PURPOSE: To measure the pH in the precorneal tear film of humans in vivo using a pH-sensitive fluorescent dye, bis-carboxyethyl-carboxyfluorescein (BCECF). METHODS: The measurement was initiated by instilling 1 microliter of 2 mM BCECF solution into the subject's eye. The pH was calculated by measuring the ratio of fluorescent intensities at two excitation wavelengths (490/430 ratio), which was dependent on pH, but independent of the dye concentration and other variables. The tears of the same subject were then collected and loaded on to a micro pH-meter to ensure the accuracy of the measurement. RESULTS: The mean pH values of 40 eyes from 20 healthy volunteers was 7.50 (SD +/- 0.23), which corresponded well with those measured by the micro pH-meter. CONCLUSIONS: The method described was useful in measuring the pH of the precorneal tear film of humans with minimal invasion.
PURPOSE: To measure the pH in the precorneal tear film of humans in vivo using a pH-sensitive fluorescent dye, bis-carboxyethyl-carboxyfluorescein (BCECF). METHODS: The measurement was initiated by instilling 1 microliter of 2 mM BCECF solution into the subject's eye. The pH was calculated by measuring the ratio of fluorescent intensities at two excitation wavelengths (490/430 ratio), which was dependent on pH, but independent of the dye concentration and other variables. The tears of the same subject were then collected and loaded on to a micro pH-meter to ensure the accuracy of the measurement. RESULTS: The mean pH values of 40 eyes from 20 healthy volunteers was 7.50 (SD +/- 0.23), which corresponded well with those measured by the micro pH-meter. CONCLUSIONS: The method described was useful in measuring the pH of the precorneal tear film of humans with minimal invasion.
Authors: Mark D P Willcox; Pablo Argüeso; Georgi A Georgiev; Juha M Holopainen; Gordon W Laurie; Tom J Millar; Eric B Papas; Jannick P Rolland; Tannin A Schmidt; Ulrike Stahl; Tatiana Suarez; Lakshman N Subbaraman; Omür Ö Uçakhan; Lyndon Jones Journal: Ocul Surf Date: 2017-07-20 Impact factor: 5.033
Authors: Xiaoyong Yuan; Bradley M Mitchell; Xia Hua; Dana A Davis; Kirk R Wilhelmus Journal: Invest Ophthalmol Vis Sci Date: 2010-04-07 Impact factor: 4.799