Recent Progress in Selenium Nanomedicines for Ocular Diseases

Vision impairment represents a significant and growing global socioeconomic burden. In the elderly population, cataracts, age-related macular degeneration (AMD), glaucoma, and diabetic retinopathy (DR) are the predominant causes of visual loss. Conventional ophthalmic drug therapies are limited by low bioavailability and dose-related toxicity, highlighting the urgent need for safer and more effective treatments. Selenium (Se), an essential trace element, is critical for antioxidant defense, redox homeostasis, and immune regulation. Although the roles of elemental Se in ocular physiology and diseases are well-documented, its clinical application is constrained by its narrow therapeutic window and poor bioavailability. To overcome these limitations, Se nanoparticles (SeNPs) have emerged as a superior alternative, offering enhanced bioavailability, reduced toxicity, and the capability for targeted drug delivery. Strong preclinical evidence supports the therapeutic potential of Se nanomedicines in models of DR, retinal neovascularization, infectious keratitis, and cataracts. Significantly, the initial stages of clinical translation are in progress, as demonstrated by a pioneering Phase I trial involving CdSe/ZnS quantum dots (QDs) in patients with retinitis pigmentosa (RP), which has shown both tolerability and improvements in visual function. This review provides a comprehensive and up-to-date analysis of Se-based nanomedicines for ocular diseases, based on a literature search of PubMed, Scopus, Web of Science, and Google Scholar. It elucidates how SeNPs uniquely synergize intrinsic multi-mechanistic bioactivities (e.g., antioxidant, anti-angiogenic) with targeted and stimuli-responsive drug delivery, establishing them as versatile nanoplatforms with significant clinical translation potential for complex ocular pathologies. Therefore, further research is essential to optimize their design, elucidate their mechanisms of action, and ultimately facilitate their safe and effective clinical translation.