This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Optics and refraction, Subject name: Ophthalmology
Most impoant factor determining convergence of light rays on retina is - 
Select and explain. 
A. Length of eyeball, B. Dioptre power of lens, C. Refractive index of cornea, D. Physical state of vitreous
C: Refractive index of cornea
Answer: C: Refractive index of cornea 
Explanation: The cornea is the most imponat refractive surface of the eye with a refractive index of 1.376. The reason for msximum refraction lies in the fact that when light travel from one refractive medium to other. In eye, there are three such refracting interfaces:- i)Air, ii)Aqueous iii) lens Reference : Optics of human eye 4th edition page15-20