The vitreous humor is .....

Which of the following statements is correct regarding the pupil of the human eye?
$(I)$. It is the aperture surrounded by the iris.
$(II)$. The diameter of the pupil is regulated by the muscle fibres of the iris.
$(III)$. It is a transparent crystalline structure attached to the ciliary body.
The correct option is:

The size of the pupil is controlled by the

Night blindness is caused by the deficiency of which of the following?

The muscles of the iris and ciliary body are derived from the:

The eye defect $Astigmatism$ can be corrected by using: