Optimizing measurement of vision-related quality of life: a computerized adaptive test for the impact of vision impairment questionnaire (IVI-CAT).

PURPOSE: To compare the results from a simulated computerized adaptive test (CAT) for the 28-item Impact of Vision Impairment (IVI) questionnaire and the original paper-pencil version in terms of efficiency (main outcome), defined as percentage item reduction. METHODS: Using paper-pencil IVI data from 832 participants across the spectrum of vision impairment, item calibrations of the 28-item IVI instrument and its associated 20-item vision-specific functioning (VSF) and 8-item emotional well-being (EWB) subscales were generated with Rasch analysis. Based on these calibrations, CAT simulations were conducted on 1000 cases, with 'high' and 'moderate' precision stopping rules (standard error of measurement [SEM] 0.387 and 0.521, respectively). We examined the average number of items needed to satisfy the stopping rules and the corresponding percentage item reduction, level of agreement between person measures estimated from the full IVI item bank and from the CAT simulations, and item exposure rates (IER). RESULTS: For the overall IVI-CAT, 5 or 9.7 items were required, on average, to obtain moderate or high precision estimates of vision-related quality of life, corresponding to 82.1 and 65.4% item reductions compared to the paper-pencil IVI. Agreement was high between the person measures generated from the full IVI item bank and the IVI-CAT for both the high precision simulation (mean bias, - 0.004 logits; 95% LOA - 0.594 to 0.587) and moderate precision simulation (mean bias, 0.014 logits; 95% LOA - 0.828 to 0.855). The IER for the IVI-CAT in the moderate precision simulation was skewed, with six EWB items used > 40% of the time. CONCLUSION: Compared to the paper-pencil IVI instrument, the IVI-CATs required fewer items without loss of measurement precision, making them potentially attractive outcome instruments for implementation into clinical trials, healthcare, and research. Final versions of the IVI-CATs are available.

The relationship between diabetic retinopathy and psychosocial functioning: a systematic review.

IMPORTANCE: Previous work has reported a link between diabetic retinopathy/diabetic macular edema (DR/DME) and psychosocial functioning, although the extent and direction of the association remains uncertain. OBJECTIVE: To determine the relationship between DR/DME and psychosocial functioning, the latter an umbrella term used to capture the emotional and social aspects of functioning which may include, for example, depression; depressive disorder; anxiety; vision-specific distress; diabetes-specific distress and emotional and social well-being. EVIDENCE REVIEW: PubMed, Embase, Medline and the Cochrane Central register were systematically searched for relevant interventional and observational quantitative studies using standardised criteria. Studies with DR/DME and psychosocial functioning as exposures or outcomes were accepted. Study quality was evaluated using the modified Newcastle-Ottawa scale for observational studies, and the modified Down's and Black checklist for interventional studies. FINDINGS: Of 1827 titles initially identified, 42 were included in the systematic review. They comprised of four interventions (one RCT, three non-RCTs) and 38 observational studies (33 cross sectional, five prospective). In studies with DR/DME as the exposure (n = 28), its severity and related vision impairment were consistently associated with poor psychosocial outcomes, mostly higher incidence of depression and depressive symptoms. Baseline depression and depressive symptoms were also associated with greater DR incidence and progression of DR. Medical intervention strategies showed significant improvement in psychosocial outcomes in patients with DR, such as significant improvements in mental health domain scores of the National Eye Institute Visual Function Questionnaire-25 (NEI VFQ 25). CONCLUSION AND RELEVANCE: Severity of DR, DME and associated vision loss are significantly associated with poor psychosocial outcomes. Aspects of depression and its symptoms show a bi-directional association, with increased incidence and progression of DR significant in those with baseline depression or depressive symptoms. Based on these findings, we propose two areas that may benefit from targeted interventions: (1) Prevention of development of poor psychological outcomes by preventing and delaying progression of DR/DME; and (2) Improved detection and management of poor psychological functioning by improving screening tools and multidisciplinary care for patients. Subsequent longitudinal studies can further help establish the underlying relationship between the two measures.

Reducing respondent burden: validation of the Brief Impact of Vision Impairment questionnaire.

