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At least 19 recordsLinked to original sources
PubMed1988

[Measuring stereoscopic vision using a stereo distance vision instrument and a new stereo near vision instrument].

Normal stereoscopic vision is necessary for many occupations. Therefore, stereoacuity must be measured accurately. Borderline values are not yet available for existing stereo-tests or, as for haploscopic tests, their degree of difficulty is too low. In order to provide an accurate, natural measuring method for both scientific and practical applications, an existing three-rod tester was modified to convert it into a distant-vision stereo-tester, and a new near-vision stereo-tester was designed. A standardized test method was developed and borderline values were established for both units.

Accommodation, Ocular↗
PubMed1997

[Determination of far vision with DIN 58220 (criterion 6/10): computer vision test with high resolution monitor in comparison with vision charts].

BACKGROUND: The results of nearly automated computerized determination of visual acuity by PC are compared to those of card measurements. The introduction of a new measuring technique should not change the dimension--visual acuity--itself, therefore there should be no difference between the results of the conventional technique and those of the PC. METHODS: Both methods were tested in a group of subjects (N = 100) with vision between 0.1-2.5. The nearly automated technique was developed and established by our department. Like the conventional method it keeps strictly to the DIN rates. For DIN-criterion we chose for the benefit of high reproducibility 6/10. RESULTS: In spite of some deficiencies in the presentation of the Landoltrings on the monitor, our analysis presents a surprisingly good correspondence between the results of the two methods. In the analysis, we are not comparing arithmetic mean values. Instead, we examine the individual difference between the two methods in acuity steps and its these distribution within the group of subjects. No statistically provable difference can be detected. This is valid for both single visual acuity and for visual line acuity, which can also be tested with the computer aided method. CONCLUSION: We conclude that the PC proves to be an equivalent method to the measurement with cards. Thus, it is suitable for the use in daily routine of vision examination with the advantage, that the investigator has less influence on the outcome of the test.

Adult↗
PubMed2000

Design of the low vision quality-of-life questionnaire (LVQOL) and measuring the outcome of low-vision rehabilitation.

PURPOSE: To design and validate a vision-specific quality-of-life assessment tool to be used in a clinical setting to evaluate low-vision rehabilitation strategy and management. METHODS: Previous vision-related questionnaires were assessed by low-vision rehabilitation professionals and patients for relevance and coverage. The 74 items selected were pretested to ensure correct interpretation. One hundred and fifty patients with low vision completed the chosen questions on four occasions to allow the selection of the most appropriate items. The vision-specific quality of life of patients with low vision was compared with that of 70 age-matched and gender-matched patients with normal vision and before and after low-vision rehabilitation in 278 patients. RESULTS: Items that were unreliable, internally inconsistent, redundant, or not relevant were excluded, resulting in the 25-item Low Vision Quality-of-Life Questionnaire (LVQOL). Completion of the LVQOL results in a summed score between 0 (a low quality of life) and 125 (a high quality of life). The LVQOL has a high internal consistency (alpha = 0.88) and good reliability (0.72). The average LVQOL score for a population with low vision (60.9 +/- 25.1) was significantly lower than the average score of those with normal vision (100.3 +/- 20.8). Rehabilitation improved the LVQOL score of those with low vision by an average of 6.8 +/- 15.6 (17%). CONCLUSIONS: The LVQOL was shown to be an internally consistent, reliable, and fast method for measuring the vision-specific quality of life of the visually impaired in a clinical setting. It is able to quantify the quality of life of those with low vision and is useful in determining the effects of low-vision rehabilitation.

Activities of Daily Living↗
PubMed2001

Biophysical vision model and learning paradigms about vision: review.

A learning paradigm of a new biophysical vision model (BVM) is presented. It incorporates anatomical and physiological evidence from micro- and macroscopic research on vision as reported in the literature during the past five years. Anatomical and physiological vision research tends to drift away from the technological foundations of encoding and reproducing size-defined images of real ongoing life scenarios. White and color light waves reflecting life scenarios are converted by the retina to encoded electrical train pulses with attached real information to be decoded by cortical vision neurons. The BVM paradigm is based on the ideas that: (1) cinema technology reproduces real-life scenes just as the human eye sees them; (2) virtual reality and robotics are computerized replications of categorized human vision faculties in operation. We believe that vision-related technology may extend our knowledge about vision and direct vision research into new horizons. The biophysical vision model has three prerequisites: (1) The faculties of human vision must be categorized. (2) Logic circuits of the 'hardware' of neuronal vision must be present. (3) Vision faculties are operated by self-induced 'software'. Vision research may be enhanced with devices constructed according to BVM that would enable biophysical vision experiments in both humans and animals.

Animals↗
PubMed1999

Quality of life of low-vision patients and the impact of low-vision services.

