Question

Which part of the eye dilates and contracts based on the environment?
A. Sclera
B. Cornea
C. Lens
D. Pupil

Answer 1

HINT:
Eyes are the organs that allow us to see and are located in the sockets of the skull called orbits. It is spherical in nature and consists of three layers namely; sclera, choroid layer and retina.

COMPLETE STEP BY STEP ANSWER:
The innermost layer is called sclera and is composed of dense connective tissue. The sclera maintains the eyeball shape and protects it from any injury. The muscles that are attached to sclera help in the movement of the eyeball.
The anterior portion of sclera is called cornea. Cornea helps in focusing light rays on the retina and allows minimum scattering and optical degradation. It protects the structures present inside the eye and contributes to the refractive power of the eye.
Lens help in focusing the light on the retina by changing its shape in order to create clear images that are kept at a distance. Iris works along with the cornea to refract or focus the light onto the retina.
The amount of light that enters the eye is regulated by pupil. Iris controls the diameter of the pupil. When the environment is dark, iris causes the dilation (enlargement) of the pupil that allows more light to enter the eye. When the environment is bright, iris causes constriction (shrinking) of the pupil that allows less light to enter the eye.
Thus, the correct answer is:- Pupil

Option ‘D’ is correct

NOTE:
The pupils in both eyes work independently. The pupil of one eye can contract whereas the pupil of another eye can remain stable. If one pupil is larger than the other one, it may be an indication of a serious medical issue.