What is Retinoblastoma?

According to the Retinoblastoma.ca site:
"Retinoblastoma (RB), is a rare form of eye cancer that affects the retina of infants and young children. It occurs in approximately 1 in every 20,000 births. About 60% of the children with retinoblastoma will have tumors in only one eye. This is referred to as unilateral retinoblastoma. The remaining 40% will have multiple tumors found in both eyes. This is referred to as bilateral retinoblastoma. RB can range dramatically in severity. No two cases are identical nor are they necessarily managed in the same way. a number of different treatments are available to children with RB. The severity and location of the tumors will determine which treatments will be suggested. With early detection and modern medical care, the survival rate for children with RB is 96%. Ongoing research and new treatment developments are allowing an increasing number of affected eyes to be saved and are maximizing the visual outcome and quality of life of each affected child."
http://retinoblastoma.ca/whatis.htm

I thought that this definition was pretty good. Other retinoblastoma sites and wikipedia have similar definitions. The breakdown of Unilateral/Bilateral varies from 60%/40% up to 75%/25% but the rest of the definition is pretty consistent with other definitions out there.