Impoant point of refraction in eye is?

Ans. is 'd' i.e., Anterior surface fo cornea Refractive system of eye The main function of refractive system of eye is to focus the light rays on the retina. The cornea (especially anterior surface) is the most impoant refractive surface of eye. The refractive power of cornea depend on two factors (i) Refractive index of cornea (Directly related), (ii) Radius of curvature (inversly related). Second impoant refractive structure of eye is lens with refractive index 1.386 - 1.406. Center (nucleus) of lens has maximum refractive index (1.46) amongst all the refractive structures of eye. Third impoant factor determining the refractive power of eye is the axial length of eyeball. lmm change in axial length leads to change of 3D in refractive power. For example, 1 mm shoening in axial length causes hypermetropia of 3D and 1mm lengthening causes myopia of 3D. Refractive index Medium Reactive index Air 1.000 Cornea 1.376 Aqueous humour 1.336 Lens 1.386 -1406 Vitreous humor 1.336