Refractive index: It is the ratio of sine of angle of incidence to the sine of angle of refraction. The refractive index of, Cornea: 1.37 Aqueous humour: 1.33 Crystalline lens: 1.42 Vitreous humour: 1.33 Also know: The total dioptric power of the eye is about +60 D out of which about +44 D is contributed by cornea and +16 D by the crystalline lens. Ref: Ophthalmology By A. K. Khurana, 3rd edition, Page 50.