Smart contact lenses harness tears to prevent dry eyes

23 Jan 2020

Image: © HQUALITY/

Researchers in Japan have developed smart contact lenses that self-moisturise by forcing tears into your eyes.

Engineers at Tohoku University have found a novel way for those who wear contact lenses to keep their eyes from drying out without intervention. In a paper published to Advanced Materials Technologies, they described lenses that could help people overcome ‘dry eye syndrome’, caused by reduced blinking and increased moisture evaporation while wearing lenses.

While contact lenses today are used to correct vision, it’s foreseen that future smart contact lenses could enhance human capabilities, including the ability to see much further into the distance or experience the world through augmented reality.

Key to this latest breakthrough is a new mechanism that keeps the lens moist. It uses something called electroosmotic flow (EOF), which causes liquid to flow when a voltage is applied across a surface. In this case, a current applied to a hydrogel causes fluid to flow upwards from the patient’s temporary tear reservoir behind the lower eyelid to the surface of the eye.

‘There is scope to expand this technology for other applications, such as drug delivery’

“This is the first demonstration that EOF in a soft contact lens can keep the lens moist,” said Prof Matsuhiko Nishizawa.

“Although there have been many recent advancements in new functions for smart contact lenses, there has been little progress in solving the drawbacks associated with wearing contact lenses day to day.”

The researchers also considered the idea of using a wireless power supply for the lenses. Two types of battery were tested, both of which are known to be safe and non-toxic, including a magnesium-oxygen battery and an enzymatic fructose-oxygen fuel cell.

Tests showed that the system can be powered by these biobatteries, which can be mounted directly on the lens.

“In the future, there is scope to expand this technology for other applications, such as drug delivery,” said Nishizawa.

Colm Gorey was a senior journalist with Silicon Republic