What is the far point and near point of the human eye with normal vision?

Chickens can see only in bright light. What type of cells is present in their retina?

Why can you not see an object clearly if it is placed very close to your eye?

Name the defects of vision of the human eye.

$(a)$ State two main causes of a person developing near-sightedness (myopia). With the help of a ray diagram, suggest how this disability can be corrected.
$(b)$ The far point of a myopic person is $150 \ cm$ in front of the eye. Calculate the focal length and power of the lens required to enable him to see distant objects clearly.

Why do we have two eyes for vision instead of just one?