The Tumbling E-test(ETDRS based) is a test of visual acuity. The results are based on the logMAR scoring metric - the Line Scoring Method. The corresponding decimal equivalent is also included. For this app, logMAR measures range from -0.2 to 0.70 and the decimal equivalent from 0.2 to 1.58. A decimal score below decimal 1.0 is considered below normal, requiring a test by an optometrist or an ophthalmologist. Less than three correct answers per line of five will end the test. If this is the case for the first line no result is calculated. How to use the app: 1. Have a helper hold the device and swipe the screen in the direction you are pointing. 2. At a distance of 3 metres to the screen, ask your helper to start the test when seated and ready. Take your time. 3. Add a photo of the tested eye(s). 4. Share your result with your optometrist or ophthalmologist.