Robot-Assisted Vitreoretinal Surgery

Customization of a passive surgical support robot to specifications for ophthalmic surgery and preliminary evaluation

PURPOSE

To customize a passive surgery support robot for ophthalmic surgery and preliminarily evaluate its performance.

STUDY DESIGN

Prospective observational study.

METHODS

The range of motion of the arm was analyzed during ophthalmic surgery and, based on this analysis, a commercially available passive robot was customized for surgical support for ophthalmic surgery; following which a prototype robot was constructed. To examine the effects on the brachial muscle during surgical operations with and without the prototype robot, surface electromyograms of the biceps and triceps were analyzed after performing continuous curvilinear capsulorrhexis (CCC) and suturing the sclerocorneal wound in a cataract surgery simulation. Six surgeons performed cataract surgery, and the degree of arm stability and muscle fatigue during surgery were evaluated using a visual analog scale.

RESULTS

During surgery, the prototype robot enabled fixation of the elbow and wrist at any position within the surgeon's range of motion, expanding the range of motion of the hand and fingers and stabilizing operability. Surface electromyography showed a significant decrease in the mean amplitude value of the biceps brachii during both CCC and suturing (p < 0.0001). No significant difference was observed in the triceps brachii. The arm stability and muscle fatigue were improved by 83.3% on the visual analog scale with the prototype robot compared with that without protpotype robot.

CONCLUSION

The use of a passive prototype robot may improve arm stability and reduce muscle fatigue during ophthalmic surgery.

Microsurgery Robots: Applications, Design, and Development

Microsurgical techniques have been widely utilized in various surgical specialties, such as ophthalmology, neurosurgery, and otolaryngology, which require intricate and precise surgical tool manipulation on a small scale. In microsurgery, operations on delicate vessels or tissues require high standards in surgeons' skills. This exceptionally high requirement in skills leads to a steep learning curve and lengthy training before the surgeons can perform microsurgical procedures with quality outcomes. The microsurgery robot (MSR), which can improve surgeons' operation skills through various functions, has received extensive research attention in the past three decades. There have been many review papers summarizing the research on MSR for specific surgical specialties. However, an in-depth review of the relevant technologies used in MSR systems is limited in the literature. This review details the technical challenges in microsurgery, and systematically summarizes the key technologies in MSR with a developmental perspective from the basic structural mechanism design, to the perception and human-machine interaction methods, and further to the ability in achieving a certain level of autonomy. By presenting and comparing the methods and technologies in this cutting-edge research, this paper aims to provide readers with a comprehensive understanding of the current state of MSR research and identify potential directions for future development in MSR.

Feature Tracking and Segmentation in Real Time via Deep Learning in Vitreoretinal Surgery: A Platform for Artificial Intelligence-Mediated Surgical Guidance

PURPOSE

This study investigated whether a deep-learning neural network can detect and segment surgical instrumentation and relevant tissue boundaries and landmarks within the retina using imaging acquired from a surgical microscope in real time, with the goal of providing image-guided vitreoretinal (VR) microsurgery.

DESIGN

Retrospective analysis via a prospective, single-center study.

PARTICIPANTS

One hundred and one patients undergoing VR surgery, inclusive of core vitrectomy, membrane peeling, and endolaser application, in a university-based ophthalmology department between July 1, 2020, and September 1, 2021.

METHODS

A dataset composed of 606 surgical image frames was annotated by 3 VR surgeons. Annotation consisted of identifying the location and area of the following features, when present in-frame: vitrector-, forceps-, and endolaser tooltips, optic disc, fovea, retinal tears, retinal detachment, fibrovascular proliferation, endolaser spots, area where endolaser was applied, and macular hole. An instance segmentation fully convolutional neural network (YOLACT++) was adapted and trained, and fivefold cross-validation was employed to generate metrics for accuracy.

MAIN OUTCOME MEASURES

Area under the precision-recall curve (AUPR) for the detection of elements tracked and segmented in the final test dataset; the frames per second (FPS) for the assessment of suitability for real-time performance of the model.

RESULTS

The platform detected and classified the vitrector tooltip with a mean AUPR of 0.972 ± 0.009. The segmentation of target tissues, such as the optic disc, fovea, and macular hole reached mean AUPR values of 0.928 ± 0.013, 0.844 ± 0.039, and 0.916 ± 0.021, respectively. The postprocessed image was rendered at a full high-definition resolution of 1920 × 1080 pixels at 38.77 ± 1.52 FPS when attached to a surgical visualization system, reaching up to 87.44 ± 3.8 FPS.

CONCLUSIONS

Neural Networks can localize, classify, and segment tissues and instruments during VR procedures in real time. We propose a framework for developing surgical guidance and assessment platform that may guide surgical decision-making and help in formulating tools for systematic analyses of VR surgery. Potential applications include collision avoidance to prevent unintended instrument-tissue interactions and the extraction of spatial localization and movement of surgical instruments for surgical data science research.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Robotics and cybersurgery in ophthalmology: a current perspective

Ophthalmology is one of the most enriched fields, allowing the domain of artificial intelligence to be part of its point of interest in scientific research. The requirement of specialized microscopes and visualization systems presents a challenge to adapting robotics in ocular surgery. Cyber-surgery has been used in other surgical specialties aided by Da Vinci robotic system. This study focuses on the current perspective of using robotics and cyber-surgery in ophthalmology and highlights factors limiting their progression. A review of literature was performed with the aid of Google Scholar, Pubmed, CINAHL, MEDLINE (N.H.S. Evidence), Cochrane, AMed, EMBASE, PsychINFO, SCOPUS, and Web of Science. Keywords: Cybersurgery, Telesurgery, ophthalmology robotics, Da Vinci robotic system, artificial intelligence in ophthalmology, training on robotic surgery, ethics of the use of robots in medicine, legal aspects, and economics of cybersurgery and robotics. 150 abstracts were reviewed for inclusion, and 68 articles focusing on ophthalmology were included for full-text review. Da Vinci Surgical System has been used to perform a pterygium repair in humans and was successful in ex vivo corneal, strabismus, amniotic membrane, and cataract surgery. Gamma Knife enabled effective treatment of uveal melanoma. Robotics used in ophthalmology were: Da Vinci Surgical System, Intraocular Robotic Interventional Surgical System (IRISS), Johns Hopkins Steady-Hand Eye Robot and smart instruments, and Preceyes' B.V. Cybersurgery is an alternative to overcome distance and the shortage of surgeons. However, cost, availability, legislation, and ethics are factors limiting the progression of these fields. Robotic and cybersurgery in ophthalmology are still in their niche. Cost-effective studies are needed to overcome the delay. Technologies, such as 5G and Tactile Internet, are required to help reduce resource scheduling problems in cybersurgery. In addition, prototype development and the integration of artificial intelligence applications could further enhance the safety and precision of ocular surgery.

