I ordered these out of curiosity. I did not understand at all what they are for or how they work. But they do change the precision of my eyesight. I have one eye that is 20-20, but the other is 20-200. When I cover the good eye, the poor one, with these glasses does see more clearly. Whether these will be very useful I don't know but they are curious and strange and fun. I also ordered them for four of my grandchildren thinking they will invent something interesting to use them for.