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Purpose: As vision is required in almost all activities of daily living, visual impairment (VI) may be one of the major treatable factors for preventing activity limitations. We aimed to evaluate the attributable risk of VI associated with activity limitations and the extent to which limitations are avoidable with optimal optical correction of undercorrected refractive errors., Methods: We analyzed 709 older adults from the Three-City-Alienor population-based study. VI was defined by presenting distance visual acuity in the better-seeing eye. Multivariate modified Poisson regressions were used to estimate the associations between vision, activity limitations, and social participation restrictions. Population attributable risk (PAR) and generalized impact fraction (GIF) were estimated. Bootstrapping was used to estimate 95% confidence intervals (CI)., Results: After adjustment for potential confounders, VI was associated with each domain of activity limitations, except basic activities of daily living (ADL) limitations. These associations were found for even minimal levels of VI. PAR was estimated at 10.1% (95% CI: 5.2-10.6) for mobility limitations, at 26.0% (95% CI: 13.5-41.2) for instrumental ADL (IADL) limitations, and at 24.9% (95% CI: 10.5-47.1) for social participation restrictions. GIF for improvement of undercorrected refractive errors was 6.1% (95% CI: 3.8-8.5) for mobility limitations, 15.8% (95% CI: 11.5-20.1) for IADL limitations and 21.4% (95% CI: 13.8-28.5) for social participation restrictions., Conclusions: About one-sixth of IADL limitations and one-fifth of social participation restrictions could be prevented by an optimal optical correction. These results underline the importance of eye examinations in older adults to prevent disability.

Purpose: To examine the effect of a home visit-based visual rehabilitation intervention on: (1) self-reported visual function and (2) depression, wellbeing, loneliness, adjustment to visual loss, and generic health-related quality of life., Methods: In an exploratory, assessor-masked, individually randomized, single-center controlled trial, 67 participants (age: 75.22 ± 16.21 years) with low vision were allocated either to receive the home visit-based visual rehabilitation intervention (n = 35) or to a waiting list control arm (n = 32). Outcome measures were collected by telephone interview at baseline and 6 months later. The primary outcome measure was the 48-item Veterans Affairs Low Vision Visual Functioning Questionnaire (VA LV VFQ-48). Secondary outcome measures were: the Patient Health Questionnaire; the Warwick-Edinburgh Mental Well-being Scale, the Adjustment to Age-related Visual Loss Scale, the standardized health-related quality of life questionnaire, and the University of California, Los Angeles Loneliness Scale. Questionnaire scores at follow-up were analyzed using analysis of covariance, controlling for the baseline score and the variables, age, number of comorbidities, visual acuity, and baseline wellbeing score., Results: Visual function (VA LV VFQ-48) improved at follow-up in both groups, with a significantly greater improvement demonstrated by the intervention group (95% confidence interval, 0.33-0.68 logits, P = 0.031), with a moderate effect size (0.55). Secondary outcomes did not indicate any statistically significant differences between groups., Conclusions: The study provides preliminary evidence that a home visit-based visual rehabilitation intervention has a positive influence on vision-related functional outcomes. A larger trial with an expanded intervention to include a mental health component and cost-effectiveness analysis is needed. (ISRCTN.com number, 44807874.).

Purpose: Spatial updating is the ability to keep track of position and orientation while moving through an environment. We asked how normally sighted and visually impaired subjects compare in spatial updating and in estimating room dimensions., Methods: Groups of 32 normally sighted, 16 low-vision, and 16 blind subjects estimated the dimensions of six rectangular rooms. Updating was assessed by guiding the subjects along three-segment paths in the rooms. At the end of each path, they estimated the distance and direction to the starting location, and to a designated target. Spatial updating was tested in five conditions ranging from free viewing to full auditory and visual deprivation., Results: The normally sighted and low-vision groups did not differ in their accuracy for judging room dimensions. Correlations between estimated size and physical size were high. Accuracy of low-vision performance was not correlated with acuity, contrast sensitivity, or field status. Accuracy was lower for the blind subjects. The three groups were very similar in spatial-updating performance, and exhibited only weak dependence on the nature of the viewing conditions., Conclusions: People with a wide range of low-vision conditions are able to judge room dimensions as accurately as people with normal vision. Blind subjects have difficulty in judging the dimensions of quiet rooms, but some information is available from echolocation. Vision status has little impact on performance in simple spatial updating; proprioceptive and vestibular cues are sufficient.

About 20%-30% of patients undergoing neurological rehabilitation report visual field defects, one of the most frequent of which is homonymous hemianopsia (loss of the same half of the visual field in both eyes). There is still no consensus as to whether homonymous hemianopsia is best treated in a restorative or compensatory manner. The aim of this review is to describe the effects of restorative rehabilitation, whose long-term efficacy is still being debated. We analyzed 56 articles describing the use of various techniques used to promote visual field recovery but concentrating on two approaches: "border training," which involves exercising vision at the edge of the damaged visual field, and "blindsight training," which is based on exercising unconscious perceptual functions in the mild of the blind hemifield where the scotoma is deep. Both techniques have been supported by functional imaging studies showing evidence of cortical rearrangement (plasticity) after rehabilitation. Although no formal meta-analysis was possible, the results of a semiquantitative evaluation suggested that the improvement in visual skills obtained is related to the type of training used: Border rehabilitation seems to improve the detection of visual stimuli, whereas blindsight rehabilitation seems to improve their processing. Finally, the addition of transcranial direct current stimulation seems to enhance the effects of visual field rehabilitation.

