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PubMed2005

[Development and evaluation of psychometric tests of the Chinese-version of low vision quality of life questionnaire].

OBJECTIVE: To develop and evaluate a Chinese language vision health related quality-of-life (VRQoL) questionnaire. METHODS: The low vision quality of life questionnaire (LVQOL) was translated and adapted into the Chinese-version low vision quality of life questionnaire (CLVQOL). The systematic protocols were set as 3 forward translations, 2 committee reviews and 1 back-ward translation. The CLVQOL was performed in 100 randomly selected people with low vision (primary group) and 100 people with normal vision (control group). Ninety-four participants from the primary group completed the CLVQOL and repeated 2 weeks later (test-retest group). The results were compared with patient demographics and the internal consistency reliability, test-retest reliability, item-internal consistency, item-discrimination validity, construct validity and discrimination validity of the CLVQOL were calculated. RESULTS: The review committee agreed that the CLVQOL replicated the meaning of the LVQOL and was sensitive to cultural adaptations. The Cronbach alpha coefficient and the split-half coefficient for the four scales and total CLVQOL scales were 0.75 to 0.97. The test-retest reliability as estimated by intraclass correlation coefficient was 0.69 to 0.95. Item-internal consistency was > 0.4 and item-discrimination validity was generally < 0.40. The varimax rotation factor analysis of the CLVQOL identified four principal factors. All of the scores of four subscales and the total score of CLVQOL of the primary group were lower than those of the control group, both in patients and local residents. CLVQOL scores were highly correlated with visual acuity. CONCLUSIONS: The CLVQOL is a culturally specific VRQOL measure instrument. CLVQOL can satisfy conventional psychometric criteria, can discriminate visually healthy populations from low vision patients and is valuable in the clinical practice and in the screening of the community populations.

Adult↗
PubMed1997

Psychophysics of reading--XVI. The visual span in normal and low vision.

The visual span in reading is the number of characters that can be recognized at a glance. The shrinking visual span hypothesis attributes reading deficits in low vision, and slow reading in normal vision at low contrast, to a reduction in the visual span. This hypothesis predicts that reading time (msec/word) becomes increasingly dependent on word length as text contrast decreases. We tested and confirmed this prediction using the rapid serial visual presentation (RSVP) method. Estimates of the visual span ranged from about 10 characters for high-contrast text to less than two characters for low-contrast text. Eye-movement recordings showed that longer reading times at low contrast are partitioned about equally between prolonged fixation times and an increased number of saccades (presumably related to a reduced visual span). RSVP measurements for six out of seven low-vision subjects revealed a strong dependence of reading time on word length, as expected from reduced visual spans.

Adolescent↗
PubMed2003

[Prevalence of low vision and blindness in defined populations in rural and urban areas in Beijing].

OBJECTIVE: To investigate the prevalence and causes of low vision and blindness in Beijing residents aged 40 and over. METHODS: 4,451 residents aged 40 and over in 3 rural communities and 5 urban communities in Beijing underwent eye examination, including examination of distant and near visual acuity (VA), best corrected distant and near VA, pinhole VA, and visual field, slit lamp biomicroscopy, and dilated ocular examination in the form of in-home survey by defined population-based sampling. The medical history was surveyed too. The data were analyzed based on the criteria of the World Health Organization. RESULTS: The general prevalence rates of low vision and blindness were 0.99% (95% CI: 0.70-1.28) and 0.39% (95% CI: 0.21-0.57) respectively. The prevalence rate of low vision in females was 1.45%, 2.23 times that of males (0.65%) (OR: 1.97, 95% CI: 1.00-3.95). The prevalence rate of low vision of rural residents was 1.76%, 2.89 times that of urban residents (0.61%) (OR: 2.93, 95% CI: 1.43-6.11). The prevalence rate of blindness in females was 0.64% and 0.37% in males. The prevalence rate of blindness of rural residents was 1.06%, 2.04 times that of the urban residents (0.52%) (OR: 3.77, 95% CI: 1.41-10.62). The 3 major causes of blindness were cataract (37.50%), glaucoma (29.20%), and high myopic macular degeneration (8.30%). The prevalence of blindness increased with age. CONCLUSION: The prevalence rates of low vision and blindness are higher in the rural areas. Cataract, glaucoma, and high myopic macular degeneration are the major causes of blindness. The prevalence of low vision and blindness are influenced by age, sex; area, health care level, educational level, and environmental factors.

