Search results for "Partial coherence"
showing 10 items of 12 documents
Reproducibility of optical biometry using partial coherence interferometry: intraobserver and interobserver reliability
2001
Abstract Purpose: To evaluate the intraobserver and interobserver variability in axial length (AL), anterior chamber depth (ACD), and corneal radius measurements using an optical biometry instrument based on partial coherence interferometry (PCI). Setting: Johannes Gutenberg University, Mainz, Germany. Methods: In this observational case series and interobserver reliability trial, 30 healthy, emmetropic to moderately myopic eyes of 15 volunteers were evaluated. The AL, ACD, and corneal radius were measured 20 times in 10 eyes by 1 observer to evaluate the intraobserver variability. To evaluate the interobserver variability, the measurements were taken in 20 eyes by 5 different observers. Me…
Comparison of Immersion Ultrasound, Partial Coherence Interferometry, and Low Coherence Reflectometry for Ocular Biometry in Cataract Patients
2011
PURPOSE: To compare ocular biometry parameters measured with immersion ultrasound, partial coherence interferometry, and low coherence reflectometry in cataract patients. METHODS: Measurements of axial length and anterior chamber depth were analyzed and compared using immersion ultrasound, partial coherence interferometry, and low coherence reflectometry. Keratometry (K), flattest axis, and white-to-white measurements were compared between partial coherence interferometry and low coherence reflectometry. Seventy-eight cataract (LOCS II range: 1 to 3) eyes of 45 patients aged between 42 and 90 years were evaluated. A subanalysis as a function of cataract degree was done for axial length and…
Comparison of partial coherence interferometry and ultrasound for anterior segment biometry.
2008
To assess the performance of a partial coherence interferometry (PCI)-based device for the determination of anterior segment biometry.Clinica Centrofama, Cartagena, Murcia, Spain.Central corneal thickness (CCT), anterior chamber depth (ACD), and lens thickness (LT) were measured with the ACMaster PCI anterior segment biometer and an Echoscan US-1800 ultrasound (US) biometer/pachymeter with and without cycloplegia. To determine the precision of the instruments, the same examiner took 30 consecutive CCT, ACD, and LT measurements in a single subject under the same conditions and with and without cycloplegia. The same measurements were performed in additional subjects.Twenty-one eyes (16 subjec…
Agreement of predicted intraocular lens power using swept-source optical coherence tomography and partial coherence interferometry
2021
PURPOSE To analyze the agreement of the predicted intraocular lens (IOL) power obtained with ANTERION, IOLMaster 700 and Pentacam AXL biometers. METHODS We calculated the monofocal and trifocal IOL power using the SRK/T, Haigis, Barrett Universal II and Hoffer Q formulas for 106 eyes. IOL power agreement between devices was evaluated using the Bland-Altman method. RESULTS We found significant differences between biometers comparisons (p 0.05), with the same outcomes for medium- and long-eyes. No significant differences were found using the SRK/T, Haigis, or Hoffer Q formulas for short-eyes (p > 0.1). However, Barrett Universal II formula produced significant differences (p < 0.05) and thes…
Graphic representation of data resulting from measurement comparison trials in cataract and refractive surgery.
2003
* BACKGROUND AND OBJECTIVES: The evaluation of new diagnostic measurement devices allows intraindividual comparison with an established standard method. However, reports in journal articles often omit the adequate incorporation of the intraindividual design into the graphic representation. * PATIENTS AND METHODS: This article illustrates the drawbacks and the possible erroneous conclusions caused by this misleading practice in terms of recent method comparison data resulting from axial length measurement in 220 consecutive patients by both applanation ultrasound and partial coherence interferometry. * RESULTS: Graphic representation of such method comparison data should be based on boxplots…
Instabilité modulationnelle incohérente
2006
Dans cet article, nous presentons une etude theorique et experimentale de l'instabilite de modulation d'une onde partiellement coherente. Les experiences ont ete realisees dans une fibre optique standard au voisinage de 1320 nm. En particulier, et en comparaison avec le cas coherent, nous observons que l'utilisation d'une onde incoherente conduit a une augmentation significative du gain et de la frequence de modulation.
Using Partial Coherence and Digital Holography for 3D Imaging and Profile Extraction
2008
Two approaches for 3D imaging are presented. At first we use partial coherence of the light source and in the second we compute the unwrapped phase by illuminating the object from several slightly different angles.
Suppression of phase ambiguity in digital holography by using partial coherence or specimen rotation
2008
In this paper we present two approaches for extracting the surface profile as well as obtaining 3D imaging of near field objects by usage of partial coherence and digital holography. In the first approach a light source with given temporal partial coherence is used to illuminate a near field object. The reflected light is interfered with the reference source. By computing the local contrast of the generated fringes one may estimate the 3D topography and the profile of the object. This approach extracts the 3D information from a single image, and its accuracy does not depend on triangulation angle like in fringe projection methods. The second approach is tomography based. There we illuminate…
Agreement between 2 swept-source OCT biometers and a Scheimpflug partial coherence interferometer
2020
PURPOSE To evaluate the agreement between different parameters obtained with 2 swept-source optical coherence tomography (SS-OCT)-based biometers and 1 Scheimpflug camera with partial coherence interferometry (PCI). SETTING Single center, Oftalvist, Alicante, Spain. DESIGN Prospective case series. METHODS Biometry was performed in 49 eyes using 3 optical biometers: ANTERION SS-OCT, IOLMaster 700 SS-OCT, and Pentacam AXL PCI. Keratometry (K), J0 and J45 vectors, anterior chamber depth (ACD), central corneal thickness (CCT), white-to-white (WTW), lens thickness (LT), and axial length (AL) were measured with each device. Bland-Altman analysis was applied. RESULTS This study comprises 49 eyes o…
Determining postoperative anterior chamber depth
2003
Abstract Purpose: To compare measured and calculated postoperative anterior chamber depths (ACDs). Setting: Department of Ophthalmology and Institute of Medical Physics, University of Vienna, Vienna, Austria, and Department of Ophthalmology, University of Mainz, Mainz, Germany. Methods: The postoperative ACD was measured in 189 pseudophakic eyes using a laboratory prototype of partial coherence interferometry (PCI). In 6 intraocular lens (IOL) groups, the mean ACD was calculated by ray tracing based on the best-known A-constants of the SRK formulas. In addition, for each IOL type, each measured ACD was compared with a value calculated using the individual spherical equivalent of the postope…