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PubMed2003

Barriers to accessing low vision services.

AIM: To investigate barriers to accessing low vision services in Australia. METHODS: Adults with a vision impairment (<6/12 in the better eye and/or significant visual field defect), who were current patients at the Royal Victorian Eye and Ear Hospital (RVEEH), were interviewed. The questions investigated self-perceived vision difficulties, duration of vision loss and satisfaction with vision and also examined issues of awareness of low vision services and referral to services. Focus groups were also conducted with vision impaired (<6/12 in the better eye) patients from the RVEEH, listeners of the Radio for the Print Handicapped and peer workers at Vision Australia Foundation. The discussions were recorded and transcribed. RESULTS: The questionnaire revealed that referral to low vision services was associated with a greater degree of vision loss (p = 0.002) and a greater self-perception of low vision (p = 0.005) but that referral was not associated with satisfaction (p = 0.144) or difficulties related to vision (p = 0.169). Participants with mild and moderate vision impairment each reported similar levels of difficulties with daily activities and satisfaction with their vision (p > 0.05). However, there was a significant difference in the level of difficulties experienced with daily activities between those with mild-moderate and severe vision impairment (p < 0.05). The participants of the focus groups identified barriers to accessing low vision services related to awareness of services among the general public and eye care professionals, understanding of low vision and the services available, acceptance of low vision, the referral process, and transport. CONCLUSION: In addition to the expected difficulties with lack of awareness of services by people with low vision, many people do not understand what the services provide and do not identify themselves as having low vision. Knowledge of these barriers, from the perspective of people with low vision, can now be used to guide the development and content of future health-promotion campaigns.

Activities of Daily Living↗
PubMed2000

[Utilization of a new night vision enhancement device (DAVIS)].

PATIENTS AND METHODS: Following complete ophthalmologic examination 37 patients with night blindness due to Retinitis Pigmentosa (sometimes Usher-Syndrome) and Choroideremia (n = 3) performed several tests with DAVIS during darkness. We evaluated the improvement of visual function on a special outside course in the city of Heidelberg (duration 1.5 to 4 hours). RESULTS: Twenty six of the patients were able to better recognize obstacles, 28 could see objects which were not seen without DAVIS. Twenty two of the 37 patients would use the DAVIS. Patients needed a visual acuity of more than 0.1 and more than 6 degree of central visual field to experience improvement with DAVIS. However, in patients with only minimal changes of the visual field, the restriction due to the presence of the device was a drawback. Sudden occurrence of light sources leads to blinding and limits the indoor use. CONCLUSION: DAVIS enhances contrast acuity especially during night and twilight. This leads to improvement of orientation due to better recognition of obstacles and allows rehabilitation of patients with night blindness for outdoor mobility. Individual test and adjustment of DAVIS is necessary to allow exact and adequate prescription.

Adolescent↗
PubMed1999

[At home utilization of low-vision aids by the visually impaired].

BACKGROUND: The increase of life expectancy causes a rising number of partially sighted. Therefore our Department of Ophthalmology has founded a laboratory for partially sighted 7 years ago. To optimize patient care, the results were now reinvestigated. MATERIALS AND METHODS: For the present study, 125 patients were selected by geographical aspects (home nearby clinic) from the lab's pool. After a 3 month minimum period of using the low-vision aid (LVA) patients were visited at their homes. Near visual acuity, distance visual acuity, magnification, and contrast sensitivity were studied under domestic and optimized conditions of illumination. Patients were interviewed in detail to investigate their habits of LVA use. RESULTS: An overall number of 94 patients (66 females and 28 males) could be evaluated. The most patients were between 80 and 84 years old. Vision impairment was attributable mostly to macular degeneration (55%) and diabetic retinopathy (21%). Visual acuity and contrast sensitivity decreased during the period of investigation. 79% of the patients had a unsatisfactory domestic illumination (< 1000 lx). Only 23% of the patients used their LVA at a fixed location. Main field of using LVA was reading (68%). The LVA were rarely used for writing and other fields of practice. 76% of LVA were used daily, more than 50% for a maximal duration of 1 h/d. Magnifiers were preferably used for short-time activities. Closed circuit television systems (CCTV) had a very good acceptance. Telescopes were characterized by a very high rate of rejection. The number of non-used LVA was approximately a fifth. Reasons were decreased visual acuity, impractical handling, missing introduction by delivering optician (54%) as well as unsatisfactory illumination. CONCLUSIONS: Improved patient care can be obtained by regular check-up visits (6 months), enhanced illumination, low-vision training, home visits, multi-disciplinary care and modified prescription of LVA.