PURPOSE: To develop a psychometrically sound and valid Brief Impact of Vision Impairment (IVI) questionnaire. METHODS: Cross-sectional data from four prospective studies (2001-2008) were pooled and randomly divided into development/validation sets (n = 416) each. Items with suboptimal psychometric properties were iteratively removed in the development set to form the Brief IVI. Psychometric properties of the Brief IVI were independently tested in the validation sample. Correlation between person measures from the original and Brief IVI was assessed [Pearson r and intraclass correlation coefficient (ICC)]. Criterion validity was determined by testing the Brief IVI's ability to discriminate levels of vision impairment (analysis of variance, ANOVA). Responsiveness was tested by comparing the ICC of the original and Brief IVI data obtained pre-/post-intervention. RESULTS: The 15-item Brief IVI, and its 9-item Visual Functioning and 6-item Emotional Well-being subscales had ordered thresholds, good precision and targeting, unidimensionality, and minimal item misfit (replicated in the validation sample). Brief and original IVI person measures were highly correlated (r = 0.97 and ICC = 0.98, p < 0.001), indicating the Brief IVI provides statistically similar measurement of vision-related quality of life (VRQoL). Brief IVI mean logit scores declined as vision impairment worsened (p = 0.001) demonstrating criterion validity. ICC of the original versus Brief IVI pre-/post-intervention was excellent (0.98), establishing that the Brief IVI was as responsive to changes in VRQoL as the original. CONCLUSIONS: The Brief 15-item IVI can obtain valid and responsive measurement of VRQoL with half the items in the original and has potential to reduce respondent burden in QoL studies.

Assessment of the psychometric properties of the Chinese Impact of Vision Impairment questionnaire in a population-based study: findings from the Singapore Chinese Eye Study.

PURPOSE: We investigated whether the Chinese impact of vision impairment (IVI) questionnaire is valid to generate reliable person estimates in a population-based sample. METHODS: VRQoL was measured using the 32-item Chinese version of the IVI questionnaire in the Singapore Chinese Eye Study (2009-2011), a population-based study of the prevalence and risk factors for VI and eye diseases in Chinese Singaporeans. Rasch analysis was used to assess the Chinese IVI's response category functioning, precision, unidimensionality, targeting and differential item functioning. The ability of the Chinese IVI to discriminate participants along the spectrum of VI demonstrated criterion validity. RESULTS: Of the 3353 participants, 27.2 % (n = 912) had VI (presenting visual acuity <6/12, better eye). Response categories were collapsed from six to four to resolve disordered thresholds. The Chinese IVI initially demonstrated multidimensionality and was split into three scales: 'Reading and Accessing Information'; 'Mobility and Independence'; and 'Emotional Well-being'. All three scales were unidimensional and demonstrated excellent range-based precision (all reliability coefficients 0.97), following removal of three misfitting items. Mean person measures decreased with worsening VI (e.g. Reading: none (7.50 logits); mild (6.99 logits); moderate (6.44 logits); and severe (3.01 logits) VI; p < 0.001). CONCLUSIONS: A three-dimensional 29-item Chinese IVI is a valid tool to assess the impact of VI on VRQoL in a large population-based sample, comprising over a quarter of participants with VI. The 28-item English IVI is also likely to be valid for use in population-based studies; however, this must be demonstrated empirically in future studies.

Evaluation of item candidates for a diabetic retinopathy quality of life item bank.

PURPOSE: We are developing an item bank assessing the impact of diabetic retinopathy (DR) on quality of life (QoL) using a rigorous multi-staged process combining qualitative and quantitative methods. We describe here the first two qualitative phases: content development and item evaluation. METHODS: After a comprehensive literature review, items were generated from four sources: (1) 34 previously validated patient-reported outcome measures; (2) five published qualitative articles; (3) eight focus groups and 18 semi-structured interviews with 57 DR patients; and (4) seven semi-structured interviews with diabetes or ophthalmic experts. Items were then evaluated during 3 stages, namely binning (grouping) and winnowing (reduction) based on key criteria and panel consensus; development of item stems and response options; and pre-testing of items via cognitive interviews with patients. RESULTS: The content development phase yielded 1,165 unique items across 7 QoL domains. After 3 sessions of binning and winnowing, items were reduced to a minimally representative set (n = 312) across 9 domains of QoL: visual symptoms; ocular surface symptoms; activity limitation; mobility; emotional; health concerns; social; convenience; and economic. After 8 cognitive interviews, 42 items were amended resulting in a final set of 314 items. CONCLUSIONS: We have employed a systematic approach to develop items for a DR-specific QoL item bank. The psychometric properties of the nine QoL subscales will be assessed using Rasch analysis. The resulting validated item bank will allow clinicians and researchers to better understand the QoL impact of DR and DR therapies from the patient's perspective.

