MUC5AC and Keratoconjunctivitis sicca: Given the overall lack of consistency within the mucin expression literature as a whole in addition to the lack of evidence supporting a clinical correlation between mucin expression and presence or absence of dry eye, concluding what, if any role(s) alteration in mucin expression plays in the pathophysiology of dry eye or the validity of targeting mucin expression as a therapeutic treatment strategy for dry eye is difficult.