Novel Bleb Classification Following Ab Interno Implantation of Gel-Stent Using Anterior Segment Optical Coherence Tomography

Precis:A novel qualitative tomographical classification for bleb after implantation of XEN-Gel-Stent using ab interno approach is presented. Association of anatomic patterns to intraocular pressure (IOP) and success rates (SR) illustrates that anterior segment optical coherence tomography can be useful tool in clinical guidance. Purpose:To present a novel classification of bleb resulting from ab interno implantation of XEN-Gel-Stent and report association of tomographical patterns with IOP and SR. Materials and Methods:A cross-sectional 1-armed study of patients receiving XEN-Gel-Stent. Tomographical changes in the bleb area were studied using swept-source optical coherence tomography in an early (d 29-90 postsurgery) and late (starting from d 91 postsurgery) phase. Frequency of patterns and their association with IOP and SR (defined as IOP<18 mmHg without medications) were studied. Results:One hundred eleven examinations of 49 blebs (49 patients) were included. Three tomographical patterns at conjunctival, 4 at tenons capsule, and 2 at episcleral level were characterized. Most frequent conjunctival pattern was subconjunctival spaces (56.3% and 53.2% in the early and late phase, respectively) and associated with lower IOP (13.0 +/- 6.0 mmHg) and higher SR (89%) but only in the early phase compared with other conjunctival patterns (P<0.05). At tenons capsule level, the hyporeflective pattern was most frequent (50% and 51.9% in early and late phase) followed by the cavernous pattern. Both patterns associated with lower IOP and higher SR compared with hyper-reflective or loss of tenon changes (P<0.005). Most blebs showed no episcleral lake (87.5% and 89.9% in early and late phase). No difference of IOP and SR was noted compared with those showing an episcleral lake. Conclusion:A practical and clinically relevant novel classification system is proposed to tomographically describe and classify blebs after implantation of XEN-Gel-Stent. Certain patterns were associated with lower IOP and higher SR.