Patients' causal beliefs about diabetic retinopathy.

PURPOSE: This study explored patients' understanding of the risk factors for diabetic retinopathy (DR) and their personal beliefs about the cause and controllability of their own DR, as well as health professionals' perceptions of patients' understanding of DR and its cause. METHODS: Eight focus groups and 18 semistructured interviews were conducted with 57 patients with DR, and seven semistructured interviews were conducted with diabetes and ophthalmic specialists. Sessions were transcribed verbatim and iteratively analyzed using the constant comparative method and NVIVO software. RESULTS: Nearly 50% of participants had proliferative DR, and most patients had undergone laser treatment. Patients had a reasonable understanding of the basic risk factors for DR such as diabetes control, although they were less clear about specific risk factors such as blood pressure and lipid control. Regarding their own disease, most patients attributed their DR either to poor diabetes control or to failings of the health care system. Some patients believed that their DR was a result of health aspects beyond their control or environmental factors, whereas others were unsure about the cause. Diabetes and ophthalmic specialists believed that many patients lacked understanding about the cause of their DR and the goal and outcome of laser treatment. Difficulty communicating the abstract concept of laser treatment outcomes in the face of concrete (yet erroneous) anecdotal evidence of the detrimental impact of laser on visual acuity was highlighted as a major barrier to mitigating patients' harmful beliefs about treatment. CONCLUSIONS: This study revealed some important gaps in patients' knowledge and potentially damaging beliefs about the cause and treatment of DR despite most patients having considerable exposure to eye health professionals and DR treatment. Improving patients' understanding of the major risk factors for DR and the realistic outcomes of laser treatment may improve patients' coping mechanisms, adaption to disease, and ocular outcomes.

The impact of diabetic retinopathy on quality of life: qualitative findings from an item bank development project.

PURPOSE: Assessing the efficacy of treatment modalities for diabetic retinopathy (DR) from the patient's perspective is restricted due to a lack of a comprehensive patient-reported outcome measure. We are developing a DR-specific quality of life (QoL) item bank, and we report here on the qualitative results from the first phase of this project. METHODS: Eight focus groups and 18 semi-structured interviews were conducted with 57 patients with DR. The sessions were transcribed verbatim and iteratively analysed using the constant comparative method and NVIVO software. RESULTS: Participants had a median age of 58 years (range 27-83 years). Twenty-seven (47%) participants had proliferative DR in the better eye, and 14 (25%) had clinically significant macular oedema. Nine QoL domains were identified, namely visual symptoms, ocular surface symptoms, vision-related activity limitation, mobility, emotional well-being, health concerns, convenience, social, and economic. Participants described many vision-related activity limitations, particularly under challenging lighting conditions; however, socioemotional issues were equally important. Participants felt frustrated due to their visual restrictions, concerned about further vision loss and had difficulty coping with this uncertainty. Restrictions on driving were pervasive, affecting transport, social life, relationships, responsibilities, work and independence. CONCLUSIONS: Patients with DR experience many socioemotional issues in addition to vision-related activity limitations. Data from this study will be used to generate data for a DR-specific QoL item bank.

Social and emotional impact of diabetic retinopathy: a review.

