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PubMed2003

The UWCDot colour vision test and low vision.

PURPOSE: Previous studies have shown that colour vision defects are common in the low vision population even when properly designed tests are used. However, there are very few clinical tests available that are suitable for this group of patients. One of the more common is the Jumbo D-15 (JD15). Although this test uses caps more suitable for the reduced acuity, it requires the patient to have some knowledge of colour order and sufficient dexterity to manipulate the caps. We compared the JD15 with the University of Waterloo Colored Dot test (UWCDot), which has neither of these requirements, to determine whether the UWCDot test could be used as a substitute for the JD15. METHODS: The colour vision of 40 consecutive low vision patients was evaluated with both tests. Acuities ranged from 6/6 to 6/1600 with a median value of 6/30. RESULTS: All subjects could perform both tests. The kappa coefficient of agreement between tests was high at 0.85 when any major crossing was a failure on the JD15 and any mistake was a failure on the UWCDot. Classification of the type of defect was also reasonable when the defect was relatively severe. CONCLUSIONS: The UWCDot can be used as a substitute for the JD15 in the low vision clinic. Both tests identify individuals with moderate-to-severe deficiencies, but the UWCDot does not require any manual dexterity and it does not require knowledge of colour-order.

Adolescent↗
PubMed1983

Effectiveness of the Humphrey Vision Analyzer low vision slide on the partially sighted.

Subjective refractions were performed on a variety of low vision patients using the Humphrey Vision Analyzer (HVA) which incorporates a low vision slide. Twenty-one eyes were examined and results were compared with standardized trial frame refraction findings. The results indicate that the HVA is an effective alternative procedure for some low vision patients, although several factors, including design of the slide, patient alignment, and target illumination, need to be carefully considered if this technique is to replace the conventional low vision trial frame examination.

Adolescent↗
PubMed1993

Discrepancy in the evaluation of visual impairment of elderly low-vision patients by general eye care practitioners and by low-vision practitioners.

Levels of impairment and disability determine eligibility for different welfare programs for visually handicapped persons. General eye care practitioners have to determine the level of impairment for administrative purposes, whereas the low-vision practitioner measures the level of impairment in order to plan the rehabilitation program. We compared the severity of visual impairment reported by the referring practitioners and the one reported by the low-vision specialists for the population of elderly low-vision patients receiving care from one of the largest rehabilitation centers for the visually handicapped in Quebec. Visual acuity ratings reported by general practitioners are lower than those reported by low-vision practitioners. The presence of visual handicap is generally well identified but the severity of visual impairment according to the World Health Organization (WHO)'s categories is not properly gauged by the general eye care practitioners as expressed by the sensitivity and the positive predictive value of the classification of the general practitioners in respect to the classification of the low-vision optometrists. The need to use existing standardized methods to measure visual acuity (VA) is emphasized. It may be hypothesized that this overestimation of the severity of the visual condition may have a negative impact on the process of rehabilitation of the elderly.

Aged↗
PubMed1992

Vision assessment and rehabilitation in low vision.

This subjective review of the year's literature on low vision, with particular emphasis on rehabilitation, attempts to search out and discuss what is new and innovative rather than to cover the year's publications with equal weight. The review covers areas of testing and assessment of children and the multiply impaired with low vision, vision stimulation, low vision aids and devices, approaches in congenital and acquired nystagmus, potential advances in high-technology applied to low vision, and psychological and educational aspects including lighting requirements for the elderly.

Disability Evaluation↗
PubMed2004

[Investigation of color vision using a web-based color vision test].

