A flexible contact lens that senses eye pressure and releases medication on demand could help treat glaucoma, the world’s second leading cause of blindness.
The compact wireless device, which was developed by a team of Chinese researchers and tested on pig and rabbit eyes so far, appears to detect and reduce increased eye pressure, one of the usual causes glaucoma.
Glaucoma is an umbrella term for a group of eye diseases where damage to the optic nerve, which relays visual information to the brain, causes irreversible vision loss and blindness in millions of people worldwide.
Where this new research is gaining momentum is in the development of a device that can detect changes in eye pressure and deliver therapeutic drugs as needed.
Recent efforts to develop smart contact lenses as wearable devices for the treatment of eye conditions have focused on either sensing pressure changes in the eye or delivering a drug – but not the two – and treatment for glaucoma usually involves eye drops, laser therapy, or surgery to reduce eye pressure.
While that sounds exciting, keep in mind that as scientists continue to experiment with all sorts of clever devices to treat eye disease, early detection of glaucoma and prompt treatment remain vital.
“Once detected, therapy for glaucoma can halt or slow its deterioration in the majority of cases,” Jaimie Steinmetz, a researcher at the Washington-based Institute for Health Metrics and Evaluation, and collaborators wrote in 2020. when analyzing the global eye load. diseases, including glaucoma.
But glaucoma is usually hard to catch because peripheral vision is the first to go, and the devices used to diagnose the disease only provide instantaneous measurements of intraocular pressure, which fluctuates with activity and sleep-wake cycles.
“Hence the importance of improving surveillance systems, highlighting the risk among family members of cases and the effectiveness of care once treatment is initiated,” Steinmetz and co-authors emphasize.
That said, contact lenses that fit well to the eye are very attractive for providing therapies for eye conditions. But the incorporation of electrical circuits and sensors into small, flexible, curved, and ultra-thin contact lenses presents a serious engineering challenge.
For something like this to work, it needs to be sensitive enough to detect changes in pressure and release precise amounts of medication on demand, all without blocking vision or irritating the eye.
“It is very difficult to install a complex theranostic system consisting of multiple modules on a contact lens,” write electrical engineer Cheng Yang of Sun Yat-Sen University and his colleagues in their paper.
But it looks like Yang and his colleagues have made some progress – at least in making a prototype lens that incorporates multiple sensors to avoid possible 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 dual-layer lens is coated with an anti-glaucoma drug, brimonidine, and sandwiches an ultra-thin air film in between. This film of air clings to a cantilevered electrical circuit that detects changes in intraocular pressure as the air pocket is compressed by pressure from outside the eye.
If and when eye pressure reaches high-risk levels, the wireless system triggers the release of 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 dual-layer lens design allowed for a compact structure to accommodate multiple electronic modules positioned in the contact lens edge region,” meaning it shouldn’t block wearers’ view, write Yang and his colleagues.
So far, however, the device has only been tested on live pig eyeballs and rabbits. Further research is therefore needed before the lens can move into clinical testing in humans.
But for now, the researchers have reported that their device can detect changes in intraocular pressure, deliver anti-glaucoma drugs through iontophoresis, and “rapidly reduce” eye pressure, as expected.
In these experiments, the rabbit’s eye pressure also remained low and did not rebound as it did when eye drops of brimonidine were given as a control treatment, so this seems somewhat promising.
“This smart system provides promising methodologies that could be extended to other ophthalmic diseases,” Yang and colleagues write.
Additionally, the researchers say their manufacturing methods are compatible with the large-scale, cost-effective manufacturing processes currently used to make printed circuit boards, so as unsightly as this device may seem, it could be made relatively easily.
But of course, we’ll have to keep a close eye on what any future research eventually shows.
The research has been published in Communication Nature.