Risk Factors for Postoperative Hyphema Following Baerveldt Glaucoma Implant Surgery: A Retrospective Cohort Study

Background/Objectives: To investigate the incidence and risk factors for postoperative hyphema following Baerveldt glaucoma implant (BGI) surgery. Methods: This retrospective study included Japanese patients who underwent BGI surgery at Fukui University Hospital between 1 April 2012 and 31 March 2025. Hyphema was defined as any clinically detectable blood in the anterior chamber. Baseline demographic, ocular, and surgical variables were compared between eyes with and without hyphema. Independent risk factors for hyphema were determined using multivariable logistic regression analysis. Results: Of 273 eyes, 77 (28.2%) developed postoperative hyphema. On multivariable analysis, tube insertion site and intraocular pressure (IOP) on postoperative day 1 were identified as independent predictors. Although the overall effect of tube insertion site was borderline (p = 0.074), anterior chamber (odds ratio [OR], 2.83; p = 0.036) and ciliary sulcus insertion (OR, 2.88; p = 0.031) were associated with significantly higher risk of hyphema compared with vitreous cavity insertion. Lower postoperative day 1 IOP was also a significant predictor (p < 0.01). Patient-related factors, including age, diabetes mellitus, hypertension, antithrombotic therapy, neovascular glaucoma (NVG), combined surgery, number of previous intraocular surgeries, and preoperative IOP, were not independently associated with hyphema. In a sensitivity analysis excluding NVG eyes (n = 191), vitreous cavity insertion remained protective, and postoperative day 1 IOP remained an independent predictor. Conclusions: Postoperative hyphema following BGI surgery is primarily determined by surgical factors and early postoperative IOP. Vitreous cavity tube insertion is associated with a markedly lower hyphema risk than anterior chamber or ciliary sulcus insertion.