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The quantification of vision impairments dates to the mid-nineteenth century with standardization of visual acuity and visual field measures in the eye clinic. Attempts to quantify the impact of vision impairments on patients’ lives did not receive clinical attention until the close of the twentieth century. Although formal psychometric theories and measurement instruments were well developed and commonplace in educational testing, as well as in various areas in psychology and rehabilitation medicine, the late start applying them to clinical vision research created a vacuum that invited poorly developed and poorly functioning instruments and analytic methods. Although this research is still burdened with legacy instruments, mandates by regulatory agencies to include the patients’ perspectives and preferences in the evaluation of clinical outcomes have stimulated the development and validation of self-report instruments grounded in modern psychometric theory and methods. Here I review the progress and accomplishments of applying modern psychometrics to clinical vision research.

Vision rehabilitation aims to improve daily functioning in patients with chronic disabling vision impairments – low vision – by providing vision assistive equipment and teaching patients effective use of the equipment; teaching patients adaptations to obviate dependence on vision; modifications of the patient’s environment to improve visibility and increase safety; and psychosocial counseling and education to help patients cope with the stress of impaired vision. The interventions that constitute vision rehabilitation are tailored to each patient’s functional goals and personal preferences. This chapter describes the theory, structure, and mechanics of an adaptive patient-reported outcome measure – the Activity Inventory (AI). The AI was developed to identify each patient’s unique set of functional goals within a hierarchical framework, to specify the cognitive and motor activities (i.e., tasks in different functional domains) the patient customarily performs to achieve his or her personal goals, and to elicit ordinal patient ratings of the importance and difficulty of each goal and the difficulty of relevant subsidiary tasks under goals that meet or exceed defined importance and difficulty criteria. The theoretical assumptions of a Rasch psychometric model that is employed to estimate measures of the patient’s overall visual ability from goal difficulty ratings and ability in each functional domain from task difficulty ratings before and after vision rehabilitation are presented and the results for a large group of low vision patients are reviewed. This chapter then explores the issue of how individual patient preferences must be factored into the outcome measures to determine the utility of functional improvements from vision rehabilitation. A theoretical framework for incorporating the utility of individual vision rehabilitation outcomes is offered and its application to functional outcome data is demonstrated.

SIGNIFICANCE To provide meaningful competition that is equitable for Paralympic athletes, classification systems are vital to determine which athletes are eligible to compete in adapted forms of sports and to group athletes for competition. Our discussion has important implications to inform how we should approach visual function assessment in sports performance. Sport participation positively benefits individuals with low vision. In particular, adapted sports exist to provide people with visual disabilities an avenue for participating in recreational activity. High-performance low-vision athletes can participate in Paralympic sports but need to be properly classified based on the severity of their vision impairment. The model for Paralympic classification was initiated by Sir Ludwig Guttmann in 1952 in a rehabilitation clinic for soldiers with spinal cord injuries. Today, the International Paralympic Committee mandates that international sports federations develop evidence-based sport-specific classification systems to ensure that eligible disabled athletes have an opportunity for meaningful competition. With the current classification system, only visual acuity and visual field measures are considered to determine an athlete's eligibility to compete, leaving room to expand our understanding of visual function requirements for individual sports. In this topical review, we discuss the origins of Paralympic sports, limitations of current classification methods, and requirements toward achieving evidence-based sport-specific evaluation systems.

SIGNIFICANCE Outpatient vision rehabilitation improves function in veterans with vision impairment, but the prevalence of cognitive impairment and the degree to which it may affect rehabilitation outcomes in the Veterans Affairs system are unknown. PURPOSE The purpose of this study was to determine the prevalence of cognitive impairment among veterans receiving outpatient vision rehabilitation in the Veterans Affairs system and compare the benefits of rehabilitation in veterans with and without cognitive impairment. METHODS We conducted cognitive assessments and a nested longitudinal cohort study in veterans with eye disorders at two outpatient rehabilitation sites. Cognition was assessed with the Modified Telephone Interview for Cognitive Status administered in person. Eligible veterans and their companions in the longitudinal study responded to questions about the veteran's function at baseline and 90 days later. Visual function was measured with the 48-item Low Vision Visual Function Questionnaire (LV-VFQ-48) and items from the Activity Inventory. RESULTS Of 291 veterans assessed (mean ± standard deviation age, 78.2 ± 12 years), 136 (46.7%) were cognitively intact (Modified Telephone Interview for Cognitive Status scores, ≥33), whereas 58 (19.9%) had borderline scores of 30 to 32, 82 (28.2%) had scores suggesting mild/moderate cognitive impairment (scores of 20 to 29), and 15 (5.2%) had scores suggesting severe cognitive impairment (score of

Purpose To provide calibrated item measures and rating category thresholds for the Activity Inventory (AI), an adaptive visual function questionnaire, from difficulty ratings obtained from a large sample of new low vision patients at pre-rehabilitation baseline. Methods Baseline AI (510 items) rating scale data from five previous low vision rehabilitation outcome studies (n = 3623) were combined, and the method of successive dichotomizations was used to estimate calibrated item measures and rating category thresholds. Infit statistics were analyzed to evaluate the fit of the data to the model. Factor analysis was applied to person measures estimated from different subsets of items (e.g., functional domains such as reading, mobility) to evaluate differential person functioning. Results Estimated item measures were well targeted to the low vision patient population. The distribution of infit statistics confirmed the validity of the estimated measures and the two-factor structure previously observed for the AI. Conclusions Our calibrated item measures and rating category thresholds enable researchers to estimate changes in visual ability from low vision rehabilitation on the same scale, facilitating comparisons between studies. Translational Relevance The work described in this paper provides calibrated item measures and rating category thresholds for a visual function questionnaire to measure patient-centered outcomes in low vision clinical research. The calibrated AI also can be used as a patient outcome measure and quality assurance tool in clinical practice.

Background Existing patient-reported outcome (PRO) measures may not be relevant to the full range of functional and vision-related quality of life (VR-QOL) concerns of individuals with vision impairment due to severe peripheral field loss (PFL). Measurement of VR-QOL in severe PFL is important in order to determine the effectiveness of vision rehabilitation interventions for this population. The purpose of this study was to characterize the impact of severe PFL due to retinitis pigmentosa (RP) and glaucoma on VR-QOL as the initial phase in the development of a novel PRO measure. Methods Individuals with severe PFL due to RP or glaucoma were recruited from the Kellogg Eye Center and the Association for the Blind and Visually Impaired. Participants completed semi-structured qualitative interviews, the Impact of Vision Impairment (IVI) questionnaire and the RAND 36-Item Health Survey. Interviews were analyzed by two coders using thematic analysis. A matrix analysis was conducted to compare VR-QOL by cause of severe PFL. Sample size was determined by thematic saturation. Results The study included 37 participants (19 RP, 18 glaucoma). Median best-corrected visual acuity for those with RP and glaucoma was 20/40 and 20/27.5, while Pelli-Robson contrast sensitivity was 1.2 log contrast sensitivity (logCS) and 1.1 logCS, respectively. Median domain scores on the IVI (reading, mobility, well-being) ranged from a low of − 0.2 to a high of 0.7 logits in those with RP and from 0.5 to 1.2 logits in those with glaucoma. Qualitative interviews identified six VR-QOL themes relevant across participants with both RP and glaucoma, including activity limitations, driving, emotional well-being, reading, mobility, and social function. VR-QOL concerns were largely consistent among those with severe PFL due to RP and glaucoma. These overarching themes contained content relevant to specific challenges related to severe PFL. Conclusions There are commonly occurring VR-QOL concerns among individuals with severe PFL due to RP and glaucoma. The outlined themes will serve as the basis for development of the Low Vision Severely Constricted Peripheral Eyesight (LV-SCOPE) Questionnaire.

