Correlation of Tear-Film Osmolarity Measured by Electrical Impedance With Different Ocular Surface Parameters in Patients Without Dry-Eye Syndrome
Purpose
To evaluate the clinical correlation between tear film osmolarity with different objective and subjective ocular surface parameters in patients without ocular surface symptoms.
Methods
We included 304 eyes of 152 consecutive patients (18-27 yo) without ocular surface symptoms. Eighty six (57%) were males. Patients were evaluated with the ocular surface disease index, McMonnies questionnaire, Schirmer’s test with and without anesthesia and Tear Ferning Test (TFT). Patients with all previous tests within normal limits were then evaluated with tear break-up time (TBUT) and Tear Film Osmolarity (TFO) using the TearLab osmometer. Tear Film samples were measured directly from the inferior lateral tear meniscus (TFO 1) and also after collecting the tear sample using absorbing polyurethane minisponges (TFO 2).
Results
21 patients (14%) were classified without dry eye after the first group of tests. The most rigorous test found to determine the population without dry eye was the TFT (40% of patients had TFT Rolando types I or II). TFO 1 was 309.0 ± 7.48 mOsms/L (290-334 mOsms/L) and TFO 2 was 309.3 ± 9.81 mOsms/L (290-328 mOsms/L). However, no correlation was found between TFO 1 and TFO 2, nor between TFO 1/TFO 2 and any of the other ocular surface parameters tested (p > 0.05).
Conclusion
TFO in this young population without dry eye was 309.0 ± 7.48 mOsms/L. There was no correlation between TFO measured in situ with TFO measured after collecting the tear sample using absorbing polyurethane minisponges. No correlation was found between TFO and the ocular surface parameters tested in this group of patients without dry eye.