What is an intraocular melanoma?
An intraocular melanoma is a cancer inside the eye. Melanoma is the type of cancer and intraocular means inside the eye. There are many different types of melanomas that can occur inside the eye. The majority fall into two categories: uveal melanoma and orbital melanoma.
Uveal melanoma is more common than orbital melanoma. Primary orbital melanomas are very rare. A uveal melanoma is the most common primary intraocular malignant tumor in adults. Primary means that it originates in the eye itself. This is in comparison to a cancer from somewhere else that has then metastasized to the eye, such as breast cancer or lung cancer. While uveal melanoma may be the most common primary tumor of the eye, it is overall very rare. The risk of developing a uveal melanoma is around 1 in 5 million. Caucasians have the highest racial predilection for this type of cancer, and it is most likely to happen in someone’s 40’s and 50s.
The uvea refers to the specific parts of the eye called the choroid, ciliary body, and the iris. A uveal melanoma is a cancer that can occur in any one of these areas. The choroid is the most common location for it to occur. Because choroidal melanomas are only visible to an eye doctor on a dilated eye exam, many patients may not know they have this problem until they see an ophthalmologist. Overall, the likelihood of this happening is low, but it is still important to get a regular dilated eye exam.
A uveal melanoma is more likely to be seen by a patient if it happens in the iris of the eye. This is the colored part of the eye which gives people their eye color. Because patients can often detect any changes in their iris themselves, these melanomas are picked up earlier. Because of the early detection, the iris melanomas also tend to have the best prognosis.
Unfortunately, the percentage of people who develop metastatic disease after a diagnosis of uveal melanomas is quite high at around 50%. Once this disease has metastasized to other parts of the body, the prognosis is quite poor. A person may only live 6 months to 12 months after they have metastatic disease.
Intraocular melanoma symptoms
Choroidal melanomas may not have symptoms until they reach a certain size that causes visual disturbances. Some visual changes may include a decrease in vision, floaters, or visual field defects. If patients are being routinely screened by their ophthalmologist, then a choroidal melanoma may be picked up during a routine exam before it begins to cause any symptoms. Iris melanomas may be seen by the patient themselves when they look in the mirror. Patients may think that their eye color is changing and express this to their doctor.
Intraocular melanoma treatment
The decision on which treatment to choose for choroidal melanomas can be complicated. There are only a small number of ophthalmologists who specialize in this very specific area and it is important to consult with them to determine the best course of action for the disease. If a tumor is small and a patient’s projected life span is short, a conservative approach of monitoring the tumor may be done. If the doctor and patient decide to proceed with more aggressive treatment, this could involve enucleation or the placement of a radiotherapy plaque on the eye. Enucleation means the complete removal of the eye. Proton beam therapy has also been done in cases of choroidal melanoma. Overall, the specific course of treatment should be decided by an expert ophthalmologist who specializes in intraocular tumors. The main goal of treatment is to prevent metastasis as this tumor can be quickly fatal once it spreads to other parts of the body.
Sources:
https://eyewiki.org/Uveal_Melanoma
Chattopadhyay C, Kim DW, Gombos DS, et al. Uveal melanoma: From diagnosis to treatment and the science in between. Cancer. 2016;122(15):2299-2312.
https://pubmed.ncbi.nlm.nih.gov/26991400/
Adetunji MO, McGeehan B, Lee V, Maguire MG, Briceño CA. Primary orbital melanoma: A report of a case and comprehensive review of the literature. Orbit. 2021;40(6):461-469.
https://pubmed.ncbi.nlm.nih.gov/32900269/