To improve the usefulness of the National Eye Institute Visual Function Questionnaire-25 (NEI VFQ-25) by enabling estimation of measures on an invariant scale and comparisons between patients and across studies.Datasets of baseline NEI VFQ-25 responses from nine studies (seven retina randomized trials, n = 2770; two low vision studies, n = 572) were combined. The method of successive dichotomizations was applied to patient ratings of the main NEI VFQ-25 and six supplemental items to estimate Rasch model parameters using the R package 'msd.' Calibrated item measures and rating category thresholds were estimated for the NEI VFQ-25, as well as for two domain-specific versions: the NEI VFQ-VF that includes only visual function items and the NEI VFQ-SE that includes only socioemotional items.Calibrated item measures were estimated from study participants (n = 3342) ranging in age from 19 to 103 years, with mean (SD) age of 69.3 (11) years and a mean logMAR visual acuity of 0.30 (Snellen 20/40). Item measure estimates had high precision (standard error range, 0.026-0.085 logit), but person measure estimates had lower precision (standard error range, 0.108-0.499 logit). Items were well targeted to most persons, but not to those with higher levels of function.Calibrated item measures and rating category thresholds enable researchers and clinicians to estimate visual, socioemotional, and combined measures on an invariant scale using the NEI VFQ-25.Applying NEI VFQ 25C calibrated item measures (software provided) to the NEI VFQ-25, users can estimate overall, visual, and socioemotional function measures for individual patients.

PURPOSE: To understand the source of between-person variance in baseline health utilities estimated from EuroQol 5-dimension questionnaire (EQ-5D) responses of a representative sample of the US low vision outpatient population prior to rehabilitation. METHODS: A prospective, observational study of 779 new low vision patients at 28 clinic centers in the US. The EQ-5D, Activity Inventory (AI), Telephone Interview for Cognitive Status (TICS), Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) physical functioning component, and Geriatric Depression Scale (GDS) were administered by telephone interview prior to rehabilitation. EQ-5D responses were transformed into health utilities, which served as the dependent variable in all analyses. Data were then analyzed to determine how much overall visual ability, functional domains of visual ability, and comorbidities (e.g. physical functioning, depression, cognition) independently contribute to the EQ-5D-based health utility index. RESULTS: Multivariable regression analyses showed that the GDS and SF-36 physical account for nearly 40% of the variance observed in health utilities estimated from EQ-5D responses of low vision patients. Age was also a significant predictor of health utilities, but accounted for very little variance. None of the other variables were significant predictors. CONCLUSIONS: Health utilities of low vision patients estimated from the EQ-5D primarily are associated with comorbid factors that are not likely to be responsive to low vision rehabilitation, thereby rendering the EQ-5D an unsuitable outcome measure for this population. However, because the EQ-5D is responsive to comorbid states, it could be a useful tool for evaluating the impact of comorbidities on low vision patient quality of life.

SIGNIFICANCE One-year follow-up is recommended for patients with macular diseases to assess functional changes associated with disease progression and to modify low-vision (LV) treatment plans, if indicated. PURPOSE The purpose of this study was to observe 255 patients with macular diseases who received LV rehabilitation (rehabilitation with a therapist) or basic LV services (LV devices dispensed without therapy) during Veterans Affairs Low-vision Intervention Trial II after the trial ended at 4 months until 1-year follow-up. METHODS The primary outcome measure was visual ability measured with the 48-item Veterans Affairs Low-vision Visual Functioning Questionnaire. Mean visual ability scores for the treatment groups were compared from baseline to 4 months, 4 months to 1 year, and baseline to 1 year. Changes from baseline to 1 year were compared between the two groups. Predictors of changes in visual ability from 4 months to 1 year were assessed using linear regression. RESULTS Both groups experienced significant improvement in all measures of visual ability from baseline to 1 year but lost visual reading ability during the observation period (LV rehabilitation group, -0.64 [1.2] logit; 95% confidence interval [CI], -0.84 to -0.44 logit; basic LV group, -0.63 [1.4] logit; 95% CI, -0.88 to -0.38 logit), and overall visual ability was lost in the LV rehabilitation group (-0.20 [0.8] logit; 95% CI, -0.34 to -0.06 logit). Loss of visual reading ability in both groups from 4 months to 1 year was predicted by reading ability scores at 4 months, loss of near visual acuity from 4 months to 1 year, and lower EuroQol-5D utility index scores; loss of overall visual ability in the LV rehabilitation group during the same time period was predicted by lower overall ability scores at 4 months. CONCLUSIONS Visual ability significantly improved in all groups from baseline to 1 year. However, the loss of visual reading ability experienced by both groups from 4 months to 1 year reduced the benefit of the services provided.

Signal Detection Theory is the standard method used in psychophysics to estimate person ability in m-alternative forced choice tasks where stimuli are typically generated with known physical properties (e.g., size, frequency, contrast, etc …) and lie at known locations on a physical measurement axis. In contrast, variants of Item Response Theory are preferred in fields such as medical research and educational testing where the axis locations of items on questionnaires or multiple choice tests are not defined by any observable physical property and are instead defined by a latent (or unobservable) variable. We provide an extension of Signal Detection Theory to latent variables that employs the same strategy used in Item Response Theory and demonstrate the practical utility of our method by applying it to a set of clinically relevant face perception tasks with visually impaired individuals as subjects. A key advantage of our approach is that Signal Detection Theory explicitly models the m-alternative forced choice task while Item Response Theory does not. We show that Item Response Theory is inconsistent with key assumptions of the m-alternative forced choice task and is not a valid model for this paradigm. However, the simplest Item Response Theory model-the dichotomous Rasch model-is found to be a special case of SDT and provides a good approximation as long as the number of response alternatives m is small and remains fixed for all items.

SIGNIFICANCE This study explores whether eccentric viewing training (EVT) changes the properties of the retinal area used for fixation in subjects with bilateral macular disease. The data presented demonstrate the feasibility of conducting a randomized controlled trial on EVT. PURPOSE Patients with bilateral central scotomas adopt other retinal area(s) called preferred retinal locus to substitute the blind fovea. EVT is offered with the goal to improve functional vision by learning how to identify and use a more useful retinal area for fixation-a trained retinal locus-and/or to improve fixation stability with their existing preferred retinal locus. An observational study was conducted to determine whether patients change and adopt a new trained retinal locus location and/or if fixation stability improves after EVT. METHODS Seventy-six patients with bilateral central scotomas received EVT from an experienced rehabilitation therapist. Retinal locations for repeated fixations and sizes of central scotomas of the better eye were recorded before and after EVT with a scanning laser ophthalmoscope. The position and area of the 95% confidence bivariate ellipse that defines the retinal area in which 95% of fixations occur were analyzed. RESULTS We observed no significant difference between the size of the area of the fitted ellipses before (mean [SD], 26.4° [19.7°]) and after (mean [SD], 24.8° [20.9°]) EVT (P = .54). However, we observed a shift in the preferred retinal locus location after EVT (P < .0001). The mean (SD) shift in the position of the center of fixation after EVT was 7.5° (5.2°; range, 0.45 to 23°). This mean difference was larger than would be expected from average within-subject fixation stability. CONCLUSIONS The location of the retinal area used for fixation changes after EVT. Fixation stability does not change after EVT. These preliminary data are yet to be confirmed with the use of a control group.

Purpose Provide item calibrations estimated for the Impact of Vision Impairment (IVI) questionnaire by pooling data from several studies of people with vision impairment (VI) representing a variety of countries and causes of VI. Methods Eight data sets from six principal investigators representing responses to IVI items from 2867 VI patients were pooled for analysis. Eligible patients were 18 years or older and from Australia, India, and the United States. Rasch analysis, using the Andrich Rating Scale Model (Winsteps version 3.65), was performed on preintervention IVI responses to estimate item and person measures, reliability coefficients, and response category thresholds. Differential item functioning (DIF) analysis and analysis of variance (ANOVA) were used to examine the effects different data sets and covariates on item estimates. Results Patient age range was 18 to 103 years (median 62 years); 55% were male. Visual acuity ranged from 20/20 to no light perception and primary diagnosis was macular degeneration in 29% of patients. Item measure estimates showed good separation reliability (R2 = 0.99). DIF magnitude did not preclude use of all IVI-28 data. ANOVA showed VA (P < 0.001) and gender (P < 0.002) were predictors of visual ability. Conclusions Analysis from pooled data support the provision of calibrated IVI item measures for researchers and clinicians to use, thus better enabling direct comparisons of patients with VI. Translational Relevance Validity testing of the IVI show that we can combine disparate data sets of patient responses to calibrate item measures and response category thresholds, and provide to others for use in comparing patients across clinical trials and on an individual basis.

