CCL2 and macular retinal edema: High levels of inflammatory cytokines, such as interleukin family members and monocyte chemotactic protein-1 (MCP-1) (Felfeli et al., 2019; Abraham et al., 2021), are also strongly associated with macular edema, which if existed or progressed after vitrectomy, will compromise the visual prognosis of PDR (Im et al., 2017).