Maintained concentration

A few years back, measurement of tear osmolarity was a concept discussed only in research laboratories. Recently, the idea of tear osmolarity as an indicator of the state of the tears, and therefore of dry More eye severity, has entered the mainstream. This is in no little part thanks to the inclusion of tear osmolarity into the latest definition of dry eye disease (DED) in the TFOS DEWS2 report which came out last year.¹ This defines dry eye disease as follows:

‘Dry eye is a multifactorial disease of the ocular surface characterised by a loss of homeostasis of the tear film, and accompanied by ocular symptoms, in which tear film instability and hyperosmolarity, ocular surface inflammation and damage, and neurosensory abnormalities play etiological roles.’