The Fate of RPE Cells Following hESC-RPE Patch Transplantation in Haemorrhagic Wet AMD: Pigmentation, Extension of Pigmentation, Thickness of Transplant, Assessment for Proliferation and Visual Function-A 5 Year-Follow Up.

(1) Background: We reviewed a stem cell-derived therapeutic strategy for advanced neovascular age-related macular degeneration (nAMD) using a human embryonic stem cell-derived retinal pigment epithelium (hESC-RPE) monolayer delivered on a coated, synthetic basement membrane (BM)-the patch-and assessed the presence and distribution of hESC-RPE over 5 years following transplantation, as well as functional outcomes. (2) Methods: Two subjects with acute vision loss due to sub-macular haemorrhage in advanced nAMD received the hESC-RPE patch. Systematic immunosuppression was used peri-operatively followed by local depot immunosuppression. The subjects were monitored for five years with observation of RPE patch pigmentation, extension beyond the patch boundary into surrounding retina, thickness of hESC-RPE and synthetic BM and review for migration and proliferation of hESC-RPE. Visual function was also assessed. (3) Results: The two study participants showed clear RPE characteristics of the patch, preservation of some retinal ultrastructure with signs of remodelling, fibrosis and thinning on optical coherence tomography over the 5-year period. For both participants, there was evidence of pigment extension beyond the patch continuing until 12 months post-operatively, which stabilised and was preserved until 5 years post-operatively. Measurement of hESC-RPE and BM thickness over time for both cases were consistent with predefined histological measurements of these two layers. There was no evidence of distant RPE migration or proliferation in either case beyond the monolayer. Sustained visual acuity improvement was apparent for 2 years in both subjects, with one subject maintaining the improvement for 5 years. Both subjects demonstrated initial improvement in fixation and microperimetry compared to baseline, at year 1, although only one maintained this at 4 years post-intervention. (4) Conclusions: hESC-RPE patches show evidence of continued pigmentation, with extension, to cover bare host basement membrane for up to 5 years post-implantation. There is evidence that this represents functional RPE on the patch and at the patch border where host RPE is absent. The measurements for thickness of hESC-RPE and BM suggest persistence of both layers at 5 years. No safety concerns were raised for the hypothetical risk of RPE migration, proliferation or tumour formation. Visual function also showed sustained improvement for 2 years in one subject and 5 years in the other subject.

Trocar localisation for robot-assisted vitreoretinal surgery.

PURPOSE: Robot-assisted vitreoretinal surgery provides precise and consistent operations on the back of the eye. To perform this safely, knowledge of the surgical instrument's remote centre of motion (RCM) and the location of the insertion point into the eye (trocar) is required. This enables the robot to align both positions to pivot the instrument about the trocar, thus preventing any damaging lateral forces from being exerted. METHODS: Building on a system developed in previous work, this study presents a trocar localisation method that uses a micro-camera mounted on a vitreoretinal surgical forceps, to track two ArUco markers attached on either side of a trocar. The trocar position is the estimated midpoint between the markers. RESULTS: Experimental evaluation of the trocar localisation was conducted. Results showed an RMSE of 1.82 mm for the localisation of the markers and an RMSE of 1.24 mm for the trocar localisation. CONCLUSIONS: The proposed camera-based trocar localisation presents reasonable consistency and accuracy and shows improved results compared to other current methods. Optimum accuracy for this application would necessitate a 1.4 mm absolute error margin, which corresponds to the trocar's radius. The trocar localisation results are successfully found within this margin, yet the marker localisation would require further refinement to ensure consistency of localisation within the error margin. Further work will refine these position estimates and ensure the error stays consistently within this boundary.

Safety profile and surgical outcomes of early vitrectomy in eyes with unexplained fundus-obscuring vitreous haemorrhage.

OBJECTIVES: To investigate the safety profile and the surgical outcomes in a large cohort of subjects undergoing early vitrectomy for unexplained fundus-obscuring vitreous haemorrhage (FOVH). METHODS: Retrospective, single-centre case series of 186 consecutive eyes presenting between January 2018 and February 2020. Primary outcomes included change in best-corrected visual acuity (BCVA), rate of intra-operative retinal tears or retinal detachment (RD), baseline proliferative vitreoretinopathy (PVR), association of demographics with clinical outcomes, and rate of significant adverse events characterised by reoperation. RESULTS: Main final diagnosis was haemorrhagic posterior vitreous detachment (76%) and the overall risk of a retinal tear with or without RD found at the time of surgery was 69%. Vitrectomy was completed within 24 h in 94% of eyes. Rate of RD was 18%; all cases were macula-sparing with no PVR. Mean change in BCVA from baseline to final follow-up was -1.53 ± 0.69 LogMAR, p < 0.001. Time from presentation to surgery was significantly associated with final BCVA (p = 0.036, beta co-efficient 0.097). There was a significant association between presence of RD and age <60 y (OR 0.94, 95%CI [0.90-0.98], p = 0.003). 4.8% required repeated vitrectomy for post-operative RD (4), epiretinal membrane formation (3), removal of oil (1), and recurrent FOVH (1). None of these reoperations were induced by complications during the first surgery. CONCLUSION: There is a high rate of retinal breaks in cases with unexplained FOVH, and the risk of a concomitant RD is higher in younger subjects. Early vitrectomy within 24 h appears a safe first-line treatment and yields good clinical outcomes.

Surgical biomicroscopy-guided intra-operative optical coherence tomography (iOCT) image super-resolution.

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. METHODS: To overcome the absence of ground truth high-resolution (HR) images, we first generate HR iOCT images by fusing spatially aligned iOCT video frames. Then, we automatically assess the quality of the HR images on key retinal layers using a deep semantic segmentation model. Finally, we use image-to-image translation models (Pix2Pix and CycleGAN) to enhance the quality of LR images via quality transfer from the estimated HR domain. RESULTS: Our proposed methodology generates iOCT images of improved quality according to both full-reference and no-reference metrics. A qualitative study with expert clinicians also confirms the improvement in the delineation of pertinent layers and in the reduction of artefacts. Furthermore, our approach outperforms conventional denoising filters and the learning-based state-of-the-art. CONCLUSIONS: The results indicate that the learning-based methods using the estimated, through our pipeline, HR domain can be used to enhance the iOCT image quality. Therefore, the proposed method can computationally augment the capabilities of iOCT imaging helping this modality support the vitreoretinal surgical interventions of the future.

Gripe-Needle: A Sticky Suction Cup Gripper Equipped Needle for Targeted Therapeutics Delivery.

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 Gripe-Needle, 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. As a result, there will be no need for an independent gripper arm for an incision task. The CTR innermost tube is equipped with a needle, providing the pathway for drug delivery, and the immediate outer tube is attached to the suction cup, providing the suction pathway. Based on experiments on various materials, we observed that adding a sticky surface with bio-inspired grooves to a normal suction cup gripper has many advantages such as, 1) enhanced adhesion through material stickiness and by air-tightening the contact surface, 2) maintained adhesion despite internal pressure variations, e.g. due to the needle motion, and 3) sliding resistance. Simple Finite Element and theoretical modeling frameworks are proposed, based on which a miniature tool-set is designed to achieve the required gripping forces during ONSF. The final designs were successfully tested for accessing the optic nerve of a realistic eye phantom in a skull eye orbit, robust gripping and incision on units of a plastic bubble wrap sample, and manipulating different tissue types of porcine eye samples.

Contemporary Outcomes and Prognostic Factors of 23-Gauge Vitrectomy for Retained Lens Fragments After Phacoemulsification.

