My guess would be geometry also.  I've changed the eye shaders to Cycles for Superfly rendering and the same thing occurs.  The Ground area has been completely turned off so there is no influence from that.  Overhauling all the eye textures does nothing and adding an HDRI background does nothing also.  Be aware that the z position is well beyond the P12 construct equalling -1430 inches or -119 feet in comparison to -32,125 mm mentioned in the post.