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. Here, OPN4 is linked to chronic inflammatory demyelinating polyradiculoneuropathy.