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PubMedDate not supplied

Evaluating psychometric properties of a clinical and a self-report blind rehabilitation outcome measure.

This study assessed the psychometric properties and evaluated the compatibility of two blind and low-vision rehabilitation outcome instruments, the VA-13 and the Functional Assessment of Self-Reliance on Tasks (FAST). Legally blind veterans (N = 190) from a Department of Veterans Affairs inpatient blind rehabilitation center completed the VA-13 (a retrospective pretest and posttest) at 6 weeks postdischarge. Clinicians rated veterans on the FAST at admission and discharge. The psychometric properties of the two instruments and their compatibility were evaluated with the use of a Rasch model analysis. The two instruments functioned consistently as screens and showed a ceiling effect at posttest; however, the VA-13 showed poor sensitivity to change. In contrast, the FAST showed more reliable change, but a few items changed in unexpected ways. Our conclusions show that the two instruments are currently not compatible for calibration; however, this can be improved with proper attention to scaling inadequacies, test administration times, and content coverage.

Activities of Daily Living↗
PubMed1995

Causes of childhood blindness in east Africa: results in 491 pupils attending 17 schools for the blind in Malawi, Kenya and Uganda.

Pupils attending 12 schools for the blind in Malawi, 3 schools in Kenya and 2 schools in Uganda were examined to determine the causes of severe visual impairment or blindness (visual acuity in the better eye of less than 6/60). A total of 491 pupils aged 3-22 years was examined. Visual acuity was measured in each eye using a Snellen E chart. The anatomical site of abnormality and underlying cause of visual loss were determined by clinical examination for each eye, and for the child. Information was recorded on a standard reporting form (the WHO/PBL Eye Examination Record for Children with Blindness and Low Vision). Data were analysed for those aged less than 16 years using a database which accompanies the form. Preventable and treatable causes were identified. 260 pupils aged 5-20 years were examined in Malawi, 163 pupils aged 3-19 years were examined in Kenya and 68 pupils aged 6-22 years were examined in Uganda. Of the 491 students included in the study 309 (62.9%) were blind (BL) and 69 (14.1%) were severely visually impaired (SVI). 244 were aged less than 16 years and had SVI/BL. In these 244 children 35.2% of visual loss was due to corneal pathology, 13.5% was due to cataract and 14.8% to diseases of the retina. Corneal pathology, attributed to vitamin A deficiency and measles infection in the majority, was responsible for proportionally more SVI/BL in students in Malawi than in Uganda or Kenya.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2000

The practical near acuity chart (PNAC) and prediction of visual ability at near.

OBJECTIVE: To improve on present reading chart designs, providing a quick and accurate method to measure the near acuity threshold, of particular importance with low vision patients. DESIGN: The Practical Near Acuity Chart (PNAC) uses a single paragraph with 3 simple related words on each line (12 lower case letters). The line print size decreases in a logMAR progression (N80-N5). METHODS: The time taken to measure near acuity of 53 subjects aged 9-91 years with the PNAC and Bailey-Lovie near chart was recorded and compared to their distance acuity (Bailey-Lovie chart), contrast sensitivity (Melbourne Edge Test) and ability to read extracts of newsprint. RESULTS: There was no difference in near acuity threshold using related or un-related words. There was a high correlation (r = 0.97) between near acuity measured with the PNAC and Bailey-Lovie charts. However, the time taken to measure near acuity was significantly faster with the PNAC (32 +/- 2 s vs 76 +/- 4 s, p < 0.001). Near acuity measured with either chart was highly correlated (p < 0.001) to distance acuity (r = 0.74), contrast sensitivity (r = 0.62) and ability to read newsprint (r = 0.87). The PNAC was shown to have high test-reliable (r = 0.99). CONCLUSIONS: The PNAC offers a quick but accurate way to measure near acuity and shows a high degree of correlation with distance acuity, contrast sensitivity and the ability to read newsprint.

Adolescent↗
PubMed2001

A comparison of patient reading performance and preference: optical devices, handheld CCTV (Innoventions Magni-Cam), or stand-mounted CCTV (Optelec Clearview or TSI Genie).