PURPOSE: To provide data on visual acuity (VA) outcomes and prognostic factors of microincision (23-gauge) vitrectomy surgery (MIVS) for retained lens fragments after complicated cataract surgery. DESIGN: Retrospective, interventional case series from 2012 to 2017. METHODS: Precataract surgery and intraoperative (vitrectomy) parameters, postvitrectomy complications, and best-corrected visual acuities (BCVAs) were identified. Vitrectomy was performed as early as corneal clarity permitted. Univariate and multivariate logistic regression were used to characterize factors associated with achieving VA better than 20/40, or worse than 20/200 at 6 months. RESULTS: This study included 291 consecutive eyes (291 patients). LogMAR BCVA improved from 0.73 ± 0.70 before cataract surgery to 0.46 ± 0.63 (P < .001) after vitrectomy. The previtrectomy VA was 1.43 ± 0.79. At 6 months, 183 (62.9%) and 45 patients (15.5%) achieved BCVAs better than 20/40 and worse than 20/200, respectively. Most frequent complications were de novo ocular hypertension (29 eyes, 10%) and transient cystoid macular edema (25 eyes, 8.6%). Postvitrectomy retinal detachment occurred in 9 eyes (3.1%). Final VA of 20/40 or better was independently associated only with better precataract surgery VA, age <75 years, absence of preexisting diabetic macular edema (DME) or postvitrectomy persistent cystoid macular edema (P < .05). Only poorer precataract surgery VA, delaying vitrectomy to later than 2 weeks, and final aphakic status were independently predictive of 20/200 or worse VA (P < .05). CONCLUSION: Contemporary VA outcomes of 23-gauge vitrectomy for retained lens fragments are comparable with that of prior predominantly non-MIVS cohorts, but fall short of benchmarks for uncomplicated cataract surgery. IOL type or timing of placement do not impact final VA.

Deep iterative vessel segmentation in OCT angiography.

This paper addresses retinal vessel segmentation on optical coherence tomography angiography (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 Superficial Vascular Plexus 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.

Learned optical flow for intra-operative tracking of the retinal fundus.

PURPOSE: Sustained delivery of regenerative retinal therapies by robotic systems requires intra-operative tracking of the retinal fundus. We propose a supervised deep convolutional neural network to densely predict semantic segmentation and optical flow of the retina as mutually supportive tasks, implicitly inpainting retinal flow information missing due to occlusion by surgical tools. METHODS: As manual annotation of optical flow is infeasible, we propose a flexible algorithm for generation of large synthetic training datasets on the basis of given intra-operative retinal images. We evaluate optical flow estimation by tracking a grid and sparsely annotated ground truth points on a benchmark of challenging real intra-operative clips obtained from an extensive internally acquired dataset encompassing representative vitreoretinal surgical cases. RESULTS: The U-Net-based network trained on the synthetic dataset is shown to generalise well to the benchmark of real surgical videos. When used to track retinal points of interest, our flow estimation outperforms variational baseline methods on clips containing tool motions which occlude the points of interest, as is routinely observed in intra-operatively recorded surgery videos. CONCLUSIONS: The results indicate that complex synthetic training datasets can be used to specifically guide optical flow estimation. Our proposed algorithm therefore lays the foundation for a robust system which can assist with intra-operative tracking of moving surgical targets even when occluded.

ADVERSE EVENTS OF THE ARGUS II RETINAL PROSTHESIS: Incidence, Causes, and Best Practices for Managing and Preventing Conjunctival Erosion.

PURPOSE: To analyze and provide an overview of the incidence, management, and prevention of conjunctival erosion in Argus II clinical trial subjects and postapproval patients. METHODS: This retrospective analysis followed the results of 274 patients treated with the Argus II Retinal Prosthesis System between June 2007 and November 2017, including 30 subjects from the US and European clinical trials, and 244 patients in the postapproval phase. Results were gathered for incidence of a serious adverse event, incidence of conjunctival erosion, occurrence sites, rates of erosion, and erosion timing. RESULTS: Overall, 60% of subjects in the clinical trial subjects versus 83% of patients in the postapproval phase did not experience device- or surgery-related serious adverse events. In the postapproval phase, conjunctival erosion had an incidence rate of 6.2% over 5 years and 11 months. In 55% of conjunctival erosion cases, erosion occurred in the inferotemporal quadrant, 25% in the superotemporal quadrant, and 20% in both. Sixty percent of the erosion events occurred in the first 15 months after implantation, and 85% within the first 2.5 years. CONCLUSION: Reducing occurrence of conjunctival erosion in patients with the Argus II Retinal Prosthesis requires identification and minimization of risk factors before and during implantation. Implementing inverted sutures at the implant tabs, use of graft material at these locations as well as Mersilene rather than nylon sutures, and accurate Tenon's and conjunctiva closure are recommended for consideration in all patients.

