Advantages of robotic assistance over a manual approach in simulated subretinal injections and its relevance for gene therapy

Sharper vision, steady hands: can robots improve subretinal drug delivery? Systematic review

Subretinal injection (SI) is a novel drug delivery method, directly to retina for treatment of various eye disease. However, manual injection requires surgical experience and precision due to physiological factors. Robots offer solution to this issue, by reducing hand tremor and increased accuracy. This systematic review analyzes current status on robot-assisted SI compared to conventional techniques. Systematic search across 5 databases was conducted to identify studies comparing manual and robot-assisted SI procedures. Extracted data included robotic systems, complications, and success rates. Four studies, including one human trial, two ex vivo porcine eye studies, and one artificial eye model study were included in the synthesis. The findings show early advantages of robot-assisted SI. Compared to traditional interventions, robot procedures result in reduced tremor, what potentially lowers the risk of complications, including retinal tears and reflux. The first in-human randomized trial showed encouraging results, with no significant differences in surgical times or complications between robot-assisted and manual SI. However, major limitation of robot-assisted procedures is longer procedure time. Robot-assisted SI holds promise by offering increased precision and stability, reducing human error and potentially improving clinical outcomes. Challenges include cost, availability, and learning curve. Overall, early stage of robot-assisted SI suggests advantages in precision, complication reduction, and potentially improved drug delivery. Further research in human randomized trials is needed to fully assess its full-scale clinical application.

Autonomous Needle Navigation in Subretinal Injections via iOCT

Subretinal injection is an effective method for direct delivery of therapeutic agents to treat prevalent subretinal diseases. Among the challenges for surgeons are physiological hand tremor, difficulty resolving single-micron scale depth perception, and lack of tactile feedback. The recent introduction of intraoperative Optical Coherence Tomography (iOCT) enables precise depth information during subretinal surgery. However, even when relying on iOCT, achieving the required micron-scale precision remains a significant surgical challenge. This work presents a robot-assisted workflow for high-precision autonomous needle navigation for subretinal injection. The workflow includes online registration between robot and iOCT coordinates; tool-tip localization in iOCT coordinates using a Convolutional Neural Network (CNN); and tool-tip planning and tracking system using real-time Model Predictive Control (MPC). The proposed workflow is validated using a silicone eye phantom and ex vivo porcine eyes. The experimental results demonstrate that the mean error to reach the user-defined target and the mean procedure duration are within an acceptable precision range. The proposed workflow achieves a 100% success rate for subretinal injection, while maintaining scleral forces at the scleral insertion point below 15mN throughout the navigation procedures.

Design of a Subretinal Injection Robot Based on the RCM Mechanism

This study presents an investigation focusing on the advancement of a robot designed for subretinal injections in the context of macular degeneration treatment. The technique of subretinal injection surgery stands as the most efficacious approach for the successful transplantation of stem cells into the retinal pigment epithelium layer. This particular procedure holds immense significance in advancing research and implementing therapeutic strategies involving retinal stem cell transplantation. The execution of artificial subretinal surgery poses considerable challenges which can be effectively addressed through the utilization of subretinal injection surgery robots. The development process involved a comprehensive modeling phase, integrating computer-aided design (CAD) and finite element analysis (FEA) techniques. These simulations facilitated iterative enhancements of the mechanical aspects pertaining to the robotic arm. Furthermore, MATLAB was employed to simulate and visualize the robot's workspace, and independent verification was conducted to ascertain the range of motion for each degree of freedom.

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.

The Role of Subretinal Injection in Ophthalmic Surgery: Therapeutic Agent Delivery and Other Indications

Subretinal injection is performed in vitreoretinal surgery with two main aims, namely, the subretinal delivery of therapeutic agents and subretinal injection of fluid to induce a controlled and localized macular detachment. The growing interest in this technique is mainly related to its suitability to deliver gene therapy in direct contact with target tissues. However, subretinal injection has been also used for the surgical management of submacular hemorrhage through the subretinal delivery of tissue plasminogen activator, and for the repair of full-thickness macular holes, in particular refractory ones. In the light of the increasing importance of this maneuver in vitreoretinal surgery as well as of the lack of a standardized surgical approach, we conducted a comprehensive overview on the current indications for subretinal injection, surgical technique with the available variations, and the potential complications.

Robotic Navigation Autonomy for Subretinal Injection via Intelligent Real-Time Virtual iOCT Volume Slicing

In the last decade, various robotic platforms have been introduced that could support delicate retinal surgeries. Concurrently, to provide semantic understanding of the surgical area, recent advances have enabled microscope-integrated intraoperative Optical Coherent Tomography (iOCT) with high-resolution 3D imaging at near video rate. The combination of robotics and semantic understanding enables task autonomy in robotic retinal surgery, such as for subretinal injection. This procedure requires precise needle insertion for best treatment outcomes. However, merging robotic systems with iOCT introduces new challenges. These include, but are not limited to high demands on data processing rates and dynamic registration of these systems during the procedure. In this work, we propose a framework for autonomous robotic navigation for subretinal injection, based on intelligent real-time processing of iOCT volumes. Our method consists of an instrument pose estimation method, an online registration between the robotic and the iOCT system, and trajectory planning tailored for navigation to an injection target. We also introduce intelligent virtual B-scans, a volume slicing approach for rapid instrument pose estimation, which is enabled by Convolutional Neural Networks (CNNs). Our experiments on ex-vivo porcine eyes demonstrate the precision and repeatability of the method. Finally, we discuss identified challenges in this work and suggest potential solutions to further the development of such systems.

