1,720,974 research outputs found
The influence of learning effect on frequency doubling technology perimetry (Matrix)
No full textPURPOSE: To determine learning effect in healthy patients without perimetric experience, tested with the frequency doubling technology perimetry, with the new model Matrix. PATIENTS AND METHODS: Frequency doubling technology in the 30-2 threshold mode was performed on 37 healthy subjects. Each subject was tested twice in different sessions. The test always began with the right eye (RE) and continued with the left eye (LE). To evaluate learning effect the results of the REs at the first session were compared with those of the LE. The following parameters were evaluated: foveal threshold (FT), reliability indexes, mean defect (MD), pattern standard deviation (PSD), glaucoma hemifield test (GHT), duration of examination. RESULTS: At the first session the average values of RE were FT=30.81 db, MD=-1 db, PSD=3.01 db, and duration of the examination=383.27 "and of LE were FT=30.73, MD=-0.79 db, PSD=2.97 db, and duration of examination 382.62." At the second session the average values of RE were FT=32.22 db, MD=+0.16 db, PSD 2.75 db, and duration of examination=374.97 db. The reliability was different and the GHT between the RE and LE in the first and second session was also different. CONCLUSIONS: A learning effect was observed between the first and the second sessions and the results of the GHT appeared improved. This above all should be taken into account when considering the clinical use of this test to avoid erroneous diagnostic conclusions. © 2007 Lippincott Williams & Wilkins, Inc
Effect of refractive correction on the accuracy of frequency-doubling technology matrix
No full textPurpose: To investigate the effect of refractive correction on the reliability and accuracy of frequency-doubling technology (FDT) Matrix examinations.Methods: Forty-eight eyes of healthy people were submitted to the FDT Matrix 30/2 threshold program. They had experience in perimetry, normal eye examination, and negative history for glaucoma and/or neurological diseases. The subjects were randomized into groups A (24 subjects) and B (24 subjects). The FDT Matrix 30/2 examinations were carried out in 3 different sessions. At the first session, groups A and B underwent the examinations with their best refractive correction. In the second session, group A underwent the FDT 30/2 examination with best refractive correction and the group B without it. In the third session, the groups were matched and followed the same protocol. The perimetric and reliability indexes and the time of examination with or without correction were considered. The Student t test was used when the distribution of the data was normal, whereas Mann-Whitney when the distribution of the data was not normal. After a Bonferroni correction, a P value <0.001 was considered as statistically significant.Results: Mean deviation reduced statistically significantly when refractive correction was used (-2.65 +/- 3.71 vs. -1.41 +/- 3.51 dB; P<0.006). All the other perimetric indexes and data considered did not change significantly when the subjects did the examination with or without the refractive correction.Conclusions: The statistically significant reduction of mean deviation obtained with corrective lens showed that a better general accuracy and reliability of FDT responses was obtained with refractive correction. Pattern standard deviation constancy with or without correction confirmed that a localized defect is the first sign of visual field defect and that the absence of differences of pattern standard deviation between the 2 sessions is related to the absence of pathologic conditions in the eyes studied. Finally, as FDT Matrix is less influenced by other nonconventional perimetric techniques by refractive errors, the use of corrective lens is advisable to improve the accuracy and reliability of the results obtained and to optimize their performance
Comparative efficacy of acetazolamide and apraclonidine in the control of Intraocular pressure following phacoemulsification
No full textPurpose: The purpose of our study was to compare the effects of systemically administered acetazolamide and topical apraclonidine 0.5% in the control of intraocular pressure (IOP) following phacoemulsification of senile cataracts. Setting: The study was conducted on patients affected by cataract and followed at the Department of Ophthalmology. Methods: Seventy-eight eyes in 78 patients were selected. Twenty-six eyes were randomly assigned to postoperative treatment with topical apraclonidine 0.5%, 26 received oral acetazolamide and the remaining 26 received no hypotensive treatment (control group). Statistical analyses were performed mainly by means of analyis of variance. Results: IOPs measured 24 h after surgery were significantly (p = 0.01) lower in the apraclonidine group compared to the control group. Conclusions: Our double-blind prospective study conducted on patients randomly assigned to treatment with apraclonidine or acetazolamide shows that the former drug is undoubtedly effective in the prevention of IOP increases following phacoemulsification. IOPs recorded in patients treated with this drug were lower than those observed in the acetazolamide and the control groups. Considering the lower risk of toxicity associated with topical administration, apraclonidine 0.5% seems to be preferable to oral acetazolamide in this postoperative setting. Copyright (c) 2006 S. Karger AG, Basel
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
Ocular Surface Changes in Glaucomatous Patients Treated with and without Preservatives beta-Blockers.
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