Adult↗
PubMedDate not supplied

The prevalence of blindness and low vision in older onset diabetes mellitus and associated factors: a community-based study.

PURPOSE: This community-based study was conducted to assess the prevalence and related factors of low vision and legal blindness in older onset diabetic patients (diagnosed at age 30 and older). METHODS: All known diabetic patients who live in the four primary health care center region Abidinpaşa Ankara, Turkey (total population: 96,348) were included in this cross-sectional study. The prevalence of known diabetes mellitus is 2.2%, of which 96.6% are older onset and 3.4% are younger onset. RESULTS: In the older onset diabetes group (1289 cases), 10.8% of the population had low vision and only 2.7% had legal blindness. Diabetic retinopathy (DR) was observed in 23.6% of the patients with low vision (42% proliferative DR) and in 62.9% of the patients with legal blindness (90.1 % proliferative DR). CONCLUSIONS: In older onset diabetic patients with low vision, nonproliferative retinopathy was a more frequent cause of impaired vision than proliferative retinopathy. Low vision and legal blindness caused by retinopathy were significantly associated with sex, age at examination, age at diagnosis, duration of diabetes, type of diabetes treatment, and hypertension in univariate analysis. However, in logistic regression analysis, low vision and legal blindness caused by retinopathy were found to be associated with longer duration of diabetes (> or =15 years), use of insulin, and hypertension.

Adult↗
PubMed2002

Low vision services for vision rehabilitation in the United Kingdom.

AIM: Little is known about the distribution and methods of delivery of low vision services across the United Kingdom. The purpose of this study was to determine the type and location of low vision services within the UK. METHODS: Survey by means of a 29 point postal questionnaire, followed when necessary by a five point telephone questionnaire. All known potential providers of low vision services (n = 2539) including hospitals (n = 277), optician/optometry practices (n = 1683), social services (n = 177), voluntary groups (n = 190), specialist teachers (n = 205), and universities (n = 6) were surveyed. For each service provider, the type, magnitude, and geographical location were determined. The distribution of services across the United Kingdom and the ratio of providers to population density of people with a visual impairment were mapped using the Geographic Information System (GIS). RESULTS: Data were obtained on 1945 (77%) service providers: 1679 (66%) responded to the postal questionnaire and 266 (11%) to the telephone questionnaire. Of all respondents, 59% (n = 1135) offer some form of help to people with a visual disability, of which 26% (n = 497) only sell magnifiers and 33% (n = 638) provide low vision services. It is estimated that in total just under 155,000 low vision consultations are offered annually, the bulk of which are provided by hospital eye departments. The distribution was geographically uneven and there appears to be scarcity in some areas. CONCLUSION: When compared to the probable number of people with a visual impairment in the UK there are apparent inadequacies in service provision in terms of distribution, magnitude, and coordination. The results highlight a need to review current services.

Health Care Surveys↗
PubMed1997

The impact of cataract surgery on low vision patients. A population based study.

PURPOSE: To assess the impact of cataract surgery on low vision patients. METHODS: Self-estimated ability to perform visually demanding tasks before and after cataract surgery and expectations and satisfaction with the surgery were analysed in all low-vision patients (n = 52), who during a one-year period underwent surgery at Norrlands University Hospital in Umeå, Sweden. Self-administered questionnaires were used and the records of the patients were studied. RESULTS: The majority (81%) of the low vision patients reported an improved ability to perform visually demanding tasks after surgery. The number of patients who were unable to read newspaper-size print decreased significantly, from 44% to 21% after surgery. The subjectively improved visual ability as well as the augmentation of VA of the operated eye were both significantly related to satisfaction with the outcome of surgery. CONCLUSION: Most low-vision patients with significant cataract benefit from surgery, both subjectively by increased ability to perform visually demanding tasks as well as by an improved visual acuity. Particularly patients with loss of peripheral visual fields subjectively gain in orientation ability. It is important to reduce unreasonable expectations about the outcome of the surgery.

