Angiographic biomarkers of filtering bleb function after XEN gel implantation for glaucoma: an optical coherence tomography‐angiography study

Abstract

Abstract Purpose To evaluate, using optical coherence tomography‐angiography (OCT‐A), the vascular features of good bleb function after XEN gel implantation (XGI) for uncontrolled glaucoma. Methods Forty‐three patients (43 eyes), who underwent XGI, were enrolled. According to the intraocular pressure (IOP) reduction, patients were classified into Group 1 (21 eyes; success) and Group 2 (22 eyes; failure). Optical coherence tomography‐angiography (OCT‐A) was performed to image the vascularization of the conjunctival bleb‐wall. The main outcomes were as follows: vessel displacement areas (VDAs), major vessel displacement area (MVDA; mm 2 ), non‐flow whole area (NFWA; mm 2 ) and bleb‐wall vessel density (BVD; %). Co‐registered B‐scans were also considered to evaluate the bleb‐wall cyst‐like structure density and area (BCSD, cysts/mm 2 ; BCSA, mm 2 ), and the bleb‐wall thickness (BT, µm). Results Mean postoperative follow‐up was 7.5 ± 0.14 months; Group 1 and 2 IOP were 14.0 ± 2.5 and 25.3 ± 2.1 mmHg, respectively (p < 0.001). Greater VDA (p < 0.001), MVDA (p = 0.046) and NFWA (p = 0.001) values, and lower BVD (p < 0.001) was found in Group 1 compared to Group 2. Group 1 showed higher BSCD, BSCA and BT values compared to Group 2 (p < 0.001). Postoperative IOP positively correlated with BVD ( r = 0.567; p = 0.003), but negatively with VDAs, MVDA ( r = −0.581, p = 0.002; r = −0.619, p = 0.001, respectively), BCSD, BCSA ( r = −0.580; p = 0.002; r = −0.664; p < 0.001) and BT ( r = −0.627, p = 0.001). Conclusion Successful filtration blebs after XGI present numerous and large areas of vessel displacement within the bleb‐wall, along with a rarefied vascular network. These OCT‐A features can be considered angiographic biomarkers of a good aqueous humour percolation through the bleb‐wall layers.

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