A Chalazion (or Meibomian Cyst) is a small cyst that occurs in either the upper or lower eyelid. It is a common condition that is caused by a blockage of one of the oily glands found in the eyelids. Sometimes the cyst may also become infected, which causes it to swell and become red. Usually antibiotics and hot compresses will help to clear the cyst but occasionally a minor surgical procedure is needed.
A Stye is another kind of eyelid cyst that is smaller but more painful than a chalazion. A stye is due to a minor infection at the base of an eyelash and looks like a small pimple. Most styes will resolve on their own but hot compresses and antibiotics sometimes help to clear them more rapidly.