135 research outputs found
The EU’s Arctic Policy: Between Vision and Reality. CEPOB #5.19, August 2019
> The EU’s Arctic policy statements have so far been primarily aggregations of existing actions, wrapped in high-level rhetoric.
> EU policy-makers have not yet developed a convincing Arctic narrative to broadly engage the EUropean public in Arctic matters.
> Although no dramatic changes took place in the Arctic in the last years, security questions and high politics have become more visible.
> The current main themes of the EU’s Arctic policy – climate, sustainable development and international cooperation – should be kept. Climate change should not be the only pillar of the EU’s Arctic engagement. Policymakers need to propose concrete future-oriented actions for issues such as marine litter. At the same time, the EU should not openly raise security questions.
> To operationalize its policies, the EU should re-consider the current institutional set-up of its Arctic policy, including ways to involve the European Parliament and making internal long-term coordination more effective
Subclinical Photoreceptor Disruption in Response to Severe Head Trauma
Commotio retinae is a transient opacification of the retina due to outer retinal disruption occurring in a contrecoup fashion after blunt trauma.Histological studies in animals and humans after ocular blunt trauma have revealed that disruption occurs at the level of the photoreceptor outer segments and retinal pigment epithelium.Recent reports using optical coherence tomography (OCT) have shown detectable disruption at the level of the photoreceptor inner segment/outer segment junction and retinal pigment epithelium and that these changes may be reversible over time with restoration of normal outer retinal architecture.However, the resolution of existing OCT technology may not be sensitive enough to detect photoreceptor disruption. Adaptive optics (AO) imaging systems enable cellular-resolution imaging of the human retina, and there is a growing number of cases where deficits have been visible on AO images but not on OCT. Herein, we report a case of subclinical photoreceptor disruption after head trauma as seen by an AO scanning ophthalmoscope (AOSO) but not apparent clinically or on spectral-domain OCT (SD-OCT)
Outer Retinal Structure in Best Vitelliform Macular Dystrophy
Importance Demonstrating the utility of adaptive optics scanning light ophthalmoscopy (AOSLO) to assess outer retinal structure in Best vitelliform macular dystrophy (BVMD).
Objective To characterize outer retinal structure in BVMD using spectral-domain optical coherence tomography (SD-OCT) and AOSLO.
Design, Setting, and Participants Prospective, observational case series. Four symptomatic members of a family with BVMD with known BEST1 mutation were recruited at the Advanced Ocular Imaging Program research lab at the Medical College of Wisconsin Eye Institute, Milwaukee.
Intervention Thickness of 2 outer retinal layers corresponding to photoreceptor inner and outer segments was measured using SD-OCT. Photoreceptor mosaic AOSLO images within and around visible lesions were obtained, and cone density was assessed in 2 subjects.
Main Outcome and Measure Photoreceptor structure.
Results Each subject was at a different stage of BVMD, with photoreceptor disruption evident by AOSLO at all stages. When comparing SD-OCT and AOSLO images from the same location, AOSLO images allowed for direct assessment of photoreceptor structure. A variable degree of retained photoreceptors was seen within all lesions. The photoreceptor mosaic immediately adjacent to visible lesions appeared contiguous and was of normal density. Fine hyperreflective structures were visualized by AOSLO, and their anatomical orientation and size were consistent with Henle fibers.
Conclusions and Relevance The AOSLO findings indicate that substantial photoreceptor structure persists within active lesions, accounting for good visual acuity in these patients. Despite previous reports of diffuse photoreceptor outer segment abnormalities in BVMD, our data reveal normal photoreceptor structure in areas adjacent to clinical lesions. This study demonstrates the utility of AOSLO for understanding the spectrum of cellular changes that occur in inherited degenerations such as BVMD. Photoreceptors are often significantly affected at various stages of inherited degenerations, and these changes may not be readily apparent with current clinical imaging instrumentation
Strategic Assessment Of Development Of The Arctic - Assessment conducted for theEuropean Union
The ‘Strategic Assessment of Development of the Arctic:
Assessment Conducted for the European Union” report
considers the trends and developments taking place in the
European Arctic today. That includes a view to 2030, with
an emphasis on the uncertainties. The analysis has been
conducted on the basis of seven themes focused on change.
The implications of Arctic changes for the European Union
as well as the role of EU policies and actions in the Arctic are examined. The European Arctic is understood here as the part of the circumpolar Arctic located between Greenland and northwest Russia
Assessing Errors Inherent in OCT-Derived Macular Thickness Maps
SD-OCT has become an essential tool for evaluating macular pathology; however several aspects of data collection and analysis affect the accuracy of retinal thickness measurements. Here we evaluated sampling density, scan centering, and axial length compensation as factors affecting the accuracy of macular thickness maps. Forty-three patients with various retinal pathologies and 113 normal subjects were imaged using Cirrus HD-OCT. Reduced B-scan density was associated with increased interpolation error in ETDRS macular thickness plots. Correcting for individual differences in axial length revealed modest errors in retinal thickness maps, while more pronounced errors were observed when the ETDRS plot was not positioned at the center of the fovea (which can occur as a result of errant fixation). Cumulative error can exceed hundreds of microns, even under “ideal observer” conditions. This preventable error is particularly relevant when attempting to compare macular thickness maps to normative databases or measuring the area or volume of retinal features
Microscopic Inner Retinal Hyper-reflective Phenotypes in Retinal and Neurologic Disease
Purpose.
We surveyed inner retinal microscopic features in retinal and neurologic disease using a reflectance confocal adaptive optics scanning light ophthalmoscope (AOSLO).
Methods.
Inner retinal images from 101 subjects affected by one of 38 retinal or neurologic conditions and 11 subjects with no known eye disease were examined for the presence of hyper-reflective features other than vasculature, retinal nerve fiber layer, and foveal pit reflex. The hyper-reflective features in the AOSLO images were grouped based on size, location, and subjective texture. Clinical imaging, including optical coherence tomography (OCT), scanning laser ophthalmoscopy, and fundus photography was analyzed for comparison.
Results.
Seven categories of hyper-reflective inner retinal structures were identified, namely punctate reflectivity, nummular (disc-shaped) reflectivity, granular membrane, waxy membrane, vessel-associated membrane, microcysts, and striate reflectivity. Punctate and nummular reflectivity also was found commonly in normal volunteers, but the features in the remaining five categories were found only in subjects with retinal or neurologic disease. Some of the features were found to change substantially between follow up imaging months apart.
Conclusions.
Confocal reflectance AOSLO imaging revealed a diverse spectrum of normal and pathologic hyper-reflective inner and epiretinal features, some of which were previously unreported. Notably, these features were not disease-specific, suggesting that they might correspond to common mechanisms of degeneration or repair in pathologic states. Although prospective studies with larger and better characterized populations, along with imaging of more extensive retinal areas are needed, the hyper-reflective structures reported here could be used as disease biomarkers, provided their specificity is studied further
- …