ive never approached modelling the pupil out of geometry, what i do is get a rough shape of the eye and then use a texture map to add the detail.
I then parent the object to the locator and animate that (poles facing the camera).
because if you think about it the human eye is not made up of several external pieces but one complete object (with bits and bobs on the inside) and if when you move your eyes the eyeball rotates to that angle slightly.
3D Modeler and Texture Painter (Learning)
"We have limits.... our imagination does not"
Final Year: University of Bradford (Worst place to live and study in the UK!!)