Development and Validation of a Smartphone-Based Visual Acuity Test (Vision at Home)

PURPOSE: To describe the development and validation of a smartphone-based visual acuity (VA) test called Vision at home (V@home). METHODS: Three study populations (elderly Chinese, adolescent Chinese, and Australian groups) underwent distance and near VA testing using standard Early Treatment Diabetic Retinopathy Study (ETDRS) charts and the V@home device; all VA tests used tumbling E optotypes. VA tests were repeated with one eye, selected randomly. Distance VA was measured monocularly at 2 m, and near VA was measured binocularly at 40 cm. Participants also completed a questionnaire about their satisfaction with the device. V@home VA (logMAR) was compared to VA for ETDRS charts at distance and near and test-retest reliability. RESULTS: The mean difference between V@home and ETDRS distance VA across all groups ranged from −0.010 to −0.100 logMAR. Tolerant weighted kappa (TWK) agreement ranged from substantial (0.742) in the Australian group to almost perfect (0.950) in the adolescent Chinese group. There was high agreement of V@home with near ETDRS VA across all groups, with a mean difference of −0.092 to −0.042 logMAR and a TWK of 0.736 to 0.837. Test-retest reliability was also high (difference: −0.018 to 0.026) for both distance and near VA tests (95% limits of agreement: −0.289 to 0.258 for distance and −0.235 to 0.199 for near). The majority of participants were satisfied with V@home. CONCLUSIONS: V@home could accurately and reliably measure both distance and near VA and is well accepted by participants. TRANSLATIONAL RELEVANCE: The V@home system could potentially serve as a useful tool to improve eye care accessibility, especially in underdeveloped areas with limited eye care personnel and resources.