Aged↗
PubMed1997

[Visual field examination in limited patient cooperation].

Objective methods to estimate the visual field are necessary, if a conventional subjective perimetry is impossible due to limited cooperation. Objective methods are indicated in infants, handicapped patients, patients with psychogenic visual field loss, and malingerers. An objective estimation of the visual field can be performed by means of pupillary light reflexes, voluntary and involuntary eye movements, and visual evoked potentials. Systematically false responses contain useful information regarding the proof of misrepresentations. The reproducibility of visual field defects can be checked by testing at different distances from the screen. This article reports on handy methods requiring no large-scale equipment.

Adult↗
PubMed2006

Viewpoint and orientation influence picture recognition in the blind.

In the first three experiments, subjects felt solid geometrical forms and matched raised-line pictures to the objects. Performance was best in experiment 1 for top views, with shorter response latencies than for side views, front views, or 3-D views with foreshortening. In a second experiment with blind participants, matching accuracy was not significantly affected by prior visual experience, but speed advantages were found for top views, with 3-D views also yielding better matching accuracy than side views. There were no performance advantages for pictures of objects with a constant cross section in the vertical axis. The early-blind participants had lower performance for side and frontal views. The objects were rotated to oblique orientations in experiment 3. Early-blind subjects performed worse than the other subjects given object rotation. Visual experience with pictures of objects at many angles could facilitate identification at oblique orientations. In experiment 5 with blindfolded sighted subjects, tangible pictures were used as targets and as choices. The results yielded superior overall performance for 3-D views (mean, M = 74% correct) and much lower matching accuracy for top views as targets (M = 58% correct). Performance was highest when the target and matching viewpoint were identical, but 3-D views (M = 96% correct) were still far better than top views. The accuracy advantage of the top views also disappeared when more complex objects were tested in experiment 6. Alternative theoretical implications of the results are discussed.

Adult↗
PubMed2004

Beyond sensory images: Object-based representation in the human ventral pathway.

We investigated whether the topographically organized, category-related patterns of neural response in the ventral visual pathway are a representation of sensory images or a more abstract representation of object form that is not dependent on sensory modality. We used functional MRI to measure patterns of response evoked during visual and tactile recognition of faces and manmade objects in sighted subjects and during tactile recognition in blind subjects. Results showed that visual and tactile recognition evoked category-related patterns of response in a ventral extrastriate visual area in the inferior temporal gyrus that were correlated across modality for manmade objects. Blind subjects also demonstrated category-related patterns of response in this "visual" area, and in more ventral cortical regions in the fusiform gyrus, indicating that these patterns are not due to visual imagery and, furthermore, that visual experience is not necessary for category-related representations to develop in these cortices. These results demonstrate that the representation of objects in the ventral visual pathway is not simply a representation of visual images but, rather, is a representation of more abstract features of object form.

Adult↗
PubMed2003

Refractive errors and cataract as causes of visual impairment in Brazil.

PURPOSE: To identify the main causes of visual impairment (VA <or= 0.2) within the population over 50 years of age examined in "Cataract Free Zone" projects sponsored by the University of Campinas from 1986 to 1995. METHODS: A retrospective review of the ophthalmic forms used for 60,404 patients examined in 74 Cataract Projects was performed. Through mass media information, adults of the target region or city were asked to self-test their vision. Patients with VA <or= 0.2 in the better eye were to come to a visual acuity test. Using Snellen charts, visual acuity testing was done by trained auxiliaries and medical students. The positive cases were then examined by ophthalmologists Criteria were established for the classification of the diagnoses and statistical analysis was performed. RESULTS: After the self-test of visual acuity, 60,404 patients came to have their visual acuity tested; 11,462 (18.97%) cases were considered positive and were submitted to complete eye examination; 5447 (42.7%) received spectacles for vision improvement, and 2704 (23.59%) had cataract surgery done. Other important causes of visual impairment were senile macular degeneration (5.4%) and glaucoma (4.02%). CONCLUSION: The main causes of visual impairment were non-corrected refractive errors and senile cataract. Ophthalmic community-based campaigns to serve the older population are recommended in order to detect and treat the identified cases and to indicate possible changes in the health care system.

Brazil↗
PubMed2003

Visual impairment and nursing home placement in older Australians: the Blue Mountains Eye Study.

