How is the sense of vision carried from the eye to the brain?

What is meant by accommodation of the eye?

$A$ person cannot see objects farther than $12\, m$ from the eye clearly. Name the defect of vision he is suffering from and the lens that should be used for correction of this defect. Illustrate with the help of a diagram,how this lens will correct the defective vision?

Name the defects of vision of the human eye.

What is the role of the pupil in a human eye?

$A$ person needs a lens of power $-4.5\, D$ for the correction of her vision.
$(a)$ What kind of defect in vision is she suffering from?
$(b)$ What is the focal length of the corrective lens?
$(c)$ What is the nature of the corrective lens?