SIGNIFICANCE Head-mounted video display systems and image processing as a means of enhancing low vision are ideas that have been around for more than 20 years. Recent developments in virtual and augmented reality technology and software have opened up new research opportunities that will lead to benefits for low vision patients. Since the Visionics low vision enhancement system (LVES), the first head-mounted video display LVES, was engineered 20 years ago, various other devices have come and gone with a recent resurgence of the technology over the past few years. In this article, we discuss the history of the development of LVESs, describe the current state of available technology by outlining existing systems, and explore future innovation and research in this area. Although LVESs have now been around for more than two decades, there is still much that remains to be explored. With the growing popularity and availability of virtual reality and augmented reality technologies, we can now integrate these methods within low vision rehabilitation to conduct more research on customized contrast-enhancement strategies, image motion compensation, image-remapping strategies, and binocular disparity, all while incorporating eye-tracking capabilities. Future research should use this available technology and knowledge to learn more about the visual system in the low vision patient and extract this new information to create prescribable vision enhancement solutions for the visually impaired individual.

Importance Examining costs and consequences of different low-vision (LV) programs provides important information about resources needed to expand treatment options efficiently. Objective To examine the costs and consequences of LV rehabilitation or basic LV services. Design, Setting, and Participants The US Department of Veterans Affairs (VA) Low Vision Intervention Trial (LOVIT) II was conducted from September 27, 2010, to July 31, 2014, at 9 VA facilities and included 323 veterans with macular diseases and a best-corrected distance visual acuity of 20/50 to 20/200. Veterans were randomized to receive basic LV services that provided LV devices without therapy, or LV rehabilitation that added a therapist to LV services who provided instruction and homework on using LV devices, eccentric viewing, and environmental modification. We compared costs and consequences between these groups. Interventions Low-vision devices without therapy and LV devices with therapy. Main Outcomes and Measures Costs of providing basic LV services or LV rehabilitation were assessed. We measured consequences as changes in functional visual ability from baseline to follow-up 4 months after randomization using the VA Low Vision Visual Functioning Questionnaire. Visual ability was measured in dimensionless log odds units (logits). Results Of 323 randomized patients, the mean (SD) age was 80 (10.5) years, 314 (97.2%) were men, and 292 (90.4%) were white. One hundred sixty (49.5%) received basic LV services and 163 (50.1%) received LV rehabilitation. The mean (SD) total direct health care costs per patient were similar between patients who were randomized to receive basic LV services ($1662 [$671]) or LV rehabilitation ($1788 [$864]) (basic LV services, $126 lower; 95% CI, $299 lower to $35 higher; P = .15). However, basic LV services required less time and had lower transportation costs. Patients receiving LV rehabilitation had greater improvements in overall visual ability, reading ability, visual information processing, and visual motor skill scores.

Purpose To investigate the value of 3 novel autoantibodies [salivary protein 1 (SP1), carbonic anhydrase 6 (CA6), and parotid secretory protein (PSP)] in differentiating Sjogren's syndrome (SS)-related dry eye from non-SS dry eye. Methods Forty-six dry eye patients with SS (SS dry eye), 14 dry eye patients without SS (non-SS dry eye), and 25 controls were included. The 2012 American College of Rheumatology classification criteria were used for the diagnosis of SS. After a detailed review of systems, the Ocular Surface Disease Index questionnaire, Schirmer test without anesthesia, tear film breakup time, and ocular surface staining were performed to assess dry eye. All participants underwent serological testing using a commercially available finger prick kit. Results Thirty-seven patients with SS (80.4%) had a positive traditional autoantibody and 28 (60.9%) had a positive novel autoantibody. Traditional autoantibodies were absent in all non-SS dry eye patients and controls. Novel autoantibodies were present in 7/14 (50%) non-SS dry eye patients and 4/25 (16%) controls. Among 3 novel autoantibodies, anti-CA6 was significantly more prevalent in the SS and non-SS dry eye groups than in controls (52.2% vs. 42.9% vs. 8.0%, P = 0.001). Dry eye patients with positive anti-CA6 alone were significantly younger than patients with only traditional autoantibodies. Anti-CA6 was associated with worse dry eye signs and symptoms. Conclusions Anti-CA6 was the most prevalent novel autoantibody in patients with dry eye, and was associated with younger age and more severe disease. Longitudinal studies are needed to determine whether anti-CA6 is a marker for early SS or perhaps another form of an autoimmune dry eye disease.

The most commonly used models for estimating measures of latent variables from polytomous rating scale data are the Andrich rating scale model and the Samejima graded response model. The Andrich model has the undesirable property of estimating disordered rating category thresholds, and users of the model are advised to manipulate data to force thresholds to come out ordered. The Samejima model estimates ordered thresholds, but has the undesirable property of estimating person measures on a non-invariant scale-the scale depends on which items a person rates and makes comparisons across people difficult. We derive the rating scale model logically implied by the generally agreed upon definition of rating scale-a real line partitioned by ordered thresholds into ordered intervals called rating categories-and show that it estimates ordered thresholds as well as person and item measures on an invariant scale. The derived model turns out to be a special case of the Samejima model, but with no item discrimination parameter and with common thresholds across items. All parameters in our model are estimated using a fast and efficient method called the Method of Successive Dichotomizations, which applies the dichotomous Rasch model as many times as there are thresholds and demonstrates that the derived model is a polytomous Rasch model that estimates ordered thresholds. We tested both the Method of Successive Dichotomizations and the Andrich model against simulated rating scale data and found that the estimated parameters of our model were nearly perfectly correlated with the true values, while estimated thresholds of the Andrich model became negatively correlated with the true values as the number of rating categories increased. Our method also estimates parameters on a scale that remains invariant to the number of rating categories, in contrast to the Andrich model.

Objective To present a method of estimating and equating scales across functional assessment instruments that appropriately represents changes in a patient's functional ability and can be meaningfully mapped to changes in Medicare G-code severity modifiers. Design Previously published measures of patients' overall visual ability, estimated from low-vision patient responses to 7 different visual function rating scale questionnaires, are equated and mapped onto Medicare G-code severity modifiers. Setting Outpatient low-vision rehabilitation clinics. Participants The analyses presented in this article were performed on raw or summarized low-vision patient ratings of visual function questionnaire (VFQ) items obtained from previously published research studies. Interventions Previously published visual ability measures from Rasch analysis of low-vision patient ratings of items in different VFQs (National Eye Institute Visual Functioning Questionnaire, Index of Visual Functioning, Activities of Daily Vision Scale, Visual Activities Questionnaire) were equated with the Activity Inventory (AI) scale. The 39 items in the Self-Report Assessment of Functional Visual Performance (SRAFVP) and the 48 items in the Veterans Affairs Low Vision Visual Functioning Questionnaire (VA LV VFQ) were paired with similar items in the AI in order to equate the scales. Main Outcome Measures Tests using different observation methods and indicators cannot be directly compared on the same scale. All test results would have to be transformed to measures of the same functional ability variable on a common scale as described here, before a single measure could be estimated from the multiple measures. Results Bivariate regression analysis was performed to linearly transform the SRAFVP and VA LV VFQ item measures to the AI item measure scale. The nonlinear relationship between person measures of visual ability on a logit scale and item response raw scores was approximated with a logistic function, and the 2 regression coefficients were estimated for each of the 7 VFQs. These coefficients can be used with the logistic function to estimate functional ability on the same interval scale for each VFQ and for transforming raw VFQ responses to Medicare's G-code severity modifier categories. Conclusions The principle of using equated interval scales allows for comparison across measurement instruments of low-vision functional status and outcomes, but can be applied to any area of rehabilitation.