Activities of Daily Living↗
PubMed1989

Psychophysics of reading. VI--The role of contrast in low vision.

The effect of contrast on reading performance was measured in 19 low-vision observers with a wide range of visual disorders and degrees of vision loss. The observers read text composed of 6 deg letters, ranging in contrast from 0.96 down to contrast threshold for reading. Reading performance was characterized by two parameters: peak reading rate is the reading rate at maximum contrast, and critical contrast is the contrast at which reading rate drops to half its maximum value. Peak reading rates were lower in observers with central field loss than in observers with intact central vision. In 16 of 19 cases, critical contrasts were higher for low-vision observers than for normal observers (averaging 3.9 times higher), indicating a decreased tolerance to contrast reduction. Values of critical contrast were closely linked to contrast sensitivity for letters (r = 0.87), but did not vary systematically with type of vision loss. Five observers read white-on-black text faster than black-on-white at both high and low contrasts. Four of the five had cloudy ocular media. We attribute this contrast polarity effect to abnormal light scatter in eyes with cloudy media. We examined the hypothesis that our low-vision observers' deviation from normal performance could be characterized (1) by a contrast scaling factor representing an attenuation of effective contrast and (2) that this scale factor could be identified with reduced contrast sensitivity. Such a description provided a good account for subjects with cloudy ocular media, where contrast attenuation results from intraocular light scatter. It provided a first order, but incomplete account for subjects with field loss where contrast attenuation is related to contrast sensitivity losses due to neural factors.

Adult↗
PubMed2004

Causes of blindness, low vision, and questionnaire-assessed poor visual function in Singaporean Chinese adults: The Tanjong Pagar Survey.

OBJECTIVE: To determine the prevalence rates and causes of low vision, blindness, and patient-assessed deficient visual function among Singaporean Chinese adults. DESIGN: Population-based cross-sectional survey. PARTICIPANTS: Singaporean Chinese adults 40 to 79 years old (n = 1152). METHODS: From an initial sampling frame of 40- to 79-year-old Chinese in the Tanjong Pagar district in Singapore, 2000 subjects were selected using a disproportionate, stratified, clustered, random-sampling method. Of 1717 eligible subjects, 1232 were examined (participation rate = 71.8%), and 80 adults who did not have visual acuity (VA) data were excluded from the analysis. MAIN OUTCOME MEASURES: Bilateral low vision was defined as best-corrected VA (BCVA) worse than 6/18 and 3/60 or better, and bilateral blindness as BCVA worse than 3/60 in the better eye or constriction of the visual field to within 10 degrees of fixation, in accordance with the World Health Organization criteria. Patient-assessed visual function was measured using a modified VF-14 questionnaire. RESULTS: The age- and gender-adjusted prevalence rates were 1.1% (95% confidence interval [CI], 0.6-1.8) for bilateral low vision and 0.5% (95% CI, 0.2-1.1) for bilateral blindness, and the mean visual function score was 98.6. The rates of bilateral low vision and blindness increased with age, whereas visual function scores decreased with age, even after adjusting for gender and education. Cataract accounted for 58.8% of bilateral low vision, 20.0% of bilateral blindness, and 52.0% of poor visual function (score<90). Glaucoma contributed to 60.0% of bilateral blindness. CONCLUSION: The age- and gender-adjusted rates of low vision and blindness were 1.1% and 0.5%, respectively. Glaucoma is a leading cause of blindness in Singaporean Chinese adults, in addition to well-recognized causes in the rest of Asia such as cataract.

Adult↗
PubMed2002

Resource allocation to prevent trachomatous low vision among older individuals in rural areas of less developed countries.

