Affiliations: [a] Research Laboratories, Nippondenso Co., Ltd., 500-1 Minamiyama, Komenoki-cho, Nisshin, Aichi 470-01, Japan | [b] Department of Ophthalmology, University of Tokyo, School of Medicine, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113, Japan | [c] Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153, Japan
Correspondence:
[*]
Corresponding author. Research Laboratories, Nippondenso Co., Ltd., 500-1 Minamiyama, Komenoki-cho, Nisshin, Aichi 470-01 (Japan). Tel 81-5617-5-1131, fax 81-5617-5-1194
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 g/l 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.
