Diagnosing Intraocular Melanoma
Specialists at NYU Langone are experienced in diagnosing intraocular melanoma. This rare cancer begins in pigment-producing cells called melanocytes inside the uvea, the middle layers of the eye. These layers are sandwiched between the sclera, the white part of the eye, and the retina, a thin layer of tissue that lines the inner surface of the eye.
The front of the uvea is called the iris, which is the pigmented part of the eye that surrounds the pupil—the black opening in the center of the iris that lets in light. The ciliary body, located in the middle of the uvea, is a thin ring of tissue that adjusts the size of the lens. The back portion of the uvea is called the choroid. It contains blood vessels that nourish the retina.
Melanomas can begin in any of these areas, but most occur in the choroid. As a result, intraocular melanoma is sometimes called choroidal melanoma, even when it affects other structures in the uvea.
Iris melanomas are usually visible and are typically discovered when they are small and have not spread to other parts of the body. In contrast, intraocular melanomas located behind the iris—in the ciliary body or choroid—can spread to the liver, bones, skin, lungs, and brain.
At NYU Langone, most intraocular melanomas are detected when they are small and can be treated effectively with vision-sparing therapies.
Causes and Risk Factors of Intraocular Melanoma
Doctors don’t know exactly what causes intraocular melanoma, but many people who develop it have a fair complexion—light-colored skin with freckles that burns easily when exposed to sunlight—and blue or green eyes. Those who spend a lot of time in the sun have a higher risk, because ultraviolet rays can damage melanocytes.
People with an inherited skin condition called dysplastic nevus syndrome, which causes them to develop a large number of unusually shaped moles, or nevi, are at increased risk of developing intraocular melanoma. Those born with a blue or gray nevus in the eye, sometimes called Nevus of Ota, also have a higher risk of developing this type of cancer.
Intraocular tumors tend to spread more quickly in people over age 60. Researchers suspect that having a weakened immune system due to aging may prevent the body from effectively fighting these tumors. This is why doctors at NYU Langone work with integrative health specialists to help decrease your stress and support your immune system.
Signs and Symptoms of Intraocular Melanoma
An iris melanoma may look like a dark spot, discoloration of the iris, or change in the size and shape of the pupil. However, most intraocular melanomas are only visible through an eye exam and cause few or no symptoms.
If the tumor is located in the macula, or center, portion of the retina or is very large, you may notice a change in vision, flashes of light, or floaters, which are spots that drift across your field of vision. These symptoms occur if the tumor causes the retina to detach from the uvea. In these instances, doctors at NYU Langone attempt to reattach the retina and preserve your vision.
Because melanomas in the iris are usually visible, they are more likely to be detected when they’re small and are less likely to spread. In contrast, melanomas that begin in the ciliary body or choroid are often discovered when they’re larger and have a greater potential to spread.
Eye cancer experts at NYU Langone recommend yearly eye exams for people with risk factors for intraocular melanoma, such as unusual nevi or occupations that expose their eyes to ultraviolet light. Early detection saves lives because intraocular melanomas can be discovered during a routine eye examination, when they are small and more treatable with vision-sparing radiation therapy.
If your doctor suspects a tumor, he or she may perform eye and imaging tests to diagnose intraocular melanoma. The doctor orders additional tests to determine if a tumor has spread.
Before an eye exam to diagnose intraocular melanoma, an ophthalmic oncologist, or eye cancer specialist, uses eye drops that dilate, or widen, your pupil. This helps your doctor view the inside of the eye. After your pupil has been dilated, the doctor uses different instruments to examine the uvea.
During ophthalmoscopy, the doctor uses a lighted instrument called an ophthalmoscope to examine the retina and the choroid. Ophthalmoscopy can be used to identify an orange pigment, called lipofuscin, which arises from the breakdown of tissue in the retina or the tumor itself. Ophthalmologists may also use this technique to estimate the tumor’s width and look for signs of retinal detachment.
In slit-lamp examination and fundoscopy, a low-power microscope and a thin beam of light are used to view the size of a tumor located toward the front of the uvea, such as the iris. This technique enables doctors to identify abnormal blood vessels, distortion of the pupil’s size and shape, pigment changes in the eye, or other signs of tumors.
