In the case of shaders, for the sclera you can simply choose a standard material or SSS if you like.
The settings for a standard material can be seen in Fig.21.
The cornea shader is the most important and there are several shaders we can choose from. But I found that a Raytrace material with the settings shown in Fig.22 worked well enough.
Apply all the maps and then you can move onto the rendering stage. I'd recommend using a powerful renderer like mental ray, with whatever settings you like. But before rendering, you'll need to create two or three area lights to mimic light shapes and reflections in the eye. Don't just use the default lights!
Once the lighting is sorted, hit "render" and enjoy the result!
My final render can be seen in Fig.23.
Thanks for your time and if you have any question, you can contact me: firstname.lastname@example.org