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 is the commonest cause of ocular morbidity globally? \nSelect and explain. \nA. Cataract, B. Refractive error, C. Ocular injury, D. Vitamin A deficiency', 'role': 'user'}, {'content': "Answer: B \nExplanation: Uncorrected refractive error remains a major cause of vision loss throughout the world. When included in the global statistics, uncorrected refractive error accounts for over 18% of profound vision loss, with a much larger percentage of moderate and severe vision loss. Ref: Pirbhai A, Kent S, Hodge W.G. (2011). Chapter 20. Causes and Prevention of Vision Loss. In Riordan-Eva P, Cunningham E.T., Jr (Eds), Vaughan & Asbury's General Ophthalmology, 18e.", 'role': 'assistant'}]