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Development of surgical assistive technology for intraocular microsurgery

Our eyesight is by far our most developed sense, playing a vital role in nearly all aspects of everyday life. As such, severe vision loss can have a devastating impact on one’s life. Advancements in medicine have led to effective treatment methods for a substantial range of eye diseases. Nevertheless, several retinal disorders remain a common cause of vision loss. At the time of writing, an estimated 244 million people worldwide suffer from a form of severe vision impairment for which no curative treatment exist.

Innovative drug developments and advanced imaging techniques may enable potentially curative surgical treatment methods. However, due to the scale and fragility of the retina, vitreoretinal surgery is already being performed at the limits of human physiological performance. Unintended motions such as hand tremor and eye rotations constrain the precision of any surgical technique. Due to this, advancements which may lead to potential cures are either limited or left untested. In order to overcome these physiological limitations, surgeons require the clinical availability of performance-enhancing technology.

The aim of this doctoral work is to further advance the technology for vitreoretinal surgery in order to enable the creation and safe application of novel treatment methods. This, in turn, seeks to contribute to our ability in limiting or ultimately preventing unnecessary human suffering caused by untreatable vision impairment. The research efforts described in this dissertation can be summarized as two-fold.

The first part of this dissertation reports on the design, development, preclinical validation, and clinical translation of a first generation of clinically viable robot-assisted technology for retinal surgery. Building further on prior research efforts, two surgical robotic systems were completed and cleared for clinical investigative use during in-human studies. Both versions of the developed technology provide equivalent performance in providing three key functionalities: eye stabilisation via a mechanical RCM, precision enhancement via impedance-type force-scaling, and prolonged instrument immobilisation via mechanical locking of the mechanism. Subsequently, the use of the developed technology during clinical translational research is described. Firstly, robot-assisted REVS on treating CRVO is described within the context of a first-in-human clinical study. In all cases the surgeon was able to successfully inject the targeted retinal vein. The conducted in-human clinical study demonstrated a world first, and sets a valuable precedent for future research. Furthermore, robot-assisted subretinal surgery on RPE replacement therapy is described. Initial in-animal results demonstrate the feasibility of robot-assisted subretinal injections with the aid of the developed technology. Overall, robotic technology shows great promise within the context of subretinal surgery, and may prove to be a key asset in enabling effective cell- and gene-therapies for retinal disorders.

The second part of this dissertation builds further on the gathered clinical experience. Three concerns related to robot-assisted vitreoretinal surgery are identified and addressed. First, hands-on repositioning of the RCM during surgery is addressed. A general approach relying on anatomy-based haptic fixtures is introduced seeking to simplify and improve RCM positioning during robot-assisted surgery. The development of a dedicated robotic setup and fixture mechanism is reported, along with an initial feasibility study. Second, the concern of limited intraocular workspace, excess tool holder volume, and compatibility with conventional surgical instruments is addressed. The synthesis of a parallel Remote Center of Motion mechanism is reported, along with an optimized design for the use-case of eye surgery. For this purpose, a numerical optimal design algorithm is proposed and implemented, based on which a kinematic re-design is suggested. Third, a solution addressing the limited perception of instrument-tissue interaction forces as well as depth estimation during instrument motion close to the retina is explored. The development of a novel combined force and distance sensing cannulation needle is reported, along with in-vivo and ex-vivo lab characterisation. Subsequently, feasibility of using the sensor in-vivo was further validated on an animal model.

Overall, this work marks a step forward on the path towards robot-assisted retinal therapy. Surgeons were enabled to investigate the potential of robotic assistance during first-in-human research. These clinical translational efforts are major advancements within the field of robot-assisted eye surgery. Initial outcomes are highly promising, and encourage further research towards establishing innovative treatments. Furthermore, this work describes advancements towards a next generation of robotic technology. Contributions were made to the state-of-the-art on surgical robotic systems, guidance fixtures, RCM mechanisms, kinematic design, and sensorized surgical instrumentation.

Date:8 Sep 2015 →  31 Dec 2020
Keywords:Robotics, Vitreoretinal surgery, Medical Technology, Eye Surgery, Retinal Vein Occlusion, Subretinal Surgery
Disciplines:Design theories and methods, Mechanics, Other mechanical and manufacturing engineering, Biological system engineering, Biomaterials engineering, Biomechanical engineering, Medical biotechnology, Other (bio)medical engineering
Project type:PhD project