People with vision-threatening diabetic retinopathy are likely to experience enhanced social and emotional strain. Critically, those with both vision-threatening diabetic retinopathy and psychosocial problems may have significantly reduced levels of functioning compared with psychologically healthy counterparts. This can cause inadequate compliance, increased strain on family functioning, worse diabetes control, increased progression of diabetic retinopathy and, consequently, further psychosocial stress resulting in a number of concerning implications for disease management, clinical outcomes and healthcare costs. However, the emotional and social health consequences of diabetic retinopathy have not yet been systematically explored. This information is crucial as it allows for a targeted approach to treatment and prevention and avoidance of the potentially detrimental implications described above. Therefore, this paper reviews the current qualitative and quantitative evidence regarding the social and emotional impact of diabetic retinopathy and identifies directions for future research. Key search terms were applied to the electronic databases Pubmed, ISI Web of Science and Embase and the bibliographies of relevant papers were systematically reviewed for additional references. Overall, the evidence suggests that diabetic retinopathy and associated vision loss have several debilitating effects, including disruption of family functioning, relationships and roles; increased social isolation and dependence; and deterioration of work prospects resulting in increased financial strain. Adverse emotional responses include fear, anxiety, vulnerability, guilt, loss of confidence, anger, stress and self-perception issues. However, the research to date is largely qualitative in nature, with most quantitative studies being small, cross-sectional and somewhat outdated. Similarly, the outcome measures used in many studies to date are suboptimal in terms of content and validity. Therefore, this review identifies the need for improved outcome measures to provide valid, meaningful measurement of the social and emotional impact of diabetic retinopathy and discusses potential directions for future research such as item banking and computer adaptive testing.

Methodology and early findings of the Diabetes Management Project: a cohort study investigating the barriers to optimal diabetes care in diabetic patients with and without diabetic retinopathy.

BACKGROUND: The Diabetes Management Project is investigating the clinical, behavioural and psychosocial barriers to optimal diabetes care in individuals with and without diabetic retinopathy. DESIGN: Prospective cohort. PARTICIPANTS: Two hundred and twenty-three and 374 patients without and with diabetic retinopathy, respectively. METHODS: All individuals underwent a comprehensive dilated eye test, anthropometric measurements, blood and urine samples, and psychosocial questionnaires. MAIN OUTCOME MEASURES: Good glycaemic control was defined as glycosylated haemoglobin < 7%, good blood pressure control as systolic and diastolic values ≤130 and 80 mmHg, respectively, and good diabetes control as glycosylated haemoglobin < 7% and blood pressure values ≤130 and 80 mmHg. RESULTS: Four hundred and one males (65.4%) and 212 females (34.6%) aged 26-90 years (mean age ± standard deviation = 64.6 ± 11.6) were examined. The median glycosylated haemoglobin for all participants was 7.5% (interquartile range = 1.7%). Average systolic and diastolic blood pressure values were 139.7 mmHg (standard deviation = 18.8) and 92.7 mmHg (standard deviation = 30.9), respectively. Initial data analyses indicate that over two-thirds of participants with diabetes have poor glycaemic control, which was worse in those with diabetic retinopathy compared with those without (76.3% vs. 49.3%; P < 0.001). Blood pressure control was similar for those with and without diabetic retinopathy, with almost a third (28.5%) of the total sample having poor blood pressure control. Overall, those with diabetic retinopathy had poorer diabetes control than those without (24.3% vs. 13.7%; P = 0.002). CONCLUSIONS: Our findings substantiate the implementation of the Diabetes Management Project, developed to assess factors associated with suboptimal diabetes care.

The relationship between visual function, duration and main causes of vision loss and falls in older people with low vision.

BACKGROUND: Falls are an alarming health problem and a major cause of injury among the elderly. The healthcare cost associated with falls is considerable. Visual acuity has been found to be an independent risk factor for falls; however, the results are not unanimous. Moreover, other aspects of visual function such as visual field, contrast sensitivity and depth perception have not been adequately investigated in relation to falls. The aim of this study, therefore, was to determine the relationship between visual function, duration, and main causes of visual impairment, and falls in individuals with low vision. METHODS: This was a cross-sectional study involving participants attending a public tertiary eye care hospital. Participants were mobile, aged 60 years or above, and had low vision (visual acuity >0.3 LogMAR in the better eye). Details about falls in the previous 12 months and other information were collected, and patients completed a questionnaire about activities of daily living. The duration and main causes of visual impairment, visual acuity, contrast sensitivity, depth perception, and visual field were assessed. Descriptive statistical analyses were performed to characterize the participants' sociodemographic and clinical data. RESULTS: One hundred and twenty seven patients (53%; 67 males) with a mean age of 76.3+/-8.3 years were recruited. Thirty seven percent of the participants (n=47) had mild, 50% (n=64) moderate and 13% (n=16) severe visual impairment (>0.3-0.5; >0.5-1.0; and >1.0 LogMAR respectively). The frequencies of single and multiple falls were 42.5% and 12.6% respectively. Visual acuity, contrast sensitivity, depth perception, visual field, main cause, and duration of visual impairment were not significantly associated with falls (p>0.05). In multiple regression analyses, physical inactivity remained the only variable independently associated with falls in all models except for visual field. Overall, visually impaired people were three times more likely to fall if they were physically inactive. CONCLUSIONS: Visual function, duration and main causes of visual impairment are not independently associated with falls in people with low vision. However, a significant relationship between non-participation in physical activity and falls was found. Further work is required to investigate the association between vision-related factors and falls in older people with visual impairment.

