Tear Osmolarity test

[Praveen]

I read that TearLab Osmolarity System is best for dry eye diagnosis. Has anybody got this test done?

[patrick]

osmolarity

yes i had it done a while ago. the readings for both eyes were 293.
i'm not exactly sure,but those figures mean moderate dry eye i guess.
measuring the osmolarity is by far the best way to see if you have dry and till what extend.
it is more reliable than the often used schirmer test which is a notorious unreliable measuring method.
maybe there are people here who are able to tell you a little more in detail about this tool for dry eye diagnosis and how to interpret the measuring numbers.

patrick...

[Praveen]

Patrick, as far as I read about this test, I think 293 reading falls under normal category. Even after low reading if you have dryness, it puts test under some doubt.

[alisonW]

My new doc uses the Tear Lab test...

and I cut and pasted a bit from my original post about it.

"each eye is a 327 which puts me in the "moderate" dry eye category. I think he said that people who do not have dry eyes are usually under 200"

I do think that like with all such tests, a lot of the accuracy depends on the ability of the person administering it. Meaning, I do think there is a large margin of error for this as well as the Schirmer's tests. (To do the TearLab, you have to look up so they can place the device at the corner of your eye. The tech said my eyes were bone dry and she had to try a few times before she could get anything. So staring up at the flourescent lights for that long (while she was trying) ultimately gave me a bit of reflex tearing in the end and I imagine this could skew the results toward my eyes reading as more moist then they truly are.

I go back in Novemeber and am going to ask them to turn off the lights before the test to see if this makes any sort of difference.

[bdsulliv]

Normal readings with symptoms

Tear osmolarity is a powerful predictor of whether or not your treatments are properly regulating the quality of your tear film. We often see treatments capably lower tear osmolarity, with symptoms lagging behind. We don't know of any tear that completely eliminates symptoms, but if you've controlled your osmolarity you are on the right path! Stick with whatever works - it can take 3-6 months for the chronic inflammatory cells to die after you've lessened the causes of inflammation (i.e., normalized your osmolarity).

Many patients, and even doctors, are confused when you get a low osmolarity reading but still have symptoms of DED. Often times, it's because you're being treated well. Other times, we've found that people who have been diagnosed with dry eye may actually have something else entirely, with similar symptoms - things such as conjunctivochalasis, EBMD, even proprioception disparity has been suggested to produce symptoms identical to dry eye - but all these causes have different therapeutic paths. So it is important to know your osmolarity to know if you've managed your disease as best as you could.

Hyperosmolarity itself has been implicated as the central pathogenetic mechanism of dry eye. An overly salty tear has been shown to cause inflammation, cause epithelial cells to spontaneously die off, and hyperosmolarity lowers the ability of mucins and proteglycans to lubricate. So if you have dry eye and have not taken steps to lower your osmolarity, it is important to get tested and find a treatment that works to stabilize your levels. Blood osmolarity is around 290 mOsms/L, which is what tears are derived from. Since dry eye compromises the homeostasis and stability of the tears, excess evaporation kicks in and the concentration (osmolarity) increases. Normal tears are very low and very stable. Dry eye tears are both elevated and unstable, meaning the more severe eye can switch back and forth and the total concentration can fluctuate. Interestingly, a study out of Turkey showed that of all the signs of dry eye, only osmolarity was sensitive enough to precede symptomatic improvement. So if you've lowered your osmolarity, again, you're on the right path and hold onto hope!