Nanocarrier-Based Ocular Drug Delivery Systems for Retinal Diseases: Mechanisms and Therapeutic Potential

Background: Posterior segment eye diseases, including age-related macular degeneration and diabetic retinopathy, are preeminent causes of vision loss worldwide. Effective drug delivery to the retina poses an ongoing therapeutic difficulty due to the presence of the anatomical and physiological barriers. Nanotechnology-based drug delivery systems represent a promising strategy to overcome those limitations. Methods: A narrative literature review was conducted using the PubMed, Scopus, and Google Scholar databases, covering publications published between 2020 and 2026. Publications evaluating nanoparticles for the treatment of the vitreoretinal disorders, including pre-clinical in vitro and in vivo studies, were analyzed. Results: Nanocarriers, including liposomes, polymeric nanoparticles, and lipid-based systems, established improved drug bioavailability, stability, and targeted delivery. The analyzed systems facilitate sustained drug release and potentially reduce the prevalence of invasive intravitreal injections. The nanocarriers’ effectiveness is primarily influenced by their physicochemical properties, such as particle size, surface charge, and encapsulation efficiency. Nonetheless, the production costs and safety aspects, including cytotoxicity, oxidative stress, and inflammatory responses, remain as significant limitations. Conclusions: Nanotechnology-based drug delivery systems serve as an auspicious therapeutic approach for posterior segment eye diseases. However, further standardized preclinical and clinical research is required to assure long-term safety, and enable successful clinical transition.