The Morphometric Analysis of Filtering Bleb Using Anterior Segment Optical Coherence Tomography: Pilot Study

Abstract

Purpose: To evaluate intrableb morphology and function after trabeculectomy using anterior segment optical coherence tomography (AS-OCT) Methods: Twenty-eight post-trabeculectomy eyes from patients with primary open-angle glaucoma were examined using AS-OCT. Intrableb structures, including bleb wall thickness, subconjunctival fluid, suprascleral fluid and the route under the scleral flap, were measured at the center of the bleb using AS-OCT and were classified according to their slit-lamp appearance. Blebs were classified as successful (IOP18 mmHg without ocular hypotensive medication) and failed (IOP>18 mmHg or use of ocular hypertensive medication.) in order to compare parameters between the two groups. Results: The blebs were classified as either diffuse filtering (n=17), cystic (n=5), encapsulated (n=3) or flattened (n=3) according to slit lamp appearance and were correlated with AS-OCT images. Blebs were classified as successful and failed in order to compare parameters between the two groups. Significant differences were observed between the two groups in regard to subconjunctival fluid space (p=0.0004). No significant differences were observed in bleb wall thickness (p=0.098), suprascleral fluid space (p=0.87) or the route under the scleral flap (p=0.196). Conclusions: AS-OCT images of the intrableb structures were correlated with the appearance of the slit lamp, and a large subconjunctival space was associated with good bleb function. AS-OCT is useful for evaluating blebs; further studies should be performed to verify these findings.