. We find that the steric composition of EF-Tu can reduce the free-energy barrier associated with the first step of accommodation: elbow accommodation. We interpret this effect within an extended kinetic model of accommodation and show how EF-Tu can contribute to efficient and accurate proofreading. PMID:27796304

Visual working memory is more tolerant than visual long-term memory.

PubMed

Schurgin, Mark W; Flombaum, Jonathan I

2018-05-07

Human visual memory is tolerant, meaning that it supports object recognition despite variability across encounters at the image level. Tolerant object recognition remains one capacity in which artificial intelligence trails humans. Typically, tolerance is described as a property of human visual long-term memory (VLTM). In contrast, visual working memory (VWM) is not usually ascribed a role in tolerant recognition, with tests of that system usually demanding discriminatory power-identifying changes, not sameness. There are good reasons to expect that VLTM is more tolerant; functionally, recognition over the long-term must accommodate the fact that objects will not be viewed under identical conditions; and practically, the passive and massive nature of VLTM may impose relatively permissive criteria for thinking that two inputs are the same. But empirically, tolerance has never been compared across working and long-term visual memory. We therefore developed a novel paradigm for equating encoding and test across different memory types. In each experiment trial, participants saw two objects, memory for one tested immediately (VWM) and later for the other (VLTM). VWM performance was better than VLTM and remained robust despite the introduction of image and object variability. In contrast, VLTM performance suffered linearly as more variability was introduced into test stimuli. Additional experiments excluded interference effects as causes for the observed differences. These results suggest the possibility of a previously unidentified role for VWM in the acquisition of tolerant representations for object recognition. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Towards sustainable infrastructure management: knowledge-based service-oriented computing framework for visual analytics

NASA Astrophysics Data System (ADS)

Vatcha, Rashna; Lee, Seok-Won; Murty, Ajeet; Tolone, William; Wang, Xiaoyu; Dou, Wenwen; Chang, Remco; Ribarsky, William; Liu, Wanqiu; Chen, Shen-en; Hauser, Edd

2009-05-01

Infrastructure management (and its associated processes) is complex to understand, perform and thus, hard to make efficient and effective informed decisions. The management involves a multi-faceted operation that requires the most robust data fusion, visualization and decision making. In order to protect and build sustainable critical assets, we present our on-going multi-disciplinary large-scale project that establishes the Integrated Remote Sensing and Visualization (IRSV) system with a focus on supporting bridge structure inspection and management. This project involves specific expertise from civil engineers, computer scientists, geographers, and real-world practitioners from industry, local and federal government agencies. IRSV is being designed to accommodate the essential needs from the following aspects: 1) Better understanding and enforcement of complex inspection process that can bridge the gap between evidence gathering and decision making through the implementation of ontological knowledge engineering system; 2) Aggregation, representation and fusion of complex multi-layered heterogeneous data (i.e. infrared imaging, aerial photos and ground-mounted LIDAR etc.) with domain application knowledge to support machine understandable recommendation system; 3) Robust visualization techniques with large-scale analytical and interactive visualizations that support users' decision making; and 4) Integration of these needs through the flexible Service-oriented Architecture (SOA) framework to compose and provide services on-demand. IRSV is expected to serve as a management and data visualization tool for construction deliverable assurance and infrastructure monitoring both periodically (annually, monthly, even daily if needed) as well as after extreme events.

Electronic Timekeeping: North Dakota State University Improves Payroll Processing.

ERIC Educational Resources Information Center

Vetter, Ronald J.; And Others

1993-01-01

North Dakota State University has adopted automated timekeeping to improve the efficiency and effectiveness of payroll processing. The microcomputer-based system accurately records and computes employee time, tracks labor distribution, accommodates complex labor policies and company pay practices, provides automatic data processing and reporting,…

Is eye damage caused by stereoscopic displays?

NASA Astrophysics Data System (ADS)

Mayer, Udo; Neumann, Markus D.; Kubbat, Wolfgang; Landau, Kurt

2000-05-01

A normal developing child will achieve emmetropia in youth and maintain it. Thereby cornea, lens and axial length of the eye grow astonishingly coordinated. In the last years research has evidenced that this coordinated growing process is a visually controlled closed loop. The mechanism has been studied particularly in animals. It was found that the growth of the axial length of the eyeball is controlled by image focus information from the retina. It was shown that maladjustment can occur by this visually-guided growth control mechanism that result in ametropia. Thereby it has been proven that e.g. short-sightedness is not only caused by heredity, but is acquired under certain visual conditions. It is shown that these conditions are similar to the conditions of viewing stereoscopic displays where the normal accommodation convergence coupling is disjoint. An evaluation is given of the potential of damaging the eyes by viewing stereoscopic displays. Concerning this, different viewing methods for stereoscopic displays are evaluated. Moreover, clues are given how the environment and display conditions shall be set and what users shall be chosen to minimize the risk of eye damages.

Letter position coding across modalities: the case of Braille readers.

PubMed

Perea, Manuel; García-Chamorro, Cristina; Martín-Suesta, Miguel; Gómez, Pablo

2012-01-01

The question of how the brain encodes letter position in written words has attracted increasing attention in recent years. A number of models have recently been proposed to accommodate the fact that transposed-letter stimuli like jugde or caniso are perceptually very close to their base words. Here we examined how letter position coding is attained in the tactile modality via Braille reading. The idea is that Braille word recognition may provide more serial processing than the visual modality, and this may produce differences in the input coding schemes employed to encode letters in written words. To that end, we conducted a lexical decision experiment with adult Braille readers in which the pseudowords were created by transposing/replacing two letters. We found a word-frequency effect for words. In addition, unlike parallel experiments in the visual modality, we failed to find any clear signs of transposed-letter confusability effects. This dissociation highlights the differences between modalities. The present data argue against models of letter position coding that assume that transposed-letter effects (in the visual modality) occur at a relatively late, abstract locus.

A direct comparison of short-term audiomotor and visuomotor memory.

PubMed

Ward, Amanda M; Loucks, Torrey M; Ofori, Edward; Sosnoff, Jacob J

2014-04-01

Audiomotor and visuomotor short-term memory are required for an important variety of skilled movements but have not been compared in a direct manner previously. Audiomotor memory capacity might be greater to accommodate auditory goals that are less directly related to movement outcome than for visually guided tasks. Subjects produced continuous isometric force with the right index finger under auditory and visual feedback. During the first 10 s of each trial, subjects received continuous auditory or visual feedback. For the following 15 s, feedback was removed but the force had to be maintained accurately. An internal effort condition was included to test memory capacity in the same manner but without external feedback. Similar decay times of ~5-6 s were found for vision and audition but the decay time for internal effort was ~4 s. External feedback thus provides an advantage in maintaining a force level after feedback removal, but may not exclude some contribution from a sense of effort. Short-term memory capacity appears longer than certain previous reports but there may not be strong distinctions in capacity across different sensory modalities, at least for isometric force.

Meteorological support for space operations: Review and recommendations

NASA Technical Reports Server (NTRS)

1988-01-01

The current meteorological support provided to NASA by NOAA, Air Weather Service, and other contractors is reviewed and suggestions are offered for its improvement. These recommendations include improvement in NASA's internal management organizational structure that would accommodate continued improvement in operational weather support, installation of new observing systems, improvement in analysis and forecasting procedures, and the establishment of an Applied Research and Forecasting Facility.

Microcontroller based fibre-optic visual presentation system for multisensory neuroimaging.

