Choroidal melanoma is a form of cancer that affects the choroid of the eye. The choroid is part of the uvea, which is the middle layer of the eye.

Melanomas are cancers that develop in pigment-producing cells called melanocytes. Cancer that forms in the melanocytes of the eye is called ocular melanoma.

Uveal melanoma is a type of ocular melanoma. It can develop on any part of the uvea. Uveal melanoma generally develops in the choroid.

This article looks at choroidal melanoma in more detail, including its causes, symptoms, and treatments.

An eye with choroidal melanoma-1.Share on Pinterest
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The eye consists of three layers:

  • the outer layer, which includes the white of the eye, or sclera, and the cornea
  • the middle layer, or uvea, which contains:
    • the iris, the colored part of the eye
    • the ciliary body, a ring of tissue that changes the shape of the lens
    • the choroid, a thin layer of tissue containing blood vessels that deliver oxygen and nutrients to the retina
  • the inner layer, which contains the retina

Choroidal melanoma affects a person’s choroid. The National Cancer Institute notes that choroidal melanoma is generally larger than melanoma of the iris and more likely to spread.

Although choroidal melanoma is the most common type of uveal melanoma, it is still rare. Research from 2017 notes that about 5⁠ or 6 in 1 million people develop uveal melanoma yearly. The American Cancer Society (ACS) states that about 90% of uveal melanomas will be choroidal or ciliary body melanomas.

Certain risk factors may increase a person’s chances of developing ocular melanoma. These risk factors include:

  • having a light skin tone
  • having light-colored eyes
  • being unable to tan
  • becoming sunburned easily
  • having atypical moles
  • having freckles
  • having nevi, which are discolored growths, on or near the eye
  • having genetic mutations that increase the risk of certain cancers
  • being an older adult

The exact cause of choroidal melanoma is currently unknown. Researchers believe that it may result from a combination of genetic and environmental factors.

Mutations in the DNA of ocular melanocytes can lead to a person developing ocular melanoma. However, further research is necessary to understand how and why this happens.

Choroidal melanoma may not cause any initial symptoms. An article in the journal Nature notes that 30% of people with choroidal melanoma have no symptoms.

When choroidal melanoma does cause symptoms, they can include:

  • blurred vision
  • photopsia, which is flashes of light in the vision
  • eye floaters, which are small dark spots or clear specks that float across the vision
  • loss of an area of vision in the visual field
  • visible tumors
  • pain
  • metamorphopsia, which is when straight lines appear to be curved
  • detached retina

Optometrists or ophthalmologists may detect ocular melanoma during routine dilated eye examinations. An ocular oncologist, a doctor specializing in eye cancers, can confirm this diagnosis.

Various tests help diagnose choroidal melanoma, including:

Biopsy

Biopsies involve taking a tissue or fluid sample from the potential cancer site.

During a biopsy for choroidal melanoma, a doctor inserts a thin, hollow needle into the eye. A person may receive a local or general anesthetic during this procedure.

However, doctors generally do not recommend biopsies to test for choroidal melanomas. Fine needle biopsies in this area can cause the cancer to spread to other parts of the eye.

Imaging tests

Imaging tests for choroidal melanomas include:

  • Ultrasound: An ultrasound uses sound waves to build an image of the inside of the body. This helps a doctor look for anything unusual inside the eye. When performing an eye ultrasound, the doctor runs a small instrument called a probe over or near the eyelid. In some cases, it is necessary for the probe to make contact with the eye.
  • Optical coherence tomography (OCT): OCT is a scan that uses light waves to produce cross-sections of a person’s eye. OCT scans can help detect the location and features of a choroidal melanoma. During an OCT scan, a person sits in front of the OCT machine while it scans the eye.
  • MRI: MRI uses strong magnetic fields and radio waves to create a picture of the inside of a person’s body. Doctors can use MRI to detect the invasion of choroidal melanoma into other tissues.

Fluorescein angiography

Fluorescein angiography involves a doctor injecting a dye into a person’s arm. This dye travels to the blood vessels of the eye. The doctor then uses a special camera to take photos of the eye, which should reveal any damage or tumors.

When a doctor determines the spread, or metastasis, of a person’s cancer, this is called staging. The ACS states that the most widely used staging systems are the American Joint Committee on Cancer (AJCC) TNM system and the Collaborative Ocular Melanoma Study (COMS) staging system.

The TNM system is based on:

  • the size and extent of the tumor (T)
  • the spread to nearby lymph nodes (N)
  • the spread to distant areas, called metastasis (M)

Doctors will add numbers, letters, or both after the T, N, and M to provide further information about the cancer. The higher the numbers, the more advanced the cancer.

Once a doctor has determined a person’s TNM categories, they can give them a stage grouping. Stage groupings for choroidal melanomas are stages 1, 2, 3, and 4.

The COM system of staging is simpler than the TMN system. It is based on the size of a person’s tumor:

  • Small: The tumor is 1–3 millimeters (mm) in height and 5–16 mm across.
  • Medium: The tumor is 3.1 to 8 mm in height and no larger than 16 mm across.
  • Large: The tumor is greater than 8 mm in height or larger than 16 mm across.

Doctors recommend different treatments for choroidal melanomas, depending on their size.

Small or medium choroidal melanomas

A small tumor may not require treatment unless it grows. Doctors may recommend a “watch-and-wait” approach.

If a small or medium choroidal melanoma does need treatment, the options may include:

  • Radiation therapy: This treatment uses radiation to destroy or shrink tumors. A form of radiation therapy called brachytherapy involves inserting radioactive material into the eye. A doctor removes this after a few days. Another option is proton therapy, which directs proton beams into the eye to destroy the tumor.
  • Laser therapy: A machine delivers beams of intense, focused light to the eye to destroy cancer cells.
  • Surgery: Surgery for choroidal melanomas can involve the removal of the affected tissue. If the eye has sustained a lot of damage, the surgeon may need to remove it entirely. This is called enucleation.

Large choroidal melanomas

The treatment for large choroidal melanomas usually involves radiation therapy or surgery. A surgeon may perform enucleation if the tumor:

  • takes up more than half of the eye socket
  • causes significant pain
  • has caused loss of vision

Learn more about proton therapy.

Generally, people with choroidal melanoma do not have a positive outlook. Research from 2021 reports that the median disease-free survival time for a person with choroidal melanoma is 26 months.

However, the outlook for a person with choroidal melanoma can depend on various factors, such as:

  • the person’s age
  • whether the cancer has spread
  • the size of the tumor

The liver is the most common area to which choroidal melanoma spreads. The disease spreads to the liver in about 50% of people with the condition. Following metastasis to the liver, the median survival time is 8 months.

Choroidal melanoma is a rare cancer affecting a person’s choroid. It is more likely to affect people with light skin and eyes.

Choroidal melanoma may not always cause symptoms, but when it does, they can include pain and vision problems.

The exact cause of choroidal melanoma is unknown. Researchers believe that the condition may be due to both environmental and genetic factors.

Choroidal melanoma is likely to metastasize to the liver, meaning that the outcome is generally not positive.

Early detection is vital for choroidal melanoma. If a person has any symptoms of the condition, they should see their doctor immediately. It is also important for people to undergo regular dilated eye exams to check their eye health, as choroidal melanoma does not always produce symptoms.