En-face optical coherence tomography in the diagnosis and management of age-related macular degeneration and polypoidal choroidal vasculopathy

published_or_final_versio

Pigment epithelial detachment composition indices (PEDCI) in neovascular age-related macular degeneration

We provide an automated analysis of the pigment epithelial detachments (PEDs) in neovascular age related macular degeneration (nAMD) and estimate areas of serous, neovascular, and fibrous tissues within PEDs. A retrospective analysis of high-definition spectral-domain OCT B-scans from 43 eyes of 37 patients with nAMD with presence of fibrovascular PED was done. PEDs were manually segmented and then filtered using 2D kernels to classify pixels within the PED as serous, neovascular, or fibrous. A set of PED composition indices were calculated on a per-image basis using relative PED area of serous (PEDCI-S), neovascular (PEDCI-N), and fibrous (PEDCI-F) tissue. Accuracy of segmentation and classification within the PED were graded in masked fashion. Mean overall intra-observer repeatability and inter-observer reproducibility were 0.86 +/- 0.07 and 0.86 +/- 0.03 respectively using intraclass correlations. The mean graded scores were 96.99 +/- 8.18, 92.12 +/- 7.97, 91.48 +/- 8.93, and 92.29 +/- 8.97 for segmentation, serous, neovascular, and fibrous respectively. Mean (range) PEDCI-S, PEDCI-N, and PEDCI-F were 0.253 (0-0.952), 0.554 (0-1), and 0.193 (0-0.693). A kernel-based image processing approach demonstrates potential for approximating PED composition. Evaluating follow up changes during nAMD treatment with respect to PEDCI would be useful for further clinical applications

Choroidal imaging by spectral domain-optical coherence tomography

AbstractDespite the fact that the choroid plays an important role in the structure and function of the eye, it has not been studied in detail in vivo. Improvements in optical coherence tomography (OCT) imaging technology allow the routine imaging of the choroid and deep optic nerve structures in most patients. As with any new technology, it needs validation in both healthy and diseased eyes. Reproducible measurements of choroidal and lamina cribrosa thickness are possible. Several variables such as age, axial length, and time of day, affect choroidal thickness and must be taken into account when interpreting data on choroidal thickness. Lamina cribrosa thickness appears to be affected by age as well but other factors need to be determined. Choroidal thickness may be used to differentiate between central serous chorioretinopathy (CSC), polypoidal choroidal vasculopathy (PCV) and exudative age-related macular degeneration (AMD). Enhanced depth imaging-optical coherence tomography (EDI-OCT) of the choroid may detect tumors not detectable by ultrasound. Studying the choroid may help us gain insight into the pathogenesis of several diseases such as AMD, CSC, glaucoma, posteriorly located choroidal tumors, and PCV among others

Optical Coherence Tomographic Angiography Imaging in Age-Related Macular Degeneration.

Optical coherence tomographic angiography (OCTA) is emerging as a rapid, noninvasive imaging modality that can provide detailed structural and flow information on retinal and choroidal vasculature. This review contains an introduction of OCTA and summarizes the studies to date on OCTA imaging in age-related macular degeneration

IMAGING AND BIOLOGICAL MARKERS IN RETINAL DISORDERS TO ASSESS GENE THERAPY SAFETY AND INVESTIGATE VASCULAR DISEASE MECHANISMS

