Melanoma of the eye (ocular melanoma)
This information is about a rare type of cancer called ocular melanoma (melanoma of the eye). You may also find it helpful to read our general information about malignant melanoma.
- What is ocular melanoma?
- Causes
- Signs and symptoms
- How it is diagnosed
- Treatment
- Conjunctival melanoma
- Research trials
- Follow-up
- Your feelings
What is ocular melanoma?
Ocular melanoma is melanoma of the eye. Melanoma is a cancer that develops from cells called melanocytes. Melanocytes produce the dark-coloured pigment melanin, which is responsible for the colour of our skin. These cells are found in many places in our body including the skin, hair, and lining of the internal organs, including the eye.
Most melanomas begin to grow in the skin, but it is also possible for a melanoma to begin in other parts of the body, such as the eye.
Within the eye itself, melanoma can develop in one of several places. Uveal melanoma is the most common type of ocular melanoma. This means it occurs along the uveal tract (the darker ring on the diagram) of the eye, which includes the choroid, ciliary body and iris.
The choroid is part of the lining of the eyeball and is dark-coloured (pigmented) to prevent light being reflected around the inside of the eye. The ciliary body extends from the choroid and focuses the eye by changing the shape of the lens. The iris is the clearly visible coloured disc at the front of the eye, which controls the amount of light entering the eye. All these structures are heavily coloured with melanin.
Melanoma can also occur in the thin lining over the white part of the eye (the conjunctiva) or on the eyelid, but this is very rare.
Ocular melanoma is the most common type of cancer to affect the eye, although, generally, it is still quite rare. Approximately 500 new cases of ocular melanoma are diagnosed in the UK each year. The incidence of ocular melanoma increases with age, and most cases are diagnosed in people in their 50s.
Causes
This is a rare type of tumour and, as for many other forms of cancer, the exact cause is unknown. It is known that exposure to ultraviolet (UV) rays (either from the sun or sunbeds) increases the risk of developing melanoma of the skin. People whose skin burns easily are most at risk: typically, people with fair skin, fair or red hair and blue eyes. However, it is not yet known whether or not there is any link between UV ray exposure and the development of melanoma of the eye.
Ocular melanoma may be more common in people who have atypical mole syndrome, which is also called dysplastic naevus syndrome. People with this condition have a greater risk of developing a melanoma of the skin, and often have over 100 moles on their body, some of which are abnormal in size and shape.
Signs and symptoms
Symptoms include blurred vision, flashing lights, shadows and misting of the lens of the eye (cataract). Often, no symptoms are noticed and an ocular melanoma may be diagnosed by an optician during a routine sight test.
All of these symptoms are common to other conditions of the eye, but it is generally possible for an eye specialist (ophthalmologist) to diagnose these tumours quite simply and painlessly. Occasionally, a small sample of tissue needs to be taken and examined (biopsy), to confirm a diagnosis.
How it is diagnosed
A number of tests may be done to diagnose ocular melanoma, including:
Ophthalmoscopy A small hand-held microscope (ophthalmoscope), similar to those used by opticians during routine eye tests, is used to look at the inside of the eye. This is likely to be the first test that you have.
Ultrasound scan A small device which produces sound waves is rubbed over the skin around the eye area. The echoes are then converted into a picture by a computer.
Colour fundus photography Photographs of the back of your eye (fundus) will be taken, and can help to show what the tumour looks like before and after treatment. For the test, your pupil will be dilated using eye drops, and a special camera will be used to take a picture of the fundus.
Fluorescein angiography A special dye, called flourescein, is injected into a vein in the arm. In a few seconds, the dye travels to the blood vessels inside the eye. A camera with special filters that highlight the dye is used to photograph the flourescein as it circulates through the blood vessels in the retina and choroid.
CT (computerised tomography) scan A CT scan takes a series of x-rays to build a three-dimensional picture of the inside of the head. The scan is painless but takes 10 minutes. It may be used to find the tumour within the eye, or to check for any spread of the disease.
MRI (magnetic resonance imaging) scan This type of scanner uses magnetism instead of x-rays to form a series of pictures of the inside of the head. The test can take about 30 minutes. It is completely painless, but some people feel a bit claustrophobic during the scan. It is also noisy and you will be given earplugs or headphones to wear.
Biopsy A small sample of tissue may be taken from the suspicious area and examined under a microscope. However, this is not necessary for most ocular melanomas, because they have a distinctive appearance and can usually be recognised easily from the x-rays and scans.
Treatment
A number of different treatments are used for ocular melanoma, depending on the size, cell type and position of the tumour, as well as other factors such as your general health, age and level of vision in both eyes. The aim of the treatment is to destroy the cancer cells, stop the cancer coming back, and to save as much of your vision as possible.
Some of the treatments for melanoma of the eye are very specialised, and only available at a few hospitals in the UK, so you may find that you have to travel to one of these centres for your treatment
Radiotherapy
This type of treatment uses high-energy rays to destroy the cancer cells, while doing as little harm as possible to normal cells. Radiotherapy may be given either from outside the body (external radiotherapy) or from within (internal radiotherapy). Radiotherapy may be the only treatment, or it may be given after surgery. Recent developments in radiotherapy have made it possible to preserve sight in the eye, either completely or partly.
