Intraocular (Uveal) Melanoma: What You Need to Know
Melanoma is usually associated with the skin, but the term melanoma itself refers to cancer that develops in pigment cells called melanocytes. These cells are mostly found in the skin, but are also in other areas of the body, such as the middle layer of the eye, the inner ear, the bones, and the heart. When cancer starts in the melanocyte cells in the middle eye, called the uvea, it is called intraocular, or uveal, melanoma. This is a rare cancer, but it is also the most common cancer of the eye, accounting for between 3 and 5 percent of all melanomas, according to the 2017 study, "Uveal melanoma: epidemiology, etiology, and treatment of primary disease."
The Middle Eye
The middle eye is made up of three layers:
The iris is the colored area at the front of the eye.
The ciliary body is the ring of tissue that is responsible for changing the size of the pupil and the shape of the lens. It is located behind the iris.
The choroid are blood vessels that bring oxygen and nutrients to the eye.
Around 90 percent of intraocular cancers first develop in the choroid, according to the American Cancer Society. These cancers are larger and more likely to spread to other areas than those that begin in the iris.
Warning Signs and Symptoms
About 30 percent of people never experience any early symptoms of intraocular melanoma, according to the American Academy of Ophthalmology (AAO). They might be diagnosed during a routine eye exam or an eye doctor might recommend they see a specialist because of potential signs of cancer. The National Cancer Institute lists some of the warning signs as:
Dark spot on iris
Floaters, which are spots that drift into your field of vision
Flashes of light
Change in size or shape of your pupil
Change in the position of the eyeball in the eye socket
During the course of the disease, some people experience complications, such as bulging eyes, a change in the color of the iris, poor vision, changes in vision or vision loss, retinal detachment, or red, painful eye.
About 2,500 new cases of intraocular cancer are diagnosed each year. It was previously thought that it was caused by excessive sun exposure; research has not found a direct link to support that, although those with fair skin and blue eyes are most at risk, according to the Ocular Melanoma Foundation. The exact cause is not yet understood.
Diagnosis of Intraocular Melanoma
An ophthalmologist can often diagnose intraocular melanoma based on appearance, photographs, and ultrasound pictures, according to the Ocular Melanoma Foundation. Some of the tests used include:
Eye exam with dilated pupil that allows doctor to look through the lens and pupil to the retina
Ultrasound of the eye
High resolution ultrasound biomicroscopy
Transillumination of the globe and iris
Indocyanine green angiography
Ocular coherence tomography
Intraocular tumors are described as small, medium, or large.
Small indicates the tumor is 5 to 16 mm in diameter and 1-3 mm thick.
Medium indicates the tumor is 16 mm in diameter or less and 3.1 to 8 mm thick.
Large indicates the tumor is any diameter or more than 16 mm in diameter and at least 2 mm thick.
A biopsy is rarely needed and can cause complications. Biopsies can sometimes result in retinal detachment, which is corrected by surgery. If you are diagnosed with intraocular melanoma, your doctor may request additional tests to see if the cancer has spread to other parts of the body.
If diagnosed early, your doctor might suggest what is called “watchful waiting.” This means you will have periodic exams to closely monitor your condition. Your doctor may recommend further treatment if the situation changes.
The most common treatment for intraocular melanoma is surgery, according to the National Cancer Institute. Depending on the size of the tumor, your doctor will remove the tumor and surrounding tissue, which can include the eye and part of the optic nerve or the eye, eyelid, muscles, nerves, and fat in the eye socket.
Some other modes of treatment include:
Radiation therapy, which uses radiation to kill cancer cells
Photocoagulation, also called light coagulation, which uses lasers to destroy blood vessels that bring nutrients to the tumor
Thermotherapy, which uses heat from a laser to destroy cancer cells
The medication aldesleukin (Proleukin) has been approved by Food and Drug Administration for treatment, according to National Institutes of Health, and ongoing studies are researching different immunotherapy and chemotherapy options to treat this disease, according to the AAO.
About 50 percent of those diagnosed with this cancer will develop metastases by 10-15 years after diagnosis. Some people will live for 20 to 25 years before metastases. There is a 6- to 12-month average survival after metastases.