GoKawiilMore than 80 million people suffer from glaucoma globally, making it the second most common cause of blindness worldwide. The disease—caused by elevated internal eye pressure damaging the optic nerve—is incurable, but its progression can be slowed with drugs to control eye pressure.
Now, researchers have developed an electronics-free smart contact lens that can track the disease in real time and also deliver drugs in response. The all-polymer lens includes a microfluidic sensor that monitors eye pressure, as well as pressure-activated drug reservoirs that dispense medicine as eye pressure rises.
“A lot of patients forget to take the medicine at the right time,” says Yangzhi Zhu, an assistant professor at the Terasaki Institute for Biomedical Innovation. “For our technology, we don’t need the user to manually operate or trigger. Everything is based on the sensor and the closed-loop drug delivery.”
A Contact Lens for Glaucoma Treatment
The gold-standard approach for measuring eye pressure requires patients to visit a clinic, and checkups are often months apart. This provides infrequent snapshots that often fail to accurately measure glaucoma’s dynamics. In addition, previous research has found that nearly half of patients stopped treating the disease within six months of filling an initial prescription.
There have been earlier efforts to treat glaucoma with smart contacts. In 2016, the U.S. Federal Drug Administration approved a device called Triggerfish, which embeds electronic components into a lens to provide continuous eye-pressure monitoring. And other research groups have built electronic smart contact lenses that combine pressure measurement and drug release.
But Zhu says the mechanical mismatch between rigid electronic components and delicate corneal tissue can lead to irritation and discomfort. “Frankly speaking, we know that electronic control is the most accurate, but the issue is that it is not user-friendly and not biocompatible, or comfortable for long-term use,” he says. “So we needed to find a better balance between the accuracy and the user comfort.”
The solution he and his colleagues came up with was to create a soft, all-polymer lens that relied on microfluidics to sense pressure and release drugs as needed. Microfluidics uses networks of microscopic channels and chambers to manipulate fluids. It’s normally used in biological analysis or medical diagnostics.
Yangzhi Zhu/Terasaki Institute for Biomedical Innovation
The researchers used 3D-printed molds to embed tiny microchannels and reservoirs into the bottom layer of their contact lens. These reservoirs were then filled with a specially designed silk sponge that can quickly absorb up to 2,700 times its weight in fluid.
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