Publications by authors named "Christos Bergeles"

Endovascular interventions are a life-saving treatment for many diseases, but they suffer from drawbacks such as radiation exposure and the potential scarcity of proficient physicians. Robotic assistance during these interventions could be a promising support for these problems. Research focusing on autonomous endovascular interventions using artificial intelligence-based methodologies is gaining popularity.

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Common-path low-coherence interferometry enables high-resolution distance measurements to be made via thin fiber-optic probes. This is particularly advantageous for applications such as ophthalmic vitreoretinal microsurgery, where the probes can be used to precisely locate the position of surgical tools relative to the retinal surface, but could also have a wide range of other medical and industrial applications. The performance of the fiber probes depends critically on the fabrication of a focusing lens at the distal tip and on creating a medium-independent partial reflection that is used for common-path interferometry.

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Objective: The primary objective was to determine which of the following angular insertion depth (AID) estimation methods had the strongest correlation with the post-operative AID (AIDpost-op) of a lateral wall (LW) electrode: 1) Escudé formula based on the largest distance from the round window (RW) to the LW (distance A), 2) the elliptic-circular approximation (ECA) method based on both distance A and the perpendicular distance (distance B), 3) a 3D reconstruction method. The secondary objective was to evaluate the impact of using the actual electrode insertion length on the evaluation of the AID estimation methods.

Methods: The study included 45 cochleae implanted with the Advanced Bionics SlimJ electrode, with all 16 active electrode contacts being intracochlear.

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The performance and scope of computer vision methods applied to ophthalmic images is highly dependent on the availability of labelled training data. While there are a number of colour fundus photography datasets, FOVEA is to the best of our knowledge the first dataset that matches high-quality annotations in the intraoperative domain with those in the preoperative one. It comprises data from 40 patients collected at Moorfields Eye Hospital (London, UK) and includes preoperative and intraoperative retinal vessel and optic disc annotations performed by two independent clinical research fellows, as well as short video clips showing the retinal fundus though biomicroscopy imaging in the intraoperative setting.

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In this study, we introduce a novel shared-control system for key-hole docking operations, combining a commercial camera with occlusion-robust pose estimation and a hand-eye information fusion technique. This system is used to enhance docking precision and force-compliance safety. To train a hand-eye information fusion network model, we generated a self-supervised dataset using this docking system.

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Background: Predicting diabetic retinopathy (DR) progression could enable individualised screening with prompt referral for high-risk individuals for sight-saving treatment, whilst reducing screening burden for low-risk individuals. We developed and validated deep learning systems (DLS) that predict 1, 2 and 3 year emergent referable DR and maculopathy using risk factor characteristics (tabular DLS), colour fundal photographs (image DLS) or both (multimodal DLS).

Methods: From 162,339 development-set eyes from south-east London (UK) diabetic eye screening programme (DESP), 110,837 had eligible longitudinal data, with the remaining 51,502 used for pretraining.

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Regenerative therapies show promise in reversing sight loss caused by degenerative eye diseases. Their precise subretinal delivery can be facilitated by robotic systems alongside with Intra-operative Optical Coherence Tomography (iOCT). However, iOCT's real-time retinal layer information is compromised by inferior image quality.

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Article Synopsis
  • - In aortic valve surgery, a robotic platform called ValveTech is used to replace damaged valves with artificial ones through a combination of teleoperation and endoscopic vision.
  • - The system involves advanced technology that includes a force observer to monitor the manipulation forces and a hybrid mechanics approach for precise, autonomous valve positioning, achieving minimal positional errors.
  • - Experiments show the ValveTech platform can enhance patient care and surgical outcomes, providing better delivery accuracy without needing sensors on the robotic tip, which simplifies its design.
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Scalar translocation is a severe form of intra-cochlear trauma during cochlear implant (CI) electrode insertion. This study explored the hypothesis that the dimensions of the cochlear basal turn and orientation of its inferior segment relative to surgically relevant anatomical structures influence the scalar translocation rates of a pre-curved CI electrode. In a cohort of 40 patients implanted with the Advanced Bionics Mid-Scala electrode array, the scalar translocation group (40%) had a significantly smaller mean distance A of the cochlear basal turn (p < 0.

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Soft robot's natural dynamics calls for the development of tailored modeling techniques for control. However, the high-dimensional configuration space of the geometrically exact modeling approaches for soft robots, i.e.

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Purpose: The use of robotics is emerging for performing interventional radiology procedures. Robots in interventional radiology are typically controlled using button presses and joystick movements. This study identified how different human-robot interfaces affect endovascular surgical performance using interventional radiology simulations.

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Purpose: To determine associations between deprivation using the Index of Multiple Deprivation (IMD and individual IMD subdomains) with incident referable diabetic retinopathy/maculopathy (termed rDR).

Methods: Anonymised demographic and screening data collected by the South-East London Diabetic Eye Screening Programme were extracted from September 2013 to December 2019. Multivariable Cox proportional models were used to explore the association between the IMD, IMD subdomains and rDR.

