Comparison of Visual Acuity Measurement Using Three Methods: Standard ETDRS Chart, Near Chart and a Smartphone-Based Eye Chart Application

Purpose: To validate the Rosenbaum near vision card (Near Chart) and a smartphone-based visual acuity (VA) test (Eye Chart) against a standard retro-illuminated Early Treatment Diabetic Retinopathy Study (ETDRS) chart within participants Materials and Methods: A cross-sectional study of participants aged >=18 years was conducted VA was measured in all participants using the ETDRS chart, Near Chart and smartphone-based Eye Chart application, respectively VA was converted to logarithm of the minimum angle of resolution (logMAR) for statistical analysis Eyes with ETDRS VA worse than 1 0 logMAR (20/200) were excluded The main outcome measures were levels of agreement between VA measured using the Near Chart or Eye Chart application vs the ETDRS chart Results: A total of 295 eyes of 151 participants were included One hundred participants (66 2%) were female and the mean age was 64 3 +/- 12 5 years Educational level was high school or below for 49% of participants and at Bachelor's degree or above for 51% The median logMAR VAs of all eyes tested using the ETDRS chart, Near Chart and Eye Chart application were 0 1, 0 0 and 0 1, respectively The median VA difference between the Near Chart vs ETDRS chart and Eye Chart application vs ETDRS chart was 0 0 logMAR in both cases for both the right eye (OD) and left eye (OS) Intraclass correlation coefficient (ICC) demonstrated a strong positive correlation between VA tested with the Near Chart vs ETDRS chart (OD: ICC=0 85;p<0 001, OS: ICC=0 77;p<0 001) and Eye Chart application vs ETDRS chart (OD: ICC=0 88;p<0 001, OS: ICC=0 74;p<0 001) Conclusion: VA measurements with the Near Chart and smartphone-based Eye Chart application corresponded well to the standard ETDRS chart, suggesting potential utility of alternative portable VA tests for in-office or remote vision monitoring, particularly during periods of physical distancing such as the Coronavirus disease 2019 (COVID-19) era