Purpose To compare the effects of uncorrected refractive error (URE) and nonrefractive visual impairment (VI) on performance and disability measures. Design Cross-sectional, population-based study. Participants A total of 2469 individuals with binocular presenting visual acuity (PVA) of ≥20/80 who participated in the first round of the Salisbury Eye Evaluation study. Methods The URE was defined as binocular PVA of ≤20/30, improving to >20/30 with subjective refraction. The VI was defined as post-refraction binocular best-corrected visual acuity (BCVA) of ≤20/30. The visual acuity decrement due to VI was calculated as the difference between BCVA and 20/30, whereas visual acuity due to URE was taken as the difference between PVA and BCVA. Multivariable regression analyses were used to assess the disability impact of (1) vision status (VI, URE, or normal vision) using the group with normal vision as reference and (2) a 1-line decrement in acuity due to VI or URE. Main Outcome Measures Objective measures of visual function were obtained from timed performance of mobility and near vision tasks, self-reported driving cessation, and self-reported visual difficulty measured by the Activities of Daily Vision (ADV) scale. The ADV responses were analyzed using Rasch analysis to determine visual ability. Results Compared with individuals with normal vision, subjects with VI (n = 191) had significantly poorer objective and subjective visual functioning in all metrics examined ( P P Conclusions Visual impairment is associated with greater disability than URE across a wide variety of functional measures, even in analyses adjusting for the severity of vision loss. Refractive and nonrefractive vision loss should be distinguished in studies evaluating visual disability and be understood to have differing consequences.

Updated estimates of the prevalence and incidence rates of low vision and blindness are needed to inform policy makers and develop plans to meet the future demands for low vision rehabilitation services.To provide updated estimates of the incidence and prevalence of low vision and blindness in the United States.Visual acuity measurements as a function of age from the 2007-2008 National Health and Nutrition Examination Survey, with representation of racial and ethnic groups, were used to estimate the prevalence and incidence of visual impairments. Data from 6016 survey participants, ranging in age from younger than 18 years to older than 45 years, were obtained to estimate prevalence rates for different age groups. Incidence and prevalence rates of low vision (best-corrected visual acuity [BCVA] in the better-seeing eye of20/40 and20/60) and blindness (BCVA of ≤20/200) in older adults were estimated from exponential models, fit to prevalence rates as a function of age (specified in 5-year age bins). The prevalence and annual incidence of low vision and blindness in the United States were estimated, using the 2010 US census data by age, from the rate models applied to the census projections for 2017, 2030, and 2050. Data were collected from November 1, 2007, to October 31, 2008. Data analysis took place from March 31, 2016, to March 19, 2017.Prevalence and incidence rates of low vision and blindness in the United States.Of the 6016 people in the study, 1714 (28.4%) were younger than 18 years of age, 2358 (39.1%) were 18 to 44 years of age, and 1944 (32.3%) were 45 years of age or older. There were 2888 male (48%) and 3128 female (52%) participants. The prevalence of low vision and blindness for older adults (≥45 years) in the United States in 2017 is estimated to be 3 894 406 persons (95% CI, 3 034 442-4 862 549 persons) with a BCVA less than 20/40, 1 483 703 persons (95% CI, 968 656-2 370 513 persons) with a BCVA less than 20/60, and 1 082 790 persons (95% CI, 637 771-1 741 864 persons) with a BCVA of 20/200 or less. The estimated 2017 annual incidence (projected from 2010 census data) of low vision and blindness among older adults (≥45 years) in the United States is 481 970 persons (95% CI, 375 541-601 787 persons) with a BCVA less than 20/40, 183 618 persons (95% CI, 119 878-293 367 persons) with a BCVA less than 20/60, and 134 002 persons (95% CI, 83 383-215 567 persons) with a BCVA of 20/200 or less. The total annual incidence for each BCVA criterion is 12.4% of the total prevalence.Low vision and blindness affect a substantial portion of the older population in the United States. Estimates of the prevalence and annual incidence of visual impairment assist policy planners in allocating and developing resources for this life-changing loss of function.

Purpose To compare the efficacy of behavior activation (BA) + low vision rehabilitation (LVR) with supportive therapy (ST) + LVR to prevent depressive disorders in patients with age-related macular degeneration (AMD). Design Single-masked, attention-controlled, randomized, clinical trial with outcome assessment at 4 months. Participants Patients with AMD and subsyndromal depressive symptoms attending retina practices (n = 188). Interventions Before randomization, all subjects had 2 outpatient LVR visits, and were then randomized to in-home BA+LVR or ST+LVR. Behavior activation is a structured behavioral treatment that aims to increase adaptive behaviors and achieve valued goals. Supportive therapy is a nondirective, psychological treatment that provides emotional support and controls for attention. Main Outcome Measures The Diagnostic and Statistical Manual IV defined depressive disorder based on the Patient Health Questionnaire-9 (primary outcome), Activities Inventory, National Eye Institute Vision Function Questionnaire–25 plus Supplement (NEI-VFQ), and NEI-VFQ quality of life (secondary outcomes). Results At 4 months, 11 BA+LVR subjects (12.6%) and 18 ST+LVR subjects (23.4%) developed a depressive disorder (relative risk [RR], 0.54; 95% CI, 0.27–1.06; P = 0.067). In planned adjusted analyses the RR was 0.51 (95% CI, 0.27–0.98; P = 0.04). A mediational analysis suggested that BA+LVR prevented depression to the extent that it enabled subjects to remain socially engaged. In addition, BA+LVR was associated with greater improvements in functional vision than ST+LVR, although there was no significant between-group difference. There was no significant change or between-group difference in quality of life. Conclusions An integrated mental health and low vision intervention halved the incidence of depressive disorders relative to standard outpatient LVR in patients with AMD. As the population ages, the number of persons with AMD and the adverse effects of comorbid depression will increase. Promoting interactions between ophthalmology, optometry, rehabilitation, psychiatry, and behavioral psychology may prevent depression in this population.

Perceived functional vision refers to the self-reported ability to perform vision-dependent activities, and is often an outcome in epidemiological studies of vision loss and clinical trials of ophthalmologic and rehabilitative treatments to improve vision and everyday functioning. Functional vision is distinct from visual function, which more properly refers to the physiologic activity and function of the eyes and the visual system (Colenbrander, 2005). In principle, functional vision ought to be closely tied to objective measures of visual function, but the correlation with visual acuity, for example, ranges from 0.5 to 0.68 (Massof & Fletcher, 2001; Revicki, Rentz, Harnam, Thomas, & Lanzetta, 2010). This range suggests that nonophthalmologic factors may contribute to the relationship. One of those factors may be the characteristic way patients perceive and report difficulty in their lives. Functional vision is assessed by asking patients to rate the difficulty they experience when performing various activities like reading newsprint or doing housework. Their responses reflect their perceived difficulty, the value they place on the activity, their mood, and their personality. Depressed mood is known to impair functional vision, perhaps through loss of interest, low self-efficacy, and low motivation (Casten & Rovner, 2008; Horowitz, Reinhardt, & Kennedy, 2005; Owsley & McGwin, 2004; Rovner, Casten, Hegel, & Tasman, 2006; Zhang, Bullard, & Saaddine, 2013). Only a few studies have evaluated the impact of personality, which shapes an individual's style of perceiving, responding to, and reporting visual difficulties (Boerner, Reinhardt, & Horowitz, 2006; Rovner & Casten, 2001; Tabrett & Latham, 2012; Warrian, Spaeth, Lankaranian, Lopes, & Steinmann, 2009). In fact, personality provides a more stable and enduring representation of a person than depression, which tends to be transient and dependent on situations (McCrae & Costa, 1990). One facet of personality is the trait of neuroticism, which refers to the increased tendency to experience negative, distressing emotions (McCrae & Costa, 1990). This trait is distributed normally in the population without a threshold indicative of disorder, and is moderately inheritable (Wray et al., 2008). Individuals on the extremes of the distribution get upset easily by life events and stay upset longer than others who face similar difficulties. They tend to be temperamental, anxious, and inflexible, and to hold pessimistic views of themselves and their circumstances. Thus, given the same degree of vision loss, people high and low in neuroticism might vary substantially in their reporting of functional vision. If their scores on the National Eye Institute Visual Function Questionnaire (NEI VFQ) differ, we cannot assume that the person who reports worse functional vision (that is, has a lower NEI VFQ score) has worse visual acuity than a person with a higher score (Mangione et al., 2001). The former person may simply have a perceptual bias that conveys greater distress and disability. The extent to which this phenomenon occurs in patients with AMD is uncertain because no studies, to our knowledge, have investigated it. If the extent is substantial, it may confound the results of studies on vision loss and disability or on the efficacy of ophthalmologic and rehabilitative treatments. In the study presented here, we tested the hypothesis that personality traits would influence self ratings of functional vision independently of objective measures of vision (that is, visual acuity, contrast sensitivity) in older persons with bilateral age-related macular degeneration (AMD). The subjects were enrolled in the Low Vision Depression Prevention TriAL (VITAL), which is a randomized controlled clinical trial that compares the efficacy of a combined mental health and low vision rehabilitation intervention with standard low vision rehabilitation to prevent depression (Casten & Rovner, n. …

