Development and validation of a smartphone-based visual acuity test (Vision at home)

Abstract

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.