Changing the color of your eyes is very quick using Photoshop and this handy video. After using the selection tool of your choice to outline the eye (this video uses the pen tool) with a little bit of feathering, just change the hue of the eye. The video shows how to do this by pressing control + h, however it can also be selected by choosing the image menu, then adjustments, then hue/saturation. This great effect can be used as shown on close up eyes or on smaller eyes further away. Both ways will come out looking very natural and different.