A soft, stretchable contact lens can now track eye pressure and movement, even when the eyelids are shut. It sends high-resolution, real-time data to a phone without blurring vision or causing discomfort.
The twin measurements – intraocular pressure and subtle shifts in gaze – are vital for catching problems like glaucoma before damage occurs.
Created by engineers at the University of Electronic Science and Technology of China and tested in rabbits and people, the lens merges capacitive and magnetic sensors inside a five-layer film.
Serpentine copper wires register pressure changes as small as one millimeter of mercury (mmHg). A wafer-thin, neodymium-doped band answers the pressure coils with a magnetic pulse that reveals eye movement.
Both signals reach an exterior receiver the size of ordinary specs and then hop wirelessly to any Bluetooth-ready device.
Why eye pressure matters overnight
Glaucoma steals sight by slowly eroding the optic nerve. The damage often begins with pressure spikes that emerge after lights-out, when standard tonometers cannot operate.
Excess pressure is not the whole story: rapid eye movement sweeps and irregular gaze fixes also correlate with disease risk.
Design and working principle of the BCL. (i) Schematic diagram of BCL-based closed-eye capacitive intraocular pressure (CIOP) and magnetic eye movement (MEM) monitoring. (ii) Key components of the BCL. (iii) Optical images depicting the BCL in initial, stretched, and twisted states, and the experimental setup worn on an eyeball. (iv) Wireless transmission of CIOP and MEM signals to portable devices. b Three-dimensional image illustrating the thickness of various BCL components. c Height profile along the pink line in (b), displaying the height of multilayer components. d Finite element analysis (FEA) and experimental results of the BCL under a series of pressing heights, with corresponding experimental height results. e Biocompatibility Characterization of the BCL. Click image to enlarge. Credit: Microsystems & NanoengineeringUntil now, no wearable system captured both cues while the eyes stayed closed. The new lens does, offering a missing night-time readout that could sharpen diagnosis and tailor drug timing.
The device builds its sensing core on a transparent elastomer shaped like a standard hydrogel lens. Five nested sheets keep the profile thinner than the edge of a credit card.
The outer face hosts the copper coil, tuned to deform with corneal bulges caused by pressure shifts. A middle layer embeds stretchable conductors leading to a micro-scale circuit.
Beneath that lies the magnetic film, followed by a comfort cushion that rests on the eye. A final, oxygen-permeable coating seals the stack and preserves clarity.
Tests on rabbit eyes showed the lens surviving thousands of blinks and pressure cycles without delamination. Human volunteers wore it for two hours under continuous monitoring and reported no burning, redness, or blur.
Continuous data and instant feedback
A glasses-mounted Tesla meter reads the magnetic changes from the lens with more than 97 percent accuracy, translating those variations into horizontal, vertical, and rotational eye motion.
At the same time, the coil’s resonance shift reveals pressure. A companion phone app plots both streams in real time and stores them for later review.
Clinicians can compare overnight peaks to daily baseline values, flagging patterns that merit therapy adjustments.
“This technology bridges a long-standing gap in ophthalmic care,” noted Dr. Guang Yao, co-lead author of the study.
“The ability to monitor both intraocular pressure and eye movement continuously – even when the eyes are closed – offers a more complete picture of eye health.”
“It enables early intervention and more accurate tracking of disease progression, particularly for glaucoma patients. And because it’s wireless and wearable, it can be used comfortably at home, not just in clinics.”
Detecting early warning signs
Eye movement data hint at disorders far outside ophthalmology. Irregular REM cycles mark sleep apnea and some mood conditions. Tremor-like micro-saccades can foreshadow Parkinson’s disease.
By delivering a clean, night-long trace, the smart contact lens could help neurologists map early warning signs without bulky lab gear. It may also aid attention studies, tracking gaze stability during prolonged tasks.
The research team foresees layering a drug-reservoir ring onto the current design. In such a closed-loop lens, a pressure spike could trigger a micro-valve to release medication directly onto the cornea.
Add a thin glucose sensor, and the system might warn diabetics of rising blood sugar while dosing their eyes as needed.
Modular fabrication means each medical discipline could swap in its own sensing film without reinventing the core electronics.
Biocompatibility assays showed no toxic leachates or immune response over a week-long animal trial. Vision tests confirmed that the lens preserved contrast and color perception.
The next hurdles are mass production and regulatory review, both eased by the fact that the base materials already appear in commercial lenses and wearable electronics. As costs drop, the device could reach pharmacies as a prescription add-on rather than a hospital-only tool.
Until now, monitoring eye health meant using slit-lamp exams or wearing daytime-only sensors – not a lens that worked around the clock.
The stretchable bimodal contact lens rewrites that rulebook, letting vision care continue after the lights go out.
By catching nocturnal pressure surges and mapping every flicker of motion, it gives doctors a fuller, round-the-clock picture of the organ they struggle hardest to observe.
For millions at risk of silent vision loss, a routine morning sync with their phone could soon replace guesswork with precise, night-laden data – and turn sleep into an ally in safeguarding sight.
The study is published in the journal Nature.
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English (US) ·