I did this on a whim last night, it took me two hours and I used an old photo.
I edited the original in Photoshop.
This is what it looked like!
I copied the eye and opened it in a new window, then proceeded to grab a photo of a Salvation Army shield and opened that in a separate window:
I erased everything inside the shield except for its outline. I put that over the eye and resized it until it looked okay. Using the clone tool I filled in any areas that didn't have 'eye' in them.
I edited the eye a little bit too, using burn and dodge to make the eye pop a little better.
I then edited the eye with Lens Distortion and gave it vertical distortion so that it was more angled. I dragged the eye layer into the photo above of the subject (Kim) and resized and turned it until it was where I wanted it. Then I ran Portraiture on the photo to soften the skin. I ran a B/W action and then messed with the photos cropping. I also added some texture to the photo, especially on the skin because I thought it needed something extra so that it wasn't very 'portraity' (although going back I would focus more on clearing the skin up and taking away any blemishes/shadows/lines)
This is what I got: