What part of the eye is primarily nourished by aqueous humor?

Aqueous humor plays a crucial role in nourishing the anterior segment of the eye, which includes the cornea, iris, and lens. This clear fluid is produced by the ciliary body and fills the space between the lens and the cornea. Its primary functions include maintaining intraocular pressure, providing nutrients to these structures, and removing metabolic waste.

The cornea, being avascular, relies entirely on the aqueous humor for its nourishment since it does not receive direct blood supply. The lens also receives its nutrients from the aqueous humor, facilitating its transparent and refractive properties. The iris, which regulates the amount of light entering the eye, is similarly nourished by this fluid.

In contrast, other parts of the eye, such as the retina and optic nerve, receive their blood supply from different sources, primarily the central retinal artery and the choroidal blood vessels, while the sclera is primarily composed of dense connective tissue and does not rely significantly on aqueous humor for nourishment. Thus, the correct answer emphasizes the specific structures that are directly nourished by aqueous humor, highlighting its importance in maintaining the health and function of critical components of the eye.