PURPOSE: To assess whether visual impairment at baseline is an independent contributor to subsequent nursing home placement during a 6-year follow-up. METHODS: 3654 non-institutionalised people aged 49+ years (82.4% of those eligible) who participated in baseline examinations of the Blue Mountains Eye Study (1992-94) were followed during 1997-99. Presenting visual acuity was measured with current glasses and a standardised refraction performed. We defined visual impairment as visual acuity reduced to <or=20/40. Permanent nursing home admissions during follow-up were confirmed by the regional Aged Care Assessment Team and government subsidy payment records. RESULTS: At baseline, 511 participants had presenting visual impairment. After refraction, vision improved to 20/30 or better in 346 persons (68%, "correctable"), while 165 (32%) remained visually impaired. During follow-up, 162 study participants (5.0%) were admitted permanently to a nursing home. The age-adjusted 6-year incidence was 3.6% for participants with normal vision, 16.2% for those with visual impairment after best correction and 8.1% for those with "correctable" visual impairment. After adjusting for non-cognitive factors that predicted nursing home placement, the relative risk (RR) for nursing home admission among persons with visual impairment after best correction was 1.8 (95% CI 1.1-2.9). A similar magnitude of association was found among persons with "correctable" visual impairment (RR 2.1, 95% CI 1.4-3.1). For each line of reduction in presenting visual acuity at baseline, there was a 7% increased risk of subsequent nursing home placement. CONCLUSIONS: This study suggests that decreased vision may be a marker or contributing factor to subsequent nursing home placement in general older populations.

Aged↗
PubMed2003

A randomized trial of visual impairment interventions for nursing home residents: study design, baseline characteristics and visual loss.

INTRODUCTION: Visual impairment among nursing home residents is higher than in community-dwelling elderly. The provision of eye care services may be beneficial to nursing home patients. Our project, a randomized trial of vision restoration and rehabilitation in nursing home residents, compares usual care to targeted interventions. In this paper, we present the baseline characteristics of our sample within the nursing homes. METHODS: Twenty-eight nursing homes on Maryland's Eastern Shore were matched in pairs by size and payment type. Each pair was randomized to usual care or targeted intervention. Habitual and best-corrected acuity was attempted, using standard letter symbol/charts and grating acuity charts. Visual impairment was vision in the better eye <20/40 on letter and/or grating acuity. The MiniMental State Examination (MMSE) was used to determine cognitive impairment. RESULTS: Of those participants eligible to be screened, 40% had severe cognitive impairment (MMSE score 0-9). No measure of acuity could be ascertained on 18% of eligibles. Among the 1305 persons with acuity data, 38% had presenting vision worse than 20/40. After refractive correction, 29% had visual impairment. There was no difference by race or gender in those with visual impairment, although they were older, compared to those without visual loss. CONCLUSIONS: The nursing home residents had high rates of both cognitive impairment and visual impairment, creating a challenging environment for visual intervention. By improving access to eye care within the context of the clinical trial, and changing either the magnitude of visual loss or the resultant impact on function, we hope to demonstrate a change in the quality of life for nursing home residents.

Aged↗
PubMed2003

Causes of visual impairment in two older population cross-sections: the Blue Mountains Eye Study.

AIMS: To describe the causes of bilateral and unilateral blindness and visual impairment in two cross-sections of an older Australian population 6 years apart. METHODS: The Blue Mountains Eye Study examined 3654 persons aged 49-97 years during 1992-1994 (population cross-section 1). Cohort survivors (2335) and 1174 persons who moved to the area or reached an eligible age were examined during 1997-2000, a total of 3509 persons (population cross-section 2). LogMAR visual acuity was measured after standardized refraction. Blindness and visual impairment were respectively defined by visual acuity <6/60 and <6/12. Causes were determined for the two temporal cross-sections. RESULTS: Age-related macular degeneration (AMD) was the principal cause of bilateral and unilateral non-correctable blindness in both cross-sections. AMD caused 77% of bilateral blindness in Cross-section 1 and 50% in Cross-section 2. Cataract, glaucoma, corneal and neurological disease were next equally frequent causes (6% each) of bilateral blindness in Cross-section 1. In Cross-section 2, cataract ranked as the third most frequent principal cause (10%) after other retinal diseases (40%). The proportion of unilateral blindness with AMD as principal cause was very similar (around one-third of cases) in the two cross-sections; while in Cross-section 2 blindness was less frequently caused by cataract (19% vs. 13%). Cataract was the principal cause of both bilateral and unilateral visual impairment, responsible for 50% of bilateral (better eye) and 35-40% of unilateral (worse eye) impairment, with slightly lower rates found in Cross-section 2 than in Cross-section 1. AMD was consistently the second most frequent cause, causing one-third of bilateral and one-fifth of unilateral visual impairment. CONCLUSIONS: These data indicate a relative stable pattern of causes for blindness and visual impairment, with AMD and cataract, respectively, dominating these two levels.