Purpose In an observational clinical outcome study, we tested the effectiveness and use of the combination of two innovative approaches to magnification: a virtual bioptic telescope and a virtual projection screen, implemented with digital image processing in a head-mounted display (HMD) equipped with a high-resolution video camera and head trackers. Methods We recruited 30 participants with best-corrected visual acuity

PURPOSE This study is an evaluation of the responsiveness of preference-based outcome measures to the effects of low vision rehabilitation (LVR). It assesses LVR-related changes in EQ-5D utilities in patients who exhibit changes in Activity Inventory (AI) measures of visual ability. METHODS Telephone interviews were conducted on 77 low-vision patients out of a total of 764 patients in the parent study of "usual care" in LVR. Activity Inventory results were filtered for each patient to include only goals and tasks that would be targeted by LVR. RESULTS The EQ-5D utilities have weak correlations with all AI measures but correlate best with AI goal scores at baseline (r = 0.48). Baseline goal scores are approximately normally distributed for the AI, but EQ-5D utilities at baseline are skewed toward the ceiling (median, 0.77). Effect size for EQ-5D utility change scores from pre- to post-LVR was not significantly different from zero. The AI visual function ability change scores corresponded to a moderate effect size for all functional domains and a large effect size for visual ability measures estimated from AI goal ratings. CONCLUSIONS This study found that the EQ-5D is unresponsive as an outcome measure for LVR and has poor sensitivity for discriminating low vision patients with different levels of ability.

To compare low-vision rehabilitation (LVR) clinicians' predictions of the probability of success of LVR with patients' self-reported outcomes after provision of usual outpatient LVR services and to determine if patients' traits influence clinician ratings.The Activity Inventory (AI), a self-report visual function questionnaire, was administered pre-and post-LVR to 316 low-vision patients served by 28 LVR centers that participated in a collaborative observational study. The physical component of the Short Form-36, Geriatric Depression Scale, and Telephone Interview for Cognitive Status were also administered pre-LVR to measure physical capability, depression, and cognitive status. After patient evaluation, 38 LVR clinicians estimated the probability of outcome success (POS) using their own criteria. The POS ratings and change in functional ability were used to assess the effects of patients' baseline traits on predicted outcomes.A regression analysis with a hierarchical random-effects model showed no relationship between LVR physician POS estimates and AI-based outcomes. In another analysis, kappa statistics were calculated to determine the probability of agreement between POS and AI-based outcomes for different outcome criteria. Across all comparisons, none of the kappa values were significantly different from 0, which indicates that the rate of agreement is equivalent to chance. In an exploratory analysis, hierarchical mixed-effects regression models show that POS ratings are associated with information about the patient's cognitive functioning and the combination of visual acuity and functional ability, as opposed to visual acuity or functional ability alone.Clinicians' predictions of LVR outcomes seem to be influenced by knowledge of patients' cognitive functioning and the combination of visual acuity and functional ability-information clinicians acquire from the patient's history and examination. However, clinicians' predictions do not agree with observed changes in functional ability from the patient's perspective; they are no better than chance.

Purpose To compare the efficacy of problem-solving therapy (PST) with supportive therapy (ST) to improve targeted vision function (TVF) in age-related macular degeneration (AMD). Design Single-masked, attention-controlled, randomized clinical trial with outcome assessments at 3 months (main trial endpoint) and 6 months (maintenance effects). Participants Patients with AMD (n = 241) attending retina practices. Interventions Whereas PST uses a structured problem-solving approach to reduce vision-related task difficulty, ST is a standardized attention-control treatment. Main Outcome Measures We assessed TVF, the 25-item National Eye Institute Vision Function Questionnaire plus Supplement (NEI VFQ), the Activities Inventory (AI), and vision-related quality of life (QoL). Results There were no between-group differences in TVF scores at 3 ( P = 0.47) or 6 ( P = 0.62) months. For PST subjects, mean ± standard deviation TVF scores improved from 2.71±0.52 at baseline to 2.18±0.88 at 3 months ( P = 0.001) and were 2.18±0.95 at 6 months (change from 3 to 6 months, P = 0.74). For ST subjects, TVF scores improved from 2.73±0.52 at baseline to 2.14±0.96 at 3 months ( P = 0.001) and were 2.15±0.96 at 6 months (change from 3 to 6 months, P = 0.85). Similar proportions of PST and ST subjects had less difficulty performing a TVF goal at 3 months (77.4% vs 78.6%, respectively; P = 0.83) and 6 months (76.2% vs 79.1%, respectively; P = 0.61). There were no changes in the NEI VFQ or AI. Vision-related QoL improved for PST relative to ST subjects at 3 months ( F (4, 192) = 2.46; P = 0.05) and at 6 months ( F (4, 178) = 2.55; P = 0.05). The PST subjects also developed more adaptive coping strategies than ST subjects. Conclusions We found that PST was not superior to ST at improving vision function in patients with AMD, but that PST improved their vision-related QoL. Despite the benefits of anti-vascular endothelial growth factor treatments, AMD remains associated with disability, depression, and diminished QoL. This clinical reality necessitates new rehabilitative interventions to improve the vision function and QoL of older persons with AMD. Financial Disclosure(s) The authors have no proprietary or commercial interest in any of the materials discussed in this article.

A simple theoretical framework explains patient responses to items in rating scale questionnaires. Fixed latent variables position each patient and each item on the same linear scale. Item responses are governed by a set of fixed category thresholds, one for each ordinal response category. A patient’s item responses are magnitude estimates of the difference between the patient variable and the patient’s estimate of the item variable, relative to his/her personally defined response category thresholds. Differences between patients in their personal estimates of the item variable and in their personal choices of category thresholds are represented by random variables added to the corresponding fixed variables. Effects of intervention correspond to changes in the patient variable, the patient’s response bias, and/or latent item variables for a subset of items. Intervention effects on patients’ item responses were simulated by assuming the random variables are normally distributed with a constant scalar covariance matrix. Rasch analysis was used to estimate latent variables from the simulated responses. The simulations demonstrate that changes in the patient variable and changes in response bias produce indistinguishable effects on item responses and manifest as changes only in the estimated patient variable. Changes in a subset of item variables manifest as intervention-specific differential item functioning and as changes in the estimated person variable that equals the average of changes in the item variables. Simulations demonstrate that intervention-specific differential item functioning produces inefficiencies and inaccuracies in computer adaptive testing.

Purpose To develop and psychometrically evaluate a visual functioning questionnaire (VFQ) in an ultra-low vision (ULV) population. Methods Questionnaire items, based on visual activities self-reported by a ULV population, were categorized by functional visual domain (e.g., mobility) and visual aspect (e.g., contrast) to ensure a representative distribution. In Round 1, an initial set of 149 items was generated and administered to 90 participants with ULV (visual acuity [VA] ≤ 20/500; mean [SD] age 61 [15] years), including six patients with a retinal implant. Psychometric properties were evaluated through Rasch analysis and a revised set (150 items) was administered to 80 participants in Round 2. Results In Round 1, the person measure distribution (range, 8.6 logits) was centered at -1.50 logits relative to the item measures. In Round 2, the person measure distribution (range, 9.5 logits) was centered at -0.86 relative to the item mean. The reliability index in both rounds was 0.97 for Items and 0.99 for Persons. Infit analysis showed four underfit items in Round 1, five underfit items in Round 2 with a z-score greater than 4 cutoff. Principal component analysis on the residuals found 69.9% explained variance; the largest component in the unexplained variance was less than 3%. Conclusions The ULV-VFQ, developed with content generated from a ULV population, showed excellent psychometric properties as well as superior measurement validity in a ULV population. Translational relevance The ULV-VFQ, part of the Prosthetic Low Vision Rehabilitation (PLoVR) development program, is a new VFQ developed for assessment of functional vision in ULV populations.

