Blender 3D: Designing Objects

Building the eyes' shaders in Cycles

The character's eyes are made up of two UV Spheres, the Corneas and the Eyes objects: the bigger Corneas one enveloping a smaller Eyes sphere, which in turn is made up of three parts: the eyeballs, the irises, and the pupils.

The Corneas sphere was first painted with a totally black Vertex Color layer, then painted with a white color only to the vertices corresponding to the front crystalline lens.

The Eyes sphere has three different materials assigned to the three different parts:

The Corneas object in Vertex Paint mode, the Eyes object with its three materials and the Rendered preview of the textured objects ...