PubMed

Kurniawan, Veldri; Klemen, Jane; Chambers, Christopher D

2011-10-30

Presenting visual stimuli in physical 3D space during fMRI experiments carries significant technical challenges. Certain types of multisensory visuotactile experiments and visuomotor tasks require presentation of visual stimuli in peripersonal space, which cannot be accommodated by ordinary projection screens or binocular goggles. However, light points produced by a group of LEDs can be transmitted through fibre-optic cables and positioned anywhere inside the MRI scanner. Here we describe the design and implementation of a microcontroller-based programmable digital device for controlling fibre-optically transmitted LED lights from a PC. The main feature of this device is the ability to independently control the colour, brightness, and timing of each LED. Moreover, the device was designed in a modular and extensible way, which enables easy adaptation for various experimental paradigms. The device was tested and validated in three fMRI experiments involving basic visual perception, a simple colour discrimination task, and a blocked multisensory visuo-tactile task. The results revealed significant lateralized activation in occipital cortex of all participants, a reliable response in ventral occipital areas to colour stimuli elicited by the device, and strong activations in multisensory brain regions in the multisensory task. Overall, these findings confirm the suitability of this device for presenting complex fibre-optic visual and cross-modal stimuli inside the scanner. Copyright © 2011 Elsevier B.V. All rights reserved.

Steady-state visual evoked potentials as a research tool in social affective neuroscience

PubMed Central

Wieser, Matthias J.; Miskovic, Vladimir; Keil, Andreas

2017-01-01

Like many other primates, humans place a high premium on social information transmission and processing. One important aspect of this information concerns the emotional state of other individuals, conveyed by distinct visual cues such as facial expressions, overt actions, or by cues extracted from the situational context. A rich body of theoretical and empirical work has demonstrated that these socio-emotional cues are processed by the human visual system in a prioritized fashion, in the service of optimizing social behavior. Furthermore, socio-emotional perception is highly dependent on situational contexts and previous experience. Here, we review current issues in this area of research and discuss the utility of the steady-state visual evoked potential (ssVEP) technique for addressing key empirical questions. Methodological advantages and caveats are discussed with particular regard to quantifying time-varying competition among multiple perceptual objects, trial-by-trial analysis of visual cortical activation, functional connectivity, and the control of low-level stimulus features. Studies on facial expression and emotional scene processing are summarized, with an emphasis on viewing faces and other social cues in emotional contexts, or when competing with each other. Further, because the ssVEP technique can be readily accommodated to studying the viewing of complex scenes with multiple elements, it enables researchers to advance theoretical models of socio-emotional perception, based on complex, quasi-naturalistic viewing situations. PMID:27699794

The Parent Component of the Kindergarten and Elementary Intervention Project (KEIP).

ERIC Educational Resources Information Center

Taylor, Linda

This paper describes an experimental early intervention program called the Kindergarten and Elementary Intervention Program, which provides support for at-risk students, their parents, and teachers. It aims at the improvement of early school adjustment through approaches designed to accommodate a wide range of individual differences; improve and…

Faculty Learning Communities: Improving Teaching in Higher Education

ERIC Educational Resources Information Center

Ward, Hsuying C.; Selvester, Paula M.

2012-01-01

Faculty learning communities (FLCs) are collaborative collegial groups of faculty and other teaching staff who are interested in and committed to the improvement of their teaching to accommodate a diverse student population through group discourse, reflection and goal setting. In this article, we describe our FLC experiences that were supported by…

A Performance Appraisal System for School Principals.

ERIC Educational Resources Information Center

Knoop, Robert; Common, Ronald W.

The Performance Review, Analysis, and Improvement System for Educators (PRAISE) is a formative evaluation instrument designed to improve the performance of school principals. The system appears to be reliable and valid and is flexible enough to accommodate the needs of a variety of schools. Sample items and categories of the instrument include…

Leadership for 2000. Management Report 1989-90/1.

ERIC Educational Resources Information Center

Roueche, John E.

Of all challenges facing open-door community colleges, none is more important than the need to renew and improve teaching quality in order to accommodate increasingly diversified student populations. Several policies have been particularly helpful to open-door institutions in improving student retention and achievement, including the following:…

Contextual remapping in visual search after predictable target-location changes.

PubMed

Conci, Markus; Sun, Luning; Müller, Hermann J

2011-07-01

Invariant spatial context can facilitate visual search. For instance, detection of a target is faster if it is presented within a repeatedly encountered, as compared to a novel, layout of nontargets, demonstrating a role of contextual learning for attentional guidance ('contextual cueing'). Here, we investigated how context-based learning adapts to target location (and identity) changes. Three experiments were performed in which, in an initial learning phase, observers learned to associate a given context with a given target location. A subsequent test phase then introduced identity and/or location changes to the target. The results showed that contextual cueing could not compensate for target changes that were not 'predictable' (i.e. learnable). However, for predictable changes, contextual cueing remained effective even immediately after the change. These findings demonstrate that contextual cueing is adaptive to predictable target location changes. Under these conditions, learned contextual associations can be effectively 'remapped' to accommodate new task requirements.

Visualising Conversation Structure across Time: Insights into Effective Doctor-Patient Consultations

PubMed Central

Angus, Daniel; Watson, Bernadette; Smith, Andrew; Gallois, Cindy; Wiles, Janet

2012-01-01

Effective communication between healthcare professionals and patients is critical to patients’ health outcomes. The doctor/patient dialogue has been extensively researched from different perspectives, with findings emphasising a range of behaviours that lead to effective communication. Much research involves self-reports, however, so that behavioural engagement cannot be disentangled from patients’ ratings of effectiveness. In this study we used a highly efficient and time economic automated computer visualisation measurement technique called Discursis to analyse conversational behaviour in consultations. Discursis automatically builds an internal language model from a transcript, mines the transcript for its conceptual content, and generates an interactive visual account of the discourse. The resultant visual account of the whole consultation can be analysed for patterns of engagement between interactants. The findings from this study show that Discursis is effective at highlighting a range of consultation techniques, including communication accommodation, engagement and repetition. PMID:22693629

Classification-Based Spatial Error Concealment for Visual Communications

NASA Astrophysics Data System (ADS)

Chen, Meng; Zheng, Yefeng; Wu, Min

2006-12-01

In an error-prone transmission environment, error concealment is an effective technique to reconstruct the damaged visual content. Due to large variations of image characteristics, different concealment approaches are necessary to accommodate the different nature of the lost image content. In this paper, we address this issue and propose using classification to integrate the state-of-the-art error concealment techniques. The proposed approach takes advantage of multiple concealment algorithms and adaptively selects the suitable algorithm for each damaged image area. With growing awareness that the design of sender and receiver systems should be jointly considered for efficient and reliable multimedia communications, we proposed a set of classification-based block concealment schemes, including receiver-side classification, sender-side attachment, and sender-side embedding. Our experimental results provide extensive performance comparisons and demonstrate that the proposed classification-based error concealment approaches outperform the conventional approaches.