BACKGROUND: Screening tests of visual functions using the Internet are theoretically possible. To use these tests as a screening test, they must deliver comparable results with conventional test procedures. A web-based color vision test was developed based on pseudoisochromatic color plates. METHOD: The web-based color vision test was developed according to the pseudoisochromatic color plates by Velhagen and Broschmann using the programming-languages HTML, Java, and Perl. Sixty-five voluntary subjects, including nine color-deficient subjects, were examined by luminescence color plates (via web-based color vision test) and pigment color plates (via book). The statistical analysis was performed by determining the correspondence and the 95%-confidence interval. RESULTS: The correspondence of the test results for all subjects was 0.98 and the 95%-confidence interval was within 0.91 and 0.99. The correspondence of the test results in the group of color-deficient subjects was 1.0 and because of the limited number the 95%-confidence interval was within 0.71 and 1.0. CONCLUSIONS: The web-based color vision test with luminescence color plates for color-efficient and color-deficient subjects delivers test results comparable to pigment color plates under standardized examination conditions. Further studies are needed to examine if the web-based color vision test can also be used as an Internet screening test.

Adult↗
PubMed2000

The refractive status and vision profile: a questionnaire to measure vision-related quality of life in persons with refractive error.

OBJECTIVE/BACKGROUND: To describe the Refractive Status and Vision Profile (RSVP), a questionnaire that measures self-reported vision-related health status (symptoms, functioning, expectations, concern) in persons with refractive error. DESIGN: Cross-sectional study by survey. PARTICIPANTS: The RSVP was self-administered by 550 participants with refractive error (or history of refractive surgery) recruited from five refractive surgery practices and one optometric practice. Information on refraction, uncorrected and best-corrected visual acuity, and history of refractive surgery was obtained from physicians' records. METHODS: Internal consistency, test-retest reliability, agreement with global measures of vision (criterion validity), discriminant validity, content validity, and construct validity (associations of scale scores with patient status variables) were assessed using Cronbach's alpha, Spearman rank correlations, factor analysis, and multitrait analysis. OUTCOME MEASURES: Scores on the overall RSVP scale (S) and on eight RSVP subscales (functioning, driving, concern, expectations, symptoms, glare, optical problems, problems with corrective lenses) were calculated based on 42 items. RESULTS: Cronbach's alpha was 0.92 for S and ranged from 0.70 to 0.93 for RSVP subscales, indicating good internal consistency. Satisfaction with vision was more strongly associated with S than with refractive error or with visual acuity. Individuals with more refractive error had significantly lower (worse) scores for S and for subscales concern, functioning, driving, optical problems, and glare. Scores for S and for subscales concern, functioning, optical problems, and driving remained significantly associated with satisfaction with vision after adjustment for age, gender, corrective lens type, and refractive error. CONCLUSIONS: The RSVP measures a range of visual, functional, and psychologic impacts of refractive error that are likely to be important to patients. The RSVP would be a useful tool for evaluating interventions for correction of refractive error and may be useful for assessing refractive surgery candidates in clinical practice.

Adolescent↗
PubMed2005

Thirty years in an urban low vision clinic: changes in prescribing habits of low vision practitioners.

PURPOSES: The purposes of this study were to determine the types of low vision devices (LVDs) prescribed by clinicians in a large optometrist led hospital low vision clinic and to investigate changes in these prescribing habits between 1973 and 2003. METHODS: Data were collected from departmental records for all patients attending the low vision clinic at Moorfields Eye Hospital in London, U.K., during the month of June in 1973, 1978, 1983, 1988, 1993, 1998, and 2003. The primary outcome measure was the type or types of LVDs prescribed to patients attending the clinic for the first time. Data were collected on the age, sex, and diagnosis of all patients attending the clinic. RESULTS: One thousand four hundred thirty-eight patient visits were identified, of which 563 (39%) were first attendances. The median age of the patients examined did not change significantly over this time. Eighty-four percent of the patients attending the clinic for the first time were prescribed at least one LVD. The devices most frequently prescribed to new patients were nonilluminated hand magnifiers, illuminated hand magnifiers, and illuminated stand magnifiers. There was a linear increase in the proportion of hand magnifiers prescribed between 1973 and 2003 (r = 0.62, p < 0.05) and a corresponding decrease in the number of near spectacle-mounted telescopes prescribed (r = 0.70, p < 0.05). CONCLUSIONS: Between 1973 and 2003, the low vision clinic at Moorfields Eye Hospital provided nearly 100,000 low vision consultations. The demographics of patients attending the clinic remained remarkably constant over this time. The number of spectacle-mounted devices prescribed to new patients fell between 1973 and 2003. It is thought this is in part the result of the increased availability of electronic magnification devices and the development of illuminated hand magnifiers. The development of the acrylic bright field magnifier and LED-illuminated LVDs have had particular clinical impact.