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Article Synopsis
  • Robot-assisted vitreoretinal surgery allows for precise operations, requiring knowledge of the surgical instrument's remote centre of motion and trocar position to avoid damaging lateral forces during procedures.
  • A method utilizing a micro-camera mounted on surgical forceps was developed to localize the trocar by tracking ArUco markers, enabling accurate positioning.
  • The experimental results showed an RMSE of 1.24 mm for trocar localization, within the acceptable error margin for optimal accuracy, but further refinements are needed for consistent marker localization.
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Soft robots that grow through eversion/apical extension can effectively navigate fragile environments such as ducts and vessels inside the human body. This paper presents the physics-based model of a miniature steerable eversion growing robot. We demonstrate the robot's growing, steering, stiffening and interaction capabilities.

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Diabetic retinopathy (DR) at risk of vision loss (referable DR) needs to be identified by retinal screening and referred to an ophthalmologist. Existing automated algorithms have mostly been developed from images acquired with high cost mydriatic retinal cameras and cannot be applied in the settings used in most low- and middle-income countries. In this prospective multicentre study, we developed a deep learning system (DLS) that detects referable DR from retinal images acquired using handheld non-mydriatic fundus camera by non-technical field workers in 20 sites across India.

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Article Synopsis
  • The study aimed to investigate if new non-invasive diagnostic technologies can detect early nerve and retinal damage in individuals with prediabetes.
  • Participants included 75 individuals, categorized as normoglycaemic, prediabetic, or type 2 diabetic, and various diagnostic tests like OCT-A and ERG were performed to assess retinal function and structure.
  • Results showed lower retinal response amplitudes and vessel densities in prediabetic participants compared to those with normal glucose levels, indicating that early changes in retinal health may occur before the onset of noticeable retinopathy.
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Diabetic retinopathy (DR) screening images are heterogeneous and contain undesirable non-retinal, incorrect field and ungradable samples which require curation, a laborious task to perform manually. We developed and validated single and multi-output laterality, retinal presence, retinal field and gradability classification deep learning (DL) models for automated curation. The internal dataset comprised of 7743 images from DR screening (UK) with 1479 external test images (Portugal and Paraguay).

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Purpose: Intra-retinal delivery of novel sight-restoring therapies will require the precision of robotic systems accompanied by excellent visualisation of retinal layers. Intra-operative Optical Coherence Tomography (iOCT) provides cross-sectional retinal images in real time but at the cost of image quality that is insufficient for intra-retinal therapy delivery.This paper proposes a super-resolution methodology that improves iOCT image quality leveraging spatiotemporal consistency of incoming iOCT video streams.

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Current laparoscopic camera motion automation relies on rule-based approaches or only focuses on surgical tools. Imitation Learning (IL) methods could alleviate these shortcomings, but have so far been applied to oversimplified setups. Instead of extracting actions from oversimplified setups, in this work we introduce a method that allows to extract a laparoscope holder's actions from videos of laparoscopic interventions.

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Background: The manufacturing of any standard mechanical ventilator cannot rapidly be upscaled to several thousand units per week, largely due to supply chain limitations. The aim of this study was to design, verify and perform a pre-clinical evaluation of a mechanical ventilator based on components not required for standard ventilators, and that met the specifications provided by the Medicines and Healthcare Products Regulatory Agency (MHRA) for rapidly-manufactured ventilator systems (RMVS).

Methods: The design utilises closed-loop negative feedback control, with real-time monitoring and alarms.

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Artificial Intelligence has showcased clear capabilities to automatically grade diabetic retinopathy (DR) on mydriatic retinal images captured by clinical experts on fixed table-top retinal cameras within hospital settings. However, in many low- and middle-income countries, screening for DR revolves around minimally trained field workers using handheld non-mydriatic cameras in community settings. This prospective study evaluated the diagnostic accuracy of a deep learning algorithm developed using mydriatic retinal images by the Singapore Eye Research Institute, commercially available as Zeiss VISUHEALTH-AI DR, on images captured by field workers on a Zeiss Visuscout 100 non-mydriatic handheld camera from people with diabetes in a house-to-house cross-sectional study across 20 regions in India.

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Regenerative therapies have recently shown potential in restoring sight lost due to degenerative diseases. Their efficacy requires precise intra-retinal delivery, which can be achieved by robotic systems accompanied by high quality visualization of retinal layers. Intra-operative Optical Coherence Tomography (iOCT) captures cross-sectional retinal images in real-time but with image quality that is inadequate for intra-retinal therapy delivery.

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This paper presents a multi-purpose gripping and incision tool-set to reduce the number of required manipulators for targeted therapeutics delivery in Minimally Invasive Surgery. We have recently proposed the use of multi-arm Concentric Tube Robots (CTR) consisting of an incision, a camera, and a gripper manipulator for deep orbital interventions, with a focus on Optic Nerve Sheath Fenestration (ONSF). The proposed prototype in this research, called , is a needle equipped with a sticky suction cup gripper capable of performing both gripping of target tissue and incision tasks in the optic nerve area by exploiting the multi-tube arrangement of a CTR for actuation of the different tool-set units.

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