Virtual Loupes: A Pilot Study on the Use of Video Passthrough Augmented Reality in Plastic Surgery.

[BACKGROUND] Plastic surgeons use loupes or operative microscope to aid in tissue dissection and anastomosis of structures. These devices have their own limitations in areas of visualization and weight. Current uses of augmented and virtual reality in surgery have been limited to operative planning and simulation. We present a proof of concept that harnesses video passthrough AR technology to augment the capabilities of loupes.

[METHODS] We first evaluated methods of gaze-based eye tracking to enable digital magnification. Using the Varjo XR-1 mixed reality headset, we compared discrete zoom through displayed pop-up menu vs continuous zoom through eye winking. Six participants were recruited to perform skin suturing simulation and completed a survey and interview. Next we assessed the performance and limitations of AR digital magnification. Varjo XR-3 was utilized to address the hardware limitations. Participants performed anastomotic suturing tasks with progressively finer suture, then completed a survey and interview.

[FINDINGS] There was no strong preference between zoom methods, although participants felt the discrete zoom was easier to use. Participants had difficulty determining depth and visualizing the suture due to limitations of digital magnification. Using Wilcoxon rank sum test to examine differences in system usability scale, the Phase 2 user experience had significant difference in percentile distribution ( 0.0390).

[CONCLUSION] Virtual loupes may be a valuable tool for plastic surgeons, with potential for variable magnification and advanced visualization. Improvements in the hardware yielded higher ratings of system usability and user experience. Further development is needed to address the limitations of existing devices.