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': 'Visual impairment in pterygium is due to – \nSelect and explain. \nA. Astigmatism, B. Myopia, C. Hypermetropia, D. Hazy cornea', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Visual disturbances occur when pterygium encroches the pupillary area or due to corneal astigmatism induced due to fibrosis in the regressive stage.', 'role': 'assistant'}]