Mobility Experiments With Microrobots for Minimally Invasive Intraocular Surgery

Purpose.: To investigate microrobots as an assistive tool for minimally invasive intraocular surgery and to demonstrate mobility and controllability inside the living rabbit eye. / Methods.: A system for wireless magnetic control of untethered microrobots was developed. Mobility and controllability of a microrobot are examined in different media, specifically vitreous, balanced salt solution (BSS), and silicone oil. This is demonstrated through ex vivo and in vivo animal experiments. / Results.: The developed electromagnetic system enables precise control of magnetic microrobots over a workspace that covers the posterior eye segment. The system allows for rotation and translation of the microrobot in different media (vitreous, BSS, silicone oil) inside the eye. / Conclusions.: Intravitreal introduction of untethered mobile microrobots can enable sutureless and precise ophthalmic procedures. Ex vivo and in vivo experiments demonstrate that microrobots can be manipulated inside the eye. Potential applications are targeted drug delivery for maculopathies such as AMD, intravenous deployment of anticoagulation agents for retinal vein occlusion (RVO), and mechanical applications, such as manipulation of epiretinal membrane peeling (ERM). The technology has the potential to reduce the invasiveness of ophthalmic surgery and assist in the treatment of a variety of ophthalmic diseases

Miniature fiber-optic force sensor based on low-coherence Fabry-Pérot interferometry for vitreoretinal microsurgery

During vitreoretinal surgery, the surgeon manipulates retinal tissue with tool-to-tissue interaction forces below the human sensory threshold. A force sensor (FS) integrated with conventional surgical tools may significantly improve the surgery outcome by providing tactile feedback to the surgeon. We designed and built a surgical tool integrated with a miniature FS with an outer diameter smaller than 1 mm for vitreoretinal surgery based on low-coherence Fabry–Pérot (FP) interferometry. The force sensing elements are located at the tool tip which is in direct contact with tissue during surgery and the FP cavity length is interrogated by a fiber-optic common-path phase-sensitive optical coherence tomography (OCT) system. We have calibrated the FS's response to axial and lateral forces and conducted experiments to verify that our FS can simultaneously measure both axial and lateral force components

Biomechanical considerations for optimising subretinal injections

\ua9 2024 The AuthorsSubretinal injection is the preferred delivery technique for various novel ocular therapies and is widely used because of its precision and efficient delivery of gene and cell therapies; however, choosing an injection point and defining delivery parameters to target a specified retinal location and area is an inexact science. We provide an overview of the key factors that play important roles during subretinal injections to refine the technique, enhance patient outcomes, and minimise risks. We describe the role of anatomical and physical variables that affect subretinal bleb propagation and shape and their impact on retinal integrity. We highlight the risks associated with subretinal injections and consider strategies to mitigate reflux and retinal trauma. Finally, we explore the emerging field of robotic assistance in improving intraocular manouvrability and precision to facilitate the injection procedure

Biomechanical considerations for optimising subretinal injections.

Subretinal injection is the preferred delivery technique for various novel ocular therapies and is widely used because of its precision and efficient delivery of gene and cell therapies; however, choosing an injection point and defining delivery parameters to target a specified retinal location and area is an inexact science. We provide an overview of the key factors that play important roles during subretinal injections to refine the technique, enhance patient outcomes, and minimise risks. We describe the role of anatomical and physical variables that affect subretinal bleb propagation and shape and their impact on retinal integrity. We highlight the risks associated with subretinal injections and consider strategies to mitigate reflux and retinal trauma. Finally, we explore the emerging field of robotic assistance in improving intraocular manouvrability and precision to facilitate the injection procedure

Design, Manufacturing and Control of an Advanced High-Precision Robotic System for Microsurgery

Microsurgeries like ophthalmic surgery confront many challenges like limited workspace and hand motion, steady hand movements, manipulating delicate thin tissues, and holding the instrument in place for a long time. New developments in robotically-assisted surgery can highly benefits this field and facilitate those complicated surgeries. Robotic eye surgery can save time, reduce surgical complications and inspire more delicate surgical procedures that cannot be done currently by surgeon’s hands. In this thesis work, the requirements for ophthalmic surgeries were studied and based on that a robotic system with 6 DOF is proposed and designed. This robotic system is capable of handling the position and orientation of the surgical instrument with theoretical accuracy of 10 μm. The design features a remote center of motion that defines the point of entry into the eye or patient’s body. The forward and inverse kinematics equations and workspace analysis of the robot is also discussed and presented. Six miniature DC motors with their PID controllers were installed on robot arms in order to run 6 DOF systems. Therefore, the dynamic behavior of a DC motor was studied and modeled and then the position and velocity transfer functions were derived and used to study the behavior of the system and also to manually tune the PID controller. The function of different elements of the control system including encoder, controller modules, Controller Area Network (CAN) and the controller software were discussed as well. The graphical user interface called EPOS Studio and performs as the motion controller is introduced and the way it organizes communications among the elements of the control system was described

遠隔操作型網膜硝子体手術支援システムの構築と眼球モデルおよび内境界膜剥離モデルの作製

学位の種別: 論文博士審査委員会委員 : （主査）東京大学教授 鄭 雄一, 東京大学准教授 加藤 聡, 東京大学准教授 中冨 浩文, 東京大学准教授 藤村 哲也, 東京大学講師 石原 聡一郎University of Tokyo(東京大学

