Increased tear osmolarity is one of the core mechanisms of dry eye and has been considered as an important diagnostic criterion, if not"gold standard", of dry eye. However, recent studies showed the limitations of tear osmolarity measurement not only in the diagnosis, but also in the therapeutic efficacy evaluation of dry eye. The clinical significance of tear osmolarity measurement has become a hot topic of argument. Herein, we review the publications on this topic and try to find the underlying causes of such argument.