The Dry Eye Zone

Rebecca's Blog


Abstract: Is tear film osmolarity testing useful for more accurate diagnosis?

Anything that will help get people to an accurate diagnosis faster, seems to me like a great idea, as long as it actually does get used this way….

Here’s the idea:

  • As we know: All eye doctors get a lot of patients with typical dry eye symptoms.

  • But: Typical dry eye symptoms overlap with so many other things!

  • So: Lots of these patients will be tarred with the usual dry eye brush, right or wrong, which means they may get inappropriate treatment and not get better.

  • But now: What if you had a simple clinical test which could tell you for sure that they DON’T have dry eye? Doctors will be galvanized to look further, and patients will get an accurate diagnosis faster, right? Ta-da, enter TearLab.

I caught my skeptical half suspecting that the clinicians who have enough dry eye sophistication to use osmolarity testing are presumably also the ones with enough dry eye sophistication to look for blepharitis before pronouncing dry eye anyway. But then, what do I know. Maybe with studies like this, TearLab will seep into more mainstream eyecare practices.

The utility of a normal tear osmolarity test in patients presenting with dry eye disease like symptoms: A prospective analysis.

Cont Lens Anterior Eye. 2018 Sep 17. pii: S1367-0484(18)30006-7. doi: 10.1016/j.clae.2018.09.002. [Epub ahead of print]

Brissette AR, Drinkwater OJ, Bohm KJ, Starr CE.



To explore the diagnostic utility of normal tear osmolarity in patients with symptoms suggestive of dry eye disease (DED).


Prospective observational cohort study of 100 patients that underwent tear osmolarity testing (TearLab™) if they endorsed one or more symptoms of potential DED. Patients were included for the study if they had a normal tear osmolarity test (value <308 mOsm/L in each eye, and an inter-eye difference <8 mOsm/L). The main outcome measure was the presence of any alternate diagnosis to explain the patient's symptoms. Results were recorded and descriptive and univariate statistics were employed.


Mean tear osmolarity was 293.40 mOsms/L (±6.82), with a mean absolute difference of 2.85 mOsms/L (±1.98) between the eyes. A possible alternate diagnosis was established in 89% of patients with normal tear osmolarity testing. The most frequent diagnoses included anterior blepharitis (26%) and allergic conjunctivitis (21%).


Common symptoms of DED overlap significantly with a wide variety of other ocular surface diseases, and a normal tear osmolarity test should increase clinical suspicion for alternate causes of those symptoms. Anterior blepharitis and allergic conjunctivitis were the most common diagnoses made in symptomatic patients with normal tear osmolarity who may have otherwise been misdiagnosed and treated for DED.