A chalazion is a swelling that can develop on the inside of your eyelids. They are usually painless unless they become infected.
The condition is quite common. It can be treated with a hot compress. If the chalazion becomes inflamed or infection, antibiotics may be needed. In rare cases, surgery may be required.
A chalazion can occur when the Meibomian glands, which create an oily substance for tears, become blocked. The oil cannot drain properly and so builds up in the gland, causing a lump on the inside of your eyelid.