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Varsha Pramil,1,2 Emily S Levine,1,2 Nadia K Waheed1 1New England Eye Center, Tufts Medical Center, Boston, MA, USA; 2Tufts University School of Medicine, Boston, MA, USACorrespondence: Nadia K WaheedNew England Eye Center, Tufts Medical Center, 260 Tremont St., Boston, MA, 02116, USATel +1 617-636-4600Fax +1 617-636-4866Email nadiakwaheed@gmail.comAbstract: Diabetic retinopathy is one of the leading causes of blindness worldwide. Optical coherence tomography angiography (OCTA) is a non-invasive technology that provides depth-resolved images of the chorioretinal vasculature and allows for the understanding of the changes in vasculature with diabetic retinopathy. Not only can it provide qualitative information, but OCTA can also provide quantitative information about the vasculature in patients with diabetic retinopathy. Macular vessel density is one of the quantitative metrics that can be obtained from OCTA images. This is a repeatable and non-subjective measurement that can provide valuable insight into the pathophysiology of diabetic retinopathy. In this non-systematic review, the measurement of macular vessel density in diabetic retinopathy and the reasons for its importance in the diagnosis and management of patients with diabetes and varying severities of diabetic retinopathy is discussed.Keywords: diabetic retinopathy, macular vessel density, OCTA

Purpose: To analyse the longitudinal changes in imaging parameters in eyes with acute or chronic central serous chorioretinopathy (CSCR)., Methods: This was a multicentric, retrospective, longitudinal, observational study in patients with a diagnosis of CSCR and having at least 4 years of follow-up. Trend in choroidal thickness (CT), area of double layer sign (DLS), area of retinal pigment epithelium (RPE) alterations, and area of hyper-autofluorescence were analysed., Results: A total of 175 eyes of 146 patients with a mean age of 52.9 ± 12.5 years were included. Fifty-two eyes had acute and 123 had chronic CSCR at baseline. There was an overall decreasing trend of CT values during follow up (from 354.4 ± 74.8 at baseline to 343.2 ± 109.4 at final visit). There was a steady rise in DLS width and RPE alteration in the overall cohort (from 811.7 ± 760.6 microns and 3.5 ± 3.3 disc areas respectively at baseline to 1209.1 ± 1113.18 microns, 4.1 ± 3.6 disc areas at final visit). An initial rise in hyper-autofluorescent area followed by steady fall was seen in chronic CSCR. A significant positive correlation (r = 0.54, p = 0.004) was seen between change in DLS width and change in area of hyper-autofluorescence. On linear regression analysis, lower CMT and absence of intraretinal fluid at baseline were associated with greater increase in RPE abnormalities., Conclusion: Acute and chronic CSCR had different pattern of change in imaging parameters with area of RPE alterations in acute CSCR not reaching values close to that of chronic CSCR eyes even after long follow up., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Purpose: To apply methods for quantifying uncertainty of deep learning segmentation of geographic atrophy (GA)., Design: Retrospective analysis of OCT images and model comparison., Participants: One hundred twenty-six eyes from 87 participants with GA in the SWAGGER cohort of the Nonexudative Age-Related Macular Degeneration Imaged with Swept-Source OCT (SS-OCT) study., Methods: The manual segmentations of GA lesions were conducted on structural subretinal pigment epithelium en face images from the SS-OCT images. Models were developed for 2 approximate Bayesian deep learning techniques, Monte Carlo dropout and ensemble, to assess the uncertainty of GA semantic segmentation and compared to a traditional deep learning model., Main Outcome Measures: Model performance (Dice score) was compared. Uncertainty was calculated using the formula for Shannon Entropy., Results: The output of both Bayesian technique models showed a greater number of pixels with high entropy than the standard model. Dice scores for the Monte Carlo dropout method (0.90, 95% confidence interval 0.87-0.93) and the ensemble method (0.88, 95% confidence interval 0.85-0.91) were significantly higher ( P  < 0.001) than for the traditional model (0.82, 95% confidence interval 0.78-0.86)., Conclusions: Quantifying the uncertainty in a prediction of GA may improve trustworthiness of the models and aid clinicians in decision-making. The Bayesian deep learning techniques generated pixel-wise estimates of model uncertainty for segmentation, while also improving model performance compared with traditionally trained deep learning models., Financial Disclosures: Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article., (© 2024 by the American Academy of Ophthalmology.)

