Types of Dry Eye Syndrome
Tears are comprised of 3 layers: lipid (oil), water, and mucus. The composition of these components is what helps to protect and nourish the surface of our eyes. The lipid or oil layer prevents the evaporation of the water layer. The mucus layer helps spread the tears evenly over the eye surface. When these layers are not functioning properly, the tears can either evaporate too rapidly or they do not reach the entire eye surface, which will then cause the symptoms of dry eyes.
There are 2 predominant forms of dry eye: aqueous and evaporative.
Aqueous Dry Eye
Aqueous dry eye is characterized by tear deficiency. It occurs when the lacrimal glands don’t produce enough of the watery component of tears.
Evaporative Dry Eye
Evaporative dry eye affects 65% of dry eye patients. It is caused by Meibomian gland dysfunction (MGD), which creates a deficiency in the oil layer of the tear film. These glands make the lipid or oily part of tears that slows evaporation and keeps the tears stable. This can be the beginning of other dry eye disease problems including damage to the cornea and sight-related issues.