A contact lens that can release a drug if it detects high pressure within the eye has been created by scientists who say it could help treat glaucoma. Glaucoma is an eye disease that involves damage to the optic nerve, and can lead to blindness if not treated. According to the charity Glaucoma UK, the most common form of the disease, known as primary open angle glaucoma, is thought to affect almost 10% of people older than 75. This form is generally caused by increased pressure within the eye, usually as a result of a buildup of fluid. Researchers in China revealed they have developed a contact lens that can sense an increase in pressure within the eye and release an anti-glaucoma drug should the pressure exceed a certain level. Writing in the journal Nature Communications, the team describe how they created the device using an upper and lower lens, with a snowflake-shaped pressure sensor and wireless power transfer device sandwiched between them around the rim of the lenses. The arrangement appears to give the effect of the wearer having golden irises. However, the team say the design allows the necessary components to be included in the device without blocking the wearer’s view or irritating the eye. When the pressure inside the eye increases, the gap between the upper and lower lenses decreases. This is detected by the pressure sensor by means of a cantilever. The sensor then sends a signal to the wireless system which subsequently triggers the release of an anti-glaucoma drug, from a hydrogel attached to an electrode, and enables it to cross the cornea of the eye. The drug, brimonidine, acts to reduce the pressure within the eye. The study reveals that the contact lenses have so far been tested on pigs’ eyes and on the eyes of living rabbits – albeit with smaller-sized lenses – although trials have yet to be carried out in humans. The researchers note the lenses are not only soft and minimally invasive but are also battery-free, adding that the approach could be expanded to help tackle other eye diseases. Prof Zubair Ahmed from the Institute of Inflammation and Ageing at the University of Birmingham, who was not involved in the work, said the research was potentially very exciting, adding that a rise in pressure within the eye was a significant problem for most people with glaucoma. “Here, the researchers have developed a minimally invasive contact lens that can detect these changes in pressure within the eye to provide real-time monitoring, but the contact lens can also respond by allowing on-demand drug delivery directly to the eye,” he said. There was potential to develop the technology further, he added. “We can now imagine that a glaucoma sufferer wearing these contact lenses will not only receive real-time information about the pressures within the eye, since the contact lens has built-in wireless capacity and can easily communicate with an app on your smartphone, but also receive, for example, pressure-relieving drugs when needed. “The materials required to create such contact lenses are inexpensive and soon could be mass-produced,” he added.