Microneedles For Glaucoma Deliver Drugs Straight Into The Eye, Focusing Treatment

So you’ve crossed your heart and hope to die, and now all that’s left is to stick that dreaded needle in your eye. If a recent study has anything to say, however, your hopes will go unanswered. Microneedles are revolutionizing how people get medicine to treat their eye diseases.

Glaucoma is the second leading cause of blindness worldwide. In the United States alone, 2.2 million people suffer from the group of disorders, which collectively result from a build-up of fluid pressure in the eye and can cause optic nerve damage over the long-term. The new drug therapies would target this pressure directly, as opposed to blanketing treatments that crudely target the entire eye.

microneedle1 Microneedles could revolutionize treatment for eye diseases. Georgia Institute of Technology

Right now the most common method for treating glaucoma is eye drops. They’re convenient and relatively cheap, not to mention painless. But they also demand daily reapplication to stay effective, and few people use them as often as they should. The new microneedles, which are barely visible to the human eye at 400 to 700 microns long, were shown in animal models to last up to six months — roughly the time between two eye doctor visits.

“We are developing different microneedle-based systems that can put the drug precisely into the part of the eye where it’s needed,” said Mark Prausnitz, lead author of the study and a professor at the Georgia Institute of Technology, in a press release.

Doctors will be able to reduce production of aqueous humor fluid in the eye, increase flow away from the eye, or both, through direct injection into space between two layers of the eye near the ciliary body, which produces the fluid. Because it’s so precise, the microneedles uses only one percent of the amount used in eye drops.

Glaucoma isn’t the only disorder the researchers hope to target. Another is corneal neovascularization, a disease involving the unwanted growth of blood vessels from an area called the limbal vascular plexus into the cornea. For this, the research team has found success in animal models with a dry drug they can inject into a subject’s eye with a solid needle. The drug sits just below the surface, near the injury site, for about a minute so the drug can dissolve into the cornea. A single dose lasted about two weeks.

microneedle2 Microneedle close-up Georgia Institute of Technology

The supreme benefit of the microneedles is their ability to deliver drugs essentially under the radar. Other methods get the job done, but come with substantial flaws.

“Increasingly, eye drops are not able to deliver drugs where they need to go, so injections into the eye are becoming more common,” said GIT Professor of Ophthalmology Henry Edelhauser. “But hypodermic needles were not designed for the eye and are not optimal for targeting drugs within the eye.”

More animal tests are still upcoming, the researchers conceded. A separate avenue of research looks at time-released injections of the drugs, although the current team did not test for that function in their recent study. For now, the focus is on maintaining success with microneedles just past the sclera and into the supraciliary space in the eye. The result is a pain-free delivery of drugs, which hold the potential to end a major cause of blindness around the world if only they could reach their targets.

“If we can do away with the need for patients to use eye drops,” Prausnitz said, “we could potentially have better control of intraocular pressure and better treatment of glaucoma.”

Source: Prausnitz M, Kim Y, Edehauser H. Targeted delivery of anti-glaucoma drugs to the supraciliary space using microneedles. Investigative Ophthalmology & Visual Science. 2014.

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