Measurement of pH, electrolytes and electrophoretic studies of tear proteins in tears of patients with dacryoliths: a novel concept for dacryoliths.

Dacryolithiasis is one of the causes of acquired nasolacrimal duct obstruction, although its origin is unclear. The purpose of this study was to investigate the differences in tear constituents between patients with nasolacrimal duct obstruction with dacryoliths and those without dacryoliths. In a prospective case-control study, undiluted tears were collected from 30 eyes from 30 patients with partial acquired nasolacrimal duct obstruction (PANDO) consisting of 17 PANDO patients with dacryoliths and 13 PANDO patients without dacryoliths. The pH, and the Na(+), K(+), Cl(-), total calcium and total protein concentrations were determined. The composition of the tear proteins was assessed by cellulose acetate electrophoresis. In the tear samples from 17 eyes with PANDO/dacryoliths, the mean +/- SD K(+) level was 15.6 +/- 3.1 mEq/l. In the tear samples from 13 PANDO controls, the mean +/- SD K(+) level was 19.8 +/- 4.9 mEq/l. The difference between the two groups was statistically significant (p = 0.02). In the tear samples from PANDO/dacryolith patients, the mean +/- SD total protein level was 129.0 +/- 72.9 mg/dl. In the tear samples from the PANDO controls the mean +/- SD total protein level was 261.6 +/- 132.5 mg/dl. The difference between the two groups was statistically significant (p = 0.00). In the tear protein fractions from electrophoresis, a low level of lysozyme was observed in the PANDO/dacryolith samples compared with the PANDO control samples (p = 0.03). The tears from patients with PANDO due to dacryoliths showed a change in the concentrations of electrolytes and protein, particularly lysozyme, compared with that of the patients with PANDO without dacryoliths, which may be related to the pathogenesis of dacryoliths.