Search results for "Optical coherence"
showing 10 items of 223 documents
Characterization of micro-fibrillated cellulose fiber suspension flow using multi scale velocity profile measurements
2017
Rheological properties and boundary layer flow behavior of Micro Fibrillated Cellulose (MFC) suspended in water was studied using a novel velocity profiling rheometric technique. The method is based on measuring stationary velocity profiles of fluid flow in a straight tube simultaneously by Doppler Optical Coherence Tomography (DOCT) and by Ultrasound Velocity Profiling (UVP). The high resolution DOCT provides velocity profiles near the transparent tube wall, while UVP yields corresponding information in the interior parts of the flow. The data from the two instruments is combined into a comprehensive velocity profile including both the thin boundary layer near the wall and the interior par…
OCT applications in contact lens fitting
2022
Optical Coherence Tomography (OCT) is a noninvasive, high-speed, high-resolution imaging technology based in the Michaelson interferometry. A near-infrared light beam is used to register the intensity variations for the light backscattered on each sample layer. Due to the high repeatability on corneal measurements, spectral domain OCT (SD-OCT) is the gold standard when talking about in vivo, non-invasive anterior segment imaging. Changes in the morphology of various ocular surfaces such as the cornea, conjunctiva, limbus or tear film with soft (SCL), rigid, corneal or scleral lens (SL) wear can be described by OCT measurements. For instance, evaluation of the corneoscleral region is essenti…
Retinal nerve fibre layer thickness measurements in myopia by optical coherence tomography
2014
Aim: Our study aimed to evaluate through OCT, in a homogeneous group of subjects with various degrees of myopia, the macular thickness and that of the RNFL with the purpose of highlighting the possible presence of a correlation between their impairment and the degree of myopia. Material and Methods : 83 students of the Faculty of Medicine were considered, distinguished into 4 groups, 3 of them according to the degree of myopia and the last group (control group) was made of emmetropic subjects. Each subject was submitted to a determination of visual acuity and refractive defect and evaluation of the thickness of the macular fibres and of the retinal nerve fibre layer (RNFL) through OCT (Stra…
Demonstration of remote optical measurement configuration that correlates to glucose concentration in blood
2010
An optical approach allowing the extraction and the separation of remote vibration sources has recently been proposed. The approach has also been applied for medical related applications as blood pressure and heart beats monitoring. In this paper we demonstrate its capability to monitor glucose concentration in blood stream. The technique is based on the tracking of temporal changes of reflected secondary speckle produced in human skin (wrist) when being illuminated by a laser beam. A temporal change in skin’s vibration profile generated due to blood pulsation is analyzed for estimating the glucose concentration. Experimental tests that were carried out in order to verify the proposed appro…
Combined multi-wavelength laser speckle contrast imaging and diffuse reflectance imaging for skin perfusion assessment
2019
Abstract Laser Speckle Contrast Imaging (LSCI) is a powerful low-cost method for visualization of flow, microcirculation and blood perfusion. Due to the fact that diseased and healthy tissues has different blood perfusion, LSCI can be a perspective tool for cancer diagnostics and discrimination between different types of tissues. Previously, multispectral diffuse reflectance imaging method for melanoma diagnostics has been introduced. In this work, multi-wavelength (532-, 655- and 850- nm) LSCI technique combined with hyperspectral camera and diffuse reflectance imaging method will be used for assessment of tissues with different skin perfusion properties. An in vivo experiment with occlusi…
Immune-Mediated Desquamative Gingivitis and Optical Coherence Tomography Diagnostic Patterns: Clinical Implication from a Systematic Review
2021
Desquamative Gingivitis (DG) comprises heterogeneous clinical manifestations of numerous immune-mediated muco-cutaneous diseases. Optical Coherence Tomography (OCT) has been proposed as a valuable diagnostic support even if, to date, there are no standardized OCT-diagnostic patterns applicable to DGs. A systematic review was performed to detect existing data on in vivo OCT diagnostic patterns of the most common immune-mediated DGs (i.e., pemphigus vulgaris, mucous membrane pemphigoid and oral lichen planus). It has been found that OCT exhibits specific patterns that address the diagnosis of DG by pemphigus vulgaris (i.e., intraepithelial unilocular blister, reduced epithelial thickness, pre…
A MEMS array-type Mirau interferometer for swept-source OCT imaging with applications in dermatology
2017
In the frame the European project VIAMOS (www.viamos.eu) we developed a microsystem based on Mirau interferometry and applied for optical coherence tomography (OCT) imaging of living tissues. The objective is to benefit from advanced MOEMS technologies, enabling a new generation of miniature and low-cost instruments using the concept of the swept-source OCT (SS-OCT) microsystem based on spectrally tuned Mirau interferometry, into which a doublet of microlens matrices (4×4) and a wafer of movable reference mirrors are included, building the active Mirau interferometer.
Evaluation of a Completely Robotized Neurosurgical Operating Microscope
2012
BACKGROUND Operating microscopes are essential for most neurosurgical procedures. Modern robot-assisted controls offer new possibilities, combining the advantages of conventional and automated systems. OBJECTIVE We evaluated the prototype of a completely robotized operating microscope with an integrated optical coherence tomography module. METHODS A standard operating microscope was fitted with motors and control instruments, with the manual control mode and balance preserved. In the robot mode, the microscope was steered by a remote control that could be fixed to a surgical instrument. External encoders and accelerometers tracked microscope movements. The microscope was additionally fitted…
NEURODEGENERATION IN MULTIPLE SCLEROSIS: COMPARISON BETWEEN CLINICAL, NEUROPSYCHOLOGICAL, MRI,AND OPTICAL COHERENCE TOMOGRAPHY PARAMETERS
2015
BACKGROUND AND OBJECTIVE Optical Coherence Tomography (OCT) enables rapid, non-invasive in vivo measurement of retinal nerve fiber layer (RNFL) thickness, reflecting axonal density within the optic nerve. There is still lack of concordance about the use of OCT in clinical routine as a surrogate measure of brain atrophy. Objective: To investigate the role of OCT as possible predictor of disability, cognitive impairment and neurodegeneration in Multiple Sclerosis (MS). MATERIAL AND METHODS We recruited patients affected by MS according to validated criteria at the Neurological Department of the University of Palermo. Patients performed Stratus OCT- 3 Zeiss to assess RNFL and GCS measurements.…
High myopic patients with and without foveoschisis: morphological and functional characteristics.
2020
Purpose: Myopic foveoschisis (MF) is characterized by the splitting of the retinal layers in the fovea of patients with high myopia (HM). MF may progress into foveal detachment or macular hole formation with consequent loss of central vision. The aim of this study is to investigate morphological and functional changes of the macular region in myopic subjects with and without foveoschisis. Design: Observational, cross-sectional, comparative study. Methods: Forty-eight patients with HM and 24 healthy controls were evaluated by spectral domain-optical coherence tomography (SD-OCT), multifocal electroretinography (mfERG) and microperimetry (MP-1) tests to assess macular thickness, functionality…