Characteristic Assessment of Angiographies at Different Depths with AS-OCTA: Implication for Functions of Post-Trabeculectomy Filtering Bleb

Abstract

This study aimed to analyze the quantitative vascular biomarkers of filtering bleb function at different depths using anterior segment optical coherence tomography angiography (AS-OCTA). This cross-sectional study is registered on Clinicaltrails.gov (NCT 04515017). Forty-six eyes with primary open-angle glaucoma that had undergone trabeculectomy with mitomycin-C for more than six months were included. Vessel density (VD) and vessel diameter index (VDI) in the superficial layer (SL), Tenon’s layer (TL), and deep layer (DL) of the bleb were obtained. The VD and VDI were higher in the failure group (both p = 0.000). Significant correlations were found between the SL, TL, DL’s VDI, and IOP in the success group (p = 0.013, 0.016, 0.031, respectively). The VD of the TL and DL were related to IOP in the failure group (p = 0.012, 0.009). Tenon’s VD (TVD) and Tenon’s VDI (TVDI) correlated with IOP adjusting for TVD, TVDI, and the Indiana Bleb Appearance Grading Scale (IBAGS) (p = 0.009, 0.043) or Kenfeld grading system (KGS) (p = 0.011, 0.016). The area under curve (AUC) of the TVD, TVDI, IBAGS, and KGS to predict surgery failure were 0.960, 0.925, 0.770, and 0.850. AS-OCTA realized the quantitative evaluation of vessels, especially the invisible vascularity beneath the conjunctiva. TVD and TVDI as detected by AS-OCTA better reflected bleb function than conventional grading systems.

Multi-Quantitative Assessment of AS-OCTA Complemented AS-OCT for Monitoring Filtering Bleb Function After Trabeculectomy

“…The previous study showed a better correlation between VD and postoperative IOP results than that obtained with the IBAGS and MBGS. 28 The slit-lamp classifications were subjective, and their AUC was relatively unsatisfactory. MVMS-BH-MCS presented by the Loess plot, a value of 17.61 was used as an early warning biomarker of the functional change of the filtering blebs.…”

“…), as previously described. 28 Briefly, the operator made a rectangular scleral flap at the size of 3 × 4 mm, and the cotton containing MMC was put for 2 minutes (Hanhui Pharmaceuticals Co., Ltd, China; 10 mg/vial). A piece of trabecular meshwork was removed, and a peripheral iridectomy was performed.…”

“…AS-OCTA was performed by a single trained operator using OCTA scanning (6 × 6 mm HD Angio Disc protocol) with XR Avanti and AngioVue software (Optovue, Inc., Fremont, CA, USA), as our previous described. 28 The Avanti OCT used the separated spectrum amplitude decorrelation algorithm (SSADA). 29 It used an 840-nm centered light source capable of 70,000 A-scans per second, and had a 5 µm axial resolution.…”

“…Vessel diameter index (VDI) was calculated as 10 times the ratio of the total image area occupied by the skeletonized vessel area. 28 , 30 …”