Towards Robotic Eye Surgery: Marker-Free, Online Hand-Eye Calibration Using Optical Coherence Tomography Images

Abstract

Ophthalmic microsurgery is known to be a challenging operation, which requires very precise and dexterous manipulation. Image guided robot-assisted surgery (RAS) is a promising solution that brings significant improvements in outcomes and reduces the physical limitations of human surgeons. However, this technology must be further developed before it can be routinely used in clinics. One of the problems is the lack of proper calibration between the robotic manipulator and appropriate imaging device. In this work, we developed a flexible framework for hand-eye calibration of an ophthalmic robot with a microscope-integrated Optical Coherence Tomography (MI-OCT) without any markers. The proposed method consists of three main steps: a) we estimate the OCT calibration parameters; b) with micro-scale displacements controlled by the robot, we detect and segment the needle tip in 3D-OCT volume; c) we find the transformation between the coordinate system of the OCT camera and the coordinate system of the robot. We verified the capability of our framework in ex-vivo pig eye experiments and compared the results with a reference method (marker-based). In all experiments, our method showed a small difference from the marker based method, with a mean calibration error of 9.2 µm and 7.0 µm, respectively. Additionally, the noise test shows the robustness of the proposed method.

A Comparative Review of Hand-Eye Calibration Techniques for Vision Guided Robots

“…An example is in critical operations like robot assisted surgery (RAS), where frequent changes in setup and recalibration is an expensive operation that must be dealt with on the fly [104]. This type of application require online calibration [105], where data is continually being captured and used to update the calibration algorithm, rendering the need for data synchronisation on both sources very apparent. One solution to the problem of temporal misalignment is the use of timestamp [106].…”

PCA-Based Visual Servoing Using Optical Coherence Tomography

“…OCT technology [11] has been considered in numerous medical and surgical applications. In [12]- [14], the authors discussed the integration of an OCT device into the surgical workflow for providing to the physician a real-time and highresolution visual feedback of the operative site (observed tissues). A miniaturized OCT in the form of millimeter size probe [15] was also considered for such surgical task.…”

Concept for Markerless 6D Tracking Employing Volumetric Optical Coherence Tomography

“…Evaluating the six degrees of freedom individually would require one to express translations and rotations in a common frame. While hand-eye calibration could be used to relate the robot and OCT-based tracking system [30,38], it would also be limited by the same system components we use in our setup for tracking, and the residual calibration error would affect the evaluation of the tracking approach. Therefore, we consider the relative rotations in the robot frame and the tracking-system frame independently and compare their magnitudes, which include all three rotational degrees of freedom.…”