Choroidal melanoma is a type of cancerous growth that originates in the choroid, a layer of eye tissue that covers the retina. It is a relatively rare form of cancer that usually afflicts people over the age of 55. Choroidal melanoma does not typically cause physical symptoms in its early stages, but it can eventually lead to vision problems. The preferred course of treatment for a small growth is a specialized type of radiation therapy. Surgery to remove the affected eye is considered a final option to prevent the cancer from spreading to other parts of the body.
The choroid layer of the eye contains melanin, a special type of pigment that helps reflect light, produce clear visual images, and provide coloration of the iris. Choroidal melanoma initially arises in these pigments and forms a tumor that spreads across the choroid. A tumor may not cause any physical symptoms if it does not grow near the lens in the front of the eye or the optic nerve at its base. Cancers that spread to these locations, however, can lead to blurry and distorted vision. A person may notice dark floating spots or be unable to focus his or her vision straight ahead.
The exact causes of choroidal melanoma are not well understood by doctors. People who have light-colored irises and those who spend a lot of time in the sunlight appear to be at the highest risk of developing the condition. In addition, some studies suggest that genetic inheritance can play a role in the development of eye cancers.
In most cases, choroidal melanoma is first noticed during a routine eye exam with an ophthalmologist. The doctor may notice unusual pigmentation in the eye or see the tumor itself on close examination. Additional diagnostic tests, such as echographs and ultrasounds, can help confirm the presence of a tumor. After confirming a diagnosis, the ophthalmologist usually refers the patient to cancer specialists for a more thorough screening and to learn about treatment options.
Choroidal melanoma tends to respond well to radiation treatments when tumors are small. Specialists can place a layer of radioactive plaque on a tumor to destroy cancerous tissue while protecting the surrounding healthy tissue. Some surgeons prefer to use beam irradiation procedures, which involve directing a concentrated beam of helium ions directly onto the tumor. If the cancer grows large enough to disrupt vision, surgeons may need to remove the entire eye in a procedure called enucleation.
Following treatment, patients are usually instructed to schedule regular appointments with their ophthalmologists to ensure the tumors do not return. Since choroidal melanoma often goes undetected until it has already begun to spread, a large number of patients suffer from secondary cancer problems. Additional radiation or chemotherapy treatments may be necessary if choroidal melanoma does spread beyond the eye.