An eye is said to be near-sighted when a

Iodopsin is a light-sensitive pigment and is present in the

Which of the following structures of the eye can be artificially implanted?

Iodopsin is associated with .......

Good vision depends on adequate intake of carotene-rich food. Select the most appropriate option from the following statements.
$I.$ Vitamin $A$ derivatives are formed from carotene.
$II.$ Photopigments are embedded in the membrane discs of the outer segment.
$III.$ Retinal is a derivative of Vitamin $A$.
$IV.$ Retinal is a part of all photopigments that absorb light.

What is the primary function of the ciliary muscles in the human eye?