CONTACT LENSES have the potential to serve as versatile tools capable of delivering ocular drugs directly to the eye, monitoring both ocular and systemic health conditions in real time, and seamlessly projecting digital information into the wearer’s field of vision, augmenting their reality and experience. This transformation and the developments needed for this to occur represent a remarkable leap forward in the capabilities of CLs, turning them into multifunctional devices. 

DRUG-ELUTING AND BIOACTIVE CLs

Development of drug-eluting CLs is aimed at maintaining optimal drug concentrations for extended periods by increasing drug residence times on the ocular surface. This allows for improved treatment efficacy for various ocular conditions while providing vision correction.

There are different strategies to control release of drugs from CLs, such as layer-by-layer coatings, imprinting technologies, and the use of nanodiamonds or gold nanoparticles, currently being used (Abdi and Mofidfar, 2023; Guo Q et al, 2021; DiPasquale and Byrne, 2021). On-demand drug release using smart polymers and hydrogels that can respond to environmental stimuli is also being explored. For instance, azobenzene- and spiropyran-based materials are being investigated for their ability to dynamically regulate light-triggered drug release through photoisomerization (Abdelmohsen et al, 2023).

DIAGNOSTIC CLs

Embedding biosensors within a lens material offers noninvasive, efficient monitoring of ocular and systemic health, as the lenses are bathed in tears. Key areas in the development of diagnostic CLs include hydrogel-based sensors capable of detecting changes in tear fluid analytes such as glucose or lactate, smart polymers to monitor tear composition and pH, and integration of graphene-based electrodes for glucose monitoring (Seo et al, 2023; Bamgboje et al, 2021).

Soft CLs with embedded electronics allow for comfortable continuous monitoring of intraocular pressure (IOP) in glaucoma without compromising lens functionality. Of note, there are colorimetric sensors that can provide visual cues for immediate diagnostic feedback, and the potential of such devices is only just starting to be realized (Zhang et al, 2022; Liu et al, 2024).

CLs AND AUGMENTED REALITY

The integration of augmented reality (AR) into a CL involves sophisticated materials and microelectronics to create “smart contact lenses” capable of projecting digital information into the wearer’s field of vision. The key areas of material exploration in AR include incorporation of flexible and transparent electronic circuits; using graphene or other transparent conductive materials to create microelectronic components; exploring silicone-based hydrogels for their comfort and oxygen permeability; developing miniaturized waveguide technologies to seamlessly direct light from micro-LEDs or other sources toward the user’s pupil; utilizing nanofabrication techniques to create tiny sensors and light sources within the lens matrix; and employing bioinspired materials to achieve better transparency and refractive properties suitable for integrating AR display technologies onto the lens surface (Guo S et al, 2021; Robert et al, 2023; Konget al, 2024).

These advancements are pivotal in realizing advanced AR-enabled CLs. While prototypes of such devices have been presented in the literature, they are not without challenges (Liu et al, 2024). Miniaturization of components, power management, and user interface design are critical engineering challenges. Privacy concerns and regulatory approvals need to be factored in to ensure the safety, accuracy, stability, and manufacturability of any such device (Efron, 2023).

THE FUTURE

The evolution of CLs into multifunctional devices marks an advancement driven by material science innovations. The trajectory includes capabilities such as drug delivery, health monitoring, and AR integration, potentially revolutionizing ocular care and the user experience.

Overcoming challenges like miniaturization and regulatory approval will be crucial to realizing this potential. The outlook suggests a transformative future where CLs become indispensable tools for both vision correction and broader health and technological applications.

REFERENCES

1. Abdi B, Mofidfar M, Hassanpour F, et al. Therapeutic contact lenses for the treatment of corneal and ocular surface diseases: Advances in extended and targeted drug delivery. Intern J Pharm. 2023 May 10;638:122740.

2. Guo Q, Jia L, Qinggeletu, Zhang R, Yang X. In vitro and in vivo evaluation of ketotifen-gold nanoparticles laden contact lens for controlled drug delivery to manage conjunctivitis. J Drug Del Sci Technol. 2021 Aug;64:102538.

3. DiPasquale SA, Uricoli B, DiCerbo MC, Brown TL, Byrne ME. Controlled Release of Multiple Therapeutics From Silicone Hydrogel Contact Lenses for Post-Cataract/Post-Refractive Surgery and Uveitis Treatment. Transl Vis Sci Technol. 2021 Dec;10:5.

4. Abdelmohsen HAM, Copeland NA, Hardy JG. Light-responsive biomaterials for ocular drug delivery. Drug Deliv Transl Res. 2023 Aug;13:2159-2182.

5. Seo H, Chung WG, Kwon YW, et al. Smart Contact Lenses as Wearable Ophthalmic Devices for Disease Monitoring and Health Management. Chem Rev. 2023 Oct 11;123:11488-11558.

6. Bamgboje D, Christoulakis I, Smanis I, et al. Continuous Non-Invasive Glucose Monitoring via Contact Lenses: Current Approaches and Future Perspectives. Biosensors. 2021 Jun 9;11:189.

7. Zhang J, Kim K, Kim HJ, et al. Smart soft contact lenses for continuous 24-hour monitoring of intraocular pressure in glaucoma care. Nat Commun. 2022 Sep 20;13:5518.

8. Liu X, Ye Y, Ge Y, et al. Smart Contact Lenses for Healthcare Monitoring and Therapy. ACS Nano. 2024 Mar 5;18:6817-6844.

9. Guo S, Wu K, Li C, et al. Integrated contact lens sensor system based on multifunctional ultrathin MoS2 transistors. Matter. 2021 Mar 3;4:969-985.

10. Robert FM, Abiven B, Sinou M, et al. Contact lens embedded holographic pointer. Sci Rep. 2023 Apr 27;13:6919.

11. Kong L, Li W, Zhang T, et al. Wireless Technologies in Flexible and Wearable Sensing: From Materials Design, System Integration to Applications. Adv Mater. 2024 Apr 23:e2400333.

12. Efron N. Augmented reality contact lenses – so near yet so far, Clin Exp Optom. 2023 May;106:349-350.