Future in precise surgery: Fluorescence-guided surgery using EVs derived fluorescence contrast agent

Surgery is the only cure for many solid tumors, but positive resection margins, damage to vital nerves, vessels and organs during surgery, and the range and extent of lymph node dissection are significant concerns which hinder the development of surgery. The emergence of fluorescence-guided surgery (FGS) means a farewell to the era when surgeons relied only on visual and tactile feedback, and it gives surgeons another eye to distinguish tumors from normal tissues for precise resection and helps to find a balance between complete tumor lesions removal and maximal organ function conservation. However, the existing synthetic fluorescence contrast agent has flaws in safety, specificity and biocompatibility to various extents. Extracellular vesicles (EVs) are a group of heterogeneous types of cell-derived membranous structures present in all biological fluids. EVs, especially engineered targeting EVs, play an increasingly important role in drug delivery because of their good biocompatibility, validated safety and targeting ability. Nevertheless, few studies have employed EVs loaded with fluorophores to construct fluorescence contrast agents and used them in FGS. Here, we systematically reviewed the current state of knowledge regarding FGS, fundamental characteristics of EVs, and the development of engineered targeting EVs, and put forward a novel strategy and procedures to produce EVs-based fluorescence contrast agent used in fluorescence-guided surgery.

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.

First-in-Human Robot-Assisted Subretinal Drug Delivery Under Local Anesthesia

PURPOSE

To report the results of a first-in-human study using a robotic device to assist subretinal drug delivery in patients undergoing vitreoretinal surgery for macular hemorrhage.

DESIGN

Double-armed, randomized controlled surgical trial (ClinicalTrials.gov identifier: NCT03052881).

METHODS

The study was performed at the Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom. In total, 12 participants were recruited-6 in the robot-assisted and 6 in the control manual surgery arm according to the prespecified inclusion and exclusion criteria. All subjects presented with acute loss of vision owing to a subfoveal hemorrhage secondary to neovascular age-related macular degeneration. After standard vitrectomy, intraoperative optical coherence tomography-guided subretinal injection of tissue plasminogen activator (TPA) was performed by either robot-assisted or conventional manual technique under local anesthesia. The robotic part of the procedure involved advancement of a cannula through the retina and stabilizing it during foot-controlled injection of up to 100 µL of TPA solution. We assessed surgical success, duration of surgery, adverse events, and tolerability of surgery under local anesthesia.

RESULTS

The procedure was well tolerated by all participants and safely performed in all cases. Total duration of surgery, time taken to complete the injection, and retinal microtrauma were similar between the groups and not clinically significant. Subretinal hemorrhage was successfully displaced at 1 month postintervention, except for 1 control subject, and the median gain in visual acuity was similar in both arms.

CONCLUSIONS

This first-in-human study demonstrates the feasibility and safety of high-precision robot-assisted subretinal drug delivery as part of the surgical management of submacular hemorrhage, simulating its potential future application in gene or cell therapy.

Stereotactic technology for 3D bioprinting: from the perspective of robot mechanism

Three-dimensional (3D) bioprinting has been widely applied in the field of biomedical engineering because of its rapidly individualized fabrication and precisely geometric designability. The emerging demand for bioprinted tissues/organs with bio-inspired anisotropic property is stimulating new bioprinting strategies. Stereotactic bioprinting is regarded as a preferable strategy for this purpose, which can perform bioprinting at the target position from any desired orientation in 3D space. In this work, based on the motion characteristics analysis of the stacked bioprinting technologies, mechanism configurations and path planning methods for robotic stereotactic bioprinting were investigated and a prototype system based on the double parallelogram mechanism was introduced in detail. Moreover, the influence of the time dimension on stereotactic bioprinting was discussed. Finally, technical challenges and future trends of stereotactic bioprinting within the field of biomedical engineering were summarized.

A novel master-slave intraocular surgical robot with force feedback

BACKGROUND

Intraocular surgery is one of the most challenging microsurgeries. Unintended movements of human hand and lack of force feedback can seriously affect surgical safety.

METHODS

We developed a novel master-slave robotic system with force feedback to assist intraocular surgeries. Isomorphism design was adopted to achieve intuitive control of the system. Contact force between instrument tip and tissues was measured with a force sensor developed by our group. Real-time force feedback was provided with one linear voice coil motor and two magnetic particle brakes in the master manipulator.

RESULTS

Experiments were carried out to verify the proposed system. In the phantom experiment mimicking realistic surgical operations, the contact force significantly reduced by more than 30% with the force feedback when peeling the egg inner shell membranes.

CONCLUSIONS

Experimental results demonstrate the effectiveness of force feedback and indicate the promise of the presented master-slave robotic system for intraocular surgery assistance.

Towards Bimanual Vein Cannulation: Preliminary Study of a Bimanual Robotic System With a Dual Force Constraint Controller

Retinal vein cannulation is a promising approach for treating retinal vein occlusion that involves injecting medicine into the occluded vessel to dissolve the clot. The approach remains largely unexploited clinically due to surgeon limitations in detecting interaction forces between surgical tools and retinal tissue. In this paper, a dual force constraint controller for robot-assisted retinal surgery was presented to keep the tool-to-vessel forces and tool-to-sclera forces below prescribed thresholds. A cannulation tool and forceps with dual force-sensing capability were developed and used to measure force information fed into the robot controller, which was implemented on existing Steady Hand Eye Robot platforms. The robotic system facilitates retinal vein cannulation by allowing a user to grasp the target vessel with the forceps and then enter the vessel with the cannula. The system was evaluated on an eye phantom. The results showed that, while the eyeball was subjected to rotational disturbances, the proposed controller actuates the robotic manipulators to maintain the average tool-to-vessel force at 10.9 mN and 13.1 mN and the average tool-to-sclera force at 38.1 mN and 41.2 mN for the cannula and the forcpes, respectively. Such small tool-to-tissue forces are acceptable to avoid retinal tissue injury. Additionally, two clinicians participated in a preliminary user study of the bimanual cannulation demonstrating that the operation time and tool-to-tissue forces are significantly decreased when using the bimanual robotic system as compared to freehand performance.