Eyeglasses↗
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↗
PubMed1995

Prevalence of low vision in elderly patients admitted to an acute geriatric unit in Liverpool: elderly people who fall are more likely to have low vision.

The prevalence of visual impairment among elderly patients admitted to hospital is unknown. This group of patients may be particularly at risk from poor vision which could jeopardise their independence. A prospective study of visual imapairment and its aetiology in acute geriatric admissions assessed after the acute illness had settled was performed. Subjects were all patients aged 65 years or over, excluding those chronically confused, admitted to the Department of Geriatric Medicine at the Royal Liverpool University Hospital with an acute medical illness. After the acute illness had settled visual impairment, as defined by the American criteria (best acuity 6/18), was assessed on the ward with a Snellen chart read at 6 m using binocular vision and current glasses. Those patients identified with impaired vision on initial screening were formally assessed in the ophthalmology department to identify the cause. 200 patients were examined. 101 patients (50.5%) had impaired vision. In these patients, correctable refractive errors were present in 40%, cataract in 37% and senile macular degeneration in 14%. Of the 101 patients with impaired vision 79% had a reversible cause. Comparing these results with a recent study in the community showed a much higher incidence for patients admitted to hospital. There was a particularly high prevalence in those elderly patients who were admitted with falls (76%, p = 0.0003). In conclusion, elderly patients, especially those presenting with falls, admitted to hospital have a high prevalence of visual impairment. Visual impairment may be compounding or causing falls.(ABSTRACT TRUNCATED AT 250 WORDS)

Accidental Falls↗
PubMed2001

[Comparison study between biological vision and computer vision].

The development and bearing of biology vision in structure and mechanism were discussed, especially on the aspects including anatomical structure of biological vision, tentative classification of reception field, parallel processing of visual information, feedback and conformity effect of visual cortical, and so on. The new advance in the field was introduced through the study of the morphology of biological vision. Besides, comparison between biological vision and computer vision was made, and their similarities and differences were pointed out.

Aerospace Medicine↗
PubMed1997

Color vision defect type and spatial vision in the optic neuritis treatment trial.

PURPOSE: To describe the types of color vision defects present in the acute phase of the disease and 6 months into recovery in the 438 participants of the Optic Neuritis Treatment Trial. METHODS: Patients meeting strict eligibility criteria were seen within 8 days of the onset of symptoms and then at regular follow-up visits. At the first and 6-month visits (and subsequent annual visits), spatial vision (acuity, contrast sensitivity), visual fields, and color vision were measured. Farnsworth-Munsell 100-hue tests were scored by a variant of the method of quadrant analysis described by Smith et al (Am J Ophthalmol. 1985; 100:176-182). RESULTS: Most persons show mixed red-green (RG) and blue-yellow (BY) color defects (one type predominating, accompanied by a lesser defect of the other type). BY defects tend to be slightly more common in the acute phase of the disease, with slightly more RG defects at 6 months. Persons may shift defect type over time. Defect type was not related to any of the spatial vision measures at either test time or to treatment group; however, severity of color defect was related to both spatial vision measures and treatment group. CONCLUSIONS: Contrary to common clinical wisdom, optic neuritis is not characterized by selective RG defects. Color defect type cannot be used for differential diagnosis of optic neuritis.

Acute Disease↗
PubMed2003

The development of the LV Prasad-Functional Vision Questionnaire: a measure of functional vision performance of visually impaired children.