BACKGROUND: Clinicians frequently prescribe reading devices for low vision patients having a central field loss. This study seeks to provide comparative information the clinician can use to assist patients in selecting the most cost-effective device(s) for reading. METHOD: In this study we compared optical devices with two types of closed-circuit televisions (CCTVs) that differed in two important characteristics: price, and whether the camera was stand-mounted with an X-Y table or whether the camera was handheld. A "within-subjects" design was used with 22 subjects. The primary comparisons between devices were subject reading speed, duration, and preference. RESULTS: Subject reading speed and duration were significantly greater with the CCTV systems than with optical devices; however, no significant performance differences were found between the two types of CCTVs. Patients did express a clear preference for one versus the other type of CCTV, with an overall preference for the stand-mounted system. When asked to consider the price differential between types of CCTVs, patient preferences were about equally divided. CONCLUSIONS: Clinicians can expect significantly better initial reading performance for patients with central visual-field losses when reading with CCTVs versus optical devices. Handheld CCTVs, when compared with stand-mounted systems, are less expensive, provide equal performance, and have slightly lower subject preference ratings. The current study provides clinicians with objective performance data and subjective preference data that can be used to help patients with central visual-field losses select the most cost-effective reading device.

Aged↗
PubMed2001

Ocular diseases and blindness in elderly Thais.

The prevalence of ocular disease and blindness in 2,092 Thai subjects, aged 60 years and over, in 33 communities in the vicinity of Siriraj Hospital, Bangkok was studied. The subjects were examined by a team which consisted of 3-4 ophthalmologists, 6 nurses and a trainee health officer. The history, visual acuity and ocular tension were recorded. The anterior and posterior segments of the eye were assessed by using a portable slit lamp biomicroscope, and a direct and indirect ophthalmoscope. The examination revealed disease of the lens in 1656 cases (79.16%), cornea 852 cases (40.72%), lid 516 cases (24.67%), conjunctiva 462 cases (22.08%), retina 300 cases (14.34%), glaucoma 128 cases (6.12%) and of the optic nerve in 39 cases (1.86%) respectively. There were 66 cases of blindness (3.15%) and 743 cases of low vision (35.5%). The causes of blindness were cataract, glaucoma, late age-related maculopathy, optic atrophy and corneal opacity.

Aged↗
PubMed1992

[Analysis of 10,686 cataract operations in Guangdong Province].

Among 10,686 cataract operations performed in Guangdong province from 1988 to 1989, 80.16% of the patients were over 55 years of age, the ratio of female to male was 1.37:1, and 53.76% were peasants, mostly little educated. Blindness was unilateral in 55.46%, bilateral in 38.83%, and low vision in 5.71%. The mode of operation was intracapsular in 68.83%, extracapsular in 25.77%, and couching in 0.52%. After operation, 50.20% of the patients were restored useful vision, and 45.25% saved from disablement, the total success rate being 95.45%. 2.13% were ineffective and 2.14% had complications. The curative effects were up to the standards stipulated by the National Federation of Disabled Persons.

Aged↗
PubMed1992

The utilization of a temporal mirror coating on the back surface of the lens as a field enhancement device.

A 37-year-old male had a right homonymous hemianopia due to trauma. During his initial low vision assessment, a small clip-on mirror was dispensed to help him compensate for his field loss. At follow-up, he reported satisfaction with the mirror. He also reported that novelty "look behind you" sunglasses were beneficial to him and less conspicuous than the clip-on mirror. He requested temporal mirror coating on otherwise clear lenses so that he could utilize the glasses at night or on cloudy days. We fabricated this for him and also mounted a small mirror nasally within the vertex distance behind his frame. The fabrication of the two devices will be discussed as well as a comparison of these three field enhancement devices.

Adult↗
PubMed2004

[Complications during the neonatal period can cause visual impairment later in life. Only few of the children were born prematurely--a surprising result of the study].

Forty per cent of children known at our low vision centre at the Department of Ophthalmology, University Hospital, Linköping, Sweden, had been treated in a neonatal ward after birth. Only few of them were born prematurely. Half of the children had an additional neurological handicap. The present neonatal screening program detects most cases of congenital cataract and all cases with retinopathy of prematurity.

