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Optic nerve diameters and perimetric thresholds in idiopathic intracranial hypertension
No full textIdiopathic intracranial hypertension (IIH) is a central nervous disorder characterised by abnormally increased cerebrospinal fluid (CSF) pressure leading to optic nerve compression. An indirect estimate of increased CSF pressure can be obtained by the ultrasonographic determination of optic nerve sheaths diameters. Computerised static perimetry is regarded as the method of choice for monitoring the course of the optic neuropathy in IIH. The aims were to compare the echographic optic nerve diameters (ONDs) and the perimetric thresholds of patients with IIH with those of age-matched controls, and to examine the correlation between these two variables in individual patients with papilloedema
Hyperemic responses of the optic nerve head blood flow to chromatic equiluminant flicker are reduced by ocular hypertension and early glaucoma
No full textWe evaluated in ocular hypertension (OHT) and early glaucoma (EOAG) patients the optic nerve head (ONH) blood flow response (RFonh) to chromatic equiluminant flicker. This stimulus generates neural activity dominated by the parvo-cellular system. Eleven EOAG, 20 OHT patients, and 8 age-matched control subjects were examined. The blood flow (Fonh) at the neuroretinal rim was continuously monitored by laser Doppler flowmetry before, during, and after a 60-s exposure to a 4 Hz, red-green equiluminant flicker stimulus RFonh was expressed as percentage Fonh-change during the last 20 s of flicker relative to baseli Responses were collected at a number of temporal sites. The highest RFonh value was used for subsequent analysis. As compared to controls, both OHT and EOAG patients showed a decrease
Pattern electroretinogram in treated ocular hypertension: a cross-sectional study after timolol maleate therapy
No full textTo investigate pattern electroretinogram changes in treated ocular hypertension, we evaluated pattern electroretinogram recordings of 48 hypertensive eyes following an 8-month timolol maleate therapy. During treatment, 27 of 48 eyes had normalized intraocular pressures (15-18 mm Hg), while 21 retained elevated values (21-25 mm Hg). Twenty-eight eyes with untreated hypertension (22-25 mm Hg) lasting at least 8 months, as well as 32 untreated, normotensive eyes served as controls. When compared to untreated normotensive controls, timolol-treated eyes with either elevated or normalized intraocular pressures showed reductions in the mean electroretinographic amplitudes. However, these amplitude reductions were substantially greater in treated eyes with elevated pressures as compared to those with normalized ones. Untreated hypertensive controls showed pattern electroretinogram reductions, with respect to normal values, that were comparable to those of treated hypertensive eyes, but larger than those of treated normotensive ones. These results indicate that, in treated ocular hypertension, pattern electroretinogram losses tend to be associated with moderately increased intraocular pressures in the range of 21-25 mm Hg. Electroretinographic abnormalities may be, at least in part, prevented only by lowering intraocular pressure into a normal range
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
Structure-function relationship in ocular hypertension and glaucoma: interindividual and interocular analysis by OCT and pattern ERG
No full textBACKGROUND:
Pattern electroretinogram (PERG) and optical coherence tomography (OCT) represent objective probes to investigate respectively the function of retinal ganglion cells and their structure as retinal nerve fiber layer (RNFL) thickness. We examined interindividual (II) correlations of PERG amplitude and RNFL thickness, as well as correlations between interocular (IO) differences in both measures, in ocular hypertension (OHT) and early glaucoma (EG) patients.
METHODS:
Thirty-one OHT, 34 EG (mean deviation: -1 to -6 dB) and 16 age-matched controls were examined in both eyes. Participants had clear optical media, no or moderate refractive errors and no concomitant ocular or systemic diseases. PERGs were elicited by counterphased (16.28 reversals/second) gratings (1.6 cycles/degree spatial frequency). The Fourier isolated 2nd harmonic PERG amplitude and phase were measured. RNFL thickness was quantified by means of OCT Stratus according to a standard protocol. Average, superior and inferior RNFL thicknesses were considered.
RESULTS:
Mean PERG amplitude was decreased (p < 0.01) in both OHT and EG patients compared to controls. Mean RNFL thicknesses were reduced (p < 0.01) in EG patients compared to both OHT and controls. In OHT patients, PERG amplitude did not correlate significantly with RNFL thickness in both II and IO analysis. In EG patients, PERG amplitude was positively correlated with RNFL thickness in both II (p < 0.005) and IO (p < 0.001) analysis. The slope of the correlation predicted that PERG losses exceeded systematically RNFL losses when the latter were between 0 and -0.25 log units.
CONCLUSIONS:
Both II and IO analyses revealed a lack of structure-function relationship in OHT, suggesting that, at this disease stage, PERG losses appear to affect primarily retinal/optic nerve head function. In EG they reflect both dysfunction and RNFL loss
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
Discriminating between early glaucoma and ocular hypertension: diagnostic accuracy of pattern electroretinogram and confocal scanning laser optic disc morphometry
No full textPurpose
To evaluate diagnostic accuracy of pattern electroretinogram (PERG) and confocal scanning laser optic disc morphometry in discriminating between early open-angle glaucoma (EOAG) and ocularhypertension (OHT).
Methods
Fifty-five randomly selected eyes of 55
patients, with a clinical diagnosis of
EOAG (26; Humphrey mean deviation
-7 dB) or OHT (29), were included in
the study. Both groups were matched
with respect to age, sex and family history.
PERGs were recorded in response
to sinusoidal gratings of optimal spatial
frequency (1.7 cycles/deg), square-wave
counterphased at 8 Hz. Response 2nd
harmonic amplitude was measured.
Confocal scanning laser morphometry
was performed by Heidelberg Retina
Tomograph (HRT; software 2.01).
Among the various HRT parameters,
disc area (DA), cuptodisc area ratio
(CDA), rim area (RA) and cup shape
measure (CSM) were selected for analysis.
Data were analyzed by Analysis of
Variance (ANOVA) and Receiver Operating
Characteristics (ROC) curves.
Correlation between functional and morphometric parameters was evaluated by multiple regression analysis. Results Mean PERG amplitude was smaller (p<O.Ol) in EOAG as compared to OHT eyes. Mean CDA and CSM were greater (p<O.Ol), and RA was smaller (p<O.Ol) in EOAG as compared to OHT eyes. The areas under the ROC curve were: PERG, 0.77; CDA, 0.69; RA, 0.71; CSM, 0.71 . Diagnostic accuracy did not differ significantly across measures. In the whole study population, PERG amplitudes were negatively correlated with CSM (r= -0.60, pCO.001). Conclusions: Functional and morphometric measures of early optic nerve damage display comparably good accuracy in discriminating between clinically defined EOAG and OHT eyes
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