Purpose: To assess the relationship between choriocapillaris (CC) loss and the development of nascent geographic atrophy (nGA) using optical coherence tomography angiography (OCTA) imaging., Methods: In total, 105 from 62 participants with bilateral large drusen, without late age-related macular degeneration (AMD) or nGA at baseline, were included in this prospective, longitudinal, observational study. Participants underwent swept-source OCTA imaging at 6-month intervals. CC flow deficit percentage (FD%) and drusen volume measurements were determined for the visit prior to nGA development or the second-to-last visit if nGA did not develop. Global and local analyses, the latter based on analyses within superpixels (120 × 120-µm regions), were performed to examine the association between CC FD% and future nGA development., Results: A total of 15 (14%) eyes from 12 (19%) participants developed nGA. There was no significant difference in global CC FD% at the visit prior to nGA development between eyes that developed nGA and those that did not (P = 0.399). In contrast, CC FD% was significantly higher in superpixels that subsequently developed nGA compared to those that did not (P < 0.001), and a model utilizing CC FD% was significantly better at predicting foci of future nGA development at the superpixel level than a model using drusen volume alone (P ≤ 0.040)., Conclusions: This study showed that significant impairments in CC blood flow could be detected locally prior to the development of nGA. These findings add to our understanding of the pathophysiologic changes that occur with atrophy development in AMD.

Objectives: To analyse the longitudinal changes in visual acuity and risk factors for recurrence or development of choroidal neovascularisation (CNV) in eyes with acute or chronic central serous chorioretinopathy (CSCR)., Methods: This was a retrospective, multicentric, longitudinal, observational study done in patients with a diagnosis of unilateral or bilateral CSCR and having at least 4 years of follow-up between the years 1999 and 2020. Kaplan-Meier curves were used for assessing cumulative risks. Multivariate logistic, linear and cox regression models were used for risk factor analyses. The trend in visual acuity, cumulative risks of recurrence and CNV formation was analysed., Results: A total of 117 out of 175 eyes (66.8%) had stable or improvement in vision at last follow-up, while 24 eyes had more than/equal to 3 line loss of vision. Four eyes (7.7%) with acute CSCR at initial presentation developed features of chronic CSCR at the final presentation. Thirty-seven eyes had recurrence during the follow-up with a 10-year cumulative recurrence rate of around 30%. On Cox proportional hazard regression analysis, history of previous treatment and male gender (p = 0.03) were associated with a lower risk of recurrence. Twenty-four developed de novo CNV by the end of follow-up and higher age (p = 0.001) and a higher number of recurrences (p = 0.05) were associated with a higher risk of early de novo CNV formation. The cumulative 10-year CNV development rate was 17.4%., Conclusion: A non-temporal relationship between acute and chronic CSCR was seen. Previous treatment, smoking and baseline RPE abnormality affected recurrence of SRF or CNV formation., (© 2022. The Author(s), under exclusive licence to The Royal College of Ophthalmologists.)

