Despite the fact that dry eye disease (DED) is a relatively common condition, there are relatively few drugs approved for its treatment. This is because the testing of such medications on actual human eyes would be quite risky. With that in mind, scientists have developed a blinking eye-on-a-chip.
The device was created by a team at the University of Pennsylvania, led by Assoc. Prof. Dan Huh and graduate student Jeongyun Seo.
It incorporates a dime-sized and -shaped 3D-printed porous surface, which serves as a scaffolding for human eye cells to grow within. Dyed-yellow corneal cells grow on the inner circle of that surface, while dyed-red cells of the conjunctiva (the tissue that covers the white part of the eye) form a ring around that circle.
A mechanical tear duct secretes dyed-blue artificial tears, which are spread evenly across the cells by a motor-activated artificial eyelid composed of a slab of gelatin. By default, that slab moves at the same rate as the average person blinks, forming a hydrating "tear film." DED occurs when the natural version of that film evaporates faster than it can be replenished, often because people tend to blink less often when performing activities such as using a computer for long periods of time. As a result, inflammation and irritation of the cornea occurs.
In lab tests, DED was induced by first placing the eye-on-a-chip in an enclosed environment with humidity similar to that of the average home or office, and then reducing its blinking rate by 50 percent. Not only did the cells negatively react in a manner similar to those in a human eye, but when a promising new lubricating drug was subsequently tested in the device, it was found to successfully reduce the DED symptoms. Clinical trials of that drug have produced a similar effect in human test subjects.
"Although we have just demonstrated proof-of-concept, I hope our eye-on-a-chip platform is further advanced and used for a variety of applications besides drug screening, such as testing of contact lenses and eye surgeries in the future," says Seo.
A paper on the research was recently published in the journal Nature Medicine.
Source: University of Pennsylvania