What is the Value of Incorporating Tear Osmolarity Measurement in Assessing Patient Response to Therapy in Dry Eye Disease?

PURPOSE: To evaluate the correlation between changes in tear osmolarity, symptoms, and corneal fluorescein staining in patients with dry eye disease (DED). DESIGN: Retrospective, clinic-based cohort study. METHODS: In this single-institution study, we reviewed the charts of 186 patients with DED from whom we had data on tear osmolarity, symptoms, and corneal fluorescein staining from 2 separate visits. Main outcomes included the correlation of the changes between the 2 visits for tear osmolarity (Tear Lab system), symptoms (Ocular Surface Disease Index), and corneal fluorescein staining (modified Oxford scheme). For teat osmolarity and corneal fluorescein staining the scores from the eye with highest readings were analyzed. The correlations were repeated on subgroups based on proposed cutoffs for DED severity and on patients' treatment. RESULTS: We found a modest, though statistically significant, correlation between changes in. corneal fluorescein staining and symptoms of DED (R = 0.31; P < .001). However, there was no correlation between the recorded change in tear osmolarity and symptoms (R = -0.091; P = .38) or between changes in tear osmolarity and corneal fluorescein staining (R = -0.02; P = .80). This lack of correlation was consistent in all the subgroups studied. A multivariate analysis revealed that changes in corneal fluorescein staining had predictive value on symptom changes, whereas tear osmolarity changes did not. CONCLUSIONS: Changes in tear osmolarity do not correlate significantly with changes in patient symptoms or corneal fluorescein staining in dry eye disease. (C) 2014 by Elsevier Inc. All rights reserved.