Filtering Blebs Using 3-Dimensional Anterior-Segment Optical Coherence Tomography

Abstract

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 < .001), as well as decreased width of the filtration opening (2.08 to 1.12 mm; difference: 95% CI, −1.75 to −0.49; 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 RELEVANCEThe 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.

Quantification of the filtering bleb's structure with anterior segment optical coherence tomography

“…The reliability of bleb horizontal brightness was also confirmed to be very high. Thus, though there have been earlier papers describing an association between AS‐OCT structural parameters and IOP control more than 6 months after surgery, this is the first report in patients who did not undergo post‐operative medical or surgical treatment to show that quantitative AS‐OCT parameters of postoperative bleb structure can serve as prognostic factors of IOP 6 months after TLE.…”

“…A number of previous studies have reported that various AS‐OCT and confocal microscopy measurement parameters are associated with the function of the bleb, including low intrableb reflectivity, an extensive hyporeflective area, the presence of an aqueous outflow channel at the scleral flap, a large number of microcysts, a large internal fluid‐filled cavity, a large subconjunctival hyporeflective space with multiloculated collections of fluid and loosely arranged sub‐epithelial connective tissue . Furthermore, a recent report on AS‐OCT measurement of the bleb revealed the importance of the width of the filtration opening at an early stage, and showed that it may be a useful prognostic indicator of long‐term IOP control . However, to the best of our knowledge, there are no reports analyzing the power of quantitative AS‐OCT parameters of postoperative bleb structure to directly predict future bleb function in patients not undergoing post‐operative treatment with antiglaucoma medication and not having undergone postoperative interventions such as needling, direct suturing and blocking suturing.…”

Effect of laser suture lysis on filtration openings: a prospective three-dimensional anterior segment optical coherence tomography study

“…Seven patients were included in our past prospective study. 13 Six patients had a history of cataract surgery prior to the subjective trabeculectomy. Of those, two eyes received vitrectomy at that time.…”

“…In addition, they compared the images before LSL and 2 weeks after LSL, while the average interval of the comparison in our study was 5.1 ± 3.8 days. As bleb morphology changes with time, 13 the difference in observation times might explain the contradictory results. Furthermore, Singh et al evaluated the increase in bleb height in a qualitative manner by comparing it with scleral thickness without statistical analysis, while our comparison was quantitative.…”

“…9,10 In our previous studies we obtained 512 3D scans that were rotated using newly developed software (CASIA bleb-assessment software, Tomey) and matched with reconstructed C-scan images (tomographic image of the slice plane perpendicular to the depth direction) to precisely identify the filtration openings on the scleral flap. [11][12][13][14] Filtration openings were identified in 95% (118 of 124) of the eyes; the location of the openings was also visualized. We found that the pattern of filtration openings was not affected by the residual suture after laser application in this small case series of laser suture lysis (LSL).…”