Teus MA, et al. - In this cross-sectional, observational study, 25 eyes were analyzed to study the morphology of blebs formed in eyes treated with XEN implants and the blebs in successfully functioning eyes following trabeculectomy (TB) vs eyes of healthy controls. In eyes in which a XEN stent was implanted, the filtering blebs formed were significantly flatter (bleb height 417 ± 183 μm) as compared to the blebs formed in TB eyes (bleb height 618 ± 256 μm). They also recorded that sub-epithelial fibrosis did not develop in any of the blebs generated by the XEN stent, whereas some fibrosis was apparent in 40% of the blebs formed after TB. When the XEN implant was used the epithelium was thicker (65 ± 18.5 μm) vs when eyes underwent TB (60 ± 17.7 μm), and also thicker in comparison to control eyes (51 ± 9.7 μm). They noted a similar decrease in the IOP induced by the XEN stent (− 8.5 ± 5.3 mmHg) to that produced by TB (− 8.8 ± 5.2 mmHg).