Unsupervised real-time speaker identification for daily movies

NASA Astrophysics Data System (ADS)

Li, Ying; Kuo, C.-C. Jay

2002-07-01

The problem of identifying speakers for movie content analysis is addressed in this paper. While most previous work on speaker identification was carried out in a supervised mode using pure audio data, more robust results can be obtained in real-time by integrating knowledge from multiple media sources in an unsupervised mode. In this work, both audio and visual cues will be employed and subsequently combined in a probabilistic framework to identify speakers. Particularly, audio information is used to identify speakers with a maximum likelihood (ML)-based approach while visual information is adopted to distinguish speakers by detecting and recognizing their talking faces based on face detection/recognition and mouth tracking techniques. Moreover, to accommodate for speakers' acoustic variations along time, we update their models on the fly by adapting to their newly contributed speech data. Encouraging results have been achieved through extensive experiments, which shows a promising future of the proposed audiovisual-based unsupervised speaker identification system.

Comparison of form in potential functions while maintaining upright posture during exposure to stereoscopic video clips.

PubMed

Kutsuna, Kenichiro; Matsuura, Yasuyuki; Fujikake, Kazuhiro; Miyao, Masaru; Takada, Hiroki

2013-01-01

Visually induced motion sickness (VIMS) is caused by sensory conflict, the disagreement between vergence and visual accommodation while observing stereoscopic images. VIMS can be measured by psychological and physiological methods. We propose a mathematical methodology to measure the effect of three-dimensional (3D) images on the equilibrium function. In this study, body sway in the resting state is compared with that during exposure to 3D video clips on a liquid crystal display (LCD) and on a head mounted display (HMD). In addition, the Simulator Sickness Questionnaire (SSQ) was completed immediately afterward. Based on the statistical analysis of the SSQ subscores and each index for stabilograms, we succeeded in determining the quantity of the VIMS during exposure to the stereoscopic images. Moreover, we discuss the metamorphism in the potential functions to control the standing posture during the exposure to stereoscopic video clips.

Access to Workplace Accommodations to Support Breastfeeding after Passage of the Affordable Care Act.

PubMed

Kozhimannil, Katy B; Jou, Judy; Gjerdingen, Dwenda K; McGovern, Patricia M

2016-01-01

This study examines access to workplace accommodations for breastfeeding, as mandated by the Affordable Care Act, and its associations with breastfeeding initiation and duration. We hypothesize that women with access to reasonable break time and private space to express breast milk would be more likely to breastfeed exclusively at 6 months and to continue breastfeeding for a longer duration. Data are from Listening to Mothers III, a national survey of women ages 18 to 45 who gave birth in 2011 and 2012. The study population included women who were employed full or part time at the time of survey. Using two-way tabulation, logistic regression, and survival analysis, we characterized women with access to breastfeeding accommodations and assessed the associations between these accommodations and breastfeeding outcomes. Only 40% of women had access to both break time and private space. Women with both adequate break time and private space were 2.3 times (95% CI, 1.03-4.95) as likely to be breastfeeding exclusively at 6 months and 1.5 times (95% CI, 1.08-2.06) as likely to continue breastfeeding exclusively with each passing month compared with women without access to these accommodations. Employed women face unique barriers to breastfeeding and have lower rates of breastfeeding initiation and shorter durations, despite compelling evidence of associated health benefits. Expanded access to workplace accommodations for breastfeeding will likely entail collaborative efforts between public health agencies, employers, insurers, and clinicians to ensure effective workplace policies and improved breastfeeding outcomes. Copyright © 2016 Jacobs Institute of Women's Health. Published by Elsevier Inc. All rights reserved.

Access to workplace accommodations to support breastfeeding after passage of the Affordable Care Act

PubMed Central

Kozhimannil, Katy B.; Jou, Judy; Gjerdingen, Dwenda K.; McGovern, Patricia M.

2015-01-01

Objectives This study examines access to workplace accommodations for breastfeeding, as mandated by the Affordable Care Act, and its associations with breastfeeding initiation and duration. We hypothesize that women with access to reasonable break time and private space to express breast milk would be more likely to breastfeed exclusively at 6 months and to continue breastfeeding for a longer duration. Methods Data are from Listening to Mothers III, a national survey of women ages 18–45 who gave birth in 2011–2012. The study population included women who were employed full- or part-time at the time of survey. Using two-way tabulation, logistic regression, and survival analysis, we characterized women with access to breastfeeding accommodations and assessed the associations between these accommodations and breastfeeding outcomes. Results Only 40% of women had access to both break time and private space. Women with both adequate break time and private space were 2.3 times (95% CI 1.03, 4.95) as likely to be breastfeeding exclusively at 6 months and 1.5 times (95% CI 1.08, 2.06) as likely to continue breastfeeding exclusively with each passing month compared to women without access to these accommodations. Conclusions Employed women face unique barriers to breastfeeding and have lower rates of breastfeeding initiation and shorter durations, despite compelling evidence of associated health benefits. Expanded access to workplace accommodations for breastfeeding will likely entail collaborative efforts between public health agencies, employers, insurers, and clinicians to ensure effective workplace policies and improved breastfeeding outcomes. PMID:26474955

Itopride for gastric volume, gastric emptying and drinking capacity in functional dyspepsia

PubMed Central

Abid, Shahab; Jafri, Wasim; Zaman, Maseeh Uz; Bilal, Rakhshanda; Awan, Safia; Abbas, Aamir

2017-01-01

AIM To study the effect of itopride on gastric accommodation, gastric emptying and drinking capacity in functional dyspepsia (FD). METHODS Randomized controlled trial was conducted to check the effect of itopride on gastric accommodation, gastric emptying, capacity of tolerating nutrient liquid and symptoms of FD. We recruited a total of 31 patients having FD on the basis of ROME III criteria. After randomization, itopride was received by 15 patients while 16 patients received placebo. Gastric accommodation was determined using Gastric Scintigraphy. 13C labeled octanoic breadth test was performed to assess gastric emptying. Capacity of tolerating nutrient liquid drink was checked using satiety drinking capacity test. The intervention group comprised of 150 mg itopride. Patients in both arms were followed for 4 wk. RESULTS Mean age of the recruited participant 33 years (SD = 7.6) and most of the recruited individuals, i.e., 21 (67.7%) were males. We found that there was no effect of itopride on gastric accommodation as measured at different in volumes in the itopride and control group with the empty stomach (P = 0.14), at 20 min (P = 0.38), 30 min (P = 0.30), 40 min (P = 0.43), 50 min (P = 0.50), 60 min (P = 0.81), 90 min (P = 0.25) and 120 min (P = 0.67). Gastric emptying done on a sub sample (n = 11) showed no significant difference (P = 0.58) between itopride and placebo group. There was no significant improvement in the capacity to tolerate liquid in the itopride group as compared to placebo (P = 0.51). Similarly there was no significant improvement of symptoms as assessed through a composite symptom score (P = 0.74). The change in QT interval in itopride group was not significantly different from placebo (0.10). CONCLUSION Our study found no effect of itopride on gastric accommodation, gastric emptying and maximum tolerated volume in patients with FD. PMID:28217377

Itopride for gastric volume, gastric emptying and drinking capacity in functional dyspepsia.

