How do tears work?
When you blink, you spread a sheet of tears over your eye. This keeps the surface of the eye soft and smooth. The tear film is important for good vision.
The tear film is made up of three layers.
An oily layer
A watery layer
A mucous layer
Each layer of the tear serves a function.
The oily layer is the outer part of the tear film. This makes the tear surface smooth and keeps the tears from drying out too quickly. This layer is generated in the meibomian glands of the eye.
The aqueous layer is the middle of the tear film. It accounts for most of what we see as tears. This layer cleans the eye, washing away particles that do not belong in the eye. This layer comes from the lacrimal gland in the eyelids.
The mucous layer is the inner layer of the tear film. This layer helps spread the aqueous layer over the surface of the eye to keep it moist. Without the presence of mucus, tears do not adhere to the eye. Mucus is produced in the conjunctiva. The conjunctiva is the transparent tissue that covers the white part of the eye and the inside of the eyelids.
In general, the eyes produce tears constantly to keep them moist. If our eyes are irritated or we cry, the eyes produce a lot of tears. However, sometimes the eyes do not produce enough tears or something affects one or more layers of the tear film. In those cases, the result is dry eyes.
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