Various hypotheses have been proposed to explain the association between PD and DED, such as corneal hypoesthesia causing decreased BR and reflex lacrimation, autonomic neuropathy due to anti-dopaminergic dysregulation leading to decreased tear secretion, increased tear osmolarity, decreased tear mucin, and lipid layer disruption secondary to meibomian gland dysfunction22,26,29–32,43–46. Here, MUC5AC is linked to autonomic neuropathy.