No doubt there are some amazing occurences in the world. However, you'd have to give a few examples of beliefs which could change the color of your eyes in order to have a meaningful discussion. Otherwise it's just going to turn into "wow, it must be a miracle". Which is fun, but not very useful.
One belief that I can think of that would change your eye color, is the belief that you can go to your optician and buy some colored lenses.
