Malignant melanoma of the eye can develop when pigment cells in your eye grow out of control. Pigment cells are responsible for your eye color. The cause of uncontrollable cell growth isn’t usually known. Exposure to ultraviolet radiation has been identified as one potential cause of the disease. Choroidal melanoma is cancer that affects the inner 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.
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.
This cancer often doesn’t cause any symptoms in its early stages. The tumor may grow for some time before the problem becomes noticeable. When symptoms occur, they include
- having blurry vision
- seeing spots
- seeing flashing lights
- having severe eye pain
Having these symptoms doesn’t mean you have choroidal melanoma. These symptoms can be caused by other conditions that are more common—and noncancerous. In fact, seeing spots and flashing lights are very common symptoms. And they are rarely related to choroidal melanoma.
Most cases of choroidal melanoma are detected during a routine, dilated eye exam. During this exam, an eye specialist (ophthalmologist) dilates the pupils to examine the back of the eye. Most of the time, no other tests are needed. But specialized tests can confirm the diagnosis.
These tests include:-
- ultrasound. A small probe placed on the eye directs sound waves toward the tumor. A machine records the patterns the waves make as they bounce off the tumor.
- fluorescein angiography. A fluorescent dye is injected into an arm vein. A rapid sequence of photographs is taken through the pupil as the dye passes through the veins in the back of the eye.
After a choroidal melanoma has been diagnosed, an MRI (magnetic resonance imaging) scan may be ordered. This can help doctors further evaluate the tumor’s characteristics.
Because the causes of choroidal melanoma are not well understood, there is no known way to prevent it.
Management and treatment of choroidal melanoma depend on the tumor’s size. If the tumor is small, it may simply be monitored. If it grows, treatment would start.
Medium and large choroidal melanomas usually are treated with radiation or surgery. Radiation therapy may be given in different ways. Local radiation is delivered via a small, metal, dish-shaped device containing radioactive iodine. The device is stitched to the sclera so that the radiation can target the tumor precisely. In some institutions, external beam radiation therapy may be used. Beams of radiation target the tumor from outside the body.
In some cases, the eye has to be removed. This is called enucleation. Most ophthalmologists recommend removing the eye if the choroidal melanoma is large. After the eye is removed, a prosthetic eye is placed into the socket. Cosmetically, the fake eye can look almost real. However, it often does not move as well as a natural eye.
If you are treated for choroidal melanoma, you will need to be monitored for the rest of your life. This helps doctors determine whether the cancer has spread to other parts of the body.
Treatment of choroidal melanoma that has already spread beyond the eye has had very limited success. There is little evidence that radiation or surgery to remove the eye affects the outcome in these cases. Researchers are studying whether chemotherapy given after the eye is removed can reduce the risk of death from metastatic choroidal melanoma. Newer biological therapies are also being tested.
The outlook depends on the size of the tumor when it’s diagnosed. The prognosis is better if the cancer is contained within the eye and has not spread to other parts of the body.