Purpose: To present a deep learning algorithm for segmentation of geographic atrophy (GA) using en face swept-source OCT (SS-OCT) images that is accurate and reproducible for the assessment of GA growth over time., Design: Retrospective review of images obtained as part of a prospective natural history study., Subjects: Patients with GA (n = 90), patients with early or intermediate age-related macular degeneration (n = 32), and healthy controls (n = 16)., Methods: An automated algorithm using scan volume data to generate 3 image inputs characterizing the main OCT features of GA-hypertransmission in subretinal pigment epithelium (sub-RPE) slab, regions of RPE loss, and loss of retinal thickness-was trained using 126 images (93 with GA and 33 without GA, from the same number of eyes) using a fivefold cross-validation method and data augmentation techniques. It was tested in an independent set of one hundred eighty 6 × 6-mm 2 macular SS-OCT scans consisting of 3 repeated scans of 30 eyes with GA at baseline and follow-up as well as 45 images obtained from 42 eyes without GA., Main Outcome Measures: The GA area, enlargement rate of GA area, square root of GA area, and square root of the enlargement rate of GA area measurements were calculated using the automated algorithm and compared with ground truth calculations performed by 2 manual graders. The repeatability of these measurements was determined using intraclass coefficients (ICCs)., Results: There were no significant differences in the GA areas, enlargement rates of GA area, square roots of GA area, and square roots of the enlargement rates of GA area between the graders and the automated algorithm. The algorithm showed high repeatability, with ICCs of 0.99 and 0.94 for the GA area measurements and the enlargement rates of GA area, respectively. The repeatability limit for the GA area measurements made by grader 1, grader 2, and the automated algorithm was 0.28, 0.33, and 0.92 mm 2 , respectively., Conclusions: When compared with manual methods, this proposed deep learning-based automated algorithm for GA segmentation using en face SS-OCT images was able to accurately delineate GA and produce reproducible measurements of the enlargement rates of GA., (Copyright © 2022 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.)

An initial misdiagnosis of papilloedema in a patient with optic nerve head swelling can be anxiety-provoking and may result in unnecessary, invasive, and costly tests. Cirrus high definition, spectral domain-optical coherence tomography (Cirrus HD-OCT) may provide a rapid and non-invasive test. We sought to determine an upper limit of average retinal nerve fibre layer (RNFL) thickness in patients with pseudopapilloedema without visible drusen using Cirrus HD-OCT that could be utilised in conjunction with the clinical presentation and physical examination when managing patients with optic nerve head swelling. Inclusion criteria consisted of at least two neuro-ophthalmological visits and repeated imaging of the optic nerve head with Cirrus HD-OCT at least 6 months apart. Exclusion criteria included clinically visible drusen along with previous or concomitant diagnosis of retinal or other optic nerve pathology. Thirty-eight eyes from 19 patients with pseudopapilloedema were included in this study. The upper limit of average RNFL thickness was defined as two standard deviations above the mean of the average RNFL thickness and was calculated to be 158.65 µm for scans obtained with Cirrus HD-OCT devices. A patient with suspected optic nerve head swelling, an average RNFL thickness less than 158.65 µm, and no other evidence of papilloedema or neurological signs or symptoms can be managed with serial follow-ups with OCT imaging for at least 6 months. If the patient continues to have no clinical symptoms suggesting increased intracranial pressure and the average RNFL thickness is stable, the likelihood of papilloedema is minimal., Competing Interests: No potential conflict of interest was reported by the authors., (© 2022 Taylor & Francis Group, LLC.)

Background: Although nonarteritic anterior ischemic optic neuropathy (NAION) is considered a disorder that primarily affects the optic nerve head, optical coherence tomography (OCT) shows peripapillary and foveal subretinal fluid associated with optic disc swelling from NAION. We sought to further evaluate retinal and vitreous changes in patients with NAION., Methods: Patients diagnosed with NAION at the New England Eye Center between 2013 and 2017 were evaluated using OCT. The presence and distribution of subretinal fluid was analyzed. Evidence of other vitreoretinal changes, including vitreopapillary traction (VPT) and the presence of hyperreflective dots (HRD), were also determined., Results: Twenty-five eyes from 20 patients who presented within 4 weeks of symptom onset were assessed. Peripapillary subretinal fluid was seen in 16 eyes (64%). Of those eyes, the subretinal fluid extended into the macula in 4 eyes (16%). Visual acuity improved in 2 of 4 eyes after subfoveal fluid resolution. Intraretinal cysts located in the peripapillary region were seen in 8 eyes (32%), HRD were noted in 11 (44.0%). There was no evidence of VPT., Conclusions: A substantial number of patients with NAION have subretinal fluid on OCT, consistent with prior reports. Resolution of subfoveal fluid may result in some recovery of visual acuity. Other retinal changes, such as intraretinal cysts and HRD, are present but have unclear implications. We did not find evidence of a primary role of VPT in the pathophysiology of NAION., Competing Interests: The authors report no conflicts of interest., (Copyright © 2021 by North American Neuro-Ophthalmology Society.)

