Diagnostic Accuracy of Online Visual Acuity Testing of Paediatric Patients.

BACKGROUND/OBJECTIVES: Remote assessment of children's visual acuity became necessary during the COVID-19 pandemic. This study aimed to assess the extent of agreement between hospital-based clinical testing and clinician-led home-based testing.

SUBJECTS/METHODS: 50 children aged 2-16 (median 8) years attending hospital eye services at two UK hospitals had routine hospital-based acuities compared with subsequent online, orthoptist-supervised home visual acuities. Agreement was assessed using intra-class correlation and Bland-Altman plots, as was test-retest (TRT) agreement of two, repeated home acuity tests.

RESULTS: Monocular acuities tested at hospital and at home were obtained from all 50 children; 33 also had binocular acuities in both settings and 35 had acuities retested immediately at home. Most children were tested at home using a computer or tablet; two were tested with a smartphone. No mean test differences were found for hospital vs home testing (-0.004 (95% CI -0.06-0.05) and -0.008 (95% CI -0.04-0.03) for binocular and monocular testing, respectively). Limits of agreement (LOAs) were ±0.32 and ±0.35 logMAR for binocular and monocular testing, respectively. LOAs for inter-ocular acuity differences (hospital vs home) were -0.15-0.25 logMAR. TRT monocular acuity agreement was excellent, with an LOA of ±0.14 logMAR.

CONCLUSIONS: We found good (binocular) and excellent (monocular) agreement between hospital and home acuity testing. LOAs were in keeping with multiple changes between measures (test; setting; time; tester) and a cohort including patients as young as two years old. Even smartphone testing proved feasible. Inability of the supervising orthoptist to check test distance or device calibration/orientation was a limitation, likely contributing to the breadth of LOAs. Home vision testing is feasible and accurate, but its precision, acceptability, health economic impact and carbon impact require more attention.