Robotising vitreoretinal surgeries

The use of robotic surgery in ophthalmology has been shown to offer many potential advantages to current surgical techniques. Vitreoretinal surgery requires complex manoeuvres and high precision, and this is an area that exceeds manual human dexterity in certain surgical situations. With the advent of advanced therapeutics such as subretinal gene therapy, precise delivery and minimising trauma is imperative to optimize outcomes. There are multiple robotic systems in place for ophthalmology in pre-clinical and clinical use, and the Preceyes Robotic Surgical System (Preceyes BV) has also gained the CE mark and is commercially available for use. Recent in-vivo and in-human surgeries have been performed successfully with robotics systems. This includes membrane peeling, subretinal injections of therapeutics, and retinal vein cannulation. There is huge potential to integrate robotic surgery into mainstream clinical practice. In this review, we summarize the existing systems, and clinical implementation so far, and highlight the future clinical applications for robotic surgery in vitreo-retina.

Robotics and optical coherence tomography: current works and future perspectives [Invited]

Optical coherence tomography (OCT) is an interferometric technique for micron-level imaging in biological and non-biological contexts. As a non-invasive, non-ionizing, and video-rate imaging modality, OCT is widely used in biomedical and clinical applications, especially ophthalmology, where it functions in many roles, including tissue mapping, disease diagnosis, and intrasurgical visualization. In recent years, the rapid growth of medical robotics has led to new applications for OCT, primarily for 3D free-space scanning, volumetric perception, and novel optical designs for specialized medical applications. This review paper surveys these recent developments at the intersection of OCT and robotics and organizes them by degree of integration and application, with a focus on biomedical and clinical topics. We conclude with perspectives on how these recent innovations may lead to further advances in imaging and medical technology.

Magnetic Soft Catheter Robot System for Minimally Invasive Treatments of Articular Cartilage Defects

Articular cartilage defects are among the most common orthopedic diseases, which seriously affect patients' health and daily activities, without prompt treatment. The repair biocarrier-based treatment has shown great promise. Total joint injection and open surgery are two main methods to deliver functional repair biocarriers into the knee joint. However, the exhibited drawbacks of these methods hinder their utility. The repair effect of total joint injection is unstable due to the low targeting rate of the repair biocarriers, whereas open surgery causes serious trauma to patients, thereby prolonging the postoperative healing time. In this study, we develop a magnetic soft catheter robot (MSCR) system to perform precise in situ repair of articular cartilage defects with minimal incision. The MSCR processes a size of millimeters, allowing it to enter the joint cavity through a tiny skin incision to reduce postoperative trauma. Meanwhile, a hybrid control strategy combining neural network and visual servo is applied to sequentially complete the coarse and fine positioning of the MSCR on the cartilage defect sites. After reaching the target, the photosensitive hydrogel is injected and anchored into the defect sites through the MSCR, ultimately completing the in situ cartilage repair. The in vitro and ex vivo experiments were conducted on a 3D printed human femur model and an isolated porcine femur, respectively, to demonstrate the potential of our system for the articular cartilage repair.

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.

Medical Microrobots

Scientists around the world have long aimed to produce miniature robots that can be controlled inside the human body to aid doctors in identifying and treating diseases. Such microrobots hold the potential to access hard-to-reach areas of the body through the natural lumina. Wireless access has the potential to overcome drawbacks of systemic therapy, as well as to enable completely new minimally invasive procedures. The aim of this review is fourfold: first, to provide a collection of valuable anatomical and physiological information on the target working environments together with engineering tools for the design of medical microrobots; second, to provide a comprehensive updated survey of the technological state of the art in relevant classes of medical microrobots; third, to analyze currently available tracking and closed-loop control strategies compatible with the in-body environment; and fourth, to explore the challenges still in place, to steer and inspire future research.

Artificial Intelligence, Digital Imaging, and Robotics Technologies for Surgical Vitreoretinal Diseases

OBJECTIVE

To review recent technological advancement in imaging, surgical visualization, robotics technology, and the use of artificial intelligence in surgical vitreoretinal (VR) diseases.

