What is the term for the angle at either end of the eyelid slit?

The term "canthus" refers specifically to the angles at either end of the eyelid slit, where the upper and lower eyelids meet. This anatomical feature is crucial in defining the eye's structure and is significant in the context of eye care and surgery.

The cornea is the clear, dome-shaped surface that covers the front of the eye and plays an important role in focusing light. While it is essential to vision, it does not describe the angle of the eyelid. The cochlea, on the other hand, is a spiral-shaped structure in the inner ear involved in hearing, and thus is unrelated to the anatomy of the eyelid. Lastly, a cataract refers to a clouding of the lens in the eye leading to decreased vision; it is not related to the eyelid structure. The canthus, therefore, is the correct term that defines the specific anatomical angles associated with the eyelid.