This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
In retinoblastoma, after enucleation, which tissue is sectioned to find out systemic metastasis 
Select and explain. 
A. Central retinal aery, B. Sclera and episclera, C. Optic nerve, D. Voex vein
C: Optic nerve
Answer: C: Optic nerve 
Explanation: C i.e. Optic nerve Enucleation is indicated in large retinoblastoma with diffuse involvement (due to poor prognosis & high risk of recurrence) & normal fellow eye (so aggressive chemotherapy is inappropriate). It should be done with minimal-manipulation and it is imperative to obtain 8-12 mm piece of optic nerve Q to rule out any spread of tumor to brain.