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Gholam A Peyman, Michel Cormier, Richard Lindstrom, Kamran Hosseini; Accurate Dose Delivery by Subconjunctival Jet Injection Device with Zero Back Flow. Invest. Ophthalmol. Vis. Sci. 2014;55(13):479.
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Subconjunctival drug delivery is an effective drug delivery route, however, the procedure requires precise administration in skilled hands and it is not free of risks (e.g. scleral puncture, conjunctival tear, unintentional (second) puncture, iatrogenic infection, etc.). Furthermore, the procedure results usually in localized, high pressure elevated bleb/bubble formation and there is an uncontrollable and unquantifiable back flow of the medication from the site of injection.
We developed an ocular jet injector delivery system that enables both subconjunctival and Intravitreal rapid injection with zero back flow characteristics, and automated diffuse distribution of the medication and thus no localized elevated thin walled bleb/bubble formation as opposed to traditional subconjunctival syringe assisted delivery. Jet injectors combining a fixed dose injection chamber with an elastomeric application platform assisted with a conventional nozzle or a microneedle were designed and manufactured. A blue dye was used as phantom medication solution and the device was loaded with this dye solution. The platform was applied on the conjunctiva of enucleated eyes or anesthetized albino rabbits so that the microneedle (or the jet from the nozzle) was penetrating the conjunctiva vertically (as opposed to a tangential positioning with a traditional needle & syringe maneuver). A rapid one shot actuation, triggered delivery of 100 microliter of the dye solution under a 200 millisecond time frame.
Results demonstrated that an average pressure of 115 PSI achieved consistent subconjunctival delivery in a reproducible manner with the microneedle jet injector vs 250 PSI using the conventional nozzle. All injections were diffusely and evenly spread under the conjunctiva and there were no back flow of the dye solution from the site of injection to the ocular surface. Macroscopically and microscopically there were no damages to the adjacent ocular tissues.
Rapid, one shot subconjunctival jet injection is possible without back flow and elevated bleb formation, and in a reproducible and apparent safe manner. Accurate dose delivery to the subconjunctival space is achieved due to zero back flow from the site of injection. Preliminary results with the same devices (different injection specs) appear to achieve the same zero back flow and accurate delivery characteristic for intravitreal delivery as well.
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