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': 'Following are the causes of sudden loss of vision except ? \nSelect and explain. \nA. Angle closure glaucoma, B. Endophthalmitis, C. Central serous retinopathy, D. Corneal ulceration', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e., Corneal ulceration", 'role': 'assistant'}]