Remote web-based self-assessment of visual acuity versus ETDRS in patients with macular diseases: a method comparison study

Background Macular diseases (MD) lead to frequent clinic visits, involve time-consuming visual acuity (VA) measurements by professionals. Independent home measurements could improve efficiency. This study evaluates the agreement of a web-based test in MD compared to in-hospital measurements. Methods Adults with MD were included at the University Medical Center Utrecht in March-July 2023. Users need a phone, computer, and 3m distance. The test uses Tumbling-E and triangles as optotypes. Primary outcome is the web-based vs. ETDRS Distance Visual Acuity (DVA). Secondary outcomes were test-retest variability (TRV), near visual acuity (NVA), and the Amsler grid. Outcomes were reported in mean differences and 95% Limits of Agreement (LoA). Results 89 eyes were included. The DVA mean difference was 0.03LogMAR(1.5 letters), SD0.17, LoA - 0.31;0.36LogMAR(-15.5;18 letters), TRV had a mean difference of 0.03(1.5 letters) SD0.14. The NVA mean difference was 0.13(6.5 letter) SD0.24, positive- and negative predictive values 0.93(95%CI = 0.82;0.98) and 0.71(95%CI = 0.51;0.86) respectively. Conclusions The agreement of the DVA web-based test is on par with Snellen line assessment and subpar to ETDRS. We showed that elderly can perform this test independently at home, providing a time- and cost-saving opportunity. Developments should focus on the NVA since it can be a valuable adjunct to MD follow-up. Trial registration the Dutch Medical Ethical committee (Medisch Ethische Toetsingscommissie; METC NedMec) registration number: 22-879/DB. Approved at 27-09-2022.