Effectiveness of an innovative and comprehensive eye care model for individuals in residential care facilities: results of the residential ocular care (ROC) multicentred randomised controlled trial.

BACKGROUND: To assess the clinical and patient-centred effectiveness of a novel residential ocular care (ROC) model in Australian individuals residing in residential care. METHODS: In this prospective, multicentred, randomised controlled trial conducted in 38 Australian aged-care facilities (2015-2017), 178 visually impaired individuals living in residential care facilities (mean age ±SD: 83.9±8.6 years; 65.7% women) were cluster randomised to ROC (n=95) or usual care (n=83) pathways. The ROC arm comprised a tailored and comprehensive within-site eye examination and care rehabilitation pathway, while usual care participants were given a referral to an external eyecare provider. Outcomes included presenting distance and near visual acuity (PNVA); Rasch-transformed Reading, Emotional and Mobility scores from the Impact of Vision Impairment questionnaire; quality of vision (QoV comprising Rasch-transformed Frequency, Severity and Bother domains) scores; Euroqol-5-Dimensions (raw scores); Cornell Scale for Depression (raw scores) and 6-month falls frequency, assessed at baseline and 6 months post intervention. Within-group and between-group comparisons were conducted using linear mixed models, adjusted for baseline differences in characteristics between the two arms. RESULTS: At 6 months, intention-to-treat analyses showed significant between-group improvements in ROC residents compared with usual care for PNVA, Emotional and QoV scores (all p<0.05) These significant findings were retained in per-protocol analyses. No other between-group changes were observed. CONCLUSION: Our ROC model was effective in improving near vision, emotional well-being and perceived burden of vision-related symptoms in residential care dwellers in Australia with vision impairment. Future studies to evaluate the cost effectiveness and implementation of ROC in Australia are warranted.

Detection and management of depression in patients with vision impairment.

PURPOSE: Depression is common in people with vision impairment and has a number of debilitating effects. However, it is often not identified and therefore is left untreated. This study aimed to explore eye healthcare professionals' views of depression in patients with vision impairment and identify current management practices and barriers to effective care. METHODS: Six focus groups and two semistructured interviews were conducted with 26 staff members from a large tertiary eye care hospital. Participants included orthoptists, ophthalmic nurses, and support staff. The data were analyzed using an inductive analytical approach based on the constant comparative method. RESULTS: Participants reported relying mainly on observational cues of patients' behavior or using other indirect methods to identify depression. On the basis of these observations, they acknowledged that the prevalence of depression in visually impaired patients at the hospital was high and believed it impacts negatively on patients' practical and emotional functioning. Few reported overtly discussing depression with patients. Responses to suspected depression varied according to individual staff knowledge of resources or referral options. Various barriers to adequate management of depression were identified, including confusion over roles and responsibilities, and unclear communication pathways between staff. Participants were enthusiastic about resolving these obstacles and establishing clear pathways to care both within the hospital and in the wider community. They were also receptive to receiving training and education about depression, with specific reference to the visually impaired population. CONCLUSIONS: There is considerable scope and enthusiasm for improving depression management in this tertiary eye care facility. The results may not, however, be generalizable to all ophthalmic settings. New initiatives need to be tailored to suit implementation within such ophthalmic services.

What is the best measure for assessing diabetes distress? A comparison of the Problem Areas in Diabetes and Diabetes Distress Scale: results from Diabetes MILES-Australia.

This study used Rasch analysis to examine the psychometric validity of the Diabetes Distress Scale and the Problem Areas in Diabetes scale to assess diabetes distress in 3338 adults with diabetes (1609 completed the Problem Areas in Diabetes scale ( n = 675 type 1 diabetes; n = 934 type 2 diabetes) and 1705 completed the Diabetes Distress Scale ( n = 693 type 1 diabetes; n = 1012 type 2 diabetes)). While criterion and convergent validity were good, Rasch analysis revealed suboptimal precision and targeting, and item misfit. Unresolvable multidimensionality within the Diabetes Distress Scale suggests a total score should be avoided, while suboptimal precision suggests that the Physician-related and Interpersonal distress subscales should be used cautiously.

