‘Smart’ contact lenses could help treat underlying cause of blindness, scientists say

(ORDO NEWS) — A flexible contact lens that senses eye pressure and releases medication on demand could help treat glaucoma, the second leading cause of blindness worldwide.

A compact wireless device developed by a group of Chinese researchers and tested in the eyes of pigs and rabbits appears to be able to detect and reduce elevated eye pressure, a common cause of glaucoma.

Glaucoma is a general term for a group of eye diseases in which damage to the optic nerve that carries visual information to the brain causes permanent vision loss and blindness in millions of people around the world.

The new study takes a step forward in developing a device capable of detecting changes in eye pressure and delivering therapeutic drugs as needed.

Recent attempts to develop smart contact lenses as wearable devices for the treatment of eye diseases have focused on either detecting pressure changes in the eye or delivering drugs, but not both, and glaucoma treatment usually involves eye drops, laser therapy, or surgery to reduction in eye pressure.

While this sounds exciting, keep in mind that while scientists continue to experiment with all sorts of amazing devices to treat eye conditions, early detection and treatment of glaucoma remains vital.

“Once glaucoma is detected, therapy can stop or slow its deterioration in most cases,” wrote Jamie Steinmetz, a research fellow at the Washington Institute for Health Metrics and Evaluation, and colleagues in a 2020 analysis of the global burden of eye disease, including glaucoma.

But glaucoma is usually difficult to detect because peripheral vision is the first to be affected, and the devices used to diagnose the condition only provide instantaneous measurements of intraocular pressure, which fluctuates with activity and sleep-wake cycles.

“Hence, the importance of improving surveillance systems, the allocation of risk among family members of patients and the effectiveness of treatment after the start of treatment follows,” emphasize Steinmetz et al.

Thus, contact lenses that fit snugly around the eye are highly attractive for delivering therapy to ophthalmic diseases. But embedding electrical circuits and sensors into small, flexible, curved, and ultra-thin contact lenses is a major engineering challenge.

For something like this to work, it needs to be sensitive enough to detect changes in pressure and release the exact amount of medication on demand—all without blocking vision or irritating the eyes.

“Installing a complex theranostic system consisting of several modules on a contact lens is very difficult,” electrical engineer Cheng Yang of Sun Yat-sen University and his colleagues write in their paper.

But it looks like Yang and colleagues are making progress – at least on a prototype lens that has multiple sensors embedded in it to avoid possible eye irritation, and a unique laser-cut snowflake design.

It is designed to treat acute angle glaucoma, a less common form of glaucoma that can occur when there is a sudden or gradual increase in fluid pressure inside the eye.

The two-layer lens is coated with the anti-glaucoma drug brimonidine, with an ultra-thin airy film in between, the researchers said. This air film is connected to a cantilever electrical circuit that senses changes in intraocular pressure when the air pocket is compressed by external pressure from the eye.

If and when intraocular pressure reaches a high-risk level, the wireless system triggers the release of brimonidine, which flows from the underside of the lens through the cornea into the eye, propelled by an electrical current in a process known as iontophoresis.

“The dual-layer design of the lens allows for a compact structure to accommodate multiple electronic modules located in the rim area of ​​the contact lens,” meaning it should not obscure the user’s view, Yang and colleagues write.

So far, however, the device has only been tested on porcine eyeballs and live rabbits, so more research is needed before the lens can be tested in human clinical trials.

But for now, the researchers report that their device can detect changes in intraocular pressure, deliver anti-glaucoma drugs via iontophoresis, and “quickly lower” eye pressure as intended.

In these experiments, the eye pressure of the rabbits also remained low and did not recover as it did when brimonidine eye drops were delivered as a control treatment, so this looks somewhat promising.

“This smart system provides a promising technique that can be extended to other ophthalmic diseases,” write Yang and colleagues.

What’s more, the researchers claim that their fabrication methods are compatible with the large-scale and cost-effective manufacturing processes currently used to make computer printed circuit boards, so as ugly as this device sounds, it can be made relatively easily.

But, of course, we have to keep a close eye on what further research will show.


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