Check it out in this link. The excercise looks like the image below, and you need to practice your cross eye skills. I found it super fun, it took me 20 minutes to be able to read the smallest print on the bottom, but I can see how this will be a great improvement to my eyesight.Give it a try, and post your comments letting me know how it goes! Even more importantly, have lots of fun with it!
This image is just an example, open the link to get the real excericise.