Trachomatous low vision can be prevented by treating or preventing infection or through surgery to treat trichiasis. Resource allocation to prevent trachomatous low vision should be directed to those interventions that are the most cost-effective. In order to assess which of many potential interventions are the more cost-effective, data on the epidemiology of the disease, the effectiveness of community- and facility-based interventions, and the cost of the interventions are required. This paper provides a stylized model of the path from risk of infection through disease to trachomatous low vision or blindness that delineates the points at which interventions may occur and for which data are required. The literature reveals a considerable amount of data regarding the epidemiology of the trachoma and its sequelae but little on the effectiveness of community-based interventions and only one study that measured costs directly. More data are needed to assist policy makers and international program partners who seek to make efficient resource allocation decisions in an effort to eliminate trachoma as a cause of incident blindness in the developing countries in which trachomatous blindness remains prevalent.

Anti-Bacterial Agents↗
PubMed2002

[Value and practice of in-home "low-vision" rehabilitation in Rhone-Alp region of France].

INTRODUCTION: To demonstrate the interest of patient's home orthoptist deplacement to realize an in-home low-vision rehabilitation and encourage orthoptists to integrate this task in their usual work methods. PATIENTS AND METHODS: Eighty-five consecutive patients coming from a private ophthalmic rehabilitation Center and needing low-vision rehabilitation, were studied. The exercises used at patient's home were usually the same as those used in the rehabilitation Center. The choice in the organization of rehabilitation was always function of patient general health, people vicinity, and social context. RESULTS: Among the 85 patients, 60 (70.6%) were rehabilitated only in the ophthalmic Center, 11 (12.9%) could have a low-vision rehabilitation only thanks to the organization of the home's patient rehabilitation and 14 (16.5%) were both rehabilitated at the ophthalmic Center and, in the patient's home, some training was necessary too. The reasons for in-home low-vision rehabilitation were mainly represented by isolation problems, mobilisation physical capacities, but also, home installation conditions making difficult to realize the orthoptist recommendations. DISCUSSION: Besides some disadvantages: time-consuming, badly paid, decrease of efficiency in familiar environment, advantages are easily objected: ergonomy, training on optic systems, and psychological comfort. CONCLUSION: In-home low-vision rehabilitation is represented by the necessity of correctly taking care of each patient. It is an answer to a social demand and must be an integral part of low-vision orthoptist work.

Adult↗
PubMed2001

[First results of the IOBA low vision unit].

PURPOSE: To verify the efficacy a treatment for the rehabilitation of vision in our Unit for Clinical Low Vision in the testing of improvements in patient's efficiency for daily life activities. MATERIAL AND METHOD: 80 patients were studied. Ophthalmologic and optometric evaluation followed by a customised vision rehabilitation program were performed according to patient's immediate needs. In a second stage a telephoned questionnaire was filled in order to record efficacy of prescribed visual aids in their own environment. RESULTS: Rehabilitation training resulted in 89% of patients showing improvement in their quality of life in both fields; functional and psychological. 85% of patients showed improvement in near activities and 35% in far activities. DISCUSSION: A correct and specialised low vision refraction and a posterior vision rehabilitation training in the use of optical and non optical aids show increase in quality of life in patients with severe visual deficiencies.

Activities of Daily Living↗
PubMed1989

[An epidemiological survey of blindness and low vision in Chongqing].

An epidemiological survey of blindness and low vision in Chongqing showed that in a random sample of 13,832, there were 62 cases of bilateral blindness and 97 cases of bilateral low vision, the prevalences being 0.45% (male 0.38%, female 0.52%) and 0.70% (male 0.50%, female 0.90%) respectively. The prevalences in people over 60 years of age were significantly higher. The important blinding diseases were cataract, infectious keratitis, corneal turbidity, glaucoma, trachoma, and ametropia/amblyopia.

Blindness↗
PubMedDate not supplied

Effect of telescopic spectacles on head stability in normal and low vision.

