Researchers have developed contact lenses with embedded sensors that measure the pressure inside the eye and send the information to an ophthalmologist for evaluation. It’s hoped that the lens will lead to the early diagnosis of glaucoma, which can lead to irreversible vision loss if left untreated.
Glaucoma occurs when the optic nerve, connecting the eye to the brain, is damaged by increased intraocular pressure (IOP), usually caused by a build-up of fluid in the front part of the eye. If it’s not treated, glaucoma can lead to irreversible loss of vision. But there’s a reason why it is sometimes called the ‘silent thief of sight’; it develops slowly over time, causing irreparable harm before there’s any vision loss. By the time glaucoma is picked up during routine eye tests, the damage may already be done.
But things may soon change thanks to a collaboration between researchers from Northumbria University in the UK and Boğaziçi University, Turkey. They’ve developed contact lenses that detect fluctuations in IOP, using the information they gather to diagnose glaucoma and have now trialed them in people.
An electrically passive sensor is embedded in a disposable soft contact lens made of polydimethylsiloxane (PDMS). Data is collected wirelessly by a wearable electronic readout system which collects, stores, and processes the data. The processed data is then given to an ophthalmologist for evaluation.
One of the benefits of using the novel contact lens, which the researchers have called GlakoLens, is that, compared to conventional eye exams, IOP measurements can be taken more easily over a longer period of time, which can result in a more accurate diagnosis.
“Intraocular pressure, or IOP, can vary greatly over a 24-hour period, so it is important to monitor the patient either at intervals or ideally continuously for a whole day to get the best insight into the health of their eyes,” said Hamdi Torun, the study’s corresponding. “Traditional methods for measuring IOP involve initially going to a clinic for a single measurement in a day, the result of which can be misleading due to the natural variation of IOP. If a variation is detected, further investigation is then needed, which requires hospitalization for a whole day, during which repeated measurements are taken using a technique called Goldmann applanation tonometry [GAT], which involves numbing the eye with drops and then using a small cone to touch the cornea to measure pressure.”
Overall, it’s a much more invasive experience than the researchers offer with GlakoLens.
“The benefit of the contact lenses we have developed is that once placed in the eye, the patient can then go about their day as normal while their IOP measurements are recorded and sent to a doctor for analysis once the 24-hour period of testing is complete,” Torun said.
The researchers tested their contact lenses on six healthy volunteers, who were asked to drink one-and-a-half liters (50 fl oz) of water and lay flat to intentionally increase their IOP. All participants wore the lens on their left eye. In addition to the data collected by the lens worn in the left eye, the researchers measured IOP in the lens-less right eye for comparison. The findings demonstrated that the contact lens sensors responded to the effects of water loading, with measurements from the right eye in agreement with those taken by the device.
Further experiments using larger cohorts of healthy individuals will investigate the sensor’s accuracy and reliability. The researchers plan to optimize the comfortability and non-invasiveness of their contact lenses in future iterations.
These are not the first glaucoma-detecting contact lenses developed. In February 2023, researchers from South Korea’s Pohang University of Science and Technology (POSTECH) tested a contact lens that monitored for glaucoma and released IOP-reducing medication into the eye as required. They had only tested their lenses on rabbits. Then, in May, a California-based startup trialed miLens, a ring placed in the eye that physically measured IOP on glaucoma patients, finding that the readings provided were just 2 mmHg – millimeters of mercury, a unit of pressure – different from GAT readings.
The researchers say that previous contact lenses have used an electrically active silicon chip, which results in a thicker, less comfortable lens that is less flexible and can restrict vision. They say the GlakoLens’ electrically passive sensor and soft contact lens ensure that wearers are more comfortable.
As well as diagnosing glaucoma, the researchers say their lenses could be used to detect other health conditions by measuring glucose, lactic acid and other molecules present in the eye.
“We believe this technology has huge potential and could not only save the sight of patients in the early stages of glaucoma but also provide early diagnosis of other diseases in future,” said Torun.
The study was published in the journal Contact Lens and Anterior Eye. and the lenses are set to be commercially available through the spin-off company GlakoLens.
Source: Northumbria University
