Which boundary of the eye is called the limbus?

• A. Conjunctiva
• B. Medial canthus
• C. Limbus
• D. Caruncle

Answer: (C)

The key idea is the border between the clear cornea and the white sclera. That transition area is the limbus, also known as the corneoscleral junction. It marks the edge of the cornea as it blends into the sclera and serves as a boundary where corneal epithelium meets conjunctival epithelium. The limbus is clinically important as a landmark for eye procedures and for the renewal of the corneal surface.

The other structures are not boundaries between cornea and sclera: the conjunctiva is the mucous membrane covering the sclera and eyelids; the medial canthus is the inner corner where the lids meet; and the caruncle is the small nodule at that inner corner.