BACKGROUND

Technological advancements in imaging enhance both preoperative and intraoperative management of surgical VR diseases. Widefield imaging in fundal photography and OCT can improve assessment of peripheral retinal disorders such as retinal detachments, degeneration, and tumors. OCT angiography provides a rapid and noninvasive imaging of the retinal and choroidal vasculature. Surgical visualization has also improved with intraoperative OCT providing a detailed real-time assessment of retinal layers to guide surgical decisions. Heads-up display and head-mounted display utilize 3-dimensional technology to provide surgeons with enhanced visual guidance and improved ergonomics during surgery. Intraocular robotics technology allows for greater surgical precision and is shown to be useful in retinal vein cannulation and subretinal drug delivery. In addition, deep learning techniques leverage on diverse data including widefield retinal photography and OCT for better predictive accuracy in classification, segmentation, and prognostication of many surgical VR diseases.

CONCLUSION

This review article summarized the latest updates in these areas and highlights the importance of continuous innovation and improvement in technology within the field. These advancements have the potential to reshape management of surgical VR diseases in the very near future and to ultimately improve patient care.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Evaluation of an Active Disturbance Rejection Controller for Ophthalmic Robots with Piezo-Driven Injector

Retinal vein cannulation involves puncturing an occluded vessel on the micron scale. Even single millinewton force can cause permanent damage. An ophthalmic robot with a piezo-driven injector is precise enough to perform this delicate procedure, but the uncertain viscoelastic characteristics of the vessel make it difficult to achieve the desired contact force without harming the retina. The paper utilizes a viscoelastic contact model to explain the mechanical characteristics of retinal blood vessels to address this issue. The uncertainty in the viscoelastic properties is considered an internal disturbance of the contact model, and an active disturbance rejection controller is then proposed to precisely control the contact force. The experimental results show that this method can precisely adjust the contact force at the millinewton level even when the viscoelastic parameters vary significantly (up to 403.8%). The root mean square (RMS) and maximum value of steady-state error are 0.32 mN and 0.41 mN. The response time is below 2.51 s with no obvious overshoot.

A Novel Electromagnetic Driving System for 5-DOF Manipulation in Intraocular Microsurgery

This work presents a novel electromagnetic driving system that consists of eight optimized electromagnets arranged in an optimal configuration and employs a control framework based on an active disturbance rejection controller (ADRC) and virtual boundary. The optimal system configuration enhances the system's compatibility with other ophthalmic surgical instruments, while also improving its capacity to generate magnetic force in the vertical direction. Besides, the optimal electromagnet parameters provide a superior comprehensive performance on magnetic field generation capacity and thermal power. Hence, the presented design achieves a stronger capacity for sustained work. Furthermore, the ADRC controller effectively monitors and further compensates the total disturbance as well as gravity to enhance the system's robustness. Meanwhile, the implementation of virtual boundaries substantially enhances interactive security via collision avoidance. The magnetic and thermal performance tests have been performed on the electromagnet to verify the design optimization. The proposed electromagnet can generate a superior magnetic field of 2.071 mT at a distance of 65 mm with an applied current of 1 A. Moreover, it demonstrates minimal temperature elevation from room temperature (25 °C) to 46 °C through natural heat dissipation in 3 h, thereby effectively supporting prolonged magnetic manipulation of intraocular microsurgery. Furthermore, trajectory tracking experiments with disturbances have been performed in a liquid environment similar to the practical ophthalmic surgery scenarios, to verify the robustness and security of the presented control framework. The maximum root mean square (RMS) error of performance tests in different operation modes remains 35.8 μm, providing stable support for intraocular microsurgery.

Analysis on key parameters in subretinal injection facilitating a predictable and automated robot-assisted treatment in gene therapy

BACKGROUND

Subretinal injection (SRI) has become an important surgical method for treating vitreoretinal diseases. Nevertheless, the optimisation of bleb formation in SRI, for the attainment of desired therapeutic outcomes, still requires further investigation.

