Optimization of novel exoscopic blue light filter during fluorescence-guided resection of Glioblastoma

Purpose Operative guidelines and use optimization for new surgical exoscopes are not well described in the literature. In this study, we evaluated use of the ORBEYE (Olympus) surgical exoscope system during 5-ALA fluorescence-guided resection of GBMs to optimize workflow and exoscope settings. Methods The ORBEYE exoscope system was fitted with a blue light filter for 5-ALA mediated fluorescence-guided surgery (FGS). Intraoperative images were obtained during 5-ALA FGS in 9 patients with primary or recurrent GBM. The exoscope was set up at constant, increasing focal distances from the target tissue, and light source intensity varied. High-resolution 4 K images were captured and analyzed. Comparisons of fluorescence to background were then generated for use optimization. Results Light intensity did not significantly influence tumor fluorescence (P = 0.878). However, focal distance significantly impacted relative fluorescent intensity (P = 0.007). Maximum average fluorescence was seen consistently at a focal length of 220 mm and a light intensity of approximately 75% maximum. Decreasing focal distance from 400 mm to 220 mm significantly increased visualized fluorescence (P = 0.0038). Conclusions The ORBEYE surgical exoscope system with blue light filter is a powerful imaging tool for 5-ALA FGS in GBM. The ORBEYE blue filter performs optimally at shorter focal distance with moderate light intensity. Similar to microscope systems, decreasing focal distance significantly influences visualized fluorescence.