Colour-changing contact lenses could replace painful skin prick tests for diabetics
11:51 GMT, 24 May 2012
Millions of diabetes sufferers face the daily grind of frequent skin prick tests to monitor their blood sugar levels.
Now researchers have developed an innovative alternative that could reveal the same information in the blink of an eye.
A team from The University of Akron have developed a contact lens that senses glucose which is the blood sugar in tears, the natural fluid that bathes the eye.
Eye-opener: This picture from the University of Akron shows a simulation of how the contact lens would work
If sugar is not being metabolised properly and glucose concentration builds up in the body, the contact lens will detect a problem and change colour.
'It works just like pH paper in your high school chemistry lab,' said Dr Jun Hu.
'The sugar molecule literally acts like the proton in a pH test, displacing a colour dye embedded in the lens, and the lens changes colour.'
Usually when you dissolve sugars in water you can't see them. Dr Hu has used a molecule, called a probe, that binds well to sugars that they then combined with a dye. When sugar concentrations rise the sugar binds to the probe and knocks the dye loose, causing a colour change.
The person wearing the lens wouldn't notice the change unless they looked in the mirror, so the team are now designing an app that will calculate sugar levels from a camera phone snap of the eye.
Scientists say the lens could be available in three years
Dr Hu said: 'This device could be used to detect subtle changes in blood sugar levels for tight management of diabetes. It can also be used to identify patients with pre-diabetic conditions, allowing early diagnosis that is crucial for preventing diabetes from advancing.
'The convenience of contact lenses could boost patient compliance to blood sugar testing, as it will reduce discomfort, inconvenience, and even cost.
'In addition, blood sugar also changes rapidly throughout a normal, active day, so a device that can monitor glucose many times in a day will provide diabetic patients with a very powerful tool in combating such a damaging condition.'
The lens is currently at the prototype phase but scientists say they could be commercially available within three years if all goes well.
The next step will be to check that the dye binds completely to the contact lens and does not leach as this could be dangerous to the eye.