Intravitreal implants for drug delivery: clinical efficacy, safety, and translational perspectives

Chronic retinal disorders such as age-related macular degeneration, diabetic macular edema, retinal vein occlusion, and noninfectious uveitis are among the leading causes of irreversible visual loss worldwide. Their management depends on repeated intravitreal injections of anti-VEGF agents or corticosteroids, which, despite proven efficacy, are associated with high treatment burden and cumulative risks. Sustained-release intravitreal drug delivery systems (DDSs) are effective strategies to prolong therapeutic activity, enhance bioavailability, minimize adverse events, and improve patient adherence.

This review provides an overview of the evolution, clinical efficacy, and translational potential of intravitreal DDSs, from nonbiodegradable implants to biodegradable systems. Advances in polymeric design, hydrogels, in situ forming systems, and 3D-printed architecture, are discussed alongside emerging clinical candidates. Key formulation, preclinical, and regulatory barriers to clinical translation are also examined. Comprehensive search on PubMed, Scopus, Web of Science, ClinicalTrials.gov, and regulatory repositories was performed (data published up to December 2025).

Intravitreal DDSs are redefining ocular pharmacotherapy by offering prolonged, localized drug release. However, further innovation in polymer design, bioerodible materials, and sterilization methods is essential to balance safety, efficacy, and manufacturability. Integration of precision medicine and next-generation biomaterials will be key to achieving fully optimized, minimally invasive retinal therapies.