Purpose: To assess global, zonal, and local correlations between vessel density changes measured by optical coherence tomography angiography and retinal sensitivity measured by microperimetry across diabetic retinopathy severity., Methods: Diabetic patients and nondiabetic controls underwent optical coherence tomography angiography imaging and microperimetry testing. Pearson's correlation was used to assess associations between average sensitivity and skeletonized vessel density (SVD) or foveal avascular zone area centrally. Linear mixed effects modeling was used to assess relationships between local SVD measurements and their spatially corresponding retinal sensitivity measurements., Results: Thirty-nine eyes from 39 participants were imaged. In all slabs, there was a statistically significant positive correlation between retinal sensitivities and SVDs on both global and zonal scales. No statistically significant correlation was found between central retinal sensitivities and the foveal avascular zone areas. Assessment of 1,136 spatially paired retinal sensitivity and SVD measurements revealed a statistically significant local relationship; this seemed to be driven by eyes with proliferative diabetic retinopathy that had reduced retinal sensitivities., Conclusion: This study supports positive correlations between SVD and retinal sensitivity at global and zonal spatial scales in diabetic eyes. However, our analysis did not find evidence of statistically significant correlations between retinal sensitivity and SVD on a local scale until advanced diabetic retinopathy.

Background: To evaluate the changes in the mean macular intercapillary area (ICA) from sequential enface optical coherence tomography angiography (OCTA) images following intravitreal anti-vascular endothelial growth factor (VEGF) therapy in initially treatment-naïve eyes with diabetic macular oedema (DME)., Methods: In this multicentre retrospective study, 6 × 6 and 3 × 3 mm customised, total retinal projection enface OCTA images were collected and processed for quantitative assessment of ICA by a customised MATLAB software. Measurements were done in concentric regions centred on the fovea-with the exclusion of foveal avascular zone (FAZ)-in 0.5 mm diameter increments as well as within the intervening rings., Results: In this study, 6 × 6 mm OCTA images from 46 eyes of 29 patients, and 3 × 3 mm OCTA images from 23 eyes of 15 patients were included. There was no significant change in mean ICA after treatment in either scan size or in any measurement regions (all p > 0.05). Multivariate analysis revealed that baseline BCVA was significantly correlated with the visual outcome (p = 0.039). Additionally, after correction for age, baseline central retinal thickness (CRT), baseline BCVA, and retinopathy severity, mean ICA in the 1.5 mm circle was found to be a significant predictor of post treatment CRT, (p = 0.006)., Conclusions: Absence of significant change in mean ICA after a minimum of three intravitreal anti-VEGF injections, may indicate that, in the short term, anti-VEGF injections neither impair nor improve macular perfusion in DME. Baseline BCVA was found to be a robust predictor of functional outcome, while inner mean ICA was a significant predictor for macular thickness outcomes., (© 2021 Royal Australian and New Zealand College of Ophthalmologists.)

Purpose: Assess epidermolysis bullosa (EB)-related corneal pathology using anterior segment optical coherence tomography (AS-OCT) and correlate imaging with clinical metrics in EB patients versus age-matched controls., Methods: EB patients and controls were recruited during an EB conference (July 2018) and at Tufts Medical Center (June-August 2019). Subjects completed a questionnaire, had best corrected visual acuity (BCVA) tested, and underwent AS-OCT scanning. Stromal and epithelial thickness were measured. Depth, length, and type of the three largest lesions were assessed by a masked examiner using a novel pathology grading system. Multivariate analysis of AS-OCT findings and clinical metrics was performed., Results: 62 EB patients and 60 age-matched controls were enrolled. Mean BCVA was 1.8 lines worse in patients (p < 0.001). Vision loss was associated with increased stromal thickness. Discrete lesions were seen in 60.2% of patient eyes, averaging 1.71 ± 1.75 lesions in patients and 0.14 ± 0.42 in controls (p < 0.001). Mean primary lesion depth was 151.88 ± 97.49 μm in patients. Patients showed significant stromal thickening versus controls and lesions were most common in the periphery and inferiorly. Differences in frequency and duration of abrasions and severity of pain were all statistically and clinically significant in patients versus controls (p < 0.001)., Conclusions: AS-OCT can visualize and quantify differences in the corneas of EB patients compared with age-matched controls. Novel findings include quantification of average depth, length, and severity of discrete lesions, and sparing of the superior quadrant from stromal thickening in EB patients. These results support use of AS-OCT and a questionnaire in clinical trials for new EB therapies., (Copyright © 2020. Published by Elsevier Inc.)

