A novel technique of rhinostomy size assessment by immersion b-scan probe following dacryocystorhinostomy - A comparative study.

PURPOSE: To measure and compare the ostium size following external and endoscopic dacryocystorhinostomy (DCR) using an innovative, noninvasive immersion B-scan ultrasonography technique and to correlate ostium dimensions with functional patency assessed by the fluorescein dye disappearance test (FDDT). METHODS: This prospective comparative study included 50 patients with nasolacrimal duct obstruction who underwent either external (n = 25) or endoscopic DCR (n = 25) between September 2022 and February 2024. Intraoperative ostium size was measured using Castroviejo's calipers for external DCR and Schirmer's strips for endoscopic DCR. Postoperative ostium dimensions (length, width, and area) were assessed on days 15, 30, and 90 using an immersion B-scan probe. Functional patency was evaluated by FDDT. Data were analyzed with ANOVA and multilinear regression. RESULTS: The mean age was 54.9 ± 13.26 years in the external DCR group and 51.76 ± 13.79 years in the endoscopic group, with female predominance (78%). At 3 months, the external DCR group showed a significantly larger ostium size (length: 11.66 ± 2.12 mm; width: 7.09 ± 1.28 mm; area: 78.91 ± 24.47 mm 2 ) compared to the endoscopic group (length: 9.84 ± 0.88 mm; width: 6.46 ± 1.14 mm; area: 58.95 ± 16.25 mm 2 ) ( P < 0.05). External DCR demonstrated superior functional patency with an FDDT sensitivity of 91% and better F1 scores throughout follow-up. CONCLUSION: Immersion B-scan ultrasonography is a reliable, noninvasive tool for postoperative assessment of ostium dimensions. External DCR results in a larger ostium size and better functional patency than endoscopic DCR.