The Science

The tear film has three layers: an outer oily layer (from meibomian glands in the eyelids), a middle watery layer, and an inner mucus layer. The oil layer slows evaporation and keeps the tear film stable.

Meibomian gland dysfunction (MGD) is a leading cause of dry eye. When these glands are blocked or produce poor-quality oil, tears evaporate too quickly (evaporative dry eye). MGD is common, especially with age. Diagnosis may include imaging and tear film analysis. Treatment ranges from warm compresses and lid hygiene to prescription therapy and in-office procedures. Understanding the science helps you and your doctor choose the right options.