In VRchat, for my own character, I created a cybernetic eye. Bunch of panel bits, and whatnot make up the actual eye texture, but one of the main things is a custom Unity shader, made using ShaderForge. The shader, creates the rather interesting holographic material on the pupils, and the shape of the pupil changes due to an assortment of blend shapes. Color & Shape can be controlled in VRchat, allowing for you to have what you please.

Blender(HighRez Eye)->SubstancePainter(Texture)->Unity(All Together)->ShaderForge(Pupil)->VRchat(Final)