PubMed

Abid, Shahab; Jafri, Wasim; Zaman, Maseeh Uz; Bilal, Rakhshanda; Awan, Safia; Abbas, Aamir

2017-02-06

To study the effect of itopride on gastric accommodation, gastric emptying and drinking capacity in functional dyspepsia (FD). Randomized controlled trial was conducted to check the effect of itopride on gastric accommodation, gastric emptying, capacity of tolerating nutrient liquid and symptoms of FD. We recruited a total of 31 patients having FD on the basis of ROME III criteria. After randomization, itopride was received by 15 patients while 16 patients received placebo. Gastric accommodation was determined using Gastric Scintigraphy. 13 C labeled octanoic breadth test was performed to assess gastric emptying. Capacity of tolerating nutrient liquid drink was checked using satiety drinking capacity test. The intervention group comprised of 150 mg itopride. Patients in both arms were followed for 4 wk. Mean age of the recruited participant 33 years (SD = 7.6) and most of the recruited individuals, i.e ., 21 (67.7%) were males. We found that there was no effect of itopride on gastric accommodation as measured at different in volumes in the itopride and control group with the empty stomach ( P = 0.14), at 20 min ( P = 0.38), 30 min ( P = 0.30), 40 min ( P = 0.43), 50 min ( P = 0.50), 60 min ( P = 0.81), 90 min ( P = 0.25) and 120 min ( P = 0.67). Gastric emptying done on a sub sample ( n = 11) showed no significant difference ( P = 0.58) between itopride and placebo group. There was no significant improvement in the capacity to tolerate liquid in the itopride group as compared to placebo ( P = 0.51). Similarly there was no significant improvement of symptoms as assessed through a composite symptom score ( P = 0.74). The change in QT interval in itopride group was not significantly different from placebo (0.10). Our study found no effect of itopride on gastric accommodation, gastric emptying and maximum tolerated volume in patients with FD.

Perceptual learning in children with visual impairment improves near visual acuity.

PubMed

Huurneman, Bianca; Boonstra, F Nienke; Cox, Ralf F A; van Rens, Ger; Cillessen, Antonius H N

2013-09-17

This study investigated whether visual perceptual learning can improve near visual acuity and reduce foveal crowding effects in four- to nine-year-old children with visual impairment. Participants were 45 children with visual impairment and 29 children with normal vision. Children with visual impairment were divided into three groups: a magnifier group (n = 12), a crowded perceptual learning group (n = 18), and an uncrowded perceptual learning group (n = 15). Children with normal vision also were divided in three groups, but were measured only at baseline. Dependent variables were single near visual acuity (NVA), crowded NVA, LH line 50% crowding NVA, number of trials, accuracy, performance time, amount of small errors, and amount of large errors. Children with visual impairment trained during six weeks, two times per week, for 30 minutes (12 training sessions). After training, children showed significant improvement of NVA in addition to specific improvements on the training task. The crowded perceptual learning group showed the largest acuity improvements (1.7 logMAR lines on the crowded chart, P < 0.001). Only the children in the crowded perceptual learning group showed improvements on all NVA charts. Children with visual impairment benefit from perceptual training. While task-specific improvements were observed in all training groups, transfer to crowded NVA was largest in the crowded perceptual learning group. To our knowledge, this is the first study to provide evidence for the improvement of NVA by perceptual learning in children with visual impairment. (http://www.trialregister.nl number, NTR2537.).

Dynamic adjustments in prefrontal, hippocampal, and inferior temporal interactions with increasing visual working memory load.

PubMed

Rissman, Jesse; Gazzaley, Adam; D'Esposito, Mark

2008-07-01

The maintenance of visual stimuli across a delay interval in working memory tasks is thought to involve reverberant neural communication between the prefrontal cortex and posterior visual association areas. Recent studies suggest that the hippocampus might also contribute to this retention process, presumably via reciprocal interactions with visual regions. To characterize the nature of these interactions, we performed functional connectivity analysis on an event-related functional magnetic resonance imaging data set in which participants performed a delayed face recognition task. As the number of faces that participants were required to remember was parametrically increased, the right inferior frontal gyrus (IFG) showed a linearly decreasing degree of functional connectivity with the fusiform face area (FFA) during the delay period. In contrast, the hippocampus linearly increased its delay period connectivity with both the FFA and the IFG as the mnemonic load increased. Moreover, the degree to which participants' FFA showed a load-dependent increase in its connectivity with the hippocampus predicted the degree to which its connectivity with the IFG decreased with load. Thus, these neural circuits may dynamically trade off to accommodate the particular mnemonic demands of the task, with IFG-FFA interactions mediating maintenance at lower loads and hippocampal interactions supporting retention at higher loads.

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

PubMed

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

2017-12-01

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

[Efficacy of topical ketorolac for improving visual function after photocoagulation in diabetic patients with focal macular edema].

PubMed

Razo Blanco-Hernández, Dulce Milagros; Lima-Gómez, Virgilio; Asbun-Bojalil, Juan

2014-01-01

Photocoagulation reduces the incidence of visual loss in diabetic patients with focal macular edema, but it can induce it for Efficacy of topical ketorolac for improving visual function after photocoagulation in diabetic patients with focal macular edema 6 weeks after treatment and produces visual improvement in some cases. Topical ketorolac may reduce the inflammation caused by photocoagulation and improve visual outcome. To determine the efficacy of topical ketorolac for improving visual function after photocoagulation in diabetic patients with focal macular edema. An experimental, comparative, prospective, longitudinal study in diabetic patients with focal macular edema was conducted. Eyes were randomized into two groups of topical treatment for 3 weeks after photocoagulation (A: ketorolac, B: placebo). Best corrected visual acuity before and after treatment was compared in each group (paired t test), and the proportion of eyes with visual improvement was compared between groups (χ(2)). The evaluation was repeated after stratifying for initial visual acuity (≥ 0.5, < 0.5). There were 105 eyes included. In group A (n= 46) mean visual acuity changed from 0.50 to 0.58 (p= 0.003), and from 0.55 to 0.55 in group B (n= 59, p= 0.83); mean percent change was 22.3% in group A and 3.5% in group B (p= 0.03). Visual improvement was identified in 25 eyes from group A (54.3%) and 19 from group B (32.2%, p= 0.019, RR 1.65); the difference only persisted when initial visual acuity was ≥ 0.5 (10 [40%], group A, 5 [14.7%], group B, p= 0.02, RR 2.72). Topical ketorolac was more effective than placebo to improve best corrected visual acuity in diabetic patients with focal macular edema.

Sensitivity of vergence responses of 5- to 10-week-old human infants

PubMed Central

Seemiller, Eric S.; Wang, Jingyun; Candy, T. Rowan

2016-01-01

Infants have been shown to make vergence eye movements by 1 month of age to stimulation with prisms or targets moving in depth. However, little is currently understood about the threshold sensitivity of the maturing visual system to such stimulation. In this study, 5- to 10-week-old human infants and adults viewed a target moving in depth as a triangle wave of three amplitudes (1.0, 0.5, and 0.25 meter angles). Their horizontal eye position and the refractive state of both eyes were measured simultaneously. The vergence responses of the infants and adults varied at the same frequency as the stimulus at the three tested modulation amplitudes. For a typical infant of this age, the smallest amplitude is equivalent to an interocular change of approximately 2° of retinal disparity, from nearest to farthest points. The infants' accommodation responses only modulated reliably to the largest stimulus, while adults responded to all three amplitudes. Although the accommodative system appears relatively insensitive, the sensitivity of the vergence responses suggests that subtle cues are available to drive vergence in the second month after birth. PMID:26891827

Advanced Multimodal Solutions for Information Presentation

NASA Technical Reports Server (NTRS)

