Which of the following is absent from the human eye?

Why are owls able to see only during the night?

The retina is most sensitive at:

Select the correct option:
$(1)$ There are no photoreceptor cells slightly above the posterior pole of the eyeball,hence it is called the blind spot.
$(2)$ Rod cells contain a purple-red protein called rhodopsin.

The '$Pecten$' is a structure found in the eye of which of the following?

Assertion : Astigmatism is due to uneven curvature of lens.
Reason : It is treated with cylindrical lenses.