Inter-relationship between visual symptoms, activity limitation and psychological functioning in patients with diabetic retinopathy.

AIMS: We explored the direct and indirect impact of restrictions in daily living activities on the relationship between perceived visual symptoms associated with diabetic retinopathy (DR) and psychological functioning. METHODS: In this prospective, cross-sectional study, 514 tertiary patients with DR (mean age±SD, 60.4±12.6 years; 64% male) answered questions related to nine domains of DR-specific quality of life. These were classified into the following predictor, mediating and outcome variables: visual symptoms (predictor variable); activity limitation, driving, lighting, social restriction, inconvenience, mobility (mediating variables); and emotional distress and concerns (outcome variables). Direct and indirect relationships between study variables were assessed using path analysis, using interval-level person measures derived from Rasch analyses of the study questionnaires. RESULTS: We found no direct effect of DR-related visual symptoms on emotional distress or concerns. Rather, the association between visual symptoms and emotional distress was mediated (all p<0.05) by mobility (indirect effect=0.07), inconvenience (indirect effect=0.28), activity limitation (indirect effect=0.13) and social restriction (indirect effect=0.11). Similarly, the relationship between DR-related visual symptoms and concerns was mediated by inconvenience (indirect effect=0.36) and social restriction (indirect effect=0.11). Lighting and driving did not have a mediating role. CONCLUSIONS: The link between vision and psychological functioning outcomes such as emotional distress and concern is complex in patients with DR and mediated by limitations in daily living activities and social factors. Interventions to enhance daily functioning and social interaction may be effective in reducing emotional distress associated with DR-related vision impairment.

Improving eye care in residential aged care facilities using the Residential Ocular Care (ROC) model: study protocol for a multicentered, prospective, customized, and cluster randomized controlled trial in Australia.

BACKGROUND: Older adults in residential aged care facilities have unnecessarily high levels of vision impairment (VI) which are largely treatable or correctable. However, no current comprehensive eye health service model exists in this setting in Australia. We aimed to determine the clinical, person-centered, and economic effectiveness of a novel eye care model, the Residential Ocular Care (ROC). METHODS/DESIGN: This protocol describes a multicentered, prospective, randomized controlled trial. A total of 395 participants with distance vision < 6/12 (0.30 LogMAR) and/or near vision N8 (1.00 M) or worse will be recruited from 38 urban and rural aged care facilities across Victoria, Australia. Aged care facilities will be randomized (1:1) to one of two parallel groups. Participants in the ROC group will receive a comprehensive and tailored eye care pathway that includes, as necessary, refraction and spectacle provision, cataract surgery, low vision rehabilitation, and/or a referral to an ophthalmologist for funded treatment. Usual care participants will be referred for an evaluation to the eye care service associated with the facility or an eye care provider of their choice. The primary outcome will be presenting near and distance vision assessed at the two- and six-month follow-up visits, post baseline. Secondary outcomes will include vision-specific quality of life, mobility, falls, depression, and eye care utilization at two and six months. An incremental cost-effectiveness analysis will also be undertaken. DISCUSSION: The ROC study is the first multicentered, prospective, customized, and cluster randomized controlled trial in Australia to determine the effectiveness of a comprehensive and tailored eye care model for people residing in aged care facilities. Results from this trial will assist health and social care planners in implementing similar innovative models of care for this growing segment of the population in Australia and elsewhere. TRIAL REGISTRATION: Australian and New Zealand Clinical Trials Registry, ACTRN12615000587505 . Registered on 4 June 2015 - retrospectively registered.

The impact of vision impairment questionnaire: an assessment of its domain structure using confirmatory factor analysis and rasch analysis.

