From its name alone, you might think dry eye disease simply means your eyes don’t produce enough tears. That’s actually only part of the story. There are several types of dry eye disease.
- Aqueous deficient dry eye: This is when your eyes don’t produce enough tears. Your lacrimal gland (in the upper, outer corner of each eye) produces your aqueous tears. These tears make up the middle, watery layer of your tear film. Some autoimmune conditions can cause inflammation in your lacrimal gland and prevent it from producing enough aqueous tears.
- Evaporative dry eye: This is when your tears evaporate too quickly. The most common cause is meibomian gland dysfunction. This means the glands in your eyelids that produce the outer, oily layer of your tear film don’t work properly. As a result, the oily layer is unstable and can’t protect the watery layer from drying up.
- Mixed dry eye: Some people have aqueous tear deficiency and tear instability. This means your eyes don’t produce enough tears, plus your tear film is unstable. Both of these problems lead to dry eye symptoms.