Purpose:
To determine whether or not there is a correlation between tear osmolarity (TO), tear meniscus height (TMH), and subjective symptoms of dry eye disease (DED).
Methods:
Thirty-three volunteers (11 men, 22 women) were asked to categorize their ocular symptoms as either none, mild, moderate or severe dry eyes. High-resolution OCT images of the inferior tear meniscus were obtained using the anterior chamber scan on the Cirrus OCT (Zeiss Inc.). Tear meniscus height and depth were digitally quantified using PixelStick software. Tear osmolarity was obtained in each eye using an osmometer (TearLab Inc.). Two-tailed t-tests were used to compare the groups; data analysis was performed in Microsoft Excel.
Results:
For each category of patients (no DE (dry eye), mild, moderate, and severe), both their highest and lowest tear osmolarities were averaged. The same was done with their TMHs. When looking at a population of no DE, mild, moderate, or severe DE, there is an upward linear trend in tear osmolarity, and a downward linear trend in TMH (Figures 1 and 2). However, when looking at tear osmolarity measurements and the corresponding TMH of one individual, a clear relationship is not present in our study.
Conclusions:
In our sample of volunteers, preliminary data suggest that within a population, mean tear osmolarities increase with more severe symptoms, and mean TMHs decrease with more severe symptoms; both occur in a linear fashion. However, there seems to be a stronger correlation between symptoms and tear osmolarity than there is between symptoms and TMH, as indicated by R2 on figures 1 and 2. We can also conclude that tear osmolarity and tear meniscus height have an inverse relationship within a population, but either value alone is not a strong predictor of symptoms in any one patient.
Keywords: cornea: tears/tear film/dry eye