Toward Improving Patient Safety and Surgeon Comfort in a Synergic Robot-Assisted Eye Surgery: A Comparative Study

When robotic assistance is present into vitreoretinal surgery, the surgeon will experience reduced sensory input that is otherwise derived from the tool's interaction with the eye wall (sclera). We speculate that disconnecting the surgeon from this sensory input may increase the risk of injury to the eye and affect the surgeon's usual technique. On the other hand, robot autonomous motion to enhance patient safety might inhibit the surgeons tool manipulation and diminish surgeon comfort with the procedure. In this study, to investigate the parameters of patient safety and surgeon comfort in a robot-assisted eye surgery, we implemented three different approaches designed to keep the scleral force in a safe range during a synergic eye manipulation task. To assess the surgeon comfort during these procedures, the amount of interference with the surgeons usual maneuvers has been analyzed by defining quantitative comfort metrics. The first two utilized scleral force control approaches are based on an adaptive force control method in which the robot actively counteracts any excessive force on the sclera. The third control method is based on a virtual fixture approach in which a virtual wall is created for the surgeon in the unsafe directions of manipulation. The performance of the utilized approaches was evaluated in user studies with two experienced retinal surgeons and the outcomes of the procedure were assessed using the defined safety and comfort metrics. Results of these analyses indicate the significance of the opted control paradigm on the outcome of a safe and comfortable robot-assisted eye surgery.

A microsurgical robot research platform for robot-assisted microsurgery research and training

Purpose

Ocular surgery, ear, nose and throat surgery and neurosurgery are typical types of microsurgery. A versatile training platform can assist microsurgical skills development and accelerate the uptake of robot-assisted microsurgery (RAMS). However, the currently available platforms are mainly designed for macro-scale minimally invasive surgery. There is a need to develop a dedicated microsurgical robot research platform for both research and clinical training.

Methods

A microsurgical robot research platform (MRRP) is introduced in this paper. The hardware system includes a slave robot with bimanual manipulators, two master controllers and a vision system. It is flexible to support multiple microsurgical tools. The software architecture is developed based on the robot operating system, which is extensible at high-level control. The selection of master–slave mapping strategy was explored, while comparisons were made between different interfaces.

Results

Experimental verification was conducted based on two microsurgical tasks for training evaluation, i.e. trajectory following and targeting. User study results indicated that the proposed hybrid interface is more effective than the traditional approach in terms of frequency of clutching, task completion time and ease of control.

Conclusion

Results indicated that the MRRP can be utilized for microsurgical skills training, since motion kinematic data and vision data can provide objective means of verification and scoring. The proposed system can further be used for verifying high-level control algorithms and task automation for RAMS research.

Adaptive Control of Sclera Force and Insertion Depth for Safe Robot-Assisted Retinal Surgery

One of the significant challenges of moving from manual to robot-assisted retinal surgery is the loss of perception of forces applied to the sclera (sclera forces) by the surgical tools. This damping of force feedback is primarily due to the stiffness and inertia of the robot. The diminished perception of tool-to-eye interactions might put the eye tissue at high risk of injury due to excessive sclera forces or extreme insertion of the tool into the eye. In the present study therefore a 1-dimensional adaptive control method is customized for 3-dimensional control of sclera force components and tool insertion depth and then implemented on the velocity-controlled Johns Hopkins Steady-Hand Eye Robot. The control method enables the robot to perform autonomous motions to make the sclera force and/or insertion depth of the tool tip to follow pre-defined desired and safe trajectories when they exceed safe bounds. A robotic light pipe holding application in retinal surgery is also investigated using the adaptive control method. The implementation results indicate that the adaptive control is able to achieve the imposed safety margins and prevent sclera forces and insertion depth from exceeding safe boundaries.

The Effect of Haptic Feedback on Efficiency and Safety During Preretinal Membrane Peeling Simulation

Purpose

We determine whether haptic feedback improves surgical performance and outcome during simulated a preretinal membrane peeling procedure.

Methods

A haptic-enabled virtual reality preretinal membrane peeling simulator was developed using a surgical cockpit with two multifinger haptic devices. Six subjects (three trained retina surgeons and three nonsurgeons) performed the preretinal membrane peeling surgical procedure using two modes of operation: visual and haptic feedback, and visual feedback only.

Results

Task completion time, tool tip path trajectory, tool–retina collision force, and retinal damage were all reduced with haptic feedback used and compared to modes where haptic feedback was disabled.

Conclusions

Haptic feedback improves efficiency and safety during preretinal membrane peeling simulation.

Translational Relevance

These findings highlight the potential benefit of haptic feedback for improving performance and safety of vitreoretinal surgery.

Toward Safe Retinal Microsurgery: Development and Evaluation of an RNN-Based Active Interventional Control Framework

OBJECTIVE

Robotics-assisted retinal microsurgery provides several benefits including improvement of manipulation precision. The assistance provided to the surgeons by current robotic frameworks is, however, a "passive" support, e.g., by damping hand tremor. Intelligent assistance and active guidance are, however, lacking in the existing robotic frameworks. In this paper, an active interventional control framework (AICF) has been presented to increase operation safety by actively intervening the operation to avoid exertion of excessive forces to the sclera.

METHODS

AICF consists of the following four components: first, the steady-hand eye robot as the robotic module; second, a sensorized tool to measure tool-to-sclera forces; third, a recurrent neural network to predict occurrence of undesired events based on a short history of time series of sensor measurements; and finally, a variable admittance controller to command the robot away from the undesired instances.

RESULTS

A set of user studies were conducted involving 14 participants (with four surgeons). The users were asked to perform a vessel-following task on an eyeball phantom with the assistance of AICF as well as other two benchmark approaches, i.e., auditory feedback (AF) and real-time force feedback (RF). Statistical analysis shows that AICF results in a significant reduction of proportion of undesired instances to about 2.5%, compared with 38.4% and 26.2% using AF and RF, respectively.

CONCLUSION

AICF can effectively predict excessive-force instances and augment performance of the user to avoid undesired events during robot-assisted microsurgical tasks.

SIGNIFICANCE

The proposed system may be extended to other fields of microsurgery and may potentially reduce tissue injury.

Sclera Force Control in Robot-assisted Eye Surgery: Adaptive Force Control vs. Auditory Feedback

Surgeon hand tremor limits human capability during microsurgical procedures such as those that treat the eye. In contrast, elimination of hand tremor through the introduction of microsurgical robots diminishes the surgeons tactile perception of useful and familiar tool-to-sclera forces. While the large mass and inertia of eye surgical robot prevents surgeon microtremor, loss of perception of small scleral forces may put the sclera at risk of injury. In this paper, we have applied and compared two different methods to assure the safety of sclera tissue during robot-assisted eye surgery. In the active control method, an adaptive force control strategy is implemented on the Steady-Hand Eye Robot in order to control the magnitude of scleral forces when they exceed safe boundaries. This autonomous force compensation is then compared to a passive force control method in which the surgeon performs manual adjustments in response to the provided audio feedback proportional to the magnitude of sclera force. A pilot study with three users indicate that the active control method is potentially more efficient.

