Instead, the new system could deliver medicine painlessly to the back of the eye through a flexible patch that would typically stay on the eye behind the lens for as much as a year at a time, slowly releasing controlled doses of medicine to the vitreous body of the eye through a group of “microneedles” too small to feel.
The rubbery patch is designed to conform to the eye’s contour and the needles can be tailored to reach specific layers of the eye as needed. The patch would be attached on an in-patient basis and would not affect the patient’s eyesight when in use.
The team of chemical and mechanical engineers tested the system successfully on eyes extracted from cows, moving the concept a major step closer to being tested on humans. The innovation is described in an article in the online edition of the Journal of Biomaterials Applications.
The patch can be compared to medication patches used on the skin, but on a much smaller scale and using different materials adapted to the complex environment of the eye.
Such a patch would be a much more precise and effective vehicle for delivering medications to patients with such conditions as vision-related complications of diabetes and age-related macular degeneration, both of which are becoming more prevalent.
“There’s lots of potential for treating eye diseases that we didn’t have even five years ago. It’s really exciting,” says co-author Heather Sheardown, a professor of chemical engineering. “There are medications out there to treat these diseases. As we develop better delivery methods, blindness isn’t going to be something that has to happen. If we can catch the disease early and we can treat it early, we can stop its progression.”
Sheardown’s lab, which focuses on delivering drugs to the back of the eye, will turn next to developing a reservoir system to allow drugs in such patches to be replenished externally.
The technical challenge for the team that developed the patch device was not only to find a way to deliver drugs in such a challenging setting, but to use affordable materials so the system can compete with hypodermic needles, explained co-author Ravi Selvaganapathy, an associate professor of mechanical engineering.
“All these stringent requirements were daunting. But the design solution that emerged was elegant,” he says.
The researchers received funding from the Natural Sciences and Engineering Research Council of Canada.
A close-up photo of the microneedles on the surface of the device can be found here: http://dailynews.mcmaster.ca/images/microneedle.jpg
A photo comparing the device to a Canadian dime can be found here: http://dailynews.mcmaster.ca/images/microneedle1.jpg
A photo comparing the tip of a hypodermic needle to the microneedles used in the device can be found here: http://dailynews.mcmaster.ca/images/microneedle2.jpg
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