Characteristics of early filtering blebs that predict successful trabeculectomy identified via three-dimensional anterior segment optical coherence tomography

Background/aims To identify the cross-sectional characteristics of filtering blebs at 2 weeks post-trabeculectomy associated with intraocular pressure (IOP) control at 1year post-trabeculectomy. Methods Ninety-nine eyes of 94 patients who had undergone primary trabeculectomy were included in this retrospective consecutive case series study. Surgical success was defined as an IOP 15mm Hg and a >20%reduction in IOP without glaucoma medication or additional glaucoma surgeries at 1year post-trabeculectomy. Subjects were classified into two groups according to whether surgery was successful or unsuccessful. Blebs were examined using swept-source three-dimensional anterior segment optical coherence tomography and evaluated for quantitative parameters, including maximum height, maximum wall thickness and ratio of hyporeflective space of the wall, as well as qualitative parameters, including multiple parallel hyporeflective layers within the wall (striping phenomenon), decreased visibility of the sclera underlying the bleb (shading phenomenon) and cyst-like structures of the wall. Results Seventy-seven eyes (77.8%) were assigned to the successful group and 22 (22.2%) to the unsuccessful group. Univariate analysis showed significant differences between the groups regarding maximum bleb height (p=0.044), maximum bleb wall thickness (p=0.017) and the striping phenomenon of the bleb wall (p=0.007). Multivariate logistic regression analysis confirmed that the striping phenomenon at 2 weeks post-trabeculectomy was significantly associated with success at 1year post-trabeculectomy (OR 3.405; 95% CI 1.059 to 10.947; p=0.040). Conclusion Taller blebs with thicker walls that showed the striping phenomenon at 2 weeks post-trabeculectomy appeared to predict good IOP control at 1 year post-trabeculectomy.