Uveal melanoma is a rare malignant cancer, affecting seven people in every million each year.
What is uveal melanoma?
Uveal melanoma develops from cells called melanocytes, which are found in the uvea (the middle layer of tissue in the wall of the eyeball). The uveal tract is made up of the choroid, ciliary body and iris.
What is the cause of uveal melanoma?
There is no known cause of uveal melanoma and it is not related to sun exposure. However, uveal melanoma is more common in those who are fair skinned and have grey/blue eyes. The average age at which an ocular melanoma develops is 55-60. If diagnosed in younger patients, there may be an association with atypical (benign) moles or skin melanoma.
What are the symptoms of uveal melanoma?
For some people there may not be any symptoms and the tumour is found during a routine eye test. For others, it can cause visual disturbances such as flashing lights, blurred vision or a shadow in one eye.
What are the treatment options?
The appropriate treatment depends largely on the size and location of the melanoma, as explained below.
Ruthenium plaque brachytherapy
A ruthenium plaque is surgically placed on the surface of your eye to treat the tumour. The plaque is a curved metal disc, about the size of a ten pence coin, which contains radioactive material, called ruthenium, which is sealed within the disc and does not contaminate the rest of your body. The tumour is receiving a dose of radiation whilst the plaque is on the surface of your eye, therefore you have to stay in hospital for observation. A second operation is needed to remove the plaque before you can go home. The length of stay in hospital may vary from a few days to a week. The results can vary depending on the size of the tumour, but for small to medium sized uveal melanoma (tumour) there is a high success rate. Larger lesions carry a greater risk of complications, which can damage vision.
Proton beam radiotherapy
Proton beam radiotherapy is a specialist treatment undertaken at the National Proton Beam Centre in Clatterbridge, near Liverpool. Protons are hydrogen ions that are accelerated to a high energy level, using a very strong magnet so that they are able to penetrate the eye and target the tumour to a specific, clearly defined depth and area. The treatment is performed over four daily outpatient visits to Clatterbridge, with accommodation provided. Before going to Clatterbridge, an eye operation is performed in London, which involves attaching small metal clips to the wall of your eye. These clips help the specialists locate the tumour in your eye. The clips are harmless and do not need to be removed. The results of this treatment can vary depending on the size of the tumour, but for medium sized uveal melanoma there is a high success rate. Larger lesions carry a greater risk of complications, which damage vision.
Photodynamic therapy involves the slow injection of a drug, called visudyne (verteporfin), through a vein in your arm. Once the injection has been performed, a low power laser is shone into the eye, focusing on the area being treated for just over a minute to activate the visudyne. Photodynamic therapy is reserved for only the smallest sized tumour (choroidal melanoma). The success rate is lower than conventional ruthenium plaque brachytherapy or proton beam radiotherapy. Visual complications are rare.
Enucleation (removal of the eye)
We usually only consider removal of the eye if:
• Your tumour is too large to treat with ruthenium plaque brachytherapy or proton beam radiotherapy
• Your eye is already painful, due to high pressure inside the eye
• The tumour is growing through the wall of the eye
Exenteration (removal of the eye and surrounding tissue)
This is only considered if a large amount of tumour has grown through the wall of the eye and cannot be removed with an enucleation.
Local resection (surgical removal of the tumour)
Small melanomas near the front interior of the eye can occasionally be surgically removed under general anaesthetic. Additional ruthenium plaque brachytherapy is often recommended.
Iridectomy (surgical removal of iris melanoma)
Small melanomas on the iris (the coloured part of the eye) can occasionally be surgically removed under a general anaesthetic. Additional ruthenium plaque brachytherapy is often recommended