The retina is the neurosensory tissue responsible for the acquisition of visual stimuli. It is biologically separated from the systemic circulation by blood-retinal barriers, limiting the possibility for circulating markers to reflect retinal changes due to disease or therapeutic intervention. However, due to the transparency of ocular media, the retina is highly accessible to high-resolution imaging, and image processing provides access to physiological parameters quantitatively. In addition, the analysis of ocular media sampled during surgical procedures provides access to biological data regarding disease processes. In this work, imaging and biological markers were developed for several experimental and clinical situations: a gene therapy preclinical safety study (Project 1); the analysis of disease mechanisms in the choroical choroidal vascular disorder central serous chorioretinopathy (CSCR) (Project 2), and a similar translational approach in retinal vascular telangiectatic disorders (Project 3). Specific image processing algorithms were designed. In Project 1, the preclinical safety of a lentiviral subretinal gene therapy for RPE65 replacement in Leber congenital amaurosis, LV-RPE65, was assessed on healthy non-human primates by conventional methods (in vivo electrophysiology, ex vivo immunohistochemistry, systemic biodistribution study) combined to in vivo analysis of the retinal structure by optical coherence tomography (OCT) at different timepoints, including early follow-up within 7 days. Imaging techniques revealed a transient and pronounced inflammatory process linked to LV-RPE65 injection that delayed retinal reattachment. Partial and transient photoreceptor loss was observed in the macular region, that was to a lesser extent also observed in control eyes injected with the vehicle. This work highlights the need to improve the surgical procedure for subretinal gene therapy delivery, and to consider using anti-inflammatory agents to prevent damaging processes occurring rapidly after subretinal injection. In Project 2, mechanisms of CSCR, a retinal disease caused by choroidal vessel dilation leading to subretinal fluid accumulation, were explored. We analyzed predictive multimodal imaging factors of episode duration (2a) and recurrence (2b), evidencing in particular choroidal thickness as prognosis factor. Non-invasive OCT angiography images of the choriocapillaris, the innermost layer of the choroid beneath the retinal pigment epithelium, were processed to detect flow voids and investigate their distribution (2c). Finally, the molecular composition of subretinal fluid from a unique case of CSCR requiring subretinal surgery, was explored using a multi-omics approach (2d). In Project 3, mechanisms of retinal vasculopathy were investigated in two pure phenotypes represented by telangiectatic disorders: type 1 macular telangiectasia (Mactel 1) (3a and 3b), and radiation maculopathy (3c). For the investigation of Mactel 1, image processing tools were used to compute global and local capillary density on OCT angiography images, showing that non-perfusion is a critical feature in Mactel 1, related to visual outcome and telangiectasia formation. This approach was combined to the biological investigation of aqueous humor from Mactel 1 cases. Intraocular levels of angiogenic factors demonstrated the involvement of placental growth factor in the pathophysiology of MacTel 1, that was correlated with multimodal imaging findings (3b). Finally, an image processing algorithm was designed and applied to radiation maculopathy, to compute automatically the fractal dimension of OCT angiography images. This parameter was relevant in assessing capillary network disruption, and demonstrated that alterations of the deep plexus influence independently visual function. The strategies developed throughout these three projects demonstrate the interest of quantitative image analysis for the investigation of retinal disorders, and the possibility of coupling imaging and biological data. This approach contributed to identify potential imaging or biological markers for diagnosis, prognosis, therapeutic response and toxicity in several biomedical situations. -- La rétine est un tissu neurosensoriel responsable de l'acquisition des signaux visuels. Elle se trouve biologiquement séparée de la circulation systémique par les barrières hémato-rétiniennes, limitant la possibilité pour des marqueurs circulants de refléter des altérations du tissu rétinien, dus à des maladies ou secondaires à des interventions thérapeutiques. Cependant, en raison de la transparence des milieux oculaires, la rétine est accessible à l'imagerie haute résolution, et l’analyse d'images permet d’extraire des paramètres physiologiques quantitatifs. En outre, l'analyse des milieux oculaires prélevés au cours d’interventions chirurgicales permet d'accéder à des données biologiques concernant les processus physiopathologiques. Dans ce travail, des marqueurs biologiques et d'imagerie ont été développés pour plusieurs situations expérimentales et cliniques : une étude de sécurité préclinique en thérapie génique (Projet 1), l'analyse de mécanismes pathologiques dans la choriorétinopathie séreuse centrale (CRSC) (Projet 2), et dans les pathologies télangiectatiques vasculaires rétiniennes (Projet 3). Des algorithmes de traitement d'image spécifiques ont été conçus. Dans le Projet 1, la tolérance préclinique d'une thérapie génique sous-rétinienne lentivirale pour remplacement du gène RPE65 dans l'amaurose congénitale de Leber, LV-RPE65, a été évaluée sur des primates non humains sains par des méthodes conventionnelles (électrophysiologie in vivo, immunohistochimie ex vivo, étude de biodistribution systémique), et par analyse in vivo de la structure rétinienne par tomographie par cohérence optique (OCT) à différents points, y compris un suivi précoce dans les 7 jours. Les techniques d'imagerie ont révélé un processus inflammatoire transitoire lié à l'injection de LV-RPE65 qui a retardé le réattachement rétinien. Une perte partielle et transitoire des photorécepteurs a été observée dans la région maculaire, détécté également, et dans une moindre mesure dans les yeux témoins, injectés avec la solution véhicule. Ce travail souligne la nécessité d'améliorer la procédure chirurgicale pour l’administration de thérapies géniques sous- rétiniennes, et d'envisager l’usage d’agents anti-inflammatoires pour limiter ces altérations. Dans le projet 2, les mécanismes de la CRSC, une maladie rétinienne causée par la dilatation des vaisseaux choroïdiens menant à l'accumulation de liquide sous-rétinien, ont été explorés. Nous avons analysé les facteurs d'imagerie multimodaux prédictifs de la durée des épisodes (2a) et de récurrence (2b), mettant en évidence notamment l'épaisseur choroïdienne comme facteur pronostic. Des images en OCT angiographie, non invasive, de la choriocapillaire, la couche la plus interne de la choroïde sous l'épithélium pigmentaire rétinien, ont été traitées pour détecter des lacunes dans le flux sanguin, et étudier leur distribution (2c). Enfin, la composition moléculaire du liquide sous-rétinien d'un cas rare de CRSC nécessitant une chirurgie sous-rétinienne, a été explorée en utilisant une approche multi- omique collaborative (2d). Dans le projet 3, les mécanismes de vasculopathie rétinienne ont été étudiés dans deux phénotypes purs représentés par les troubles télangiectasiques : télangiectasie maculaire de type 1 (Mactel 1) (3a et 3b), et maculopathie radique (3c). Pour l'étude de Mactel 1, des outils de traitement d'images ont été utilisés pour calculer la densité capillaire globale et locale sur des images d’OCT angiographie, montrant que la non-perfusion est un paramètre critique dans les Mactel 1, corrélé à la fonction visuelle et à la formation des télangiectasies. Cette approche a été combinée à l'étude biologique de l'humeur aqueuse dans des cas de Mactel 1. Des niveaux intraoculaires de facteurs angiogéniques ont démontré l'implication du facteur de croissance placentaire dans la physiopathologie de MacTel1. De plus, ce facteur était corrélé avec la densité capillaire en OCT angiographie (3b). Enfin, un algorithme de traitement d'images a été conçu et appliqué à la maculopathie radique pour calculer automatiquement la dimension fractale des images d’OCT angiographie. Ce paramètre était pertinent dans l'évaluation de la perturbation du réseau capillaire, et a démontré que les altérations du plexus profond influencent indépendamment la fonction visuelle. Les stratégies développées dans ce travail démontrent l'intérêt de l'analyse d'image quantitative pour l'étude des pathologies rétiniennes, et la possibilité de coupler l'imagerie et les données biologiques. Cette approche a permis d'identifier des marqueurs biologiques ou d'imagerie potentiels pour le diagnostic, le pronostic, la réponse thérapeutique et la toxicité dans les différentes situations étudiées

