Question

What is the function of iris?

• A. It focuses light on retina.
• B. It controls the size of pupil.
• C. It controls ciliary muscles.
• D. It controls the size of cornea.

Answer 1

The correct option is B

It controls the size of pupil.

Iris is the dark muscular diaphragm, which controls the size of the pupil. It is responsible for controlling the amount of light reaching the retina by regulating the size of pupil. The size of pupil can fluctuate as the iris has tiny muscles that can either widen or narrow, depending upon surrounding light. At night, the muscles will widen the pupil so there is sufficient light in the eye. When it is too bright outside, the pupil will contract to allow less light into the eyes and prevent damage of retina.