The nasal turbinates in the nasal cavity are divided into the superior, middle and inferior turbinates, below which are the superior, middle and inferior nasal passages, respectively, and the nasolacrimal duct opens in the inferior nasal passage in the nasal cavity. When the mucous membrane in the inferior nasal canal becomes congested, swollen, or obstructed by polyps, tearing can occur, or when the posterior end of the inferior turbinate becomes enlarged and compresses the nasolacrimal duct. In sinusitis and sinus cysts, it is necessary to pay attention to the direction of the nasolacrimal duct when performing windowing in the lower nasal tract to prevent damage to the nasolacrimal duct and cause complications such as tearing and pus flow.