• Tear pH was measured in 44 normal subjects by immersing the tip of a microcombination glass pH probe in the tear fluid in the inferior cul-de-sac. The normal pH range was 6.5 to 7.6; the mean value was 7.0. This method provides a rapid and accurate measure of tear pH and may better our understanding of tear physiology and tear buffering capacity.
Abelson MB, Udell IJ, Weston JH. Normal Human Tear pH by Direct Measurement. Arch Ophthalmol. 1981;99(2):301. doi:10.1001/archopht.1981.03930010303017