Purpose: To evaluate the outcomes of multidisciplinary low vision rehabilitation (LVR) in adults with low vision (LV) in India using the Veterans Affairs Low Vision Visual Functioning Questionnaire (VA LV VFQ-48) and the Impact of Vision Impairment (IVI) questionnaire., Methods: Consecutive adults with LV referred for the first time to the Centre for Sight Enhancement were administered the 28-item IVI and VA LV VFQ-48 before and after LVR (4 months). Rasch-scaled scores were generated for the IVI and the VA LV VFQ-48 along with each of their subscales at both the time points. Effect size (ES) was calculated using Cohen's d coefficient., Results: Two hundred fifty-five patients completed the LVR program. Following LVR, the linear measures revealed significant improvements in vision-related quality of life (VRQoL) using the IVI at follow-up (P < 0.0001), with large ES for reading and accessing information (ES = 1.0) and relatively moderate ES for overall IVI (ES = 0.63) and mobility subscale (ES = 0.53). No significant improvement was found on emotional well-being subscale (ES = 0.18; P = 0.06). Similarly, significant improvements in VRQoL (P < 0.0001) were found for the VA LV VFQ-48 at follow-up, albeit moderate ES for the overall visual ability (ES = -0.67) and its subscales (reading [ES = -0.72], mobility [ES = -0.45], visual information [ES = -0.47), visual motor [ES = -0.54])., Conclusions: Regardless of the instrument used for assessment, our multidisciplinary LVR program resulted in statistically significant improvements in visual functioning and VRQoL of those adults with LV deemed appropriate for intervention (dropout rates were high); however, the improvements were modest, and the clinical relevance of these small improvements may be limited. Nonetheless, further studies should attempt to increase the completion rates in order to draw strong inferences.

Purpose: Bioptic telescopic spectacles (BTS) consist of a small telescope (or telescopes) mounted high in a pair of spectacle lenses. More than 40 states allow for some form of bioptic driving licensure for people with decreased central vision. The purpose of this study was to determine significant associations among previous driving experience, vision, and motor vehicle collisions (MVCs) for bioptic drivers in Ohio., Methods: We conducted a retrospective study of patients who received a vision examination and subsequently obtained bioptic licensure. We obtained driving records from the Ohio Bureau of Motor Vehicles in order to determine MVC involvement. Relationships among vision measures, age, sex, previous experience, and MVCs were investigated using time-to-event analysis and the Cox proportional hazards regression model., Results: We identified 237 bioptic drivers (65% male). Age at initial exam ranged from 16 to 81 years, and mean visual acuity was approximately 20/120. The number of MVCs per driver ranged from 0 to 11, with 124 (52%) drivers having had at least one MVC. Visual acuity and contrast sensitivity were not significant predictors of MVC. Drivers without previous driving experience were significantly more likely to have been involved in an MVC (P < 0.001), and this association remained significant after adjusting for age and sex (P = 0.01). The rate of MVC per year decreased steadily over a 10-year period for drivers without previous experience., Conclusions: Previous nonbioptic driving experience, but not visual acuity or contrast sensitivity, was associated with yearly MVC rate in bioptic drivers.

Purpose: Severe visual impairment can have a profound impact on personal independence through its effect on mobility. We investigated whether the mobility of people with vision low enough to be registered as blind could be improved by presenting the visual environment in a distance-based manner for easier detection of obstacles., Methods: We accomplished this by developing a pair of "residual vision glasses" (RVGs) that use a head-mounted depth camera and displays to present information about the distance of obstacles to the wearer as brightness, such that obstacles closer to the wearer are represented more brightly. We assessed the impact of the RVGs on the mobility performance of visually impaired participants during the completion of a set of obstacle courses. Participant position was monitored continuously, which enabled us to capture the temporal dynamics of mobility performance. This allowed us to find correlates of obstacle detection and hesitations in walking behavior, in addition to the more commonly used measures of trial completion time and number of collisions., Results: All participants were able to use the smart glasses to navigate the course, and mobility performance improved for those visually impaired participants with the worst prior mobility performance. However, walking speed was slower and hesitations increased with the altered visual representation., Conclusions: A depth-based representation of the visual environment may offer low vision patients improvements in independent mobility. It is important for further work to explore whether practice can overcome the reductions in speed and increased hesitation that were observed in our trial.

Purpose: To evaluate the change in visual functioning (VF) using the L. V. Prasad-Functional Vision Questionnaire II (LVP-FVQ II) following multidisciplinary low vision rehabilitation (LVR) services in children with low vision (LV)., Methods: Children with LV referred for the first time to the Centre for Sight Enhancement were administered the LVP-FVQ II at baseline and at 3 to 4 months' follow-up to assess the outcomes of LVR. Participants' responses to the LVP-FVQ II at baseline and follow-up were transformed into interval-level estimates of VF using Rasch analysis. Cohen's d values (effect size) were used to estimate the magnitude of change in VF., Results: A total of 183 participants completed the rehabilitation (mean age, 11.9 years; male, 57%). More than one-half of the participants had retinal disorders (55%) and most were moderately visually impaired (<20/60-20/200, 76.5%). Using the LVP-FVQ II, significant improvement in VF after rehabilitation was recorded (P < 0.0001) and the increase in VF (SD) was 1.20 (1.82) logits. Using Cohen's d, the magnitude of the improvement in LVR intervention at follow-up was found to be 0.75, indicating nearly large treatment effect., Conclusions: Ours is the first study to provide strong evidence that LVR services result in nearly large and significant improvements in the overall VF in children with LV, regardless of the cause of LV. These results should encourage eye care professionals to refer children with LV to LVR services. Further investigation is needed to determine if the improvement in VF can be sustained over a longer duration (>4 months).