Wenzel, Elizabeth M.; Godfroy-Cooper, Martine

2018-01-01

High-workload, fast-paced, and degraded sensory environments are the likeliest candidates to benefit from multimodal information presentation. For example, during EVA (Extra-Vehicular Activity) and telerobotic operations, the sensory restrictions associated with a space environment provide a major challenge to maintaining the situation awareness (SA) required for safe operations. Multimodal displays hold promise to enhance situation awareness and task performance by utilizing different sensory modalities and maximizing their effectiveness based on appropriate interaction between modalities. During EVA, the visual and auditory channels are likely to be the most utilized with tasks such as monitoring the visual environment, attending visual and auditory displays, and maintaining multichannel auditory communications. Previous studies have shown that compared to unimodal displays (spatial auditory or 2D visual), bimodal presentation of information can improve operator performance during simulated extravehicular activity on planetary surfaces for tasks as diverse as orientation, localization or docking, particularly when the visual environment is degraded or workload is increased. Tactile displays offer a third sensory channel that may both offload information processing effort and provide a means to capture attention when urgently required. For example, recent studies suggest that including tactile cues may result in increased orientation and alerting accuracy, improved task response time and decreased workload, as well as provide self-orientation cues in microgravity on the ISS (International Space Station). An important overall issue is that context-dependent factors like task complexity, sensory degradation, peripersonal vs. extrapersonal space operations, workload, experience level, and operator fatigue tend to vary greatly in complex real-world environments and it will be difficult to design a multimodal interface that performs well under all conditions. As a possible solution, adaptive systems have been proposed in which the information presented to the user changes as a function of taskcontext-dependent factors. However, this presupposes that adequate methods for detecting andor predicting such factors are developed. Further, research in adaptive systems for aviation suggests that they can sometimes serve to increase workload and reduce situational awareness. It will be critical to develop multimodal display guidelines that include consideration of smart systems that can select the best display method for a particular contextsituation.The scope of the current work is an analysis of potential multimodal display technologies for long duration missions and, in particular, will focus on their potential role in EVA activities. The review will address multimodal (combined visual, auditory andor tactile) displays investigated by NASA, industry, and DoD (Dept. of Defense). It also considers the need for adaptive information systems to accommodate a variety of operational contexts such as crew status (e.g., fatigue, workload level) and task environment (e.g., EVA, habitat, rover, spacecraft). Current approaches to guidelines and best practices for combining modalities for the most effective information displays are also reviewed. Potential issues in developing interface guidelines for the Exploration Information System (EIS) are briefly considered.

76 FR 56967 - Amendment of Class E Airspace; Glendive, MT

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-15

... Positioning System (GPS) standard instrument approach procedures. This improves the safety and management of... Airport, to accommodate IFR aircraft executing RNAV (GPS) standard instrument approach procedures at the...

77 FR 38476 - Establishment of Class E Airspace; Eureka, NV

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-28

... (GPS) standard instrument approach procedures at Eureka Airport, Eureka, NV. This improves the safety... Eureka Airport, to accommodate IFR aircraft executing a new RNAV (GPS) standard instrument approach...

Case management services for work related upper extremity disorders. Integrating workplace accommodation and problem solving.

PubMed

Shaw, W S; Feuerstein, M; Lincoln, A E; Miller, V I; Wood, P M

2001-08-01

A case manager's ability to obtain worksite accommodations and engage workers in active problem solving may improve health and return to work outcomes for clients with work related upper extremity disorders (WRUEDs). This study examines the feasibility of a 2 day training seminar to help nurse case managers identify ergonomic risk factors, provide accommodation, and conduct problem solving skills training with workers' compensation claimants recovering from WRUEDs. Eight procedural steps to this case management approach were identified, translated into a training workshop format, and conveyed to 65 randomly selected case managers. Results indicate moderate to high self ratings of confidence to perform ergonomic assessments (mean = 7.5 of 10) and to provide problem solving skills training (mean = 7.2 of 10) after the seminar. This training format was suitable to experienced case managers and generated a moderate to high level of confidence to use this case management approach.

Framing effectiveness in impact assessment: Discourse accommodation in controversial infrastructure development

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

Rozema, Jaap G., E-mail: j.rozema@uea.ac.uk; Department of Development and Planning, Aalborg University, A.C. Meyers Vænge 15, DK-2450 København SV; Bond, Alan J.

There is ongoing debate about the effectiveness of impact assessment tools, which matters both because of the threat to future practice of the tools which are frequently perceived to be ineffective, and because of the disillusionment that can ensue, and controversy generated, amongst stakeholders in a decision context where opportunities for meaningful debate have not been provided. In this article we regard debate about the meaning of effectiveness in impact assessment as an inevitable consequence of increased participation in environmental decision-making, and therefore frame effectiveness based on an inclusive democracy role to mean the extent to which impact assessment canmore » accommodate civil society discourse. Our aim is to investigate effectiveness based on this framing by looking at one type of impact assessment – environmental impact assessment (EIA) – in two controversial project proposals: the HS2 rail network in England; and the A4DS motorway in the Netherlands. Documentary analysis and interviews held with key civil society stakeholders have been deployed to identify discourses that were mobilised in the cases. EIA was found to be able to accommodate only one out of four discourses that were identified; for the other three it did not provide the space for the arguments that characterised opposition. The conclusion in relation to debate on framings of effectiveness is that EIA will not be considered effective by the majority of stakeholders. EIA was established to support decision-making through a better understanding of impacts, so its ineffectiveness is unsurprising when its role is perceived to be broader. However, there remains a need to map discourses in different decision contexts and to analyse the extent to which the range of discourses are accommodated throughout the decision process, and the role of impact assessment in those processes, before recommendations can be made to either improve impact assessment effectiveness, or whether it is simply perceptions of effectiveness that need to be improved. - Highlights: • Effectiveness of EIA is defined in terms of its ability to accommodate discourses. • Four separate discourses were identified across two controversial cases. • EIA is considered to mobilize one out of four discourses only. • Discourse mapping is recommended to improve EIA effectiveness.« less

Improved bridge joint materials and design details.

DOT National Transportation Integrated Search

2017-06-01

Expansion joints accommodate bridge movements that result from factors such as thermal expansion and contraction, concrete shrinkage, creep effects, live loading, settlement of the foundation and substructure, and environmental stressors. Expansion j...

25 CFR 170.411 - What may a long-range transportation plan include?

Code of Federal Regulations, 2012 CFR

2012-04-01

...; (b) Trip generation studies, including determination of traffic generators due to land use; (c) Social and economic development planning to identify transportation improvements or needs to accommodate...

25 CFR 170.411 - What may a long-range transportation plan include?

Code of Federal Regulations, 2011 CFR

2011-04-01

...; (b) Trip generation studies, including determination of traffic generators due to land use; (c) Social and economic development planning to identify transportation improvements or needs to accommodate...

25 CFR 170.411 - What may a long-range transportation plan include?

Code of Federal Regulations, 2013 CFR

2013-04-01

...; (b) Trip generation studies, including determination of traffic generators due to land use; (c) Social and economic development planning to identify transportation improvements or needs to accommodate...

25 CFR 170.411 - What may a long-range transportation plan include?

Code of Federal Regulations, 2014 CFR

2014-04-01

...; (b) Trip generation studies, including determination of traffic generators due to land use; (c) Social and economic development planning to identify transportation improvements or needs to accommodate...

Automatic motion correction for in vivo human skin optical coherence tomography angiography through combined rigid and nonrigid registration

NASA Astrophysics Data System (ADS)

Wei, David Wei; Deegan, Anthony J.; Wang, Ruikang K.