Telescopic spectacles, highly magnifying visual aids mounted in spectacle frames, markedly alter the visual consequences of head movements. To evaluate the effect of this altered visual feedback on head stability, angular head velocity of normally sighted and low vision subjects was measured in the roll, pitch, and yaw axes. Measurements were made under two postural conditions: (1) quiet standing; and (2) walking in place, as well as three visual conditions: (1) eyes closed; (2) unmagnified vision; and (3) vision with 4 x binocular telescopic spectacles. For normal subjects during quiet standing, both unmagnified vision and vision with telescopic spectacles tended to reduce spontaneous head velocity in all axes as compared to the eyes-closed condition. However, in low vision subjects neither unmagnified vision nor vision with telescopic spectacles produced significant changes in values of head velocity relative to those measured with eyes closed. Spontaneous head velocities for standing low vision subjects tended to be higher than in normal subjects, although not all differences were statistically significant. During walking in place, Fourier analysis demonstrated prominent frequency components related to harmonics of the walking frequency under all viewing conditions. In normal subjects, vision with telescopic spectacles, to a greater degree than unmagnified vision, reduced head velocity during walking in the roll and yaw, but not the pitch, axes. For low vision subjects, significant reductions in head velocity during walking were observed only during vision with telescopic spectacles. These findings indicate that vision reduces angular instability of the head during standing and walking. Magnification produced by telescopic spectacles further improves head stability under some conditions, although the effect of vision is least evident in the pitch axis. The stabilizing effect of vision is reduced in low vision subjects.

Adult↗
PubMed1987

Clinical use of the Pepper Visual Skills for Reading Test in low vision rehabilitation.

The Pepper Visual Skills for Reading Test (VSRT) is an assessment instrument designed by Whittaker et al. to evaluate the reading skills of patients with macular degeneration who were able to read to their satisfaction before their vision loss. The VSRT was administered to 10 patients with macular degeneration and central scotomas from the Low Vision Optometry Program at the Hines Veterans Administration Hospital Central Blind Rehabilitation Center and the Visual Impairment Center to Optimize Remaining Sight (VICTORS) at Westside Veterans Administration Medical Center, Chicago. Reading skills were measured before and after a low vision treatment program. Results indicate that this test may be useful in designing low vision training programs, evaluating the progress of individual patients receiving low vision services, and evaluating low vision programs designed to rehabilitate those with reading difficulty.

Aged↗
PubMed1997

Blindness and low vision in Jimma Zone, Ethopia: results of a population-based survey.

A population-based study on the prevalence of blindness and low vision was carried out in Jimma Zone, south-western Ethiopia between November 1994 and January 1995. A total of 7423 people from a sample of 8215 (90.4%) was examined. Sixty-three (0.85%) were blind (visual acuity less than 3/60 in the better eye) and 125 people (1.7%) had low vision (less than 6/18-3/60). Cataract and aphakia (52.4%), corneal opacity and phthisis bulbi (25.4%), and glaucoma (9.5%) were the major causes of blindness. Cataract (56.8%), refractive errors (28.8%), and corneal opacity (12.8%) were the major causes of low vision. Corneal opacity from trachoma was responsible for 20.6% of all blindness and 10.4% of low vision. The prevalence of visual impairment due to refractive errors was 5.1/1000 population. Almost 25% of the study population had active trachoma, and 0.9% of pre-school children had signs of vitamin A deficiency. Out of a total population of 2 million an estimated 17,000 people are blind and 34,000 have low vision (i.e., a total of 51,000 people with visual impairment). Approximately 20,000 people require cataract surgery, 52,000 require lid surgery for trichiasis, 24,000 require spectacles (excluding presbyopia), including 10,000 for significant refractive errors, half a million require treatment for active trachoma and 4,000 require glaucoma treatment. Effective and feasible eye care programs need to be established in the zone and the available ophthalmic services have to be strengthened. These may be achievable through joint efforts of the community and the Ministry of Health in collaboration with non-governmental organizations. The available eye services are briefly described and recommendations made to meet the important needs for prevention of blindness in the region.

Adolescent↗
PubMed1998

Psychophysics of reading. XVII. Low-vision performance with four types of electronically magnified text.

