1,721,078 research outputs found
New insight on choroidal vasculature: multimodal morphofunctional approach
No full textmaging the choroid in vivo using standard modalities is difficult because of light scattering within overlying tissue, particularly the retinal pigment epithelium (RPE). Although the choriocapillaris is composed of relatively large-diameter capillaries, they are interconnected in a dense arrangement. The flow in the choriocapillaris is fast and because of the prominent fluorescein leakage vascular structure is obscured. Indocyanine green dye shows less leakage than fluorescein, but it still leaks from the choriocapillaris and stains Bruch’s membrane and the choroidal stroma. Optical coherence tomography angiography has high axial resolution, but the lateral resolution is insufficient to visualize the choriocapillaris clearly in the posterior pole. Nevertheless, it can detect choriocapillaris blood flow, producing contrast between the RPE and choriocapillaris. However, because of signal loss, fringe
wash-out, and thresholding used in signal processing, the vessels in Sattler’s layer and certainly in Haller’s layer appear dark in normal eyes. Purpose of the lecture is to evaluate various choroidal multimodal imaging findings and to allocate them in the context of different macular diseases
Optical coherence tomography angiography
No full textOptical coherence tomography angiography (OCT-A) is one of the most recent advances in ophthalmic imaging. It allows a depth-resolved assessment of retinal and choroidal blood flow, exceeding the levels of detail commonly obtained with fluorescein or indocyanine green angiographies. One of the first applications of OCT-A was detecting choroidal neovascularizations (CNV) in central serous chorioretinopathy (CSCR) within those flat irregular pigmented epithelium detachments (PED) that are observed commonly in cases of long-standing disease. Thanks to the long wavelength and to the poor influence of the light scattering phenomenon of OCT-A devices, a distinct CNV is easier to detect than FA. Qualitative and quantitative assessments of OCT-A findings in CSCR have been investigated within the last 3 years, both in clinical and experimental settings. This chapter constitutes an overview of all the potential findings and applications of OCT-A in CSCR to better understand how to translate its theoretical usefulness into clinical practice
New insight on choroidal vasculature: multimodal morphofunctional approach
No full textmaging the choroid in vivo using standard modalities is difficult because of light scattering within overlying tissue, particularly the retinal pigment epithelium (RPE). Although the choriocapillaris is composed of relatively large-diameter capillaries, they are interconnected in a dense arrangement. The flow in the choriocapillaris is fast and because of the prominent fluorescein leakage vascular structure is obscured. Indocyanine green dye shows less leakage than fluorescein, but it still leaks from the choriocapillaris and stains Bruch’s membrane and the choroidal stroma. Optical coherence tomography angiography has high axial resolution, but the lateral resolution is insufficient to visualize the choriocapillaris clearly in the posterior pole. Nevertheless, it can detect choriocapillaris blood flow, producing contrast between the RPE and choriocapillaris. However, because of signal loss, fringe
wash-out, and thresholding used in signal processing, the vessels in Sattler’s layer and certainly in Haller’s layer appear dark in normal eyes. Purpose of the lecture is to evaluate various choroidal multimodal imaging findings and to allocate them in the context of different macular diseases
OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY VERSUS TRADITIONAL MULTIMODAL IMAGING IN ASSESSING THE ACTIVITY OF EXUDATIVE AGE-RELATED MACULAR DEGENERATION A New Diagnostic Challenge
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Sildenafil in ophthalmology: An update
No full textSildenafil citrate, a selective oral phosphodiesterase 5 inhibitor, is a widely used drug for erectile dysfunction that acts by elevating cGMP levels and causing smooth muscle relaxation. It also has 10% activity against PDE6, a key enzyme in phototransduction cascade in the retina. Recent ocular imaging developments have further revealed the influence of sildenafil on ocular hemodynamics, particularly choroidal perfusion. Choroidal thickness is increased, and choroidal perfusion is also enhanced by autoregulatory mechanisms that are further dependent on age and microvascular abnormalities. Studies demonstrating high intraocular pressure via a “parallel pathway” from increased choroidal volume and blood flow to the ciliary body have challenged previous concepts. Another new observation is the effect of sildenafil on bipolar cells and cyclic-nucleotide gated channels. We discuss potential deleterious effects (central serous chorioretinopathy, glaucoma, ischemic optic neuropathy, and risks to recessive carriers of retinitis pigmentosa), potential beneficial effects (ameliorate choroidal ischemia, prevent thickening of Bruch membrane, and promote recovery of the ellipsoid zone) in macular degeneration, as well as potential drug interactions of sildenafil
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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