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The blinking 'eye on a chip' test device

Latest 'eye on a chip' device can now blink

A newly developed ‘eye on a chip’ that can blink has been a heralded as a major breakthrough for dry eye disease (DED) research.

A challenge for researchers developing DED treatments has been the availability of methods to test drugs without human or animal subjects. However, researchers from the University of Pennsylvania have now developed a fake eye that simulates blinking.

Researchers from the University of Pennsylvania’s Department of Bioengineering collaborated with colleagues from the Department of Ophthalmology and Department of Materials Science and Engineering to develop the eye.

The completed ‘eye on a chip’ is made from a 3D printed scaffold on which eye cells are grown. A slab of gelatine is used as the eyelid, which is mechanically moved over the ‘eye’ at the same rate a human blinks. The eye is also fed by a mechanical ‘tear duct’, which spreads artificial tears over the eye to create a tear film.

"From an engineering standpoint, we found it interesting to think about the possibility of mimicking the dynamic environment of a blinking human eye"
Dan Huh, University Of Pennsylvania

“From an engineering standpoint, we found it interesting to think about the possibility of mimicking the dynamic environment of a blinking human eye,” Dr Dan Huh, Assistant Professor of Bioengineering at the University of Pennsylvania and stud lead, said.

“Blinking serves to spread tears and generate a thin film that keeps the ocular surface hydrated. It also helps form a smooth refractive surface for light transmission. This was a key feature of the ocular surface that we wanted to recapitulate in our device.”

The device is being used to simulate DED by cutting the rate of artificial blinking and creating an environment to simulate the humidity of real-life conditions.

Compared to real eyes with DED, the device recorded similar results in an Schirmer strip test, an osmolarity test and in a keratography test.

“When people think of DED, they normally treat it as a chronic disease driven by inflammation, but there’s now increasing evidence suggesting that mechanical forces are important for understanding the pathophysiology of DED,” Huh said.

“As the tear film becomes thinner and more unstable, friction between the eyelids and the ocular surface increases, and this can damage the epithelial surface and also trigger adverse biological responses such as inflammation.”

Based on this, the team decided to test a lubricin-based drug that is currently undergoing clinical trials.

“When we tested this drug in our device, we were able to demonstrate its friction-lowering effects, but, more importantly, using this model we discovered its previously unknown capacity to suppress inflammation of the ocular surface,” Huh said.

The team hopes the blinking eye model could go on to be used in many other drug tests and reduce the necessity for early human and animal trials. Their research was published in the journal Nature Medicine.

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