Most people with low vision need magnification to read. Page navigation is the process of moving a magnifier during reading. Modern electronic technology can provide many alternatives for navigating through text. This study compared reading speeds for four methods of displaying text. The four methods varied in their page-navigation demands. The closed-circuit television (CCTV) and MOUSE methods involved manual navigation. The DRIFT method (horizontally drifting text) involved no manual navigation, but did involve both smooth-pursuit and saccadic eye movements. The rapid serial visual presentation (RSVP) method involved no manual navigation, and relatively few eye movements. There were 7 normal subjects and 12 low-vision subjects (7 with central-field loss, CFL group, and 5 with central fields intact, CFI group). The subjects read 70-word passages at speeds that yielded good comprehension. Taking the CCTV reading speed as a benchmark, neither the normal nor low-vision subjects had significantly different speeds with the MOUSE method. As expected from the reduced navigational demands, normal subjects read faster with the DRIFT method (85% faster) and the RSVP method (169%). The CFI group read significantly faster with DRIFT (43%) and RSVP (38%). The CFL group showed no significant differences in reading speed for the four methods.

Adolescent↗
PubMed2003

[Status of low-vision rehabilitation for age-related macular degeneration by orthoptists in the North of France].

AIM OF THE STUDY: To evaluate the status of low-vision rehabilitation carried out by the orthoptists in the North of France. This study was a preliminary step in setting up a network between different vision professionals for the management of age-related macular degeneration (AMD) the North of France. METHODS: The ASO (Association Septentrionale d'Ophtalmologie) conducted a survey funded by the URCAM (Union Régionale des Caisses d'Assurance Maladie) with the FAQSV (fond d'aide à la qualité des soins de ville). The survey was based on the analysis of two forms sent to orthoptists of the North region of France. RESULTS: The survey analyzed 46 responses (a representative sample with 69% responses) providing a description of the orthoptists of the North of France: 19% males, 81% females whose mean professional experience was 13.3 years. Thirty-four percent of the orthoptists have had training in low-vision rehabilitation. This training was given during the university courses for 21% of responders and during a postgraduate course for 79%. Of the orthoptists surveyed, 64% worked in a private context, 9% in a public context, and 27% in both public and private contexts. Their main activity was in their own private practice for 60%, in an ophthalmologist's office for 20%, in a public institution for 16%, and a private institution for 4%. The mean number of patients treated was 70 per week per orthoptist, with 21% working mostly with children, 36% working mainly with adults between 16 and 60 years of age, and 7% with the elderly, whereas 36% reported no specificity related to patient age. The mean number of patients dealt with for low vision related to AMD was 4.1 per month per orthoptist. The average number of patients dealt with for low vision with no relation to AMD was 1.5 per month. The prescriber of low-vision rehabilitation was an ophthalmologist for 88.9% of the orthoptists and a general practitioner for 11.1%. Questions addressed to AMD patients: at the beginning of the survey, 83.8% of the patients did not have sufficient visual acuity to be able to read a text of current size (Parinaud 4); 40.4% of the patients required help for everyday life, and 59.6% were autonomous. For 7.1% of the patients, low-vision rehabilitation was carried out less than 1 month after the stabilization of retinal lesions, but in 35.3%, rehabilitation was carried out more than 2 years after lesions were stabilized. The main request of the patients involved improvement of near vision (89.9%). CONCLUSION: This survey will be a preliminary step in setting up a regional health network coordinating the ophthalmological and orthoptic management of AMD.

Aged↗
PubMed1999

What is low vision? A re-evaluation of definitions.

PURPOSE: To re-evaluate definitions of low vision, visual impairment, and disability. METHODS: We review current definitions of legal blindness and low vision and how these definitions are variably based on disability or impairment. We argue for a definite distinction being made between criteria for visual impairment and visual disability, low vision being defined as the presence of a visual impairment that results in a disability. Visual impairment is defined according to population norms and a statistical cut-off is used. Visual disability is defined by consideration of the level of visual measures which result in measurable or reportable disability. We consider the evidence that contrast sensitivity should be a criterion for visual disability in addition to visual acuity and visual field. CONCLUSIONS: According to the current information, we define visual impairment as best monocular or binocular visual acuity <(worse than) 6/7.5, total horizontal visual field <146 degrees (Goldmann III-4e) or <109 degrees (III-3e), and contrast sensitivity <1.5 (PelliRobson); we define visual disability as best monocular or binocular visual acuity <6/12 or contrast sensitivity <1.05.

Blindness↗