Adolescent↗
PubMed1991

Reading performance of geriatric patients post exudative maculopathy.

This study was performed to evaluate any differences in reading speed and duration of comfortable reading speed in geriatric patients with post disciform stage exudative age-related macular degeneration (ARMD) or ocular histoplasmosis. Reading speed and duration with CCTV, illuminated stand magnifier, and spectacle lenses were compared for 37 patients in the Low Vision Program at the Central Blind Rehabilitation Center. Results indicate significantly faster reading speed with CCTV and spectacle lenses as compared to illuminated stand magnifiers. The difference between reading speeds measured with spectacle reading glasses and CCTVs was borderline significant. Patients read significantly longer with CCTVs than with spectacle lenses or illuminated stand magnifiers. No significant difference was found comparing spectacle lenses or illuminated stand magnifiers with regard to reading duration.

Aged↗
PubMed1991

[Risk factors and visual prognosis of 407 patients with retinal vein occlusion].

Among 407 patients (416 eyes) with retinal vein occlusion (RVO), 196 eyes had branch RVO, 185 eyes central RVO, and 26 eyes hemi-central RVO. The ischemic type accounted for 39.7%, and the non-ischemic type 60.3%. The risk factors were vascular hypertension (59.8%), retinal arteriosclerosis (58.0%), increased blood beta-lipoprotein (49.0%) and fibrinogen (21.7%), and high blood viscosity. The mean levels of whole blood and plasma viscosity were significantly higher in the patients than in the controls. The therapeutic effective rate was 63.2% for branch RVO, 52.4% for central RVO, and 69.2% for hemicentral RVO. The resultant rate of blindness was 15.9%, and that of low vision 23.1%, due to cystoid macular edema (44.4%) and vitreous hemorrhage (15.4%). The incidence of neovascular glaucoma was 9.5% in central RVO.

Adult↗
PubMed1989

Reproducibility of refraction and visual acuity measurement under a standard protocol. The Macular Photocoagulation Study Group.

The authors present results of a study in which certified visual acuity examiners in the Macular Photocoagulation Study Group, performed independent replicate refractions and visual acuity measurements on both eyes of patients whose visual acuities ranged from 20/20 to less than 20/800. Patients with neovascular age-related macular degeneration (AMD), ocular histoplasmosis, or idiopathic neovascularization were represented. A total of 328 observations for 164 eyes from 82 patients were available for analysis. Overall reliabilities of the refraction data and the visual acuity data were 98.9% and 98.7%, respectively. Differences between replicate measurements were small; 87% were less than one line. However, differences were greater in patients with visual acuity less than 20/100 and in patients with AMD. These results indicate that the reliability of refraction and visual acuity measurements under a standard protocol is high and may depend on both visual acuity level and disease process. If a standard, systemic procedure is used for refraction and visual acuity testing, the clinician may be able to differentiate between true changes and measurement error, even among low vision patients with AMD.

Aging↗
PubMed1989

Stand magnifiers: an evaluation of new optical aids from COIL.

This paper discusses stand magnifiers and the optical parameters that clinicians should know in order to understand the viewing requirements and the expected resolution for low vision patients. We report on measurements made of key optical parameters of a new series of stand magnifiers from Combined Optical Industries Limited (COIL) and comparison is made to the previous series of stand magnifiers from the same manufacturer. These results illustrate that manufacturers' specifications of optical parameters are generally inaccurate and misleading. We urge manufacturers to provide clinically relevant information about their optical products.

Equipment Design↗
PubMed1989

[A blindness prevention monitoring system and its application].

The authors conducted a survey of blindness and low vision in the population of 49,770 in Zhong Ning County of Ningxia Province and opened up blindness prevention and treatment with emphasis on cataract. Sight was restored to 88% of the curable blind, bringing down the rate of blindness from 0.24% to 0.14%. A blindness prevention monitoring system of 4 levels was established and its application and significance in the prevention of blindness explored.

Blindness↗
PubMed1989

[An epidemiologic survey of cataract in Shunyi County, Beijing].

