Self-Reported Visual Ability Versus Task Performance in Individuals With Ultra-Low Vision

PURPOSE: Visual functioning questionnaires are commonly used as patient-reported outcome measures to estimate visual ability. Performance measures, on the other hand, provide a direct measure of visual ability. For individuals with ultra-low vision (ULV; visual acuity (VA) <20/1600), the ultra-low vision visual functioning questionnaire (ULV-VFQ) and the Wilmer VRI—a virtual reality–based performance test—estimate self-reported and actual visual ability, respectively, for activities of daily living. But how well do self-reports from ULV-VFQ predict actual task performance in the Wilmer VRI? METHODS: We administered a subset of 10 matching items from the ULV-VFQ and Wilmer VRI to 27 individuals with ULV. We estimated item measures (task difficulty) and person measures (visual ability) using Rasch analysis for ULV-VFQ and using latent variable signal detection theory for the Wilmer VRI. We then used regression analysis to compare person and item measure estimates from self-reports and task performance. RESULTS: Item and person measures were modestly correlated between the two instruments, with r(2) = 0.47 (P = 0.02) and r(2) = 0.36 (P = 0.001), demonstrating that self-reports are an imperfect predictor of task difficulty and performance. CONCLUSIONS: While self-reports impose a lower demand for equipment and personnel, actual task performance should be measured to assess visual ability in ULV. TRANSLATIONAL RELEVANCE: Visual performance measures should be the preferred outcome measure in clinical trials recruiting individuals with ULV. Virtual reality can be used to standardize tasks.