A weighted version of the Melbourne Low-Vision ADL Index: a measure of disability impact

Development and Validation of the Life for Low Vision Questionnaire (LIFE4LVQ) Using Rasch Analysis: A Questionnaire Evaluating Ability and Independence

Low vision (LV) has a substantial impact on an individual’s daily functionality and patient-reported outcome measures (PROMs) are increasingly incorporated into the evaluation of this problem. The objective of this study was to describe the design of the new “Life for Low Vision Questionnaire (LIFE4LVQ)”, as a measure of daily functionality in LV and to explore its psychometric properties. A total of 294 participants completed the LIFE4LVQ and the data were subjected to Rasch analysis to determine the psychometric properties of the questionnaire, including response category ordering, item fit statistics, principal component analysis, precision, differential item functioning, and targeting. Test–retest reliability was evaluated with an interval of three weeks and intraclass correlation coefficients (ICC) were used. The correlation between the questionnaire score and Best Corrected Visual Acuity (BCVA) was examined using Spearman’s correlation coefficient. Rasch analysis revealed that for most items the infit and outfit mean square fit values were close to 1, both for the whole scale and its subscales (ability and independence). The separation index for person measures was 5.18 with a reliability of 0.96, indicating good discriminant ability and adequate model fit. Five response categories were found for all items. The ICC was 0.96 (p < 0.001; 95% CI, 0.93–0.98), suggesting excellent repeatability of the measure. Poorer BCVA was significantly associated with worse scores (rho = 0.559, p < 0.001), indicating excellent convergent validity. The functional, 40-item LIFE4LVQ proved to be a reliable and valid tool that effectively measures the impact of LV on ability and independence.

Reliability and validity of the Canadian-French ecological adaptation of the weighted version of the Melbourne low-vision ADL Index

Background: The Mesure de l'impact de la déficience visuelle dans les activités quotidiennes (MIDVAQ) is the Canadian-French adaptation of the Melbourne Low-Vision ADL Index. It measures performance, personal importance and handicap situation in 16 instrumental activities requiring near vision (standardized material, part A) and in 9 self-care and domestic activities (self-report questionnaire, part B). This study aimed at measuring the MIDVAQ reliability and its relationship with measures of visual functions and functional vision.Methods: The MIDVAQ was administered twice to 100 visually impaired participants, at home, with their personal visual and non-visual aid. A second rater was present at T1. Two different versions of part A were used alternately at T1 and T2.Results: The total Handicap scale demonstrates good internal reliability (Cronbach's alpha coefficient = 0.82) and very high inter-rater and test-retest reliability (ICCs = 1.00 and 0.86). Part A alternative versions are highly comparable. Vision function measures are significantly correlated with total Handicap score, for which 48% of the variance is explained by functional vision estimates, age, and education.Conclusions: The MIDVAQ is highly valid and reliable. It can be useful to measure the functional impact of the visual impairment, its progression, and the outcomes of low vision rehabilitation services.Implications for rehabilitationEven if administered at home in an ecological way, this measure of the impact of the visual impairment in daily activities is very reliable.Given its good metric properties, this tool can be confidently used to assess the functional impact of visual impairment, outcomes of the low vision rehabilitation services, etc.This measurement tool provides complementary information to those obtained from clinical measures of visual functions, by reflecting the interaction between the functional abilities with the requirements of the environment.

Occupational performance in the basic and instrumental daily activities of persons with low vision who received rehabilitation services

Introduction

The objective was to describe the occupational performance in basic and instrumental daily activities of persons living in the community who have received comprehensive interdisciplinary low vision rehabilitation services.

Method

The Mesure de l'impact de la déficience visuelle dans les activités quotidiennes (a measure of the impact of visual impairment in daily activities) was administered at home to 102 individuals who participated in a comprehensive low vision rehabilitation program. Performance in 16 near-vision activities was measured with the person's aids and strategies; nine more global tasks were questionnaire-based. Handicap scores were obtained by multiplying performance × importance ratings.

Results

Average performance was satisfactory or very satisfactory for 21/25 items, even if 92% of the participants had a moderate or severe visual impairment. A severe or total handicap was present in at least one activity for 79% of the subjects. The most handicapping activities required visual searches of finely printed information on a complex or visually crowded document, or shopping and mobility.

Conclusion

People with low vision who took part in a comprehensive rehabilitation program generally face no or slight handicap situations in their basic and instrumental daily activities. However, major handicap situations may remain in some important activities.

