James T. Deremeik

The activity inventory: An adaptive visual function questionnaire

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 patients 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.

Clinically Meaningful Rehabilitation Outcomes of Low Vision Patients Served by Outpatient Clinical Centers

IMPORTANCEnTo facilitate comparative clinical outcome research in low vision rehabilitation, we must use patient-centered measurements that reflect clinically meaningful changes in visual ability.nnnOBJECTIVEnTo quantify the effects of currently provided low vision rehabilitation (LVR) on patients who present for outpatient LVR services in the United States.nnnDESIGN, SETTING, AND PARTICIPANTSnProspective, observational study of new patients seeking outpatient LVR services. From April 2008 through May 2011, 779 patients from 28 clinical centers in the United States were enrolled in the Low Vision Rehabilitation Outcomes Study. The Activity Inventory, a visual function questionnaire, was administered to measure overall visual ability and visual ability in 4 functional domains (reading, mobility, visual motor function, and visual information processing) at baseline and 6 to 9 months after usual LVR care. The Geriatric Depression Scale, Telephone Interview for Cognitive Status, and Medical Outcomes Study 36-Item Short-Form Health Survey physical functioning questionnaires were also administered to measure patients psychological, cognitive, and physical health states, respectively, and clinical findings of patients were provided by study centers.nnnMAIN OUTCOMES AND MEASURESnMean changes in the study population and minimum clinically important differences in the individual in overall visual ability and in visual ability in 4 functional domains as measured by the Activity Inventory.nnnRESULTSnBaseline and post-rehabilitation measures were obtained for 468 patients. Minimum clinically important differences (95% CIs) were observed in nearly half (47% [95% CI, 44%-50%]) of patients in overall visual ability. The prevalence rates of patients with minimum clinically important differences in visual ability in functional domains were reading (44% [95% CI, 42%-48%]), visual motor function (38% [95% CI, 36%-42%]), visual information processing (33% [95% CI, 31%-37%]), and mobility (27% [95% CI, 25%-31%]). The largest average effect size (Cohen du2009=u20090.87) for the population was observed in overall visual ability. Age (Pu2009=u2009.006) was an independent predictor of changes in overall visual ability, and logMAR visual acuity (Pu2009=u2009.002) was predictive of changes in visual information processing.nnnCONCLUSIONS AND RELEVANCEnForty-four to fifty percent of patients presenting for outpatient LVR show clinically meaningful differences in overall visual ability after LVR, and the average effect sizes in overall visual ability are large, close to 1 SD.

Visual ability of patients seeking outpatient low vision services in the United States.

IMPORTANCEnMost patients with low vision are elderly and have functional limitations from other health problems that could add to the functional limitations caused by their visual impairments.nnnOBJECTIVEnTo identify factors that contribute to visual ability measures in patients who present for outpatient low vision rehabilitation (LVR) services.nnnDESIGN, SETTING, AND PARTICIPANTSnAs part of a prospective, observational study of new patients seeking outpatient LVR, 779 patients from 28 clinical centers in the United States were enrolled in the Low Vision Rehabilitation Outcomes Study (LVROS) from April 25, 2008, through May 2, 2011. The Activity Inventory (AI), an adaptive visual function questionnaire, was administered to measure overall visual ability and visual ability in 4 functional domains (reading, mobility, visual motor function, and visual information processing) at baseline before LVR. The Geriatric Depression Scale, Telephone Interview for Cognitive Status, and Medical Outcomes Study 36-Item Short-Form Health Survey physical functioning questionnaires were also administered to measure patients psychological, cognitive, and physical health states, respectively.nnnMAIN OUTCOMES AND MEASURESnPredictors of visual ability and functional domains as measured by the AI.nnnRESULTSnAmong the 779 patients in the LVROS sample, the mean age was 76.4 years, 33% were male, and the median logMAR visual acuity score was 0.60 (0.40-0.90 interquartile range). Correlations were observed between logMAR visual acuity and baseline visual ability overall (ru2009=u2009-0.42) and for all functional domains. Visual acuity was the strongest predictor of visual ability (P u2009<u2009.001) and reading ability (Pu2009<u2009.001) and had a significant independent effect on the other functional domains. Physical ability was independently associated with (Pu2009<u2009.001) overall visual ability as well as mobility and visual motor function. Depression had a consistent independent effect (Pu2009<u2009.001) on overall visual ability and on all functional domains, whereas cognition had an effect on only reading and mobility (Pu2009<u2009.001).nnnCONCLUSIONS AND RELEVANCEnVisual ability is a multidimensional construct, with visual acuity, depression, physical ability, and cognition explaining more than one-third of the variance in visual ability as measured by the AI. The significant contributions of the nonvisual factors to visual ability measures and the rehabilitation potential (ie, ceiling) effects they may impose on LVR are important considerations when measuring baseline visual ability and ultimately LVR outcomes in ongoing clinical research.

Activities of Daily Living and Rehabilitation with Prosthetic Vision

Now that technology has the capability to provide ultra-low vision to individuals who are functionally blind, there is a recognized need for vision rehabilitation to become part of the process of adaptation. This chapter will present concepts of rehabilitation as they relate to prosthetic vision, describe approaches to evaluation and instruction, address issues related to measuring outcomes, and offer thoughts on the future of rehabilitation for individuals with prosthetic vision.

Visual Disability in the Elderly: Implications for Visual Rehabilitation

When visual system disorders result in bilateral visual impairments, patients have difficulty performing their customary activities and experience a diminished quality of life (West et al. 2002). Visual impairments increase patients’ risk of falling (Ivers et al. 1998), injury (Salive et al. 1994), poor general health (Crews and Campbell 2001), depression (Casten et al. 2004), and even death (Pedula et al. 2006). Activity-limiting chronic visual impairments, collectively called “low vision,” most often are caused by age-related visual system disorders, with age-related macular degeneration, glaucoma, diabetic retinopathy, and cataract leading the list (Congdon et al. 2004). Some visual system disorders, such as diabetic retinopathy, are manifestations of more general disorders that frequently produce co-disabilities. But most low vision patients are elderly, so comorbidities and co-disabilities from diseases unrelated to their visual system disorders are common (Ahmadian and Massof 2008). Thus, for a large portion of the low vision population, activity limitations from visual impairments are superimposed on and worsen activity limitations from comorbidities (Langelaan et al. 2009).