title: Measurement of tear electrolyte concentration and turnover rate using a flexible conductimetric sensor.
abstract: Tear fluid conductivity was measured by a non-invasive method. A flexible 3 mm-wide conductimetric sensor was placed inside the human subjects temporal lower cul-de-sac (similar to Schirmer test strip), and used to evaluate electrolyte concentration and turnover rate in tear for normal, healthy subjects aged between 30 to 85 years in a normal, light indoor environment. The tear electrolyte concentration was calculated from tear conductivity to give a mean value of 297 mEq/l (S.D. 30 mEq/l; n = 29) which was consistently with previously reported values. Tear turnover rate was calculated by a single exponential equation of tear conductivity change, following the application to the eye-drops of 40.0 milligrams sodium chloride solution. The mean turnover rate was 44.2% per minute (S.D. = 13.3% per minute; n = 30), being in agreement with previously reported values.
authors.affiliation: Research Laboratories, Nippondenso Co., Ltd., Aichi, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Mitsubayashi
authors.forename: K
authors.initials: K
authors.lastname: Ogasawara
authors.forename: K
authors.initials: K
authors.lastname: Yokoyama
authors.forename: T
authors.initials: T
authors.lastname: Takeuchi
authors.forename: T
authors.initials: T
authors.lastname: Tsuru
authors.forename: I
authors.initials: I
authors.lastname: Karube
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003217:Conductometry / Q000295:instrumentation*; D004553:Electric Conductivity; D004573:Electrolytes / Q000032:analysis* / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D007638:Keratoconjunctivitis Sicca / Q000175:diagnosis; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D013666:Tears / Q000737:chemistry*
chemical_list: D004573:Electrolytes