PURPOSE: To investigate the functional status and quality of life of patients at a low-vision clinic and to evaluate the impact of low-vision services. METHODS: Interviews, including the Medical Outcomes Study 36-Item Short Form (SF-36), the Visual Function-14 (VF-14), and the 51-item Field Test Version of the National Eye Institute Visual Functioning Questionnaire (NEI-VFQ), were administered to 156 consecutive patients 1 week before and 3 months after their low-vision clinic visit. RESULTS: Low-vision patients scored lower (P < .001) in physical functioning and role limitations caused by physical and emotional health problems than published SF-36 scores of the age-appropriate United States normal population, patients with congestive heart failure, and clinically depressed patients. Low-vision services were associated with improvement in the subjective functional status of 150 patients (98.7%) and were rated "very useful" by 82 (53.9%) patients. The SF-36 scores did not change significantly after low-vision services. The VF-14 mean score improved from 35.8 to 41.2 (P < .001). Four NEI-VFQ subscale scores improved significantly (P < .001): general vision, near activities, distance activities, and peripheral vision. CONCLUSIONS: The SF-36, VF-14, and NEI-VFQ demonstrate that low-vision clinic patients perceive marked impairment of functional status and quality of life. Low-vision services are associated with high patient satisfaction. Vision-targeted questionnaires are more sensitive than general health-related quality of life questionnaires to changes in functional status and quality of life after low-vision services, and they may help elucidate the outcomes of low-vision services.

Adolescent↗
PubMed1995

Low vision in east African blind school students: need for optical low vision services.

AIMS: There is increasing awareness of the needs of children with low vision, particularly in developing countries where programmes of integrated education are being developed. However, appropriate low vision services are usually not available or affordable. The aims of this study were, firstly, to assess the need for spectacles and optical low vision devices in students with low vision in schools for the blind in Kenya and Uganda; secondly, to evaluate inexpensive locally produced low vision devices; and, finally, to evaluate simple methods of identifying those low vision students who could read N5 to N8 print after low vision assessment. METHODS: A total of 230 students were examined (51 school and 16 university students in Uganda and 163 students in Kenya, aged 5-22 years), 147 of whom had a visual acuity of less than 6/18 to perception of light in the better eye at presentation. After refraction seven of the 147 achieved 6/18 or better. Eighty two (58.6%) of the 140 students with low vision (corrected visual acuity in the better eye of less than 6/18 to light perception) had refractive errors of more than 2 dioptres in the better eye, and 38 (27.1%) had more than 2 dioptres of astigmatism. RESULTS: Forty six per cent of students with low vision (n = 64) could read N5-N8 print unaided or with spectacles, as could a further 33% (n = 46) with low vision devices. Low vision devices were indicated in a total of 50 students (35.7%). The locally manufactured devices could meet two thirds of the need. CONCLUSION: A corrected distance acuity of 1/60 or better had a sensitivity of 99.1% and a specificity of 56.7% in predicting the ability to discern N8 print or better. The ability to perform at least two of the three simple tests of functional vision had a sensitivity of 95.5% and a specificity of 63.3% in identifying the students able to discern N8 or better.

Adolescent↗
PubMed1998

A comparison of low vision clinic data with low vision survey and blindness registration information.

PURPOSE: To determine whether low vision demographic data provided by low vision clinic data are comparable to that provided by blindness registration and disability questionnaire information. METHODS: Low vision demographic data for Canada and Ontario within the postcensus Health and Activity Limitation Survey (HALS 1991) were obtained from Statistics Canada. These data were compared with 4744 reports of low vision examinations obtained in a multi-center low vision clinic study in Ontario, Canada (1991-1994) and appropriate annual figures from the Canadian National Institute for the Blind (CNIB). RESULTS: Data from the low vision clinic study and the CNIB were similar. The low vision clinic study (and CNIB) reported far fewer adults (15 to 64 years) and far more seniors (65+ years) obtaining low vision examinations than suggested by HALS. CONCLUSIONS: HALS does not report on patients with low vision, as defined in low vision clinics. The differences between survey, low vision clinic, and blindness registration data are presented.

Adolescent↗
PubMed1995

Is there a need for binocular vision evaluation in low vision?

The purpose of this study was to determine the need for a binocular vision evaluation in the management of low vision patients. Thirty subjects were selected with visual acuities of at least 6/60 in each eye. Twenty-three had age-related macular degeneration as the primary ocular pathology and seven had various other ocular conditions. The binocular vision evaluation comprised: detailed history and symptoms with an emphasis on the occurrence of near vision problems; modified binocular vision assessment which included cover test at near, ocular movements, convergence, Bagolini glasses, horizontal vergence reserves and prismatic measurement of any observed anomaly. History and symptoms revealed horizontal and vertical diplopia, jumbling of print, asthenopia, intermittent blurring and print being too small. Binocular vision assessment revealed exophoria at near, manifest horizontal deviations, convergence insufficiency, and vertical muscle imbalance. These anomalies occurred either singly or in combination. The results indicate that there is a need for binocular vision evaluation in low vision in order to reveal near vision disorders that may be partly attributable to binocular vision anomaly and not solely due to ocular pathology. This information should facilitate the implementation of the appropriate course of optometric management for these patients.

