Which structure in the eye is primarily responsible for the refraction of light?

The cornea is the primary structure responsible for the refraction of light in the eye. It is a transparent, dome-shaped front layer of the eye that contributes significantly to the eye's total optical power. The cornea refracts light as it enters the eye, bending the light rays to help focus them onto the retina, which is crucial for clear vision.

Refraction occurs due to the change in the speed of light as it moves from air (a less dense medium) into the aqueous humor (a denser medium) of the eye. The cornea has a fixed curvature and is responsible for about two-thirds of the eye's overall focusing power, making it the most critical structure for this function.

The other structures mentioned, while they have roles in vision and the anatomy of the eye, do not primarily contribute to the process of refraction. The sclera, which is the white outer layer of the eye, provides protection and form but does not play an active role in bending light. The vitreous body is the gel-like substance that fills the eye and helps maintain its shape, but it does not refract light. The conjunctiva is a thin membrane covering the eye's surface and eyelids, serving mainly to protect and lubricate the