External radiotherapy In external radiotherapy a beam of radiation is directed to the area of the tumour. The treatment is normally given as small doses, called fractions, over a few days. Different types of radiotherapy machines can be used. One, called a Cyclotron, is specifically used to treat eye tumours. This machine directs a proton radiation beam precisely at the affected area, causing as little radiation exposure as possible to the surrounding healthy eye tissue. Before the treatment, a minor operation is carried out to attach small metal tags to various parts of the eye. The tags act as markers for the radiation beam.
Internal radiotherapy This treatment is given by placing a radioactive source (called a plaque) close to the tumour. This normally involves a stay in hospital of up to a week. Using a local anaesthetic to numb the eye and sedation to make you feel relaxed, the radioactive plaque is placed close to the tumour in the eye. A general anaesthetic can also be used if preferred. Another operation is carried out to remove it when the treatment is finished.
Certain precautions need to be taken while the plaque is in your eye. You will need to stay in one room and each member of staff and your visitors will only be allowed in for a short time each day. This is to reduce any unnecessary exposure to radiation. Once the radioactive source is removed, no precautions will be necessary, as the radiation will no longer be present.
Transpupillary thermotherapy (TTT)
This can be used to treat very small ocular melanomas, or as an additional treatment after radiotherapy. The tumour is heated with a special type of laser beam. Cancer cells are more susceptible to heat than normal cells and so will be destroyed. Several treatments are normally needed.
Surgery
Depending on the size and position of the tumour, it may be possible to remove it without needing to remove the eye. However, if the cancer is growing rapidly, is large or painful, removal of the eyeball may be the most appropriate treatment for you. This is called enucleation.
For many people, this suggestion can be quite shocking and a lot of discussion may be needed with the doctors involved before the decision to go ahead is taken. You can have an artificial eye (prosthesis) made that matches your remaining eye. An implant can be inserted which makes the artificial eye move realistically.
Surgery for melanoma of the eye is usually done using a local anaesthetic and sedation to relax you. A general anaesthetic can also be used.
Conjunctival melanoma
Melanoma affecting the thin lining over the white part of the eye (the conjunctiva) is rare. Some conjunctival melanomas may be due to sun exposure (and in this way they are like those of the skin which are more common in people with fair colouring and pale eyes who burn more easily in the sun). However, most conjunctival melanomas develop from a condition called primary acquired melanosis (PAM), which causes brown/dark patches (pigmentation) on the conjunctiva. Sometimes the melanoma will develop from an existing freckle or mole on the conjunctiva. Any new pigmentations, or changes to an existing area, should be checked with your doctor.
A conjunctival melanoma is diagnosed by taking a small sample of cells (a biopsy) from the pigmented area. If a melanoma is diagnosed, the abnormal area (and a margin of healthy cells around it) will be removed during a small operation. The surgery may be followed by treatment called cryotherapy. This involves freezing the area to kill any melanoma cells that may have been left behind after the surgery.
If the melanoma is quite large, it may sometimes be necessary to completely remove the conjunctiva as well as the eyeball. This is a rare operation, called an orbital exenteration. After this type of surgery you will need a facial prosthesis (false part), which covers the eye socket and contains false lids, lashes and an artificial eye. The eye will not be able to move. The prosthesis can be mounted on to a pair of glasses, or fixed onto the face with special glue, or rarely, with studs that are fixed in the bone around the eye socket.
The thought of this operation can be very distressing and you may need to spend time talking it through with your doctor or specialist nurse. They will discuss it very carefully with you and answer any questions you may have. Ongoing support will be available from doctors, counsellors and patient support groups to help you cope at this difficult time.
Research trials
Research into treatments for ocular melanoma is ongoing and advances are being made. Cancer doctors use clinical trials to assess new treatments. Before any trial is allowed to take place an ethics committee must have approved it and agreed that the trial is in the interest of patients.
You may be asked to take part in a clinical trial. Your doctor must discuss the treatment with you so that you have a full understanding of the trial and what it involves. You may decide not to take part, or to withdraw from a trial, at any stage. You will then receive the best standard treatment available.
Follow-up
After your treatment is completed, you will have regular check-ups and possibly scans or x-rays. These will probably continue for several years. If you have any problems, or notice any new symptoms between these times, let your doctor know as soon as possible.
Ocular melanoma can sometimes spread to other parts of the body, mainly to the liver, but also to the lungs and bones. It is, therefore, important to let your specialist know if you notice any new symptoms, where ever they are in the body, as often further treatment can be given.
Your feelings
During your diagnosis and treatment of cancer, you are likely to experience a number of different emotions, from shock and disbelief to fear and anger. At times, these emotions can be overwhelming and hard to control. It is quite natural, and important, to be able to express them.
Each individual has their own way of coping with difficult situations; some people find it helpful to talk to friends or family, while others prefer to seek help from people outside their situation. Some people prefer to keep their feelings to themselves. There is no right or wrong way to cope, but help is available if you need it.
