Hyperosmolarity of the tear flim means that there is more salt in the tear film than normal. There seems to be a connection with higher than normal salt content and dry eye. Dr Eric Donnenfeld, a world renown corneal specialist recently presented a study of over 1000 confirmed dry eye patients that showed that this group had significantly saltier tear film than a group that did not have dry eye. CLICK HERE for more information.
This then implies that by measuring the salt content of the tear film or its osmolarity, one should be able to diagnose dry eyes more accurately. The instrument of choice seems to be one called TearLab® Osmolarity System.
Even though the data presented seems compelling I (Dr Jim Kokkinakis) was lucky enough to be present at an excellent presentation last year at The International Society of Contact Lens Specialists in Spain where Dr William Benjamin presented his own studies using the TearLab®. It seems that the overlap between dry eye and normal patients using osmolarity as a measure was vague.
In September 2012 The International Society of Contact Lens Specialists will meet again and it will be interesting to see what more data Dr Benjamin has come up with.
Even though the TearLab® would be useful to have, unless it can be definitely shown to have clinical value we will refrain from using it.
The issue with Dry Eyes is the clinical signs observed by the optometrist do not necessarily match up with what the patient feels. It would be very helpful if there was a test like the TearLab® with a certainty of 99% to ®®differentiate who is normal and who definitely has dry eyes. Treatment before there were symptoms would seem to be preferable. Stay tuned for more on this topic as there seems to be momentum on osmolarity of the tear film and dry eyes.