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At least 973 records · Page 54Linked to original sources
PubMed2003

Testing different interpretations for the mistaken belief that rays exit the eyes during vision.

Research has shown that children and adults believe that emissions from the eye occur during the act of vision. Such beliefs are similar to ancient extramission theories of perception. In Study 1, the authors tested the idea that extramission beliefs might stem from people's thinking about what might occur during vision as opposed to what is necessary for seeing. Training participants to think about what is necessary for vision, however, had no effect on extramission responses. The results of Study 2 indicated that emphasizing the idea of visual input led to a decline in extramission responses and supported the hypothesis that extramission notions stem from the outer-oriented phenomenology of vision.

Adult↗
PubMed2004

Incorporating vision and hearing tests into aged care assessment: methods and the pilot study.

PURPOSE: Vision and hearing impairments are frequent in older people and may contribute to their reliance on aged care services. This study aims to assess whether incorporating vision and hearing screening into routine aged care assessments and provision of appropriate health care services will influence health outcomes of older individuals. METHODS: The proposed project is a 2 x 2 factorial design randomized controlled trial. The pilot study recruited 208 participants aged 65+ years attending an aged care assessment center at Westmead Hospital, Sydney, who were randomly allocated to one of four groups: vision and hearing tests, vision tests only, hearing tests only, or neither. Face-to-face interviews with all participants were conducted. Questionnaires included Activity of Daily Living (ADL), 36-item Short-Form health survey (SF-36), Mini-Mental State Exam (MMSE) and questions about use of health care and community support services. Participants will be re-examined after 12 months to assess changes over time in quality-of-life, physical and cognitive function, incident falls and use of health and community aged care services.

Aged↗
PubMed2006

The reliability of data collection periods of personal costs associated with vision impairment.

PURPOSE: To determine the reliability of vision-related personal costs collected over 1, 3 and 6 months (extrapolated to 12 months) compared to one-year data. METHODS: Participants of any age, with a presenting visual acuity of < 20/40 in the better eye and an ability to converse in English, were recruited. Monthly cost diaries, in large print and electronic copies with instructions available in audio and Braille, were used prospectively to collect personal costs. The personal expenses were grouped under four categories, namely: (a) medicines, products and equipment, (b) health and community services, (c) informal care and support and (d) other expenses. Sociodemographic and clinical data were also collected. RESULTS: 104 participants (59 females) with a mean age of 64 years completed the 12-months diaries. Almost 40% of the participants had severe visual impairment (< 20/200) in the better eye and the most common cause of vision loss was AMD (n=40; 38%). The mean total personal costs collected from the 12-months diaries were 3,330+/-2,887 AUS dollars. There were no significant differences between the 12-months data and extrapolated 1, 3 and 6-months diaries (t-tests; p=0.17, 0.89 and 0.73, respectively). However, the 1-month variation was substantially larger (SD+/-5,860) compared to the 3-month and 6-month variances (SD+/-3,037 and 3,030, respectively) for total costs. Also, compared to the 12-months diaries, the 1-month data consistently recorded the weakest correlation coefficients for all cost categories compared to the other time intervals. CONCLUSIONS: Given that diary completion can be particularly challenging for individuals with impaired vision, a minimum 3-months data collection period can provide reliable estimates of annual costs associated with vision impairment.

Cost of Illness↗
PubMed1989

Risk of imbalance in elderly people with impaired hearing or vision.

We evaluated the effect of impaired hearing and vision on balance in a sample of 977 elderly people residing in the community. Of the sample, 21% reported balance problems, 27% vision problems, and 30% hearing problems. The increased relative risk for balance problems was 1.7 for each 10-year age increment. Women were 1.7 times more likely to report balance problems than were men. The relative risk of imbalance with impaired vision decreased with age from 2.8 in those aged 65-69 years to 1.0 in those over 85 years. There was no age-hearing interaction, the relative risk for impaired hearing is 1.6. It appears that impaired vision and hearing are important risk factors for imbalance and perhaps falls and injury.

Accidental Falls↗
PubMed1983

Selective disturbance of movement vision after bilateral brain damage.

