Search results for "Aberration"
showing 10 items of 293 documents
The effect of longitudinal chromatic aberration on the lag of accommodation and depth of field.
2016
Purpose Longitudinal chromatic aberration is present in all states of accommodation and may play a role in the accommodation response and the emmetropisation process. We study the change of the depth of field (DOFi) with the state of accommodation, taking into account the longitudinal chromatic aberration. Methods Subjective DOFi was defined as the range of defocus beyond which the blur of the target (one line of optotypes of 0.1 logMAR shown on a black-and-white microdisplay, seen through different colour filters) was perceived as objectionable. The subject's eye was paralysed and different, previously-measured accommodative states (corresponding to the accommodative demands of 0D, 2D and …
Single-Nucleotide Polymorphism Array-Based Karyotyping of Acute Promyelocytic Leukemia
2014
Acute promyelocytic leukemia (APL) is characterized by the t(15;17)(q22;q21), but additional chromosomal abnormalities (ACA) and other rearrangements can contribute in the development of the whole leukemic phenotype. We hypothesized that some ACA not detected by conventional techniques may be informative of the onset of APL. We performed the high-resolution SNP array (SNP-A) 6.0 (Affymetrix) in 48 patients diagnosed with APL on matched diagnosis and remission sample. Forty-six abnormalities were found as an acquired event in 23 patients (48%): 22 duplications, 23 deletions and 1 Copy-Neutral Loss of Heterozygocity (CN-LOH), being a duplication of 8(q24) (23%) and a deletion of 7(q33-qter) (…
Corneal and Refractive Astigmatism in Adults: A Power Vectors Analysis
2009
Purpose. In this article, we examine the relationship between corneal and refractive astigmatism (including with the rule, against-the-rule, and oblique astigmatism) in an adult population using power vectors. Methods. Refractive and keratometric measures of astigmatism were conducted on right eyes of 105 white subjects aged 18 to 59 years. We performed a linear regression of refractive astigmatic error on corneal astigmatism, using the J0 and J45 components of the astigmatism. Results. We obtained a statistically significant regression relationship between the corneal (C) and refractive (R) astigmatism for both J0 and J45 components, namely, RJ0 = 1.07 × CJ0 − 0.28; and RJ45 = 1.46 × CJ45 …
Predictive chromosomal clusters of synchronous and metachronous brain metastases in clear cell renal cell carcinoma
2014
Synchronous (early) and metachronous (late) brain metastasis (BM) events of sporadic clear cell renal cell carcinoma (ccRCC) (n = 148) were retrospectively analyzed using comparative genomic hybridization (CGH). Using oncogenetic tree models and cluster analyses, chromosomal imbalances related to recurrence-free survival until BM (RFS-BM) were analyzed. Losses at 9p and 9q appeared to be hallmarks of metachronous BM events, whereas an absence of detectable chromosomal changes at 3p was often associated with synchronous BM events. Correspondingly, k-means clustering showed that cluster 1 cases generally exhibited low copy number chromosomal changes that did not involve 3p. Cluster 2 cases ha…
Array comparative genomic hybridization analysis of chromosomal imbalances and their target genes in gastrointestinal stromal tumors.
2007
Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the gastrointestinal tract. The tumors characteristically harbor KIT or PDGFRA mutations, and mutant tumors respond to imatinib mesylate (Glivectrade mark). Chromosomal imbalances resulting in altered gene dosage are known to have a role in the molecular pathogenesis of these tumors, but the target genes remain to be identified. The present study aimed to identify some of these genes. In total, 35 GIST samples were screened for chromosomal imbalances by array-based comparative genomic hybridization. A cDNA array was used to define the minimal common overlapping areas of DNA copy number change. Eight confirmative, …
Cytogenetic findings in secondary acute nonlymphocytic leukemia
1992
Abstract We here report the results of cytogenetic studies carried out in eight patients with acute nonlymphocytic leukemia developed after primary neoplasias. In seven of the reported cases, clonal chromosome aberrations were found, some being specific of de novo acute nonlymphocytic leukemia (ANLL). Numerical abnormalities were detected, such as the total monosomy of chromosomes 5, 7, 21, trisomy of chromosomes 8, 11, 15, and duplication of chromosome Y. Structural changes were also observed: a del(12)(p12), a del(16)(q22), the translocations t(3;5)(p21;q35),t(3;7)(p21;q35), and t(12;14)(p12;q32) and other changes involving chromosome 8. The finding of a hypertetraploid karyotype with com…
Chromosomal abnormalities in Waldenström's macroglobulinemia
1992
We report the results of cytogenetic studies of direct bone marrow (BM) preparations and of short-term BM and peripheral blood (PB) cultures from 17 patients with Waldenström's macroglobulinemia. We noted clonal chromosome changes in 10 patients. Abnormalities affected chromosomes X, Y, 2, 4, 5, 15, 16, 18, 19, 20, 21, and 22; in particular, chromosomes 2, 4, and 5 were involved in structural changes: a homogeneously staining region [hsr(2)], a der(4)t(4;?)(q32;?), and a 5q+. The other chromosomes were involved in numerical abnormalities, such as pseudodiploidy (a 46,X,-X,+15 clone), loss of chromosome Y, and monosomy of chromosomes 16, 18, 19, 20, 21, and 22. Nonclonal chromosome rearrange…
Intrasubject repeatability of corneal power, thickness, and wavefront aberrations with a new version of a dual rotating Scheimpflug–Placido system
2014
Purpose To determine the intrasubject repeatability of a recently introduced dual-camera rotating Scheimpflug–Placido imaging system (Galilei G4) in determining corneal thickness, power, and wavefront aberrations in young healthy subjects. Setting University of Valencia, Valencia, Spain. Design Prospective evaluation of diagnostic technology. Methods The study comprised right eyes of 25 subjects aged 20 to 40 years with a spherical equivalent ranging from −4.25 to +1.00 diopters. The central corneal thickness, thinnest point value and location, anterior and posterior surface curvatures, total corneal power, and corneal wavefront aberrations were measured for distance vision using the dual S…
Repeatability of whole-cornea measurements using an anterior segment imaging device based on OCT and Placido-disk
2017
Current advances in refractive surgery require high accuracy of corneal measurements. We aim to evaluate the repeatability of topographic measurements using an integrated Placido disk - OCT device.Thirty right eyes of thirty healthy and young subjects were included. The topographic parameters of simulated keratometry, asphericity, minimum pachymetry, white-to-white distance, spherical aberration and corneal elevation were studied. Three measurements were taken by the same observer using the Visante omni device. The coefficient of repeatability (CoR), coefficient of variation (CoV) and intraclass correlation coefficient (ICC) were calculated to assess the repeatability. The Bland-Altman grap…
Precision of a commercial hartmann-shack aberrometer: limits of total wavefront laser vision correction.
2012
Purpose To assess the intrasession and intersession precision of higher-order aberrations (HOAs) measured using a commercial Hartmann-Shack wavefront sensor (Zywave; Bausch & Lomb) in refractive surgery candidates. Design Prospective, experimental study of a device. Methods To analyze intrasession repeatability, 1 experienced examiner measured 30 healthy eyes 5 times successively. To study intersession reproducibility, the same clinician obtained measurements from another 30 eyes in 2 consecutive sessions at the same time of day 1 week apart. Results For intrasession repeatability, excellent intraclass correlation coefficients (ICCs) were obtained for total ocular aberrations, total HOAs, a…