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
[{'content': 'Which of the following is not of prognostic significance to choroidal melanoma ? \nSelect and explain. \nA. Presence of retinal detachment, B. Size of the tumour, C. Cytology of the tumor cells, D. Presence of extraocular extension', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Prognosis of choroidal melanoma depends upon :-\n\nCell type\nSize of tumor\nLocation of tumor\nEvidence of invasion (extrascleral or vortex vein)\nAge of the patient\nCytology\nChromosomal abnormalities.', 'role': 'assistant'}]