Can tear composition be tested?

[Lacrima]

I've been told I have lower than normal tear production (5mm on Schirmer's test) as well as "poor tear quality."

I was hoping to find out what part of my tear production is lacking or anomalous, but today at my appointment I asked the opthalmologist and he told me there is no way to test this.

Has anyone here heard of/ had a test to analyse their tear composition? If so, do you think it is important to find this out before getting punctal plugs (my opthalmologist has suggested one in each eye).

Thank you!

[indrep]

The tear film is actually quite complex. There was at one time(like a fairy tale-many years ago) a tear assay analysis system that several doctors tried to incorporate into their practices. Unfortunately the things it measured didn't seem to be impacted by any treatments and did not correlate with signs the doctor could see. Today the consensus is osmolarity of the tear film leads to the inflammatory response that contributes,not causes, dry eye. Keep in mind that those with systemic inflammatory disease have that inflammatory response already. There is currently one osmolarity tester being marketed to eye care practices. It does not measure the tear composition.

Imagine a bowling ball, if a drop of water lands on the bowling ball it rolls right off. The bowling ball is an "unwettable" surface, the same as an eye. So we first need a substance that will hold to the eye and then hold water on the eye. This is accomplished on the eye with the "mucin" layer. The mucin layer is formed by goblet cells in the conjuctiva(clear covering of the white part of your eye).

Now that we have something that holds water on the eye, we need water. This comes from the lacrimal glands that are located in the lids. Many things impact the ability of these glands to secrete water and produce water.

Now once water is produced and secreted there has to be an evaporation regulator. This is the oily lipid layer produced by meibomian glands in the upper and lower lids and secreted through ducts at the lid margin.

So, if any one of these components becomes disrupted, it creates a dysfunctional tear film and leads to the break down of the other components. This is ultimately why many products are needed to address the multiple issues relating to compromised tear film and ocular surface. Also, all of these components take time to heal in a healthy environment. So once the right combination is started it can take several months to crate a healthy environment and then several months for the healing to take place. Keeping in mind that if one or more of the producing glands are damaged, consistent therapy will be needed for a lifetime. This is a chronic illness that requires treatment therapy.

I hope this helps in a Cliff Notes type of way.

[eyemech]

I have recently incorporated the TearLab osmolarity test in my office. What has amazed me is that it actually gives me a number to shoot at. Schirmer is only valid when reduced. If not reduced, the patient can still have dry eye. If reduced, I still wonder if the reason it is reduced is that the cornea may have reduced sensitivity and therefore not cause reflex tearing.

[Lacrima]

Indrep: Thank you so much for taking the time to write the Cliff Notes I now have a much clearer idea about how the different tear components relate, and can see why it would be inconclusive to test the actual tears for any single deficiency...

One reason I thought this kind of test was possible, is that on the forum, I often see dry eye patients talking about having aqueous deficency, or MGD, or even both. I am wondering how these are diagnosed if not through analysis of the tears.

Eyemech: Thank you, I hadn't heard of TearLab or even the term 'osmolarity.' I will look into this more.

[Tanner]

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