Aged↗
PubMed2003

The prevalence and incidence of visual impairment in people of age 20-59 years in industrialized countries: a review.

BACKGROUND: Reviews on the prevalence of blindness and low vision in persons of age 20 to 59 years are lacking. We have therefore carried out a review based on a Medline search. METHODS: The review was confined to epidemiological studies performed in Western Europe, North America and Australia covering the age group 20 to 59 years where there were comparable definitions of blindness and low vision according to the IAPB and WHO classification of blindness and low vision. RESULTS: Three surveys, four register studies and two studies based on multiple sources matched our selection criteria. Blindness and low vision are described separately. Blindness: Only one study, based on multiple sources, covered the whole age group 20 to 59 years. In this study the overall prevalence of blindness was 0.08%. The prevalence of blindness was 0.04% among those 20-39 years old, whereas in the age group 40-59 years it was 0.1% in two surveys and one study on multiple sources. However, the prevalence was higher, 0.5% among whites and 0.7% among colored, in The Baltimore Eye Study. The definition of blindness was similar in all three studies. Low vision: Three studies provided data on the prevalence of low vision in the age group 20-59 years, although the number of cases was very small. In one study the prevalence of a visual acuity < or = 6/24 to 6/48 was 0.07% and in another the prevalence was 0.17% using < 6/18 to 0.5/60. No person with low vision was found in the third study. CONCLUSIONS: The existing epidemiological data on blindness and low vision among adults aged 20 to 59 years are insufficient. Epidemiological studies based on multiple sources are needed for the study of rare conditions such as blindness and low vision.

Adult↗
PubMed2004

2002 global update of available data on visual impairment: a compilation of population-based prevalence studies.

PURPOSE: For the past 25 years, the WHO Programme for the Prevention of Blindness and Deafness has maintained a Global Data Bank on visual impairment with the purpose of storing the available epidemiological data on blindness and low vision. The Data Bank has now been updated to include studies conducted since the last update in 1994. METHODS: An extensive literature search was conducted in international and national scientific and medical journals to identify epidemiological studies that fulfilled basic criteria for inclusion in the Data Bank, namely a clearly stated definition of blindness and low vision, and prevalence rates derived from population-based surveys. Sources such as National Prevention of Blindness Programmes, academic institutions or WHO country or regional reports were also investigated. RESULTS: Two-hundred-and-eight population-based studies on visual impairment for 68 countries are reported in detail, providing an up-to-date, comprehensive compilation of the available information on visual impairment and its causes globally.

Adolescent↗
PubMed2002

Prevalence and causes of severe visual impairment and blindness in children in Mongolia.

BACKGROUND: Reliable epidemiological data on the prevalence and causes of visual loss in children are difficult to obtain, but are essential for planning. No such data are available from Mongolia. AIM: To determine the prevalence and causes of severe visual impairment and blindness (SVI/BL) in children from a defined area of Mongolia, using several methods of identification. METHODS: Children with presenting visual acuities of <6/60 in the better eye who lived in 10 of the 18 provinces (Aimaks) were identified 1) by family doctors 2) in the school for the blind 3) by visiting eye departments in the capital. All eligible children were examined (or data extracted from hospital records) and the cause of visual loss determined using the WHO classification system. RESULTS: Sixty-four children with SVI/BL before refraction were identified who lived in the 10 study Aimaks. They were recruited by family doctors (52); by home visits (3); from hospital records (4); or from the school for the blind (5). The prevalence of SVI/BL before refraction was 0.19/1,000 children (95% CI 0.16-0.22), decreasing to 0.16/1,000 after refraction (95% CI 0.13-0.19) but there was considerable variation from Aimak to Aimak. The major causes of SVI/BL were lesions of the lens (34%), central nervous system disorders (19%), lesions of the whole globe (e.g. microphthalmos) (14%), and retinal conditions (12.5%). Hereditary factors were responsible for 27% of causes, and 17% of children were blind following acquired conditions of childhood. The underlying cause could not be determined in 48%. The causes of SVI/BL was analysed in a further 16 children who lived outside the study Aimaks to compare the causes in children in special education with those not in schooling, and by age. CONCLUSION: The prevalence estimate obtained was lower than anticipated, and possible reasons are discussed. The pattern of causes of SVI/BL is similar to that in children in schools for the blind in China, but is very different from other Asian countries. Meningococcal meningitis was the most common preventable cause of SVI/BL, and immunisation is being considered. Other preventable causes were rare, and the majority of children needing surgical intervention had already been identified and referred for treatment. The control of blindness in children could possibly be improved by better management of conditions requiring surgery, and by the provision of low vision devices.

Adolescent↗