Patient-Centered Outcome Measures to Assess Functioning in Randomized Controlled Trials of Low-Vision Rehabilitation: A Review

Low-vision rehabilitation (LVR) aims to improve the functioning of patients with chronic uncorrectable visual impairment. LVR is inherently a patient-centered intervention since its approach and goals are dictated by the needs and abilities of each individual patient. Accordingly, it is essential to have patient-centered outcome (PCO) measures to assess and compare the efficacy and effectiveness of low-vision interventions; however, there is a lack of evidence on the effectiveness of LVR interventions. We reviewed the literature in order to identify randomized controlled trials (RCTs) in the field of LVR and the outcome measures used to assess patient functioning in these trials. We identified 15 RCTs of LVR that employed nine unique patient-reported, five unique performance-based, and one hybrid (combined patient-reported and performance) outcome measures. Since these trials used distinct tools to assess patient functioning, it is difficult to compare the effectiveness of competing rehabilitation interventions across studies. Selecting valid outcome measures that are both relevant to LVR goals of specific patient populations and that measure functioning across a range of visually demanding tasks could improve the ability to detect the effect of LVR and to compare rehabilitation strategies. There are advantages and limitations to the use of both patient-reported and performance-based outcome measures, and additional work should be undertaken to explore the relationship between these modes of assessment, as well as strategies for optimally integrating these approaches. Careful selection of outcome measures in the design of future RCTs in LVR may lead to improved understanding of the effectiveness of LVR and, ultimately, to improved functioning of patients with low vision.

The assessment of disability related to vision performance-based measure in diabetic retinopathy

PURPOSE

To validate a third-generation performance-based measure of visual function titled "Assessment of Disability Related to Vision" (ADREV) in a study population of patients with diabetic retinopathy.

DESIGN

Prospective, cross-sectional study.

METHODS

Patients with nonproliferative or proliferative diabetic retinopathy, free from ocular comorbidity, were recruited from a single institute and completed the ADREV, the 25-Item National Eye Institute Visual Functioning Questionnaire (VFQ-25), and a clinical ophthalmic examination. Correlation, regression, and bootstrap analysis were conducted to determine the relationship between ADREV scoring and each of the study's clinical and self-report measures of visual ability, while controlling for potential confounders.

RESULTS

Ninety-one patients with diabetic retinopathy completed the study and analysis showed that the ADREV total and subscale scores shared a stronger relationship with the clinical measures of visual function than did the VFQ total and subscale scores. Regression analysis revealed that binocular visual acuity, contrast sensitivity, and better eye visual field were the best predictors of ADREV performance.

CONCLUSIONS

The ADREV performance measure is a valid instrument for the assessment of disability related to vision in patients with diabetic retinopathy. Furthermore, the assessments provided by ADREV were more related to traditional clinical indicators of visual impairment than were the results of the self-report measure, specifically the VFQ-25.

Validation of the visual disability questionnaire (VDQ) in India

PURPOSE

To validate visual disability questionnaire (VDQ) in patients with low vision in India, and explore whether the two latent traits "importance" and "difficulty" associated with performance of daily activities are valid and independent constructs.

METHODS

The VDQ consisting of 25 items was administered verbally to 137 subjects with low vision aged 16 to 89 years. Responses for each item were rated for importance and difficulty using a 5-category Likert scale. Rasch analysis was used to estimate interval measures of response ratings.

RESULTS

Subjects could discriminate only three response categories for importance and difficulty. Content validity was demonstrated by good separation indices for importance (4.24 and 2.59 for the item and person parameters, respectively) and difficulty ratings (7.64 and 3.33, respectively). High reliability scores were recorded for importance (0.95 and 0.87) and difficulty ratings (0.98 and 0.92). The most important items were "grooming" (1.15 logits) and "reading newspaper" (0.97 logits). Although "threading a needle" was the least important item (-2.79 logits), it was the most difficult task (3.13 logits). The least difficult item was moving around in familiar places (-2.51 logits). A poor correlation was observed between the item measures (r = -0.19, p = 0.34) and also between person measures (r = 0.18, p = 0.03) of importance and difficulty.

CONCLUSIONS

The VDQ is a valid questionnaire with importance and difficulty ratings found to be independent constructs. This questionnaire could be used to prioritize the goals for rehabilitation intervention in patients with low vision.

