Which structure of the eye is described as the transparent coat covering the iris and pupil?

The cornea is the transparent structure that covers the iris and pupil of the eye. It serves several important functions, including protecting the inner parts of the eye and helping to focus light. The cornea is the first part of the eye that light encounters as it enters, and its curvature plays a significant role in bending light rays to ensure that they can be properly focused onto the retina at the back of the eye.

In contrast, the sclera is the white, opaque outer layer of the eyeball, which provides protection and structure but does not allow light to pass through. The conjunctiva is a thin, transparent membrane that covers the sclera and lines the inner surface of the eyelids, but it does not cover the iris and pupil. The retina, located at the back of the eye, is responsible for converting light into neural signals but is not involved in the light-entry process.

Thus, the cornea is uniquely characterized by its transparency and strategic location in relation to the iris and pupil, making it essential for proper vision.