Purpose
Intraoperative OCT utilizing a microscope-integrated optical coherence tomography (MIOCT) system may potentially revolutionize ophthalmic surgery by providing real-time images of tissue microstructure during surgical maneuvers. However, clinical translation of current-generation MIOCT systems have been limited by bulky optomechanics, which require precision alignment and integration with surgical microscopes, and fixed-focus optical designs, which rely heavily on surgeon-based focusing of the surgical field. We present a system design for a novel MIOCT system focused on clinical translation with a reduced-size monolithic form factor, tunable focus, foot-pedal control, and heads-up-display (HUD) for enhanced ergonomics and surgeon feedback.
Methods
A novel MIOCT scan-head was implemented with optomechanical mounts designed into the enclosure and 3D printed as a monolithic unit to ensure precision optical alignment and reduce system weight (Fig. 1). An electrically tunable lens allowed for real-time focus control, which can compensate for +/-7D of defocus for optimized imaging of both anterior and posterior segment and surgeon-independent fine OCT focus. A microcontroller board allowed for analog control of the OCT imaging field position, scan length, orientation, and focus via foot-pedal control. A VGA display was also folded into the optical path of the microscope ocular, which provided overlaid OCT images on a customizable HUD for surgeon feedback.
Results
Ophthalmic surgical instruments and maneuvers were imaged in cadaveric porcine eyes as a proof-of-concept with our novel MIOCT system using a Bioptigen SDOIS engine (830+/-30 nm, 20 kHz line-rate). The tunable lens allows optimization of OCT signal by focusing within the retina or on features above the tissue surface. HUD overlays of OCT cross-sectional images provide real-time feedback on tissue-instrument interactions for surgical guidance (Fig. 1).
Conclusions
Enhanced ergonomics may facilitate clinical translation of intraoperative OCT. Our novel MIOCT implementation addresses several limitations of previous microscope-integrated systems. Functional features, such as focus control, aiming, and HUD provide real-time feedback on surgical maneuvers, which can potentially be used to guide surgical decision-making while minimizing disruption to surgical workflow.
Keywords: 551 imaging/image analysis: non-clinical •
552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) •
762 vitreoretinal surgery