Validity and Reliability of WHOeyes Application in Community-based Visual Acuity Screening Program

The evolution of visual acuity screening has seen a paradigm shift towards electronic charts and mobile apps for smart devices. However, these tools lack proper validation, raising significant concerns about their safety and accuracy. This study aimed at determining the validity of the WHOeyes app against the gold standard Snellen chart in community vision screening. Secondly, to evaluate the app's inter-rater reliability and its agreement with the Snellen chart in community vision screening.

A community-based analytical cross-sectional study was conducted from February to May 2024, involving participants aged 9 years and older. Visual acuity was tested using both the WHOeyes app and the Snellen chart by different examiners. Measurements were converted to the logarithm of the minimum angle of resolution (MAR) units for analysis.

The study involved 601 participants with a mean (SD) age of 42.4 (±17.9) years. The WHOeyes app showed a good range of sensitivity (66.67% to 100%), specificity (85.7% to 100%), and positive and negative predictive values between 36.3% to 100% and 69.4% to 100% at different cut-offs of 6/12, 6/18, 6/60, and beyond. Kappa value of the WHOeyes app vs. the Snellen chart showed moderate to substantial agreement, given visual impairment as a categorical outcome. Receiver operating characteristic curve (ROC) WHOeyes app demonstrated an area under the curve of 0.96 with optimal cut-offs between 6/12 and 6/18.

WHOeyes is a valid and reliable screening application that may be used to identify visual impairments among people of different ages in the community.