Reproducibility and repeatability of the OcuSense TearLab™ osmometer

Cornea

Abstract

Background

Some studies report that increased tear osmolarity is a reliable indicator of dry eye syndrome (DES). The OcuSense TearLab™ osmometer requires less than a 100-nl sample of tears and provides an instant quantitative result. Our aim was to clinically evaluate this instrument in terms of its reproducibility and repeatability.

Methods

Twenty-nine participants who ranged in age from 19 to 49 years (mean ± SD: 23.3 ± 5.5 years) were recruited. Osmolarity readings were collected by two operators, in two sessions separated by 1 or 2 weeks in order to assess test reproducibility and repeatability.

Results

The coefficient of reproducibility was 39 mOsms/l; the coefficient of repeatability was 33 mOsms/l.

Conclusions

Our mean coefficient of variation over four readings for 29 subjects is 2.9%, which compares well with that reported by the manufacturer. Our results inform practitioners about the level of change over time that can be considered clinically relevant for healthy subjects. This value is 33mOsms/l; any change smaller than this could be attributed to measurement noise.

Keywords

Dry eye Osmolarity Osmometer TearLab Tears 

Notes

Acknowledgements

The authors declare no conflicts of interest.

Authorship

All named authors were involved in the conception and design of the study, interpretation of data, and revising it critically for important intellectual content. MA, HB and FE were involved with the data analysis. All named authors gave final approval of the version to be published. MA collected the data. HB, MA and FE drafted the article. FE provided training with data collection.

References

  1. 1.
    Srinivasan S, Nichols K (2009) Collecting tear osmolarity measurements in the diagnosis of dry eye. Expert Rev Ophthalmol 4:451–453CrossRefGoogle Scholar
  2. 2.
    Mathers W (2000) Why the eye becomes dry: a cornea and lacrimal gland feedback model. CLAO J 26:159–165PubMedGoogle Scholar
  3. 3.
    Nelson J, Wright J (1986) Tear film osmolarity determination: an evaluation of potential errors in measurements. Cur Eye Res 5:677–681CrossRefGoogle Scholar
  4. 4.
    Pensyl C, Benjamin W (1999) Vapor pressure osmometry: minimum sample microvolumes. Acta Ophthalmol Scand 77:27–30PubMedCrossRefGoogle Scholar
  5. 5.
    Bron A (2001) Diagnosis of dry eye. Surv Ophthalmol 45:S221–S226PubMedCrossRefGoogle Scholar
  6. 6.
    Sullivan B (2005) Clinical resorts of a first-generation lab-on-chip nanolitre tear film osmometer. Ocul Surf 3:S31CrossRefGoogle Scholar
  7. 7.
    Benelli U, Nardi M, Posarelli C, Albert T (2010) Tear osmolarity measurement using the TearlabTM Osmolarity System in the assessment of dry eye treatment effectiveness. Con Lens Anterior Eye 33:61–67CrossRefGoogle Scholar
  8. 8.
    Pederson-Bjergaard K, Smidt B (1952) Electrolytic conductivity, osmotic pressure, and hydrogenion concentration of human lachrymal fluid. Acta Derm Venereol Suppl (Stockh) 32:261–267Google Scholar
  9. 9.
    OcuSense Inc. (2008) TearLab Osmolarity test Card: Instructions for useGoogle Scholar
  10. 10.
    Uniacke N, Hill R (1970) Osmotic pressure of the tears during adaptation to contact lenses. J Am Optom Assoc 41:932–936PubMedGoogle Scholar
  11. 11.
    Gilbard J, Farris R, Santamaria J (1978) Osmolarity of tear microvolumes in keratoconjunctivitis sicca. Arch Ophthalmol 96:677–681PubMedCrossRefGoogle Scholar
  12. 12.
    Bland J, Altman D (1986) Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1:307–310PubMedCrossRefGoogle Scholar
  13. 13.
    Chen S, Chandna A, Norcia A, Pettet M, Stone D (2006) The repeatability of best corrected acuity in normal and amblyopic children 4 to 12 years of age. Invest Ophthalmol Vis Sci 47:614–619PubMedCrossRefGoogle Scholar
  14. 14.
    Fortes MB, Diment BC, Di Felice U, Gunn AE, Kendall JL, Esmaeelpour M, Walsh NP (2011) Tear Fluid Osmolarity as a Potential Marker of Hydration Status. Med Sci Sport Exerc 43:1590-1597Google Scholar
  15. 15.
    Tomlinson A, McCann LC, Pearce EI (2010) Comparison of Human Tear Film Osmolarity Measured by Electrical Impedance and Freezing Point Depression Techniques. Cornea 29:1036–1041PubMedCrossRefGoogle Scholar
  16. 16.
    Utine CA, Bicakcigil M, Yavuz S, Ciftci F (2011) Tear Osmolarity Measurements in Dry Eye Related to Primary Sjögren’s Syndrome. Curr Eye Res 36:683–690PubMedCrossRefGoogle Scholar
  17. 17.
    Versura P, Profazio V, Campos EC (2010) Performance of Tear Osmolarity Compared to Previous Diagnostic Tests for Dry Eye Diseases. Curr Eye Res 35:553–564PubMedCrossRefGoogle Scholar
  18. 18.
    Khanal S, Millar T (2011) Barriers to clinical uptake of tear osmolarity measurements. Br J Ophthalmol. doi: 10.1136/bjo.2011.202754
  19. 19.
    Messmer E, Bulgen M, Kampik A (2010) Hyperosmolarity of the tear film in dry eye syndrome. Dev Ophthalmol 45:129–138PubMedCrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  1. 1.Ophthalmic Research Group, School of Life and Health SciencesAston UniversityBirminghamUK

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