Choroidal melanoma is a cancer that affects part of the eye. It develops in the choroid, the sponge-like membrane at the back of the eye between the sclera (the white of the eye) and the retina. (The retina is the light-sensitive structure at the back of the eye. It sends visual information to the brain.) The choroid is rich in blood vessels and supplies nutrients to the retina.
Over time, many choroidal melanomas enlarge and cause the retina to detach. This can lead to vision loss. The tumors also can spread (metastasize) to other parts of the body. The liver is the most common site for metastasis. If it spreads, this cancer can be fatal.
Although choroidal melanoma is rare, it is the most common eye cancer in adults. It usually occurs in people who are middle-aged or older.
Melanomas usually occur in the skin. But they can also develop in places where certain cells contain the pigment melanin. The choroid is one such example.