It is also known as uveal melanoma. Tumors develop in the melanocytes, the pigment-producing cells within the uvea that give color to the eye.
Most melanomas affect the skin, but some develop in other parts of the body, including the eye.
If cancer starts in the eye, this is primary eye cancer. If the eye melanoma starts elsewhere in the body and spreads to the eye, it is called secondary eye cancer.
Eye cancer is usually secondary, and 9 out of 10 eye melanomas start in the skin.
Signs and symptoms
Some patients may experience no symptoms, while others may have light flashes, blurring of vision, or see dark spots in their field of vision.
The following signs and symptoms are possible:
- a dark spot in the iris that gets bigger
- a displacement of the eye within the eye socket
- seeing flashing lights
- watery eyes>
- poor or blurry vision or loss of peripheral vision in one eye
There may also be floaters, or small specks or squiggles that move about in the patient’s field of vision. Floaters may be seen more clearly when looking at a plain background, such as a blank wall. They may appear as tiny dots, circles, lines, clouds, or cobwebs.
Floaters are common, especially as people age, and they do not necessarily indicate cancer.
Rarely, pain in or around the eye can be a sign of eye melanoma.
Causes and risk factors
Experts are not sure what the exact cause of ocular melanoma is, but genetic factors are believed to play a role in cells becoming cancerous.
Scientists have found links between eye cancer and some genetic changes, but it remains unclear exactly where these changes occur, or if they cause cancer to develop.
The following factors increase the chance of developing eye melanoma:
Eye color: People with blue eyes have a higher risk of developing melanoma of the eye than those with brown eyes.
Exposure to ultraviolet (UV) light: Exposure to UV light, for example from sunshine, may increase the risk, but research has not confirmed this.
Dysplastic nevus syndrome: In this condition, a person develops atypical moles, known as dysplastic nevi, which look different from ordinary moles. They have irregular borders, may be mixed in color, and appear in clusters. Dysplastic nevi are more likely to develop into malignant melanoma than ordinary moles.
Genetic factors: Some chromosomal abnormalities, such as those found on chromosome 3, increase the risk of melanoma spreading from the eye to other parts of the body.
Treatment and prevention
Treatment depends on several factors, including where and what type of tumor it is, the size of the tumor, and the patient’s general health.
If there is a small lesion, a doctor may suggest monitoring it rather than treating it straight away, as treatment can lead to some vision loss.
A number of surgical options are possible.
Iridectomy removes parts of the iris with small melanomas that have not spread to other parts of the eye.
Iridotrabeculectomy removes parts of the iris and the supporting tissues where melanomas may have spread.
Radiation therapy can provide a localized treatment for an eye melanoma.
Iridocyclectomy removes part of the iris and ciliary body. The ciliary body is a thin layer between the white of the eye and the retina that contains blood vessels.
Choroidectomy removes part of the choroid, and sometimes part of the wall of the eye as well. The choroid is the pigmented, vascular part of the eye. The operation may be followed by a course of radiation therapy.
Enucleation removes the whole eye, in cases where the tumor is large, and any other treatment would result in the loss of most of the eye. It may also be recommended if there is eye pain.
The surgeon will implant an ocular prosthesis, or artificial eye. This does not provide vision. It is a cosmetic substitute.
Radiation and other targeted therapy
Radiation therapy can destroy the genetic material of cancer cells and stop them from reproducing. The radiation is carefully targeted to destroy the cancer cells while limiting damage to healthy cells. The doctor can deliver radiation from inside or outside the eye.
Two types of radiation treatment are teletherapy and brachytherapy.
Teletherapy generates radiation from outside of the patient’s body. It targets the malignant cells in the eye.
Brachytherapy temporarily anchors small radioactive seeds into the eye to shrink the tumor. The ophthalmologist or oncologist will stitch a plaque, or small implant, containing several iodine-125 seeds to the wall of the eye, near the tumor. It remains there for 4 to 5 days. The doctor carefully monitors the size of the tumor.
Transpupillary thermotherapy (TTT) is a type of infrared laser therapy that uses heat in the form of a laser to shrink smaller tumors.
Cryotherapy can freeze the cancerous cells.
Outlook and prevention
Treatment of eye melanoma is effective if it is detected and treated early enough. if the cancer only affects the eye, 80 percent of people will survive at least 5 years after diagnosis. If the cancer has spread to other parts of the body, around 15 percent will live for at least another 5 years.
To reduce the risk of skin cancer and eye cancer, the American Cancer Society recommends using protection from strong sunlight, including sunglasses with UVA and UVB protection, sunblock, and a hat.
Sunshine and outdoor work have not been proven to cause eye cancer, but they may increase the risk.