I have a buddy who is blind. In the US, paper currency is all the same size and shape, so it's impossible to distinguish them by feel alone. He uses a system of folds to remember which bill is which, but if he drops one, or the cashier doesn't tell him what the denominations are, etc..., he ends up not know which bill is which. Occasionally that means he has to ask someone, despite having a 'routine' that is generally very effective.

The idea for the app came from Hans Jørgen Wiberg who himself has tunnel vision. He worked for the danish blind society, where he taught blind people to cook. One thing he often heard was "If only I could have a pair of eyes a few minutes a day..." He also knew of blind people who used facetime to connect to their loved ones. But the good thing about this concept is that you just say "Thank you" and disconnect and you are done with it, you don't owe someone a favour.