Robot-assisted subretinal injection system: development and preliminary verification

BACKGROUND

To design and develop a surgical robot capable of assisting subretinal injection.

METHODS

A remote center of motion (RCM) mechanical design and a master-slave teleoperation were used to develop and manufacture the assisted subretinal surgery robot (RASR). Ten fresh isolated porcine eyes were divided into the Robot Manipulation (RM) group and Manual Manipulation (MM) group (5 eyes for each group), and subretinal injections were performed by the robot and manual manipulation methods, respectively. A preliminary verification of the robot was performed by comparing the advantages and disadvantages of the robot manipulation and manual manipulation by using optical coherent tomography (OCT), fundus photography, and video motion capture analysis after the surgery.

RESULTS

Both the robot and the manual manipulation were able to perform subretinal injections with a 100% success rate. The OCT results showed that the average subretinal area was 1.548 mm² and 1.461 mm² in the RM and MM groups, respectively (P > 0.05). Meanwhile the volume of subretinal fluid obtained using the retinal map mode built in OCT was not statistically different between the RM and MM groups (P > 0.05). By analyzing the surgical video using Kinovea, a motion capture and analysis software, the results suggest that the mean tremor amplitude of the RM group was 0.3681 pixels (x direction), which was significantly reduced compared to 18.8779 pixels (x direction) in the MM group (P < 0.0001).

CONCLUSION

Robot-assisted subretinal injection system (RASR) is able to finish subretinal injection surgery with better stability and less fatigue than manual manipulation.

OCT-guided Robotic Subretinal Needle Injections: A Deep Learning-Based Registration Approach

Subretinal injection (SI) is an ophthalmic surgical procedure that allows for the direct injection of therapeutic substances into the subretinal space to treat vitreoretinal disorders. Although this treatment has grown in popularity, various factors contribute to its difficulty. These include the retina's fragile, nonregenerative tissue, as well as hand tremor and poor visual depth perception. In this context, the usage of robotic devices may reduce hand tremors and facilitate gradual and controlled SI. For the robot to successfully move to the target area, it needs to understand the spatial relationship between the attached needle and the tissue. The development of optical coherence tomography (OCT) imaging has resulted in a substantial advancement in visualizing retinal structures at micron resolution. This paper introduces a novel foundation for an OCT-guided robotic steering framework that enables a surgeon to plan and select targets within the OCT volume. At the same time, the robot automatically executes the trajectories necessary to achieve the selected targets. Our contribution consists of a novel combination of existing methods, creating an intraoperative OCT-Robot registration pipeline. We combined straightforward affine transformation computations with robot kinematics and a deep neural network-determined tool-tip location in OCT. We evaluate our framework's capability in a cadaveric pig eye open-sky procedure and using an aluminum target board. Targeting the subretinal space of the pig eye produced encouraging results with a mean Euclidean error of 23.8μm.

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.

Subretinal Therapy: Technological Solutions to Surgical and Immunological Challenges

Recent advances in ocular gene and cellular therapy rely on precisely controlled subretinal delivery. Due to its inherent limitations, manual delivery can lead to iatrogenic damage to the retina, the retinal pigment epithelium, favor reflux into the vitreous cavity. In addition, it suffers from lack of standardization, variability in delivery and the need to maintain proficiency. With or without surgical damage, an eye challenged with an exogenous viral vector or transplanted cells will illicit an immune response. Understanding how such a response manifests itself and to what extent immune privilege protects the eye from a reaction can help in anticipating short- and long-term consequences. Avoidance of spillover from areas of immune privilege to areas which either lack or have less protection should be part of any mitigation strategy. In that regard, robotic technology can provide reproducible, standardized delivery which is not dependent on speed of injection. The advantages of microprecision medical robotic technology for precise targeted deliveries are discussed.

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.

Controlled subretinal injection pressure prevents damage in pigs

Introduction Administration of retinal gene- and stem cell therapy in patients with retinal degenerative diseases (RDD) is in many cases dependent of a subretinal approach. It has been indicated that manual subretinal injection is associated with outer retinal damage, which may be explained be high flow rate in the injection cannula. In the present porcine study, we evaluated flow-related retinal damage after controlled subretinal injection at different flow rates. Methods Flow rate through a 41G cannula was estimated at different injection pressures (6-48 PSI (pounds per square inch)) in an in-vitro setup. A linear correlation between flow rate and injection pressure was found from 6-32 PSI. In full anesthesia, 12 pigs were vitrectomized and received a controlled subretinal injection of 300 microliters balanced saline solution at injection pressures of either 14, 24 and 32 PSI (four in each group). Prior to surgery and two and four weeks after surgery, the eyes where examined by multifocal electroretinogram (mfERG) and fundus photographs. At the end of follow-up, the eyes were enucleated for histology. Results The in vitro flow study determined that the flow in a 41 G cannula shift from laminar to tubular at 32 PSI, and that the manual injection flow is tubular. In the porcine study we showed a significant difference in retinal pigment epithelium (RPE) damage between the three pressure groups (p = 0.0096). There was no significant difference in damage to the outer retina (p = 0.1526), but the high-pressure group (32 PSI) had most outer retinal damage. The middle-pressure group (24 PSI) showed minimum retinal damage. There was no significant change in the mfERG ratios during follow-up. Discussion/Conclusion This study indicates that an injection pressure at approximately 24 PSI might be safe for subretinal delievery. Retinal damage at low injection pressures may be explained by mechanical damage to the RPE due to prolonged needle time in the subretinal space, whilst retinal damage at high pressures can be related to high flow in the injection cannula. Controlled subretinal injection pressure of 24 PSI showed minimum mechanical and flow-related damage to the porcine retina.