If you think about it, contact lenses are already a type of wearable medical device. They sit on the surface of the eye, bathed in a tear film full of useful biomarkers and offer a direct route for drug absorption. Because of this unique position, researchers have been experimenting with ways to turn ordinary lenses into tiny health-monitoring platforms.
Thanks to advances in microelectronics, flexible sensors and biocompatible materials, contact lenses can now be embedded with miniature circuits, pressure-detecting films or drug reservoirs, all while remaining comfortable to wear. Some of these technologies, like continuous Intraocular pressure (IOP) monitoring, are close to being used clinically. Others, like glucose-sensing and augmented reality (AR)-based visual enhancement, are still in early testing. But taken together, they signal a future where contact lenses could become everyday tools for disease management.
Glucose-Sensing Contact Lenses for Diabetes
Researchers have long explored measuring blood glucose non-invasively through tears. Although tear fluid contains much less glucose than blood, a lens that can provide accurate readings could reduce finger pricks or offer an alternative way to monitor trends.
Most experimental glucose-sensing lenses use tiny electrochemical sensors embedded within the lens.[1] These sensors react with glucose in the tear film and wirelessly send readings to an external device.[1] Advances in ultra-thin electronics, graphene-based components and optical sensing have made these designs increasingly realistic and practical over the past decade.[1][2]
But here is the catch: tear glucose levels don’t always match blood glucose levels directly. They can change with irritation, crying or environmental factors. Studies also show that each person may have a different time delay (or “lag”) between changes in blood glucose and what appears in their tear film. [3] For clinical accuracy, this delay must be accounted for.
The best-known commercial attempt came from Verily (Google’s life-sciences division), but the project was discontinued because the sensors could not reliably correlate tear and blood glucose in everyday conditions.[4] With improved calibration and smarter analytics, glucose-sensing lenses may still find a role, perhaps as trend monitors rather than replacements for continuous glucose monitors.
Figure 1: Illustration of glucose leakage from blood into the tear film. Figure from Park W, et al. 2024.
Continuous Intraocular Pressure Monitoring in Glaucoma
Measuring IOP only in clinic is like checking a patient’s heart rate once a day – you miss a lot of important variations. Glaucoma patients often have pressure spikes at night or during certain daily activities and these spikes may contribute to disease progression.
Smart contact lenses offer a clever solution. The Sensimed Triggerfish® lens is the most established device in this area.[5] Instead of measuring pressure directly, it detects tiny changes in the shape of the cornea that correlate with IOP fluctuations.[5] The lens sends these readings wirelessly to a recorder worn by the patient.
While the Triggerfish doesn’t give absolute IOP readings in mmHg, it does provide a detailed 24-hour profile of relative pressure changes.[5] This can enable clinicians to identify nocturnal peaks that might explain disease progression or evaluate whether a glaucoma treatment is actually controlling pressure throughout the day.[5]
In addition, theranostic contact lenses, lenses that diagnose, monitor and treat, are an emerging powerful next step. A smart lens currently under development integrates a highly sensitive IOP sensor alongside a flexible drug-delivery system.[6] When IOP spikes are detected, the lens automatically releases anti-glaucoma medication via iontophoresis.[6] Such devices provide personalised and feedback-controlled glaucoma therapy.
Of course, these contact lenses aren’t perfect. They can feel slightly less comfortable than standard lenses, they are costly and interpretation of their output data requires training. But among all the smart lens technologies, continuous IOP monitoring is currently the most clinically mature.
Drug-Eluting Contact Lenses
Patient adherence to long term eye drops is challenging. Many struggle with the technique, forget doses or find frequent applications inconvenient.
Drug-eluting contact lenses offer an elegant alternative. These lenses are designed to release medication slowly while being worn, maintaining much more consistent drug levels on the ocular surface. Researchers have experimented with several delivery methods such as polymer films, nanoparticles and diffusion-controlling additives.[7]
Latanoprost, a common glaucoma medication, has been widely tested in animal models and early human studies. Results so far suggest that these lenses can lower IOP at least as well as daily drops, and possibly more consistently.[7][8]
A major benefit of this approach is improved adherence, patients simply wear the lens rather than remembering multiple daily drops. However, a few challenges remain before these lenses become mainstream. The lens must stay breathable and comfortable, even with medication inside. Storage, sterilisation and manufacturing must also meet strict medical standards. But if these hurdles are overcome, drug-eluting lenses may significantly improve treatment adherence for many debilitating chronic eye diseases.
Augmented-Reality Contact Lenses for Visual Loss
While glucose sensors and drug-releasing lenses are practical innovations, augmented-reality (AR) contact lenses feel almost futuristic.
The idea is simple: project digital images or enhancements directly into the user’s visual field. Imagine magnifying text, highlighting edges, or improving contrast in real time, features that could be extremely helpful for patients with central vision loss from conditions like age-related macular degeneration.
