The nasolacrimal duct is a small tube that connects the eye to the nasal cavity. It allows tears, produced by the lacrimal glands, to drain from the surface of the eye into the nose. This drainage helps keep the eyes moist and prevents overflow of tears. When you cry or your eyes water, the excess tears travel through the nasolacrimal duct. If this duct becomes blocked, it can lead to excessive tearing or infections. Proper functioning of the nasolacrimal duct is essential for maintaining eye health and comfort.