Purpose: A pocket-sized collision warning device equipped with a video camera was developed to predict impending collisions based on time to collision rather than proximity. A study was conducted in a high-density obstacle course to evaluate the effect of the device on collision avoidance in people with peripheral field loss (PFL)., Methods: The 41-meter-long loop-shaped obstacle course consisted of 46 stationary obstacles from floor to head level and oncoming pedestrians. Twenty-five patients with tunnel vision (n = 13) or hemianopia (n = 12) completed four consecutive loops with and without the device, while not using any other habitual mobility aid. Walking direction and device usage order were counterbalanced. Number of collisions and preferred percentage of walking speed (PPWS) were compared within subjects., Results: Collisions were reduced significantly by approximately 37% (P < 0.001) with the device (floor-level obstacles were excluded because the device was not designed for them). No patient had more collisions when using the device. Although the PPWS were also reduced with the device from 52% to 49% (P = 0.053), this did not account for the lower number of collisions, as the changes in collisions and PPWS were not correlated (P = 0.516)., Conclusions: The device may help patients with a wide range of PFL avoid collisions with high-level obstacles while barely affecting their walking speed.

Purpose: To determine the validity, reliability, and measurement characteristics using factor and Rasch analysis of the Very Low Vision Instrumental Activities of Daily Living (IADL-VLV) in persons with severe vision loss., Methods: From an initial pool of 296 tasks, 25 were shortlisted after conducting a Delphi survey with persons designated legally blind. Using further input from occupational therapy and low-vision professionals, 11 activities were chosen to be pilot tested. Forty legally blind participants (better eye visual acuity < 20/200) underwent clinical assessments and functional tests as well as the 53 IADL tasks related to the 11 activities. The task pool was refined and condensed using factor and Rasch analysis., Results: Based on iterative principal component analyses, tasks were grouped together into the following domains: reading signs/information access, signature placement, clothes sorting, shelf search, gesture recognition, clock reading, and table search. A final selection of 23 tasks yielded satisfactory measurement characteristics, differentiated between at least four different levels of IADL performance (person separation of 3.8), and had adequate task difficulty for the tested sample (person mean -0.61). In multivariate analyses, only visual acuity (VA) and percent of remaining visual field (VF) were associated with IADL performance., Conclusions: Using a large item pool, participant, and expert input, as well as factor and Rasch analysis, we designed a valid and reliable assessment to measure vision-related IADL performance in persons with severe vision loss. This assessment tool can be used in clinical sight restoration trials., (Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.)

Purpose: To design and evaluate an instrument appropriate for assessing vision-related quality of life (VRQoL) in persons with severe vision loss., Methods: A total of 603 legally blind persons (better eye visual acuity of <20/200) were interviewed using an item pool based on the original Impact of Vision Impairment (IVI) questionnaire, augmented by items appropriate for persons with severe vision loss. Refinement and item reduction was done in three steps using factor and Rasch analysis to assess psychometric properties, exploring key indices, such as response category functioning (floor and ceiling effects), instrument unidimensionality, discriminant ability, and targeting of item difficulty to patient ability., Results: A final pool of 28 items was selected that grouped into two subscales of the IVI-VLV: activities of daily living, mobility, and safety (ADLMS; 16 items) and emotional well-being (EWB; 12 items). Both subscales are unidimensional, able to differentiate reliably between at least three different levels of VRQoL, and item difficulty was adequate for the assessed sample. Using generalized linear models and controlling for age, we found that only poor general health (P = 0.005 and P = 0.007) and concurrent depression and anxiety (P = 0.019 and P < 0.001) were associated with a lower ADLMS and EWB subscale score, respectively., Conclusions: The IVI-VLV is a valid and reliable VRQoL measure in persons with severe vision loss, and its measurement is almost unaffected by participants' self-perceived general or mental health. The IVI-VLV can be used as an outcome measure in trials attempting sight restoration., (Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.)

Purpose: To compare self-assessed driving habits and skills of licensed drivers with central visual loss who use bioptic telescopes to those of age-matched normally sighted drivers, and to examine the association between bioptic drivers' impressions of the quality of their driving and ratings by a "backseat" evaluator., Methods: Participants were licensed bioptic drivers (n = 23) and age-matched normally sighted drivers (n = 23). A questionnaire was administered addressing driving difficulty, space, quality, exposure, and, for bioptic drivers, whether the telescope was helpful in on-road situations. Visual acuity and contrast sensitivity were assessed. Information on ocular diagnosis, telescope characteristics, and bioptic driving experience was collected from the medical record or in interview. On-road driving performance in regular traffic conditions was rated independently by two evaluators., Results: Like normally sighted drivers, bioptic drivers reported no or little difficulty in many driving situations (e.g., left turns, rush hour), but reported more difficulty under poor visibility conditions and in unfamiliar areas (P < 0.05). Driving exposure was reduced in bioptic drivers (driving 250 miles per week on average vs. 410 miles per week for normally sighted drivers, P = 0.02), but driving space was similar to that of normally sighted drivers (P = 0.29). All but one bioptic driver used the telescope in at least one driving task, and 56% used the telescope in three or more tasks. Bioptic drivers' judgments about the quality of their driving were very similar to backseat evaluators' ratings., Conclusions: Bioptic drivers show insight into the overall quality of their driving and areas in which they experience driving difficulty. They report using the bioptic telescope while driving, contrary to previous claims that it is primarily used to pass the vision screening test at licensure.

