Background: Since the advent of robotic-assisted surgery, the value of using robotic systems to assist in surgical procedures has been repeatedly demonstrated. However, existing technologies are unable to perform complete, multi-step procedures from start to finish. Many intraocular surgical steps continue to be manually performed.

Methods: An intraocular robotic interventional surgical system (IRISS) capable of performing various intraocular surgical procedures was designed, fabricated, and evaluated. Methods were developed to evaluate the performance of the remote centers of motion (RCMs) using a stereo-camera setup and to assess the accuracy and precision of positioning the tool tip using an optical coherence tomography (OCT) system.

Results: The IRISS can simultaneously manipulate multiple surgical instruments, change between mounted tools using an onboard tool-change mechanism, and visualize the otherwise invisible RCMs to facilitate alignment of the RCM to the surgical incision. The accuracy of positioning the tool tip was measured to be 0.205±0.003 mm. The IRISS was evaluated by trained surgeons in a remote surgical theatre using post-mortem pig eyes and shown to be effective in completing many key steps in a variety of intraocular surgical procedures as well as being capable of performing an entire cataract extraction from start to finish.

Conclusions: The IRISS represents a necessary step towards fully automated intraocular surgery and demonstrated accurate and precise master-slave manipulation for cataract removal and—through visual feedback—retinal vein cannulation.

Intraocular robotic interventional surgical system (IRISS): Mechanical design, evaluation, and master-slave manipulation.

Minimally invasive surgery, including laparoscopic and thoracoscopic procedures, benefits patients in terms of improved postoperative outcomes and short recovery time. The challenges in hand-eye coordination and manipulation dexterity during the aforementioned procedures have inspired an enormous wave of developments on surgical robotic systems to assist keyhole and endoscopic procedures in the past decades. This paper presents a systematic review of the state-of-the-art systems, picturing a detailed landscape of the system configurations, actuation schemes, and control approaches of the existing surgical robotic systems for keyhole and endoscopic procedures. The development challenges and future perspectives are discussed in depth to point out the need for new enabling technologies and inspire future researches.

Review of surgical robotic systems for keyhole and endoscopic procedures: state of the art and perspectives

During retinal microsurgery, surgeons cannot adequately visualize subsurface anatomical structures. In our previous work, a customized B-mode optical coherence tomography (OCT) probe was integrated into an ophthalmic robotic system to provide depth perception. This paper presents new approaches for implementing and achieving real-time feedback and assistive robotic control based on B-mode OCT imaging. The robotic system was comprised of a parallel robot, a micro-injection tool, and a telemanipulation master interface. A method for calibrating the B-mode OCT image scaling and distortion was presented using thin plate splines. Determining the OCT scanning plane relative to the robot base frame is presented through experiments and analyzed for sensitivity. A dual-rate controller using low frequency OCT feedback and high frequency position servoing was presented and tested for accuracy and latency. Three-dimensional assistive telemanipulation virtual fixtures based on microscope and OCT feedback are presented. The experimental evaluation demonstrated following target anatomy and semi-automated micro-injection. These results present the key steps towards achieving an integrated system for OCT feedback control using a miniature intraocular B-mode probe.

Calibration and Integration of B-Mode Optical Coherence Tomography for Assistive Control in Robotic Microsurgery

In this paper, we provide a new generalized kinematic formulation of the Remote Center of Motion (RCM) constraint for serial robotic arms to be useful for implementation in torque-controlled robots. A minimally invasive surgery assisted by a serial robot could be used for inserting a surgical tool through a desired insertion position, i.e. trocar position. The restricted movement caused by the trocar, i.e. the RCM constraint, must be guaranteed by the robotic system in order to avoid injury to the patient. The generalized formulation, presented in this paper, associates the task-space with the RCM constraint coordinates, which are described by the minimum distance between the surgical tool and the trocar position. In order to simultaneously achieve the surgical tool-tip trajectory and the RCM constraint, two control methods are proposed and compared, one using a projection in the null-space, the other by combining both tasks using a task-space augmentation method. Moreover, when additional lower priority tasks have to be implemented in the null-space of the two higher priority tasks, the kinematic formulation simplifies the calculation of the null-space projectors. Furthermore, unlike the previous studies, the formulation represented can be applied not only in a kinematic control but also in a dynamic control approach. Simulations were conducted to validate effectiveness of the proposed formulation, using a planar 4-DOF system as well as the dynamic model of a Kuka LBR 7 iiwa R800 robot arm.

A new kinematic formulation of the RCM constraint for redundant torque-controlled robots

Retinal vein cannulation is a technically demanding surgical procedure where therapeutic agents are injected into the retinal veins to treat occlusions. The clinical feasibility of this approach has been largely limited by the technical challenges associated with performing the procedure. Among the challenges to successful vein cannulation are identifying the moment of venous puncture, achieving cannulation of the micro-vessel, and maintaining cannulation throughout drug delivery. Recent advances in medical robotics and sensing of tool-tissue interaction forces have the potential to address each of these challenges as well as to prevent tissue trauma, minimize complications, diminish surgeon effort, and ultimately promote successful retinal vein cannulation. In this paper, we develop an assistive system combining a handheld micromanipulator, called “Micron”, with a force-sensing microneedle. Using this system, we examine two distinct methods of precisely detecting the instant of venous puncture. This is based on measured tool-tissue interaction forces and also the tracked position of the needle tip. In addition to the existing tremor canceling function of Micron, a new control method is implemented to actively compensate unintended movements of the operator, and to keep the cannulation device securely inside the vein following cannulation. To demonstrate the capabilities and performance of our uniquely upgraded system, we present a multi-user artificial phantom study with subjects from three different surgical skill levels. Results show that our puncture detection algorithm, when combined with the active positive holding feature enables sustained cannulation which is most evident in smaller veins. Notable is that the active holding function significantly attenuates tool motion in the vein, thereby reduces the trauma during cannulation.

Towards Robot-Assisted Retinal Vein Cannulation: A Motorized Force-Sensing Microneedle Integrated with a Handheld Micromanipulator †.

This paper presents the virtual fixture control methods for a hybrid parallel-serial micromanipulator, which is designed for assisting ophthalmic surgeons. Virtual fixtures are features of surgical robotic setups to improve quality of the surgery and reduces the operation risk. In the domain of ophthalmic surgery lack of virtual fixtures in manual operations has limited, and sometimes even blocked, the treatment options. The contribution of this paper is concept analysis and implementation of flexible virtual fixture for the novel hybrid parallel-serial mechanism and experimentally evaluation of this concept. The virtual fixture using this mechanism enables the user to adjust them even during the procedure. Pivoting around a Remote Center of Motion (RCM), which in retinal surgery is the incision point, is the most famous virtual fixture of ophthalmic surgery. Autonomous RCM adjustment for Vitreo-Retinal surgery, implying retinal reachability study, is the secondary contribution which is investigated in this paper.

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P. Gschirr

Papers

Virtual fixture control of a hybrid parallel-serial robot for assisting ophthalmic surgery: An experimental study