Hi all, first of all sorry for my English
This is my solution for improve the eyes material in Blender.
First of all create a vertex group for Cornea
and assign the "cornea material"
for the eye color I created a simple texture to mask the iris
and this is the material
now with the color ramp and the node "color mix - multiply" we can vary the color and brightness of the iris
some example
I hope it will help someone!
...if it's a double post, sorry ...
Ciao