The Tear Film and Dry Eye Disease

The tear film is a thin layered coating that keeps the surface of the eye smooth, moist, and protected. Its innermost component is a mucin layer produced by conjunctival goblet cells that helps tears adhere to the cornea, its middle aqueous layer is secreted mainly by the lacrimal glands, and its outer lipid layer, produced by the meibomian glands in the eyelids, slows evaporation. Blinking spreads the film across the eye, and tears drain through the puncta into the nose.

Dry eye disease arises when this system fails, either through reduced aqueous production or through excessive evaporation, most often due to meibomian gland dysfunction. The resulting instability and increased salt concentration of the tears trigger inflammation on the ocular surface, which further impairs tear production in a self perpetuating cycle. Contributing factors include aging, hormonal changes, autoimmune disease, contact lens wear, certain medications, and reduced blinking during screen use.

Treatments range from lubricants and eyelid therapies to anti inflammatory drops and punctal plugs..