Treating Eye Diseases by Needles Through the Eye
Meghan Hegarty (12:00 Micro) found another article from Science Daily, which describes research from Georgia Tech with a new method for drug delivery. The eye is an immunologically privileged site of the body, which is the reason corneal transplants are actually rather easy to accomplish. However, this also creates other problems in that delivery of compounds through the bloodstream to the eye can be challenging. Here is Meghan’s summary, which describes an outside of the box approach to the problem:
Nearly everyone has heard of smoking marijuana to help treat glaucoma, but how effective can this method be? Researchers have discovered a more effective and reliable method, one that involves the eye to be punctured by small needles. Microneedles that are no larger than 700 microns, can deliver drugs to specific areas of the eye rather than the whole eye. By this method, researchers believe the effectiveness of the treatment can be increased, as well as limit side effects and reduce the amount of drug needed to treat both glaucoma and corneal neovascularization.
Glaucoma is the second leading cause of blindness in the world and affects more than 2.2 million people in the United States alone. The microneedle injection treatment method could replace daily administration of eye drops and only be needed every three to six months. The second disease, corneal neovascularization, results in the growth of unnecessary blood vessels that impair vision. For this disease, researchers have created a treatment that would inject a dry drug compound to stop the vessel growth via a solid microneedle. The use of needles to treat eye conditions allows doctors to deliver the drug within the eye to specific areas, rather than the whole eye. Mark Prausnitz of the School of Chemical and Biomolecular Engineering at the Georgia Institute of Technology states that they are developing “different microneedle-based systems that can put the drug precisely into the part of the eye where it’s needed.” To further improve this, researchers want to create a drug that is has a controlled-release formulation that would allow one application to treat the condition for months.
The research is being supported by the National Eye Institute of the National Institutes of Health and is currently being tested on animals. The new treatments have become necessary since only about fifty-six percent of glaucoma patients follow the appropriate treatment protocol to their eye disease. Glaucoma is currently being treated with eye drops that need to be applied daily, a nuisance to many. The microneedle would inject drugs into space between two layers of the eye near the ciliary body. The drug would stay near the injection site and would reduce intraocular pressure through the injection. Because the injection targets a specific site, researchers are able to reduce pressure by using only one percent of the amount of drug that is required to produce a similar reduction with eye drops.
The ultimate goal for the researchers would be for patients suffering with glaucoma is for them to only need to visit a doctor to get the injection, and not need another injection for the next six months. Getting rid of the eye drop treatment method would potentially have better control of the symptoms and treatment. To treat corneal neovascularization, the needle would need to be help in place in the eye for roughly one minute until the drug dissolved into the cornea of the eye. In animal testing, the drug stopped the growth of unwanted blood vessels for about two weeks after one application.
Currently, eye injections are being completed with hypodermic needles that are much larger than the microneedles to administer a drug into the center of the eye. While patients tolerate this method, the microneedle treatment would not cause significant side effects and are tailored specifically to penetrate the eye only as far as needed to deliver the drug. For example, the needle required for glaucoma treatments would only need to be about half a millimeter long. Before this new treatment method can become available to people, more animal testing needs to be completed. If all goes well in the animal trials, people would have a much more effective and convenient method to battle their eye conditions.