27/02/2026
👁️ Meibomian Glands
Meibomian glands are modified sebaceous (oil) glands located vertically inside the tarsal plate of both upper and lower eyelids.
They secrete meibum (oily secretion) which forms the outer lipid layer of the tear film and prevents tear evaporation.
🔬 Function
✔ Prevents rapid evaporation of tears
✔ Maintains tear film stability
✔ Provides smooth optical surface
✔ Prevents dry eye
🔢 Number of Meibomian Glands
Upper eyelid: 🟡 25–40 glands (usually more numerous and longer)
Lower eyelid: 🟡 20–30 glands
👉 Upper lid has more glands than lower lid.
⚠️ Clinical Importance
Dysfunction → Meibomian Gland Dysfunction (MGD)
Leads to Evaporative Dry Eye
Can cause Chalazion or posterior blepharitis