Histopathological findings of failed blebs after microinvasive bleb surgery with the XEN Gel Stent and Preserflo MicroShunt

The success of XEN Gel Stent (XEN) and Preserflo MicroShunt (Preserflo) implantation depends mainly on the development of bleb fibrosis. This study aimed to describe the histological findings of bleb fibrosis after XEN and Preserflo surgery. This retrospective study included patients with different types of glaucoma who underwent revision surgery after XEN or Preserflo implantation. The available clinical information and histological samples of removed fibrotic tissue were analyzed. Thirty-six patients were included. Revision surgery was performed at a median of 195 (range = 31–1264) days after primary surgery. The mean intraocular pressure changed from 29.1 (± 10.3) mmHg at baseline to 18.3 (± 8.7) mmHg (− 37