PURPOSE: To assess and validate the subscale structure of the 28-item Impact of Visual Impairment (IVI) Scale by using confirmatory factor analysis (CFA) and Rasch analysis for use as an outcome measure. METHODS: Three hundred nineteen participants completed the IVI questionnaire, and the responses then were subjected to Rasch analysis by RUMM2020 software. With the person estimates for each item, CFA was used to assess two hypothesized structures: three-and four-factor models. The subscales of the model with the best fit were then further validated by Rasch analysis. RESULTS: CFA supported a three-factor model that included items from the emotional well-being, reading and accessing information, and mobility and independence subscales. Almost all the selected goodness-of-fit statistics for the three-factor model were better than the recommended values. The factor loadings of the items on their respective domains were all statistically significant (P < 0.001) and ranged between 0.54 and 0.81. The three subscales individually fitted the Rasch model according to the item-trait interaction test (mobility and independence chi(2) [df] = 45.9 [44], P = 0.39; emotional well-being = 28.4 [32], P = 0.65; and reading and accessing information = 43.5 [36], P = 0.18). The item-fit residuals values of the three subscales were <2.5 and showed mean and standard deviations approximating 0 and 1, respectively. The internal consistency reliability of the subscales (alpha) was substantial, ranging between 0.89 and 0.91. CONCLUSIONS: An examination of the IVI dimension confirmed a three-subscale structure that displays interval measurement characteristics likely to provide a valid and reliable assessment of restriction of participation. The findings provide an opportunity for a more detailed measurement of the effects of different types of low-vision rehabilitation programs.

The effectiveness of low-vision rehabilitation on participation in daily living and quality of life.

PURPOSE: To evaluate the effectiveness of a multidisciplinary low-vision rehabilitation program on quality of life evaluated by the Impact of Vision Impairment (IVI) instrument. METHODS: First-time referrals to low-vision clinics were assessed before and after rehabilitation (3-6 months). Rasch analysis was used to estimate the three IVI subscale and overall values on an interval scale. A mixed between-within subjects ANOVA was used to identify whether presenting visual acuity had an interaction effect with rehabilitation change. Cohen d values were used to estimate the magnitude of the change and the standardized response mean (SRM) procedure was selected to determine the clinical significance of the rehabilitation-induced changes. RESULTS: One hundred twenty-four women and 68 men (mean age, 80.3 years) completed the rehabilitation. Most had age-related macular degeneration (62%, 119) and were moderately to severely vision impaired (<6/18; 78%, 149). After rehabilitation, significant improvements were recorded for the overall IVI score (P = 0.006) and two subscales: reading and accessing information and emotional well-being (P = 0.007 and 0.009, respectively). No significant improvement was found on the mobility and independence subscale (P = 0.07). The magnitude of the post-intervention improvement was found to be relatively moderate (Cohen d = 0.17-0.30) and clinically modest (SRM = 0.22-0.42). CONCLUSIONS: Significant improvements in overall quality of life and two specific areas of daily living in people with low vision were found, although the magnitude and clinical significance of the rehabilitation-induced gains were modest. Further investigation in other models of low-vision rehabilitation is needed to optimize quality of life gains in people with low vision.

Diabetic Retinopathy and Macular Edema Quality-of-Life Item Banks: Development and Initial Evaluation Using Computerized Adaptive Testing.

Purpose: The purpose of this study was to assess the psychometric properties of diabetic retinopathy (DR) and diabetic macular edema (DME) quality-of-life (QoL) item banks and determine the utility of the final calibrated item banks by simulating a computerized adaptive testing (CAT) application. Methods: In this clinical, cross-sectional study, 514 participants with DR/DME (mean age ± SD, 60.4 ± 12.6 years; 64% male) answered 314 items grouped under nine QoL item pools: Visual Symptoms (SY); Ocular Comfort Symptoms (OS); Activity Limitation (AL); Mobility (MB); Emotional (EM); Health Concerns (HC); Social (SC); Convenience (CV); and Economic (EC). The psychometric properties of the item pools were assessed using Rasch analysis, and CAT simulations determined the average number of items administered at high and moderate precision levels. Results: The SY, MB, EM, and HC item pools required minor amendments, mainly involving removal of six poorly worded, highly misfitting items. AL and CV required substantial modification to resolve multidimensionality, which resulted in two new item banks: Driving (DV) and Lighting (LT). Due to unresolvable psychometric issues, the OS, SC, and EC item pools were not pursued further. This iterative process resulted in eight operational item banks that underwent CAT simulations. Correlations between CAT and the full item banks were high (range, 0.88-0.99). On average, only 3.6 and 7.2 items were required to gain measurement at moderate and high precision, respectively. Conclusions: Our eight psychometrically robust and efficient DR/DME item banks will enable researchers and clinicians to accurately assess the impact and effectiveness of treatment therapies for DR/DME in all areas of QoL.

