algorithm for mobile application and perform a pilot study todetermine its validity and reliability as a tool for vision testin the community.Methods: A simple visual acuity test algorithm in the form ofa single letter E display was designed as the optotype fordevelopment of a mobile application. The standardisedoptotype is presented at random to test visual acuity forcorresponding level of 3/60, 6/60, 6/18, and 6/12. The finalresult is auto-generated based on the classification of theWHO for visual impairment and blindness. The Snellen chartwas used as the gold standard to determine its validity whilefive different users were involved to determine its inter-raterreliability. A pilot study was performed between April tillNovember 2019, in the Universiti Sultan Zainal AbidinMedical Centre (UMC) at Kuala Nerus and MoorisOptometrist Centre at Marang, Terengganu. A total of 279participants aged four years old and above were involved inthis study. Results: The highest sensitivity was found at the vision levelcut-off point of 6/12 with the percentage of 92.7% and 86.8%for the right and left eye, respectively. The specificity wasmore than 89% for all vision levels in both eyes. TheKrippendorff’s alpha value for the inter-rater reliability was0.87 and 0.83.Conclusion: The relatively high level of validity andreliability obtained indicate the feasibility of using thedesigned optotype to develop a valid and reliable mobile appfor vision test. The app can be used to screen vision by non-medical persons, at anytime and anywhere to help improvepublic awareness and capability to correctly determine theirvisual status.