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Niklas Alexander Maierhofer, Anne-Marie Jablonka, Hessam Roodaki, Abouzar Eslami, Mathias Maier, Ali Nasseri, Chris Patrick Lohmann; Implications of robot-assisted subretinal injections guided by intraoperative OCT. Invest. Ophthalmol. Vis. Sci. 2020;61(7):3715.
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© ARVO (1962-2015); The Authors (2016-present)
Surgical subretinal delivery of stem cells, gene vectors and pharmaceuticals via injections has found its way into clinical practice. However, complexities associated with maneuvering miniature instruments and performance under minimal haptic feedback are barriers in mainstream adoption of such therapeutic approaches. Introduction of surgical robots as manipulation devices together with establishment of advanced imaging devices as their sensing counterparts open new opportunities for facilitation of subretinal injections. This study attempts to use intraoperative OCT with a surgical robot for subretinal injections.
Injections are done by a 6 degrees of freedom custom-made robot controlled in a master-slave fashion. A disposable 1ml syringe filled with perfluorooctane (C8F18) and tipped with a 40G bent cannula is attached to the last joint of the robot. Ex-vivo porcine eyes are fixated on a rubber base allowing movements in XY plane. After performing a standard manual three port pars plana vitrectomy (PPV), the retinal target area is determined under a LUMERA 700 microscope with RESCAN 700 (Zeiss, Oberkochen, Germany). The needle is then robotically maneuvered through a trocar penetrating the retina. The process is continuously monitored via microscope-integrated OCT. At sufficient retinal depth, C8F18 is slowly injected into the subretinal space forming a bleb visible in OCT images. At all times, RPE continuity is monitored and maintained.
The procedure was performed on 40 ex-vivo porcine eyes with 28 successful injections (70%). Out of the 12 failure cases, 5 were due to penetration through the RPE (12.5%) and 7 were due to no or minimal bleb formation caused by reflux (17.5%). The duration of a successful injection from the moment of entry through the trocar till retraction was on average 118 seconds.
The combination of an imaging device capable of providing continuous depth-resolved OCT cross-sections with a robot allows for precise subretinal injections. Further studies on comparison of robot-assisted injections versus manually performed procedures could shed light on the advantages of employing robots for the purpose.
This is a 2020 ARVO Annual Meeting abstract.
Microscopic and OCT view of the injection needle in the subretinal space before injection.
Microscopic and OCT view of the formed bleb after injection.
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