2017-06-01

When using optical coherence tomography angiography (OCTA), the development of artifacts due to involuntary movements can severely compromise the visualization and subsequent quantitation of tissue microvasculatures. To correct such an occurrence, we propose a motion compensation method to eliminate artifacts from human skin OCTA by means of step-by-step rigid affine registration, rigid subpixel registration, and nonrigid B-spline registration. To accommodate this remedial process, OCTA is conducted using two matching all-depth volume scans. Affine transformation is first performed on the large vessels of the deep reticular dermis, and then the resulting affine parameters are applied to all-depth vasculatures with a further subpixel registration to refine the alignment between superficial smaller vessels. Finally, the coregistration of both volumes is carried out to result in the final artifact-free composite image via an algorithm based upon cubic B-spline free-form deformation. We demonstrate that the proposed method can provide a considerable improvement to the final en face OCTA images with substantial artifact removal. In addition, the correlation coefficients and peak signal-to-noise ratios of the corrected images are evaluated and compared with those of the original images, further validating the effectiveness of the proposed method. We expect that the proposed method can be useful in improving qualitative and quantitative assessment of the OCTA images of scanned tissue beds.

Automatic motion correction for in vivo human skin optical coherence tomography angiography through combined rigid and nonrigid registration.

PubMed

Wei, David Wei; Deegan, Anthony J; Wang, Ruikang K

2017-06-01

When using optical coherence tomography angiography (OCTA), the development of artifacts due to involuntary movements can severely compromise the visualization and subsequent quantitation of tissue microvasculatures. To correct such an occurrence, we propose a motion compensation method to eliminate artifacts from human skin OCTA by means of step-by-step rigid affine registration, rigid subpixel registration, and nonrigid B-spline registration. To accommodate this remedial process, OCTA is conducted using two matching all-depth volume scans. Affine transformation is first performed on the large vessels of the deep reticular dermis, and then the resulting affine parameters are applied to all-depth vasculatures with a further subpixel registration to refine the alignment between superficial smaller vessels. Finally, the coregistration of both volumes is carried out to result in the final artifact-free composite image via an algorithm based upon cubic B-spline free-form deformation. We demonstrate that the proposed method can provide a considerable improvement to the final en face OCTA images with substantial artifact removal. In addition, the correlation coefficients and peak signal-to-noise ratios of the corrected images are evaluated and compared with those of the original images, further validating the effectiveness of the proposed method. We expect that the proposed method can be useful in improving qualitative and quantitative assessment of the OCTA images of scanned tissue beds.

Recent improvements to Binding MOAD: a resource for protein-ligand binding affinities and structures.

PubMed

Ahmed, Aqeel; Smith, Richard D; Clark, Jordan J; Dunbar, James B; Carlson, Heather A

2015-01-01

For over 10 years, Binding MOAD (Mother of All Databases; http://www.BindingMOAD.org) has been one of the largest resources for high-quality protein-ligand complexes and associated binding affinity data. Binding MOAD has grown at the rate of 1994 complexes per year, on average. Currently, it contains 23,269 complexes and 8156 binding affinities. Our annual updates curate the data using a semi-automated literature search of the references cited within the PDB file, and we have recently upgraded our website and added new features and functionalities to better serve Binding MOAD users. In order to eliminate the legacy application server of the old platform and to accommodate new changes, the website has been completely rewritten in the LAMP (Linux, Apache, MySQL and PHP) environment. The improved user interface incorporates current third-party plugins for better visualization of protein and ligand molecules, and it provides features like sorting, filtering and filtered downloads. In addition to the field-based searching, Binding MOAD now can be searched by structural queries based on the ligand. In order to remove redundancy, Binding MOAD records are clustered in different families based on 90% sequence identity. The new Binding MOAD, with the upgraded platform, features and functionalities, is now equipped to better serve its users. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

Methods and Devices for Modifying Active Paths in a K-Delta-1-Sigma Modulator

NASA Technical Reports Server (NTRS)

Ardalan, Sasan (Inventor)

2017-01-01

The invention relates to an improved K-Delta-1-Sigma Modulators (KG1Ss) that achieve multi GHz sampling rates with 90 nm and 45 nm CMOS processes, and that provide the capability to balance performance with power in many applications. The improved KD1Ss activate all paths when high performance is needed (e.g. high bandwidth), and reduce the effective bandwidth by shutting down multiple paths when low performance is required. The improved KD1Ss can adjust the baseband filtering for lower bandwidth, and can provide large savings in power consumption while maintaining the communication link, which is a great advantage in space communications. The improved KD1Ss herein provides a receiver that adjusts to accommodate a higher rate when a packet is received at a low bandwidth, and at a initial lower rate, power is saved by turning off paths in the KD1S Analog to Digital Converter, and where when a higher rate is required, multiple paths are enabled in the KD1S to accommodate the higher band widths.

Space Station Human Factors Research Review. Volume 1: EVA Research and Development

NASA Technical Reports Server (NTRS)

Cohen, Marc M. (Editor); Vykukal, H. C. (Editor)

1988-01-01

An overview is presented of extravehicular activity (EVA) research and development activities at Ames. The majority of the program was devoted to presentations by the three contractors working in parallel on the EVA System Phase A Study, focusing on Implications for Man-Systems Design. Overhead visuals are included for a mission results summary, space station EVA requirements and interface accommodations summary, human productivity study cross-task coordination, and advanced EVAS Phase A study implications for man-systems design. Articles are also included on subsea approach to work systems development and advanced EVA system design requirements.

Space Shuttle Payload Information Source

NASA Technical Reports Server (NTRS)

Griswold, Tom

2000-01-01

The Space Shuttle Payload Information Source Compact Disk (CD) is a joint NASA and USA project to introduce Space Shuttle capabilities, payload services and accommodations, and the payload integration process. The CD will be given to new payload customers or to organizations outside of NASA considering using the Space Shuttle as a launch vehicle. The information is high-level in a visually attractive format with a voice over. The format is in a presentation style plus 360 degree views, videos, and animation. Hyperlinks are provided to connect to the Internet for updates and more detailed information on how payloads are integrated into the Space Shuttle.

Functional vision in children with perinatal brain damage.

PubMed

Alimović, Sonja; Jurić, Nikolina; Bošnjak, Vlatka Mejaški

2014-09-01

Many authors have discussed the effects of visual stimulations on visual functions, but there is no research about the effects on using vision in everyday activities (i.e. functional vision). Children with perinatal brain damage can develop cerebral visual impairment with preserved visual functions (e.g. visual acuity, contrast sensitivity) but poor functional vision. Our aim was to discuss the importance of assessing and stimulating functional vision in children with perinatal brain damage. We assessed visual functions (grating visual acuity, contrast sensitivity) and functional vision (the ability of maintaining visual attention and using vision in communication) in 99 children with perinatal brain damage and visual impairment. All children were assessed before and after the visual stimulation program. Our first assessment results showed that children with perinatal brain damage had significantly more problems in functional vision than in basic visual functions. During the visual stimulation program both variables of functional vision and contrast sensitivity improved significantly, while grating acuity improved only in 2.7% of children. We also found that improvement of visual attention significantly correlated to improvement on all other functions describing vision. Therefore, functional vision assessment, especially assessment of visual attention is indispensable in early monitoring of child with perinatal brain damage.

Effective utility accommodation : final report.

DOT National Transportation Integrated Search

2009-12-08

The report presents research regarding methods to improve project delivery times and minimize construction delays due to utility coordination by conducting a study of the current best practices used by six (6) similar state transportation departments...

Lack of oblique astigmatism in the chicken eye.

