Final answer:
Hereditary retinoblastoma occurs earlier in life, typically in infancy or early childhood, while non-hereditary retinoblastoma usually presents later, in older children or young adults.
Step-by-step explanation:
There are two forms of retinoblastoma, a type of retinal cancer, that are distinguished by the age at which they occur. The hereditary or germline form of retinoblastoma typically presents earlier in life, often in infancy or early childhood.
On the other hand, the non-hereditary or sporadic form tends to occur later in life, usually in older children or young adults. This is because the hereditary form involves a mutation in the retinoblastoma gene (Rb) that is present from birth.
Increasing the risk for retinal cells to escape normal controls on cell division and become cancerous. In contrast, the non-hereditary form results from mutations acquired during the individual's lifetime.