Nanomaterial-enabled smart contact lenses: bridging sensing, therapy, and theranostics for next-generation ocular healthcare

Smart contact lenses (CLs) are emerging as multifunctional biomedical platforms that merge vision correction with advanced diagnostic and therapeutic capabilities. By integrating nanomaterials with tailored optical, electronic, and structural properties into soft hydrogel matrices, CLs can continuously interface with tear fluid, enabling real-time access to a rich spectrum of ocular and systemic biomarkers. This review highlights the functional roles of nanomaterials in enabling electrochemical, plasmonic, and SERS-based diagnostics, as well as controlled release, photothermal, and antimicrobial therapies. We also discuss the emergence of theranostic CLs that couple real-time on-eye sensing with on-demand intervention, positioning them as prototypes of closed-loop ocular healthcare systems. Emphasis is placed on material design, functional integration, and clinical translation challenges, showing how nanotechnology is redefining CLs as next-generation, patient-tailored biomedical devices. The translational gap between proof-of-concept demonstrations and clinical practice is also evaluated, identifying key unresolved challenges in sensor validation, long-term biocompatibility, power management, and regulatory approval, and proposing a priority research agenda for the field.