Doctors may use gonioscopy to identify tumors hidden where the iris attaches to the eye. In this technique, the doctor uses a mirrored lens to determine if the tumor has spread to the area where the iris meets the ciliary body—the place that normally drains fluid from the eye.
Eye cancer specialists at NYU Langone use ultrasound imaging to view and measure tumor dimensions. Ultrasound is particularly helpful when tumors are not visible with an ophthalmoscope or other eye exam techniques.
High-frequency ultrasound uses ultra-short sound waves to view tumors in the front of the eye, including the iris and ciliary body. Low-frequency ultrasound, which emits longer sound waves, is typically used to view tumors in the choroid, or back of the eye, and look for signs of retinal detachment.
During an ultrasound, the doctor numbs the eye with drops. Next, he or she places a small probe called a transducer on the surface of the eye, on your eyelid, or in a small cup of water over your eye. The probe emits and collects sound waves that bounce off structures in the eye, providing detailed information about a tumor’s size, shape, and reflectivity. A tumor that does not reflect, or bounce, many sound waves usually indicates that it is a melanoma, rather than a tumor that has spread from elsewhere in the body.
This procedure is not painless, but is only slightly uncomfortable.
In transillumination, the doctor shines a bright light onto the eyeball. This technique is used to measure tumors in the ciliary body. In a healthy eye, the light easily penetrates tissues of the eyeball. When a ciliary body melanoma is present, however, the light is blocked in the area of the tumor. The resulting dark area or shadow is evaluated to determine a tumor’s shape and measure its size.
Fluorescein angiography is a technique for evaluating blood vessels in the eye. The doctor injects an orange, fluorescent dye into a blood vessel in your arm. The dye travels to and highlights blood vessels in the eye and tumor.
Fluorescein angiography enables doctors to identify leaking blood vessels, new blood vessels, or a retinal detachment caused by a tumor. As the dye circulates through the tumor, the doctor takes pictures of the inside of the eye with a specialized camera.
Optical Coherence Tomography
In optical coherence tomography, laser light creates cross-sectional images of the iris, retina, and choroid. This imaging technique is most sensitive for finding a leakage beneath and within the retina or a retinal detachment, which can occur if a tumor is growing in this part of the eye. These findings help your doctor diagnose a choroidal melanoma.
Imaging After Diagnosis
Additional imaging tests may be used to determine if the intraocular tumor has spread beyond the eye to other parts of the body. Depending on the size and location of the tumor, our doctors may recommend imaging tests immediately after diagnosis to help plan for treatment. Others may be used during follow-up appointments to assess tumor growth.
Because intraocular melanomas can spread to the liver, skin, bone, and other areas of the body, eye cancer specialists at NYU Langone usually perform a total body PET/CT scan. This imaging test measures the metabolic activity of the intraocular tumor, which indicates how rapidly it is growing. It is also used to determine if the tumor has spread to other parts of the body, which affects your treatment plan.
During the PET portion of the scan, a radiologist injects a small amount of radioactive glucose, or sugar, into a vein. This substance collects in tumor cells, which are detected by a computer. The computer creates three-dimensional images that show the metabolic activity of any known or newly discovered tumors.
The CT portion of the scan enables the doctor to identify and measure tumors that have spread to other parts of the body. A CT scan is a type of X-ray that uses a computer to create three-dimensional, cross-sectional images of organs and structures in the body.
The radiologist may perform a CT scan with a contrast agent, a dye injected into a vein to create a clearer picture.
An MRI scan uses a magnetic field and radio waves to create computerized, three-dimensional images of organs such as the liver to determine if an intraocular melanoma has spread. Before an MRI, your doctor may give you a contrast agent via injection to enhance the images.
After the primary, or original, melanoma has been treated, doctors at NYU Langone recommend an MRI with contrast twice a year for the first four years after diagnosis, then once a year for the next six years or longer.
Because an MRI does not contain radiation, it is safe to repeat this test frequently. An MRI scan cannot be given to people who have an implantable pacemaker, other metallic devices in their bodies, or kidney problems that would prevent the contrast agent from being eliminated.
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