Tiny tools, big vision: A minireview on carbonized nanomaterials in ophthalmology

Ocular diseases represent a persistent global health burden due to the complex anatomical and physiological barriers of the eye, which limit effective drug delivery. Conventional therapies such as topical eye drops or systemic medications often suffer from poor bioavailability, rapid clearance, and limited tissue penetration, resulting in inadequate therapeutic outcomes and diminished patient compliance. The advent of nanotechnology has opened new avenues for overcoming these challenges, with carbon-based nanomaterials, particularly carbon dots (CDs), emerging as an up-and-coming class for ocular applications. CDs possess a unique combination of advantageous properties, including intrinsic antibacterial, antioxidant, anti-inflammatory, and anti-angiogenic activities, high biocompatibility, tunable surface chemistry, and strong photoluminescence. These features not only enable multifunctional therapeutic action but also facilitate real-time bioimaging and theranostic applications. Compared to other nanomaterials, such as carbon nanotubes, graphene oxide, or metallic nanoparticles, which often exhibit ocular toxicity or limited biodegradability, CDs offer a superior safety profile, minimal cytotoxicity, and sustained retention at ocular target sites. The facile surface functionalization of CDs enables their integration into a wide array of delivery systems, such as nanogels and in situ-forming gels, allowing for controlled and prolonged drug release. This review comprehensively explores the multifaceted therapeutic potential of CDs in treating various ocular disorders, including microbial keratitis, retinal neovascularization, dry eye syndrome, and vitreous opacities. In addition, we address key safety considerations and discuss the translational prospects of CD-based nanomedicine, underscoring their transformative potential in next-generation ocular therapeutics.