Researchers at the Georgia Institute of Technology and Atlanta's Emory University have developed microneedles less than a millimeter in length that can deliver drug molecules and particles to the region in the back of eye. The new technology provides an alternative to current methods which are either invasive, with drugs being injected into the center of the eye, or based on eyedrops, which are limited in their effectiveness.

During the study, the injections targeted the suprachoroidal space of the eye, which is located between the white of the eye (sclera) and the vascular layer of the eye (choroid). The suprachoroidal space works as a natural passageway for drugs injected across the sclera to flow along the eye’s inner surface before reaching the back of the eye.

A diagram of the human eye, indicating the location of the sclera and choroid - labels at top right (Image via Shutterstock)

The injected fluids reached the targeted structures and remained there for as long as two months, a fact that opens the way for slow-release drug design. Additionally the injected molecules and particles did not reach the lens or front part of the eye in significant amounts, decreasing the chances of side effects, since this is the area where they usually occur.

The microneedles are made of stainless steel. The researchers believe that they will cause less trauma to the eye than the larger hypodermic needles, and reduce the risk of infection. For the study, the researchers used compounds that fluoresced inside the eye, indicating that they had reached their targets. Now, the researchers will use actual drugs to find out how well the technique will fare in terms of actually treating the targeted structures.

As new compounds to treat eye diseases are developed, a more efficient delivery method will increase the efficiency of the treatment of the choroid and retina, which are the structures the microneedles target. “With this technique, we are keeping the drug right where it needs to be for most therapies of interest in the back of the eye,” said Henry Edelhauser, a professor of ophthalmology at Emory School of Medicine.

Details of the study were published in the July issue of the journal Investigative Ophthalmology & Visual Science.

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