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Vladimir Zarnitsyn, Samirkumar Rajnikant Patel, Rozemarijn S Verhoeven, Matthew S Lawrence; Characterization of sodium fluorescein administered into the suprachoroidal space of nonhuman primates using a microneedle. Invest. Ophthalmol. Vis. Sci. 2014;55(13):5258.
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© 2017 Association for Research in Vision and Ophthalmology.
The purpose of this study was to determine if microneedles could successfully administer fluid into the suprachoroidal space (SCS) of non-human primates and to characterize the delivery using standard ophthalmic imaging tools.
Two African green monkeys were injected in both eyes with sodium fluorescein (600 µg/mL). 50 µL was injected in the first animal and 100 µL was injected in the second. Microneedles of 33 G in diameter with length of approximately 650 µm were manufactured (Clearside Biomedical, Alpharetta GA) in order to access the suprachoroidal space in the monkey eyes. Microneedles were inserted across the conjunctiva and into the sclera at a perpendicular angle 5 mm posterior to the limbus with no surgical cut-down of the sclera. Intravitreal injections were performed with a 31 G needle and 50 and 100 µL was injected in the right eye of two monkeys. Intraocular fluorescein concentration was measured non-invasively over time by fluorophotometry to characterize fluorescein signal over the anterior-posterior extent of the eye. Color and fluorescent fundus photography, and optical coherence tomography (OCT) were also performed. Baseline and post-injection ultrasound biomicroscopy (UBM) was used to define the baseline eye wall thickness and its perturbation post-injection.
50 and 100 µL of fluorescein were successfully injected into SCS. Slit lamp biomicroscopy and OCT revealed no adverse effects associated with SCS injection over the time period evaluated. Suprachoroidal delivery was confirmed with UBM, revealing ocular wall thickening deep to the scleral conjunctival boundary. The absence of a substantial subconjunctival fluorescein accumulation and a negligible intraocular fluorescein signal by fundus photography, Spectralis® autofluorescence imaging, and fluorophotometry was additionally consistent with successful suprachoroidal placement of the delivered fluorescein. In contrast, intravitreal fluorescein injection contributed to significant intraocular fluorescein signal in the vitreous, serving as a positive control to substantiate the SCS placement of the microneedle injections.
SCS injection of up to 100µL of fluorescein was successfully performed in the primate eye using a microneedle and was well tolerated.
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