What鈥檚 that twinkle in your eye? A contact lens for people with diabetes contains a tiny light that lets them know if their sugar levels get too high.
Diabetes affects the body鈥檚 ability to regulate a type of sugar called glucose. If blood sugar levels aren鈥檛 properly monitored, they can creep up and damage organs.
People with diabetes can monitor their sugar levels by pricking their finger and testing their blood with a glucose meter, but many find this painful and inconvenient.
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狈辞飞,听听at Ulsan National Institute of Science and Technology in South Korea听and his colleagues have developed a contact lens that continuously monitors sugar in tears. Previous studies have shown that the sugar content of tears corresponds closely with blood sugar.
The clear, flexible lens contains a glucose sensor that sends electrical signals to an LED. The light is configured to stay on when sugar levels are normal and switch off if they exceed a particular figure. For the study, this threshold figure was set, but could easily be personalised to the individual wearer.
The wearer can check the LED display when they look in the mirror to see if it is on or off. The team acknowledge that it is counter-intuitive to have the sensor switch off rather than on when a glucose threshold is met, and may look to change this in future experiments.
Specks of glitter
The sensor and light are placed to the side of the pupil where they can鈥檛 disturb vision, and are so small they look like specks of glitter.
To test the contact lens, the team fitted it to the eye of a live rabbit. When they washed tear fluid containing extra sugar into the eye, the LED switched off. The lens didn鈥檛 appear to cause any irritation and didn鈥檛 overheat or fall apart.
The researchers are hoping the contact lens will become commercially available within the next five years. According to Park, it will mainly be used to let people with diabetes know if they need to adjust their medication or lifestyle because their sugar levels have crept up. But it could also be useful for monitoring people at risk of developing diabetes, he says.
听at agrees that the contact lens could help people get early intervention if their blood sugar shoots up. However, one limitation is that it only tells people whether they have exceeded a particular sugar level, rather than giving an exact reading, he says. 鈥淚t means you can鈥檛 see how your blood sugar is trending over time, which is often valuable information.鈥�
Sugar monitoring
The new technology听is a significant advance over prior contact lenses for sugar monitoring, says听听at Oregon State University. 鈥淭he research team has considered many of the issues that may limit smart contact lenses, including transparency, reduced haze and high flexibility,鈥� he says.
Several other options for sugar monitoring are now available for people with diabetes. In September, the US Food and Drug Administration听听that is worn on the back of the arm and continuously measures sugar via a small wire inserted below the skin surface. People can download the data to their phone or computer to see how their blood sugar levels change over time.
Other groups are working on patches that detect sugar in听听and a mouth guard for measuring sugar in听.
Park鈥檚 group is investigating whether its smart contact lens can monitor other diseases by measuring different chemicals in tears. The team is also interested in filling the lens with LED pixels to create completely immersive augmented reality experiences.
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