Melanoma is often thought of as a skin cancer, but it can affect other parts of your body, too. Melanoma affects the melanocytes, cells that produce pigment. These cells are found in your skin, but they're also found in your uvea, a portion of your eye that contains your iris. Melanoma that forms in the uvea is known as ocular melanoma or melanoma of the eye. Here are five things you need to know about it.

What are the symptoms of ocular melanoma?

Ocular melanoma doesn't always cause symptoms. Most of the time, they develop in the part of the uvea that isn't visible, so you may not realize you have it until your optometrist discovers it during a routine eye exam.

Some people do experience symptoms. These symptoms include things like seeing a dark spot on the iris. The shape of the pupil can also change. Vision changes such as blurred vision, loss of vision, or seeing flashing lights can also occur.

What causes it?

Ocular melanoma develops when errors form in the DNA of the melanocytes in your eyes. Normally, cells with errors die and are replaced with healthy cells, but this doesn't happen with ocular melanoma. These errors in these cells make them grow and multiply instead of dying. Researchers still aren't sure why this happens.

While the precise cause of ocular melanoma isn't known, many risk factors for the cancer have been identified. People with blue or green eyes have a higher risk, as do people of Caucasian descent. Getting a lot of sun exposure, either from natural sun or from tanning beds, is also a risk factor. Older age is also a risk factor.

How serious is it?

Survival rates for ocular melanoma are good, as long as you get prompt treatment. The five-year survival rate for ocular melanomas that haven't spread is 80%. This rate drops to 15% if the cancer spreads to other parts of the body, so don't delay getting treatment.

Is it treatable?

Ocular melanoma can be treated. Your optometrist will refer you to an ocular oncologist, a type of doctor that specializes in treating eye cancer. The two main treatment options are radiation therapy and surgery. A type of radiation therapy called plaque radiation therapy is usually used to treat your ocular melanoma.

During this therapy, a plaque covered in radioactive seeds will be sewn onto to the wall of your eye, near your cancer. Radiation from the plaque will damage and kill the cancer cells, and after four or five days, the plaque will be removed. If you're scared of getting this procedure, or if you're a good candidate for another reason, an external beam can be used to direct radiation into your cancer cells.

Surgery can also be done. If your melanoma is small, the tumor and a small margin of healthy tissue around the tumor will be removed. If the melanoma is large, your entire eye may need to be removed. It can be replaced later with a high-quality artificial eye.

Can it be prevented?

Since the cause of ocular melanoma isn't yet known, it's not known if preventing it is possible. However, optometrists recommend a few precautionary steps that may later be proven to be preventative. They recommend staying out of the sun and protecting your eyes from sun exposure by wearing sunglasses. Exercising regularly and eating a healthy diet may also be preventative as these behaviors have been shown to reduce the risk of other types of cancers.

If you're worried about ocular melanoma, or have noticed changes in your eyes, see your optometrist for a screening or at your next appointment for your eyeglasses.