Development of a Novel Handheld Device for Active Compensation of Physiological Tremor

In microsurgery, the human hand imposes certain limitations in accurately positioning the tip of a device such as scalpel. Any errors in the motion of the hand make microsurgical procedures difficult and involuntary motions such as hand tremors can make some procedures significantly difficult to perform. This is particularly true in the case of vitreoretinal microsurgery. The most familiar source of involuntary motion is physiological tremor. Real-time compensation of tremor is, therefore, necessary to assist surgeons to precisely position and manipulate the tool-tip to accurately perform a microsurgery. In this thesis, a novel handheld device (AID) is described for compensation of physiological tremor in the hand. MEMS-based accelerometers and gyroscopes have been used for sensing the motion of the hand in six degrees of freedom (DOF). An augmented state complementary Kalman filter is used to calculate 2 DOF orientation. An adaptive filtering algorithm, band-limited Multiple Fourier linear combiner (BMFLC), is used to calculate the tremor component in the hand in real-time. Ionic Polymer Metallic Composites (IPMCs) have been used as actuators for deflecting the tool-tip to compensate for the tremor

Vitreo-retinal eye surgery robot : sustainable precision

Vitreo-retinal eye surgery encompasses the surgical procedures performed on the vitreous humor and the retina. A procedure typically consists of the removal of the vitreous humor, the peeling of a membrane and/or the repair of a retinal detachment. Vitreo-retinal surgery is performed minimal invasively. Small needle shaped instruments are inserted into the eye. Instruments are manipulated by hand in four degrees of freedom about the insertion point. Two rotations move the instrument tip laterally, in addition to a translation in axial instrument direction and a rotation about its longitudinal axis. The manipulation of the instrument tip, e.g. a gripping motion can be considered as a fifth degree of freedom. While performing vitreo-retinal surgery manually, the surgeon faces various challenges. Typically, delicate micrometer range thick tissue is operated, for which steady hand movements and high accuracy instrument manipulation are required. Lateral instrument movements are inverted by the pivoting insertion point and scaled depending on the instrument insertion depth. A maximum of two instruments can be used simultaneously. There is nearly no perception of surgical forces, since most forces are below the human detection limit. Therefore, the surgeon relies only on visual feedback, obtained via a microscope or endoscope. Both vision systems force the surgeon to work in a static and non ergonomic body posture. Although the surgeon’s proficiency improves throughout his career, hand tremor will become a problem at higher age. Robotically assisted surgery with a master-slave system can assist the surgeon in these challenges. The slave system performs the actual surgery, by means of instrument manipulators which handle the instruments. The surgeon remains in control of the instruments by operating haptic interfaces via a master. Using electronic hardware and control software, the master and slave are connected. Amongst others, advantages as tremor filtering, up-scaled force feedback, down-scaled motions and stabilized instrument positioning will enhance dexterity on surgical tasks. Furthermore, providing the surgeon an ergonomic body posture will prolong the surgeon’s career. This thesis focuses on the design and realization of a high precision slave system for eye surgery. The master-slave system uses a table mounted design, where the system is compact, lightweight, easy to setup and equipped to perform a complete intervention. The slave system consists of two main parts: the instrument manipulators and their passive support system. Requirements are derived from manual eye surgery, conversations with medical specialists and analysis of the human anatomy and vitreo-retinal interventions. The passive support system provides a stiff connection between the instrument manipulator, patient and surgical table. Given the human anatomical diversity, presurgical adjustments can be made to allow the instrument manipulators to be positioned over each eye. Most of the support system is integrated within the patient’s headrest. On either the left or right side, two exchangeable manipulator-support arms can be installed onto the support system, depending on the eye being operated upon. The compact, lightweight and easy to install design, allows for a short setup time and quick removal in case of a complication. The slave system’s surgical reach is optimized to emulate manually performed surgery. For bimanual instrument operation, two instrument manipulators are used. Additional instrument manipulators can be used for non-active tools e.g. an illumination probe or an endoscope. An instrument manipulator allows the same degrees of freedom and a similar reach as manually performed surgery. Instrument forces are measured to supply force feedback to the surgeon via haptic interfaces. The instrument manipulator is designed for high stiffness, is play free and has low friction to allow tissue manipulation with high accuracy. Each instrument manipulator is equipped with an on board instrument change system, by which instruments can be changed in a fast and secure way. A compact design near the instrument allows easy access to the surgical area, leaving room for the microscope and peripheral equipment. The acceptance of a surgical robot for eye surgery mostly relies on equipment safety and reliability. The design of the slave system features various safety measures, e.g. a quick release mechanism for the instrument manipulator and additional locks on the pre-surgical adjustment fixation clamp. Additional safety measures are proposed, like a hard cover over the instrument manipulator and redundant control loops in the controlling FPGA. A method to fixate the patient’s head to the headrest by use of a custom shaped polymer mask is proposed. Two instrument manipulators and their passive support system have been realized so far, and the first experimental results confirm the designed low actuation torque and high precision performance