## International Classification of Retinoblastoma (ICRB) **Key Point:** Group E represents the most advanced intraocular disease with the worst prognosis and highest risk of metastasis and globe loss. ### ICRB Stratification (A–E) | Group | Features | Prognosis | Globe Salvage | |-------|----------|-----------|---------------| | **A** | Small tumours, no vitreous seeding | Excellent | >95% | | **B** | Medium tumours, minimal vitreous involvement | Good | 85–90% | | **C** | Intraocular disease with vitreous seeding | Intermediate | 70–80% | | **D** | Advanced intraocular disease, significant vitreous seeding | Poor | 50–60% | | **E** | Extensive intraocular disease, poor visual potential, retinal detachment, neovascular glaucoma, phthisis | Very Poor | <10% | ### Group E Characteristics - Massive tumour burden - Total retinal detachment - Neovascular glaucoma - Vitreous haemorrhage - Phthisical eye (end-stage) - Optic nerve involvement - Extraocular extension **High-Yield:** Group E typically requires **enucleation** (surgical removal of the eye) rather than globe-salvaging chemotherapy. The risk of metastatic disease and mortality is substantially higher. **Clinical Pearl:** The ICRB classification guides treatment decisions: - Groups A–C: chemotherapy (intravenous, intra-arterial, or intravitreal) with globe salvage intent - Groups D–E: enucleation ± adjuvant therapy **Warning:** Do not confuse ICRB (international standard) with older Reese–Ellsworth classification, which is less commonly used in modern practice. [cite:Boyd & Manzitti Ophthalmology; American Academy of Ophthalmology Retina Module] 
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