There are a few things that can cause lumps or masses on your eyelids. One of them is a chalazion cyst, also sometimes called a Meibomian cyst or Meibomian gland lipogranuloma. It usually starts as a slowly growing lump on the eyelid, which becomes hard and sometimes quite large. There are about 100 oil secreting Meibomian glands on the eyelid along the eyelashes. When one of the ducts that drain them becomes blocked, the fluid backs up and causes a chalazion.
Chalazion cysts can often be treated conservatively with warm compresses several times a day. Some health care providers recommend washing the eyelids/eyelashes with baby shampoo every day as well. It is important to have a chronic lump on the eyelid diagnosed professionally, because while it may be something you can treat at home, it may also be a sign of a systemic illness, skin cancer, or even if it is a chalazion, it can become big and hard enough to damage your cornea.
If the chalazion requires medical treatment, you may start with a low dose long-term antibiotic for a period of a few weeks or months in addition to the compresses and washing. But if the cyst persists and affects your vision or there is a lot of discomfort or pressure on your eye, you may require surgery.
Surgery for a chalazion cyst can often be done from under the eyelid. It is an outpatient procedure done with local anesthesia and sedation, and the recovery is not usually painful, but it can be irritating as is anything that puts pressure on your eye.
The recovery period after surgery is short, and you may be prescribed antibiotic and/or lubricating eye drops. If the surgery is done from under the eyelid, there will not be a visible scar. The only downside is there is no guarantee that you won’t develop another chalazion. Continuing to wash with the baby shampoo may help prevent recurrence.
Sources:
National Center for Biotechnical Information: ABC of Eyes. Elkington, AR & Khaw, PT. Eyelid and Lacrimal Disorders. BMJ, Volume 297.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1833910/pdf/bmj00299-0047.pdf
Medline Plus: Chalazion
http://www.nlm.nih.gov/medlineplus/ency/article/001006.htm