The causes of a chalazion
Chalazions are caused by the inflammation of the Meibomian gland. The Meibomian glands produce lipids (fat), which form the "meibum" and mingle with tears to ensure the lubrication of the ocular surface. These tiny glands are located in the eyelids and are connected to the free edge of the eyelids by a small canal. It can happen that this canal gets blocked: in this case, the meibum manufactured by the gland cannot flow, the gland becomes clogged and swells and inflammation and sometimes infection can occur.
Some people are particularly prone to chalazions which then tend to re-occur. Chalazions are favoured by the existence of dry eye or any inflammation of the ocular surface, such as rosacea which thickens the lipids produced by the Meibomian glands and makes their evacuation more difficult if not impossible.