METHODS

This study analysed the influence of surgical parameters on SRI using a robotic setup. The surgical procedure was automated using visual guidance. A predictive model for bleb formation was established through regression analysis. To validate the model, we compared the clinical data's target area with the simulated SRI's actual area using parameters determined by the predictive model.

RESULTS

The insertion angle dominated the eccentricity and area of the bleb. The injection speed dominated the axial angle. Automated SRI increased success rate and produced predictable outcomes.

CONCLUSIONS

We could provide accurate SRI on phantom models by adjusting surgical parameters based on the patient's clinical information. Automatic robot-assisted SRI is a promising surgical technique with highly predictable results.

Artificial Intelligence in Ophthalmic Surgery: Current Applications and Expectations

Artificial Intelligence (AI) has found rapidly growing applications in ophthalmology, achieving robust recognition and classification in most kind of ocular diseases. Ophthalmic surgery is one of the most delicate microsurgery, requiring high fineness and stability of surgeons. The massive demand of the AI assist ophthalmic surgery will constitute an important factor in boosting accelerate precision medicine. In clinical practice, it is instrumental to update and review the considerable evidence of the current AI technologies utilized in the investigation of ophthalmic surgery involved in both the progression and innovation of precision medicine. Bibliographic databases including PubMed and Google Scholar were searched using keywords such as "ophthalmic surgery", "surgical selection", "candidate screening", and "robot-assisted surgery" to find articles about AI technology published from 2018 to 2023. In addition to the Editorials and letters to the editor, all types of approaches are considered. In this paper, we will provide an up-to-date review of artificial intelligence in eye surgery, with a specific focus on its application to candidate screening, surgery selection, postoperative prediction, and real-time intraoperative guidance.

Simultaneous Online Registration-Independent Stiffness Identification and Tip Localization of Surgical Instruments in Robot-assisted Eye Surgery

Notable challenges during retinal surgery lend themselves to robotic assistance which has proven beneficial in providing a safe steady-hand manipulation. Efficient assistance from the robots heavily relies on accurate sensing of surgery states (e.g. instrument tip localization and tool-to-tissue interaction forces). Many of the existing tool tip localization methods require preoperative frame registrations or instrument calibrations. In this study using an iterative approach and by combining vision and force-based methods, we develop calibration- and registration-independent (RI) algorithms to provide online estimates of instrument stiffness (least squares and adaptive). The estimations are then combined with a state-space model based on the forward kinematics (FWK) of the Steady-Hand Eye Robot (SHER) and Fiber Brag Grating (FBG) sensor measurements. This is accomplished using a Kalman Filtering (KF) approach to improve the deflected instrument tip position estimations during robot-assisted eye surgery. The conducted experiments demonstrate that when the online RI stiffness estimations are used, the instrument tip localization results surpass those obtained from pre-operative offline calibrations for stiffness.

Magnetic Soft Helical Manipulators with Local Dipole Interactions for Flexibility and Forces

Magnetic continuum manipulators (MCMs) are a class of continuum robots that can be actuated without direct contact by an external magnetic field. MCMs operating in confined workspaces, such as those targeting medical applications, require flexible magnetic structures that contain combinations of magnetic components and polymers to navigate long and tortuous paths. In cylindrical MCM designs, a significant trade-off exists between magnetic moment and bending flexibility as the ratio between length and diameter decreases. In this study, we propose a new MCM design framework that enables increasing diameter without compromising on flexibility and magnetic moment. Magnetic soft composite helices constitute bending regions of the MCM and are separated by permanent ring magnets. Local dipole interactions between the permanent magnets can reduce bending stiffness, depending on their size and spacing. For the particular segment geometry presented herein, the local dipole interactions result in a 31% increase in angular deflection of composite helices inside an external magnetic field, compared to helices without local interactions. In addition, we demonstrate fabrication, maneuverability, and example applications of a multisegment MCM in a phantom of the abdominal aorta, such as passing contrast dye and guidewires.

