Eye, or ocular, melanoma is the most common type of eye cancer. It usually affects the uvea, which is the layer between the retina and the white of the eye.
Most melanomas affect the skin, but some develop in other parts of the body, including the eye. Eye melanoma develops in the pigment-producing cells that give color to the eyes.
If cancer starts in the eye, it is called primary eye cancer. If eye melanoma begins elsewhere in the body and spreads to the eye, it is called secondary eye cancer.
Eye melanoma is usually a secondary cancer, meaning that it begins in a different location in the body and spreads to the eye. In fact, around 9 out of 10 eye melanomas begin in the skin.
In 2019, the American Cancer Society (ACS) estimate that there will be around 3,360 new diagnoses of eye cancer in the United States. Most of these will be ocular melanoma.
Some people with eye melanoma may experience no symptoms at all. Others may have light flashes, experience blurred eyesight, or see dark spots in their field of vision.
The following signs and symptoms are possible:
- a dark spot in the iris, which may grow
- displacement of the eye within the eye socket
- flashing lights in the visual field
- watery eyes
- blurry vision
- a loss of peripheral vision in one eye
A person might also experience “floaters.” These are specks or squiggles that move around in a person’s field of vision.
A person may be able to see floaters more clearly when looking at a plain background, such as a blank wall. They may also appear as tiny dots, circles, lines, clouds, or cobwebs.
Floaters are common, especially as people get older. They do not necessarily indicate cancer.
Rarely, pain in or around the eye can be a symptom of eye melanoma.
Experts are not sure exactly what causes ocular melanoma.
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 seem to increase the risk of developing eye melanoma:
- Eye color: People with blue or green eyes have a higher risk of developing ocular melanoma than those with brown eyes.
- Exposure to ultraviolet (UV) light: Exposure to UV light may increase the risk of conjunctival melanoma. This is a melanoma that occurs on the surface of the eye.
- Dysplastic nevus syndrome: In this condition, a person develops atypical moles, known as dysplastic nevi. These are different to ordinary moles. They have irregular borders, may contain several different colors, and often appear in clusters. Dysplastic nevi are more likely to develop into malignant melanomas than ordinary moles.
- Ethnicity: Eye melanoma is most likely to develop in white people.
Eye melanoma can develop at any age. However, it becomes more likely as people get older.
Early detection, diagnosis, and treatment of ocular melanoma are crucial for a good outlook.
Undergoing regular eye tests with a doctor who specializes in eye treatment, known as an ophthalmologist or optometrist, is the best way to detect eye melanoma early.
During the test, an eye doctor will examine the outer part of the eye, looking out for enlarged blood vessels. The results of this examination can reveal whether any eye conditions, including tumors, are present.
They will also examine the inside of the eye. They will use ophthalmoscopy to examine the inside of the eye, including the retina, the optic nerve, and the lens. This procedure can be direct or indirect.
- Indirect ophthalmoscopy: During this procedure, an eye doctor will use a special headlamp along with a lens to shine a very bright light into the eye.
- Direct ophthalmoscopy: In this test, an eye doctor will use an ophthalmoscope, which is a device consisting of a concave mirror and a battery operated light. They will use a single eyepiece to examine the eye.
An eye doctor may give a person medication to dilate the pupils and enlarge the opening into the structures of the eye.
Ophthalmoscopy is usually enough to detect most eye melanomas.
If the eye doctor suspects eye melanoma, they may request the following imaging tests:
- Ultrasound: High frequency sound waves produce images of structures inside the eye. Eye melanomas usually have distinctive features on an ultrasound image. An ultrasound scan may also help determine the thickness of the tumor.
- Fluorescein angiography: The eye doctor will inject a yellow dye into a vein in the individual’s arm. As the dye circulates in the eyes, a specialized camera will take flash pictures every few seconds for several minutes. These images can show the flow of the dye and highlight the blood vessels in the retina.
If the ophthalmologist confirms a diagnosis of ocular melanoma, they may refer the person to an ocular or regular oncologist to treat the cancer.
Further tests can determine whether or not the cancer has spread to other parts of the body. When a cancer spreads, it is known as metastasis.
Tests for metastasis include:
- blood tests, which can help a doctor determine if eye melanoma has spread to the liver
- a chest X-ray, to detect anomalies in the lungs
- a CT or MRI scan of another part of the body
- a biopsy, in which the doctor takes a tissue sample for testing in a laboratory
A biopsy is not usually necessary to diagnose melanoma. However, it can provide information about whether or not a conjunctival melanoma is likely to spread.
Treatment depends on several factors, including the location, size, and type of tumor, as well as the person’s overall health.
If a melanoma lesion on the eye is small, a doctor may suggest monitoring rather than immediate treatment. Interventions may lead to some vision loss.
In the sections below, we list more specific treatment options.
Several surgical options are available:
A surgeon will remove parts of the iris containing small melanomas that have not spread to other parts of the eye.
A surgeon will remove parts of the iris and supporting tissues to which melanomas may have spread.
A surgeon will remove part of the iris and ciliary body. The ciliary body, which contains blood vessels, is a thin layer between the white of the eye and the retina.
A surgeon will remove part of the choroid and, sometimes, a section of the eyewall. The choroid is the pigmented part of the eye that contains blood vessels. A course of radiation therapy may follow the procedure.
A surgeon will remove the whole eye. An eye doctor may recommend this procedure in cases where the tumor is large and any other treatment would result in the loss of most of the eye. They may also request enucleation for people with severe eye pain.
The surgeon will then implant an ocular prosthesis, or an artificial eye. This does not provide vision. It is a cosmetic substitute.
Radiation and other targeted therapy
Radiation therapy destroys the genetic material of cancer cells and stops them from reproducing.
A health professional targets the radiation to destroy the cancer cells while limiting damage to healthy cells. They can deliver radiation from inside or outside the eye.
The two types of radiation treatment available for eye melanomas are teletherapy and brachytherapy.
This method generates radiation from outside of the patient’s body. It targets the malignant cells in the eye.
A health professional will temporarily anchor small radioactive seeds into the eye to shrink the tumor. They will stitch a plaque, or small implant, containing several iodine-125 seeds to the wall of the eye, near the tumor. It will remain there for 4–5 days, emitting radiation. The eye doctor will carefully monitor the size of the tumor.
Other forms of targeted treatment include:
- Transpupillary thermotherapy: This is a type of infrared laser therapy that administers heat to shrink smaller tumors.
- Cryotherapy: A health professional can freeze and kill the cancerous cells using liquid nitrogen.
To reduce the risk of skin and eye cancer, the ACS recommend using protection from strong sunlight, including sunglasses with UVA and UVB protection, sunblock, and a wide brimmed hat.
Scientists have not yet proven that sunshine and outdoor work cause eye cancer, but they may increase the risk.
Treatment of eye melanoma can be effective if a health professional detects, diagnoses, and treats the cancer early enough.
The ACS measure the outlook for cancer using the 5 year relative survival rate. This provides a person’s likelihood of living for 5 years after a cancer diagnosis compared with a person who does not have cancer.
According to the ACS, if melanoma has not spread beyond the eye, the relative survival rate is 85%. If the cancer has spread to other parts of the body, the rate drops to around 19%.