Purpose: To evaluate the effects of intervals between preoperative intravitreal injection of bevacizumab (IVB) and surgery on the components of removed diabetic fibrovascular proliferative membranes.
Design: interventional, consecutive, prospective, comparative case series,
Participants: A total of 52 eyes of 49 patients with active diabetic fibrovascular proliferation with complications necessitating vitrectomy.
Methods: Participant eyes that had IVB were divided into 8 groups in which vltreoretinal surgery was performed at days 1, 3, 5, 7, 10, 15, 20, and 30 postinjection. A group of eyes with the same diagnosis and surgical intervention without IVB injection was used for comparison. In all eyes, proliferative membrane specimens obtained during vitrectomy were sent for histopathologic examination using hematoxylin-eosin stain, immunohistochemistry (CD34 and smooth muscle actin), and Masson's trichrome stain.
Main Outcome Measures: Cornparative analysis of different components of the fibrovascu!ar proliferation (CD34, smooth muscle actin, and collagen) among the study groups.
Results: Pan-endothelial marker CD34 expression levels starting from day 5 postinjection were significantly less than in the control group IP