Abstract: Tear osmolarity

This is the largest study of its kind by far that I recall seeing and involved many internationally known ocular surface disease figures. Very compelling argument for the use of tear osmolarity testing in diagnosing dry eye.

Tear Osmolarity in the Diagnosis and Management of Dry Eye Disease.

PURPOSE: To evaluate the use of tear osmolarity in the diagnosis of dry eye disease.

DESIGN: A prospective, observational case series to determine the clinical usefulness of tear osmolarity and commonly used objective tests to diagnose dry eye disease.

METHODS: A multicenter, 10-site study consisting of 314 consecutive subjects between 18 and 82 years of age. Bilateral tear osmolarity, tear film break-up time (TBUT), corneal staining, conjunctival staining, Schirmer test, and meibomian gland grading were performed. Diagnostic performance was measured against a composite index of objective measurements that classified subjects as having normal, mild or moderate, or severe dry eye. The main outcome measures were sensitivity, specificity, area under the receiver operating characteristic curve, and intereye variability.

RESULTS: Of the 6 tests, tear osmolarity was found to have superior diagnostic performance. The most sensitive threshold between normal and mild or moderate subjects was found to be 308 mOsms/L, whereas the most specific was found at 315 mOsms/L. At a cutoff of 312 mOsms/L, tear hyperosmolarity exhibited 73% sensitivity and 92% specificity. By contrast, the other common tests exhibited either poor sensitivity (corneal staining, 54%; conjunctival staining, 60%; meibomian gland grading, 61%) or poor specificity (tear film break-up time, 45%; Schirmer test, 51%). Tear osmolarity also had the highest area under the receiver operating characteristic curve (0.89). Intereye differences in osmolarity were found to correlate with increasing disease severity (r(2) = 0.32).

CONCLUSIONS: Tear osmolarity is the best single metric both to diagnose and classify dry eye disease. Intereye variability is a characteristic of dry eye not seen in normal subjects.

Am J Ophthalmol. 2011 Feb 8. [Epub ahead of print]
Lemp MA, Bron AJ, Baudouin C, Del Castillo JM, Geffen D, Tauber J, Foulks GN, Pepose JS, Sullivan BD.
Department of Ophthalmology, Georgetown University, Washington, DC.