Our eyes begin to develop very early in the womb. Rapidly growing cells in the eye, called retinoblasts, will eventually mature and form the retina, the light-sensing part of the eye that is located in the back of the eye. Sometimes, these specialized cells do not stop reproducing and form a tumor on the retina. These tumors may continue to grow, filling almost the entire vitreous humor (the jellylike substances the fills the eyeball). These tumors can also break off and spread to other parts of the eye, and eventually outside to lymph nodes and other organs.

Retinoblastoma occurs most often in children 5 years and under. It rarely occurs in adults. Between 200 and 300 children are diagnosed with retinoblastoma each year, affecting one in every 20,000. About 40% of all cases of retinoblastoma are inherited, meaning the cancer is passed on from parent to child. Retinoblastoma occurs about 75% of the time in one eye, and 25% of the time in both eyes.

Symptoms of retinoblastoma include:

• A pupil that appears white when light is shone into it, called leucocoria, may mean that a retinal tumor is present. Blood vessels in the back of the eye will normally reflect red.
• The eyes may not move or focus in the same direction.
• Eye pain
• The pupil is constantly dilated.
• Red eye(s)

An eye exam and imaging test given by an eye doctor can diagnose retinoblastoma.

If retinoblastoma is suspected, an ophthalmologist will need to examine the eye using special equipment to see the retina. Other tests may be conducted to determine the stage of the retinoblastoma, or how far it has spread. These tests include ultrasound, MRI scans, CT scans, bone scans, spinal tap, and bone marrow tests.

Stages of retinoblastoma include:

• Intraocular retinoblastoma. The earliest stage of retinoblastoma, found in one or both eyes. It has not yet spread to tissue outside of the eye.
• Extraocular retinoblastoma. This type of cancer has either spread outside of the eye or to other parts of the body.
• Recurrent retinoblastoma. The cancer has come back or spread in the eye or to other parts of the body after being treated.

Because it is usually found before it spreads outside of the sclera (white of the eye), retinoblastoma is highly curable. There are also many types of treatment that can save sight in the eye affected by retinoblastoma. Treatments are selected based on the stage of cancer at the time of diagnosis. Options include:

• Photocoagulation. A laser is used to kill blood vessels that feed the tumor.
• Cryotherapy. Extremely low temperatures are used to kill cancer cells.
• Chemotherapy. Chemotherapy is a treatment given intravenously (injected into the vein), orally, or is injected into the fluid that surrounds the brain and spinal cord, called intrathecal chemotherapy. These powerful doses of cancer-killing medication help kill or slow the growth of multiplying cancerous cells.
• Radiation therapy. Radiation may be given externally or internally. External-beam radiation therapy uses X-rays to kill cancer cells. Internal, or local radiation therapy, involves placing small amounts of radioactive material inside of or near the tumor to kill cancer cells.
• Enucleation. Surgery to remove the eye.

Over 90% of children will survive more than five years after being diagnosed with retinoblastoma. Patients are able to retain about 85% of vision in the affected eye after treatment.

Hereditary forms of retinoblastoma are more likely to reoccur years after treatment; therefore, close follow-up after treatment is important for these patients.

Because heredity and age play such large roles in retinoblastoma, the best prevention is through early detection. All babies should have a general eye exam at birth and then again at six months. A doctor will be able to detect any serious congenital problems or the appearance of retinal tumors. Newborns with a family history of retinoblastoma should have a thorough eye exam a few days after birth, at six weeks, once every three months until age two, and once every four months until age three. The chance is 1 in 2 that a parent will pass on the DNA mutation that causes retinoblastoma. A blood test can be used to determine if this mutation is present.

For adults, prevention means getting a thorough regular eye examination at least once a year and more often, as recommended by your ophthalmologist, if you have a personal or family history of eye disorders or diabetes.

Reviewed by the doctors at The Cleveland Clinic Cole Eye Institute.

Edited by Charlotte E. Grayson, MD, WebMD, November 2004.

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