To establish a safe and reproducible surgical delivery technique using the developed surgical device, we transplanted grafts into the subretinal space of 12 rabbits (
Supplementary Movie S3) and assessed the graft condition (damaged, folded), side (front, back), position (center, near, far), and direction (anterior, posterior, right, left) immediately after surgery (
Fig. 2). The device transplanted all grafts into the subretinal space without adverse events. The surgical outcomes immediately after the surgery are listed in
Table. Briefly, successful surgery was achieved in eight rabbits (
Fig. 4A), an unfavorable graft condition (fold) was observed in two rabbits (
Fig. 4B), and a misdirection (right direction) was observed in two rabbits (
Fig. 4C). Based on a surgical video analysis, after the ejection of the grafts into the subretinal space, the grafts moved toward and halted at the outlet. As the reason for the cause of the folded graft and right direction, we considered that the distance between the inlet and the outlet (
Fig. 4B, black line) was shorter than the graft length, and the flow paths (
Fig. 4C, black solid line) and the insertion device (
Fig. 4C, black dotted line) were not coaxial. A distance between the inlet and the outlet greater than graft and coaxial flow paths and insertion device corrected the condition and direction (consecutive five of five and nine of nine grafts, respectively). In addition, we examined whether we could recover from possible difficulties, such as damaged grafts, folded grafts, misdirection, inside-out grafts, and slipped grafts, to reposition the graft in the subretinal space or extract and reload the graft from the subretinal space to the device. Transplanted grafts could be repositioned in the subretinal space by aspiration with the brush backflush needle (
Supplementary Movie S4) and reloaded grafts from the subretinal space by aspiration with the developed device (
Supplementary Movie S5).