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': 'All of the following are features of asteroid hyalosis except: \nSelect and explain. \nA. Usually bilateral, B. Solid vitreous, C. Spherical calcium bodies, D. Usually asymptomatic', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Usually bilateral', 'role': 'assistant'}]