Citation information: Stelmack JA, Tang XC, Reda DJ, Stroupe KT, Rinne S & Massof RW. VA LOVIT II: a protocol to compare low vision rehabilitation and basic low vision. Ophthalmic Physiol Opt 2012, 32, 461–471. doi: 10.1111/j.1475-1313.2012.00933.x Abstract Purpose: To compare the effectiveness of low vision rehabilitation (LVR) and basic low vision (LV) in a single masked multicentre randomised controlled trial (RCT). Methods: Three hundred and thirty patients eligible for US. Veterans Affairs (VA) healthcare services with primary eye diagnosis (better-seeing eye) of macular disease and best-corrected distance visual acuity of 0.40–1.00 logMAR (6/15 to 6/60 or 20/50 to 20/200 Snellen) are being enrolled at seven VA facilities. All participants receive an optometric LV examination; and they are eligible to receive the same LV devices that are provided without charge. In LVR, a LV therapist dispenses devices and provides 2 or 3 (1½ to 2½ h) therapy sessions with assigned homework to teach effective use of remaining vision and LV devices. Contact time with the therapist depends upon the devices prescribed and the patient’s progress in learning the skills that are taught. In basic LV, devices are dispensed by the optometrist without LV therapy. Contact time for dispensing is one hour or less depending on LV devices prescribed. The primary outcome measure is a comparison of the changes in visual reading ability (estimated from patients’ difficulty ratings of reading items on the VA LV VFQ-48 questionnaire) between the treatment and control arms from pre-intervention baseline to 4 months (2 months after completion of treatment). Secondary outcome measures are changes in overall visual ability, visual ability domain scores calculated from subsets of items (mobility, visual information processing and visual motor skills), Short Form-36, and Minnesota Low Vision Reading Test scores. Cost-effectiveness analysis will be conducted using VA LV VFQ-48 scores and QALYS computed from EuroQol scores. Results: A total of 137 patients representing 41.5% of the study target of 330 patients were randomised from October 2010 to March 2012. Among those 137 patients, mean age was 80.2 (S.D. ± 9.9) years at enrollment; 97.1% of the patients were males; 94.2% were white. Mean best corrected VA was 0.65 (S.D. ± 0.3) logMAR (approximately Snellen 6/27 or 20/90) at baseline. Conclusions: LOVIT II is the first multicentre RCT comparing the effectiveness and cost-effectiveness of LVR and basic LV for patients with macular diseases and near normal or moderate levels of visual impairment.

To determine if visual field (VF) loss resulting from glaucoma is associated with greater fear of falling.Prospective, observational study.Fear of falling was compared between 83 glaucoma subjects with bilateral VF loss and 60 control subjects with good visual acuity and without significant VF loss recruited from patients followed up for suspicion of glaucoma.Participants completed the University of Illinois at Chicago Fear of Falling Questionnaire. The extent of fear of falling was assessed using Rasch analysis.Subject ability to perform tasks without fear of falling was expressed in logits, with lower scores implying less ability and greater fear of falling.Glaucoma subjects had greater VF loss than control subjects (median better-eye mean deviation [MD] of -8.0 decibels [dB] vs. +0.2 dB; P0.001), but did not differ with regard to age, race, gender, employment status, the presence of other adults in the home, body mass index (BMI), grip strength, cognitive ability, mood, or comorbid illness (P ≥ 0.1 for all). In multivariate models, glaucoma subjects reported greater fear of falling as compared with controls (β = -1.20 logits; 95% confidence interval [CI], -1.87 to -0.53; P = 0.001), and fear of falling increased with greater VF loss severity (β = -0.52 logits per 5-dB decrement in the better eye VF MD; 95% CI, -0.72 to -0.33; P0.001). Other variables predicting greater fear of falling included female gender (β = -0.55 logits; 95% CI, -1.03 to -0.06; P = 0.03), higher BMI (β = -0.07 logits per 1-unit increase in BMI; 95% CI, -0.13 to -0.01; P = 0.02), living with another adult (β = -1.16 logits; 95% CI, -0.34 to -1.99 logits; P = 0.006), and greater comorbid illness (β = -0.53 logits/1 additional illness; 95% CI, -0.74 to -0.32; P0.001).Bilateral VF loss resulting from glaucoma is associated with greater fear of falling, with an impact that exceeds numerous other risk factors. Given the physical and psychological repercussions associated with fear of falling, significant quality-of-life improvements may be achievable in patients with VF loss by screening for, and developing interventions to minimize, fear of falling.

The purpose of the study is to evaluate the relationship between time trade off (TTO) and standard gamble (SG) estimates of health and vision utilities in a low vision patient sample.Telephone surveys were conducted on 74 low vision patients. All study participants were administered utility questionnaires that used the TTO and SG methods as they relate to health and vision.There is high between-person variability in the relationship of TTO- to SG-estimated utilities for both vision and health. However, when transformed to logits, differences between TTO and SG utilities for health are equal to differences between TTO and SG utilities for vision. These differences are symmetrically distributed around the origin. The data were consistent with a model that includes both health or vision state and personal response criteria. The model explains between-person variability in the relationship of TTO to SG utilities as idiosyncratic differences within people between response criteria for making TTO and SG judgments.The large between-person variability in the relation of utilities estimated from TTO to those estimated from SG can be explained by large between- and within-person variability in personal TTO and SG response criteria. However, within each person, the response criteria used to judge health state are the same as the response criteria used to judge vision state. This observation leads to the conclusion that health and vision states are in the same units when estimated from utilities. A meta-analysis of published studies that compared TTO with SG utilities for different health states confirms the conclusion of the model that average utilities across people are criterion-free estimates of average health-related states on a common logit scale.

Age-Related Macular Degeneration (AMD) is the leading cause of severe vision loss in older adults and impairs the ability to read, drive, and live independently and increases the risk for depression, falls, and earlier mortality. Although new medical treatments have improved AMD's prognosis, vision-related disability remains a major public health problem. Improving Function in AMD (IF-AMD) is a two-group randomized, parallel design, controlled clinical trial that compares the efficacy of Problem-Solving Therapy (PST) with Supportive Therapy (ST) (an attention control treatment) to improve vision function in 240 patients with AMD. PST and ST therapists deliver 6 one-hour respective treatment sessions to subjects in their homes over 2 months. Outcomes are assessed masked to treatment assignment at 3 months (main trial endpoint) and 6 months (maintenance effects). The primary outcome is targeted vision function (TVF), which refers to specific vision-dependent functional goals that subjects highly value but find difficult to achieve. TVF is an innovative outcome measure in that it is targeted and tailored to individual subjects yet is measured in a standardized way. This paper describes the research methods, theoretical and clinical aspects of the study treatments, and the measures used to evaluate functional and psychiatric outcomes in this population.

Purpose We evaluated the validity of a single dry eye severity measure estimated using Rasch analysis from a battery of clinical tests and patient symptoms. Methods This study included 203 dry eye patients and 51 controls. Administered tests included the Ocular Surface Disease Index (OSDI), tear osmolarity, Schirmer's test, noninvasive break-up time, and ocular surface staining. Each of the 12 OSDI questions and each clinical test was defined to be a separate indicator to estimate a single dry eye severity measure from Rasch analysis. Measures of severity were estimated for each subject (person measures) and measures of sensitivity to severity were estimated for each sign and symptom (indicator measures). Results The average severity measure for dry eye patients was significantly greater than the average severity measure for controls (−0.39 vs. −1.2, P < 0.001). The distribution of indicator measures was well matched to the distribution of person measures. No indicator carried >10% of the total information about dry eye severity carried by all indicators together. However, the most informative indicators were corneal and conjunctival staining. Conclusions Our study indicated that there is no single “best” dry eye test. Clinical tests and symptoms should be used in combination to estimate a single dry eye severity measure. Translational Relevance There is no single “gold standard” testing method for dry eye that correlates with the severity of disease. We propose that Rasch analysis can be used to calculate an objective dry eye severity score from a battery of clinical indicators.

