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K. Hosseini, M. Cormier, G. A. Peyman; Intraocular Jet Injector Device. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5106. doi: https://doi.org/.
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Various ocular diseases requiring intraocular drug administration could benefit from an automated, minimally invasive, and safe drug delivery system, (e.g. AMD, diabetic retinopathy, endophthalmitis, CMV retinitis). Recent novel drug development for conditions such as AMD focuses almost entirely on intravitreal injections of Anti VEGFs. In addition, subconjunctival injection is being increasingly explored for conditions such as AMD (e.g. Sirolimus). Besides conventional syringes and needles, there are no intraocular injection devices on the market and existing devices are not adapted to intraocular injection. In particular they lack a mechanism that would allow precise positioning to the pars plana area, the area of choice used for intravitreal injection. We have developed a jet injector, combining a positioning platform and a microneedle for precise positioning and safe automated injection through the pars plana area.
A prototype automated jet injector combining an alastomeric application platform 6 mm in diameter and a microneedle extending 1 mm beyond the center of the positioning platform was designed and manufactured. The device was filled with a dye solution. For injection, the edge of the platform was applied at the limbus of enucleated albino rabbit eyes so that the microneedle was positioned at the pars plana area and the microneedle was then pushed inside the sclera using gentle manual force. Each eye was then injected with 0.1 mL of dye solution using injection pressures ranging between 30 and 1000 psi. Following removal of the device, the eyes were dissected to evaluate the quality of injection and possible damage to the lens and pictures were taken.
Results demonstrated that high pressure (1000 psi) is necessary to achieve consistent intravitreal injection. Subconjunctival injection could be reproducibly achieved using a range of intermediate pressures. Low injection pressure (30 psi) yielded inconsistent results with a large number of wet injections. In all cases absence of macroscopic damage to the lens and to the different structures of the eye was noted.
A microneedle jet injector combined with a positioning platform is a feasible device for consistent automated intravitreal or subconjunctival injection. Placement of the edge of the platform at the corneo-scleral limbus allows precise positioning and application of the microneedle to the pars plana area. A microneedle that penetrates partly through the sclera allows the use of lower pressures for minimally invasive intravitreal jet injection as compared to conventional jet injection.
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