A patient who suffered bilateral posterior brain damage exhibited disturbance of movement vision in a rather pure form. The patient had no impression of movement in depth, and could only discriminate between a stationary and a moving target in the periphery of her otherwise intact visual fields. She had some movement vision in the central part of her visual fields, provided that target velocity did not exceed 10 deg/s. Neither did she possess visual movement after effects nor apparent (phi) visual movement. In addition, visually guided eye and finger movements were impaired. In contrast to the disturbance of movement perception in the visual modality, movement perception elicited by acoustic and tactile stimuli was not impaired. On the basis of the localization of the cerebral damage (as judged by CT scanning and neuropsychological testing) it is concluded that the observed disorder in movement vision is due to bilateral cerebral lesions affecting the lateral temporo-occipital cortex and the underlying white matter. The selectivity of the visual disturbance supports the idea that movement vision is a separate visual function depending on neuronal mechanisms beyond the primary visual cortex.

Adult↗
PubMed1991

Disturbance of movement vision after bilateral posterior brain damage. Further evidence and follow up observations.

In 1983 we reported in this Journal a patient who suffered a disturbance of movement vision in a relatively pure form. This uncommon cerebral visual deficit resulted as a consequence of bilateral brain damage affecting the lateral temporo-occipital cortex and the underlying white matter. In this paper we present further evidence for the selectivity of the movement vision deficit. Furthermore, follow-up examination did not reveal any significant change which indicates that the disorder appears irreversible. Magnetic Resonance Imaging (MRI) shows bilateral lesions involving the upper (cranial) part of the occipital gyri and the adjacent portion of the middle temporal gyri, with the main focus of damage in the upper (cranial) banks of the anterior occipital sulcus. In addition, cortico-cortical fibre pathways interconnecting occipital, temporal and parietal 'visual' areas are also affected bilaterally. The selectivity of the movement vision deficit and the irreversibility of the disorder strongly support the idea that movement vision is a separate function which is subserved by a visual pathway specialized for the processing of visual motion.

Brain Diseases↗
PubMed2005

Statistical and molecular analyses of evolutionary significance of red-green color vision and color blindness in vertebrates.

Red-green color vision is strongly suspected to enhance the survival of its possessors. Despite being red-green color blind, however, many species have successfully competed in nature, which brings into question the evolutionary advantage of achieving red-green color vision. Here, we propose a new method of identifying positive selection at individual amino acid sites with the premise that if positive Darwinian selection has driven the evolution of the protein under consideration, then it should be found mostly at the branches in the phylogenetic tree where its function had changed. The statistical and molecular methods have been applied to 29 visual pigments with the wavelengths of maximal absorption at approximately 510-540 nm (green- or middle wavelength-sensitive [MWS] pigments) and at approximately 560 nm (red- or long wavelength-sensitive [LWS] pigments), which are sampled from a diverse range of vertebrate species. The results show that the MWS pigments are positively selected through amino acid replacements S180A, Y277F, and T285A and that the LWS pigments have been subjected to strong evolutionary conservation. The fact that these positively selected M/LWS pigments are found not only in animals with red-green color vision but also in those with red-green color blindness strongly suggests that both red-green color vision and color blindness have undergone adaptive evolution independently in different species.

Animals↗
PubMed1992

Development of the 'Activities of Daily Vision Scale'. A measure of visual functional status.

To develop a method for the evaluation of visual function in subjects with cataracts, the authors identified 20 visual activities and categorized them into five subscales (distance vision, near vision, glare disability, night driving, and daytime driving) that comprised the Activities of Daily Vision Scale (ADVS). Each subscale in the ADVS was scored between 100 (no visual difficulty) and 0 (inability to perform the activity because of visual difficulty). In 334 subjects scheduled for cataract extraction (mean age 75 +/- 9 years, 67% women), ADVS scores (mean +/- standard deviation) for each subscale ranged from 44 +/- 31 for night driving to 72 +/- 24 for near vision activities. When administered by telephone, inter-rater reliability coefficients (r) were 0.82 to 0.97 (P < 0.001) for each of the subscales, and test-retest reliability was 0.87 for the scale overall. Cronbach's coefficient alpha was very high for both the in-person (alpha = 0.94) and telephone (alpha = 0.91) formats. Criterion validity, the correlation between visual loss and ADVS score, was -0.37 (P < 0.001) when the ADVS was administered in person and -0.39 (P < 0.001) when it was administered by telephone. Content validity as assessed with factor analysis showed that 88% of the variance of the principal components weighted on one factor. The authors conclude that substantial visual disability is not captured by routine visual testing and that the ADVS is a reliable and valid measure of patient's perception of visual functional impairment.

