Retinoblastoma occurs when a cell of the growing retina develops a mutation in the RB gene (a tumor suppresser gene). This mutation causes the cell to grow out of control and become cancererous.

Sometimes this mutation develops in a child whose family has never had eye cancer, but other times the mutation is present in several family members. If the mutation runs in the family, there is a 50% chance that an affected person's children will also have the mutation and a high risk of developing retinoblastoma.

One or both eyes may be affected. A visible whiteness in the pupil may be present. Blindness can occur in the affected eye, and the eyes may appear crossed. The tumor can spread to the eye socket, and to the brain, by means of the optic nerve. This is a rare tumor, except in families that carry the RB gene mutation.

• A white glow in the eye that is often seen in photographs taken with a flash; instead of the typical "red eye" from the flash, the pupil may appear white or distorted
• Pupil, white spots
• Crossed eyes
• A red, painful eye
• Poor vision
• The iris may be a different color in each eye.

• An examination of the eye with dilation of the pupil
• A CT or MRI study of the head to evaluate tumor and possible spread
• An ultrasound of the eye (head and eye echoencephalogram)

Treatment options depend upon the size and location of the tumor. Small tumors may be treated by laser surgery. Radiation and chemotherapy may be needed if the tumor has spread beyond the eye.

The eye may need to be removed if the tumor does not respond to other treatments. It is important to seek treatment from a physician with experience treating this rare type of tumor.

If the cancer has not spread beyond the eye, almost all patients can be cured, though cure may require aggressive treatment and even removal of the eye to be successful. If the cancer has spread beyond the eye, the likelihood of a cure is much lower and depends on which organs are affected.