Why are tears salty?

The lacrimal glands above each eye produce tears by filtering blood plasma, which is naturally about 0.9 percent salt (mostly sodium chloride). Tears also contain potassium, proteins, lipids and lysozyme, an enzyme that fights bacteria. There are three types of tears: basal tears that keep the eye moist, reflex tears triggered by irritants like onions, and emotional tears. Emotional tears contain slightly higher levels of stress hormones and proteins than reflex tears, which is why some scientists suggest crying may help relieve stress. The salt in all tears helps maintain the right chemical balance on the eye’s surface.