Scientists Created a 'Self-Plugging' Eye Microneedle

It may seem like something out of a horror movie, but some conditions require medications to be properly injected into your eye.

Not only does the procedure seem awful, but there are other things that may go wrong. Endophthalmitis, for example, is a bacterial infection caused by germs entering the hole where the needle was inserted.

Repeated injections might potentially cause harm to the ocular tissue. Worse worse, tumor cells may float through the freshly created hole and spread to other parts of the body.

With this in mind, an international group of researchers has created a new, perhaps superior technique for delivering medications to the eye that avoids these issues.

The new procedure has done well in preclinical studies, but it still includes eye needles, which is a source of our nightmares.

"This novel improvement in drug delivery treatment can avoid problems associated with using needles to treat serious eye diseases," said Ali Khademhosseini, head of the Terasaki Institute for Biomedical Innovation.

Intravitreal injection is the medical term for injecting a medication into the vitreous humor of the eye (jelly-like fluid that fills the eyeball). It's used to treat conditions including age-related macular degeneration (AMD) and diabetic eye disease.

Multiple injections of an anti-VEGF medication into the jelly-like material in the eye are now the therapy.

Instead of relying on several infection-risking injections between treatments, the researchers developed an ultrathin microneedle that remains in the eye and biodegrades over time.

While within the eye, the microneedle contains a hydrogel 'plug' that seals the hole it has produced and gradually releases the medicine it is coated in. Below is an illustration of what this would look like.

A graphical representation of the new design

The researchers, who came from a variety of universities around South Korea, put the new approach to the test in several ways.

The microneedles were first implanted into the eyes of excised pigs. This indicated that the hole had been closed after the injection and that the medicine (in this example, a purple dye) had spread across the eye as expected.

The scientists then took it a step further and implanted the microneedle into living pigs. The investigators discovered no signs of leaking or irritation at the location, and the needle's tip remained securely lodged in place seven days later.

"It is also noteworthy that the fluorescent signal of [the model drug] rhodamine B was evident even in the deeper retinal tissues and retinal pigment epithelium at the farmost site from the tip of self-plugging microneedle," the researchers write in their new report.

"These data indicate that [the model drug] from the tip of the self-plugging microneedle was successfully dispersed through the vitreous and the retina."

As is typical with these kind of trials, there's a long way to go before your neighborhood optometrist injects you with a biodegradable self-plugging microneedle. Longer investigations in animal models will be required to establish safety, and clinical trials will be required to validate if the design is also safe in people.

However, for the time being, this is an intriguing discovery that may bring a little less horrifying answer to a horrifying situation.