Intraocular Biopsy and ImmunoMolecular Pathology for "Unmasking" Intraocular Inflammatory Diseases.

Intraocular inflammation can hide a variety of eye pathologies. In 33% of cases, to obtain a correct diagnosis, investigation of the intraocular sample is necessary. The combined analyses of the intraocular biopsy, using immuno-pathology and molecular biology, point to resolve the diagnostic dilemmas in those cases where history, clinical tests, and ophthalmic and systemic examinations are inconclusive. In such situations, the teamwork between the ophthalmologist and the molecular pathologist is critically important to discriminate between autoimmune diseases, infections, and intraocular tumors, including lymphoma and metastases, especially in those clinical settings known as masquerade syndromes. This comprehensive review focuses on the diagnostic use of intraocular biopsy and highlights its potential to enhance research in the field. It describes the different surgical techniques of obtaining the biopsy, risks, and complication rates. The review is organized according to the anatomical site of the sample: I. anterior chamber containing aqueous humor, II. iris and ciliary body, III. vitreous, and IV. choroid and retina. We have excluded the literature concerning biopsy for choroidal melanoma and retinoblastoma, as this is a specialized area more relevant to ocular oncology.

Optic Disc Pit Maculopathy: New Perspectives on the Natural History.

PURPOSE: To investigate the natural history of optic disc pit maculopathy and explore the associations between demographic, anatomic, and functional characteristics. DESIGN: Retrospective, comparative case series. METHODS: This was a single-center medical record review of previously untreated optic disc pit maculopathy. Baseline data of visual function, demographics, and pit physiognomy were collected, and further subgroup analysis was undertaken on patients with long-term follow-up, according to whether they were monitored or received surgical intervention. LogMAR visual acuity was the primary outcome measure, and anatomic characteristics were reported where available. RESULTS: Eighty-seven patients were identified with a new presentation of optic disc pit maculopathy. No demographic or pit features were correlated with vision at baseline. In 51 patients with available optical coherence tomography data, only the presence of subretinal fluid at baseline was associated with poorer visual acuity (P < .001). Fifty-two patients who were monitored without treatment had available long-term follow-up data. The mean change in visual acuity in this group was 0.01, with 77% maintaining visual acuity ≤0.30. Twenty-seven patients underwent surgery and showed significant postoperative improvement in vision (P < .001), with 59% achieving an acuity ≤0.30. Duration of postoperative follow-up was associated with better visual acuity (P = .007). CONCLUSION: Many patients with optic disc pit maculopathy maintain good long-term visual acuity and may demonstrate resolution of subretinal fluid in the absence of surgical intervention. There may be evidence to support delaying surgical treatment until visual deterioration is observed because of the potential stability or spontaneous improvement of the condition, the high rate of reoperation, and the long-term positive outcomes of deferred intervention.

Descemet Membrane Endothelial Keratoplasty (DMEK) Graft Dislocation Into the Vitreous Cavity.

PURPOSE: To present our experience of Descemet stripping endothelial keratoplasty (DMEK) graft luxation into the vitreous cavity in 2 cases. METHODS: DMEK was performed in 2 patients with aphakic bullous keratopathy. The indications for keratoplasty were endothelial failure caused by chronic intermediate uveitis and glaucoma in 1 case and decompensated previous penetrating keratoplasty in the other. Both cases had enlarged pupils and had previously undergone pars plana vitrectomy. In both cases, the DMEK graft dislocated into the vitreous cavity during unfolding maneuvers and could not be retrieved during the same procedure. RESULTS: No signs of retinal detachment were observed during follow-up (6 months and 1 year). Although visualization of the graft was not possible on examination, B-scan confirmed the presence of the lenticule lying over the retina. One case underwent repeat DMEK, and 1 case underwent repeat penetrating keratoplasty. In 1 case, the graft was retrieved after a month and sent for histopathology. In both cases, corneal transparency and corrected visual acuity improved to full potential after the final procedure. Histopathology of the retrieved graft showed only endothelial cell loss and no fibrocellular proliferation. CONCLUSIONS: The risk of fibrous proliferation and retinal detachment after posterior dislocation of DMEK grafts may be less than in grafts including corneal stroma, but pars plana vitrectomy and retrieval of the dislocated corneal transplant are still indicated after revision corneal transplant surgery where visual symptoms or signs of fibrotic change around the dislocated graft are evident.

