April 2010
Volume 51, Issue 13
ARVO Annual Meeting Abstract  |   April 2010
Impact of Time Between Collection on Human Tear Film Fluid Osmolarity
Author Affiliations & Notes
  • A. Keech
    CCLR - School of Optometry, University of Waterloo, Waterloo, Ontario, Canada
  • M. Senchyna
    R & D, Alcon Research Ltd, Fort Worth, Texas
  • B. D. Sullivan
    TearLab Corp., San Diego, California
  • M. A. Lemp
    Ophthalmology, Georgetown and George Washington U, Washington, Dist. of Columbia
  • L. W. Jones
    CCLR - School of Optometry, University of Waterloo, Waterloo, Ontario, Canada
  • M. J. Brubaker
    R & D, Alcon Research Ltd, Fort Worth, Texas
  • Footnotes
    Commercial Relationships  A. Keech, None; M. Senchyna, Alcon Research Ltd., E; B.D. Sullivan, TearLab Corp., E; TearLab Corp., P; M.A. Lemp, TearLab Corp., I; TearLab Corp., C; L.W. Jones, TearLab Corp., F; Alcon Research Ltd., F; M.J. Brubaker, Alcon Research Ltd., E.
  • Footnotes
    Support  Alcon Research Ltd.
Investigative Ophthalmology & Visual Science April 2010, Vol.51, 4174. doi:
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      A. Keech, M. Senchyna, B. D. Sullivan, M. A. Lemp, L. W. Jones, M. J. Brubaker; Impact of Time Between Collection on Human Tear Film Fluid Osmolarity. Invest. Ophthalmol. Vis. Sci. 2010;51(13):4174.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose: : Previous research has indicated that reflex tearing may be significantly hypo-osmolar as compared to the equilibrated, basal tear film. However, neither the degree of perturbation nor the length of time required for the osmolarity of the inferior meniscus to equilibrate following reflex tearing are well characterized. The purpose of this study was to determine the relative stability of tear meniscus osmolarity during repeated tear sampling.

Methods: : Tear fluid from the inferior lateral meniscus was obtained from control (n = 10) and dry eye patients (n = 10) using the TearLabTM Osmolarity System. Dry eye was classified on symptoms only as defined by a score of >20 on the Ocular Surface Disease Index (OSDI). Four samples from each eye were collected in 15 minute and then 1 minute intervals for a total of eight tear collections per eye, per day. Each patient returned on three separate days for a total of 960 tear collections in the study.

Results: : Symptom scores and maximum per-subject osmolarity of the dry eye group {OSDI=40.0±14.8, Osmolarity=321.0±10.7 / 315.9±9.5 (1 min / 15 min intervals)} were significantly higher than controls {OSDI=7.1±4.4, Osmolarity=300.9±6.1 / 297.8±5.9 (1 min / 15 min intervals)}, with p < 0.005 for all groups. Of particular clinical interest, the standard deviation of osmolarity within each eye was significantly increased in the dry eye group as compared to controls. Within each person, no significant difference was found between the osmolarity distributions of 1 minute or 15 minute collection intervals, regardless of whether the person was classified as control or dry eye (p = 0.81/0.16 OD/OS control, p = 0.79/0.54 OD/OS dry eye).

Conclusions: : No change in osmolarity distribution was observed whether tears were collected in rapid succession or given time to equilibrate between measurements. These data suggest that reflex tearing plays less of a role in determining meniscus osmolarity than previously suspected, and that the inherent tear film instability present in dry eye disease may represent a more substantial source of variance. This effect is most likely evident in the early stage of the disease where subjects are able to transiently compensate for hyperosmolarity induced by environmental stress.

Keywords: cornea: tears/tear film/dry eye • clinical (human) or epidemiologic studies: systems/equipment/techniques 

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