Eye cancer is the formation of tumors from cells in any of the multiple parts of the eye and its surrounding structures. The American Cancer Society reports that the eye has three major structures: the eyeball, the orbit and the adnexal structures (accessory to the eye, such as tear glands and the eye lids). The eyeball has three main layers: the sclera, the uvea and the retina. Cancer of the eye is more rare than other types of cancers, but there are multiple possible types of eye cancer.
Intraocular or Uveal Melanoma
The American Society of Clinical Oncology reports that the most common type of primary eye cancer in American adults is intraocular melanoma. This type of cancer arises from melanocytes, which are cells in the eye that produce pigment. According to the American Cancer Society, the melanocytes that usually become cancerous are in the uvea, and thus this type of cancer is often referred to as uveal melanoma. About 90 percent of uveal melanomas develop in a substructure of the uvea called the choroid. Other forms of uveal melanoma begin in the iris. This form of cancer is easier to spot than cancer of melanocytes in the choroid because the cancer is visible as a growing spot on the iris. Furthermore, melanoma in the iris rarely spreads to other sites in the body, and thus people with this type of cancer often have an optimistic prognosis. Uveal melanomas are often made up of two types of cells: spindle cells and epithelioid cells. Epithelioid cells are more likely than spindle cells to spread to other sites of the body (metastasize).
Intraocular Lymphoma
The American Cancer society reports that intraocular lymphoma is cancer that begins in a type of immune cell, called a lymphocyte, that is present in the eye. This type of cancer is quite rare, and usually occurs in the elderly or in people who have compromised immune systems, such as those with AIDS.
Adnexal and Orbital Cancer
The orbit and adnexal, or accessory, structures of the eye are made up of skin, muscle, and nerve tissues. When cancer begins in the cells of these structures, they are much like cancers that affect the skin, nerve, or muscles in other parts of the body. For example, one type of adnexal structure cancer is the eyelid. When cancer affects the eyelid, it is a skin cancer, and can arise from either basal or squamous cells. The American Society of Clinical Oncology notes that this type of tumor can be removed surgically, and usually does not spread to other sites in the body. When cancer arises from the muscle cells surrounding the eyes, it is referred to as a muscle cancer, or sarcoma; when it arises from the nerves in or around the eye, it is called a neuroma.
