iOCT-guided simulated subretinal injections: a comparison between manual and robot-assisted techniques in an ex-vivo porcine model

Abstract

The purpose of this study is to compare robot-assisted and manual subretinal injections in terms of successful subretinal blistering, reflux incidences and damage of the retinal pigment epithelium (RPE). Subretinal injection was simulated on 84 ex-vivo porcine eyes with half of the interventions being carried out manually and the other half by controlling a custom-built robot in a master–slave fashion. After pars plana vitrectomy (PPV), the retinal target spot was determined under a LUMERA 700 microscope with microscope-integrated intraoperative optical coherence tomography (iOCT) RESCAN 700 (Carl Zeiss Meditec, Germany). For injection, a 1 ml syringe filled with perfluorocarbon liquid (PFCL) was tipped with a 40-gauge metal cannula (Incyto Co., Ltd., South Korea). In one set of trials, the needle was attached to the robot’s end joint and maneuvered robotically to the retinal target site. In another set of trials, approaching the retina was performed manually. Intraretinal cannula-tip depth was monitored continuously via iOCT. At sufficient depth, PFCL was injected into the subretinal space. iOCT images and fundus video recordings were used to evaluate the surgical outcome. Robotic injections showed more often successful subretinal blistering (73.7% vs. 61.8%, p > 0.05) and a significantly lower incidence of reflux (23.7% vs. 58.8%, p < 0.01). Although larger tip depths were achieved in successful manual trials, RPE penetration occurred in 10.5% of robotic but in 26.5% of manual cases (p > 0.05). In conclusion, significantly less reflux incidences were achieved with the use of a robot. Furthermore, RPE penetrations occurred less and successful blistering more frequently when performing robotic surgery.

Sharper vision, steady hands: can robots improve subretinal drug delivery? Systematic review

“…Maierhofer et al utilized 72 porcine eyes to compare the efficacy of their custom robot with manual surgery, simulating drug injection with perfluorocarbon liquid [ 13 ]. Standard triple channel pars plana vitrectomy approach was performed.…”

“…Studies using porcine eyes also indicated potential reduction in subretinal reflux, a complication where the injected drug leaks back out [ 13 ]. Included studies suggest that RA SI may improve drug delivery efficiency.…”

“…While visual acuity improvement did not reach statistical significance, the procedure was well tolerated, and there were no major differences in surgical times or complications between RA SI and manual groups. Ex vivo studies using porcine eyes also achieved successful drug delivery in both RA and manual groups [ 13 , 14 ].…”

“…Currently, RA SI procedures take longer than manual techniques [ 5 , 13 , 14 ]. This might be due to the novelty of the technology and the learning curve for surgeons—robots contribute their operation time for maximum accuracy of the injection, which requires additional procedure time for more controlled movements of the system.…”