The Effect of Combined Phacovitrectomy on Aqueous Humor Cytokines in Patients with Proliferative Diabetic Retinopathy

Abstract

Purpose: To investigate the impact of combined phacovitrectomy versus vitrectomy alone on perioperative concentrations of vascular endothelial growth factor (VEGF) and interleukin-8 (IL-8) in the aqueous humor (AH) of patients with proliferative diabetic retinopathy (PDR). Methods: This prospective, comparative case series included 15 patients with PDR indicated for vitreoretinal surgery. AH samples were collected at three time points: preoperatively (one week prior to surgery), intraoperatively, and postoperatively (one month after surgery). Twelve patients underwent phacovitrectomy, and three patients underwent vitrectomy alone. All patients received a preoperative intravitreal bevacizumab injection. Concentrations of VEGF and IL-8 were quantified using enzyme-linked immunosorbent assay. Results: In the overall cohort, AH VEGF concentrations followed a U-shaped pattern, decreasing from a preoperative mean of 322.26 pg/ mL to an intraoperative mean of 45.47 pg/mL (p = 0.002) before significantly rebounding to 205.16 pg/mL postoperatively (p = 0.005 vs. intraoperative). This trend was driven by the phacovitrectomy group, which showed a significant postoperative VEGF rebound (p = 0.002). Conversely, the vitrectomy-only group showed no significant change. IL-8 concentrations increased significantly from the intraoperative to the postoperative period in the phacovitrectomy group (p = 0.003), a change not observed in the vitrectomy-only group. Conclusions: Phacovitrectomy induces a significant postoperative elevation of both VEGF and IL-8 in the anterior chamber, creating a pro-angiogenic and pro-inflammatory microenvironment. These findings provide a potential mechanistic explanation for increased risk of neovascular glaucoma observed clinically following combined phacovitrectomy.