What Is Ocular Melanoma?

Ocular melanoma (eye melanoma) is a rare type of cancer that affects various parts of the eye, specifically the choroid, ciliary body, and iris. Although rare, it is the most common cancer of the eye in adults.

According to the American Cancer Society, the most recent estimates for eye cancer in the United States are:

  • 3,320 new cancers (mainly melanomas) of the eye and orbit (1,750 in men and 1,570 in women)
  • 400 deaths from cancers of the eye and orbit (220 in men and 180 in women)

Read on to learn more about the symptoms, causes, diagnosis, and treatment of ocular melanoma.

A female ophthalmologist uses a phoropter to check a male patient’s eyes

Thomas Northcut / Getty Images

Types of Ocular Melanoma

Melanoma is a type of cancer that develops from cells called melanocytes. Melanocytes give the skin its pigment (color). Melanoma usually develops in the skin, but because there are melanocytes in different parts of the body, it can start in other places, such as the eye.

Most eye melanomas form in the area of the eye called the uvea, which includes the iris, ciliary body, and choroid. This is called uveal melanoma. While it is the most common type of cancer of the eye, it is still rare with an incidence of 5.1 cases per million people per year.

Very rarely, melanoma starts in the conjunctiva, which is the outer lining of the eye. This is called conjunctival melanoma.

Ocular Melanoma Symptoms

Occular melanoma does not always cause symptoms. Sometimes it is found by an eye doctor during a routine eye test.

Signs and symptoms of ocular melanomas can include:

  • Having trouble seeing
  • Losing part of the field of vision
  • Seeing flashes of light
  • Seeing spots, squiggly lines, or floating objects (floaters)
  • Having a dark spot on the iris (the colored part of the eye)

Less serious conditions can also cause many of these symptoms. For example, floaters can happen as part of the aging process. Still, make sure to tell your doctor if you have these symptoms.

Causes

It is not clear what causes ocular melanomas, but there are risk factors that can increase your chances of developing one.

Known ocular melanoma risk factors include:

  • Eye color: People with light-colored eyes are somewhat more likely to develop melanoma of the eye than people with darker eyes and skin color.
  • Age and gender: Eye melanomas can occur at any age, but the risk goes up as people get older. Eye melanoma is also slightly more common in men than in women.
  • Race/ethnicity: White people are more susceptible to ocular melanoma than people of other races/ethnicities.
  • Inherited conditions: People with dysplastic nevus syndrome have many abnormal moles on the skin. They are at an increased risk of skin melanoma and also seem to have a higher risk of developing melanoma of the eye.
  • Moles: Different types of moles (nevi) in the eye or on the skin have been associated with an increased risk of uveal ocular melanoma.

Too much exposure to sunlight or tanning beds is a known risk factor for skin cancer and has been proposed as a possible risk factor for melanoma of the eye.

Diagnosis

Undergoing regular eye tests with a doctor who specializes in eye treatment (an ophthalmologist or optometrist) is the best way to find ocular melanoma early.

Your doctor will ask if you are having any symptoms, check your vision, and check every physical part of the eye for abnormalities. This may include a slit lamp eye exam (an instrument where high-intensity light is shone into the eyes) and a dilated retinal exam (where drops are applied to the eyes to dilate the retina).

If an eye doctor thinks that you may have ocular melanoma, there are several tests they can use to make the diagnosis.

Tests that can be used to diagnose ocular melanoma include:

  • Eye examination: The eye doctor looks at the inside of your eye using a small, handheld lens and light called a binocular indirect ophthalmoscope. The doctor will also look for enlarged blood vessels on the outside of the eye, which can be a sign of a tumor inside the eye.
  • Ultrasound scan: An ultrasound scan uses sound waves to build up a picture on a computer screen of the inside of your eye and nearby areas. The doctor gently presses a small probe against your closed eyelid and moves it over the skin. 
  • Fluorescein angiography: The doctor injects a dye, called fluorescein, into a vein in your arm. They then use a special camera to take photos of the dye as it moves through the blood vessels at the back of your eye. The doctor takes several quick pictures of the eye.

If your doctor thinks that cancer has spread beyond the eye, other tests—like an MRI or CT scan—can be done. The liver is one common site of metastasis (spread) for ocular cancer.

For most types of cancer, the diagnosis is made by removing a small piece of the tumor, called a biopsy, and looking at it in a lab. However, a biopsy is not usually needed to diagnose eye melanomas, since most cases can be accurately diagnosed by an eye exam and imaging tests. 

Treatment

The main factors when deciding about treatment for eye melanoma include the location and size of the tumor, as well as the likelihood of saving vision in the affected eye. 

Your treatment options will also depend on whether cancer has spread to other areas of the body, the possible side effects, and your overall health.

Watchful Waiting

Not all eye melanomas grow quickly and need to be treated right away. Therefore, observation (or watchful waiting) is sometimes recommended.

In some cases, it’s hard for a doctor to be sure that a spot is truly a melanoma. If the tumor is very small, watching it closely and treating it only if it starts to grow can be the best approach.

Surgery

Eye surgery is common in the treatment of ocular melanoma. During surgery, an ophthalmologist will remove parts or all of the affected eye depending on the size and spread of the tumor.

Surgical options include:

  • Iridectomy: Removal of part of the iris
  • Iridocyclectomy: Removal of part of the iris and ciliary body
  • Sclerectomy/endoresection: Removal of the choroidal tumor while keeping the eye
  • Enucleation: Removal of the eye

Radiation Therapy

Radiation therapy is another common treatment for ocular melanoma. It might be the only treatment, or it can be combined with surgery.

There are two types of radiation therapy: external and internal. Both use specific types of energy to disrupt the activity of cancer cells and eliminate them, as well as to prevent them from undergoing cell division.

Laser Therapy

This procedure uses heat in the form of a laser to shrink a smaller tumor. It’s also called thermotherapy or transpupillary thermotherapy (TTT).

Laser therapy potentially has fewer side effects than surgery or radiation therapy, but can also be combined with radiation therapy.

Does Ocular Melanoma Spread?

Most uveal melanomas are only within the eye when they are first diagnosed. It is rare for this form of cancer to have already spread outside of the eye when it is spotted.

In about half of all patients, the melanoma will come back after treatment (recurrence). Cancers that recur within the eye are usually treated by removing the eye.

When melanoma recurs outside the eye, it most often comes back in the liver. It might also come back in other areas, like the lungs or bones. These cancers are often hard to treat.

Prognosis

The prognosis for melanoma of the eye depends on how big the cancer is when it is diagnosed and which parts of the eye are affected.

The overall five-year survival rate for eye melanoma is 82%. When melanoma has not spread outside the eye, the five-year relative survival rate is about 85%.

The survival rate for people with cancer that has spread to nearby structures or lymph nodes is 71%. If the melanoma has spread to distant parts of the body, the survival rate is 13%. However, very few cases of eye cancer are diagnosed at this late stage.

Summary

Ocular melanoma is a type of cancer that affects the eye. It’s often found during a routine eye exam. Sometimes, ocular melanoma can spread to other parts of the body as well, most often the liver. The treatment will depend on individual factors, but can include medication, surgery, or a combination of methods.

A Word From Verywell

The best way to catch ocular melanoma early and treat it before it has a chance to spread is by having regular eye checkups and reporting any changes in vision to your eye doctor or primary care doctor.

Treatment for ocular melanoma can be very effective, especially when it’s found early. According to the American Cancer Society, if the melanoma has not spread beyond the eye, the relative survival rate is 85%.

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