Robotic Integration in the Field of Opthalmology and Its Prospects in India

In this paper, an overview of the integration of robotic techniques into surgical fields of ophthalmology is described and the details about the latest advancements and future potentials associated with it are presented. The eye is a small, enclosed space that does not tolerate the misplacement of instruments that general surgery can tolerate. As the retina doesn't regenerate, it is of paramount importance to avoid injury. Furthermore, there are additional limitations of unassisted human hands in terms of dexterity, tremor, and precision in positioning instruments in the eye. Robotics has become a promising solution to these human challenges. The emergence of robotic technology into the domain of rapidly advancing micro-invasive surgery has reduced discomfort in patients and enhanced safety, capabilities, and outcomes. With the arrival of the Femtosecond laser system for robotic cataract surgery in several hospitals in India, the paradigm of robotic surgery has shifted as people started to accept and apply it. Although there is still much to learn in this area, there is growing interest in creating gadgets that perform complete surgical procedures. The fundamental objective of these surgeries would be to increase speed and efficiency without compromising the capacity to increase precision. Major criteria include an acceptable range of motion, the capacity to switch instruments mid-surgery, and simultaneous manipulation of the surgical instrument. Robotic surgery is an already well-established technological advancement employed across the globe by leading surgeons in their fields but its curve in ophthalmology is still under supervision. Just like every other advance, robotics has its own set of disadvantages including but not limited to the costs, limited availability, and long learning curve. Nonetheless, this paper doesn't intend to promote the replacement of surgeons with technology, it's intended to get aware of the utilities of technology to improve care and deliver personal compassionate care. This quest is for the idea of robotics in the ocular field and improvisation of the field.

Degradable silk-based soft actuators with magnetic responsiveness

Soft actuators with stimuli-responsiveness have great potential in biomedical applications such as drug delivery and minimally invasive surgery. In this study, protein-based soft actuators with magnetic actuation are fabricated using naturally occurring silk proteins and synthesized Fe₃O₄ magnetic nanoparticles (NPs). Briefly, magnetic silk films are first prepared by solution casting of a mixture containing silk proteins, synthesized Fe₃O₄ NPs, and glycerol. The molecular structures of the magnetic silk films are characterized by FTIR spectroscopy, which show that the β-sheet content in the films is about 20%. The mechanical tests show that the magnetic silk films can be stretched to over 200% under wet conditions and Young's modulus is estimated to be 4.89 ± 0.69 MPa, matching the stiffness of soft tissues. Furthermore, the enzymatic degradability, good biocompatibility, and in vivo X-ray visibility of the films are demonstrated by the in vitro enzymatic degradation test, in vivo biocompatibility test, and micro-CT imaging, respectively. Degradable silk-based soft actuators with magnetic responsiveness are successfully prepared by thermal forming or plastic molding of the magnetic silk films. The fabricated soft actuators can be actuated and move with precise locomotive gaits in solutions using a magnet. In addition, the retention of the soft actuators and localized drug delivery in gastrointestinal tracts by attaching a magnet to the abdominal skin are demonstrated using model systems. The degradable silk-based soft actuators provide many opportunities for improving current therapeutic strategies in biomedicine.

Robotic Assistance for Intraocular Microsurgery: Challenges and Perspectives

Intraocular surgery, one of the most challenging discipline of microsurgery, requires sensory and motor skills at the limits of human physiological capabilities combined with tremendously difficult requirements for accuracy and steadiness. Nowadays, robotics combined with advanced imaging has opened conspicuous and significant directions in advancing the field of intraocular microsurgery. Having patient treatment with greater safety and efficiency as the final goal, similar to other medical applications, robotics has a real potential to fundamentally change microsurgery by combining human strengths with computer and sensor-based technology in an information-driven environment. Still in its early stages, robotic assistance for intraocular microsurgery has been accepted with precaution in the operating room and successfully tested in a limited number of clinical trials. However, owing to its demonstrated capabilities including hand tremor reduction, haptic feedback, steadiness, enhanced dexterity, micrometer-scale accuracy, and others, microsurgery robotics has evolved as a very promising trend in advancing retinal surgery. This paper will analyze the advances in retinal robotic microsurgery, its current drawbacks and limitations, as well as the possible new directions to expand retinal microsurgery to techniques currently beyond human boundaries or infeasible without robotics.

Robotics in Vitreo-Retinal Surgery

PURPOSE

Modern vitreo-retinal surgery has scaled new frontiers with the advent of better instrumentation. However, physiological tremors, intraocular dexterity and difficulty in visualization hamper minimally invasive retinal surgery. Robotics has the potential to overcome these limitations and improve surgical outcomes. This review aims to provide a comprehensive summary of the advances made in the field of robotics in vitreo-retinal surgery.

METHODS

This review included 30 studies comprising randomized control trials, nonrandomized comparative studies and systematic reviews on the application of robotics in vitreo-retinal surgery.

RESULTS

Robotic systems presently available in vitreo-retinal surgery can be broadly classified based on the extent of automation into five categories: robot-assisted, co-manipulated, tele-operated, partially/fully automated and magnetically controlled devices. Key features of individual devices are highlighted in this review. Robotic assistance in vitreo-retinal surgery can maximize performance for routine procedures, enable high-precision procedures such as targeted gene therapy and retinal vein cannulation, improve ergonomics, and revolutionize tele-surgery. Cost limitations and compatibility with available surgical systems are the barriers in implementation of robotics in retinal microsurgery.

CONCLUSION

This review provides a concise summary of the available robotic systems in vitreo-retinal surgery, advantages over conventional systems, current applications and future implications. Robotics is a rapidly evolving field, which holds great promise in the future of vitreo-retinal surgery.

Data-Driven Modelling and Control for Robot Needle Insertion in Deep Anterior Lamellar Keratoplasty

Deep anterior lamellar keratoplasty (DALK) is a technique for cornea transplantation which is associated with reduced patient morbidity. DALK has been explored as a potential application of robot microsurgery because the small scales, fine control requirements, and difficulty of visualization make it very challenging for human surgeons to perform. We address the problem of modelling the small scale interactions between the surgical tool and the cornea tissue to improve the accuracy of needle insertion, since accurate placement within 5% of target depth has been associated with more reliable clinical outcomes. We develop a data-driven autoregressive dynamic model of the tool-tissue interaction and a model predictive controller to guide robot needle insertion. In an ex vivo model, our controller significantly improves the accuracy of needle positioning by more than 40% compared to prior methods.

Magnetic Soft Materials and Robots

In conventional classification, soft robots feature mechanical compliance as the main distinguishing factor from traditional robots made of rigid materials. Recent advances in functional soft materials have facilitated the emergence of a new class of soft robots capable of tether-free actuation in response to external stimuli such as heat, light, solvent, or electric or magnetic field. Among the various types of stimuli-responsive materials, magnetic soft materials have shown remarkable progress in their design and fabrication, leading to the development of magnetic soft robots with unique advantages and potential for many important applications. However, the field of magnetic soft robots is still in its infancy and requires further advancements in terms of design principles, fabrication methods, control mechanisms, and sensing modalities. Successful future development of magnetic soft robots would require a comprehensive understanding of the fundamental principle of magnetic actuation, as well as the physical properties and behavior of magnetic soft materials. In this review, we discuss recent progress in the design and fabrication, modeling and simulation, and actuation and control of magnetic soft materials and robots. We then give a set of design guidelines for optimal actuation performance of magnetic soft materials. Lastly, we summarize potential biomedical applications of magnetic soft robots and provide our perspectives on next-generation magnetic soft robots.