Aged↗
PubMed1999

Providing timely and ongoing vision rehabilitation services for the diabetic patient with irreversible vision loss from diabetic retinopathy.

BACKGROUND: Diabetic retinopathy (DR) remains the leading contributor to severe vision loss in the United States among persons 20 to 70 years of age. Despite advances in disease management and treatment, patients with vision loss from DR continue to constitute a significant portion of patients served in vision rehabilitation service (VRS) settings. These patients present special challenges to VRS providers because of early onset, fluctuations in and the complex nature of vision loss, unique visual demands of disease management, and associated multi-system losses. CASE REPORTS: After introductory epidemiologic review, a case presentation format is used to illustrate solutions a multidisciplinary VRS can offer the special visual challenges of the person with diabetes with vision loss from DR. Four patients are presented--ages 30 to 70 years--with varying degrees and types of vision loss, with different lifestyle demands and disease management needs. The cases address vocational issues, vision fluctuation, coordinating adaptive solutions to complex visual losses, and meeting diabetic needs to measure medication, insulin, and blood glucose levels, to maintain skin care, diet, exercise, transportation, family roles, and support systems. CONCLUSIONS: The unique and complex needs of people with diabetes who experience vision loss can be well addressed through timely and ongoing VRS consultations, in conjunction with medical/ocular disease management.

Adult↗
PubMed2001

Vision multiplexing: an engineering approach to vision rehabilitation device development.

Multiplexing is the transmission of two or more messages simultaneously over the same communication channel in a way that enables them to be separated and used at the receiving end. The normal visual system provides us with a very wide field of view at an apparent high resolution. The wide field of view is continuously monitored at a low resolution, providing information for navigation and detection of objects of interest. These objects of interest are sampled over time using the high-resolution fovea. Most disabling visual conditions impact only one of the components, the peripheral low-resolution wide field or the central high-resolution fovea. The loss of one of these components prevents the interplay of central and peripheral vision needed for normal function and causes disability. Traditionally low-vision aids replace or supplement the missing function, but usually at a cost of a significant loss in the surviving function. For example, magnifying devices increase resolution but reduce the field of view, whereas minifying devices increase the field of view but reduce resolution. A proposal to resolve many of the problems of current visual aids by exploring a general engineering approach--vision multiplexing--that takes advantage of the dynamic nature of human vision is presented. Vision multiplexing seeks to provide both the wide field of view and the high-resolution information in ways that could be accessed and interpreted by the visual system. This paper describes the use of optical methods and computer technologies in the development of a number of new visual aids, all of which apply vision multiplexing to restore the interplay of central and peripheral vision using eye movements in a natural way.

Biomedical Engineering↗
PubMed2001

Preliminary investigation of the responsiveness of the Melbourne Low Vision ADL index to low-vision rehabilitation.

PURPOSE: To conduct a preliminary investigation on the ability of the Melbourne Low Vision ADL Index to detect changes in functional ability as a result of low-vision rehabilitation. METHODS: Twenty two subjects with age-related macular degeneration (ARMD) who were newly referred to the Kooyong Low Vision Clinic were recruited. The Melbourne Low Vision ADL Index was administered prerehabilitation and postrehabilitation. Changes in scores and effect size statistics were analyzed. RESULTS: The median total score for the subjects prerehabilitation was 67, and the median total score postrehabilitation was 76. The difference in prerehabilitation and postrehabilitation scores was statistically significant (Wilcoxon signed rank test = 248.5, p < 0.001). The mean change score for the total Melbourne Low Vision ADL Index was 9.3 (SD, 5.6). Thus the overall effect size statistic (mean change score divided by SD of prerehabilitation score) was 0.78. CONCLUSIONS: This preliminary investigation indicates that the Melbourne Low Vision ADL Index is responsive to a rehabilitation program for patients with ARMD. It has potential to be used as a measure of low-vision rehabilitation outcomes.

Activities of Daily Living↗
PubMed2001

The development of the Melbourne low-vision ADL index: a measure of vision disability.

