Dear Doctor: Our neighbor was diagnosed with cancer in his right eye. It’s called ocular melanoma. I don’t want to bother him or his wife with a lot of questions, but I’d like to know more about the disease. Can you explain about risk factors and symptoms? How common is it? I thought melanoma was a skin cancer.
Dear Reader: Ocular melanoma is what is known as a primary intraocular cancer. That means that the disease begins within the eye itself. It’s a rare type of cancer that occurs most often in adults, and it affects only 5 or 6 out of every 1 million people each year. It can occur at any age and in people of all races, but it tends to be more common in those with lighter skin and eye color.
You’re correct that we’re most accustomed to hearing about melanoma in connection to skin cancer. However, the root of the word derives from melanocytes, which are cells that produce and contain the pigment known as melanin. These cells are found both in the skin and the eyes and, depending on their density and distribution, lend each their specific color. The word “oma” denotes swelling, tumor or other abnormal growth. Melanoma, therefore, refers to cancers that begin in the melanocytes.
Ocular melanoma usually arises in the uvea, which is the middle of the three layers of the eye. The positioning makes it difficult to see, and this type of cancer causes few, if any, symptoms. When symptoms do occur, they can include a dark spot that is visible on the iris, a change to the shape of the pupil, visual distortion or a blind spot in the peripheral vision, the perception of flashing lights or the sensation of pressure within the eye. Most often, ocular melanoma is identified when the eyes are dilated in the course of a routine exam. Ultrasound and a range of scans may then be used to confirm a diagnosis.
In addition to lighter eye color, risk factors for this type of cancer include exposure to sunlight or UV light, increased pigmentation on the uvea, having a mole in or on the surface of the eye, older age and being of Caucasian descent.
This is an aggressive type of cancer that can potentially spread to other areas of the body, most often to the liver. Immediate treatment is often necessary. The approach depends on the size and placement of the tumor, and the stage at which it is found. The two most common treatments are radiation therapy and surgery. Depending on the size and placement of the tumor, vision may be preserved. In advanced cases, aggressive treatment may be necessary, and vision is lost.
When an eye must be removed, patients can opt for reconstructive surgery, including the use of an artificial eye, or prosthesis. When tumors are small, they can sometimes be removed with laser treatment, which heats and destroys the cells. Investigative therapies that have shown promise include cryosurgery, which involves freezing the affected cells, immunotherapy and drugs that target proteins involved in tumor growth.
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