When considering the burden of visual impairment on aging individuals and society at large, it is important to bear in mind that vision changes are a natural aspect of aging. In this article, we consider vision changes that are part of normal aging, the prevalence of abnormal vision changes caused by disorders of the visual system, and the anticipated incidence and impact of visual impairment as the US population ages. We then discuss the services available to reduce the impact of vision loss, and the extent to which those services can and should be improved, not only to be better prepared for the anticipated increase in low vision over the coming decades, but also to increase the awareness of interactions between visual impairment and comorbidities that are common among the elderly. Finally, we consider how to promote improved quality, availability, and acceptance of low vision care to lessen the impact of visual impairment on individuals, and its burden on society.

Purpose: To compare the on-road driving performance of visually impaired drivers using bioptic telescopes with age-matched controls., Methods: Participants included 23 persons (mean age = 33 ± 12 years) with visual acuity of 20/63 to 20/200 who were legally licensed to drive through a state bioptic driving program, and 23 visually normal age-matched controls (mean age = 33 ± 12 years). On-road driving was assessed in an instrumented dual-brake vehicle along 14.6 miles of city, suburban, and controlled-access highways. Two backseat evaluators independently rated driving performance using a standardized scoring system. Vehicle control was assessed through vehicle instrumentation and video recordings used to evaluate head movements, lane-keeping, pedestrian detection, and frequency of bioptic telescope use., Results: Ninety-six percent (22/23) of bioptic drivers and 100% (23/23) of controls were rated as safe to drive by the evaluators. There were no group differences for pedestrian detection, or ratings for scanning, speed, gap judgments, braking, indicator use, or obeying signs/signals. Bioptic drivers received worse ratings than controls for lane position and steering steadiness and had lower rates of correct sign and traffic signal recognition. Bioptic drivers made significantly more right head movements, drove more often over the right-hand lane marking, and exhibited more sudden braking than controls., Conclusions: Drivers with central vision loss who are licensed to drive through a bioptic driving program can display proficient on-road driving skills. This raises questions regarding the validity of denying such drivers a license without the opportunity to train with a bioptic telescope and undergo on-road evaluation.

Purpose: To determine the relationship between refractive error as measured by autorefraction and that measured by trial frame refraction among a sample of adults with vision impairment seen in a university-based low-vision clinic and to determine if autorefraction might be a suitable replacement for trial frame refraction., Methods: A retrospective chart review of all new patients 19 years or older seen over an 18-month period was conducted and the following data collected: age, sex, primary ocular diagnosis, entering distance visual acuity, habitual correction, trial frame refraction, autorefraction, and distance visual acuity measured after trial frame refraction. Trial frame refraction and autorefraction were compared using paired t-tests, intraclass correlations, and Bland-Altman plots., Results: Final analyses included 440 patients for whom both trial frame refraction and autorefraction data were available for the better eye. Participants were mostly female (59%) with a mean age of 68 years (SD = 20). Age-related macular degeneration was the most common etiology for vision impairment (44%). Values for autorefraction and trial frame refraction were statistically different, but highly correlated for the spherical equivalent power (r = 0.92), the cylinder power (r = 0.80) and overall blurring strength (0.89). Although the values of the cross-cylinders J(0) and J(45) were similar, they were poorly correlated (0.08 and 0.15, respectively). The range of differences in spherical equivalent power was large (-8.6 to 4.9)., Conclusions: Autorefraction is highly correlated with trial frame refraction. Differences are sometimes substantial, making autorefraction an unsuitable substitute for trial frame refraction.

Purpose: Quality of life (QoL) questionnaires have been suggested as the most appropriate way to measure the effectiveness of low vision rehabilitation. This study investigated the relative contribution of visual and psychosocial factors to different aspects of QoL in people with low vision., Methods: A total of 448 consecutive patients between the ages of 18 and 96 years, with best-corrected binocular visual acuity≤6/18 and attending a low vision clinic, were recruited. Telephone delivery of previously validated questionnaires was used. The Low Vision Quality of Life (LVQOL), the Adaptation to Age-Related Vision Loss (AVL)-12, and the Keele Participation Restriction Questionnaire (KAP) questionnaires were considered as outcome measures for functional vision, adaptation to vision loss, and participation restriction, respectively. Personality (BFI-10), religious beliefs (SBI-15), social support (MOS), the mental and physical components of general health (the MCS and PCS of SF-12), well-being (WHO-5), use of magnifiers (MLVQ), understanding of their eye condition and satisfaction with the eye clinic (MLVQ), level of education, and financial status were all considered as predictive of QoL., Results: Regression analysis found the PCS and MCS from SF-12 to be major predictors of LVQOL, AVL-12, and KAP scores. Although distance visual acuity and contrast sensitivity were predictors of LVQOL scores, "use of magnifiers" did not contribute to any of the QoL measures., Conclusions: Nonvisual factors, such as physical and mental health, were found to be stronger predictors of QoL in people with low vision than visual factors such as contrast sensitivity and visual acuity, or the use of magnifiers. Researchers need to be aware when measuring QoL in a population with low vision that even vision-related QoL is strongly influenced by nonvisual variables.