Preliminary study of an RNN-based active interventional robotic system (AIRS) in retinal microsurgery

PURPOSE

Retinal microsurgery requires highly dexterous and precise maneuvering of instruments inserted into the eyeball through the sclerotomy port. During such procedures, the sclera can potentially be injured from extreme tool-to-sclera contact force caused by surgeon's unintentional misoperations.

METHODS

We present an active interventional robotic system to prevent such iatrogenic accidents by enabling the robotic system to actively counteract the surgeon's possible unsafe operations in advance of their occurrence. Relying on a novel force sensing tool to measure and collect scleral forces, we construct a recurrent neural network with long short-term memory unit to oversee surgeon's operation and predict possible unsafe scleral forces up to the next 200 ms. We then apply a linear admittance control to actuate the robot to reduce the undesired scleral force. The system is implemented using an existing "steady hand" eye robot platform. The proposed method is evaluated on an artificial eye phantom by performing a "vessel following" mock retinal surgery operation.

RESULTS

Empirical validation over multiple trials indicates that the proposed active interventional robotic system could help to reduce the number of unsafe manipulation events.

CONCLUSIONS

We develop an active interventional robotic system to actively prevent surgeon's unsafe operations in retinal surgery. The result of the evaluation experiments shows that the proposed system can improve the surgeon's performance.

Intraocular robotic interventional surgical system (IRISS): Semi-automated OCT-guided cataract removal

BACKGROUND

With the development of laser-assisted platforms, the outcomes of cataract surgery have been improved by automating several procedures. The cataract-extraction step continues to be manually performed, but due to deficiencies in sensing capabilities, surgical complications such as posterior capsule rupture and incomplete cataract removal remain.

METHODS

An optical coherence tomography (OCT) system is integrated into our intraocular robotic interventional surgical system (IRISS) robot. The OCT images are used for preoperative planning and intraoperative intervention in a series of automated procedures. Real-time intervention allows surgeons to evaluate the progress and override the operation.

RESULTS

The developed system was validated by performing lens extraction on 30 postmortem pig eyes. Complete lens extraction was achieved on 25 eyes, and "almost complete" extraction was achieved on the remainder due to an inability to image small lens particles behind the iris. No capsule rupture was found.

CONCLUSION

The IRISS successfully demonstrated semiautomated OCT-guided lens removal with real-time supervision and intervention.

Techniques for robot-aided intraocular surgery using monocular vision

This paper presents techniques for robot-aided intraocular surgery using monocular vision in order to overcome erroneous stereo reconstruction in an intact eye. We propose a new retinal surface estimation method based on a structured-light approach. A handheld robot known as the Micron enables automatic scanning of a laser probe, creating projected beam patterns on the retinal surface. Geometric analysis of the patterns then allows planar reconstruction of the surface. To realize automated surgery in an intact eye, monocular hybrid visual servoing is accomplished through a scheme that incorporates surface reconstruction and partitioned visual servoing. We investigate the sensitivity of the estimation method according to relevant parameters and also evaluate its performance in both dry and wet conditions. The approach is validated through experiments for automated laser photocoagulation in a realistic eye phantom in vitro. Finally, we present the first demonstration of automated intraocular laser surgery in porcine eyes ex vivo.

State of the art of robotic surgery related to vision: brain and eye applications of newly available devices

Background

Robot-assisted surgery has revolutionized many surgical subspecialties, mainly where procedures have to be performed in confined, difficult to visualize spaces. Despite advances in general surgery and neurosurgery, in vivo application of robotics to ocular surgery is still in its infancy, owing to the particular complexities of microsurgery. The use of robotic assistance and feedback guidance on surgical maneuvers could improve the technical performance of expert surgeons during the initial phase of the learning curve.

Evidence acquisition

We analyzed the advantages and disadvantages of surgical robots, as well as the present applications and future outlook of robotics in neurosurgery in brain areas related to vision and ophthalmology.

Discussion

Limitations to robotic assistance remain, that need to be overcome before it can be more widely applied in ocular surgery.

Conclusion

There is heightened interest in studies documenting computerized systems that filter out hand tremor and optimize speed of movement, control of force, and direction and range of movement. Further research is still needed to validate robot-assisted procedures.

Robotic Vitreoretinal Surgery

PURPOSE

To review the current literature on robotic assistance for ophthalmic surgery, especially vitreoretinal procedures.

METHODS

MEDLINE, Embase, and Web of Science databases were searched from inception to August, 2016, for articles relevant to the review topic. Queries included combinations of the terms: robotic eye surgery, ophthalmology, and vitreoretinal.

RESULTS

In ophthalmology, proof-of-concept papers have shown the feasibility of performing many delicate anterior segment and vitreoretinal surgical procedures accurately with robotic assistance. Multiple surgical platforms have been designed and tested in animal eyes and phantom models. These platforms have the capability to measure forces generated and velocities of different surgical movements. "Smart" instruments have been designed to improve certain tasks such as membrane peeling and retinal vessel cannulations.

CONCLUSION

Ophthalmic surgery, particularly vitreoretinal surgery, might have reached the limits of human physiologic performance. Robotic assistance can help overcome biologic limitations and improve our surgical performance. Clinical studies of robotic-assisted surgeries are needed to determine safety and feasibility of using this technology in patients.

Motorized Micro-Forceps with Active Motion Guidance based on Common-Path SSOCT for Epiretinal Membranectomy

In this study, we built and tested a handheld motion-guided micro-forceps system using common-path swept source optical coherence tomography (CP-SSOCT) for highly accurate depth controlled epiretinal membranectomy. A touch sensor and two motors were used in the forceps design to minimize the inherent motion artifact while squeezing the tool handle to actuate the tool and grasp, and to independently control the depth of the tool-tip. A smart motion monitoring and a guiding algorithm were devised to provide precise and intuitive freehand control. We compared the involuntary tool-tip motion occurring while grasping with a standard manual micro-forceps and our touch sensor activated micro-forceps. The results showed that our touch-sensor-based and motor-actuated tool can significantly attenuate the motion artifact during grasping (119.81 μm with our device versus 330.73 μm with the standard micro-forceps). By activating the CP-SSOCT based depth locking feature, the erroneous tool-tip motion can be further reduced down to 5.11μm. We evaluated the performance of our device in comparison to the standard instrument in terms of the elapsed time, the number of grasping attempts, and the maximum depth of damage created on the substrate surface while trying to pick up small pieces of fibers (Ø 125 μm) from a soft polymer surface. The results indicate that all metrics were significantly improved when using our device; of note, the average elapsed time, the number of grasping attempts, and the maximum depth of damage were reduced by 25%, 31%, and 75%, respectively.

