Ordering fake eyes

I'm studying for another test I have on Monday all about contact lenses and prosthetic eyes. Prosthetic eyes are actually really cool. One thing they have to consider when ordering a fake eye is his big to draw the pupil (the black part of your eye). A real pupil can change size a lot in different lighting and when you're talking or reading. The doctor will base the pupil size off of the good eye's pupil size in normal room illumination and in conversation so that the eyes will look normal when they're talking with someone. How cool is that?