Evaluation of a new tear osmometer for repeatability and accuracy, using 0.5-μl (500-nanoliter) samples

Elvin H. Yildiz, Vincent C. Fan, Hina Banday, Lakshmi V. Ramanathan, Ratna K. Bitra, Eileen Garry, Penny A. Asbell

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

PURPOSE: To evaluate the repeatability and accuracy of a new tear osmometer that measures the osmolality of 0.5-μL (500-nanoliter) samples. METHODS: Four standardized solutions were tested with 0.5-μL (500-nanoliter) samples for repeatability of measurements and comparability to standardized technique. Two known standard salt solutions (290 mOsm/kg H2O, 304 mOsm/kg H2O), a normal artificial tear matrix sample (306 mOsm/kg H2O), and an abnormal artificial tear matrix sample (336 mOsm/kg H2O) were repeatedly tested (n = 20 each) for osmolality with use of the Advanced Instruments Model 3100 Tear Osmometer (0.5-μL [500-nanoliter] sample size) and the FDA-approved Advanced Instruments Model 3D2 Clinical Osmometer (250-μL sample size). RESULTS: Four standard solutions were used, with osmolality values of 290, 304, 306, and 336 mOsm/kg H2O. The respective precision data, including the mean and standard deviation, were: 291.8 ± 4.4, 305.6 ± 2.4, 305.1 ± 2.3, and 336.4 ± 2.2 mOsm/kg H2O. The percent recoveries for the 290 mOsm/kg H2O standard solution, the 304 mOsm/kg H2O reference solution, the normal value-assigned 306 mOsm/kg H2O sample, and the abnormal value-assigned 336 mOsm/kg H2O sample were 100.3, 100.2, 99.8, and 100.3 mOsm/kg H2O, respectively. CONCLUSIONS: The repeatability data are in accordance with data obtained on clinical osmometers with use of larger sample sizes. All 4 samples tested on the tear osmometer have osmolality values that correlate well to the clinical instrument method. The tear osmometer is a suitable instrument for testing the osmolality of microliter-sized samples, such as tears, and therefore may be useful in diagnosing, monitoring, and classifying tear abnormalities such as the severity of dry eye disease.

Original languageEnglish
Pages (from-to)677-680
Number of pages4
JournalCornea
Volume28
Issue number6
DOIs
StatePublished - Jul 2009

Keywords

  • Dry eye disease
  • Precision
  • Repeatability
  • Tear osmolality
  • Tear osmometer

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