I came across an intresting method for animating Iris opening if your eye is having simple texture map for eye Iris.
Whole method is about animating UV’s over map that will give illusion of Iris getting scaled up or down.
So here we have an poly eye ball. with a image as an eye map.
Now second step would be to select the UV’s that are covering the black part. And then after selecting them just type “polyMoveUV” in command/script editor
Now we can connect scale U and scale V attribute of polyMoveUV1 node to whatever controler you wish to scale the iris.
And we are done.You can now just animate scale. Simple!
Make sure Construction history is in right order.