Ocular inflammation after intraocular drug delivery: Mechanisms, risk factors, and implications for clinical practice

Ocular inflammation is a well-known complication of intraocular drug delivery. While relatively rare, it can lead to serious outcomes, including retinal vasculitis and vascular occlusion that are among the most feared adverse events in ophthalmic practice. These reactions have received increasing attention with the widespread use of anti-vascular endothelial growth factors and, more recently, anti-complement therapies. In this review, we discuss current concepts of post-injection inflammation, linking experimental findings with clinical experience. We consider how drug formulation, immune responses, delivery techniques, and the use of silicone oil-coated syringes may contribute to inflammatory risk, and how these factors differ between agents. Particular emphasis is placed on distinguishing infectious from sterile inflammation, a critical step for timely and appropriate management. Using evidence from clinical trials and real-world studies, we compare patterns of intraocular inflammation reported with different intraocular therapies and outline practical considerations for prevention, recognition, and treatment. As intraocular therapies continue to evolve, understanding and addressing these complications remains essential for safe and effective ophthalmic care.