Great for what its made for
This app works great for its intended purpose: as a fast and fun screening tool. It is not meant to pick up your voice as you say the letters or go to 20/15. If you got all the way to 20/15, great! It only goes to 20/20 because 20/20 is normal. It is supposed to tell if you cant get to 20/20, not 20/15.
iTunes User X47 about
EyeChart - Vision Screening