Ostium Characteristics and Its Relevance in Successful Outcome Following Endoscopic Dacryocystorhinostomy.

Study aims to assess the postoperative ostium shrinkage pattern and also attempted to evaluate various ostium parameters and their impact on surgical outcome by using DOS scoring system. Prospective study comprising 44 patients of NLD obstruction with 52 procedures performed during October 2016 to November 2018. Various dimensions of bony neo-ostium were recorded intraoperatively and during 1st, 3rd and 6th month follow up. Degree of ostium shrinkage and its correlation with anatomical and functional success was studied. DCR ostium (DOS) scoring system, comprised of ten various ostium parameters, was used to evaluate postoperative ostium. Intraoperative mean ostium height and width were 13.67 ± 2.76 mm and 7.0 ± 1.94 mm and surface area was 98.33 ± 38.46 mm. Maximum ostium shrinkage (by 66.93%) occurred at 1 month and after which, average size of ostium was quite stable with little change. The anatomical and functional success rate was 94.23% and failure rate was 5.77%. DOS score was "excellent" in 40(75.92%), "good" in 9(17.31%) and "poor" in 3(5.77%) cases. Meticulous evaluation at regular intervals is important for surgeon to understand the characters of ostium during healing and also helps in early detection of pathologies and may facilitate early corrective intervention. We believe that DOS system provides an effective protocol to standardize the ostium evaluation. The ostium parameters with favourable surgical outcome are ostium location anterior to axilla of MT, circular/ oval shape with shallow base, size > 8 × 5 mm, clearly visualized and dynamic ICO, absence of ostium cicatrization, granulomas, synechiae and other pathologies.