Feasibility study on robot-assisted retinal vascular bypass surgery in an ex vivo porcine model

PURPOSE

To describe a new robot-assisted surgical system for retinal vascular bypass surgery (RVBS) and to compare the success rate with freehand RVBS.

METHODS

A robot-assisted system for retinal microsurgery was constructed to include two independent robotic arms. A 23-gauge light probe and an intraocular forceps were affixed to the arm end effectors to perform the intraocular manipulation. Harvested porcine eyes were introduced to be established animal models of closed-sky eyeballs after that pars plana vitrectomy using temporary keratoprosthesis was performed by a skilful surgeon. Retinal vascular bypass surgery (RVBS) was performed by an inexperienced ophthalmologist to test the ease of use. A stainless steel wire (45-μm pipe diameter) was used as an artificial vessel. Before RVBS, the wires were prepositioned at the retinal surface of the eyes. The Control group (n = 20) underwent freehand RVBS, and the Experimental group (n = 20) underwent robot-assisted RVBS. To create the simulated bypass, the distal end of the wire was inserted into the selected vessel and advanced ~4 mm away from the optic disc. If successful, then the proximal wire end was inserted and advanced ~2 mm towards the optic disc. The difference in the success rate for the freehand and robot-assisted procedures was analysed by the chi-square test.

RESULTS

The success rate for the freehand RVBS was 5% (1/20 eyes). In contrast, the robot-assisted success rate was 35% (7/20) of eyes (p < 0.05).

CONCLUSION

This study demonstrated the feasibility of robot-assisted RVBS in ex vivo porcine eyes. The robotic system increased the accuracy and stability of manipulation by eliminating freehand tremor, leading to a higher surgical success rate.

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

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.

EyeSLAM: Real-time simultaneous localization and mapping of retinal vessels during intraocular microsurgery

BACKGROUND

Fast and accurate mapping and localization of the retinal vasculature is critical to increasing the effectiveness and clinical utility of robot-assisted intraocular microsurgery such as laser photocoagulation and retinal vessel cannulation.

METHODS

The proposed EyeSLAM algorithm delivers 30 Hz real-time simultaneous localization and mapping of the human retina and vasculature during intraocular surgery, combining fast vessel detection with 2D scan-matching techniques to build and localize a probabilistic map of the vasculature.

RESULTS

In the harsh imaging environment of retinal surgery with high magnification, quick shaky motions, textureless retina background, variable lighting and tool occlusion, EyeSLAM can map 75% of the vessels within two seconds of initialization and localize the retina in real time with a root mean squared (RMS) error of under 5.0 pixels (translation) and 1° (rotation).

CONCLUSIONS

EyeSLAM robustly provides retinal maps and registration that enable intelligent surgical micromanipulators to aid surgeons in simulated retinal vessel tracing and photocoagulation tasks.

Cooperative robot assistant for vitreoretinal microsurgery: development of the RVRMS and feasibility studies in an animal model

PURPOSE

The purpose of the study was to describe the development of a robotic aided surgical system named RVRMS (robotic vitreous retinal microsurgery system) and to evaluate the capability for using it to perform vitreoretinal surgery.

METHODS

The RVRMS was designed and built to include the key components of two independent arms. End-effectors of each arm fix various surgical instruments and perform intraocular manipulation. To evaluate properly the RVRMS, robot-assisted 23-gauge surgical tasks including endolaser for retinal photocoagulation, pars plana vitrectomy (PPV), retinal foreign body removal and retinal vascular cannulation were performed in two different sizes of an animal model. Endolaser was performed in the eye of a living Irish rabbit and the other tasks were done in a harvested porcine eye. For each evaluation, the duration and the successful completion of the task was assessed.

RESULTS

Robot-assisted vitreoretinal operations were successfully performed in nine rabbit eyes and 25 porcine eyes without any iatrogenic complication such as retinal tear or retinal detachment. In the task of using an endolaser, three rows of burns around the induced retinal hole were performed in nine rabbit eyes with half size intervals of laser spots. Nine procine eyes underwent PPV followed by successful posterior vitreous detachment (PVD) induction assisted with triamcinolone acetonide (TA). Nine porcine eyes completed removal of a fine stainless steel wire, which was inserted into prepared retinal tissue. Finally, retinal vascular cannulation with a piece of stainless steel wire (6mm length, 45 μm pipe diameter and one end cut to ∼30° slope) was successfully achieved in seven porcine eyes. The average duration of each procedure was 10.91±1.22 min, 11.68±2.11min, 5.90±0.46 min and 13.5±6.2 min, respectively.

CONCLUSIONS

Maneuverability, accuracy and stability of robot-assisted vitreoretinal microsurgery using the RVRMS were demonstrated in this study. Wider application research of robotic surgery and improvement of a robotic system should be continued.

The Role of Haptic Feedback in Robotic-Assisted Retinal Microsurgery Systems: A Systematic Review

Retinal microsurgery is one of the most technically difficult surgeries since it is performed at the threshold of human capability. If certain retinal conditions are left untreated, they can lead to severe damage, including irreversible blindness. Thus, techniques for reliable retinal microsurgery operations are critical. Recent research shows promise for improving surgical safety by implementing various types of sensory input and output. Sensory information is used to inform the surgeon about the environment inside the eye in real time. This review examines literature that discusses human factors and ergonomics (HFE) of sensory inputs and outputs of retinal microsurgery instrumentation with a focus on force and haptic feedback. Thirty-four studies were reviewed on the following topics: (1) variation between different input sensory devices and their performance, (2) variation between alternative output sensory devices and their performance, and (3) variation between alternative output sensory devices and their user satisfaction. This review finds that the implementation of HFE is important for the consideration of retinal microsurgery devices, but it is largely missing from current research. The addition of direct comparisons between devices, measures of user acceptance, usability evaluations, and greater realism in testing would help advance the use of haptic sensory feedback for retinal microsurgery instruments.