PubMed

Maier, Felix M; Howland, Howard C; Ohlendorf, Arne; Wahl, Siegfried; Schaeffel, Frank

2015-04-01

Primate eyes display considerable oblique off-axis astigmatism which could provide information on the sign of defocus that is needed for emmetropization. The pattern of peripheral astigmatism is not known in the chicken eye, a common model of myopia. Peripheral astigmatism was mapped out over the horizontal visual field in three chickens, 43 days old, and in three near emmetropic human subjects, average age 34.7years, using infrared photoretinoscopy. There were no differences in astigmatism between humans and chickens in the central visual field (chicks -0.35D, humans -0.65D, n.s.) but large differences in the periphery (i.e. astigmatism at 40° in the temporal visual field: humans -4.21D, chicks -0.63D, p<0.001, unpaired t-test). The lack of peripheral astigmatism in chicks was not due to differences in corneal shape. Perhaps related to their superior peripheral optics, we found that chickens had excellent visual performance also in the far periphery. Using an automated optokinetic nystagmus paradigm, no difference was observed in spatial visual performance with vision restricted to either the central 67° of the visual field or to the periphery beyond 67°. Accommodation was elicited by stimuli presented far out in the visual field. Transscleral images of single infrared LEDs showed no sign of peripheral astigmatism. The chick may be the first terrestrial vertebrate described to lack oblique astigmatism. Since corneal shape cannot account for the difference in astigmatism in humans and chicks, it must trace back to the design of the crystalline lens. The lack of peripheral astigmatism in chicks also excludes a role in emmetropization. Copyright © 2015 Elsevier Ltd. All rights reserved.

Self Reflections of Undergraduate Students on Using Web-Supported Counterintuitive Science Demonstrations

NASA Astrophysics Data System (ADS)

Kumar, David Devraj; Dunn, Jessica

2018-03-01

Analysis of self-reflections of undergraduate education students in a project involving web-supported counterintuitive science demonstrations is reported in this paper. Participating students (N = 19) taught science with counterintuitive demonstrations in local elementary school classrooms and used web-based resources accessed via wireless USB adapters. Student reflections to seven questions were analyzed qualitatively using four components of reflection (meeting objectives/perception of learning, dynamics of pedagogy, special needs accommodations, improving teaching) deriving 27 initial data categories and 12 emergent themes. Overall the undergraduates reported meeting objectives, engaging students in pedagogically relevant learning tasks including, providing accommodations to students with special needs, and gaining practice and insight to improve their own teaching. Additional research is needed to arrive at generalizable findings concerning teaching with web-supported counterintuitive science demonstrations in elementary classrooms.

Optimizing fiducial visibility on periodically acquired megavoltage and kilovoltage image pairs during prostate volumetric modulated arc therapy

PubMed Central

Zhang, Pengpeng; Happersett, Laura; Ravindranath, Bosky; Zelefsky, Michael; Mageras, Gig; Hunt, Margie

2016-01-01

Purpose: Robust detection of implanted fiducials is essential for monitoring intrafractional motion during hypofractionated treatment. The authors developed a plan optimization strategy to ensure clear visibility of implanted fiducials and facilitate 3D localization during volumetric modulated arc therapy (VMAT). Methods: Periodic kilovoltage (kV) images were acquired at 20° gantry intervals and paired with simultaneously acquired 4.4° short arc megavoltage digital tomosynthesis (MV-DTS) to localize three fiducials during VMAT delivery for hypofractionated prostate cancer treatment. Beginning with the original optimized plan, control point segments where fiducials were consistently blocked by multileaf collimator (MLC) within each 4.4° MV-DTS interval were first identified. For each segment, MLC apertures were edited to expose the fiducial that led to the least increase in the cost function. Subsequently, MLC apertures of all control points not involved with fiducial visualization were reoptimized to compensate for plan quality losses and match the original dose–volume histogram. MV dose for each MV-DTS was also kept above 0.4 MU to ensure acceptable image quality. Different imaging (gantry) intervals and visibility margins around fiducials were also evaluated. Results: Fiducials were consistently blocked by the MLC for, on average, 36% of the imaging control points for five hypofractionated prostate VMAT plans but properly exposed after reoptimization. Reoptimization resulted in negligible dosimetric differences compared with original plans and outperformed simple aperture editing: on average, PTV D98 recovered from 87% to 94% of prescription, and PTV dose homogeneity improved from 9% to 7%. Without violating plan objectives and compromising delivery efficiency, the highest imaging frequency and largest margin that can be achieved are a 10° gantry interval, and 15 mm, respectively. Conclusions: VMAT plans can be made to accommodate MV-kV imaging of fiducials. Fiducial visualization rate and workflow efficiency are significantly improved with an automatic modification and reoptimization approach. PMID:27147314

A double dissociation of the acuity and crowding limits to letter identification, and the promise of improved visual screening

PubMed Central

Song, Shuang; Levi, Dennis M.; Pelli, Denis G.

2014-01-01

Here, we systematically explore the size and spacing requirements for identifying a letter among other letters. We measure acuity for flanked and unflanked letters, centrally and peripherally, in normals and amblyopes. We find that acuity, overlap masking, and crowding each demand a minimum size or spacing for readable text. Just measuring flanked and unflanked acuity is enough for our proposed model to predict the observer's threshold size and spacing for letters at any eccentricity. We also find that amblyopia in adults retains the character of the childhood condition that caused it. Amblyopia is a developmental neural deficit that can occur as a result of either strabismus or anisometropia in childhood. Peripheral viewing during childhood due to strabismus results in amblyopia that is crowding limited, like peripheral vision. Optical blur of one eye during childhood due to anisometropia without strabismus results in amblyopia that is acuity limited, like blurred vision. Furthermore, we find that the spacing:acuity ratio of flanked and unflanked acuity can distinguish strabismic amblyopia from purely anisometropic amblyopia in nearly perfect agreement with lack of stereopsis. A scatter diagram of threshold spacing versus acuity, one point per patient, for several diagnostic groups, reveals the diagnostic power of flanked acuity testing. These results and two demonstrations indicate that the sensitivity of visual screening tests can be improved by using flankers that are more tightly spaced and letter like. Finally, in concert with Strappini, Pelli, Di Pace, and Martelli (submitted), we jointly report a double dissociation between acuity and crowding. Two clinical conditions—anisometropic amblyopia and apperceptive agnosia—each selectively impair either acuity A or the spacing:acuity ratio S/A, not both. Furthermore, when we specifically estimate crowding, we find a double dissociation between acuity and crowding. Models of human object recognition will need to accommodate this newly discovered independence of acuity and crowding. PMID:24799622

Randomized clinical trial of treatments for symptomatic convergence insufficiency in children.

PubMed

2008-10-01

To compare home-based pencil push-ups (HBPP), home-based computer vergence/accommodative therapy and pencil push-ups (HBCVAT+), office-based vergence/accommodative therapy with home reinforcement (OBVAT), and office-based placebo therapy with home reinforcement (OBPT) as treatments for symptomatic convergence insufficiency. In a randomized clinical trial, 221 children aged 9 to 17 years with symptomatic convergence insufficiency were assigned to 1 of 4 treatments. Convergence Insufficiency Symptom Survey score after 12 weeks of treatment. Secondary outcomes were near point of convergence and positive fusional vergence at near. After 12 weeks of treatment, the OBVAT group's mean Convergence Insufficiency Symptom Survey score (15.1) was statistically significantly lower than those of 21.3, 24.7, and 21.9 in the HBCVAT+, HBPP, and OBPT groups, respectively (P < .001). The OBVAT group also demonstrated a significantly improved near point of convergence and positive fusional vergence at near compared with the other groups (P

A new ChainMail approach for real-time soft tissue simulation.

