Graphene contact lenses offer smart vision, sensing, and drug delivery on the eye

Graphene, a single atom-thick carbon material, is poised to revolutionize contact lenses by transforming them into intelligent devices capable of disease sensing, drug delivery, and infection prevention. Researchers Lina M. Shaker, Ahmed Alamiery, and Naseer Ali Hussien from Al-Ayen Iraqi University have reviewed the advancements in graphene-integrated contact lenses, highlighting their potential in Discover Chemistry. The review discusses applications such as transparent electrodes for retinal diagnostics and wireless sensors for glaucoma, while acknowledging the challenges in achieving clinically approved products due to unresolved toxicological concerns.

Graphene's appeal lies in its exceptional properties: it transmits 97.7% of visible light, conducts electricity with high carrier mobility, and exhibits significant mechanical strength. These attributes make it ideal for contact lenses, allowing for transparency, conductivity, and durability. Unlike traditional materials like indium tin oxide, graphene is flexible and can integrate seamlessly with the soft hydrogel substrates of modern lenses, supporting the embedding of electronics directly into the ocular environment.

The biointerface chemistry of graphene is crucial for its application in contact lenses. Its smooth surface minimizes protein adsorption and bacterial adhesion, reducing biofouling and infection risks. Graphene's antimicrobial properties, including direct contact killing and oxidative stress induction, offer protection against microbial colonization. Additionally, its resistance to chemical degradation and ability to be functionalized for optimal wettability enhance its suitability for extended wear and drug delivery.

The review categorizes the technological maturity of graphene-integrated lenses, from conceptual designs to laboratory prototypes. Notably, graphene photodetectors on flexible substrates have shown potential for night-vision capabilities, although clinical validation is pending. More established are prototypes for electromagnetic shielding and moisture retention, which address concerns about wireless radiation exposure and dry eye syndrome.

Two notable prototypes include transparent electroretinography systems and wireless intraocular pressure sensors for glaucoma management. The graphene-on-lens electrode system enhances retinal recordings, while the pressure sensor detects corneal curvature changes, transmitting data wirelessly. These prototypes represent significant advancements in the field, although they remain in preclinical stages.

Graphene's potential extends to biosensing and drug delivery. Graphene field-effect transistors functionalized with antibodies have detected tear cortisol, and glucose sensing is being explored for non-invasive diabetes monitoring. Drug delivery applications involve graphene oxide lenses for controlled release of various therapeutics, potentially improving efficacy and reducing side effects.

Manufacturing challenges include the high cost of chemical vapor deposition for monolayer graphene and the need for precise transfer techniques. Solution-phase processing offers a cheaper alternative but compromises quality. Safety concerns, such as oxygen permeability and heat dissipation, require innovative solutions like micro-heat-spreader grids and pore drilling. Toxicological studies are ongoing, with no graphene-enhanced lenses yet receiving regulatory approval.

The review anticipates future developments from 2025 to 2030, including multimodal biosensing with heterostructures, energy-harvesting modules, and AI integration. However, the success of graphene-based contact lenses will depend on overcoming technical and regulatory hurdles, proving their long-term safety and efficacy for ocular use.