Medical Engineering and Microneurosurgery: Application and Future

Robotics and medical engineering can convert traditional surgery into digital and scientific procedures. Here, we describe our work to develop microsurgical robotic systems and apply engineering technology to assess microsurgical skills. With the collaboration of neurosurgeons and an engineering team, we have developed two types of microsurgical robotic systems. The first, the deep surgical systems, enable delicate surgical procedures such as vessel suturing in a deep and narrow space. The second type allows for super-fine surgical procedures such as anastomosing artificial vessels of 0.3 mm in diameter. Both systems are constructed with master and slave manipulator robots connected to local area networks. Robotic systems allowed for secure and accurate procedures in a deep surgical field. In cadaveric models, these systems showed a good potential of being useful in actual human surgeries, but mechanical refinements in thickness and durability are necessary for them to be established as clinical systems. The super-fine robotic system made the very intricate surgery possible and will be applied in clinical trials. Another trial included the digitization of surgical technique and scientific analysis of surgical skills. Robotic and human hand motions were analyzed in numerical fashion as we tried to define surgical skillfulness in a digital format. Engineered skill assessment is also feasible and should be useful for microsurgical training. Robotics and medical engineering should bring science into the surgical field and training of surgeons. Active collaboration between medical and engineering teams and academic and industry groups is mandatory to establish such medical systems to improve patient care.

A Compact Telemanipulated Retinal-Surgery System that Uses Commercially Available Instruments with a Quick-Change Adapter

We present a telemanipulation system for retinal surgery that uses a full range of unmodified commercially available instruments. The system is compact and light enough that it could reasonably be made head-mounted to passively compensate for head movements. Two mechanisms are presented that enable the system to use commercial actuated instruments, and an instrument adapter enables quick-change of instruments during surgery. A custom stylus for a haptic interface enables intuitive and ergonomic telemanipulation of actuated instruments. Experimental results with a force-sensitive phantom eye show that telemanipulated surgery results in reduced forces on the retina compared to manual surgery, and training with the system results in improved performance.

Effects of Micro-Vibratory Modulation during Robot-Assisted Membrane Peeling

In retinal microsurgery, membrane peeling is a standard procedure requiring the delamination of a thin fibrous membrane adherent to the retina surface by applying very small forces. Robotic devices with combined force-sensing instruments have significant potential to assist this procedure by facilitating membrane delamination through induced micro-vibrations. However, defining the optimal frequency and amplitude for generating such vibrations, and updating these parameters during the procedure is not trivial. Automatic adjustment of these parameters via an adaptive control scheme is possible only if the individual parameter effects on delamination behavior are known. This study presents an experimental exploration of how micro-vibration amplitude and frequency affect membrane peeling forces alone. Combining a micromanipulator and a force-sensing micro-forceps, several peeling experiments were done on artificial phantoms (bandages) and inner shell membrane of raw chicken eggs. In the tested range of micro-vibration frequencies (10-50 Hz) the average delamination force was minimized mostly at 30 Hz for the bandages and at 50 Hz for the egg membranes. Increasing the micro-vibration amplitude from 50 μm up to 150 μm provided further reduction in average force, thus facilitated membrane delamination.

The introduction of a new robot for assistance in ophthalmic surgery

This paper introduces the design and development of a new robotic system to assist surgeons performing ophthalmic surgeries. The robot itself is very compact and similar to an average human hand in size. Its primary application is intraocular micromanipulation in order to overcome the existing challenges in treatment of diseases like Retinal Vein Occlusion (RVO). The novel hybrid mechanism designed for this robot allows microscale motions and is stable in the presence of vibrations common in operation room (OR). The robotic system can be easily integrated into standard operation rooms and does not require modification of conventional surgical tools. This compact microsurgical system is suitable for mounting on the patient's head and thereby, solves the problem of patient motion. The compatibility of the robotic system with a real world surgical setup was evaluated and confirmed in this work.

Improvement of optical coherence tomography using active handheld micromanipulator in vitreoretinal surgery

An active handheld micromanipulator has been developed to cancel hand tremor during microsurgery. The micromanipulator is also applicable in optical coherence tomography to improve the quality of scanning and minimize surgical risks during the scans. The manipulator can maneuver the tool tip with six degrees of freedom within a cylindrical workspace 4 mm in diameter and 4 mm high. The imaging system is equipped with a 25-gauge Fourier-domain common-path OCT probe. This paper introduces the handheld OCT imaging system and techniques involved and presents stabilized OCT images of A-mode and M-mode scans in air and live rabbit eyes. We show the first demonstration of OCT imaging using the active handheld micromanipulator in vivo.

Accurate real-time depth control for CP-SSOCT distal sensor based handheld microsurgery tools

This paper presents a novel intuitive targeting and tracking scheme that utilizes a common-path swept source optical coherence tomography (CP-SSOCT) distal sensor integrated handheld microsurgical tool. To achieve micron-order precision control, a reliable and accurate OCT distal sensing method is required; simultaneously, a prediction algorithm is necessary to compensate for the system delay associated with the computational, mechanical and electronic latencies. Due to the multi-layered structure of retina, it is necessary to develop effective surface detection methods rather than simple peak detection. To achieve this, a shifted cross-correlation method is applied for surface detection in order to increase robustness and accuracy in distal sensing. A predictor based on Kalman filter was implemented for more precise motion compensation. The performance was first evaluated using an established dry phantom consisting of stacked cellophane tape. This was followed by evaluation in an ex-vivo bovine retina model to assess system accuracy and precision. The results demonstrate highly accurate depth targeting with less than 5 μm RMSE depth locking.

Evaluation of microsurgical tasks with OCT-guided and/or robot-assisted ophthalmic forceps

Real-time intraocular optical coherence tomography (OCT) visualization of tissues with surgical feedback can enhance retinal surgery. An intraocular 23-gauge B-mode forward-imaging co-planar OCT-forceps, coupling connectors and algorithms were developed to form a unique ophthalmic surgical robotic system. Approach to the surface of a phantom or goat retina by a manual or robotic-controlled forceps, with and without real-time OCT guidance, was performed. Efficiency of lifting phantom membranes was examined. Placing the co-planar OCT imaging probe internal to the surgical tool reduced instrument shadowing and permitted constant tracking. Robotic assistance together with real-time OCT feedback improved depth perception accuracy. The first-generation integrated OCT-forceps was capable of peeling membrane phantoms despite smooth tips.