The report presents the findings of an epidemiologic study of cataract in Shunyi County, Beijing, conducted in 1985, revealing that the general prevalence of senile cataract was 5.99%, and in people over 40 years of age, 18.58%; the rate obviously increased with age. Cataract accounted for 14.54% of the blind and 20.51% of the low-vision. The diagnostic criteria for senile cataract in surveys and the strategy for the prevention and treatment of senile cataract are recommended.

Adult↗
PubMed1995

A profile of the demographics, training and driving history of telescopic drivers in the state of Michigan.

BACKGROUND: Five-hundred twenty-eight licensed, telescopic drivers in the state of Michigan, were sent a questionnaire consisting of 50 questions to evaluate the demographics, formal training procedures experienced by these drivers, and their driving habits. METHODS: One-hundred forty-nine responses were tabulated to determine the characteristics of the telescopic driver in the state of Michigan. RESULTS: The findings show an increased necessity for dynamic assessment, training and follow-up of the telescopic wearer and for referral to a specific driving program to establish safe driving skills. CONCLUSION: As the field of low vision expands in its delivery of care, and with improvement in technology, the desire for telescopic driver's licenses will increase. The need for dynamic training procedures delivered by the multidisciplinary rehabilitative team becomes even more vital to ensure safe driving skills and to protect the privilege to drive. Extensive training, followup and communication must be an integral part of this process.

Adolescent↗
PubMed1994

Epidemiological aspects of visual impairment above 50 years in a rural area.

A cross-sectional survey was conducted in 5 villages in central India to find out the extent, causes and epidemiological factors for visual impairment among 903 individuals aged above 50 years; 44.3% of them were visually impaired (29.4% with low vision and 14.9% blind). Age-specific visual impairment increased at a rate of 13.2% with each decade of advancing age. Landless labourers suffered more from visual impairment than other occupational groups (p < 0.05). Socioeconomic and literacy status of the population did not significantly influence the prevalence of visual impairment. Major causes of visual impairment were cataract (48.5%), refractive errors (24.5%), age-related macular degeneration (10%), glaucoma (6.8%), and others (10.2%). In view of the high prevalence of visual impairment among the elderly individuals, it is necessary to intensify our efforts in motivating them for early detection and treatment.

Aged↗
PubMed1995

Recording eye movements using coaxial cameras--applications for visual ergonomics and reading studies.

We developed a system of coaxial video cameras that records monocular eye position and scene, and superimposes these images using a digital video mixer. We mounted miniature video cameras above and below a cube beam-splitting prism in the spectacle plane. An infrared emitting diode was imaged in the cornea to locate eye position. The technique was accurate to about 0.5 degrees within 15 degrees of primary gaze; however, we see its main advantages as being its low cost and simple design that, for some applications, does not require complex computer analysis and data manipulation. With improved camera optics, it has the potential for helmet mounting and use remote from a recording console. We used the instrument to monitor a reader's eye position when using low vision devices, and see applications of the technique in the field of visual ergonomics and sports vision.

Calibration↗
PubMed1996

Cataract free zone and primary health care approach to prevention of blindness in Shunyi county of Beijing.

OBJECTIVE: To establish a three-level eye care network, together with a referral and monitor system for the prevention of blindness, with the aim of creating a cataract free zone. SUBJECTS AND METHODS: Shunyi County with a population of 548364 was chosen as the target site. Our activities included (1) establishment of a County Guiding Committee for the prevention of blindness: (2) training local ophthalmologists and primary eye care personnel: (3) extensive publicity of knowledge for the prevention of blindness: (4) screening for blindness and low vision, (5) cataract surgery as the chief measure for creating a cataract free zone. RESULTS: A referral and monitor system for cataract blindness was established in 1987. Seven local ophthalmologists, 449 primary eye care health workers and six optometrists were trained. 815 cataract-blind patients were identified. Up to December 1991, 667 patients (737 eyes), accounting for 81.84% of the total, were treated with cataract surgery, 90.64% of these eyes had their sight restored, and 59.66% patients resumed work. A cataract free zone has been created in Shunyi County. CONCLUSIONS: The prevention of blindness with cataract surgery as the chief measure can dramatically decrease the prevalence of blindness in a relatively short period of time.

Blindness↗