Endoscopic dacryocystorhinostomy (En-DCR) has the advantages of less surgical trauma, shorter time, less postoperative bleeding, faster recovery, and no skin scars. However, the success rate of En-DCR surgery still varies greatly between 58% and 94% , and the main reason for the failure of the surgery is the membranous closure of the anastomosis. The application of new packing materials in dacryocystorhinostomy provides some new ways to improve the success rate of En-DCR.

Hydroxybutyl chitosan (HBCS), with its non-toxicity, biocompatibility, biodegradability, antibacterial, moisturizing properties, water solubility and temperature sensitivity, is widely used in biomedicine to prevent postoperative adhesions.

5-Fluorouracil (5-FU) is an antimetabolite drug that is effective in the treatment of keloids. The application of 5-FU in glaucoma filtration surgery has demonstrated its good safety and efficacy. Studies have shown that antimetabolites as adjuvant therapy for DCR have a positive impact on improving the success rate of surgery In this study, thermosensitive hydroxybutyl chitosan will be applied to the anastomosis site of the nasal mucosal flap and the lacrimal mucosal flap, or 0.3ml of 5-fluorouracil solution (25mg/ml) was injected into the nasal mucosa around the anastomosis at the same time. The investigators would like to observe the different situations of clinical symptoms, lacrimal duct flushing, endoscopy, and bacterial flora changes in patients with chronic dacryocystitis, to compare them with the previous intraoperative packing of gelatin sponge wrapped with thrombin and Tobramycin Dexamethasone. Furthermore, the investigators intend to evaluate the safety and efficacy of HBCS and 5-FU adjuvant internal En-DCR in the treatment of chronic dacryocystitis, and provide new ideas for the adjuvant therapy of En-DCR.

Endoscopic dacryocystorhinostomy (En-DCR) has the advantages of less surgical trauma, shorter time, less postoperative bleeding, faster recovery, and no skin scars. However, the success rate of En-DCR surgery still varies greatly between 58% and 94% , and the main reason for the failure of the surgery is the membranous closure of the anastomosis. The application of new packing materials in dacryocystorhinostomy provides some new ways to improve the success rate of En-DCR.

Hydroxybutyl chitosan (HBCS), with its non-toxicity, biocompatibility, biodegradability, antibacterial, moisturizing properties, water solubility and temperature sensitivity, is widely used in biomedicine to prevent postoperative adhesions.

5-Fluorouracil (5-FU) is an antimetabolite drug that is effective in the treatment of keloids. The application of 5-FU in glaucoma filtration surgery has demonstrated its good safety and efficacy. Studies have shown that antimetabolites as adjuvant therapy for DCR have a positive impact on improving the success rate of surgery In this study, thermosensitive hydroxybutyl chitosan will be applied to the anastomosis site of the nasal mucosal flap and the lacrimal mucosal flap, or 0.3ml of 5-fluorouracil solution (25mg/ml) was injected into the nasal mucosa around the anastomosis at the same time. The investigators would like to observe the different situations of clinical symptoms, lacrimal duct flushing, endoscopy, and bacterial flora changes in patients with chronic dacryocystitis, to compare them with the previous intraoperative packing of gelatin sponge wrapped with thrombin and Tobramycin Dexamethasone. Furthermore, the investigators intend to evaluate the safety and efficacy of HBCS and 5-FU adjuvant internal En-DCR in the treatment of chronic dacryocystitis, and provide new ideas for the adjuvant therapy of En-DCR.

Inclusion Criteria:

• Voluntary and able to sign an informed consent form
• Age ≥18 years
• Diagnosed with chronic dacryocystitis
• Willing and able to complete all planned visits and evaluations

Exclusion Criteria:

• Those who do not meet the inclusion criteria;
• Those who are allergic to hydroxybutyl chitosan and 5-fluorouracil;
• Patients suffering from blepharitis, hordeolum, blepharitis, ectropion, keratitis, lacrimal tumor and other external eye, ocular surface and other lacrimal diseases within three months, or those who have received eye surgery;
• Patients with chronic dacryocystitis and a history of lacrimal canal placement;
• Patients with history of lacrimal duct surgery and lacrimal duct fistula;
• Patients who have used glucocorticoid sprays within three months.
• Those who have had a history of facial trauma (eyelid trauma, nasal trauma, etc.) or have undergone facial surgery within three months;
• Abnormal nasal cavity or nasal diseases (nasal polyps, nasal tumors, turbinate hypertrophy, nasal bone fracture, etc.) within three months or those who have undergone nasal surgery;
• Patients with epiphora caused by other reasons such as facial paralysis or severe eyelid laxity;
• Those who suffer from autoimmune diseases, bleeding diseases, renal insufficiency dialysis treatment and other serious systemic diseases
• Patients with blisters or herpes zoster;
• Those with more serious skin diseases such as acne, rosacea or scar constitution;
• According to the investigator's judgment, it may interfere with Test results or medical history, personal history and allergy history that increase the risk of patients;
• Those who have participated in clinical trials of other drugs within the last 3 months;
• Those who cannot be followed up regularly or who cannot cooperate with the investigator.