RESUMO
BACKGROUND: The implantation of a XEN gel stent is an innovative method for filtration surgery using an ab interno approach. The morphological evaluation of the resulting bleb is decisive for surgical success. Bleb revision is frequently needed after XEN implantation and might affect the bleb morphology. Aim of this study was to examine bleb morphology using anterior segment OCT (AS-OCT) and analyze the morphological differences of blebs after primary XEN implantation and after bleb revision. MATERIAL AND METHODS: Included were eyes that underwent XEN implantation (Pr-X) or bleb revision after XEN (ReX group). An AS-OCT of blebs was performed and images were classified using a novel classification system (the Jenaer bleb grading system, JBGS). Frequency of different tomographic patterns (M) and their correlation with intraocular pressure (IOP) were analyzed. RESULTS AND DISCUSSION: A total of 69 eyes (40 in the PrX and 29 in the ReX groups) were included. At the conjunctival level, the most common M in both groups was subconjunctival spaces (M-C2) followed by intraconjunctival cysts (C1) and no conjunctival changes (C0). No differences of frequencies between the two groups or of IOP between the three Ms were seen. At the tenon level, the most commonly seen Ms in the PrX group were hyporeflective and cavernous changes (M-T2, T3) followed by no changes (M0) and hyperflective changes (T1). In the ReX group, the MT1 and T2 were most commonly seen followed by T3 and T0. The MT2 and T3 in the PrX group and the MT1 and T2 in the ReX group correlated with lower IOP. An episcleral lake (M-ES1) was seen significantly less frequently in the PrX group compared with ReX group where it correlated with lower IOP CONCLUSION: The hyperreflective changes at the tenon level and the presence of an episcleral lake were seen more frequently following bleb revision compared with primary XEN implantation and correlated with lower IOP. The interpretation of bleb morphology using AS-OCT should only be done considering the surgical approach used.