Choroidal Melanoma

What Is It?

Choroidal melanoma is a cancer of the eye that develops from the pigmented cells of the choroid, the spongelike membrane that lies between the sclera (the white of the eye) and the retina. The choroid is rich in blood vessels, and supplies nutrients to the retina. Choroidal melanoma is a primary cancer, meaning the tumor originates in the eye rather than moving to the eye from cancer in another part of the body. Although choroidal melanoma is a rare form of cancer, it is the most common primary eye cancer in adults.

Over time, many choroidal melanomas enlarge and cause the retina to detach, which can lead to vision loss. The tumors also can spread (metastasize) to other parts of the body and cause death. Choroidal melanomas most commonly spread to the liver. According to the U.S. National Institutes of Health, 1,680 to 2,240 new cases of this cancer are diagnosed each year in the United States and Canada, which is about six to eight new cases per million people each year. People who are middle-aged or older are most susceptible.

Symptoms

This cancer often causes no symptoms in its early stages, so the tumor may grow for some time before the problem becomes noticeable. When symptoms occur, they include blurred vision, floaters, flashing lights or severe eye pain. These symptoms also can be caused by many other, more common noncancerous causes.

Diagnosis

Most cases of choroidal melanoma are detected during a routine, dilated-eye exam, in which an ophthalmologist dilates the pupils to examine the back of the eye Most of the time, a choroidal melanoma can be diagnosed through a clinical examination alone. During a dilated-eye exam, the ophthalmologist is able to recognize choroidal melanoma by the tumor's pigmentation, its location and shape, and other clinical observations. Specialized tests can help make the diagnosis more certain:

• Echography — A small probe is placed on the eye, directing sound waves toward the tumor and recording the pattern as the waves reflect off the tumor.
• Fluorescein angiography — A fluorescent dye is injected into a vein in the arm, and a rapid sequence of photographs is taken through the pupil as the dye passes through the veins in the back of the eye.

Expected Duration

Once it develops, choroidal melanoma often will continue to grow unless it is treated. Treatment is recommended if findings indicate that the tumor is likely to enlarge and cause loss of vision, or possibly spread to other organs.

Prevention