Evaluation of Successful and Failed Filtering Blebs after Trabeculectomy Using Anterior Segment Optical Coherence Tomography

Abstract

Purpose: To evaluate filtering bleb characteristics using anterior segment optical coherence tomography (AS-OCT) and analyze correlations between these parameters and intraocular pressure (IOP). Methods: The study included 54 eyes of 43 patients who underwent trabeculectomy with mitomycin-C. The patients were divided into two groups based on mean postoperative IOP. The criterion for surgical success was mean unmedicated postoperative IOP ≤18 mmHg. Patients with IOP values >18 mmHg were prescribed anti-glaucoma drops and classified as a surgical failure. All patients underwent AS-OCT, and maximum bleb height, maximum bleb wall thickness, and maximum fluid-filled cavity height were measured. AS-OCT bleb parameters were compared between the successful and failed groups. Results: Of the 54 eyes, 37 (68.5%) were in the successful group, and 17 (31.5%) were in the failed group. Mean preoperative IOP values in the successful and failed groups were 26.9 ± 6.5 mmHg and 22.9 ± 4.9 mmHg, preoperatively, versus postoperative values of 13.3 ± 2.1 mmHg and 22.8 ± 2.8 mmHg, respectively. Mean postoperative follow-up time was 17.4 ± 9.5 months in the successful group and 19.1 ± 10.1 months in the failed group (P = 0.22). In the successful and failed groups, mean bleb height was 1473.7 ± 150.6 μm and 1165.4 ± 217 μm (P < 0.001), bleb wall thickness was 670.5 ± 119.9 μm and 538.8 ± 144.3 μm (P = 0.001), and fluid-filled cavity height was 736.5 ± 196.8 μm versus 532.5 ± 226.2 μm (P = 0.001), respectively. Conclusions: The results of this study showed that higher AS-OCT values for bleb height, wall thickness, and fluid-filled cavity height were associated with greater functional success. These parameters may be helpful in determining bleb functionality.