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. To address this limitation, we introduce an unpaired video super-resolution methodology for iOCT quality enhancement. A recurrent network is proposed to leverage temporal information from iOCT sequences, and spatial information from pre-operatively acquired OCT images. Additionally, a patchwise contrastive loss enables unpaired super-resolution. Extensive quantitative analysis demonstrates that our approach outperforms existing state-of-the-art iOCT super-resolution models. Furthermore, ablation studies showcase the importance of temporal aggregation and contrastive loss in elevating iOCT quality. A qualitative study involving expert clinicians also confirms this improvement. The comprehensive evaluation demonstrates our method's potential to enhance the iOCT image quality, thereby facilitating successful guidance for regenerative therapies.
The aim of this study was to investigate the repeatability of manual measurements of choroidal thickness in healthy subjects imaged on spectral domain optical coherence tomography (OCT) using the ...enhanced depth imaging (EDI) technique.
Fifty consecutive, healthy, young, adult volunteers with no known eye disease were enrolled prospectively. Two good-quality horizontal and vertical line scans through the fovea were obtained for each eye. Using the manual calipers provided by the software of the proprietary device, two experienced OCT readers measured the subfoveal choroidal thickness (SFCT) of the horizontal and vertical line scans for all eyes. The readers were masked to each other's readings. Intraobserver, interobserver, and intrasession coefficients of repeatability (CRs) were calculated.
Mean (standard deviation SD) age of the study subjects was 38 (5) years (range, 30-49 years). Mean (SD) subfoveal choroidal thickness was 332 (90) μm (right eyes) and 332 (91) μm (left eyes). Intraobserver CR was approximately 23 (95% confidence interval CI, 19-26) μm, whereas interobserver and intrasession CRs were greater at 32 (95% CI, 30-34) and 34 (95% CI, 32-36) μm, respectively. There was no significant difference in SFCT between all pairs of SFCT measurements except for the two intrasession vertical line scans.
A change of >32 μm was likely to exceed interobserver variability in SFCT. Future studies are required to estimate the repeatability of SFCT measurements in patients with chorioretinal pathology.
This article presents a medical robotic system for deep orbital interventions, with a focus on Optic Nerve Sheath Fenestration (ONSF). ONSF is a currently invasive ophthalmic surgical approach that ...can reduce potentially blinding elevated hydrostatic intracranial pressure on the optic disc via an incision on the optic nerve. The prototype is a multi-arm system capable of dexterous manipulation and visualization of the optic nerve area, allowing for a minimally invasive approach. Each arm is an independently controlled concentric tube robot collimated by a bespoke guide that is secured on the eye sclera via sutures. In this article, we consider the robot's end-effector design in order to reach/navigate the optic nerve according to the clinical requirements of ONSF. A prototype of the robot was engineered, and its ability to penetrate the optic nerve was analysed by conducting ex vivo experiments on porcine optic nerves and comparing their stiffness to human ones. The robot was successfully deployed in a custom-made realistic eye phantom. Our simulation studies and experimental results demonstrate that the robot can successfully navigate to the operation site and carry out the intervention.
Age-related macular degeneration (AMD) remains a major cause of blindness, with dysfunction and loss of retinal pigment epithelium (RPE) central to disease progression. We engineered an RPE patch ...comprising a fully differentiated, human embryonic stem cell (hESC)-derived RPE monolayer on a coated, synthetic basement membrane. We delivered the patch, using a purpose-designed microsurgical tool, into the subretinal space of one eye in each of two patients with severe exudative AMD. Primary endpoints were incidence and severity of adverse events and proportion of subjects with improved best-corrected visual acuity of 15 letters or more. We report successful delivery and survival of the RPE patch by biomicroscopy and optical coherence tomography, and a visual acuity gain of 29 and 21 letters in the two patients, respectively, over 12 months. Only local immunosuppression was used long-term. We also present the preclinical surgical, cell safety and tumorigenicity studies leading to trial approval. This work supports the feasibility and safety of hESC-RPE patch transplantation as a regenerative strategy for AMD.
Abstract Pregnancy-associated retinal diseases are conditions that may occur uniquely in pregnancy or, more commonly, general conditions that may worsen or alter during pregnancy as a result of ...hematologic, hormonal, metabolic, cardiovascular, and immunologic changes. Diabetic retinopathy (DR) is by far the most common retinal condition that is altered by pregnancy. However, there are currently no widely accepted, precise clinical guidelines regarding its management during pregnancy. At present it is not possible to predict who will regress and who will progress without treatment. Some of the variation in progression of DR in pregnancy may be a result of well-known risk factors such as hypertension or inadequate glycemic control prior to pregnancy. Other pregnancy-associated retinal diseases are relatively uncommon, and their treatments are poorly characterized. Pre-existing conditions include the white dot syndromes, such as punctuate inner choroidopathy and ocular histoplasmosis syndrome, as well as chorioretinal neovascularization from many other etiologies. Retinal and chorioretinal disorders that can arise during pregnancy include central serous chorioretinopathy and occlusive vasculopathy such as retinal artery occlusion (Purtschers-like retinopathy) and retinal vein occlusion. There remains a small group that appear to be unique to pregnancy, with pre-eclampsia– and eclampsia-associated retinopathy, disseminated intravascular coagulopathy, or amniotic fluid embolism being the best described. In angiogenic retinal diseases outside of pregnancy, the use of anti-vascular endothelial growth factor (anti-VEGF agents) has proven helpful. There are no safety data about the use of anti-VEGF agents during pregnancy, and conventionally the proposed interventions have been laser photocoagulation and systemic or intravitreal injections of steroids. Most of the literature on the treatment of pregnancy associated–chorioretinal neovascularization is anecdotal.
