When light rays enter the eye, most of the refraction occurs at the  

Which of the following statement is correct?

A person needs a lens of power $-4.5 \mathrm{D}$ for correction of her vision.

$\left(a\right)$ What kind of defect in vision is she suffering from?

$\left(b\right)$ What is the focal length of the corrective lens?

$\left(c\right)$ What is the nature of the corrective lens?