The idea of the comic EYE MatCap is very simple. Create an eye and place it in the middle of the image used by the MatCap, then apply the MatCap to a sphere and you have an eye that is always looking at the camera.
In the video below, I show you a few things you can do with this simple trick, including some fancy Keyshot comic renders!
You can also use the Hue and the Saturation slider from the material modifiers to quickly change the eye colour. The Depth A slider, lets you change the size of the iris and pupil. Here is a reference image: