This is an eyeball model reference for those who can't quite get the shape right or just forgot how it looks like. I put very little detail to the textures/material, since I am focusing on the model itself. However, I put enough work to make it look believeable. You can also change between Cycles and BI and still have the materials work. I tried to copy the materials between the two rendering engines, but I seem to have forgotten how to use the BI materials XD so I got it as close as I could :P
hope this helps you in your projects!
PS: I got the eye texture from a google search. Therefore it does not belong to me.