ABSTRACT
Diagnosis of RB was based on the Reese-Ellsworth ( R-E) staging system, first published in the 1960s . It divided eyes into five groups, I to V, each with subgroups, a and b . These divisions were according to the extent and location of disease as determined by ophthalmoscopy . The relative risk of losing an eye treated with primary external beam radiotherapy (EBRT) served as the index that clinically separated the groups . Group I included eyes with the lowest risk of enucleation and group V eyes the highest . In 2005, Murphree proposed a new classification system for intraocular retinoblastoma that ranks tumors for the risk of treatment failure and enucleation or EBRT by specific morphologic features, and the extent of disease in the eye at initial diagnosis . Its groups follow the natural history of intraocular retinoblastoma from early disease (group A) to late disease (group E) . Group A eyes have the lowest risk of treatment failure and group E eyes have the highest risk with groups B, C, and D having intermediate risk . The presence of vitreous or subretinal seeding is the major ophthalmologic feature that separates eyes with a low risk for enucleation (groups A and B) from those containing advanced tumors (groups C and D) with a higher risk (Figure 10 .1) .
