# Why does Cornea have greater refractive power than lens even though its refractive index is lesser than than of lens?

Why does Cornea have greater refractive power than lens even though its refractive index is lesser than than of lens?

Refractive index of cornea = 1.39

Refractive index of lens = 1.41

Refractive power of cornea = 43 D

Refractive power of lens = 19D

1. )Cornea is direct in contact with air so more relative refraction And lens is in contact with aqueous and cornea so less refraction compared to direct contact with air

2. Cornea has much greater curvature than lens

Refractive power means how much a medium/ surface can bend light as it passes through it.

When light passes from cornea it is coming from air R. I. =1 to cornea=1.39

Difference is: 0.39

When it passes through lens it is coming from aqueous humor RI:1.33 to lens RI:1.41 Difference is: 0.08

The greater the difference in Refractive index the greater the bending power which is refractive power.

because its the difference between refractive index of air and refractive index of cornea…its a huge difference with respect to the difference between refractive index of aqeous and lens…more difference means more refractive power…

Refractive power doesn’t depend on the refractive index of the material.

It’s dependent on the relative difference in refractive index between the two media, to and from light is passing through