Purpose: In addition to performance-based measures, vision-related quality of life (QOL) and other subjective measures of psychosocial functioning are considered important outcomes of training in the visually impaired. In a multicenter, masked, randomized controlled trial, subjective effects of training in the use of closed-circuit televisions (CCTV) were investigated., Methods: Patients (n = 122) were randomized either to a treatment group that received usual delivery instructions from the supplier combined with concise outpatient training, or to a control group that received delivery instructions only. Subjective outcomes were the low vision quality-of-life questionnaire (LVQOL), EuroQOL 5 dimensions, adaptation to age-related vision loss (AVL), and the Center of Epidemiologic Studies Depression scales. Linear mixed models were used to investigate treatment effects. Differential effects of patient characteristics were studied by implementing higher order interactions into the models., Results: From baseline to follow-up, all patients perceived significantly less problems on the reading and fine work dimension (-28.8 points; P < 0.001) and the adaptation dimension (-4.67 points; P = 0.04) of the LVQOL. However, no treatment effect was found based on the intention-to-treat analysis., Conclusions: This study demonstrated the effect of receiving and using a CCTV on two vision-related QOL dimensions; however, outpatient training in the use of CCTVs had no additional value. (trialregister.nl number, NTR1031.).

Purpose: To investigate the effectiveness of training in the use of closed-circuit television (CCTV) on reading performance in visually impaired patients., Methods: In a multicenter masked randomized controlled trial, 122 patients were randomized either to a treatment group that received usual delivery instructions from the CCTV supplier combined with concise outpatient standardized training, or to a control group that received delivery instructions only. The main outcome measure was reading performance, which was obtained by measuring reading acuity, reading speed, reading errors, column-tracking time, and technical reading, approximately two weeks after patients had received their CCTV and 3 months later. Videotapes of all measurements were rated by two investigators. Training effects were analyzed with linear mixed modeling., Results: There were no statistically significant differences in results between the treatment and control group. However, introducing a CCTV increased reading acuity (mean difference [MD] 0.93 logRAD; P < 0.01) and maximum reading speed (MD 15 wpm; P < 0.01), and decreased the number of errors (MD 0.33; P = 0.04), compared to reading without CCTV. Average reading speed (P = 0.05), number of errors (P = 0.04), and column-tracking time (P = 0.01) improved over time., Conclusions: Prescribing a CCTV and the delivery instructions by the supplier seemed sufficient to improve reading performance. Additional training in the use of this device did not result in further improvement. Based on these results, outpatient low-vision rehabilitation centers may consider reallocating part of the training resources into other evidence-based rehabilitation programs. (trialregister.nl number, NTR1031.).

Purpose: One objective of the Montreal Barriers Study was to examine demographic characteristics of people with vision impairment that may hinder their referral or decision to access rehabilitation services., Methods: Data collection was conducted in three phases, whereby during phase I, patients in ophthalmology department waiting rooms underwent a structured interview to ascertain demographic variables that may be related to their utilization of the rehabilitation process. Phase II examined variables recorded in the rehabilitation agency file of those who had made the choice to access services. Phase III examined the rehabilitation access behavior of those participants who were referred as part of phase I., Results: In phase I, 54% of the 702 participants had been referred to and received rehabilitation services. An additional 13% were aware of these services but chose not to access them, whereas 33% were unaware of their existence. The variables associated with positive access choice were education, diagnosis, race, acuity at the time of interview, and living situation. In phase II, it was found that acuity at agency intake was markedly better than at the study interview. Of the participants who were referred to rehabilitation services as part of the phase I protocol, it was found in phase III that only 56% had engaged in rehabilitation services., Conclusions: It seems that even under ideal referral situations, there remain barriers to vision rehabilitation services that have not been specifically identified in the present study. Further research is necessary on the psychological and psychosocial contributors to this process.

Purpose: To evaluate the validity, reliability, and measurement characteristics of the Visual Function 14 (VF-14) in a German sample using Rasch analysis., Methods: This was a clinic-based, cross-sectional study with 184 patients with low vision recruited from an outpatient clinic at a German eye hospital. Participants underwent a clinical examination and completed the German VF-14 scale. The validity of the VF-14 scale was assessed using Rasch analysis. The main outcome measure was the overall functional score provided by the VF-14., Results: After collapsing two response categories for items 13 and 14, the VF-14 scale satisfied fundamental criteria to achieve fit to the Rasch model, namely, ordered thresholds, the ability to distinguish between different strata of participant ability, absence of misfitting items, no evidence of unidimensionality, and no significant differential item functioning for key sociodemographic covariates. The VF-14 is able to discriminate between participants with different levels of vision impairment and across different cultural groups., Conclusions: The VF-14 is a valid, reliable, and unidimensional questionnaire for use in a German population. These findings contribute to the growing evidence base for second generation patient reported outcome measures in ophthalmology, and support the use of the German VF-14 in tertiary eye clinics in Germany to capture the impact of visual impairment on visual function from the patient's perspective and to inform low vision rehabilitation and interventions.

Purpose: The use of patient-reported outcome (PRO) measures to assess self-reported difficulty in visual activities is common in patients with impaired vision. This study determines the visual and psychosocial factors influencing patients' responses to self-report measures, to aid in understanding what is being measured., Methods: One hundred visually impaired participants completed the Activity Inventory (AI), which assesses self-reported, vision-related activity limitation (VRAL) in the task domains of reading, mobility, visual information, and visual motor tasks. Participants also completed clinical tests of visual function (distance visual acuity and near reading performance both with and without low vision aids [LVAs], contrast sensitivity, visual fields, and depth discrimination), and questionnaires assessing depressive symptoms, social support, adjustment to visual loss, and personality., Results: Multiple regression analyses identified that an acuity measure (distance or near), and, to a lesser extent, near reading performance without LVAs, visual fields, and contrast sensitivity best explained self-reported VRAL (28%-50% variance explained). Significant psychosocial correlates were depression and adjustment, explaining an additional 6% to 19% unique variance. Dependent on task domain, the parameters assessed explained 59% to 71% of the variance in self-reported VRAL., Conclusions: Visual function, most notably acuity without LVAs, is the best predictor of self-reported VRAL assessed by the AI. Depression and adjustment to visual loss also significantly influence self-reported VRAL, largely independent of the severity of visual loss and most notably in the less vision-specific tasks. The results suggest that rehabilitation strategies addressing depression and adjustment could improve perceived visual disability.

