Bleb Analysis by Using Anterior Segment Optical Coherence Tomography in Two Different Methods of Trabeculectomy

Abstract

Citation: Hamanaka T, Omata T, Sekimoto S, Sugiyama T, Fujikoshi Y. Bleb analysis by using anterior segment optical coherence tomography in two different methods of trabeculectomy. Invest Ophthalmol Vis Sci. 2013;54:6536-6541. DOI: 10.1167/iovs.13-12439 PURPOSE. To investigate the correlation between bleb morphology and IOP control via the modified Indiana Bleb Appearance Grading Scale (IBAGS) and anterior-segment optical coherence tomography (AS-OCT) in two different trabeculectomy (TLE) groups.METHODS. This study involved 94 eyes with primary open angle glaucoma that underwent two different TLE methods: limbal-based TLE (group I, 62 eyes) and fornix-based TLE (group II, 32). IOP control was defined as successful with an IOP 20 mm Hg and ‡20% reduction of preoperative IOP. IBAGS and various parameters of the bleb height, extent, wall thickness, ciliochoroidal detachment (CCD), and lake under the scleral flap (LUSF) were obtained by slitlamp and AS-OCT, respectively. Correlation between IOP control and IBAGS/AS-OCT parameters were assessed by SAS.RESULTS. Both groups had the same success rate. As to correlation between IOP control and IBAGS, extent and Seidel were the best-paired parameters in group I (Cp ¼ 3.0402, R ¼ 0.6401), yet no parameter was significant in group II (maximum R ¼ 0.1599). As to correlation between IOP control and AS-OCT, the combinations of height, extent, and the minimum value of bleb wall thickness were significant (Cp ¼ 0.2037, 0.2314, R ¼ 0.4336, 0.4330) in group I. In group II, no parameter was significant, except CCD and/or LUSF (P ¼ 0.032). As to coincidence of IBAGS and AS-OCT parameters, height and extent in group I (P ¼ 0.000, P ¼ 0.000) and height in group II were statistically significant (P ¼ 0.020).CONCLUSIONS. IOP control in limbal-based TLE seemed to be more dependent on the large size and thinned-wall bleb than that in fornix-based TLE.

Comparison of bleb morphology between trabeculectomy and deep sclerectomy using a clinical grading scale and anterior segment optical coherence tomography

“…When calculating the correlation coefficients for IBAGS scores and final IOP at 3 months, we found that horizontal extent and vascularity were negatively correlated for both surgical groups (À0.74 and À0.46, respectively), meaning the broader and more vascular the bleb, the lower the IOP. In the study by Hamanaka et al, 19 they found that a wider bleb extent and leak showed success in IOP in limbal-based TRAB with no significant results for fornix-based TRAB.…”

“…There has been a movement from limbal-based TRAB to a fornix-based TRAB, as the former has a higher risk of developing an avascular bleb with subsequent blebitis than the fornix-based TRAB. 19,27 Unlike TRAB, DS is not entirely dependent on bleb formation. Once aqueous flows across an intact trabeculo-Descemet's membrane, it may enter (i) the open ends of Schlemm's canal; (ii) the intra-scleral space; (iii) the suprachoroidal space; or (iv) the subconjunctival space 6.…”

“…This reaffirms the notion that higher blebs and/or larger fluid reservoirs were important in achieving lower IOP following surgery. Singh et al 16 and Hamanaka et al 19 confirm the notion that AS-OCT and IBAGS analysis of bleb morphology can be used to predict the success of TRAB, which was dependent on a large-size bleb, albeit the latter study demonstrating improved IOP reduction with a thinner conjunctival wall.…”

“…16,17 AS-OCT offers superior image resolution compared with the ultrasound biomicroscopy and is more reproducible as it does not make contact during examination, hence will not alter morphology nor increase the risk of infection. 18,19 In this retrospective study, we investigated the use of the IBAGS and AS-OCT in measuring the bleb morphology of filtering blebs postoperatively in eyes that have undergone TRAB and DS. We also investigated the correlation of bleb morphology with postoperative IOP at 3 months.…”

Benefit of Measuring Anterior Segment Structures Using an Increased Number of Optical Coherence Tomography Images: The Chinese American Eye Study

“…AS-OCT imaging has provided insight into a wide variety of topics including anatomical changes after pupillary dilation and peripheral iridotomy, postsurgical changes after cataract surgery and trabeculectomy, and the relationship between intraocular pressure and the configuration of the anterior chamber angle. 2–12 …”