My version looks quite different at first, but the result is very similar :)

...

elif mat.Name() in ("corneaLeft", "corneaRight"):
    x, y = cycles_root.Location()
    x += nodewidth
    root_node.Delete()
    root_node = C_mix(fac=nn(poser.kNodeTypeCodeCyclesLIGHTPATH,
                             pos=(x + nodewidth, y + spacer),
                             collapse=1,
                             ),
                      nodeA=nn(poser.kNodeTypeCodeCyclesTRANSPARENTBSDF,
                               pos=(x, y + spacer * 2),
                               collapse=1,
                               ),
                      nodeB=nn(poser.kNodeTypeCodeCyclesGLASSBSDF,
                               IOR=1.35,
                               Distribution=1,
                               pos=(x, y + spacer * 3),
                               collapse=1,
                               ),
                      pos=(10, y + spacer * 2),
                      collapse=0
                      )
    cycles_root["Surface"] = root_node

...

Scaling the eyeball should do it. But maybe I use a Deformer to scale the eye. Maybe this works better than a simple morph.

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