## **Core Concept**
The cornea, a transparent avascular structure in the eye, relies on diffusion for its nutritional needs due to the lack of blood vessels. Its nourishment primarily comes from the aqueous humor and to some extent from the atmosphere. The avascular nature of the cornea is crucial for maintaining transparency.

## **Why the Correct Answer is Right**
The cornea gets its nourishment mainly from the **aqueous humor**. The aqueous humor, produced by the ciliary body, fills the anterior and posterior chambers of the eye. It provides nutrients and oxygen to the cornea and lens, which are avascular structures. The cornea also receives some oxygen directly from the air, but the primary source of its nourishment is the aqueous humor.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because, although atmospheric oxygen does contribute to corneal nutrition, it is not the main source.
- **Option B:** This option might seem plausible but is incorrect because the main source of nourishment is specified as the aqueous humor.
- **Option C:** This option is incorrect because tears provide some nutrients and protection but are not the primary source of nourishment for the cornea.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the cornea's avascularity is essential for its transparency, and its nutritional needs are met through diffusion from the aqueous humor and to a lesser extent from the atmosphere. This concept is crucial in ophthalmology, especially when considering corneal transplantation and the management of corneal diseases.

## **Correct Answer:** . aqueous humour