Glaucoma could be treated with contact lenses that release drugs.

 Scientists have developed a contact lens that can administer a medicine if it senses high pressure inside the eye, which they believe could effectively treat glaucoma.

Glaucoma is an eye condition that causes damage to the optic nerve and, if left untreated, can result in blindness.

The most prevalent subtype of the disease, called primary open angle glaucoma, is believed to affect around 10% of those over the age of 75, as per the charity Glaucoma UK. Intense pressure within the eye, usually a consequence of accumulation of fluid, causes this type of glaucoma.

Researchers in China have designed a contact lens that can detect an increase in intraocular pressure and deliver an anti-glaucoma medicine if the pressure rises above a set threshold.

The team describes how they developed the gadget using an upper and lower lens, with a snowflake-shaped sensor and wireless power transfer device positioned between them around the rim of the lenses, in the journal Nature Communications. The arrangement gives the impression that the wearer has golden irises. The design, however, allows for the necessary elements to be integrated in the device without obscuring the wearer's view or irritating the eye, according to the scientists.

How it works

The distance between both the upper and lower lenses narrows as the pressure inside the eye rises. A cantilever is used by the pressure sensor to detect this. The sensor then transmits a signal to the wireless system, which causes an anti-glaucoma medicine to be released from a hydrogel connected to an electrode and cross the cornea of the eye. Brimonidine works by lowering the pressure inside the eye.

The contact lenses have been tested on the eyes of pigs' and living rabbits (albeit with smaller lenses), according to the report, but human trials have yet to be conducted.

The lenses are not just soft and minimally intrusive, but also battery-free, according to the researchers, who believe the technology might be broadened to help with other eye problems.

Prof Zubair Ahmed of the University of Birmingham's Institute of Inflammation and Ageing, who was not involved in the research, said the findings were potentially extremely fascinating, adding that a rise in intraocular pressure was a serious problem for most individuals with glaucoma.

"The researchers have developed a minimally intrusive contact lens that can detect these changes in eye pressure to give real-time monitoring, but the contact lens can also respond by allowing on-demand medicine delivery directly to the eye," he explained.

He said that the technology might be further developed. "We can now imagine that a glaucoma patient wearing these contact lenses will not only receive real-time information about the pressures within the eye, because the contact lens has built-in wireless capability and can easily communicate with an app on your smartphone, but will also receive pressure-relieving drugs when needed."

"The materials required to make such contact lenses are low-cost and might be mass-produced in the near future," he noted.