The left ventricular assist device Impella 5.0 (Abiomed Inc, Danvers, MA) has become widely accepted as a temporary mechanical circulatory support for patients in cardiogenic shock. The Impella 5.0 is placed through an anastomosed graft. When removing the device, blood clot formation has been noted in the anastomosed graft. The blood clot has been reported to dislodge and embolize distally, causing acute limb ischemia. Here, we present our simple, inexpensive, and effective "loop and snare" technique for safer device removal, preventing distal embolic complications. In our experience of 6 patients who had Impella 5.0 removal with this technique, the distal embolic complication was 0%., (Copyright © 2020 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.)

Aims: Valve interstitial cells are active and aggressive players in aortic valve calcification, but their dynamic mediation of mechanically-induced calcific remodeling is not well understood. The goal of this study was to elucidate the feedback loop between valve interstitial cell and calcification mechanics using a novel three-dimensional culture system that allows investigation of the active interplay between cells, disease, and the mechanical valve environment., Methods & Results: We designed and characterized a novel bioreactor system for quantifying aortic valve interstitial cell contractility in 3-D hydrogels in control and osteogenic conditions over 14 days. Interstitial cells demonstrated a marked ability to exert contractile force on their environment and to align collagen fibers with the direction of tension. Osteogenic environment disrupted interstitial cell contractility and led to disorganization of the collagen matrix, concurrent with increased αSMA, TGF-β, Runx2 and calcific nodule formation. Interestingly, RhoA was also increased in osteogenic condition, pointing to an aberrant hyperactivation of valve interstitial cells mechanical activity in disease. This was confirmed by inhibition of RhoA experiments. Inhibition of RhoA concurrent with osteogenic treatment reduced pro-osteogenic signaling and calcific nodule formation. Time-course correlation analysis indicated a significant correlation between interstitial cell remodeling of collagen fibers and calcification events., Conclusions: Interstitial cell contractility mediates internal stress state and organization of the aortic valve extracellular matrix. Osteogenesis disrupts interstitial cell mechanical phenotype and drives disorganization, nodule formation, and pro-calcific signaling via a RhoA-dependent mechanism., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Background: Clostridium difficile infection (CDI) is a growing problem in the community and hospital setting. Its incidence has been on the rise over the past two decades, and it is quickly becoming a major concern for the health care system. High rate of recurrence is one of the major hurdles in the successful treatment of C. difficile infection. There have been few studies that have looked at patterns of recurrence. The studies currently available have shown a number of risk factors associated with C. difficile recurrence (CDR); however, there is little consensus on the impact of most of the identified risk factors., Methods: Our study was a retrospective chart review of 198 patients diagnosed with CDI via Polymerase Chain Reaction (PCR) from February 2009 to Jun 2013. In our study, we decided to use a machine learning algorithm called the Random Forest (RF) to analyze all of the factors proposed to be associated with CDR. This model is capable of making predictions based on a large number of variables, and has outperformed numerous other models and statistical methods., Results: We came up with a model that was able to accurately predict the CDR with a sensitivity of 83.3%, specificity of 63.1%, and area under curve of 82.6%. Like other similar studies that have used the RF model, we also had very impressive results., Conclusions: We hope that in the future, machine learning algorithms, such as the RF, will see a wider application.