Personal impact of disability in osteoarthritis: patient, professional and public values

BACKGROUND

Osteoarthritis (OA) is a leading cause of disability. Numerous tools are available to assess this, but they fail to place a patient value upon disability. In rheumatoid arthritis, research has shown patients have different importance values for similar disabilities, and these individual values can be used to weight disability levels, creating a measure of personal impact.

OBJECTIVES

Firstly, to determine if the Health Assessment Questionnaire (HAQ) can be used as the basis for an importance value scale by assessing if it includes activities considered important by OA patients. Secondly, to determine if the weights used for the value scale should be based on population, healthcare professional or patient values.

METHOD

Twenty-five OA patients, 25 healthy controls and 25 healthcare professionals rated the importance of the items on the HAQ and shortened Modified HAQ (MHAQ). Prior to completing the HAQ, patients generated a list of activities that were important to them.

RESULT

The HAQ contained 69% of items that patients considered important. No items were consistently deemed unimportant by patients. There was low agreement within and between groups about the importance of the items on the HAQ and MHAQ.

CONCLUSION

The HAQ is a suitable basis for a value scale for an OA disability impact score. Importance values for function differed for patients, healthcare professionals and the general population; therefore individual patient weightings need to be used. Further work is under way to validate a measure of the personal impact of disability in patients with lower limb OA.

Assessment of function related to vision (AFREV)

OBJECTIVES

To evaluate the relationship of a performance-based measure of visual functioning to clinical and subjective measures in glaucoma patients.

DESIGN

Cross-sectional survey of glaucoma patients.

PARTICIPANTS

Forty-three patients with primary open-angle glaucoma.

METHODS

Patients were evaluated using a novel performance-based measure, the Assessment of Function Related to Vision (AFREV), standard clinical tests of visual function, and the National Eye Institute's Visual Functioning Questionnaire (NEI-VFQ-25), a self-reported quality of life measure. Correlations of the AFREV scores with visual field scores, monocular and binocular visual acuity, contrast sensitivity scores, and NEI-VFQ scores were calculated. Rasch analysis was used to estimate the visual ability required by each task of AFREV for a particular response (item measures) and to estimate the visual ability of each patient (person measures).

MAIN OUTCOME MEASURES

AFREV and NEI-VFQ total scores.

RESULTS

The AFREV total scores were highly correlated with contrast sensitivity (r = 0.772), binocular visual acuity (r = -0.768), better-eye visual acuity (r = -0.737), worse-eye visual acuity (r = -0.675), and Estermann visual field efficiency scores (r = 0.606) as well as with NEI-VFQ scores (r = 0.70). The resulting index, constructed from 5 items of the AFREV, is unidimensional, thereby satisfying the primary assumption of the Rasch model. The Rasch person-item map demonstrates that the "putting stick into holes" and "reading small print" tests require the most visual ability.

CONCLUSIONS

The AFREV performance-based measure, a new test of a spectrum of activities, correlates well with some standard measures of visual function and certain aspects of self-report assessments. AFREV appears to be a valid measure of performance ability that may provide information not obtainable from standard measures of visual function or subjective surveys.

Evaluation of Melbourne Edge Test contrast sensitivity measures in the visually impaired

AIM

Contrast sensitivity (CS) provides important information on visual function. This study aimed to assess differences in clinical expediency of the CS increment-matched new back-lit and original paper versions of the Melbourne Edge Test (MET) to determine the CS of the visually impaired.

METHODS

The back-lit and paper MET were administered to 75 visually impaired subjects (28-97 years). Two versions of the back-lit MET acetates were used to match the CS increments with the paper-based MET. Measures of CS were repeated after 30 min and again in the presence of a focal light source directed onto the MET. Visual acuity was measured with a Bailey-Lovie chart and subjects rated how much difficulty they had with face and vehicle recognition.

RESULTS

The back-lit MET gave a significantly higher CS than the paper-based version (14.2 +/- 4.1 dB vs 11.3 +/- 4.3 dB, p < 0.001). A significantly higher reading resulted with repetition of the paper-based MET (by 1.0 +/- 1.7 dB, p < 0.001), but this was not evident with the back-lit MET (by 0.1 +/- 1.4 dB, p = 0.53). The MET readings were increased by a focal light source, in both the back-lit (by 0.3 +/- 0.81, p < 0.01) and paper-based (1.2 +/- 1.7, p < 0.001) versions. CS as measured by the back-lit and paper-based versions of the MET was significantly correlated to patients' perceived ability to recognise faces (r = 0.71, r = 0.85 respectively; p < 0.001) and vehicles (r = 0.67, r = 0.82 respectively; p < 0.001), and with distance visual acuity (both r = -0.64; p < 0.001).