PURPOSE: To develop a reliable and valid questionnaire (the LV Prasad-Functional Vision Questionnaire, LVP-FVQ) to assess self-reported functional vision problems of visually impaired school children. METHODS: The LVP-FVQ consisting of 19 items was administered verbally to 78 visually impaired Indian school children aged 8 to 18 years. Responses for each item were rated on a 5-point scale. A Rasch analysis of the ordinal difficulty ratings was used to estimate interval measures of perceived visual ability for functional vision performance. RESULTS: Content validity of the LVP-FVQ was shown by the good separation index (3.75) and high reliability scores (0.93) for the item parameters. Construct validity was shown with good model fit statistics. Criterion validity of the LVP-FVQ was shown by good discrimination among subjects who answered "seeing much worse" versus "as well as"; "seeing much worse" versus "as well as/a little worse" and "seeing much worse" versus "a little worse," compared with their normal-sighted friends. The task that required the least visual ability was "walking alone in the corridor at school"; the task that required the most was "reading a textbook at arm's length." The estimated person measures of visual ability were linear with logarithm of the minimum angle of resolution (logMAR) acuity and the binocular high contrast distance visual acuity accounted for 32.6% of the variability in the person measure. CONCLUSIONS: The LVP-FVQ is a reliable, valid, and simple questionnaire that can be used to measure functional vision in visually impaired children in developing countries such as India.

Adolescent↗
PubMed1995

Vision development in the monocular individual: implications for the mechanisms of normal binocular vision development and the treatment of infantile esotropia.

PURPOSE: The purpose of this research is to study the vision development in monocular individuals so as to better understand normal binocular vision development and to refine the treatment of infants with infantile esotropia. METHODS: Thirty-six subjects with one clinically normal eye and one eye with no vision (no light perception or history of enucleation) are studied. In addition to measurement of standard parameters of development such as visual acuity, measurement of motion processing is made by both optokinetic and electrophysiologic techniques. A comparison is made of vision development among three populations: the monocular population, the normal population, and patients with a history of infantile esotropia. Such comparison is made to study the relative effects of interruption of binocularity and binocular competition. The monocular population represents individuals who have interruption of binocularity, whereas the infantile esotropia population has both interruption of binocularity and binocular competition. RESULTS: The OKN data suggest that the monucular population is more similar to the normal population than the esotropia population. The electrophysiologic data shows a statistically significant difference in the three populations. Motion processing is more fully developed in the monocular population than in the infantile esotropia population when compared to the normal population. CONCLUSIONS: 1. The development of motion processing appears to be particularly vulnerable to abnormal experience during the first year of life. 2. Monocular subjects have a less abnormal motion processing system when compared to patients with infantile esotropia even when monocularity is congenital. 3. The results indirectly support the premise that prealignment alternate occlusion is of benefit to the patient with infantile esotropia prior to realignment. 4. Development of the motion processing system does not necessarily parallel the development of other binocular functions.

Adolescent↗
PubMed1984

Low-vision aids for patients with suboptimal vision after closed vitrectomy for diabetic vitreous hemorrhage.

The use of low-vision aids to improve postoperative vision after successful closed vitrectomy for vitreous hemorrhage was evaluated in 30 diabetic patients. The distance vision improved with telescopic systems in 28 of 30 patients, whereas the near vision improved with microscopic systems in all cases. Patient acceptance of these low-vision aids was 50% for telescopic systems and 83% for microscopic systems.

Adult↗
PubMedDate not supplied

The impact of managed eye care on use of vision services, vision costs, and patient satisfaction.

OBJECTIVES: This study was designed to evaluate the impact of introducing a managed vision benefit program on the use and costs of vision services in a managed care setting and also to assess satisfaction with those services after the program was introduced. METHODS: Utilization and costs were compared for two groups of patients. The comparison group (n = 36,168) included all patients enrolled for 18 months before implementation of the managed eye-care plan. The study group (n = 23,816) included those enrolled for 18 months following its implementation. Medical claims, survey, and administrative data were used to evaluate study outcomes. RESULTS: The overall use of vision care was similar before and after the introduction of the managed eye-care programs, with 24% of each group receiving at least one vision service during the 18-month period. Nevertheless, an increase in the use of routine eye-care services and a decrease in medical eye-care services were observed following program implementation. The overall cost of providing eye-care services to patients decreased from 1.86 dollars to 1.36 dollars per member per month after the program started, largely owing to a reduction in spending associated with medical eye-care services. More than 90% of patients surveyed were satisfied with their vision care provided by the program. CONCLUSIONS: Findings suggest that introducing routine and medical managed eye-care programs in a managed care setting allows for a reduction in medical costs while maintaining access to care and patient satisfaction.

