What Is Retinoblastoma? Retinoblastoma is a rare type of eye cancer that develops in the retina, the part of the eye that detects light and color. Although this disorder can occur at any age, it usually develops in young children. Most cases of retinoblastoma occur in only one eye, but both eyes can be affected. The most common sign of this disorder is a visible whiteness in the normally black pupil (the opening through which light enters the eye). This unusual whiteness is particularly noticeable in photographs taken with a flash, and is called "cat's eye reflex" or leukocoria. Other signs and symptoms of retinoblastoma include crossed eyes or eyes that do not point in the same direction (strabismus); persistent eye pain, redness, or irritation; and blindness or poor vision in the affected eye. People with the hereditary form of retinoblastoma may also develop a tumor in the brain called pinealoma. Pinealoma develops in the pineal gland, which is located at the ba...