Purpose: To identify the critical success factors (CSF) associated with coverage of low vision services., Methods: Data were collected from a survey distributed to Vision 2020 contacts, government, and non-government organizations (NGOs) in 195 countries. The Classification and Regression Tree Analysis (CART) was used to identify the critical success factors of low vision service coverage. Independent variables were sourced from the survey: policies, epidemiology, provision of services, equipment and infrastructure, barriers to services, human resources, and monitoring and evaluation. Socioeconomic and demographic independent variables: health expenditure, population statistics, development status, and human resources in general, were sourced from the World Health Organization (WHO), World Bank, and the United Nations (UN)., Results: The findings identified that having >50% of children obtaining devices when prescribed (χ(2) = 44; P < 0.000), multidisciplinary care (χ(2) = 14.54; P = 0.002), >3 rehabilitation workers per 10 million of population (χ(2) = 4.50; P = 0.034), higher percentage of population urbanized (χ(2) = 14.54; P = 0.002), a level of private investment (χ(2) = 14.55; P = 0.015), and being fully funded by government (χ(2) = 6.02; P = 0.014), are critical success factors associated with coverage of low vision services., Conclusions: This study identified the most important predictors for countries with better low vision coverage. The CART is a useful and suitable methodology in survey research and is a novel way to simplify a complex global public health issue in eye care.

Purpose: Perceptual learning has been shown to be effective in improving visual functions in the normal adult visual system, as well as in adults with amblyopia. In this study, the feasibility of applying perceptual learning to enhance reading speed in people with long-standing central vision loss was evaluated., Methods: Six observers (mean age, 73.8) with long-standing central vision loss practiced an oral sentence-reading task, with words presented sequentially using rapid serial visual presentation (RSVP). A pre-test consisted of measurements of visual acuities, RSVP reading speeds for six print sizes, the location of the preferred retinal locus for fixation (fPRL), and fixation stability. Training consisted of six weekly sessions of RSVP reading, with 300 sentences presented per session. A post-test, identical with the pre-test, followed the training., Results: All observers showed improved RSVP reading speed after training. The improvement averaged 53% (range, 34-70%). Comparisons of pre- and post-test measurements revealed little changes in visual acuity, critical print size, location of the fPRL, and fixation stability., Conclusions: The specificity of the learning effect, and the lack of changes to the fPRL location and fixation stability suggest that the improvements are not due to observers adopting a retinal location with better visual capability, or an improvement in fixation. Rather, the improvements are likely to represent genuine plasticity of the visual system despite the older ages of the observers, coupled with long-standing sensory deficits. Perceptual learning might be an effective way of enhancing visual performance for people with central vision loss.

Purpose: To validate estimates of self-perceived driving ability from difficulty ratings of driving tasks and to determine the association of the importance and difficulty of driving with the magnitude of visual impairments., Methods: A consecutive series of 851 patients at a low-vision clinic rated the importance of driving on a four-point scale. Those who gave nonzero importance ratings then rated driving difficulty on a five-point scale. Those who gave nonzero difficulty ratings then rated the difficulty of each of 21 driving tasks on a five-point scale. Visual acuity was measured with the Early Treatment of Diabetic Retinopathy Study (ETDRS) chart, and contrast sensitivity was measured with the Pelli-Robson chart. Rasch analysis was used to test the validity and reliability of self-perceived driving ability estimates from difficulty ratings of tasks., Results: Patients who rated driving as not important (41%) had worse visual acuity (logMAR = 0.88) and worse contrast sensitivity (log CS = 0.83) than did those who rated driving as extremely important (55%; logMAR = 0.62; log CS =1.03; multivariate analysis of variance [MANOVA]; P = 0.003). Self-perceived driving ability correlated negatively with the overall rating of driving difficulty (r = -0.69; P < 0.001) and with logMAR (r = -0.28; P < 0.001), and correlated positively with log CS (r = 0.35; P < 0.001). The most difficult driving tasks were navigating in parking ramps, parking in the correct space, seeing lane markings, and reading signs. The least-difficult driving tasks were seeing traffic and reading the speedometer. Rasch analysis confirmed instrument validity and reliability., Conclusions: Low-vision patients appeared to devalue the goal of driving when visual impairments were more severe. Valid measures of self-perceived driving ability can be estimated from difficulty ratings of specific driving tasks.

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.

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.

Purpose: To explore the psychometric properties of the Impact of Vision Impairment scale (IVI) by using Rasch analysis., Methods: Three hundred fourteen first-time referrals to low-vision clinics completed the 32-item IVI. The data were Rasch-analyzed with a partial credit model using RUMM2020 software (RUMM Laboratory, Perth, WA, Australia). The overall fit of the model, response scale, individual item fit, differential item functioning, unidimensionality, and person-separation reliability were assessed., Results: Initially, 26 items displayed disordered thresholds. However, collapsing the response scale to three categories (4 items) and four categories (28 items) produced ordered response thresholds for all items. Four items with high proportions of missing responses, poor spread, high skewness, and deviation between observed and expected model curves were then removed. This adjustment produced overall fit to the Rasch model (item-trait interaction chi(2) = 118.3; P = 0.32). The final mean (SD) person and item fit residuals ere 0.06 (0.85) and -0.20 (1.45), respectively. The person-separation reliability was 0.9, indicating that the scale was able to discriminate between several different groups of participants. The revised scale was well targeted to the participants, with similar mean locations for items (0.00) and persons (0.16). A significant difference between participants of mild, moderate, and severe visual impairment (ANOVA; P 0.001) supported the criterion validity of the Rasch-scaled IVI., Conclusions: The results provide support for the measurement properties of the Rasch-scaled 28-item version of the IVI and of its potential for assessing outcomes of low-vision rehabilitation. A raw score-to-Rasch person measure conversion is supplied.