There are several design strategies; however hybrid designs involving both glasses and lenses are anticipated to be first used clinically. Another ambitious approach involves placing the display directly onto the contact lens. Mojo Vision developed a prototype containing a micro-LED display and eye-tracking sensors.[9] However, the company paused development in 2023 due to engineering and funding barriers, particularly the difficulty of powering a display safely on the surface of the eye.[9]
It may take years before fully self-contained AR contact lenses are available, however if successful, AR lenses could become a discreet, highly functional option for visual rehabilitation.
Shared Challenges Across All Smart Lens Technologies
Although each type of smart contact lens has a different goal, they all face similar obstacles. The biggest is ensuring the lens stays safe and comfortable. Adding electronics or drug reservoirs must not reduce oxygen reaching the cornea or increase the risk of infection.
Powering the lenses is another major hurdle, especially for devices that require constant data transmission or display capabilities. Batteries on the lens surface are generally not safe, so researchers are exploring wireless power transfer and ultra-low-power chips.
Data interpretation is also an important issue. For example, glucose-sensing and IOP-monitoring lenses generate signals that need calibration or algorithmic interpretation before they can guide clinical decisions. And, as with any new medical device, regulatory approval requires extensive safety data and real-world testing.
Because many smart lenses rely on wireless transmission to relay data to a smartphone, wearable hub or clinic, they introduce new concerns around data security, ownership and potential misuse. Continuous streams of biometric information such as IOP fluctuations, medication-release history and glucose trends, could be vulnerable to interception or unauthorised access. Beyond hacking risks, there is the broader worry that companies might use health-linked data commercially by profiling users for targeted advertising or sharing information with third parties. Within an NHS framework, this raises important questions about who owns the data, how it is stored and which entities (if any) should have access. Clear governance would be essential to ensure these data are protected from insurers, employers or government bodies whose interests may not align with patient welfare. Ultimately, strong encryption, transparent consent mechanisms and NHS-standard data safeguards would be mandatory before widespread adoption.
For smart lenses with AR capabilities, the ethical considerations extend beyond health data. By overlaying information directly into a user’s visual field, AR systems hold the power to influence perception and decision-making in ways that are far more intimate than conventional screens. Intrusive advertising, or even subtle changes in how objects are highlighted, could manipulate the user without their full awareness. This raises concerns about autonomy, informed consent and the psychological impact of living with digitally mediated vision. Safeguards such as strict regulation of advertising, transparent control over what overlays are allowed and robust user opt-out mechanisms would be essential. Within the NHS, AR lenses would need a clear separation between clinical functionality and any commercial content to ensure that patient care remains the sole priority.
Looking Ahead
Smart contact lenses have great potential to move from experimental concepts towards meaningful clinical tools. Continuous IOP-monitoring lenses are already helping clinicians manage glaucoma more precisely. Drug-eluting lenses could soon make chronic eye treatments easier and more effective. Glucose-sensing lenses may become practical once accuracy improves. AR lenses, while still in early development, could transform low-vision rehabilitation in the long run.
The value of smart contact lenses lies not in replacing existing care but in adding continuous, personalised, data-driven insights that traditional clinic-based measurements simply cannot provide. In my view, the NHS stands to benefit significantly: these lenses could reduce clinic congestion, improve long-term outcomes and support a shift toward home-based monitoring, aligning well with NHS priorities. But these promising technologies will need careful, phased adoption. Cost-effectiveness, reliability, training, data-integration infrastructure and long-term safety evidence will determine how quickly they can be implemented. If ongoing research can overcome these current challenges, smart contact lenses could play a meaningful role in future ophthalmic care in the UK.
References
[1] Elsherif M, Abdelhamid HN, Heo J, Li C, Morsi Y. Wearable smart contact lenses for continual glucose monitoring: a review. Front Med (Lausanne). 2022;9:858784.
[2] Lee S, Jo I, Kang S, Jang B, Moon J, Park JB, et al., Smart Contact Lenses with Graphene Coating for Electromagnetic Interference Shielding and Dehydration Protection. ACS Nano. 2017 Jun
[3] Park W, et al. In-depth correlation analysis between tear glucose and blood glucose: establishing personalized lag-time for contact-lens-based glucose monitoring. Nat Commun. 2024.
[4] Verily Life Sciences. Update on the glucose-sensing smart contact lens program. 2018.
[5] Dunbar GE, Shen BY, Aref AA. The Sensimed Triggerfish contact lens sensor: efficacy, safety, and patient perspectives. Clin Ophthalmol. 2017 May 8;11:875-882.
[6] Kim TY, Mok JW, Hong SH, Jeong SH, Choi H, Shin S et al., Wireless theranostic smart contact lens for monitoring and control of intraocular pressure in glaucoma. Nat Commun. 2022 Nov
[7] Gao D, Yan C, Wang Y, Yang H, Liu M, Wang Y et al., Drug-eluting contact lenses: Progress, challenges, and prospects. Biointerphases. 2024 Jul.
[8] Ciolino JB, Ross AE, Tulsan R, Watts AC, Wang RF, Zurakowski D, et al., Latanoprost-Eluting Contact Lenses in Glaucomatous Monkeys. Ophthalmology. 2016 Oct
[9] Mojo Vision. Corporate update on AR contact lens development pause. 2023.
