An adequate and consistent layer of tears on the surface of the eye is essential to keep your eyes healthy, comfortable and seeing well.Tears bathe the eye’s surface to keep it moist and wash away dust, debris and microorganisms that could damage the cornea and lead to an eye infection.
A normal tear film consists of three important components:
- An oily (lipid) component
- A watery (aqueous) component
- A mucous-like (mucin) component
Each component of the tear film serves a critical purpose. For example, tear lipids help keep the tear film from evaporating too quickly and increase lubrication, while mucin helps anchor and spread the tears across the surface of the eye.
Each tear component is produced by different glands on or near the eye:
- The oily component is produced by meibomian glands in the eyelids.
- The watery component is produced by lacrimal glands located behind the outer aspect of the upper eyelids.
- The mucin component is produced by goblet cells in the conjunctiva that covers the white of the eye (sclera).
A problem with any of these sources of tear film components can result in tear instability and dry eyes.