Abstract： Objective To investigate the relationship between the morphological characteristics of the filtering bleb following trabeculectomy and intraocular pressure and surgical outcome.Methods A prospective study.Patients who had undergone trabeculectomy were followed six times over one year.Morphologic features were assessed by anterior seg-ment optical coherence tomography(AS-OCT).The variance of each feature,the relationships between features and intra-ocular pressure(IOP),and the surgical outcomes were investigated.Results IOP at postoperative week 2 was signifi-cantly lower than at postoperative 3,6 and 12 months(P<0.00238).Patients with a broader distribution of microcysts were predominant at two weeks postoperatively,while those without microcysts were the least prevalent.The proportion of blebs with flat-mild bulge gradually increased within 1-year postoperatively,while the proportion of"wide"blebs gradually decreased.Patients with more subconjunctival cysts gradually decreased after 6 months postoperatively.At postoperative week 2,the indicator of IOP is encapsulation,vascularity,and microcysts(P<0.05).Morphological classification under AS-OCT at two weeks postoperatively was a significant predictor of long-term surgical outcomes(P<0.001).Conclu-sions AS-OCT is an effective tool for evaluating blebs.Diffuse blebs at postoperative 2 weeks are more likely to achieve long-term success,while encapsulated blebs are more likely to fail.