AdrianP - it was rendered in Vray with separeted spheres for retina and eyball.
Darestudio - thank you!
torakiki - thank you!
polaroid29 - yep anatomy books and practice but if you could take some classical drawing lesson it will most critical you could do. Currently I'm taking some live draw sessions
and I must say that classical drawing education the only way to do things right 'cos you could spend years learning by yourself and get nothing or almost nothing.
Arthaven - yes and steel ass also help if you have one )