Delivering drugs directly to the eye using microneedles that dissolve

Enlarge (credit: Chen et al. 2018)

Patients with certain chronic eye diseases, like glaucoma and macular degeneration, typically either use inefficient eyedrops or have to get injections directly into their eyes. A team of researchers wants to replace these with a small patch patients can place on the eye, much like a contact lens. When removed, the patch leaves behind microneedles, which slowly dissolve in the corneal fluid, releasing drugs into the eye as they do. They claim it could make treatments more accessible and less painful for patients, while also providing a more controlled release of the drug.

Replacing injections with a patch

Getting drugs into the eye is a challenge. The most effective solutions tend to be unpleasant and involve actual injections into the eyeball. If doctors deliver the injection in a less horrifying part of the body, it can take a dangerously high initial dose to ensure that enough of the drug actually reaches the eye. Eye drops tend to wash out, and they're surprisingly inefficient: the eye only absorbs about five percent of the drug most of the time. For some patients, these tradeoffs lead to a choice between needles and blindness.

Some recent ideas have focused on contact lens-like hydrogels that keep drugs on the surface of the eye longer than eye drops to surgically implant tiny drug reservoirs into the eye. Others have involved microneedles: pyramid-shaped needles just a few hundred micrometers long. Microneedles have been increasingly popular as a less-painful way to get drugs through a patient's skin without an injection-they've been used to deliver vaccinations, local anesthetics, and anti-diabetic medications.

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