Eye melanoma: causes and treatments


Eye melanoma: causes and treatments

Ocular, or eye, melanoma is the most common type of eye cancer. It normally affects the uvea, the vascular layer of the eye between the retina and the white of the eye.

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.

The American Cancer Society estimate that, in 2017, there will be 3,130 new cancers of the eye and the eye's orbit in the United States (U.S.), and that 330 people will die of such cancers.

It can happen at any age, but it becomes more likely as people get older.

Signs and symptoms

Eye melanoma may cause vision problems, or there may be no 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.

Risk factors

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.

Taking the correct precautions when exposed to the sun may reduce the risk of eye melanoma.

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.

Ethnicity: It is most likely to affect white people.

Diagnosis

Early detection and treatment of ocular melanoma are crucial for effective treatment. Having regular eye tests with an ophthalmologist, or eye doctor, is the best way to protect your eyes.

The doctor examines the outer part of the eye, looking out for enlarged blood vessels. This may indicate a number of eye conditions, including a tumor. The ophthalmologist also examines the inside of the eye.

Ophthalmoscopy is used 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 uses a head lamp to shine a very bright light into the eye.

Direct ophthalmoscopy uses an ophthalmoscope, a device consisting of a concave mirror and battery-operated light. The operator uses a single eyepiece to look into the eye.

The ophthalmologist may give medication to the patient to dilate the pupils and enlarge the opening into the structures of the eye.

Looking into the eye is sufficient to detect and diagnose most tumors.

Tests

An ophthalmologist can diagnose ocular melanoma.

If the doctor suspects eye melanoma, they may order 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. Ultrasound may also help to determine the thickness of the tumor.

Fluorescein angiography: A yellow dye is injected into a vein in the patient's arm. As the dye circulates in the eyes, a special camera takes flash pictures every few seconds for several minutes. The images can tell show where the dye is going, and it highlights the blood vessels in the retina.

If ocular melanoma is confirmed, the ophthalmologist may refer the patient to an ocular or regular oncologist for treatment of the cancer.

Metastasis

Further tests can detect whether the cancer has metastasized, or spread to other parts of the body.

These include:

  • blood tests, to determine whether the cancer has spread to the liver
  • a chest X-ray to detect abnormalities in the lungs
  • a CT or MRI scan of other parts of the body

A biopsy, in which the doctor takes a tissue sample for testing in a laboratory. A biopsy is not usually needed.

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.

Surgery

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.

According to the American Cancer Society, 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.

Prevention

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.

Uveal Melanoma, A Modern Approach to Ocular Oncology | #UCLAMDCHAT Webinar (Video Medical And Professional 2020).

Section Issues On Medicine: Disease