Retinoblastoma (Rb) is a rapidly developing cancer that develops in the cells of the retina, the light-detecting tissue of the eye. In the developed world, Rb has one of the best cure rates of all childhood cancers (95-98%), with more than nine out of every ten sufferers surviving into adulthood. Retinoblastoma is a very treatable cancer.
There are two forms of the disease; a genetic, heritable form and a non-genetic, non-heritable form. Approximately 55% of children with Rb have the non-genetic form. If there is no history of the disease within the family, the disease is labeled "sporadic", but this does not necessarily indicate that it is the non-genetic form.
In about two thirds of cases,  only one eye is affected (unilateral retinoblastoma); in the other third, tumours develop in both eyes (bilateral retinoblastoma). The number and size of tumours on each eye may vary. In certain cases, also the pineal gland is affected (trilateral retinoblastoma). The position, size, and quantity of tumours are considered when choosing the type of treatment for the disease.
The most common and obvious sign of retinoblastoma is an abnormal appearance of the pupil, leukocoria. Other less common and less specific signs and symptoms are deterioration of vision, a red and irritated eye, faltering growth, or delayed development. Some children with retinoblastoma can develop a squint, commonly referred to as "cross-eyed" or "wall-eyed" (strabismus). However, retinoblastoma presence with advanced disease in developing countries and eye enlargement is a common finding.
Depending on the position of the tumors, they may be visible during a simple eye exam using an ophthalmoscope to look through the pupil. A positive diagnosis is usually made only with an examination under anesthetic (EUA). A white eye reflection is not always a positive indication of retinoblastoma and can be caused by light being reflected badly or by other conditions such as Coats's Disease.
In a photograph, the photographic fault red eye may be a sign of retinoblastoma, if the photograph is in one eye and not in the other eye.