If you want to know how to change the colors of the eyes in Photoshop, you’re at the right place.
This is the picture I am going to use.

To begin, open your picture in Photoshop.
Zoom-in a lot, and grab the Point to Point Selection tool and select the eyes like you can see on the picture below.

Now in your layer manager [press F7 if you don't have it] click on the effect icon which looks like this and select Color Balance

Now you have to play a little bit with the colors balances to change the colors of the eyes, those are my settings:

And this is my final result: