Design of a compact robotic assisted ophthalmic system

Purpose:Robotics have enhanced and refined microinvasive surgery in several disciplines. Its applicability in eye surgery has been limited by ergonomic and scaling issues. Our aim was to design and build a microrobotic system adapted to the needs of vitreoretinal surgeons. Methods:Constraints regarding head positioning and size, ocular access, surgical execution, and procedural requirements were defined by observations at live surgeries, discussions with surgeons, operation room teams, and computer simulations. Additional design parameters for the robotic slave (RS) included a low weight, high stiffness, low friction and play-free design. For the control module (CM), intuitiveness of the controller, body posture of the operator and patient proximity were considered. Results:The RS consists of at least two instrument manipulators (IMs).The IM’s design allows 5 degrees of freedom through a kinematically defined rotation point at the entry site into the sclera. Force measurement down to 10mN is possible and manipulation with an accuracy o

Evaluation of depth precision during subretinal injections in robot-assisted versus manual surgery

Purpose :To quantify the difference in depth precision between manual and robot-assisted surgery.Methods :Nine experienced vitreoretinal surgeons were asked to perform a subretinal injection on a phantom retina model, both manually and robot assisted using the Preceyes Surgical System (PSS) (Eindhoven, NL). Participants were randomized to perform manual or robot-assisted surgery first. The phantom retina model was composed of two gel layers separated by a thin paper layer. The task was to create a bleb under the paper, within the bottom gelatine layer, with the objective to keep the instrument as still as possible during injection.To measure distance to the target depth, which was below the paper layer, an OCT-based distance sensor was integrated into the subretinal needle. The OCT A-scan data was recorded, together with start and stop times of the injection. To quantify depth precision, drift and tremor of the instrument tip were analysed. Drift was defined as the total displacement over the entire injection time, tremor was defined as the amplitude of movements on a small time scale.Results :Mean drift in manual surgery was 363µm (SD 278µm) and reduced to 28µm (SD 22µm) in robot-assisted surgery. Mean tremor in manual surgery was 37µm (SD 18µm) and reduced to 4µm (SD 5µm) in robot-assisted surgery. Mean injection time in manual surgery was 44 seconds (SD 16 seconds) and mean injection time for robot assisted surgery was 63 seconds (SD 18 seconds).Conclusions :In this study it was shown that robot assisted surgery with the PSS drastically improves depth precision over manual surgery by reducing both drift and tremor by a factor of 10.This is a 2020 ARVO Annual Meeting abstract.info:eu-repo/semantics/publishe

Defining appropriate parameters for robotic subretinal drug delivery ensures minimal reflux

Purpose: Vitreous reflux during subretinal injection limits the degree and surface area transfected and is wasteful of a precious product. The precision and stability offered by the Preceyes platform allows for an optimized, time-independent delivery. The purpose of this study is to identify parameters important to insure reflux-free robotic subretinal drug delivery.Setting/Venue: Comparative trial in an ex vivo animal modelMethods: Freshly harvested porcine eyes underwent a standard pars plana vitrectomy with IOP control under microscopic visualization through a Rescan 700 Zeiss device; followed by subretinal injection using a 41G Teflon needle, with the Preceyes Surgical System (PSS). The following subretinal injection cannula parameters were analyzed: speed of injection, tip configuration, and positioningResults: Following multiple injections, positioning of the tip above the RPE without penetration through Bruch’s membrane was possible in all cases by using a stepwise penetration algorithm irrespective of the angle of approach. Blunt needles did not penetrate as well as needle tips with polished edges. Small robotically controlled rotations and wiggling of the injection cannula did not result in a cleaner penetration or less reflux. Sufficient delay is required between the completion of the injection and retraction of the needle to prevent reflux.Conclusions: Robotics allows for a better understanding of the injection process and a determination of critical parameters and steps. Several parameters appear critical to an efficient reflux-freeinjection.Theme: New Drug Treatment and Technologyinfo:eu-repo/semantics/nonPublishe

Use of an in vitro model to compare manual and robotic assistance in subretinal injections

