An eye setup I worked on to use with my characters.
I haven't seen it done like this elsewhere but it made sense to me - I wanted the cornea to only cover the iris, then fade away. That way I find it easier to control the material and appearance of the sclera.
For the darkening where the sclera and iris meet I made the SSS in that area deeper (which is what seems to be happening in real life, as far as I can see on the high res close ups I referenced)
maybe a bit overdone on the blood vessels but overall a very nice looking piece of work...
wow that is amazing work !!