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': 'Most important factor determining convergence of light rays on the retina is \nSelect and explain. \nA. Length of eyeball, B. Refractive index of cornea, C. Dioptre power of lens, D. Physical state of vitreous', 'role': 'user'}, {'content': 'Answer: B \nExplanation: refracting structures with their refractive\xa0indices given in parentheses-cornea\xa0(1.37), the aqueous humour (1.33), the crystalline lens\xa0(1.42), and the vitreous humour (1.33).\nThe total dioptric\xa0power of the eye is about +60 D out of which about\xa0+44 D is contributed by the cornea and +16 D by the\xa0crystalline lens.', 'role': 'assistant'}]