Meibomian gland dysfunction (MGD) is the most common cause of dry eye syndrome. Upwards of 75% of dry eye patients have MGD, which causes dry eye due to increased evaporation of the tears or decreased tear production. MGD is also known as meibomitis or meibomianitis (inflammation of the meibomian glands).
Symptoms of MGD are exactly the same as dry eye symptoms, including crustiness, redness, blurry vision, itching and tearing.
The meibomian glands are located in your eyelids. There are 30 to 40 glands in your upper lids and slightly fewer in your lower lids. The glands secrete an oily substance through openings located on the edge of your eyelids adjacent to your eyelashes.
The oil is called meibom and is an oily mixture that forms the top layer of the tear film. The oil, also called “lipid,” prevents the watery tears from rapid evaporation.
There are 3 layers to a normal tear film:
- Oily or lipid layer (superficial top layer of tears)
- Aqueous (the actual fluid of tears)
- Mucin (allows tears to spread evenly across the eye)