Melanoma is cancer that develops in pigment-producing cells called melanocytes. Ocular melanoma is when this type of cancer develops in your eye.

Ocular melanoma is an extremely rare cancer that affects about 5 out of every 1 million adults. Despite its rarity, it’s the most common cancer that primarily develops in the eye. It often doesn’t cause symptoms in the early stages.

The 5-year relative survival rate of ocular melanoma is 85 percent when caught early, but it drops to 15 percent if it spreads to a distant organ.

Keep reading to learn more about this rare cancer, including symptoms, how it’s diagnosed, and treatment options.

Your eye is made up of three layers:

  • Sclera. The sclera is the protective white outer layer that wraps around most of your eyeball.
  • Uvea. This is the middle layer, and it contains your iris and the ciliary muscles that control your lens. It also has a layer of tissue filled with blood vessels called the choroid.
  • Retina. The retina is the innermost layer, and it’s made of special cells that detect light and send electrical information to your brain.

Ocular melanoma most commonly develops in the uvea. It can also develop in the conjunctiva, a thin layer of tissue that covers the eye’s surface.

Uveal melanoma

Ocular melanoma can develop in your:

  • iris
  • ciliary muscles
  • choroid

According to older 2012 research, about 85 percent of cases of uveal melanoma develop in the posterior choroid. Cancer of the ciliary muscles is associated with the least favorable outlook.

Cancers that develop in the iris tend to be detected quickest and have the best outlook.

Conjunctival melanoma

Conjunctival melanoma develops in the membrane on the surface of your eye. According to a 2014 review, it makes up about 2 percent of eye cancers.

Ocular melanoma may or may not cause symptoms, depending on the location of the tumor and its size. It may take many years for symptoms to develop, but they can include:

The exact cause of ocular melanoma is not known, but it’s thought that a combination of genetic and environmental factors may play a role.

Research is inconclusive about whether ultraviolet (UV) light exposure increases the risk of ocular melanoma like it does with skin melanoma.

About 50 percent of people with ocular melanoma have a loss of genetic information on chromosome 3.

People with a strong family history of eye cancers may have a rare genetic mutation in their BAP1 gene. The BAP1 gene is classified as a tumor suppressor gene and slows down cell division.

The genes EIF1AX and SRSF2/SF3B1 also seem to occur frequently in people with ocular melanoma.

Although it’s not clear why ocular melanoma develops, certain people are at a higher risk. Risk factors include:

  • older age
  • light-colored eyes
  • fair skin
  • inability to tan
  • sunburning easily
  • having moles or freckles
  • having eye freckles
  • having atypical mole syndrome

Ocular melanoma can develop in people of any ethnic group, but it’s 8 to 10 times more common in people of European descent than in people of African descent.

People with BAP1 cancer syndrome, a rare genetic condition, are at an increased risk of:

Depending on what part of your eye is affected, melanoma can interfere with your vision or cause increased eye pressure. It can also spread to other parts of your body.

Ocular melanoma is estimated to spread to distant organs in about 40 to 50 percent of people with the cancer. When it spreads, it goes to the liver about 80 percent of the time. It’s also known to spread to the:

  • lungs
  • skin
  • soft tissue
  • bone

Treatment for eye melanoma varies based on the size and location of the tumor and whether it’s causing symptoms.

Watchful waiting

Small melanomas may not require any treatment if your doctor thinks it’s going to grow slowly. However, there’s an increasing trend to treat small melanomas early.

Radiation therapy

Brachytherapy is often used for small- to medium-sized cancer. This technique involves implanting a radioactive disc next to the tumor for several days to damage cancer cells and shrink the tumor.

External beam radiotherapy is also sometimes used. It delivers laser beams of radiation to destroy cancer cells.

Surgery

Various surgical techniques may be used to remove the tumor. In some cases, the area around the tumor may be removed. The most extreme option is the removal of the entire eye, which may be necessary if your eye is severely damaged.

Cancers of the eye are sometimes spotted during a routine eye exam.

The American Optometric Association recommends that all adults have an eye exam at least every 2 years. They recommend that people at risk of vision problems and adults ages 65 and over have an exam annually.

Eye cancer often does not cause symptoms in the early stages, but if you do develop potential symptoms, it’s important to see your eye doctor right away.

Doctors make a diagnosis of ocular melanoma based on:

  • your symptoms
  • your medical history
  • an evaluation of your eye

Cases of ocular melanoma are often discovered in a routine eye exam and confirmed by an ocular oncologist, a doctor who specializes in cancer of the eye.

If cancer is suspected, your doctor may recommend other tests, such as:

  • Ultrasound of the eye. In an eye ultrasound, high energy sound waves are bounced off the tissues in your eye to create a picture.
  • Fluorescein angiography. In fluorescein angiography, a colored dye is injected into a vein in your arm, and it travels through your bloodstream. A camera with a special filter detects the dye and forms a picture.
  • Fundus autofluorescence. A special camera detects the natural pigment in your eye and reveals damage as points of light.
  • Optical coherence tomography. An imaging device detects changes in light waves to create a detailed image of your eye.
  • Fine needle aspiration biopsy. Your eye is injected with a thin needle to collect a sample of tissue to be tested in a laboratory.

The cause of ocular melanoma is largely unknown, and it isn’t clear if it can be prevented.

It’s not clear if there’s an association with sunlight exposure or how strong this association is. It’s possible that protecting your eyes from the sun may help reduce your risk of cancer.

The American Cancer Society recommends wearing UV-protected sunglasses when you’re outside in strong sunlight. Wrap-around glasses with at least 99 percent UVA and UVB protection are best.

According to the American Cancer Society, the 5-year relative survival rate of ocular melanoma is 82 percent.

A 2022 study of 355 people with uveal melanoma who were treated with ruthenium-106 brachytherapy found that:

  • 99 percent were cancer-free after 5 years
  • 97 percent were cancer-free after 7 years
  • 85 percent were cancer-free after 9 years

The researchers also found that 63 percent of the participants developed radiation complications, and of these:

A Swedish study followed a group of 677 people with uveal melanoma who were treated with brachytherapy over a 40-year period. The researchers found that most uveal melanoma-related deaths were in the first 10 years after treatment. People who survived 20 years or more had no survival disadvantage over people in the general population.

Ocular melanoma is the most common type of cancer that starts in the eye. It most commonly develops in the middle layer of the eye, below the white of your eye, but can also develop in the mucous membranes on the surface of your eye.

Eye cancer often does not cause symptoms, but if you do notice any potential warning signs, it’s important to see an eye doctor right away for a proper evaluation.