In the human eye,the image of an object is formed on the $................$.

Name the outermost layer of the eye. What is its function?

The far point of a myopic person is $80 \,cm$ in front of the eye. What is the nature and power of the lens required to correct the problem?

$A$ person suffering from an eye defect uses lenses of power $-1\, D$. Name the defect he is suffering from and the nature of lens used.

$A$ $14$ year old student is not able to see clearly the questions written on the blackboard placed at a distance of $5\, m$ from him.
$(a)$ Name the defect of vision he is suffering from.
$(b)$ With the help of labelled ray diagrams show how this defect can be corrected.
$(c)$ Name the type of lens used to correct this defect.

Name the essential parts of the human eye.