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Jarel Gandhi, Fukutaro Mano, Raymond Iezzi, Jose S Pulido, Alan D Marmorstein; Iterative development of an insertion instrument for sub-retinal transplantation. Invest. Ophthalmol. Vis. Sci. 2020;61(7):792.
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To develop, through methodological iteration, an inserter to perform sub-retinal transplantation of a cell-scaffold implant.
Four inserters were prototyped by various methods. The first two inserters (D1, D2) were machined from stainless steel hypodermic stock and utilized a syringe-style plunger mechanism. Subsequent inserters (D3, D4) included a clear plastic tip that was 3D printed using a soft lithography technique. For D3 a plunger was fashioned from a metal wire and silicone plunger that was driven by a pneumatic actuator. In D4 the silicone was omitted from the plunger and replaced with a silicone seal above the plunger. The ability of the inserters to deliver a fibrin hydrogel was initially assessed using post-mortem domestic pig eyes. D3 and D4 were further assessed for surgical implantation of fibrin hydrogels in the sub-retinal space of live domestic pigs.
The metal cannula design (D1) utilizing fluid-based deployment was unsuccessful at expelling the fibrin implant within a pressured eye (n=3). The design was modified to include a polytetrafluoroethylene (PTFE) plunger (D2). The plunger deployment mechanism was successful at deploying the fibrin implant (n=1). However, in some instances the implant became wedged within D2 potentially causing damage to the implant. To visualize if damage occurred, our next iteration consisted of a clear plastic housing tip (D3). D3 allowed us to determine that the use of a silicone sealed plunger was problematic resulting in successful placement in only 1 of 7 in vivo trials. To address this, D4 was designed with a detachable tip mechanism that featured a spring-loaded metal wire plunger and no silicone plug. D4 was successful at placing the implant within the sub-retinal space on 15 of 17 attempts.
A mechanical plunger was necessary for successful deployment. Visualization of the implant within the inserter was crucial to assess potential damage occurring within the inserter during deployment. Two key aspects of implantation include the use of a clear tip and metal plunger. These properties will be included in further iterations of the instrument.
This is a 2020 ARVO Annual Meeting abstract.
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