Motorized Force-Sensing Micro-Forceps with Tremor Cancelling and Controlled Micro-Vibrations for Easier Membrane Peeling

Retinal microsurgery requires the manipulation of extremely delicate tissues by various micron scale maneuvers and the application of very small forces. Among vitreoretinal procedures, membrane peeling is a standard procedure requiring the delamination of a very thin fibrous membrane on the retina surface. This study presents the development and evaluation of an integrated assistive system for membrane peeling. This system combines a force-sensing motorized micro-forceps with an active tremor-canceling handheld micromanipulator, Micron. The proposed system (1) attenuates hand-tremor when accurate positioning is needed, (2) provides auditory force feedback to keep the exerted forces at a safe level, and (3) pulsates the tool tip at high frequency to provide ease in delaminating membranes. Experiments on bandages and raw chicken eggs have revealed that controlled micro-vibrations provide significant ease in delaminating membranes. Applying similar amount of forces, much faster delamination was observed when the frequency of these vibrations were increased (up to 50 Hz).

Force-Sensing Microneedle for Assisted Retinal Vein Cannulation*

Retinal vein cannulation (RVC) is a challenging procedure proposed for drug delivery into the very small retinal veins. The available glass cannulas for this procedure are both hard to visualize and fragile thereby limiting the feasibility of both robot-assisted and manual RVC approaches. In this study, we develop and test a new force-sensing RVC instrument that can be easily integrated with the existing manual and robotic devices. The tool enables (1) the measurement of the forces required for puncturing retinal veins in vivo and (2) an assistive method to inform the operator of the needle piercing the vessel wall. The fiber Bragg grating based sensor can be inserted into the eye through a small (∅ 0.9 mm) opening and provides a quantitative assessment at the tool tip with a resolution smaller than 0.25 mN. Assessment of forces during vessel penetration in the chorioallantoic membranes of chicken embryos have revealed a consistent sharp drop in tool tip force upon vessel puncture that has been used as a signature to provide auditory feedback to the user to stop needle advancement and begin drug delivery.

Design and Research of a Robotic Aided System for Retinal Vascular Bypass Surgery

With reference to the study of the robotic system for ophthalmology microsurgery, a robotic system was presented with the key mechanism design and control subsystem scheme considering the procedures and features of retinal vascular bypass surgery. After discussion of the clinical application, the human-machine cooperated surgical process of the robotic system for retinal vascular bypass surgery was described, and the design of the surgical layout environment was proposed. The intraocular motion planning method was also described and corresponding experiments using a table tennis ball model and an in vitro porcine eye model were performed. Finally, the feasibility analysis and robotic system error analysis were also summarized and future works discussed for further research.

Towards Robot-Assisted Vitreoretinal Surgery: Force-Sensing Micro-Forceps Integrated with a Handheld Micromanipulator

In vitreoretinal practice, controlled tremor-free motion and limitation of applied forces to the retina are two highly desired features. This study addresses both requirements with a new integrated system: a force-sensing motorized micro-forceps combined with an active tremor-canceling handheld micromanipulator, known as Micron. The micro-forceps is a 20 Ga instrument that is mechanically decoupled from its handle and senses the transverse forces at its tip with an accuracy of 0.3 mN. Membrane peeling trials on a bandage phantom revealed a 60-95% reduction in the 2-20 Hz band in both the tip force and position spectra, while peeling forces remained below the set safety threshold.

Swept source optical coherence tomography based smart handheld vitreoretinal microsurgical tool for tremor suppression

Microsurgeons require the ability to make precise and stable maneuvers in order to achieve surgical objectives and to minimize surgical risks during freehand microsurgical procedures. This work presents a novel common path swept source optical coherence tomography based smart surgical tool that suppresses hand tremor. It allows enhanced tool tip stabilization, more accurate targeting and may lower surgical risk. Here the one dimensional motion tremor of a surgeon's hand is assessed by the surgical instrument. The ability to accurately locate a surgical target and the ability to maintain tool tip offset distances in a chicken embryo model are significantly improved as compared to freehand use.

Force sensing micro-forceps for robot assisted retinal surgery

Membrane peeling is a standard vitreoretinal procedure, where the surgeon delaminates a very thin membrane from retina surface using surgical picks and forceps. This requires extremely delicate manipulation of the retinal tissue. Applying excessive forces during the surgery can cause serious complications leading to vision loss. For successful membrane peeling, most of the applied forces need to be very small, well below the human tactile sensation threshold. In this paper, we present a robotic system that combines a force sensing forceps tool and a cooperatively-controlled surgical robot. This combination allows us to measure the forces directly at the tool tip and use this information for limiting the applied forces on the retina. This may prevent many iatrogenic injuries and allow safer maneuvers during vitreoretinal procedures. We show that our system can successfully eliminate hand-tremor and excessive forces in membrane peeling experiments on the inner shell membrane of a chicken embryo.

Telerobotic contact transscleral cyclophotocoagulation of the ciliary body with the diode laser

To assess the feasibility of using the Robotic Slave Micromanipulator Unit (RSMU) to remotely photocoagulate the ciliary body for the treatment of glaucoma with the diode laser. In fresh unoperated enucleated human eyes, the ciliary body was destroyed either with a standard contact transscleral cyclophotocoagulation 'by hand' diode laser technique, or remotely using the RSMU. The treated sections were fixed in formalin, paraffin-embedded, and stained with hematoxylin and eosin. Histological evaluation was performed by a masked observer using a standardized grading system based on the amount of damage to the ciliary body to evaluate effectiveness of treatment. Both methods of contact transscleral cyclophotocoagulation showed therapeutic tissue disruption of the ciliary processes and both the non-pigmented and pigmented ciliary epithelium. Histology examination of remote robotic contact transscleral cyclophotocoagulation and "by hand" technique produced similar degrees of ciliary body tissue disruption. Remote diode laser contact transscleral cyclophotocoagulation of the ciliary body in fresh enucleated human eyes is possible with the RSMU. Therapeutic tissue disruption of the ciliary body was achieved. Additional study is necessary to determine the safety and efficacy of robotically-delivered cyclophotocoagulation in live eyes.

Vision-Based Control of a Handheld Surgical Micromanipulator with Virtual Fixtures

Performing micromanipulation and delicate operations in submillimeter workspaces is difficult because of destabilizing tremor and imprecise targeting. Accurate micromanipulation is especially important for microsurgical procedures, such as vitreoretinal surgery, to maximize successful outcomes and minimize collateral damage. Robotic aid combined with filtering techniques that suppress tremor frequency bands increases performance; however, if knowledge of the operator's goals is available, virtual fixtures have been shown to further improve performance. In this paper, we derive a virtual fixture framework for active handheld micromanipulators that is based on high-bandwidth position measurements rather than forces applied to a robot handle. For applicability in surgical environments, the fixtures are generated in real-time from microscope video during the procedure. Additionally, we develop motion scaling behavior around virtual fixtures as a simple and direct extension to the proposed framework. We demonstrate that virtual fixtures significantly outperform tremor cancellation algorithms on a set of synthetic tracing tasks (p < 0.05). In more medically relevant experiments of vein tracing and membrane peeling in eye phantoms, virtual fixtures can significantly reduce both positioning error and forces applied to tissue (p < 0.05).

