A cancerous growth in any part of the eye.
Eye cancer can occur in many parts of the eye where a tumor can occur. Because of this there are several types of ocular cancer. Their occurrence varies in the age of the affected individual. This article will focus on retinoblastoma, the most common eye cancer in children, and intraocular melanoma, the most common eye cancer in adults.
Retinoblastoma can occur at any age but is most often seen in children younger than five. About 200 children a year are diagnosed with it in the United States. Retinoblastoma starts with a small tumor in the retina, the very back of the eye. In growing children, the retina originates from cells called retinoblasts that grow and divide very quickly. These cells eventually become the mature cells of the retina when they stop growing. In the case of retinoblastoma the retinoblasts don't stop growing and form a tumor that can continue to grow and cause further complications if not treated quickly.
Retinoblastoma typically has three classifications: intraocular, extraocular and recurrent retinoblastoma. In the intraocular form the cancer can be found in one or both eyes but not in tissue external of the eye. In the extraocular form the cancer has spread outside the eye. It can spread to the tissue surrounding the eye or it can invade other areas of the body. In the recurrent form the cancer returns after already being treated. It may recur in the eye, its surrounding tissues, or elsewhere in the body.
Intraocular melanoma is a rare cancer overall, yet it is the most common eye cancer seen in adults. It is when cancer cells are found in the uvea of the eye. The uvea includes the iris (the colored portion of eye), the ciliary body (an eye muscle that focuses the lens) and the choroid (found in the back of the eye next to the retina).
Intraocular cancer of the iris usually grows slowly and usually doesn't spread. The tumor is seen on the iris as a darker spot than the surrounding area. Intraocular cancer of the choroid or ciliary body occurs in the back of the eye. They are classified by size with a small tumor being 2-3 mm or smaller and a medium or large tumor being bigger than 3 mm.
Intraocular cancer can spread and become extraocular as well. If not found and treated early enough it can spread to the surrounding tissues, the optic nerve or into the eye socket.
Causes and symptoms
Genetics is thought to play a role in eye cancer. In regards to retinoblastoma, it is believed that if a tumor develops only in one eye then it isn't hereditary. However, if a tumor occurs in both eyes then it is hereditary. Those who have hereditary retinoblastoma have a rare risk of developing a tumor in the brain and should be monitored on a regular basis.
The cause of intraocular melanoma is still vague. Genetics could play a role, but age is also a factor. Inter-estingly enough, this type of cancer is seen most often in white people from a northern European descent.
The symptoms of this type of cancer usually begin with blurred vision and tenderness of the eye. Advanced symptoms may include loss of vision. If these symptoms persist a person should make an appointment with their ophthalmologist.
An ophthalmologist makes a diagnosis. The doctor is usually able to see the tumor through the pupil or directly on the iris if the cancer is intraocular melanoma of the iris. Because the doctor can usually readily see the tumor a biopsy is rarely needed.
An ultrasound or a fluorescein angiography are two tests doctors use to further diagnose eye cancers. In an ultrasound sound waves are pointed at the tumor and depending on how they reflect off the tumor the doctor can better diagnose it. In a fluorescein angiography a fluorescent dye is injected into the patients arm. When this dye circulates through the body and reaches the eye a series of rapid pictures are taken through the pupil. The tumor will show up in these photos.
Once a diagnosis has been made, the treatment can begin.
The treatment depends on how far advanced the tumor is. If the tumor is in the advanced stages and there is little hope of regaining vision the most effective treatment
- choroidectomy-removal of part of the choroid,
- iridectomy-removal of part of the iris,
- iridocyclectomy-removal of parts of the ciliary body and parts of iris,
- iridotrabeculectomy-removal of parts of the supporting tissues around the cornea and iris.
In eye cancer where the tumor is small and there is a good chance that the vision will be restored less drastic measures than the above surgeries are taken. Radiation and chemotherapy are two courses of treatment that help in killing off the existing tumor and preventing its spread into other areas of the body.
Besides radiation and chemotherapy there are other methods of treating eye cancer. Cryotherapy uses extreme cold to destroy the cancer cells. Thermotherapy uses heat to destroy the cancer cells. Photocoagulation uses a laser to destroy blood vessels that supply the tumor with nutrients. If the tumor isn't advanced these are good options to treat it in order to avoid losing an eye.
A radiation/surgical treatment for eye cancer is brachytherapy. A small plaque with radioactive iodine on one side and gold on the other is stitched to the eye behind the tumor with the radioactive iodine facing the tumor. The gold is used to shield the other tissues from the radiation. It is left there for a period of time depending on the dosage of radiation needed and then it is removed. In this way the tumor is treated and hopefully will shrink and eventually die.
Other than the treatments above, there aren't any alternative treatments. New clinical trials are constantly under way to further the treatment of the disease in the future.
All forms of retinoblastoma and intraocular melanoma are treatable. Enucleation can usually be avoided if found early enough. The outlook is positive for people with eye cancer.
A good healthy diet and lifestyle are always recommended to prevent cancer. Known carcinogens should always be avoided.
Wilson, Czechonska, Finger, Rausen, Hooper, and Haik. "Chemotherapy for Eye Cancer." Survey of Ophthalmology (March/April 2001): 416-44.
The American Cancer Society. 2000. <http://www.cancer.org>.
Cancer Net. 2001. <http://www.cancernet.nci.nih.gov>.
JHMI. 2001. <http://www.med.jhu.edu>.
National Eye Institute. 1998. <http://www.nei.nih.gov>.
Thomas Scott Eagan
Ronald Watson, PhD
Carcinogen—A substance that is known to cause cancer.
Cornea—The clear layer that covers the front part of the eye.
Enucleation—Surgical removal of the eye.
Pupil—The hole in the eye that allows light in.