1,720,957 research outputs found
Evaluation of the risk factors associated with conversion of intended deep anterior lamellar keratoplasty to penetrating keratoplasty
No full textBackground/aimsTo identify and evaluate risk factors associated with the need to convert intended deep anterior lamellar keratoplasty (DALK) to penetrating keratoplasty (PK).MethodsRetrospective institutional cohort study including all consecutive eyes undergoing intended DALK between May 2015 and October 2018 at 'Villa Igea' Hospital (Forli, Italy). The indications for surgery were categorised as (1) keratoconus without scarring; (2) keratoconus with scarring; (3) non-keratoconus without scarring; and (4) non-keratoconus with scarring. Multivariate binary logistic regression analysis was performed, introducing, as independent variables, those that reached a significance level of less than 0.05 in univariate analysis. The main outcome measure was whether or not conversion to a PK occurred.Results705 eyes were included, with conversion to PK occurring in 16.2% (n=114) of cases. The factors that remained significant in multivariate analysis were corneal scarring (OR=3.52, p<0.001), manual dissection (OR=42.66, p<0.001), type 2 bubble (OR=90.65, p<0.001) and surgeon inexperience (OR=10.86, p<0.001). A receiver operating characteristic (ROC) curve based on the factors significant in the multivariate binary logistic regression analysis achieved a sensitivity of 89.5% (95% CI 82.3% to 94.4%) and a specificity of 80.2% (95% CI 76.8% to 83.3%) with an area under the ROC curve of 0.91 (95% CI 0.88 to 0.93) (p<0.001)ConclusionOccurrence of a type 2 bubble, the need for manual dissection, the presence of scarring and surgeon inexperience are independent risk factors for the need to convert intended DALK to PK. Correct identification and management of the type of bubble achieved during pneumatic dissection is instrumental in minimising the rate of conversion to PK
Obstructive Sleep Apnea and Keratoconus: A Systematic Review and Meta-analysis.
Full text linkBACKGROUND: Despite the increasing number of studies focused on the association between obstructive sleep apnea (OSA) and keratoconus (KC), to date, no comprehensive meta-analysis or systematic review was published. OBJECTIVE: The objective of this study was to evaluate the association between OSA and KC. DATA SOURCES: Sources of data were PubMed, Scopus, and Web of Science databases. STUDY ELIGIBILITY CRITERIA: The criteria for study eligibility were case-control studies and cohort studies reporting data on the association of OSA with KC with risk ratio, odds ratio, or hazard ratio with 95% confidence intervals or sufficient raw data for calculation. STUDY APPRAISAL AND SYNTHESIS METHODS: Meta-analysis was conducted with a random-effects model using odds ratio with 95% confidence interval as the effect size. Heterogeneity was evaluated using the Q and I tests. Sensitivity analysis and assessment of publication bias were performed. RESULTS: Five studies (four case-control studies and one cohort study) published between 2012 and 2016 and involving 33,844 subjects (16,922 patients with KC, 16,922 controls) were included in this meta-analysis. A significant association between OSA and KC has been shown (pooled odds ratio, 1.841; 95% confidence interval, 1.163 to 2.914; P = .009). A significant heterogeneity was observed (Q = 15.8, I = 74.6%). There was no evidence of significant publication bias (P = .07). The sensitivity analyses indicated the stability of results. LIMITATIONS: Heterogeneity across the studies was observed. Data from four hospital-based case-control studies and one large population-based cohort study were combined. Most of the included studies ascertained OSA by the Berlin Questionnaire, which is a screening tool. CONCLUSIONS: This meta-analysis provides significant evidence that OSA is associated with KC. Therefore, a proper screening for OSA is warned for KC patients for the prevention of various cardiovascular comorbidities. Further prospective studies are warranted to explore more in-depth the casual relationship between the two conditions
Successful Visualization of a Big Bubble during Deep Anterior Lamellar Keratoplasty using Intraoperative OCT
No full textThe article illustrates the use of anterior segment optical coherent tomography to demonstrate the successful formation of a big bubble during deep anterior lamellar keratoplast
Management of Type 2 Bubble Formed During Big-Bubble Deep Anterior Lamellar Keratoplasty
No full textCorrispondig letter related to Management of Type 2 Bubble Formed During Big-Bubble Deep Anterior Lamellar Keratoplast
Successful Descemet membrane endothelial keratoplasty in proven herpetic endothelial decompensation requires intensive antiviral therapy
No full textPurpose: To report the outcomes of Descemet membrane endothelial keratoplasty (DMEK) with intensive antiviral therapy for corneal edema secondary to herpes simplex virus type 1 (HSV-1)-mediated endotheliitis. Methods: All eyes with polymerase chain reaction positive for HSV-1 undergoing DMEK for endothelial decompensation between January 2014 and January 2018 were followed up prospectively at our tertiary referral center. All eyes had been free of active inflammation for a minimum of 9 months and were treated prophylactically with high-dose systemic and topical antivirals, which were continued for a prolonged period of time. Primary outcomes were the occurrence of immunological rejection and/or recurrence of endotheliitis, eventually resulting in graft failure. Secondary outcomes were best spectacle-corrected visual acuity and endothelial cell loss. Results: Four consecutive eyes of 4 patients were included with a mean (±SD) patient age of 68.5 ± 15.1 years. The postoperative follow-up averaged 22 months. No eyes exhibited any signs of immunologic rejection, recurrence of endotheliitis, or graft failure. Mean (±SD) decimal best spectacle-corrected visual acuity improved from 0.2 ± 0.1 to 0.7 ± 0.2 (P = 0.007), whereas mean (±SD) endothelial cell loss was 56% ± 10.2% at the final postoperative follow-up. Conclusions: DMEK is an effective option to treat corneal edema secondary to HSV-1-related endotheliitis. Intensive antiviral prophylaxis may reduce the risk of recurrence and subsequent graft failure.Purpose: To report the outcomes of Descemet membrane endothelial keratoplasty (DMEK) with intensive antiviral therapy for corneal edema secondary to herpes simplex virus type 1 (HSV-1)mediated endotheliitis. Methods: All eyes with polymerase chain reaction positive for HSV-1 undergoing DMEK for endothelial decompensation between January 2014 and January 2018 were followed up prospectively at our tertiary referral center. All eyes had been free of active inflammation for a minimum of 9 months and were treated prophylactically with high-dose systemic and topical antivirals, which were continued for a prolonged period of time. Primary outcomes were the occurrence of immunological rejection and/or recurrence of endotheliitis, eventually resulting in graft failure. Secondary outcomes were best spectacle-corrected visual acuity and endothelial cell loss. Results: Four consecutive eyes of 4 patients were included with a mean (6SD) patient age of 68.5 6 15.1 years. The postoperative follow-up averaged 22 months. No eyes exhibited any signs of immunologic rejection, recurrence of endotheliitis, or graft failure. Mean (6SD) decimal best spectacle-corrected visual acuity improved from 0.2 6 0.1 to 0.7 6 0.2 (P = 0.007), whereas mean (6SD) endothelial cell loss was 56% 6 10.2% at the final postoperative follow-up. Conclusions: DMEK is an effective option to treat corneal edema secondary to HSV-1-related endotheliitis. Intensive antiviral prophylaxis may reduce the risk of recurrence and subsequent graft failure
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
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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