Purpose: To compare manual positioning and injection using a phantom retina model for subretinal delivery and compare it to the same procedure assisted by the Preceyes Surgical SystemSetting/Venue: Randomized comparative trial in a simulated settingMethods: Ten vitreoretinal surgeons carried out a simulated subretinal injection on a phantom retina model, under microscopic visualization through a Rescan 700 OCT Zeiss device. The procedure was carried out using a syringed fitted with a 41 G needle and an integrated distance sensor. The surgeon was asked to perform the surgery manually or with the assistance of the Preceyes Surgical System (PSS; Preceyes, Eindhoven, the Netherlands). Prior to the experiment, participants received a 15 minutes introduction to the surgical protocol and how to manipulate the robotic system. Each surgery was recorded by Rescan video, iOCT and with the distance sensor. Success in creating a subretinal bleb, presence of reflux, subretinal injection duration and depth precision were subsequently analyzed. Depth precision quantification was obtained by analyzing drift (defined as the total displacement over the entire injection time) and tremor at the needle extremity using OCT A-scan recording obtained from the distance sensor. Manual and robotic approaches were compared.Results: Subretinal bleb creation was achieved in 90% of PSS assisted surgeries with associated reflux in 70% of the cases. With manual surgery, bleb formation was succesful in 50% of the cases, and reflux was noted in 80%. In manual surgery, mean tremor was 55 μm (SD 40 μm), mean drift was 256 μm (SD 103 μm) and mean subretinal injection time was 25 sec (SD 9 sec). In robot-assisted surgery, mean tremor was 3 μm (SD 2 μm), mean drift was 25 μm (SD 23 μm) and mean subretinal injection time was 50 sec (SD 23 sec).Conclusions: Robotic assistance increases subretinal injection success in this in vitro model with higher rate of bleb formation and lower rate of reflux compared to manual surgery. The use of the PSS is also associated with improvement in the depth precision, the ability to remain a non-limited time into the subretinal space and the possibility to use an iOCT to guide the injection process which allows a better control of subretinal delivery .Theme: New Drug Treatment and Technologyinfo:eu-repo/semantics/nonPublishe

Advantages of subretinal delivery by robotic assistance over a manual approach

Purpose: Robotics provides high positional stability as well as micrometer precision and accuracy in XYZ. It also removes any time constraint on drug delivery within the subretinal space. Hence, the delivery procedure can be analyzed and optimized using appropriate imaging techniques and its performance compared to manual surgery.Materials and Methods: Freshly harvested porcine eyes were used for the initial studies. A standard pars plana vitrectomywith IOP control was performed under microscopic visualization through a Zeiss Rescan 700. Subsequently, subretinal injection using a 41G Teflon needle, was executed with or without the Preceyes Surgical System (PSS). The following parameters were recorded: absence of a Bruch’s membrane breech, initiation success and duration to subretinal bleb creation. Surgical iOCT and microscopic recording where analyzed and categorized after completion of the surgery. Surgical success was defined as a creation of a subretinal bleb confirmed by intraoperative oct, while avoiding reflux.Results: No breech of Bruch’s membrane was observed using either manual or robotic assistance. While static positioning was possible manually in the subretinal space, repeated contact with Bruch’s was observed due to physiologic hand tremor. There was no motion while using the PSS. Surgical success was achievedin 80% of PSS assisted surgeries (blebs creation in 100%, with leakage in 20% at the time of retraction). With manual surgery, leakage was observed in all cases, in only 40% of cases could a bleb be successfully created. Leakage was observed at all stages of bleb initiation, injection and retraction of the needle. Time involved in bleb generation was longer while using the PSS which may have bearing on the success.Conclusions: Robotics allows for a more controlled access to the subretinal space, minimizes the risk of reflux, during the injection process or on retraction of the needle. PSS also allowed for realtime use of an iOCT to guide the injection process.info:eu-repo/semantics/publishe

Defining parameters for robotic or manual reflux-free subretinal injections in an ex vivo animal model

Purpose :To define parameters of success for reflux-free subretinal injection using an assistive robotic system versus manual surgery.Methods :Ten freshly harvested porcine eyes underwent a standard pars plana vitrectomy with IOP control under microscopic visualization through a Rescan 700 Zeiss device; followed by subretinal injection using a 41G Teflon needle, with or without the Preceyes Surgical System (PSS). The following parameters were recorded: absence of a Bruch's membrane breach, initiation success and duration to subretinal bleb creation. Surgical iOCT and microscopic recording where analyzed and categorized after completion of the surgery. Surgical success was defined as a creation of a subretinal bleb confirmed by intraoperative oct, while avoiding reflux.Results :No breach of Bruch's membrane was observed using either manual or robotic assistance. While static positioning was possible manually in the subretinal space, repeated contact with Bruch's was observed due to physiologic hand tremor. There was no motion while using the PSS. Surgical success was achieved in 80% of PSS assisted surgeries (blebs creation in 100%, with leakage in 20% at the time of retraction). With manual surgery, leakage was observed in all cases, in only 40% of cases could a bleb be successfully created. Leakage was observed at all stages of bleb initiation, injection and retraction of the needle. Time involved in bleb generation was longer while using the PSS which may have bearing on the success.Conclusions :Subretinal injection using an assistive robotic system reduces the incidence of reflux and increases the rate of successful bleb formation in this porcine model. The model appears appropriate to study parameters involved in bleb formation and dynamics such as pump flow, duration of injection, and needle design.info:eu-repo/semantics/publishe

A model system to define injection pressure and flow characteristics during subretinal drug delivery

Purpose :The risk of retinal, RPE damage and vitreous reflux increases with increased injection pressure during subretinal injections. Using a model chamber in which injection and chamber pressure can be modulated, this study aims to identify the optimal injection characteristics for subretinal drug delivery.Methods :A 38 G outer diameter subretinal injection cannula proximally attached to a MicroDose™ Injection device filled with colored water was inserted through a 23 G valved trocar into a 38 cm3 closed chamber with a defined inner pressure generated by an external compressor. The foot pedal-controlled viscous fluid injection (VFI) modes of two different vitrectomy systems (R-Evolution™ CR from BVI-Optikon and Stellaris Elite™ from Bausch and Lomb) were used to inject the solution with an injection pressure ranging from 1 to 50 psi with predefined chamber pressures of 10 ,20 and 30 mm Hg. Each injection was recorded using a video recording system. The following parameters were analyzed :pressure recording in the model, injection pressure, velocity of the injected solution, presence of an unintentional flow after release of the foot pedal.Results :The predefined pressure recorded inside the model was constant and unaffected by the different injections pressure levels chosen on the VFI. A minimal pressure of 6 psi was needed to generate a flow inside our model. From 6 to 9 psi, the velocity of the flow was categorized as slow. Higher than 10 psi, we observed a flow with high exit velocity (figure). In all cases, a persistent flow was observed after releasing the foot pedal in VFI mode. The quantity of fluid increased when increasing the level pressure of injection.Conclusions :Increased Injection pressure are associated with less controlled, high exit velocity flow characteristics. The model appears appropriate to study flow control and its possible role in RPE loss in the context of gene therapyinfo:eu-repo/semantics/publishe

Release of experimental retinal vein occlusions by direct intraluminal injection of ocriplasmin

\u3cp\u3ePurpose Retinal vein occlusions (RVO) are a major cause of vision loss in people aged 50years and older. Current therapeutic options limit the consequences of RVO but do not eliminate the cause. Cannulation of the involved vessel and removal of the clot may provide a more permanent solution with a less demanding follow-up. However, cannulation of smaller retinal veins remains challenging. This paper explores the use of ocriplasmin (recombinant plasmin without its kringles) to clear RVO, using a robotic micromanipulator. Methods Branch RVO were induced in a porcine model with rose bengal followed by 532nm endolaser to the superior venous branch of the optic nerve. The vein was cannulated proximal to the occlusion or beyond the first branching vessel from the obstruction. The vein was infused with a physiologic citric acid buffer solution (CAM) or CAM/ocriplasmin. The time of cannulation, number of attempts, and the ability to release the thrombus were recorded. Results Cannulation and infusion was possible in all the cases. The use of a micromanipulator allowed for a consistent cannulation of the retinal vein and positional stability allowed the vein to remain cannulated for up to 20min. In none of the attempts (5/5) with CAM did the thrombus dissolve, despite repeat infusion/relaxation cycles. In 7/7 injections of CAM/ocriplasmin near to the point of obstruction, the clot started to dissolve within a few minutes of injection. An infusion, attempted beyond the first venous branch point proximal to the clot, was unsuccessful in 2/3 attempts. Conclusions Ocriplasmin is effective in resolving RVO if injected close to the site of occlusion with the use of a micromanipulator.\u3c/p\u3

Robotic Assisted Cannulation of Occluded Retinal Veins.

PURPOSE: To develop a methodology for cannulating porcine retinal venules using a robotic assistive arm after inducing a retinal vein occlusion using the photosensitizer rose bengal. METHODOLOGY: Retinal vein occlusions proximal to the first vascular branch point were induced following intravenous injection of rose bengal by exposure to 532nm laser light delivered by slit-lamp or endolaser probe. Retinal veins were cannulated by positioning a glass catheter tip using a robotically controlled micromanipulator above venules with an outer diameter of 80μm or more and performing a preset piercing maneuver, controlled robotically. The ability of a balanced salt (BSS) solution to remove an occlusion by repeat distention of the retinal vein was also assessed. RESULTS: Cannulation using the preset piercing program was successful in 9 of 9 eyes. Piercing using the micromanipulator under manual control was successful in only 24 of 52 attempts, with several attempts leading to double piercing. The best location for cannulation was directly proximal to the occlusion. Infusion of BSS did not result in the resolution of the occlusion. CONCLUSION: Cannulation of venules using a robotic microassistive arm can be achieved with consistency, provided the piercing is robotically driven. The model appears robust enough to allow testing of therapeutic strategies aimed at eliminating a retinal vein thrombus and its evolution over time

Ex-vivo experiments with a microrobotic surgical system for vitreo-retinal surgery

Purpose:Developments in vitreo-retinal eye surgery are limited by human capabilities. To improve current vitreo-retinal surgical procedures and to enable new procedures, a robotic system has been developed, extending human capabilities. Methods:A compact, lightweight, easy to setup robotic master-slave system has been realized to perform vitreo-retinal eye surgery (Slave see Figure 1, Master see Figure 2). The system’s reach covers the major part of the vitreous cavity (up to the peripheral region). A combination of advanced mechanical and control design facilitates high accuracy