Purpose: To evaluate the sensitivity to change, in patients who undergo vision rehabilitation, of the Veteran Affairs (VA) Low Vision Visual Functioning Questionnaire (LV VFQ-48), which was designed to measure the difficulty visually impaired persons have in performing daily activities and to evaluate vision rehabilitation outcomes., Methods: Before and after rehabilitation, the VA LV VFQ-48 was administered by telephone interview to subjects from five sites in the VA and private sector. Visual acuity of these subjects ranged from near normal to total blindness., Results: The VA LV VFQ exhibited significant differential item functioning (DIF) for 7 of 48 items (two mobility tasks, four reading tasks, and one distance-vision task). However, the DIF was small relative to baseline changes in item difficulty for all items. Therefore, the data were reanalyzed with the constraint that item difficulties do not change with rehabilitation, which assigns all changes to the person measure. Subjects in the inpatient Blind Rehabilitation Center (BRC) program showed the largest changes in person measures after vision rehabilitation (effect size = 1.9; t-test P < 0.0001). The subjects in the outpatient programs exhibited smaller changes in person measures after rehabilitation (effect size = 0.29; t-test P < 0.01). There was no significant change in person measures for the control group (test-retest before rehabilitation)., Conclusions: In addition to being a valid and reliable measure of visual ability, the VA LV VFQ-48 is a sensitive measure of changes that occur in visual ability as a result of vision rehabilitation. Patients' self-reports of the difficulty they experience performing daily activities measured with this instrument can be used to compute a single number, the person measure that can serve as an outcome measure in clinical studies. The VA LV VFQ-48 can be used to compare programs that offer different levels of intervention and serve patients across the continuum of vision loss.

Purpose: Visually impaired people are permitted to use bioptic telescopes for driving in many states in the United States. However, it has been suggested that the telescope is used only to meet the visual acuity criteria for licensure. In this study, a survey was used to establish the extent to which bioptic telescopes are used by and meet the driving needs of people with moderately reduced visual acuity., Methods: A cross-sectional survey of a convenience sample of 58 bioptic drivers was administered by telephone interview. Bioptic telescope usage patterns were quantified with questions designed specifically for the study. Driving patterns were quantified by use of the Driving Habits Questionnaire. Subjects were recruited from four sources across the United States to ensure a range of bioptic training and driving experience., Results: The majority (74%) rated the bioptic telescope as very helpful, and almost all (90%) would continue to use it for driving, even if it were not required for driving licensure; however, only 62% reported always wearing the bioptic when driving. Subjects had relatively unrestricted driving habits, driving a mean of 222 +/- 211 miles per week, and 85% aged < or =65 years drove to work. With the exception of driving in rain, in bright sunlight, and at night, there was little difficulty with driving in a variety of situations, and levels of driving avoidance due to vision impairment were low (<10%)., Conclusions: The bioptic telescope met the (self-reported) driving needs of the majority of visually impaired drivers in this survey and was found to be a useful aid for tasks requiring resolution of detail.

Purpose: To describe psychometric properties of a self-report questionnaire, the Veterans Affairs (VA) Low-Vision Visual Functioning Questionnaire (LV VFQ-48), which was designed to measure the difficulty visually impaired persons have performing daily activities and to evaluate low-vision outcomes., Methods: The VA LV VFQ-48 was administered by telephone interview to subjects with visual acuity ranging from near normal to total blindness at five sites in the VA and private sector. Rasch analysis with the Andrich rating scale model was applied to difficulty ratings from 367 subjects, to evaluate measurement properties of the instrument., Results: High intercenter correlations for item measure estimates (intraclass correlation coefficient [ICC]=0.97) justified pooling the data from these sites. The person measure fit statistics (mean square residuals) confirm that the data fit the assumptions of the model. The item measure fit statistics indicate that responses to 19% of the items were confounded by factors other than visual ability. The separation reliabilities for pooled data (0.94 for persons and 0.98 for items) demonstrate that the estimated measures discriminate persons and items well along the visual ability dimension. ICCs for test-retest data (0.98 for items and 0.84 for persons) confirm temporal stability. Subjects used the rating categories in the same way at all five centers. Ratings of slight and moderate difficulty were used interchangeably, suggesting that the instrument could be modified to a 4-point scale including not difficult, slightly/moderately difficult, extremely difficult, and impossible. Fifty additional subjects were administered the questionnaire with a 4-point scale to confirm that the scale was used in the same way when there were four rather than five difficulty ratings., Conclusions: The VA LV VFQ-48 is valid and reliable and has the range and precision necessary to measure visual ability of low-vision patients with moderate to severe vision loss across diverse clinical settings.

