Age- and gender-related differences in human lacrimal fluid peroxidase activity

There is evidence to suggest that estrogen influences lacrimal fluid peroxidase activity in women. In this study we investigated changes in peroxidase activity related to ageing and gender. These changes might help to explain the common problem of dry-eye syndrome in menopausal women. Unstimulated tears were collected from 70 healthy subjects of both sexes (age range 24-90 years). Tear samples were collected from 9 to 10 a.m., when peroxidase activity remained stable. In women, lacrimal fluid peroxidase activity decreased significantly during the menopause (p < 0.05 by one-way ANOVA), and thereafter remained unchanged. Conversely, in men, lacrimal fluid peroxidase activity decreased later, declining significantly only towards the age of 80 (p < 0.05). Lacrimal fluid peroxidase activity differs in men and women: the gender-related difference accentuates during ageing, probably owing to changing estrogen levels.