Development and ex-vivo validation of 36G polyimide cannulas integrating a guiding miniaturized OCT probe for robotic assisted subretinal injections

We introduced and validated a method to encase guiding optical coherence tomography (OCT) probes into clinically relevant 36G polyimide subretinal injection (SI) cannulas. Modified SI cannulas presented consistent flow capacity and tolerated the typical mechanical stress encountered in clinical use without significant loss of sensitivity. We also developed an approach that uses a micromanipulator, modified SI cannulas, and an intuitive graphical user interface to enable precise SI. We tested the system using ex-vivo porcine eyes and we found a high SI success ratio 95.0% (95% CI: 83.1-99.4). We also found that 75% of the injected volume ends up at the subretinal space. Finally, we showed that this approach can be applied to transform commercial 40G SI cannulas to guided cannulas. The modified cannulas and guiding approach can enable precise and reproducible SI of novel gene and cell therapies targeting retinal diseases.

Adaptive Control Improves Sclera Force Safety in Robot-Assisted Eye Surgery: A Clinical Study

The integration of robotics into retinal microsurgery leads to a reduction in surgeon perception of tool-to-tissue interaction forces. This blunting of human tactile sensory input, which is due to the inflexible mass and large inertia of the robotic arm as compared to the milli-Newton scale of the interaction forces and fragile tissues during ophthalmic surgery, identifies a potential iatrogenic risk during robotic eye surgery. In this paper, we aim to evaluate two variants of an adaptive force control scheme implemented on the Steady-Hand Eye Robot (SHER) that are intended to mitigate the risk of unsafe scleral forces. The present study enrolled ten retina fellows and ophthalmology residents into a simulated procedure, which simply asked the trainees to follow retinal vessels in a model retina surgery environment. For this purpose, we have developed a force-sensing (equipped with Fiber Bragg Grating (FBG)) instrument to attach to the robot. A piezo-actuated linear stage for creating random lateral motions to the eyeball phantom has been provided to simulate disturbances during surgery. The SHER and all of its dependencies were set up in an operating room in the Wilmer Eye Institute at the Johns Hopkins Hospital. The clinicians conducted robot-assisted experiments with the adaptive controls incorporated as well as freehand manipulations. The results indicate that the Adaptive Norm Control (ANC) method, is able to maintain scleral forces at predetermined safe levels better than even freehand manipulations. Novice clinicians in robot training however, subjectively preferred freehand maneuvers over robotic manipulations. Clinician preferences once highly skilled with the robot is not assessed in this study.

Force and Velocity Based Puncture Detection in Robot Assisted Retinal Vein Cannulation: in-vivo Study

OBJECTIVE

Retinal vein cannulation is a technically demanding surgical procedure and its feasibility may rely on using advanced surgical robots equipped with force-sensing microneedles. Reliable detection of the moment of venous puncture is important, to either alert or prevent the clinician from double puncturing the vessel and damaging the retinal surface beneath. This paper reports the first in-vivo retinal vein cannulation trial on rabbit eyes, using sensorized metal needles, and investigates puncture detection.

METHODS

We utilized total of four indices including two previously demonstrated ones and two new indices, based on the velocity and force of the needle tip and the correlation between the needle-tissue and tool-sclera interaction forces. We also studied the effect of detection timespan on the performance of detecting actual punctures.

RESULTS

The new indices, when used in conjunction with the previous algorithm, improved the detection rate form 75% to 92%, but slightly increased the number of false detections from 37 to 43. Increasing the detection window improved the detection performance, at the cost of adding to the delay.

CONCLUSION

The current algorithm can supplement the surgeons visual feedback and surgical judgment. To achieve automatic puncture detection, more measurements and further analysis are required. Subsequent in-vivo studies in other animals, such as pigs with their more human like eye anatomy, are required, before clinical trials.

SIGNIFICANCE

The study provides promising results and the criteria developed may serve as guidelines for further investigation into puncture detection in in-vivo retinal vein cannulation.

