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

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