A low vision rehabilitation program with a structured curriculum was evaluated in a randomized controlled trial. The treatment group demonstrated large improvements in self-reported visual function (reading, mobility, visual information processing, visual motor skills, and overall). The team approach and the protocols of the treatment program are described. ********** Outcomes research is focused on understanding the "end results" of health care interventions (Agency for Healthcare Research and Quality, 2000). For individuals with chronic conditions, for whom a cure is not possible, "end results" must include measures of effects that they experience and care about, such as their perception of their ability to function at home and in the community. "For clinicians and patients, outcomes research informs decision making by providing evidence of the risks, benefits, and results of treatment" (Agency for Healthcare Research and Quality, 2000). Clinicians who use evidence-based practice integrate their clinical experience with research evidence in making decisions about the care of individual patients (Mozlin, 2000). As health care costs escalate and increase competition for resources, policy makers are using outcomes research to identify strategies that can be implemented through evidence-based policy to improve the "quality and value of care" (Gray, 2001). The need, demand, and costs associated with low vision care are expected to increase as the U.S. population ages because there is as yet no cure for most age-related eye diseases, and the incidence and prevalence rates of chronic visual impairments increase rapidly with age (Massof, 2002). Low vision outcomes must be studied, using the same standards that are applied to other medical treatments, with scientifically rigorous studies, such as randomized controlled trials, to develop an evidence base to guide policy and funding decisions and support guidelines for clinical practice. The Department of Veterans Affairs (VA) Low Vision Intervention Trial (LOVIT) was designed to provide evidence of the effectiveness of low vision rehabilitation. LOVIT evaluated an outpatient-based low vision rehabilitation program that was targeted to veterans with moderate and severe macular diseases using a randomized controlled trial design. The program was modeled after the inpatient Hines Blind Rehabilitation Center low vision rehabilitation program, that has been shown to be effective in previous outcomes studies (Stelmack, Moran, Dean, & Massof, 2007; Stelmack, Stelmack, & Massof, 2002; Stelmack et al., 2006) using lessons that were adopted from or are similar to those found in manuals and textbooks on low vision therapy (Backman & Inde, 1979; Freeman & Jose, 2000; Jose, 1985; Lund & Watson, 1997; Quillman, 1980; Wright & Watson, 1995). The goal of the LOVIT investigators was to determine if the low vision program achieved at least a moderate treatment effect. If so, the program could be compared to other service delivery models or curricula in future studies. LOVIT was conducted at the Hines, Illinois, and Salisbury, North Carolina, VA medical facilities. The institutional review boards at both facilities approved the protocol and informed consents. The research followed the tenets of the Declaration of Helsinki for research on human subjects. The participants in the trial were 126 veterans with macular diseases whose visual acuity in the better-seeing eye was worse than 20/100 and better than 20/500. They were selected randomly for low vision rehabilitation treatment (a low vision examination followed by six weekly therapy sessions and the prescription and dispensing of low vision devices) or were placed on a waiting list control group. Those in the control group were offered other low vision services or admission to a VA blind rehabilitation center after the trial was completed. The participants in the treatment and control groups rated the difficulty they experienced performing common activities during the telephone administration of the VA Low Vision Visual Functioning Questionnaire-48 (VA LV VFQ-48) (Stelmack, Szlyk, Stelmack, Babcock-Parziale et al. …

The Department of Veterans Affairs (VA) Low Vision Intervention Trial (LOVIT) developed an outpatient low-vision programme for patients with macular diseases providing low-vision rehabilitation comparable to VA inpatient blind rehabilitation centres (BRCs). This programme targets veterans who do not need or chose not to participate in a comprehensive inpatient blind rehabilitation programme. We examined costs and consequences using veterans in LOVIT and comparable veterans in an inpatient BRC.We compared costs and consequences between treatment patients who participated in LOVIT, a two-site randomized clinical trial, and a sample of comparable patients who received treatment at a VA inpatient BRC. We measured consequences as the change in functional visual ability from baseline to follow-up (LOVIT: 4 months after randomization; BRC: 3 months after discharge) using the VA Low Vision Visual Functioning Questionnaire (VA LV VFQ-48).There were 55 LOVIT and 121 BRC patients for our analyses. Average costs were $38,627.3 higher for BRC patients ($5,054.4 +/- $404.7 SD for LOVIT vs. $43,681.7 +/- $8,853.6 SD for BRC, p0.0001). Thus, the BRC cost $38,627.3 per patient more than the LOVIT programme (95% CI: $17,414 to $273,482). There was a greater improvement in overall visual ability, mobility, and visual motor skill scores for BRC patients; however, there was no significant difference in improvement in reading ability or visual information processing scores.As VA increases outpatient blind rehabilitation services, LOVIT provides a model for expanding outpatient low-vision rehabilitation services for veterans at substantially lower costs than current inpatient BRC services.

PURPOSE. The Activity Inventory (AI) is an adaptive visual function questionnaire that consists of 459 Tasks nested under 50 Goals that in turn are nested under three Objectives. Visually impaired patients are asked to rate the importance of each Goal, the difficulty of Goals that have at least some importance, and the difficulty of Tasks that serve Goals that have both some importance and some difficulty. Consequently, each patient responds to an individually tailored set of questions that provides both a functional history and the data needed to estimate the patient’s visual ability. The purpose of the present article is to test the hypothesis that all combinations of items in the AI, and by extension all visual function questionnaires, measure the same visual ability variable. METHODS. The AI was administered to 1880 consecutively-recruited low vision patients before their first visit to the low vision rehabilitation service. Of this group, 407 were also administered two other visual function questionnaires randomly chosen from among the Activities of Daily Living Scale (ADVS), National Eye Institute Visual Functioning Questionnaire (NEI VFQ), 14-item Visual Functioning Index (VF-14), and Visual Activities Questionnaire (VAQ). Rasch analyses were performed on the responses to each VFQ, on all responses to the AI, and on responses to various subsets of items from the AI. RESULTS. The pattern of fit statistics for AI item and person measures suggested that the estimated visual ability variable is not unidimensional. Reading-related and other items requiring high visual resolution had smaller residual errors than expected and mobility-related items had larger residual errors than expected. The pattern of person measure residual errors could not be explained by the disorder diagnosis. When items were grouped into subsets representing four visual function domains (reading, mobility, visual motor, visual information), and separate person measures were estimated for each domain as well as for all items combined, visual ability was observed to be equivalent to the first principal component and accounted for 79% of the variance. However, confirmatory factor analysis showed that visual ability is a composite variable with at least two factors: one upon which mobility loads most heavily and the other upon which reading loads most heavily. These two factors can account for the pattern of residual errors. High product moment and intraclass correlations were observed when comparing different subsets of items within the AI and when comparing different VFQs. CONCLUSIONS. Visual ability is a composite variable with two factors; one most heavily influences reading function and the other most heavily influences mobility function. Subsets of items within the AI and different VFQs all measure the same visual ability variable.

The aim of the study is to test if EQ-5D, a more generic instrument, and Activity Inventory, a more specific instrument to the visual condition, produce consistent results when considering the different levels of visual impairment. By assessing how these instruments reflect visual status in a sample of patients with visual impairment, we will help to understand how they can work in cultural context and population in which they were never tested before.Method is based on Multivariate Analysis of Variance, in which the levels of visual impairment (slightly, moderate, severe/blindness) are defined through the visual acuity values, and the utility values derived from EQ-5D and the Activity Inventory.Participants were recruited in 3 public hospitals as a part of an ongoing study of prevalence and costs of visual impairment in Portugal. Patients attending outpatient appointments in these hospitals with acuity in the better eye of 0,30logMAR or worse and/or visual field in the better eye Poster presentation

Massof RW, Hsu CT, Baker FH, Barnett GD, Park WL, Deremeik JT, Rainey C, Epstein C. Visual disability variables. I: The importance and difficulty of activity goals for a sample of low-vision patients. Objective To test the validity and reliability of latent trait measures estimated from ratings by low-vision patients of the importance and difficulty of selected activity goals. Design Validation of a telephone-administered functional assessment instrument using Rasch analysis of self-assessment ratings. Setting Telephone interviews of respondents in their homes. Participants Consecutive series of 600 outpatients with low vision. Interventions Not applicable. Main outcome measures Ratings of the importance and difficulty of achieving 41 activity goals. Person and item traits were measured with the Andrich rating scale model. Measurement validity and reliability were tested statistically by comparing response patterns and distributions with measurement model expectations. Results Patients could distinguish only 3 categories of importance and 4 categories of difficulty. The distributions of person and item measure fit statistics were consistent with 2 unidimensional constructs: value of independence estimated from importance ratings and visual ability estimated from difficulty ratings. However, 8 of 41 activity goals were poor estimators of value of independence and 7 of 41 activity goals were poor estimators of visual ability. Person measure distributions could be divided into 3 statistically distinct strata for estimates from both importance ratings and difficulty ratings. Item measure distributions could be divided into 21 strata for estimates from importance ratings and 7 strata for estimates from difficulty ratings. Conclusions The 2 variables that define visual disability—value of independence and visual ability—are valid constructs that can be estimated accurately and reliably from patient ratings of the importance and difficulty of activity goals.

