Characteristics of successful filtering blebs at 1 year after trabeculectomy using swept-source three-dimensional anterior segment optical coherence tomography

Purpose: To identify the cross-sectional characteristics of filtering blebs associated with intraocular pressure (IOP) control at 1 year after trabeculectomy with a square scleral flap and a fornix-based conjunctival flap. Methods: A retrospective consecutive case series study was conducted. Eighty-four eyes of 79 patients who had undergone primary trabeculectomy were included. Surgical success was defined as IOP ≤15 mmHg and a >20% reduction in IOP without glaucoma medication and without additional glaucoma surgery at 1 year after trabeculectomy. The subjects were classified into two groups according to whether surgery was successful or unsuccessful. Filtering blebs were examined using swept-source three-dimensional anterior segment optical coherence tomography and evaluated for the following quantitative parameters: maximum bleb height, maximum bleb wall thickness, and ratio of hypo-reflective space of the bleb wall. Results: Sixty-six eyes were determined to be successful and 18 eyes unsuccessful. Univariate analysis showed significant differences between the two groups regarding bleb height (P < 0.001), bleb wall thickness (P = 0.011), and ratio of hypo-reflective space of the bleb wall (P = 0.002). Multivariate logistic regression analysis confirmed that the bleb height was significantly associated with success in trabeculectomy [odds ratio 13.996 (95% confidence interval 1.184–165.420); P = 0.036]. Conclusion: A tall bleb with a thick hypo-reflective wall may be a feature of the well-functioning bleb.