CONCLUSIONS

The CS increment-matched back-lit MET gives higher CS values than the old paper-based test by approximately 3 dB and is more repeatable and less affected by external light sources. Clinically, the MET score provides information on patient difficulties with visual tasks, such as recognising faces.

Blindness, low vision, and other handicaps as risk factors attached to institutional residence

AIMS

To estimate the risk of living in an institution and being visually impaired.

METHODS

Two national surveys were pooled: (1) 2075 institutions (for children or adults with handicaps, old people, and psychiatric centres) were selected randomly, in 18 predefined strata, from the French health ministry files. From these institutions, 15 403 subjects were selected randomly and handicap was documented by interview in 14 603 (94.9%) of them; (2) level of handicap was documented in a randomised, stratified sample of 356 208 citizens living in the community; from this sample, 21 760 subjects were further selected at random and 16 945 people were interviewed. Data on handicaps (visual, auditory, speech, brain, visceral, motor, and other) and activities of daily living (ADL) were extracted. The odds ratio (OR) of living in an institution was estimated, using stepwise logistic regressions with age, geographical area, handicaps, and ADL as co-variables.

RESULTS

Subjects in institutions, compared to those living at home, were, respectively, more often female (64.3% v 52.4%) and older (68.7 v 38.0 years); they more often had handicaps (ORs: speech, 6.59; brain, 10.17; motor, 8.86; visceral, 3.49; auditory, 2.66; other, 1.53); and were less often able to perform their ADL (46.2% v 97.1%) without assistance. Below 80 years, blind people were more often in institutions (ORs 0.239 to 0.306); whereas in older people the association was reversed (OR: 3.277). Low vision was always significantly associated with institutional residence (ORs from 0.262 to 0.752).

CONCLUSION

Visual handicap was associated with institutional residence. The link persisted after adjustment for known confounding factors.

Normative contrast sensitivity values for the back-lit Melbourne Edge Test and the effect of visual impairment

BACKGROUND

The Melbourne Edge Test (MET) is a portable forced-choice edge detection contrast sensitivity (CS) test. The original externally illuminated paper test has been superseded by a backlit version. The aim of this study was to establish normative values for age and to assess change with visual impairment.

METHOD

The MET was administered to 168 people with normal vision (18-93 years old) and 93 patients with visual impairment (39-97 years old). Distance visual acuity (VA) was measured with a log MAR chart.

RESULTS

In those eyes without disease, MET CS was stable until the age of 50 years (23.8 +/- 0.7 dB) after which it decreased at a rate of approximately 1.5 dB per decade. Compared with normative values, people with low vision were found to have significantly reduced CS, which could not be totally accounted for by reduced VA.

CONCLUSIONS

The MET provides a quick and easy measure of CS, which highlights a reduction in visual function that may not be detectable using VA measurements.

Correctable visual impairment in older people: a major unmet need

This review seeks to determine the prevalence of correctable visual impairment (VI) in older people in the UK, to discover what proportion of these cases are undetected, to suggest reasons for the poor detection and to make recommendations for improving the detection. To establish the context of these issues, the review will also touch on the general prevalence and causes of VI in older people in developed countries and on the impact of VI in older people. Typically, studies suggest that VI affects about 10% of people aged 65-75, and 20% of those aged 75 or older. There is a strong relationship between impaired vision in older people and both reduced quality of life and increased risk of accidents, particularly falls. The literature suggests that those with low vision are about two times more likely to have falls than fully sighted people, and the annual UK cost of treating falls directly attributable to VI is pound 128 million. The literature on the prevalence of undetected reduced vision in older people reveals that between 20 and 50% of older people have undetected reduced vision. The majority of these people have correctable visual problems (refractive errors or cataract). It is particularly startling that, in 'developed countries', between 7 and 34% of older people have VI that could simply be cured by appropriate spectacles. The reasons why so many cases of treatable VI remain untreated are discussed, and suggestions are made for improving the detection of these cases. We conclude that there should be better publicity encouraging older people to attend for regular optometric eye examinations. A complementary approach is annual visual screening of the elderly, possibly as part of GPs annual health check on people aged 75 years and older. Recommendations are made for evaluating new approaches to screening and for improving the management of cases detected by screening.