This procedural eye ball shader is modified from Larry Gritz's eyeball.sl and Matt Breit's eye shader. I keep the UV direction from Larry's shader and use Matt's idea for the iris and normal. Larry Gritz's original eyeball.sl can be found in the shader source if you install 3Delight renderer. I studied how they made the pattern for a eye ball and made a new version. This image is rendered by Pixie. There are some small black spots which may not happen in PRman.
Reference: