When the lacrimal gland fails to produce enough tears to coat the surface of the eye, symptoms of aqueous tear deficient dry eye may appear. When tear volume is low, the tears become hyperosmotic. Hyperosmolarity in regards to tears means that there is less water and more salt in the tears.
Increased hyperosmolarity of the tears causes increased hyperosmolarity of the corneal epithelium. As a result, inflammatory mediators collect in the tear film and on the surface of the eye, exacerbating ocular surface disease. Inflammatory mediators cause damage to goblet cells in the corneal epithelium.
Goblet cells are important because they produce mucin, the bottom layer of the tear film. Mucin is a glycoprotein with mucous-like properties that attract tears to the corneal surface, keeping tears on the eye. Decreased mucin production results in tear film instability and subsequent increase in tear hyperosmolarity and inflammation.
There are currently two eye drops that help treat Aqueous Deficient Dry Eye– Restasis and Xiidra.