[Functional nasolacrimal duct decompression for chronic dacryocystitis].

Objective:To investigate the feasibility of endoscopic nasolacrimal decompression for chronic dacryocystitis. Method:22 patients with chronic dacryocystitis hospitalized at Longgang ENT hospital were participated in this study. An injection of 30% iohexol was administered to conduct lacrimal sac angiography. The injection was stopped when the agent reflux from the lacrimal duct, and a computed tomography（CT） scan of the lacrimal duct was performed immediately. Sinuses Trachea Isoftware was used to reconstruct a three-dimensional（3D） view of the lacrimal passage and its surrounding structures. The software was used to simulate the "cutting" of the lacrimal sac and nasolacrimal duct; the lacrimal sac and nasal lacrimal duct were removed after 1/2-3/4 circumferences to decompress the passage and expose the membranous nasolacrimal duct. CT scans were performed on ten adult frozen cadaveric heads, and the nasolacrimal duct decompression operation was simulated. Then, the bone of the nasolacrimal duct was removed, membranous nasolacrimal duct was exposed, and the capsular nasolacrimal duct was dilated. Result:①The lacrimal angiography study revealed that lacrimal duct obstruction occurred in the nasolacrimal duct segment, accounting for 72.7%（16/22） of the study cases. ② The anatomical examination showed that the outer sidewall of the nasolacrimal duct was composed of the tear groove of the maxilla, and the inner wall was composed of the descending process of the lacrimal bone. ③ In cadaveric heads, decompression of the osseous nasolacrimal duct was performed, exposing the membranous nasolacrimal duct. ④ A balloon catheter could dilate the membranous nasolacrimal duct and allow the lacrimal passage to be flushed. Conclusion:Endoscopic nasolacrimal decompression preserves the integrity of the lacrimal duct, allows drainage of the lacrimal duct, and avoids obstruction of the lacrimal duct by preventing lacrimal granulation.