Comparison of the Intrableb Characteristics of Anterior Segment Optical Coherence Tomography Imaging in Trabeculectomy according to Amniotic Membrane Transplantation

Abstract

Introduction: The purpose of this study was to compare the characteristics of filtering bleb with anterior segment optical coherence tomography (AS-OCT) according to amniotic membrane transplantation (AMT).

Methods: One hundred and sixteen eyes of 103 glaucoma patients who underwent trabeculectomy with (AMT group; 85 eyes) or without AMT (control group; 31 eyes) were included. Intrableb parameters were evaluated with AS-OCT. Surgical success was defined as an intraocular pressure (IOP) ≤18 mm Hg and IOP reduction ≥20% without medication at the time of AS-OCT examination. Logistic regression analyses were performed to determine factors associated with IOP control.

Results: In the eyes with successful IOP control, the fluid-filled space area, score, and height were greater for the AMT group than the control group (all ps < 0.001), while stripping layer thickness was greater and bleb wall reflectivity was lower for the control group than the AMT group (all ps < 0.001). Surgical success in the AMT group was associated with greater fluid-filled space score, lower bleb wall reflectivity, and microcyst formation (odds ratio [OR] = 8.016, 0.913, and 16.202, respectively, all ps ≤ 0.041). Lower bleb wall reflectivity alone was associated with surgical success in the control group (OR = 0.815, p = 0.019).

Conclusion: The extent of the fluid-filled space was associated with successful IOP control after trabeculectomy with AMT. Hyporeflective bleb wall was associated with successful IOP control in AMT and control groups.

Keywords: Amniotic membrane transplantation; Anterior segment optical coherence tomography; Bleb; Primary open-angle glaucoma; Trabeculectomy.

Fig. 1.

Surgical technique of amniotic membrane transplantation (AMT) over scleral flap during trabeculectomy. a Cryopreserved amniotic membrane was peeled from nitrocellulose filter paper. 15 × 15 mm single layer of amniotic membrane was placed over the scleral flap with the stromal side up. b The limbal side of the amniotic membrane was secured to both sides of the scleral flap margin with two micropoint 10-0 nylon vascular needles. The amniotic membrane was placed under Tenon’s capsule with the stromal side up using a muscle hook. c The conjunctiva and Tenon’s capsule were closed with interrupted micropoint 10-0 nylon vascular needles. For trabeculectomy without AMT, the same procedure was performed except for AMT.

Fig. 2.

Representative anterior segment optical coherence tomographic images of fluid-filled space score (FFSS) and measurements of intrableb parameters. a Fluid-filled space was diffuse and extended posteriorly beyond the field of image view (FFSS 2). b The fluid-filled space was limited and demarcated with a clear posterior margin (FFSS 1). c Fluid-filled space was not visible (FFSS 0). The white and white dotted two-way arrows indicate the bleb wall thickness and fluid-filled space height, respectively. The star indicates the fluid-filled space and the asterisk indicates scleral flap. The black arrow indicates the microcyst and the white arrow indicates visible amniotic membrane beneath the bleb wall.

Fig. 3.

Different intrableb structures of eyes in the same patient who underwent trabeculectomy with or without amniotic membrane transplantation (AMT). a Slit-lamp bleb photographic image of the right eye that underwent trabeculectomy with AMT. The bleb had diffuse, moderate height, and mild vascularity based on the Indiana Bleb Appearance Grading Scale (H2 E3 V2 S0) at 1.5 years after trabeculectomy with AMT. b Anterior segment optical coherence tomographic image of the right eye that underwent trabeculectomy with AMT. Diffuse and posteriorly extended fluid-filled space was noted with low bleb wall reflectivity and multiple microcysts. c Slit-lamp bleb photographic image of the left eye that underwent trabeculectomy alone without AMT. The bleb had diffuse, moderate height, and mild vascularity based on the Indiana Bleb Appearance Grading Scale (H2 E3 V2 S0) at 2 years after trabeculectomy alone. d Anterior segment optical coherence tomographic image of the left eye that underwent trabeculectomy alone without AMT. Multiple parallel hyporeflective layers and fluid-filled channels with striping phenomenon in Tenon’s capsule were noted. The star indicates the fluid-filled space, the black arrow indicates the microcyst, and the white arrow indicates visible amniotic membrane beneath the bleb wall. The white arrow head indicates the margin of hyporeflective layers with striping phenomenon.

Fig. 4.

Representative cases of anterior segment optical coherence tomography (AS-OCT) images in patients who underwent trabeculectomy with (a, c, e) or without (b, d, f) amniotic membrane transplantation (AMT). a AS-OCT image of the bleb in the AMT group showed diffuse and extended fluid-filled space (FFSS 2) and successful IOP control at 2 years after trabeculectomy. b The filtering bleb in the control group showed thick bleb wall with low reflectivity, multiple parallel hyporeflective layers and fluid-filled channels, microcysts and successful IOP control at 2.5 years after trabeculectomy. c AS-OCT image of the bleb in the AMT group showed bleb wall with low reflectivity and multiple microcysts, posteriorly extended fluid-filled space (FFSS 2), and successful IOP control at 2 years after trabeculectomy. The transplanted amniotic membrane was visible within the suprascleral space. d AS-OCT image of the bleb in the control group showed a thick bleb wall with striping phenomenon and successful IOP control at 2 years after trabeculectomy. e AS-OCT image of the bleb in the AMT group showed a thin and high reflective bleb wall regarded as an encapsulated bleb. IOP control was unsuccessful at 3 years after trabeculectomy. f AS-OCT image of the bleb in the control group showed a high reflective bleb wall with low bleb height and minimal fluid-filled space, and unsuccessful IOP control at 1 year after trabeculectomy. The star indicates the fluid-filled space and the asterisk indicates the scleral flap. The black arrow indicates microcyst and the white arrow indicates visible amniotic membrane beneath the bleb wall. The white arrow head indicates the margin of hyporeflective layers with striping phenomenon.