Validity and Reliability of Vis-Screen Application: A Smartphone-Based Distance Vision Testing for Visual Impairment...

Background and Objectives: The health-related mobile applications (app) might assist in promoting inclusive health and tele-treatment, especially for the less severe diseases. In this paper, a study had been done to determine the app's reliability in terms of raters and the app's agreement with the Snellen chart. Materials and Methods: A cross-sectional sectional study was conducted between November 2019 and September 2020. Participants were selected via purposive sampling from selected communities in Terengganu state. All participants underwent vision testing with the Vis-Screen app and Snellen chart for validity and reliability accordingly. Results: A total of 408 participants were involved, with a mean age of 29.3. The sensitivity of the presenting vision of the right eye (PVR) ranged from 55.6% to 88.4%, with specificity between 94.7% to 99.3%, while the positive and negative predictive values were between 57.9% and 81.7% and 96.8% and 99.0%, respectively. The positive likelihood ratios ranged between 16.73 and 73.89, whereas the negative likelihood ratios ranged from 0.12 to 0.45. The area under the receiver operating characteristic curve (AUC) for all cut-off points ranged between 0.93 and 0.97, and the optimum cut-off point was at 6/12. The kappa values for intra-rater and inter-rater were 0.85 and 0.75, respectively, while the app's reliability with the Snellen chart was 0.61. Conclusions: Vis-Screen was concluded to be valid and reliable for use as a screening tool for detecting individuals with visual impairment and blindness in the community. A valid and reliable portable vision screener like Vis-Screen will help expand the eye care feasibility while providing similar accuracy as the conventional charts in clinical practices.