Activities of Daily Living↗
PubMed1977

A marble used as a low-vision reading aid: a case report.

An unusual low-vision remedy was encountered in which a simple dime-store marble was used in near vision tasks. Although the marble was found satisfactory as a low-vision aid, the patient could be better assisted with a commercially available magnifier of lesser dioptric power. This case serves to demonstrate a patient's ingenuity in independently solving his own low vision problem.

Creativity↗
PubMed1980

Cool white, Ultralume, and Vita-Lite fluorescent lamps for use in color vision testing.

Thirty-one normal and 20 color vision-deficient persons were tested with the Hardy-Rand-Rittler (HRR) Pseudoisochromatic Plates, Farnsworth's D-15 and 100-Hue tests, and the Davidson & Hemmendinger (D & H) Color Rule using Vita-Lite, Ultralume, and Cool White fluorescent lamps to determine their usefulness for color vision measurement. The persons with deficient color vision were classified with a Nagel anomaloscope. The Macbeth Easel lamp was the reference for determining relative lamp performance. No normal was misclassified with any of the lamps. Scores with the Vita-Lite lamp were qualitatively and quantitatively most similar to those with the Macbeth lamp. The Ultralume gave intermediate results, and the Cool White was the least satisfactory substitute. Norms for the metameric D & H Color Rule for each lamp were different, which prevented intercomparisons. Best separation of the scores of deficient from normal persons with the D & H Rule occurred with the Macbeth and Vita-Lite lamps. Better performance with the Vita-Lite and Ultralume lamps can be expected from protans with the HRR and 100-Hue Tests and poorer performances from deutans on the HRR tests than with the standard Macbeth Lamp. The Cool White lamp was judged an unsuitable substitute for color vision testing.

Adolescent↗
PubMed1982

A survey and evaluation of lantern tests of color vision.

This paper reports a survey of the lantern tests that have been or are used to evaluate the color vision of people who wish to enter occupations that require the ability to recognize colored signal lights reliably. The origin of each lantern is traced and the principal features of each are described. The available data concerning failure rate of normals, the failure rate of people with defective color vision, and the extent to which scores on lantern tests correlate with field trials are summarized. Despite the fact that lantern tests have been used since the turn of the century and that some lanterns have been in use for more than 30 years and some for much longer periods, the available validation data are incomplete and sometimes conflicting. However, the data do indicate that some lanterns may fail a significant proportion of normals and that there is considerable variation between lanterns in the proportion of color vision defectives that will fail. It is noted that most lanterns will pass some protanomals despite their reduced sensitivity to red light and correspondingly short visual range for red signals. The view of Cameron is supported that a more rational approach would be to made a clinical diagnosis of the type of color vision defect, to reject protanopes, deuteranopes, and protanomals and to use a lantern test only to determine which deuteranomals should be accepted.

Aerospace Medicine↗
PubMed1984

A new contrast sensitivity vision test chart.

A new contrast sensitivity vision chart has been tested and compared to an automated video-based vision tester on 83 observers whose ages ranged from 9 to 75 years. Good agreement was found between the contrast sensitivity measurements obtained from the vision chart and the automated tester for similar population and age variations. These results suggest that vision test charts can be developed to provide useful contrast sensitivity psychometric functions and yet be as simple to use as present eye charts.

Adolescent↗
PubMed1986

Motion sensitivity in central and peripheral vision.

The visual resolution of motion is important both for indicating the presence of moving objects and for assisting locomotion and spatial orientation. Additionally, motion may enhance the visibility of low contrast features of the environment. For patients with reduced central vision, these functions may be especially significant as the detection of motion is superior to the ability to resolve stationary detail in peripheral vision. The present paper analyzes the effects of specific stimulus variables on motion sensitivity in both central and peripheral vision. Implications of these findings for low vision patients are discussed.

