What provides essential nutrients to the cornea?

The aqueous humor is the correct choice because it plays a crucial role in providing essential nutrients to the cornea. This clear fluid is located in the anterior chamber of the eye, between the cornea and the lens, and it continuously nourishes the cornea, delivering vital substances such as glucose, amino acids, and other nutrients essential for maintaining the health and transparency of this avascular structure.

While tears do offer some level of protection and hydration for the cornea, they primarily serve to keep the surface moist and provide lubrication during blinking, rather than nourishing the cornea metabolically. The vitreous humor, located in the larger posterior segment of the eye, does not contact the cornea and is not involved in nutrient delivery to it. The corneal epithelium, although it serves as a protective barrier and participates in maintaining corneal health, relies on the aqueous humor for its nutritional needs. Thus, the aqueous humor is fundamentally important for providing the necessary nutrients that sustain the cornea's function and integrity.