Quantitative analysis of optical coherence tomography for neovascular age-related macular degeneration using deep learning

PURPOSE: To apply a deep learning algorithm for automated, objective, and comprehensive quantification of optical coherence tomography (OCT) scans to a large real-world dataset of eyes with neovascular age-related macular degeneration (AMD), and make the raw segmentation output data openly available for further research. DESIGN: Retrospective analysis of OCT images from the Moorfields Eye Hospital AMD Database. PARTICIPANTS: 2473 first-treated eyes and another 493 second-treated eyes that commenced therapy for neovascular AMD between June 2012 and June 2017. METHODS: A deep learning algorithm was used to segment all baseline OCT scans. Volumes were calculated for segmented features such as neurosensory retina (NSR), drusen, intraretinal fluid (IRF), subretinal fluid (SRF), subretinal hyperreflective material (SHRM), retinal pigment epithelium (RPE), hyperreflective foci (HRF), fibrovascular pigment epithelium detachment (fvPED), and serous PED (sPED). Analyses included comparisons between first and second eyes, by visual acuity (VA) and by race/ethnicity, and correlations between volumes. MAIN OUTCOME MEASURES: Volumes of segmented features (mm3), central subfield thickness (CST) (μm). RESULTS: In first-treated eyes, the majority had both IRF and SRF (54.7%). First-treated eyes had greater volumes for all segmented tissues, with the exception of drusen, which was greater in second-treated eyes. In first-treated eyes, older age was associated with lower volumes for RPE, SRF, NSR and sPED; in second-treated eyes, older age was associated with lower volumes of NSR, RPE, sPED, fvPED and SRF. Eyes from black individuals had higher SRF, RPE and serous PED volumes, compared with other ethnic groups. Greater volumes of the vast majority of features were associated with worse VA. CONCLUSION: We report the results of large scale automated quantification of a novel range of baseline features in neovascular AMD. Major differences between first and second-treated eyes, with increasing age, and between ethnicities are highlighted. In the coming years, enhanced, automated OCT segmentation may assist personalization of real-world care, and the detection of novel structure-function correlations. These data will be made publicly available for replication and future investigation by the AMD research community