PubMed

Zhang, Jinao; Zhong, Yongmin; Smith, Julian; Gu, Chengfan

2016-07-03

This paper presents a new ChainMail method for real-time soft tissue simulation. This method enables the use of different material properties for chain elements to accommodate various materials. Based on the ChainMail bounding region, a new time-saving scheme is developed to improve computational efficiency for isotropic materials. The proposed method also conserves volume and strain energy. Experimental results demonstrate that the proposed ChainMail method can not only accommodate isotropic, anisotropic and heterogeneous materials but also model incompressibility and relaxation behaviors of soft tissues. Further, the proposed method can achieve real-time computational performance.

Visual improvement for bad handwriting based on Monte-Carlo method

NASA Astrophysics Data System (ADS)

Shi, Cao; Xiao, Jianguo; Xu, Canhui; Jia, Wenhua

2014-03-01

A visual improvement algorithm based on Monte Carlo simulation is proposed in this paper, in order to enhance visual effects for bad handwriting. The whole improvement process is to use well designed typeface so as to optimize bad handwriting image. In this process, a series of linear operators for image transformation are defined for transforming typeface image to approach handwriting image. And specific parameters of linear operators are estimated by Monte Carlo method. Visual improvement experiments illustrate that the proposed algorithm can effectively enhance visual effect for handwriting image as well as maintain the original handwriting features, such as tilt, stroke order and drawing direction etc. The proposed visual improvement algorithm, in this paper, has a huge potential to be applied in tablet computer and Mobile Internet, in order to improve user experience on handwriting.

Family involvement in the psychological treatment of obsessive-compulsive disorder: A meta-analysis

PubMed Central

Thompson-Hollands, Johanna; Edson, Aubrey; Tompson, Martha C.; Comer, Jonathan S.

2014-01-01

Psychological treatments for OCD are increasingly aimed at improving outcomes by directly incorporating family members to address family disruption, dysfunction, or symptom accommodation. Much remains to be learned about the pooled effects of “family-inclusive treatment” (FIT) for OCD and factors that may explain variation in response. Random-effects meta-analytic procedures were conducted to empirically evaluate the overall effect of FITs on OCD, and treatment moderators. Study search criteria yielded 29 studies examining FIT response in 1,366 OCD patients. Outcome variables included OCD symptoms and global functioning. Examined moderators included age group, gender, minority status, treatment length and format, and inclusion of specific family-focused treatment elements. FITs for OCD demonstrated a large overall effect on OCD symptoms (pooled d = 1.68, SE = 0.14) and global functioning (pooled d = 0.98, SE = 0.14). Moderator analyses found that individual family treatments (versus group) and FITs targeting family accommodation of symptoms (versus those that did not target accommodation) were associated with greater improvements in patient functioning. Results indicate a robust overall response to FITs for OCD and clarify key moderators that inform optimal circumstances for effective treatment. Findings underscore the need for continued momentum in the development, evaluation, and dissemination of FITs for OCD. PMID:24798816

The needs of parents of children with visual impairment studying in mainstream schools in Hong Kong.

PubMed

Lee, Florence M Y; Tsang, Janice F K; Chui, Mandy M Y

2014-10-01

This study attempted to use a validated and standardised psychometric tool to identify the specific needs of parents of children with visual impairment studying in mainstream schools in Hong Kong. The second aim was to compare their needs with those of parents of mainstream school children without special education needs and parents having children with learning and behavioural problems. Cross-sectional survey. Mainstream schools in Hong Kong. Parents of 30 children with visual impairment who were studying in mainstream schools and attended assessment by optometrists at Child Assessment Service between May 2009 and June 2010 were recruited in the study (visual impairment group). Parents of 45 children with learning and behavioural problems recruited from two parent support groups (learning and behavioural problems group), and parents of 233 children without special education needs studying in mainstream schools recruited in a previous validation study on Service Needs Questionnaire (normal group) were used for comparison. Participants were invited to complete a self-administered Service Needs Questionnaire and a questionnaire on demographics of the children and their responding parents. The visual impairment group was asked additional questions about the ability of the child in coping and functioning in academic and recreational activities. Needs expressed by parents of the visual impairment group were significantly higher than those of parents of the normal group, and similar to those in the learning and behavioural problems group. Parents of children with visual impairment expressed more needs for future education and school support than resources for dealing with personal and family stress. Service needs of children with visual impairment and their families are high, particularly for future education and school support. More study on the various modes of accommodation for children with visual impairment and more collaborative work among different partners working in the field of rehabilitation will foster better service for these children and their families.

Use of subjective and objective criteria to categorise visual disability.

PubMed

Kajla, Garima; Rohatgi, Jolly; Dhaliwal, Upreet

2014-04-01

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

Attention and Visual Motor Integration in Young Children with Uncorrected Hyperopia.

PubMed

Kulp, Marjean Taylor; Ciner, Elise; Maguire, Maureen; Pistilli, Maxwell; Candy, T Rowan; Ying, Gui-Shuang; Quinn, Graham; Cyert, Lynn; Moore, Bruce

2017-10-01

Among 4- and 5-year-old children, deficits in measures of attention, visual-motor integration (VMI) and visual perception (VP) are associated with moderate, uncorrected hyperopia (3 to 6 diopters [D]) accompanied by reduced near visual function (near visual acuity worse than 20/40 or stereoacuity worse than 240 seconds of arc). To compare attention, visual motor, and visual perceptual skills in uncorrected hyperopes and emmetropes attending preschool or kindergarten and evaluate their associations with visual function. Participants were 4 and 5 years of age with either hyperopia (≥3 to ≤6 D, astigmatism ≤1.5 D, anisometropia ≤1 D) or emmetropia (hyperopia ≤1 D; astigmatism, anisometropia, and myopia each <1 D), without amblyopia or strabismus. Examiners masked to refractive status administered tests of attention (sustained, receptive, and expressive), VMI, and VP. Binocular visual acuity, stereoacuity, and accommodative accuracy were also assessed at near. Analyses were adjusted for age, sex, race/ethnicity, and parent's/caregiver's education. Two hundred forty-four hyperopes (mean, +3.8 ± [SD] 0.8 D) and 248 emmetropes (+0.5 ± 0.5 D) completed testing. Mean sustained attention score was worse in hyperopes compared with emmetropes (mean difference, -4.1; P < .001 for 3 to 6 D). Mean Receptive Attention score was worse in 4 to 6 D hyperopes compared with emmetropes (by -2.6, P = .01). Hyperopes with reduced near visual acuity (20/40 or worse) had worse scores than emmetropes (-6.4, P < .001 for sustained attention; -3.0, P = .004 for Receptive Attention; -0.7, P = .006 for VMI; -1.3, P = .008 for VP). Hyperopes with stereoacuity of 240 seconds of arc or worse scored significantly worse than emmetropes (-6.7, P < .001 for sustained attention; -3.4, P = .03 for Expressive Attention; -2.2, P = .03 for Receptive Attention; -0.7, P = .01 for VMI; -1.7, P < .001 for VP). Overall, hyperopes with better near visual function generally performed similarly to emmetropes. Moderately hyperopic children were found to have deficits in measures of attention. Hyperopic children with reduced near visual function also had lower scores on VMI and VP than emmetropic children.