What is choroidal melanoma?
Choroidal melanoma is cancer that affects the part of the eye. It develops in the sponge-like choroidal layer at the back of the eye, between the sclera (the white of the eye) and the retina. (The retina is a light-sensitive structure at the back of the eye that sends visual information to the brain.) The choroid abounds in the blood vessels and supplies nutrients to the retina.
Over time, many choroidal melanomas expand and secrete the retina. This can lead to loss of vision. Tumors can also spread to other parts of the body (metastasize). The liver is the most common site of metastasis. If it spreads, this cancer (choroidal melanoma) is fatal.
Although choroidal melanoma is very rare, it is the most common eye cancer in adults. It usually occurs in middle-aged or older people. Melanomas usually appear on the skin. But choroidal melanoma also develops in areas where the pigment melanin is present in some cells. The choroid is one such example.
What parts of the eye are affected by melanoma?
Primary ocular melanoma can be divided into 2 types:
- Uveal melanoma: Arise within the iris, choroid, and ciliary body. These are the most common forms of ocular melanoma, occurring consistently at a rate of 7 per million per year in the US Most cases (more than 90%) involve choroids. It contains approximately 6% ciliary body and 4% iris.
- Conjunctival melanomas: They occur less frequently as the incidence increases. Conjunctival melanoma occurs in less than 5 cases per million per year.
Who gets ocular melanoma?
Ocular melanoma occurs equally in men and women. The maximum incidence of the show is close to 62 years. People at high risk for ocular melanoma are Caucasian and have fair skin and pale iris colour. However, melanoma can also affect people with darker skin and eye colour. Melanosis, congenital ocular melanocytosis, and neurofibromatosis are also associated with an increased risk.
Most patients with conjunctival melanoma have melanocytes in the umbilicus (moles). About 20% is expected to arise from the umbilicus and 60-75% from conjunctival melanosis.
Causes of choroidal melanoma
The cause of ocular melanoma is unclear.
Doctors know that ocular melanoma occurs when there are defects in the DNA of healthy eye cells. DNA defects tell cells to grow and multiply under control, so mutated cells often survive when they die. The mutant cells accumulate in the eye and form an ocular melanoma.
Ocular melanoma occurs
Ocular melanoma usually develops in the cells of the middle layer (uvea) of the eye. The uvea has three components, each of which is affected by ocular melanoma:
- Iris, which is the coloured part in front of the eye
- The choroidal membrane, which is the membrane of the blood vessels and connective tissue between the sclera and the retina behind the urethra.
- The ciliary body, which is in front of the urethra and secretes a clear liquid (aqueous humor) into the eye.
- Ocular melanoma also occurs in the front of the eye (conjunctiva), in the socket around the eyeball, and on the eyelid, although this type of ocular melanoma is very rare.
Risk factors for choroidal melanoma
The goal of choroidal melanoma treatment is to detect the tumor early, thus reducing metastasis. When a doctor finds a small borderline tumor, be it a benign nevus or a cancerous melanoma, there are risk factors identified and published by the oncology service at Wills Eye Hospital, which can be used to diagnose minor melanoma.
These factors include thickness greater than 2 mm, subcutaneous fluid, symptoms, orange pigment, tumor margin near the optic disc, absence of chronic drusen, absence of surrounding cavity, and holiness on ultrasound. These risk factors are crucial in determining the malignant potential of a small pigmented choroidal tumor.
Diagnosis for choroidal melanoma
Most cases of choroidal melanoma are found on a routine dilated eye exam. During this test, the ophthalmologist will examine the students to examine the back of the eye. Most of the time, no other tests are needed. But special tests can confirm the diagnosis. These tests include:
- Ultrasound: A small probe placed over the eye directs the sound waves at the tumor. A machine records the patterns the waves make as they bounce off the tumor.
- Fluorescein angiography: A fluorescent dye is injected into the vein in your arm. The pupil takes a quick sequence of photos as the color passes through the veins at the back of the eye.
- Once choroidal melanoma is diagnosed, magnetic resonance imaging (MRI) may be ordered. This can help doctors better assess the symptoms of the tumor.
- Pictures of the blood vessels in and around the tumor (angiogram). During an angiogram of your eye, a pigment is injected into a vein in your hand. The colour travels to the blood vessels of the eye. The camera with special filters to detect colour takes several minutes of flash images every few seconds.
- The optical coherence tomography: The imaging test creates images of parts of the uveal tract and the retina.
Removal of suspicious tissue samples for analysis. In some cases, your doctor may recommend a procedure to remove a tissue sample (biopsy) from your eye. To remove the pattern, a fine needle is inserted into the eye and used to remove suspicious tissue. The tissue is analyzed in a laboratory to determine if the eye contains melanoma cells. An eye biopsy is generally not required to diagnose ocular melanoma.
Determine if cancer has spread
Your doctor may recommend additional tests and procedures to determine if the melanoma has spread (metastasized) to other parts of your body. Exams may include:
Tests to measure liver function:
- Chest x-ray
- Computed tomography (CT)
- Magnetic resonance imaging (MRI) scan
- Abdominal ultrasound
- Positron emission tomography (PET)
Choroidal melanoma treatment
The management and treatment of choroidal melanoma depend on the size of the tumor. If the tumor is small, it can be controlled. If it increases, start treatment. Ocular melanoma treatment options depend on the location and size of the ocular melanoma, as well as your general health and preferences. Waiting for treatment for small eye melanoma
Small eye melanoma does not require immediate treatment. If the choroidal melanoma is small and growing, you and your doctor may choose to wait and watch for signs of growth. If choroidal melanoma develops or causes problems, you can seek treatment at that time.
Radiation therapy uses high-energy energy, such as protons or gamma rays, to kill cancer cells. Radiation therapy is commonly used for small to medium-sized eye melanoma.
Radiation is generally called direct tumor brachytherapy by placing a radioactive film in the eye. The panel was placed with temporary strips. The plate looks like a bottle cap and contains many radioactive seeds. The plate remains intact for four to six days before removal.
Radiation, like proton beams, can also come from a machine that directs radiation at the eye (external beam radiation or teletherapy). This type of radiation therapy is often done over several days.
Laser treatment to kill melanoma cells may be an option in some cases. One type of laser treatment, called thermotherapy, uses an infrared laser and is sometimes used in combination with radiation therapy.
Photodynamic therapy combines drugs with a specific wavelength of light. The medicine drug exposes cancer cells. This treatment damages the vessels and cells that make up ocular melanoma. Photodynamic therapy is used in small tumors because it is not effective for large cancers.
Extreme cold (cryotherapy) can be used to destroy melanoma cells in some small-eye melanomas, but this treatment is not commonly used.
Operations used to treat ocular melanoma include procedures that remove part of the eye or remove the entire eye. The procedure you undergo depends on the size and location of your eye melanoma. Options can include:
- Surgery to remove a small area of melanoma and healthy tissue. Surgery to remove the melanoma and the healthy tissue around it is an option for treating minor melanoma.
- Surgery to remove the entire eye (wrap). Nucleation is often used for large eye tumors. It can also be used if the tumor is causing eye pain.
Once the melanoma eye is removed, an implant is inserted in the same position and the muscles that control eye movement are attached to the implant, allowing the implant to move.
After you have spent some time healing, an artificial eye (prosthesis) is made. The surface in front of your new eye will be custom painted to fit your current eye.