Melanoma is commonly known as a type of cancer that affects the skin, but did you know it can affect other parts of the body, like the nails, mucosal tissue, and even the eyes? When melanoma starts in the cells in the eye that make pigment (melanocytes), it’s called ocular melanoma or uveal melanoma. Read on to find out the basics of ocular melanoma, seven ways this condition affects the eye, and how it can be treated.

What Is Ocular Melanoma?

Ocular melanoma usually develops in the eye’s middle layer — the uvea — which has three parts:

• The iris — The colored part of the eye
• The ciliary body — A circular structure that contains muscles and secretes a transparent liquid
• The choroid — A layer of blood vessels and connective tissue

Ocular melanoma is a rare type of melanoma but can be serious if it spreads to important organs of the body.

Ocular melanoma usually doesn’t cause symptoms early on and affects parts of the eye you can’t see, making it hard to detect. Sometimes ocular melanoma doesn’t cause symptoms at all. However, when symptoms do occur, they’re usually easy to detect since they can change how your eye looks or how you see.

Who Is at Risk of Ocular Melanoma?

Ocular melanoma is the most common type of eye cancer. However, it’s quite rare, affecting only 5 in a million adults. It is much less common than melanoma of the skin and makes up just 3 percent to 4 percent of all melanoma cases.

The exact cause of ocular melanoma is unknown, but it’s linked to certain risk factors including:

• Fair skin that gets sunburned easily
• Light-colored eyes
• Certain skin conditions, including dysplastic nevus syndrome (also called atypical mole syndrome)
• Family history of ocular melanoma or other cancers, which may be linked to a rare genetic mutation
• Older age, especially in the 60s and 70s

The prognosis (outlook) of ocular melanoma may depend on where it started and if it spreads. Ocular melanoma can spread to other important parts of the body, including the bones, lungs, and liver. This is called metastasis. About 50 percent of people with ocular melanoma will have metastasis 10 to 15 years after being diagnosed. Conjunctival melanoma — when melanoma affects the outer layer of the eye — is rare but can be life-threatening if the cancer spreads to organs like the liver, brain, and lungs.

Eye Symptoms of Ocular Melanoma

Sometimes ocular melanoma doesn’t cause noticeable symptoms, or it may take many years for symptoms to appear. For example, ocular melanoma usually doesn’t cause symptoms in the early stages. If and when symptoms do show up, they can be very noticeable. Below are seven ways ocular melanoma can affect vision and different parts of the eye.

1. Blurred or Double Vision

Ocular melanoma can cause blurred or double vision. When you have blurred vision, things look fuzzy or out of focus. Ocular melanoma in the ciliary body can cause changes in the lens (the clear part of the eye behind the iris that helps focus light) and lead to blurry vision.

Double vision refers to seeing two of the same image as if the image were copied and pasted right next to the original. For example, if someone held up two fingers, you would see four fingers.

Ocular melanoma can also cause distorted vision in which the straight lines of a grid appear wavy or blank.

2. Eye Floaters

Another symptom of ocular melanoma is the feeling of having something in your eye that you can see, like a speck of dust or what appears to be a cobweb or string. These spots in your vision are called eye floaters. You don’t actually have something in your eye — a floater is a glitch in your vision. Eye floaters may drift when you move your eyes or seem to rush away when you try to look at them.

3. Flashes of Light

Ocular melanoma can cause you to have a sensation of flashing lights in your eyes. These pinpricks in your vision can look like lightning streaks or shooting stars.

Flashes of light are caused by physical force on the retina. When ocular melanoma is in the uvea’s choroid, it can cause the retina — the lining at the back of the eye — to separate from the layer of blood vessels that provide necessary oxygen and nutrients. This can lead to flashes of light, floaters, and poorer vision.

4. Change in Pupil Shape

Another noticeable symptom of ocular melanoma is a change in the shape of the pupil. The pupil is the black circle in the center of your eye that’s surrounded by the colored iris. Ocular melanoma can cause the normally round pupil to lose its shape and look distorted.

5. Dark Spot on the Eye

Most of the time, ocular melanoma develops in a part of the eye you can’t see, so you might not know you have the condition. However, sometimes ocular melanoma causes a dark spot on the iris or conjunctiva — the thin, clear layer that protects your eye. The dark spot is easy to notice if you have light-colored eyes and may grow over time.

6. Reduced Vision

Ocular melanoma can also lead to reduced or even lost vision. For example, you may have a smaller field of vision (the entire area you can see around you when you look straight ahead) or a blind spot in your peripheral vision (the sides of your vision). You may need to turn your head or move your eyes more to see what’s around you. Reduced vision can be scary and affect your everyday life.

7. Bulging Eye

Ocular melanoma can also cause the eye to bulge or look like it's popping out. The eyeball may change position in the eye socket (the bony space that holds the eye, including its nerves and muscles). Bulging of the eye can look alarming, but it’s not common for this to happen.

Treatment for Ocular Melanoma

Treatment of ocular melanoma depends on many factors, including the size and location of the tumor, the stage of melanoma, and any symptoms. Treatment for ocular melanoma often involves radiation therapy or surgery. There’ve been advances in treatment for metastatic ocular melanoma — when ocular melanoma spreads — but there’s still no cure.

The goal of radiation is to kill cancer cells or keep them from growing or spreading to other parts of the body. As for surgery, how extensive it is depends on the size and location of the melanoma. For example, a small melanoma can be removed along with a bit of healthy tissue. If the melanoma is big or causes pain, the entire eye may need to be removed and replaced with an artificial eye. Both radiation and surgery may cause vision damage.

Other treatment options may include photodynamic therapy (a combination of medicine and certain wavelengths of light), laser treatment, and cryotherapy (cold treatment).

If you have or are at risk of melanoma, talk to your doctor right away if you experience any of the above eye symptoms. They may refer you to an ophthalmologist for tests, such as an eye exam or biopsy (taking a tissue or fluid sample to look at under a microscope), to figure out if ocular melanoma is the cause and recommend next steps.

Talk With Others Who Understand

MyMelanomaTeam is the social network for people with melanoma and their loved ones. On MyMelanomaTeam, people come together to ask questions, give advice, and share their stories with others who understand life with melanoma.

Have you been diagnosed with ocular melanoma? What eye symptoms do you have? Share your experience in the comments below, or start a conversation by posting on your Activities page.