A Robotic Injection System for Consistent Pneumo-dissection of the Deep Stroma in Big Bubble DALK Surgery

In this paper we present a novel robotic injection system capable of performing clinically relevant pneumo-dissection of the deep stroma for the big bubble DALK procedure. Because the recommended clinical technique to insert a needle into the deep stroma using a horizontal approach results in inconsistent dissection, we designed an automatic injection robot to employ a vertical approach to consistently pneumo-dissect the tissue. In bench testing with synthetic tissues, the system was able to generate a max pressure of 90 kPa and held the pressure with a deviation of 0.07 kPa. Using this pressure, the system was used to successfully pneumo-dissect the deep stroma of N=5 ex vivo rabbit corneas. The resulting pneumo-dissections had dissection area of 87.50 ± 2.70%, circularity of 89.20 ± 0.77%, and an off-center percentage of 3.10 ± 2.20%. These metrics were significantly better than surgeons performing freehand injections with a horizontal approach. To our knowledge, this paper reports the first-time automatic robotic injections were used to create pneumo-dissection in the deep stroma. Integration of the robotic injector in future DALK procedures will enable control over variations in injection pressure, volume, and speed which may generate even more uniform dissection of the deep stroma.