Chalazion

A round, painless swelling in the upper or lower eyelid caused by obstruction of one of the meibomian glands that lubricate the edge of the eyelids. Chalazions are sometimes called meibomian cysts. They are particularly common in people suffering from acne, rosacea, or seborrhoeic dermatitis. If the cyst becomes infected the eyelid becomes more swollen, red, and painful. A large swelling putting pressure on the cornea at the front of the eye can cause blurring of vision. About a 3rd of chalazions disappear without treatment, but large cysts may need to be removed surgically.