When you wear contact lenses, you expect to experience better vision of the outside world – focusing on faces, screens and more. But what if you could also monitor the inner world – not the mind, but your body’s vital signs? Until now, contact lenses with built-in sensors for measuring intraocular pressure (IOP) are too stiff, bulky, and can even partially block vision. Worse yet, some don’t even have the sensitivity to do the job. So far.
A revolutionary design has just been successfully tested in volunteers: a soft, transparent contact lens capable of taking quantitative IOP measurements in real time, using a smartphone, according to a new study. published in the journal Biomedical genius. More importantly, the new device successfully performed all wireless functions without inducing inflammation for all 10 human participants, which could have serious benefits for people with glaucoma.
Smart contact lens detects key symptom of glaucoma
The new contact lens uses wireless antenna, strain sensor, capacitors, uses expandable metal that interconnects, resistors and integrated circuit to enable wireless communication. When the device was tested on rabbits, it generated measurements comparable to a commercial tonometer – and it was found to be perfectly safe when tested on 10 humans, with no inflammation observed. The device can measure basic vital signs including heart rate, body temperature, electrical activity of the heart, in addition to glucose, lactate and alcohol levels in body fluids such as sweat, blood tears and saliva. Measuring all of these continuously is crucial for diagnosing a wide range of diseases.
Medically speaking, the eyes are a good choice for measuring these vital signs, as they can expose electrical sensors to continuous tear fluid samples – where a portable device could record and report signals from the eye. It could diagnose multiple diseases from eye conditions, but the recent study focused on the technology’s ability to detect glaucoma.
Glaucoma is an optic neuropathy that often leads to irreversible vision loss, and IOP is the only risk factor scientists are sure we can control – meaning the only way we have to treat glaucoma is reduce IOP. Typically, IOP measurement is done with various forms of tonometry, but they lack the clinical specificity required for fully effective monitoring. To overcome this, the new smart contact lens design has been touted as a promising candidate for wearable sensing technology – capable of maintaining physical contact with the cornea and detecting corneal limbus expansion – a key symptom of a jump from the IOP. .
The new design of contact lenses still faces many challenges
In other words, the new smart contact lens can monitor a key signifier of glaucoma with a significant degree of specificity with minimally invasive technology, comparable to regular contact lenses. But there are still challenges for the new design before it can be implemented on a large scale. For example, conventional sensors using metals or semiconductors lack the sensitivity to detect the subtle lens distortions that IOP fluctuations create – specifically, lens distortions of just 0.03%. in tensile stress per mm Hg.
In addition, quite complex circuitry is required to amplify the signal from the modest biosensor, so that the lens data is not drowned in the background electromagnetic noise. Rigid electronic materials in sensors, metal antennas, integrated circuits, and interconnect structures can block human vision – and potentially damage the cornea and eyelid. No one wants to put a contact lens in their eye if there is a risk of it cutting the inside of your eyelid. Finally, measuring smart contact lens biosignals requires cumbersome equipment – which would limit the range of motion of a wearer who might prefer to go outdoors, or anywhere outside of a clinical environment.
There’s a lot to be done before these smart contact lenses become a reliable diagnostic tool for clinical environments – not to mention a popular, market-driven alternative to regular doctor and optometrist visits. But this recent study is still a laudable breakthrough – one that could signal a new, simple way to monitor, diagnose, and aid in the treatment of some of the more unwieldy diseases, including glaucoma.