This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Tumors, 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: *After enucleation, optic nerve is examined and if it shows tumor invasion, postoperative radiotherapy to the orbital apex and chemotherapy are given. Ref: Khurana 7th/e p.317.