The concentration of lactoferrin in tears of normals and of diabetics.

The tear lactoferrin content and the tear secretion rate was determined in 105 normal subjects (age range: 15-93 years) and 21 diabetic patients (age 21-78 years). Tear sampling was performed using glass capillaries and the lactoferrin concentration in tears was tested employing an enzyme-linked immunosorbent assay. Tear secretion rate was measured using standardized Halberg filter paper placed in the inferior fornix for 5 min. The lactoferrin level of normal tears showed a significant inverse correlation with age, the mean value of the 8th decade (0.81 mg/ml) constituting only about half the value of the lactoferrin level found in the 3rd decade (1.48 mg/ml). The tear secretion rate also displayed a significant decrease with age, but no correlation could be demonstrated between the tear secretion rate and lactoferrin concentration. No difference was found in lactoferrin level between men and women. We were not able to demonstrate any correlation between lactoferrin content of tears and the duration of diabetes in the 21 diabetic subjects, and there was no difference between the level of lactoferrin in normal tears compared to the concentration in diabetic tears. No difference was found between the tear secretion rate in normals and in diabetics.