Tear Fluid Osmolarity as a Potential Marker of Hydration Status

Abstract

T(osm) increased with dehydration and tracked alterations in P(osm) with comparable utility to USG. Measuring T(osm) using the TearLab osmolarity system may offer sports medicine practitioners, clinicians, and research investigators a practical and rapid hydration assessment technique.

Reproducibility and repeatability of the OcuSense TearLab™ osmometer

“…Another study investigated the use of OcuSense TearLab™ osmometer measurements as a potential marker of hydration status and reported statistically significant reductions in tear film osmolarity with fluid restriction [14]. The reported change was from 293 ± 9 mOsms/l to 305 ± 13 mOsms/l, which again falls within our measurement noise values and suggests that this change may not be clinically relevant.…”

Is This Elderly Patient Dehydrated? Diagnostic Accuracy of Hydration Assessment Using Physical Signs, Urine, and Saliva Markers

“…However, point of care devices that utilize nanotechnology for the assessment of saliva osmolality are under development. 40,41 For example, the osmolarity of tears can now be assessed using the principle of impedance on as little as 50 nL 42,43 Thus, this limitation should not be seen to detract from the future application of saliva osmolality to assess hydration status in clinical care. Second, with saliva sampling in a clinical population, there may be a potential confounding effect of anything which can affect saliva flow rate (eg, anticholinergic medications, or recent food/fluid consumption).…”

Assessment of thermal dehydration using the human eye: What is the potential?

“…In addition, decreases in plasma osmolality during a fluid intake trial were also reflected in decreases in Tosm providing confidence that the changes in Tosm reflect changes in hydration and not an exercise artefact (Fortes et al, 2011). A large correlation was observed between Tosm and plasma osmolality (r¼0.72, Po0.01), however the mechanism(s) for the observed association of Tosm and plasma osmolality remains to be elucidated (Fortes et al, 2011) (Fig. 2); for example, it remains a matter of contention whether tear fluid represents a direct filtrate from plasma (Ubels et al, 1994).…”

“…4) (Fortes et al, 2011). In addition, decreases in plasma osmolality during a fluid intake trial were also reflected in decreases in Tosm providing confidence that the changes in Tosm reflect changes in hydration and not an exercise artefact (Fortes et al, 2011).…”

“…tear quality, pressure) can be influenced by both volume and osmolality changes in blood (Ashkenazi et al, 1992;Gaasterland et al, 1979;Patel and Blades, 2003;Visscher and Carr, 1944), the latter of which is the current criterion measure for static hydration assessment of hypertonichypovolaemia (Cheuvront et al, 2010;Feig and McCurdy, 1977); as such, one or both hypovolaemia subtypes may be diagnosed with non-invasive human eye measures (Fortes et al, 2011;Kayikcioglu et al, 1998;Martin et al, 1999). A paucity of research exists that examines the potential for using ocular measures for hydration assessment (Fortes et al, 2011;Hunt et al, in press;Kayikcioglu et al, 1998) Therefore, the aim of this review is to discuss three ocular measurements that may have the potential for use as non-invasive hydration assessment markers, including tear fluid osmolarity (Tosm), non-invasive tear break-up time (NITBUT) and intraocular pressure (IOP).…”