Phase 1 clinical study of an embryonic stem cell-derived retinal pigment epithelium patch in age-related macular degeneration.

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.

Stem cell-derived retinal pigment epithelium transplantation for treatment of retinal disease.

Age-related macular degeneration remains the most common cause of blindness in the western world, severely comprising patients' and carers' quality of life and presenting a great cost to the healthcare system. As the disease progresses, the retinal pigmented epithelium (RPE) layer at the back of the eye degenerates, contributing to a series of events resulting in visual impairment. The easy accessibility of the eye has allowed for in-depth study of disease progression in patients, while in vivo studies have facilitated investigations into healthy and diseased RPE. Consequently, a number of research groups are examining different approaches for the replacement of RPE cells in age-related macular degeneration (AMD) patients. This chapter examines some of these initial proof-of-principle studies and goes on to review the use of pluripotent stem cells as a source for RPE replacement in a number of current AMD clinical trials. Finally, we consider just some of the regulatory and manufacturing challenges presented in taking a promising AMD treatment from the research bench into clinical trials in patients, and how to mitigate potential risks early in process development.

Rescue of the MERTK phagocytic defect in a human iPSC disease model using translational read-through inducing drugs.

Inherited retinal dystrophies are an important cause of blindness, for which currently there are no effective treatments. In order to study this heterogeneous group of diseases, adequate disease models are required in order to better understand pathology and to test potential therapies. Induced pluripotent stem cells offer a new way to recapitulate patient specific diseases in vitro, providing an almost limitless amount of material to study. We used fibroblast-derived induced pluripotent stem cells to generate retinal pigment epithelium (RPE) from an individual suffering from retinitis pigmentosa associated with biallelic variants in MERTK. MERTK has an essential role in phagocytosis, one of the major functions of the RPE. The MERTK deficiency in this individual results from a nonsense variant and so the MERTK-RPE cells were subsequently treated with two translational readthrough inducing drugs (G418 & PTC124) to investigate potential restoration of expression of the affected gene and production of a full-length protein. The data show that PTC124 was able to reinstate phagocytosis of labeled photoreceptor outer segments at a reduced, but significant level. These findings represent a confirmation of the usefulness of iPSC derived disease specific models in investigating the pathogenesis and screening potential treatments for these rare blinding disorders.

Identification and Correction of Mechanisms Underlying Inherited Blindness in Human iPSC-Derived Optic Cups.

Leber congenital amaurosis (LCA) is an inherited retinal dystrophy that causes childhood blindness. Photoreceptors are especially sensitive to an intronic mutation in the cilia-related gene CEP290, which causes missplicing and premature termination, but the basis of this sensitivity is unclear. Here, we generated differentiated photoreceptors in three-dimensional optic cups and retinal pigment epithelium (RPE) from iPSCs with this common CEP290 mutation to investigate disease mechanisms and evaluate candidate therapies. iPSCs differentiated normally into RPE and optic cups, despite abnormal CEP290 splicing and cilia defects. The highest levels of aberrant splicing and cilia defects were observed in optic cups, explaining the retinal-specific manifestation of this CEP290 mutation. Treating optic cups with an antisense morpholino effectively blocked aberrant splicing and restored expression of full-length CEP290, restoring normal cilia-based protein trafficking. These results provide a mechanistic understanding of the retina-specific phenotypes in CEP290 LCA patients and potential strategies for therapeutic intervention.