Filtering blebs using 3-dimensional anterior segment optical coherence tomography: A prospective investigation

Importance Posttrabeculectomy changes in bleb parameters measured using 3-dimensional (3-D) anterior-segment optical coherence tomography (OCT) remain uncharacterized and might be related to postsurgical intraocular-pressure (IOP) control. Objective To evaluate time-dependent posttrabeculectomy changes in filtering bleb parameters using 3-D anterior-segment OCT. Design, Setting, and Participants This prospective observational study was conducted at Kumamoto University Hospital, Kumamoto, Japan. Patients with open-angle glaucoma who underwent uncombined fornix-based trabeculectomy at Kumamoto University Hospital between January 1, 2012, and October 31, 2012, were included. Twenty-nine eyes were enrolled, 23 of which were followed up for 1 year without additional glaucoma surgical procedures; 3 required additional glaucoma surgery. Interventions Imaging filtering blebs using 3-D anterior-segment OCT. Main Outcomes and Measures The primary end points were changes in bleb parameters including the position and width of the filtration openings on the scleral flap, the total bleb height, fluid-filled cavity height, bleb wall thickness, and bleb wall intensity, which were measured using 3-D anterior-segment OCT. The secondary end points were postsurgical IOP measured 0.5, 3, 6, and 12 months after trabeculectomy, and the effects of aqueous cytokine levels on the bleb parameters. Results We observed increased total bleb height (0.82 to 1.25 mm; difference: 95% CI, 0.10 to 0.75; P  = .01), bleb wall thickness (0.46 to 0.61 mm; difference: 95% CI, 0.02 to 0.28; P  = .03), and distance from the top of the scleral flap to the filtration opening (1.69 to 2.16 mm; difference: 95% CI, 0.28 to 0.70; P P  = .002) between 0.5 and 12 months posttrabeculectomy. The filtration openings tended to close from the fornix side of the scleral flap during the wound healing process. Moreover, the width of the filtration opening at 0.5 months posttrabeculectomy correlated with the IOP at 12 months ( P  = .02). The aqueous humor level of monocyte chemoattractant protein–1 was correlated with the width of the filtration opening at 3 and 6 months posttrabeculectomy. Conclusions and Relevance The width of the filtration opening at 0.5 months posttrabeculectomy correlated with the IOP at 12 months. The width of the filtration opening at the early stage may be a prognostic factor for long-term IOP control. Large-scale studies with longer follow-up periods are required.