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Author: Kim Hoover
Publisher:
ISBN:
Category : Eye
Languages : en
Pages : 66
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Author: Kim Hoover
Publisher:
ISBN:
Category : Eye
Languages : en
Pages : 66
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Author: Albert Burg
Publisher:
ISBN:
Category :
Languages : en
Pages : 1
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Author: Mariko Hirano
Publisher:
ISBN:
Category : Visual acuity
Languages : en
Pages : 156
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Purpose: When a target is in motion, two thresholds can be measured: dynamic visual acuity (DVA, the smallest target size at which an observer can resolve target detail) and speed threshold (the fastest target speed at which an observer can resolve target detail). Many different factors can influence DVA and speed threshold, including target trajectory, velocity, size, contrast, and colour. The limitation with research to date is that there is no standardized, validated tool with which to assess either DVA or speed thresholds. The Vision & Motor Performance Lab at the University of Waterloo School of Optometry has recently developed a distance visual acuity chart (moV&, V&MP Vision Suite) that can measure static visual acuity, DVA, and speed thresholds. moV& allows for the specifications of target trajectory, speed, size, contrast, and colour of both the target and background when measuring DVA. The primary objective of this dissertation is to examine the validity and repeatability of the high contrast (100% contrast), low contrast (61% and 20% contrast), and colour (red target on a white background and white target on a blue background) functions of moV&. If reliable, the data will then be used to examine the effect of target trajectory, speed, and size on DVA and speed threshold. Methods: Three cross-sectional studies were conducted in order to address the research objectives. Each experiment required participants to attend 2 study visits separated by a minimum of 14 days. All participants completed the static visual acuity tests before completing the dynamic tests in a randomized order. Experiment 1 (n = 25) determined the validity and repeatability of moV& using targets at 100% contrast. At each visit, static and dynamic visual acuity was measured using Snellen, ETDRS, and moV& charts. Experiment 2 determined the repeatability of the low contrast and coloured functions of moV&. Participants were assigned to either the contrast (n=21) or colour (n=21) study block. For the contrast block, low contrast (61% and 20% contrast) static and dynamic visual acuities were measured using Snellen and moV& charts. For the colour block, coloured optotype and background (red target on a white background, white target on a blue background) static and dynamic visual acuities were measured using the ETDRS and moV& charts. Experiment 3 (n = 67) examined the effect of target trajectory, speed, and size on DVA and speed threshold using the targets studied in Experiments 1-2. Data from Experiments 1 and 2 was used to determine the effect of target trajectory, speed, and size on DVA and speed threshold. A repeated measure ANOVA was used to compare static moV& visual acuity to ETDRS and Snellen charts. Test-retest reliability was determined via Lin's correlation coefficient of concordance (CCC). Three-way ANOVA was used to determine the effect of trajectory, speed, and size on DVA and speed thresholds. Results: moV& yielded similar high contrast static visual acuity when compared to the EDTRS and Snellen charts. All high contrast static and dynamic visual acuities demonstrate good test-retest repeatability (CCCs ranged 0.451 to 0.953). moV& static visual acuities were significantly better than Snellen at both 61% and 20% contrast (p
Author: National Research Council
Publisher: National Academies Press
ISBN: 0309083486
Category : Social Science
Languages : en
Pages : 369
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When children and adults apply for disability benefits and claim that a visual impairment has limited their ability to function, the U.S. Social Security Administration (SSA) is required to determine their eligibility. To ensure that these determinations are made fairly and consistently, SSA has developed criteria for eligibility and a process for assessing each claimant against the criteria. Visual Impairments: Determining Eligibility for Social Security Benefits examines SSA's methods of determining disability for people with visual impairments, recommends changes that could be made now to improve the process and the outcomes, and identifies research needed to develop improved methods for the future. The report assesses tests of visual function, including visual acuity and visual fields whether visual impairments could be measured directly through visual task performance or other means of assessing disability. These other means include job analysis databases, which include information on the importance of vision to job tasks or skills, and measures of health-related quality of life, which take a person-centered approach to assessing visual function testing of infants and children, which differs in important ways from standard adult tests.
Author: John M. B. Rumpakis
Publisher:
ISBN:
Category : Visual acuity
Languages : en
Pages : 130
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Author: J.E. Bos
Publisher:
ISBN:
Category :
Languages : en
Pages : 32
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Author: Nataša Vujko Muždalo
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: National Research Council
Publisher: National Academies Press
ISBN:
Category : Medical
Languages : en
Pages : 75
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Book Description
Recent vision research has led to the emergence of new techniques that offer exciting potential for a more complete assessment of vision in clinical, industrial, and military settings. Emergent Techniques for Assessment of Visual Performance examines four areas of vision testing that offer potential for improved assessment of visual capability including: contrast sensitivity function, dark-focus of accommodation, dynamic visual acuity and dynamic depth tracking, and ambient and focal vision. In contrast to studies of accepted practices, this report focuses on emerging techniques that could help determine whether people have the vision necessary to do their jobs. In addition to examining some of these emerging techniques, the report identifies their usefulness in predicting performance on other visual and visual-motor tasks, and makes recommendations for future research. Emergent Techniques for Assessment of Visual Performance provides summary recommendations for research that will have significant value and policy implications for the next 5 to 10 years. The content and conclusions of this report can serve as a useful resource for those responsible for screening industrial and military visual function.
Author: Leah Richards
Publisher:
ISBN:
Category :
Languages : en
Pages : 52
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Author: William Alexander Bercha
Publisher:
ISBN:
Category :
Languages : en
Pages : 62
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