Flexible contact lenses that sense eye pressure and release medication on demand could help treat glaucoma, the second largest global cause of blindness worldwide.
The compact wireless device, developed by a team of Chinese researchers and tested in the eyes of pigs and rabbits so far, appears to detect and reduce high intraocular pressure, one of the usual causes of glaucoma.
Glaucoma is an umbrella term for a group of eye diseases in which damage to the optic nerve, which transmits visual information to the brain, causes irreversible vision loss and blindness in millions of people around the world.
This new research highlights the development of a device capable of detecting changes in intraocular pressure and delivering therapeutic drugs as needed.
Recent efforts to develop smart contact lenses as wearable devices to treat eye conditions have focused on either sensing pressure changes in the eye or delivering medication—but not both—and glaucoma treatment usually includes eye drops, laser therapy, or surgery to reduce intraocular pressure.
While it sounds exciting, keep in mind that as scientists continue to experiment with all kinds of nifty devices to treat eye diseases, early detection of glaucoma and timely treatment remain vital.
Jamie Steinmetz, research scientist at the Washington-based Institute for Health Metrics and Evaluation, and collaborators wrote in 2020 when analyzing the global burden of eye diseases, including glaucoma.
But glaucoma is usually hard to detect because peripheral vision is the first to go, and the devices used to diagnose the condition only provide rapid measurements of intraocular pressure, which fluctuates with the activity, sleep and wake cycles.
“Hence the importance of improving monitoring systems, highlighting risk among case family members, and effectiveness of care once treatment has begun,” Steinmetz and co-authors emphasize.
However, contact lenses that are in contact with the eye have great appeal to offer treatments for eye diseases. But incorporating electrical circuits and sensors into tiny, flexible, curved, ultra-thin contact lenses A serious engineering challenge.
For something like this to work, it would have to be sensitive enough to detect pressure changes and release minute amounts of the drug on demand — all without obstructing vision and irritating the eye.
“It is extremely difficult to install a complex multi-module therapeutic regimen on a contact lens,” electrical engineer Cheng Yang of Sun Yat-sen University and colleagues wrote in their paper.
But Yang and his colleagues seem to have made progress — at least in fabricating a prototype lens that has multiple sensors built right into it to avoid potential eye irritation and a unique laser-cut snowflake design.
It is designed to treat acute angle-closure glaucoma, a less common form of glaucoma that can occur with a sudden or gradual buildup of fluid pressure inside the eye.
According to the researchers, the two-layer lens is covered with an anti-glaucoma drug, brimonidine, And a very thin air film sandwiches in between. This air film is attached to a cantilevered circuit that senses changes in intraocular pressure when the air pocket is compressed by external pressure from the eye.
If intraocular pressure reaches dangerously high levels, the wireless system releases brimonidine, Which flows from the underside of the lens through the cornea into the eye, driven by an electric current in a process known as iontophoresis.
“The double-layer lens design enabled the compact structure to accommodate the electronic multi-modulus placed in the contact lens rim region,” Yang and colleagues wrote, meaning that it should not obscure the wearer’s vision.
So far, the device has only been tested on the eyeballs of live pigs and rabbits, so more research is needed before the lens moves toward clinical trials in humans.
But for now, the researchers report that their devices can detect changes in pressure inside the eye, deliver anti-glaucoma drugs via iontophoresis and “rapidly lower intraocular pressure,” as designed.
In these experiments, the rabbit’s eye pressure also remained low and did not rebound as it did with eye drops Brimonidine was given as a control treatment, so it appears somewhat promising.
“This intelligent system provides promising methodologies that can be extended to other eye diseases,” Yang and colleagues write.
What’s more, the researchers say their manufacturing methods are compatible with the large-scale and cost-effective manufacturing processes currently used to make computer circuit boards, and as ugly as this device may sound, it can be made relatively easily.
But of course, we’ll have to keep a close eye on what any future research eventually shows.
The search was published in Nature Communications.