A Submillimeter Continuous Variable Stiffness Catheter for Compliance Control

Minimally invasive robotic surgery often requires functional tools that can change their compliance to adapt to the environment and surgical needs. This paper proposes a submillimeter continuous variable stiffness catheter equipped with a phase-change alloy that has a high stiffness variation in its different states, allowing for rapid compliance control. Variable stiffness is achieved through a variable phase boundary in the alloy due to a controlled radial temperature gradient. This catheter can be safely navigated in its soft state and rigidified to the required stiffness during operation to apply a desired force at the tip. The maximal contact force that the catheter applies to tissue can be continuously modified by a factor of 400 (≈20 mN-8 N). The catheter is equipped with a magnet and a micro-gripper to perform a fully robotic ophthalmic minimally invasive surgery on an eye phantom by means of an electromagnetic navigation system.

Evolutionary design of magnetic soft continuum robots

Worldwide cardiovascular diseases such as stroke and heart disease are the leading cause of mortality. While guidewire/catheter-based minimally invasive surgery is used to treat a variety of cardiovascular disorders, existing passive guidewires and catheters suffer from several limitations such as low steerability and vessel access through complex geometry of vasculatures and imaging-related accumulation of radiation to both patients and operating surgeons. To address these limitations, magnetic soft continuum robots (MSCRs) in the form of magnetic field-controllable elastomeric fibers have recently demonstrated enhanced steerability under remotely applied magnetic fields. While the steerability of an MSCR largely relies on its workspace-the set of attainable points by its end effector-existing MSCRs based on embedding permanent magnets or uniformly dispersing magnetic particles in polymer matrices still cannot give optimal workspaces. The design and optimization of MSCRs have been challenging because of the lack of efficient tools. Here, we report a systematic set of model-based evolutionary design, fabrication, and experimental validation of an MSCR with a counterintuitive nonuniform distribution of magnetic particles to achieve an unprecedented workspace. The proposed MSCR design is enabled by integrating a theoretical model and the genetic algorithm. The current work not only achieves the optimal workspace for MSCRs but also provides a powerful tool for the efficient design and optimization of future magnetic soft robots and actuators.

A Review of Robotic and OCT-Aided Systems for Vitreoretinal Surgery

The introduction of the intraocular vitrectomy instrument by Machemer et al. has led to remarkable advancements in vitreoretinal surgery enabling the limitations of human physiologic capabilities to be reached. To overcome the barriers of perception, tremor, and dexterity, robotic technologies have been investigated with current advancements nearing the feasibility for clinical use. There are four categories of robotic systems that have emerged through the research: (1) handheld instruments with intrinsic robotic assistance, (2) hand-on-hand robotic systems, (3) teleoperated robotic systems, and (4) magnetic guidance robots. This review covers the improvements and the remaining needs for safe, cost-effective clinical deployment of robotic systems in vitreoretinal surgery.

Auditory Feedback Effectiveness for Enabling Safe Sclera Force in Robot-Assisted Vitreoretinal Surgery: a Multi-User Study

Robot-assisted retinal surgery has become increasingly prevalent in recent years in part due to the potential for robots to help surgeons improve the safety of an immensely delicate and difficult set of tasks. The integration of robots into retinal surgery has resulted in diminished surgeon perception of tool-to-tissue interaction forces due to robot's stiffness. The tactile perception of these interaction forces (sclera force) has long been a crucial source of feedback for surgeons who rely on them to guide surgical maneuvers and to prevent damaging forces from being applied to the eye. This problem is exacerbated when there are unfavorable sclera forces originating from patient movements (dynamic eyeball manipulation) during surgery which may cause the sclera forces to increase even drastically. In this study we aim at evaluating the efficacy of providing warning auditory feedback based on the level of sclera force measured by force sensing instruments. The intent is to enhance safety during dynamic eye manipulations in robot-assisted retinal surgery. The disturbances caused by lateral movement of patient's head are simulated using a piezo-actuated linear stage. The Johns Hopkins Steady-Hand Eye Robot (SHER), is then used in a multi-user experiment. Twelve participants are asked to perform a mock retinal surgery by following painted vessels inside an eye phantom using a force sensing instrument while auditory feedback is provided. The results indicate that the users are able to handle the eye motion disturbances while maintaining the sclera forces within safe boundaries when audio feedback is provided.