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Optical coherence tomography (OCT) allows high-resolution imaging of tissue microstructure and is the goldstandard for clinical ophthalmic diagnostics. Recent development of microscope-integrated intraoperative OCT (iOCT) systems has allowed cross-sectional imaging of surgical dynamics, but limitations in real-time visualization of instrument-tissue interactions remain the critical barrier for iOCT-guided ophthalmic surgery. Spatial compounding has been previously presented as a method for acquiring, processing, and visualizing cross-sectional iOCT images of surgical maneuvers. However, spatial compounding trades-off temporal resolution and FOV, which generally limits video-rate visualization to small regions at the tip of surgical instruments. To overcome these limitations, we present methods for automated dynamic surgical instrument tracking iOCT. B-scans are obtained along and orthogonal to the instrument axis and centered at the instrument tip at all times to allow cross-sectional visualization of ophthalmic surgical maneuvers for intraoperative guidance. Surgical instrument tracking has been previously demonstrated using different imaging modalities, including an OCT-integrated scanning probe. However, the latter uses large feature points, which are impractical in a surgical setting. Here, we describe automated stereo-vision instrument tracking, which achieves <250 μm accuracy, using tracking feature points that are easily integrated with ophthalmic surgical instruments. The instrument tracking system was integrated with an iOCT system to provide video-rate instrument tip tracked crosssectional B-scan imaging during ophthalmic surgical maneuvers, allowing visualization of tissue-instrument interactions and providing feedback on positioning, depth of penetration, and tissue compression in cadaveric porcine eyes. Real-time instrument tracked cross-sectional imaging can potentially help guide clinical decision-making during ophthalmic surgery.
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