OPN4 and myeloid sarcoma: Specifically, recent optical coherence tomography (OCT) examinations revealed structural abnormalities in the RCG layer in either condition,6,12,17 and in MS, this was indeed shown to be associated with a deficient melanopsin-mediated pupillary response.12 Whether this functional–neuropathological relation also prevails in CIDP could be a promising research question for future studies on the pathological overlap between CIDP and MS at the border zone between PNS and CNS.