Humans↗
PubMed1986

Contribution of vision variables to mobility in age-related maculopathy patients.

Can mobility performance be predicted from measures of vision function? This study addressed this question by measuring a series of vision variables including visual acuity, visual fields, and differential motion sensitivity in a group of patients with age-related maculopathy (ARM) and a group of age-matched normals. Mobility performance at three adaptation levels was determined objectively on an indoor course. The results indicate that for the patients with ARM, mobility variables can be predicted from measures of vision function, including differential velocity sensitivity, and that simple variables such as time taken to complete the course and average speed are those which relate best to vision.

Aging↗
PubMed1991

Comparison of reading speed in normal observers through different forms of equivalent power low vision devices.

Compensation at near for vision loss can be achieved using a variety of equivalent forms of low vision magnifiers. Each has inherent advantages and disadvantages in terms of field, working distance, etc. We compared the reading speed of 60 trained, normal observers with 4 commonly prescribed types of low vision devices of +12 D equivalent power (spectacles, hand magnifier, stand magnifier, and telemicroscope) to their normal reading speed. Although there was individual variance in performance, reading speed with all the devices was generally within 20% of normal reading speed. Implications are that in terms of differences in reading speed for normals, the form of the low vision device is not as significant as acquiring proficiency in the use of the selected device.

Adult↗
PubMed1991

Reading speed through different equivalent power low vision devices with identical field of view.

Adequate reading speed is one of the criteria low vision patients may use to assist them when they are comparing and selecting equivalent power low vision devices. Inherently, various optical devices of equivalent power will produce different fields of view. We compared the reading speed of 32 trained, normal observers with 4 commonly prescribed types of low vision devices of +12 D equivalent power (spectacles, hand magnifier, stand magnifier, and telemicroscope) which were modified to provide nearly identical fields of view. Our results show that only the reading speed obtained with the telemicroscope was significantly different from those of the other systems (p less than 0.01). Implications are that the field of view provided by a low vision device is the primary parameter limiting reading speed of equivalent power devices.

Adult↗
PubMed1993

An analysis of the role of vision anomalies in reading interference.

Several reviews of the literature have shown a relation between vision anomalies and reading problems. The studies have been correlational - comparative in nature and thus have not established causal relations. This paper suggests that before experimental studies are conducted to establish causation, studies of the process by which vision anomalies produce reading interference need to be conducted. The paper discusses the factors to consider in studying vision and reading interference. The factors are: nature of the vision anomaly, type and severity of symptoms produced, type of reading interference (perceptual or functional deficiency), amount and type of near task demands, reading skill, and reading development stage.

Adolescent↗
PubMed1995

Vision thresholds from psychometric analyses: alternatives to probit analysis.

Vision scientists and clinicians regularly obtain measures of vision and determine a person's vision threshold by choosing one of numerous methods of analysis. Analytical methods differ in their presumptions about the measures, in their complexity and in the ease of obtaining the threshold estimate. In light of these differences among so-called methods of psychometric analysis, the question is, "Do various analytical methods provide essentially equivalent vision threshold estimates or are there consequential differences that require consideration?" Measures of visual acuity, motion processing, and texture processing were obtained from 20 subjects. Each set of measures was analyzed by five psychometric methods: Logit Analysis, Normit Analysis, and linear regression of z-score transformed, logit transformed and untransformed probabilities vs. stimulus strength. The resulting thresholds were compared to the threshold obtained from Probit Analysis, which was used as a reference or "gold standard." Thresholds from the procedures were remarkably similar to those from Probit Analysis. In addition, examination of the speed of the procedures revealed that Probit Analysis was up to 10 times slower than some of the others. Considering the similarity of thresholds, the speed of computation, and the ease of implementation, Logit and Normit Analyses especially provide effective alternatives to the current gold standard, Probit Analysis, for the estimation of psychometric thresholds. In addition, z-score, logit, and linear regressions also produced unbiased threshold estimates under many circumstances, but the latter method should be applied with some caution.

Algorithms↗