Measuring Tear-Film Osmolarity in Dry-Eye Disease: Review of the Literature
Purpose
To analyze the role of objectively measuring tear film osmolarity in the diagnosis of dry eye disease, based on a review of the peer-reviewed literature.
Methods
A literature search of all peer-reviewed articles associated with tear film osmolarity was conducted. Identified studies were graded into four categories: very low, low, moderate and high quality using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) as well as the University of Michigan Practice Guidelines. The grading systems evaluated study design parameters including sample size, randomization, masking, sponsorship and the presence of a control population. Studies were classified as supportive of, neutral, or negative to the objective measurement of tear film osmolarity as a helpful test in the diagnosis of dry eye disease.
Results
164 peer-reviewed study articles relevant to tear osmolarity and dry eye disease were identified. Of these, 72% indicated that tear film osmolarity was a useful diagnostic tool, while 7% suggested no utility to the test. Thirty percent of studies were rated as ‘moderate’ to ‘high’ quality based on study design. In this subgroup 73% supported the use of objective tear osmolarity measurement in dry eye diagnosis, 18% were neutral regarding the test and 10% suggested no utility.
Conclusion
Tear film osmolarity has been identified as a central mechanism related to dry eye disease by the Dry Eye Workshop (DEWS) report. Peer-reviewed literature indicates that an objective evaluation of tear film osmolarity is valuable in the diagnosis of dry eye disease.