Adult↗
PubMed2004

Comparison of preschool vision screening tests as administered by licensed eye care professionals in the Vision In Preschoolers Study.

PURPOSE: To compare 11 preschool vision screening tests administered by licensed eye care professionals (LEPs; optometrists and pediatric ophthalmologists). DESIGN: Multicenter, cross-sectional study. PARTICIPANTS: A sample (N = 2588) of 3- to 5-year-old children enrolled in Head Start was selected to over-represent children with vision problems. METHODS: Certified LEPs administered 11 commonly used or commercially available screening tests. Results from a standardized comprehensive eye examination were used to classify children with respect to 4 targeted conditions: amblyopia, strabismus, significant refractive error, and unexplained reduced visual acuity (VA). MAIN OUTCOME MEASURES: Sensitivity for detecting children with > or =1 targeted conditions at selected levels of specificity was the primary outcome measure. Sensitivity also was calculated for detecting conditions grouped into 3 levels of importance. RESULTS: At 90% specificity, sensitivities of noncycloplegic retinoscopy (NCR) (64%), the Retinomax Autorefractor (63%), SureSight Vision Screener (63%), and Lea Symbols test (61%) were similar. Sensitivities of the Power Refractor II (54%) and HOTV VA test (54%) were similar to each other. Sensitivities of the Random Dot E stereoacuity (42%) and Stereo Smile II (44%) tests were similar to each other and lower (P<0.0001) than the sensitivities of NCR, the 2 autorefractors, and the Lea Symbols test. The cover-uncover test had very low sensitivity (16%) but very high specificity (98%). Sensitivity for conditions considered the most important to detect was 80% to 90% for the 2 autorefractors and NCR. Central interpretations for the MTI and iScreen photoscreeners each yielded 94% specificity and 37% sensitivity. At 94% specificity, the sensitivities were significantly better for NCR, the 2 autorefractors, and the Lea Symbols VA test than for the 2 photoscreeners for detecting > or =1 targeted conditions and for detecting the most important conditions. CONCLUSIONS: Screening tests administered by LEPs vary widely in performance. With 90% specificity, the best tests detected only two thirds of children having > or =1 targeted conditions, but nearly 90% of children with the most important conditions. The 2 tests that use static photorefractive technology were less accurate than 3 tests that assess refractive error in other ways. These results have important implications for screening preschool-aged children.

Amblyopia↗
PubMed1980

Effects of preschool screening for vision and hearing on prevalence of vision and hearing problems 6-12 months later.

In order to determine whether children screened 6-12 months previously for vision and hearing had fewer vision and hearing problems than a non-screened cohort, a trained nurse-tester examined 763 screened and 743 non-screened kindergarten children matched for age, sex, and socioeconomic status. The screened cohort had significantly fewer vision problems (10%) than the unscreened (15%). The difference for moderately severe problems (visual activity 20/50 or worse) was also significant. 58% more screened than unscreened children were wearing glasses. The screened cohort had more hearing problems (16.8%) than the non-screened group (14%), but the difference was not statistically significant. There was a marked seasonal variation in prevalence of hearing problems, the frequency in November and December being twice that in April, presumably a result of increased frequency of upper respiratory problems in those months. Preschool hearing screening, unlike vision screening, is not associated with improved end results.

Child, Preschool↗
PubMed1985

[Magnifying vision aids and their use by vision-handicapped patients].

Patients with visual acuities of below 0.4 at both long and short range cannot be sure of seeing well enough to read or watch TV. Low-vision aids improve vision to a such a degree that these activities can be performed once again. However, aside from this positive effect, low-vision aids have some disadvantages which sometimes prevent patients from actually using them. An investigation conducted among 150 patients revealed that 84% of them used their low-vision aids for about an hour or so a day.

Adolescent↗