PURPOSE: To develop a new test of activities of daily living (ADLs) appropriate for the low-vision population: the Melbourne Low-Vision ADL Index (MLVAI). METHODS: The MLVAI was designed as a desk-based clinical assessment, comprising 18 observed items on complex ADLs in part (a) and 9 questions on broad self-care ADLs in part (b). Each item was rated on a five-level descriptive scale from 0 to 4, based on independence, speed, and accuracy of performance. It was designed to be administered under standardized conditions with regard to the instructions, illumination, and working distances. The validity and reliability of the new MLVAI was determined for 122 subjects who were representative of the general low-vision population, in a cross-sectional study. RESULTS: Two items were found to be redundant and were eliminated from the test. Thus, the final test comprised 25 items, with 100 being the highest possible score. Cronbach's alpha indicated an internal reliability of 0.96, and an intraclass correlation coefficient indicated an overall reliability of 0.95. The SE of measurement was 4.5. According to Spearman's correlation coefficient, the test-retest reliability was 0.94 (P < 0.001), and the interpractitioner reliability for five different pairs of practitioners was 0.90 or higher (P < 0.001). With regard to validity, there was a moderately high correlation with vision impairment (r = -0.68, P < 0.001). Using Rasch analysis, content validity was also demonstrated by good separation indexes (4.70 and 9.88) and high reliability scores (0.96 and 0.99) for the person and items parameters, respectively. Separate calculation of indexes and reliability scores for parts (a) and (b) indicated high content validity and reliability of each part. However, the separation indexes and reliability scores were higher for part (a) than for part (b). The correlation coefficient for part (a) and part (b) was 0.68. CONCLUSIONS: The MLVAI is a highly valid and reliable standardized test of ADL performance for the general low-vision population. It may be used to assess patients with low vision and has the potential to be used as a measure of low-vision rehabilitation outcomes.

Activities of Daily Living↗
PubMed1998

A systems model for low vision rehabilitation. II. Measurement of vision disabilities.

BACKGROUND: This study presents and tests a method of measuring vision disabilities. Based on the model presented in the first paper of this series, cognitive and motor activities ("tasks") are organized in a hierarchy that identifies the tasks' behavioral goals (purposes) and the social objectives the goals serve. Two latent variables important to the definition of vision disability are identified: "value of living independently" and "visual ability for independent living." The basic principles of the Rasch measurement model are reviewed, and Rasch models are used to measure the two variables that define vision disability. The need for rehabilitation to meet each goal is represented by "rehabilitative demand," a mathematical function of the measurements made of the value and difficulty of achieving each goal independently. METHODS: Over 400 patients with low vision rated both the importance and difficulty of independently achieving each of 24 goals. Rasch analysis was used to derive interval measures of the social value of each goal, the value that individual patients placed on each goal relative to the derived social definition of independence, the visual ability required to achieve each goal without help, and the visual ability of individual patients to live independently. A rehabilitative demand function was ascertained from the judgments of 17 AAO Diplomates in Low Vision through triadic comparisons and multidimensional scaling. RESULTS: Self-care had the greatest "social value" for independence; performing music had the least. Recreational reading required the greatest "visual ability" to accomplish independently; self-care required the least. Rehabilitative demand was linear with value and nonmonotonic with difficulty. CONCLUSIONS: Rehabilitative demand, an algorithm for defining vision disability, incorporates interval measures of visual ability and the value of independent living estimated from patient-based assessments, a social scale of the value of activities relative to independent living, and a consensus opinion of low vision experts on the prioritization of the need for rehabilitation.

Activities of Daily Living↗
PubMed1990

"Object vision" and "spatial vision": the neuropsychological evidence for the distinction.

The distinction between "object vision" and "spatial vision" was made by Ungerleider and Mishkin (1982) on the evidence of behavioural and neuroanatomical studies, largely with monkeys. It holds that separate cortical systems are involved, the occipito-temporal in object vision, the occipito-parietal in spatial vision. This distinction has been unquestioned; it appears as though fact in influential textbooks; but has never been subjected to critical scrutiny. Theoretically, there are substantial difficulties, for instance because during perception objects do not form a special category, apart from their features; and because shape, pattern and size are spatial features of objects. Empirically, for the monkey the behavioural distinction does not hold (because parietal cortex is not the sole cortical area involved in "spatial vision"); and in man because parietal lesions have long been known to lead to impaired perception of incomplete pictures. Moreover, although Ungerleider and Mishkin do not generalise their distinction to touch, this sense deserves consideration, given that Mishkin had earlier argued that vision and touch have a similar organisation. In touch there are direct anatomical connections between the areas serving "object touch" and "spatial touch", and both in man and in the monkey it seems established that the same region processes spatial performance in vision and in touch. Further work is needed particularly on the spatial disorder after parietal lesions: in the monkey, research has frequently been confined to one non-specific test; in man, important differences related to the laterality of the lesion, have only recently emerged. Then "spatial performance" may be found to be more closely linked to motor output than to sensory input.

Animals↗