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Published on Jun 5, 2018
When you blink, a tear film spreads over the eye making the surface smooth and clear. The tear film is made up of three distinct layers. An oily layer, a watery layer and a mucous layer. Each layer is needed for the tear film to keep our eyes moist.
Tears protect the eyes and keep them moist and healthy. Tears come from the conjunctiva which is the clear tissue over the white of the eye, and from the lacrimal glands. These glands are located above each eye. The tears flow across teh surface of your eye and drain through tiny holes called puncta. Puncta are in the corners of your upper and lower eyelids near the nose. The tears then travel through tiny passages in the eyelids. They eventually go into the nasal lacrimal duct before emptying into your nose; this is why your nose runs when you cry. When the tear drainage system is either partly or completely blocked, tears cannot drain normally. The eye becomes watery and irritated it can also be constantly infected. A blocked tear duct can be due to age, injury or infection.