This application tests the Visual Acuity. It contains a build-in sequence of letters shown to the operator. The operator is instructed step by step.
The operator is instructed to read and write down what they see on changing plates - from a distance.
Finally, after the operator choses which plate (Letters size) was read with difficulty - from instructed distance. The result of his/her Visual Acuity is shown to them on a scale of 20 (100/20, ..., 40/20, or 20/20).
The test is done for both eyes meaning that the operator is shown 24 plates. The plates change every 60 seconds automatically.