Targeting specific regions of the eye when injecting drugs using hypodermic needles has been a challenge that researchers at Georgia Tech are helping overcome. Using tiny stainless steel microneedles less than 1mm in length, the researchers injected fluorescein and fluorescently tagged dextrans, bevacizumab, and polymericparticles into the suprachoroidal space of rabbits’ eyes.
Because of the anatomy of the eye around the suprachoroidal space, injected particles quickly found themselves on the choroid and retina and remained there for months. Not only does the technique allow for drug targeting of the back of the eye, it automatically provides an option for extended release therapeutics.
From the study abstract in Investigative Ophthalmology & Visual Science:
Results. Molecules and particles injected near the limbus using a microneedle flowed circumferentially around the eye within the suprachoroidal space. By targeting the suprachoroidal space, the concentration of injected materials was at least 10-fold higher in the back of the eye tissues than in anterior tissues. In contrast, intravitreal injection of fluorescein targeted the vitreous humor with no significant selectivity for posterior versus anterior segment tissues. Half-lives in the suprachoroidal space for molecules of molecular weight from 0.3 to 250 kDa ranged from 1.2 to 7.9 hours. In contrast, particles ranging in size from 20 nm to 10 μm remained primarily in the suprachoroidal space and choroid for a period of months and did not clear the eye. No adverse effects of injection into the suprachoroidal space were observed.
Conclusion. Injection into the suprachoroidal space using a microneedle offers a simple and minimally invasive way to target the delivery of drugs to the choroid and retina.
Abstract in Investigative Ophthalmology & Visual Science: Targeted Administration into the Suprachoroidal Space Using a Microneedle for Drug Delivery to the Posterior Segment of the Eye
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