Purpose: To evaluate the sensitivity of the National Eye Institute Visual Functioning Questionnaire-25 (NEI VFQ-25) to change in visual abilities after low-vision rehabilitation in two different Veterans Administration (VA) low-vision programs, Methods: Seventy-seven legally blind veterans from the Blind Rehabilitation Center (BRC) at Hines VA Hospital and 51 partially sighted veterans from the Visual Impairment Center to Optimize Remaining Sight (VICTORS) program at the Chicago Health Care Network, West Side Division, were administered the NEI VFQ-25 plus supplement in interview format at admission and discharge. Instructions for administration were modified to have study participants answer all the questions as if they were wearing glasses or contact lenses or were using low-vision devices. Interval measures of person ability and item difficulty were estimated from the patients' responses to 34 of the 39 items on the VFQ-25 plus supplement before and after rehabilitation, by the polytomous rating scale measurement model of Wright and Masters., Results: In VICTORS patients, item order by difficulty before rehabilitation agreed with item order for BRC patients. Visual ability scales are used similarly by different patients with different degrees of low vision. Based on prerehabilitation person measure distributions, VICTORS patients were less disabled, as would be predicted by visual acuity, than were BRC patients. After rehabilitation, estimated item difficulty for 4 of the 34 items decreased significantly in both BRC and VICTORS patients., Conclusions: The present study demonstrates that the NEI VFQ-25 plus supplement can be used to measure the effects of low-vision rehabilitation; however, only 7 of the 34 items tested are sensitive to change after rehabilitation. Targeted activities, such as reading ordinary print, small print, and street signs are easier to perform for graduates of both programs after rehabilitation. The patients' visual ability also shows improvement in both BRC and VICTORS. Improvement in visual ability is independent of change in difficulty of targeted items. Although this was not a controlled clinical trial, the decrease in difficulty of targeted items may reflect the use of low-vision aids and training to make tasks easier. The change in visual ability may reflect positive outcomes of rehabilitation or may be the consequence of patients' overestimates of their functional ability at the time of discharge.

Purpose: To assess the performance of two approaches to visual acuity testing in a group of nursing home residents with cognitive impairment. The study was a cross-sectional comparison of the effectiveness of two tests of visual acuity., Methods: Nursing home residents participating in a clinical trial were tested with both recognition acuity charts and grating acuity cards (Teller) by masked observers., Results: Of the nursing home residents (n = 656) who participated in the study, 86% could respond to visual acuity testing in at least one eye. Eighty-four percent were testable using Teller cards versus 73% who were testable by Early-Treatment Diabetic Retinopathy Study (ETDRS) charts or Lea symbol charts. Forty-one percent of individuals with MiniMental Status Examination (MMSE) scores lower than 10 were testable by recognition acuity, whereas 61% were testable with grating acuity cards. Grating acuity correlated well with recognition acuity (R = 0.79; 95% CI, 0.75-0.98, intraclass correlation coefficient [ICC]). The correlation was slightly lower in individuals with decreased MMSE scores. Although grating acuity was one line better than recognition acuity on average and median acuities were the same, 24% of individuals had results that differed by three or more lines., Conclusions: Teller acuity cards can effectively test the vision in cognitively impaired individuals who are not testable by conventional means. Grating acuity results correlated well with those of recognition acuity, although differences of three or more lines were not uncommon. Wider use of grating acuity testing allows a more complete assessment of visual function in the cognitively impaired elderly.

Purpose: To develop a new test of activities of daily living (ADLs) appropriate for the low-vision population: the Melbourne Low-Vision ADL Index (MLVAI)., Methods: The MLVAI was designed as a desk-based clinical assessment, comprising 18 observed items on complex ADLs in part (a) and 9 questions on broad self-care ADLs in part (b). Each item was rated on a five-level descriptive scale from 0 to 4, based on independence, speed, and accuracy of performance. It was designed to be administered under standardized conditions with regard to the instructions, illumination, and working distances. The validity and reliability of the new MLVAI was determined for 122 subjects who were representative of the general low-vision population, in a cross-sectional study., Results: Two items were found to be redundant and were eliminated from the test. Thus, the final test comprised 25 items, with 100 being the highest possible score. Cronbach's alpha indicated an internal reliability of 0.96, and an intraclass correlation coefficient indicated an overall reliability of 0.95. The SE of measurement was 4.5. According to Spearman's correlation coefficient, the test-retest reliability was 0.94 (P < 0.001), and the interpractitioner reliability for five different pairs of practitioners was 0.90 or higher (P < 0.001). With regard to validity, there was a moderately high correlation with vision impairment (r = -0.68, P < 0.001). Using Rasch analysis, content validity was also demonstrated by good separation indexes (4.70 and 9.88) and high reliability scores (0.96 and 0.99) for the person and items parameters, respectively. Separate calculation of indexes and reliability scores for parts (a) and (b) indicated high content validity and reliability of each part. However, the separation indexes and reliability scores were higher for part (a) than for part (b). The correlation coefficient for part (a) and part (b) was 0.68., Conclusions: The MLVAI is a highly valid and reliable standardized test of ADL performance for the general low-vision population. It may be used to assess patients with low vision and has the potential to be used as a measure of low-vision rehabilitation outcomes.

Telescopic spectacles can theoretically improve function of low vision patients by enlarging retinal images. However, unintended head movement may produce sufficient instability of enlarged retinal images to negate the visual benefit. We investigated this phenomenon as a cause of failure in 38 low vision patients who had previously attempted use of telescopic spectacles. Patients underwent evaluation of the vestibulo-ocular reflex, visual-vestibulo-ocular reflex, head stability in the pitch and yaw axes, and sensitivity of magnified visual acuity to head motion. Although it was impossible to distinguish successful from unsuccessful telescopic spectacle users by means of clinical or historical data, multiple logistic regression analysis was used to derive a useful predictive function based on measurements of sensitivity of magnified vision to head motion, and head instability in the pitch axis. Predictive performance was found to be superior to conventional clinical judgement. These findings support the hypothesis that retinal image stability is important to functional vision, and suggest that head-stabilizing strategies may improve function with telescopic spectacles in certain low vision patients.