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Tear osmolarity best method of diagnosing dry eye, study says
Am J Ophthalmol. 2011;151(5):792-798.
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Tear osmolarity is the best way to diagnose and classify dry eye disease, according to a study.
However, tear osmolarity "should be used in conjunction with other clinical tests, or when a conflict between signs and symptoms arise," the authors said.
The prospective, multicenter, observational case series included 314 consecutive subjects between the ages of 18 and 82 years. Subjects were examined for bilateral tear osmolarity, tear film breakup time, corneal staining, conjunctival staining, Schirmer test and meibomian gland grading. Diagnostic scores were measured against a composite index for dry eye classification.
Of the tests, tear osmolarity was found to have superior diagnostic performance, as well as the highest area under the receiver operating characteristic curve (0.89).
Researchers determined that 308 mOsm/L was the most sensitive threshold between normal and mild or moderate cases, and 315 mOsm/L was the most specific.
Tear hyperosmolarity exhibited 73% sensitivity and 92% specificity at a cutoff of 312 mOsm/L, according to the study.
Sensitivity was poor for corneal staining (54%), conjunctival staining (60%) and meibomian gland grading (61%). Specificity was poor for tear film breakup time (45%) and Schirmer test (51%).
Inter-eye differences in osmolarity correlated with increasing disease severity.