Concentric tube robots (CTRs) are catheter-like robots that can navigate anatomical lumen to reach surgical targets that are deep inside the body. While CTRs have been extensively studied in ...quasi-static conditions, unique robot behaviours such as hysteresis and snapping, i.e. the sudden release of elastic energy accumulated due to robot tubes' twisting, are relatively underexplored. For the first time, we present a real-time dynamic model that captures both snapping and hysteresis for CTRs with arbitrary number of tubes and precurved shape. We pursue Reduced-Order Modelling (ROM) with shape interpolation-based kinematics to reach a system of minimal states appropriate for ultimate real-time non-linear control. We implement and incorporate our theoretical contributions within the open-source modelling software package TMTDyn and make them available to the robotics community. Our method is experimentally verified using a highly curved CTR that undertakes complex 3D dynamic motions, for the first time predicting similar pathways during highly nonlinear snapping motions, which is when classical models fail, while preserving the state-of-the-art modeling accuracy of <inline-formula><tex-math notation="LaTeX">\approx</tex-math></inline-formula>6% mean error.
Concentric tube robots (CTR) can traverse tightly curved paths and offer dexterity in constrained environments, making them advantageous for minimally invasive surgical scenarios that experience ...strict anatomical and surgical constraints. Their shape is controlled via rotation and translation of several concentrically arranged super-elastic precurved tubes that form the robot backbone. As the elastic energy accumulated in the backbone due to bending and twist of the tubes increases, robots can exhibit sudden snapping motions, which can damage the surrounding tissues. In this paper, we proposed an approach for closed-loop steering of a redundant CTR that allows for snap-free motion and enhances its force/velocity manipulability, increasing the capacity of the robot to move and/or exercise forces along any direction. First, a controller stabilizes the CTR end-effector on a desired time-variant trajectory. Next, an online optimizer uses the robot's redundant Degrees of Freedom (DoF) to reshape its manipulability in real-time and steer it away from potentially snapping configurations or increase its capacity in delivering force payloads. Simulations and experiments demonstrate the performance of the proposed control strategy. The controller can steer a generally unstable CTR along trajectories while avoiding instabilities with a mean error of 850 μm, corresponding to 0.6% of arclength, and improves robot ability to exercise forces by 55%.
Background
The main objective of this study was to test Argus II subjects on three real‐world functional vision tasks.
Design
The study was designed to be randomized and prospective. Testing was ...conducted in a hospital/research laboratory setting at the various participating centres.
Participants
Twenty eight Argus II subjects, all profoundly blind, participated in this study.
Methods
Subjects were tested on the three real‐world functional vision tasks: Sock Sorting, Sidewalk Tracking and Walking Direction Discrimination task
Main Outcome Measures
For the Sock Sorting task, percentage correct was computed based on how accurately subjects sorted the piles on a cloth‐covered table and on a bare table. In the Sidewalk Tracking task, an ‘out of bounds’ count was recorded, signifying how often the subject veered away from the test course. During the Walking Direction Discrimination task, subjects were tested on the number of times they correctly identified the direction of testers walking across their field of view.
Results
The mean percentage correct OFF versus ON for the Sock Sorting task was found to be significantly different for both testing conditions (t‐test, P < 0.01). On the Sidewalk Tracking task, subjects performed significantly better with the system ON than they did with the system OFF (t‐test, P < 0.05). Eighteen (18) of 27 subjects (67%) performed above chance with the system ON, and 6 (22%) did so with system OFF on the Walking Direction Discrimination task.
Conclusions
Argus II subjects performed better on all three tasks with their systems ON than they did with their systems OFF.
This paper addresses retinal vessel segmentation on
(OCT-A) images of the human retina. Our approach is motivated by the need for high precision image-guided delivery of regenerative therapies in ...vitreo-retinal surgery. OCT-A visualizes macular vasculature, the main landmark of the surgically targeted area, at a level of detail and spatial extent unattainable by other imaging modalities. Thus, automatic extraction of detailed vessel maps can ultimately inform surgical planning. We address the task of delineation of the
in 2D Maximum Intensity Projections (MIP) of OCT-A using convolutional neural networks that iteratively refine the quality of the produced vessel segmentations. We demonstrate that the proposed approach compares favourably to alternative network baselines and graph-based methodologies through extensive experimental analysis, using data collected from 50 subjects, including both individuals that underwent surgery for structural macular abnormalities and healthy subjects. Additionally, we demonstrate generalization to 3D segmentation and narrower field-of-view OCT-A. In the future, the extracted vessel maps will be leveraged for surgical planning and semi-automated intraoperative navigation in vitreo-retinal surgery.
This letter introduces a novel 7 Degree Of Freedom (DOF) cable-driven haptic device based on the concept of a configurable cable platform. In the proposed concept, a 1-DOF pinch grasping capability ...is provided via a network of ten passive cables kept in tension. The coordinated action on the cable platform of eight active cables driven from the base, fully controls the position, orientation, and grasping configuration of the device. This constitutes the first 7-DOF cable-driven robot that is made of a network of cables instead of a pure parallel architecture. Original static and kinematic models were developed to address the particularities of the proposed architecture. They are detailed in this manuscript and used to define the workspace and the control algorithm of the design. A working prototype illustrating an implementation of the theory is presented.
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