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Vladimir Zarnitsyn, Samirkumar Rajnikant Patel, Jesse Yoo, Glenn Noronha; Characterization of Suprachoroidal Injection in Multiple Species. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5032. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Suprachoroidal injections allow targeted administration of drugs to the choroid and retina and could lead to additional treatment options for vision threatening diseases. Here we aim to characterize and compare suprachoroidal injections in the eyes of rats, rabbits, pigs, non-human primates, dogs, and humans.
A retrospective study was performed to examine ex-vivo and in-vivo suprachoroidal injections into rat, rabbit, dog, pig, non-human primate and human eyes using microneedles. Microneedles developed for each species were used for suprachoroidal injection. Literature analysis and ultrasound bio-microscopy (UBM) were used to determine the thickness of the posterior layers of the eye (conjunctiva, sclera, choroid, and retina). A suprachoroidal injection was confirmed by either UBM or visual confirmation of injected formulation in the eye. The volume and type of formulation (solution, suspension, or gel) injected were collected.
Ranking of the total thickness of the posterior ocular tissues was as follows in order of increasing thickness: rat< rabbit< non-human primate< dog< human< pig and ranged from 0.35 mm -1.5 mm. Microneedle length ranged between 0.3 mm and 1.6 mm and was species dependent. The number of injections performed ranged from less than 10 in dogs to thousands in rabbits. Volume of formulations injected in each species in-vivo was: rat ≤ 5, rabbit ≤ 300, non-human primate ≤ 50, dog ≤ 100, pig ≤ 100 µL. In ex-vivo human eyes the volume was ≤ 100 µL. Suprachoroidal injections of solutions and suspensions were injectable in every species, while gels were only tested in rabbit and pig eyes. Suprachoroidal injection resulted in the formulation being injected within and between the sclera and choroid. The injectate spreads through portions of the eye and the immediate layers in all directions circumferentially towards the limbus and the optic cup and laterally around the eye during and following administration.
Suprachoroidal injections are characterized as injections that involve the administration of an injectate within the sclera and choroid and the expansion of the suprachoroidal space. The capability to inject drug formulations in a wide range of species should enable the non-clinical and clinical evaluation of suprachoroidal administration for the potential treatment of eye diseases.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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