Glass material is dark on cornea of eye I've tried to research this, but none of the solutions I found worked for me. I'm really just experimenting with modeling and materials, so this isn't really suppose to be anything. 

Here's the link to the .blend file: 



I'm trying to create an eye using the cycles nodes. From following tutorials, my understanding is that I should have an inner sphere with the color materials, and an outer sphere with a glass shader on it to give the eye some shininess and reflectivity. Unforturnately, the glass material looks very dark. If I pull the cornea sphere out of the socket, it looks like a perfectly decent glass ball, but when it's in the socked, it's incredibly dark. I'll attach images of the rendered version and of my nodes setup.
I had accidentally applied the glass material to the inner eye as well as the outer eye. It was dark because there was nothing for the light to bounce off. It looks much better now.