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': 'Intractable secondary galucoma is seen in: \nSelect and explain. \nA. Diffuse iris melanoma, B. Nodular iris melanoma, C. Melanocyte deposits in anterior pa of iris, D. Melanocyte proliferation in posterior uveal tissue', 'role': 'user'}, {'content': "Answer: A \nExplanation: Diffuse iris melanomas are associated with intractable secondary glaucomas. 'Iris melanomas are usually nodular, but diffuse tumors can involve the iris stroma extensively and infiltrate the out flow system to cause intractable secondary glaucoma'. Ref: The Wills Eye Hospital Atlas of Clinical Ophthalmology, By William Tasman, Edward A. Jaeger, Wills; The Eye:Basic sciences in Practice, 2nd Edition, Page 422", 'role': 'assistant'}]