With the exception of the eventual, however begrudging, acceptance of dry eye disease as a thing, the biggest paradigm shift in the dry eye world has been the acknowledgement that both tear quality and quantity matter.
Heck, according to the very latest (and best!) definition of dry eye, DEWMD (Doomed), dry eye disease (DED) is “a reduction in the quantity and/or quality of the tears leading to discomfort, visual disturbance or both.” Meibomian gland dysfunction (MGD) of almost any origin is largely the culprit when we talk about tear quality. Michael Lemp, MD, himself is on record