What happens to the image distance in the eye when we increase the distance of an object from the eye?

State one function each of iris,pupil,and cornea.

$A$ 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?

Accommodation means the adjustment of light going into the eye for image formation.

$A$ person cannot see objects distinctly when placed beyond $2\, m$.
$(a)$ Identify the eye defect.
$(b)$ Give two reasons for this defect.
$(c)$ Calculate the power and nature of the lens he should be using to see the distant objects clearly.
$(d)$ Draw the ray diagrams for the defective and the corrected eye.

What kind of lens is used in the spectacles of a person suffering from myopia (near-sightedness)?