VisionC is the first ETDRS chart completely configurable to be presented at any distance from 20 cm to 400 cm (1 cm step) and for any Contrast from 0 to 100% (1% step). It is the only one that allows you to control de luminance of the background and the optotype with a low-cost external luminance meter.
The visual acuity with the ETDRS is usually measured at three distances (far, intermediate and near) but research studies sometimes differ in the specific distance for each one of the categories. With VisionC you can select the specific distance for each one of these three configurations in such a way you can rapidly access to the specific distance you desire.
The App comes with a different set of letters in order to avoid memorization. Therefore either letters for distance, intermediate and near or right, left and both eyes differ to prevent memorization.