Purpose: To determine the relationships of (1) tear osmolarity (TO) levels with the severity of signs and symptoms of dry eye disease (DED) and (2) changes in TO with changes in signs and symptoms.
Methods: Patients (N = 405) with moderate to severe DED in the Dry Eye Assessment and Management (DREAM) Study were evaluated at baseline and at six and 12 months. Associations of TO with signs and symptoms were evaluated using Pearson correlation coefficient (r) and regression models.
Results: The mean (standard deviation [SD]) TO was 303 (16) mOsm/L at baseline and 303 (18) mOsm/L at both six and 12 months. TO was higher in older patients (306 mOsm/L for ≥70 years vs. 300 mOsm/L for <50 years; P = 0.01) and those with Sjögren's disease (311 vs. 302 mOsm/L; P < 0.0001). TO did not differ between patients randomized to placebo and omega-3 fatty acid supplementation. TO was weakly correlated with conjunctival (r = 0.18; P < 0.001) and corneal staining scores (r = 0.17; P < 0.001), tear film break-up time (r = 0.06; P = 0.03), and Schirmer test score (r = -0.07; P = 0.02) but not with Ocular Surface Disease Index scores (r = 0.03; P = 0.40). Changes in signs and were not significantly correlated with change in TO at six or 12 months.
Conclusions: Within DREAM, TO was weakly correlated with DED signs, explaining <5% variability in signs. Changes in tear osmolarity were not associated with changes in signs and symptoms of DED, indicating that the association may not be causal.