Robot-assisted intraocular surgery: development of the IRISS and feasibility studies in an animal model

PURPOSE

The aim of this study is to develop a novel robotic surgical platform, the IRISS (Intraocular Robotic Interventional and Surgical System), capable of performing both anterior and posterior segment intraocular surgery, and assess its performance in terms of range of motion, speed of motion, accuracy, and overall capacities.

PATIENTS AND METHODS

To test the feasibility of performing 'bimanual' intraocular surgical tasks using the IRISS, we defined four steps out of typical anterior (phacoemulsification) and posterior (pars plana vitrectomy (PPV)) segment surgery. Selected phacoemulsification steps included construction of a continuous curvilinear capsulorhexis and cortex removal in infusion-aspiration (I/A) mode. Vitrectomy steps consisted of performing a core PPV, followed by aspiration of the posterior hyaloid with the vitreous cutter to induce a posterior vitreous detachment (PVD) assisted with triamcinolone, and simulation of the microcannulation of a temporal retinal vein. For each evaluation, the duration and the successful completion of the task with or without complications or involuntary events was assessed.

RESULTS

Intraocular procedures were successfully performed on 16 porcine eyes. Four eyes underwent creation of a round, curvilinear anterior capsulorhexis without radialization. Four eyes had I/A of lens cortical material completed without posterior capsular tear. Four eyes completed 23-gauge PPV followed by successful PVD induction without any complications. Finally, simulation of microcannulation of a temporal retinal vein was successfully achieved in four eyes without any retinal tears/perforations noted.

CONCLUSION

Robotic-assisted intraocular surgery with the IRISS may be technically feasible in humans. Further studies are pending to improve this particular surgical platform.

A Comparative Study for Robot Assisted Vitreoretinal Surgery: Micron vs. the Steady-Hand Robot

In vitreoretinal surgery, application of excessive forces and unintentional motion due to hand-tremor can easily result in serious complications. Robotic assistance when combined with tool-to-tissue force sensing capabilities has significant potential to improve such practice. In this paper, we evaluate the membrane peeling performance of a single user for two distinct robotic systems with integrated force sensing capabilities: Micron and the Steady-Hand Robot. We show that these systems provide promising performance improvement with similar impact on peeling forces and comparable tremor cancellation trends.

Impact of robotic assistance on precision of vitreoretinal surgical procedures

PURPOSE

To elucidate the merits of robotic application for vitreoretinal maneuver in comparison to conventional manual performance using an in-vitro eye model constructed for the present study.

METHODS

Capability to accurately approach the target on the fundus, to stabilize the manipulator tip just above the fundus, and to perceive the contact of the manipulator tip with the fundus were tested. The accuracies were compared between the robotic and manual control, as well as between ophthalmologists and engineering students.

RESULTS

In case of manual control, ophthalmologists were superior to engineering students in all the 3 test procedures. Robotic assistance significantly improved accuracy of all the test procedures performed by engineering students. For the ophthalmologists including a specialist of vitreoretinal surgery, robotic assistance enhanced the accuracy in the stabilization of manipulator tip (from 90.9 µm to 14.9 µm, P = 0.0006) and the perception of contact with the fundus (from 20.0 mN to 7.84 mN, P = 0.046), while robotic assistance did not improve pointing accuracy.

CONCLUSIONS

It was confirmed that telerobotic assistance has a potential to significantly improve precision in vitreoretinal procedures in both experienced and inexperienced hands.

Real-Time Retinal Vessel Mapping and Localization for Intraocular Surgery

Computer-aided intraocular surgery requires precise, real-time knowledge of the vasculature during retinal procedures such as laser photocoagulation or vessel cannulation. Because vitreoretinal surgeons manipulate retinal structures on the back of the eye through ports in the sclera, voluntary and involuntary tool motion rotates the eye in the socket and causes movement to the microscope view of the retina. The dynamic nature of the surgical workspace during intraocular surgery makes mapping, tracking, and localizing vasculature in real time a challenge. We present an approach that both maps and localizes retinal vessels by temporally fusing and registering individual-frame vessel detections. On video of porcine and human retina, we demonstrate real-time performance, rapid convergence, and robustness to variable illumination and tool occlusion.

Evaluation of a Micro-Force Sensing Handheld Robot for Vitreoretinal Surgery

Highly accurate positioning is fundamental to the performance of vitreoretinal microsurgery. Of vitreoretinal procedures, membrane peeling is among the most prone to complications since extremely delicate manipulation of retinal tissue is required. Associated tool-to-tissue interaction forces are usually below the threshold of human perception, and the surgical tools are moved very slowly, within the 0.1-0.5 mm/s range. During the procedure, unintentional tool motion and excessive forces can easily give rise to vision loss or irreversible damage to the retina. A successful surgery includes two key features: controlled tremor-free tool motion and control of applied force. In this study, we present the potential benefits of a micro-force sensing robot in vitreoretinal surgery. Our main contribution is implementing fiber Bragg grating based force sensing in an active tremor canceling handheld micromanipulator, known as Micron, to measure tool-to-tissue interaction forces in real time. Implemented auditory sensory substitution assists in reducing and limiting forces. In order to test the functionality and performance, the force sensing Micron was evaluated in peeling experiments with adhesive bandages and with the inner shell membrane from chicken eggs. Our findings show that the combination of active tremor canceling together with auditory sensory substitution is the most promising aid that keeps peeling forces below 7 mN with a significant reduction in 2-20 Hz oscillations.

Active tremor cancellation by a "smart" handheld vitreoretinal microsurgical tool using swept source optical coherence tomography

Microsurgeons require dexterity to make precise and stable maneuvers to achieve surgical objectives and to minimize surgical risks during freehand procedures. This work presents a novel, common path, swept source optical coherence tomography-based "smart" micromanipulation aided robotic-surgical tool (SMART) that actively suppresses surgeon hand tremor. The tool allows enhanced tool tip stabilization, more accurate targeting and the potential to lower surgical risk. Freehand performance is compared to smart tool-assisted performance and includes assessment of the one-dimensional motion tremor in an active microsurgeon's hand. Surgeon hand tremor-the ability to accurately locate a surgical target and maintain tool tip offset distances-were all improved by smart tool assistance.