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Contact lens that enhances tear flow could prevent dry eye

A grant from CooperVision has supported a team of researchers from the Terasaki Institute for Biomedical Innovation in Los Angeles to develop a contact lens prototype that uses tears to monitor patient health.

The lens is composed of a specially engineered hydrogel, which is optimised to obtain elastic characteristics that would allow it to be engineered into various shapes with a smooth surface profile.

They then modelled the microchannels in the hydrogel with the use of a 3D printed mould. The final step in the manufacturing process was to enclose the hydrogel channels by bonding an additional layer of hydrogel to the surface of the microchannel.

Once the successful prototype was completed, it was tested for its performance in channelling and collecting fluids such as artificial tears.

“A noteworthy observation during these tests was that when the hydrogel was mildly dehydrated, liquid flow in the channels would stop, but when additional rhythmic pressure was applied, the flow would resume,” the researchers said.

“This was an important demonstration of support for the hypothesis that eye blinking would also provide the necessary pressure and additional hydration needed to allow for tear flow in the contact lens, and therefore, in the eye.”

According to the Terasaki Institute, measurable biomarkers found in tears include sodium ions, which are useful indicators of dry eye disease, and glucose molecules, an early diagnostic tool for diabetes. Measuring the pH of tears can also be used to check for cell viability, drug effectiveness and for signs of disease.

“In addition to our successful fabrication of microchannels in commercial contact lens hydrogels, we also found that eye-blinking pressure may facilitate tear exchange in the lens through these microchannels,” Dr Shiming Zhang, from the Terasaki Institute’s research team said.

“This is an exciting finding because it opens the possibility for the lenses to be a means of preventing dry eye disease, a condition commonly found in contact lens wearers. We aim to develop a patented contact lens that actively treats this condition by enhancing tear flow in the eye.”

The research team is planning to experiment with smaller channels in thinner hydrogel films before a final contact lens is devised.

Director and CEO of the Terasaki Institute, Dr Ali Khademhosseini, said the successful prototype and the continuing efforts to perfect its capabilities mark a significant advance in contact lens biosensing.

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