All of the following are layers of the cornea except?

The correct answer identifies "Conjunctiva" as the layer that is not part of the cornea. The cornea is made up of three primary layers: the epithelium, stroma, and endothelium.

The epithelium is the outermost layer, providing a protective barrier against environmental damage and pathogens. Just beneath that is the stroma, comprising the bulk of the cornea's structure, which is composed of collagen fibers and contributes to the cornea's transparency and strength. The innermost layer, the endothelium, is critical for maintaining corneal hydration and transparency by regulating fluid and nutrient exchange.

In contrast, the conjunctiva is not a layer of the cornea but rather a thin, translucent membrane that covers the inner surface of the eyelids and extends to cover part of the eyeball's surface. Its main function is to lubricate and protect the eye, and it plays no structural role within the cornea itself. Understanding the distinction between the layers of the cornea and adjacent structures such as the conjunctiva is crucial in anatomy and medical coding, particularly regarding vision-related diagnoses and treatments.