Participants
CRS patients over 18 years old who indicated and were scheduled for ESS between
January 2020-August 2021 were enrolled in this study. The diagnosis of CRS was based on the criteria according to a European position paper on rhinosinusitis and nasal polyps.(12)  The exclusion criteria included patients with underlying diseases that affect mucociliary function, i.e., cystic fibrosis, ciliary dyskinesia, previous radiotherapy at head and neck regions, patients who had previous sinonasal surgery or sinonasal tumors, patients who had evidence of sinus aplasia or severe deviated nasal septum on computerized tomography (CT) scan, pregnant women, patients who had allergic to fluorescein and who refused to participate in the study.
All patients underwent preoperative CT scan of the nose and paranasal sinuses, and Lund-Mackay (LM) staging system (13) , was assessed for each nasal cavity separately. Nasal endoscopic exam was carried out to distinguish phenotype features, CRS with nasal polyp (CRSwNP) and CRS without nasal polyp (CRSsNP). In addition, the participants completed the Thai Sinonasal Outcome Test 22 items (SNOT-22)(14) on the admission date for a baseline assessment.