Combined poor diabetes control indicators are associated with higher risks of diabetic retinopathy and macular edema than poor glycemic control alone.

PURPOSE: To examine the association of individual and combined indicators of diabetes control with diabetic retinopathy and diabetic macular edema. MATERIALS AND METHODS: In this clinical, cross-sectional study, 613 adults with type 2 diabetes (372 any diabetic retinopathy; 183 any diabetic macular edema) were examined. Diabetic retinopathy was assessed from fundus photographs; diabetic macular edema from Ocular Coherence Tomography scans; and HbA1c and serum lipid values from fasting blood samples. Poor glucose control was defined as HbA1c≥7%; poor blood pressure control as SBP≥130/DBP≥80; and poor lipid control as total cholesterol:HDL ratio≥4.0. The association of poor glucose control, poor blood pressure control and poor lipid control alone and in combination (poor glucose & blood pressure control; poor glucose & lipid control; poor blood pressure & lipid control; and poor glucose, blood pressure & lipid control) with diabetic retinopathy/diabetic macular edema was examined using multiple logistic regression models. RESULTS: Patients' mean±standard deviation age was 64.9±11.6 years (57% male). In adjusted models, compared to those with good control of all indicators (n = 99, 18.3%), the odds ratio (95% Confidence Interval) of having any diabetic retinopathy was 2.44 (1.34-4.46), 3.75 (1.75-8.07), 4.64 (2.13-10.12) and 2.28 (1.01-5.16) for poor glucose control only; poor glucose & blood pressure control; poor glucose & lipid control; and poor glucose, blood pressure & lipid control, respectively. Correspondingly for diabetic macular edema, they were 3.19 (1.55-6.59); 3.60 (1.58-8.22); 2.76 (1.18-6.44); and 3.01 (1.18-7.67), respectively. Odds were not significantly increased for other indicators. DISCUSSION: Compared to individual indicators of poor diabetes control, risk of diabetic retinopathy and diabetic macular edema increased three to fourfold with a combination of these indicators. Targeting combined diabetes control indicators is important to reduce risk of diabetic retinopathy/diabetic macular edema.

Factors associated with knowledge of diabetes in patients with type 2 diabetes using the Diabetes Knowledge Test validated with Rasch analysis.

OBJECTIVE: In patients with Type 2 diabetes, to determine the factors associated with diabetes knowledge, derived from Rasch analysis, and compare results with a traditional raw scoring method. RESEARCH DESIGN & METHODS: Participants in this cross-sectional study underwent a comprehensive clinical and biochemical assessment. Diabetes knowledge (main outcome) was assessed using the Diabetes Knowledge Test (DKT) which was psychometrically validated using Rasch analysis. The relationship between diabetes knowledge and risk factors identified during univariate analyses was examined using multivariable linear regression. The results using raw and Rasch-transformed methods were descriptively compared. RESULTS: 181 patients (mean age±standard deviation = 66.97±9.17 years; 113 (62%) male) were included. Using Rasch-derived DKT scores, those with greater education (ß = 1.14; CI: 0.25,2.04, p = 0.013); had seen an ophthalmologist (ß = 1.65; CI: 0.63,2.66, p = 0.002), and spoke English at home (ß = 1.37; CI: 0.43,2.31, p = 0.005) had significantly better diabetes knowledge than those with less education, had not seen an ophthalmologist and spoke a language other than English, respectively. Patients who were members of the National Diabetes Service Scheme (NDSS) and had seen a diabetes educator also had better diabetes knowledge than their counterparts. Higher HbA1c level was independently associated with worse diabetes knowledge. Using raw measures, access to an ophthalmologist and NDSS membership were not independently associated with diabetes knowledge. CONCLUSIONS: Sociodemographic, clinical and service use factors were independently associated with diabetes knowledge based on both raw scores and Rasch-derived scores, which supports the implementation of targeted interventions to improve patients' knowledge. Choice of psychometric analytical method can affect study outcomes and should be considered during intervention development.