Each layer of lens has a role in the refractive index of the entire lens. Which component has maximum refractive index?

Refractive index increases from 1.386 in the peripheral coex to 1.41 in the central nucleus of the lens. The anterior capsule surface of the lens has a greater refractive index than the posterior capsular surface (1.364-1.381 compared with 1.338-1.357). The change in refractive index from the surface of the lens to the center results from changes in protein concentration, the higher the concentration, the greater the refractive power. Ref: Ophthalmology edited by Myron Yanoff, Jay S. Duker, James J. Augsburger, 2009, Page 383.