Massof RW, Hsu CT, Baker FH, Barnett GD, Park WL, Deremeik JT, Rainey C, Epstein C. Visual disability variables. II: The difficulty of tasks for a sample of low-vision patients. Objectives To test the validity and reliability of measures of visual ability and to evaluate the relation between measurements made at the task level and measurements made at the goal level of a hierarchical model for visual disability. Design Validation of a telephone-administered functional assessment instrument using Rasch analysis on self-assessment ratings. Setting Telephone interviews of respondents in their homes. Participants Consecutive series of 600 outpatients with low vision. Interventions Not applicable. Main outcome measures Ordinal ratings of the difficulty in performing a subset of 337 tasks. Measures of the visual ability of each patient and the required visual ability to perform each task were made using the Andrich rating scale model. Measurement validity and reliability were tested statistically by comparing response patterns and distributions to measurement model expectations. Results Results were consistent with a single visual ability construct. Patients' visual ability estimated from task difficulty ratings agreed with estimates from goal difficulty ratings ( r =.74); the difficulty of individual goals was equal to the weighted average of the difficulties of subsidiary tasks ( r =.79). However, conclusions from the Rasch analysis were not confirmed by principal components analysis of item residuals, which indicated that visual ability had a 2-dimensional structure, with 1 factor related to mobility and the other related to reading. Factor analysis on person measures estimated from subsets of functionally grouped items confirmed the 2-dimensional structure of visual ability. Conclusions Our study results confirm the hierarchical structure of the Activity Breakdown Structure model and show how the individualized Activity Inventory can produce measures of limitations in functional vision.

To test hypotheses that low vision patient responses to visual function rating scale questionnaires conform to an additive conjoint structure and that the Likert score is a sufficient statistic for the latent patient trait; to compare results for two competing stochastic measurement models; and to determine if different questionnaires measure the same construct in low vision patients.Visual function rating scale questionnaires were administered to 284 low vision subjects by telephone. Each subject was administered two of four questionnaires: ADVS, NEI VFQ-25 plus supplement, expanded VAQ, and VF-14.Data were analyzed with the Muraki item response model and the Andrich measurement model. The estimates of latent person, item, and response threshold measures from the two models are linearly related. The Muraki model produced a better overall fit to the item response data, the Andrich model produced a better fit to the average ratings for each person and item. Fit statistics for the Andrich model were proportional to the item-dependent discrimination parameter in the Muraki model. The ADVS was the most accurate measure and the NEI VFQ was the least. Reliability was similar for all four instruments. Person measures for each pair of instruments were linearly related indicating that all four instruments measured the same construct. The person measure estimate from the Andrich model is monotonic with the average rating. That relationship suggests a transformation of the Likert score that can correct the floor and ceiling effects in rating scale data.Patient responses to all four questionnaires conform to varying degrees to an additive conjoint structure. The Likert score is a sufficient statistic for the ADVS and the VAQ, but not for the NEI VFQ or VF-14. All four instruments measure the same construct in the low vision population, but they differ in measurement accuracy and precision.

The purpose of this study was to develop an instrument that would be sensitive to the visual difficulties of persons with low vision and that could be used to evaluate outcomes and plan vision rehabilitation services. Toward that end, the Veterans Affairs Low Vision Visual Functioning Questionnaire was administered to 117 participants in rehabilitation programs in Veterans Affairs medical centers and in the private sector. The results demonstrate that the questionnaire is an effective instrument for measuring vision difficulties in persons who receive low-vision rehabilitation.

Visual impairment among nursing home residents is higher than in community-dwelling elderly. The provision of eye care services may be beneficial to nursing home patients. Our project, a randomized trial of vision restoration and rehabilitation in nursing home residents, compares usual care to targeted interventions. In this paper, we present the baseline characteristics of our sample within the nursing homes.Twenty-eight nursing homes on Maryland's Eastern Shore were matched in pairs by size and payment type. Each pair was randomized to usual care or targeted intervention. Habitual and best-corrected acuity was attempted, using standard letter symbol/charts and grating acuity charts. Visual impairment was vision in the better eye20/40 on letter and/or grating acuity. The MiniMental State Examination (MMSE) was used to determine cognitive impairment.Of those participants eligible to be screened, 40% had severe cognitive impairment (MMSE score 0-9). No measure of acuity could be ascertained on 18% of eligibles. Among the 1305 persons with acuity data, 38% had presenting vision worse than 20/40. After refractive correction, 29% had visual impairment. There was no difference by race or gender in those with visual impairment, although they were older, compared to those without visual loss.The nursing home residents had high rates of both cognitive impairment and visual impairment, creating a challenging environment for visual intervention. By improving access to eye care within the context of the clinical trial, and changing either the magnitude of visual loss or the resultant impact on function, we hope to demonstrate a change in the quality of life for nursing home residents.

The American Medical Association's (AMA) visual efficiency scale, a vision disability metric based on visual impairment measurements, was adopted in 1925. That scale was based on a 30-year history of theoretical models in vision economics, a misinterpretation of Snellen notation for visual acuity, and an erroneous application of Weber's psychophysical law. The AMA visual efficiency scale survived uncontested for 75 years. In 2001, the AMA adopted a new vision disability scale based on logarithmic transformations of visual acuity and visual field diameter. Like the earlier visual efficiency scale, the new scale is theoretical-it is not supported by any data that speak to the relationship between vision disability and visual impairments. Attempts to measure vision disability date to the early 1980s with the development of self-assessment visual function rating scale questionnaires. Nearly all of the questionnaires developed over the last 20 years use Likert scales, but use them incorrectly. The development of a vision disability metric based on Likert scaling parallels the historical development of other forms of measurement. A tutorial review of psychometrics-classical test theory, item response theory, and Rasch analysis-shows how vision disability measurement scales can be estimated from Likert-type visual function rating scales. We conclude that preliminary data relating measures of vision disability to measures of visual acuity and visual fields support the new AMA vision disability scale.

Purpose To compare the efficacy of behavioral activation (BA) plus low vision rehabilitation with an occupational therapist (OT-LVR) with supportive therapy (ST) on visual function in patients with age-related macular degeneration (AMD). Methods Single-masked, attention-controlled, randomized clinical trial with AMD patients with subsyndromal depressive symptoms (n = 188). All subjects had two outpatient low vision rehabilitation optometry visits, then were randomized to in-home BA + OT-LVR or ST. Behavioral activation is a structured behavioral treatment aiming to increase adaptive behaviors and achieve valued goals. Supportive therapy is a nondirective, psychological treatment that provides emotional support and controls for attention. Functional vision was assessed with the activity inventory (AI) in which participants rate the difficulty level of goals and corresponding tasks. Participants were assessed at baseline and 4 months. Results Improvements in functional vision measures were seen in both the BA + OT-LVR and ST groups at the goal level (d = 0.71; d = 0.56 respectively). At the task level, BA + OT-LVR patients showed more improvement in reading, inside-the-home tasks and outside-the-home tasks, when compared to ST patients. The greatest effects were seen in the BA + OT-LVR group in subjects with a visual acuity ≥20/70 (d = 0.360 reading; d = 0.500 inside the home; d = 0.468 outside the home). Conclusions Based on the trends of the AI data, we suggest that BA + OT-LVR services, provided by an OT in the patient's home following conventional low vision optometry services, are more effective than conventional optometric low vision services alone for those with mild visual impairment. (ClinicalTrials.gov number, NCT00769015.).