Smart contact lens alleviates dry eye syndrome

Researchers at Tohoku University in Japan have used electroosmotic flow to create a self-moisturising contact lens, an advance that could help alleviate dry eye syndrome.

dry eye syndrome
Illustration of a self-moisturising soft contact lens that supplies tears via electroosmotic flow from the temporary tear reservoir behind the lower eyelid (Image: Tohoku University)

The self-moisturising lens, which works by maintaining a layer of fluid between the contact lens and the eye, is described in Advanced Materials Technologies.

“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,” said Prof Matsuhiko Nishizawa, an engineer at Tohoku University.

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One drawback with contact lenses is that they can cause dry eye syndrome due to reduced blinking and increased moisture evaporation. Dry eye syndrome can lead to corneal wounds, inflammation, and a feeling of discomfort.

According to the University, the system uses electroosmotic flow (EOF), which causes liquid to flow when a voltage is applied across a charged 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.

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

The researchers also explored the possibility of using a wireless power supply for the contact lenses and tested two types of battery, a magnesium-oxygen battery and an enzymatic fructose-oxygen fuel cell, both of which are non-toxic to living cells. They reportedly showed that the system can be successfully powered by these biobatteries, which can be mounted directly on the charged contact lens.

Further research is needed to develop improved self-moisturising contact lenses that are tougher and capable of operating at smaller currents.

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