What is the limbus in relation to the eye?

The limbus refers specifically to the border or margin where the cornea meets the sclera (the white part of the eye). This area is anatomically important because it plays a crucial role in the health and function of both the cornea and the surrounding tissues. The limbus is rich in stem cells which are responsible for regenerating corneal epithelial cells, helping maintain the clarity and health of the cornea. Therefore, understanding that the limbus indicates a boundary is essential for recognizing its implications for eye health and disease management.

The other choices describe different structures or areas related to the eye but do not accurately define the limbus. For example, the inner layer of the retina, the space between the eyelids, and the raised disk at the entry of the optic nerve refer to distinct and separate components of the eye's anatomy, rather than the specific margin of the cornea and sclera that the limbus represents.