Tear osmolarity as a biomarker for dry eye disease severity.

PURPOSE To study the association between tear osmolarity and dry eye severity grade, based on a modified Dry Eye Workshop (DEWS) scale, and between osmolarity and the signs and symptoms that determine dry eye disease severity. METHODS Nineteen patients with dry eye disease were asked to complete an evaluation of dry eye signs and symptoms composed of the Ocular Surface Disease Index (OSDI) questionnaire, corneal staining with fluorescein, conjunctival staining with lissamine green, tear-film breakup time (TFBUT), Schirmer's test with anesthesia, and tear sample collection. Tear samples were collected in 5-microL microcapillaries. Tear osmolarity was measured in the right eye with a tear osmometer. RESULTS Tear osmolarity correlated significantly with dry eye severity grade (modified DEWS). Schirmer's test and tear osmolarity correlated significantly at r=-0.52, with Schirmer's test result, with adjustment for age, contributing significantly to the independent estimate of tear osmolarity. CONCLUSIONS Tear osmolarity correlates with dry eye severity and therefore could provide a biomarker for disease severity.