Emerging Smart Contact Lens Technology for Wearable Biosensors and Drug Delivery: Biomarkers in Tears

There is a growing need for personalised medicine to manage and prevent diseases, as well as to monitor patient health continuously, even outside the hospital setting. Biosensor devices hold a huge potential in addressing this need and can aid in decentralising healthcare by offering faster disease diagnosis and prognosis. Integrating biosensors with wearables such as contact lenses has widened their scope of application and addresses some key challenges associated with other techniques, such as invasive monitoring and the need for bulky equipment. Indeed, traditional approaches tend to be invasive, such as those used for diabetes management that require regular finger pricks to obtain a blood sample to monitor glucose. In contrast, smart contact lenses use tears, which are naturally and regularly replenished. Tears are rich in biomarkers such as proteins and electrolytes, and variations in their concentration can be monitored non-invasively to offer valuable information related to the onset or progression of disease. In addition, intraocular pressure monitoring for glaucoma has been achieved using contact lenses utilising nanomaterials and microfluidics technology. With these promising successes, current researchers seek to address neurodegenerative diseases and cancer diagnosis and prognosis using contact lenses. Contact lenses can also be used as ocular drug delivery systems as they possess 10 times more drug bioavailability advantage than topical administration. By combining contact lenses with a sensing platform, a power source, an antenna, a data transmitter, and a display, smart contact lenses have become more than vision collection devices. Although considerable challenges remain to be tackled because we are still at the initial stages of this technological advancement, the number of diseases and drugs that could potentially be sensed and delivered, respectively, seems vast.